PRODUCTS/SERVICES LISTING AISCO SYSTEMS INC. ABB INDUSTRIE AG #603 Zurich, Switzerland
ADVANCED DYNAMICS CORP. LTD. #440 SI. Bruno, Quebec, Canada
AGA GAS, INC. #116,118 Cleveland, Ohio
AIR LIQUIDE AMERICA CORP. #532 http://www.airliquide.com Walnut Creek, Califomia Air Liquide America, part of the world's largest industrial gas company, offers oxy-fuel burners, high oxygen for copper convertors (in partnership with Union-Miniere), process modelling, and the patented SPAL process using liquid argon inerting for high quality melts. The group, a full service supplier will also feature its large on-site oxygen plants, cylinders and hard goods products. Air Liquide America is becoming the industry's preferred partner through creative solutions.
AIR PRODUCTS & CHEMICALS #324 Allentown, Pennsylvania Air Products and Chemicals, Inc. is a leading worldwide supplier of industrial gases and related technology. At TMS '97, the company will feature its broad range of products and services that help customers increase their productivity and meet mounting environmental challenges. Forexample, Air Products will highlight its Ez-Fire™ Oxygen Combustion Systems for rotary, reverb, and sweat fumaces that enable customers to increase productivity, reduce melting costs, and reduce bag house loadings. In operation at over 40 customer locations, the systems are easy to install and require minimal capital investment. The company also will showcase its ndustrial i gas supply capabilities, ranging from on-site generation to cylinder supply, as well as ongoing applications and engineering support.
#417,516 Burlington, Ontario, Canada Aisco Systems Inc. provides engineered machinery, systems and integrated process solutions for aluminium smelter rodding rooms, casthouses and copper tankhouses. Rodding Room - Aisco is a technical leader in supplying rodding room equipment, from anode loading/unloading, butt bath cleaning systems, butt and thimble presses and rod reconditioning equipment to anode and rod mating stations and iron pouring systems. Casthouse - Aisco provides slabfT-barlbiliet sawlines with fully automated material handling. Product inspection and packaging equipment is available to suit customer requirements. Our automated foundry ingot casting, stacking and strapping equipment is designed and built for heavy duty use in primary and secondary facilities. Copper Tankhouse - Aisco produces copper anode preparation and tankhouse machinery and solutions to yourtankhouse problems. Our unique carousel design provides high production rates and efficient use of plant space. Please call Aisco to discuss your equipment requirements or visit us at booth #417/516 at the 1997 TMS Show.
ALAN WORSWICK (ENGINEERING) LTD. # 135 http://www.worswick.com Blackburn, England Alan Worswick (Engineering) Ltd. wasformed in 1960 and initially specialized solely in the design and manufacture of rotary - ingot casting machines. Progressing from this they moved into the field of automatic ingot handling with the conveyors, cooling baths and ingot stacking machines to provide a complete, automated ingot production system. As time passed, they received many enquiries and subsequent orders for specialized machines for the non-ferrous metal industry including billet stackers, anode producing machines, block/sow casters, lead dross removal machines and automated gravity die casting machines, in fact equipment to produce everything from zinc balls to aluminium engine blocks. To date, Worswick have built more than 300 casters and 100 stackers and would be pleased to discuss your requirements at the 1997 TMS Annual Meeting &Exhibition at Orlando, at our Booth No. 135.
Oaisco
-
Fully automated aluminium billet sawline:
ALAN WORSWICK (ENGINEERING) LTD.
ALCAN INTERNATIONAL LTD. #230,232 Montreal, Quebec, Canada
ALCOA #225 Alcoa Center, Pennsylvania
ALMEQ NORWAY A.S.
AIR I. PRODUClS t.aT
#501,503 Oslo, Norway
ALMEX, USA INC.
AIR PRODUCTS &CHEMICALS
#605,607 Long Beach, California
AISCO SYSTEMS, INC.
Al
ALTEK INTERNATIONAL INC.
ANKER-CAST
#421, 423, 520, 522 http://www.altek-dross.com Exton, Pennsylvania ALTEK Intemationallnc. is the North American representative of HERTWICH ENGINEERING GmbH, manufacturer of Continuous Homogeni· zation, Horizontal Casting and Integrated Sawing Systems. Altek is also a designer, manufacturer and supplier of aluminum dross recycling sys· tems. "THE PRESS," the patented device for treating hot dross, maximizes the in·house recov· ery of metal and prepares the remaining dross for maximum recovery from the dross recycler. The system is environmentally clean, in most cases eliminating the need for a baghouse. "THE PRESS" is safe, easy to operate, has fast cooling cycles and low operating and maintenance costs. "THE PRESS" does not utilize compressed air, water or other costly gas additions. ALTEK offers additional recycling stems that treat the cooled dross. ALTEK also has ajOint venture agreement with DIDION Manufacturing Co., manufacturer of Dross Tumbling equipment for the aluminum recycling industry. The cold processing technology, "THE TUMBLER", further treats the dross, increases the in· house recovery, generates saleable by· products and other smaller fractions that require subsequent handling or land filling. AnotherTUM· BLER system treats salt cake, recovering sub· stantial amounts of metal.
#619,621 Mississauga, Ont, Canada
IE 0D0DOc;J HERlWlCH ENGINEERING
Mllchln." und IndUllrleanllgln O'...... t'lof
ALTEK INTERNATIONAL, INC.
ALU-CUT INTERNATIONAL #602,604 Katy, Texas
ALUMINIUM TODAY #722 Redhill, Surrey, England
APPLIED RESEARCH LABORATORIES DIVISION OF FISONS INSTRUMENTS #129 Beverly, Massachusetts ARL is the world leader for instrumentation that determines the chemical composition of alumi· num alloys. The instruments are ideal for any operation from foundries to incoming materials control. Designed for stability, reliability, and perfor· mances, ARL Models 2460 and 3460 Metals Analyzers provide cost effective analysis and turn·key operations. The ARL Model 4460 Metals Analyzer com· bines leading edge technology, a current con· trolled source (CCS) and time resolved spectros· copy (TRS), to significantly improve all areas of aluminum analysis. All of ARL's Metal Analyzers embody critical success factors to meet the quality demands of today's market. • Unmatched Stability and Reliability • World Class Factory Calibration • Speed and Accuracy • Most Advanced Software Technology • Advanced TechnicaVService Support ARL is dedicated to customer satisfaction by providing a distinct performance and value ad· vantage for all quality operations.
ASBURY FLUXMASTER OF UTAH, INC. #521 http://www.asbury.com Rodeo, California Asbury Fluxmaster, adivision of Asbury Car· bons, produces and markets a line of high quality consumable foundry materials. These materials include awide range of aluminum fluxes, titanium products, degassers, coatings, and injection fluxes. Asbury Fluxmaster was added in 16 years ago as a division to our 100+ year old parent company to expand our historic strength into the nonferrous metals market. Asbury Fluxmaster offers customers the ben· efits of a professional, knowledgeable staff, a proven line of products, custom packaging options, and quality customer service. Asbury Fluxmaster products are marketed and sold in the United States through our network of Territory Managers and distributors. Fluxmaster also has international agents and sales in over 20 countries. Call Asbury or stop by booth #521 to give our professional staff the opportunity to impress you. Our telephone number is (510) 799-3636 and our fax is (510) 799-7460 or visit our web page at http://www.asbury.com.
Asbury Fluxmaster FLUX & AllOY INJECTION SYSTEMS
TITANIUM-BORON GRAIN REFINERS
FLUX ES·DEGASSERS
INJECTION FlUXES
ENVIRONMENTAUY SAFE UNIFlUX
-,...
.·.·ASBURy ASBURY FLUXMASTER
ATAN-SISTEMAS DE AUTOMACAO #529,531,533,628,630,632 Belo Horizonte, Minas GeraiS, Brazil ATAN is a Brazilian automation engineering company situated in Belo Horizonte, the third largest city in Brazil. Atan has established a solid reputation for supplying the Brazilian market with automation solutions for complex process control problems which is a blend of technology, skills, experience and flexibility. We have been acting as a systems integrator and automation products developer. In the 1997 TMS Meeting, we will be presenting the latest SCORE release -which is a comprehensive automation solution oriented to control and supervision of aluminum smelter lines. In Brazil, we are the leader supplier for smelters automation, and since 1987, we implemented the SCORE system in companies like ALBRAS, ALCAN, and CSA. In 1996, ATAN signed a contract to implement the SCORE system in HUTA ALUMINIUM KONIN SA, in Poland, Sy the end of this year, the SCORE system will control more than 1400 pot cells all overthe world.
BArAN AUTOMATION SYSTEMS
ATAN-SISTEMAS DE AUTOMACAO
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B&P PROCESS EQUIPMENT AND SYSTEMS #125 Saginaw, Michigan B&P Process Equipment and Systems, LLC. (Manufacturers of Baker Perkins Machinery) i s a supplier of specialized process equipment for the production of carbon pastes, energetic materials, plastics, industrial chemicals, solid waste pyrolistion, and chemical separations. In 1903, B&P supplied batch anode and cathode paste mixers for the first commercial aluminum smelter in the United States. As smelter began to increase ins ze, i B&P evolved the initial tilt-type unit into a f xi ed bowl, bottom discharge unit specifically for the production of carbon pastes, with the first unit being installed in 1935, which is still in service today. As the industry requirements continued to grow, B&P increased our offering in 1952 with the continuous carbon paste Polyneader® , which is being displayed at the 1997 TMS Annual Meeting Exhibition.
B&PPROCESS EQUiPrvENr ~DSYS1EMS
B&P PROCESS EQUIPMENT AND SYSTEMS
BETZIDEARBORN WATER MANAGEMENT GROUP #806, 808, 810 Trevose, Pennsylvania BetzDearborn Water Management Group markets engineered water treatment programs that use customized products and value-added services in solving problems associated with boilers, cooling towers, and influent and effluent systems in a wide variety of industries, commercial establishments, and institutional facilities. Hundreds of BetzDearborm researchers simulate the operation of a water system, troubleshoot, and isolate problems in one of the largest water research facilities in the world.
ft !!,:~~:!orn BETZ WATER MANAGEMENT GROUP
BLASCH PRECISION CERAMICS #623 Albany, New York
BLOOM ENGINEERING CO., INC. #814 Pittsburgh, Pennsylvania Bloom Engineering Company, Inc. designs and manufactures bumers, controls and combustion equipment for the aluminum, other nonferrous and ferrous industries.
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Representatives from Bloom will be available to discuss Bloom'scomplete burner line including Fuel Energy, highintensity and regenerative burners as well as their application to various furnaces used in the industry. Featured at the show will be Bloom's recently introduced Ultra 3 Low NO,™ flame less bumers, Measured NO, values from Bloom's complete line of Ultra Low NO,TN regenerative and conventional burners are the lowest in the industry.
BMI·FRANCE REFRACTORIES #716, 718 Carnegie, Pennsylvania BMI-FRANCE Refractories has a complete line of products to service the aluminum industry. Our Alu-One line of non-wetting materials has been proven to provide excellent resistance to molten aluminum penetration. This line consists of non-wetting low-cement vibratable and pump castables, insulating castables, plastics, gunning materials and brick to effectively construct and maintain all molten aluminum melting/holding furnaces and ladles. BMI-FRANCE SurShot Process Technology blends the properties of low-moisture and lowcement castables. The resultant wet-mix is processed through a pneumatic pump and specially designed shotcrete nozzle for placement. The SurShot process reduces equipment downtime and increases installation reliability.
LiMCA II systems are anovel technique for the in-line monitoring of inclusions inaluminium melts. They provide real-time data on the total inclusion content of the melt, as well as the distribution of particle sizes, i nthe range of 20 to 300 micrometers. The PoDFA technology consists in the metallographic analysis of aporous disk through which a sample of mel! has been filtered. I! provides a measurement of the total inclusion content, broken down by types of particles. AISCAN hydrogen analyzers define the state of the art in the direct measurement of hydrogen dissolved in l quid i a ul minium. They are easy-touse, portableinstruments which provide objective and reproducible measurements at very competitive costs. Three different models are available to suit your needs.
BOMEM Hartmann&Braun
BNZ MATERIALS, INC.
#241 http://www.ceramics.com/bnz/ Littleton, Colorado BNZ Materials, Inc. consists of two businesses which are appropriate to the metalsindustry. The Zelienople, Pennsylvaniaplant manufactures/markets Insulating Firebrick and complementary refractory products such as mortars, aggregates, castables and calcium silicate block. Insulating Firebrick are used in a variety of applications in the metals industry, from carbon baking fumaces to melting and holding fumaces. The Billerica, Massachusetts plant manufactures a line of calcium silicate boards under the Marinite18 trademark. They are machined into various parts for conveying, containing, and forming aluminum,lead, zinc,tin and other non-ferrous metals. These parts include spouts, floats, launders, distribution plates, head boxes, baffles, headers, tips, rings, distribution boxes, stoppers, basins, snouts, orifice plates, hot top and ingot mold liners as well as parts in the metal handling and casting systems of many casting machines. See page A19
BOMEM,INC. #229, 231 Quebec, Canada Bomem offers advanced analytical instruments for the characterization of aluminium melts.
BOMEM, INC.
BORGESTAD FABRIKKER AS #640 Porsgrunn, Norway
BUSSA.G.
#322 Pratteln, Switzerland BUSS A. G., Basel, Switzerland are the leading supplier of Anode-Paste production lines. In view of the present situation at the world primary aluminium market it is very obvious that new ideas and methods are required for improving the cost benefits. Small things can be important and can make or break the business. Consequently, BUSS A. G. has introduced the inline BUSS-Tandem System for mixing and kneading of the paste for prebaked anodes, as well as under consideration of the renaissance of the Russian aluminium industry, also the improved production of Soederberg-paste with the dry-process. Do not waste your cash, contact us at our booth or elsewhere. We are pleased to negotiate with any interested party the tailor-made possibilities for improving the production of anode paste, either with existing or new installations. Our knowledge is your cost benefit. See page A19
CARGill, INC. #600 Minneapolis, Minnesota
Consolidated Ceramic'steam of sales, marketing and technical personnel provides unparalleled service to the aluminum industry; we invite you to come and meet us.
COBALT DEVELOPMENT INSTITUTE #633 Wickford, Essex, United Kingdom THE CD.I. is the world association for all those engaged in cobalt's multi-faceted world. Production, extraction, refining, converting, chemical preparation, trading. It also covers the many enduses from superalloys to catalysts, battery additions, cemented carbides, diamond tooling, tyre adhesives, paint driers, hard facing alloys, dental alloys, and many others. The C.D.I. will be exhibiting information on many of these subjects and staff will be available to answer your questions and supply further information. Afull range of C.D.l.literature will also be available.
CONSOLIDATED CERAMIC PRODUCTS, INC. #321 ,323 Blanchester, Ohio For 40 years, Consolidated Ceramic Products has been of service to the aluminum industries worldwide. An innovative manufacturer and marketer of ceramic based products, it maintains operations in Cincinnati, Ohio and Sheffield, England with distribution points around the world. CCPI products and services for temperature measurement, chemical modification and physical transport of molten aluminum include: • Ceramic coated alloyed cast iron thermocouple protection tubes. • Mineral insulated and plasma beaded, ceramic insulated thermocouple elements. • ACCUTIP Dipping thermocouples. • Ceramic coated fluxing pipe, available with gas diffusing media. • Ceramic coated alloyed cast iron riser stalk tubes. • Vacuum formed fiber tapout cones with matching cast iron plugs. • Radiant and immersion heaters and replacement elements. • Thermal profiling services for aluminum melting, holding and heallreatingfumaces. • High technology SIALON thermocouple protection tubes, level sensors, riser stalk tubes, heater tubes, and special shapes. • Aluminum Titanate riserstalktubes,sprues and break rings. • Custom cast iron castings such as transfer troughs, air and water cooled pig molds, flow devices, and crust plungers. • Impellers, shafts, rotors, nozzles, baffles and pre-cast liners for degassing and filtration systems.
CONSOLIDATED CERAMIC PRODUCTS,INC.
DIXON TICONDEROGA COMPANY #436 Lakehurst, New Jersey The Dixon Ticonderoga Company is a principal supplier of graphite products for induslrial purposes. Our 169 years of working with this form of carbon has provided us the experience and knowledge to meet our customers' diverse requirements and ever-changing needs. Dixon Graphokotes R offer a wide choice of lubricants for the aluminum, copper, and zinc industries. Semi-aqueous, synthetic, VM&P naptha and solvent binder formulations are available in a range of viscosities. Our graphite lubricants are formulated to provide efficient and effective lubrication in difficult environments. Plan to visit our display booth and take advantage of our technical support. See our product line of roll sheet casting, billet casting, extrusion and permanent mold casting graphite lubricants.
rmn~~ft. .
lWlJ.,IAvn
ERICO, INC. #700, 702 CLeveland, OH Erico personnel will be demonstrating the CADWELL Process. The CADWEL~ Process is a method of making welded electrical connections of aluminum to aluminum,copper to copper and copper to steel in which no external sources of heat such as electricity or gas are required. The CADWELDI Process is based on the reaction of granular metals which when reacted produce a molten metal. This reaction, which is completed in seconds, takes place in a graphite crucible. The liquid metal flows from this crucible section into amold section where it meets the end of the conductor to be welded. The temperature of the molten metal is sufficient to fuse the metal of the conductors and results in awelded molecular bond. Welding alloys exist for aluminum, copper and copper to steel connections.
ESM SOFTWARE #540 http://www.esm-software.com Hamilton, Ohio ESM Software, adeveloper and distributor of materials science software, will demonstrate version 3.0 of TAPP, adatabase of thermophysical properties of materials and a collection of 2000 phase diagrams. Properties include density, expansion coefficients, elastic moduli, thermal and electrical conductivities, diffusivities, vapor pressure and thermodynamic properties. Acompanion product, MAPP, is a database access program to the ASM International Mat.DB databases of engineering alloys and polymers. Other products include ChemSage, ChemGeo, and HSC Chemistry - for calculations of complex phase equilibria, phase diagram CD-ROM's, SciGlass and Sci Polymer - material property databases with predictive algorithms, MOAT - a mineralogical database, X-ray - for attenuation, transmission and spectra calculation, plus CaRine, ATOMS, Crystal Designer and Crystal Office for display and analysis of crystalline structures.
DIXON TICONDEROGA COMPANY
DIXON TICONDEROGA
EBNER FURNACES, INC.
#541
EMS SOFTWARE
Wadsworth, Ohio
EIRICH MACHINES, INC. #325 Roselle, Illinois
FCB
#816
Givors Cedex, France
ELSEVIER SCIENCE
#812
http://www.elsevier.nl
New York, New York
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FOSECO, INC.
#311,313,315,317,410,412,414,416 Cleveland, Ohio FOSECO, INC. manufactures products and provides services for casting aluminum throughout the wor1d. Foseco's recent purchase of the SNI~business from Praxair, Inc. enables Foseco to bring afull line of products for in line processing of molten aluminum to our customers. SNIF degassing equipment and technology is recognized as the wor1d's market leader. FOSECO'S TILlT~ grain refiner is widely used for foundry ingot. FOSECO'S FIL TREX®, a sintered, phosphate-free composition, is a premium ceramic foam filter offering new advantages to our customers. Through a worldwide distributor agreement with Metaullics" Inc., FOSECO offers molten metal processing equipment such as pumps and the Metaullics Car· tridge Filter, ahigh-efficiency bonded particulate filter for critical aluminum applications. Premium refractory materials for molten aluminum filtration and casting are supplied by FOSECO as well. FOSECO can provide engineering and metallurgical services for molten aluminum processing as required by our customers. FOSECO is committed to helping improve the business performance of our customers.
GAUTSCHI ELECTRO FOURS, S.A. #222 Tagerwilen, Switzerland
GLAMA MASCHINEBAU GmbH #137 Gladbeck, Germany
W.L. GORE & ASSOCIATES, INC. #428 Elkton, Maryland GORE·TE~ membrane filter bags are a two layer filter system consisting of an microporous expanded PTFE membrane laminated to a backing support material. The efficiency of this filter media is such that even sub-micron particles are filtered at the surface of the membrane. This allows for extremely low emission rates, especially for PM10 and heavy metals. Since the membrane is very slick, it offers excellent particle release when the filter is cleaned. This allows for low operating pressure drops, even at higherthan-normal filtration velocities, which in tum allows for improvements in process draft and melt shop evacuation. GORE·TEX membrane filter bags are used in a wide variety of metallurgical processing applications. They are considered when existing control equipment is inadequate for emission any hygiene requirements. The use of these filters allows you to upgrade the performance of your system, reducing or eliminating the need for additional bag houses or operating costs.
AS
GRAPHITE ELECTRODE SALES #646 http://www.homewood.neVGES Birmingham, Alabama Graphite Electrode Sales (GES) is one of the largest importers of graphite electrodes in North America. GES markets all sizes of electrodes, and anodes as well as many specialty graphite rounds, squares, and blocks. The company offers competitive pricing, established reliability and quality, dependable delivery, as well as technical knowledge and support. GES is a major supplier of many members of the TMS and would like to invite your company to visit us at booth 646 to discuss your needs. We could save your company up to $8000.00 per truckload on your electrode needs.
GRAPHITE ENGINEERING & SALES COMPANY
#613 Greenville, Michigan Graphite Engineering & Sales Company is a customer-oriented company specializing in cutting and machining graphite products. The level of excellence we demand of our quality and service have provided Graphite Engineering with continuing success and growth. Graphite Engineering will have on hand knowledgeable Sales Engineers to answer any questions you may have. Graphite Engineering specializes in machining graphite per your specifications. Graphite Engineering will be displaying the following items: nuts and bolts brazing fixtures degassing shaft and rotor canister inserts run-out plates molds secondary billet casting rings heating elements electrodes crucibles sintering trays sintering boats Visit Graphite Engineering & Sales Company at booth # 613 to discuss your graphite requirements.
A.P. GREEN INDUSTRIES, INC.
#404,406 http://www.apgreen.com Mexico, Missouri A.P. Green Industries, Inc. is a leading producer of refractory materials for primary and secondary metal applications: EXPRESS' free-flowing, self-leveling castables for quick installation into the most intricate linings without the use of vibration. EXPRESS castables can be pumped, poured, or vibrated. Available in dense, insulating, ultra-low cement, and aluminum non-wetting versions. ALSTO~ and GREEN KLEEN non-wetting aluminum contact castables for areas exposed to molten metal. CHEMOBAR dry barrier material for reduction cell vapor barriers.
CENTURION' high-fired 45% alumina brick with excellent high temperature properties for carbon baking pit furnaces. CENTURION bnrick are available as standard or special shapes, including hte new GREENLOK system inter1ocking fluewwall and headwall shapes. UNACASre pre-cast shape technology for furnace construction, metal transfer systems, and other problem-solving applications_ GREENGUN phosphate-bonded gunning plastics for furnace construction, and hot-gunned or COld-gunned maintenance on the fly.
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APGreen A.P. GREEN INDUSTRIES, INC.
HARBISON·WALKER REFRACTORIES #800, 802, 804 Pittsburgh, Pennsylvania Harbison-Walker Refractories Company (H-W) will present a variety of new and proven products for non-ferrous furnace application designed to reduce installation time, lower production operating cost, improve metal quality and productivity. TMS attendees are invited to learn about the PNEUCRETElM System. Our new line of virtually dust-free spray refractory combines the performance advantages of monolithic refractories with the installation ease of pneumatic spraying. By eliminating the need for form casting, PNEUCRETE System products can dramatically improve furnace availability. Visitors will also find information about the time and cost-saving benefits of VERSAFLO~ lowmoisture castables. These innovative products retain outstanding physical properties at varying water contents. This allows refractory installers to pump or cast according to their needs. VERSAGUN', VERSAFLOW's companion low-cement gun mix line, will be featured along with other outstanding H-W products, including ALCO~, ALCOR~ and HARBIDE' PLASTIC 70AL. H-Wtechnical representatives will be available to answer refractory-related questions.
HEPWORTH REFRACTORIES, INC.
HI·TECH CERAMICS, INC.
#227 Franklin, Ohio
#616 http://www.ceramics.com/vesuvius Alfred, New York In today's economy with low metal prices and high overhead costs, you need suppliers who will work with you to help meet your goals. HI-TECH CERAMICS is ready to be your partner providing: • Proven high efficiency and easy to use filters. We manufacture the strongest, most thermal shock resistant, and most refractory filters on the market. • Quarterly reports on size, weight, squareness and ~ to ensure you are receiving consistent high quality product every day. • Technical services including inclusion analysis, priming rate analysis, technical training on filter usage and more! Come visit us at booth 616 at the TMS show to see and feel the quality of our product and talk with our technical representatives on the new developments in ceramic foam filters. HI-TECH CERAMICS is the quality and service leader when it comes to molten metal filtration. See page A19
HERAEUS ELECTRO·NITE CO.
HARBISON-WALKER REFRACTORIES
HENCON, B.V. #433 Ulft, Gelderland, Netherlands For more than 40 years, HENCON designs, manufactures and supplies heavy duty INDUSTRIAL MOBILE EQUIPMENT. The delivery program covers the complete range of special mobile equipment for potrooms (prebaked and Soderberg) and casthouse like: • Anode PalietTransporters • Ladle Transporters • Tapping Trucks • Vacuum Cleaners • Alumina Feeders • Vacuum Systems • Anode Covering Vehicles • Anode Briquette Feeders • Crust Breakers • Bath Cleaning Machines • Combined Feeding Trucks • Scrap Loaders • Rack Raising Trucks • Spading Machines • Pot Skimming Vehicles • Sideloaders • Box Charging Machines Recent developments, like a new design of Anode Pallet Transporters and Ladle Transporters will be shown at the TMS Exhibition.
#523,525 Philadelphia, Pennsylvania Heraeus Electro-Nite is the world's argest l producer of molten metal sensors to the iron and steel industry. Heraeus Electro-Nite has, for the past several years, devoted aportion of their R&D efforts to the primary aluminum area. As a result of these efforts, they have introduced two new sensors for the primary aluminum potline. The Postitherm AL expendable thermocouple system has been developed for direct and accurate temperature measurements in the liquidbath. The Type uS' thermocouplehas been designed to provide the potline operator with an accurate, calibrated temperature measurement every time, in less than 15 seconds. The Cry-O-Therm Sensor has been recently described as "breakthrough technology for the potline". The Cry-O-Therm Sensor utilizes a single precision thermocouple to measure both the bath and liquidus temperatures on the potline floor. Visit Heraeus Electro-Nite at Booths 523-525 to leam more about these exciting neew sensors for the potline.
HI·SCOPE SYSTEMS COMPANY #347 Closter, New Jersey HI·SCOPE SYSTEMS is the first 3·0 Image video microscope for observation and visual inspection of materials and components. Unique 360 degree rotary viewing provides superior resolution and great depth of field, perfect for quality control, failure analysis, and research development. HIS-SCOPE can be connected to Video Printer, VCR, or PC for documentation, image analysis,and measurement. Magnification range from 5X to 600X for 3-D rotary viewing and up to 2500X for straight viewing.
HI-SCOPE Systems Company (A s..bs;d;orr of WIN SYsnMS Of AMERICA CORP.)
HIGH TEMPERATURE SYSTEMS, INC. #400 http://www.HITEMP.COM Chagrin Falls, Ohio High Temperature Systems, Inc. of Chagrin Falls, Ohio is pleased to announce a revolutionary molten metal pump. This new pump is based upon the successes of the "Bulldog Series" with some exciting new features. The motor rests upon a hinged motor mount. This flip-top design allows easier removal of the shaft and impeller from the top of the pump. Heavier materials and a beefed· up shaft and impeller are standard features for an improved pump life. An optional self·cleaning control system generates automatic cleaning cycles. This mechanism reduces the need to stop the pump for cleaning. Gas injection is an available option with new benefits. A h gh i speed vortex generation at the point of gas introduction improves the disburse· ment of gas in the melt. Aspring loaded flux tube holder assures abetter fit ni to the base extension. Patentspending.
HI-SCOPE SYSTEMS COMPANY
HENCONB.V.
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HOLCAN CONSTRUCTIONS RTY LTD.
HOGANAS
REFRACTO RI ES
Revolutionary molton metal pump. HIGH TEMPERATURE SYSTEMS, INC.
HOGANAS ELOFAST AS #327 Fjellhamar, Norway HOGANAS ELDFAST AS is part of the H6ganas Eldfast group of companies originating in Sweden and dating back to the 19th century. We supply "complete packages" of refractories and acid resistant material- from design to products, contracting and service. Our fast , easy to install pot barriers, layer-andsidewall refractories. BJUF S ,DENSCAST 50, and ladle castable ALKON have been very popular in the aluminium industry for many years. Now, at last, we can meet demands to reduce pollution and harmful dust in the production environment and, at the same time cut installation costs with our unique new product DRYCAST. DRYCAST is a ready -to- use vibratable mix for electrolytic pot lining. II flows easily into all corners, forming an even smooth surface of high penetration-and slag resistance and minimal porosity in less than 30 minutes. If you are looking for better working environment, improved economy and productivity and no dust!. Welcome to HOGAN AS ELDFAST AS, Booth 327.
HOGANAS ELDFAST REFRACTORIES
HOLCANCONSTRUCTIONS PTY LTO.
#340 Queensland, Australia The Holcan Welding System offers an altemative to hand, friction or flah butt welding of anode rod stubs and adds a degree of automation at a low capital cast. Our system will outperform manual welding methods by up to 60% Simplistic design and proven reliability allows for in house maintenance to be carried out on all pieces of equipment, therefore eliminating the need for technical assistance from outside sources.
HOLTON CONFORM #512 West Howe, Boumemouth, England Hollon Conform produces machines and complete lines for the continuous extrusion of nonferrous metals. At TMS '97, Holton is presenting this technology and its applications for manufacturing aluminum solids, tubes and sheathing! cladding operations. Grain Refining Rod- Hollon's technology is used to manufacture aluminum grain refining rod. The coiled rod has no discontinuities, ahomogenous distribution of grain refining elements and a bright finish. Solid Conductors- Holton Conform extrudes solid a ul minum conductors including sector shapes. Round and Multipart Tubing- Hollon Conform is capable of direct extrusion of heat transfer tubing with consistent mechanical properties, no perforations and no surface lubricant. Reprocessing Scrap- Holton has developed technology to accept granulated aluminum, including process scrap, converting it directly into products such as steel deoxidizing rod without melling. Sheathing of Cable Cores- Holton's sheathing lines extrude seamless aluminum tubes around cable cores including fibre optic units (OPGW) and coaxial RF cables (CATV). Cladding- Holton's ines l are used for the continuous aluminum cladding of steel wires and aluminum stabilizing of superconductor cable cores. Hollon Conform and its customers are supported around the world by jts parent company, Outokumpu.
U HOLCAN ANODE ROD oIL WELDING SYSTEMS. HOLTON CONFORM
HOLTON CONFORM
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HORIBA INSTRUMENTS #635 Irvine, California Horiba Instruments manufactures a broad line of analytical instrumentation used for environmental monitoring and testing for research and QC laboratory applications. Horiba will be exhibiting its full line of particle characterization instruments including: 1. Light Scattering Particle Size Analyzers with a range of 0.02 to above 1000 microns with an optional dry powder feeder & autosampler; 2. Surface Area Analyzers with automatic calibration & zeroing for maximum repeatability & accuracy; 3. Centrifugal Sedimentation Particle Size Analyzers with a range of 0.03 to 300 microns for fast & economical sedimentation analyses and 4. Gas Pycnometers for measuring true densityl volume of particles.
Horiba's LA·910 Particle Size Analyzer with Auto Sampler HORIBA INSTRUMENTS
HOSOKAWA MIKROPUL #434 http://www.hosokawamicron.com Summit, New Jersey
HYDRO ALUMINUM AS #401 , 403,405, 407, 500, 502, 504, 506 Oslo, Norway
INDUSTRIAL PRODUCTS INTERNATIONAL (IPI)
#121 , 123 Englewood, Colorado
INNOVATIVE CONCEPTS #130 Richland, Washington The U.S. Department of Energy is sponsoring aluminum-related technologies through the Innovative Concepts program. The concepts address innovations in aluminum production, waste minimization, and fabrication. The program sponsors technologies that are novel and innovative, providing seed money, commercialization strategy guidance,and preliminary promotional assistance to introduce the concepts to industry for consideration for further development and eventual incorporation into their processes. The technologies are breakthrough technology or novel uses of
current technology and will likely require additional development and industrial guidance, but will introduce technologies that may be utilized in the future by the aluminum industry.
DEPARTMENT
i"OOYatiVC CONCEPTS INNOVATIVE CONCEPTS
JBM, INCORPORATED #124 Knoxville, Tennessee JBM, Incorporated located in Knoxville, Tennessee is a custom metal fabrication shop with design, installation, machining, welding, maintenance and consultation services. The three owners of JBM bring a total of over 90 years of experience and expertise specializing in the Aluminum Smelting Industry of North America. JBM offers 21 st century patented anode riser bar technologyto dramatically decrease millivolt drop and make your anode riser bar almost maintenance free from normal repair and pin wash. JBM offers an extensive specialized repair program for pot shells and anode riser bars to lower your operating cost and provide maximum production time. Visit our booth for additional information.
JERVIS B. WEBB INTL. CO. #234, 236 http://www.industry.net!jbwebb Farmington Hills, Michigan The Jervis 8. Webb Company has more than 75 years of experience in managing, producing, and installing large-scale integrated material handling systems. Today, Webb material handling systems move products and materials in almost every industry. The management and staff of the Jervis B. Webb Company are dedicated to maintaining our leading market position within the material handling industry by applying 100% of our efforts toward one product; custom engineered material handling systems. Webb's experience in the Aluminum Smelter industry includes furnishing material handling equipment and systems for several large aluminum companies. Because ofthe Webb Company's diversity in the material handling field, many systems have been engineered and installed in different areas of aluminum operations. Included in these installations are several Power & Free Systems for Rodding Rooms, with the most notable being for Kaiser, Alcoa, Alcan and Intalco. Power &Free systems offer many advantages for the handling operations involved in rod processing for butt return to delivery of the rodded anode.
KABERT INDUSTRIES INC.
#510 Villa Park, Illinois Since 1960 Kabert Industries Inc. has been furnishing the aluminum industry with casting supplies. Fiberglass cloth, an inexpensive and effective method of nonferrous molten metal distribution and filtration, i sspecifically woven for the aluminum industry at our plant in Lynn, Indiana. Plain, lena and twill weave cloth styles are woven to specification. Three, four or six strand yam cloths are available. Also at our Lynn facility, the cloth is cut and sewn into a variety of mini channel bags, trough socks and many other shapes. Other products available include gaskets, vacuum formed shapes, and ceramic foam filters.
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KABERT INDUSTRIES INC.
KABERT INDUSTRIES INC.
KAISER ALUMINUM #235, 237, 334, 336 Mead, Washington
KALIUM CHEMICALS #736 Mt. Pleasant, Michigan
KB ALLOYS, INC. #108, 110 Reading, Pennsylvania Since its founding in 1950 as the Kawecki Chemical Company, the name KB Alloys has been synonymous with innovation and leadership in the aluminum master alloy industry. Many of today'sindustry standards-metallurgical grain refiners, including TIBOR®,TITAL®andTICAR®, waffle ingot and rod, along with countless chemistry advances-number among KB Alloys' "industry-firsts. The company has always been guided by a philosophy of growth through a commitment to research, technical development and high-quality products. TIBOR®, TICAR® and TITAL® master alloys are used for grain refinement to deter cracking in the ingots when casting and to improve casting speeds. BORAL® master alloy is used to improve conductivity, beryllium to minimize magnesium bum off, and strontium to modify the silicon phase in foundry alloys. Hardener alloys are used to improve mechanical and physical properties. MULTIPLEX®alloys provide an effective method for simultaneous introduction of multiple alloying elements. Alloys are available in a variety of forms-ingot, bar, buttons, flake and coiled and cui rod-each designed to increase throughput, uniformity and better predictability as compared to pure elements or salts.
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Every KB Alloys product is backed by outstanding worldwide technical support and acompany-wide commitment to customer service. Experienced sales engineers, research metallurgists and trained agents can help you select the best product for your process and application. We can also provide responsive, knowledgeable answers and technical support to help you overcome problems and get the most out of the products you produce. Strategic, customer-focused manufacturing and worldwide inventories. With advanced ISO 9002 certified manufacturing facilities in both the Eastem and Westem United States, as well as in Great Britain, and strategically located customerfocused inventories, we provide fast, reliable delivery of consistently high-quality master alloys anywhere in the world.
KHD HUMBOLDT WEDAG AG #224 Cologne, Germany KHD Humboldt Wedag AG has its main fields of activities in the design and construction of plants for the base materials industries, such as cement production, minerals processing, coal preparation and nonferrous metallurgy. For the nonferrous metals industries KHD Humboldt Wedag AG supplies plant and equipment to the: • primary aluminium industry • copper, zinc and lead smelting industries and for • hazardous waste incineration For the aluminium industry, KHD Humboldt Wedag AG designs, supplies and installs • bauxite crushing and grinding systems • green anode plants • anode handling systems • rodding plants • pot line equipment and is the world-leading supplier of vibrating compactors for forming of green anodes, cathode blocks and electrodes, with more than seventy units supplied to the aluminium and carbon products industries. For the smelting of copper concentrates and other sulfide metal concentrates and for mineralisation of metallurgical residues and contaminated wastes KHD Humboldt Wedag AG supplies its CONTOP smelting cyclone technology and other standard thermal processes according to the process requirements.
KUMERA CORPORATION #435 Riihimaki, Finland Kumera Corporation is a worldwide marketer of manufactured products and engineering services. The corporation consists of three major operating divisions: The Foundry Division (Peiron Oy), The Mechanical Workshops Division (Kumera Oy), and the Kumera Technology Center, the company's engineering arm. The foundries and workshops of Kumera Corporation produce industrial castings in steel and alloys, mechanical power transmissions for a wide range of industrial and marine applications, and process machineries. The company is also a leading supplier of hazardous waste buming lines in Europe. Kumera Technology Center serves the aluminium, copper, and nickel smelters as well as metallurgical and mining industries generally, supplying main process equipment and process modemization services. For many years Kumera has been known as a supplier of equipmentfor Aluminium Anode Paste Plants. As a result of the good response from deliveries of these key items of the Paste Plants, Kumera has widened its scope of supply and is now offering a complete Anode Paste Plant for Soderberg technology and an Anode Plant for production of prebaked anodes. The plants are based on Hydro technology. Together with its partners, Kumera is able to offer an extensive range of equipment for Alumina refineries as well. More details about this package can be obtained at TMS exhibition in Orlando.
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LAROX
Larox PF Pressure Filter LAROX
LECO CORPORATION
KUMERA CORPORATION
LAROX
KHD HUMBOLDT WEGAGAG
resulting in filter availability of up to 95%. Achieve up to 94% dry cake, clearer filtrate and reduce operating costs up to 70% compared to other dewatering systems. Optional washing to produce high purity cakes is also available.
#536 hltp://WWW.larox.fi Columbia, Maryland Larox, Inc. is an international manufacturer and distributor of a complete line of pressure filtration equipment and slurry valves. Larox pressure filters have a revolutionary vertical design that offers superior dewatering performance. Operation is fully automatic. Capacity is up to 150 tons of dry solids per hour. Cycle times are as short as 6 minutes. The filters contain no continuously moving parts. Maintenance is minimal,
#636 hltp:/Iwww.lecousa.com SI. Joseph, Michigan LECO Corporation was founded in 1936 and throughout its 60 years has pioneered innovative analytical technology. This stream of product development began with the first rapid carbon determinator for the iron and steel industry and now includes a range of analytical instruments, spectrometers, and metallographic products. Over the years, the LECO name has come to be synonymous with accurate, dependable, and innovative instrumentation. LECO's comprehensive line of metallographic products includes cut-off machines, grinders, polishers, and mounting presses forsample preparation, microscopes, hardness testers, and image analysis systems. The new Spectrum System 2000 automated grinder/polishercan be upgraded, beginning with the modular base unit to which you can add the fully automated grinder/polisher head and then add another base unil. The newest addition to LECO's atomic emission spectrometer product line is the GDS-750A. It is capable of both bulk analysis and quantitative depth profile analysiS. For more information, contact: LECO Corporation, 3000 Lakeview Avenue, SI. Joseph, MI 49085-2396 USA, Phone: 616-982-5496 or Fax: 616-982-8977. hltp:/Iwww.lecousa.com.
LECO is a registered trademark of LECO Corporation.
Spectrum System 2000 Grinder/Polisher LECO CORPORATION
LEM DYNAMP INC. #333 Grove City, Ohio LEM is aglobal supplier of Current and Voltage Transducers, Instruments, probes Power Semiconductor testers, as well as Power Network Analyzers. The Metals Industries are particularly interested in DynAmp, Direct Current Management Information Systems. These give the manager accurate reports of AC to DC Energy Conversion, Current efficiency and Production Energy efficiency. At the heart of these systems are 0.1 % accurate, high current (4 kA to 500 kAI transducers. Other instruments of interest are portable units for measuring anode or cathode currents and safety related models include rectifier protection systems and the RDCMS family of power supply current distribution monitors.
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LEM DYNAMP INC.
LIGHT METAL AGE #127 hllp:/Jwww.lightmetalage.com San Francisco, Califomia For over 55 years, Light Metal Age magazine has covered primary production and semi-fabrication of light metals, primarily Aluminum and associated non-ferrous industries throughout the world. Circulation goes to smelters, rolling mills, extrusion plants, sheet rod and wire mills, foundries and die casting, anodizing, roll coating, coil coating and forging operations. Recipients are executives, presidents, general managers, plant managers, technicians, metallurgists, chemists and engineers responsible for fabrication, production and operation.
MASTER ALLOYS COMPANY LIGHT METAL AGE
LOMA MACHINE MFG. INC. #534 New Rochelle, New York
LONDON &SCANDINAVIAN METALLURGICAL CO. LTD. #318 London, England
MAERZ OFENBAU GmbH #432 Dusseldorf, Germany
MASTER ALLOYS COMPANY #326 Munster, IN Master Alloys will be exhibiting its popular 100% canned hardeners. The canned hardener is 100% element in apre-weighed, moisture-proof aluminum can. The element is not released into the aluminum until it is under the melt which negates any oxidation and results in very high recoveries. This unique way to alloy aluminum has many advantages over other forms of hardeners. Besides being pre-weighed and moisture proof as stated above, the product is easy to store; reduces inventory; easy to use; fast dissolution; high recoveries; free from contamination; and guaranteed composition. In addition to the can hardeners, Master Alloys supplies grain refiners and specialty alloys to the aluminum industry.
MBNA AMERICA BANK N.A. #620 New York, New York
McALLISTER MILLS CO. #134, 136 Independence, Virginia
MECHATHERM INTERNATIONAL LTD. #528 Kingswinford, West Midlands, England Mechatherm is a privately owned company, formed in 1973, initially supplying fumaces and associated handling gear for the aluminum extrusion, steel reheating and general heat treatment industries . The company has continually prospered, developing a world-wide clientele and expanding the product range into the specialized areas of air recirculated aluminium heat treatment and has now also accumulated SUbstantial references in aluminium melting and holding fumaces together with our own vertical D.C. casting machines. Considerable success has been forthcoming in extrusion fumaces for pre-heating brass and copper billets. The company operates aQuality System complying with IS09001 (BS5750 Part 1 /EN29001) and has been approved by Lloyds Register Quality Assurance Limited. Mechatherm will have available literature showing its product range and will be displaying photographs, posters and videos of installations. See page A19
_Mechatherm MECHATHERM INTERNATIONAL LIMITED
AID
MOLTECH SYSTEMS LTD.
MEDIA CYBERNETICS
#441 http://www.mediacy.com Silver Spring, Maryland Media Cybernetics, based in Silver Spring, Maryland, designs and markets image analysis software for end-users and software developers. Since 1981, it has held a unique position in the imaging marketplace, offering software at both the programmer's toolkit and end-user application levels. Media Cybernetics creates products that offer ease of use, creative control and are compatible with a variety of hardware and software standards. Image-Pro Plus is an image analysis software package for Windows which provides counting, sizing, statistical and image enhancement operations. It has an intuitive and consistent interlace designed to produce results quickly. Materials-Pro Analyzer, aspecialized software solution for the analysis of metals, ceramics, polymers, and other advanced materials is a 'plug-in" module for Image-Pro Plus. MaterialsPro Analyzerprovides materials science researchers wtth cost-effective and user friendly software allowing them to automate the analysis of digitized images of specific materials products. Sophisticated preprocessing routines and standard material measurements allow users to determine grain size, measure shape and orientation, gauge porosity and nodularity, and perlorm phase analysis.
MEDIA CYBERNETICS
MEGAQUIP INDUSTRIES LTD. #740 Delta, Canada
The Melauilics L-35GI gas Injection pump is used for demagging and/or degassing operalions. II feaures an open bladed impeller and is designed for low mainlainance and easy repair. METAULLICS SYSTEMS CO. LP.
MILWARD ALLOYS INC.
#424 Lockport, New York Milward Alloys, Inc. founded in 1948, is a manufacturer and worldwide supplier of aluminum based and copper based master alloys. Milward Alloys has aligned with KBM Affilips of The Netherlands to offer the aluminum industry the most complete master alloy line available in North America, combined with world class manufacturing and the finest in laboratory expertise and technical support. Materials produced include a wide variety of grain refiners, modifiers, hardeners anddegasifiers which are manufactured as 318' rod, conti-cast, ACU-STIX, and shot. All are designed for clean, easy, and precise additions foryourconvenience. Plan to visit our booth to take advantage of our technical support, see our unique product line and discuss your product needs. Call us anytime at 716/434-5536 or fax to 716/434-3257.
METAULLICS SYSTEMS CO. L.P. #211,213,215,310,312,314 Solon, Ohio http://www.metaullics.com Metaullics Systems is a leading supplier of equipment for handling and processing non-ferrous molten metals. Metaullics manufactures a complete line of molten metal pumps as well as degassing and filtration equipment. Metaullics also manufactures equipment to aid in melting UBC and other light gage scrap. During the 1997 Exhibition, Metauliics will display its revolutionary new L-Series circulation, gas injection, and all new transfer pumps, Bonded Particle cartridge and Multicast filters, and other equipment for handling and processing molten aluminum.
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mocrECH MOLTECH SYSTEMS LTO.
MOLTEN METAL EQUIPMENT INNOVATIONS, INC. #402 Middlefield, Ohio Molten Metal Equipment Innovations, Inc. is a dynamic and innovative company that designs and manufactures people-friendly equipment for the Aluminum industry. Products include molten metal Circulation, transfer and gas injection pumps, scrap melting systems and rotary degassers. We specialize in the ability to customize any of our products to meet our customers' unique needs. MMEI invests heavily into engineering, new products and upgrading of our existing equipment. We are fully staffed to offer avariety of services to our customers. This includes on-site installation and start-up of the initial equipment as well as continued field support.
Molten Metal Equipment Innovations
MILWARD ALLOYS, INC.
All
#627,629,726,728 Carouge, Switzerland In twenty years of research, the MOLTECH Group has developed Products and Processes for aluminum electrowinning, including TINOR Aluminum-wettable Protective Cathode Coating, OPANOR Anode Oxidation Protection and EXCELNOR Side Wall Oxidation Protection, which have been tested extensively in laboratories and commercial Cells and are now available for commercial use. The ultimate goal for MOLTECH research is the development of the NOVANOR non-carbon non-consumable anode to replace carbon anodes, thereby reducing pollution in their fabrication and use, and in residue disposal. NOVA NOR anode laboratory test results are very promising and pilot scale tests are now in process. The TINOR Application System and the OPANOR System are available for the automatic application of the Products. MOLTECH invites everyone to visit its stand at TMS, which will feature an OPANOR System.
without vibration. They can be mixed and pumped some distance to aform. Best of all, they can now be gunned with standard swing-valve pumping equipment. FUSi0 2N preformed shapes are pure fused silica. A unique production process allows National to be very cost competitive while offering customized materials and shapes to meet customer needs.
NORTH AMERICAN MFG. COMPANY #606 Cleveland, Ohio
NORTH AMERICAN REFRACTORIES CO. #820, 822 Mifflinburg, Pennsylvania Rotary Oegasser MOLTON METAL EQUIPMENT INNOVATIONS, INC.
MURLIN CHEMICAL INC. #330 West Conshohocken, Pennsylvania Murlin Chemical, Inc. manufactures Bone Ash at its plant located inWest Conshohocken, Pennsylvania, USA. Established in 1978, Murtin Chemical supplies Bone Ash to the non-ferrous metals industry worldwide. Bone Ash is accepted by the non-ferrous metals industry as a superior release agent. Application of Bone Ash to a surface exposed to molten metal provides aconsistent barrier against attack by the molten metal. Plan to visit us at Booth 330 at the 1997 TMS exhibition to see and feel our product. Our representative will happily explain the advantages of Bone Ash in detail. You may contact us at (610) 825-1165 or fax us at (610) 825-8659 for further information.
NALCO CHEMICAL COMPANY
NORTON PRIMARY METALS SYSTEMS
Saint-GobainINorton Ind. Cer. Corp #517, 519 Worcester, Massachusetts Norton provides refractories for many primary metal containment and/or critical contact applications. Norton refractory products for the aluminum industry include reduction cell sidewall bricks and blocks; reverberatoryfumace ramp &floor bricks, other high-erosion components, mortars, ramming cements, dry vibration cements and low-moisture castables. Norton also supplies refractories for critical areas in filler systems, molten metal pumps, troughs and heat exchangers. Norton refractory products for the copper industry include shaft fumace liners, bricks, bumer components, associated mortars and ramming cements, low moisture-high strength castables for launders, spoons and other critical metal contact applications. The major strengths of material expertise, forming techniques, application experience and statistical process control result in high quality bonded and monolithic silicon carbide, alumina and mullite refractory products for a wide variety of applications.
#100, 102, 104, 106 Naperville, Illinois
NATIONAL REFRACTORIES & MINERALS CORP. #411 , 413 Columbiana, Ohio The National Refractories exhibit will highlight applications of Et and FUSi02N. Et products expand the uses of the company'swell known EZ Cast product line. FUSi0 2N products are National's new line of fused silica preformed shapes, foam blocks, castables, and cement. Ell castables are a family of products designed to offer three options for installation; pouring, gunning, and pumping. The unique materials can be installed by mixing and pouring into place
NORTON PRIMARY METALS SYSTEMS
PARKER HANNIFIN #720 Des Plaines, Illinois
PECHINEY CORPORATION
#301 , 303 Greenwich, Connecticut With an annual aluminium production of one million metric tons, PECHINEY is oneofthe major producers. • The Aluminium PECHINEY Technology has always been very innovative and has set many records, particularly for power consumption, cathode performances and environmental protection (3800 cells AP 18 and AP 30 inthe world). • CARBONE SAVOIE is the trademark for carbon products manufactured by PECHINEY SERS. Its experience spans more than seventy years and covers a wde i range of products (baked products and ramming pastes). CARBONE SAVOIE Products are quality certified ISO 9002 and used throughout the world in the primary aluminium,ferro alloy and steel industries. • PECHINEY Aluminium Engineering markets the PECHINEY Group's Technologies inthe following forms: • transfer of licences, operating know-how and technical assistance to the aluminium rolling facilities • Design fabrication and sale of specific casthouse equipment, i.e. Alpur, Jumbo3C ... • Supply of tumkey workshops in the form of basic engineering packages, lines of equipment and their operating know-how.
PECH I N E Y>~ PECHINEY CORPORATION
PERMATECH #219, 221,223 Graham, North Carolina Permatech engineers, designs and manufactures precision precast refractory parts and assemblies for the molten aluminum industry. The major focus of our business is directed toward molten metal transportation,filtration and casting. We specialize in precision, tight tolerance parts that can be adapted to improve any casting system. Major product categories include: transition plates, thimbles, ceramic foam filter bowls, large metal treatment boxes, troughs and specialty materials. Permatech products include unique castables and superior insulating projects such as non-wetting Moldable and Foam Insulation. Major product innovations include: • Sigma LO-Iow density ceramic transition plates, superior performances, advantages of a ceramic • Low Density Delta components-highly insu lating troughs, table tops and covers • Complete, ready to install, molten metal systems which include filter bowl, trough and large box assemblies • Excess Air Preheat systems for Ceramic
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Foam Filters and troughing systems • Unique compositions that provide superior performance and molten metal resistance Our goal is to supply refractory parts and systems which optimize molten metal quality and production efficiency, and reduce total operating costs by providing innovative, proven solutions to our customers' problems. Visit with us and discuss your application at Booth 219.
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Are you interested? Please take the chance to ask our specialists during the TMS Show or contact us directly: C.A. Pi card GmbH & Co. KG Hasteraue 9, 0-42857 Remscheid P.O. Box 140440, 042825 Remscheid Phone ++49/2191 /893-136 Fax ++49/2191/893/223
PLiBRICO #437 Chicago, Illinois Plibrico Company is a manufacturer and in· staller of monolithic refractories. Plibrico's prod· uct line is composed of a wide range of plastics, castables, and maintenance materials suitable for just about any refractory application. Not only can Plibrico offer a variety of materials, we can install these materials utilizing various methods, such as our patented HyRate and Mini·HyRate plastic gunning, pumping, Plishot, gunniting, etc. Please stop by our booth and discuss how the Plibrico representative in your area can successfully solve your refractory applications.
Ceramic Foam Filter Bowl Assembly with Excess Air Preheater. PERMATECH
PICARD, CARL AUG #430 Remscheid, Germany Picard is an intemational company with sub· sidiaries in Germany, England, USA and Hong Kong. For more than 120 years, Picard is well known as manufacturer of Wear Parts for various industries. One of the main production ranges of the company is the production of Wear Parts for Anode·paste-mixers like Liners/wearing Plates, Kneading Teeth, and Screws Flights I Paddle Screws. These Wear Parts can be offered in two executions: a) Standard· Execution b) Special High-wear·resistant Execution The Standard Execution is a hard·faced ex· ecution to achieve good and long service-time. The High·wear-resistant Execution guarantees an extraordinary long time and wear· resistance which is caused by hardfacing and coating a tungsten·carbide material. Besides the new parts, C.A. Picard offers an economical and favorable re·conditioning service which either can be arranged in your plant or our works.
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® PLiBRICO
PREMELT SYSTEMS #641,643 Kalamazoo, Michigan PREMELT is the foremost supplier of total metal scrap cleaning and processing systems worldwide. PREMELT'S patented, innovative metal processing equipment and techniques reo suit in unprecedented operational efficiencies and cost reductions. Annual metal cost savings of 10% or more are common in most PREMELT Systems. Engineering and supplying light metal scrap processing, cleaning, drying and fumace charging systems for the metals industry since 1981 .
PREMIER REFRACTORIES AND CHEMICALS, INC. #426 Clayton, Missouri Premier Refractories, a leader in Monolithic Refractories for the Aluminum Industry, offers a complete line of products including Castables, Plastics, Mortars and Ceramic Fibers Featured Products: AJugard· Non Wetting Refractories for Aluminum Contact
BluRam Plastic· The Original Mullite Based Plastic Monomax· A Monolithic Ceramic Fiber Product TruForm- Custom Engineered Refractory Shapes
-;.JRI=IIIII'::" ---.-----PREMIER REFRACTORORIES AND CHEMICALS, INC.
PRINCETON GAMMA TECH., INC. #141 Princeton, New Jersey
http://www.pgt.com
PROCEDAIR INDUSTRIES #818 Montreal, Que., Canada
PYROTEK N I C. #201,203,205,207,300,302,304,306 Spokane, Washington Pyrotek offers aluminium producers a com· plete range of materials for applications in the carbon bake, pot rooms and smelting areas. At TMS in Orlando, Florida, February 9 -13, 1997, Pyrotek will exhibit items such as high-tech ceo ramics, Wagstaff casting tableconsumbales, casting tips for strip casters and metal treatment equipment. In addition to the exhibition, Pyrotek's Degassing Manager, Mark Palmer, will be presenting a paper on the recent developments and uses of small·diameter Sialon immersion heat· ers. For more information, contact: Anna Henry, Pyrotek, E. 9503 Montgomery Avenue, Spokane, WA 99206 USA, Phone: 509-926·6212 or Fax: 509·927-2408
PylOlek
Floats, pins, transition ring and caster tip section. PYROTEK, INC
R&D CARBON LTD.
#601 Zurich, Switzerland R&D Carbon Ltd. serves the petroleum coke, pitch and aluminum industries: Research and Development: Basic resarch is carried out to better understand relationships
between raw material properties and process parameters. Technical Services: Raw material evaluations for anodes, cathodes, and other carbon products are performed in bench or pilot plant scale. Technology audits and in-plant process optimisation are carried out at customer's plants. Laboratory Test Equipment: Easilyoperated and reliable test instruments have set worldwide standards for testing carbon products. Bake Furnace Process Control: An integrated bake fum ace firing and process control system guarantees high productivity, low energy consumption and consistent anode quality. Training: Special training courses in the basics of anode manufacture are offered in our training centre or at customer's location. Engineering: A new process for green anode manufacturing allows the reduction in investment and operating cost. In cooperation with leading engineering companies our patented anode technology is marketed worldwide.
REFRACTORY TECHNOLOGY, INC. #240 Gurnee, Illinois REFRECTORY TECHNOLOGY INC. (REFTECH). the innovator of state-of-the-art monolithic refractories for molton aluminum contact applications, offers a full range of refractory solutions for the Aluminum Industry. Continuing its pledge to develop and and produce the most current refractory technology available, on display will be new products designed specifically to tackle the problem areas of chemical attaCk, mechanical damage, and physical damage. Again being featured will be the reduced cement gunning mixes (Refgun). Experinced representatives will be available to discuss problems and provide answers.
REFRACTORY TECHNOLOGY. INC.
RESEARCH· COTTRELL
#732, 734 Branchburg. New Jersey Research-Cottrell is the exclusive worldwide licensee for Alcoa's A-398 and A-446 fluidized bed dry scrubbing technologies. The technologies-the basis for the new MACT rules-provide state-of-the-art emission control and fluoride recovery from both primary aluminum polline and bake oven applications. A-398 systems are currenlly installed on more than 20 smelters (56 potlines) worldwide, treating over20 million cfm of potroom gases from both prebake and Soderburgtype reduction cells. The A-398 and A-446 technologies routinely achieve greater than 99.9% fluoride removal efficiencies. In addition to controlling fluorides and particulate, the A-446 scrubbing process significantly reduces hydrocarbons (Tars, POM, B(a)P) and S02 emissions from bakeoven furnaces, without a separate spray cooling chamber. Alcoa's proven fluid bed scrubber systems and Research-Cottrell's vast air pollution control experience in fabric filter, electrostatic precipitator, wet and dry scrubber. and VOC-removal technologies, combine to allow Research-Cottrell to offer the "Besf technologies at a competitive price.
•
Research-Cottrell
An Air & Water Technologies Company
RESEARCH-COTTRELL
REX ROTO CORPORATION #112,114 Fowlerville, Michigan Here is an opportunity you won't get very often. A place to go for help that has forty years of experience. The largest company of it's kind in the country. A staff of experienced and knowledgeable people, two plant locations plus corporate offices with research and development capabilities. All of this designed and dedicated to helping you solve your problems, the problems of heat containment, specialty refractories and superior results in performance. Our recommendations are based on experience and experimentation and not just guess work. Our programs provide extensive engineering and design services and if we haven't done it before we will find a way to do it this time. Have a good day by making Rex Roto Corporation your refractory division and the problem solvers for your refractory needs.
RHENIUM ALLOYS, INC. #537 http://www.rhenium.thomasregister.com Elyria, Ohio Rhenium Alloys, Inc. is the largest producer of fabricated rhenium products in thewortd. Founded in 1966. the rhenium powder metallurgical facility located in Elyria, Ohio, has advanced the production of high purity rhenium to ensure a consistent quality to their customers and for its own powder metallurgy fabrication. This high technological company produces rhenium and rhenium alloyed with molybdenum and tungsten to manufacture sheet, wire and rod. Seamless molybdenum rhenium and molybdenum tubing, molybdenum disintegrating electrodes and copper tungsten wire, rod, tubing, sheet, for EDM is produced additionally. High density ingots up to 4" in diameter formed at Rhenium Alloys, Inc. can be used to produce a variety of components utilized in both high and low temperature regimes. The chemical department, at Rhenium Alloys, Inc., produces a high grade of rhenium as perrhenic acid, and consistently uniform metal powder. Rhenium Alloys, Inc. is dedicated to fast delivery of superior products around the world.
RTI CONSTRUCTION, LTD. #242 Gumee, Illinois RTI Construction, Ltd., was formed and began operation in May 1995. The ideas was to provide complete, proper, and top quality refractory installation services to all types of refractory lined fumaces, vessels and equipment. We have expertise in all areas of refractory installations with men and equipment to do the job on time and RIGHT the first time. Our management team comprises over 100 years of service to the refractory industry. RTI's specialty is molten aluminum melting, holding and transfer equipment. However, our organization has built thermal oxidizers, waste to energy and utility steam generators, multiple hearth incinerators, carbon regenerators, annealing and heat treating fumaces, carbon bake furnaces, crackers, towers, vessels and all types of acid proof and resistant linings. We have also installed gunite refractories in numerous varied applications. RTI Construction, Ltd. is located in Gurnee, Illinois and can be reached by telephoning 847625-0056 or FAX 847-625-9983. Mr. Leo T. Bormann, General Manager is the contact.
SCHARF WESTFALIA GmbH
REX ROTO CORPORATION
#341 Lunen, Germany The Scharf Westfalia GmbH & Co KG (SWS) was established in 1972. emerged from the former Gewerkschaft Eisenhirtte Westfalia, laterWestfalia Becarit, presently fully owned by Deutsch Bergbau - Technik GmbH &Co KG (DBT), which is a 100 % daughter company of Ruhr Kohle AG (RAG).
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The company is located in the cities of Liinen, head office (North Rhine Westphalia) and Oelzen (Lower Saxony) Scharf Westfalia designs, develops, manufactures, and supplies turn key plants and systems as well as components for the Aluminium Industry. The Aluminium division is responsible, amongst others, forstate-of-the-arttum key Anode Rodding Shops, Anode Handling and Storage, as well Butt and Bath Treatment Plants for the Aluminium Industry. We are considered to be the world leader in the design, engineering and supply of such plants. Three of our most recent plants have been sucessfully started up in Bahrain (ALBA) and Canada (Alouette) in Autumn 1992 as well in South Africa (AlusafBayside) in Autumn 1995. All three were handled as a tum-key project. Alba and Alouette were using the Pechiney AP 30 technology, incorporating the revolutionary casting caroussel, and Alusaf the 165 kA technologyofVAW. The knowledge our experts have at their fingertips is reflected by their handling of international projects. As an international dynamic mechanical engineering company, Scharf Westfalia offers a professional Know -How and a progressive technology forthe solution of challenging problems. Our activities cover the following disciplines: Planning Design Engineering Manufacture Logistic Training Assembly Commissioning Maintenance Project Management The following systems are presenting our main product line: Turn key plants for: Anode Rodding Shops Cleaning and handling of bath and butt material Baked and green anode handling and storage systems Cooling tunnel for anode butts and bath material Crucible cleaning Fully automated transports System for green and baked anodes Anode traverse beam for the handling of anodes in the electrolyte cell
6'M ~~~ms~~
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SCHARF-WESTFALIA GmbH
SELCOM, SELECTIVE ELECTRONICS, INC. #622,624 Southfield, Michigan
SELEE CORPORATION #111,113,119,210,212 httpJ/v;ww.selee.com Hendersonville, North Carolina SELEE Corporation is the premier manufacturer of ceramic foam filters for use in the ferrous and non-ferrous metals industries as well as innovative refractory and preheat systems and a growing line of specialty products. SELEE Corporation is THE ONLY CERAMIC FOAM FILTER AND REFRACTORIES SUPPLIER IN THE WORLD TO ACHIEVE ISO 9001 , FORD 01, AND OS-9000 CERTIFICATIONS. This means SELEE Corporation will deliver to you on time the best quality products in the industry. SELEE has maintained the market and technical leadership for the ceramic foam industry by developing strong partnerships with customers. These partnerships allow customers to share SELEE resources to solve all types of problems. SELEE resources include: • Full Range of Ceramic Foam Filters • Custom Refractories, Bowls, Burners • Specialty Consumables • Fully Equipped Metallurgical Lab • A Team of Applications Engineers • ADedicated Customer Service Department • Nationwide Direct Sales Force • R&D Pilot Plant Facility for Partnership De velopments • TOM Programs that Provide: • Continuous Improvement • Full Product Certification • Self-Directed Work Teams • On-Site Customer Training Programs
Am!:?r~f.Group
SELEE CORPORATION
SENTECH CORPORATION #511,513,610,612 Tempe, Arizona
SERMASS.A. #120 Saint Ouentin Sur Isere, France
SHIELDALLOY METALLURGICAL CORPORATION #318,320 Newfield, New Jersey Shieldalloy Metallurgical Corporation's (SMC) Aluminum Products Group has been producing grain refiners, master alloys, and compacted products for use in the Aluminum Industryfor25 years. SMC was the first company to develop and introduce the newest technology of continuous cast and conformed rod which offers the highest quality grain refining rod, strontium-aluminum rod or other master alloy rod in the industry. Our continuing efforts in technical development have resulted in a variety of new grain refiners or master alloys and hardeners for use in the primary, secondary, and foundry markets. We invite you to visit our booth to discuss these new alloys and other new products that we have developed such as our Castcut which offers very tight weigh control for precision addition requirements. Also, SMC not only offers traditional briquettes of manganese, iron, and chrome but also our newest product ALTAB which offers the most cost effective means of adding manganese, iron, chromium, copper, etc. to molten aluminum.
SKAMOLAIS #329, 331 http://www.cheminova.com Nykobing Mors, Denmark Skamol lnsulation introducing new products at TMS/AIME 1997. Backed by more than 80 years experience, Skamol Insulation is one of the world's leading manufacturers of thermal insulation for the temperature range 600-1200 degrees Celsius (1112 degrees -2192 degrees Fahrenheit) offering products based on Moler, Perlite, Calcium Silicate and Vermiculite. At the 1997 TMS Annual Meeting and Exhibition, Skamol will be introducing a new range of Perlite Block Insulation. Due to the special chemistry, the Perlite Blocks are especially applicable for insulation of aluminium reduction cell cathodes giving the benefit of good resistance to molten aluminium and quick installation due the large sizes. Further, Skamol has joined forces with Norwegian Elkem Carbon in introducing two new types of cold ramming pastes based on Electrically Calcined Anthracite (ECA). The development of these cold ramming pastes is a clear improvement of the conventional lining concept, reducing emissions of hazardous tar and PAH (polyaromatic hydrocarbons) to a minimum and increasing pot life and enhancing profitability. We are pleased to announce that our senior R&D Manager, Mr. Stig F. Johansson will be giving alecture on the subject: Penetration Force of Bath Components into Pot Linings Described by Non-equilibrium Thermodynamics. Our sales teams from Denmark and the USA look forward to seeing you.
({3
skamol insulation
Hot Aluminum Crucible Cleaner
SKAMOL
SME #122 Littleton, Colorado
STAS APPLIED TECHNOLOGIES SOCIETY S.T.A.S. Ltd.
#226,228 Chicoutimi, Quebec, Canada STAS specializes in the development, fabrication and commercialisation of technologically advanced equipment for the aluminum industry according to international manufacturing standards. Our clients are serviced by a network of representatives in the Americas, Europe ASia, Australia and South Africa. STAS is a recognised leader in its innovative abilities to supply specialized equipment according to customer needs to improve quality, reduce pollution and lower costs, using the latest in programmable automatic controls. Examples include dross coolers, molten metal jet stirrers, bed fillers, HF monitors, gas injection fluxing units and crucible cleaners. STAS is located in Quebec, where 2,000,000 tonnes of aluminum alloys are produced in the most technologically advanced plants in the world. World-class research facilities clone by, sucn as the Alcan RIO Centre, the Centre de recherche industrielle and the University of Quebec provide STAS with many opportunities to develop the latest technologies for the aluminum industry.
Alcan Inert Gas Dross Cooler STAS APPLIED TECHNOLOGIES
STELLAR MATERIALS INC. http://www.stelterbrink.com #637 Detroit, Michigan Thermbond is aunique new refractory material with features and benefits unavailable in traditional refractories. Thermbond is completely and naturally non-wetting to aluminum - with no additives to bum out. Thermbond bonds permanently to other refractories. Existing linings may be veneered and repaired with Thermbond.
STELTER &BRINCK, INC. #335 http://www.stelterbrinck.com Harrison, Ohio Stelter & Brinck, Inc. is a full service combustion engineering and manufacturing company. We are centrally located near Cincinnati, Ohio, and our experience with combustion equipment dates back to 1956. Our packaged industrial equipment offers excellent quality at a competitive price, while the reliability of our engineering and manufacturing lessens downtime and increases productivity. Stelter & Brinck offers: Fully packaged and ready to install equipment. All equipment is prepiped and prewired. Heavy duty construction. Installation and design services available. Onsite start up is available. One year guarantee on all equipment. Fully staffed service and engineering teams for later support and maintenance. Stelter & Brinck builds awide range of combustion equipment. The Mill Products Division serves the nonferrous and ferrous metals industry and builds the following: Sow preheaters, crucible preheaters, car bottom furnaces, aging and an-
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nealing furnaces, trough and runner castable dryers, and other specialty equipment. We also build catalytic fume oxidizers, fume incinerators, and industrial air heaters for a wide range of industries.
• Casthouse: Scraps loader truck, Molten metal tapping truck, Molten metal ladle trans porter • Cleaners: Anode cavity cleaner, Baked anode cleaning station, Ladle cleaning station, Vacuum cleaner, Butt cleaning station • Feeders: Alumina feeding truck, Alumina f luoride feeding truck, Soederberg paste feed ing truck, Anode covering truck, point feed ers • Miscellaneous: Stud pulling module, Spadi ng truck, Anode transporter truck, Anode lifting beam.
TEXSEM LABORATORIES INC. #704 Provo, Utah
THE METALLURGICAL SOCIETY OFCIM #706 Montreal, Que., Canada
THERMAL CERAMICS & THERMIC REFRACTORIES STELTER & BRINCK, INC.
SUPERIOR GRAPHITE #146 Chicago, Illinois Superior Graphite Co. has designed a line of graphite lubricants and coatings specifically to meet the challenges of aluminum processing. All of our products are made with the finest ingredients and backed by our experienced technical support staff. So, whether it be smelting, casting, extrusion or forging, Superior Graphite Co. can supply you with a premium graphite product to meet your processing requirements. Stop by booth #146 for more information and free gift.
TECHMO CAR & ENGINEERING #427, 429, 526 Limena, Padova, Italy Since its foundation in 1961 , Techmo Car's objective has always been to improve some of the burdensome and difficult work conditions in the aluminium industry. Techmo Car was one of the first companies to study and introduce high-teChnology equipment and machinery into aluminium plants,with the double aim of ahigher productivity and better, safer work conditions. Production Range: • Anode changers: Standard changing truck, Multipurpose changing truck, Pot tending module • Breakers: Hammer crust breaker truck, Wheel crust breaker truck, Spent pot lining breaker truck, Spent pot lining breaker truck, Dustop long life hydraulic hammer
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#117,216,218,220 Augusta, Georgia
THERMAL SYSTEMS AMERICA #138 Canastota, New York Thermal Systems America looks forward to the 1997 TMS. New this year is an interactive introduction to the engineering solutions and products available from Thermal Systems America. Join us at our booth 138 and: 1. Take a planttour 2. Leam about the history of TSA 3. TSA Products include • Floor Tile • Crucibles • Troughs • Fumace components • Filter Boxes • Electrical Pass Throughs • Starwheels • Degassing Systems • Flow Control Most importantly, stop by and meet the people of TSA, who continue to make TSA the leader in providing engineering solutions to the industries we serve.
THERMAL SYSTEMS AMERICA
THERMCON OVENS B.V.
#617 Geldermalsen, The Netherlands Melting and holding fumaces for aluminium designed and built by Therrncon are in wide spread use with major aluminium producers around the world. In recent years D.C. casting machines and homogenizing fumaces have been added to the delivery program making Thermcon an all-round supplier for tum key casthouse packages. Recycling of aluminium scrap has been a priority with Thermcon for many years already, hence the development of side well furnaces with integrated incinerators, enclosed charging systems and delacquering and preheating installations in operation with clients such as V.A.w., Daiki in Japan. Thermcon will give an update on the latest furnace technology available and developments underway to meet the requirements of the future, both with respect to improved economics and compliance with environmental regulations.
33 METAL PRODUCING #611 Cleveland, Ohio
THORPE TECHNOLOGIES INC. #305, 307 http://www.thorpetech.com Whittier, Califomia Thorpe Technologies Inc., aprofessional engineering organization, focuses exclusively on the design, development, engineering, and construction of industrial fumaces, delacquering systems, thermal oxiders, and related thermal technology. Aluminum product line includes: • Apros-based technology delacquering sys tems • Rectangular Melting Furnaces • Sidewell Melting Fumaces • Dry Hearth Melting Fumaces • Round Top Charge Melting Furnaces • Tilting Melting Furnaces • Rotary Melting Fumaces • Stationary Holding Fumaces • Tilting Holding Furnaces • Batch Homogenizing Fumaces • Continuous Homogenizing Fumaces Thorpe Technologies Inc. is headquartered in Whittier, CA; Tel: 310-903-8230 with a branch office serving the eastem United States located in Gulf Shores, AL; Tel: 334-968-6211 .
For 75 years, the Thorpe industrial fumace design group has provided industrial fumace design and engineering services to clients throughout th(; united States and abroad. The Thorpe Te~nnologies Inc. organization is one more step .0 do an even better job in the rapidly changing, and increasingly technical, fumace design marketplace.
U.S. BUREAU OF MINES #337 Pittsburgh, Pennsylvania
UNIFRAX CORPORATION-FIBERS DIVISION #505, 507 Niagara Falls, New York Unifrax Corporation (formerty known as The Carborundum Company) is one of the leading producers of high performance, heat-management materials used by many industries in a diverse group of applications. Unifrax is committed to solving industrial insulating problems and providing exceptional value to its customers. This commitment is evident in the company's investment in advanced process technology, its state-of-the-art manufacturing facilities, its extensive research and development activities, and its continual focus on quality in the broad range of products and services it offers. Fiberfrax insulating products are available in more than 50 product forms. They have traditionally been used in heat vessels in the production and processing of ferrous and non-ferrous metals, industrial chemicals, petroleum products, power generation, and ceramic, glass, and other industries employing process temperatures up to 3000 degrees Fahrenheit (1650 degrees Celsius). Unifrax will exhibit one of their latest product developments, Insulfrax Specialty Glass Fiber at the upcoming TMS show in February'97. Insulfrax Specialty Glass Fiber is an evolutionary breakthrough in insulating materials resulting in aproduct with awide range of applications in the primary metals and metals processing industries and possessing superior thermal and mechanical properties.
U.S. DEPT. OF ENERGY - OFFICE OF INDUSTRIAL TECHNOLOGIES #128 Washington, D.C. In collaboration with academia, and other federal and state agencies, the Department of Energy's Office of Industrial Technologies and the aluminum industry are working together to build astronger and more competitive industry, to achieve national goals for energy, the economy, and the environment. The Aluminum Association recently published ALUMINUM INDUSTRY: Industry/Govemment Partnerships for the Future which provides the initial vision for the U.S. Aluminum industry to compete globally into the 21 st century. On October 9, 1996, Secretary Hazel O'leary signed a compact with the aluminum industry to establish a research and development partnership. This partnership will identify appropriate areas for joint R&D that can improve the quality of life in the United States and promote the manufacture of competitively priced and ecologically sustainable aluminum products. DOE is facilitating the Aluminum Industry's development of Technology Roadmap to establish a strategy for achieving the goals set forth in its vision document.
VESUVIUS NEOMELT #618 Buffalo, New York Vesuvius Neomelt is a wortd leader in the design, manufacture and supply of refractory products for the containment, transfer and flow control of both ferrous and non-ferrous molten metals. An extensive network of manufacturing plants, strategicallylocated throughoutlhe wortd,complement local technical and marketing organizations, geared to servicing diverse customers and industries. Products are manufactured using a variety of forming processes including slip casting, blending, isostatic and hydraulic pressing, spinning, and injection molding. The diversity of manufacturing processes enables the formation of a multitude of shapes and blends from many different materials including Alumina, MgO, Fused Silica, Graphitized Alumina, SiC, Zirconia and Sialon. The broadest range of products from a s ni gle refractory source includes, Pouring Pins and Spouts, Burner Tubes, Thermocouple Sheaths, Rotary Degassing Components, Low Pressure Stalk Tubes, Refractory Cements, Crucibles and much more. Vesuvius Neomelt is the refractory solution for your business.
VANDEMARK METALS &ALLOYS #710,712 Lockport, New York VanDeMark Metals &Alloys, Inc. supplies afull line of products to the cast shops of the North American Copper and Aluminum industries. Featured products include Petrocarb Injection Systems, an innovative, cost-saving process for injection alloying of Manganese, Chrome, Iron and Copper metal powders into molten Aluminum and Copper. VanDeMark is also a recognized supplier of high quality Aluminum Master Alloys including 5% Boron, 3% Titanium-1% Boron, and 10% Strontium; and Copper Master Alloys including 10% Beryllium and 15% Phosphorus. VanDeMark is committed to benefiting you with products, knowledge, service and value that will improve your processes, increase your profits and reduce your costs. Make our market your market through our results-oriented sales, distribution, product representation and technical support. Visit our booth or call us at 716-433-6764 or fax to 716-4332850.
"VANDEMARK METALS & ALLOYS. INC.
VANDEMARK METAL &ALLOYS, INC.
VESUVIUS NEOMELT
Zyacarb-sillcon carbide, Tercod-carbon bonded SiC, Kelltride-silicoon nitride bonded SiC, and Sialon thermocouple protection tubes.
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Zyarock®.fused silica shapes for primary alu· minum and non·ferrous applications. VESUVIUS NEOMELT
WAGSTAFF ENGINEERING INC. #101,103,105,107, 200,202,204,206 Spokane, Washington Wagstaff, Inc. has provided innovative casting equipment for the aluminum industry for over 40 years. Known worldwide for such industry breakthroughs as Air SlipTM, MaxiCast™, and LHC technology, Wagstaff continues to bring new ideas and equipment to the marketplace. Wagstaff's precision machined billet casting system, MaxiCast™, comprises a casting table, starting head base, tooling, and utilities. The system maximizes the number of billets that can be cast in the casting pit.
Other advantages include: • Hot-top metal distribution system for low operating costs • Graphite lined molds with continuous lubri cation • Wagstaffs AirSlipTM mold technology for op timum Billet quality • Self-centering starting heads to prevent mold damage • Lattice-design starting head base to reduce the impact that any metal spill produces Wagstaff rolling ingot molds have long been the industry standard. The revolutionary Low Head Composite™ (LHC) system produces Ingot quality comparable to EMC. All of Wagstaffs ingot molds offer: • Precision machined molds for accurate, re producible ingot dimensions • Self-aligning system to assure mold to start ing head alignment • Curl reduction technology to prevent hang ups • Full range of ingot contours and sizes Wagstaff AutoCast™Control Systems allow operators to maintain precise control over the many variables of a cast. Benefits include: • Predictable and repeatable casting starts • Highly accurate metal level control
WAHL REFRACTORIES, INC. #131,133 Fremont, Ohio Wahl Refractories, Inc. is recognized as an innovative leader in the manufacturing of refractory specialties and preformed shapes, including the patented SIFCA products serving the aluminum industry worldwide. Wahl also offers engineering and installation services.
WESTERN INDUSTRIAL CERAMICS #420,422 Tualatin, Oregon
ZYP COATINGS #126 Oak Ridge, Tennessee lYP® Coatings, Inc. was established in 1982 and specializes in producing the most complete line of protective paintable refractory coatings for high-temperature use. Fields of use include washcoatings that provide long-term protection of metals, ceramics and graphite from oxidation and chemical attack. These unique paintable coatings produce the maximum performance of the coated substrate. lYP® Coatings, Inc. pioneered the use of boron nitride-based coatings for non-wetting applications with molten aluminum, magnesium and their alloys and drosses. The Boron Nitride Lubricoat® is known as the leader for foundry uses such as for permanent molds, and as a coating for crucibles, ladles, molds, dies, stalk tubes, riser tubes, immersion tubes, degassing units, bubbler tubes, _etc. A totally new product, Boron Nitride Hardcoat, was developed to meet customer requests for added hardness and abrasion resistance along with the nonwetting of boron nitride. ZYP® Coatings, Inc. sells these products internationally in many specialty foundry areas.
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BNZ Materials, Inc. BNZ MATERIALS, INC.
BUSS, A.G.
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Make HI·TECH CERAMICS part of your metal cleanliness improvement team today! HIGH TECH CERAMICS
MECHATHERM INTERNATIONAL LIMITED
1997 TMS Annual Meeting and Exhibition Orlando Convention Center, Orlando, Florida SESSION TITLE
ROOM
DAY
PAGE
Advances in Coating Technologies I .................................................................................................... 315B
MonAM
1
Advances in Coating Technologies II ..... .............................................................................................. 315B Advances in Coating Technologies III ................................................................................................. 315B
MonPM TueAM
36 75
Advances in Coating Technologies IV ................................................................................................. 315B Advances in Coating Technologies V ................................................................................................... 315B
TuePM
144
Wed AM
150
Advances in Coating Technologies VI ................................................................................................. 315B Advances in Electrically Conductive Materials I ................................................................................. 340B
Wed PM MonAM
189
Advances in Electrically Conductive Materials II ................................................................................ 340B Advances in Synthesis & Processing of Metal and Ceramic Matrix Composites I ............................. 340B
MonPM TueAM
37 76
Advances in Synthesis & Processing of Metal and Ceramic Matrix Composites II ............................ 340B Advances in Synthesis & Processing of Metal and Ceramic Matrix Composites III ........................... 340B
TuePM Wed AM
115 151
Advances in Synthesis & Processing of Metal and Ceramic Matrix Composites IV .. ......................... 340B Advances in Synthesis & Processing of Metal and Ceramic Matrix Composites V ..... ....................... 340B
Wed PM ThuAM
190 222
Alumina & Bauxite Technology I ........................................................................................................ 230D Alumina & Bauxite Technology II ....................................................................................................... 230D
TueAM TuePM
78 116
Alumina & Bauxite Technology III ...................................................................................................... 230D Alumina & Bauxite Technology IV ...... ................................................................................................ 230D
Wed AM Wed PM
152 191
Aluminum Dross & Salt Cake Processing ...................................................................................... ...... 231 C Aluminum Reduction Technology I ..................................................................................................... 230A
ThuAM
223
MonAM
3
Aluminum Reduction Technology II .................................................................................................... 230A
MonPM
Aluminum Reduction Technology III ....... ............................................................................................ 230A
TueAM
38 79
Aluminum Reduction Technology IV .................................................................................................. 230A
TuePM
117
Aluminum Reduction Technology V ........... ......................................................................................... 230A
Wed AM Wed PM
153
Aluminum Reduction Technology VI .................................................................................................. 230A Aluminum Reduction Technology VII ................................................................................................. 230A
2
ThuAM
192 224
Aqueous Electrotechnologies I ............................................................................................................. 231A Aqueous Electrotechnologies II ........................................................................................................... 231A
MonAM MonPM TueAM TuePM Wed AM Wed PM MonAM MonPM
4 39 80 119 154 193 5 40
Aqueous Electrotechnologies III .......................................................................................................... 231A
TueAM
81
Aqueous Electrotechnologies IV .......................................................................................................... 231A
TuePM
120
Aqueous Electrotechnologies V ........................................................................................................... 231A
Wed AM
156
Applications of Sensors & Modeling in Materials Processing I .......................................................... 232A Applications of Sensors & Modeling in Materials Processing II ......................................................... 232A Applications of Sensors & Modeling in Materials Processing III ............... ......................................... 232A Applications of Sensors & Modeling in Materials Processing IV ...... .................................................. 232A Applications of Sensors & Modeling in Materials Processing V ......................................................... 232A Applications of Sensors & Modeling in Materials Processing VI.. ...... ................................................ 232A
Aqueous Processing (G.A.) .................................................................................................................. 240B
Wed PM
194
Automotive Alloys I ............................................................................................................................. 340A
Wed AM
157
Automotive Alloys II ............................................................................................................................ 340A
Wed PM
196
Automotive Alloys III ..... ...................................................................................................................... 340A
ThuAM TueAM
225 83
Carbon Technology II ........................................................................................................................... 230C Carbon Technology III ... ....................................................................................................................... 230C
TuePM
121
Wed AM
159
Carbon Technology IV ......................................................................................................................... 230C
Wed PM
197
Carbon Technology I ............................................................................................................................ 230C
SESSION TITLE
ROOM
DAY
PAGE
Carbon Technology V ........................................................................................................................... 230C
ThuAM
226
Cast Shop Technology I ........................................................................................................................ 230B
MonAM
7
Cast Shop Technology II ...................................................................................................................... 230B
MonPM
41
Cast Shop Technology 1111 .................................................................................................................... 230B
TueAM
84 122
Cast Shop Technology IV ..................................................................................................................... 230B
TuePM
Cast Shop Technology V ...................................................................................................................... 230B
Wed AM
160
Cast Shop Technology VI ..................................................................................................................... 240A
Wed AM
161
Cast Shop Technology VII .................................................................................................................... 230B
Wed PM
16]
Cast Shop Technology VIII .................................................................................................................. 230B
ThuAM
227
Casting and Solidification (G.A.) ......................................................................................................... 231A
Wed PM
197
Chemistry & Physics of Nanostructures and Related Nonequilibrium Materials I .............................. 330C
MonAM
8
Chemistry & Physics of Nanostructures and Related Nonequilibrium Materials II ............................ 330C
MonPM
43
Chemistry & Physics of Nanostructures and Related Nonequilibrium Materials III ........................... 330C
TueAM
85
Chemistry & Physics of Nanostructures and Related Nonequilibrium Materials IV ........................... 330C
TuePM
124
Chemistry & Physics of Nanostructures and Related Nonequilibrium Materials V ............................ 330C
Wed AM
162
Chemistry & Physics of Nanostructures and Related Nonequilibrium Materials VI ........................... 330C
Wed PM
201
Chemistry & Physics of Nanostructures and Related Nonequilibrium Materials VII ......................... 330C
ThuAM
228
Composites: Mechanical Properties & Processing (G.A.) ................................................................... 240D
Wed AM
163
Defining Core Materials Curriculum I ................................................................................................. 340D
TueAM
86
Defining Core Materials Curriculum II ................................................................................................ 340D
TuePM
125
Design & Reliability of Solder & Solder Joints I ................................................................................. 332
MonAM
9
Design & Reliability of Solder & Solder Joints II ............................................................................... 332
MonPM
44
Design & Reliability of Solder & Solder Joints III .............................................................................. 332
TueAM
88
Design & Reliability of Solder & Solder Joints IV .............................................................................. 332
TuePM
126
Design & Reliability of Solder & Solder Joints V ............................................................................... 332
Wed AM
165
Design & Reliability of Solder & Solder Joints VI .............................................................................. 332
Wed PM
202 229
Design & Reliability of Solder & Solder Joints VII ............................................................................. 332
ThuAM
Evolution & Advanced Characteristics of Thin Film Microstructures I .............................................. 340C
MonAM
12
Evolution & Advanced Characteristics of Thin Film Microstructures II ............................................. 340C
MonPM
46
Evolution & Advanced Characteristics of Thin Film Microstructures III ............................................ 340C
TuesAM
90
Evolution & Advanced Characteristics of Thin Film Microstructures IV ............................................ 340C
TuePM
128
Evolution & Advanced Characteristics of Thin Film Microstructures V ............................................. 340C
Wed AM
167
Evolution & Advanced Characteristics of Thin Film Microstructures VI ............................................ 340C
Wed PM
203
Exemplary Practice in the Extractive Metallurgy of Copper ............................................................... 340D
Wed PM
204
Fundamentals of Gamma Titanium Aluminides I ................................................................................ 330E
MonAM
13
Fundamentals of Gamma Titanium Aluminides II ............................................................................... 330E
MonPM
47
Fundamentals of Gamma Titanium Aluminides III .............................................................................. 330E
TueAM
91
Fundamentals of Gamma Titanium Aluminides IV .............................................................................. 330E
TuePM
129
Fundamentals of Gamma Titanium Aluminides V ............................................................................... 330E
Wed AM
168
Fundamentals of Gamma Titanium Aluminides VI .............................................................................. 330E
Wed PM
205
General Metallurgy (G.A.) ................................................................................................................... 231C
Wed PM
206
General Recycling I .............................................................................................................................. 230C
MonAM
14
General Recycling II ............................................................................................................................. 230C
MonPM
48
Global Exploitation of Heap Leachable Deposits I .............................................................................. 231 C
MonAM
15
II
SESSION TITLE
ROOM
DAY
PAGE
Global Exploitation of Heap Leachable Deposits II ............................................................................. 231C
MonPM
49
Global Exploitation of Heap Leachable Deposits III ........................................................................... 231 C
TueAM
92
Global Exploitation of Heap Leachable Deposits IV ........................................................................... 231 C
TuePM
131
Global Exploitation of Heap Leachable Deposits V ............................................................................ 231C
Wed AM
169
High Temperature Superconductors I ................................................................................................... 315A
MonAM
16
High Temperature Superconductors II ................................................................................................. 315A
MonPM
50
High Temperature Superconductors III ................................................................................................ 315A
TueAM
93
High Temperature Superconductors IV ................................................................................................ 315A
TuePM
132 170
High Temperature Superconductors V ................................................................................................. 315A
Wed AM
High Temperature Titanium Alloys I .................................................................................................... 231 B
MonAM
18
High Temperature Titanium Alloys II .................................................................................................. 231B
MonPM
51
Hume Rothery Award Symposium for Bruno Predel I ......................................................................... 330B
MonPM
53
Hume Rothery Award Symposium for Bruno Predel II ....................................................................... 330B
TueAM
95
Hume Rothery Award Symposium for Bruno Predel III ...................................................................... 330B
TuePM
133
Innovations in Aluminum I ................................................................................................................... 232B
Wed AM
171
Innovations in Aluminum II ................................................................................................................. 232B
Wed PM
207
Int'l Symposium on Rhenium and Rhenium Alloys I .......................................................................... 232C
MonAM
20
Int'l Symposium on Rhenium and Rhenium Alloys II ......................................................................... 232C
MonPM
55
Int'l Symposium on Rhenium and Rhenium Alloys III ........................................................................ 232C
TueAM
97
Int'l Symposium on Rhenium and Rhenium Alloys IV ....................................................................... 232C
TuePM
135
Int'l Symposium on Rhenium and Rhenium Alloys V ......................................................................... 232C
Wed AM
172
Int'l Symposium on Rhenium and Rhenium Alloys VI ....................................................................... 2400
Wed PM
208
Int'l Symposium on Rhenium and Rhenium Alloys VII ...................................................................... 2400
Wed PM
209
Int'l Symposium on Rhenium and Rhenium Alloys VIII ..................................................................... 232C
Wed PM
209
Int'l Symposium on Rhenium and Rhenium Alloys IX ....................................................................... 232C
ThuAM
232
Int'l Symposium on Rhenium and Rhenium Alloys X ......................................................................... 231 A
ThuAM
233
Int'l Symposium Processing & Handling of Powders and Dusts I ...................................................... Salon 6
MonAM
19
Int'l Symposium Processing & Handling of Powders and Dusts II ..................................................... Salon 6
MonPM
53
Int'l Symposium Processing & Handling of Powders and Dusts III .................................................... Salon 6
TueAM
96
Int'l Symposium Processing & Handling of Powder and Dusts IV ..................................................... Salon 6
TuePM
134
Light Weight Alloys for Aerospace Applications I ............................................................................... 330A
MonAM
21
Light Weight Alloys for Aerospace Applications II ............................................................................. 330A
MonPM
56
Light Weight Alloys for Aerospace Applications III ., .......................................................................... 330A
TueAM
98
Light Weight Alloys for Aerospace Applications IV ............................................................................ 330A
TuePM
137
Light Weight Alloys for Aerospace Applications V ............................................................................. 330A
Wed AM
173
Light Weight Alloys for Aerospace Applications VI ............................................................................ 330A
Wed PM
211 100
Low Energy Beam Processes in Electronic Materials I ....................................................................... 314B
TueAM
Low Energy Beam Processes in Electronic Materials II ...................................................................... 314B
TuePM
138
Low Energy Beam Processes in Electronic Materials III ..................................................................... 314B
Wed AM
175
Low Energy Beam Processes in Electronic Materials IV ..................................................................... 314B
Wed PM
212
Materials & Technologies for Microelectronics I ................................................................................. 314B
MonAM
24
Materials & Technologies for Microelectronics II ............................................................................... 314B
MonPM
60
Materials for Spallation Neutron Sources I ....................................................................................... '" Salon 4
MonPM
59
Materials for Spallation Neutron Sources II ......................................................................................... Salon 4
TueAM
102
III
SESSION TITLE
ROOM
DAY
PAGE
Materials for Spallation Neutron Sources III ....................................................................................... Salon 4
TuePM
140
Materials for Spallation Neutron Sources IV ....................................................................................... Salon 4
Wed AM
175
Materials Processing Fundamentals I ................................................................................................... 231B
TueAM
103
Materials Processing Fundamentals II .................................................................................................. 231B
TuePM
14]
Materials Processing Fundamentals III ................................................................................................ 231B
Wed AM
176
Materials Processing Fundamentals IV ................................................................................................ 231B
Wed PM
213
Materials Processing Fundamentals V ................................................................................................. 231B
ThuAM
237
Materials, Coatings & Processes for Improved Reliability of High Temperature Compo I ................. Salon 3
MonAM
23
Materials, Coatings & Processes for Improved Reliability of High Temperature Compo II ................ Salon 3
MonPM
57
Materials, Coatings & Processes for Improved Reliability of High Temperature Compo III ............... Salon 3
TueAM
102
Materials, Coatings & Processes for Improved Reliability of High Temperature Compo IV ............... Salon 3
TuePM
138
Mechanical Behavior (GA) .................................................................................................................. 230D
MonAM
25
Metallurgy of Less Common Metals II ................................................................................................ 240A
Wed PM
214
MicrostructurelProperty Relationship: Corrosion and Deformation II (G.A.) ..................................... 240C
Wed AM
179
MicrostructurelProperty Relationships-Deformation I (G.A.) ............................................................. 240B
Wed AM
179
Non-Linear Fracture Processes in Brittle Crystalline Solids I ............................................................. 232B
MonPM
61
Non-Linear Fracture Processes in Brittle Crystalline Solids II ............................................................ 232B
TueAM
104
Non-Linear Fracture Processes in Brittle Crystalline Solids III ........................................................... 232B
TuePM
142
Physical Metallurgy: Fundamentals & Applications (G.A.) ................................................................. 232B
MonAM
27
Pyrometallurgy & Melting Practice ...................................................................................................... 230D
MonPM
62
Rare Earths, Science, Technology and Applications I .......................................................................... Salon 8
MonAM
28
Rare Earths, Science, Technology and Applications II ........................................................................ Salon 8
MonPM
63
Rare Earths, Science, Technology and Applications III ....................................................................... Salon 8
TueAM
105
Rare Earths, Science, Technology and Applications IV ....................................................................... Salon 8
TuePM
143
Rare Earths, Science, Technology and Applications V ........................................................................ Salon 8
Wed AM
180
Recent Advances in Fracture I .............................................................................................................. 314A
MonAM
29
Recent Advances in Fracture II ............................................................................................................ 314A
MonPM
64
Recent Advances in Fracture III ........................................................................................................... 314A
TueAM
106
Recent Advances in Fracture IV ........................................................................................................... 314A
TuePM
143
Recent Advances in Fracture V ............................................................................................................ 314A
Wed AM
181
Recent Advances in Fracture VI ........................................................................................................... 314A
Wed PM
216
Recent Advances in Fracture VII .......................................................................................................... 314A
ThuAM
238
Shaping & Forming of High Performance Powder Products I ............................................................. Salon 7
MonPM
70
Shaping & Forming of High Performance Powder Products II ........................................................... Salon 7
TueAM
108
Shaping & Forming of High Performance Powder Products III .......................................................... Salon 7
TuePM
145
Spray Forming-Experimental Analysis & Applications I ..................................................................... 330B
Wed AM
183
Spray Forming-Experimental Analysis & Applications II ................................................................... 330B
Wed PM
217
Spray Forming-Experimental Analysis & Applications III .................................................................. 330B
ThuAM
240
Structure & Properties of Bulk Amorphous Alloys I ............................................................................ 340A
MonAM
31
Structure & Properties of Bulk Amorphous Alloys II .......................................................................... 340A
MonPM
71
Structure & Properties of Bulk Amorphous Alloys III ......................................................................... 340A
TueAM
109
Structure & Properties of Bulk Amorphous Alloys IV ......................................................................... 340A
TuePM
146
Structure & Properties of Internal Interfaces I ..................................................................................... 330G
MonAM
32
Structure & Properties of Internal Interfaces II .................................................................................... 330G
MonPM
72
IV
SESSION TITLE
ROOM
DAY
PAGE
Structure & Properties of Internal Interfaces III ................................................................................... 330G
TueAM
110
Structure & Properties of Internal Interfaces IV .................................................................................. 330G
TuePM
147
Structure & Properties of Internal Interfaces V .................................................................................... 330G
Wed AM
184
Structure & Properties of Internal Interfaces VI .................................................................................. 330G
Wed PM
219
Successful University-Industry Linkage for a Global Economy I ....................................................... 340D
MonAM
33
Successful University-Industry Linkage for a Global Economy II ...................................................... 340D
MonPM
73
Synthesis of Lightweight Metallic Materials I ..................................................................................... 330F
MonAM
34
Synthesis of Lightweight Metallic Materials II .................................................................................... 330F
MonPM
73
Synthesis of Lightweight Metallic Materials III .................................................................................. 330F
TueAM
112
Synthesis of Lightweight Metallic Materials IV .................................................................................. 330F
TuePM
148
Synthesis of Lightweight Metallic Materials V .................................................................................... 330F
Wed AM
186
Synthesis of Lightweight Metallic Materials VI .................................................................................. 330F
Wed PM
220
Synthesis of Lightweight Metallic Materials VII ................................................................................. 330F
ThuAM
241
The Increasing Importance of Secondaries & Residues in Primary & Secondary CulNi Smelting ..... 340D
Wed AM
187
Update of the Practice of Copper in Electrorefinery Bleed-Off Treatment .......................................... 340D
ThuAM
243
v
1997 TMS ANNUAL MEETING & EXHIBITION FEBRUARY 10-13, 1997 MONDAY FEBRUARY 10
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THURSDAY FEBRUARY 13
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Aluminum Reduction I page 3
Aluminum Reduction II page 38
Aluminum Reduction III page 79
Aluminum Reduction IV page 117
Aluminum Reduction V page 153
Aluminum Reduction VI page 192
Aluminum Reduction VII page 224
Cast Shop Technology I page 7
Cast Shop Technology II page 41
Cast Shop Technology III page 84
Cast Shop Technology IV page 122
Cast Shop Technology V page 160
Cast Shop Technology VII page 161
Cast Shop Technology VIII page 227
General Recycling - I page 14
General Recycling - II page 48
Carbon Technology I page 83
Carbon Technology II page 121
Carbon Technology III page 159
Carbon Technology IV page 197
Carbon Technology V page 226
Mechanical Behavior (GA) page 25
Pyrometallurgy & Melting Practice I page 62
Alumina & Bauxite I page 78
Alumina & Bauxite II page 116
Alumina & Bauxite III page 152
Alumina & Bauxite IV page 191
Aqueous Electrotechnologies T&PI page 5
Aqueous Electrotechnologies T&PII page 40
Aqueous Electrotechnologies T&PIII page 81
Aqueous Electrotechnologies T&PIV page 120
Aqueous Electrotechnologies T&PV page 156
Casting and Solidification (GA) page 197
Int'l. Symp. on Rhenium and Re Alloys X page 233
High Temp Titanium Alloys I page 18
High Temp Titanium Alloys II page 51
Materials Processing Fund I page 103
Materials Processing Fund II page 141
Materials Processing Fund III page 176
Materials Processing Fund IV page 213
Materials Processing Fund V page 237
Global Expl of Heap Leach Deposits I page 15
Global Expl of Heap Leach Deposits II page 49
Global Expl of Heap Leach Deposits III page 92
Global Expl of Heap Leach Deposits IV page 131
Global Expl of Heap Leach Deposits V page 169
General Metallurgy (GA) page 206
Alum Dross & Salt Cake Prod page 223
Appls of Sensors & Modeling in Materials Proc I page 4
Appls of Sensors & Modeling in Materials Proc II page 39
Appls of Sensors & Modeling in Materials Proc III page 80
Appls of Sensors & Modeling in Materials Proc IV page 119
Phys Metall Fund & Appl (GA) page 27
Non-linear Fracture in Brittle Crystalline Solids I page 61
Non-linear Fracture in Brittle Crystalline Solids II page 104
Non-linear Fracture in Brittle Crystalline Solids III page 142
Innovations in Aluminum I page 171
Innovations in Aluminum II page 207
Int Symp on Rhenium and Re Alloys XI page 235
IntSympon Rhenium and ReAlloys I page 20
IntSympon Rhenium and ReAlloys II page 55
Int Symp on Rhenium and Re Alloys IV page 135
Int Symp on Rhenium and Re Alloys V page 172
Int Symp on Rhenium and Re Alloys VIII page 209
Int Symp on Rhenium and Re Alloys IX page 232
Cast Shop Technology VI page 161
Metallurgy of Less Common Metals page 214
Microstructure Prop Relationships: Corrosion and Deformation I (GA) page 177
Aqueous Processing (GA) page 194
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IntSympon Rhenium and Re Alloys III page 97
----Tutorial Luncheon Lecture 12-1 :30 pm
AM
Appls of Sensors & Appls of Sensors & Modeling in Materials Modeling in Materials ProcV ProcVI page 154 page 193
Microstructure Prop Relationships: Corrosion and Deformation II (GA) page 179
1997 TMS ANNUAL MEETING & EXHIBITION FEBRUARY 10-13, 1997 MONDAY FEBRUARY 10 AM
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Recent Advances in Fracture VI page 216
Materials & Technologies for Microelectronics I page 24
Materials & Technologies for Microelectronics II page 60
Low Energy Beam Proc in Electronic Materials I page 100
Low Energy Beam Proc in Electronic Materials II page 138
Low Energy Beam Proc in Electronic Materials III page 175
Low Energy Beam Proc in Electronic Materials IV page 212
High Temp Superconductors I page 16
High Temp Superconductors II page 50
High Temp Superconductors III page 93
High Temp Superconductors IV page 132
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Adv in Coating Technologies I page 1
Adv in Coating Technologies II page 36
Adv in Coating Technologies III page 75
Adv in Coating Technologies IV page 114
Adv in Coating Technologies V page 150
Adv in Coating Technologies VI page 189
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Lt Weight Alloys
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Lt Weight Alloys
Hume Rothery Symposia on Thermodynamics of Alloy Formation I page 53
Hume Rothery Symposia on Thermodynamics of Alloy Formation II page 95
Hume Rothery Symposia on Thermodynamics of Alloy Formation III page 133
Spray Forming Exp, Analysis & Appls I page 183
Spray Forming Exp, Analysis & Appls II page 217
Spray Forming Exp, Analysis & ApplsIII page 240
Chem & Phys of Nanostructures II page 43
Chem & Phys of Nanostructures III page 85
Chem & Phys of Nanostructures IV page 124
Chem & Phys of Nanostructures V page 162
Chem & Phys of Nanostructures VI page 201
Chem & Phys of Nanostructures VII page 228
Fund of Gamma Ti Aluminides I page 13
Fund of Gamma Ti Aluminides II page 47
Fund of Gamma Ti Aluminides III page 91
Fund of Gamma Ti Aluminides IV page 129
Fund of Gamma Ti Aluminides V page 168
Fund of Gamma Ti Aluminides VI page 205
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Syn of Lightweight Metallic Materials I page 34
Syn of Lightweight Metallic Materials II page 73
Syn of Lightweight Metallic Materials III page 112
Syn of Lightweight Metallic Materials IV page 148
Syn of Lightweight Metallic Materials V page 186
Syn of Lightweight Metallic Materials VI page 220
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Structure and Properties of Internal Interfaces I page 32
Structure and Properties of Internal Interfaces II page 72
Structure and Structure and Properties of Internal Properties of Internal Interfaces III Interfaces IV page 110 page 147
Structure and Properties of Internal Interfaces V page 184
Structure and Properties of Internal Interfaces VI page 219
Design & Reliability of Solder & Solder Interconnects I page 9
Design & Reliability of Solder & Solder Interconnects II page 44
Design & Reliability of Solder & Solder Interconnects III page 88
Design & Reliability of Solder & Solder Interconnects IV page 126
Design & Reliability of Solder & Solder Interconnects V page 165
Design & Reliability of Solder & Solder Interconnects VI page 202
Design & Reliability of Solder & Solder Interconnects VII page 229
Structure Prop of Bulk Amorphous Materials I page 31
Structure Prop of Bulk Amorphous Materials II page 71
Structure Prop of Bulk Amorphous Materials III page 109
Structure Prop of Bulk Amorphous Materials IV page 146
Automotive Alloys I page 157
Automotive Alloys II page 196
Automotive Alloys III page 225
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High Temp Superconductors V page 170
1------
Institute of Metals Lecture 12:00 noon
for Aerospace Appls V page 173
for Aerospace AppisVI page211
Syn of Lightweight Metallic Materials VII page 241
1997 TMS ANNUAL MEETING & EXHIBITION FEBRUARY 10-13,1997 MONDAY TUESDAY WEDNESDAY FEBRUARY 10 FEBRUARY 11 FEBRUARY 12
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Adv in Electrically Conductive Materials I page 2
Adv in Electrically Conductive Materials II page 37
Adv in Syn & Proc Met & Ceramic Matrix Comp I page 76
Adv in Syn & Proc Met & Ceramic Matrix Comp II page 115
Adv in Syn & Proc Met & Ceramic Matrix Comp III page 151
Adv in Syn & Proc Met & Ceramic Matrix Comp IV page 190
Evolution & Adv Char of Thin Film Micro I page 12
Evolution & Adv Char of Thin Film Micro II page 46
Evolution & Adv Char of Thin Film Micro III page 90
Evolution & Adv Char of Thin Film Micro IV page 128
Evolution & Adv Char of Thin Film Micro V page 167
Evolution & Adv Char of Thin Film Micro VI page 203
Successful Univ-Ind Linkage/Global Economy I page 33
Successful Univ-Ind Linkage/Global Economy II page 73
Defining Core Materials Curriculum I page 86
Defining Core Materials Curriculum II page 125
Inc Imp Cu/Ni Smelting: Tech Econ I page 187
Exemplary Practice in the Extractive Metallurgy of Cu page 204
MONDAY FEBRUARY 10
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Materials Coatings & Pro Imp Reliability II page 57
Materials Coatings & Pro Imp Reliability III page 102
Materials Coatings & Pro Imp Reliability IV page 138
Materials for Spallation Neutron Sources I page 59
Materials for Spallation Neutron Sources II page 102
Materials for Spallation Neutron Sources III page 140
Inter Symp Proc & Handling of Powder Dusts II page 53
Inter Symp Proc & Handling of Powder Dusts III page 96
Inter Symp Proc & Handling ofPowder Dusts IV page 134
Shaping & Forming of High Performance Powder Prod I page 70
Shaping & Forming of High Performance Powder Prod II page 108
Shaping &Forming of High Performance Powder Prod III page 145
Rare Earths Science Tech Applications II page 63
Rare Earths Science Tech Applications III page 105
Rare Earths Science Tech Applications IV page 143
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Rare Earths Science Tech Applications I page 28
WEDNESDAY FEBRUARY 12 AM
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THURSDAY FEBRUARY 13 AM Adv in Syn & Proc Met & Ceramic Matrix Comp V page 222
Update of the Practice of Cu Elect Bleed I page 243
THURSDAY FEBRUARY 13 AM
Materials for Spallation Neutron Sources IV page 175
Rare Earths Science Tech Applications V page 180
MONDAY: McClintock Luncheon
Time: 12:00 noon
Room: Grand Ballroom C
Location: Clarion Plaza Hotel
TUESDAY: EPD Luncheon EPD Lecture
Time: 12:00 noon Time: 1:45 pm
Room: Grand Ballroom D Room: Grand Ballroom C
Location: Clarion Plaza Hotel Location: Clarion Plaza Hotel
WEDNESDAY: Light Metals Luncheon
Time: 12:00 noon
Room: Grand Ballroom D
Location: Clarion Plaza Hotel
1997
TMS
Minerals' Metals' Materials
ANNUAL MEETING
TECHNICAL PROGRAM 9:45am
ADVANCES IN COATINGS TECHNOLOGIES II: SESSION I: Sponsored by: MDMD Surface Modification & Coatings Technology Committee Program Organizers: C.R. Clayton, State University of New York at Stonybrook, College of Engineering and Applied Sciences, Stony Brook, NY 11794-2200; J.K. Hirvonen, US Army Materials Technology Lab., Arsenal St., Watertown, MA 02172; A.R. Srivatsa Monday, AM February 10, 1997
Room: 315B Location: Orlando Convention Center
Session Chairperson: J.K. Hirvonen, US Army Materials Technology Lab., Arsenal St., Watertown, MA 02172
8:35 am THE DARPA PROGRAM IN ADVANCED THIN FILM COATING TECHNOLOGY: Lawrence H. Dubois, Thomas J. Moran, Defense Sciences Office, Defense Advanced Research Projects Agency, Arlington, VA Corrosion and wear of mechanical and structural components and systems cost U.S. Industry and the military millions of dollars every year and leads to excess waste, decreased product reliability, and poor worker safety. Unfortunately, the surface preparation, application and use of most coatings to protect to protect these components leads to the generation of significant quantities of hazardous wastes which are subsequently released to the air, water and land. Through the development of new, more advanced corrosion and wear resistant coating systems and/or surface preparation techniques, the DoD and its suppliers can not only minimize the environmental impact of these materials, but improve performance and decrease costs. The DARPA program in advanced thin film coatings is developing innovative technologies to eliminate volatile organic compounds, heavy metals and other hazardous waste materials in the manufacture, application and maintenance of high performance wear, fatigue and corrosion resistant coatings of utility to the 000.
9:10am ADVANCES IN SURFACE TECHNOLOGY IN RUSSIA: Anthony J. Perry " Jesse N. Matossian', Michael O. Thompson 3 ; 'ISM Technologies, San Diego, CA; 'Hughes Research Labs, Malibu, CA; 3Cornell University, Ithaca, NY Since the removal of the Berlin Wall and the changes in the relationships between the former Soviet Union with the rest of the world, a great deal of information has become available on their technology. Developments in some areas appear to have outpaced those in the West, specifically in the application of ion beams to surface modification. The present authors have had the opportunity to attend workshops in Russia and to visit laboratories. In the present work, a report is given on some of the technologies reviewed there and which are now becoming available to the West. These include novel designs in the fields of cathodic arc sources and gas ion sources, and intense ion and electron beams. These technologies will be presented.
THE JET DEPOSITIONTM PROCESS: NEW TECHNIQUES AND AP· PLICATIONS: Brett Halpern, Jet Process Corporation, 24 Science Park, New Haven, CT 06511 Development of the "sonic jet sources in low vacuum" theme enables the Jet Vapor DepositionThI process UVDTM) to make a wide range of thin film materials. Thus, we have developed jet sources, driven in the O.l-lOtorr range by mechanical pumps, for deposition of metals, semiconductors, oxides, nitrides, alloys and guest-host materials in multicomponent and multilayer form. These sources combine high rate, high efficiency, and low temperature operation with excellent control of microstructure. For example, we recently described and patented an "electron-jet, or e-jetThl "source, which combines metal thermal vaporization with an intense thermionic plasma and allows high rate deposition of metals, oxides and nitrides coupled with simultaneous ion bombardment at high flux and low energy. JVD's versatility opens new approaches to problems in electronic, automotive, aerospace, corrosion resistance and optical applications. In this talk we review the principles of JVD, new jet source developments, JVD's advantages over conventional CVD and PVD and recent commercial applications.
10:20 am BREAK 10:30 am DoD ACTIVITIES IN ION BEAM PROCESSING: James K. Hirvonen, Metals Research Branch, U.S. Army Research Laboratory,APG, MD 210055069 The use of energetic ion beams for beneficially modifying the surface sensitive properties of critical military material has been pursued within DoD now for almost two decades demonstrating improved material properties including increased wear-, fatigue-, corrosion-, and oxidation-resistance. High dose ion implantation has been demonstrated to be technically suitable for extending the lifetime of precision aerospace bearings (U.S. Navy) and specific cutting tools (U.S. Army). Ion beam assisted deposition(ffiAD) processing has increased both the number and the variety of DoD applications, including robust optical coatings and coatings for wear, corrosion and fatigue improvements. A 000 program exploring these benign, dry, ion beam techniques for supplanting the wet CrlCd electroplating processing is currently underway at the National Defense Center for Environmental Excellence [Johnstown, PAj. This program includes the scheduled installation [Fall 96j of a large ion beam system for the processing of selected DoD components. The status of this program and other recent DoD ion beam efforts will be discussed.
11:05 am SURFACE PROCESSING BY GAS CLUSTER ION BEAMS: Allen Kirkpatrick, Epion Corporation, Bedford, MA 01730 Clusters consisting of hundreds or thousands of weakly bound atoms can be formed from various gases by expanding the gas through a small nozzle into high vacuum. The clusters can be ionized and subjected to acceleration potentials so as to produce beams of cluster ions which possess high total energy, mass and momentum in combination with low energy per constituent atom. Cluster ion beams have been shown to be capable of producing processing effects which have not been available with monomer ions. A number of prospective applications for gas cluster ions have been identified and commercial gas cluster ion beam equipment is now being developed. This paper will review the current status of gas cluster ion technology and will include discussion of methods for generation of the gas cluster beams, kinetics of the interactions of cluster ions with solid materials, anticipated applications and available equipment.
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cation disorder in the films. We have observed a strain stabilized metal-insu·· lator transition in epitaxial Sr,.,Ca xRu0 3 thin films deposited on (l00) SrTiO, substrates that differed in crystalline quality. The growth mechanisms of the films and their correlation with the crystalline quality of the substrates is discussed. We have also grown epitaxial planar SNS heterostructures YBCOI L~.4Sr1.6Cus02JYBCO. We will discuss the microstructures, junction properties and the origin of the interface resistance between YBCO and La6.4Sr1.6CU S020'
11:40 am COMPARISON OF DEPOSITION TECHNOLOGIES FOR ION ASSISTED COATINGS: A.J. Armini, S.N. Bunker, L.A. Stelmack, Implant Sciences Corporation The current ion assisted coating methods and the corresponding equipment are compared, for depositing a variety of wear and/or corrosion resistant coatings. Ion beam assisted deposition (lBAD), unbalanced magnetron sputtering, and cathodic arc processes were used to deposit coatings of amorphous diamond, chromium, and noble metals for various applications in the aerospace, biomedical, and industrial markets. The three techniques were compared with respect to coating uniformity, deposition rate, adhesion, and microstructure. Coatings were evaluated for hardness, adhesion, smoothness, sliding wear, and friction coefficient. Coating-substrate adhesion was measured using the diamond scratch test. Wear and friction were measured against several opposing materials, using a high speed, high temperature pin-on-disk instrument. Scale-up issues and the suitability of each technology for various production applications will be discussed.
9:30 am INVITED FUNDAMENTAL INVESTIGATIONS OF CADMIUM STANNATE THIN FILMS: T.J. Coutts, w.P. Mulligan, X. Wu, National Renewable Energy Laboratory, Golden, CO 80215 We are investigating a variety of novel transparent conductive oxides, including cadmium stannate (CdzSn04 ), cadmium indate (CdInp.), zinc stannate (Zn2Sn04 and ZnSn03), and zinc indium oxide (Zn2Inps)' To date, the cadmium stannate films have shown the highest conductivity, with resistivities as low as 1.3x10" ohm-cm. Films have been fabricated with sheet resistances as low 2 ohm/sq., while maintaining approximately 80% transmittance across the visible and near infrared. The conductivity of the films is high because of both high electron concentration and relatively high electron mobility. One possible explanation for the high mobility is that the electron effective mass is unusually low. Direct measurement of the effective mass by cyclotron resonance is not feasible due to the extremely short electron scattering times characteristic of these highly defective materials. Instead, we have estimated effective mass by Drude modelling of optical reflectance and transmittance data, and by analysis of a combination of electron transport measurements, including resistivity, Hall effect, thermopower, and transverse NemstEttingshausen effect. Cadmium stannate films with a range of carrier concentrations were fabricated, and their optical and transport properties were measured. We will present the results of our comparative analysis of carrier effective mass by these two independent methods. Possible conduction band curvature, and carrier scattering time and mechanisms will also be reported. The implications for design of novel transparent conductive oxides will be discussed.
ADVANCES IN ELECTRICALLY CONDUCTIVE MATERIALS I Sponsored by: EMPMD Electronic Packaging and Interconnection Materials Committee Program Organizers: S. Jin, Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974; M.E. Fine, Northwestern University, Evanston, IL 60208;K.N. Tu, UCLA, Los Angeles, CA 90095 Monday, AM February 10, 1997
Room:340B Location: Orlando Convention Center
Session Chairperson: S. Jin, Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974
8:30 am INVITED ELECTRODE MATERIALS FOR LITIDUM BATTERIES AND FUEL CELLS: A. Manthiram, Center for Materials Science and Engineering, ETC 9.104, The University of Texas at Austin, Austin, TX 78712
10:00 am BREAK 10:20 am INVITED ELECTRICALLY ACTIVE POLYMERS: M. E. Galvin, Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974
Electrically conducting metal oxides find potential applications in electrochemical systems such as batteries and fuel cells. For example, several lithium insertion compounds are used as cathodes in rechargeable lithium batteries. However, the battery performance and cyclability of the cathodes are controlled partIy by the microstructure and morphology, which in turn are influenced by the methods of synthesis and processing used. A novel approach involving the reduction of aqueous metallate solutions with aqueous alkali metal borohydrides at ambient temperatures to obtain amorphous or nanocrystalline transition metal oxide electrodes will be presented. The electrode performance of, for example, amorphous or nanocrystalline V02, cr02' Mo02, and LiMnp4 will be discussed. In addition, the design and synthesis of perovskite-based metal oxides that exhibit mixed electronic and ionic conductivity will be presented. These mixed conductors are attractive not only as electrode materials for solid oxide fuel cells but also for oxygen separation membranes and catalysts.
It has been known for two decades that polymers with extended conjugation could be rendered highly conductive by doping, that is, by oxidizing or reducing the polymer chain. The commercialization of these polymers has, however, been limited by their poor chemical stability in the doped form. More recently these polymers have shown promise when used in their undoped forms in LEDs, light emitting diodes, or in thin film transistors. This talk will cover the recent developments in these two areas and describe the scientific challenges which still remain.
10:50 am INVITED NOVEL ANISOTROPIC CONDUCTORS THROUGH THE DESIGN OF COMPOSITE STRUCTURES: S. Jin, Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974 Anisotropic electrical conductivity with many orders of magnitude change along different directions can be obtained by the design of novel, composite structures. Materials with such characteristics are useful for a variety of electronic applications including ultra-high density circuit interconnections, 3-D packaging, and solder-free interconnection. Optically transparent but electrically conductive medium can also be made via composite route. Novel composite structures with vertically aligned metal elements in ceramic or polymer sheets will be described. Materials fabrication process, electrical properties and reliability issues will also be discussed.
9:00 am INVITED EPITAXIAL TmN FILMS AND HETEROSTRUCTURES OF METALLIC OXIDES FOR DEVICE APPLICATIONS: C.B. Earn, Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC27708 For many electronic device applications, it is necessary to have epitaxial growth of metallic oxide thin films in a single heterostructure. We have grown epitaxial thin films of Sr1.,Ca.Ru03 and La".4Sr1.6Cug020 in-situ by 90 degree offaxis sputtering. These metallic oxides are pseudo-cubic perovskites, which could be ideal electrodes for ferroelectric devices, and normal metal barriers for SNS junctions in integrated superconducting devices. However, the properties of epitaxial thin films of the metallic oxides may be quite different from the corresponding bulk materials because of the existence of strain and
11:20 am OPTICAL STUDIES FOR THE CHARACTERIZATION OF CONDUCTING POLYMERS: L.M. Abrantes, CECUL, Dept. Qumica, FCUL, B1oco C 1-5 piso, 1700 Lisboa, Portugal; J.P. Correia, INET!, Dept. de Energias Renovaveis, 1699 Lisboa Codex, Portugal
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The properties of conducting polymers have stimulated much interest in many fields of research and considerable effort has been directed towards reliable characterization of the envisaged properties for commercial applications. Apart from polyacetylene (PA) the major existing conducting polymers can be electrochemically synthesized and this encouraged the use of conventional electrochemical methods coupled to other techniques to study the electropolymerization and insulator!conductor conversion of these new materials. The purpose of this paper is to give an overview of the ability of optical methods to provide useful information on the properties of electronically conducting polymers. Three techniques will be focused and their contribution illustrated considering different systems: I) The principles of the Probe Beam Deflection (also known as Mirage Effect) and respective data for polyaniline (PANI) systems discussed. ii) Recent applications of Photocurrent Spectroscopy are reviewed and photoeffects displayed by poly-3methylthiophene (P3MeTh) analysed. iii) The information on structural changes during electropolymerization and doping processes, which can be provided by ellipsometry evidenced by the study of PANI, P3MeTh and polypyrrole.
efficiency upon the duct exhaust velocity was determined for the HS S~derberg cells using this method.
8:55 am COS, CS, AND SO, EMISSIONS FROM PRE-BAKED HALL HEROULT CELLS: Frank M. Kimmerle, Luc Noel, Alcan International Ltd., Arvida Research and Development Centre, P.O. Box 1250, Jonquiere, QC, G7S-4K8, Canada; John T. Pisano, Unisearch Ass. Inc., 222 Snidercroft Rd., Concord, ONT, L4K IB5, Canada Measurements of CO" CO, COS and CS, emissions in collected gas samples by GC-MS and of SO, by ion chromatography of scrubber solutions allowed us to complete a carbon and sulphur mass balance for PI55 pre-bake electrolysis cells. COS and CS, emissions were confirmed by continuous analysis using tunable diode laser absorption spectrometry of the flue cases from 64 cells over a two day period. While the volume mixing ratios of COS and CS, of the flue gases agree with those reported recently for a German prebake smelter, the specific emissions were found to be considerably lower.
9:20am
11:40 am HYDROSTATICALLY EXTRUDED COPPER-NIOBIUM SPARK ERODED POWDER: M.A. Hill', J. E Bingert', EE. Spada', A.E. Berkowitz', S.A. Bingert', 'Los Alamos National Laboratory, Los Alamos, New Mexico 87545, 'Center for Magnetic Recording Research, University of California at San Diego, La Jolla, CA 92093
PERFLUOROCARBON (PFC) GENERATION IN LABORATORYSCALE ALUMINUM REDUCTION CELLS: Steen Nissen, Donald R. Sadoway, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139-4307 The generation of CF4 and C,F6 is being studied in a laboratory-scale aluminum reduction cell. During electrolysis in well behaved cells and in cells on anode effect, anode gases have been analyzed by gas chromatography (GC) on-line. Process parameters have been systematically varied to determine how PFC generation depends upon anode material (industrial pre-bake and S~derberg), bath ratio (l.45, 1.15 and 0.56), LiF concentration (0 and 2.7%), current density (0.7 A cm-' and higher), and temperature (970 and 800°C). Measurements agree with those reported for industrial cells with respect to total PFC level as well as the ratio of CF4 to C,F6' The main factor determining PFC concentration appears to be the anodic overvoltage. The functional relationship between the rate of PFC generation and anodic overvoltage is derived from the current-overpotential equation. Research sponsor: U.S. Environmental Protection Agency, Atmospheric Pollution Prevention Division.
High strength, high conductivity copper-niobium wire is a promising conductor wire for use in pulsed high field magnets. Due to the high melting point of niobium, it is difficult to produce an ingot with a fine, homogeneous structure. One possibility for reducing the scale of the cast structure, improving the homogeneity of the ingot, and enhancing the strength at a given level of deformation strain is to use rapid solidification techniques, such as powder processing, to fabricate the Cu-Nb ingot. Both melt spinning and gas atomization of Cu-Nb are difficult due to problems associated with thermal shock of components, such as crucibles and stopper rods. Spark erosion provides a method for powder production without the use of components which may crack under thermal stresses. Furthermore, in the spark erosion process quench rates exceeding I ()6 K/s from temperatures above I ()4 K promote formation of fine particles with homogeneous composition. Spark eroded Cu-lO vol % Nb powder has been consolidated by cold pressing and subsequently hydrostatically extruded to form 2.5 cm diameter rod with a yield strength of 500 MPa and a conductivity of 85% lACS at a reduction of £=2.6.
9:45 am REDUCTION OF THE CF4 EMISSIONS FROM PRE-BAKED HALL HEROULT CELLS: Frank M. Kimmerle, Gilles Potvin, Alcan International Ltd., Arvida Research and Development Centre, P.O. Box 1250, Jonquiere, QC, G7S-4K8, Canada; John T. Pisano, Unisearch Ass. Inc., 222 Snidercroft Rd., Concord, ONT, L4K IB5, Canada
ALUMINIUM REDUCTION TECHNOLOGY I: Environmental
It has been established that CF4 and C,F6 are given off from the Hall-Heroult
electrolysis cells during so-called anode effects. The introduction of a novel alumina feeding and cell operation algorithm in the Grande Baie smelter operating with PI55 pre-bake electrolysis cells, has dramatically reduced the anode effect duration and anode effect frequency. The implementation of the new cell control logic constituted a unique opportunity to compare data from some two hundred events before and after commissioning on identical cells. Using tunable diode laser absorption spectrometry we measured PFC emissions from individual anode effects with a temporal resolutions of as little as 8 seconds. This communication will describe the experimental set-up, present the decrease in PFC emissions attained, discuss the CF/C,F6 ratios observed and compare the data observed with model predictions.
Sponsored by: LMD Aluminum Committee Program Organizer: Harald A. 0ye, Institute of Inorganic Chemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway Monday,AM February 10, 1997
Room: 230A Location: Orlando Convention Center
Session Chairperson: Michel Reverdy, Aluminium Pechiney, Pechiney-Balzac, France
8:30am CELL HOODING EFFICIENCY MEASUREMENTS FOR HS S0DERBERG CELLS: Alton T. Tabereaux, Jim Brown, Ivan Eldridge, Reynolds Metals Company, Manufacturing Technology Laboratory, 3326 East 2nd Street, Muscle Shoals, AL 35661
10:10 am BREAK 10:30 am POTROOM COMPARISON TRIAL OF A LASER HF MEASURING INSTRUMENT AND AN INTENSIVE AIR SAMPLING ARRAY OVER A 400 M PATH: D.L. Death, J.E. Eberhardt, R.P. Read, C.A. Rogers, CSIRO Division of Minerals, Private Mail Bag #5, Menai, NSW, 2234 Australia; M. Atkinson, Comalco Research Center, P.O. Box 316, Thomastown, Vic. 3074, Australia; D. Collins, Alcoa of Australia Ltd., Point Henry Works, P.O. Box 460, Geelong, VIC. 3220, Australia; K. Whiteley, Tomago Aluminium Co. Ltd., P.O. Box 405, Raymond terrace NSW, 2324, Australia
A method has been developed for measuring the gas capture efficiency of volatile gas emissions for the cell hooding system of HS S~derberg ceUs. No prior method for measuring the gas capture efficiency for HS S~derberg cells has been reported to date. This paper presents the newly developed procedures, techniques and results measured during plant tests for the gas capture efficiency of 92 kA HS S~derberg cells equipped with an improved cell hooding system to reduce plant emissions. The dependency of the gas capture
The laser hydrogen fluoride measuring instrument described at TMS'95 was
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compared with an optimised eighty-fold array of air sampling cassettes over a 400 m path in a potroom of the Tomago (NSW) aluminium smelter. Thirteen one-hour comparison trials were performed at average HF concentrations over the range 0.07-3.7 mgINm3. For the twelve concentrations up to 2.0 mgINm3 the cassette array average and the laser average correlated with a slope of 0.93 and a regression coefficient r2 = 0.98. For the nine points up to 1.5 mgINm3 the slope was 1.02 and the regression coefficient r2= 0.99. As configured during the comparison trial the laser instrument did not correctly indicate the 3.7 mgINm3 HF concentration due to insufficient signal to noise ratio. The correlation between array and laser was considered very good. The technique is being commercialised. The contributions of Frank Fleer of AirWaterNoise Ltd to this work are gratefully acknowledged. This work was partly supported by the Australian Aluminium Council.
APPLICATIONS OF SENSORS AND MODELING TO MATERIALS PROCESSING I
Sponsored by: Jt. EPD/MDMD Synthesis, Control, and Analysis in Materials Processing Committee and EPD Process Fundamentals Committee Program Organizers: S. Viswanalhan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; R.G. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487; J.C. Malas, Wright-Patterson AFB, OH 45433-6533; L.L. Shaw, Dept. of Metallurgy & Materials Science, Univ. of Connecticut, Storrs, CT 06269-3136; R. Abbaschian, P.O. Box 116400, 132 Rhines Hall, Univ. of Florida, Gainesville, FL 32611-6400
Monday, AM February 10, 1997
10:55 am THE MEASUREMENT OF GASEOUS FLUORIDE IN THE ALUMINIUM INDUSTRY: John M. Jones, Anglesey Aluminium Metal Ltd., Penrhos Works, P.O. Box 4, Holyhead, Gwynedd, LL65-2UJ, United Kingdom
Room: 232A Location: Orlando Convention Center
Session Chairs: R.G. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487; D.J. Fray, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 30Z, United Kingdom
The introduction of integrated Pollution Control (IPC) by means of the Environmental Protection Act (EPA 90), has brought with it regulatory requirements for operators of industrial processes in the U.K. to undertake continuous monitoring of gaseous atmospheric releases. In response to these changes Anglesey Aluminium Metal Limited (AAM) has chosen to install Tunable Diode Laser Spectroscopy (TDLAS). This method, operating in the Middle Infra Red region (MIR), is gaining increased acceptance as the choice for trace gas measurement where sensitivity, specificity, and fast response are required. This paper focuses on this change to the gaseous fluoride monitoring activities at AAM with particular attention to stack monitoring.
8:30am STABILITY ANALYSIS OF MICROSTRUCTURE EVOLUTION PROCESSES: WM. Mullins, Wright Laboratory, WLIMLlM-TMCI, Bldg. 653, 2977 PSt., WPAFB, OH 45433-7746; R.D. Irwin, E.A. Medina, Department of Electrical and Computer Engineering, Stocker Center, Ohio University, Athens, OH 45701 Various stability criteria are introduced and thermo-kinetic models for metallurgical processes are used as concrete examples for evaluation. Kinetic criteria for the process of dynamic recrystallization are proposed. These criteria are compared to the non-equilibrium thermodynamic approaches discussed in the literature. The application of macroscopic stability criteria to materials processing is then discussed.
11:20 am IMPROVED EFFICIENCIES IN THE DRY SCRUBBING PROCESS: Geir Wedde, ABB Environmental, P.O. Box 6260 Etterstad, 0603 Oslo, Norway An advanced process for removal and recovery of fluorides and particulates from the aluminium reduction pot gas has been developed and tested in pilot plant prior to full scale installation. The dry scrubbing process is arranged in two stages with a counter-current flow of the alumina allowing for the reactive fresh alumina at the tail end of the process. The benefits and features of this concept include high process flexibility with stable and improved performance on removal of fluorides, reduced pressure drop and low particulate emission by optimized filter design and operating performance, and improved compactness through design and equipment developments.
8:55 am STATISTICAL ANALYSIS OF INTERFACE DYNAMICS IN NONSPHERICAL MORPHOLOGIES: S.p. Marsh, Code 6325, Naval Research Laboratory, Washington, D.C. 20375-5000; M.E. Glicksman, Rensselaer Polytechnic Institute, Troy, NY Complex interfaces can be described as a distribution of interfacial patches, each having a differential area. The patches are fully characterized by a mean curvature, a dimensionless shape factor, and an extensive variable such as solid angle or area. Using this approach, a statistical theory of Ostwald ripening has been extended to describe the diffusion-limited coarsening of nonspherical convex interfaces. Coarsening rate constants are calculated as a function of both the precipitate volume fraction and the geometric shape factor. Application of these results to ripening of ellipsoidal precipitates and other morphologies will be discussed.
11:45 am TGT RI - A NOVEL REACTOR / FILTER CONCEPT FOR DRY SCRUBBING: B. Cloutier, Procedair Industries Inc., 625 President Kennedy, Montreal, Quebec, Canada H3A IK2; Ph. Dumortier, B. Caratge, Procedair SA, 25-27 Boulevard de la Paix, 78951 St. Germain en Laye Cedex, France The fluorine emissions from modern PFPB pots have led to a requirement to further improve gas scrubbing efficiency. This improvement has been achieved without any detrimental effect on scaling or attrition of alumina. Economic factors create a further technical challenge of reducing capital cost and lowering energy consumption. A novel process called the TGT-RI which combines an innovative reactor concept integrated in a new generation of fabric filter fully responds to the new requirements of aluminium producers. Several years of exhaustive tests have been conducted on gases emitted by large pots to develop the TGT filter and then the TGT-RI concept of integrating the reactor within the filter unit. The paper will incorporate a comprehensive set of test results. A descriptive of the fust industrial applications on pot gases and baking furnaces is presented.
9:20am ULTRA FINE PRECIPITATES IN REACTOR PRESSURE VESSEL STEELS INVESTIGATED BY MONTE CARLO SIMULATIONS: STRUCTURE, COMPOSITION, AND MORPHOLOGY: c.L. Liu, G.R. Odette, B.D. Wirth, and G.E. Lucas, Dept. of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106 Ultra fine scale precipitates are the leading cause to the irradiation embrittlement of reactor pressure vessel (RPV) steels and may limit the continued operation or extended life of a number of nuclear power plants around the world. Tremendous effort in studying these precipitates has been made using various experimental techniques such as small angle neutron scattering (SANS) and atom probe field ion microscope (APFIM). However, detailed identity and characteristic of the precipitates 0 atomic scale are not well known. We propose a self-consistent model, combining advanced thermodynamics, small angle neutron scattering measurements, and Lattice Monte Carlo simulations, to examine detailed identity and characteristic of the ultra fine precipitates on atomic scale in Fe-based mUlticomponent systems Fe-Cu-Ni-Mn and Fe-Cu-Ni-Mn-Si. A systematic parametric study using both the metallur-
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gical and simulation variables is carried out. Interaction parameters in an extended regular solution treatment, composition, and temperature as the metallurgical variables, and starting configurations, sizes of simulation cells, and simulation duration as the simulation variables, are exercised. The results from the simulations are in good agreement with those from SANS and APFIM.
almost any axial forging process. A wide data base is experimentally obtained, which validates the model. This dimensional analysis is an alternative to the traditional methods for calculating the stresses in metal forming. 11:10 am MODELING OF LIQUIDUS TEMPERATURE AND ELECTRICAL CONDUCTIVITIES OF MANGANESE SMELTING SLAGS BY THE USE OF NEURAL NETS: M.A. Reuter, Faculty of Mining and Petroleum Engineering, Delft University of Technology, Delft, The Netherlands, R H. Eric, A.A. Hejja, School of Process and Materials Engineering, University of the Witwatersrand, Johannesburg, Private Bag 3, WITS 2050, South Africa
9:45am OBSERVATION AND CALCULATION OF MARANGONI CONVECTION INDUCED THERMALLY IN A MOLTEN SALT: T. Takasu, 1.M. Toguri, Dept of Metallurgy and Materials Science, University of Toronto, 184 College Street, Toronto, Ontario, Canada, M5S lA4; H. Itou, T. Nakamura, Dept of Materials Science & Engineering, Kyushu Institute of Technology, Secsui-cho 1-1, Tobata-ku, Kitakyushu, 804 Japan
Liquidus temperature and electrical conductivity data measured on synthetic slags were modeled by the use of neural nets(NN). In this work the applied multilayer feedforward NNs were trained by a conjugate-gradient optimization for which a three layer formulation was used. Very good fits were obtained for both the liquidus temperature and the conductivity data. The synthetic slags were prepared from pure oxides to represent a wide range of compositions likely to be encountered in ferromanganese and silicomanganese smelting. The slag constituents were in the following range: MnO;5-30%, CaO;20-35%, MgO;5-15%, Si0 ;27-58%, AIP,;5%. Liquidus temperatures 2 varied from 1300°C to 1380°C and increased with increasing basicity ratio. The electrical resistivity of slags decreased with the increase of basicity ratio from 0.55 to 1.1 but above 1.1 basicity ratio the resistivity tended to increase depending upon the MnO content.
Marangoni convection has a large effect on materials processing since it remarkably promotes heat and mass transport near the free interface. In order to clarify the behavior of marangoni convection in a molten salt, observation and calculation of the thermal convection in a column held between a pair of Pt disks (2mm in diameter) which were fixed to hot thermocouples, were carried out. Calculated flow patterns and absolute values of fluid velocity agreed well with the observed results. When the temperatures of both disks were set equal and the height of liquid bridge was 2.4mm, four vortexes were generated on the longitudinal plane and typical velocity was 15mm1s. From the calculated isothermal lines the behavior of promotion of heat transport is obvious; fluid heated at the disks was conveyed to the free surface and fluid cooled at the surface was conveyed to the inner region. Increase in the height of column and/or increase in the absolute value of applied temperature difference lead to increase in fluid velocity lineally in this calculation range.
AQUEOUS ELECTROTECHNOLOGIES: PROGRESS IN THEORY AND PRACTICE I: Copper Electrowinning and Refining
10:10 am BREAK 10:20am MIXING PHENOMENA PERTINENT TO FERROALLOY REFINING USING WATER MODELS: G. Akdogan, R.H. Eric, School of Process and Materials Engineering, University of the Witwatersraind, Johannesburg, Private Bag 3, Wits 2050 South Africa
Sponsored by: EPD Aqueous Processing Committee, Copper, Nickel, Cobalt Committee, Lead, Zinc, Tin Committee and Precious Metals Committee Program Organizers: D.B. Dreisinger, University of British Columbia, Department of Metals and Materials Engineering, 309-6350 Stores Road, Vancouver, B.C., Canada; E. Ozberk, Sherrill International, Bag 1000, Fort Saskatchewan, AB, T8l 2P2, Mrs. S. Young, BHP Copper Inc., 2400 Oracle Road, Suite 200, Tucson, AZ. 85704; R.S. Kunter, Advanced Sciences Inc., 405 Urban Street, Suite 401, lakewood, CO 80228
Mixing phenomena in a bottom blown air-stirred one-seventh water model of CLU (Creusot-Loire Uddeholm) reactor was studied using three different configurations of straight circular nozzles fitted axially at the bottom of the vessel. The mixing time has been experimentally determined utilizing acid injection and pH measurements at various gas flow rates, bath heights and nozzle orientations in the presence and in the absence of a second phase. High air flow rates were utilized usually above the range of ordinary flow meters. During experiments the air flow rates varied from 0.OO599m'/sec to 0.01465m'/sec. An integral orifice plate assembly, which is coupled to two pressure transmitters, was constructed to calculate gas flow rates from pressure readings. Experimental results reveal that the mixing time decreases with increasing gas flow rate. A critical gas flow rate exists after which the mixing time tends to increase for all tuyere configurations studied. For a given gas flow rate the mixing time increases non-linearly with increasing bath height. Off-center configuration gives slightly lower mixing times as compared to center configuration. The presence of an upper oil layer increases the mixing time significantly for all configurations showing its resistance to the recirculatory velocity of fluid near the surface of the bath. Under the very high flow rates employed in this investigation, it is found that the contribution of buoyancy to the total stirring energy density is very small, but its contribution increases with increasing bath height.
MondaY,AM February 10, 1997
Room: 231A location: Orlando Convention Center
Session Chairperson: Mrs. S. Young, BHP Copper Inc., 2400 Oracle Road, Suite 200, Tucson, AZ. 85704
8:30am EFFECTS OF FLUID VELOCITY OF ELECTROLYTE ON COPPER ELECTROREFINING: A. Tsubouchi, T. Nakamura, F. Noguchi, I. Iakasu, Kyushu Institute of Technology, Department of Materials Science and Engineering, Kitakyushu, Japan 804 A high current density operation is desired to improve the productivity in copper electrorefining. However, a lot of problems still remain such as passivation of anode, dendritic deposition of cathode and contamination of impurity elements during the high current density electrorefining of copper. To clear the problems mentioned above, effects of the fluid velocity of the electrolyte on the morphology of copper deposition on cathode and the passivation behaviour of anode have been investigated at various current densities in the present study. Although a granular appearance of the copper deposition was obtained with increasing the current density, it was depressed by an increase of the fluid velocity of the electrolyte. Then an uniform deposition on the cathode was also observed when the fluid velocity of it became higher. Further more, no passivation behaviour of anode could be found by high speed circulating the electrolyte even in the high current density operation.
10:45 am DIMENSIONAL ANALYSIS FOR PREDICTING THE STRESSES IN FORGING: T. Robert N., Congreso 128-A204, Col. La Joya, Del. Tlalpan, Mexico, D.F., 14090; 1. Navarrete M., 1. Ramirez V., G. Salas B., M. Noguez A., Departamento de Ing. Metalurgica, Facultad de Quimica, Universidad Nal. Autonoma de Mexico, Cuidad Universitaria, 04510 Mexico, D.F. The stresses required in an axial closed die forging are determined by the geometry of the blank and that of the die, the yield stress of the working material and the process variables like temperature, strain, strain rate, friction, etc. Five adimensional groups of the mentioned parameters are proposed. Like the Reynolds number, they permit the characterization and evaluation of
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8:55am
Electrochemical techniques are a valuable means of analyzing the passivation of commercial copper anodes. Electrochemical impedance spectroscopy (EIS) provides information concerning transport and reaction phenomena occurring at an electrode surface. Commercial copper anodes of varying compositions have been examined using EIS. Experiments were conducted in a flat cell with an electrolyte of 40 gil Cu2+ and 160 gil H,SP4 maintained at 65°C. Impedance spectra were obtained at the potentials characteristic ofthe open circuit voltage and the passive region for each anode. The spectra of the passivating films exhibited a flattened resistive/capacitive loop at middle to high frequencies and an inductive loop at low frequencies. An equivalent circuit utilizing an inductor-resistor series in parallel with the double layer capacitance and charge transfer resistance was adequate in modeling the impedance data. The influence of anodes impurities on the components of the equivalent circuit is discussed and correlated with a bilayer passivation model.
ENERGY SAVING IN COPPER ELECTROWINNING: C. Lupi, D. Pilone, Dip. ICMMPM, Universita di Roma "La Sapienza", V. Eudossiana, 18,00184 Roma, Italy The energy consumption, in the electro winning step of copper production by hydrometallurgical traditional process, generally represents more than 114 of the total energy requirement. The considerable saving can be achieved just in this step that requires about 8 GJ/tonne of the produced copper. To save energy the cell voltage, or more appropriately its anodic component, can be reduced: that is because the anodic voltage represents the main component of cell voltage and so it is responsible for the actual energy consumption in the copper sulphate electrowinning. In this work some ways are studied to lower the anodic voltage. First the cobalt ions were added to the sulphate solution in order to study the catalytic effect on oxygen discharge. Then lead alloys anodes (Pb-Ag, Pb-Sb-Ag and Pb-Ca) were used to promote a better oxygen evolution as a result of a different anodic surface. Their behaviour was compared with the Pb-Sb traditional ones. Finally, as already pointed out by several authors for zinc electro winning, ethylene glycol was employed as anodic depolarizer in order to verify its effectiveness in the case of copper electrowinning. Combining all the above-mentioned ways energy saving ranging from 20% to 27% is achieved. All the tests were carried out on a laboratory pilot-plant for long time to simulate the industrial conditions. The obtained copper deposits were observed by SEM to highlight their morphology and were also analyzed by spectrometer to verify their purity.
10:30 am SURFACE ROUGHENING OF ELECTROWON COPPER IN THE PRESENCE OF CHLORIDE IONS: E. Ilgar, P. Yu, T.I. O'Keefe, University of Missouri-Rolla, Department of Metallurgical Engineering and Graduate Center for Materials Research, Rolla, MO 65409-1170 A statistically designed screening test was carried out in the absence and presence of 20 ppm Cl· ions using a three factor, two-level factorial design in an electrolyte containing 36 gl" Cu 2+ and 150 gl" sulfuric acid. The independent variables evaluated were agitation, current density and temperature; their influence on surface roughness was determined. Using the data generated, a model expression was developed to allow estimation of surface roughness of the copper deposits. X-ray diffraction, scanning electron microscopy, cyclic voltamrnetry, electrochemical impedance spectroscopy and profilometer techniques were used in the evaluation. The copper deposited at current densities where activation was the primary control mechanism appeared similar in morphology whether stirring was used or not. The addition of 20 ppm Cl' ions to the electrolyte gave rougher deposits under the same conditions. In the mixed control regions, where mass transfer effects were initiated, considerably rougher and more dendritic deposits were obtained when CI' ions were present. Agitation was effective in reducing the copper surface roughness both in the apparent activation and mixed control regions in the presence of Cl' ions. The results of this study showed that 20 ppm Cl· polarized the copper deposition at low overpotentials but caused depolarization at higher overpotentials, and promoted roughening even where Cu2+ mass transfer was not a factor.
9:20am NUMERICAL COMPUTATION OF ANODIC SLIME BEHAVIOUR IN COPPER REFINING CELLS: A Filzwieser, A. Lackner, K. Hein, P. Paschen, Department of Nonferrous Metallurgy, University of Leoben, A8700 Leoben, Austria; K. Pachler, AVL List GmbH, A-8020 Graz, Austria The fluid flow in a copper refining cell is calculated three dimensionally, using the CFD-software package FIRE. The simulation is based on density variations in the boundary layer at the electrode surface. Calculations and LDA-measurements are in good correspondence. The actual glue concentration in the cell is calculated, too. Moreover, a two phase flow approach is developed, based on the "Discrete Droplet Model" to simulate the behaviour of anode slime during electrolysis. The position, velocity and diameter of each anode slime particle is described. The computations show the dependence of slime particle size distribution, density and electrolyte circulation rate on the possibility of being included in the cathode copper or collected at the cell bottom.
10:55 am THREE-DIMENSIONAL CALCULATION OF CURRENT DISTRIBUTION IN ELECTRODEPOSITION OF COPPER: Y.S. Choi, N.S. Kim, S.H. Jeon, T. Kang, Seoul National University, Department of Metallurgical Engineering, Seoul, Korea; R.I. Sohn, Seoul National University, Department of Mineral and Petroleum Engineering, Seoul, Korea
9:45am INFLUENCE OF THE ELECTROCRYSTALLIZATION INHIBITORS DURING COPPER ELECTROREFINING: A NEW EXPERIMENTAL APPROACH: J.-L. Delplancke, M. Degrez, C. Temrnerman, R. Winand, Universite Libre de Bruxelles, Metallurgy, CP165, 50 Av. F.D. Roosevelt, BI050 Brussels, Belgium
The thickness uniformity of electrodeposits depends largely on the current density distribution over the cathode. The current distribution is determined by the geometrical characteristics of the electrodes and the cell, the polarization at the electrode surface and the mass transfer in the electrolyte. The calculation of the current distribution is possible by various numerical techniques, among which the boundary element method (BEM) is considered to be most efficient. In this study the program for the calculation of 3-dimensional current distribution by use of the BEM with a linear element of trigonal type was developed and applied to the rectangular cathodes in copper electroplating. For simplicity the anode potential was assumed to be constant and the nonlinear polarization curves obtained from the potentiodynamic experiments were fitted to a linear equation over the range of current densities, 20 - 80 mAl cm'. The effect of the cell dimension and the anode shape on current distribution was simulated. The calculated values agreed fairly well with the measured values and the thickness uniformity could be improved by the proper combination of the cell geometry and the anode shape.
The influence of the copper electrocrystallization inhibitors (mainly thiourea, gelatin and chloride ions) is studied in a new fully automatic pilot plan. This paper describes the conception and the building of this plan. The plan is in hydrodynamic similitude with an industrial copper electrorefining plan. Three cells with forced electrolyte flow may be connected in parallel or in series on order to model the copper production cells. The electrolyte is characterized chemically and electrochemically before and after electrolysis. One day and one week long experiments are performed. The structure of the deposits is characterized by SEM, EDX and metallographic cross-sections. The new approach for the study of these inhibitors is firstly to reproduce the experimental conditions observed in the industry with the three additives present simultaneously in the electrolyte and secondly to study the influence of a slight modification of the concentration of one inhibitor, the others being present in the electrolyte with their industrial nominal concentrations.
10:10 am THE CHARACTERIZATION OF PASSIVATING FILMS ON COMMERCIAL COPPER ANODES USING IMPEDANCE SPECTROSCOPY: M.S. Moats, J.B. Riskey, S.C. Campin, University of Arizona, Copper Research Center, Material Science and Engineering Department, College of Engineering and Mines, Tucson, AZ
11: 20 am THE SOUTHERN PERU ILO REFINERY, DESIGN FEATURES, OPERATION AND IMPROVEMENT: F. Begazo, W.A. Enrico, Southern Peru Limited, 180 Maiden Lane, New York, NY 10038 Southern Peru Limited's 110 Refinery, the largest in Peru, began operations in
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1975 with a production capacity of 165,000 stpy. Southern Peru bought the Refinery from the state owned Minero Peru S.A. on June 1, 1994. The refinery processes blister from Southern Peru's lIo smelter. Blister copper is processed in an anode plant equipped with two 365 st. tilting reverberatory furnaces, a 26 mold casting wheel and an anode press machine. Copper is electrorefined in a tank house equipped with 768 commercial cells, 44 stripper cells and 40 liberator cells, utilizing two electrolyte circuits and a 21,000 ampere rectifier. During 1989 through 1994, a program for improving productivity was carried out by increasing the number of cells and increasing current density to the total rectifier capacity. As a result, a capacity of 215,000 stpy of refined copper, 2 million troy ounces of silver and 6,000 troy ounces of gold per year was achieved. In 1994, Southern Peru announced plans to increase the capacity to 250,000 stpy of cathode with a US$ 18 million investment and a US$2 million investment in environmental improvement projects, as part of the purchase agreement with the Peruvian government. This paper outlines the scope of the Southern Peru Limited refinery modernization and environmental program. It describes the implementation of the electrolytic plant expansion based on installation of polymer concrete celis, a new rectifier, a new selenium roaster and a precious metal plant upgrades.
9:10am EFFECTS OF SOLUTES ON GRAIN REFINEMENT OF SELECTED WROUGHT ALUMINIUM ALLOYS: M.A. Keams, P.S. Cooper, London & Scandinavian Metallurgical Co. Limited, Fullerton Road, Rotherham, South Yorkshire, S60 lDL, England An analysis of the effects of alloy additions on the grain refinement in a series of model and commercial aluminium alloy compositions is reported. The data of Birch and Fisher published earlier describing grain refinement in 32 systems, including AA3004, AA5083, AA6063 and AA 7050, are considered in terms of the supercooling effect of each alloy addition. A simple model describing grain size in terms of additive supercooling effects of individual alloy additions is proposed which fits the data reasonably well. Deviations from simple additive behaviour are evident in systems where strong intermetallic interactions occur. Interaction coefficients amongst solutes are invoked to explain these deviations. Individual alloying effects on grain refinement are treated in terms of constitutional supercooling parameters and behaviour is shown to be similar to that described in earlier studies. Zirconium is shown to have a general poisoning effect in a range of alloy compositions. 9:30am THE BUBBLE SIZE AND MASS TRANSFER MECHANISMS IN ROTOR STIRRED REACTORS: Stein Tore Johansen, Svend Gnldahl, Per Ola Grlilntvedt, PaJ. Tetlie, Rune Garnmelsreter, SINTEF Materials Technology, N-7034 Trondheim, Norway; Karl Venas, Pal Skaret, Karl Venas a.s., Trondheim, Norway; Erling Myrbostad, Bj\'lrn Rasch, Hydro Aluminium a.s R&D Centre, N·6600 Sunndals\'lra, Norway
CAST SHOP TECHNOLOGY I: Fundamentals and Modelling Sponsored by: LMD Aluminum Committee Program Organizer: Wolfgang A. Schneider, YAW aluminium AG, Research and Development, Georg-von-Boeselager-Str.25, 0-53117 Bonn, Germany Monday, AM February 10, 1997
The performance characteristics ofthe HYCAST Rotor has been investigated in a water model. The removal rate of oxygen from water is measured for a large number of operational conditions. By combining different techniques the energy dissipation in the reactor, the mass transfer at the top surface and the bubble sizes may be determined experimentally. Investigations of the bubble dynamics by high speed video show that the bubbles in this type of reactors are very different from what is hitherto believed. Based on such a picture the paper demonstrates that the mass transfer and bubble sizes in the HYCAST Unit may be explained by a relatively simple theory which seems to explain all available experimental data. It is also demonstrated how we from this theory can scale from the oxygen removal in water model to hydrogen removal in liquid aluminum.
Room: 230B Location: Orlando Convention Center
Session Chairperson: Einar K. Jensen, Elkem a/s Research, N-4602 Kristiansand S., Norway
8:30am MATHEMATICAL MODELLING OF THE METAL FLOW IN SIDEWELLFURNACES: Y.S. Kocaefe, R.T. Bui, D. Kocaefe, Department of Applied Sciences, University of Quebec at Chicoutimi 555, Boul. de I'Universite, Chicoutimi, Quebec, Canada G7H 2BI
9:50am MODELLING OF SURFACE SEGREGATION DEVELOPMENT DURING D.C. CASTING OF ROLLING SLAB INGOTS: A. Mo, HJ. Thevik, SINTEF Materials Technology, Box 124 Blindern, N-0314 Oslo, Norway; B.R. Henriksen, E.K Jensen, Elkem Research, Box 40, N·4602 Kristiansand, Norway
Many different types of furnaces are used in aluminum industry for melting and treating the metal. Sidewell furnaces are commonly used for scrap melting. Metal flow in the furnace is provided by different types of equipment such as pumps and impellers, and plays an important role in furnace performance. A three-dimensional model has been developed to simulate the metal flow in such furnaces. In this paper, the model will be described, and the results will be presented showing how various operating and design parameters such as impeller position and rotational speed, sidewell geometry and arch design affect the metal flow.
A two dimensional mathematical model for the development of macrosegregation at and close to the ingot surface during DC casting of rolling slabs is presented. The model accounts for macrosegregation caused by exudation of interdendritic melt and macrosegregation associated with solidification shrinkage. Equations for the conservation of energy, solute, momentum, and mass during the stationary phase of the process are solved numerically by a finite element method in a solution domain defined by a vertical cross section of the ingot. The main simplifications in the modelling concept are to assume the solidified part of the mushy zone to move with the casting speed, and to consider a binary alloy solidifying according to the lever rule. The thickness and solute concentration of the surface layer and the macrosegregation close to the surface are calculated, and modelling results are compared with measurements on real castings.
8:50am Na AND Ca PICK-UP FROM HALL BATH IN INGOT FURNACES: David H.DeYoung, Aluminum Company of America, Molten Metal Processing Center, Alcoa Technical Center, Alcoa Center, PA 15069 A series of laboratory tests were conducted to explore the reaction of bath with AI-Mg alloys, as may occur when Hall bath enters ingot furnaces in a smelter-supplied ingot plant. Results showed that Mg clearly reacts with bath and adds Na and Ca to the metal by the reactions: 2(N~AIF6) + 3 Mg ~ 6 Na + 2 AlF3 + 3 MgF2 (1) and CaF2 + Mg ~ Ca + MgF2 (2) Temperature, Mg concentration in the alloy, the quantity of bath added to the metal, and the particle size of the bath added all influenced the reaction. At 700°C the Na and Ca pick-ups that occurred from these reactions were approximately 15 ppm while at 900°C the pick-ups were greater than 300 ppm. The pick-ups increased with increasing quantity of bath up to a limiting amount, beyond which no further pick-up occurred. The variation of the reaction with particle size indicated that the reaction is limited by the available bath-metal surface area.
10:10 am BREAK 10:20 am A MODEL TO PREDICT THE STEADY STATE PULL-IN DURING D.C.-CASTING OF ALUMINIUM SHEET INGOTS: Arild Hdkonsen, Hydro Aluminium R&D Materials Technology, P.O.Box 219, N-6601 SunndalS\'lra, Norway By combining empirical results with a dimensional analysis, a model for the prediction of pull-in during DC-casting of aluminium sheet ingots is con-
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11:40 am FUNDAMENTALS OF UBC DECOATINGIDELAQUERING FOR EFFICIENT MELTING: Wesley Stevens, Francois Tremblay, Arvida Research and Development Centre, Alcan International Limited, 1955 Mellon Blvd., Jonquiere, Quebec, Canada G7S 4K8
structed. The model predicts the steady state pull-in along the rolling faces of an ingot. By using an alloy dependent constant, the nominal geometry and the casting speed, the model can easily calculate a near optimal mould shape. It is also possible to calculate the resulting shape of the rolling faces of an ingot for a given mould geometry, alloy constant and casting speed. The model requires only a spread sheet for these calculations. Comparisons with experiments show a very good agreement. The best fit values of the alloy constant for several commercial aluminium alloys are presented. The value of this constant varies within 12%.
Aluminum used beverage cans (UBC) should be cleaned to completely remove all organic and residues to maximize metal recovery on remelting. This process must also minimize oxide formation. The aluminum industry uses three principal decoating technologies. The most used is the rotary kiln. The other processes are the belt decoater and the fluidized bed decoater. The presentation will cover the fundamental science for decoating shredded UBC to minimize metal loss on remelting. Laboratory work and plant trials have shown the requirements for complete decoating. These are: correct temperature range for the coatings to be pyrolized, good process gas to shred contact for all the scrap, sufficient oxygen being present to complete the oxidation of the carbon compounds present. The basic principles of the three decoating technologies used for the decoating of UBC will be discussed in relation to how they correspond to the fundamental process requirements.
10:40 am THE MECHANISM OF PULL-IN DURING D.C.-CASTING OF ALUMINIUM SHEET INGOTS: Hallvard G.Fjl£r, Institute for Energy Technology, P.O. Box 40, N-2007 Kjeller, Norway; Arild Hakonsen, Hydro Aluminium R&D Materials Technology, P.O. Box 219, N-6601 SunndalS(lira, Norway The pull-in phenomenon apparent in the DC-casting process of aluminium sheet ingots is investigated both analytically and by use of numerical models calculating temperatures, strains and stresses. The major part of the pull-in takes place above the bottom of the sump, but is mainly caused by thermal contractions and deformations in regions below. The strong and almost exactly linear dependency of the pull-in on the casting speed is explained. The effects on the pull-in of different cooling conditions and of various thermophysical and thermomechanical properties are investigated. 2D plain strain approximations have been successfully applied in calculating the pullin for the centre part of the rolling face, but 3D effects are significant close to the narrow ingot surface. This is illustrated by comparison of results from 3D and 2D calculations. Modelling results are also compared with measurements of ingot thickness variations. A very good agreement is obtained.
CHEMISTRY AND PHYSICS OF NANOSTRUCTURES AND RELATED NON EQUILIBRIUM MATERIALS I: DIffusion and Phase Transformations Sponsored by: Jt. EMPMD/SMD Chemistry and Physics of Materials Committee, MSD Thermodynamics and Phase Equilibria Committee Program Organizers: Brent Fultz, 138-78, California Institute of Technology, Pasadena, CA 91125; En Ma, Louisiana State Univ., Dept. of Mechanical Eng., Baton Rouge, LA 70803; Robert Shull, NIST, Bldg. 223, Rm B152, Gaithersburg, MD 20899; John Morral, Univ. of Connecticut, Dept. of Metallurgy, Storrs, CT 06269; Philip Nash, Illinois Institute of Technology, METM Dept., Chicago, IL 60616
11:00 am WATER COOLING IN DIRECT CHILL CASTING: BOILING THEORY: John Grandfield, Comalco Research Centre, P.O.Box 316, Thomastown, Victoria 3074, Australia
Monday, AM February 10, 1997
The intensity of the water cooling in direct chill casting affects the process heat flow and the performance of the casting process. The intensity depends on the boiling behaviour on the ingot surface. The basic mechanisms of boiling, the different boiling modes (nucleate, unstable film and stable film boiling), the effect of water composition, temperature, flow and velocity on boiling behaviour and heat transfer are reviewed. A new method for measuring the heat transfer coefficients has been developed and some new results on the effect of water composition and temperature are presented together with results from inverse calculations based on insitu measurements during casting.
Room: 330C Location: Orlando Convention Center
Session Chairperson: Brent Fultz, 138-78, California Institute ofTechnology, Pasadena, CA 91125
8:30 am INVITED KINETICS OF ATOMIC TRANSPORT IN THE FORMATION OF NONEQUILIBRIUM MATERIALS: Michael 1. Aziz, Division of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge MA 02138
11:20 am HEAT TRANSFER MEASUREMENTS BETWEEN HOT METAL AND COOLING WATER - APPLICATION TO DC CASTING SIMULATION: B. Magnin, L. Maenner, Y. Caratini, Pechiney Centre de Recherches de Voreppe, BP 27, F-38340 Voreppe, France
Rapid solidification can result in the production of nonequilibrium materials either primarily due to nucleation or primarily due to growth. Rapid growth can trap in solute or point defect supersaturations or chemical disorder, or can cause the formation of nonequilibrium microstructures. Additionally, large driving forces can permit the nucleation and growth of other metastable phases. The phenomenology and mechanisms for these processes will be discussed. Models and experiments will be reviewed.
The numerical simulation of DC casting requires a good knowledge of the heat transfer between ingot and cooling water. This is especially true for the starting phase, where most defects are initiated. An experimental set-up has been developed to characterize this heat exchange close to process operating conditions. The method is based on the measurement of the cooling of a preheated instrumented aluminium block quenched by a water curtain. A 2D transient inverse model allows to determine the distribution of heat transfer coefficient and temperature on the whole surface of the block. In this way, heat flux can be assessed both at the water impingement point and below. The results obtained with the experimental apparatus are in good agreement with heat transfer rates calculated from in-situ temperature measurements using cast-in thermocouples. This device is thus an efficient and economical method to determine the influence of cooling water characteristics on the law describing heat transfer coefficient as a function of surface temperature. These laws have been measured and introduced in a numerical simulation of DC casting in order to study the effect of water cooling and casting parameters on the thermal evolution of the ingot during the different phases of casting.
9:00 am INVITED DEVIATIONS FROM LINEAR DIFFUSION DURING SOLID-STATE AMORPHIZATION IN Ni-Hf DIFFUSION COUPLES: M. Atzmon, W.S.L. Boyer, The University of Michigan, Department of Nuclear Engineering and Radiological Sciences, Materials Science and Engineering, Ann Arbor, MI48109-2104 When analyzing diffusion measurements, the diffusion coefficient is often assumed to be independent of composition and time. In this paper, studies of possible deviations from this simple picture will be reported. During amorphous alloy growth in an elemental diffusion couple, the amorphous phase has a wide homogeneity range, and the interdiffusion coefficient is unlikely to be uniform. Experimental results in Ni-Hf thin-film couples will be described, which indicate that the interdiffusion coefficient varies significantly with composition. This variation leads to significant systematic errors in determining the interfacial compositions from measured composition profiles. A more reliable measurement method will be presented. A number of authors
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have suggested that evolution of macrostress during amorphization by interdiffusion affects the rate of the latter. Using a combination of substrate curvature and lattice parameter measurements, we have determined the evolution of stress during interdiffusion in Ni-Hf thin-film couples. The amorphous phase is observed to form under large tensile stress, which relaxes by creep during subsequent growth. Neither this stress, nor that induced by ion irradiation, affects the interdiffusion coefficient. 9:30 am INVITED SINTERING OF SMALL ASSEMBLIES: R.S. Averback, Huilong Zhu, M. Yeadon, J.M. Gibson, Materials Science and Engineering, University of Illinois, 1304 W. Green St., Urbana, IL 61801 The sintering of small assemblies of nanoparticles has been investigated by a combination of molecular dynamics computer simulations and in situ observations in a UHV transmission electron microscope. Because the radius of curvature of nanoparticles is so small, enormously large interfacial stresses are developed when nanoparticles come in contact with other nanoparticles or substrates, and this leads to sintering by plastic deformation of the particles on the time scale of some picoseconds. Surprisingly, these particles rotate and form twins and other low energy configurations. Several examples of such sintering will be illustrated, including nanoparticle assemblies of Cu, amorphous alloys and intermetallic compounds. Interactions between nanoparticles and substrates will also be discussed.
10:00 am INVITED EFFECT OF FREE SURFACES ON THE KINETICS AND MORPHOL· OGY OF SPINODAL DECOMPOSITION: Long-Qing Chen, Materials Science and Engineering, Penn State University, University Park, PA 16802 The kinetics of spinodal decomposition and morphological evolution near a crystalline surface were investigated by microscopic master equations in the point and pair approximations and a second-neighbor interaction model. Both two-dimensional (2-D) and 3-D model systems were considered. It is shown that, in the presence of a surface, spinodal decomposition initially involves surface segregation, followed by anisotropic decomposition in the near-surface region, and then followed by isotropic decomposition in the bulk. It is demonstrated that, due to segregation, a surface spinodal decomposition may take place for alloys whose overall average compositions are outside the bulk spinodal. It is found that the presence of a surface results in a dominant concentration wave which produces interesting transient morphological patterns such as distorted hexagonal precipitate lattices for relatively low-volume fractions and straight stripes at high volume fractions in the near-surface region. The relevance of these results to the mechanisms of diffusional phase transformations, such as spinodal ordering and decomposition, in nanoscale crystalline materials will be discussed. 10:30 am BREAK
10:45 am INVITED SELF·PROPAGATING REACTIONS IN NANOSCALE MULTILAYER MATERIALS: Tim Weihs, Materials Science & Engineering, The Johns Hopkins University, Baltimore, MD 21218 This presentation describes self-propagating, exothermic reactions in nanoscale, multilayer materials. The talk begins with a review of self-propagating reactions in powder-based materials and then focuses on similar exothermic reactions in multilayer foils. The multilayer foils consist of alternate layers of materials that have high heats of mixing, such as Al and Ni. The individual layers (of Al or Ni) are only nanometers thick, but hundreds of these layers are sputter deposited to form one foil with a total thickness between 10 and 100 microns. The layered foils arc easily removed from their substrates, and their exothermic mixing can be started at room temperature with a small spark. Te exothermic reactions propagate al speeds greater than 10mls and they reach final temperatures as high us 1600°C The reactions can propagate in air, vacuum, or liquids. The velocities, the heats, and the temperatures of the reactions will be presented for at least two different multilayer systems, and the chemical and structural parameters that control these properties will be addressed using an analytical model. The final segment of the talk will describe how reactive multilayer foils can be used as local heat sources to joint structural components.
11:15 am INVITED NANOSTRUCTURED PALLADIUM ALLOY MEMBRANE MATERI· ALS: Kenneth J. Bryden, Jackie Y. Ying, Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139-4307 Membranes are often fabricated from palladium since it has a very high hydrogen permselectivity. Diffusion through the metal is often the rate-limiting step in hydrogen transport through palladium-based membranes. The flux through these membranes can be increased by tailoring a microstructure that allows for higher hydrogen diffusivity. Nanostructured palladium has a much higher hydrogen diffusivity than conventional palladium due to its large volume fraction of grain boundaries. Thus, nanostructured metal membranes would provide higher hydrogen fluxes and better performance. By doping palladium with another element, enhanced stability against grain growth, stability against the alpha to beta phase transition which causes cracking, and enhanced poisoning resistance can be achieved. In this study nanostructured pure palladium and palladium alloy membranes were synthesized by pulsed electrodeposition. The hydrogen permselectivity through these materials was determined in a membrane reactor and the effect of common poisons (e.g. carbon monoxide and hydrogen sulfide) on hydrogen diffusivity was also measured to relate the hydrogen permeation properties of these materials to their microstructure and elemental composition.
DESIGN AND RELIABILITY OF SOLDERS AND SOLDER INTERCONNECTS: Session I: Microelectronic Packaging Technology -Trends and the Importance of Solder and Solder Joints Reliability Sponsored by: MSD Flow and Fracture; SMD Mechanical Metallurgy; EMPMD Electronics Packaging and Interconnection Materials Committees Program Organizers: R.K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; D.R. Frear, Sandia National Laboratory, Mail Stop 1411, Albuquerque, NM 87185; S.M.L. Sastry, Washington UniverSity, Mechanical Engineering Dept., St. Louis, MO 63130; K.L. Murty, North Carolina State University, Materials SCience and Engineering Dept., Box 7909, Raleigh, NC 27695; P.K. Liaw, University of Tennessee, Materials Science and Engineering Dept., Knoxville, TN 37996; W.L. Winterbottom, Reliability Consultant, 30106 Pipers Lane Court, Farmington Hill, MI 48331 Monday, AM February 10, 1997
Room: 332 Location: Orlando Convention Center
Session Chairperson: Ephraim Suhir, LucentTechnologies, Bell Laboratories, Room 7G·326, 700 Mountain Avenue, NJ 07974; Theodore Ejim, Lucent Technologies, Bell Laboratories, Engineering Research Center, P.O. Box 900, Princeton, NJ 08542
8:30am OPENING STATEMENTS: Dr. Darrel R. Frear, EMPMD Chair and, Senior Member of Technical Staff, Department 1811, Mail Stop 1411, P.O. Box 5800, Sandia National Laboratories, Albuquerque, NM 87185
8:40 am Keynote MICROELECTRONIC PACKAGE TRENDS· THE ROLE OF RELI· ABILITY IN PARTICULARLY, RELATED TO SOLDER JOINT RE· LIABILITY: c.P. Wong' and Rao Tummala", Georgia Institute of Technology, Packaging Research Center (PRC), School of Materials Science & Engineering, and School of Electrical & Computer Engineering, 778 Atlantic Drive, Atlanta, GA 30332;'Professor and Assistant Director, PRC; "Pettit Chair Professor, Georgia Eminent Scholar and Director, PRC The trends of microelectronic devices have advanced to the state that they operate in excess of 200 MHz with submicron feature size. Furthermore, these high performance IC requires Inputs/Outputs (lIO) signals that are in excess of a few 1000's. Low-cost, high performance flip-chip, area array solder joint interconnects are key to the success of this technology. In order to enhance the thermal cycle fatigue-life of these solder joints, underfill encapsulants are
needed. In this talk, we will review the microelectronic packaging technology trends, the role of reliability, in particularly, the use of underfill encapsulants to enhance the thermal cycle fatigue life of solder joints will be discussed.
mance of the devices, as well as for the short- and long term mechanical reliability of the soldered optical fibers and the solder materials themselves. We address the geometry's of, and the loading condition in, fiber-optics solder joints, and suggest several analytical stress models that enable one to evaluate thermally and mechanically induced stresses in solder joint assemblies in fiber-optics structures. These models include: thermal stresses in metallized fibers soldered into ferrules or capillaries; stresses at the menisci areas in soldered joints; comparison of the thermal stresses due to the application of "hard" (high modulus) and "soft" (low modulus) solders; interaction of the "global" and "local" thermal stresses in optical fibers whose end portions are soldered into capillaries; evaluation and interaction of mechanical and thermal stresses in solder joints during proof-testing of optical fibers soldered into ferrules; and others. The merits and shortcomings of soldered assemblies in comparison with adhesively bonded structures are also briefly discussed.
9:15 am KEYNOTE SOLDER JOINTS IN ELECTRONICS - DESIGN FOR RELIABILITY: Werner Engelmaier, President, Engelmaier Associates, Inc., 23 Gunther Street, Mendham, NJ 07945 The emerging new technologies provide ever more challenges to assure the reliability of electronic products. The ever increasing demands in electronic products for higher performance, lower cost, less space (weight) is leading to ever denser interconnection needs. Solder joint reliability is becoming an even more important issue with the advent of new surface mount packages and the use of surface mounted electronics in such hostile environments as the automobile and space. The new packages are characterized by larger sizes, finer pitches, andlor problematic materials which require an up-front 'Design for Reliability (DfR)' to meet reliability requirements. The hostile environments can include thermal excursions over temperature ranges in which multiple interactive damage mechanisms are operative. The reliability of electronic assemblies requires a definitive design effort that has to be carried out concurrently with the other design functions during the developmental phase of the product. There exists a misconception in the industry, that quality manufacturing is all that is required to assure the reliability of an electronic assembly. While of course, consistent high quality manufacturing - and all that this implies is a necessary prerequisite to assure the reliability of the product, only a DfR-procedure can assure that the design - manufactured to good quality - will be reliable in its intended application. Explicit DfR-procedures need to be employed to account and compensate, at least in part, for the prevalent damage mechanisms. This needs to be complemented with 'Design for Manufacturability (DfM)' which widens the process windows and takes into account the manufacturing capabilities. These demands put an increasing burden on the designers who will require a heightened technical understanding of the underlying issues and more sophisticated design tools. Thus, adherence to quality standards, such as IPC-A-620, Acceptability of Electronic Assemblies with Surface Mount Technologies, andANSII1-STD-001, Requirements for Soldered Electrical and Electronic Assemblies does not assure reliable solder connections, only quality solder connections. It is for this reason that IPC-D-279, Design Guidelines for Reliable Surface Mount Technology Printed Board Assemblies, is being developed. The 'Design for Reliability (DfR), for solder attachments in electronic interconnections will be the emphasis of the paper.
11:00 am INVITED MICROSTRUCTURAL ANALYSIS OF ELECTRONIC MATERIALS: Aleksander Zubelewicz, IBM Microelectronics, W-64, Bldg. 4-2, 1701 North Street, Endicott, NY 13760 The electronic industry is changing at a rapid pace. Faster and more powerful processors and ASICs continuously replace the slower devices, while price competitiveness and time-to-market becomes the true challenge for many manufacturers. The dynamic nature of the electronic industry drives for the need of using smaller packages with higher lIO count. Recently, fine pitch, a family ofBGA components, and Chip Scale Packages represent the "hottest" technologies allowing for high lIO density. However, the future electronics applications will require processors operating with speed of several hundred MHz, then the present packaging technology may need further modifications. Consequently, the traditional PTH interconnection technology is being replaced by Surface Mount Technology and Ball Grid Arrays. Furthermore, new interconnection materials such as lead free solders and conductive adhesives are being seriously considered as a replacement of the commonly used lead based alloys. The objective of the paper is to discuss the behavior and failure mechanisms for the interconnection materials. Obviously, solders are at the top of the list, followed by encapsulations and conductive adhesives. During manufacturing operations, solders are used in the form of a paste, and when reflowed becomes ductile polycrystalline materials. These pastes must maintain appropriate rheological characteristics. It will be shown that a typi .. cal paste (solder or conductive adhesive) exhibits three stages of behavior: paste as a viscous solid, paste as a viscous fluid, and the transition stage between solid and fluid. Solder joints (after reflow) are thought to carry input! output electrical functions of the assembly as well as are designed to provide a mechanical support for the package or chip. Solders exhibit very complex microstructural behavior. There is a need for material model of solders, a model that can be used in the form of constitutive equations with built-in damage criteria, equipped with functions that represent microstructural evolution of solders, and allowing to predict the effect of strain/damage localization in solder joints. Moreover, this theory should lead to simple fatigue equations when needed. One such theory exists and will be discussed in the paper. In many cases, solder joints become the weakest link. Enhancement of the joint reliability can be accomplished by encapsulating them with polymer based materials. A microstructural numerical study for encapsulant will be briefly presented in the paper. It will be shown that fracture originates at the microscopic level of the materials, coalesce, and forms a localized fracture zone.
9:50 am KEYNOTE MEETING MARKET DEMANDS - NEW AND CRITICAL TECHNOLOGIES FOR ELECTRONIC PACKAGING AND ASSEMBLIES: Jennie S. Hwang, President, H-Technologies Group Inc., 5325 Naiman Parkway, Cleveland, OH 44139 Advanced technologies are transforming manufacturing, and the information highway is speedily progressing. In this exciting and changing time, the electronic industry has responded and will continue to respond to competitive products in the global market place. The speaker will provide a capsule view of key segments of electronics hierarchy in market needs and the demands in new technologies. The presentation will separately address the market and technology in chip level, package level, and board level, as well as, the critical supporting materials and technologies. Dr. Hwang will conclude her talk by highlighting the important aspects of the reliability of solder joints in relation to the new market trends.
11 :25 am INVITED INCONSISTENCIES IN THE UNDERSTANDING OF SOLDER JOINT RELIABILITY PHYSICS: Liang-chi Wen, G. Mon, R. Ross, Jr., Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109
10:25 am BREAK 10:35 am INVITED SOLDER MATERIALS AND SOLDER JOINTS IN FIBER OPTICS ENGINEERING - RELIABILITY REQUIREMENTS AND PREDICTED STRESSES: Ephraim Suhir, Lucent Technologies, Bell Laboratories, Physical Sciences and Engineering Division, Room 7G-326, 700 Mountain Avenue, NJ 07974
An inherent reliability problem associated with surface mount applications is that solder joints, which serve both as an electrical and a mechanical connection between part and board, are subject to thermal fatigue failure. Solder joint failure involves a complex interplay of creep and fatigue processes. Over the years, many analytical and experimental research studies have aimed to improve state-of-the-art assessment of solder joint integrity from a physics of failure perspective. Although considerable progress has been made, there still exist many inconsistent and even contradictory correlations and conclusions.
Typical solder materials and solder joints, employed in fiber-optics engineering, are examined from the stand-point of the requirements for optical perfor-
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This paper reviews the unique properties of near-eutectic tin-lead solder, properties such as age-softening and 'superplastic' behavior under low strain rate loading. Fundamental mechanical and thermomechanical processes are modeled to demonstrate many inconsistencies observed in the literature. These inconsistencies are to be found in both analysis and testing issues. Analytical inconsistencies arise in correlations involving Coffin-Manson and strain energy density algorithms for cycle-life prediction, the effects of mean temperature and cycle frequency, and the determination of test acceleration factors. Testing inconsistencies are to be found in the areas of mechanical versus thermal cycling, failure definations, detection methodology and treatment of failure statistics. The objective of this paper is to identify important unsettled analysis and testing issues whose resolution by the solder joint research community will assure a greater degree of solder joint reliability.
DESIGN AND RELIABILITY OF SOLDERS AND SOLDER INTERCONNECTS: POSTER SESSION Sponsored by: MSD Flow and Fracture; SMD Mechanical Metallurgy; EMPMD Electronics Packaging and Interconnection Materials Committees Program Organizers: R.K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; D.R. Frear, Sandia National Laboratory, Mail Stop 1411, Albuquerque, NM 87185; S.M.L. Sastry, Washington University, Mechanical Engineering Dept., St. Louis, MO 63130; K.L. Murty, North Carolina State University, Materials Science and Engineering Dept., Box 7909, Raleigh, NC 27695; P.K. Liaw, University of Tennessee, Materials Science and Engineering Dept., Knoxville, TN 37996; W.L. Winterbottom, Reliability Consultant, 30106 Pipers Lane Court, Farmington Hill, MI 48331
11:50 am INVITED AUTOMATED SOLDER LIFE ANALYSIS OF ELECTRONIC MODULES: Stephen A. McKeown, Lockheed Martin Control Systems, 600 Main Street, Johnson City, NY 13790
Monday - Thursday February 10-13, 1997
Room: 332 Location: Orlando Convention Center
Session Chairperson: R.K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA95134
The solder life analysis methods developed by Engelmaier and Steinberg have been incorporated into an automated method which combines the results of finite-element models, a component location file obtained from a computeraided design tool, component data, and environment data to calculate the expected solder joint life for each surface mount technology component on an electronic module. The method uses the finite-element method to calculate the coefficient of thermal expansion at different locations on the surface of the module which is used in determining the thermal cycling life of the solder joints. Finite-element analysis is also used to determine the surface strains due to vibration of the module which also influences solder joint life. The component location is taken from a Mentor'" neutral file which also provides component description and orientation. Component data includes the dimensions of the part and information on the solder joint fillet geometry. Environment data includes temperature ranges, dwell times, vibration levels, and durations of thermal/vibration missions. This information is combined in a ANSI C-language program to determine the calculated failure rate of each component for the combined environments, and the overall computed reliability of all of the analyzed solder joints.
ALLOY DESIGN OF Sn-Ag-In-Bi-Sb SOLDER SYSTEM USING THERMODYNAMIC CALCULATIONS: Byeong-Joo Lee l and Hyuck Mo Lee 2, IMaterials Evaluation Center, Korea Research Institute of Standards and Science, Yusong P.O. Box 102, Taejon 305-600, Korea; 2Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Kusong-Dong 373-1, Yusong-gu, Taejon 307-701, Korea TiN-BASED, ACTIVE METAL CONTAINING SOLDERS FOR JOINING OF ALUMINA: Tim Schwilm l , O. T. Inal! and Frederick G. Yost2, Materials and Metallurgical Engineering Department, New Mexico Tech, Soccoro, NM 87801; 2Sandia National Laboratories, Albuquerque, NM 87815 THERMAL AGING CHARACTERISTICS AND WETTING FORCE MEASUREMENTS OF EUTECTIC Ag-Sn SOLDER ALLOY: Guna Selvaduray, Hason Fong and Kristine Griley, Department of Materials Engineering, San Jose State University, San Jose, CA 95192
12:10 am WHEN IS A MODIFIED COFFIN-MANSON APPROACH VALID FOR SOLDER JOINT RELIABILITY PREDICTION?: Robert Darveaux, Amkor Electronics, 1900 S. Price Road, Chandler, AZ 85248
EVALUATION OF INTERMETALLIC PHASE FORMATION AND CONCURRENT DISSOLUTION OF INTERMETALLIC DURING REFLOW SOLDERING: M. Schaefer!, W. Laub l , R.A. Fournelle l and J. Liang 2, IMaterials Science Program, Marquette University, 1515 W. Wisconsin Ave., Milwaukee, WI 53201-1881; 2Allen-Bradley Company, 1201 S. Second St., Milwaukee, WI, 53204
The Coffin-Manson approach is based on relating fatigue life to plastic strain range. The basic equation has been modified by Norris-Landzberg, Engelmaier, and others to include temperature, frequency or dwell time effects. These modifications were determined empirically on specific types of soldered assemblies. Today, they are commonly applied to a wide range of assemblies and test conditions, as well as field use conditions. The main advantage of these empirical relations is that they are easy to use. They are basically back of the envelope calculations that require almost no expertise on the part of the engineer. This paper explores the validity of modified Coffin-Manson approaches as applied to solder joint reliability analysis. Several case studies are examined, and the limits of the approach are defined.
NANOSTRUCTURAL ANALYSIS OF PADS-TREATED SOLDER SURFACE: James L. Marshalfl and Brett Piekarski 2, IDepartment of Chemistry, University of North Texas, Denton, TX 76203-5068; 2Army Research Laboratory, AMSRL-EP-RC, 2800 Powder Mill Road, Adelphi, MD 20783 INTERFACIAL REACTION BETWEEN PALLADIUM AND LEADTIN SOLDERS: G. Ghosh, Dept. of Materials Science and Engineering, Northwestern University, Evanston, IL 60208-3108
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10:10 am BREAK
EVOLUTION AND ADVANCED CHARACTERIZATION OFTHIN FILM MICROSTRUCTURES I: Nucleation and Growth
10:30 am INVITED MOLECULAR VIEW OFCVD DIAMOND FILM GROWTH: DavidJ. Srolovitz, Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109-2136; Corbett Battaile*, James E. Butler, DDGas/Surface Dynamics Section, Code 6174, Naval Research Laboratory, Washington DC 20375-0001
Sponsored by: MSD Structures Committee, EMPMDThin Films and Interfaces Committee Program Organizers: Eric P. Kvam, School of Materials Engineering, Purdue University, West Lafayette, IN 47907-1289; Steven M. Yalisove, Dept. Materials Science and Eng., HH Dow Bldg., University of Michigan, 2300 Hayward St., Ann Arbor, MI48109-1204; Eric P. Chason, Sandia National Labs., Dept. 1112, MS 1415, PO Box 5800, Albuquerque, NM 87185 Monday, AM February 10,1997
Kinetic Monte Carlo computer simulations of the growth of diamond thin films are presented as a function of hot filament chemical vapor deposition reactor conditions. The model includes chemical reactions between surface atoms, gaseous hydrogen and hydrocarbons, and between species on adjacent surface sites. Gas phase hydrocarbon composition is varied over six orders of magnitude. The effects of surface atomic structure and morphology on growth behavior are included explicitly. The evolution of surface structure (including reconstruction) during growth and evidence for step-flow growth and surface roughening will be presented. Model predictions for the growth rates of high symmetry facets will be presented and the influence of these growth rates on surface roughness, microstructure, point defect incorporation and texture will be discussed.
Room: 340C Location: Orlando Convention Center
Session Chairs: D.J. Srolovitz, Dept. of Materials Science and Engineering, University of Michigan, Ann Arbor, MI48109-2136; D.P. Adams, Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185
10:50 am
8:30 am INVITED CORRECTION FACTORS TO THE CLASSICAL NUCLEATION RATE: David T. Wu, Dept. of Mechanical Engineering, Yale University, New Haven, CT 06520
MICROSTRUCTURAL INVESTIGATION OF THE GROWTH OF YBa, Cu 3 0,.x INd, CuO/YbA, CU 3 0,.x TRILAYERED FILMS ON LaSrGaO. SUBSTRATES: Y.H.Li, A.E. Staton-Bevan, Department of Materials, Imperial College, London SW7 2Bp, UK; Z. Trajanovic, I. Takeuchi, T. Venkatesan, Department of Physics, University of Maryland, MD 20742
The rate of nucleation can have a strong influence on the microstructure of thin films. This talk discusses corrections to the classical expression for nucleation rate. For heterogeneous nucleation's spherical cap model a new contact-angle dependence for the prefactor is presented, while in homogeneous nucleation the self-consistency correction is reconsidered using the idea of "kinetic potential." Both corrections can increase the nucleation rate significantly.
AHRTEM study of an YBCOlNdzCuO/YBCO trilayered films on LaSrGaO. substrate with PBCO as a template layer has shown that in-plane aligned aaxis oriented YBCO films may be grown on (100) LaSrGaO. substrates by pulsed laser deposition, which contain some domains with the c-axis misaligned by 90° in plane of the films. A NdzCuO. insulating layer, with a thickness of approximately lOnm, may be grown epitaxially between a-axis oriented YBCO layers with its c-axis parallel to the c-axis of the YBCO layers. A 90° -misoriented a-axis YBCO grain in the lower YBCO layer can nucleate a 90°-misoriented Nd2CuO. grain in the a-axis oriented Nd2CuO. layer and this grain can further nucleate a 90° -misoriented YBCO grain in the top YBCO layer. Narrow vertical NdP, plates were observed in 90°-misoriented NdzCuO. grains formed epitaxially with the N~CuO. grains. The interface between the PBCO template layer and the LaSrGaO. substrate is quite rough with some amorphous islands in the template layer.
9:10 am INVITED EVOLUTION OF THIN FILM MICROSTRUCTURE AND MORPHOLOGY DURING CHEMICAL VAPOR DEPOSITION: D.P.Adams, T.M. Mayer, E. Chason, B.S. Swartzentruber, Sandia National Laboratories, P.O. Box 5800, Albuquerque, N.M. 87185 We present a study of thin film growth by thermal chemical vapor deposition (CVD). In this investigation of metal growth onto Si substrates, the effects of chemical kinetic processes on both film structure and morphology are determined. Scanning tunneling microscopy is used to identify the nucleation sites and to monitor island growth during the submonolayer regime. Analysis of measured island size distributions reveals the importance of site-specific chemical reactions and precursor molecule diffusion. Also, we monitor the development of surface roughness of thicker films by x-ray reflectivity. These experiments demonstrate the influence of nucleation rate on surface morphology. Finally, we show how CVD kinetics can be manipulated by use of adsorbates which passivate chemically - reactive substrate sites. Adsorbate layers have been used to modify the nucleation rate and fabricate nanometer - size structures via selective - area growth. This work was supported by the U.S. Department of Energy under contract DE-AC04-94AL85000.
11:10 am ADVANCES IN THE PROCESSING AND APPLICATIONS OF HIGH TEMPERATURE SUPER CONDUCTING FILMS: M. Sisodia, R.K. Yadava, Dept. of Metallurgical Engineering, Malaviya Regional Engineering College, Jaipur 302 017, India High critical temperature (high-T,) superconductors have captured the interest of engineers and scientists world wide. For its commercial utilization in the field of microelectronics and electronic systems, they must be fabricated into desirable configurations, thin and thick films. During studies it has been observed that these superconducting thin films operating at liquid N2 temperature offer great possibilities for faster, more sensitive and precise electronics devices. Present paper reviews the fabrication techniques of high-T, superconducting thin films which primarily includes Pulsed-Laser Deposition, Molecular ion beam epitaxy, Chemical Vapour Deposition (CVD) by using epitaxial growth on single crystal substrates (YSZ,MgO,Si, etc.) with excellent microstructural control and properties relationship. In addition to it, thick film fabrication is also discussed with major techniques like Screen Printing and Plasma Spraying along with associated processing parameters. Furthermore, advanced applications of each are enumerated at length.
9:50am TEM INVESTIGATION OF CVD ALUMINA MULTILAYER COATINGS: M. Halvarsson, Department of Physics, Chalmers University of Technology, S-412 96 Gtiteborg, Sweden; S. Vuorinen, Research and Development, Seco Tools AB, S-737 82 Fagersta, Sweden Chemically vapour deposited (CVD) alumina is frequently used as a wearresistant coating on cemented carbide cutting tool inserts. Two crystallographic modifications of alumina are used, a-Alp3 and k-AI20 3, often in combination with TiN, TiC, and Ti(C,N). In this paper, the microstructures of single and multilayer coatings of CVD k-Alp, have been investigated. The aim of this work was to describe the detailed microstructure of the coatings and relate this to mechanical properties and tool life. Deposition of the experimental coatings was carried out in a computer-controlled hot-wall CVD reactor. The coatings were examined by analytical scanning and transmission electron microscopy (SEMIEDX and TEMlEDX).
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disordered solution phases. Thermodynamic values obtained from the model parameters as well as the calculated phase diagram are in good agreement with the experimental data. The intrinsic defect concentrations calculated from the model parameters for y - TiAl are compared with the predictions of the first principle calculation, the semi empirical relationship and the available experimental data, reasonable agreement is obtained. The model parameters for the ordered intermetallic phases can be converted to the format of sublattice model and Wagner Schottky model.
FUNDAMENTALS OF GAMMA TITANIUM ALUMINIDES I: Phase Equilibia and Transformations Sponsored by: MSD Flow & Fracture and Phase Transformations Committees Program Organizers: Kwai S. Chan, Southwest Research Institute, PO Drawer 28510, San Antonio, TX 78228-0510; Vijay K. Vasudevan, Dept. of Materials Science &Engineering, University of Cincinnati, PO Box 210012, Cincinnati, OH 45221-0012; Young-Won Kim, UES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432-1894 Monday, AM February 10,1997
9:20am PHASE DIAGRAM MODELLING OF TiAIALLOYS: Nigel Saunders, Thermotech Ltd, The Surrey Research Park, Guildford GU2 5YG, UK; IRC in Materials for High Performance Applications, University of Birmingham, Birmingham Bl5 2TT, UK
Room: 330E Location: Orlando Convention Center
The phase relations in Ti-Al based systems are by no means well established except for the case of a few specific ternary systems. This lack of information is now being exacerbated as new generation alloys are commonly multi-component in nature. Thermodynamic phase diagram modeling for Ti-AI-X systems has been presented previously which can now form the basis for the extension of the modeling technique to multi-component alloys. Examples of calculations for a variety of multi-component alloys will be shown and the effect of light elements such as 0 will also be modeled. An important factor in the success of the calculation method is that the ordering of the ~ phase to ~,can now be incorporated. I. N. Saunders, to be published in "Titanium '95: Science and Technology," eds. P. Bleckinsop et al (London: Inst. Materials, 1996).
Session Chairpersons: Michael J. Kaufman, Dept. of Materials Science and Engineering, Univ. of Florida, 201 Rhines Hall, Gainesville, FL 32611; Bruce A. MacDonald, National Science Foundation, 4201 Wilson Blvd., Arlington, VA 222039966
8:25am OPENING REMARKS: Kwai S. Chan, Southwest Research Institute, PO Drawer 28510, San Antonio, TX 78228-0510 8:30 am INVITED KINETIC AND MECHANISTIC ASPECTS OF THE a -7 Ym MASSIVE TRANSFORMATION IN TiAI ALLOYS: Ping Wang, D. Veeraraghavan, Vijay K. Vasudevan, Dept. of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45221-0012
9:40am EFFECTS OF SUBLATTICE ORDERING AND COMPOSITIONAL UNCERTAINITIES ON THE DETERMINATION OF ACCURATE AND PRECISE DEBYE-WALLER AND STRUCTURE FACTORS IN TiAI: S. Jayanthi, S. Swaminathan, H.L. Fraser, Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210; J.P. Jones, School of Metallurgy and Materials, University of Birmingham, Edgbaston Bl5 2TT, UK; D.M. Maher, Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC
The kinetics and temperature dependence of the a-7Y transformation in Ti(46-48) at.% Al alloys was studied using a novel computer-controlled temperature and electric resistivity acquisition system. Samples of the alloys were heated by controlled direct resistance heating and cooled at various rates by a helium jet quench. In situ, real time, high speed, simultaneous measurements of electrical resistivity and temperature were made during both heating and cooling. Using the resistivity and thermal arrest data, the start and finish temperatures of the various transformation modes, viz., lamellar, WidmanstattenJ feathery and massive were determined as a function of cooling rate. The data obtained was correlated with light and electron microscope observations to establish transformation diagrams, and to determine the growth rate of the massive g phase as a function of undercooling. The experimental data was fitted into physical models and thermodynamic quantities such as the enthalpies/driving forces of formation of the massive y were determined. The activation enthalpy for boundary diffusion estimated from this data indicates that the massive transformation is controlled by interfacial (rather than volume) diffusion. Defect structures in the massive y phase and the massive y-parent interface were characterized in detail by TEM. The implications of these studies on the mechanism of the massive transformation will be discussed. This research is supported by grants from the National Science Foundation (Dr. Bruce MacDonald, Program Monitor) and UESlWright Laboratory (Dr. Madan Mendiratta, Program Monitor).
There has been significant interest aimed at determining the anisotropy of charge densities in the intermetallic compound TiAI. Such determinations require the accurate measurement of low order structure factors, which in turn requires an accurate knowledge of the Debye-Waller factors of the given alloy/compound. Hence, the quest for assessments of charge densities in TiAI has involved determinations of the Debye-Waller factors and structure factors. The first of these are conveniently extracted from single crystal x-ray diffraction experiments, and it has been found that in samples whose compositions are Al rich sub-lattice ordering occurs, such that there are unequal values of the Debye-Waller factors for the two Ti sites. The effect of this sublattice ordering on the determination of the Debye-Waller factors has been assessed and will be discussed. Furthermore, the effect of compositional uncertainties on the determination of both Debye-Waller factors and structure factors has been investigated. It has been shown that sample compositions must be known to within ±0.15at. % for accurate determination of charge densities. These limitations will be discussed, and an experimental approach to overcome these will be detailed. This work has been supported by the National Science Foundation, Dr. Bruce MacDonald as Program Manager.
9:00am CALCULATION OF THE Ti-AI PHASE DIAGRAM: F. Zhang, S.L. Chen, Y.A. Chang, Department of Materials Science and Engineering, University of Wisconsin, Madison, WI 53706; UR Kattner, National Institute of Standards and Technology, Gaithersburg, MD 20899
10:00 am BREAK 10:20 am PHASE RELATIONS AND ALPHA DECOMPOSITION IN Ti-(25-50) AI ALLOYS: Y- W Kim, UES, Inc., Dayton, OH 45432
A thermodynamic description of the Ti Al system is developed in this study. Nine phases were considered in this system. They are disordered solution phases: liquid, a-(Ti, AI), I3-(Ti, AI), (AI); ordered intermetallic phases: !l.:zTi3AI, Y- TiAI, TiAI3 and stoichiometric compounds: TiAl" Ti,AI5 • The Redlich Kister equation was used to describe the excess Gibbs energy for the disordered solution phases; the generalized quasi-chemical model recently developed in our research group was used to describe the ordered intermetallic phases. The parameters describing these models were obtained by optimization using the experimental phase equilibrium and thermodynamic data available in the literature. The quasi-chemical model is an extension of the Bragg Williams model similar to the extension of the regular solution model for
The phase relations in Ti-(25-55) at.%AI involved in the decomposition and transformations of the high temperature alpha phase were investigated by conducting annealing/cooling experiments in a cooling/heating rate range of 0.2 - 100D C/min. X-ray and differential thermal analyses were conducted to determine phase relations, transformation temperatures and enthalpies involving various alpha-decompositions. Three types of decomposition reactions were found to exist, depending on composition and cooling rate, that is, I: a-7!l.:z; II: a-7a,-7L(a, + y); and III:a-7L(a' + y)-7L(a' 2 + y). In Types II and III, the undercooling and the lamellar spacing (Ar) for the lamellar struc-
13
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ture (L) were related to cooling rate and Al content. The ordering reaction in Type III, u~a., took place at increasingly higher temperatures (with Al content) than the Type I extrapolation due to the compositional changes. Both TYpe I and II reactions are favored in low AI-content alloys; however, they (TYpe II in particular) could take place even in Ti-48AI. This and the other reactions will be analyzed in detail.
emission TEM equipped with an imaging parallel EELS. Furthermore, results for u 2- Ti-36at. %AI and y -Ti-52at. %AI in binary lamellar TiAI are presented. The results of this study are discussed with a view to the mechanical behavior and the phase stability of y -TiAI based compounds. This work has been supported by a grant from the National Science Foundation with Dr. Bruce MacDonald as program manager.
10:40 am GRAIN REFINEMENT AND LAMELLAR FORMATION IN HOTWORKED Ti-(42-47)AI·(0·0.5)B ALLOYS: Yow. Kim, UES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432
GENERAL RECYCLING I: Theory Sponsored by: Jt. EPDILMD Recycling Committee Program Organizers: James C. Daley, Daley & Associates, 1020 W. Cactus Wren Drive, Phoenix, AZ 85021; John M. Rapkoch, Davy International, 2440 Camino Ramon, San Ramon, CA 94583
Small amounts of boron additions are known to effectively refine the alpha grains in hot worked TiAI alloys when heat treated in the alpha field, resulting in the formation of fine lamellar colony microstructures. The boron additions raise significantly the critical cooling rate above which the formation of fully lamellar structures begins to be suppressed. Since this cooling rate allows the lamellar spacing to be controllable to a greater range, it is critical to understand the formation mechanism and kinetics of gamma laths in the presence of boron (in the form ofborides). For this, annealing and cooling experiments and microstructural observations have been conducted on forged alloys of Ti-(42-47)Al-(0-0.5)B. DTA measurements are underway to detect the undercoolings before gamma precipitation in the alpha matrix as a function of cooling rate. The results will be presented and analyzed to explain the role of borides on the grain refinement, the formulation of gamma precipitates, and the retardation of nonlamellar microstructure formation.
Monday, AM February 10, 1997
Room: 230C Location: Orlando Convention Center
Session Chairpersons: James C. Daley, Daley & Associates, 1020 W. Cactus Wren Drive, Phoenix, AZ 85021; John M. Rapkoch, Davy International, 2440 Camino Ramon, San Ramon, CA 94583
8:30am USE OF PVC AS A CHLORINATING AGENT IN THE RECYCLING OF METALS: F. Tailoka, D.J. Fray, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB2 3QZ, United Kingdom
11:00 am THE a2~g SHEAR TRANSFORMATION: P.M. Hazzledine, UES, Inc., 4401 Dayton-Xenia Rd. Dayton, OH 45432; B.K. Kad, Dept. of Applied Mechanics & Engineering Science, University of California-San Diego, La Jolla, CA 92093; V.K. Vasudevan, Dept. of Materials Science and Engineering, Univ. of Cincinnati, Cincinnati, OH 45221
The standard free energy of formation of the oxides of the ferrous metals is generally more negative than that for the chlorides whilst the reverse is true for the equivalent compounds of the non-ferrous metals. As a source of chlorinating agent PVC has been used. PVC has the nominal formula C2H2HCI. On combustion in air, considerable heat is generated and hydrogen chloride, water vapor and carbon dioxide are evolved. It can be regarded as a free source of heat and a chlorinating agent if scrap PVC is used. In this work, this gas has successfully been used to separate zinc, lead and copper from residues such as Jarosite, EAF dust and waste materials containing copper. Dioxins were not detected either in the residues or the condensed chlorides.
When a hexagonal close packed crystal, with ideal clu ratio, is sheared by Shockley dislocations on alternate basal planes the resulting crystal is face centered cubic. The six Shockley vectors generate cubic structures in two orientations which are twins of each other. When the D0 19 structure is sheared by the same six Shockley vectors the result is three different 12H structures and their three twins. These 12H structures are composed of tetragonal unit cell building blocks, having axial ratios I: I :,h In this description, all of the {100} planes have alternate compositions Ti, TiAI and the unique c axes are in six different directions, one resulting from each of the six Shockley shears. The 'tetragonal' description of the structures is the same as the tetragonal structure Lloexcept that in Llo the {IOO} planes have alternate compositions Ti, AI. Thus, shearing the D0 19 structure in one of the Shockley directions by 112";2 creates a crystal structure which is as close to Llo as the composition allows. The six variants of gamma may therefore be formed from a single crystal of Uz by the operation of dislocations with the six available Shockley Burgers vectors so long as the composition may be corrected by diffusion.
8:55am HYDROCHLORIC LEACIDNG OFMAGNESIUM·BEARING MATE· RIALS: V.A. Lelio, C.A. Silva, M.G. Menenzes, I.e. Pires, L.G. Macedo, School of Mines, Federal University of Ouro Preto, Praca Tiradentes, 20; Ouro Preto, MG, 35400-000, Brazil Asbestos industry produces large amounts of serpentine (magnesium silicate) tailings. The effect of this on human health is well-known. Besides this, the processing of a Brazilian rock known as "Pedra sabiio" (soap stone) generates powders that are discharged in the environment. This material is also a potential resource of magnesium. Magnesium oxide is used in many industries like refractory, waste water treatment, among others. The applicability of hydrochloric leaching for the recuperation of magnesium oxide from those materials has been investigated. The effect of time, temperature, particle size and solid/liquid ratio, on the leaching of magnesium and impurities, is discussed.
11:20 am A SYSTEMATIC STUDY OF THE ELECTRONIC STRUCTURE OF STABLE AND METASTABLE FORMS OF y·TiAI: J.M.K. Wiezorek, X.D. Zhang, R. Banerjee, H.L. Fraser, Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210 Numerous theoretical, first principle calculations studies have shown that the interatomic bonding in TiAI is a mixture of covalent and metallic. There is a need to complement these studies with experimental observations. Electron energy loss spectroscopy (EELS) is capable of providing electronic structure information through the near edge fine structure in core loss peaks, since these reflect the combined effects of bonding parameters such as charge transfer, hybridization, and variation of the crystal and ligand field. In this paper, EELS has been used to study the electronic structure of stable and metastable forms of y -TiAI. The near-edge EELS signatures of the equilibrium phases at Ti-25at. %Al, Ti-75at. %Al and Ti-52at.%Al have been used to assess the suitability of this experimental method for the study of the electronic structure in y-TiAI compounds. Metastable phases of y -Ti-50at.%Al and u 2- Ti-48at. %Al have been generated by very rapid quenching from the a-phase field, and thin amorphous films of a-Ti-48at.%Al have been deposited by magnetron sputtering. The near edge structure of these phases have been studied using a field
9:20am THE RECOVERY OF TELLURIUM FROM COPPER ANODE SLIME BY HYDRO·METALLURGICAL PROCESSES: K.-1. Rhee, C.-K. Lee, Korea Institute of Geology, Mining and Minerals, P.O. Box 14, Taejon, Korea 305-350; H.S. Kim, T.H. Kim, e.S. Yoo, H.J. Sohn, Y.-f. Kim, Dept of Mining & Petroleum Engrg., Seoul National University, 151-742 Seoul, Korea The recovery of tellurium from pretreated copper anode slime was carried out by a series of hydrometallurgical processes. These include leaching of cemented Te at high temperature with oxygen purging in NaOH solution, precipitation of Te02 from leach liquor, leaching of Te02 in alkaline solution, precipitation of impurities by N~S, and electrowinning of tellurium. The optimum conditions of each process were determined and discussed in terms of various parameters associated with each step to maximize the recovery
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and purity of tellurium.
GLOBAL EXPLOITATION OF HEAP LEACHABLE GOLD DEPOSITS I: Exploration and Development of Shallow Heap Leachable Gold Deposits
9:45 am BREAK 10:00am PRODUCTION OF NON-FERROUS METALLIC CONCENTRATES FROM ELECTRONIC SCRAP: Jorge Alberto Soares Tenorio, Ricardo Perez Menett, Arthur Pinto Chaves, Department of Metallurgical and Materials Engineering, University of Sao Paulo, 05508-900, Sao Paulo, Brazil
Sponsored by: EPD Process Mineralogy, Precious Metals, Aqueous Processing Committees; Newmont Mining Corporation, Denver, CO Program Organizers: Donald M. Hausen, Consultant, 1767 S. Woodside Dr., Salt Lake City, UT 84124; David Dreisinger, University of British Columbia, Dept. of Metals & Materials Eng., 309-6350 Storres Rd., Vancouver, BC V6T 124, Canada; Richard Kunter, Advanced Science, Inc., 405 Irvine St., Suite 401, Lakewood, CO 80278; William Petruk, CANMET, 555 Booth St., Ottawa, Ontario J1A 081; Richard D. Hagni, University of Missouri-Rolla; Dept. of Geology & Geophysics, Rolla, MO 65401
Electronic components have metals with important valor like Au, Ag and Cu. These metals have a high performance in electric conductance. The recycling of scrap, however is too difficult because we have the presence of other metals like Fe, AI, Zn, Sn, more ceramics and plastics, all together in electronic components. This work had for subject define one way for physical separation. We have researched methods that obtained metallic concentrates nonferrous. By the way we have used three types of scrap. We have used equipment of mineral processing. The metallic concentration make more easy the recuperation of metals because short the volume of material used. We have obtained, since of types studied an middle compassion of plastic, ceramic and metals.
Monday, AM February 10, 1997
Room: 231C Location: Orlando Convention Center
Session Chairpersons: Donald M. Hausen, Consultant, Salt Lake City, UT; Leonard Harris, Consultant and Former General Manager, Minera Yanacocha, Peru
10:25am DESIGN AND CONSTRUCTION OF A SMALL-SCALE USED BEVERAGE CAN RECYCLING UNIT: Jim S-J. Chen, Frederick Higgins, Joseph Vinch, James Kelly, Steven Smigiel, Center for Environmental Studies, College of Engineering, Temple University, Philadelphia, PA 19122
8:30 am Opening Remarks Donald M. Hausen, Program Organizer and 1997 Chairman of the TMS Process Mineralogy Committee 8:40am MINE GEOLOGY AND PROCESS ORE CONTROL AT NEWMONT MINES, CARLIN, NV: Joseph C. Rota, Newmont Exploration Ltd., Carlin, NV 89822
A small-scale recycling unit for used beverage cans is designed, constructed and tested. The unit consists of a rotary kiln for delacquering, a gas-fired furnace crucible for melting, a baghouse for pollution control and an air recirculating system for heat recovery and oxygen control. The delacquering kiln utilizes a counter flow thermal decoating process and the optimized operating condition was found to be at lOOO°F, 6-7% Oz and a residence time of 15 minutes. In melting, a special salt mixture is made by combining cryolite and sodium chloride. The salt mixture has a low melting temperature (
The Carlin Trend, located in NE Nevada, has produced over 17 million ounces of gold from Newmont's open pit and underground operations since 1965. Oxidized portions of sediment-hosted disseminated submicron-sized native gold is mostly amenable to dump or heap leaching, yielding 50 to 70% recovery of contained gold. Metallurgical control and grade of heap leach ores are maintained by geological techniques and standard assays. Mine geologists provide field observation and mineralogic data by daily visual blasthole logging. Refractory components are separated from oxide to ensure high recovery. Geologic and assay data are combined to create mine polygons in an engineering computer database. Mining selectivity is thus enhanced by ore control geologists who make production decisions based on direct mineralogic observations at active mine faces.
10:50am OPTIMIZATION OF SALT COMPOSITION IN THE RECYCLING OF ALUMINUM CANS: Jorge Alberto Soares Tenorio, Fabio Delgado, Department of Metallurgical and Materials Engineering, University of Sao Paulo, 05508-900, Sao Paulo, Brazil
9:05 am BASIC CONCEPTS OF OXIDE GOLD DEPOSITS AND EXPLORATION STRATEGY: E. Daniel Baker, Senior Mineralogist, Newmont Metallurgical Services, 417 Wakara Way, Salt Lake City, UT 84108
During the melting processing of aluminum can scrap there is a considerable loss of metal due of metal trapping in the dross. Among all techniques available to recover this kind of scrap, the one using saline fluxes, based on NaCI I KCl equimolar composition and fluorides addition is outstanding. The investigation into the melting of AA3004 and AA5l82 alloys (materials which the body and the lid of beverage cans are made of), the effect of delacquering, and the influence of different fluxes and the temperatures on the process yield are the main objectives of this work. Melting tests were carried out in order to access the effect of fluorides and the melting temperature on the recycling process yield. The fluoride efficiency for the temperature of 750°C was: CaPz < NaP < Na3AlF6 < KF.
The term oxide gold deposits, refers to gold-bearing veins, faults, and shear zones that typically contain appreciable amounts of oxidized ore or gossanous material, resulting from oxidation of sulfides. The concept of oxide gold deposits underwent a dramatic change after the discovery of the Carlin gold mine in north central Nevada in early 1960's, and now implies large tonnage, low-grade bulk minable deposits that are processed by milling and/or heap leach methods. Oxide gold deposits may be classified into two types: (1) primary oxide ores derived directly from the effects of hydrothermal alteration on oxidized host rocks, and (2) secondary oxide ores derived from the epigenetic effects of circulating post mineral fluids oxidizing gold-bearing sulfides. Each type of oxide gold deposit has unique diagnostic mineralogic and metallurgical characteristics, that must be addressed in order to achieve a successful exploration strategy. 9:30am BLUE STAR SUBDISTRICT ZONED ALTERATION AND GOLD MINERALIZATION AND ITS INFLUENCE ON MINE OPERATIONS, CARLIN TREND, EUREKA COUNTY, NV: Cindy L. Williams, Newmont Exploration Ltd., Carlin NV 89822 Blue Star subdistrict open-pit gold deposits include multiple mines with 1.194 million ounces reserve and past production totalling 3.144 million ounces.
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ali
The deposits are characterized by zoned alteration, including: 1) silicified core with erratic gold grade; 2) adjacent mill-grade (>0.04 ozlst) intense quartzsericite-pyrite alteration; 3) enveloping heap-leach grades (0.006-0.04 oz/st) weaker sericite-kaolinite-quartz-pyrite alteration; 4) surrounding decarbonatized and intensely argillized waste and leach grade ore; 5) pervasively decarbonated waste; and 6) peripheral waste with local propylitic and weaker decarbonated alteration. Each alteration assemblage is characterized by distinct rock strength parameters that influences geotechnical pit slope design, as well as metallurgy and optimizing of drilllblast cycles. Alteration of barren assemblages extend hundreds of feet beyond orebodies.
HIGH TEMPERATURE SUPERCONDUCTORS I: BSCCO Conductor Development Sponsored by: Jt: EMPMD/SMD Superconducting Materials Committee Program Organizers: U. Balachandran, Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439; Paul J. McGinn, University of Notre Dame, Notre Dame, IN 46556
Room: 315A Location: Orlando Convention Center
9:55 am BREAK
Monday, AM February 10, 1997
10:05 am GEOLOGY AND MINERALOGY RELATED TO HEAP LEACHING AT THE RAIN MINE, ELKO COUNTY, NV: Dean G. Heite, Newmont Exploration Ltd., Carlin NV 89822
Session Chairpersons: Gye-Won Hong, Superconductivity Research Laboratory, KAERI, Taejeon, Korea; P. Haldar, Intermagnetics General Corp., Latham, NY
8:30 am INVITED POWER APPLICATIONS OF HIGH TEMPERATURE SUPERCONDUCTORS: P. Haldar, M.S. Walker, D.W. Hazelton, J.G. Hoehn, Jr., Intermagnetics General Corporation, Latham, NY 12208
Gold Mineralization at Rain is largely hosted by Mississippian Webb Formation consisting of interbedded siltstones and mudstones. The NW-striking SE-dipping Rain fault is a main feeder structure for the deposit. Five ore types based on XRD and visual rock chip logging were identified: argillaceous (>30% clays); siliceous «20% barite; siliceous-baritic (20-40% barite); baritic (>40% barite); and calcareous (major carbonate minerals). The Rain heap-leach pad was commissioned in 1988, and to date 10.3 million tons of ore averaging 0.023 ozlst have been treated. Recovery to date through December 95 is approximately 56% for a tota1132,453 ounces of gold produced. Two major factors have contributed to low leach recoveries at Rain: 1) excess argillaceous ore than expected on the pad, mostly late in the mine life, and 2) about half of the heaps were run-of-mine ore with no agglomeration. Testwork on leach grade composites indicated recoveries near 69% for material crushed to minus 1 1/5".
Intermagnetics has concentrated on manufacturing long lengths of silver sheathed Bi-2223 and surface coated Bi-2212 HTS conductor. Development work has led to the successful manufacture of Bi-2223 multifilament conductor in lengths exceeding 1 km, with properties useful for most electric power applications. Surface coated, low cost, Bi-2212 conductor in lengths over 400 meters are now also being produced. Several lengths of high performance tapes have already been delivered to GE to wind the first HTS generator coil. The coils were successfully tested in a steady state, conduction cooled environment generating 40,000 amp-turns at 23.5 K. Novel and unique hybrid magnet designs are being designed and built with the availability of both Bi2212 and Bi-2223 HTS conductors. The demonstration and test of a pre-prototype 1 MVA transformer utilizing HTS windings is planned in collaboration with ORNL, Waukesha Electric, and RG&E. The development of the largest HTS coils is continuing, for the construction of a 15 KV fault current limiter as part of the DOE-SPI program with Lockheed Martin, Southern California Edison, and LANL. Several high amp-turn coils have also been fabricated and delivered to the U.S. Navy to demonstrate a high horse power HTS homopolar motor. These demonstrations indicate the rapid progress being made to develop commercial applications of high-temperature superconductors.
10:30 am GEOLOGY OF THE TUSC GOLD DEPOSIT, EUREKA COUNTY, NV: PaulO. Malan and Leroy Schutz, Newmont Exploration Ltd., Carlin NV 89822 The Tusc gold deposit, located 8 miles NW of Carlin, Nevada, along the Carlin trend, is one of several structurally controlled gold deposits associated with the Good Hope fault within the Maggie Creek Subdistrict. Mining commenced in 1994 with an oxide reserve of 780,000 ounces of gold averaging 0.039 opt Au. The Good Hope Fault forms the SW edge of the Schroeder Mountain uplift (Carlin Window) and juxtaposes carbonate rocks of the Roberts Mountains Formation against siliceous mudstone, chert and siltstone of the Rodeo Creek Unit. Submicroscopic gold is disseminated in the shear zones of the Good Hope fault system and in crosscutting northeast-striking, highangle faults in the lower plate carbonates in the immediate hanging wall. Wallrock alteration includes argillization, decalcification, silicification, and alunite veining, supergene leaching and oxidation. Arsenic forms a strong halo around the ore and an antimony anomaly occurs in the upper part of the deposit.
8:50 am INVITED CONTROLLED PRECIPITATION OF SECOND PHASES IN (Bi,Pb)2223 CERAMICS AND ITS INFLUENCE ON THE PINNING: P. Majewski, S. Kaesche, A. Sotelo, F. Aldlinger, Max-Planck-Institut ftir Metallforschung, Pulvermetallurgisches Laboratorium, Heisenbergstr. 5, D70569 Stuttgart Taking the temperature dependent Pb solubility of (Bi,Pb)2+xSr2Ca,CuPIO+d [(Bi,Pb)2223] into account, it is possible to precipitate various second phases in single phase (Bi,Pb)2223 ceramics at temperatures below 840°C, i.e., Pb.SrsCu0 1o, Ca,Cu03, CuO and Bi 2Sr2CaCup8 (Bi2212). At 800°C, the kinetic of the formation is fast resulting in ]..lm-sized second phase precipitates after about 6 h. The J, of the samples increases with precipitation, indicating increased pinning properties of the ceramics. After a maximum increase of J at about 3 h, J, decreases again. '
10:55 am MULTI-METAL RECOVERABLE RESERVE ESTIMATES AND WHITTLE PIT OPTIMIZATION OFMILLAND HEAP LEACHABLE GRADE ORES AT THE MCCOY BLACK COVE MINE, NV: Songlin Zhang, Mining Engineer, Echo Bay Minerals Company, McCoy/Cove Mine, #1 McCoy Mine Rd., Battle Mountain, NV 89820
9:10 am INVITED EFFECT OF LEAD CONTENT ON PHASE EVOLUTION AND MICROSTRUCTURAL DEVELOPMENT IN Ag-CLAD Bi-2223 COMPOSITE CONDUCTORS: N.N. Merchant, v.A. Maroni,A.K. Fischer, S.E. Dorris, W. Zhong, N. Ashcom, Argonne National Laboratory, Argonne. IL 60439
The McCoy/Cove mine, located in Eureka-Battle Mountain trend of Nevada, is a gold and silver deposit. Case studies of recoverable reserve estimation for gold and silver were made using multiple indicator kriging and volume variance correction. The grade tonnage distributions of recoverable reserves were constructed and compared with the distributions defined by blast hole assays. Optimal pits were generated by Whittle 4D pit optimization package to analyze the impact of different processing recoveries at different economic cutoffs. The results were compared with ordinary kriging. The study indicates that the proposed method for multi-mineral recoverable reserve estimation is more accurate than kriging in terms of grade and tonnage. The method of using recoverable reserves for pit optimization will maximize global reserve recovery and revenue, and is more efficient than condition simulation regarding computing power.
Silver-sheathed monofilamentary BiL8PbxSrL98CaL97Cu3080y (Bi-2223) tapes prepared by a two powder process that used powder containing varying lead contents, x, from 0.2 to 0.5 were subjected to thermomechanical processing and then characterized by XRD, SEM and EDX. Texture was studied using image analysis software on scanned SEM images. It was found that tapes with low lead content (0.20 and 0.25) showed incomplete conversion to Bi·
16
2223, had small grain size, and poor c-axis texture. Tapes having higher lead content (0.4 and 0.5) also showed incomplete conversion and the presence of lead-rich secondary phases. Tapes with lead contents of 0.30 and 0.35 showed complete conversion to Bi-2223, had the least amount of secondary phases, showed best c-axis texture, and had the highest Jc. The carbon content of the precursor powder also had a strong influence on secondary phase chemistry. Work was supported by the U.S. Department of Energy (DOE), Energy Efficiency and Renewable Energy, as part of a DOE program to develop electric power technology, under Contract W-31-109-Eng-38.
10:40 am INVITED MECHANICAL DEFORMATION AND INHOMOGENEITY OF BiSrCaCuO/Ag COMPOSITES: Z. Han and T. Freltoft, NKT Research Center NS, Sognevej 11, DK-2605, Brjllndby, Denmark
9:30 am INVITED EFFECT OF PARTICLE SIZE REDUCTION ON THE MICROSTRUCTURE EVOLUTION AND CRITICAL CURRENT DENSITY OF Ag! Bi-2223 TAPES: Weon-Ju Kim, Jae-Keun You, Ho Jin Lee, Hee-Gyoun Lee, Gye-Won Hong, Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Taejon 305-600, Korea
The mechanical deformation of BiSrCaCuOIAg composites is generally an inhomogeneous process. Inadequate control of the deformation process results in sausaging and cracking, degrading the superconducting properties of the composite and reducing its mechanical strength. In this paper, we will apply our model of "powder flow" to describe the mechanical deformation process of BiSrCaCuOIAg composites wires and tapes. Furthermore, results from experiments using a new deformation method "semi-continuous pressing" will be presented. By this method, it is possible to produce superconducting tapes with better homogeneity than obtained by conventional rolling. The influence of mechanical deformation on the strength of the tape, especially the bending strength, will also be discussed.
The effects of the particle size of precursor powder on the microstructure and J, of Ag-sheathed Bi-2223 tapes were investigated. The calcined powder with overall composition of Bi189Pbo41Sr201C~2Py was milled for various times using planetary ball mill. The transport property of the tapes was found to depend strongly on the particle size of the precursor powder. Enhanced reactivity of the milled powder facilitated the formation of 2223 phase and resulted in an increase of J,. Excessive milling, however, led to the amorphisation of the powder and degraded the electrical property of the tapes.
11:00 am INVITED HIGH TEMPERATURE SUPERCONDUCTOR DEVELOPMENT AT TOSHIBA: HIGH TENSILE STRENGTH AgMg(Ni) SHEATHED Bi2223 CONDUCTOR AND COILS: Y. Yamada, K. Yamamoto, K. Tasaki, H. Onoda, O. Horigami, Toshiba R&D Center, 4- I, Ukishima-Cho, Kawasaki, 210 Japan; T. Koizumi, T. Hasegawa, Showa Electric Wire and Cable Co., Ltd., 2-1-1, Odaskae, Kawasaki 210, Japan; T. Kiyoshi, K. Inoue, National Research Institute for Metals, 1-2-1, Sengen, Tukuba, Ibaraki 305, Japan
9:50am EFFECTIVE FABRICATION PRACTICES FOR Ag-SHEATHED SUPERCONDUCTOR: D.-W Yuan, M. J. Pollock, 1. Kajuch, Concurrent Technologies Corporation, Johnstown, PA 15904
Recent activity of high temperature superconductors and its application at Toshiba will be presented. We have been developing high tensile strength conductor using AgMg(Ni) sheath material. Short samples exhibited 200 MPa of 0.2% yield strength which was 4 times to 10 times higher than that of the conventional Ag-sheathed conductor and also higher than the Nb8Sn conductor. Recently the high tensile strength conductor 100m long was successfully fabricated and wound for the energizing test at 21 Tesla back up filed. The coil was successfully excited without any degradation. We have been also studying the effect of sausaging on critical current density. The sausaging started to occur clearly when the Vickers hardness of the oxide core was higher than that of Ag sheath. This implies that the harder sheath materials such as AgMg sheath may suppress the sausaging and improve critical current density.
The powder-in-tube (PIT) process has been widely used to fabricate long lengths of superconducting wires and tapes. However, problems associated with irregularly shaped cross sections resulting from the metalworking process have been identified and need to be addressed. In this investigation, Agclad Bi2Sr2CaCu,08 superconductors were formed by using different wire drawing and tape roIling practices. The effects of annealing and drawing direction on geometric characteristics of the round wires were determined. Also, the impact of reduction in thickness per pass and roll configuration on the properties of the tapes was investigated. The study shows that geometrical uniformity and core dimensional stability are strongly influenced by the roIling parameters chosen. A combination of small roll diameter and small reduction per pass reduces dimensional variations. This practice also leads to higher critical current densities at cryogenic temperatures in the resulting superconducting tapes. Recommendations for optimum fabrication schemes for wires and tapes are presented.
11:20 am RECENT DEVELOPMENTS IN THE FABRICATION OF IDGH-J,AgCLAD (Bi,Pb)2Sr2C3zCupy CONDUCTORS: U. Balachandran, A.N. Iyer, Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439; M. Lelovic, T. Deis, N.G. Eror, Dept. of Materials Science and Engineering, University of Pittsburgh, Pittsburgh, PA 15261; P. Haldar, Intermagnetics General Corp., Latham, NY 12110
10:10 am BREAK We have resolved the issue of current distribution inside Ag-clad (Bi,Pb)2Sr2C~Cupy (Bi-2223) superconductor tapes by showing that the region of high critical current density (J,) is next to the Ag sheath. In this talk, we report a J, value >10' Ncm2 at 77 K in a self-field in Bi-2223 tapes made by the Ag-wire-in-tube method, in which a silver wire was introduced into the Ag tube. The Ag wire extended along the entire length of the tape. At 77 K and in self-field, a maximum J, of 2 x 10' Ncm 2 (critical current, I" = 22 A) was measured after three pressing cycles. Recently, we analyzed the transport current properties of Ag-clad Bi-2223 tapes as a function of cooling rate. A comparison between furnace-cooled and slow-cooled tapes showed that the slow-cooled tapes reached I, values two or three times higher than those of the furnace-cooled tapes. Based on our observations, a cooling schedule that includes several intermediate cooling steps is suggested and will be discussed in this talk. Work at ANL and part of the work at IGC is supported by the U.S. Department of Energy (DOE), Energy Efficiency and Renewable Energy, as part of a DOE program to develop electric power technology, under Contract W-31-109-Eng-38.
10:20 am FABRICATION OF TUBULAR SUPERCONDUCTOR STRUCTURES: J.F. Bingert, T.G. Holesinger, B.L. Bingham, D.A. Korzekwa, MST-6, Los Alamos National Laboratory, Los Alamos, NM 87545 A tubular architecture provides many potential attributes when applied to bulk superconductor structures. These include enhanced structural stability compared to wires and tapes, and isotropic field dependence transverse to the conductoris long axis. At the same time, virtues associated with traditional OPIT processing may be preserved, such as a thin, dense HTSC layer with basal-plane texture. In this study, candidate deformation processing routes for tubular composite conductors were investigated in order to determine their potential to produce desired structures and properties. These processes included tube drawing, tube ironing, and hydrostatic extrusion. For tube drawing and ironing, an HTSC precursor form was isostatically pressed over a mandrel, while the hydrostatic extrusion billet was manually loaded with powder. The as-deformed and sintered tubes were characterized for geometric uniformity, density, texture, and transport properties. An analysis of the relative stress states encountered during tube processing compared with roIling will also be presented.
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microstructure show reduced amounts of primary and anelastic creep strains, in comparison to a+B heat treated specimens with globular a-grains and variable amounts of a+B mixture. The results obtained show also very similar kinetics of primary creep build up and strain recovery and suggest similar deformation mechanisms. Based on TEM investigations of dislocation structures of crept specimens, the results are discussed with respect to different mechanisms of dislocation motion under the effect of internal stress.
11:40 am INVITED DEVELOPMENT OF HTS-POWER TRANSMISSION CABLES AND RESISTIVE FAULT CURRENT LIMITERS: H.-W Neumiiller, Siemens AG, Corporate Research and Development, P.O. Box 3220, D-91050 Erlangen, FRG Our long-term joint project covers both the development of HTS conductors and the realization of junction models demonstrating the feasibility of future prototypes. Multifilament 2223 BPSCCO tapes are reproducibly produced having j,-s up to 30 kAlcm2 for short samples and i 220 kAlcm2 for lengths 2110 m. In a fIrst step two layer 10 m cable dfunction model was machine wound, which showed a current capacity of 1100 A. No degradation was found under bending tests down to bending radii of I m. The switching elements for resistive fault current limiters consist of ceramic plates with meander shaped YBCO coatings. Two ways are investigated: both polycrystalline YSZ substrates coated by biaxially in plane oriented IBAD YSZ buffer layers (pc) and single crystal sapphire substrates (sc). 10 x 10 cm2 pc switching elements have been produced up to a switching power of 1500 VA (j, = 60 kAlcm2). Improvements of the large scale IBAD-deposition raised j, above 1()5 Alcm2, small samples (I x I cm2) attained j, = 1 MAlcm2, 10 x 10 cm2 pcor alternatively" 0 sc switching elements are the basis of the proposed 100 kVA function model.
9:20am MINIMIZING BETA FLECKS IN THE Ti-17 ALLOY: C.E. Shamblen, GEAircraft Engines, One Neumann Way, MD M85, Cincinnati, OH 452156301 Normal liquid to solid partitioning ofCr during ingot solidifIcation for the Ti17 alloy can result in the formation of a segregation anomaly called B flecks. These B flecks can exhibit a signifIcantly lower Btransus than the alloy; they may also present mechanical property issues. While the major thrust toward minimizing B flecks is through melt process control, this paper addresses the capability of reducing the extent of Cr segregation using a high temperature B fIeld homogenization heat treatment. The interdiffusion coefficients for Cr in B phase Ti-17 were determined and used in diffusion equations to calculate the rate of dissipation of the segregated regions. Correlation is shown for the calculated, and critical experiment demonstrated, increase in the B fleck B transus temperature with the time and temperature of these homogenization heat treatments.
HIGH TEMPERATURE TITANIUM ALLOYS
9:40am ANISOTROPIC BIAXIAL CREEP OF TEXTURED Cp-Ti TUBING: K. Linga Muny, Ratnaji R. Kola*, North Carolina State University, Box 7909. Raleigh, NC 27695-7909;*now with AT&T Laboratories, Murray Hill, NJ
Sponsored by: SMD Titanium Committee Program Organizers: R.G. Rowe, M.F.X. Gigliotti, GE Corporate Research and Development, P.O. Box 8, K-l MB103, Schenectady, NY 12301; D. Eylon, Univ of Dayton, Materials Engineering, K 1262, 300 College Park, Dayton, OH 45869; P.J Bania, Mgr. Quality and Technology, Timet, POBox 2128, Henderson, NV 89015
Monday, AM February 10, 1997
Biaxial creep behavior of thin-walled tubing of cold-worked stress-relieved cp-titanium alloy was investigated using internal pressurization superimposed with axial load at ??? K. Creep anisotropy was characterized in terms of a creep locus at a constant energy dissipation with power-law dependencies of the component (hoop and axial) strain-rates under varied stress ratios. The experimental results were fIt to the modifIed Hill's equation with anisotropy parameters, R and P which are also the contractile strain (rate) ratios. The crystallographic texture of the tubing was characterized through inverse and direct pole fIgures from which the ~rystallite Qrientation Qistribution functions (CODF) were derived. The CODF was combined with plasticity model based on power-law stress dependence of the strain-rate and dominance of basal prism and pyramidal slip systems were considered. In contrast to the recrystallized materials, experimental results deviated from the prism-model predictions albeit the deformed microstructures revealed only prism dislocations. These differences are attributed to the grain-shape anisotropy due to cold-work. Quantitative analyses of the superimposed effects of grain shape anisotropy due to cold-work. Quantitative analyses of the superimposed effects of grain shape anisotropy on grain orientation anisotropy (texture) are underway and the results to-date will be presented. This work supported by the National Science Foundation.
Room: 231B Location: Orlando Convention Center
Session chairperson:M.F.X. Gigliotti, GE Corporate Research and Development, P.O. Box 8, Schenectady, NY 12301
8:30 am INVITED ELEVATED TEMPERATURE MECHANICAL PROPERTIES OF THE NEAR-a TITANIUM ALLOY TIMETAL 1100: 1. Lindemann, A. Styczynski, L. Wagner, Technical University of Brandenburg at Cottbus, 03013 Cottbus, Germany Fully lamellar with fIne (150 m) and coarse (500 m) prior B grain sizes as well as duplex structures with a p volume fractions of 20 and 60% (15 m a p size) were prepared in TlMETAL lIOO by thermomechanical processing. Tensile behavior and HCF properties at R=-1 and R=O.1 were evaluated at ambient and elevated (600°C were performed at nominal stresses of 210 and 300 MPa. The fIne grained fully lamellar microstructure combines the advantages of the B annealed structures (excellent creep resistance) and duplex structures (high tensile ductility) without suffering from the disadvantages of the duplex structures, i.e., anomalous mean stress sensitivity of the fatigue strength and poor creep strength. Both properties are related to the presence of the a p phase. The fatigue and creep results on the various microstructures will be interpreted in terms of phase morphologies, crystallographic textures and particular deformation mechanisms.
10:00 am BREAK 10:20 am MICROSTRUCTURAL STABILITY OF A IDGH TEMPERATURE a-~ Ti ALLOY: X. D. Zhang', J M.K. Wiezorek', DJ. Evans2 and H.L. Fraser';'Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus, OH 43210; 2Materials Directorate, Wright Laboratory,. WLIMLLM, Wright Patterson AFB, OH 45433
9:00am PRIMARY AND ANELATIC CREEP BEHVIOUR OF A HIGH TEMPERATURE NEAR a- Ti-ALLOY: M. Es-Souni, Fachhochschule Kiel, Institute of Materials Technology, Legienstr. 25, Kie124103, Germany
The microstructural development of Ti-6AI-2Mo-2Cr-2Sn-2Zr-0.2Si(Ti-622-22S) alloy after various heat treatments has been examined by optical microscopy, scanning electron microscopy (SEM), conventional transmission electron microscopy (CTEM) and high resolution electron microscopy (HREM), coupled with high spatial resolution microanalysis. Partitioning of alloying elements and the precipitation of intermetallics as a function of heat treatment are the main issues addressed in this paper. Titanium silicide . athermal (0 and ordered
The creep behavior of a high temperature near a alloy Ti 6242 Si has been investigated in the stress range from 160 to 350 MPa and a temperature range from 500 to 6000C, using constant stress tensile creep experiments. Emphasis has been put on primary and anelastic creep behavior and their dependencies on stress, strain and processes microstructures. It is shown that both primary and anelastic creep strongly depend on creep strain and applied stress. Increasing stress and/or strain results in higher primary and anelastic creep strains. Furthermore, B-heat treated specimens with a fully transformed B-
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for comparison. The significance of these observations will be discussed in view of the fundamental understanding and further control of the structural stability of these type of o:-~ Ti alloys.
INTERNATIONAL SYMPOSIUM ON PROCESSING AND HANDLING OF POWDERS AND DUSTS I: Injection of Powders and Dusts
10:40 am INFLUENCE OF ENVIRONMENT ON THE FATIGUE CRACK PROPAGATION BEHAVIOR AT ELEVATED TEMPERATURE OF THE Ti-ALLOY IMI 834: O. Schauerte" A. Gysler, G. Lutjering, Technical University Hamburg-Harburg, 21071 Hamburg, Germany; S. Lesteriin, J. Petit, E.N.S.M.A., 86960 Futuroscope Cedex, France
Sponsored by: Jt. EPDIMDMD Synthesis, Control, and Analysis of Materials Processing Committee, Powder Metallurgy, Reactive Metals, and Non-Metallic Materials Committees Program Organizers: Thomas P. Battle, DuPont, Edgemoor, DE 19809; Hani Henein, University of Alberta, Edmonton, AL; Gordon Irons, , 1280 Main StWest, Hamilton, Ontario L8S 4L7; John Moore, Colorado School of Mines, Dept. of Met and Matis, Golden, CO 80401; Beverly Aikin, CWRU - NASA LeRC, 21000 Brookpark Road, MS 106-5, Cleveland, OH 44135; Iver Anderson, Ames Laboratory, Iowa State University, 122 Metals Development Bldg, Ames, IA 500113020; John Pusateri, Horsehead Resources Development, Monaca, PA
The fatigue crack propagation behavior of the high-temperature Ti-alloy IMI 834 was investigated at a test temperature of 500°C under different environmental conditions: vacuum, laboratory air, and Ar =50% relative humidity. Two different microstructures were compared, a pure lamellar and a bi-modal structure, consisting of 20% equiaxed primary a phase in a lamellar matrix. Crack propagation tests were carried out on CT-specimens under constant amplitude sinusoidal loading conditions with a frequency of 30 Hz at R = 0.1 and R =0.6. The results showed for example, that at R =0.6 fatigue crack propagation for both microstructures occurred at much lower near threshold .1K- values (4 MPa - m 112) in the two aggressive environments (air, humidAr) as compared to those measured in vacuum (10 MPa - mll2). Furthermore, in an intermediate LlK-regime (6 to 12 MPa - m1l2) the daJdN-K curves in the aggressive environments exhibited a plateau region with a nearly constant crack propagation rate of about 5 x IO-8mJcycie. At high growth rates these curves approached those measured in vacuum. The results will be discussed on the basis of fracture surface studies (e.g. cleavage-like features found in the aggressive environments in comparison to a ductile fracture mode in vacuum), through thickness crack front profile analysis, and crack closure measurements.
Monday, AM February 10, 1997
Room: Salon 6 Location: Clarion Plaza Hotel
Session Chairs: Gordon Irons, Dept. Matis Sci. and Eng., McMaster University, 1280 Main St West, Hamilton, Ontario L8S 4L7; John Pusateri, Technical Center, Horsehead Resource Dev., 300 Frankfort Road, Monaca, PA 15061
8:30am AN OVERVIEW OF THE INJECTION OF POWDERS AND DUSTS INTO MOLTEN METALS: Gordon A. Irons, Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L7 Canada
l1:00am OXIDATION RESISTANT COATINGS FOR THE O-PHASE: T.J. Jewett, Department of Materials Science and Engineering, SUNY-Stony Brook, Stony Brook, NY 11794-2275
The science and technology of powder injection has evolved from its start in the desulphurization of iron over 20 years ago. The inherent advantages of powder injection are: rapid reaction rate, good mixing, the ability to handle fine materials, flexibility and low capital cost. The fundamental engineering science related to the fluid mechanics of injection, and the associated thermodynamics and kinetics of the processes will be reviewed. Due to the above advantages, this technology is finding application in the recycling of in-plant dusts and other secondary materials, and in the non-ferrous industry. Some of these developments will be highlighted.
Following the discovery of improved oxidation resistance of Ti-AI-based alloys containing second phase precipitates of AI-rich Ti(Cr,AI)2' a similar approach was suggested for the o-phase. A schematic representation of the TiAI-Cr-Nb quaternary system was constructed at 800°C. Subsequently, five alloys, based on the Ti-AI-Cr-Nb quaternary system were prepared in order to probe the phase equilibria between the corresponding Ti,AIX compositions of the Ti-Al-Nb and Ti-AI-Cr ternary systems. The samples were homogenized above the beta-transus then heat treated at 800°e. The resulting phase equilibria and microstructure were evaluated. Additionally, cyclic oxidation studies, at 800 and 900°C were conducted on the heat treated samples to assess their oxidation resistance. Similar behavior for the alloys was observed at 800°C, however, at 900°C the Cr rich alloys experienced significant spalling.
9:15am IMPROVING NON-FERROUS METAL CONTROL THROUGH AUTOMATED POWDER INJECTION: R. J. Liguori, VanDeMark Metals and Alloys, Inc., One North Transit Road, Lockport, NY 14094; D. W. Hoyle, Hickman, Williams, and Company, Technicarb Division, 40 Port Avenue, P.O. Box 872, Monroe, MI 48161 This paper describes results obtained from a new and patented control process designed to automate powdered additions via subsurface injection into a molten metal furnace. The process automatically receives spectrometer data, compares it to targeted values and accordingly calculates, weighs and pneumatically feeds the additives into the metal furnace by subsurface powder injection. Current installation and trials indicate alloy savings and improved metal control. Results of injection with many different powders injected in industrial applications are discussed.
11:20am OXIDATION BEHAVIOR OF TERNARY Ti,AI-Nb ALLOY: R.G. Reddy, Yang Li, Department of Metallurgical and Materials Engineering, University of Alabama, P.O. Box 870202, Tuscaloosa, AL 35487-0202 The oxidation behavior of ternary Ti,AI-Nb alloy has been studied in pure oxygen over the temperature range of 750°C to lloo°C. The experiments were carried out using TGA. The oxidation products were analyzed using Xray diffraction, SEM and EDS. Parabolic rate constants were calculated. An effective activation energy of 268 Kllmol was deduced. The oxidation products formed are non-continuous protective scale on Ti3AI-Nb alloys. The results showed that oxidation products were mainly a mixture of Ti02 (rutile) and AIP3 (alumina). For oxidation scale at llOO°C, it exhibited a layered scale of alternate rutile and alumina. The present results were also compared with that of binary Ti3Al.
9:45am FLASH CONVERTING OF MK (CHALCOCITE) CONCENTRATE AN OVERVIEW: G. J. Morgan}, A. A. Shook2, 1. K. Brimacombe l and G. G. Richards 3. IThe Centre for Metallurgical Process Engineering, The University of British Columbia, Vancouver, BC Canada V6T lZ4; 2New Technology Development, BHP Steel, Wollongong NSW, Australia 2526; 3Cominco Research, Trail, BC Canada VIR 4L8 Flash converting of MK concentrate (Cu 2S) was considered as an option for the process flowsheet modifications at Inco's Copper Cliff operations. The flash converting of chalcocite was known to have problems, such as the generation of large amounts of dust, so a comprehensive research program was undertaken at the Centre for Metallurgical Process Engineering, University of British Columbia to examine the process. This paper is a compilation of the results of the project, some of which have been published elsewhere. The
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The Digital Particle Image Velocimetry (DPIV) technique was used to measure the instantaneous velocity distribution of polyvinyl chloride particles suspended in an upright cylindrical water bath (0.218 m diameter) agitated by injection of air through a top-submerged centric lance. The time-averaged particle velocity and kinetic energy distributions were obtained from the instantaneous velocity data. The effects of gas flowrate (3.3 10.5 - 5 10.5 Nm 3/s), liquid depth (0.164-0.196 m), fractional lance submergence (60-90%), and particle diameter (50-80 /lm) were investigated. The magnitudes of the particle velocities and kinetic energies increased with increasing gas injection rate, and increasing lance submergence. Variation of the liquid depth had minimal influence on the particle behaviour under the conditions studied. Steady state liquid phase flowfield simulations using a commercial Computational Fluid Dynamics package were combined with a dynamic force balance on individual suspended particles to predict the time-averaged particle velocities. Satisfactory agreement was found between the predicted and measured particle velocities, outside the bubble plume region. The particle velocities were integrated with time to predict the trajectories and residence times of particles introduced into the flowfield at different positions. Particles introduced near the plume region were predicted to have much shorter residence times than particles released near the primary recirculation vortex.
mechanism and kinetics of the combustion of individual particles of MK were determined, and dust generation criteria were established. The flash converting flame was mathematically simulated, and dust generation regions within the flame were identified. Pilot plant trials were conducted, confirming that the dust generation rate could be affected (reduced) by altering the burner configuration, and thus the flame characteristics.
10:15 am BREAK
10:30 am DENSE PHASE PNEUMATIC INJECTION FOR FINE MATERIALS: Robert G. Goffin, Paul Wurth Ltd., 3310 South Service Road, Burlington, Ontario L7N 3M6, Canada Pneumatic injection of various fine materials such as metallic concentrates, fluxes and fuels into pyrometallurgical vessels has become an important practice. Injection is an evolutionary step from pneumatic conveying - the receiving vessel is now a metallurgical process unit instead of a storage unit. Proper injection system design must integrate conveying, injection, metallurgical process and physical constraints, as well as the limitations of specific material characteristics. Dilute phase pneumatic conveying requires large quantities of conveying gas in order to move material. Load ratios in the order of 10:1 (weight of solid gas:weight of conveying gas) are typical. In order to eliminate the problems associated with dilute phase (including extreme pipeline and component abrasion, excess conveying gas, etc.) steady development has been made in the application of dense phase (load ratios substantially higher than 25: 1) pneumatic conveying and injection technology. Load ratio selection is dependent upon many factors including specific material characteristics and system requirements. This paper will outline the advantages of dense phase pneumatic injection technology and will present successful and reliable pyrometallurgical applications.
INTERNATIONAL SYMPOSIUM ON RHENIUM AND RHENIUM ALLOYS I: Plenary Session: Welcome and Keynote Addresses Sponsored by: SMO Refractory Metals Committee and MOMO Powder Materials Committee Program Organizer: Dr. Boris D. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036
11:00 am COAL PARTICLE INJECTION AND DEVOLATILISATION UNDER RAPID HEATING CONDITIONS: J. Beeson', V. SahajwaUa 1, G. Belton2, 'School of Materials Science and Engineering, University of New South Wales, Sydney, Australia; 2BHP Research, Newcastle Laboratories, Newcastle, Australia
Monday, AM February 10,1997
New developments in the metallurgical industry, such as iron bath smelting processes and pulverised coal injection into blast furnaces involve coal injection and devolatilisation under rapid heating conditions. These new technologies employ coal particle heating rates around 104 °C/sec. Under these conditions the volatile matter released cannot be established from standard analysis and this can have a significant effect on the process. For example the volatile matter released, which is in excess of that from standard analysis, may lead to excess gas in the top space of a bath smelter. When the efficiency of the reactor relies on a fine balance of post combustion reactions, the increase in release of volatile matter may lead to a decrease in the efficiency of the reactor. In pulverised coal injection to blast furnaces, the amount of volatiles released, and the time taken for this release, influences the combustion behaviour of the coal and char. In this study, the injection and devolatilisation of three size fractions of various coals into a drop tube furnace was investigated. The surface mean diameters of each size fraction were 92 /lm, 121 /lm, and 172/lm. Four coal types were investigated, sub-bituminous, bituminous, semi-anthracite and an anthracite. These were injected at temperatures of lOOO°C, 1200°C, and 1400°C. The ash content and volatile matter remaining in each of the chars was determined in order to calculate the volatile yield using the ash tracer method and the rate of volatiles release. An apparent activation energy for the release of volatiles was calculated. The results show a strong dependence of the activation energy for volatile release on coal crystallite size, as determined by X-ray diffraction. Hence the crystallite size could be an important characteristic of coals that is significant for coal selection for the new technologies in the metallurgical industry.
8:30am WELCOME AND OPENING REMARKS: Prof. Dr. Maria A. Tylkina, Baikov Institute of Metallurgy, Russian Academy of Sciences, Moscow, Russia
Room 232C Location: Orlando Convention Center
Session Chairperson: Dr. Boris D. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036
Additional speakers names to be announced later.
9:10am RHENIUM SEVENTY YEARS OLD: Fathi Habashi, Department of Mining and Metallurgy, Laval University, Quebec City, Canada, GIK 7P4 Rhenium was discovered in Berlin in 1925 by Ida Tacke, Walter Noddack, and Otto Berg. It was isolated in milligram amounts by Ida Noddack (born Tacke) in 1926. The first 100 kg of the metal were produced seventy years ago from carbonaceous copper shist ore (Kupferschiefer) from the Mansfeld District in Germany. The process was so complicated and the price so high that production was discontinued until early 1950 when tungsten-rhenium and molybdenum-rhenium alloys were prepared. These alloys found important applications in industry that resulted in a great demand for the metal produced from the molybdenite fraction of porphyry copper ores. The early story of rhenium will be told from personal interviews with Ida Noddack (1896-1978).
9:35am RHENIUM BACKGROUND AND MARKETS: Tom A. Millensifer, Powmet, Inc., 2625 Sewell St., P.O. Box 5086, Rockford, IL 61125
11:30 am PREDICTION AND MEASUREMENT OF THE TIME-AVERAGED VELOCITIES OF INERT PARTICLES SUSPENDED IN GASSTIRRED LIQUID BATHS: H. Pham, D.E. Langberg, M. Nilmani, G.K. Williams Cooperative Research Centre for Extractive Metallurgy, University of Melbourne, Parkville, Victoria 3052 Australia
Rhenium existed as a curiosity with little practical application for it's first nearly 50 years. Use was limited to a few specialty and high temperature alloy applications. In the early 1960's interest in the potential for catalytic use of Rhenium developed and by the early 1970's significant catalytic use had begun. Greater production was required. Leading development of production technology in the Western World was Kennecott Copper Corporation 20
which originated industrial scale recovery techniques. In 1963 Shattuck Chemical in Denver, Colorado installed recovery facilities based on Kennecott's technology. The facilities were followed by recovery at Starck in Germany and Molycorp in Chili. In 1980 Duval Corporation, a subsidiary of Pennzoil, installed recovery facilities and began recovery in mid 1981. Today recovery from Molybdenite exists in the Western World in only three places with one other available but not operating at this time. Recovery from Copper is reported in Japan and Kazakhstan, and also from Copper Smelting in Jianxi Province China as well as at several Molybdenum Roaters in Russian and other areas of the CIS.
LIGHT WEIGHT ALLOYS FOR AEROSPACE APPLICATION IV: Session I: AI Alloys Sponsored by: SMD Non-Ferrous Metals Committee Program Organizer: Eui W. Lee, W.E. Frazier, Code 4342, Naval Air Warfare Center, Patuxent River, MD 20670; K. Jata, WUMLLM, WPAFB, OH 45433; N.J. Kim, Center for Advanced Aerospace Materials, POSTECH, Pohang, 790-784, Korea Monday, AM February 10, 1997
10:00 am INVITED MILL PRODUCTS AND FABRICATED COMPONENTS IN RHENIUM METAL AND RHENIUM RICH ALLOYS: Jan-c. Carlen, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036
Room: 330A Location: Orlando Convention Center
Session Chairperson: Eui W. Lee, Code 4342, Naval Air Warfare Center, Patuxent River, MD 20670
For a metal which is produced in quantities around 50 tons per year world-wide, it should be difficult to talk about bulk usage. However, about 90% of the rhenium produced is used for catalysts and as an alloying element in nickel-cobalt-base super-alloys. This paper deals with mill products based on powder metallurgy production of rhenium and molybdenum-rhenium and tungsten-rhenium alloys. Rhenium is a metal which work-hardens very quickly in cold-working and which cannot be hot-worked because of hot-shortness and poor oxidation resistance. This makes plastic forming of rhenium a very delicate process. Rhenium cannot be machined using conventional methods but other means of making complicated shapes have been developed. Alloys between rhenium and tungsten and rhenium and molybdenum have their best properties at or close to the solubility limit for rhenium in each metal, which may create problems with formation of a brittle, intermetallic phase (sigma phase). However, these alloys are much easier to form using plastic hot and cold forming. They can also be formed into various shapes using regular machining methods. Means of avoiding or eliminating the negative effect of sigma phase are briefly discussed. Finally the industrial usage of mill products and as-sintered products of rhenium and its alloys with molybdenum and tungsten is discussed. These materials have found many challenging applications in space, defense, electronic, energy, scientific instruments and other high-tech industries.
8:30am ELECTRODE POTENTIAL DEPENDENCE OF ENVIRONMENTAL CRACKING IN HIGH STRENGTH 7XXX ALUMINUM ALLOYS: L.M. Young, R.P. Gangloff, Department of Materials Science and Engineering University of Virginia, Charlottesville, VA 22903 This research aims to determine the effect of electrode potential on the kinetics of environmental crack growth in precipitation hardened 7XXX aluminum alloys. High resolution compliance and electric potential measurements of daJdt provide part of the foundation to understand the mechanisms for the aging-microstructure dependence of short-transverse cracking. Measured Stage II growth rates in AA7075-T651, immersed in aqueous chloride, are slow and depend on electrode potential and inhibitor addition. For cracking in a molybdate-chloride solution, daJdt rises from 10-7 mmls at -900 mV seE (near-open circuit) to 10.5 mmls at -750 mV SCE ' but is constant or declines with more noble applied polarization. The crack path is along or near high-angle boundaries, but the crystallographic and microstructure details are undefined. These results are consistent with literature findings for AA7075-T6 in KI solution. The potential for the maximum in daJdt is more noble for the iodide compared to the molybdate, and is most active for cracking in bare chloride solution. This transition potential is governed by the onset of substantial localized crack tip dissolution which causes an IR difference that shields the crack from changes in anodic polarization. The importance of this potential dependence is illustrated by results for AA 7050-T6 in molybdate. Crack growth is faster compared to the AA7075 case if both alloys are at their open circuit potential. Crack growth in AA7050 is slower than that in AA7075 if the comparison is made at a fixed electrode potential.
10:25 am THE PERSPECTIVES FOR DEVELOPMENT OF RHENIUM PRODUCTION IN RUSSIA: Albert D. Besser, A.V. Peredereev, State Research Center of Russia, 13 Acad. Korolyov Street, 129515 Moscow, Russia The rhenium's production base in Russia is based on the processing of the concentrates of the effective tungsten-molybdenum mines (Zhirkenskyi, Sorskyi, Tyrnyauzskyi) and opening up of the new ones (Bugdainskyi, Aksukskyi and others), as well as on the recovery of rhenium from the gases during the burning of the shales. The substantial content of rhenium and of some other rare components in the volcanic slags has been revealed. The extraction technology has been developed. The processing technology of the secondary rhenium-containing raw materials and of the intermediate products has been developed and realized in the industrial conditions. The technologies concerning the extraction of more than 90% of rhenium from the molybdenite concentrates following the pyro- and hydrometallurgical processes have been developed and are ready now for the industrial realization.
8:55 am GRAIN SIZE AND TEMPERATURE DEPENDENCE OF INELASTIC DEFORMATION IN 5083 AI ALLOY: Yong Nam Kwon, Young Won Chang, Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790-784, Korea The inelastic deformation behavior of 5083 A 1 alloy has been studied to clarify the effects of grain size and temperature by conducting a series of load relaxation tests. The experimental results were then analyzed based on the recently proposed internal variable theory of inelastic deformation. The inelastic deformation of fine grained 5083 Al alloy at high temperatures is confirmed to consist of grain boundary sliding and accommodating grain matrix deformation caused by dislocation glide processes. A Hall-Petch type relation is found to exist between the grain size and an internal strength variable, instead of the generally used flow stress. 9:20am ON THE WARPAGE OF 7050 ALUMINUM PLATES: M. L. Smith', J. Foyos', E. W. Lee2, C. Ho and O. S. Es-Said, IMechanical Engineering Department, Loyola Marymount University, Los Angeles, CA 90045; 2Naval Air Warfare Center, Code 434200A, NAWCAD PAX, Patauxent River, MD 20670; 3Mechanical Engineering Department, Howard University, Washington, DC Investigators need a consistent and accurate method to measure and report sample warpage to assess material distortion during heat treatment. Consistent and accurate sample surface profile measurement can commence only
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after the sample is precisely positioned. This paper proposes using a positioning fixture which exactly constrains a sample's six degrees of freedom. Mounted in this fixture, standard dimensional inspection tools such as level gauges and dial indicator are then used to measure profiles along predetermined sample surface zones. Normalizing those measurements with respect to fixture constraint points and then plotting them on a graph allow precise warpage measurement and easy distortion visualization. In this study samples of 7050 plates were machined. The samples were of I " 1.5", and 4" thickness and the cross-sectional shapes were U-channels and I beams. Samples were solution treated and one group was quenched in water and the second group in a polyalkylene-glycol solution. The effect of the sample's thickness and shape as well as the quenching medium on the warpage behavior will be discussed.
Constant heating rate thermal desorption scans were performed to identify hydrogen trap sites and quantify trap binding energies. In all desorption experiments, a quadrupole mass spectrometer was used to distinguish the desorption of hydrogen from that of other atomic or molecular species. Results from isothermal experiments show that bulk diffusion of hydrogen in the overaged alloy is appreciably slower than in the peak aged temper or in pure aluminum. Constant heating rate experiments reveal multiple trapping sites in both the alloy and in pure aluminum. The effects of the number and binding energy of trap sites on the diffusivity of hydrogen is quantified and the implications of these results on the hydrogen environment assisted cracking of precipitation hardened AI-Zn-Mg alloys are discussed. 11:00 am EVOLUTION OF MICROSTRUCTURE, FRACTURE TOUGHNESS AND FATIGUE RESISTANCE DURING PROCESSING OF 7X50 ALUMINU1\I ALLOYS: F.D.S. Marquis, Department of Metallurgical Engineering, College of Chemical, Physical, and Materials Science & Engineering, South Dakota School of Mines and Technology, Rapid City, SD 5770 I
9:45am DYNAMIC DEFORMATION CHARACTERISTICS OF AI-Li ALLOYS: Chang Gil Lee, Ki Jong Kim, and Sunghak Lee, Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
The evolution of microstructures was studied in 7X50 aluminum alloys, as a function of the manufacturing variables, during laboratory and industrial processing conditions. The fracture toughness, fatigue crack initiation and fatigue crack propagation of typical microstructures was measured. Low fracture toughness values and low resistance to fatigue crack growth were observed as a result of a high degree of recrystallization and a large volume fraction of both particles and hydrogen porosity. The resistance to fatigue crack propagation was higher in microstructures consisting of deformed grains with significant substructure. The morphology of various types of particles, volume fraction of the recrystallized microstructures, the grain and subgrain morphologies were observed to influence considerably the fatigue resistance. These microstructural parameters could be controlled effectively by the amount of total strain and the strain of the final pass, and the deformation temperatures during controlled rolling and subsequent double aging during final thermomechanical processing. Relationships between microstructure/fracture toughness/fatigue resistance will be discussed.
This paper presents a correlation study between microstructure and dynamic deformation behavior of AI-Li alloys which have great potential for structural armor materials. The selected materials were a 2090 AI-Li alloy, a Weldalite 049 alloy, and a 7039 Al alloy, to allow a comparative study of different strengths and microstructures. These alloys were deformed at a very high strain rate by ballistic impact. The amount and the distribution of adiabatic shear bands were examined after the ballistic impact testing, and the dynamic shear stress-strain curves were obtained from the dynamic torsional Kolsky bar (strain rate=i-103/sec) test in order to evaluate the possibility of forming adiabatic shear bands. In the vicinity of the perforated region, adiabatic shear bands were hardly observed in the 2090 and the Weldalite alloys, whereas they easily formed in the 7039 alloy. The overall observed phenomenology was interpreted using the dynamic shear stress- strain curves, together with the strength level and microstructure. In the curves, the maximum shear stress and the shear strain at the maximum stress point were of primary importance in analyzing the adiabatic shear banding behavior, suggesting that the torsional Kolsky bar test is a good tool for evaluating the ballistic performance AI-Li alloys.
11:25 am EFFECT OF PRE-AGE STRETCHING ON MECHANICAL AND HIGH CYCLE FATIGUE PROPERTIES OF THE 2024-T851 ALUMINUM ALLOY FOR AIRCRAFT: Han-Chang Shih, New-Jin Ho*, Steel and Aluminum Research & Development Dept. *Institute of Materials Science and Engineering, National Sun Yat-Sen University
10:10 am COMPETITION BETWEEN METASTABLE AND STABLE PHASES DURING SOLIDIFICATION OF AI-Fe-V-Si ALLOYS: Hyang Jin Koh, Woo Jin Park*, Sangho Ahn* and Nack J. Kim, Center for Advanced Aerospace Materials, Pohang University of Science and Technology, San 31, Hyojadong, Pohang 790-784 Korea, and * Research Institute of Industrial Science and Technology, San 32, Hyojadong, Pohang 790-390, Korea
Cold-stretching prior to artificial aging could increase the yield strength of the 3024 aluminum alloy due to the enhanced nucleation of the S' precipitates. However, the S' phase itself became weakened in resistance to dislocating due to thinning and was thus more easily sheared off. Consequently, the Orowan's strengthening mechanism could only occur in specimens undergoing long-time overaging. The strength of this alloy were thus a compromise of dislocation-induced hardening and precipitate-induced softening. Also, its high cycle fatigue performance became more and more deteriorated with increasing pre-aging strain on the basis of the similar reason.
AI-Fe-V -Si alloys have been produced by strip casting and spray casting. These processes offer relatively fast solidification rates and can produce near net shape products such as thin gauge strips or billets with the fine microstructure free from segregation. It has been shown that the microstructure of the alloys consists of various phases; bcc phase, microquasicrystalline phase, icosahedral phase, and the newly found hexagonal phase. All the phases are structurally related and have close orientation relationships among them. The volume fraction and distribution of these phases depend on the solidification rate and the degree of undercooling. The degree of recalescence occurring during solidification also affects the final microstructure, in that the less thermally stable phases transform to the stable phase. 10:35 am THE EFFECTS OF AGING ON THE DIFFUSION AND TRAPPING OF HYDROGEN IN AN AI-6.2Zn-2.3Mg-2.3Cu ALLOY: George A. Young Jr., John R. Scully, Center for Electrochemical Science & Engineering, Materials Science & Engineering, The University of Virginia, Charlottesville, VA 22903 Thermal desorption spectroscopy was used to investigate the diffusion and trapping of hydrogen in a AI-6.2Zn-2.3Mg-2.3Cu alloy and in pure aluminum. Both the peak aged (T6) and overaged (T74) tempers were investigated for the alloy. Hydrogen was uniformly charged into rod-shaped samples via exposure to water vapor saturated air. Isothermal desorption scans were utilized to determine the apparent activation energy for hydrogen diffusion.
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10:20 am THE EFFECT OF CAST SIZE ON HOT CORROSION RESISTANCE OF SINGLE CRYSTAL NICKEL BASED SUPERALLOY CMSX-4: Ming Li, V. Desai, Mechanical Materials and Aerospace Engineering Department, University of Central Florida, Orlando, FL 32816; N.S. Cheruvu, Southwest Research Institute, 6220 Culebra Road, San Antonio TX 78228
MATERIALS, COATINGS AND PROCESSES FOR IMPROVED RELIABILITY OF HIGH TEMPERATURE COMPONENTS I: Materials and Process I Sponsored by: SMD High Temperature Materials Committee Program Organizers: Dr. N. S. Cheruvu, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX, 78228; Dr. K. Dannemann, GE Power Generation Engineering, One River Road, Schenectady, NY 12345 Monday, AM February 10, 1997
Advanced single crystal (SC) nickel based superalloys have been available in small cast size for aero engine applications for a long time. Where as the SC techniques are not yet widely used in the land based engine components because of their much larger size which makes casting and the subsequent heat treatment more difficult. The difference in defects, such as microporosity, segregation, y/yl eutectic, and dendritic structure, derived from casting size differences will affect the heat treatment process and the subsequent service properties, including hot corrosion/oxidation behavior. Hot corrosion tests were carried out at 900, 950, and 1000°C on specimens coated with Na,SO. in air. Three different kinds of specimens; as-cast and heat treated CMSX-4 from small and large blades, and IN738, were used to study the effects of cast defects and heat treatment on hot corrosion behavior and to compare the hot corrosion resistance of the single crystal superalloy with a typical land based turbine material. The corrosion product morphology, microstructure and composition were investigated using metallography and SEMIEDS. It is concluded that although the hot corrosion resistance of this single crystal material is not as good as that of IN738, proper heat treatment can double its hot corrosion resistance.
Room: Salon 3 Location: Clarion Plaza Hotel
Session Chairman.' Dr. N. S. Cheruvu, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228
8:30 am INVITED STATUS, ISSUES AND CHALLENGES OF MATERIALS FOR ADVANCED LAND BASED GAS TURBINES: B.B. Seth, Westinghouse Electric Corporation, Orlando, FL 32826-2399 Abstract not available. 9:20am DEVELOPMENT OF DIRECTIONALLY SOLIDIFIED BLADES AND VANES FOR LAND BASE TURBINE: Hisataka Kawail , Kohji Takahashi', Ikuo Okada', Taiji Trigoe', Akira Mitsuhashi2; lMitsubishi Heavy Industries, Ltd, Takasago Research & Development Center, 2-1-1 Shinhama Arai-Cho, Takasago, Hygo Pref. 676 JAPAN; 2Mitsubishi Materials Corporation, 1-297 Kitabukuro-Cho Omiya, Saitama 330, Japan
10:40 am RELIABILITY OF A SINGLE CRYSTAL NiAl ALLOY FOR GAS TURBINE APPLICATIONS: R. D. Noebe, J. Salem, 1. Manderscheid, NASA Lewis Research Center, M.S. 24-1, Cleveland, OH 44135; R. Darolia, General Electric Aircraft Engine Co., Cincinnati, OH 45215 Due to numerous property advantages, NiAI single crystal alloys are being investigated as a replacement for Ni-based single crystal superalloys in high pressure turbine engine sections, however, the current drawback is their lack of ductility. Consequently, a significant effort is being made to develop testing and design methodologies that will account for this lack of ductility. The present approach is to modify existing test methods and brittle design methodologies, such as those in the Ceramic Analysis and Reliability Evaluation of Structures (CARES) code, and to experimentally verify the results. To this end, the statistical nature and source of fracture in a high-strength, single crystal NiAI alloy has been studied via flexural testing of 3- and 4-point bend specimens of various crystallographic orientations. Flexural strength results indicate a wide dispersion in strength that can be characterized via normal or Weibull statistics. While the fracture strength was function of orientation, the Weibull modulus was not. Failure origins were determined for most of the specimens tested. In all cases, failure occurred from singular carbide particles or machining damage. It was also determined that the Weibull scaling law applies to uniaxial cases for effective surface area changes of 300% or less.
Directionally solidified blades and vanes, so-called DS blades and vanes, have already been used in jet engines, but seldom in land-base gas turbines, because there are large differences in the size of hot parts, fuel and so on between jet engines and land-base gas turbines. It is necessary to take these differences into account when developing DS blades and vanes for land-base gas turbines. Mitsubishi Heavy Industries, Ltd. started to develop DS blades some years ago. First, material properties, such as, tensile strength, creep rupture, fatigue, other physical properties, etc, were investigated. Then, the optimization of casting conditions for large size blades (501FGff 1st blade) was conducted. Finally, actual DS blades were cast and it was confirmed their material properties were excellent. Also their machinability and coating were evaluated and good results were obtained. As a result, DS blades were installed in an actual gas turbine (MF1l1Gff) in January 1994 which have been in operation since then. 9:40am MICROSTRUCTURAL STABILITY OF ADVANCED SINGLE CRYSTAL SUPERALLOYS: WS. Walston, GE Aircraft Engines, 1 Neumann Way, M85, Cincinnati, OH 45215
11:00 am EFFECT OF SOLUTION HEAT TREATMENT ON DS TRANSVERSE STRENGTH: H. Tamaki, A. Yoshinari, A. Okayama, N. Watanabe, M. Kobayashi, Hitachi Research Laboratory, Hitachi, Ltd., Hitachi, Ibaraki, Japan
Microstructural stability is a key parameter in the development and application of single crystal superalloys. The formation of topologically close packed (TCP) phases occurs to some degree in most single crystal superalloys. The effect of these phases on properties will be discussed. In addition, the effects of time and temperature on the formation of TCP phases will be shown for a recent single crystal superalloy, Rene N6. Another form of microstructural instability has recently been observed in high refractory content single crystal superalloys. This instability, termed SRZ, is a cellular phase transformation that can occur either beneath coatings or in the alloy substrate. The occurrence and effects of this instability in various alloys will be discussed. The third form of microstructural instability observed in several single crystal superalloys is the conversion of the y matrix with y' precipitates to a microstructure with a continuous y phase. Several examples of this behavior will be shown. The relationship between this form of instability, rafting and creep rupture properties will also be discussed.
It is well known that creep-rupture strength of nickel-base superalloys strongly depends on the conditions of solution heat treatment. Jackson et al. I showed that creep-rupture life of MAR M 200 Hf DS in longitudinal direction increased with increasing volume fraction of fine y' upon solution heat treatment. On the other hand, Cetel and Duhl 2 showed that creep ductility of PWA1426 DS in transverse direction decreased with increasing volume fraction of fine y'. In this study, in order to investigate the effect of solution heat treatment on DS transverse strength, CMI86LC DS which is usually used without solution heat treatment was solution heat treated at 1548K for different time periods. Results are summarized as follows. (I) Creep-rupture strength of CMI86LC DS in longitudinal direction increased by solution heat treatment. (2) Creep-rupture strength of CM186LC DS in transverse direction decreased by solution heat treatment. (3) Boron at grain boundaries diffused into grains by solution heat treatment. This phenomenon possibly caused the decrease of creep-rupture strength of CM186LC DS in transverse direction.
10:00 am BREAK
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11:20 am ALLOY 603GT: ANEW COBALT FREE ALLOY FOR GAS TURBINE COMPONENTS: D. C. Agarwal, 11210 Steeplecrest Dr. # 120, Houston, TX 77065-4939; U. Brill, Krupp-VDM GmbH, Werdohl, Germany
9:00 am INVITED SOLDER ALLOY DEVELOPMENT: Yun Zhu, Delco Electronics Corporation, 2705 S. Goyer Road, M/S D-16, Kokomo, IN 46904-9005 In this presentation, the process of alloy development and down selection is summarized. An initial list of more than 70 alloys was constructed, including binary, ternary, quaternary, and quinary alloys. he first selection process was applied based on the toxicology, economic, and availability criteria. Then a downselection criteria matrix, including melting temperatures, wetting behavior, and thermo-mechanical fatigue, was generated for a quantitative comparison of alloys with respect to three baseline alloys: eutectic Sn-Pb, Sn-Bi, and Sn-Ag solders. Physical testing was performed to provide the data for downselection. Extensive phase diagrams from literature and thermodynamic calculation were used to predict the melting temperature range, and compare with experimental results. A comprehensive literature search was conducted to identify publications of the past 25 years.
Modern gas turbine components must possess unique combination of various high temperature strength and corrosion resistance properties for providing increased efficiency and reliability of operation. Some of these properties, which a material must have are good isothermal and cyclic oxidation resistance, good carburization resistance, good thermal stability, good stress rupture and fatigue strength and most importantly, good fabric ability and weldability. Alloy 603GT is a new cobalt free nickel base alloy especially developed for modern gas turbine components. Its basic composition of high chromium, high aluminum, high carbon (25 Cr, 2.6 AI, 0.3 C, 0.1 Y, 9 Fe, Ni balance) and micro alloying with titanium and zirconium, gives this alloy a unique combination of excellent high temperature strength and superior oxidation resistance, carburization resistance, good thermal stability, grain growth resistance and spallation resistance. It's development, properties and cost effectiveness are discussed.
9:30 am INVITED ECONOMICS, AVAILABILITY, AND TOXICOLOGY: Charles DeSantis, Hamilton Standard Division of United Technologies Corporation, MIS 3-2-F2, One Hamilton Road, Windsor Locks, CT06096-101O; Joe Fegley, Texas Instruments, 2501 W. University, Box 801/ MIS 8013,McKinney, TX 75070; Tsung-Yu Pan, Ford Motor Company, P. O. Box 2053, SRL Building, MID 3135, Dearborn, MI 48121-2053
11:40 am MECHANICAL PROPERTY COMPARISON OF SELECTED NICKEL BASE SUPERALLOYS FOR LAND BASED GAS TURBINE APPLICATIONS: Colin Thomas, Howmet Corporation, Whitehall, MI 49445
Based on data from the U.S. Department of Interior, an economics/availability study was completed which estimates the impacts on supply and cost to the electronics industry if it were to replace tin-lead solder with a lead-free solder alloy. Considerations in this study included the availability of the replacement materials, world mine production and consumption, world reserves and reserve bases, present world mine production capacity, principal reserve locations, average annual price and price history. Seven alloying elements were investigated. They were antimony, bismuth, cadmium, copper, indium, silver, tin, and zinc. Limits placed on the estimated alloy cost, ore reserve consumption rate, and required mine or refining capacity permitted rank ordering of potential alloys. An extensive literature search on the toxicity of common solder alloying elements was also conducted. Available data on the disposition, toxicity, and exposure limits of these solder alloying elements were analyzed in order to rank their use risk. The process used to evaluate the economics, availability, and toxicity of lead free solders, as well as the findings of the study will be discussed.
Abstract not available.
MATERIALS &TECHNOLOGIES FOR MICROELECTRONICS I Sponsored by: EMPMD Electronic Packaging and Interconnection Materials Committee Program Organizers: Michael R. Nolis, Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015; Dr. Sung K. Kang, IBM, TJ Watson Research Center, Yorktown Heights, NY 10598 Monday, AM February 10, 1997
Room: 314B Location: Orlando Convention Center
Session Chairperson: TBA
10:00 am BREAK 8:30 am INVITED INTRODUCTION OF THE NCMS LEAD-FREE SOLDER DEVELOPMENT PROJECT: Jerald Rosser, Hughes Aircraft Company, P.O.Box 11337, Building 801/E-24, Tucson, AZ 85734-1337
10:20 am INVITED MANUFACTURING WITH LEAD-FREE SOLDERS: John Greaves, Electronics Manufacturing Productivity Facility, 714 N. Senate Ave., Indianapolis, IN 46202-3112
Since 1990, proposed legislation and consumption taxes on the use of lead have concerned the electronics industry in this country. Although the consumption of lead for electronic interconnections (via solder) is relatively low in comparison to batteries, the possibility of restricting lead usage for solder alloys would have a dramatic effect on the electronics industry. This concern lead the National Center for Manufacturing Sciences (NCMS), a not-for-profit cooperative research consortium of more than 215 U.S. North American manufacturers, to establish a multi-year Lead Free Solder Project, involving participants from industry, (GM DELCO, AT&TlLucent Technologies, United TechnologiesiHamilton Standard, GM-Hughes, Rockwell International, Ford, Texas Instruments), academia (Rensselaer Polytechnic Institute), and national laboratories (Sandia, NIST, and Electronic Manufacturing Productivity Facility). The objective of the program was to identify lead free solder alternative replacement(s) for lead bearing solders in the electronics industries. The alloy(s) must meet the interconnect performance requirements at operating environments ranging from -40 to + l25°e. Over the past three years, numerous lead free alloy solders have been thoroughly evaluated. The project participants will be presenting the results of this four year NCMS evaluation of the material properties, economic impact, toxicological properties, manufacturability, modeling and reliability predictions.
Successful introduction of lead-free solders into the manufacturing process requires subtle changes in process parameters. Changes in density, melting temperature, wetting and spreading behavior, all affect the parameters necessary for optimum manufacturing and reliability. This currently results in a need to change print speeds, squeegee pressures, and stencil thicknesses. Component placement is relatively unchanged. The largest changes in manufacturing with lead-free solders are those in the reflow process. Manufacturing lead-free solders with RMA fluxes requires modifying reflow profiles to insure that the flux is active when the solder reaches the melting temperature. Manufacturing with fluxes designed for lead-free solders simply requires setting the conveyor speeds and zone temperatures to achieve the suggested profile. No substantial difference has been noticed in the cleaning of leadfree alloys and the lead-free alloys evaluated are compatible with no-clean processes as well. Wave soldering of lead-free solders using RMA fluxes can present some difficulties if the process is not well controlled. While many lead-free solders can be used in wave-soldering with no changes to the profile or pot temperature, using fluxes and profiles designed for lead-free solders can increase yields and simplify the wave-soldering process.
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10:50 am INVITED Pb-FREE SOLDER RELIABILITY COMPARISON: Gordon Whitten, Delco Electronics Corporation, 700 East Firmin St., M/S TlOO-34, Kokomo, IN 46904-9005 The reliability of several Lead-free solder alloys are compared. Thermal cycle testing was performed using two different profiles: 0 to + 100°C, to simulate telecommunications and office environments; and -55 to +125°C, to simulate automotive and military environments. The National Center for Manufacturing Sciences (NCMS) Surface Mount Reliability Test Vehicle(SMRTV) was used to test more than 2000 jointslboard with more than 10,000 joints per alloy for each temperature cycle. Five Pb-free alloys are compared to 3 baseline alloys, SnPb Eutectic, SnAg Eutectic, and SnBi Eutectic. Three parameter Wiebull analysis is used to determine failure free time, Wiebull life, and Wiebull shape parameter.
11:20 am INVITED RELIABILITY MODELING FOR LEAD-FREE MICROELECTRONICS: ScottA. Schroeder, Rockwell International Science Center, 1049 Camino Dos Rios, Thousand Oaks, CA 91360 The NCMS Lead-Free Project Modeling Task Group was formed to determine the capability of existing models developed by the consortium members to predict low cycle fatigue life for specified test vehicles using downselected lead-free solder alloys. A quantitative summary and objective analysis of predictions and modeling capability for down-selected alloys are generated. Life prediction results are correlated with reliability test vehicle data using a -55 to 125 C thermal cycle. The final project goal is a design guide for predicting joint fatigue life for lead-free leadless capacitors and resisters, 44 LCCC, 32 TSOP, and 132 PQFP components. Solder down-selection guidance is provided through recommendations of mechanical tests, test priority, and evaluation of hysteresis loop, thermo-mechanical fatigue, creep, and tensile property data. Alloy phase diagram modeling information provides manufacturing down-selection criteria. Additional support is provided through stress analysis of manufacturing test vehicles.
MECHANICAL BEHAVIOR TMS General Abstract Session Monday, AM February 10, 1997
Room: 230D Location: Orlando Convention Center
Session Chairperson: George T. Gray, III, Los Alamos National Laboratory, Los Alamos, NM 87545
8:30am INFLUENCE OF TEXTURE AND STRESS STATE ON THE CONSTITUTIVE RESPONSE OF AN AUTOMOTIVE STEEL: Carl M. Cady*, Shuh-Rong Chen, George T. Gray III, Los Alamos National Laboratory (LANL), MST-5 MS-G755, Los Alamos, NM 87545; John F. Bingert, David A. Korzekwa, LANL, MST-6 MS-G770, Los Alamos NM 87545 The relationships between the stress state, texture, revalue (Lankford parameter), and yield surface for a DQSK mild sheet steel have been analyzed. The strain rate and temperature sensitivity of the flow stress and the insensitivity of the strain hardening rate indicate that thermal activation over a Peierls barrier is the rate controlling mechanism for deformation in DQSK. The stress/ strain response for DQSK steel is shown to be strongly influenced by strain rate and temperature which is consistent with this controlling mechanism. A calculated yield surface, using the Quadratic Hill criterion, is shown to produce an accurate correlation with the experimental results. Comparisons of the stress/strain response with the calculated yield surface and texture measurements will be shown to correlate with the relationships between the inplane and through thickness deformation.
Ii.,
8:50am THE MICROTEXTURE OF FRACTURE IN LITHIUM-CONTAINING ALUMINUM ALLOYS: R. Crooks, Analytical Services and Materials, Inc., NASA Langley Research Center, M/S 188A, Hampton, VA 23681-000 I; P.N. Kalu, Department of Mechanical Engineering, FAMlFSU, Tallahassee, FL; A.P. Reynolds, Department of Mechanical Engineering, University of South Carolina, Columbia, SC An Electron Back-Scattered Pattern (EBSP) system was used on a scanning electron microscope (SEM) to examine the crystallographic features of intergranular fracture in several lithium-containing aluminum alloys. The alloys examined have thin, flat grains with a "pancake" morphology, which tend to be highly elongated in the rolling direction. Metallographically prepared and electropolished samples of longitudinal sections were examined in the SEM where absorbed current images and diffraction data were collected throughthickness, with patterns indexed to the images. Delamination fracture was then induced in the samples by torsional loading, which often produced several cracks, and samples were returned to the SEM chamber to determine the crack locations relative to the previously acquired data. The results indicate that delamination occurs between grains near the Sand R texture component orientations, which are known to form during deformation processing and as a result of grain boundary initiated recrystallization, respectively.
9:10am ELEVATED TEMPERATURE COMPRESSIVE SLOW STRAIN RATE PROPERTIES OF SEVERAL DIRECTIONALLY SOLIDIFIED NIAL(NB, MO) ALLOYS: J. Daniel Whittenberger, Ronald D. Noebe, NASALewis Research Center, Cleveland, OH 44135; Steven M. Joslin, B.F. Oliver, The University of Tennessee, Knoxville, TN 37996-2200 Three NiAI-based alloys containing 3Nb-IOMo, 5Nb-IOMo or 13.6Nb-18Mo (at. %) were directionally solidified (ds'ed) to develop interpenetrating networks of B2 crystal structure NiAI Laves NiAINb and bcc metallic Mo. It was hoped that the Mo would improve the fracture toughness, while the Laves phase would promote good creep resistance. Examination of the alloys indicated that the as-grown structure consisted of essentially unalloyed NAL NiAINb alloyed with -8.5 Mo, and a Mo solid solution containing 27Nb7Ni-7 AI. Compressive properties were measured between 1200 to 1400 K in air with strain rates ranging from -10.4 to _1O. 8s· 1• The flow strengths of the two alloys with IOMo were nearly identical and much weaker than those for NAI-13.6Nb-18Mo. Comparison the properties of this latter alloy with other ds'ed NAI-based eutectics revealed that it was the strongest material under lower temperature/fast deformation conditions, but this advantage was lost at higher temperatures and/or slower strain rates.
9:30am DEFORMATION AND FAILURE MECHANISMS IN MATERIALS THAT DEFORM BY TWINNING AND MARTENSITIC TRANSFORMATION: Surya R. Kalidindi, R.D. Doherty, Department of Materials Engineering Drexel University, Philadelphia, PA 19104 MP35N (35% Co, 35% Ni, 10% Mo, 20% Cr) exhibits an remarkable combination of ultrahigh strength, high ductility, high fracture toughness, high corrosion resistance, and it retains its room temperature strength upto about 600°C. This alloy hardens from 390 MPa (in the annealed state) to 1385 MPa after being 53% cold drawn and then to 1935 MPa on subsequent aging of the cold-drawn material at 600°C for four hours. Furthermore, the alloy was found to show a 50% reduction in area before failure in tension tests of the cold drawn and aged samples. The mechanisms of the primary and secondary hardening obtained through cold working and subsequent aging have been investigated in this study by optical and transmission electron microscopy investigations on deformed and deformed and aged samples. Some of the interesting observations made in our study include: (i) Plots of strain hardening rate versus stress (or strain) in simple compression of annealed MP35N indicate four distinct regimes of strain hardening which when suitably normalized were found to be in excellent agreement with the corresponding measurements in several other low stacking fault energy fcc alloys. (ii) The amount of secondary hardening in MP35N depended critically on the amount of plastic deformation imposed prior to aging. It was observed that a strain of about 0.2 was needed before secondary hardening could be detected and that the increase in strength by secondary hardening saturated at a strain of about 0.6. (iii) Simple compression deformation on samples that exhibited significant
secondary hardening produced extensive micro-scale shear banding. The extent of shear banding increased with increased levels of secondary hardening and macro-scale shear bands were noted in compression of heavily deformed and aged samples. (iv) Measurements of plane strain fracture toughness revealed that the 53% cold-worked samples retained high toughnesses (about 120 MPa m112) even after the secondary hardening. The formation of shear bands noted above did not seem to effect either the fracture toughness or the ductility of the deformed and aged samples compared to the deformed only samples upto about 53% reduction levels in cold-drawing. Beyond about 60% reduction levels in cold-drawing, the ductility of the deformed and aged samples was observed to drop precipitously. A detailed investigation using the optical microscope and TEM was undertaken to explain the above observations. We are presently attempting to correlate the microscopy observations to the results from the mechanical testing. These results and our current understanding of the physical origin of the properties described above will be presented.
The effects of heat treatment and Mo content on microstructure and mechanical properties of high temperature gear steels have been investigated. High temperature gear steels require temper resistance, hot hardness, fracture toughness and impact strength for operation at elevated temperatures. The compositions(wt.%) of gear steels studied in this work were Fe-2.0Ni-I.Ocr(l-3.15)Mo-2.0Cu-OAMn-0.llC steels. The ingots manufactured by the vacuum induction melting were hot-rolled at 1473 K to 15mm thickness. The hot-rolled plates were quenched and tempered at various conditions. The degree of secondary hardening is increased with the Mo content due to the precipitation of fine alloy carbide(M02C) during tempering treatments. Continuous cooling transformation diagrams were obtained. High temperature mechanical tests(Hardness, Toughness, Impact energy) were conducted. Cylindrical compressive specimens of 8mm diameter and 12mm height were machined from the hot-rolled plates. High temperature compressive tests were carried out in an compression testing machine at various strain rates. The microstructure aRer deformation was investigated. The deformed structure was dynamically recrystallized at higher temperatures and lower strain rates. Activation energy and flow equation at high temperatures were discussed.
9:50am MECHANICAL BEHAVIOR OF PM uno FORGED ALLOY AT ELEVATED TEMPERATURES: Chih-An Yin, and K. A. Green, Allison Engine Company, P. O. Box 420, S-52, Indianapolis, IN 46204-0420
11:00 am MICROSTRUCTURAL CHANGE DURING SUPERPLASTIC DEFORMATION IN LOW ALLOYED Zn-Al ALLOY: W.B. Lee, T.K. Ha, CG. Park, Center for Advanced Aerospace Material, Univ. of Sci. & Tech., POSTECH, Pohang, 790-784, Korea
Material characterization tests for tensile, creep-rupture, low cycle fatigue and fatigue crack growth responses were conducted on PIM uno forged disc alloy SUbjected to a specified heat treatment. The purpose of this investigation is to examine the effects of the thermomechanical processes on the high temperature mechanical behavior of this material with a special attention to the creep-rupture, low cycle fatigue and fatigue crack growth rate. The results of analysis are mainly based on the phenomenological approach and predicted methods so that the quantitative comparison can be presented. in addition, the fracture morphologies of the material at 538°C and 650°C were also investigated by SEM and optical metallography to determine the relationships of failure modes, relative fatigue and creep-rupture life to the grain size, local microstructure and defect inclusions resulted from different consolidation processes.
Microstructural change and deformation behavior have been observed in superplastic Zn-Al alloys. Row-alloyed Zn-AI alloys, which contains a small fraction of precipitates at grain boundary, showed superplastic deformation behaviors even at room temperature, while pure Zn is very brittle. In the present study, the effects of aluminum composition (up to 1 wt.%) on the change in the microstructure (the role of precipitates) as well as dislocation structure have been investigated during the superplastic deformation. TEM in situ deformation was also performed to investigate dislocation behavior at grain boundary during superplastic deformation oflow alloyed Zn-AI alloys. 11:20 am EFFECTS OF YIELD STRESS AND TEXTURE ON DELAYED HYDRIDE CRACKING IN Zr-2.5Nb PRESSURE TUBE: In Sup Kim, Je Yong Oh, Korea Advanced Institute of Science and Technology, Taejon 305701, S. Korea
10:10 am BREAK 10:20 am STUDY AND COMPARISON OF (111 }DEFORMATION MICRO BANDS ASSOCIATED WITH IMPACT CRATERS AND PENETRATION CHANNELS IN THICK COPPER PLATES: L.E. Murr, J.M. Rivas, E. P. Garcia, CoS. Niou, and E. Ferreyra T., Department of Metallurgical and Materials Engineering, The University of Texas at El Paso, EI Paso, TX 79968
The delayed hydride cracking (DHC) in pressure tubes is caused by diffusion of hydrogen atoms into crack tip region, precipitation of hydride, and consequent fracture of the hydrided region under stress. To explain DHC quantitatively, many models have been proposed and the Puis model has been well recognized among them. In this study, the effects of yield stress and texture on DHC have been investigated in Zr-2.5Nb pressure tube material and experimental results were introduced and compared to Puis DHC model. The delayed hydride cracking velocity (DHCV) increased with yield stress, while the threshold stress intensity factor increased as yield stress decreased. The activation energy of DHCV was dependent on the texture. When the direction of crack propagation was longitudinal, the activation energy was 34kJI mol. However, in the case of circumferential propagation, the energy was measured as 17kJ/moi.
While copper, having critical grain sizes greater than about 20 !lm, will twin above a critical, plane-wave shock pressure of about 20 GPa, {Ill }deformation twins are essentially absent below impact craters or along dense rod penetration channels in copper plates (1.3 to 3.5 cm thick) where instantaneous (plane-wave impact) shock pressures exceed 100 GPa; for spheres and rods impacting at velocities between 1.5 and 6.7 kmIs, with densities ranging from 2.2 to 17.6 g/cm3. However, deformation microbands consisting of elongated, dense dislocation wall structures (0.1 to 0.4 ,am wide), coincident with primary { Ill} planes; occur in bands or zones removed several millimeters from the crater or penetration channel walls, and predominantly in grains which exhibit little or no (plastic) distortion. These microbands possess misorientations ranging from I to 3° and appear to be created as a consequence of intense shear wave phenomena associated with these unique, high strain, high-strainrate deformation regimes. They also occur amongst dense, equiaxed, dislocation cells whose misorientations are <1°, and appear to be related to ( III }deformation twins or twin faults which also emerge from or occur amongst, dislocation cells in plane-wave shock loaded copper, for example. Supported by NASA-JSC Grant NAG-9-481 and U.S. Army Contract DAAE30-94-C-0059.
11:40 am DEVELOPMENT OF TEXTURE AND MICROSTRUCTURE DURING COLD ROLLING OF Ni~I(B,Zr): B. Bhattacharya, R.K. Ray, Department of Materials and Metallurgical Engineering, Indian Institute of Technology, Kanpur - 208016, India The present report deals with textural as well as microstructural developments during cold rolling of a two-phase Ni,AI(B,Zr) alloy. Basically a pure metal type texture was obtained at lower levels of deformation, while a mixed type (both pure metal and alloy type) was observed at high strain. The transition was detected after about 35% reduction which was correlated with a possible structural transformation in the yl'phase. The change of deformation mode from slip to twinning in i was confirmed by electron microscopy. However, the second phase (Ni-base, disordered yphase) in the alloy is not known to suffer any change in the deformation mode with straining. Therefore, it is suggested, that the textural development in the two phases will be of different nature; the combined effect will be reflected in the form of the textural change
10:40 am EFFECTS OF HEAT TREATMENT AND MO CONTENT ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Fe-NiCr-Mo HIGH TEMPERATURE GEAR STEELS: Cha-Yong Lim, SungJoon Kim- Korea Institute of Machinery and Materials, #66 Sangnam-Dong, Changwon, Kyungnam, Korea 641-010
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for the whole sample, as mentioned above.
gated. The results indicate that titanium additions lead to a substantial improvement in toughness at a carbon level of 0.16 but the improvement in toughness is less at a carbon level of 0.16 but the improvement in toughness is much less at a carbon level of 0.2. The objective of the work reported here is identification of sulfide type and measurement of sulfide size in these two higher carbon steels. Because of the large number of possible sulfides of titanium the major emphasis has been on identifying sulfide type from transmission electron microscopy diffraction results.
PHYSICAL METALLURGY: Fundamentals and Applications TMS General Abstract Session Monday, AM February 10, 1997
Room: 232B Location: Orlando Convention Center
9:30pm HIGH TEMPERATURE PHASE STABILITY OF THE YTTRIA STABILIZED t' PHASE ZIRCONIAS: James S. Smith, Fu-Jen Pan, Jan-Fong Jue, Materials and Systems Research Inc., 1473 S. Pioneer Rd., Salt Lake City, UT 84104; Kevin T. Zysk, AEDCIDOT, 1099 Avenue C, Arnold Air Force Base, TN 37389-9011
Session Chairperson: Warren M. Garrison, Dept. of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213
8:30am EFFECT OF COLD WORKING ON THE OMEGA PHASE IN BETA TITANIUM ALLOYS: M.Saqib, N. Stefansson, R. Srinivasan, I. Weiss, Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH 45435
Yttria doped zirconias containing 3 to 8 mole% stabilizer were fabricated by (i) sintering at 1450°C and (ii) heat treating at 2100°C for 15 minutes with a gas fired furnace to obtain (i) regular tetragonal (t) and cubic (c) phase, and (ii) largegrained tetragonal (I') and c phase materials, respectively. The materials were annealed at temperatures between 11 OO°C and 2000°C in air for various times. The effect of annealing time and temperature as well as cooling rate on the phase stability of the I' phase zirconia will be discussed. A working T-T-T diagram will be proposed. High temperature bending strength and compressive strength data will be presented. The possibility of precipitation strengthening in the annealed samples will also be addressed.
High specific strength, excellent corrosion resistance, good cold formability and age hardening response are some of the attractive properties of the metastable ~ titanium alloys. The effect of cold deformation on the stability of OJ phase present in metastable ~ alloys is not clearly understood. In this study, two ~ titanium alloys: TIMETAL 21S and TIMETAL LCB were fast cooled from above the ~-transus temperatures and subsequently cold rolled to total reductions ranging from 5 to 35%. The fast cooled microstructure consisted of ~ phase with dispersion of athermal OJ precipitates. Selected area electron diffraction patterns from the as-cooled and the cold rolled specimens revealed the presence of diffuse intensity maxima at l/3<112>~ and 2/3<111>~ locations, characteristic of the presence of OJ phase. The average integrated intensities of the diffuse maxima from the OJ phase and the sharp diffraction spots from the ~ phase were measured using microdensitometer. The intensity ratio; (diffuse intensity) oo/(diffraction spots intensity) ~ was used as a measure of the relative volume fraction of the OJ phase in the ~ phase matrix. The volume fraction of the OJ phase was found to decrease linearly with an increase in the amount of cold deformation both alloys.
9:50 am BREAK 10:00 am PHASE STABILITY IN NbCr2-BASED LAVES PHASE ALLOYS: J.H. Zhu, P.K. Liaw, Department of Materials Science and Engineering The University of Tennessee, Knoxville, TN 37996; C.T. Liu Metals and Ceramics Division Oak Ridge National laboratory Oak Ridge, TN 37831-6115 Phase stability in NbCr2-based transition-metal Laves phases is studied in this paper, using data from binary X-Cr, Nb-X, and ternary Nb-CrX phase diagrams. It was shown that when the atomic size ratios are kept identical, the average electron concentration factor (e/a = the average number of electrons per atom outside the closed shells of the component atoms) is the determinate factor in controlling the phase stability of NbCr2-based transition-metal Laves phases. The eta ratios for different Laves phase structures were determined as follows: with eta < 5.76, the C15 structure is stabilized; at an e/a range of 5.88-7.53, the C14 structure is stabilized; with eta> 7.65, the C15 structure was stabilized again. A further increase in the electron concentration factor (e/a > 8) leads to the disordering of the alloy. The electron concentration effect on the phase stability of transition-metal A3B intermetallic compounds and Mg-based Laves phases is also reviewed and compared wit'n the present observations in transition-metal Laves phases. Finally, experimental results on Cr-Nb-Cu ternary system were also presented and explained in light of the eta ratio correlation with phase stability.
8:50am GRAIN BOUNDARY NIOBIUM-RICH CARBIDES IN INCONEL 718*: Ming Gao, Robert P. Wei, Dept. of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA 18015 In a previous study, niobium was identified as the principal embrittling element for oxygen-enhanced crack growth in nickel based alloys, such as Inconel 718. Niobium was believed to come principally from the oxidation and decomposition of niobium-rich carbides at the grain boundaries. To better establish their type density and distribution, g.b. carbides in Inconel 718 that were exposed by crack growth at 700°C or by hydrogen embrittlement were characterized by SEM and EDS. The carbides were also analyzed by highresolution AEM. Two types of carbides were identified; those associated with the primary NbC, and those (secondary carbides) that formed during heat treatment. The results will be presented and discussed in relation to environmentally assisted crack growth. Research supported by the National Science Foundation, Division of Materials Research, under Grant DMR-9102093.
10:20 am THE MARTENSITIC TRANSFORMATION CURVES FOR SHAPE MEMORY ALLOYS: H.Y. Yu, Naval Research Laboratory, Mechanics of Materials Branch, Code 6380, Washington, D.C. 20375-5343 The mechanical behavior of shape memory alloys is closely related to the martensitic phase transformation. A martensitic transformation is considered to be a first order solid state structural transformation that is diffusionless and whose initial phase maintains metastability. Conventional models, such as the "exponential model" and the "cosine model" do not describe the martensitic transformation satisfactorily. In this study, the martensitic transformation curves for thermoelasaticity and pseudoelasticitiy are obtained by using the principle of energy balance. The results are in good agreement with experimental results for steels and nitinol alloys.
9:10 am THE INFLUENCE OF CARBON LEVEL ON SULFIDE PARTICLE DISTRIBUTIONS IN TITANIUM MODIFIED STEELS OF THE AF1410 TYPE: Luana E./orio, Warren M. Garrison, Jr., Dept. of Materials Science and Engineering, Camegie Mellon University, Pittsburgh, PA 15213 Earlier studies showed that small titanium additions to the 0.10 wt. % carbon steel HY180 lead to the gettering of sulfur as particles of Ti 2CS. The Charpy impact energy of HY180 when sulfur is gettered as MnS is about 160J but increases to about 270J when sulfur is gettered as Ti,CS. The improvement in toughness is attributed to the particles of Ti 2CS being more resistant to void nucleation than particles of MnS. The effects of small titanium additions on sulfide and other second phasae particle distributions and the toughness of AF1410 steel at carbon levels of 0.16 wt% and 020 wt% are being investi-
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10:40 am RULE OF ADDITIVITY IN PHASE TRANSFORMATIONS: David T. Wu, Dept. of Mechanical Engineering, Yale University, P.O. Box 208284, New Haven, CT 06520
RARE EARTHS, SCIENCE, TECHNOLOGY AND APPLICATIONS I: Separation and Processing Sponsored by: LMD Reactive Metals Committee Program Organizers: R.G. Bautista, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno, Reno, NV 89557; C.O. Bounds, RhonePolenc Rare Earths and Gallium, CN 7500, Prospect Plains Rd., Cranbury, NJ 08512; Timothy W. Ellis, Lulicke and Soffa Industries, Inc., 2101 Blair Mill Rd., Willow Grove, PA 19090; Barry T. Kilbourn, Molycorp, Inc., Executive 46 Office Center, 710 Route 46 East, Fairfield, NJ 07004
The rule of additivity is used to predict CCT diagrams from TTT diagrams. Avrami showed that a nucleation and growth reaction is additive if it is isokinetic. Later Cahn proposed site-saturation as another condition for additivity to hold. This talk presents more general conditions under which the rule of additivity is valid. 11:00 am REVISITING THE EFFECT OF CURVATURE ON CHEMICAL POTENTIAL FOR BINARY SYSTEMS: N Kulkarni, R T. DeHoff, 253A Rhines Hall, Depaslment of Materials Science and Engineering, University of Florida, Gainesville, FI-32611
Monday, AM February 10, 1997
Room: Salon 8 Location: Clarion Plaza Hotel
Session Chairpersons: Renata G. Bautista, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno, Reno, NV 89557; K. OsseoAsare, Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802
The effect of curvature on the chemical potential for binary systems, at constant temperature and pressure, is usually given in the literature by the GibbsThomson equation. Many forms of this equation have appeared in the literature, that can be shown to be incorrect and in violation of the condition for chemical eqUilibrium for a two-phase system. A simple self-consistent procedure to derive the Gibbs-Thomson equation for binary systems is provided. The resultant equation for the chemical potential shift is independent of the solution model and has an inverse dependence on the width of the two-phase field.
8:30am SEPARATION OF RARE EARTHS, THORIUM AND URANIUM DURING MONAZITE PROCESSING BY SOLVENT EXTRACTION USING 2-ETHYL HEXYL PHOSPHONIC ACID MONO 2-ETHYL HEXYL ESTER: NS. Narayanan, Y.R. Nair, V.D. Narayanan, Indian Rare Earths, Limited, Rare Earths Div., Udyogamandal, 683 501, Kerala State, India
11:20 am METRIC AND TOPOLOGICAL CONTRIBUTIONS TO THE RATE OF CHANGE OF BOUNDARY LENGTH IN TWO DIMENSIONAL GRAIN GROWTH: R.T. DeHoff, Department of Materials Science Engineering, 253A Rhines Hall, University of Florida, Gainesville, Fl-32611
Monazite, one of the major sources of rare earths, is normally opened by digestion with hot concentrated caustic soda solution. Caustic digestion dissolves phosphate and leaves a hydrated mixed metal oxides cake con- containing thorium, uranium and rare earths. By leaching this cake with hydrochloric acid at pH 3.0 to 3.2 bulk of the rare earths are preferentially removed and separated. The slurry left after removal of major portion of rare earths contains all the thorium and uranium present in the feed monazite. In addition this slurry also contains substantial quantities of rare earths. Solvent extraction tests were carried out to develop a process to separate rare earths, thorium and uranium present in the mixed chloride solution obtained by dissolving the above slurry in hydrochloric acid.
The boundary in a two dimensional grain structure decreases its length during grain growth. Four distinct processes may contribute to this length change: I) The smooth motion of the grain edges toward their centers of curvature; 2) Migration of cell corners resulting from the edge motion; 3) The annihilation of small grains (topological process b; 4) The switching process (topological process II). Using von Neumann's assumption that the local velocity is proportional to the local boundary curvature and geometrically general kinematic equations, the contribution of each of these four processes is assessed The result is a kinetic equation in which the metric and topological contributions to the rate of grain growth in two dimensions are made explicit.
9:00am PREPARATION OF DYCL3 BY DEHYDRATION IN A FLUIDIZED BED: lohan Sundstrom, Department of Metallurgy, Division of Process Metallurgy, The Royal Institute of Technology, S-100 44, Stockholm, Sweden. Anhydrous DyCI, was prepared from its hexahydrated mother-compound by batch-wise and continuous dehydration using a fluidized bed. A gas mixture of variable composition between argon and HCl was used. The productivity was high, reaching values of 0.28 mol Hplm2xs during the dehydration to DyCI,xHP and 0.079 mol H,Q/m2xs during the dehydration to DyCI,. By using an overall reaction rate equation, developed from previous findings it was possible to predict the outcome of the continuous fluidization process. The fluidization process efficiency decreases drastically when water content is below DyCI3xO.lHp. Therefore, in a final treatment the last traces of water were removed by slowly purging gas through a fixed bed. 9:30am MASS SPECTROMETRIC STUDY OF VAPORIZATION PROCESSES AND THERMODYNAMIC PROPERTIES OF DyF3-DY203: v.L. Stolyarova, S. Seetharaman, The Royal Institute of Technology, S-100 44, Stockholm, Sweden In the present work the vaporization processes and thermodynamic properties Of the DyF3-Dy,Q, system were studied at the temperatures 1173-1423 K in the concentration range from the individual DyF, to the individual DY2 by the Knudsen effusion mass spectrometric method. It was found, the DyF3' DyOF, Dy,QF4 molecules were the main species in vapour. The DyF, activity in the DyF,-Dyp, system was calculated by comparing the total ion currents of dysprosium triufluoride over the system and the individual compo-
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nent. The influence of the cell material (Pt, Mo, Ta) on the concentration of the DyFJ, DyOF, Dy,oF4 vapour species in the gaseous phase over the DyF3Dy,03 was illustrated. Results, obtained in the present study are in agreement with the available information on the phase diagram of the DyFJ-Dy,oJ system.
RECENT ADVANCES IN FRACTURE I: Elastic Plastic Fracture I: A Symposium Dedicated to Professor Emeritus Frank A. McClintock
10:00 am BREAK
Sponsored by: MSD Flow and Fracture, SMD Mechanical Metallurgy Committees Program Organizers: Dr. R.K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; Dr. A.B. Geltmacher, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D.C. 20375; Dr. K. Sadananda, Naval Research Laboratory, Code 6323, 4555 Overlook Drive SW, Washington D.C. 20375; Dr. P. Matic, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D.C. 20375
10:30am PRECIPITATION PROCESSES IN THE SEPARATION OF RARE EARTHS: K. Osseo-Asare, Department of Materials Science and Engineering, Pennsylvania, State University, University Park, PA 16802 Abstract not available. 11:00 am Nd,Fe 14B/oc-Fe BASED NANOCOMPOSITE PERMANENT MAGNET MATERIALS PREPARED VIAL MECHANICAL MILLING: W.E Miao, P.G. McCormick, R. Street, Research Centre for Advanced Mineral and Materials Processing, The University of Western Australia, Nedlands, w.A. 6907, Australia
Monday, AM February 10, 1997
Room: 314A Location: Orlando Convention Center
Session Chairpersons: Professor Ali S. Argon, Department of Mechanical Engineering, Massachusetts Institute ofTechnology, Cambridge, MA 02139; Dr. K. Sadananda, Naval Research Laboratory, Code 6323, 4555 Overlook Drive SW, Washington D.C. 20375
Nanocrystalline mixtures of Ndj'e 14B and oc-Fe have been synthesized by mechanical milling and heat treatment. The samples exhibit isotropic magnetic behaviour, with significant remenence enhancement associated with exchange coupling across the interfaces of hard and soft magnetic phases. Magnetic Phases. Magnetic properties are found to depend on the volume fraction of the oc-Fe phase and heat treatment. The effect of alloy additions to increase the saturation magnetization of the soft phase and the magnetocrystalline anisotropy of the hard phase has also been investigated.
8:30am OPENING STATEMENTS: Dr. K. Sadananda, Head, Deformation and Fracture Section, Naval Research Laboratory, Code 6323, Washington D.C. 8:40am INTRODUCTION OF PROFESSOR EMERITUS FRANK A. McCLINTOCK: Professor Ali S. Argon, Department of Mechanical Engineering, Massachusetts Institute of Technology, Room 1-306, Cambridge, MA 02139
11:30am NOVEL TECHNIQUE FOR THE PREPARATION OF SINTERED YBCO: M.l. Hussain, FA. Khwaja, Mazhar Hussain, Anwar-VI-Haque, Department of Physics, Quaid-I-Azam University, Islamabad, Pakistan., Department of Chemistry, Quaid-I-Azam University, Islamabad, Pakistan
8:50 am KEYNOTE DUCTILE FRACTURE: HIGHLIGHTS AND PROBLEMS: Professor Emeritus Frank A. McClintock, Massachusetts Institute of Technology, Department of Mechanical Engineering, Room 1-304, Cambridge, MA 02139
We report on the preparation ofYBCO sintered sample by a novel technique named "Explosion Method". The stoichiometric ratio of the compounds were mixed and the powder was encapsulated in the quartz tube. The capsule exploded at 16-hours for specific mass of the product and the size of the tube. The powder was pelletized and characteristic properties were checked. The detailed investigation is carried out on the mass of the product and the size of the capsule which plays an important role in the preparation of superconducting phase, in this method. It has been observed that explosion is important for the superconductivity. The absence of annealing is an advantage in this process, however, the sample deteriorate with time.
The developing understanding of fracture by hole growth is reviewed, with mention of unsolved problems: Tipper in the late 1940's showed not only the idealized limiting micro-mechanisms of fracture by cleavage and by hole growth, but also the current problems of linkages of holes by irregular fine cracks and cleavage with concurrent plastic deformation. Both micromechanisms can lead to either ductile or brittle structures; the IrwinWilliams stress intensity concept K; the Paris fatigue crack correlation; elastic-plastic fracture instability in sheet, the Hutchinson, and Rice and Rosengren annular I-fields for initial and early growth of cracks in power-law materials; The K-T and J-Q extensions; fracture mechanics for predicting the behavior of large structures from tests on small, perhaps fully plastic specimens; traditional and fitness-for-service design and maintenance; the finite element method; its strength, current limitations, and needs; history effects, including the wolf's ear fracture, very low cycle fatigue, and torsion; micro-models of crack formation and growth; McClintock and Ourson; extreme value idealizations in statistics; cooperative and multi-stage problems; crack roughening and three-dimensional effects; recent work on rigid-plastic; non-hardening mechanics of initial and continuing growth of cracks, both with and without symmetry. 9:20 am INVITED ELASTIC-PLASTIC FRACTURE MECHANICS OF STRENGTHMISMATCHED INTERFACE CRACKS: David M. Parks, S. Oanti, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 Recent progress in rationalizing and predicting the diverse ductile and brittle cracking behaviors seen in a given structural alloy under monotomic loading (i.e., shallow versus deep cracks; tension versus bending; ductile growth versus cleavage, etc.) has rested critically upon improved characterizations of elastic-plastic crack-front stress and deformation fields. For macroscopically homogeneous elastic-plastic materials, these improved descriptions of the crack-front fields typically include a parameter such as J or CTOD which
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10:45 am INVITED THE ROLE OF FRICTIONAL CRACK SLIDING ON THE COMPRESSIVEFAILURE OF ICE AND ON ITS BRITTLE·TO·DUCTILETRAN· SITION: Erland M. Schulson, Department of Mechanical Engineering, Thayer School of Engineering, 8000 Cummings Hall, Darthmouth College, Hanover. NH 03755
scales the intensity of crack-tip deformation, as well as a parameter such as the T-stress or the Q parameter which accounts for the triaxiality of the cracktip fields. When a crack lies along or near a planar material interface across which there is a significant gradient in plastic deformation resistance, the local stress and deformation fields exhibits features which differ both in magnitude and in kind from the homogeneous fields noted above. Such conditions are encountered in strength-mismatched weldments, in which the flow strength of the weld metal, Ywm' differs that of the baseplate, Ybp ' Major features of such strength-mismatched interface fields are that (i) for a given macroscopic characterization of crack-tip deformation (in terms of J or aOD), deformation preferentially focuses in the softer material, and (ii) stress triaxiality in the softer material exceeds that attainable in even the most severe of the homogeneous fields noted above. We review basic features of strength-mismatched interface crack fields as determined from finite element solutions under well-constrained and fully plastic conditions, for a range of strength mismatches and strain hardening behaviors. The fields can be welldescribed with slip-line fields appropriate to the level of strength-mismatch. Implications of these fields for the toughness of interface cracks are noted.
In 1962 McClintock and Walsh pointed out that frictional sliding across the surface of closed cracks inclined to the direction of loading is an important element in brittle compressive failure. The friction reduces the effective shear stress on the crack plane and so lowers the stress concentrated at the crack tip. Frictional sliding thus increases the far-field stress for out-of-plane wing crack initiation and growth, thereby raising the failure stress (e.g., Brace and Bombolakis 1963, Nemat-Nasser and Horii 1982, and Ashby and Hallam 1986). This paper will show that the brittle compressive failure of ice can be understood in terms of the frictional crack sliding/wing crack mechanism, and that its brittle-to-ductile transition can be explained by incorporating cracktip creep.
9:45 am INVITED IN-PLANE CONSTRAINT EFFECTS IN ELASTIC-PLASTIC FRACTURE MECHANICS: John W Hancock, I. Li,A.D. Karstensen, A. Nekkal, Department of Mechanical Engineering, University of Glasgow, Scotland G 12 8QQ, UK
11:10 am INVITED FRACTURE IN THE DUCTILE AND DUCTILEIBRITTLE REGIMES: CELL MODEL STUDIES: Robert H. Dodds} and C. Fong Shi2, 'Department of Civil Engineering, 2129 Newmark Laboratory, MC-250, University of lllinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, IL 61801; 2Division of Engineering, Brown University, Providence, RI 02912
McClintock (1971) has shown that under plane strain conditions, the fully plastic flow fields are not unique, but depend on geometry and loading. In mode I, the loss of uniqueness is shown to originate from the nature of the elastic field and in particular the sign of the non-singular T stress. The nature of these fields is elucidated by constructing a family of plane straw slip line fields (Du and Hancock 1991). As such they belong to a family of fields which can be described by J and a second parameter which determines the level of crack tip constraint (QIl). This family of fields are deviatorically similar but differ largely hydrostatically (O'Dowd and Shih 1991, Beteg6n and Hancock 1991). Boundary layer formulations have been used to infer the force on mixed mode slip line fields in contained yielding (Hancock, Karstensen and Nekkal 1996). These differ from those discussed by Shih (1974) in that plasticity does not surround the crack tip, due to the occurrence of an-elastic wedge on the crack flanks. Both mode I and mixed mode fields for weakly stain hardening materials can be interpreted as belonging to a single family such that constraint loss by mixed mode loading. This gives a family of fields which differ largely hydrostatically on the plane of maximum hoop stress. Finally slip line fields for cracks on the interface between a rigid subsume and a perfectly plastic material, subject to mixed mode loading have been constructed, and these are also discussed in terms of constraint effects (Li and Hancock 1996). Experimental data on the effect of in plane constraint on fracture toughness is discussed within the framework of two parameter fracture mechanics. Finally the methods by which constraint enhanced toughness can be used in safety cases based on failure assessment diagrams is discussed (MacLennan and Hancock 1995).
Mode I crack initiation and growth under plane strain conditions in tough metals have been successfully simulated using an elastic-plastic continuum model which accounts for void growth and coalescence ahead of the crack tip. A row of void-containing cell elements is placed on the symmetry plane ahead of the initial crack. These cell elements incorporate the softening characteristics of the hole growth and its strong dependence on stress triaxiality. Under increasing strain, the voids grow and coalesce to form new crack surfaces thereby advancing the crack. The material parameters are the Young's modulus, yield stress and strain hardening exponent of the metal and two additional parameters, D and fo' characterizing the dimension of the cell element and the initial volume fraction of the void centered within the cell. Once the above material parameters have been calibrated for the material under investigation, the model can be applied to compute relationships among load, load-line displacement and crack advance with no restrictions on the extent of plastic deformation and crack advance [Xia and Shih, (1995a and 1995b)]. The model has been applied to several specimen geometries which are known to give rise to significantly different crack tip constraints and crack growth resistance behaviors. Computed results are compared with sets of experimental data for two tough steels. Details of the load, displacement and crack growth histories are accurately reproduced [Xia, Shih and Hutchinson, 1995]. Suitably defined measures of crack tip loading intensity, such as those based on the I-integral can also be computed; however such crack growth resistance curves no longer play the central role in this approach. The above model has been employed in the transition regime where a crack initiates an grows by ductile tearing but final failure can occur catastrophic cleavage fracture. Crack growth causes significant alterations in the stress field, the process zone size, the competition between ductile and brittle processes and the sampling volume. The effects are accounted for by incorporating weakest link statistics into the cell element model. The cleavage fracture model also takes into account the increase of sampling volume with crack growth and the competition between void nucleation from carbide inclusions and unstable inclusion cracking which precipitates catastrophic cleavage fracture. Load-displacement behavior, ductile tearing resistance and transition to cleavage fracture are discussed for several different test geometries and a range of microstructural parameters. The model predicts trends in the ductilelbrittle transition region that agree with experimental data [Xia and Shih, (1996)].
10:10 am BREAK 10:20 am INVITED TOUGHENING OF METAL MATRIX COMPOSITES THROUGH CONTROL OF INTERFACE TOUGHNESS BETWEEN FIBERS AND MATRIX: Ali S. Argon}, M. Seleznev' and C.F. Shih2, 'Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, 2Division of Engineering, Brown University, Providence, RI 02912 In Al alloys reinforced with AI20 3 fibers control of the size of interface precipitates of A~Cu, through coarsening, permits control of the effective separation toughness of the interface under the deformation induced local mixed modes of interface fracture during the evolution of global composite fracture, which assures optimization of both transverse strength and axial toughness. Experiments and micromechanical modeling will be presented demonstrating the effectiveness of this strategy.
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10:05 am PHASE SEPARATION, CRYSTALLIZATION AND FORMATION OF QUASICRYSTALS IN BULK Zr-BASEDAMORPHOUSALLOYS: Uwe
STRUCTURE AND PROPERTIES OF BULK AMORPHOUS ALLOYS I
Koster, Department of Chemical Engineering, University of Dortmund, D44221 Dortmund, Gennany
Sponsored by: Jt. EMPMD/SMD Alloy Phases Committee, ASM-MSD Thermodynamics and Phase Equilibria Committee, MSD Atomic Transport Committee, MDMD Solidification Committee, Lawrence Livermore National Laboratory and Los Alamos National Laboratory Program Organizers: Patrice EA Turchi, Chemistry and Materials Science Department (L-268), Lawrence Livermore National Laboratory, P.O. Box BOB, Livermore, CA 94551; Ricardo B. Schwarz, Center for Materials Science (MSK765), Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545; John H. Perepezko, Department of Materials Science and Engineering, University of Wisconsin, Madison, WI 53706
Monday, AM February 10, 1997
Crystallization occurs by nucleation and growth. Growth may be primary, eutectic or polymorphic. Crystallization statistics as perfonned by TEM indicate heterogeneous nucleation with large transient times below the glass transition; nucleation and growth rates obey Arrhenius equations with activation energies typical for diffusion. Above glass transition homogeneous nucleation has been found and kinetics can be described best by Vogel-FulcherTammann equations. From Crystallization studies typical metal-metalloid glasses are fragile, but the new bulk amorphous alloys are strong glasses. Amorphous phase separation prior to crystallization not only increases the glass fonning ability, but also leads to the fonnation of nanocrystalline structures. Phase separation might be responsible for the strong influence of oxygen and hydrogen on the crystallization of Zr-based metallic glasses. Some bulk amorphous alloys transfonn into quasicrystals. Their nucleation and growth rates are measured in detaiL The relation between glass-fonning ability, existence of Laves phases and fonnation of quasicrystals will be discussed.
Room: 340A Location: Orlando Convention Center
Session Chairperson: Dr. Robert J. Gottschall, Division of Materials Science (ER13), U.S. Department of Energy, Germantown Building, 19901 Germantown Road, Germantown, MD 20874-1290
10:45 am BREAK 8:30am INTRODUCTORY REMARKS: Robert J. Gottschall, Division of Materi-
11:00 am
BULK NANOCRYSTALLINE AND AMORPHOUS REFRACTORY ALLOYS AND THEIR PROPERTIES: S.J. Poon', GJ. Shiflet', DJ. Li',
als Science (ER-13), U.S. Department of Energy, Gennantown Building, 19901 Gennantown Road, Gennantown, MD 20874-1290
KJ. DohertyZ, 'Department of physics, 2Department of Materials Science, University of Virginia, Charlottesville, VA 22901
8:45 am FERROMAGNETIC BULK AMORPHOUS ALLOYS: Akihisa Inoue,
Synthesis of bulk samples of refractory metal alloys containing nanocrystalline and amorphous phases via conventional casting and their structural and physical properties will be reported. First, we will present results on (Fe, Ni, Cu, Nb )9SZrS systems. Key factors for fonning the titled phases will be discussed. Then we will report recent results on titanium alloys, with emphasis on structure and phase transfonnation.
Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-77, Japan Since the discoveries of bulk amorphous alloys in Ln-Al-TM, Mg-Ln-TM and Zr-Al-TM (Ln=lanthanide metal, TM=transition metal) systems for the last several years, great attention has been paid to bulk amorphous alloys. It was subsequently reported that bulk amorphous alloys were fonned in Ti-ZrTM, Zr-Ti-TM-Be and Pd-Ni-Cu-P systems. The maximum thickness reaches 40 mm and the critical cooling rate is of the order of lK1s. However, there have been no data on bulk amorphous alloys with ferromagnetism at room temperature. We have derived three empirical rules for the achievement of large glass-fonning ability from previously reported bulk amorphous alloys. Based on the three rules, we have searched new ferromagnetic bulk amorphous alloys and succeeded in finding several ferromagnetic bulk amorphous alloys in Fe-, Co- and Ln-based systems. The Fe-based bulk amorphous alloys exhibit good soft magnetic properties of 1.3 T for magnetization, 2 Aim for coercive force (Hc), 7000 for penneability at 1 kHz and 21xlO-6 for magnetostriction. The Ln-based bulk amorphous alloys were prepared in the diameter range up to 15 mm and exhibited rather good hard magnetic properties of high Hc of 400 Wm and maximum energy products of 20 kJ/m3. These discoveries seem to be promising for future progress of bulk amorphous alloys.
11:40 am
BULK AMORPHOUS METALLIC ALLOYS: SYNTHESIS BY FLUXING TECHNIQUES AND PROPERTIES: Yi He, Ricardo B. Schwarz, Center for Materials Science, MS-K765, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 Fluxing techniques have been used to study the undercooling and vitrification of glass-fonning binary, ternary and quaternary alloy melts. By reducing and neutralizing heterogeneous nucleation centers, molten Pd lOFe30NiJzo were undercooled to 303 K or 0.26 T no below its melting temperature T m' while bulk amorphous Pd-Ni-P and Pd-Cu-P alloy rods with diameters ranging from 7 to 25 mm were synthesized over a wide composition range. The crystallization temperatures Tx and the glass transition temperatures Tg of these bulk amorphous alloys were determined by differential scanning calorimetry (DSC). For most bulk amorphous Pd-Ni-P alloys, the difference IlT=Tx-T. is larger than 90 K, and bulk amorphous Pd,.,Ni.J'20 cylinders with 25 mm in diameter can be easily fabricated. IlT for bulk amorphous Pd-Cu-P alloys is smaller than for amorphous Pd-Ni-P alloys, and exhibits a dependence on the phosphorus concentration which peaks near 20 at. % P. The glass fonnability of Pd-Cu-P was increased substantially when part of Cu was placed by Ni. Our results demonstrate that the critical cooling rates for glass fonnation in PdNi-P and Pd-Cu-Ni-P alloys are the lowest among all known bulk metallic glass fonning systems. The density, microhardness, elastic properties, specific heat and the glass fonnation range of these alloys will be reported.
9:25am THERMODYNAMIC AND KINETIC ASPECTS OF BULK METALLIC GLASS FORMING ALLOYS: William L. Johnson, W.M. Keck Laboratory of Engineering Materials 138-78, California Institute of Technology, Pasadena, CA 91125 The development of several families of multicomponent alloys which fonn metallic glasses at relatively low cooling rates has triggered renewed interest in thennodynamic and kinetic properties of undercooled liquid metals as well as glass fonnation. Results of studies of atomic diffusion, viscosity, specific heat, liquid phase separation, and crystallization kinetics will be surveyed for alloys in the Zr-Ti-Ni-Cu-Be and Zr-Ti-Ni-Cu-Al systems. Containerless processing studies of the undercooled melts using electrostatic and electromagnetic levitation will be described. Liquid phase separation, impurity effects, and heterogeneous crystal nucleation are found to play an important and often unanticipated role in the crystallization kinetics. This has led to new understanding of the factors which govern glass fonnation in these bulk glass fonning materials.
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9:30am ATOMISTIC STUDY OF GRAIN BOUNDARIES IN NiAI: M. Yanl, V. Vitek', S.P. Chen l, lTheoreticai Division, Los Alamos National Laboratory, Los Alamos, NM 87545; 'Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104
STRUCTURE AND PROPERTIES OF INTERNAL INTERFACES I: Atomic Structures and Bonding Sponsored by: Jt. EMPMD/SMD Chemistry & Physics of Materials Committee, MSD Computer Simulation Committee Program Organizer: Diana Farkas, Dept. of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061; Elizabeth A. Holm, Sandia National Lab, Physical and Joining Metallurgy, MS 1411, Albuquerque, NM 87185-0340; David J. Srolovitz, Dept. of Materials Science & Engineering, University of Michigan, Ann Arbor, MI 48109-2136 Monday, AM February 10, 1997
We have studied the grain boundary properties in NiAI B2 compound by applying the empirical N-body central force potentials of the Finnis-Sinclair type. These potentials have been constructed for B2 NiAI by fitting a number of equilibrium properties of the alloy and reproducing the asymmetric behavior of constitutionals point defects in off-stoichiometric NiAI. At the same time, these potentials assure the structural and mechanical stability ofthe B2 lattice. It was found that in stoichiometric NiAI alloy boundaries in surplus of Al atoms have appreciably lower cohesive strength than the stoichiometric boundaries or boundaries in surplus of Ni atoms. From the structural point of view, boundaries in surplus of Al possess the largest expansion and are associated with large "holes". On the other hand, boundaries with the stoichiometric configuration or in surplus of Ni atoms have more compact structures. The segregation of the antisite defects and vacancies at grain boundaries was also investigated by performing molecular static and Monte Carlo calculations. It was found that no antisite defects are favored at grain boundaries at the stoichiometric bulk composition. In the case of Ni in surplus in the bulk Al atoms have strong tendency to segregate to the boundary region. The effects of such grain boundary features upon the mechanical properties of NiAl will be discussed.
Room: 330G Location: Orlando Convention Center
Session Chairperson: Elizabeth A. Holm, Sandia National Lab, Physical and Joining Metallurgy, MS 1411, Albuquerque, NM 87185-0340
8:30 am INVITED THEORETICAL CALCULATIONS FOR INTERFACES: GRAIN BOUNDARIES IN COVALENT MATERIALS AND METAL-CERAMIC INTERFACES: Masanori Kohyama, Dept. of Material Physics, Osaka National Research Institute, AIST, 1-8-31, Midorigaoka, Ikeda, Osaka, 563, Japan
9:50am GRAIN BOUNDARY STRUCTURE TRENDS IN B2 COMPOUNDS: Batsirai Mutasa, Diana Farkas, Yuri Mishin, Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
For distorted configurations at interfaces in covalent materials or for interfaces between dissimilar materials, it is difficult to develop reliable interatomic potentials. For such systems, it is desirable to perform electronic structure calculations so as to clarify the stable configurations and microscopic nature. Currently, such kinds of enormous calculations are becoming possible by virtue of the development of the efficient theoretical methods and the high-performance computers. In this paper, we present our recent band-theoretical calculations for grain boundaries in Si, SiC and diamond, and for AISiC interfaces. First, grain boundaries in covalent materials have been dealt with by using the transferable tight-binding method [1]. For those in Si, general features of stable configurations and general relations between local structural disorder and local electronic structure are clarified. These are compared with those in diamond. For those in SiC, effects of interfacial C-C or Si-Si bonds and interfacial stoichiometry are analyzed. Second, ab initio calculations for grain boundaries in Si and in SiC have been performed by using the first-principles molecular dynamics (FPMD) method [2]. Stability of the structural models and the nature of interfacial C-C and Si-Si bonds in SiC are analyzed more quantitatively. Third, ab initio calculations for AI-SiC interfaces have been investigated [3]. The features of AI-C and Al-Si interactions at the interfaces are clarified.
The relaxed atomistic grain boundary structures in B2 aluminides were investigated using molecular statics and embedded atom potentials in order to explore general trends for a series of B2 compounds. Free surface energies and grain boundary structures were studied in three compounds, FeAl, NiAl and CoAl. These alloys respectively have increasing anti-phase boundary energies. The misorientations chosen for detailed study correspond to the L5(310) and ~5(21 0) boundaries. The effects of both boundary stoichiometry and simulation block stoichiometry on grain boundary energetics were considered. Chemical potentials and point defect energies were calculated for boundaries contained in both stoichiometric and off-stoichiometric bulks. The surface energies for these B2 aluminides were also calculated so that trends concerning the cohesive energy of the boundaries could be studied. The implications of stoiciometry, the multiplicity of the boundary structures and possible transformations between them for grain boundary brittleness are also discussed.
9:10am ATOMIC STRUCTURE OF INTERFACES IN THE LAMELLAR TiAI AND EFFECTS OF DIRECTIONAL BONDING: V. Vitek, R. Siegl, Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104; H. Inui, M. Yamaguchi, Department of Metal Science and Technology, Kyoto University, Kyoto 606, Japan
10:10 am BREAK 10:30 am INVITED EPITAXY AND ORIENTATION RELATIONSHIP IN BICRYSTALS: P. Pirouz' , Y. Ikuhara', F. Ernst3, 'Deparment of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106-7204; 'Department of Materials, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan; 3Max-Planck-Institut flir Metallforschung, Seestr. 92, D-70174, Stuttgart, Germany
The microstructure of nearly stoichiometric TiAI alloys, which are important candidates for high-temperature applications, consists of lamellae with Llo and DO '9 structures. A serious limitation is their low room temperature ductility. The failure often occurs by cracking along the lamellar interfaces and one clue to the fracture propensity is the atomic structure of these interfaces. To investigate this atomic structure we first carried out atomistic calculations employing Finnis-Sinclair type central force many-body potentials. However, calculated atomic structures exhibit some significant discrepancies when compared with high-resolution electron microscopy observations. For this reason further calculations have been made using an ab initio electronic structure full-potential method. An excellent agreement between calculated and observed structures was then attained. This result can be interpreted in terms of the covalent type bonding across the interface. This emphasizes significance of directional bonding in TiAI which may play an important role in its mechanical behavior. *Research supported by the U.S. Dept. of Energy, Office of Basic Energy Sciences, Grant No. DE-FG02-87ER45295 and NEDO.
When two crystals are in contact, the interaction between the atoms at or near their interface often orients the crystals in a unique way. Usually, one of the two crystals is a matrix or a substrate, and the other crystal is a precipitate within the matrix, or a deposit on the substrate. In this talk, a recently-proposed method for predicting the orientation relationship (OR) between two crystals is described and experimental cases of film/substrate composites are compared with the predictions of the model. The case of three-dimensional OR, where the film-substrate orientation relationship is maintained irrespective of the substrate surface on which the film is grown, is described, and this is compared with those cases where multiple DRs may be favored resulting on the dependence of the OR on the substrate surface. Finally, the physical basis of the model is described in terms of the energy minimization of adatoms deposited on a rigid substrate.
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11:10 am STRUCTURAL CHARACTERIZATION AND MODELING OF THE ALUMINUM {111}1 SAPPHIRE (0001) HETEROPHASE INTERFACE: DL Medlin, K.F. McCarty, R.Q. Hwang, J.E. Smugeresky, T. Tsuji and M.l. Baskes, Sandia National Laboratories, Livermore CA 94551; Shizuoka University, Jyoohoku 3-5-1, Hamamatsu 432, Japan We are investigating AllAFO' interface structure using thin films fabricated by deposition of aluminum from an effusion source onto (0001) sapphire under UHV conditions. Structural considerations suggest that the metal would grow to match the close-packed metal planes and directions with the closepacked oxygen ions ofthe sapphire substrate, i.e., (OOOI)AI'O'1I (Ul) metal and [1O-lOlAI'O' II [-11 Olmetal. Although this orientation is predominant, transmission electron microscopy observations also show the existence of two additional types of orientation relationship, corresponding to rotations of 30 degrees and -II degrees from the primary domain orientation. A comparison of the predictions of atomistic calculations for the interface structure and dislocation configuration with the results of high resolution and conventional transmission electron microscopy observations will be presented. This work is supported by the U.S. DOE under contract DE-AC04-94AL85000. 11:30 am INVESTIGATION OF THE BONDING CHANGES ASSOCIATED WITH GRAIN BOUNDARY EMBRITTLEMENT: V.l. Keast, J. Bruley, D.B. Williams, P. Rez', Department of Materials Science and Engineering, Whitaker Lab #5, Lehigh University, Bethlehem PA 18015; *Center for Solid State Science and Department of Physics, Arizona State University, Tempe, AZ 85287-1704 Grain boundary embrittlement by impurity or alloying elements is a common and technologically important phenomenon, of which the embrittlement of Cu by Bi is a classic example. Investigations, using the near edge fine structure in the electron energy loss spectrum (EELS), have indicated that there is a change in bonding at the grain boundaries associated with the segregation ofBi. Namely, there is a decrease in the density of the d states for Cu atoms at the boundary when Bi is present. The effect of variations in grain boundary misorientation on the Bi segregation levels and on the near edge structure will be described. Comparisons between results from EELS and x-ray photoelectron spectroscopy (XPS) will also be made. (Supported by NSF (DMR 93-0625)
8:30am SCIENCE & TECHNOLOGY POLICIES FOR DEVELOPMENT: An International Overview: Dr. Krishan Rajan, Rensselaer Polytechnic Institute, Materials Engineering Department, MRS-UO, Troy, NY 12180-8554 In the presentation we provide an overview of the role changing political structures and its influence on science and technology policies. Specific issues of the role of the private sector in different types of economies are from the role of multinational corporations to state owned enterprises. The different roles played by industry in these counties in promoting cooperation among the different sectors in science and technology policy are examined. 9:00am COMPETITIVE TECHNOLOGY DEVELOPMENT: STRATEGIC PARTNERSHIPS WITH UNIVERSITY AND GOVERNMENT: Michele Migliuolo, Vice President of Technology, Kurt J. Lesker Company, 1515 Worthington Avenue, Clairton, PA 15025 Product development in a growing small business can be difficult due to lack of internal expertise or facilities. Often technology is not developed due to an apparent lack of appropriate resources. We discuss the long standing and on-gong strategic technology transfer programs at the Kurt J. Lesker Company. We leverage financial resources (internal, government, customer) with technical resources (internal, university, customer), to develop new products and processes which are more effectively manufacturable. Our research programs serve to establish us as a manufacturer of exceptional deposition systems and component, and as an engineering firm with the knowledge which a manufacturer of devices and systems requires. It is the combination of our deposition systems and process technology which will ensure that this firm is regarded as a world leader in materials science. By allowing our company to perform research and development efforts which we would not have otherwise undertaken, our funding sources thus contribute to business growth, direct company growth, academic research, education of graduate students and researchers, and local economic growth as a result of increased employment. 9:30am THE ATTRACTION OF UNIVERSITY CONSULTANCY SERVICES FOR INDUSTRIAL COMPANIES: Dr. Brian Mellor, Manager, Engineering Materials Consultancy Service, University of Southampton, Southampton S017 IBJ, UK 10:00 am BREAK
SUCCESSFUL UNIVERSITY-INDUSTRY LINKAGES FOR A GLOBAL ECONOMY Sponsored by: TMsnnternational Activities Committee Program Organizers: Dr. Krishna Rajan, Rensselaer Polytechnic Institute, Materials Engineering Department, MRS-11 0, Troy, NY 12180-8554; Dr. Arthur Willoughby, Southampton University, Eng. Materials Dept., Hants, Southampton S017 1BJ, UK; Dr. Chris Bickert, North American Rep., Tech Transfers, Aluminum Pechiney, Mamaroneck, NY 10543; Prof. Akio Sasaki, Kyoto University, Dept. of Electronic Sci & Engr, Kyoto 606-01, JAPAN Monday, AM February 10, 1997
Room: 3400 Location: Orlando Convention Center
Session Chairperson: Dr. Krishna Rajan, Rensselaer Polytechnic Institute, Materials Engineering Department, MRS-110, Troy, NY 12180-8554
8:25 am INTRODUCTION: Dr. Krishna Rajan, Rensselaer Polytechnic Institute, Materials Engineering Department, MRS-llO, Troy, NY 12180-8554
10:15 am TITLE TBA: Dr. David Edmonds, Head of Materials, Leeds University, School of Materials, Leeds LS2 9JT 10:45 am TITLE TBA: Prof Guilemany, University of Barcelona, Department de Enginyeria Quimica, I Metal.lurgia, Calle Marti I Franques, I, 08028 Barcelona, Spain 11:15 am TITLE TBA: Dr. L. Delaey, K.U. Leuven, Dept. MTM, Ce eCroylaan 2, 3001 Heverlee, Belgium
fraction of IMI834 and MMC, but here the MMC is in the middle of the laminate. Bonding parameters: temperature, pressure and time have been optimised. Effective Young's Modulus and bend strength have been imestigated using four-point bend tests, and impact fracture toughness of the laminates and control samples have been assessed by using an instrumented impact testing. For un-notched specimens, 100% IMI834 has highest fracture toughness with lowest E and strength; MMC, in contrast, has higher strength and lowest fracture toughness. However, for notched specimens, both of them have lower strength and fracture toughness compared with the S-type laminate. The measured stiffness (E) for the S-type laminate was greater than that for IMI834 by about 1.7. By laminating materials, the impact fracture toughness of S-type laminate for un-notched and notched specimens, compared with 100% MMC material, increased by about 2.7 and 4.6. Young's modulus strength, and fracture toughness can be optimised by selecting different structures. Lamination by combining tough matrices and reinforced components is an effective way to improve toughness for high strength materials, like MMC, and the properties of the materials can be tailored according to a particular application.
SYNTHESIS OF LIGHT-WEIGHT METALLIC MATERIALS II: Metallic Composites I Sponsored by: MSD Synthesis/Processing Committee Program Organizers:C.M. Ward-Close, Structural Materials Center, R50 Building, Defense Research Agency, Famborough, Hampshire, GU14 6TD, United Kingdom; F.H. Froes, University of Idaho, Institute for Materials and Advanced Processes, Mines Bldg 204, Moscow, ID 83844-3026; D.J. Cheliman, Lockheed Aeronautical Systems Co., Lockheed Corporation, Marietta, GA 30063-0150; S. S. Cho, Vice President of Rapidly Solidified Materials Research Center, (RASOM), Chungnam National University, Taedok Science Town, Taejon 305-764 Korea
Monday, AM February 10, 1997
Room: 330F Location: Orlando Convention Center
Session Chairpersons: F.H. (Sam) Froes, University of Idaho, Institute for Advanced Processes, Mines Bldg 204, Moscow, 10 83844-3026; D. Cheliman, Lockheed Aeronautical Systems Co., Lockheed Corporation, Marietta, GA 30063-0150
9:40am PROCESSING OF TilSiC COMPOSITES: A COMPARATIVE STUDY OF THE FOIL-FIBRE-FOIL AND THE TAPE-CASTING TECH· NIQUES: Zheng Xiao GUO, Department of Materials, Queen Mary and Westfield College, University of London, Mile End Road, London EI 4NS, UK
8:30am RECENT ADVANCES IN THE SYNTHESIS OF LIGHT WEIGHT METALLIC MATERIALS: c.M. Ward-Close l , F. H. Froes 2, and S.S. Cho', !Chief Metal Matrix Composites, Structural Materials Centre, DRA Farnborough. Hampshire GUl4 6TD. UK; 2Director IMAP, University of Idaho, Moscow, Idaho 83844-3026; 3Lockheed Technical Fellow, Advanced Structures and Materials, Lockheed Aeronautical Systems Co., Marietta, Gorgia 30063; 'Vice Director of RASOM, Rapidly Solidified Materials Research Center, Chungnam National University, Taedok Science Town, Taijon 305-764, Korea
Ti-based SiC fibre reinforced composites are strong, stiff and light-weight materials for high temperature applications up to 700-1 OOO°C. As with any other advanced materials, their development has to overcome both economic and technical hurdles. Here, a study into the foil-fibre-foil and the tape-casting processing techniques is reported. The fundamental procedures invol ved in the techniques are compared and discussed. Possibilities of reducing product costs are analysed. Due to the reactive nature of titanium, the composites must be processed under minimum thermal exposure to reduce undesirable fibre/matrix interfacial reactions: on the other hand, care should also be taken not to use too Iowa temperature or too large a pressure in order to avoid fibre breakage. This requires an optimum balance of the processing temperature, pressure and time. Therefore, both theoretical and experimental investigations were conducted for the consolidation of aligned fibre mats with matrix foils or with matrix pOWder-tapes. The effects of processing parameters, such as temperature pressure and time, on the mechanisms of identification are evaluated. Predictions of the process model are compared with experimental findings, which shows satisfactory agreement. Various types of interfacial defects and fibre breaking have been analysed in relation to the processing parameters and fibre/matrix lay-ups. Consequently, defect- and reaction- free composites have been obtained. This is particularly successful with the assistance of a temporary hydrogenation procedure using either pre-hydrogenated foils or powder particles during processing.
Recent advances in the synthesis of light-weight metallic materials will be reviewed with emphasis on developments which have occurred since the last symposium in this series. Primary consideration will be given to alloys based on aluminium, magnesium and titanium both in monolithic and composite configurations. Emphasis will be on synthesis/processing/fabrication rather than the more traditional microstructure-mechanical property relationships. Particular attention will be given to the status of commercialisation of high performance light-weight metallic materials. 9:00am HYDROGEN STORAGE WITH MAGNESIUM-IRON NANOCOMPOSITES: M.A. Imam, Materials Science and Technology Division, Code 6323, US Naval Research Laboratory, Washington, DC 20375; R.L. Holtz, Geo-Centers, Inc., 10903 Indian Head Highway, Fort Washington, MD 20744 Of potential practical hydrogen storage materials (HSM), pure Mg would be best from the standpoint of hydrogen capacity per unit mass. However, pure Mg has poor hydrating reactivity due to surface oxide poisoning and low catalytic activity. Mg-Ni is a well-known attentive that is more stable against oxidation. The Ni aids catalysis of the H2 dissociate chemisorption and produces additional benefits by lowering the dehydrogenation temperature, but at the expense of a decrease in storage capacity. Theoretical considerations suggest that nanostructured Mg with low concentrations of both Ni and Fe will be an optimum Mg-based HSM. We have prepared submicron Mg-(Ni,Fe) pseudoalloys by bail milling and report here on the hydrogen storage characteristics.
10:00 am BREAK 10:20 am CHARACTERISATION OF SIGMA SiC FIBREITITANIUM ALLOY MMCS FABRICATION BY PLASMA SPRAYING AND FOILIFIBRE METHODS: A.M. Baker; P.S. Grant, M.L. Jenkins, C.M. Ward-Close, Z. Fan, B Cantor ,OCAMAC, Department Of Materials University of Oxford, Parks Road, Oxford OXI 3PH, UK A new process for vacuum plasma spray manufacturing of multi-ply Titanium/SiC fibre MMC rings has been developed. Material produced can be identified easily by subsequent vacuum hot pressing or HIP. Ti and Ti-6Al4V matrices have been 'spray-wound' with C coated and CmBx coated DRA Sigma SiC fibres. Characterisation by electron microscopy has identified interfacial reaction products, showing that the fibre/matrix reaction is similar to that for plasma sprayed monotapes. SiC fibres chemically extracted from the matrix have been subjected to tensile and bend testing to quantify process damage for spray-wound and foil/fibre material. This has shown that fibre damage from spray/winding is of a similar magnitude to that from foil/fibre processing. Possible mechanisms for fibre damage during processing have been identified.
9:20am PROCESSING AND PROPERTIES OF TITANIUM AND TITANIUM METAL MATRIX COMPOSITE BASED LAMINATES: Y.Q. Zuo, DJ. Smith, P.G. Partridge!, A. Wisbey2 Department of Mechanical Engineering lInterface Analysis Centre, University of Bristol, UK; 'Structural Materials Centre, DRA Famborough, UK Two laminate systems based on titanium alloy IMI834 and titanium metal matrix composite (MMC) have been manufactured by diffusion bonding. The S-type laminate contain 50% MMC in the outside layers and 50% Vol. IMI834 in the middle of the laminate. The C-type laminate contains the same volume
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10:40 am CONSOLIDATION OF CONTINUOUS SiC/Ti-6AI-4V MATRIXCOATED FIBRE METAL MATRIX COMPOSITES: S. Schuler, B. Derby, MJ. Wood, C.M. Ward-Close', Oxford Centre for Advanced Materials and Composites, OCAMAC, Department of Materials, University of Oxford, Parks Road, Oxford, OXI 3P; Structural Materials Centre, Defence Research Agency, DRA, Farnborough Hampshire, GU14 6TD, UK
reaction barrier concept developed for titanium metal matrix, composites including those based on y- TiA 1. The newly developed coating system, designated FUWT'. consists of GdlGdB3 where the Gd layer (adjacent to SiC) works as a compliant layer while the GdB3 layer works as a reaction barrier. The results of this work indicate that the FUWT coating perform well both a reaction barrier (protect the SiC fibre from reactions with titanium up to 100°C) and a compliant layer (absence of thermal cracking in AiAI based composite). The interfacial shear strength of an as-fabricated SiCIFUWTlTi-6AI-4V was found to be higher than the presently available SCS6ITi-6AI-4V and Sigma (SMI240)ITi06AI-4V composites. 'From the surnames of the four co-inventors: Froes, Upadhyaya, Ward-Close and Tsakiropoulos.
The consolidation of continuous matrix-coated fibre Metal Matrix Composites, MMC, has been investigated using a theoretical as well as an experimental approach. A numerical, quantitative model has been developed for the solid-state consolidation of continuous Matrix-Coated Fibre, MCF, Metal Matrix Composites. In addition, an experimental verification programme was conducted using two different samples types, one produced under normal conditions and one containing yttrium maker layers. The marker layers were used to make the matrix deformation visible, which occurs during the consolidation, and hence offered the opportunity of a direct comparison of the predicted matrix deformation and the experimentally determined matrix deformation. The materials investigated were continuous Textron SCS-6 SiC fibres in a Ti-6AI-4V metal matrix. The fabrication route chosen was the Matrix-Coated Fibre method, developed by the DRA Farnborough, UK. In this method, the fibres are pre-coated prior to consolidation with the matrix material using Electron Beam Evaporation, a Physical Vapour Deposition technique. The thickness of the matrix-coating and hence the final fibre volume fraction of the composite can easily be varied by adjusting the coating time. For the consolidation to the final composite the matrix-coated fibres are stacked, degassed placed into a titanium container and hot-isostatically pressed. The analytical model is based on a Finite Element Model, FEM.
11:20 am THE MANUFACTURE OF Ti ALLOY/SiC FIBRE COMPOSITES BY A NEW SPRAYIWIND PROCESS: Z.Y. Fan, P.S. Grant, B. Cantor, Department of Materials, Oxford University, Parks Road, Oxford OXI 3PH, UK. This paper describes a new method of manufacturing Ti alloy/SiC fibre reinforced composites. Three dimensional hoop reinforced rings, cylinders and tubes are being manufactured by concurrent plasma spraying of titanium alloy and mechanical winding of SiC or other reinforcing fibres or wires. The paper will outline the manufacturing process concentrating on the range of geometry's which can be manufactured, and will discuss the variety of microstructures which can be achieved.
11:40 am SYNTHESIS AND PHASE EQUILIBRA IN TiB, PARTICLE REINFORCED IDGH MODULUS STEEL: Kouji Tanaka, Tadashi Oshima and Takashi Takashi Saito, Toyota Central R&D Labs, Inc., 41-1 Yokomichi, Nagakute, Aichi, 480-11, JAPAN
l1:00am RECENT ADVANCES IN FIBER COATING TECHNOLOGY FOR USE IN SiC/Ti-MMCs: D Upadhyaysl, P. Tsakiropoulos 2, and F.H.Froes l• Institute for Materials and Advanced Processes, University of Idaho, Moscow, ID 83844-3026'; Department of Materials Science and Engineering, University of Surrey, Guildford, Surrey, GU2 5XH, UK: Structural Materials Centre, DRA Farnborough, Hants GUl4 6TD, UK
This paper describes the synthesis of high modulus steel for automobile parts with an emphasis on its alloy-designing concept and phase eqUilibrium. Titanium diboride (TiB2) particles have been verified to be the best reinforcement for improving isotropic Young's modulus of steels. The calculated phase diagram shows that TiB2 has a narrow tow-phase equilibrium window with carbon-free Fe-Cr-Ti ferric steel and has neither solubility of iron nor chromium. Those thermo-dynamical stability's ofTiB2 are responsible for maintaining its own high Young's modulus of 540GPa in the ferocity steel. Both pre-mixed and in-situ TiB2 particles effectively reinforced the ferocity steel matrix. The developed steel with 30vol.%TiB2 showed a Young's modulus of 280GPa which apparently corresponded to 350GPa due to its reduced density of 6.6g/cc compared with 7.8g1cc of the conventional steel.
Continuous silicon carbide fibre-reinforced titanium-based metal matrix composites offer many advantages over conventional monolithic materials including high strength-to-density ratio. However, there is a need to design an improved protective coating for the silicon carbide fibre to combat interfacial chemical reactions as well as to accommodate large mismatch in the coefficient of thermal expansion (CTE) between the SiC fibre and titanium matrix. This paper describes the strategy for designing coating for continuous silicon carbide fibre and reports on a new coating system based on a compliant layer/
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conditions required for this behavior in the presence of energetic ions. Mo films were sputter deposited on amorphous substrates and grown to a large variety of thickness. The homologous temperature does not exceed 0.2 in any of the experiments performed. These films were characterized by a large battery of synchrotron x-ray, electron microscopy, and surface analysis. The data have led to an atomistic model to explain and predict the in-plane texturing based on shadowing and anisotropic growth rates which force a competitive grain growth mechanism during the growth. Detailed comparison to experiment will demonstrate the role that limited diffusion and mass transport play in the final microstructure of the film. Examples of how this model can be exploited to design a particular microstructure will be presented.
ADVANCES IN COATINGS TECHNOLOGIES II: SESSION II Sponsored by: MDMD Surface Modification & Coatings Technology Committee Program Organizers: C.A. Clayton, State University of New York at Stonybrook, College of Engineering and Applied Sciences, Stony Brook, NY 11794-2200; J.K. Hirvonen, US Army Materials Technology Lab., Arsenal St., Watertown, MA 02172; A.A. Srivatsa Monday, PM February 10, 1997
Room: 315B Location: Orlando Convention Center
3:15pm CERAMIC-METALLIC COATINGS BY ELECTRON BEAM PHYSICAL VAPOR DEPOSITION PROCESS: Douglas Wolfe, M. Movchan, Jogender Singh, Applied Research Laboratory, Pennsylvania State University, University Park, PA 16804
Session Chairperson: TBA
1:30pm OXIDE AND NITRIDE SUPERLATTICE COATINGS: William D. Sproul, BIRL, Northwestern University, 1801 Maple Avenue, Evanston, IL 60201
Electron beam physical-vapor deposition (EB-PVD) process is considered to be a cost-effective and robust coating technology that has overcome some of the difficulties or problems associated with the metals spray, CVD and PVD processes. The EB-PVD process offers many desirable characteristics such as relatively high deposition rates (up to 100-500 mmlminute with an evaporation rate - 10-15 Kg/hour), dense coatings, precise composition control, columnar and poly-crystalline microstructure, low contamination, and high thermal efficiency. Various metallic and ceramic coatings (oxides, carbides, nitrides) have been deposited at relatively low temperatures. EB-PVD has the capability of producing multilayered nanolaminated metallic/ceramic coatings on large components by changing the processing conditions such as ingot composition, part manipulation, and electron beam energy. Attachment of an ion beam source to the EB-PVD process offers additional benefits such as dense coatings with improved adhesion.
Over the past 10 years, three major advances in reactive sputtering technology have made it possible to deposit both conductive and non-conductive fully-dense films at high rates. These three advances are unbalanced magnetron (UBM) sputtering, partial pressure control of the reactive gas, and pulsed DC power. Multicathode UBM sputtering systems provide a dense secondary plasma that produces well-adhered, fully dense films. With both pulsed-dc power and partial pressure control, films such as aluminum oxide can now be deposited reactively at rates up to 78% of the pure metal rate. The reactive UBM sputtering process is used to deposit polycrystalline nitride superJattice films such as TiN/NbN or TiNNN with hardnesses exceeding 50 GPa, - more than double the hardness of either component in the film. The nitride superJattice work is being extended to oxide films. Clear, amorphous, nanolayered AI2031Zr02 films have been deposited at high rates with a hardness of 10 GPa. Work is underway to deposit these films in a crystalline form, which should enhance their hardness.
3:50 pm BREAK 4:05pm COMMERCIAL APPLICATIONS OF PLASMA SOURCE ION IMPLANTATION: J.T. Scheuer, K.c. Walter, Los Alamos National Laboratory, Los Alamos, NM; w.G. Home, Empire Hard Chrome, Chicago, IL; R.A. Adler, North Star Research Corporation, Albuquerque, NM 87109
2:05pm CONTROL OF INTERFACE STRENGTH IN NIOBIUM-ALUMINUM OXIDE MULTILAYERS BY ION BEAM ASSISTED DEPOSITION: G S. Was, H. Ji, J.W. Jones, Cooley Bldg., University of Michigan, Ann Arbor, MI 48109; N. Moody, Sandia National Laboratory, Div. 8712, MS 9403, Livermore, CA 94551
Commercial plasma source ion implantation (PSII) equipment built by North Star Research Corporation has recently been installed at Empire Hard Chrome, Chicago, IL. Los Alamos National Laboratory has assisted in this commercialization effort via two Cooperative Research and Development Agreements to develop the plasma source for the equipment and to identify low-risk commercial PSII applications. The PSII system consists of a 1m x 1m cylindrical vacuum chamber with a pulsed, inductively coupled rf plasma source. The pulse modulator is capable of delivering pulses with peak currents of 100 kV and peak currents of 300 A at maximum repetition rate of 400Hz. The pulse modulator uses a thyratron to switch a pulse forming network which is tailored to match the dynamic PSII load. This presentation will focus on early commercial applications to production tooling and manufactured components and characterization of implanted coupons.
The toughness of a niobium-aluminum oxide multilayer depends on the interface strength, which can be controlled by both the orientation relationship of the constituents and the composition at the interface. As a first approximation to multilayers, niobium films were deposited onto (OOOl) sapphire substrates by ion beam assisted deposition (!BAD) under various conditions. In addition to the (110) fiber texture, strong in-plane texture was introduced by simultaneous ion bombardment. Stronger in-plane texture was developed with higher ion energy and ion to atom arrival rate ratio (R ratio). Different orientation relationships at the niobium-sapphire interface were achieved by varying the orientation of the sapphire substrates with respect to the ion beam incident direction. The hardness and modulus of the niobium layer were also modified by the ion bombardment. A dopant (Ag) was introduced at the interface at levels from a fraction of a monolayer to one monolayer during niobium layer deposition.
4:40pm SPUTTERED CHROME NITRIDE AS AN ALTERNATIVE TO ELECTROPLATED CHROME: Michael Graham, Keith Legg, Paul Rudnik, Peter Chang, BIRL, Northwestern University, Evanston IL 60201
2:40pm CONTROLLING THE EVOLUTION OF TEXTURE IN SPUTTER DEPOSITED Mo FILMS: S.M. Yalisov, J.C. Bilello, University of Michigan, Department of Materials Science and Engineering, Ann Arbor MI 48119
BIRL has been involved in hardcoating development for engineering applications for several years. A major effort over the past four years has focused on the replacement of electroplated chrome in applications where the steel substrates have moderate hardnesses (Rc38-42) and therefore only modest support for hard PVD coatings. Much of the development work has been supported by the government through DARPA as part of an environmental thrust to eliminate pollution sources and health hazards from their OEM's as well as their repair facilities. BIRL has developed the use of duplex processing (plasma nitriding + sputter-coating) and thick PVD coating (15-20um) with CrN and demonstrated wear performance characteristics superior to com-
Evolution of crystallographic ordering in sputter deposited polycrystalline refractory metal films has been observed in several laboratories. While the ordering in the growth direction, out-of-plane texture, is well known, the ordering in the plain of Growth, in-plane texture, has only been reported by the ion enhanced growth community. The work presented here, will describe the
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mercial chrome plating. This paper reviews some of the process developments involved in these programs and the wear test results. Production cost estimates have also been conducted for certain components, and it has been demonstrated that PVD coating is competitive with electroplating when the total manufacturing process is taken into account.
grating, pinning, failing a runner, and healing, all with respect to the detailed local microstructure of the runners. Here we will report and describe how grain boundaries dramatically influence almost all aspects of EM-induced void and failure dynamics in submicron runners. We also find a striking change in EM-mechanism as a function of temperature in the range 200 - 300°C. Studies as a function of linewidth and passivation state were also performed. Our findings have important implications for both electromigration modeling and conventional reliability testing.
5:00pm CHARACTERISTIC OF TiN FILM DEPOSITED ON STELLITE USING REACTIVE MAGNETRON SPUTTER ION PLATING: Whungwhoe Kim, Joungsoo Kim, Surface Treatment Group, KAERI, Taejon, Korea, Mingu Lee, Heesoo Kang, Wonjong Lee, Dept. of Materials Science, KAIST Taejon, Korea
3:00 pm INVITED DOPANT ACTIVATION OF HEAVILY-DOPED Si BY HIGH CURRENT DENSITY: 1.S. Huang K. N. Tu, Department of Materials Science & Engineering, UCLA, Los Angeles, CA 90095-1595
TiN films were deposited onto stellite 6B alloy (Co base) by the reactive magnetron sputter ion plating. As the substrate bias increases, TiN film changes from colunmar structure to dense structure due to densification and resputtering by ion bombardment. Oxygen, the major impurity, is decreased greatly when the substrate bias is applied. The preferred orientation of the TiN films changes from (200) to (111) with decreasing N21Ar ratio. The change of the preferred orientation is discussed in terms of surface energy and strain energy which are related with the impurity contents and the ion bombardment damage. The hardness of the TiN film increases with increasing compressive stress generated in the film by virtue of ion bombardment.
Novel dopant activation in the heavily boron-doped p+-Si was created by applying an electrical current of high current density. The heavily boron-doped p+-Si was obtained by ion implantation and annealed at 900° C for 30 min to achieve a partial boron activation. For additional activation, we gradually applied current until a current density of 2.5xlOE7 Ncm 2 was reached. The resistance of the p+-Si responded by a gradual increase, then it decreased with a precipitous drop. The resistance was reduced by a factor of 5 to 18. Mechanisms of the novel dopant activation will be proposed. Dopant activation in the heavily arsenic-doped n+ -Si will also be discussed. 3:30 pm BREAK
ADVANCES IN ELECTRICALLY CONDUCTIVE MATERIALS II
3:50 pm INVITED DEVELOPMENT OF LOW THERMAL-EXPANSION, HIGH-CONDUCTIVITY ALLOYS BASED ON THE Cu-Fe-Ni TERNARY SYSTEM: R.D. Cottle, R.K. Jain, C.c. Hays, Z. Eliezer, L. Rabenberg, Center for Materials Science and Engineering, The University of Texas at Austin, Austin, TX 78712; M.E. Fine, Northwestern University, Evanston, IL 60208
Sponsored by: EMPMD Electronic Packaging and Interconnection Materials Committee Program Organizers: S. Jin, Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974; M.E. Fine, Northwestern University, Evanston, IL 60208;K. N. Tu, UCLA, Los Angeles, CA 90095 Monday, PM February 10, 1997
The FCC phase in Cu-Fe-Ni ternary system contains a miscibility gap within which tie-lines extend from nearly pure Cu toward the Invar composition, Fe - 36% Ni. This suggests that it should be possible to prepare alloys containing isotropic distributions of Invar within high conductivity, Cu-rich, matrices, and that the Invar fraction can be controlled by selecting starting compositions at various points along the tie line. The resulting combinations of low thermal expansion with high electrical and thermal conductivity will be of interest in the electronic circuit packaging industry. Technical difficulties in developing such alloys arise from incomplete solid solubility at high temperatures at the Cu-rich end of the series and from the slow approach to complete chemical phase separation at low temperatures. Quaternary element additions and mechanical deformation processes are being explored as approaches to creating more nearly homogeneous starting alloys. Microstructural developments and electrical and thermal properties will be reported and discussed.
Room: 340B Location: Orlando Convention Center
Session Chairperson: M.E. Fine, Northwestern University, Evanston, IL 60208
2:00 pm INVITED TRANSITION METAL CARBIDES AND NITRIDES FOR ELECTRONIC DEVICES: Wendell S. Williams, Department of Physics, University of Illinois, Urbana, IL 61801 The need for thermally stable, diffusion-resistant but electronically conducting materials for interconnects in ultra large scale integrated circuits has led to the successful application of transition metal carbides and nitrides, particularly TiN. Another application is the use of superconducting NbN to make Josephson junctions - NbN/SilNb and NblMgOlNbN. And high-temperature resistors with nearly zero temperature coefficients have been made from TaN. This family of materials, sometimes called "metallic ceramics," can be deposited as thin films by several processes, including reactive sputtering, metal-organic chemical vapor deposition and plasma-assisted chemical vapor deposition. An interesting but potentially troublesome characteristic of these NaCl-structured materials is their wide range of deviation from stoichiometry, involving many percent random atomic vacancies, scattering centers for conduction electrons. Hence film preparation requires that the non-metal! metal ratio be close to unity. It is not widely recognized that these defectridden crystal structures are non-equilibrium phases: when cooled slowly from high temperatures, some develop ordered phases with lower resistivities.
4:20pm PROCESS OPTIMIZATION OF HIGH-STRENGTH, HIGH-CONDUCTIVITY Cu-Cr IN-SITU COMPOSITE: H. G. Suzuki, K. Adachi, S. Tsubokawa, T. Takeuchi, National Research Institute for Metals, 1-2-1 Sengen, Tsukuba 305, Japan High-strength, high-conductivity Cu-Cr in-situ composites were developed through the optimization of various process variables. Ingots were obtained by vacuum induction melting. Dendritic Cr was in-situ precipitated during solidification. After hot forging and solution treatment at 1000°C, repeated cold working was performed to get fine lamellar spacing of single crystalline Cr second phase. The analysis of microstructure by TEM showed dynamic recrystallization of Cu matrix and fine distribution of Cr precipitates. These structures give the strength level of 900 MPa and relative conductivity, lACS, of 78%. The mechanism of high strength and high conductivity will be discussed.
2:30 pm INVITED ELECTROMIGRATION IN SUBMICRON AI-0.5%Cu INTERCONNECTS FOR SILICON ULSI: I.A. Prybyla, S.P. Riege, A.W. Hunt, Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974 Systematic studies of the influence of local microstructure on electromigration (EM) dynamics in submicronAl(O.5 wt % Cu) interconnects were performed using in-situ transmission electron microscopy (TEM) techniques. This approach has allowed us to observe in real-time voids forming, growing, mi-
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4:40pm THE CHARACTERISTICS OF ELECTRICAL CONDUCTIVITY AND PRECIPITATION OF Cr BY AGING IN Cu-Cr IN-SITU COMPOSITE: f. Yan, H.G. Suzuki, National Research Institute for Metals, 1-2-1 Sengen, Tsukuba 305, Japan
retrofitted into the existing facility. This multi-national team utilizing state of the art modeling and process control technology, successfully designed and implemented a twelve pot test section at Nadvoitsy. Cell performance measured over twelve months has consistently exceeded minimum design indices and paces world class cell performance. Measurements of magnetic field, heat flow, and voltage distribution compare closely with predicted values. Design features, including a novel six anode superstructure, design methodology, test protocol, construction and operation practices, and cell performance data are presented in this paper.
Aging treatment is one of the most important materials processing techniques for obtaining high electrical conductivity in Cu in-situ composite. In this work, we systematically investigated the effect ofCr precipitation on electrical conductivity ofaCu-15 wt % Cr in-situ composite, by means of aging treatment, electrical conductivity measurement, scanning electron microscopy, analytical electron microscopy, high resolution electron microscopy and X -ray lattice parameter measurement. The optimum aging condition for obtaining peak electrical conductivity has been determined. In addition, it is found that an appropriate amount of cold working can further enhance the electrical conductivity of the composite. The related mechanism has also been studied.
2:50pm BATH TEMPERATURE MEASUREMENTS WITH THERMOCOUPLES: Paul Verstreken, Heraeus Electro-Nite Int. N.V., Grote Baan 27a, 3530-Houthalen, Belgium After a brief introduction into the physical principles of thermoelectricity an overview of commonly used thermocouples is given. The construction of thermocouple sensors and assemblies is discussed. An overview of calibration procedures is given. Errors can arise from the materials (thermocouple wires and sheathing) used, and the way the actual measurement is performed. Reasons for drifting are discussed. There is a relation between the thermal properties (thermal mass and heat conductivity) of the sheathing material, the measuring procedure and the obtained accuracy of the temperature measurement. From this, recommendations on how to improve the quality of bath temperature readings, are made.
ALUMINIUM REDUCTION TECHNOLOGY II: Soderberg, Equipment Sponsored by: LMD Aluminum Committee Program Organizer: Harald A. 0ye, Institute of Inorganic Chemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway MondaY,PM February 10, 1997
Room: 230A Location: Orlando Convention Center
3:15 pm BREAK 3:35pm A NEW INSTRUMENT FOR FAST TEMPERATURE MEASUREMENT IN ALUMINIUM REDUCTION CELLS: Fucang Xu, fie Li, Huazhang Wang, Yexiang Liu, Department of Metallurgy, Central South University of Technology, Changsha, Hunan 410083, China
Session Chairpersons: Alton T. Tabereaux, Reynolds Metals Company, Manufacturing Technology Laboratory, 3326 East 2nd Street, Muscle Shoals, AL; Peter Polyakov, Light Metals Department, Non-ferrous Metals Academy, Krasnoyarsk sabochiy SI. 95, 660025, Krasnoyarsk, Russia
A new instrument, with a single-chip microcomputer as its core and based on a new method named Dynamic Temperature Measurement, has been developed for fast temperature measurement in aluminium reduction cells. When a cold thermocouple is inserted into hot electrolyte, the instrument measures the thermocouple output curve and meantime identifies the parameters of a time series-analysis model which is used to describe the temperature-time curve. Until the convergence of the identification is verified, the instrument predicts the temperature of the electrolyte from the obtained information. In the way, the temperature can be indicated before the thermocouple output reaches its balance point, with the measurement process lasting only some 50 seconds and measurement accuracy reaching ±2°C, a range acceptable for industrial measurement.
2:00pm IMPLEMENTATION OF POINT FEEDING IN THE SODERBERG LINES AT HYDRO ALUMINUM KARMOY: Knut Arne Paulsen, Willy K. Rolland, Asbj¢m Larsen, Hydro Aluminum a.s, Karm¢y Plants, N-4265 H?lVik, Norway; Marvin Bugge, Norsk Hydro a.s, Research Centre, N-3901 Porsgrunn, Norway A concept for point feeding of alumina to S¢derberg cells has been developed at Hydro Aluminum Karm¢y. During 1996 and early 1997 the bar breaker equipment on all 340 cells will be replaced by point feeders. Alumina is fed by means of a fluidized feeder and mechanically forced into the bath. The lifetime of the equipment is comparable to that of the cathode life. The concept has proved to stabilize the operation of the cell. Furthermore, the stability improves the current efficiency and also allows the amperage to be increased. Implementation of point feeding includes revised operational procedures and new target values for the operational parameters and also affects the organization. The anode effect frequency has been reduced in several steps during the development period. Today, the anode effect frequency is about one tenth of the corresponding value for the previous bar breaker cells resulting in reduction of perfiuorocarbon emissions.
4:00pm A DEVICE FOR CONTINUOUS ALUMINA FEED INTO AN ALUMINIUM ELECTRIC CELL: A. I. Begunov, E.V. Kudryavtseva, State Technical University, Lermontov Str. 83, Irkutsk, Russia A new device is suggested here to cover the cell and feed alumina into it. The covering is designed having such thermal resistance that no crust develops on the electrolyte surface. Alumina is fed from the intermediate hopper, which is one piece with the covering plate, into the electrolyte through the narrow slot, the width of which ranges from 0.8 to 1.2 mm. The alumina feed rate is determined by its bulk properties ("sandy", "mealy", "moist"), the width and length of the slot and the intermediate hopper wall flare angle. The cold model of the device yielded the dependencies of alumina slot spead on the parameters mentioned above. The device has no crust-breaking appliances or volumetric dosers. Dosage is effected only to gravity feed of raw materials through a slot of predetermined cross-section. Because of that, low operation costs and high reliability of the suggested device are expected.
2:25pm A UNIQUE, ECONOMIC SODERBERG TO PREBAKE CONVERSION FOR THE RUSSIAN ALUMINIUM INDUSTRY: S. Tsymbolov, G. Necheav, Nadvoitsky Aluminium Smelter, Zavodskaya Street, 1, Nadvoitsy, 186430, Karelia, Russia; Lee E. Swartling, Kaiser Aluminum Technical Services, Inc. 6177 Sunol Boulevard, Pleasanton, CA 94566; G. Volfson, AllRussian Aluminium & Magnesium Institute, 86 Sredny Prospect, St. Petersburg, 199026, Russia The majority of Russian aluminum smelting technology is S¢derberg, historically associated with non-competitive performance and ecological problems. After conversion to conventional prebake cell technology was found economically unjustifiable, the Nadvoitsky Aluminium Smelter, Karelia, Russia commissioned the All-Russia Aluminium and Magnesium Institute and Kaiser Aluminum Technical Services Inc. to design a unique prebake technology cell with world class performance which could be economically
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4:25pm VISUALISATION OF TAPPING OPERATIONS: Marcus Walker, Comalco Research Centre, P.O. Box 316, Thomastown, Australia 3074 The removal of molten aluminium from Hall- Heroult cells is known a "tapping". This operation causes process disturbances including entrainment of electrolyte and sludge in the tapped metal as well as producing localised wear
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of the cathode. This paper describes the use of a full scale physical model for determining the optimal tapping conditions to reduce both bath entrainment and cathode erosion for various cell operating strategies. Flow visualisation and numerical modelling has shown that the flow towards the tapping pipe is predominantly radial, however under and inside the pipe, the flow swirls intensely. Under certain conditions the swirling flow induces a vortex at the bath metal interface through which bath can be entrained in the flow. The swirling action was also seen to produce a region of locally high velocities on the cathode surface which enhances erosion of the cathode through a number of possible mechanisms.
perature, nucleation position, solid fraction at nucleation temperature, and droplet temperature and velocity, is formulated. The concept of transient nucleation is applied to model such short nucleation event. A maximum droplet velocity exists, beyond which droplet velocity shows an inflection phenomenon during the flight. For shorter flight distance, smaller droplet is faster to reach a given flight distance; however, for longer flight distance, the situation is reversed. Variations of the gas flow patterns have more effects on smaller droplet, and the effects are more significant at longer flight distance. A minimum surface heat transfer coefficient exists as the droplet flies. Prior to nucleation or recalescence, smaller droplet has lower temperature at a given flight distance, and has lower nucleation temperature. Medium size droplet flies over the shortest flight distance before the nucleation starts. Smaller droplet has larger solid fraction at the end of recalescence. Atomization gas has more effects on droplet momentum than on the heat content of the droplet.
4:50pm A NEW CONCEPT OF RESOLVING LADLE CLEANING AT SLOVALCO BY TECHMO: F. Zannini, F. Marchetti, R. Balasso, J. lfju, Techmo Car SpA, Via R. Colpi 15/17,35010 Limena (PD), Italy
2:50pm Techmo has elaborated a new concept of resolving the problem of ladle cleaning based on standard features of the new aluminium smelter implemented by Hydro Aluminium's technology at SLOVALCO a.s. A thorough design work has resulted in a piece of equipment with new arrangement and orientation in good agreement with the tapping system and work organization of the plant. Some optimization was fulfilled in order to meet the requirements of the new plant in possible best manner.
THE EFFECT OF FORCED COOLING A PERMANENT COMPOSITE MOLD ON AIR GAP FORMATION: D.R. Gunasegaram', D. Celentano', T.T. Nguyen', 'CRC for Alloy and Solidification Technology (CAST) and CSIRO Division of Manufacturing Technology, Locked Bag 9, Preston 3072, Australia; 'International Center for Numerical Methods in Engineering, Edificio Col Campus Norte-UPC, Gran Capitan, sIn. 08034 Barcelona, Spain It is well known that the air gap that forms between casting and mold during the solidification process of an aluminum alloy substantially alters the rate of heat transfer at this interface. This paper reports studies on the effect of force cooling a composite permanent mold on the initiation and growth of the air gap. Interesting comparisons are made with the case where no forced cooling is employed. The two experiments are simulated using a fully coupled thermomechanical model called VULCAN, a finite element code, and its temperature and displacement predictions are validated. The air gaps are measured using LVDTs. The alloy used isA356, and the mold comprises H13 steel and beryllium-copper. Air jets are used to force cool the mold component surrounding an isolated thick section of the casting. The inverse heat conduction problem is solved in order to obtain boundary conditions for VULCAN.
APPLICATIONS OF SENSORS AND MODELING TO MATERIALS PROCESSING II Sponsored by: Jt. EPDIMDMD Synthesis, Control, and Analysis in Materials Processing Committee and EPD Process Fundamentals Committee Program Organizers:S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; R.G. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487; J.C. Malas, Wright-Patterson AFB, OH 45433-6533; LL Shaw, Dept. of Metallurgy & Materials Science, Univ. of Connecticut, Storrs, CT 06269-3136; R. Abbaschian, P.O. Box 116400, 132 Rhines Hall, Univ. of Florida, Gainesville, FL 32611-6400 Monday, PM February 10, 1997
3:15 pm BREAK
Room: 232A Location: Orlando Convention Center
3:25pm EFFECT OF TRANSVERSE DEPRESSIONS AND OSCILLATION MARKS ON HEAT TRANSFER IN THE CONTINUOUS CASTING MOLD: E.G. Thomas, D. Lui, B. Ho, G. Li, Y. Shang, Department of Mechanical and Industrial Engineering, University of Illinois at UrbanaChampaign, 1206 West Green Street, Urbana, IL 61801
Session Chairs: B.G. Thomas, Dept of Mechanical and Industrial Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801; B.a. Li, Dept of Mechanical Engineering, Louisiana State University, Baton Rouge, LA 70803
Results from mathematical models and plant experiments are combined to quantify the effect of transverse depressions and oscillation marks on heat transfer in the continuous casting mold. A heat transfer model has been developed to calculate transient heat conduction within the solidifying steel, coupled with the steady-state heat conduction with the continuous casting mold wall. The model features a detailed treatment of the interfacial gap between the shell and mold, including mass and momentum balances on the solid and liquid powder layers. The model predicts the solidified shell thickness down the mold, temperature in the mold and shell, thickness of the resolidified and liquid powder layers, heat flux distribution down the mold, mold water temperature rise, ideal taper of the mold walls, and other related phenomena. The important effect of non-uniform distribution of superheat is incorporated using the results from previous 3-D turbulent fluid flow calculations within the liquid cavity. Results from plant experiments confirm that transverse surface depressions and oscillation marks form at the meniscus and move down the mold. Measurements of mold thermocouple temperatures and breakout shell thickness were used to calibrate the models. The predicted local surface temperature fluctuations were consistent with transient mold temperature measurements. The results indicate that the surface depressions and oscillation marks are filled with mold flux, but still have a significant effect on decreasing heat transfer, especially locally. Insights are gained into the formation of associated surface cracks and breakouts.
2:00pm NUMERICAL ANALYSIS OF FLOATING ZONE REFINING PROCESSES: S.P. Song, B.Q. Li, Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA 70803 A numerical model is developed to represent complex electromagnetic, thermal and free surface deformation phenomena in floating zone refining and single crystal growth processes. The model is developed using a coupled boundary element and finite element method, with finite element meshes used for the melting zone region and boundary elements for the exterior region or free space. The free surface deformation model is developed using the weighted residual method. With the model, the complex transport and free surface phenomena in a floating, zone system are studied as a function of various operating conditions including applied current, frequency, inductor position and shape, surface tension, floating zone diameter and height. Model development and numerical results are presented.
2:25pm MODELING OF SOLIDIFICATION AND VELOCITY OF ATOMIZED MOLTEN DROPLET DURING ATOMIZATION AND SPRAY FORMING: Y.H. Su, c.- Y. A. Tsao, Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan, China A mathematical model to describe the solidification behaviors of atomized droplets during flight, in terms of nucleation temperature, recalescence tem-
39
the fairly complex cell-layout. As the cathodes are placed opposite direction in every other unit, cranks must be able to move toward two directions (X and Y) at the same time and to stop precisely at the tolerance level of a few millimeter. The central monitoring system for machine operation run by an original application software with MICROSOFT EXCEL© on WINDOWS 95©, was started in June 1996. There had been one person only for operating a manual crane before. Now an operator of a stripping machine can control the automatic crane for the same row at the same time. As a result, only one person can operate both a crank and a stripping machine for one row. And more labour saving is expected in the future.
3:50pm CHANGE OF PATTERN OF SOLIDIFICATION IN INGOTS CAST FROM THE BOTTOM, REPRESENTED BY A MATHEMATICAL MODEL AND ITS EFFECT ON THE APPARITION OF DEFECTS IN THE SEAMLESS TUBES OF C.V.G SIDOR: J. Rodriguez, A. Valles, C.Y.G SIDOR, Puerto Ordaz, Venezuela, M. Rao, Universidad Nacional Experimental de Guayana, Puerto Ordaz, Venezuela This paper shows a mathematical model based on finite elements, applied to bottom cast ingots of C.Y.G Sidor Plant. The model was used as a strategy to determine the thermal effects that are produced when the solidification conditions are modified, without interfering with the production process. The modification consisted of placing a thermal insulant on top of mould. The results obtained by the model indicated that the solidification time increases with insulant on top of the mould. With these results a significant number of casts were run with and without insulant. Later by means of a metallurgical analysis it was determined that the ingots cast with insulant reduce the level of nonmetallic inclusions and the presence of internal blistering in seamless pipes.
2:25 pm INDUSTRIAL SIZE "PLACID ELECTROWINNING CELL": C.Frfas, M.A. Garda, G. Dfaz, Tecnicas Reunidas, S.A., R&D Centre, Madrid, Spain Under the auspicious of the Commission of the European Union, a consortium composed of six European organizations has developed the PLACID process, into the Brite Euram II Programme. The project began on January 1993 and was finished on April 1996. The PLACID process is based on a novel technology able to deal with different lead bearing materials, mainly lead oxide secondaries: Lead-acid batter pastes, lead fumes, furnace slags, oxide residues, etc., producing "four nines" pure lead in an efficient manner with a benign influence on the environment. In the PLACID process, lead is leached in warm, slightly acidic, brine to form soluble lead chloride. This solution is purified by cementation with lead powder. Pure lead is then won from the lead chloride electrolyte on the cathode of the electro winning cell and is collected. This electrolytic cell is the heart of the process and it was especially developed to give optimum performance. Hydrochloric acid is reformed in the cell and returned to the leaching bath; reagent net consumption in the process is irrelevant. This paper is concerning the development of the PLACID electrowinning cell up to industrial size electrodes. The performed work has covered three levels of development: laboratory study, bench scale experimentation and pilot plant prototype testing (16 Kg/h electrolytic lead production). After 1,000 hours operating time, the achieved results of the pilot plant electrowinning cell have been very satisfactory, demonstrating the ability of the Placid electrowinning cell to produce top quality electrolytic lead (above 99.99% Pb) with high current efficiency and low energy consumption.
4:15pm MATHEMATICAL MODELING AND EXPERIMENTAL MEASUREMENTS OF EXOTHERMIC PHENOMENA IN NON FERROUS SYSTEMS: S.A. Ferenczy, S.A. Argyropoulos, Dept of Metallurgy and Materials Science, University of Toronto, 184 College Street, Toronto, Ontario, Canada M5S 3E4 Microexothermic and macroexothermic phenomena have been indentified various non-ferrous systems, which from recent experimental and mathematical studies have been shown to enhance heat and mass transfer. This paper will present experimental results and computer simulations describing the transient exothermic dissolution of nickel cylinders into liquid aluminum. Axisymmetric heat, mass and momentum equations the SIMPLER algorithm was modified to incorporate phase change and the micro exothermic macroexothermic events. Dissolution experiments were performed and the results compared to the mathematical simulation. The development of coupled temperature, concentration and momentum boundary layers are examined.
2:50pm
AQUEOUS ELECTROTECHNOLOGIES: PROGRESS IN THEORY AND PRACTICE II: Zinc and Lead Electrowinning
CHARACTERIZATION OF ANTIMONY-GELATIN ADDITIVES IN ZINC SULPHATE ELECTROLYTES USING IMPEDANCE ANALYSIS: X. Tang, P. Yu, TJ. O'Keefe, University of Missouri-Rolla, Department of Metallurgical Engineering and Graduate Center for Materials Research, Rolla, MO 65409-1170; G. Houlachi, Noranda Technology Centre, PointeClaire, Quebec, H9R 1G5, Canada
Sponsored by: EPD Aqueous Processing Committee, Copper, Nickel, Cobalt Committee, Lead, Zinc, Tin Committee and Precious Metals Committee Program Organizers: D.B. Dreisinger, University of British Columbia, Department of Metals and Materials Engineering, 309-6350 Stores Road, Vancouver, B.C., Canada; E. Ozberk, Sherrill International, Bag 1000, Fort Saskatchewan, AB, T8l 2P2; Mrs. S. Young, BHP Copper Inc., 2400 Oracle Road, Suite 200, Tucson, AZ 85704; R.S. Kunter, Advanced Sciences Inc., 405 Urban Street, Suite 401, lakewood, CO, 80228
Monday, PM February 10, 1997
Impedance measurements were used to investigate the electrochemical characteristics of acidic zinc sulphate electrolytes containing Sb'+, gelatin and their mixtures. The data were correlated with cyclic voltammetry curves made using synthetic as well as industrial electrolytes. The cyclic voltammetry results were similar to those obtained in previous studies in that antimony caused a depolarizing effect while gelatin gave an increase in the potential for zinc nucleation on an aluminum substrate. The electrochemical impedance spectroscope (EIS) evaluations were conducted on electrodeposited zinc at three overpotential values. The potentials were chosen to represent various current density regions in the zinc polarization curves. The antimony and gelatin gave characteristic impedance plots which correlated with expected behaviour, particularly current efficiency. Both antimony and glue appear to modify the intermediate zinc reaction sequence, but in different ways. The data strongly suggest that film formation and stability are major factor in the zinc ion reduction mechanism.
Room: 231A location: Orlando Convention Center
Session Chairperson: Dr. E. Ozberk, Sherrill International, Bag 1000, Fort Saskatchewan, AB, T8l 2P2
2:00pm DEVELOPMENT OF AUTOMATIC MATERIAL HANDLING AND MONITORING SYSTEMS IN AN EXISTING ELECTROLYTIC ZINC PLAN: T. Yamada, R. Togashi, T. Aichi, Akita Zinc Co., Ltd., Hjima Refinery, Akita, Japan
3:15pm EFFECTS OF ANTIMONY AND CONTINUOUS GELATIN ADDITION ON CURRENT EFFICIENCY IN THE HUDSON BAY ZINC ELECTRO WINNING TANKHOUSE: P. Merrin, Hudson Bay Mining & Smelting Co., Limited, Flin Flon, Manitoba, R8A IN9, Canada
Mainly due to the strong yen and the relatively low metal price, the zinc refineries in Japan are being forced to reduce man power. At IIjima, a new automatic material - handling system for cathode transportation was developed and the first system went to service in August 1994. The work was started in 1993 and all installation will be finished in the summer 1997. The critical part of this work was to achieve the designed cycle time because of
This study was conducted at Hudson Bay Mining and Smelting's zinc electrowinning tankhouse to determine the effects of varying levels of antimony and continuous gelatin addition on current efficiency. The levels of antimony
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and gelatin were varied between 0.010 - 0.030 mg/l and 0 - 10 mg/l respectively, using the fresh electrolyte as reference. The test was designed to determine the optimum operating point for current efficiency, and to investigate any interaction that occurs between the two components. An non-linear mathematical model relating these three variables was produced, giving an optimum operating point of 6.5 mg/l of gelatin and increasing current efficiency with decreasing antimony levels. Individually, the antimony concentration was approximately linear with current efficiency, while gelatin concentration was parabolic. An interaction term is present but is not significant enough to improve the ability of the tankhouse to handle purification upsets in antimony.
3:40pm THE EFFECTS OF SOME FOAMING REAGENTS ON ACID MIST CONTROL AND ZINC ELECTRO WINNING FROM KlDD CREEK ZINC ELECTROLYTE: A.M. Alfantazi, D.B. Dreisinger, University of British Columbia, Department of Metals and Materials Engineering, Vancouver, B.c., V6T lZ4, Canada; J. Synnott, M. Boissoneault, Falconbridge Ltd., Kidd Creek Division, P.O. Bag 2002, Timmins, Ontario, P4N 7Kl, Canada The effects of five commercially available foaming reagents (range of 0 to 25 ppm) namely Dowfroth 250 Saponin, Yucca, Licorice and Meta-Para Cresol on acid mist control, current efficiency, polarization behaviour, and deposit morphology and orientation were investigated using a bench scale electrolysis apparatus (cell volume 3L). The deposition was carried out at 500 Am" and 38°C for 3 hours from Kidd Creek zinc electrolyte. The acid mist control capability of the various reagents was studied and compared by characterizing the foam layer generated during actual electrowinning conditions and by direct quantitative measurements of acid mist levels on top of the electrowinning cells. Within the range considered, the addition of these reagents reduced the current efficiency, refined the grain size of the deposit, and changed to preferred orientation of most of the deposits. Among the reagents tested, acid mist measurements indicated that Licorice and Dowfroth 250 were the best acid mist suppressant at emissions of 0.30 mg/m3 and 0.31 mg/m3 respectively while Yucca and MPC produced the most mist at 3.0 mg/m3 and 3.3 mg/m3 emission rates respectively.
4:00pm ELECTROPURIFICATION OF ZINC LEACHING SOLUTION: S. Yamashita, K. Hata, S. Goto, Department of Metallurgy, Chiba Institute of Technology, Chiba, Japan The average consumption of zinc dust for purification of zinc leaching solution is more than 25 kg per ton of electrolytic zinc. Authors proposed to remove impurities in zinc leaching solution by electrolysis instead of cementation by zinc dust. The effects of copper and arsenic on electrodeposition of cobalt in zinc sulfate solution were examined fundamentally by using potentiostat. The mesh cathodes of stainless steel and lead anodes are used in the electrolytic cell for removal of cobalt and an electrolyte is circulating rate of electrolyte, concentration of copper and arsenious ions on removal of cobalt are studied. Removal of Ni, and Cd are also examined.
4:25pm Cl ANION ELIMINATION FROM Zn SULPHATE SOLUTION BY PERIODICAL REVERSE ELECTROLYTIC SYSTEM: T. Yoshida, M. Kahata, M. Dobashi, M. Suzuki, Mitsui Mining and Smelting Co. Ltd., Sairama, Japan In Japan, almost 30% of steel is produced by electric arc furnace (EAF) melting of iron scrap. And the dust from EAF includes approximately 20-30 wt % of Zn and 3.5 wt % of CI. They are treated as industrial waste to recover Zn as Zn oxide mainly by pyro metallurgical process. On the other hand, high purity zinc recovery by direct hydro-metallurgical processing is one of the most effective method. In this case, Cl in the EAF dust is dissolved in liquid phase by leaching, but the Cl anion in electrolyte attacks anode which is made of a lead base alloy. Several processes have been proposed to remove Cl anion from acidic sulfate solution. In this study, an electrolytic process is established to eliminate CI anion from Zn sulfate electrolyte. It is known that CI anion can be removed by anode oxidation. From our study it can be said that the elimination rate of Cl anion depend on the anode material, i.e. the elimination rate is Pb - Ag alloy> Pb DSE. Furthermore in industrial electro-
winning process, electrolyte includes Mn dioxide. Therefore, the effect of Mn in electrolyte should also be considered for CI elimination. It seems that Mn dioxide deposition on anode decreases the efficiency of CI anion removal. The periodical reverse system was induced to prevent from efficiency decrease. By using periodical reverse system, deposited Mn dioxide is removed very rapidly when the current was reversed for short time. More than 95% of CI anion can be removed in extremely short period than conventional method. At the symposium the detailed data will be presented about CI anion elimination by periodical reverse system.
4:50pm THE ROLE OF COPPER AND ANTIMONY ADDITIVES IN THE REMOVAL OF COBALT FROM ZINC SULPHATE SOLUTIONS: V. Van der Pas, D. Dreisinger, University of British Columbia, Department of Metals and Materials Engineering, Vancouver, British Columbia, V6T IZ4 Canada Zinc sulphate electrolyte used for zinc electrowinning must be purified for cobalt ions. The cobalt is removed in a cementation stage by the addition of zinc dust. Copper and antimony are frequently used additives which enhance the cementation of cobalt. This paper aims at a better understanding of how copper and antimony promote the removal of cobalt. Initial experiments were done in a batch cementation reactor. Copper and antimony precipitated in the early stages of cementation indicating that a preferential substrate was formed. The individual role of copper and antimony was further investigated in an electrochemical cell. On a microscale, the growth process, morphology and the composition of the precipitates under various conditions were examined with SEM and XRD. It was found that cobalt could not be deposited in its pure form but as a cobalt-zinc alloy with zinc as the prime constituent. The effect of copper addition is of increasing the cathodic surface area of zinc dust by precipitating as numerous dendrites. Antimony acts as a cathodic surface onto which a cobalt-zinc alloy with an increased cobalt content is deposited.
CAST SHOP TECHNOLOGY II: EqUipment and Operations Sponsored by: LMD Aluminum Committee Program Organizer: Wolfgang A. Schneider, VAW aluminium AG, Research and Development, Georg-von-Boeselager-Str.25, 0-53117 Bonn, Germany Monday, PM February 10, 1997
Room: 230B Location: Orlando Convention Center
Session Chairperson: Kurt Ehrke, Aluminium Essen GmbH, Sulterkamp 71, 045356 Essen, Germany
2:00pm REFRACTORY SOLUTIONS DESIGNED TO OVERCOME CORUNDUM GROWTH IN ALUMINIUM FURNACES: Duncan Jones, Morganite Thermal Ceramics Ltd., Liverpool Road, Neston, South Wirral, L64 3RE, England Corundum is an extremely hard, high temperature form of aluminium oxide. Its formation in aluminium melting furnaces and metal treatment units can lead to a reduction in operating efficiency and premature failure of the furnace lining. The formation of corundum is known to be dependent on several factors, including furnace atmosphere, operating temperature, alloy composition and refractory type. The paper describes solutions to this phenomenon identifying its cause and effect whilst highlighting refractory design criteria. Results from an extensive testing programme, classifying resistance to corundum growth against various qualities of refractory product are discussed.
2:20pm USE OF SIALON IMMERSION HEATERS IN MOLTEN ALUMINUM: Mark Palmer, Pyrotek Inc., E.9503 Montgomery Avenue, Spokane, WA; Andre Teytu, Atherm, Rue de Moirind 13, 38420 Domene, France Small diameter electric immersion heaters offer unique benefits when used in molten aluminum heating applications. The I" diameter heaters allow
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3:50pm THIN GAUGE TWIN-ROLL CASTING, PROCESS CAPABILITIES AND PRODUCT QUALITY: O. Daaland, M.L.Nedreberg, A.B.Espedaal, Hydro Aluminium a.s, R&D Materials Technology, N-4265 Hi'tvik, Norway
greater flexibility in vessel design than traditional immersion heating systems. The electric heating elements are inside a Sialon sheath, which is nonwedded by molten aluminum and offers long life. Since the development of these heaters, they are being used in many different types of molten aluminium holding vessels. Pechiney Aluminium Engineering utilizes these small heaters in Alpur degassing vessels and the Pechiney Deep Bed Filter Heaters are also used in die casting holding furnaces for both primary and supplemental heating applications. The net result of using the small immersion heaters is high metal heat-up rates, compact vessel designs, energy savings, uniform metal temperatures, and user friendly equipment designs. The paper describes the capabilities of the heaters, the design flexibility they allow, and performance results obtained from initial installations.
Traditionally industrial twin roll casters have been operated at gauges 6-7 mm, depending on the type of caster and the final product requirements. Over the past few years it has become apparent that a significant increase in productivity can be achieved when the casting gauge is reduced. Hydro Aluminium embarked on an extensive R&D thin gauge casting program in the beginning of the 1990's, and this paper presents results of a five year lasting project (joint program between Hydro Aluminium and Lauener Engineering). Based on over 400 casting trials the major benefits and limitations of casting at reduced gauge and increased speed are outlined. Important aspects for product quality are discussed including: cooling rates and dendrite structure, microstructural characteristics (as-cast grain structure and texture), segregation behaviour, surface quality and mechanical properties after thermomechanical processing. Results for casting of several alloys (including the 5xxx and 8xxx-system) are given. Additionally, numerical modelling results of the strip casting process are included.
2:40pm IMPACT OF GOOD METAL CIRCULATION AND FURNACE OPERATION FOR INCREASED PERFORMANCES FOR SIDEWELL FURNACES: G. Riverin, W. Stevens, Arvida Research and Development Centre, AIcan International Limited, 1955 Mellon Blvd., Jonquiere, Quebec, Canada G7S 4K8; D. Bristol, AIcan Rolled Products Company, P.O.Box 837, Greensboro, 30642; Y. Kocaefe, Universite du Quebec it Chicoutimi 555, Boul. de l'Universite E, Chicoutimi, Quebec, Canada G7H 2Bl
4:10pm PECHINEY JUMBO 3CMTM - START-UP OF THE NEUF-BRISACH THIN STRIP CASTER: Pierre-Yves Menet, Pechiney Rhenalu NeufBrisach, Z.I.Biesheim, BP 49, F-68600 Neuf-Brisach, France; Robert Cayol, Pechiney Aluminium Engineering, Centr' Alp-725 rue Aristide Berges, F38340 Voreppe, France; Jacques Moriceau, Pechiney Rhenalu Melting and Casting Direction ofTechnology, Centr' Alp-725 rue Aristide Berges, F-38340 Voreppe, France
Sidewell furnaces have long been operated for scrap melting, including UBC. The paper discusses important criteria for the optimum energy and melt rate performances for these types of furnaces. Intensive work has been done in several AIcan recycling installations in order to increase these furnace performances. Several operating parameters are outlined combined with the importance of melt stirring in the main hearth and in the sidewell. Mathematical and physical modeling provided key elements responsible for better furnace operation. The impact and advantages of the improved melt stirring and furnace operation are explained and discussed in detail.
Following extensive research and development work at the Pechiney Research Center in Voreppe, a new Jumbo 3CMTM thin strip caster has been installed at the Pechiney Rhenalu Neuf-Brisach plant. First of its generation, it is capable of casting a 2m wide strip under a maximum load of 2900 tons. This paper reviews the various features of the equipment which make possible the casting of thin strip of aluminum alloys covering a wide range of applications, from foil stock to can stock. Initially scheduled for start-up in June '96, the equipment was started on time. Performances concerning the installation itself and the casting of several alloys are given. A video of the installation and an actual casting will be shown during the Cast-Shop session.
3:00pm CAST HOUSE WATER TREATMENT WITH AEC TECHNOLOGY: Ed Grodecki, Betz Water Management Group, 4150 Washington Road, Bldg.2, Suite 206, McMurray, PA 15317 Cast house water treatment programs typically use organic phosphates to control both corrosion and deposition. These materials can break down or revert into inorganic phosphates in the presence of heat, long retention times and oxidizing biocides. The consequence of this reversion is the loss of calcium carbonate deposit control and an increase in the potential for forming inorganic phosphate deposits. Both situations would result in poor heat removal at the critical heat transfer surfaces. With the advent of the ABC molecule, cast house water treatment technology has taken a new step in controlling corrosion and scaling. The AEC molecule does not contain phosphate and does not break down in the presence of oxidizing biocides. It also has good thermal stability and does not degrade over time. Used in place of an organic phosphate, ABC will provide excellent calcium carbonate scale control without the risk of phosphate deposition. This paper studies a case history of one such application on a billet caster.
4:30pm AN UPDATE ON DOWN-GAUGING THE FATA-HUNTER SPEEDCASTERTM AT NORANDAL, HUNTINGTON (TN): R. Beals, B. Taraglio, C. Romanowski, FATA HUNTER Inc., 6147 River Crest Drive, Riverside, CA 92507 The first of a new generation of Thin-GaugelHigh-Speed FATA Hunter machines is now in operation at Norandal's Huntington (TN) facility. Following the late February 1996 start-up of the machine, a down-gauging program was commenced which combined normal 5 mm gauge production with a series of pilot production trials at progressively lighter gauges. This paper overviews this start-up program and compares the production rates and metallurgical characteristics of the thin-gauge cast material with conventional-gauge, twinroll cast strip. In addition, a brief video tape of the FATA Hunter 86" wide SpeedCasterTM in operation will be presented.
3:20pm MOLTEN ALUMINUM PLUS WATER - A DIFFERENT POINT OF VIEW: George J. Binczewski, S C Systems, PO Box 6154, Moraga, CA 94570 For forty years, the Aluminum Industry has conducted and sponsored investigations directed at establishing a better understanding of the safety aspects associated with the sometimes explosive occurrence which may happen when there is a physical contact between molten aluminim and water. Industry concern has resulted in a poling of resources among companies, associations, and technical organizations. There has been a substantial funding of investigative projects conducted by capable research organizations employing sophisticated techniques. While useful information has been gained and translated into operational procedures, the basic cause remains elusive. A completely different, and additional, investigative approach is suggested based on cumulative experience and observation of daily occurrences. This can provide the informational basis to alleviate the safety and liability concerns associated with direct contact between molten aluminum and water.
4:50pm MAGNETIC EDGE DAMS IN A TWIN ROLL ALUMINIUM CASTER: Craig Anderson, Peter Davidson, Engineering Department, Cambridge University, Cambridge CB2 IP2, United Kingdom In the twin roll casting process, molten aluminium is fed between two cooled rotating rollers where it cools, solidifies and is carried by roller rotation to the nip, where it is compressed to a single sheet and expelled. To prevent aluminium escaping laterally, from the roller edges, dams are required. Physical edge dams are subject to erosion from the rollers and molten metal and require maintenance and replacement. Hence there is a strong economic case for using magnetic edge dams, where the interaction of a magnetic field and a current provide sufficient repUlsive force to contain the molten aluminium, which do not physically touch either the rollers or molten metal and require little or no maintenance. This paper discusses the theory behind high fre-
3:40 pm BREAK
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quency magnetic edge dams and describes the design and construction of a practical system. Laboratory testing of the magnetic edge dam system is shown to give good agreement with theory and the installation and operation of the system on an experimental twin roll caster is described.
and Fe segregation between the nanocrystal and the matrix were secured in a TEM with a field emission gun. Both Fe and Od are preferentially rejected into the remaining matrix as the aluminum-rich nanocrystal grows. After reaching a specific size, which varies with temperature, growth slows down and funkier changes are slight until subsequent nucleation and growth of compound phases. such as Al 4 0d occur. The relative stability of the formation of nanocrystals from an amorphous matrix will be addressed. Research supported by the University of Virginia Academic Enhancement Program.
5:10pm DECOATING TECHNOLOGY FOR THE ALUMINIUM INDUSTRY: O.H. Perry, Stein Atkinson Stordy Ltd., Midland House, Ounsdale Road, Wombourne, Wolverhampton WV5 8BY, England
3:00 pm INVITED DIFFUSION FIELD IMPINGEMENT DURING PRIMARY CRYSTALLIZATION OF ALUMINUM NANOCRYSTALS: D.R. Allen, lC. Foley, J.H. Perepezko, Materials Science and Engineering, University of Wisconsin - Madison, 1509 University Avenue, Madison, WI 53706
The technology for recycling aluminium scrap has evolved over a number of years through five major changes as follows: direct charging, side bay melter with puddlers, rotary furnaces, shredding and flat belt delacquering machines, shredding and rotary kilns, today it is now possible to fully decoat any aluminium material which can be shredded. With the invention of IDEX® rotary kiln systems all materials from UBC, extrusions, coated foils, through to 6 micron aseptic foils can be successfully reclaimed and either remelted or processed with minimal metal loss. During 1996 three systems have been commissioned in the Americas for decoating materials which contain 3 to 80% VOC by weight and ranging from 4 to 7 tonnes per hour. This paper discusses the changing technology and the current "state of the art" in rotary kiln technology.
Aluminum-rich glasses containing about 85 at% Al and a combination of transition and rare earth element additions have yielded microstructures of Al nanocrystals in an amorphous matrix with nanocrystal volume fractions approaching 20% and excellent mechanical properties. A high density of nanocrystals ( >1020 m·3 ) develops during the primary crystallization reaction but growth is limited. A new kinetics analysis shows that diffusion field the nanocrystals. The kinetics model has been applied to DSC exotherms that correspond to primary fcc nanocrystal formation. A thermodynamic model of the fcc-liquid phase support heat evolution rate calculations used in the model. The results indicate that modification of the nucleant density should be the primary focus in limiting nanocrystal growth due to reduced length scales.
CHEM.ISTRY AND PHYSICS OF NANOSTRUCTURES AND RELATED NONEQUILIBRIUM MATERIALS II: Phase Transformations
3:20pm MICROSTRUCTURAL AND THERMAL ANALYSES OF CRYSTALLIZATIONINULTRAFINEAMORPHOUSTITANIAPARTICLES: J.S. Yin, L. He, O.L. Oriffin*, E. Ma, Mechanical Engineering, *Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803
Sponsored by: Jt. EMPMD/SMD Chemistry and Physics of Materials Committee, MSD Thermodynamics and Phase Equilibria Committee Program Organizers: Brent Fultz, 138-78, California Institute ofTechnology, Pasadena, CA 91125; En Ma, Louisiana State Univ., Dept. of Mechanical Eng., Baton Rouge, LA 70803; Robert Shull, NIST, Bldg. 223, Rm B152, Gaithersburg, MD 20899; John Morral, Univ. of Connecticut, Dept. of Metallurgy, Storrs, CT 06269; Philip Nash, Illinois Institute ofTechnology, METM Dept., Chicago, IL 60616 Monday, PM February 10, 1997
Uitrafine amorphous titania particle aggregates, with a mean particle size of 145 nm, were prepared using a hydrolysis technique in an aerosol reactor. Their crystallization bahavior has been studied using transmission electron microscopy, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. The amorphous powder crystallized into anatase with a crystallization enthalpy of 27 kJ/mol and an apparent activation energy of 2.0 e V. The anatase phase nucleated preferentially in contact regions between neighbouring particles. This crystallization mode is interpreted as a consequence of the presence of appreciable local pressure (stress) which was predicted by model calculations and observed under TEM. An analysis suggests that the pressure effect reduces the relative stability of the amorphous phase by enhancing the thermodynamic driving force for nucleation and possibly also the crystallization kinetics. The nucleation and growth behavior observed has important implications when these amorphous particles are used as precusors to form nanocrystalline titania. The results are also discussed in comparison with the crystallization behavior reported previously for other ultrafine-structured oxides.
Room: 330C Location: Orlando Convention Center
Session Chairperson: John Morral, Univ. of Connecticut, Dept. of Metallurgy, Storrs, CT06269
2:00 pm INVITED ALUMINIUM-BASED NANOPHASE COMPOSITES BY DEVITRIFICATION: A.L. Greer, University of Cambridge, Department of Materials Science & Metallurgy, Pembroke Street, Cambridge CB2 3QZ, UK Al-TM-Ln alloys (TM ... transition metal; Ln .. .lanthanide) can be rapidly quenched into a fully amorphous state and then partially devitrified to give a nm-scale microstructure of aluminium crystallites uniformly dispersed in an amorphous matrix. This is a highly unusual microstructure for an aluminium alloy, indicating a high density of independent nucleation events in the glass. This study focuses on the development and stability of microstructure in a series of Al-Ni-Y alloys. The effects of various single- and two-stage heat treatments are explored. The emphasis is on the particular features associated with the unusual nm-scale - among these is the overlap between coarsening and further transformation arising from capillarity effects on the crystallites.
3:40 pm BREAK 3:55 pm INVITED PRESSURE INDUCED CRYSTAL-TO-AMORPHOUS TRANSFORMATIONS: R.-B. Schwarz, PJ. Yvon*, Center for Materials Science, Los Alamos National Laboratory, Los Alamos, NM 87545, *Present address: SRMA, Centre d'Etudes Saclay 91191 OifNvette, France Pressure-induced crystal-to-glass transformations have been observed in tetrahedrally coordinated elements (e.g. Oe, Si), ionic and molecular crystals (alpha-Si0 2. FeSi04 , A1PO., Fe PO., SnBr4 ), and hydroxides (ice, Ca(OH)2' Co(OH)2)' In these materials, the crystal transforms polymorphically to a higher density glassy phase. Crystal-to-glass transformation have also been observed to occur through pressure-induced reactions between mixtures of elements such as germanium and aluminum. This paper reviews the formation of amorphous phases in alloys and elemental mixtures and discusses the possibility of obtaining bulk amounts of amorphous phases.
2:30 pm INVITED KINETICS OF NANOPHASE CRYSTALLIZATION IN AI-Fe-Gd ALLOYS: A.A. Csontos, G.J. Shiflet, Materials Science and Engineering, University of Virginia, Charlottesville, VA 22903 This presentation will provide results an the formation and subsequent growth of nanocrystalline aluminum phases in an amorphous matrix. A prototype for this family of metallic glass alloys that can be transformed into nanocrystalline material is the AI90Fe,Od, system. Detailed measurements of nanocrystalline isothermal growth from an amorphous A!"oFe,Od, matrix were made from 150 to 500°C. Coupled with growth of the nanocrystals, measurements of Od
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4:25pm STABLE VS. METASTABLE PHASE EQUILIBRIA IN FACETEDI NON·FACETED METALLIC GLASS SYSTEMS: T.M. Adams. M.J. Kaufman, Materials Science and Engineering, University of Florida, Gainesville, FL 32611
high temperature treatment were investigated. The ribbons with such structures in optimum state have good elastic and shape memory properties.
DESIGN AND RELIABILITY OF SOLDERS AND SOLDER INTERCONNECTS: Session II: Microelectronic Packaging Technology -Trends and the Importance of Solder and Solder Joint Reliability
Since metallic glasses can be used as precursors for nanocrystalline structures, it is important to understand the relationship between the transformation characteristics of the stable faceting phases and the metastable ordered phases (MOP's) in faceted/non-faceted systems. Such an understanding of the competitive nucleation and growth kinetics should allow better control of the transformation structures. Following some past work on AI-Ge alloys, it has been proposed that, in general, for faceted/non-faceted systems, no equilibria exist between the MOP's and the stable faceted phases. In order to support this assertion of generality, the Hf-Be and AI-Ge systems are being investigated. Crystallization of amorphous melt spun ribbons and co-evaporated thin films is effected by standard furnace anneals and in-situ electron beam heating. Once annealed, the resulting microstructures are characterized using XRD and TEM. In addition, in-situ hot-stage TEM is used to examine the relationship between the MOP and the stable faceting phase while the transformations are occurring. All of this work is being done in the vicinity of the stoichiometric composition of the most stable MOP (Hf-50Be and AI50Ge). Basic modelling efforts of the metastable phase equilibria are also under way using THERMOCALC with estimated heats of formation for the MOP's determined through DSCIDTA and empirical formulations.
Sponsored by: MSD Flow and Fracture; SMD Mechanical Metallurgy; EMPMD Electronics Packaging and Interconnection Materials Committees Program Organizers: R.K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; D.R. Frear, Sandia National Laboratory, Mail Stop 1411, Albuquerque, NM 87185; S.M.L. Sastry, Washington UniverSity, Mechanical Engineering Dept., St. Louis, MO 63130; K.L. Murty, North Carolina State University, Materials Science and Engineering Dept., Box 7909, Raleigh, NC 27695; P.K. Liaw, University of Tennessee, Materials Science and Engineering Dept., Knoxville, TN 37996; W.L. Winterbottom, Reliability Consultant, 30106 Pipers Lane Court, Farmington Hill, MI 48331
Monday, PM February 10, 1997
Room: 332 Location: Orlando Convention Center
Session Chairpersons: Sungho Jin, LucentTechnologies, Bell Laboratories, Room 7G·326, 700 Mountain Avenue, NJ 07974; Iver E. Anderson, Ames Laboratory, Iowa State University, 122 Metals Development Bldg., Ames, IA 50011
4:45pm STRUCTURAL TRANSITIONS IN Ti/AI NANOLAYERED THIN FILMS: R. Banerjee, X.D. Zhang and H. L. Fraser, Materials Science and Engineering, Ohio State University, Columbus, OH 43210; M. Asta, A.A. Quong, Computational Materials Science, Sandia National Laboratories, Livermore, CA, R. Ahuja, Multi Arc Scientific Coatings, Troy, MI
2:00 pm INVITED THE INFLUENCE OF MICROSTRUCTURE ON THE FAILURE OF EUTECTIC SOLDERS: John W. Morris, Jr., H. Reynolds, Department of Materials Science and Mineral Engineering, University of California, Berkeley, and Center for Advanced Materials, Lawrence Berkeley Laboratory, CA 94720
Nanolayered materials often exhibit unusual structural features which are significantly different from those of their bulk counterparts. Such structural transitions could lead to novel properties of the material motivating research directed towards engineering the structure at the nanoscale. Laminated thin films based on Ti, Al and Ti-aluminides have potential application as coatings for components used in high temperature aerospace applications. A series of structural transitions were observed in Ti I Al multilayered thin films on reducing the layer thickness ofthe Ti and Al layers 1. An hcp-fcc transition was found to occur in the Ti layers on reduction of the layer thickness to 5 nm. Al too exhibited an fcc-hcp transition on reducing the layer thickness to 2.5 run. Interestingly, a 2.5 nm Ti layer had an hcp structure. An atempt was made to explain these transformations in the stacking sequence of the Ti and Al layers using a model initially proposed by Redfield and Zangwill. Subsequently, first principles electronic structure calculations are in progress to determine the effect of bulk, interfacial and thin film strain energies on the structural stability of the multilayers. Initial results suggest that strain energy may be playing a pivotal role in determining the structure.
There are three key mechanisms of failure during the life of microelectronic solder joints: overload failure during handling, thermal fatigue failure during service, and, particularly in the case of joints for optoelectronic devices, dimensional changes during service. Each of these failure modes is strongly influenced by microstructure of the solder, which is, in turn, affected by the composition of the solder, the chemical nature of the substrate, and the manufacturing process that is used to create the joint. The present talk will discuss the varieties of microstructure that are found in common solder joints, their influence on lifetime and failure mode, and the metallurgical techniques that can be used to control microstructure and modify the nature and kinetics of joint failure. 2:25 pm INVITED DIFFUSION PROCESSES IN LEAD BASED SOLDERS USED IN MI· CROELECTRONIC APPLICATIONS· AN OVERVIEW: Devendra Gupta l , J. M. Oberschmidt2 , K. Vieregge3, 'IBM T. 1. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598; 2IBM Semiconductor Research and Development Center, Rt. 52-API, Hopewell Junction, NY 12533; 3Hoogovens Aluminium GmbH, 5400 Koblenz, Germany
5:05 pm NANOSTRUCTURES AND PROPERTIES IN RAPIDLY SOLIDIFIED Ti(SO)Ni(SO-X)Cu(X)ALLOYS: V. G. Pushin, S.B. Volkova, N.M. Matveeva*, A.S. Chistjakov, Institute of Metal Physics, Ural Division of Russian Academy of Sciences, S. Kovalevskoi 18, 620219 Ekaterinburg, Russia; *Baikov Institute of Metallurgy, Russian Academy of Sciences,Leninskij prospect 49, 117911 Moscow, Russia
Lead based solders are main stay of the microelectronic industry. Besides their use in printed boards, they are employed in interconnections of Si chipto-substrates such as the multi-chip-modules, the thermal-conduction-module, the tape-automated bonding etc. During their service, the solder interconnections, commonly known as C-4 joints, are subjected to temperatures of the order of 100°C which translate to homologous temperatures of Trrm~ 0.5 where Tmis the melting temperature in Kelvin. At these temperatures. a host of diffusion and related phenomena become operative notably the diffusion in the lattice and grain boundaries, creep and fatigue which eventually determine reliability of the device packaging. We have carried out extensive diffusion studies on the Pb-In and Pb-Sn solders over a range of composition using radioactive tracer techniques. We will discuss therein the various diffusion process, their modifications through ternary solute additions such Au and Cu and the role of unstable microstructure particularly in the eutectic solders.
Rapidly solidified Ti-Ni-Cu alloys prepared by melt spinning were studied. It is found that under super rapid cooling rates alloys with 25-40 at% Cu are formed in initial amorphous state, with 15-25 at% Cu - in amorphous-crystalline state, with 15 at% Cu don't become amorphous under spinning. Crystallization heat treatment of amorphous alloys leads to the formation of nanoscale TiNi-based solid solution, which undergo martensitic B2.>B'9 martensitic transition in cooling. Temperatures of martensitic transformations for RSalloys have been established to be lower, than for same alloys prepared under traditional cooling rates, because of nano-scale grain size of B2-phase crystalizing from amorphous structure. The martensite in a nano- and micro grains may have different morphology and orientations. Nanophase (B 2. TiNiCu) and nanocomposite (B 2+B,.(TiCu)) structures formed under crystallization by means of laser treatment, heating effect of electrical current and
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2:50 pm INVITED DEFORMATION, FATIGUE CRACKING AND COARSENING IN A LEAD-TIN EUTECTIC: T. Plookphol', Donald S. Stone} and S. -M. Lee', IMaterials Science and Engineering Dept., University of Wisconsin, Madison, WI; 'Samsung Electronics Co., Suwon, Korea
The mechanical properties (E, 0"02' UTS and 0%) of fIve Pb-Sn solder alloys (63Snl37Pb, 62Snl36Pb/2Ag, 96Snl4Ag, 95Pb/5Sn, 90PbIlOSn) commonly used in electronic packaging have been determined over the temperature range of -200°C to 150°C using uniaxial tensile test, dynamic mechanical analysis, and acoustic pulse method. The following results have been found: (l) the elastic moduli decreases linearly with increasing temperature until 70°C, then rapidly drop for the temperature 100°C and above; the strength (00 ." UTS) decreases with increasing temperature with the exception that for the solid solution solder (95Pb/5Sn, 90SnlIOSn) which remain approximately constant; (3) the ductility change is complex: for lead matrix solid solution solders; the total elongation (a) increasing slowly with increasing temperature, the uniform elongation (a) is relatively high (>20%), and decreases slowly with increasing temperature, and the neck elongation (a) increases sharply with increasing temperature; whereas, for the eutectic solders (63Snl37Pb, 62Pb/ 36Ag12Ag, 96Snl4Ag), the super-plasticity occurs at high temperature (> 100°C), while at low temperature (-150°C) the brittle fracture occurs, the higher uniform elongation occurs at about -100°C.
Over the last several years, we have experimented with lead-tin eutectic carefully controlled microstructure in order to leam about creep, microstructural evolution, and fatigue cracking in this alloy. The purpose of those experiments has been to formulate a mechanistic basis for modeling the creep-fatigue interaction. In this paper we review the work. Creep tests, tensile tests, and load relaxation tests combined with microstructural characterization and theoretical modeling have helped to provide insight into the roles of dislocations and colony boundary sliding during creep. Colony boundary sliding impacts upon cracking and coarsening during fatigue. Work hardening and dynamic recovery during creep affect subsequent coarsening. Fatigue experiments examining the effects of frequency and strain range on fatigue crack growth have revealed transitions in mode of crack growth accompanying the onset of colony boundary sliding at low strain rates. Experimental studies of the effect of prior deformation on subsequent coarsening reveal that the factor by which coarsening accelerates depends on the rate of deformation. 'Supported by the Wisconsin Alumni Research Foundation.
4:25pm A MODEL OF REACTIVE WETTING FOR THIN DROPS: James A. Warren!, W. J. Boettinger 1• A. R. Roosen', IMetallurgy Division, 'Ceramic Division, Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899
3:15 pm BREAK When a liquid alloy spreads on a substrate, interdiffusion may result in melting of the substrate of the substrate and/or formation of intermetallic phases. We investigate the former case and describe the evolution of the non-planar interface on the lower surface of the drop. An approximate diffusion analysis is performed for a drop whose height is much smaller than its width. The coupling between the melting process and the rate of advance of the triple junction is explored for a variety of contact angle conditions. Numerical solution of the governing equation are performed and compared to experimental results for Bi-Sn alloys spreading of a droplet on a grain boundary.
3:25 pm ANEW METHODOLOGY TO MEASURE DAMAGING STRAINS IN LEADtrIN SOLDERS: Abbas l. Attarwala! and Juan M. Sanchez', IHewlettPackard Company, IC Business Development Division, Palo Alto, CA 94304; 'Center for Materials Science, The University of Texas at Austin, TX 78712 A new methodology was developed to isolate and measure the damaging strains in lead/tin solders. The new methodology is based on load controlling cycling as opposed to strain controlled cycling. Under load controlled cycling conditions it is easy to separate out the effects of the different strain components. It was determined that the damaging strains were primarily creep strains, even at a cyclic rate of 0.5 Hz at a temperature of -40°C. Fractographic analysis of the fractured specimens confIrmed that failure even at -40°C occurs by creep processes. The envelope strain curve generated from load controlled cycling data is a direct measure of the damaging strains stored in the material. A new parameter, Yo was identified. Yo is the damaging strain stored per cycle. The damaging strains per cycle measured for various solder compositions tested at varying frequencies, temperatures and microstructures could all be correlated by simple linear relationships. It was observed that the damaging strain stored during the secondary creep region of the envelope strain curve ranges from 2% strain to 18% strain depending on the test conditions.
4:45 pm EFFECT OF COMPOSITE STRENGTHENING STRATEGIES ON THE MICROSTRUCTURAL EVOLUTION IN A TIN-SILVER SOLDER: A. W. Gibson, S.L. Choi, J.L. McDougall, T.R. Bieler, K.N. Subramanian, Department of Materials Science and Mechanics, Michigan State University, East Lansing, MI48824 Pending Federal regulations provide the impetus for using Pb-free solders. Automotive electronics and solders are exposed to thermal cycles in the range of -40°C to 150°C under cyclic and quasi-static conditions, and they experience low and high frequency mechanical fatigue vibrations. Since coarsening of microstructural features is known to affect fatigue resistance, the effects of aging behavior is investigated using eutectic Sn-Ag solder as a model system, with and without intentionally added intermetallic strengthening phases. Small single shear lap specimens with a size similar to joints in microelectronic applications are used to obtain microstructures that are obtained in real solder joints. Eutectic Sn-Ag solder joint microstructures coarsen when aged between 40 and 150°C for as little as a week. The microstructural evolution and its effect on mechanical properties is monitored with ageing temperature and time, and the kinetics of ageing is determined. The effects of adding composite intermetallic phases on the solder interface and ageing behavior are compared to the model Sn-Ag system.
3:45pm CREEP CRACK PROPAGATION OF 63Snl37Pb WITH EMPHASIS ON COLONY BOUNDARY DEFORMATION AND RUPTURE: Scott A. Schroeder! andM. R. Mitchell' and A. G. Evans', lRockwell ScienceCenter, 1049 Camino Dos Rios, Thousand Oaks, CA 91360; 'Division of Applied Sciences, Harvard University, Pierce Hall, 29 Oxford Street, MA 02138 Experiments on deformation and rupture of eutectic SnlPb solder will be discussed. These involve in-situ fIeld emission SEM observations made during tensile and thin-walled torsional shear testing at room and elevated temperatures. Deformation concentrates on colony boundaries, leading to cavitation, cracking, and tertiary creep. Cavity formation also induces a large anelastic (time-dependent recoverable strain) effect. Progressive colony boundary damage has been mapped from sequential in-situ images. Subsequent strain fIeld mapping and animations, highlight and quantify the relative deformations. High magnifIcation image sequences characterize cavity growth and coalescence mechanisms. Upon combining with calculations of stress distribution, creep induced cavitation and crack propagation have been quantifIed.
5:05 pm FORCED DIFFUSION THERMOGRAPHY FOR NONDESTRUCTIVE EVALUATION OF MICROSTRUCTURES: David A. Jahnke, Bela l. Sandor, Nuclear Engineering and Engineering Physics Dept., University of Wisconsin, 153 Engineering Research Building, Madison, WI 53704 Forced Diffusion Thermography (FDT), differential temperature detection across a material flaw while providing a controlled AC heat flux input, has been developed recently for structural integrity assessment in large structures. This paper presents FDT to identify microscopic flaws by both fInite element analysis and experimentation. The technical difficulties are the production of a microscopic width heat flux line pattern and the spatial and temperature resolution of the infrared camera. A fInite element model one millimeter square and one-third millimeter deep of tin solder material with various surface crack sizes specimens with known microscopic flaws were per-
4:05pm MECHANICAL PROPERTIES OF Pb/Sn SOLDERS AT THE TEMPERATURE RANGE OF -200°C TO 150°C: W. Kinzy Jones, Yanqing Liu, Marc A. Zamino, Gerardo L. Gonzales, Department of Mechanical Engineering, Florida International University, Miami, FL 33199
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estimated for the elastic modulus measurement using the sonic resonance method. A two-layer composite model was developed and applied for measuring the elastic modulus of thin film that is generally difficult to measure. The Ti coated Si wafer composites were produced using magnetron sputtering and used to test the developed model.
formed using an infrared camera with a temperature resolution of one mK. A seven mW helium-neon laser provided an AC heat input area of 250 micron wide by five millimeters long to the specimen's surface. The results show that this method can be applied to detect flaws in small specimens of solder and similar materials.
3:40 pm BREAK
EVOLUTION AND ADVANCED CHARACTERIZATION OF THIN FILM MICROSTRUCTURES II: Stress and Mechanical Properties
4:00 pm INVITED EPITAXY AND STRESS IN METAL THIN FILM COMPOUNDS AND MULTILAYERS: B.M. Clemens, T.e. Hufnagel, V. Ramaswamy, M.e. Kautzky, C.T. Wang, Department of Materials Science and Engineering, Stanford University, Stanford, CA 93405-2205
Sponsored by: MSD Structures Committee, EMPMD Thin Films and Interfaces Committee Program Organizers: Eric P. Kvam, School of Materials Engineering, Purdue University, West Lafayette, IN 47907-1289; Steven M.Yalisove, Dept. Materials Science and Eng., HH Dow Bldg., University of Michigan, 2300 Hayward St., Ann Arbor, MI48109-1204; Eric P. Chason, Sandia National Labs., Dep1.1112, MS 1415, PO Box 5800, Albuquerque, NM 87185 Monday, PM February 10, 1997
Epitaxial growth can be used to control and help understand thin film properties. We use sputter deposition to grow a variety of epitaxial thin film structures, including compounds and multilayers. The large stresses observed in these materials can have a large effect on properties. Using in-situ stress measurements and x-ray diffraction we study the stress evolution during growth and relate this behavior to thin film structure and properties. For Fe on Cu (00 I), we find that Fe is fcc up to a thickness of 10-12 mono layers, whereupon bcc Fe is observed in first the Pitsch and then the Bain orientations. The fcc Fe shows some relaxation of the misfit from the Cu, as do the Pitsch orientation bce, which is in tension, and the Bain orientation bee, which is in compression. In the giant magnetostrictive compound TbFe2, we have used epitaxy and differential thermal contraction to control the stress and hence the orientation of magnetization. This understanding and and control can lead to improved device performance.
Room: 340C Location: Orlando Convention Center
Session Chairs: E.H. Chason, Sandia National Laboratories, Albuquerque, NM 87185-1415; R.C. Cammarata, Surface and Interface Science Branch, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375
2:00 pm INVITED
4:40pm THE MECHANICAL BEHAVIOR OFPZTTHIN FILMS DEPOSITED BY A SOL·GEL TECHNIQUE: D.F. Bahr, J.S. Wright, L.F. Francis, N.R. Moody*, W. W. Gerberich; Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, *Sandia National Laboratories, Livermore, CA 94550
SURFACE AND INTERFACE STRESS EFFECTS ON THIN FILM GROWTH: R.C. Cammarata, Surface and Interface Science Branch, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 Associated with any solid surface is a surface stress. It is an intrinsic thermodynamic quantity that represents the reversible work per unit area needed to elastically stretch the surface. In materials where there is a large surface area to volume ratio, such as thin films, surface stresses can have a mltior influence on the growth and structure. In the case of a solid-solid interface, there are two interface stresses that represent the work needed to stretch the two phases on either side of the interface. Simple models for surface and interface stresses will be presented. These will then be used to analyze thin film epitaxial growth as well as intrinsic stress generation in nonepitaxial films. It will be shown that surface and interface stresses playa central role in determining the critical thickness for epitaxy, and can lead to significant intrinsic stresses in nonepitaxial films, especially during the early stages of growth.
Lead-zirconate-titanate (PZT) thin films are used in microelectromechanical systems (MEMS) as piezoelectric components. Both the mechanical and electrical properties of the PZT layer must be known in order to understand the piezoelectic response of the PZT for use as either a sensor or actuator. These properties are controlled by the composition and structure of the PZT film and its interface. Variations in PZT film structure and morphology are caused by changing solution processing conditions. PZT films have been deposited to thicknesses between 400 and 600 nm onto a multilayered electrode structure of platinum, titanium, titanium dioxide and silicon oxide. Nanoindentation has been used to characterize the effects of grain size and structure on the mechanical properties of the PZT films. The effects of the substrate and the multilayered electrode are accounted for to determine the modulus and hardness of the PZT films.
2:40 pm INVITED STRESS MONITORING DURING THIN FILM GROWTH: Jerrold A. Floro, Eric Chason, Sandia National Labs, P.O. Box 5800, Albuquerque, NM 87185-1415
5:00pm ADHESION OF CVD TiN ON 316L SURGICAL STAINLESS STEEL OBTAINED IN A MASS TRANSFER REGIME: M. H. Staia, School of Metallurgy and Materials Science, Universidad Central de Venezuela, Apartado 49141, Caracas 1042-A, Venezuela; C. Julia Schmutz, Swiss Centre for Electronics and Microtechnology Incorporated, P.O. Box 41, Neuchatel, Switzerland
Thin films are typically deposited under severe kinetic constraints, resulting in highly non-equilibrium microstructures. These films often exhibit stress levels far in excess of the bulk yield strength. The origin and evolution of the film stress during deposition is, in most cases, poorly understood. We have developed a technique for real-time measurement of film stress during deposition - the Multi-beam Optical Stress Sensor (MOSS). MOSS is a technique for determination of stress through measurement of the substrate curvature. It has the virtues oflow sensitivity to ambient vibration, simplicity of setup, and ease of use. We will describe the technique, and demonstrate its use for the particular case of SiGe heteroepitaxial growth on Si. We first discuss the elastic/plastic behavior of SiGe, and then focus on the surface segregation of Ge during SiGe growth. The latter topic, while somewhat specialized, is well-suited to demonstrate the interpretation of MOSS data, and to highlight both the strengths and limitations of the technique.
An investigation has been undertaken to study the adhesion of TiN coatings deposited by using CVD process at 900°C on surgical stainless steel. The microscratch test method (CSEM) was employed to evaluate the coating adhesion. Three scratches were performed at progressive load under the test conditions. Observation of the surface damages by means of an optical microscope permitted to determine the critical load. No acoustic emission detections or frictional force fluctuations could be correlated with the optical observations. In this investigation, the critical load corresponds to the regular occurrence of delamination. Scanning electron microscopy provided the essential and detailed information about the mode of failure of the coatings along the scratch channel. It was found that the coatings presented high plastic deformation and cohesive fracture at values lower than the critical load, Lc.
3:20pm ELASTIC MODULUS MEASUREMENT OF THIN FILM USING A DYNAMIC METHOD: Y. Kim, Department of Metallurgical Engineering, Chonnam National University, Kwangju, 500-757, Korea The effect of external medium (air in this study) and specimen damping was
46
2:50pm MICROSTRUCTURE EVOLUTION THROUGH THE a-ty PHASE TRANSFORMATION IN A Ti-48 AT. % Al ALLOY: T. Kumagai, E. Abe, M. Nakamura, National Research Institute for Metals, Tsukuba-shi, !baraki 305, Japan
FUNDAMENTALS OF GAMMA TITANIUM ALUMINIDES II: Phase Transformations and Microstructure Evolution
The a (disordered h.c.p.) -t y (TiAI; ordered Llo structure) massive transformation is partially suppressed even in a Ti-48 at. %Al alloy, when the alloy is quenched rapidly from the high temperature a phase filed. The untransformed (meaning 'not massively transformed') regions show an extremely fine a, (Ti3AI; ordered DO'9 structure) / ylamellar structure rather than an a 2 single phase structure, which is commonly observed in the quenched alloys with AI concentration of less than 47 at. %AI. By the subsequent aging treatment this. fine ajylamellar structure changes easily to the fine y grain structure, which is quite similar to the massively transformed y grain structure. The microstructural development of the extremely fine ajy lamellae during the isothermal aging treatments is presented and the a-ty phase transformation through the ajy lamellar structure will be discussed.
Sponsored by: MSD Flow 8. Fracture and Phase Transformations Committees Program Organizers: Kwai S. Chan, Southwest Research Institute, San Antonio, TX 78228-0510; Vijay K. Vasudevan, Dept. of Materials Science & Engineering, University of Cincinnati, Cincinnati, OH 45221-0012; Young-Won Kim, UES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432-1894 Monday, PM February 10, 1997
Room: 330E Location: Orlando Convention Center
Session Chairpersons: Hamish L. Fraser, Dept. of Materials Science and Engineering, Ohio State University, Columbus, OH 43210; Hubert I. Aaronson, Dept. of Materials SCience & Engineering, Carnegie Mellon University, Pittsburgh, PA 15213
3:10pm THE GAMMA TO ALPHA TRANSFORMATION IN A Ti-48AIALLOY: K. Muraleedharan, T.M. Pollock, Dept. of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213; P. Wang, v.K. Vasudevan, Dept. of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45221
1:55 pm OPENING REMARKS 2:00 pm INVITED PHASE TRANSFORMATION BEHAVIOR OF GAMMA TITANIUM ALUMINIDE ALLOYS DURING SUPERTRANSUS HEAT TREATMENT: S.L. Semiatin*, V. Seetharamann, D.M. Dimiduk*, Yow. Kim, K.H. G. Ashbee* *Wright Laboratory Materials Directorate, WLIMLLM, WrightPatterson AFB OH 45433; UES, Inc., 4401 Dayton-Xenia Rd., Dayton OH 45432
The transformation from y to a in a Ti-48Al alloy during aging in the a+y phase field between 1275-1350°C is reported using microhardness, optical, scanning and transmission electron microscopy. The results indicate that on heating a primary y structure to temperatures in the two-phase a+y phase field, packets of a nucleate within the y grains in four orientations parallel to the four (111}g planes. The a platelets generally nucleate at grain boundaries and stacking faults on {111) planes bounded by 116<112] Shockley partial dislocations appear to serve as nuclei for them. The a precipitation kinetics, volume fraction and packet thickness depend strongly on the aging temperature, generally increasing with increase in temperature. These changes are also accompanied by significant hardening with time at temperature, from the initial value to a maximum, followed by a decrease at longer times. The morphology of the resulting microstructures, nucleation mechanisms, orientation relationship between the phases, sub-structure development and kinetics of precipitation during the transition will be discussed.
Recent work has suggested that near-fully lamellar or fully-lamellar microstructures may provide attractive combinations of room and elevated temperature properties in near-gamma titanium aluminide alloys. The development of such microstructures via thermal processing high in the two-phase (alpha+gamma) field or in the single-phase (alpha) field is described. In particular, the interaction of the dissolution of gamma grains and the growth of alpha grains during isothermal and transient heat treatment processes will be summarized. Models for the kinetics of gamma grain dissolution and alpha grain growth will be presented. The broad application of such models for the design of heat treatments to obtain fully lamellar microstructures will be illustrated for several forged gamma components.
3:30 pm BREAK 3:50pm THE ORDERING TIE LINES AND TIE TRIANGLES IN TITANIUM ALUMINIDES: D.-H. Hou, H.L. Fraser, Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210
2:30pm THE ROLE OF THE a, PHASE IN ULTRAFINE LAMELLAR MICROSTRUCTURES DEVELOPED IN TWO-PHASE y-TiAlALLOYS: P.I. Maziasz, c.T. Liu, Metals & Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831- 6115
The site occupancies of alloying elements in yTiAI and the ordering states in orthorhombic titanium aluminides are investigated using the newly developed Ordering Tie Line (OTL) analysis. The OTL, which can represent the atom configuration in an ordered alloy in a graphical and intuitive way, is a parameter that is unique to ordered alloys. There are two properties of an OTL, one being its slope, indicating the trend for sublattice occupancy, and the other the compositional endpoints, corresponding to the compositions of the individual sublattices. The slope can be determined conveniently by Atom Location by Channeling Enhanced Microanalysis (ALCHEMI) experiments, whereas the compositional endpoints may be determined either from additional information concerning the ordering scheme or determined by other experiments/simulations. In the present study, compositional endpoints are determined by simulation using the dynamical theory of electron diffraction. The OTL analysis which was originally developed for ternary compounds has been further extended to quaternary systems such as TiAl with two alloying elements and ternary system with three sublattice sites such as the orthorhombic alloys based on Ti 2AINb. For the TiAI alloys, the effect of alloying elements of Nb, Cr, Mo and Mn on the OTL are determined and discussed. For the orthorhombic alloy, it will be shown how the ordering state can be described by the Ordering Tie Triangle (OTT), and how to measure the OTT by the ALCHEMI experiments. Since the OTL can provide a direct measure of the ordering state, it will be an important parameter for alloy design. This work has been supported by the US ONR, Dr. George Yoder as Program Manager.
y-TIAI alloys (i.e. Ti-47 AI-2Cr-2Nb (at. %)) have ultrafine fully-lamellar structures after processing or heat-treatment above the a-transus temperature; such structures produce outstanding high-temperature strength. The lamellar colonies consist of fine laths ofal and y phases, with 100-200 nm average lamellar spacings and 200-500 nm a,-a, spacings. Generally these structures are dominated by y /a 2 interfaces rather than y/yinterfaces, and they are relatively free of various structural defects often found in fully-lamellar structures. Aging studies of different alloys at 800-1 OOO°C indicates that dissolution of the fine a2 lamellae is one of the critical first steps that triggers instability and continuous coarsening of the overall lamellar structure during aging or creep. This paper focuses on detailed TEMIAEM characterization of the ~ component of the microstructure and how that information feeds into designing better TiAI alloys. Research supported by the U. S. Department of Energy, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Industrial Technologies, Advanced Industrial Materials (AIM) Program, and Assistant Secretary for Defense Programs, Technology Management Group, Technology Transfer Initiative, under contract DE-AC05-960R22464 with Lockheed-Martin Energy Research Corp.
47
4:10pm DECOMPOSITION OF 1-TIAII
GENERAL RECYCLING II: Practice
J. Zhang, Z.H. Zhang, D.x. Zou, Z. Y. Zhong, Central Iron and Steel Re-
search Institute, Beijing 100081, China
Sponsored by: Jt. EPDILMD Recycling Committee Program Organizers: James C. Daley, Daley & Associates, 1020 W. Cactus Wren Drive, Phoenix, AZ. 85021; John M. Rapkoch, Davy International, 2440 Camino Ramon, San Ramon, CA 94583
It's found in the cast Ti-46.5Al-2.5V-1.0Cr (at%) ingot, that the discontinuous coarsening (DC) dominates the decomposition of the lamellar structure when annealing at temperatures lower than l273K while the continuous coarsening (CC) does at the temperature between l373K and 1473K. In the case of CC, the lamellae coarsened segmentally and then the FL microstructure decomposed to a finer equiaxed near ganuna (NG) microstructure as annealing time went on. The TEM observation showed that the prior lamellae are quite neat and perfect and the annealed lamellae have inner terminations. Thus, the Rayleigh's perturbation and breakdown of lamellae was believed to have occurred along with the CC. Furthermore, a cycle heat treatment of 1173K1423K has been designed to increase the density of the inner terminations of lamellae. After that, the FL microstructure has been decomposed to a more homogeneous and even finer equiaxed NG microstructure.
Monday, PM February 10, 1997
Room: 230C location: Orlando Convention Center
Session Chairpersons: James C. Daley, Daley & Associates, 1020 W. Cactus Wren Drive, Phoenix, AZ. 85021; John M. Rapkoch, Davy International, 2440 Camino Ramon, San Ramon, CA 94583
1:30pm RECYCLING OF MAGNESIUM ALLOY SCRAP, A NECESSITY: Christine Brassard, Lisabeth Riopelle, Oddmund Wallevik, Hydro Magnesium Market Development Center, 21644 Melrose Avenue, Southfield, MT 48075-9705
4:30pm MICROSTRUCTURE EVOLUTION DURING POSTWELD HEAT TREATMENT OF GAS TUNGSTEN-ARC AND ELECTRON BEAM WELDS IN CAST Ti-48AI-2Cr-2Nb ALLOY: WA. Baeslack III, C.M. Jensen, H. Zheng, Department of Industrial, Welding and Systems Engineering, Ohio State University, Columbus, OH 43210; T.1. Kelly, GE Aircraft Engines, 1 Neumann Way, Evendale, OH 45215
The use of magnesium alloys is growing rapidly, particularly in die cast parts for the automotive industry. Supporting this growth in the future means that Mg has to be an economically and ecologically attractive material, and recycling of alloy scrap becomes a necessity. What kinds of magnesium scrap will be on the market? What are the opportunities and challenges for this emerging recycling industry? Different recycling processes have been developed, and operation facilities are today recycling large volumes of class 1 diecast returns based on a flux refining technology. Characterization of the recovered metal demonstrates that the performance of appropriately recycled magnesium alloy is comparable to an alloy made from primary electrolytic metal. The sludge generated from this process can also be recycled through the existing primary Mg operations in order to close the environmental loop.
The microstructures of multi-pass gas tungsten-arc (GTA) welds produced in cast Ti-48AI-2Cr-2Nb (at. %) have been evaluated in the as-welded condition and following postweld heat treatment over a range of temperatures from 1000 to 1300°C. Although postweld heat treatment did not significantly affect the cast, HIP' ed and heat-treated base metal microstructure, it did promote transformation of a predominantly lamellar 400 DPH as-welded) observed to parallel the fusion boundaries, which exhibited an extremely fine lamellar microstructure, were also softened by postweld heat treatment, although they remained harder than the surrounding weld metal microstructure. This work was supported by a grant to the Carnegie Mellon University from the Air Force Office of Scientific Research.
1:55pm INMETCO CADMIUM RECOVERY FACILITY: George Cingle III, INMETCO, 245 Portersville Road, Ellwood City, PA 16117; Gerald LaRosa, Davy International, One Oliver Plaza, Pittsburgh, PA 15222 The INMETCO Cadmium Recovery Facility currently processes commercial and industrial nickel/cadmium batteries at their Ellwood City, PA plant. The facility receives recycled nickel/cadmium batteries to recover cadmium shot product and nickel/iron scrap. The technology employed for the dismantling of industrial cells and the distillation of cadmium is under license from SAFf-NIFE in Sweden. In addition, INMETCO has installed a thermal pretreatment pilot unit for processing commercial and consumer cells which has recently demonstrated encouraging results. The INMETCO facility began detailed design in February 1995. The first cadmium distillation furnace was brought on-line December 1995, and the complete facility was operational April 1996. The facility can process 2450 short tons per year of industrial cells and 630 short tons per year of consumer cells. The facility design incorporated provisions for future expansion to allow INMETCO the ability to keep up with the forecasted growth of recycling nickel/cadmium batteries through the year 2000.
4:50pm INTERACTION BETWEEN TiAI AND AIN AT HIGH TEMPERATURES: Y. Paransky, E. Y. Gutmanas, Department of Materials Engineering, Technion, Haifa 32000, Israel In this work, interfacial reactions between TiAl intermetallic and aluminum nitride have been studied in the 800-1200°C temperature range. Titanium a1uminides are developing as a new group of materials for high temperature applications. Their load bearing capacity can be considerably improved by introducing high strength ceramic fibers, such as SiC or boron. Due to the high reactivity of Ti-containing materials, chemical interaction between fibers and TiAl matrix takes place at the processing and/or service temperatures resulting in deterioration of mechanical properties. Fibers can be protected by a thin coating layer which dissolves slowly enough to prevent the matrix from attacking the fiber during the composite lifetime. AlN is a possible choice for such a coating in Ti-containing matrices. Interfacial reactions between AIN and TiAI matrix have been studied using the diffusion couple approach. Phases growing at the interface between TiAl and AIN have been identified by XRD, SEMlEDS, AES and TEM; the kinetics of reaction layer growth has also been investigated. It has been found that AIN is more stable in TiAI than in pure Ti. In the latter case, the dissolution of AlN is faster due to the higher activity of Ti and high diffusivity or nitrogen in Ti.
2:20pm COPPER RECYCLING FROM INDUSTRIAL WASTE BY MATTE SMELTING: Kazuhiro Asai, Yasuhito Kawasaki and Junzo Hino, Nippon Mining & Metals Co. Ltd., Toranomon 2-10-1, Minato-ku, Tokyo 105, Japan Hitachi Refinery of Nippon Mining & Metals Co., Ltd. installed a reverberatory type recycling furnace in 1978 in order to treat the industrial wastes which contain metal elements such as copper, gold and silver. Waste materials and pyrite such as galvanizing sludge, hydroxide slime and dust, are smelted together, and sulfidized copper, iron and precious metals are transformed into matte and other metallic elements are oxidized into slag. This copper matte is transported to Saganoseki smelter, and copper and precious metals are recovered. Recently it became difficult to get pyrite economically because of the decrease of pyrite production. Therefore, new treating process of the liquid waste has been investigated at Hitachi. In this process, the sulfide or sulfate from the liquid waste are smelted as the sulfur source instead of pyrite.
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2:45 pm BREAK
GLOBAL EXPLOITATION OF HEAP LEACHABLE GOLD DEPOSITS II: Bioleaching of Refractory Ores
3:00pm THE SUBMERGED ARC FURNACE AND ITS APPLICATION IN THE NON-FERROUS RECYCLING INDUSTRY: Gero Rath, Mannesmann Demag, Huttentechnik MDH
Sponsored by: EPD Process Mineralogy, Precious Metals, Aqueous Processing Committees; Newmont Mining Corporation, Denver, CO Program Organizers: Donald M. Hausen, Consultant, 1767 S. Woodside Dr., Salt Lake City, UT 84124; David Dreisinger, University of British Columbia, Dept. of Metals & Materials Eng., 309-6350 Storres Rd., Vancouver, BC V6T 124, Canada; Richard Kunter, Advanced Science, Inc., 405 Irvine St., Suite 401, Lakewood, CO 80278; William Petruk, CANMET, 555 Booth St., Ottawa, Ontario J1A 081; Richard D. Hagni, University of Missouri-Rolla; Dept. of Geology & Geophysics, Rolla, MO 65401
Residues from the non-ferrous industry contain highly valuable metallic substances which make their recovery by thermal treatment desirable from the economic and environmental point of view. The electric slag resistance furnace, a variant of the submerged arc furnace is one which is used more frequently for these recycling purposes. In the last decade Mannesmann Demag has built and commissioned most of these furnaces. The paper will give an overview of the operational applications and characteristics based on the experience gained so far in lead and copper recycling.
Monday, PM February 10, 1997
3:25pm AUTOMATIC SORTING OF ALUMINUM PACKAGINGS FROM DOMESTIC REFUSE: G.J. Nijhof ea., Hoogovens R&D, P.O. Box 10.000, 19709 CA I1muiden, The Netherlands
Room: 231C Location: Orlando Convention Center
Session Chairpersons: Richard D. Hagni, Chairman, Geol.lGeophysics Dept., Univ. Missouri, Rolla, MO; Kenneth A. Brunk, Mineral Consultant, Former Vice President, Newmont Gold Co. Denver, CO
This work is part of a major European research project on the re-use of packaging materials in their post consumer state. The first stage of the recovering of aluminum from a waste stream is to free the non-ferrous metals with an Eddy Current machine. Previous research has given excellent results on the separation of aluminum from pre-separated packaging material. At this moment there were two reasons for a new test series: In the Netherlands all cities are obliged to collect the organic waste separately from the other waste, thus leading to a rest fraction with a high potential on aluminum. The newest generation Eddy Currents work with a higher separation efficiency. This report will discuss the results of these test series. The recovered aluminum is used for remelting trials in another sub-project of this research programme.
This address discusses how "Mineral Processing Technology" can playa major role in the life and profitability of a mining company. Examples of past and present technological breakthroughs and their impacts will be examined. Also, the future of processing technology will be emphasized.
3:50pm PILOT SCALE INVESTIGATION OF FLEXIBLE ALUMINUM PACKAGING BY THERMAL PRETREATMENT: H. Rossel, R. Pietruck, YAW aluminum AG, Research & Development, Georg-von-Bosselager-Strabe 25, 53117 Bonn, Germany; Y. Bertaud, Y. Caratini, Pechiney CRY, Vorreppe, France
2:35pm OPERATION OF NEWMONT'S BIOOXIDATION DEMONSTRATION PLANT AND PRODUCTION OF GOLD FROM LOWER GRADE REFRACTORY ORES: R.M. Perry, F.-P. Sawyer, A.J. Schindler, M.1. Shutey, Newmont Gold Company, Carlin, NV 89822; H.B. White, Newmont Metallurgical Services, Salt Lake City, UT 84108
Laminates with aluminum are typically combined with other materials like plastics, paper, etc. The aluminum content is considerably below 50%. Therefore the separation of the laminate partner by a thermal procedure before the melting process is a successful solution. The paper reports the practical experiences with a pilot equipment in the l00kg-scale. Additionally the numerical approach to simulate the thermal process is presented. This work is part of a major European research project (PACK-EE) on the re-use of packaging materials in their post consumer state. Preliminary information on this project can be found in Light Metals, 1996.
Test work on biooxidation pretreatment of low grade refractory gold has been ongoing at Newmont Gold Company since 1988, including laboratory testing and pilot biooxidation heaps (400 to 25,000 st). Metallurgical results of an oxidation process utilizing Thiobacillus ferroxidans have culminated in the design, construction and operation of a 780,000 ton bioxidation demonstration facility. The facility has processed 780,000 tons of refractory ore, using a batched process with separate pads for bioxidation and ammonium thiosulfate gold extraction. Siliceous sulfide refractory (SSR) and carbonaceous (CSR) ores are treated separately during biooxidation pretreatment unit operation. Procedures and results of grinding, agglomeration and pad biooxidation cycle (180 days) are followed by lime neutralization, and dumped on oxide leach pads, or stacked on the ammonium thiosulfate leach pad. Gold is leached with either cyanide for SSR ores or ammonium thiosulfate for preg-robbing CSR ores.
2:00 pm KEYNOTE THE ROLE OF PROCESS TECHNOLOGY AS A KEY BUSINESS UNIT: Kenneth A. Brunk, Minerals Consultant, and Former Vice President, Newmont Gold Company, Aurora, CO 80016
4:15pm REMELTING AND PURIFICATION OF ALUMINUM PACKAGING WASTE: G.H. Nijhof ea., Hoogovens R&D, P.O. Box 10.000, 1970 CA I1muiden, The Netherlands
3:00pm BIOLEACHING AND PROCESSING OF A REFRACTORY GOLD ORE: N.S. Lynn, Lyntek, Inc.; and W. Reid, U.S. Gold/Gold Capital, Denver, CO 80204
This work is part of a major European research project on the re-use of packaging materials in their post consumer state. Recovering aluminum from household refuse leads to a mix-up with other metals, e.g. copper and steel. The aluminum industry aims to make packaging materials from waste packagings. Therefore, a purification step is required during the remelting operation. This research is focused on the removal of excess iron from the melt. The technique used is the formation of intermetallic compounds of FeMn by adding Mn, followed by separating these intermetallics from the molten metal. Theoretical studies of the ternairy and quarternairy phase diagrams, using computer modeling, have predicted the possible limits of purification. After laboratory trials some large scale remelting experiments have been performed to study the applicability of this technique.
A new process has been developed to bioleach refractory gold ores to expose the precious metal values using Thiobacillus ferrooxidans bacteria. The ore is hosted in a limestone rock with secondary replacement of carbonaceous and pyritic minerals. Crushing, stacking, bioleaching, rinsing and neutralization have been completed in a 45-day total time cycle. The use of sulfuric acid operation, and concentrated Thiobacillus ferroxidans popUlation allows the short bioleaching cycle. The ore is then processed using conventional carbon-in-leach cyanide recovery techniques. 3:25 pm BREAK
49
3:35 pm OXYGEN DIFUSION INTO WET ORE HEAPS IMPEDED BY WATER VAPOR UPFLOW: RW. Bartlett, K.A. Prisbrey, Univ. ofIdaho, College of Mines and Earth Resources, Moscow, ID 83844-3025
2:20 pm INVITED DIRECT OBSERVATION OF CURRENT DISTRIBUTIONS IN TIDN SUPERCONDUCTORS USING MAGNETO-OPTIC IMAGING: T.H. Johansen, M.Baziljevich, H. Bratsberg, Department of Physics, University of Oslo, Box 1048 Blindern, 0316 Oslo, Norway; Y. Shen, P. Vase, NKT Research Center, Sognvej 11,2605 Brlilndby, Denmark
Natural bioxidation of shallow, refractory ore heaps, relying on gaseous oxygen diffusion from the heap surface is attractive because of its simplicity and potential low cost, especially without using a lined pad, which is possible if percolation of leachate through the heap is avoided. In this case, the excess oxidation enthalpy must be removed by water evaporation from within the wet ore heap, and the rising water vapor flux within it will impede the downward oxygen flux. An analysis of this process shows that for typical values of pyrite grades and limited temperature increases. In the ore heap, the oxidation rate and penetration into the heap is reduced to values between about 30 percent and 50 percent of those obtained when leachate percolation occurs and water evaporation is not significant mechanism of heat removal.
A thin film ofYBa2Cup'_B prepared by laser ablation and shaped by etching as a long strip was studied by magneto-optic imaging. The penetration of a perpendicular magnetic field was investigated in detail, and a model-independent method of determining the space-resolved current distribution was developed. The inverse magnetic problem, i.e., that of using a field map to derive the underlying current distribution, is formulated and solved analytically for the strip geometry. The observed current profile across the strip gives direct evidence for the assumptions made in the Bean model. Also other geometries were investigated, demonstrating the new application of magnetooptics as a tool to determine current flow patterns.
4:00pm ECONOMIC CRITERIA FOR CHOOSING BIOHEAP PRETREATMENT OF MIXED OXIDEIREFRACTORY GOLD ORE: Robert W Bartlett, Univ. of Idaho, College of Mines & Earth Resources, Moscow, ID 83844-3025
2:40 pm INVITED FABRICATION OF BIAXIALLY-TEXTURED TIDCK FILM Y-Ba-Cuo SUPERCONDUCTOR: V. Selvamanickam, M.S. Walker, P. Haldar, R S. Sokolowski, Intermagnetics General Corporation, Latham, NY 12110; A. Ivanova, A.E. Kaloyeros, State University of New York at Albany, Albany, NY 12222; D. E. Fenner, Fenner Engineering Associates, Simsbury, CT06070
Bioheap pretreatment of sulfidic refractory gold ore prior to cyanide leaching is a promising new technology, especially for low-grade ores that cannot be oxidized by pressure leaching or roasting. Ores containing both refractory and amenable gold require economic decisions whether, or not, to pretreat before cyanide leaching. This choice is more complex than familiar ore/waste cut-off grade decisions. Pretreatment may increase recovery but delays receiving revenue. An equation has been developed that computes a "critical cyanide leachable gold grade" for determining whether pretreatment will be profitable. If the ore's actual cyanide leachable grade, without pretreatment, is above critical grade, pretreatment will not pay. The parameters in this equation are: waste/ore cut-off grade, pretreatment yield, total gold grade, pretreatment operating cost and project's financial discount rate. Calculations are provided for use in mine development planning when bioheap pretreatment is an available option.
High current densities have been recently demonstrated at 77 K in thick film YBCO superconductor deposited on biaxially-textured metallic substrates. The effort at Intermagnetics has been directed towards the development of an industrially scaleable process based on biaxially-textured substrate technology. Biaxially-textured metallic substrates have been fabricated in long lengths with an average in-plane orientation better than 10° and an average out-ofplane orientation better than 7°. Buffer layers that are structurally and chemically compatible with YBCO have been deposited on the metallic substrates with a biaxial texture similar to that of the substrate. Metal-Organic Chemical Vapor Deposition (MOCVD) has been used for deposition ofYBCO since this technique enables a high rate of deposition that is not limited by line-ofsight. Stoichiometric, dense, and biaxially-textured films of YBCO superconductor have been successfully deposited by MOCVD on the biaxially textured substrates. This research was partially supported by the Department of Energy.
HIGH TEMPERATURE SUPERCONDUCTORS II:
veco and Hg-Conductor Development
3:00 pm INVITED HIGH CRITICAL CURRENT DENSITY TAPES BY EPITAXIAL DEPOSITION OF SUPER CONDUCTING THICK FILMS ON BIAXIALLY TEXTURED METAL SUBSTRATES: A. Goyal, D.P. Norton, M. Paranthaman, E.D. Specht, J.D. Budaj, D.M. Kroeger, D.K. Christen, Q. He, B. Saffian, EA. List, D.E Lee, S. Shoup, P.M. Martin, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6116
Sponsored by: Jt: EMPMD/sMD Superconducting Materials Committee Program Organizers: U. Balachandran, Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439; Paul J. McGinn, University of Notre Dame, Notre Dame, IN 46556 Monday, PM February 10, 1997
Room: 315A Location: Orlando Convention Center
A method to obtain long lengths of flexible, biaxially oriented substrates with smooth, chemically compatible surfaces for epitaxial growth of high temperature superconductors is reported. The technique uses well established, industrially scaleable, thermolllechanical processes to impart a strong biaxial texture to a base metal like Ni. This is followed by vapor deposition of epitaxial buffer layers (metal andlor ceramic) to yield chemically compatible surfaces for HTS film deposition. Substrates prepared using this method are referred to as Rolling Assisted Biaxially Textured Substrates (RABITSN). Epitaxial YBCO films grown using laser ablation on RABITS'" have critical current densities exceeding 7 x 105 Ncm2 at 77 K in zero-field and have field dependences similar to epitaxial films on single crystal ceramic substrates. The texture of the base metal has been achieved in lengths over I m and scaleable techniques are being pursued to deposit epitaxial multilayers. Deposited conductors made using this technique offer a potential route for the fabrication oflong lengths of high J, wire capable of carrying high currents in high magnetic fields and at elevated temperatures. Research sponsored by U.S. DOE under contract DE-AC05 960R22464.
Session Chairpersons: V. Selvamanickam, Intermagnetics General Corporation, Latham, NY; M.J. Kramer, Ames Laboratory, Ames, IA
2:00 pm INVITED CRITICAL CURRENT IN SMALL ANGLE GRAIN BOUNDARIES: C. S. Pande, RA. Masumura, Naval Research Laboratory, Washington, DC 20375-5343 It is now well known that even small angle grain boundaries (misorientation angle ~ 10) show drastic reduction in inter-grain critical current. Drawing upon on our previous work, we show that this reduction must be ascribed to the stress field in proximity of the dislocations forming the small angle boundary. The alternate view that the reduction is due to the presence of dislocation cores is investigated by calculating their size as a function of misorientation. We show that the concept though probably valid for large misorientation (9 ~ 10) leads to serious disagreement with experiments for small values (9 ~ 10).
a
3:20 pm INVITED TRANSPORT BEHAVIOR OF GRAIN BOUNDARIES IN YBa2Cu)O,a: ACOMPARISON BETWEEN THIN FILM AND BULK BI-CRYSTALS: D.J. Miller, Y.R Todt, M. St. Louis-Weber,* D.G. Steel, X.E Zhang, K.E. Gray, U. Balachandran*, Materials Science Division and *Energy Technol-
50
ogy Division, Argonne National Laboratory, Argonne, IL 60439
can form pinning sites in these materials, resulting in enhanced high field critical currents. Supported by U.S. Department of Energy, under Contract No. W-7405-Eng-82.
The structure and transport properties of grain boundaries in thin film and bulk bi-crystals ofYBa,Cu,07JJhave been studied in detail. The thin film bicrystals were prepared by sputter deposition onto SrTi03 bi-crystal substrates while the bulk bi-crystals were prepared by a dual-seeded melt textured growth process. The structures of these two types of grain boundaries can be very different: thin film boundaries typically exhibit meandering and impurity phases that extend through the thickness of the film while the bulk boundaries tend to be very straight and relatively free of impurity phases. A comparison of the transport behavior between these two types of boundaries will be presented and the implications of the similarities and differences will be discussed. This work was partially supported by the U.S. Department of Energy, Basic Energy Sciences-Materials Sciences, under Contract No. W-31109-ENG-38 and by the National Science Foundation through the Science and Technology Center for Superconductivity under Contract No. DMR 9120000.
4:50 pm INVITED THE EFFECT OF PROCESSING PARAMETERS ON Hg-1223 TAPE FABRICATION: R. Meng, Y.Wang, B. Hickey, KRoss, Y. Xue, C.w. Chu, Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932 We have developed a process to fabricate Hg-1223 tape on a metal substrate with a transition temperature of 130 K and a self-field critical current density of 2 x 1()4 Ncm' at 77 K However, the reproducibility of the tape is poor and weak links exist in the tape so prepared. We have therefore investigated the chemical stabilities, processing parameters, and Ni doping effect on the Hg1223 phase formation and grain growth. We found that doping can suppress the volatility of Hg in Hg-1223 and speed up the growth of Hg-1223. While Ni was found to be better than the other metal substrates tested it failed to retain its integrity for prolonged exposure to the processing conditions. Only a slight amount of Ni can be incorporated into the Hg-1223 grain, and it usually enters the Cu sites leadiing to a slight suppression of T,. Proper processing conditions to eliminate the diffusion of Ni to Hg-1223, while favoring the growth and alignment of the Hg-1223 tape, will be discussed.
3:40 pm BREAK 3:50 pm INVITED PROCESS OPTIMIZATION FOR YBCO THICK FILMS: l.S. Abell, T.C. Shields, J. Langhom, S.C. Watcham, School of Metallurgy and Materials, University of Birmingham, Birmingham B 15 2TT, UK
5:10pm PREPARATION OF HIGH-TEMPERATURE SUPERCONDUCTING SILVER-SHEATHED HgBa,Cu04+d TAPES: G.B. Peacock,' M. Khaliq,' G. Yang,'T. C. Shields,2 I. Gameson,' 1. S. Abell,2 andP. P. Edwards,' 'School of Chemistry, 2School of Metallurgy and Materials, The University of Birmingham, Edgbaston, Birmingham, B152TT,UK
Superconducting thick films are finding technological exploitation in various applications; for example as inductive components in power engineering designs such as fault current limiters, and as microwave devices like filters in cellular communications applications. For efficient performance in these different fields superconducting properties require optimisation with respect to different parameters such as critical current density (Jc) and surface resistance (Rs). The microstructural control to deliver these properties demands careful processing. Flux pinning additions, composition control, doping, and novel processings techniques have been employed to improve the characteristics of the films. Barrier layer technology to enable the exploitation of low dielectric loss and economically attractive alumina substrates has been studied. The relationship between processing, microstructure and superconducting behavior will be discussed.
We have produced silver-sheathed HgBa2Cu04+0 superconducting wires and tapes exhibiting a transition temperature of 96 K Progress in the synthesis of these tapes was achieved by packing the stoichiometric mixtures of oxides into the silver tubes, air-quenching the samples and the novel use of thermal cycling. Superconducting properties were assessed by SQUID and a.c. susceptibility measurements. Various routes have been adopted to optimize superconductivity in HgBa2Ca2Cu,08+0 tapes: these include packing superconducting Hg-1223 powders in tubes, mixing pre-formed materials with mixtures of oxides in different ratios, using precursors, etc. Phase purity, texture and morphology of samples has been investigated using XRD and SEM.
4:10pm MULTI-WAFERMANUFACTURINGOFLARGE-AREAYBCOTHIN FILMS FOR R.F. DEVICE APPLICATIONS: c.N. Soble, V.C. Matijasevic, Z. Lu, T. Kaplan, K von Dessonneck, Conductus, Inc., Sunnyvale, CA 95123
HIGH TEMPERATURE TITANIUM ALLOYS II
Scaling up PVD and CVD techniques to reasonable manufacturing levels has been a scientific and engineering challenge for companies developing HTS materials for commercial applications. In this paper, we discuss the process development and optimization work associated with ramping up a multi-wafer reactive co-evaporation deposition system capable of depositing high quality YBCO on 2" to 8" wafers (R-pl sapphire or LaAI0 3). YBCO thin films deposited using this technique exhibit good electrical properties with transition temperatures 85-87 K and Jc >2 x 106 Ncm' at 77 K Microwave surface resistance, Ro' is
Sponsored by: SMDTitanium Committee Program Organizers: R G. Rowe, M.F.X. Gigliotti, GE Corporate Research and Development, P.O. Box 8, K-1 MB103, Schenectady, NY 12301; D. Eylon, Univ of Dayton, Materials Engineering, K 1262, 300 College Park, Dayton, OH 45869; P.J Bania, Mgr. Quality and Technology, Timet, POBox 2128, Henderson, NV 89015 Monday, PM February 10, 1997
Room: 231B Location: Orlando Convention Center
Session Chairperson: P.J. Bania, Timet, P.O. Box 2128, Henderson, NV 89015
4:30 pm INVITED PHASE DIAGRAM AND CATION DISORDER STUDIES IN REl+xBaz.xCu30,+O' RE = Pr, Nd, Sm, Eu, and Gd: M l. Kramer, H. Wu, KW. Dennis, R.w. McCallum, Ames Laboratory, Iowa State University, Ames, IA50011
2:00 pm INVITED PHASE EQUILBRIA IN Ti-AI-Nb ALLOYS: K. Muraleedharan, Dept. of Materials Science & Eng., Carnegie Mellon University, Pittsburgh, PA 15213; D. Banerjee, Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500058, India
For the light rare earth elements, the orthorhombic REB
The phase equilibria in the technologically important Ti-AI-Nb ternary system are presented. Special emphasis is made in the composition regime where the Orthorhombic (0, Ti 2AINb, Cmcm) phase has considerable presence in the microstructures. Isothermal sections at temperatures at and above 700°C are presented along with three vertical section at 22.5, 25 and 27.5 atomic % Al levels. The difficulties experienced in determining the pha~e diagrams, arising out oflow diffusivities and the nature of the alph0 peritectoid transformation, are highlighted. The presence of a large solubility range for the single phase phase field close to an Al content 27.5% is discussed in the
°
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were found to be critical issues. Improvements in MMC transverse tensiJ e and creep strengths can be made by increasing the matrix properties throug h alloy chemistry modifications, as well as through microstructural manipula·· tion. This program, and others, have examined, in a systematic way, the ef.· fects of elemental additions, such as Mo, Ta, Si, V, and 0, on mechanical properties, environmental resistance, and processability of Ti-Al-Nb alloys. These efforts have led to the state-of-the-art MMC matrix orthorhombic titanium aluminide alloy. This work was supported by Contract F33615-91-C5647.
light of the experimental results. Finally a clear definition of the areas wherein there exists a lack in our current understanding of the Ti-AI-Nb system are highlighted. 2:30pm PROCESSIMICROSTRUCTUREIPROPERTY RELATIONSHIPS IN AN ORTHORHOMBIC TITANIUM ALUMINIDE ALLOY: A.P. Woodfield, GE Aircraft Engines, I Neumann Way, Cincinnati OH 45215; S.K. Srivatsa, V.K. Vasudevan, University of Cincinnati, Cincinnati, OH 45215
4:10pm THE EFFECT OF HEAT TREATMENTS ON THE MECHANICAL BEHAVIOR OF AN ORTHORHOMBIC Ti-ALLOY: S. Lutjering, D. Eylon, University of Dayton, Dayton, OH 45469-0240; P.R. Smith, Materials Directorate, Wright Laboratory, Wright-Patterson AFB, OH 5433-7817
An orthorhombic titanium aluminide alloy ingot with a nominal composition of Ti-22AI-26Nb (atom percent) has been produced and converted to 6" diameter billet. A continuous cooling transformation diagram was generated using compression samples, and TEM performed to understand phase evolution during cooling. A series of melts were· cut from the 6" billet and either forged into pancakes or rolled into rings using a variety of process routes. The effects of process variables and final heat treatment on the microstructure and mechanical properties of the pancakes and rings have been evaluated. Mechanical properties included tensile (room temperature to 1300F), creep (1000- 12oop), fracture toughness (room temperature) and fatigue (room temperature to 1200F).
Titanium aluminide alloys containing the ordered orthorhombic phase, based on Ti2AINb, are considered as potential materials for the compressor section of aerospace engines both in their monolithic form and as matrices in metal matrix composites. The microstructure (volume fraction of the ordered alpha-2, B2 and orthorhombic phases, grain size, lath size and spacing) has a significant effect on the mechanical properties of these materials. In this study two heat treatments of the orthorhombic alloy Ti-22AI-23Nb resulting in a fully transformed and a duplex microstructure were investigated. Room temperature and elevated temperature tensile and cyclic behavior including fatigue life, fatigue crack initiation and propagation will be discussed with respect to these microstructural conditions.
2:50pm THE ORDERING BEHAVIOR OF THE ORTHORHOMBIC PHASE IN Ti-AI-Nb ALLOYS: K. Muraleedharan, D. Banerjee, Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderbad 500058, India The ordering behavior of the orthorhombic (0, Ti2AlNb, Cmcm) phase are presented. The presence of the 0 phase in two distinct forms with different site occupations is discussed. They are (1) the 01 phase Nb atoms occupying the Ti sublattice randomly and (2) the 02 phase with a specific sublattice for the Nb atoms. Both 01 and 02 exhibit the same space group and lattice periodicity and this makes their identification from one another a difficult task. We present in this paper, the various diffraction effects which arise due to the different ordering behavior of the 0 phase, for both X -ray and electron diffraction. Specific reflections are singled out. A definition of the order parameter and its experimental determination are presented. Possible transitions between the two forms are presented in the spirit of the Landau-Lifshitz theory for order-disorder transformations.
4:20pm EFFECT OF MICROSTRUCTURE ON THE CREEP AND RT TENSILE BEHAVIOR OF 0+B2 ALLOYS: CJ. Boehlert, B.S. Majumdar, V. Seetharaman, UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432-1894 The phase evolution, room temperature tensile, and elevated temperature creep behaviors of Ti-25AI-25Nb and Ti-23AI-27Nb have been examined. A variety of microstructures, consisting of different volume fractions of B2 and 0 were achieved through deformation processing and heat treatments. Supertransus heat treated microstructures suffered from intergranular attack and exhibited low ductility. Subtransus heat treated microstructures exhibited a balance of RT tensile and elevated temperature creep performance. Creep samples showed evidence of microstructural instability, involving cellular/widmanstatten precipitation of 0 phase within the B2 grains. The kinetics of 0 phase precipitation at the creep temperature, 650°C, and the effect of this instability on creep are presented. In addition, overall effects of microstructural features on tensile, creep, and damage accumulation are discussed.
2:10pm EFFECT OF EXPOSURE ON FATIGUE OF COATED AND UNCOATED ORTHORHOMBIC Ti- ALUMINIDES: J.R. Dobbs, M.F.x. Gigliotti, GE CR&D, P.O. Box 8, K-l, MB105, Schenectady, NY 12301; MJ. Kaufman, Dept. Materials Science and Engineering, Univ. of Florida, 201 Rhines Hall, Gainesville FL 32611
4:40pm PRODUCTION OF HIGH TEMPERATURE TITANIUMALUMINIDE FOILS VIA PLASMA SPRAY PROCESSING: R.S. Thakur, Mohit Sisodia*, M.K. Bhargava, Materials Procurement Division, Hindhustan Motors Company, Indore, India; *Dept. of Metallurgical Engineering, Malaviya Regional Engineering College, Jaipur 302 017, India
Both uncoated and coated fatigue samples of the alloy Ti-22AI-26Nb were subjected to elevated temperature exposures in air. Oxygen ingress and interdiffusion (and reaction) of elements between coating and substrate cause changes in both microstructure and properties (i.e., embrittlement). After exposure, the microstructures ofthe substrate, the reaction zone and the oxidation products were examined, and fatigue tests were conducted. The suitability of selected coatings for protection of orthorhombic alloys against property degradation from exposure at elevated temperatures will be discussed.
Plasma Spray Forming is a upscaled version of droplet deposition method from the melt, which combines the steps of melting, rapid solidification, and consolidation into a single operation. The present paper critically reviews the versatility of this process which is successfully applied to the synthesis ofTi alloys and Ti- aluminide preforms for subsequent cold rolling into thin foils. These Plasma Sprayed preforms are transformed into dense wrought Tialuminide foils by a roll consolidation process. It has been observed that production of this dense foils are as continuous coil, which would improve process efficiency and yield high quality at low cost. Actually these high strength Ti alloys and Ti-aluminide foils are required for fabricating composite structures for advanced aerospace technology and space shuttles. In addition to it, various parameters are discussed which primarily includes designing of optimum interface, growth kinetics etc., and became necessary in enhancing service life of these foils at elevated temperatures.
3:30 pm BREAK 3:50 pm INVITED ORTHORHOMBIC TITANIUM ALUMINIDE ALLOY DEVELOPMENT: e.G. Rhodes, Rockwell Science Center, Thousand Oaks, CA; lC. Chesnutt, General Electric Aircraft Engines, Evendale, OH; J.A. Hall, Allied Signal Inc., Phoenix, AZ; J.R. Porter, Rockwell Science Center, D.A. Miracle, M.L. Gambone, Materials Directorate, USAF, Wright-PattersonAFB, OH The development of a Ti-based metal matrix composite (MMC) material, capable of sustained and repeated exposure to service temperatures in the range of 650°-760°C (1200°-I 400°F), has been undertaken in a U.S. Air Force sponsored program. Several performance characteristics qualify as "critical" for specific turbine engine component applications and service environments. To define these component-critical MMC characteristics, we selected a turbine engine compressor rotor, in which transverse tensile and creep strengths
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HUME-ROTHERY AWARD SYMPOSIUM FOR BRUNO PREDEL: Thermodynamics of Alloy Formation I: Experimental Measurement Sponsored by: Jt. EMPMD/SMD Alloy Phase Committee Program Organizers: Prof. VA Chang, Department of Materials Science & Engineering, University of Wisconsin, Madison, WI 53706-1595; F. Sommer, MaxPlanck-Institut fur Metallforschung, Inst. Fur Werkstowissenschaft, Seestrasse 92, 0-70174 Stuttgart, Germany Monday, PM February 10, 1997
Room: 330B Location: Orlando Convention Center
Session Chairman:V. A. Chang, Department of Materials Science & Engineering, University of Wisconsin, Madison, WI 53706-1595
2:00pm OPENING REMARK: Y.A. Chang, Department of Materials Science & Engineering, University of Wisconsin, Madison, WI 53706-1595 2:05 pm KEYNOTE CONSTITUTION AND THERMODYNAMICS OF MONOTECTIC ALLOYS: Prof Dr. B. Predel, Max -Planck-Institut fiir Metailforschung, Inst. fUr Werkstoffwissenschaft, Seestra~e 92, D-70 174 Stuttgart, Germany Many binary systems exhibit miscibility gaps in the liquid state. It is well known that melts which are passing a miscibility gap on cooling, solidify to a regular consisting of two layers. Such metallic solid bodies are not interesting for technical applications and have also scarcely been investigated scientifically. Genuine interest in demixing systems only arised as it seemed possible to prevent layer formation under zero gravity. However, experiments in space have shown that even under migro-g conditions, phase separation is occurring, yet in another way as on earth and also not finely dispersed. Afterwards, there resulted an intensive disclosure of the thermodynamics and the kinetics of the separation of liquid immiscible phases. After the discussion of the results obtained it is indicated how layer formation can be prevented and a finely dispersed structure can be realized in order to enable technical use. 2:50 pm INVITED ENTHALPY OF FORMATION OF LIQUID [TRANSITION METALsp METAL] BINARY ALLOYS: M. Gaune-Escard, 1.P. Bros, IUSTI-UMR 129, Universite de Provence, Centre de St-Jerome, 13397 Marseille, France With a fully automated high temperature calorimeter (Tmox = l800K) and using the direct drop method, the molar integral of formation of the binary liquid alloys (Ga and In with Fe, Co, Ni, Rh, Pd, Ir, and Pt) have been measured with an accuracy of about 6%. From these results the molar partial enthalpies have been calculated and the transfer of electrons from the sp-metal to the transition metal has been deduced. Moreover some liquidus points of the equilibrium phase diagram of these systems have been obtained. 3:25 pm BREAK 3:40 pm INVITED HIGH· TEMPERATURE THERMOCHEMISTRY OF INTERMETAL· LIC COMPOUNDS OF TRANSITION METALS AND RARE EARTH METALS WITH TiN: S.V. Meschel, 0.1. Kleppa, James Franck Institute, University of Chicago, Chicago, IL 60637 A wide range of intermetallic compounds of transition metals and rare earth metals with tin have been studied by direct synthesis calorimetry at 1473 ± 2K. The results provide a picture of the systematic dependence of the standard enthalpy of formation of the compounds on the number of 3d-, 4d- and 5d-electrons in the considered transition metals, and on the number of f-electrons in the lanthanide metals. The results will be compared with earlier experimental data, where available, and with predictions from the semi-empirical model of Miedema and co-workers.
4:20 pm INVITED APPLICATIONS OF EMF MEASUREMENTS IN THERMODY· NAMIC STUDIES: A. Mikula, Institut fiir Anorganische Chemie, Universitiit Wien, Vienna, Austria The use of emf measurements for the determination of thermodynamic properties of materials is reviewed. The development of a new galvanic cell techniques will be presented and their advantages and disadvantages in their application for certain problems will be discussed. There is a wide field for new applications of this technique like fuel cells, production of hydrogen, developments of new batteries, control of production processes and developments of new sensors. Scientific applications include kinetic measurements and studies of thermodynamic properties. This work will concentrate on the use of emf measurements of the thermodynamics of phase and reaction eqUilibria. 4:55 pm INVITED HEAT CAPACITY OF LIQUID ALLOYS: F. Sommer, Max-PlanckInstitut fUr Metallforschung, Institut fUr Werkstoffwissenschaft, Seestr. 75, D-70l74 Stuttgart, Germany Some specific features of the temperature and concentration dependence of the heat capacity C p of ordering or segregating liquid alloys will be discussed. Some recent experimental Cp-data (e.g. Al-La-Ni, Bi-Ga, AI-In) obtained using a new adiabatic calorimeter are presented. The ability of some models to describe the different characteristics of the CpCT,x)-course of liquid alloys is demonstrated. A direct connection between the thermodynamic properties of liquid alloys and the atomic transport properties like diffusion and viscosity will be described.
INTERNATIONAL SYMPOSIUM ON PROCESSING AND HANDLING OF POWDERS AND DUSTS II: Powder Handling and Instrumentation Sponsored by: Jt. EPDIMDMD Synthesis, Control, and Analysis of Materials Processing Committee, Powder Metallurgy, Reactive Metals, and Non·Metallic Materials Committees Program Organizers: Thomas P. Battle, DuPont, Edgemoor, DE 19809; Hani Henein, University of Alberta, Edmonton, AL; Gordon Irons, 1280 Main St West, Hamilton, Ontario L8S 4L7; John Moore, Colorado School of Mines, Dept. of Met and Matis, Golden, CO 80401; Beverly Aikin, CWRU - NASA LeRC, 21000 Brookpark Road, MS 106-5, Cleveland, OH 44135; Iver Anderson, Ames Laboratory, Iowa State University, 122 Metals Development Bldg, Ames, IA 500113020; John Pusateri, Horsehead Resources Development, Monaca, PA Monday, PM February 10, 1997
Room: Salon 6 Location: Clarion Plaza Hotel
Session Chairs: Hani Henein, Advanced Matis. and Proc. Lab, University of Alberta, 606 Chem-Min Eng. Bldg, Edmonton, AL T6G 2G6; Thomas Battle, DuPont White Pigments and Mineral Products, Edge Moor Plant, Edge Moor, DE 19809
2:00pm BENEFITS OF MEMBRANE SURFACE FILTRATION IN THE NON· FERROUS INDUSTRY: Christine E. Kafka, W L. Gore and Associates, Inc., 101 Lewisville Road, P.O. Box 1100, Elkton, MD 21922-1100 Stricter particulate emission regulations and the competitive requirements to produce metal as economically as possible are driving the non-ferrous pro· cessing industry to focus on cleaner and more efficient technologies. One area of interest is the air cleaning systems. Presently, there are many different air filtration technologies employed by the industry. Fabric filtration systems with expanded polytetrafluoroethylene (ePTFE) membrane filters are increasingly being chosen to provide optimum performance over conventional depth filtration. The selection of filtration technology greatly affects the performance of the baghouse and process. The ePTFE membrane surface filtration provides consistently higher airflow and longer filter life, while also providing the additional benefit of the lowest particulate emission of any fabric filtration media. Membrane filtration provides these benefits in concentrate drying, primary and secondary smelter and converter baghouses, with case histories around the world.
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2:25pm
3:40pm
PHYSICAL EXAMINATION AND HANDLING OF WET AND DRY C 60, K. Lozano l , X. Sheng', A. Gaspar-Rosas', F. Chibante', E. V. Barrera', 'Rice University, Dept. Mechanical Engineering and Materials Science, P. O. Box 1892, Houston, TX 77251; 'Paar Physica USA, Houston, TX 773888909; 'Nanotechnologies of Texas, Houston, TX 77081
A STUDY OF THE MECHANISMS OF POWDER ENTRAPMENT IN PACKED PARTICLES: D. Pinson', A.B. Yu l , P. Zu1li2, M. J. McCarthy'. 'School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, Australia; 2BHP Research - Newcastle Laboratories, P.O. Box 188, NSW 2287, Australia
The structure-property relationships of C 60 dissolved in decahydronaphtalene (decalin) and a petroleum solvent viscous standard (PSVS) were studied. This work was motivated mainly by the interest to improve fullerene dispersion in powder processing by wet methods. Measurements of solubility, density, viscosity and elasticity were conducted varying the concentration level of C6(j' A Decalin solution was mixed with Cu powder and the Coo dispersion and Cu grain-size growth were evaluated. Decalin can dissolve 1.9 mg/ml of Coo while the PSVS dissolves 0.15 mg/ml. The viscosity behavior shown by both solutions was Newtonian, with a small increase in viscosity as a function of fullerene concentration. The elastic portion of the solvents did not change with fullerene concentration. The samples prepared by wet methods showed less Coo agglomerates. This presentation will also emphasize the aspects of handling the fullerene powder in wet and dry methods. This work was supported by National Science Foundation DMR-9357505.
Gas-powder-liquid multiphase-phase flow in packed beds can be found in many industrial applications. One typical example is the flow in the lower part of a modem ironmaking blast furnace with high pulverised coal injection, which includes an upward flow of gas and (unburnt) coal and downward flow of liquid iron and slag in a coke bed. Understanding the mechanisms governing the powder entrapment in packed particles is an important step toward the modelling of such a flow system. This paper presents a study of the mechanisms through a model experiment in which the form and volume of deposits, i.e. the entrapped powder, can be visualised. It is found that the contact point between particles plays an important role in capture of powder, and the presence of a liquid may significantly increase the powder entrapment and lead to a dramatic increase in gas pressure drop. The effects of variables relevant to the blast furnace process, such as liquid properties, gas, powder and liquid flowrates, and the size ratio between (flowing) powder and (packed) particle have been studied, and correlations have been formulated for modelling purposes.
2:50pm ON THE IMPROVED FLOWABILITY OF COHESIVE POWDERS BY COATING WITH FINE PARTICLES: R. Mei l , J.F. Klausner', H. Shang', and E. Kallman', 'Department of Aerospace Engineering, Mechanics, and Engineering Science 2I)epartment of Mechanical Engineering, University of Florida, Gainesville, FL 32611
4:05pm RECENT DEVELOPMENTS IN THE TECHNIQUE FOR CHARACTERIZING THE SHAPE, SIZE, AND TEXTURE OF METAL POWDER GRAINS: B.H. Kaye l , L. C. Paquette', 'Professor of Physics, 'Research Associate, Department of Physics, Laurentian University, Sudbury, Ontario, P3E 2C6
Poor flow ability of cohesive powders is the source of frequent concern in powder handling in many industrial processes. Coating of fine particles on the surface of primary powder particles can be applied to improve powder flowability. In this paper, we examine quantitatively the effect of coating fine particles on the cohesion force between primary powder particles by extending the JKR theory to include the effect of coating particles on the forcedisplacement relationship. It is shown that the cohesion force between two primary powder particles in the presence of a fine coating particle is directly proportional to the size ratio of the coating particle to the primary powder particle resulting in a drastic reduction in the cohesion force. Through discrete element simulation of powder flows the improved flowability is demonstrated. The effect of coating on improving the flowability is also quantified by comparing the measured angles of repose at a static condition and the flow rates of the gravity driven flow through a funnel for powders with and without particle coating.
Computer image analysis continues to develop rapidly and the falling costs and increasing power of personal computers make it possible to characterize the shape, angularities and, for rough texture powder grains, the fractal dimensions. New data on the characterization of various types of metal grains will be presented. Assessment of the size distribution of powders using diffractometers and time of flight spectrometers is making it possible to characterize the shape and size of metal powder grains in real time. Again, new data demonstrating the utility of this type of information for the powder metaurgist will be presented. Some of the newer size characterization equipment uses small quantities of powder samples and new procedures for taking representative samples from free fall tumbler mixers will be reviewed and sampling data presented.
4:30pm 3:15pm
CHARACTERIZING THE FLOW OF METAL POWDERS USING THE CONCEPTS OF FRACTAL GEOMETRY AND CHAOS THEORY TO INTERPRET THE AVALANCHING BEHAVIOR OF A POWDER DEPENDENT ON POWDER GRAIN CHARACTERISTICS: B. H. Kaye l , L.C. Paquette', 'Professor of Physics, 'Research Associate, Department of Physics, Laurentian University, Sudbury, Ontario, P3E 2C6
POROSITY CALCULATION OF PARTICLE MIXTURES: Z.P. Zou', A. B. Yu l , P. Zulli> , School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, Australia; 'BHP Research Newcastle Laboratories, P. O. Box 188, NSW 2287, Australia A packing of particles is an assemblage of particles and is widely encountered in many industries. Porosity or packing density is known to be the simplest and most accessible parameter in characterising particle packing. It is very useful to develop a method for predicting the porosity and related packing properties of particulate mixtures for property and/or process control. Particle characteristics affect porosity mainly via three factors: (dimensionless) particle size distribution, particle shape and absolute particle size, giving various packing systems from the simple (coarse) spherical particle packing to the complicated system involving fine and non-spherical powders. Consequently, the modelling of the relationship between porosity and particle characteristics may be carried out by considering these three factors. This paper presents a mathematical model developed on the basis of some simple and physically sound concepts in this direction, with examples provided to confirm its applicability.
The avalanching behavior of a portion of powder in a slowly rotating disc can be related to the flow behavior of powder in processing equipment. To interpret the observed avalanching behavior a new data processing procedure has been developed which permits instant visual recognition of shifts in the flow behavior. This can be caused by changes in powder grain structure; additives (such as glidants) and changes in ambient properties (such as humidity). Data on these four metal powders of different size, shape and texture will be presented.
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!''M?
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3:00pm RHENIUM RECOVERY FROM NON-TRADITIONAL RESOURCE: AM. Chekmarev, I.D. Troshkina, D. Mendeleyev, University of Chemical Technology of Russia, Miusskaya Sq. 9, Moscow 125047, Russia
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INTERNATIONAL SYMPOSIUM ON RHENIUM AND RHENIUM ALLOYS II: Extraction and Recycling of Rhenium
About 50% world resource of rhenium is found in non-traditional carbonbased resource. The search of rhenium occurrence and the study of rhenium distribution in high-viscous oil, native bitumen and oil shale processing are performed by the radiotracer and kinetic methods of analysis. The productsconcentrate of rhenium are determined. Methods of rhenium recovery from the processing products including hydrometallurgical techniques are developed. Sorption methods are worked out for rhenium recovery from additional resource; waste water, intermediate products in processing of various types of source etc.
Sponsored by: SMO Refractory Metals Committee and MOMO Powder Materials Committee Program Organizer: Dr. Boris D. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036 Monday, PM February 10, 1997
Room: 232C Location: Orlando Convention Center
Session Chairpersons: Dr. A.M. Chekmarev, D. Mendeleyev University of Chemical Technology of Russia, Miusskaya Sq. 9, Moscow 125047, Russia; Tom A. Millensifer, Powmet, Inc., 2625 Sewell St., P.O. Box 5086, Rockford, IL 61125
3:20 pm BREAK 3:40pm RHENIUM AND OSMIUM RECOVERY FROM SULFURIC ACID SCRUB SOLUTIONS: I.D. Troshkina, AM. Chekmarev, A.B. Mayboroda, D. Mendeleyev University of Chemical Technology of Russia, Miusskaya Sq. 9, Moscow 125047, Russia
2:00pm EXTRACTION OF RHENIUM FROM MOLYBDENITE CONCENTRATES: Mahesh C. lha, William A. May, Entech Molybdenum Inc., 5950 McIntyre Street, Golden, CO 80403-7499
The presence ofradiogenic osmium-187 formed by by-fussion of rhenium187 is the specific characteristic of some rhenium -containing source. The technology for the recovery of rhenium and osmium from sulfuric acid scrub solutions formed by wet gas purifying in pyrometallurgical processing of sulfide polymetallic ores was developed. The technology is based on extraction and sorption techniques following preliminary conversion of the metals into the optimal chemical species. The technology ensures quantitative recovery, concentration and separation of rhenium and osmium, production of commercially viable concentration of the elements.
By-product molybdenite concentrates from copper mines are the most important source of rhenium. The rhenium content is low, generally in the few hundred ppm range. Almost all of these concentrates are roasted to technical grade molybdic oxide, the most common molybdenum product sold commercially. Rhenium oxide is volatilized at high roasting temperatures and condensed downstream at lower temperatures, eventually reporting to the scrubber liquor as a dilute solution. This paper reviews several hydrometallurgical approaches that have been used commercially and for researched and recommended to recover the rhenium from such dilute solutions. The methods include ion exchange, solvent extraction, selective leaching/precipitation, and crystallization for concentration and purification steps. Ammonium perrhenate is typically the end product.
4:00pm RECYCLING OF RHENIUM: D.V. Drobot, V.I. Bukin, Moscow State Academy of Fine Chemical Technologies, Pr. Vemadskogo 86, 117571 Moscow, Russia
2:20pm A DATABASE APPROACH TO THE RECYCLING OF RHENIUM: Laird G.L. Ward, Noble and PGM Recycling Representation, 23 Longview Road, E. Fallowfield, Coatesville, PA 19320-4311; David P. Dillard, Research Librarian, Paley Library, Temple University, Philadelphia, PA
The aim of the investigation is the generalization of the published results according of rhenium extraction from secondary materials. Such materials can be classified as binary WoRe and Mo-Re alloys; several composition NiRe alloys; Al-Pt-Re catalysts and other Re-containing secondary products. The range of technological processes is very mice and depends on forms and Re concentration in secondary materials. For Re extraction from binary alloys can be used processes including interaction with KNO, or oxidation. In the last case it may be obtained volatile Re207. Purification can be done by rectification Rep7' The full extent of Re extraction from such materials is 92-94%. Combination of the chlorination process with solvent extraction allows to obtain Re metal with extent of extraction -92%. Re can be obtained from Mo-Re, WoRe alloys by means of electrochemical process (alkali solutions) or H:SO. solutions (Ni-Re alloys). For the production of the pure Re products it's necessery to use combination with solvent extraction or sorbtion. Complex Re and Pt extraction metals from AI-Pt-Re containing catalyst is the most important problem. There are known two methods, which differ at the first step: annealing with Na2CO, or annealing in oxidation atmosphere are possible. Extents ofRe and Pt extraction are 90 and 92%.
Since its discovery by the German investigators W. Noddack, Ida Tacke and 0. Berg in 1925 and, at about the same time, by the Czechs 1. Heyrovsky and V. Dolejsek, and the British investigators 1.G.E Druce and EH. Loring, rhenium, element of atomic number 75 has gradually established a niche for itself in the industrial world. With the technology of rhenium now well established, its further technical progress may be impeded for the lack of a ready means to recover it from scrapped sources. This conference, being the next to follow the Rhenium Conference in 1963, affords an opportunity to review the approaches published for the recovery of the element rhenium from some of the diverse products in which it has played a unique and very special role. 2:40pm CHEMICAL PROCESSING OF SPENT Pt-Re CATALYST FOR Re RECOVERY: Mahmoud I. ElGuindy, Gemini Industries Inc., 2311 South Pullman Street, Santa Ana, CA 92705
4:20pm BEHAVIOR & RECOVERY OF RHENIUM DURING THE CONVERSION OF MOLYBDENUM CONCENTRATES AND MISCELANEOUS TYPES OF THE SECONDARY RAW MATERIALS: N.N. Rakova, L.V. Miakisheva, KN. Yegorychev, V.S. Strizhko, The Moscow State Institute of Steel & Alloys, Moscow, Russia
Annually, over 5 million lbs of spent Reformer Catalysts are treated for the recovery of contained Platinum and Rhenium. In this publication a summary of available technology and methods employed for the processing of spent Pt-Re Catalyst will be discussed. Special emphasis will be on Rhenium recovery, purification and production of Catalytic Grade Ammonium Perrhenate. Furthermore, the factors influencing the chemical processing, the residence time and the purity of products in addition to metal accountability will be discussed. Recommended actions to be taken by petroleum processors to assist and facilitate recovery operations will also be presented.
The definite works to create scientific foundations and the technology for the recovery of rhenium from the primary and secondary raw materials were initiated in the 60's at the Chairs of the rare-earth metals & powder metallurgy led by the Distinguished Metallurgist of Russia, professor AN. Zelikman. 1. The molybdenum concentrates- one of the prime sources to recover rhenium along with the sulfide copper and copper/moly raw materials. The researches have been tested to investigate a behavior of rhenium during roasting process of the molybdenum concentrates and during the attack by the nitrogen acid.
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2. The researchers have been tested with form and mechanism of extraction of molybdenum and rhenium from sulfur acid and nitrogen/sulfur acid solutions of different compositions. During the elaborations of the extraction methods of distribution and the recovery it has been taken into account the differences in the forms of molybdenum and rhenium presence in the acid atmospheres and it has been suggested to utilize the neutral, anion- and cation exchange extragents. 3. The processes of the deep cleaning of the rhenium combination through trihydroxychloride, having the below melting and flashing temperature have been developed. The purity of the recovered ammonium perrhenate and metallic rhenium is exceeding their purity during the production and refinery by the other methods. 4. Some methods have been tested to regenerate rhenium, tungsten, molybdenum from the wastes of WRe & Mo-Re alloys with further treatment of the mixtures of chlorides of tungsten and rhenium by the water with the presence of oxidant and oxidation of alloys by means of oxygene and sublimation of rhenium oxide.
This study presents results of texture and microstructural development in AI-Li 2195 alloy processed by near-net-shape roll forging method. The manufacturing technique is a multi-stage process that combines conventional ingot conversion, back extrusion, and ring rolling to produce a heavy walled cylindrical forging preform. The preform is then rolled to near-final diameter using contoured rolling mandrels. A combination of optical microscopy, Orientation Distribution Function (ODF) and Orientation Imaging Microscopy (OIM) was used in this investigation. At the early stage of processing, (110) fiber texture was predominant. Following the second stage of processing, the texture was similar to characteristic fcc rolling texture. At the conclusion of processing, {OO 1 }<11 0> and {112} < 110> shear components were developed at the expense of Brass! component. The possible mechanisms responsible for the texture changes are discussed in relation with the microstructural evolution. 2:25 pm ALLOY COMPOSITION EFFECT ON THE GLASS FORMING ABILITY AND THERMAL STABILITY OF THE A~Mm4NilO.xFe. AMORPHOUS ALLOYS: H.W. Jin, Y.J. Kim, e.G. Park, Center for Advanced Aerospace Materials, Pohang Univ. of Sci. & Tech., Pohang 790-784, Korea; M.e. Kim, Research Inst. of Industrial Science and Tech., Pohang 790-600, Korea
4:40pm RHENIUM RECOVERY FROM SECONDARY RAW MATERIALS OF VARIOUS TYPES: A.Y. Elutin, M.Y. Istrashkina, Z.A. Peredereeva, State Research Centre-State Institute of Rare Metals-GIREDMET, 5 B. Tolmachevsky Per., Moscow 109017, Russia This report submits data of high-efficiency methods for rhenium recovery from secondary raw materials of various types, such as exhausted platinumrhenium catalysts and scrap of rhenium-containing molybdenum, tungsten and nickel based alloys. Developed methods are used on a commercial level at industrial enterprises of Russia and CIS. A process for selectively recovering rhenium from exhausted Pt-Re catalysts includes next steps: roasting, acid- or alkali-assisted leaching, ion-exchange recovery or rhenium from the solution and preparing high-purity ammonium perrhenate (99.99%). Results of developing commercially applicable methods are useful for rhenium recovery from scrap of rhenium-containing alloys.
Amorphous aluminum alloys show an attractive combination of high tensile strength and low density. The commercial applications of these alloys, however, have been restricted due to relatively poor thermal stability and glass forming ability (GFA). The GFA and the thermal stability of AI86Mn 4Ni,().,Fe, alloys have been investigated with various alloy composition. Amorphous ribbons with the thickness from 20pm to 30!J,m were prepared by single roll melt-spinner. The microstructural evolution upon heating was observed by using X-ray diffraction and transmission electron microscopy (TEM). The GFA of the present alloys decreased with the increase of Fe content. However, the first (lowest) crystallization temperature, T d , increased with increasing Fe content. The effects of alloy composition on the GFA and the thermal stability will be discussed in terms of the atomic bonding and electronic structure of the amorphous alloy.
5:00pm DETERMINATION OF RHENIUM BY RADIOTRACER METHODS OF ANALYSIS: I.D. Troshkina, A.M. Chekmarev, Y.I. Shamaev, D. Mendeleyev, University of Chemical Technology of Russia, Miusskaya Sq. 9, Moscow 125047, Russia
2:50pm EFFECT OF STRETCHING PRIOR TO AGING ON MECHANICAL PROPERTIES Al-Cu-Li (2195) ALLOY: Z.x. Li 1, R A. Mirshams I, E.A. Kenik2, P.J. Hartley' ;'DepartrnentofMechanical Engineering, Southern University, Baton Rouge, LA 70813; 2Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831; 3Lockheed Martin Manned Space Systems, New Orleans, LA 70189
Radiometric correction and interpolation methods have been worked out for rhenium determination with extraction of the tetraphenylphosphonium complex into dichlorethane. Radiotracer I88Re (16,9 h) is obtained in IB8Re-gen_ erator which is a glass column filled with aluminium oxide with a parent isotope 18BW (69, 4 d) adsorbed firmly. The isotope I88Re formed is eluted from the generator by 0,9% solution of sodium chloride. Liquid scintillation counting was used. The method allows to determine from 1 to 100 mg of rhenium (VII) in analyzed probe. The relative standard deviation is 0.05-0,09 over the whole concentration range.
TheAI-Cu-Li (2195) alloy was stretched uniaxially from 0% to 15% of pIastic deformation prior to aging. The tensile properties of naturally and artificialy aged specimens in 0, 45, and 90 degrees with respect to the pre-stretching direction were evaluated and their microstructures were characterized via TEM. The results indicated that the naturally aged specimen exhibited mainly 0' (AI3Li) precipitates whose size appeared to be insensitive to pre-stretching. The moderate increase in yield strength by pre-stretching was attributed to work hardening effect. On the other hand, it was found that the precipitates of the artificially aged (at 180°C) specimen were primarilyT, (AI2CuLi) phase. The size of the T I precipitates decreased with increasing amount of pre-su'etching. A pronounced increase in yield strength by pre-stretching was observed with the presence of fine TI precipitates. The relationship between mechanical properties and microstructures will be discussed. This work was sponsored partially by the Louisiana Board of Reagent and DOE-SHaRE program at Oak Ridge National Laboratory.
LIGHT WEIGHT ALLOYS FOR AEROSPACE APPLICATION IV: Session II: AI Alloys Sponsored by: SMD Non-Ferrous Metals Committee Program Organizer: Eui W. lee, W.E. Frazier, Code 4342, Naval Air Warfare Center, Patuxent River, MD 20670; K. Jata, WUMllM, WPAFB, OH 45433; N.J. Kim, Center for Advanced Aerospace Materials, POSTECH, Pohang, 790-784, Korea Monday, PM February 10, 1997
Room: 330A location: Orlando Convention Center
3:15 pm CONTROL OF PROPERTIES BY RE (RARE EARTH METALS) ADDITION IN HIGH Mg CONTAINING Al ALLOYS: S.D. Park, lH. Jung, H.K. Cho, Departments of Metallurgical Engineering, Kyungpook National University, Taegu 702-701, Korea
Session Chairperson: W.E. Frazier, Code 4342, Naval Air Warfare Center, Patuxent River, MD 20670
2:00pm THE DEVELOPMENT OF TEXTURE IN AI-Li 2195 ALLOY DURING RING ROLL FORGING: Lan Zhang, Peter N. Kalu, Department of Mechanical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL32310
Recently, there is a great deal of interests in AI-Mg alloys due to their good combinations of strength and formability. To further improve their properties, high Mg containing Al alloys have been studied although serious problems associated with the precipitation of ~ (Mg 5AI B), such as low thermal stability and poor corrosion resistance, are generated with higher Mg concen-
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tration. In the present study, changes in ~ precipitation behavior and mechanical properties by RE addition in high Mg containing Al alloys have been investigated. It has been shown that the precipitation of ~ phase is restrained and mechanical properties are improved by RE addition. 3:40pm EFFECT OF COMPOSITION AND TEMPERATURE ON THE STRENGTH AND FRACTURE TOUGHNESS OF AI-Cu-Li-Ag ALLOYS: Cynthia L. Lach, NASA Langley Research Center, Mail Stop 188A, Hampton, VA 23681; Richard P. Gangloff, Department of Materials Science and Engineering, Thornton Hall, University of Virginia, Charlotttesville, VA 22903 The use of AI-Cu-Li-Ag-Mg-Zr alloys for fabricating aerospace vehicle components can potentially reduce system weight. For damage tolerant analysis, it is important to characterize and understand alloy strength and fracture toughness, particularly as affected by minor changes in composition and test temperature. The uniaxial tensile deformation, plane strain fracture toughness, and plane stress tearing resistance of two precipitation hardened alloys, AA2095 andAA2195, were examined as a function ofCu and Li levels and temperature from -185 a C to 135°C. As temperatures decreased, the crack initiation toughness of AA2095 declined mildly while the toughness of AA2195 increased mildly. Alloy AA2195 demonstrated superior toughness in all cases. For each alloy the elastic modulus, yield strength and work hardening coefficient increased with decreasing temperature, while ductility declined from 135°C to -185 a C. A plastic strain-critical distance-based micromechanical model utilized these properties to predict that K1C1 increased mildly with declining temperature for each alloy. The slope of this trend was in good agreement with measurements for AA2195, but less so far AA2095. In all cases fracture occurred without delamination and by microvoid nucleation, growth and coalescence involving second phase particles which were particularly large in the higher CulLi variant (AA2095). This difference, along with separate relationships between nearest-neighbor particle spacing and the critical microstructural distance from the model explain the higher toughness ofAA2195. 4:05pm EFFECT OF Be ADDITION ON THE PRECIPITATION AND MECHANICAL PROPERTIES OF AI-Cu-Li-Mg-(Ag)-Zr ALLOYS: D. S. Chung, S. H. Cho*, H. K. Cho*, Dept. of Metallurgy, Changwon Industrial Master's College, Changwon 641-772, KOREA; * Dept. of Metallurgical Engineering, Kyungpook National University, Taegu, 702-701 The effect of Be addition on the precipitation and mechanical properties of Al-Cu-Li-Mg-(Ag)-Zr alloys has been investigated by detailed transmission electron microscopy and hardness and tensile tests. It has been shown that the Be addition accelerates the aging response and improves the ductility while maintaining the strength of Al-Cu-Li-Mg-(Ag)-Zr alloys. Such improvements in mechanical properties are due to changes in precipitation behavior of AICu-Li-Mg-(Ag)-Zr alloys by Be addition. 4:30pm MICROSTRUCTURAL EVOLUTION AND GRAIN DISTRIBUTION IN SUPERPLASTICALLYFORMED AI-Li 8090 ALLOY: Peter N. Kalu, H. Garmestani, Department of Mechanical Engineering, FAMU-FSU College of Engineering, 2525 Pottsdamer St., Tallahassee, FL 32310 With the advent of new analytical tools to study microstructures and microtexture, it is now necessary to re-characterize materials with complex structures. Using Orientation Imaging Microscopy (OIM), several microstructural parameters were obtained for superplastic AI-Li 8090 alloy deformed in tension. Grain orientation and distribution as well as the effective grain size based on standard definition of large angle grain boundaries were determined as a function of strain. The data was correlated with various models for superplasticity. The implications of the results on the deformation mechanisms operating during superplastic deformation is discussed. 4:55pm DISLOCATION STRUCTURES PRODUCED DURING HIGH TEMPERATURE DEFORMATION OF AI-LiAA8090ALLOY: W Fan, M.e. Chaturvedi, Department of Mechanical and Industrial Engineering, University of Manitoba Winnipeg, Manitoba, Canada, R3T 2N2; N.C. Goel, N.L.
Richards, Bristol Aerospace Ltd, Winnipeg, Manitoba, Canada, R3C 2S4 Deformation microstructures of an aluminum-lithiumAA8090 SPF grade sheet have been studied by TEM. The alloy was deformed in tension at the superplastic deformation temperature of 530°C and at a strain rate of lxl()-3/sec. The tensile testing machine was fitted with a specially designed in-situ water quenching apparatus to preserve the deformation microstructure produced at the temperature of testing. The TEM thin foils were made from samples deformed and in-situ quenched from different strain levels. Most of the thin foils were prepared with the surface parallel to the through thickness crosssection of the sheet, rather than parallel to the rolling plane. Dislocation pairs and dislocation networks were observed in the deformed samples even when deformation was as large as 475%. The observed characteristics of dislocation configuration suggest that dislocation interactions take place during superplastic deformation, in which grain boundary sliding is considered to play a dominant role and the role of dislocations is mainly to accommodate grain boundary sliding. In this paper, the possible implications of dislocation interactions and the mechanism of superplastic deformation in aluminum-lithium alloy AA8090 are discussed.
MATERIALS, COATINGS AND PROCESSES FOR IMPROVED RELIABILITY OF HIGH TEMPERATURE COMPONENTS II: Materials and Process II Sponsored by: SMD High Temperature Materials Committee Program Organizers: Dr. N.S. Cheruvu, Southwest Research Institute, 6220 Culebra Road, San AntoniO, TX 78228; Dr. K. Dannemann, GE Power Generation Engineering, One River Road, Schenectady, NY 12345 Monday, PM February 10, 1997
Room: Salon 3 Location: Clarion Plaza Hotel
Session Chairman: Dr. K. G. Kubarych, Solar Turbines, 2200 Pacific Highway, P.O. Box 85376, San Diego, CA 92186
2:00pm MODELING ENGINE COMPONENT CREEP DEGENERATION: A.K. Koul, X.J. Wu, Structures and Materials Propulsion Laboratory, Institute of Aerospace Research, National Research Council of Canada, Ottawa, Ontario, Canada KIAOR6 The paper presents a mechanistic approach to modeling creep degeneration of superalloy components with a view to developing residual life prediction algorithms. In accordance with the deformation decomposition rule: E ~ Eg + Egb" we classify degeneration mechanisms into two categories: 1) grain boundary deformation controlled degeneration mechanisms, including grain boundary sliding (GBS), cavitation and GBS assisted oxidation; and 2) intragranular deformation controlled degeneration mechanisms. The evolutionary creep equation for each strain component is thus mechanism-based. Generally, GBS is responsible for the transient, while intragranular deformation mechanisms, particularly dislocation glide-plus-climb and dislocation multiplication, contribute to tertiary creep deformation during short term tests. When coupled with cavitation and oxidation, GBS also contributes to tertiary creep. The total creep strain is a result of the summation of all above contributions, and the entire creep, as a continuous process, is thus described. Superimposed on these mechanisms are various fracture criteria to predict the eventual event of creep rupture. 2:30pm THE EFFECT OF DEFECTS ON THE LCF BEHAVIOR OF AN ADVANCED SINGLE CRYSTALSUPERALLOY: K.A. Dannemann, H. Jang, WI. King, GE Power Generation, Schenectady, NY 12345 The defect propensity in single crystal castings is enhanced with increased casting size. As the industrial gas turbine community moves towards the application of large single crystal castings, there is increasing concern regarding the effects of grain and casting defects on part life. Although aircraft engine experience provides a basis for single crystal grain limits, the cycle and life requirements of large industrial gas turbines differ considerably. The
effect of several types of defects on the low cycle fatigue behavior of an advanced single crystal alloy will be discussed. Tests were run on cast-to-size LCF bars with intentional defects (freckles, inclusions, low angle boundaries, recrystallized grains, slivers, mis-oriented grains) in the gage section. A correlation between defect size and LCF life was observed. Work to date indicates LCF life is more dependent on defect size than type.
tically, mechanical properties (i.e., hardness and tensile properties) and erosion resistance are discussed. 4:10pm THERMALAND MECHANICAL PROPERTIES OF THERMAL BAR· RIER COATING ON CU-SUBSTRATE PREPARED BY DETONA· TION·GUN THERMAL SPRAY METHOD: Y.M. Rhyim, H.w. Jin, e.G. Park, Center for Advanced Aerospace Materials, Pohang University of Science & Technology, Pohang 790-784, Korea; S.B. Kim, M.e. Kim, Research Institute of Industrial Science & Technology, Pohang 790-600, Korea
2:50pm HOT FORMING CHARACTERISTICS OF Ni·BASE SINGLE CRYS· TAL SUPERALLOY CMSX·6: D. Zhao, H. Dong, M. Zelin, A. Dalley, Concurrent Technologies Corporation, 1450 Scalp Ave., Johnstown, PA 15904
Thermal barrier coating (TBC) consisting of yp,stabilized Zr02 top coat on a MCrAIY bond coat has been developed for thermal protection of hot components used in steel plant, especially the tuyeres in blast furnace. Since the tuyere is used under extremely harsh chemical environment and high temperature (up to 2300°C) within the blast furnace, it is essential to develop a strong and tough protective coating, that is fully compatible to the tuyere's pure copper substrate, by applying the detonation-gun thermal spray method. As fuel gas amount increased, the porosity of MCrAIY coat layer generally decreased to less than 1%, but microcracks can be formed with extreme fuel gas amount. The metallic bond coat with the thickness greater than 100!lm is required to sustain the ceramic top coat. In obtaining the best top coat, the spraying condition with maximum detonation temperature was found as an optimum condition from the computer simulation. A partially stabilized zirconia top coat layer deposited by this condition exhibited the low porosity with high hardness (-640 DPH) which is better than the coating made by plasma spraying. The thermal fatigue resistance of the present TBC was revealed to depend on both the thickness of ceramic top coat and the composition of the stabilizer. The result on the thermal conductivity is also discussed.
High temperature deformation processing of Ni base single crystal superalloy CMSX-6 has been shown to be a feasible process. However, it is essential that the single crystal material be deformed at a low strain rate and within an appropriate temperature range to prevent recrystallization and fracture. In order to establish these limits, the hot forming behavior of Ni base single crystal superalloy CMSX-6 was investigated by performing high temperature compression, bending, and rolling tests. Stepwise deformation and annealing tests were also conducted to simulate multi-pass rolling practice. The flow stress and recrystallization behavior were characterized over a range of temperatures, strain rates, and strains. Metallurgical phenomena, such as changes in size and morphology of y' particles, orientation change of the single crystal specimens, subgrain boundary formation, recovery, and recrystallization, occurred during the high temperature deformation processes. These phenomena were analyzed to understand their influence on forming of single crystals. Deformation at too high temperatures resulted growth of y' particles and deteriorated the service properties of single crystals. Highly mis-oriented subgrain formation around y' particles lead to recrystallization. Deformation mechanisms were investigated by analyzing the results of compression and indentation tests. The primary slip systems activated were of (111 )<110> type. This work was conducted by the National Center for Excellence in Metalworking Technology, operated by Concurrent Technologies Corporation under contract No. NOOI40-92-C-BC49 to the U.S. Navy as part of the U.S. Navy Manufacturing Technology Program.
4:30pm ELECTROCHEMICAL PROCESSING OF THERMAL BARRIER COATINGS: S. W. Banovic, K. Barmak, A.R Marder, C.M. Petronis, D.G. Puerta, D.E Susan, Lehigh University, Department of Material Science and Engineering,S E. Packer Ave., Bethlehem, PA 18015
3:10pm EFFECT OF TEMPERATURE ON THE DEFORMATION CHARAC· TERISTICS OF A Ni·Mo·Cr ALLOY: w.e. Johnson, D.L. Klarstrom, Haynes International, 1020 W. Park Avenue, P.O. Box 9013, Kokomo, IN 46904; M. Dollar, Haynes International, Engineering 1 Bldg., 10 W. 32nd Street, Chicago, IL 60616
Multilayer, graded thermal barrier coatings have been fabricated using electrochemical methods. The inner two layers of the coatings are electro-deposited from aqueous baths and consist of 18 vol. % Al and 20 vol. % Al + 7 vol. % alumina, respectively, in a Ni matrix. The outer two layers are electrophoretically deposited form non-aqueous baths and contain an oxidation-resistant alumina 1 zirconia layer and a thermal-resistant yttria-stabilized zirconia outer layer, respectively. The alumina + zirconia layer was formed by reaction bonding of an aluminum-alumina-zirconia precursor powder. In addition to the details of the fabrication, the results of thermal cycling and mechanical testing of these four-layer coatings will be presented.
The high temperature, age hardenable, Ni-Mo-Cr alloy HAYNES 242 shows a change in deformation characteristics dependent upon the testing temperature. Aged material shows microtwinning to be a dominant deformation mechanism at all testing temperatures. However, this does not preclude the occurrence of slip at room temperature and elevated temperature. Grain boundaries also seem to playa role in the fracture propagation mechanism at work in tested samples. Samples in the aged condition fracture with a combined mode of dimple rupture and cleavage as opposed to annealed samples which fracture through a dimple rupture mode alone. The fracture surface shows microvoid coalescence but the fracture takes place in a shear-type mode as opposed to the traditional cup and cone ductile fracture.
4:50pm ELECTRON BEAM PHYSICAL VAPOR DEPOSITION OF NICKEL· BASE ALLOYS USING REFRACTORY ADDITIONS: D.A. Madey, A.M. Ritter, S. Tin, M.R Jackson, S. Rutkowski, RA. Nardi, GE Corporate Research & Development, P.O. Box 8, Schenectady, NY 12301 Many potential applications of electron beam evaporation demand tight compositional control in the deposits and high deposition rates. Adding tungsten to nickel-based evaporation pools can increase evaporation rates and improve compositional control in deposits. Effects of tungsten addition on several alloys, NiCoAI, NiCoCr, and NiCrAI were investigated. Magnitudes of compositional gradients in the deposits, measured using electron microprobe techniques, were used to evaluate the sensitivity of vapor cloud chemistry to fluctuations in processing parameters. Compositional and microstructural gradients in quenched evaporation pools, studied using microprobe and SEM, yielded information about the evolution of steady state in the pools. Tungsten distributions in the pools, which may significantly affect temperature distribution, fluid flow, and heat transfer, were mapped using back scattered electron microscopy and energy dispersive X-ray analysis. Currently, pool surface temperatures are being mapped using an infrared imaging radiometer and effects of refractory additives other than tungsten are being evaluated.
3:30 pm BREAK 3:50pm SOLID PARTICLE EROSION RESISTANCE OFIRON,NICKELAND COBALT·BASEDALLOYS: B.F. Levin, J.N. DuPont,A.R. Marder, Lehigh University, Energy Research Center, Bethlehem, PA 18015 The erosion behavior of commercially available iron, nickel and cobalt-based alloys was evaluated and a relative ranking of their erosion resistance was developed. Microhardness tests were conducted in the vicinity of the eroded surface to measure the size of the plastic zone beneath the eroded surface. It was found that all alloys deformed plastically and a new toughness parameter has been proposed which shows good correlation with erosion resistance. To find a relationship between mechanical properties and erosion resistance, elevated temperature mechanical test were conducted for all alloys. The erosion resistance of tested materials exhibited good correlation with their tensile toughness. Relationships between the ability of materials to deform plas-
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5:10pm RF MAGNETRON SPUTTERING OF MoSiz + X SiC COMPOSITE THIN FILMS: S. Govindarajan, lJ. Moore, Advanced Coatings and Surface Engineering Laboratory, Dept. of Met. & Materials Eng., T.R. Ohno, Dept. of Physics, Colorado School of Mines, Golden, CO 80401-1887 A critical component of a prototype coating system being developed to protect molybdenum against high temperature oxidation (i.e. at 16oo°C for 500 hours) is a functionally graded layer based on MoSi z + x SiC (where x is the variable mole fraction of SiC in the film). Different approaches for synthesizing composite films include sputtering from elemental or compound targets, reactive sputtering, and direct sputtering of composite targets. This paper will explore the feasibility of synthesizing composite films by RF magnetron sputtering of a composite target. Results of compositional depth profiling using Auger Electron Spectroscopy, microstructural evaluation and X-Ray diffraction analyses of the films will be presented. In particular, the diffusion of silicon and carbon in to the substrate will be characterized using a "ballcratering" technique followed by auger electron spectroscopy (AES). This technique will help to overcome the disadvantages associated with ion-beam sputtering during depth protiling (e.g. different sputter yields for the constituent elements, interface broadening effects, etc.).
MATERIALS FOR SPALLATION NEUTRON SOURCES I: Radiation Effects, A Sponsored by: Jt. SMDIMSD Nuclear Materials Committee Program Organizers: M.S. Wechsler, North Carolina State University, L.K. Mansur, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6376; C.L. Snead, Brookhaven National Laboratory, Upton, NY 11973-5000; W.F. Sommer, Los Alamos National Laboratory, Los Alamos, NM 87545 Monday, PM February 10, 1997
Room: Salon 4 Location: Clarion Plaza Hotel
Session Chairperson: M.S. Wechsler, North Carolina State University, 106 Hunter Hill Place, Chapel Hill, NC 27514-9128
2:00pm CALCULATIONS OF RADIATION EFFECTS ON 316 STAINLESS STEEL CONTAINER MATERIALS FOR THE NSNS: M.S. Wechsler!, M.H. Barnett!, L.K. Mansur2 , J.M. Barnes2, L.A. Charlton 2, 1.0. 10hnson2; 'North Carolina State University, Dept. of Nuclear Engineering, Raleigh, NC 27695-7909; 20ak Ridge National Laboratory, Computational Physics and Engineering Division Oak Ridge, TN 37831-6376 A current pre-conceptual design for the National Spallation Neutron Source (NSNS) considers the target to be flowing liquid mercury contained within a double-walled 316 stainless steel vessel. Calculations are underway to determine the neutron flux and to estimate the rates at which displacements, helium, and hydrogen are produced. The primary computational tools are MCNP, SPECTER, HETC, and LAHET. The displacement and helium production rates range up to about 10.7 DPAIs and 10.6 appm He/s due to the spectrum of neutrons produced by a 1700 Me V proton beam. The variation of calculated damage rates throughout the target region of NSNS is described and discussed. 2:30pm HELIUM PRODUCTION RATES ARISING FROM SPALLATION NEUTRONS IN THE LANSCE RADIATION EFFECTS FACILITY: F.A. Garner', W. F. Sommer2, P. D. Ferguson2, M. S. Wechsler3, M.H. Barnett3, B.M. Oliver'; 'Pacific Northwest Laboratory, Richland, WA 99352; 2Los Alamos National Laboratory, MS H805, Los Alamos, NM 87545; 3North Carolina State University, Raleigh, NC 27695-7909; 'Rockwell International Corporation, Canoga Park, CA 91303-2790 Foils of pure Cu, Co, Fe and Ni were irradiated in the second inboard tube of the rabbit system adjacent to the beam stop of the LANSCE facility. After irradiation, the foils were cut in half to determine neutron fluence and spectra via measurement of gamma activation, and to measure helium generation via
isotopic dilution mass spectroscopy. The measured helium concentrations were 0.110,0.152,0.122 and 0.097 appm for Fe, Ni, Cu, and Co, respectively. The dpa level calculated for copper was 0.011 dpa, yielding a value of ILl appm/ dpa. Comparisons with improved calculations of neutron flux/spectra and helium and displacement production rates are in progress to characterize the neutron environment of the rabbit system and to assess its radiation damage effects. 3:00pm THE EFFECT OF THE NEW NUCLEON-NUCLEUS ELASTIC SCATTERING MODEL IN LAHET VERSION 2.8 ON DAMAGE CROSS SECTION CALCULATIONS: E.J. Pitcher!, P.D. Ferguson', G.1. RusselJI, 1.D. Court', L.L. Daemen!, M.S. Wechsler2, R.E. PraeJI, D.G. Madland!; 'Los Alamos National Laboratory, Los Alamos, NM 87545; 2North Carolina State University, Raleigh, NC 27695-7909 The latest release of the medium-energy Monte Carlo transport code LAHET includes a new nucleon-nucleus elastic scattering treatment based on an interim global medium-energy phenomenological optical-model potential. Implementation of the model in LAHET allows nuclear elastic scattering for neutrons with energies greater than 15 MeV and for protons with energies greater than 50 MeV. Previous investigations on the impact of the new elastic scattering model revealed that the addition of the proton elastic scattering channel can lead to a significant increase in the calculated damage energy. We report here results of further investigations on the impact of the new elastic scattering model on calculated damage cross sections and recoil spectra for materials and particle energies prototypic of spallation target environments. With the new elastic scattering treatment, the damage cross section for 20-MeV neutrons on light nuclei (A < 30) as calculated by LAHET is in much better agreement with SPECTER calculations, where significant discrepancies have previously been observed. 3:30 pm BREAK 3:50pm THE INFLUENCE OF SUBCASCADE FORMATION ON DISPLACEMENT DAMAGE AT HIGH PKA ENERGIES: R.E. Stoller, Oak Ridge National Laboratory, Metals and Ceramics Division, Oak Ridge, TN 378316376 Molecular dynamics (MD) simulations of displacement cascades have been extended to energies as high as 40 keV. These simulations are the highest energy cascades completed to date and they provide valuable insight on the formation of primary damage in irradiated materials. An MD simulation at 40 keY is equivalent to a PKA energy of 61 keY, which is the average PKA energy from a neutron with an energy of 1.8 MeV. Although peak neutron energies in a spallation neutron source will be much higher than 1.8 MeV, the degree of subcascade formation observed at MD energies above 20 ke V suggests that little change in the primary damage state will be observed for higher energies. This implies that fission reactor data should provide a good simulation of the displacement damage observed in a spallation neutron source. Thus, the effect of transmutation products is likely to be the most important difference between the two irradiation environments. 4:20pm INVESTIGATION OF HIGH-ENERGY-PROTON EFFECTS IN ALUMINUM: C.J. Czajkowski, c.L. Snead, M. Todosow, Brookhaven National Laboratory, Upton, NY 11973-5000 Specimens of !l00 aluminum were exposed to several fluences of 23.5-GeV protons at the Brookhaven Alternating Gradient Synchrotron. Although this energy is above those currently being proposed for spallation neutron applications, the results can be viewed as indicative of trends and other microstructural evolution with fluence that take place with high-energy proton exposures such as those associated with an increasing ratio of gas generation to dpa. TEM investigation showed significantly larger bubble size and lower density of bubbles compared with lower-energy proton results. Estimates of H and He gas generation made using Monte Carlo are also used in this comparison. Additional testing showed that the tensile strength increased with fluence as expected, but the microhardness decreased, a result for which an interpretation is still under investigation.
To address the critical issue of placing electronic assemblies in extreme tern .. perature environments that exceed the operating temperatures of commonly used eutectic Sn-Pb solder or high-Pb content alloys, National Center for Manufacturing Sciences (NCMS) initiated a national consortium in 1996 titled "High Temperature Fatigue Resistant Solder Project". The project objective is to demonstrate and deploy the technology to substantially improve the performance of solder joints at elevated temperatures under thermal cycling conditions. Two types of solder are to be developed: one with a performance objective of up to l6OC, "Alloy 160", for organic substrate; and a second alloy with a performance objective of 205C, "Alloy 205", for ceramic substrate, copper die bonding substrates, and hybrid technology. The goal is to demonstrate a thermal fatigue resistance that, in the respective temperature ranges, is equal to or better than that of conventional solders. The need for these new alloys is being driven by the automotive, telecommunications, avionics, and military industries. The project is organized into four task groups with five phases of work, and extends over a period of 33 months. The participants include automotive and military companies, solder suppliers, academic institutions, and national laboratories.
4:50pm RESPONSE OF STRUCTURAL MATERIALS TO RADIATION ENVIRONMENTS: CJ. Czajkowski, Brookhaven National Laboratory, Upton, NY 11973-5000 An evaluation of proton and neutron damage to various materials has been performed. The proton studies were conducted at energies of 0.2, 0.8, and 23.5 GeV and consisted of evaluation of proton-irradiated window/target materials from accelerators. The materials evaluated for the proton irradiations included high-purity (69's), 1100, and 5052 aluminum, 304 stainless steel, and inconel 718. The neutron damage research centered on 6061 T-6 aluminum from a control rod follower from the BNL HFBR, which received thermal fluence up to -4 X 1023 nlcm 2. The effects of thermal-to-fast neutron flux ratios are discussed. The increases in tensile strength in the proton-irradiated materials are shown to be due to atomic displacements, resulting in radiation hardening. Production of helium in the grain boundaries of protonirradiated 69's aluminum is also discussed. The major factor contributing to the mechanical-property changes in the neutron-irradiated 6061 aluminum is transmutation products formed by interactions with thermal neutrons.
3:30 pm BREAK 3:50 pm INVITED MICROSTRUCTURE AND PHASE EQUILmRIA IN THE Ag-Cu-8n TERNARY SYSTEM: M.R. Notis, Department of Materials Science and Engineering, Lehigh, University, 5 East Packer Ave., Bethlehem, PA 18015
MATERIALS &TECHNOLOGIES FOR MICROELECTRONICS II: An Issue for Lead·Free Solders (NCMS)
The Ag-Cu-Sn system is of interest for use in Pb-free solder alloys, brazing alloys, and in alloys for dental applications. The nature of the invariant reactions in the Sn-rich comer remain in question, and little is known about the effect of Cu addition on the width of the Ag 3Sn phase field and its adjoining two- and three-phase fields at lower temperatures. A series of alloys were prepared and studied by metallography and by thermal analysis in order to elucidate these aspects of the Ag-Cu-Sn system.
Sponsored by: EMPMD Electronic Packaging and Interconnection Materials Committee Program Organizers: Michael R. Notis, Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015; Dr. Sung K. Kang, IBM, TJ Watson Research Center, Yorktown Heights, NY 10598 Monday, PM February 10, 1997
Room: 314B Location: Orlando Convention Center
4:20 pm INVITED TAPE AUTOMATED BONDING (TAB) TECHNOLOGY FOR CHIP INTERCONNECTIONS: Sung K. Kang, IBM T.J.Watson Research Center, P.O.Box 218, Rm 37-250, Yorktown Heights, NY 10598
Session Chairperson: TBA
2:00 pm INVITED FILLET-LIFTING IN PLATED-THROUGH-HOLE EOMETRICS: Carol Handwerker, Ursula Kattner, Bill Boettinger, NIST, 223/A153, Gaithersburg, MD 20899; Chris Bailey, University of Greenwich, Wellington Street, Woolwich, London SE18 6PF
Tape automated bonding (TAB) technology has been widely used in low-;;ost consumer products as well as in high-performance multichip modules. TAB technology facilitates the chip-on-board (COB) assembly scheme in most applications. In this talk, two key issues of TAB technology, wafer bumping and inner lead bonding, are reviewed in conjunction with COB applications. Bumping refers to the process of adding raised metal contacts to bond pads in order to provide both the necessary bonding metallurgy for chip-to-1ead bonding and a physical standoff to prevent lead-chip shorting. This is done on a wafer or on a TAB tape. Various bumping processes in use are discussed in terms of bump materials/processing, structure, geometry, bump properties and behavior during bonding.
Separation of the solder fillet from the circuit board pad along the solderintermetallic interface has been observed for a wide range of lead-free solder alloys. The tendency for such separation depends on a number of factors, including solder composition, the freezing range (also known as the pasty range), the mechanical properties of the solder, and the interfacial toughness. The processes leading to fillet-lifting will be described and the potential for eliminating this problem in lead-free alloys will be discussed.
4:50pm MONTE CARLO SIMULATION OF STEP COVERAGE OF COPPER: Y.G. Wang, X.W.Zhou, R.AJohnson, H.N.GWadley, Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA 22903
2:30 pm INVITED CONCLUSIONS OF THE NCMS LEAD-FREE SOLDER DEVELOPMENT PROJECT: Duane Napp, NCMS, 3025 Boardwalk, Ann Arbor, MI 48108-3266
A new Monte Carlo procedure for atomistically simulating physical vapor deposition processes is developed and used to model the two-dimensional physical vapor deposition of the step coverage of copper. The method consists of an implant approximation for the initial adatom adsorption on a surface and a multipath diffusion analysis to simulate subsequent surface morphology and interior atomic structure evolution. An embedded atom method is used to determine the activation energies for each of the many available diffusion paths. The method has been used to predict the morphology/structure evolution of copper films over the length and time scales encountered in practical deposition processes. The modeling approach has enabled determination of the effect of vapor processing variables such as flux orientation, deposition rate, substrate temperature, kinetic energy and aspect ratio on deposit morphology/microstructure and step coverage behavior.
A summary of the completed 4 year study of lead free solder alloys will be presented. In addition to toxicological considerations it was critical to define and agree on the factors and the methodology used in the down selection of 79 alloys to 7 promising alloys. It was necessary to conduct a manufacturing evaluation of compatible surface finishes and generate manufacturing process parameters necessary to assemble test hardware. The results of the extensive reliability evaluations and the modeling of the final down selected alloys will be presented. Follow-on NCMS material interconnect projects will be discussed. 3:00 pm INVITED HIGH TEMPERATURE FATIGUE RESISTANT SOLDER - A NCMS PROJECT: Duane Napp, NCMS, 3025 Boardwalk, Ann Arbor, MI481083266
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acterize the mechanical behavior included Vickers hardness, four-point flexure at 25 and 800°C, indentation fracture, indentation strength, and mass loss corrosion testing. In addition, the microstructure was characterized using optical and scanning electron microscopy to examine the polished and etched microstructures, the cracks located at the corners of the hardness indents, and the fracture surfaces produced by flexure testing. Correlations were made between the mechanical properties of flexural strength and hardness and the microstructural parameter of contiguity. Experimental results indicate that the strength of!BC composites with Ni3Al at 800°C compares favorably to the room-temperature strength. At 25°C, plastic deformation of the Ni3Al and FeAl binders occurs, but the strength of the composite with FeAl is higher due to strong bonding along the carbide-binder interfaces. WC-based composites yielded higher flexural strength and fracture toughness values, while TiC-based composites produced higher hardness values. Increased binder amounts produced higher values of flexural strength and fracture toughness due to a reduction in the number of carbide-carbide interfaces and an increase in plastic deformation in the crack-tip region, respectively.
5:10pm PEEL STRENGTH IN A CuiCr POLYIMIDE SYSTEM: l. S. Park, lun Yu, Department of Materials Science and Engineering, KAIST, P.O. Box 201, Cheongryang, Seoul, 130-650, Korea The adhesion strength of a metal film on a substrate is usually measured by the Peel Test. This test is not a direct measure of the interfacial energy because of the severe plastic deformation of the metal film accompanying the test. In the present analysis, using the Cu/Cr/polyimide system, the surface energy was deduced from the peel strength measurements and corresponding elasto-plastic analysis of the peel test. The metallpolyimide interface energy was varied by changing the pretreatment condition of the polyimide surface in Ar(+) RF plasma, and the adhered film thickness and yield stress were varied by changing the electroplating conditions. After the peel test, the chemistry of the Cr/polyimide interfaces were studied by AES and XPS.X-ray measurements of the residual strain in the peeled films were very useful in estimating the plastic work expenditure accompanying peeling. Results indicate that the deduced interfacial fracture energy is usually much smaller than the peel strength and is influenced by the RF pretreatment, but the interfacial energy is independent of the mechanical properties of the metal film, as expected.
3:00pm INTERFACIAL SLIDING ALONG SOLDERIINTERMETALLIC IN· TERFACES: C. Zhang, D. Yao, lK. Shang, Department of Materials Science and Engineering, University of Illinois, Urbana, IL 61801 Intermetallic cells formed during reactive wetting of metal substrates often lead to a microcellular interface morphology. Evidence is given of interfacial sliding as the crack grows, along these interface, subcritically at very low strain energy release rates under cyclic loading. Physical model was constructed to capture the salient aspects of the interfacial sliding mechanism. The model predicted that the crack shielding should arise from interfacial sliding and the magnitude of the crack shielding depended on loading-mode, roughness of the interface, and sliding resistance of the interface. Experiments designed to test the validity of the model will be described and comparisons will be made between model predictions and experimental results.
NON·LlNEAR FRACTURE PROCESSES IN BRITTLE CRYSTALLINE SOLIDS I: Metallic Systems Sponsored by: ASM·MSD Flow and Fracture and SMD Mechanical Metallurgy Committees Program Organizer: J.K. Shang, Department of Materials Science and Engineering, University of Illinois, Urbana, IL 61801; P.K. Liaw, Department of Materials Science and Engineering, University ofTennessee, Knoxville, TN 37996·2200; S.X. Mao, Department of Mechanical Engineering, University of Calgary, Calgary, Alberta, Canada, T2N 1N4 Monday, PM February 10, 1997
3: 30 pm BREAK
Room: 232B Location: Orlando Convention Center
4:00 pm INVITED MICROMECHANISMS OF CRACK·TIP DEFORMATION AND TOUGHENING TITANIUM ALUMINIDES IN INTERMETALLICS: W.O. Soboyejo, C. Mercer, Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus, OH 432101179; P.B. Aswath, Materials Science Program, Department of Mechanical Engineering, The University of Texas at Arlington, P.O. Box 19301, Arlington, TX 76019
Session Chairperson: J.K. Shang, Department of Materials Science and Engineering, University of Illinois, Urbana, IL 61801
2:00 pm INVITED DAMAGE TOLERANCE IN BRITTLE MATERIALS: R.O. Ritchie, Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 94720
The micromechanics of crack-tip deformation and toughening are elucidated for a range of a2- and y-based titanium aluminides. Crack-tip deformation is shown (via crack-tip transmission electron microscopy) to occur by a combination of microcracking and slip under cyclic loading. Toughening mechanisms in a2-based alloys (crack-tip blunting, bridging, deflection and microcrack shielding/anti-shielding) are also modeled using micromechanics. Similarly, the crack tip deformation and toughening mechanisms in gammabased titanium aluminides (deformation-induced twinning and slip) are elucidated for a range of experimental and near commercial alloys. Micromechanical models are also presented for the prediction of toughening in gamma alloys. The paper shows clearly that crack-tip shielding mechanisms do not necessarily result in slower fatigue crack growth rates.
A critical factor in the design of advanced materials for structural application is the development of sufficient damage tolerance, i.e., resistance to fracture and subcritical crack growth in the presence of pre-existing flaws. In practical terms, this implies designing microstructures with adequate fracture toughness based on toughening mechanisms that are resilient to cyclic loading, and where appropriate elevated temperatures and adverse environments. In this presentation, such considerations will be reviewed for a number of "low ductility" advanced materials, including ceramics (Si3N., SiC) and intermetallics (g-TiAl, MoSi2 , Nb3Al) in the form of monolithic, composite and layered materials. 2:30pm PROCESSING, MECHANICAL BEHAVIOR, AND MICROSTRUC· TURAL CHARACTERIZATION OF LIQUID PHASE SINTERED IN· TERMETALLIC·BONDED CERAMIC COMPOSITES: C.B. Thomas, P.K. Liaw, Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996-2200; T.N. Tiegs, Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6115
4:30pm SHEAR LIGAMENT TOUGHENING AND MICROMECHANICAL MODELLING IN IRON ALUMINIDE INTERMETALLICS: Scott X. Mao, Department of Mechanical Engineering, University of Calgary, Calgary, Canada T2N IN4 The fracture behavior of an iron aluminide intermetallica in air environment was studied. At room temperature, round tensile specimens were tested at different strain rates. By carefully examining the lateral surface of the tensile specimens, ligament-like structures that connected between microcracks were found. SEM pictures show that these structures, which can be called shear ligments, undergo ductile fracture by shearing. This type of fracture dissipates more energy and was believed to enhance the fracture toughness of the material. By use of a micromechanical model of shear ligment toughening,
Intermetallic-bonded ceramic (!BC) composites with various amounts of a WC or TiC carbide phase mixed with a Ni3Al or FeAl binder phase were successfully fabricated by liquid phase sintering and hot isostatic compaction methods. The influence of carbide type, binder type, and binder content on the flexural strength, hardness, fracture toughness, and corrosion resistance of!BC composites was investigated. Experimental techniques used to char-
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fracture toughness of the material, K, was estimated at different strain rate. The values of critical parameters, which are ligment length, area fraction and work to fracture by shear were obtained from SEM observations on different tensile specimens. K was found to be decreased towards lower strain rates. This strain rate effect was similar to that obtained experimentally. This outcome verified the importance of shear ligments in determining the materials fracture toughness.
2:20pm QUENCH DROSSING OF LEAD BULLION:: Funsho K. Ojebuoboh, Asarco Inc., Technical Services Center, 3422 South 700 West, Salt Lake City, UT 84119 New technology has been developed for drossing lead bullion. The technique was developed to replace conventional copper drossing, so-called rough crossing, performed in kettles. With quench drossing, water granulation of bullion exiting the smelting furnace, usually above 900°C (1700°F), is used to arrest equilibrium formation of the dross species. The process is based on granulating lead bullion from the furnace, thereby quenching the bullion, and subsequently sweating lead off the granules in a rotary kiln furnace. The major benefit of the new technology is expected to be reduced air-borne lead which is normally associated with conventional drossing. The process also has the potential of making lead crossing metallurgy more susceptible to better process control. The process and its development are described.
5:00pm MlCROMECHANISMS OF CRACK-TIP DEFORMATION IN ZIRCONIA TOUGHENED INTERMETALLICS: F. Ye, G- Y. Lu, P. Ramasundaram and W.O. Soboyejo, Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus, Ohio 43210-1179 The micromechanisms of crack-tip deformation will be elucidated for zirconia toughened nickel aluminide and molybdenum disilicide intermetallic composites reinforced with partially stabilized zirconia particles with different particle sizes. The transformation toughening components associated with different stabilizers (ceria, magnisia and yttria) are also quantified using micromechanics models and experimental results obtained from laser Raman spectroscopy and optical interference analyses. Shielding contributions from other applicable toughening mechanisms are also discussed. Stable fatigue crack growth in zirconia toughened intermetallics is attributed to the effects of kinematic irreversibility due to stress-induced martensitic transformations under cyclic loading. The relative contributions from microcracking and slip phenomena (to kinematic irreversibility) are also discussed.
2:40pm RECYCLING OF MAGNESIUM ALLOY SCRAP, A NECESSITY: Christine Brassard, Lisabeth Riopelle, Oddmund Wallevik, Hydro Magnesium Market Development Center, 21644, Melrose Avenue, Southfield, MI 48075-9705 The use of magnesium alloys is growing rapidly, particularly in die cast parts for the automotive industry. Supporting this growth in the future means that Mg has to be an economically and ecologically attractive material, and recycling of alloy scrap becomes a necessity. What kinds of magnesium scrap will be on the market? What are the opportunities and challenges for this emerging recycling industry? Different recycling processes have been developed, and operation facilities are today recycling large volumes of class I diecast returns based on a flux refining technology. Characterization of the recovered metal demonstrates that the performance of appropriately recycled magnesium alloy is comparable to an alloy made from primary electrolytic metal. The sludge generated from this process can also be recycled through the existing primary Mg operations in order to close the environmental loop.
PYROMETALLURGY AND MELTING PRACTICE Sponsored by: EPD Pyrometallurgy Committee & Process Fundamentals Committee Program Organizer: David G.C. Robertson, Center for Pyrometallurgy, Univ. of Missorui-Rolla, Rolla, MO 65401; Garry W. Warren, Dept. of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL 35487 Monday, PM February 10, 1997
3:00pm THE REACTION MECHANISM OF OXIDIZED CHALCOPYRITE CONCENTRATE PARTICLES AND COPPER MATTE WITH IRON SILICATE SLAG: K. FagerluntP, P. Nurmi', H. lalkanen', P. Taskinen2, 'Helsinki University of Technology, Laboratory of Metallurgy, Vuorimiehentie 2, FIN-02150 Espoo Finland; ZOutokampu Research Oy, P.O.BOX 60, SF28101 Pori, Finland
Room: 230D Location: Orlando Convention Center
Session Chairperson: David G.C. Robertson, Center for Pyrometallurgy, Univ. of Missorui·Rolla, Rolla, MO 65401
The reaction mechanism and settling behaviour of oxidized chalcopyrite particles and coppper matte droplets introduced into synthetically prepared fayalite type slag under nitrogen and argon atmosphere have been investigated in this work. As a part of the investigation into flashsmelting reaction phenomena in a settler region, a laboratory experiments were conducted by means of aXray image system and a vertical tube furnace. The reaction phenomena of oxidized chalcopyrite in iron silicate slag was studied in a tube furnace, temperature being 1300°C, and inert gas flow (N2). The partly oxidized samples of chalcopyrite were blown into synthetic fayalitic slag. Reaction products were studied and analysed using light optical microscope (LOM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and chemical methods. Industrial copper matte and oxidized chalcopyrite were introduced into iron silicate slag. The melting and settling behaviour, the variation of the copper matte droplet shape and the movement of melting interface were continuously monitored by X-ray image system.
2:00pm A TWO-LIQUID SLAG MIXING EXPERIMENTAL TECHNIQUE FOR STUDYING THE OXIDATIVE PRE-FUMING TREATMENT OF LEAD BLAST FURNACE SLAG: Adrian Deneys, David Robertson, and Nick Schupp Center for Pyrometallurgy, University of Missouri-Rolla Rolla, M065401 An experimental technique has been devised for studying the reaction kinetics of the homogeneous, liquid phase reaction: ZnO + FeO = Zn(g) + Fe 203, by which zinc evolution can occur from a molten AlP3-CaO-FeO-Fez03 -Si02ZnO bath in the absence of a carbonaceous reductant. When studying the reaction kinetics by heating from room temperature, solid state reactions and poorly defined melting points may obscure the starting point of the reaction. In order to eliminate this problem, an experimental technique was devised whereby two molten slags could be melted independently, and then mixed, to provide a well defined starting point from which to begin taking measurements. Two crucibles were mounted in a vertical reaction cylinder. The upper, mild steel, crucible had a bottom pouring plug which was sealed by a steel stopper rod. A fayalite mixture was contained in this crucible. The lower crucible contained an AI 203-CaO-Si02-ZnO mixture. Once the two slags had been melted, the steel stopper rod was removed from the upper crucible. The upper, reduced slag (fayalite in equilibrium with the upper steel crucible), drained into the lower crucible where the two slags were mixed by submerged argon stirring. Dip samples were taken to measure the zinc content of the final mixture as a function of time. The experimental procedure will be described, as well as results of experiments which were conducted on synthetic slags. The system investigated was similar to the lead blast furnace slag which is produced by the primary lead smelters of Missouri, USA.
3:30 pm BREAK 3:40pm MELTING OF HIGH PURITY CHROMIUM: Raymond K.F. Lam, Giuseppe Colella, Materials Research Corporation, 542 Route 303, Orangeburg, NY 10962 Unacceptable levels of impurity were noted from high purity chromium melting operation. Analysis of past chromium melting determined that total oxygen content was the critical parameter. Thermodynamic analysis of oxides and liquid chromium was presented. Acceptable operating conditions were identified. A new process of melting high purity chromium with oxide addi-
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tion for controlling the activity of Cr,03 was recommended. Experimental results of the new melting process were presented.
Ferroalloy of Nb, as the main product ofNb recovered from Nb-bearing iron ores, is recently produced by the following route. Nb-bearing iron concentrate is reduced in a blast furnace to generate Nb-bearing hot metal, which is then smelted in a converter to yield Nb-enriched slag. Finally Nb- enriched slag is reduced in an electric furnace to get ferroalloy of Nb. In order to improve the recovery ratio of Nb, it is important to acquire a deep understanding on how Nb is transferred to hot metal from slag. In the present work, raw material containing niobium oxide were carbothermally reduced under the conditions of calm metal-slag interface or stirred metal-slag interface, respectively. Under the former condition, the quenched samples were found through SEM observations that NbC layer occurred at the metal-slag interface. In this case, Nb transfer to hot metal from slag slows down and the rate controlling step is Nb diffusion in NbC layer. Under the later conditions, it was found that no NbC layer occurred at the metal-slag interface, indicating that NbC formed at the interface sunk into hot metal due to the higher density of NbC than that of hot metal. In this case, the rate controlling step is Nb diffusion in slag.
4:00pm ADVANCED NON-FERROUS SCRAP MELTER: J.S. Becker, J.E Heffron, R.J. Hewertson, E. Keith Riley, Air Products and Chemicals, Inc., 7201 Hamilton Boulevard, Allentown, PA 18195-1501 Technology developed and first implemented in the United Kingdom enables very low grade non ferrous scraps containing sils, organics, plastics and ferrous metals to be directly charged, without pretreatment, into a unique melting furnace. Two furnaces have been in full scale production for over four and two years, respectively. A third furnace was only recently commissioned. The oxy-fuel-based furnace design incorporates internal afterburning in the furnace's hot zone, producing excellent thermal efficiency and very low emissions. Advanced process control insures complete combustion of all volatiles in an environment that is not oxidizing to the melt. Thus metal yields have been excellent. The furnace is very low in Nox This paper will provide both theoretical background and extensive operating results for this new melting concept. Applications describing both purpose built new furnaces and retrofits of existing reverberatory furnaces will be presented. Extensive operating emissions data will be presented.
RARE EARTHS SESSION: SCIENCE, TECHNOLOGY AND APPLICATIONS II: Battery and Materials Chemistry
4:20pm OXYGEN ENHANCEMENT OF BURNERS FOR IMPROVED PRODUCTIVITY: D.1. Krichten, W.J. Baxter, C.E. Baukal, Air Products and Chemicals, Inc., 7201 Hamilton Blvd., Allentown, PA 18195
Sponsored by: LMD Reactive Metals Committee Program Organizers: R.G. Bautista, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno, Reno, NV 89557; C.O. Bounds, RhonePoulenc Rare Earths and Gallium, CN 7500, Prospect Plains Rd., Cranbury, NJ 08512; Timothy W. Ellis, Kulicke and Sofia Industries Inc., 2101 Blair Mill Rd., Willow Grove, PA 19090; Barry T. Kilbourn, Molycorp, Inc., Executive 46 Office Center, 710 Route 46 East Fairfield, NJ 07004
A method of retrofitting air-fuel burners with oxy-fuel capability overcomes the potential problems associated with oxygen combustion in aluminum melting furnaces. Several years of operation in rotary furnaces reclaiming dross and UBC scrap and since 1993 in revereratory furnaces prove the usefulness of the retrofit approach. The retrofit burner uses the existing combustion air connection, burner housing, and burner tile and replaces the gas tube with an oxy-gas burner. Maintaining a portion of the air flow to the burner reduces the potential for localized overheating. This technique optimizes the mix of air and oxygen to the burner for the given furnace geometry and meltrate desired. Proper design of the burner reduces Nox emissions by moderating the flame temperature with furnace gas recirculation. Economic analysis of using merchant oxygen shows the benefits are increased productivity and reduced overall unit cost of melting. In practice, the melt rate in rotary furnaces increases by up to 50% and by up to 35% in reverberatory furnaces. Oxygen enhancement reduces melting cost by 112-3/4 cents per pound of aluminum melted.
Monday, PM February 10, 1997
Room: Salon 8 Location: Clarion Plaza Hotel
Session Chairperson: Charles O. Bounds, Rhone-Poulenc Rare Earths and Gallium, Cranbury, NJ 08512; Danesh Chandra, Dept. of Chemical and Metallurgical Engineering, University of Nevada, Reno, NV 89557
1:30pm SURFACE FILMS ON MmNi .5.sCoo.8A1o.7 ELECTRODES IN 30% KOH THEIR IMPACT ON HYDROGEN STORAGE CAPACITY AND REACTION RATES: M.E. Fiorino, Bell Laboratories, Lucent Technologies, Whippany, NJ 07981; R. L. Opila, Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974; K. Konstadinidas, Bell Laboratories, Lucent Technologies, Norcross, OA 30071, W. C. Fang, Utmost Industrial Corp., Taipei, Taiwan, China
4:40pm THE REDUCTION BEHAVIOR OF HEMATITE COMPACTS BY H2 and H 2-CO GAS MIXTURES: l.J. Moon, C.H. Rhee, Materials Science & Engineering, Pohang University of Science and Technology, Pohang 790784, Korea
Misch metal based intermetallics are currently employed as reversible hydride-forming electrodes in Ni - Metal Hydride batteries with 30% KOH electrolyte. In spite of the thermodynamic instability of rare earths in this medium, these electrodes retain storage hydrogen ability and support rapid electron transfer for hundreds of hydriding-dehydriding cycles. Results of electrochemical and XPS studies of one such intermetallic MmNi3.5Coo.8Alo7' have led to the development of a model to explain these properties.
The reduction behavior of hamatite by H2 and ~-CO gas mixtures was investigated to elucidate the reduction mechanism at 1073 - 1223K. The hetatite compacts were made by Cold Isostatic Pressing to produce compacts of uniform shape and size. The compacts were sintered at 1273K for 30 min., and showed a contraction of 29%. Mercury pressure porosimeter and BET technique were used for measuring the total porosity, pore size distribution and pore surface area of the compacts. Reduction was followed up by means of weight-loss technique using Cabn Balance (Model: TO-I71, capacity 109, accuracy ± 10 ~g.) Microscopic examination (SEM, EPMA), X-ray, and carbon analysis were used to correlate the structure of reduced compacts with the mechanisms of reduction and carbon deposition. The values of apparent activation energy for ~ reduction were between 11.21 kcal/mol and 14.38 kcal/mol. StruCtural changes, kinetics, and mechanisms of reduction and carbon deposition with ~ and H2-CO gas mixtures is discussed.
2:00pm THERMAL AGING OF LaNis.)1nx HYDRIDES: S. Bagchi,D. Chandra, W.N. Cathey, University of Nevada, Reno, NV 89557-0136 USA, R.C. Bowman Jr., Aerojet Electronic Systems, P.O. Box 296, Azusa, CA 91702; F. E. Lynch, Hydrogen Consultant Inc., 12420 N. Dumont Way, Littleton, CO 80125 The Joule-Thomson expansion of hydrogen gas offers a method to produce temperatures below 30K for use in cryocollers in space surveillance satellites. Metal hydrides are a critical components of these devices, providing a non-mechanical method to compress the hydrogen gas. The LaNis.xMnx-hydrides have potential applications in cryocooling devices: Luo and coworkers' presented detailed studies on their hydriding behavior. In this study, thermal aging behavior of two LaNi- s-xMn. -hydrides (x=O.4, and 1.5) was investigated to evaluate its long term stability. The hydriding behavior of La,02Ni•. 6Mno.• did not change significantly after thermal aging at 453K for 260 hours.
5:00pm MECHANISM OF NB TRANSFER TO HOT METAL FROM SLAG: Fan Peng, Yang Tianjun, Zhou Yusheng, Dong Yicheng, Wei Shonkun, Sichuan Union University, P.O. Box 373, Chengdu, Sichuan, 610065, China Nb-bearing iron ores are today the most significant source of niobium in China.
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2:30pm EFFECT OF RARE EARTH SUBSTITUTIONS FOR La ON THE HYDROGEN ABSORPTION OF La-BASED ABs ALLOYS: C O. Bounds, B. M. Ma, J. Patel, Rhone-Poulenc, Rare Earths and Gallium, CN 7500, Cranbury, NJ
:Ui'iULJ#~"
RECENT ADVANCES IN FRACTURE II: ElasticPlastic Fracture II: A Symposium Dedicated to Professor Emeritus Frank A. McClintock
The performance of Ab5-type alloys for hydrogen absorption including the electrochemical absorption as an electrode for rechargeable batteries has been demonstrated to be a complex function of the composition, microstructure and surface condition. The compositional studies have focused primarily on substitutions for Ni on the B-site (e.g. Co, AI, Mn, etc.). This current study examine, the effect of rare earth substitutions for La on the A-site and considers both other "light" rare earths (Ce, Nd, Pr) and "heavy" rare earths (Dy, Sm, etc.).
Sponsored by: MSD Flow and Fracture, SMD Mechanical Metallurgy Committees Program Organizers: Dr. R. K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; Dr. A. B. Geltmacher, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375; Dr. K. Sadananda, Naval Research Laboratory, Code 6323, 4555 Overlook Drive SW, Washington D. C. 20375; Dr. P. Matic, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375
3:00 pm BREAK
Monday, PM February 10, 1997
3:30pm GAS-PHASE HYDROGENATION PROPERTIES AND ELECTRODE PERFORMANCE OF La(Ni,Al,Co,V)sALLOYS: L.-c. Lei, S.-U. Liu T.P. Pemg, Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, 30043
Room: 314A Location: Orlando Convention Center
Session Chairpersons: Professor James A. Joyce, Department of Mechanical Engineering, U.S. Naval Academy, 590 Holloway Road, Annapolis, MD 21402; Professor Ronald W. Armstrong, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742
A series of LaNi5-based alloys, with partial substitution ofNi by AI, Co, or V, were prepared. The gas-phase hydrogen absorption kinetics and pressureComposition-temperature curves were measured. The activation became easier and the plateau pressure was reduced as Ni was partially substituted by AI. Substitution with Co reduced the hysteresis as well as the hydrogenation capacity. Less degradation of hydrogenation capacity after long cycles of hydriding- dehydriding was observed when substituted with both Al and Co. Vanadium is often considered as a hydride former, but when it was added to LaNi 5it was found that V occupied the B site. A small amount of substitution of Ni with V led to a higher hydrogenation capacity and faster activation rate.
2:00 pm INVITED DETERMINING THE J-CRACK GROWTH RESISTANCE BEHAVIOUR OF A DUCTILE MATERIAL: Edward Smith, Manchester Materials Science Center, Manchester University and UMIST, Grosnover Street, Manchester Ml 7HS, UK Ductile fracture has been the major theme of Frank McClintock's research career. This paper is concerned with the determination of a ductile material's crack growth resistance behaviour when it is expressed in terms of the deformation J-integral JD • Attention is focussed on the determination of the crack growth resistance curve from load, load-point displacement and crack extension measurements using single loaboratory test specimen. A commonly used procedure is based on the separation of JD into an elastic component JE and a plastic componentJDP' and the ability to express J DP for a non-growing crack in terms of the plastic energy integrals via eta factors that are independent of the applied loadings. The paper highlights the conditions which must be satisfied for JDpto be expressed in this way, and the limitations of some currently used practices based on this J DP formulation are indicated. Against this background, the author reviews his "two extremes" procedure, whereby the appropriate eta factors are obtained by ensuring that JDP assumes the correct form at the two extreme levels of deformation: small-scale yielding and extensive deformation at limit load conditions. Determination of the eta factors requires only a knowledge of the stress intensity factor and the limit load solutions, and not the material flow properties. The "two extremes" procedure is validated by comparing its predictions with well documented results for specific geometrical configurations. However, the procedure can be applied to any geometrical configuration, and the paper provides some examples.
4:00pm ATOMIZATION PROCESSING EFFECTS ON HYDRIDING BEHAVIOR OF ABs ALLOYS FOR BATTERY APPLICATIONS: R.C. Bowman, Jr., C. Witham, B. Fultz, California Institute of Technology, Pasadena, CA 91125; B.V. Ratnakumar, Jet Propulsion Laboratory, Pasadena, CA 911 09; T.W. Ellis, Kulicke and Soffa Industries, Inc., Willow Grove, PA 19090; I.E. Anderson, Ames Laboratory, Ames, IA 51122 Hydriding characteristics of some AB5 alloys produced by high pressure gas atomization (HPGA) were examined during reactions with hydrogen gas, and In electrochemical cells. Hydrogen storage capacities and equilibrium pressures for HPGA LaNi5, LaNi4.75Sno.25' and MmNi3.5Coo.sAlo4Mflo3 were nearly identical to cast alloys after extensive annealing. The large discontinuous volume change across the alpha-beta plateau region for HPGA LaNi5Hx produced extensive fracturing in all but the smallest alloy spheres. 4:30pm NEW ANISOTROPIC RARE EARTH LASER FLUORIDES BaR 2F s(R=Y,Dy-LU): GROWTH AND CHARACTERIZATION: Alexander A. Kaminskii, Andrei V. Butashin, Institute of Crystallography, Russian Academy of Sciences, Leninskii prosp. 59, 117333, Moscow, Russia
2:25 pm INVITED PREDICTING THE DUCTILE-TO-BRITTLE TRANSITION IN NUCLEAR PRESSURE VESSEL STEELS FROM CHARPY SURVEILLANCE SPECIMENS: James A. Joyce, Department of Mechanical Engineering, U.S. Naval Academy, 590 Holloway Road, Annapolis, MD 21402
Anisotropic fluoride crystals doped with Ln 3+ ions have attracted a great interest of investigators as effective active materials for designing multi-wave crystalline lasers, which emit stimulated emission (SE) in the unique number of the 4fN~4fN and 4fN·15dl~4J:1" manifold-to-manifold transitions in UV, visible, and IR spectral ranges. Among them BaR,Fs crystals are distinguished by their Congruent melting at =950°C, good capacity to dissolve activator Ln 3+ ions, wide transparency ranging from VUV to far IR, birefringence and short phonon spectra.
One important application of elastic-plastic fracture mechanics has been to assure the structural integrity of nuclear reactor pressure vessels. Present toughness requirements are based on the postulation of a large defect size, the use of dynamic test data to give lower bound toughness values, and the use of safety factors on the allowable stresses. As vessels have aged the material toughness has degraded and the ductile-to-brittle transition has shifted toward the vessel operating temperature. Extrapolating this process means that many existing vessels will not meet the present toughness requirement. well before the end of their design lives. The need to superimpose multiple safety factors, as is presently done has thus been questioned, and much recent research has been directed toward lessening the toughness requirements while maintaining a high level of structural integrity. The situation remains difficult, however, at least in part because only Charpy specimens are available as surveillance specimens for many commercial reactor vessels, and these speci-
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mens are too small to obtain any type of "valid" fracture toughness information using standard ASTM methods. Presently a lower bound K'R toughness curve is shifted relative to reference temperature RTNOT and used to define the ductile-to brittle transition. The RTNDT is thus a very critical value, and difficulties have arisen because of the wide variability that can result in its estimation. Recent work by ASTM Committee E08 has proposed a method to obtain a new reference temperature and a method to define using a probabilistic approach, a median ductile-to-brittle transition curve from a set of six properly tested small samples which would in many cases be precracked Charpy specimens. This method seems to be very robust, predicting a reference temperature with small variability. From the results of these specimens a "master curve" can be developed defining the median ductile-to-brittle transition curve as well as statistical confidence bounds. This curve is plant specific and could be used to assure that the pressure vessel had adequate toughness for continued operation. This paper presents a large data set on two pressure vessel steels, A515 and A533B, obtained to investigate the newly proposed ASTM test method. Data is available on a large number of precracked Charpy specimens, as well as data on standard IT C(T) and SE (B) specimens. Additional data is also available on large specimens, specimens with shallow cracks (afW =0.1), and surface cracked geometries tested in tension, bending, and combined tension and bending. Most specimens demonstrated cleavage failure - in some instances after significant amounts of ductile crack extension. Since the data sets are not presently complete, how well the new procedure fares cannot be determined. The applicability of constraint quantification and correction techniques that are presently being developed separately by this project will be included in the final analysis. The comparison of the large and small specimens, the surface cracked and through cracked specimens, and the predominantly bend and tensile loadings should allow a clear determination of the value of the new proposed ASTM "master curve" approach. 2:50 pm INVITED A COMMON FORMAT APPROACH FOR APPLYING DUCTILE FRACTURE MECHANICS: John D. Landes+ and J. R. B. Cruz'· +Department of Mechanical and Aerospace Engineering, University of Tennessee, Knoxville, TN 37996; IPEN, 'Sao Paulo, Brazil (on leave to the University of Tennessee) Applications of ductile fracture mechanics methods to prediction of structural behavior can be done using numerical or analytical methods. Numerical methods can be more accurate but are often beyond the capability of ordinary engineering organizations. Also the result may have relevance only to the specific structure being analyzed. Analytical methods have often used a failure diagram approach in which the failure load of a structure can be estimated. A ductile fracture methodology proposed by Landes, et. al. took the load versus displacement for a laboratory specimen and through a series of analytical steps predicted the load versus displacement behavior for a structural component. The prediction could be made for any geometry where the infonnation on limit load, and the calibration of fracture parameters was available. This prediction gave a more complete information in that both the maximum load could be determined as well as the stability of the structure after maximum load. The prediction of the loading behavior during ductile fracture depends on the deformation behavior of the structure and the cracking behavior, usually the former is the more important. The ductile fracture methodology uses a principal of load separation proposed by Ernst in which the loading of a cracked body can be specified by separate but multiplicative functions, one of geometry, that is cracking behavior, and one of deformation. The load versus displacement for the specimen is separated into two functional behaviors, a transfer is made for these functions from the specimen geometry to the structural component geometry and two functions are combined to predict load versus displacement of the structural component. The entire procedure could be completed with a hand calculator. Since the first proposal of this ductile fracture methodology, additional work has been done on the determination of the deformation behavior for the structural component. Donoso, et. al. showed that deformation behavior of any structural component, including test specimens geometries, can be derived from the basic stress-strain behavior of the material. With this the deformation behavior of the component can be determined from that of the specimen using common functional expressions with similar constants, ones that be determined from the stress-strain behavior and transferred to any common geometry with a set calibration factors that pertain to that geometry. This approach was labeled, the "common format" approach. Using this "common format"
approach the ductile fracture methodology was revisited to see if the procedure could be simplified using the calibration factors to transfer from one geometry to another, namely from test specimen to structural component. This paper describes the result of that study. What was found was that the 'common format' calibration factors can be used to transfer the load factors based on material stress. However, a difficulty rose with the transfer of strain factors. The relation of the structural displacement to strain behavior is sensitive to the type of displacement being measured, that is placement of the gage, and gage length. In order to complete an easy transfer of specimen deformation characteristics to the structural component, strain calibration factors need to be determined. With the development of these, the procedure in the ductile fracture methodology can be made easier and application of ductile fracture mechanics greatly facilitated. 3:15 pm BREAK 3:25 pm A NEW MODEL TO CALCULATE THE CRACK EXTENSION: Inhoy Gu, Department of Mechanical Engineering, Chung-Ang University, Seoul 156-756, South Korea A fracture analysis method is proposed on the criterion that the resistance to crack extension can be characterized in the critical CTOA, an instantaneous ratio of CTOD increment to stepwise crack extension. The CTOD of finite element analysis is written in a function of crack length and applied stress for the load range up to near the limit load. The normalized CTOD function for the compact specimen is independent of crack length ratio with some conditions, under which the function can be used in the crack-extension analysis. After crack initiation, the CTOD increments due to a load increment and a crack increment are successively calculated to determine another crack extension, with their integrations during the stable crack growth. The calculations are made to fit to the tests of effective crack lengths by appropriate fracture constants. The cleavage fracture mode is characterized in the crack growth without crack opening. The total CTOD for the cleavage fracture of AI 7075-T651 increases a little as the specimen size increases greatly. Thus the cleavage fracture may occur with a rising load in big specimens and with a falling load in small specimens. The critical CTOA for the ductile fracture of Al 2024-T351 decreases with an increasing specimen size. The size-corrected fracture constants are applied to calculate the failure loads on other compact and center-cracked specimens, in good agreement with the available test loads. The fracture-predicting capability of the proposed method seems promising from cleavage to ductile fracture modes regardless of crack extension, probably, except the limit-load fracture. Therefore, the fracture constants may account for specimen property as well as material property, and they are transferred between specimens. 3:50 pm INVITED DUCTILE FRACTURE OF HIGH TOUGHNESS STEELS UNDER MULTIAXIAL TENSION: D. M. Goto, J.P. Bandstra, D. A. Koss, Department of Materials Science and Engineering, Penn State University, University Park, PA 16802; Concurrent Technologies Corporation, 1450 Scalp Avenue, Johnstown, PA 15904 The influence of stress state on ductile fracture is examined on the basis of both experiments and computational modeling. Using HY-I 00 steel as a model material, we examine the failure of notched tensile specimens in terms of the void initiation, growth, and linking process. Particular attention is given to the issue of void linking as a result of either global coalescence, which occurs at high stress triaxilities, or a localized void-sheet process, as is observed at high stress triaxilities. The void-sheet mode of linking is modeled on the basis of microstructural conditions present in the HY-IOO steel with the result that the predicted influence of stress state agrees well with experimental observations. The transition to global void coalescence, and a much greater sensitivity of failure stress to stress state, is also addressed. This research was supported by the Office of Naval Research, the Naval Surface Warfare Center, and Concurrent Technologies Corporation.
source hardening which lead to interesting effects of thermal neutrons on radiation hardening of these materials.
4:15 pm INVITED MIXED·MODE NON·LINEAR FRACTURE ALONG INTERFACES: John L Bassani, N.J.-J. Fang, Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104
5:20pm USE OF X·RAY TOMOGRAPHIC MICROSCOPY TO STUDY DUC· TILE FRACTURE: Wayne E. King, G.H. Campbell, D.L. Haupt, J.H. Kinney, R.A. Riddle, w.L. Wien, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box S08, Livermore, CA 94551-9900
Recently, problems in interfacial fracture have led to a general interest in planar crack growth under mixed-mode loading. Of particular interest is the relationship between the applied stress intensity/mode-mix and the corresponding quantities near the crack tip. We have developed mixed-mode solutions of the HRR type and of the Hui-Riedel type for stationary and propagating interface cracks. In contrast, asymptotic and small-scale yielding solutions for the crack growth in a time-independent elastic-plastic material predict that the mode mix (tension versus shear) in the vicinity of the crack tip can only take on discrete values rather than varying continuously with the mode mix of the remotely applied elastic fields. In the case of a stationary interface crack or a growing creep crack in either homogeneous materials or along interfaces we have found crack-tip solutions which admit a continuous variation of mode mix within certain limits. Slip line solutions for stationary interface cracks have also been developed. These asymptotic solutions are in good agreement with small-scale-yielding finite element calculations that include the transient growth period.
X-Ray tomographic microscopy (XTM) is a promising technique to investigate ductile fracture because voids formed under conditions of high triaxiality can be directly observed nondestructively. In this experiment, ultra high vacuum diffusion bonding has been used to make model specimens in the AU sapphire system. Samples were prepared in the 4-point bend geometry with notch. XTM images acquired after several loadings of the sample revealed the morphology of the growing voids. The primary finds are that (i) damage ahead of the notch initiates by interface debonding at a location coinciding with maxima in triaxiality and tensile traction at the interface, (ii) debonding occurs at the most early stages in the observation of plasticity, (iii) the debond expands for a limited distance, likely arresting due to crack tip blunting, (iv) this lenticular debond then becomes spherical with further strain, and (v) intergrowth of the spherical voids leads to the typical ductile rupture fracture surfaces observed in the system. This work performed under the auspices of U. S. Department of Energy and the Lawrence Livermore National Laboratory under contract No. W-7405-Eng-4S.
4:40pm RECENT ADVANCES IN THE APPLICATION OF THE GURSON MODEL TO THE EVALUATION OF DUCTILE FRACTURE TOUGH· NESS: Winfried Schmitt, D. oZ. Sun, J. G. Blauel, Fraunhofer Institut Werkstoffmechanik, Fraunhofer IWM WiihlerstraBe 11, D-7910S Freiburg, Germany
5:40pm MICROPLASTICITY AND DUCTILE FRACTURE IN METALS: Wally o. Soboyejo, B. Rabeeh, J. Dipasquale, R. Pryor, Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus OH 43210-1179
For many metallic materials the Gurson model modified by Needleman and Tvergaard describes the ductile rupture process characterized by nucleation, growth and coalescence of voids. Since these local processes are similar in smooth specimens and in cracked specimens, a material dependent critical volume fraction of voids, Ic, may be determined from numerical analyses of tensile tests. However, because of the strong gradient in the stress-strain field at the crack tip an additional length parameter, I" is required to model the coalescence process in cracked specimens. Since the effects of triaxiality are adequately taken into account in the model, Ic and I, may be transferred to specimens with different shapes and sizes. Hence, it is possible to evaluate ductile fracture resistance curves for different geometries and loading conditions with the same set of micromechanical parameters. The authors have applied this local approach to ductile fracture for a series of ferritic and austenitic steels including weld materials even after neutron embrittlement. Besides notched and smooth tensile specimens of standard sizes also miniature specimens with diameter down to 2 mm have been used for the determination oflc. Dynamic effects have been taken into account based on dynamic tensile tests and visco-plastic formulation to model the strain-rate sensitivity of the stress-strain curves. The characteristic length is usually determined for small SENB-specimens. As examples, instrumented impact tests with SENB and Charpy specimens have been simulated using three-dimensional models.
Recent evidence of microplasticity in ductile metals is presented for a range of ductile metals with cubic and hexagonal closed packed structures deformed to failure under monotonic loading. Microplasticity is shown to occur at very low stress levels (-5 - 10%) of the bulk stress. Microscopic of microplasticity evidence is shown to include: slip band localization via shear localization; grain boundary sliding; subgrain formation; deformation-induced precipitation; and localized flow mechanisms. Ductile fracture is shown to initiate by coalescence of voids that are nucleated around stress-induced precipitates. Deformation in the so-called elastic regime is shown to be associated ViI ith the spread of localized plasticity phenomena across the gauge. Linear plasticity concepts are used to explain the initial deformation characteristics. The implications of microplasticity are also assessed for fatigue damage initiation and ductile fracture initiation.
5:00pm SUPERIMPOSED EFFECTS OF DSAAND NEUTRON·IRRADIATION ON MECHANICAL AND FRACTURE BEHAVIOR OF FERRITIC STEELS IN THE UPPER SHELF REGION: Rao K. Mahidhara i and K. Linga Murty2, 'Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; 2North Carolina State University, P. O. Box 7909, Raleigh, NC 27695 It is now well established that radiation embrittlement of ferritic steels such as used for pressure boundary applications is sensitive not only to the alloying elements (Cu, Ni, P etc.) and interstitial impurities (lIAs) such as C and N, but also radiation flux and irradiation temperature. The increased strength and decreased ductility in the DSA region leads to reduced energy to fracture and this region usually lies in the upper shelf regime. This is also clearly evident in the elastic-plastic thcture toughness (JiC). While dips in the fracture energy are noted in steels, pure (Armco) showed peaks in this region apparently due to the increased rates of work-hardening. Exposure to neutron irradiation suppressed the effects of DSA leading to apparent increased energy values at temperatures where dips are noted in the unirradiated materials. Such tests on pure iron are in progress and results to-date will be reported here. Radiation effects on Hall-Petch relation are investigated in pure iron, and radiation exposure resulted in increased friction hardening and decreased
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tion of the load train. The method of computing RBR parameters, Gf and hf from the tensile test data at ambient and elevated temperatures, is described.
RECENT ADVANCES IN FRACTURE: A Symposium Dedicated to Emeritus Professor Frank A. McClintock: POSTER SESSION: Mechanics of Fracture
With W the energy absorbed by the specimen from necking to fracture and
A the u:tiform cross-sectional area at the necking point, the parameters GfWpj A n estimates the average energy per unit cross-sectional area required to cause fr~cture. Also, with A as the minimum cross-sectional area of the neck at fracture, In(AjA) me~sures the average longitudinal plastic strain perpendicular to the pl~e of the neck accumulated from the point of necking to fracture. Therefore, the parameter, lj=Gjln(AjA} estimates the .avera~e i~ cremental plastic energy per unit volume by the specimen per umt longitudInal plastic strain at the neck to sustain the fracture process. In the post-necking regime of tensile deformation with progressive development of the neck, the absorption of energy tends to get increasingly confined to the near-neck section, and therefore G and more so lj reflect the resistance of this region to microvoid growth. He;ce, for an initially homogeneous ductile specimen, the RBR parameters estimate the toughness in a severely work-hardened condition and for a state of stress which is a combination of uniaxial tensile and hydrostatic stresses. For a specimen with gradient in toughness along its length, for example a transverse-weld specimen the neck is expected to initiate at the section least resistant to microvoid growth. For such a specimen, therefore the RBR method automatically determines the toughness of the weakest section, without a prior knowledge as to its location or the need for placing a notch or crack in the section. The advantage of the RBR method has been successfully exploited to characterize the effect of aging of three different dissimilar metal weld (DMW) joints viz. (i) an Alloy 80012.25Cr-IMo steel joint (at 300 K), (ii) an Alloy 800/9Cr-IMo steel joint (at 300 K) and (iii) a type 316LN stainless steel/Alloy 800 joint (at 773 K), including determination of the optimum post-weld heat treatment (PWHT) temperature determined from the RBR toughness parameters is identical to that determined by the conventional method of correlating the microstructure with conventional tensile properties. For the Alloy 800/9Cr-IMo steel DMW joint, the RBR toughness parameters led to unambiguous identification of the optimum PWHT temperature while the conventional structure-property method failed to do so. The efficacy and sensitivity of the two new ductile fracture toughness parameters have also been demonstrated.
Sponsored by: MSD Flow and Fracture; SMD Mechanical Metallurgy Committees Program Organizers: Dr. R. K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; Dr. A. B. Geltmacher, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375; Dr. K. Sadananda, Naval Research Laboratory, Code 6323, 4555 Overlook Drive SW, Washington D. C. 20375; Dr. P. Matic, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375 Monday-Thursday February 10-13, 1997
Room: 314A Location: Orlando Convention Center
Session Chairperson: Dr. R. K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134
APPROXIMATE SOLUTIONS FOR STRAIN HARDENING SOLID WITH A CRACK: Yu G. Matvienko, Mechanical Engineering Research Institute, Russian Academy of Sciences, 4 Griboedov Street, 101830 Moscow, Russia A working out of nonlinear fracture mechanics criteria and application of calculation methods requires the availability of solutions to elastic-plastic crack problems. Such solutions depend on details of deformation behaviour of materials. For most cases the solutions must be computed numerically and that could be connected with some difficulties. Therefore, a working out of approximate analytical solutions is an actual problem. New analytical solutions relate I-integral to applied stress, notch (crack) geometry and strain hardening. The method is based on stress concentration analysis near a notchcrack tip in strain hardening solid. Approximate analytical I-solutions are calculated in accordance with the theoretical stress concentration factor formulas of Neuber for several crack configurations: elliptical notch in infinite plate, deep grooved shaft, deep double etch notch, shallow double notch in tension. The important role of I-integral is a measure of the intensity of the near-tip stress and strain that can be written in the form of the HRR-singularity. So, to assess I-dominance for fully plastic conditions the HRR-model and the method based on an equation of equilibrium was employed. It was assumed that (i) the characteristic size of the singularity is determined by the condition of the equality of the singularity stress and the applied stress, (ii) the force, that is not transmitted by the crack, is counterbalanced by the additional force of the singularity stress field depends strongly on the crack size and weakly on hardening. To predict the behaviour of a crack in ductile materials it is necessary to use non-linear fracture mechanics criteria. One such criterion can be associated with the failure assessment diagram (FAD) which merges the two extreme brittle fracture and plastic collapse. New FAD has been obtained from the energy balance taking into account crack tip blunting and difference between the energy of surface stresses and the surface energy. The present work assumes the relation between crack blunting and I-integral.
SIMPLE STOCHASTIC MODELS OF FRACTURE WITH HEALING: M. Ausloos, R. D'Hulst, N. Vandewalle, SUPRAS, Institut de Physique B5, Universite de Liege, B-4000 Liege, Belgium There are several ways of approaching the problems of fracture. One of them is through algorithmic modelisation. We follow the ideas of a stochastic process, i.e. the most extreme situation, in order to find whether general behaviors of fracture phenomena can be quantified and if so through which ingredients. We use the numerical power of coarse grain cases allowing for easy access to asymptotic time regimes. Atoms on sites in a two dimensional plane are supposed to be ejected inside or outside an initial boundary. Several "percolatiOn/fracture-like" path were found as a function of size. The concentration of the various crack thresholds, the distribution of clusters, the fractal dimension of the cracks were obtained. Power law features were indicative of essential processes. It will be shown that the rules give sometimes rise to "healing processes". ATOMISTIC STUDIES OF CRACK PROPAGATION: Diana Farkas, Vijay Shastri, Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0219
ESTIMATION OF DUCTILE FRACTURE TOUGHNESS FROM TENSILE TESTS FOR ENGINEERING APPLICATIONS: S.K. Ray, A.K. Bhaduri and P. Rodriguez, Fracture Mechanics Section, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
We will present the results of atomistic studies of fracture in ordered intermetallic alloys using the embedded atom method. The propagations of cracks is studied through atomistic computer simulation with particular emphasis on the competition between crack propagation and dislocation emission processes at the crack tip. The boundary conditions for these simulations are obtained from continuum elasticity theory and the region close to the crack is allowed to relax in order to achieve the minimum energy configuration. The atomistic simulations enable the study of the local atomic configuration at the crack tip in a realistic crystal structure and its importance for crack propagation. The studies include the simulation of crack structure and propagation in the presence of dislocations, in an effort to contribute to the modeling of ductile fracture processes.
An empirical method for characterizing the ductile fracture toughness using two parameter (viz., Gf and hf) that can be determined from tensile test data of smooth cylindrical specimens has been evolved for engineering applications by Ray, Bhaduri and Rodriguez (herein after referred to as the RBR method). This stipulates that the post-necking regime during tensile deformation is demonstrated by microvoid growth and coalescence processes, and therefore the energy absorbed in this regime can be used to estimate the resistance of the necked region to ductile fracture. The test procedure employed is simple, and does not require gauge-length extensometry. The test is carried out in a screw-driven machine at constant cross-head speed, with on-line deforma-
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COMPARISION OF LOCALIZED NECKING CRITERIA USED IN FINITE ELEMENT ANALYSIS OF SHEET METAL FORMING OPERATIONS: Sriram Sadagopan, Robert H. Wagoner, Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus, OH 43210
ness of ductile fracture decreases with temperature and is proportional to the root square of the yield stress. All the conclusions are proven using fractographical data. EFFECTS OF INCLUSIONS ON DUCTILE FRACTURE OF AN E'I!42PCT Ni ALLOY IN TENSION AND SHEAR: N. Yuki., R. Foley" and G. Krauss''', 'Nippon Mining and Metals Company Ltd, 3 Kurami, Samukawa, Koza, Kanagawa 253-01, Japan; "Department of Mechanical, Materials and Aerospace Engineering, Illinois Institute of Technology, Chicago, IL 60616; '''Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401
Localized necking is one of the most common failure modes limiting formability in technological sheet metal forming operations. Prediction of localized necking for general three dimensional components using finite element simulations can be very useful in die/process design. Different failure criteria, based on macroscopic quantities, are used to predict localized necking. This presentation will compare the results from these different failure criteria for some standard geometries. The effect of applied boundary conditions on these results will also be discussed.
Effects of inclusions on ductile fracture have been examined with laboratory produced Fe-42 pct Ni alloy. The inclusion volume fraction was varied between approximately 0.01 and 3.00 pet. Axisymmetric tensile bars and cylindrical, double shear test samples were tested in the recrystallized condition. In the tensile test, increasing inclusion volume fraction significantly reduced post-uniform elongation and strain to fracture. In the shear test, fracture displacement obtained from load-displacement data and strain to fracture calculated from shear test samples decreased with increasing inclusion volume fraction. The fracture behavior in tension and in shear is related to inclusion distribution. Applicability of different models is considered.
MICROPLASTICITY AND DUCTILE FRACTURE IN A METASTABLE BETA TITANIUM ALLOY: Wally O. Soboyejo+, B. Rabeeh' and S. Rokhlin" +Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus OH 43210-1179; *Department of Industrial, Welding and Systems Engineering, The Ohio State University, 190W. 19th Ave. Columbus OH 43210 Micromechanisms of tensile deformation and fracture in a metastable beta Ti-15V-3Cr-3Al-3Sn alloy are elucidated in this paper. Tensile deformation is shown to be associated with significant levels of microplasticity at stress levels above -10% of the tensile yield strength. Microplasticity in the socalled elastic regime is shown to occur via shear localization and concomitant slip band formation; grain boundary sliding; subgrain formation; stress induced a phase precipitation; and atomic flow mechanisms that are not fully understood at present. Ductile fracture is also shown to initiate by decohesion around a precipitates produced largely via stress-induced precipitation. Catastrophic failure in the metastable beta Ti-15V-3Cr-3AI-3Sn alloy is shown to occur by the coalescence of microvoids produced via decohesion around a precipitates. Attempts are made to model the ductile fracture processes using classical ductile fracture theories. The implications of the microplasticity phenomena are also discussed within the context of elasticity and plasticity theories.
NEUTRON IRRADIATION EFFECTS ON THE DUCTILE-BRITTLE TRANSITION OF FERRITICIMARTENSITIC STEELS: Ronald L. Klueh and D. J. Alexander, Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 Below -4500C, neutron irradiation hardens the Cr-Mo ferritic/martensitic steels considered for future fusion power plants. Hardening reduces ductility, but the major effect is an increase in the ductile-brittle transition temperature (DBTT) and a decrease in the upper-shelf energy (USE), as measured by a charpy impact test. After irradiation, DBTT values can increase to well above room temperature, thus increasing the chances of brittle rather than ductile fracture. Such a shift in DBTT could eliminate certain steels for nuclear applications. Steels are being developed for fusion applications that have a low DBTT prior to irradiation and then show only a small shift after irradiation. Low-chromium (3% Cr) and high-chromium (9% Cr) CroW steels are being investigated. Amartensitic 9Cr-2WVTa (nominally Fe-9Cr-2W-0.25V-0.07TaO.IC) steel had a much lower DBTT than the conventional 9Cr-lMoVNb (Fe-9Cr-lMo-0.25V-0.06Nb-0.1 C) and l2Cr-lMoVW (Fe-12Cr-lMo-0.25V0.5W-0.5Ni-0.2C) steels prior to neutron irradiation and showed a much smaller increase after irradiation. The tantalum in 9Cr-2WVTa was concluded to affect the fracture stress. For the 3Cr steels, the type of bainitic microstructure formed during heat treatment affected the impact behavior. Granular bainite had inferior properties compared to an acicular bainite. Alloying was used to promote the acicular bainite. Improved toughness makes the steels candidates for both nuclear and non-nuclear applications.
ON THE MECHANISMS AND TOUGHNESS OF DUCTILE FRACTURE: Alexander D. Vasilevand S. A. Firstov, Francevich Institute for Problems of Materials Science, 3 Krjijanivskoho str., Kyiv-142, UA-252680, Ukraina The mechanism of ductile fracture of metallic and some ceramic materials subjected to uniaxial and bending loading in a wide temperature range as well as fracture toughness, and its temperature and structural dependencies are discussed. The main instrument that was used to formulate the ductile fracture mechanism was scanning and transmission electron microscopy of single and polycrystalline, and strengthened by particle<, materials. On the basis of study of fracture surfaces of pre-deformed pure particleless materials, the mechanisms of void nucleation, growth and coalescence of voids was found. The pore in particle less materials nucleate along the boundaries of dislocation cellular structure that formed in a course of deformation precedingfracture. The nucleation of pores and subsequent delaminations along the cell and grain boundaries is the main reason of the fracture toughness increase of pre-deformed materials. With the longitudinal cleavage technique it is shown that the intergranular pores nucleate first of all. The decrease of grain size promotes to the transition from cleavage to ductile, by void coalescence, fracture. In materials strengthened with particles there is the temperature region where particles, even with weak interface, do not play the preferable sites of pores nucleation. In those materials, two kinds of ductile, by void coalescence, fracture mechanism may be determined. It is shown that the same mechanism of pores nucleation is valid in ionic (Nact) single crystals but at temperature above 0.6 of melting temperature. In partially stabilized zirconia single crystals some dislocation plasticity arises at temperature above l300°C and results in delaminations along interdomain boundaries that points out the same mechanism of pores nucleation. In silicon nitride ceramics the dimple-like, the so-called foam-like, fracture may be found as a result of decomposition of silicon nitride into silicon oxide and gases at temperature above lOOO°C. To estimate the fracture toughness of materials failed by ductile manner, the formula: where is the yield stress, is the elastic modulus and is the diameter of the dimples, is proposed. It is shown also that tough-
DAMAGE EVOLUTION IN HYPO- AND PSEUDO-EUTECTIC AI-Si ALLOYS: Tz. Kamenova, R. Doglione, lL. Douziech, C. Berdin and Dominique Franliois, Ecole Centrale Paris, Laboratoire De Mechanique, Grande Voie des Vignes, F-92295 Chatenay-Malabry Cedex, France The evolution of fracture processes in an hypoeutectic and in an eutectic AlSi cast alloys has been studied by means of in situ tensile tests SEM observations. Chilled and cast alloys were investigated. It has been established that the damage initiates at low strains (of the order of 0.5%) by fracture of the largest Si particles, situated at the periphery of eutectic colonies. When the strain increases, finer and finer particles break within the colonies. In the hypereutectic alloys further straining induces a concentration of the damage along the fine interdentritic particles alignments. This leads to the formation of intensive slip bands in these regions followed by microcracks coalescence. The cracks thus created stop at the eutectic colonies, until final fracture by their propagation. The validity of the Weibull statistics to describe the number of cracked Si particles as a function of the applied load was proven. It was also observed that the volume increase of the microcracks was very small. These observations allowed to build a model of damage evolution based on micromechanics of inclusions at two different scales, that of eutectic colony and that of the whole specimen, yielding the fracture probability in the various zones.
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EFFECTS OF INCLUSION DISTRIBUTION ON THE FRACTURE TOUGHNESS OF STRUCTURAL STEELS: Warren M. Garrison, Jr., Department of Materials Science and Engineering, Carnegie Mellon University, 3301 Wean Hall, Pittsburgh, PA 15213; Andrzej L. Wojcieszynski, Crucible Research Center, Campbells Run Road, Pittsburgh, PA 15205; Luena E. lorio, Department of Materials Science and Engineering, Carnegie Mellon University, 3301 wean Hall, Pittsburgh, PA 15213
scribed using a conformal mapping procedure. Dislocation microstructures, generated from the crack tip, are shown over a wide range of loading rates. With increasing loading rate, a transition is observed from ductile-to-brittle behavior. However, even when the crack propagates in a brittle manner, significant dislocation emission occurs first. The dislocation microstructures observed are very complex and highly organized. As the load continues to increase, several distinct transitions in dislocation microstructure are observed. The effects of pre-existing dislocation network within the material are also examined. The dislocation network is strongly modified by the crack, decreases dislocation emission from the crack tip and, after evolution in the crack tip field, provides some crack tip blunting.
When fracture occurs by micro-void coalescence the fracture toughnesses of structural steels are controlled by both the inclusion distribution and the finescale microstructure. The characteristics of the inclusion distributions which influence toughness include volume fraction, spacing and void nucleation resistance. The effects of inclusion distributions on toughness are, however, not independent of the fine-scale microstructure and the extent to which varying characteristics of the inclusion distributions influences toughness can depend on the fine-scale microstructure. This talk will focus on three areas. First the effects of inclusion spacing and void nucleation resistance of inclusion particles will be discussed. Second, the degree to which such effects are influenced by fine-scale microstructure, in particular austenite grain size, will be considered. It has been found that the most effective way of minimizing the detrimental effect of inclusions on fracture toughness is to getter sulfide as titanium carbo-sulfide as particles of titanium carbo-sulfide are more resistant to void nucleation than particles of other sulfides such as MnS. Therefore, the third topic to be considered will be the effect of alloy composition on the formation of as titanium carbo-sulfide. This work was funded by the National Science Foundation, The Army Research Office, Teledyne Allvac and the Ben Franklin Program of Pennsylvania.
MECHANISMS OF DUCTILE FRACTURE IN PURE SILVER UNDER HIGH· TRIAXIAL STATES: Michael E. Kassner, Department of Mechanical Engineering and The Center for Advanced Materials Research, Oregon State University, Corvallis, OR 97331 Experimental and finite element method (FEM) analyses were used to study the mechanisms of ductile fracture of constrained, high purity, silver interlayers under high triaxial stress states. Interlayer bonds loaded in simple tension develop a principal stress state that is large and axisymmetric. Ductile, plastic-strain failure was observed in these bonds when the maximum mean stress to yield ratio 0 approached approximately four, in agreement with recent numerical analyses by other investigators, who postulated unstable growth of a cavity subjected to a far-field axisymmetric stress state at this ratio, without significant far-field plastic strain. Ambient temperature delayed-failure (creep) tests of constrained silver interlayers, at relatively low applied loads, also appear to be due to unstable cavity growth. The mechanism of ductile fracture was further studied by biaxially loading these interlayers through the application of various combinations of tension and torsion loads. Low macroscopic-strain ductile fractures are again observed, but the axisymmetric and non-axisymmetric failure-stress values and FEM analysis of the stress levels required for cavity instability do not directly support an unstable growth model, even when considerations for plastic incompatibilities across grain boundaries are considered. Other ductile fracture theories such as cavity nucleation and interlinkage warrant consideration.
FRACTURE TOUGHNESS OFWC·Co CERAMIC·METAL COMPOS· ITES: James M. Densley, Carolyn E. Graves, John P. Hirth, Department of Materials and Mechanical Engineering, Washington State University, Pullman, WA 99164 The fracture toughness of a normal and nanoscale grain size WC-Co ceramicmetal composite with same compositions are compared. The fracture behavior is discussed as a mechanism of localized plastic deformation. Analysis of the cermets is done by both pure mode I and mixed-mode 11111 fracture toughness methods.
THE EFFECTS OF STERILIZATION AND OXIDATION ON THE FRACTURE OF 'ARTIFICIAL CARTILAGE' (ULTRA·HIGH MOLECULAR WEIGHT POLYETHYLENE): Thomas J. Mackin and Jeff Windau, Department of Mechanical and Industrial Engineering, The University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801
EFFECT OF LOADING MODE ON FRACTURE PROPERTIES OF A VANADIUM ALLOY: H.-X (Huaxin) Li, RJ. Kurtz, R.H. Jones, Pacific Northwest National Laboratory, P. O. Box 999, Mail Stop IN P8-15, Richland, WA99352 The effect of mode I and mixed-mode 11111 loading on the fracture behavior of a vanadium alloy containing 4 wt% Cr and 4 wt% Ti (V4Cr4Ti) was investigated at room temperature. The V4Cr4Ti alloy was annealed at lOOO°C for I hour in vacuum. Compact tension (CT) specimens were used to study mode I properties and modified compact tension (MCT) specimens were used for mixed-mode 11111. A MCT specimen is the same as a CT specimen except the principal axis of the crack plane is slanted at an angle of 25 and 45 degrees from the load line. When the crack angle is equal to zero, a MCT specimen becomes a CT specimen. With the MCT specimen, an applied load can be resolved to mode I load (P) and mode III load (Pi.) at the crack tip. The mixities [PJPiii+PJ used were 0, 0.32 and 0.5 for crack angles 0, 25 and 45 degrees, respectively. It was found that the introduction of PHi dramatically lowered fracture toughness of V4Cr4Ti alloy. The mechanism how mixedmode 11111 loading affects fracture behavior of the V4Cr4Ti alloy is discussed.
Ultra-high molecular weight polyethylene (UHMWPE; 4xl03 g/mole) is commonly used as artificial cartilage in orthopedic implants. Several processing methods are used to fabricate the stock material, followed by machining, and gamma-irradiation sterilization prior to final implantation. Over the 15 year anticipated lifetime, cyclic and tribologicalloading change the properties of the material. The need for improved implant lifetimes motivated a detailed investigation of the relationships between processing/sterilization and properties in UHMWPE. Gamma irradiation changes the mechanical properties by promoting enhanced crystallization, while lifetime aging results in the formation of carbon-oxygen groups that change the subsequent properties. Both effects improved the ductility of the materials and led to overall improvements in yield strength, tensile strengths elastic modulus. These results are in sharp contrast to previous studies where any increase in crystallinity decreased the ductility of the UHMWPE. A broad array of experimental techniques were utilized to verify the measured changes in microstructure and properties. We will report on these changes in mechanical properties coupled with a fractographic analysis of failed specimens to relate the mechanisms of ductile failure in UHMWPE to the microstructural changes brought about by production, fabrication, sterilization and aging of these implant materials.
DYNAMICALLY GENERATED DISLOCATIONS SUB·STRUCTURE AHEAD OF A CRACK TIP: N. Zacharopoulos', DJ. Srolovitz' and R A. LeSar", 'Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109; "Center for Materials Science, Los Alamos National Laboratory, NM 87545
A MIXED·MODE FRACTURE MECHANISM MAP: M. Manoharan, Division of Materials Engineering, School of Applied Science, Nanyang Technological University, Singapore-639798, Singapore
We investigate the propagation of a semi-infinite, mode III crack at constant KIll' At each time step, crack can grow and/or screw dislocations can be emitted from the crack tip. This model incorporates dislocation interactions with the crack, other dislocations, and all image dislocations. The emitted dislocations can significantly shield the crack. Dislocation-dislocation and dislocation-crack interactions are calculated using the fast multipole method applied within a stress-function framework. Dislocation-crack interactions are de-
As fracture mechanics has developed as a discipline, many parameters have been developed to characterize the instability condition. However, a majority of this work has been confined to the investigation of mode I fracture. Thus, we have standardized methods for experimentally determining Krc ' J IC and J-
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resistance curves for mode I crack propagation. However. cracks in real materials can be SUbjected not just to tensile stresses but to complex stress states so that the development of suitable parameters to characterize mixed-mode crack initiation and propagation is important in the evolution of suitable design criteria. Further, observations indicate that initially flat cracks in some tough materials tend to reorient themselves to oblique planes during growth. For these materials, crack propagation can be said to occur under combined mode conditions. A considerable amount of work on mixed mode I1IIl fracture toughness of materials is available. The superposition of mode III loading results in drastic reduction in fracture toughness in some materials whereas in other materials it has little effect or even results in an increase in the fracture toughness. Fracture mechanism maps delineating regions of susceptibility to tensile and shear loads have been proposed. In this paper, data on a wider range of materials, including steels, aluminum alloys, metal matrix composites, ceramics and polymers will be used to extend and reinforce the fracture mechanism map concept. EFFECTS OF STRESS STATE ON DEFORMATION AND FRACTURE OF STRUCTURAL MATERIALS: John J. Lewandowski, Dept. of Materials Science and Eng., Case Western Reserve University, Cleveland, OH 44106 The deformation and fracture of structural materials is significantly affected by changes in the microstructure and imposed stress state. Such changes in stress state may affect the micro-mechanisms of failure whereby a material which normally fails in a ductile manner may undergo a ductile-to brittle transition. In other cases, the imposition of a more severe stress state may accelerate the stages of ductile fracture to such an extent that very low ductility is obtained. The imposed stress state may be easily changed via testing notched specimens or via testing with confining pressure in monolithic materials. The presentation will review previous and ongoing work investigating the effects of stress state on the fracture of a variety of metallic materials, including more recent work on metallic composites.
SHAPING AND FORMING OF HIGH PERFORMANCE POWDER PRODUCTS: SESSION I Sponsored by: MDMD Powder Materials Committee Program Organizers: Dr. William E. Frazier, Naval Air Warfare Center Aircraft Division, Patuxent River, MD 20657; Prof. Henry R. Piehler, Dept. of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213; Dr. Jeffrey Waldman, Dept. of Materials Engineering, Drexel University, Philadelphia, PA 19104; Dr. Phillip Parrish, MATSYS Inc., Arlington, VA 22209
Monday, PM February 10, 1997
Room: Salon 7 Location: Clarion Plaza Hotel
Session Chair: Dr. Phillip Parrish, MATSYS Inc., Arlington, VA
to consolidation, following the debulking, i.e., binder off-gassing, and pow· der settling and fiber rearrangement, of the initial tape-cast powder/fiber monotape.
3:00pm A DENSIFICATION CONSTITUTIVE MODEL FOR POWDER BASED ALUMINUM MATRIX COMPOSITES MATERIALS: Erik J. Jilinsk, John 1. Lewandowski, Dept. of Material Science and Engineering, Case Western Reserve University, Cleveland, OH 44106; Paul T. Wang, The Aluminum Company of America, Alcoa Technical Center, Alcoa Center, PA 15169 Intelligent, cost effective processing of powder based materials requires an understanding of the key physical variables during processing and the ability to implement these variables into suitable analytical models that can describe the overall consolidation behavior of the powdered material during fabrication. In this presentation, a modified form of the Ourson continuum level densification model, derived through a micromechanical approach, is developed and applied to an aluminum metal matrix composite reinforced with SiC particulate. The results of this model, also applicable to short or chopped fiber reinforced powder based composite material, capture the influence that volume fraction of reinforcement has on the densification of the powder based aluminum alloy metal matrix composite and provides the first step of the analytical framework needed for designing a process model capable of describing the consolidation behavior of the composite material during a powder forging type fabrication process.
3:30pm MODELING THE HOT CONSOLIDATION OF METAL POWDERS AND METAL-MATRIX COMPOSITES: R.E. Dutton, S.L. Samiatin, Materials Directorate, Wright Laboratory, WLlMLLM, Wright-PattersonAFB, OH45433 The modeling of the deformation and densification behavior of metal powders during hot consolidation processes was treated through the application of a continuum yield function and associated flow rule modified to incorporate microstructure effects such as grain growth, pore size, and pore geometry. It was shown that consolidation behavior can be described over the entire range of densities through two parameters, Poisson's ratio and the stress intensification factor, which are readily measured using uniaxial upset tests. The accuracy of the material modeling approach was validated by comparing the densification predicted from both a simple analytical model and an FEM with observed behavior during the die-pressing of monolithic gamma titanium aluminide powder and the hot-isostatic pressing oftapecast monotape composite layups comprising alpha-two titanium powder and continuous silicon carbide fibers. In addition, the effect of pore anisotropy on the yielding and flow behavior of partially consolidated powder compacts was addressed.
4:00 pm 2:00pm 3-D HIP MODELING: RESULTS ON NON-AXISYMMET4RIC PARTS: WE. Eisen, Crucible Research Center, 6003 Campbell's Run Rd., Pittsburgh, PA 15205 Abstract not available.
2:30pm MODELING OF THE POWDERIMONOTAPE METHOD FOR TITANIUM MATRIX COMPOSITE CONSOLIDATION: e.e. Bampton, KJ. Newell, Rockwell Science Center, P.O. Box 1085, Thousand Oaks, CA 91358 A computer model, Discrete Element Consolidation Analyzer (DECA), is described which was developed with support from Wright Laboratory, to assist in the optimization and control of the so-called tape-cast powder monotape processing method for titanium matrix composite consolidation. DECA simulates the viscoplastic densification of a randomly packed spherical titanium alloy powder aggregate and continuous fiber array by hot pressing. Using state variable analysis together with automated remeshing, the model performs a continuous simulation of powder particle contact-contact interaction, free surface evolution and void closure. A unique capability of this model is the realistic simulation of the final random powder packing geometry, prior
PHYSICAL MODELING OF THE EARLY STAGES OF METAL POWDER CONSOLIDATION AND COMPARISON TO EXISTING ANALYTICAL MODELING APPROACHES: David P. DeLo, Henry R. Piehler, Dept. of Materials Science and Engineering, Carnegie Mellon Univer&ity, Pittsburgh, PA 15213 The important mechanisms during the early stages of metal powder consolidation are not well understood nor are they properly included in consolidation models. The result is that models tend to underpredict strain-rates, particularly during the early stages of consolidation. In a series of interrupted HIP experiments, PREP Ti-6AI-4V powder was consolidated in thin-walled containers, and the resulting partially consolidated specimens examined metallographically. Stereo micrographs of fractured specimen surfaces were examined qualitatively and quantitatively to gain insights into early stage mechanisms and appropriate modeling approaches. Evidence of particle rearrangement was found throughout the early stages of consolidation. Contact areas between particles increase in size at a much slower rate than is predicted by popular mechanistic models. Particle size effects, including rigid body motion of larger particles facilitated by preferential deformation of small particles, contribute to rearrangement. The critical assumptions required for common mechanistic and continuum models are not consistent with the observed mechanisms and behaviors requiring new modeling approaches that are consistent with the observed behavior.
I ' " " . mlM
4:30pm CONSOLIDATION OF NANOSTRUCTURED METAL POWDERS BY RAPID FORGING: PROCESSING, MODELING,AND SUBSEQUENT MECHANICAL BEHAVIOR: G.R. Shaik, Walter W. Milligan, Dept. of Metallurgy and Materials Engineering, Michigan Technological University, Houghton, MI 49931
2:40pm CAN A BULK AMORPHOUS PHASE BE OBTAINED FROM LIQUID SILICON OR GERMANIUM?: Yan Shao, Frans Spaepen, Division of Engineering and Applied Sciences, Pierce Hall, Harvard University, 29 Oxford Street, Cambridge, MA 02138 A number of methods have been used to undercoolliquid silicon and germanium: levitation melting, flux treatments, atomization, rapid cooling following laser melting of thin films, and quenching of droplet dispersions. An amorphous phase has been produced so far only in small volumes. The competition between the kinetics of nucleation and growth of the crystalline and the amorphous phases under these various conditions will be reviewed, and the possibility of obtaining bulk amounts of the amorphous phase will be assessed.
Nanostructured metals are a potentially-promising class of materials with ultrafine grain sizes. A limitation on commercial implementation of nanostructured materials has been grain coarsening during consolidation. In this research, attritor-milled powders with 20 om grain sizes inside micrometer-sized powder particles were consolidated by induction heating and rapid forging of cold-pressed compacts. Grain growth was limited by minimizing the time at consolidation temperature. Fully-dense materials were obtained at relatively low temperatures around 500°C. The consolidation process was successfully modeled with the Arzt-Ashby-Easterling HIP model, modified slightly for geometrical constraints, stress state and the nature of the nanostructured metal. Modeling and mechanical testing indicated that creep dominated the consolidation process, apparently due to the ultrafine microstructures. Mechanical properties at ambient and elevated temperatures. We gratefully acknowledge the support of the Air Force Office of Scientific Research, under grant F49620-94-1-0255, which is monitored by Dr. Walter Jones, and the National Science Foundation, under grant DMR-92-57465, which is monitored by Dr. Bruce MacDonald.
3:20 pm BREAK 3:40pm THERMODYNAMIC FRAMEWORK FOR SOLID-STATE AMORPHIZATION: D. Wolf, Materials Science Division (MSD-212), Argonne National Laboratory, Argonne, IL 60439 Atomistic computer simulations are used to expose important thermodynamic parallels between melting and solid-state amorphization and the important role of nanocrystalline microstructures. Molecular-dynamics simulations demonstrate that every crystal can, in principle, melt by two entirely different causes and underlying mechanisms; a comparison with experiments suggests that both can be operative in solid-state amorphization I. Also, simulations of a model nanocrystalline material exhibit the existence of low- and high-frequency lattice-vibrational modes not seen in the perfect crystal but also present in the amorphous phase'. The possibility of a reversible, free-energy based transition between these two metastable phases that is governed by a critical grain size is discussed together with possible mechanisms for the transition. Work supported by the US Department of Energy, BES-Materials Science under Contract No. W-31-109-Eng-38.
STRUCTURE AND PROPERTIES OF BULK AMORPHOUS ALLOYS" Sponsored by: Jt. EMPMDISMD Alloy Phases Committee, MSD Thermodynamics and Phase Equilibria Committee, MSD Atomic Transport Committee, MDMD Solidification Committee, Lawrence Livermore National Laboratory and Los Alamos National Laboratory Program Organizers: Patrice EA Turchi, Chemistry and Materials Science Department (L-268), Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551; Ricardo B. Schwarz, Center for Materials Science (MSK765), Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545; John H. Perepezko, Department of Materials Science and Engineering, University of Wisconsin, Madison, WI 53706 Monday, PM February 10, 1997
4:20pm THERMODYNAMIC AND KINETIC PROPERTIES OF AMOR· PHOUS AND LIQUID STATES: A. V. Granato, Physics Department, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, IL 61801-3080
Room: 340A Location: Orlando Convention Center
The magnitude and temperature dependence of the liquid state shear modulus G, specific heat C p' diffusivity D and viscosity T\ are all closely related, according to the interstitialcy model. It has been proposed by Dyne, Olsen and Christensen that the viscosity is given by T\=hoexp(F/kT) where ho is a reference viscosity and F is given by the work required to shove aside neighboring particles in a diffusion process, where F=GVc and Vc is a characteristic volume. In the interstitialcy model, the high frequency thermodynamic liquid state shear modulus is given by G(T)=Goexp[( -')'(T-T,;J], where Go is the shear modulus at a reference temperature To which can be taken as the glass temperature. The resulting non-Arrhenius behavior of the viscosity is compared with experimental data for the shear modulus.
Session Chairperson: Dr. Ricardo B. Schwarz, Center for Materials Science (MSK765), Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545
2:00pm STRUCTURE OF BULK AMORPHOUS ALLOYS DETERMINED BY SYNCHROTRON RADIATION: T. Egami, W. Dmowski, Department of Materials Science and Engineering (LRSMlKI), University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA 19104-6272; Yi He, Ricardo B. Schwarz, Center for Materials Science (MS-K765), Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 The atomic structure of Pd-Ni-P bulk amorphous alloys was studied by the anomalous (resonance) x-ray scattering technique using synchrotron radiation tuned near the Pd K-edge. Bulk samples of Pd~i.J',o' Pd 30NisoP,o' and PdsoNi34PI6 amorphous alloys were prepared by the flux method in the form of rods with the diameter of 10-14 mm. X-ray measurements were carried out at the X-7A beamline of the NSLS, Brookhaven National Laboratory. The results show that the structures are basically described by the dense random packed structure with small chemical short-range order. The implication of this result with respect to the stability of the glass will be discussed.
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STRUCTURE AND PROPERTIES OF INTERNAL INTERFACES II: Interfacial Kinetics and Motion
Sponsored by: Jt. EMPMD/SMD Chemistry & Physics of Materials Committee, MSD Computer Simulation Committee Program Organizer: Diana Farkas, Dept. of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061; Elizabeth A. Holm, Sandia National Lab, Physical and Joining Metallurgy, MS 1411, Albuquerque, NM 87185-0340; David J. Srolovitz, Dept. of Materials Science & Engineering, University of Michigan, Ann Arbor, MI 48109-2136
Monday, PM February 10, 1997
Room: 330G Location: Orlando Convention Center
Session Chairperson: V. Vitek, Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104
1:30 pm INVITED GRAIN BOUNDARY MIGRATION EFFECT OF MISORIENTATION, IMPURITIES, PHASE TRANSITIONS AND TRIPLE JUNCTIONS: L.S. Shvindlennan', G. Gottstein, U. Czubayko, D.A. Molodov, VG. Sursaeva', Institut fijr Metallkunde und Metallphysik, RWTH Aachen, D-52056 Aachen, Germany; 'Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow District, 142432 Russia The mobility of high-angle grain boundaries and triple junctions is the key factor, which controls the recrystallizations and grain growth processes. The mobility of individual <111> tilt grain boundaries in Al was measured under the constant driving force, in-situ, over a wide range of temperatures, in the vicinity of special misorientation and away from it, in ultra-pure Al and in Al doped with small amount of soluble impurities. The steady state motion of grain boundary systems with triple junctions was investigated in-situ at different temperatures on tricrystals of Zn. A transition of the steady state motion of the grain boundary system with triple junction from junction kinetics to grain boundary kinetics was observed. For the first time it was shown that triple junctions are able to drag grain boundary motion. The grain structure evolution in polycrystals for different kinds of kinetics will be discussed. 2:10pm MECHANISMS AND CRYSTALLOGRAPHY OF GRAIN BOUNDARY MIGRATION: A TWO DIMENSIONAL COMPUTER SIMULATION STUDY: M. Upmanyu, R.w. Smith, D.J. Sro]ovitz, Dept. of Materials Science and Eng., University of Michigan, Ann Arbor, MI 48lO9
with lower cavitation. High-resolution grain boundary composition measurements on deformed samples revealed that the Sn remains on the boundary during GBS but the Mg is redistributed in a heterogeneous manner. The points to the possibility of engineering the grain boundary composition for optimized deformation characteristics and post-formed properties such as stress corrosion cracking resistance. Work supported by the Materials Division. Office of Basic Energy Sciences, U.S. Department of Energy under Contract DE-AC06-76RLO 1830. 2:50pm ATOMISTIC CHARACTERIZATION OF CERAMICIMETALINTERFACES: SIMULATION AND EXPERIMENTS: D.A. Shashkov, R. Benedek, & D.N. Seidman, Northwestern University, Department of Materials Science and Engineering, Evanston, IL 60208-3lO8 Our research on ceramic/metal (CIM) interfaces that utilizes transmission electron, high-resolution electron, Z-contrast microscopy, and atom-probe microscopies, in collaboration with ab initio atomistic modeling, is presented. Heavy use is made of atom-probe microscopy to address questions concerning the chemistry of the terminating plane and segregation of solute species to the ceramic/metal interfacial region. Detailed results are presented for the {222) MgO/Cu, {222) CdO/Ag, (222) MgO/Cu(Ag), and (222) CdO/Ag(Au) interfaces. All the CIM interfaces were created via internal oxidation, at elevated temperatures, of high-purity binary or ternary metallic alloys, thereby producing atomically clean interfaces. Solute-atom segregation was induced at the (222) CIM interfaces by annealing specimens containing a ternary addition at 500 D C for prolonged periods of time. The level of segregation, i.e., the Gibbsian interfacial excess, is determined directly by the atom-probe technique. Results concerning ab initio atomistic modeling of the {222) MgO/ Cu coherent interface (zero-misfit approximation), using local density functional theory (LDFT) within the plane-wave pseudopotential framework, are presented for two polar { Ill} and two nonpolar {100} MgO/Cu and CdO/Ag interfaces and are discussed with respect to our experimental observations. This research is supported by the Department of EnergylBasic Energy Sciences. 3:10 pm BREAK 3:30 pm INVITED COMPUTER SIMULATION STUDIES OF THE KINETICS OF INTERFACE DIFFUSION AND PHASE FORMATION: 1.M. Rickman, Dept. of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18lO5-3195
Two dimensional molecular dynamics simulations of grain boundary migration are performed using the half-loop bicrystal geometry employed in the experiments performed by Shvindlerman, et a1. We examine the dependence of the steady state grain boundary velocity on grain boundary curvature by varying the half-loop width at constant temperature. The grain boundary velocity is proportional to the half-loop curvature and the grain boundary mobility follows an Arrhenius relationship. In the present study, we examine grain boundary migration for several different grain misorientations. We employ movies of these simulation in order to deduce the dominant mechanisms of grain boundary migration and how these mechanisms depend on grain boundary structure.
Two kinetic processes associated with grain boundaries are discussed. In the first study, we examine quantitatively the impact of heterogeneous nucleation on the temporal evolution of a phase transformation with particular emphasis on the correlation of nucleation site distribution and product phase microstructure. This is accomplished by investigating spatial correlation~ in the transforming system via the calculation of nonequilibrium correlation functions and by characterizing product grain sizes and shapes. Computer simulations of transformations are employed in order to validate our theoretical description and to relate microstructural features of the evolving phase to relevant length and time scales in the problem. In the second study, we investigate the kinetics of grain boundary diffusion using a spatially inhomegeneous lattice gasmode1. It is found that atomic transport can be accurately described by a series of approximate rate equations and that one can ascribe a bias, in a certain sense, to tagged atoms.
2:30pm INTERACTION OF SOLUTE SEGREGATION AND GRAIN BOUNDARY SLIDING PROCESSES: 1.S. Vetrano, E.P. Simonen, S.M. Bruemmer, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352
4:10 pm INVITED THERMODYNAMICS OF GRAIN BOUNDARY ANISOTROPY AND GRAIN BOUNDARY WETTING: W Craig Carter, John W. Cahn, Materials Science Engineering Laboratory, NIST, Gaithersburg, MD 20899
The sliding of grain boundaries can be influenced by the presence of solute segregants. Additionally, the sliding mechanism itself also triggers vacancy fluxes that may result in the non-equilibrium redistribution of solute atoms at boundaries and triple points. The interaction of these two processes have been studied in Al Mg-Mn based systems with and without additions of Sn, an equilibrium segregant. Fine-grained structures have been produced and samples tested under conditions that induce grain boundary sliding (GBS). The presence of Sn on the boundaries before deformation allows easier GBS
Abstract not available. 4:30 pm MICROCHEMISTRY OF INTERNAL INTERFACES DURING IRRADIATION: E.P. Simonen, S.M. Bruemmer, Pacific Northwest National Laboratory, P.O. Box 999, MS P8-15, Richland, WA 99352 Nonequilibrium microchemistries develop at irradiated interfaces in alloys.
The driving force for the radiation-induced segregation is the flow of radiation produced defects to internal interfaces. A unique feature of these segregation profiles is the narrow nanometer dimension near grain boundaries. Theoretical predictions and analytical measurements indicate that nonequilibrium composition gradients normal to grain boundaries are in excess of 106 atom fraction/em. Fast arrival rates of radiation-produced point defects create potential influences on grain boundary structure and dynamics. Conventional theories assume that dominant mutual recombination of grain boundary defects prevents their influence on boundaries. In the present paper, the dynamics of defect arrival and annihilation are examined in relation to extreme nonequilibrium conditions at internal interfaces. This work was supported by the Materials Sciences Branch, BES, U.S. Department of Energy, under Contract DE-AC06-76RLO 1830.
SUCCESSFUL UNIVERSITY-INDUSTRY LINKAGES FOR A GLOBAL ECONOMY II Sponsored by: TMSnnternational Activities Committee Program Organizers: Dr. Krishna Rajan, Rensselaer Polytechnic Institute, Materials Engineering Department, MRS-110, Troy, NY 12180-8554; Dr. Arthur Willoughby, Southampton University, Eng. Materials Dept., Hants, Southampton S017 1BJ, UK; Dr. Chris Bickert, North American Rep., Tech Transfers, Aluminum Pechiney, Mamaroneck, NY 10543; Prof. Akio Sasaki, Kyoto University, Dept. of Electronic Sci & Engr, Kyoto 606-01, JAPAN
Monday, PM February 10, 1997
Room: 3400 Location: Orlando Convention Center
Session Chairperson: Dr. Krishna Rajan, Rensselaer Polytechnic Institute, Materials Engineering Department, MRS-110, Troy, NY 12180-8554
2:00pm TITLE TBA: Mr. Jeff Lawrence, Associate Administrator of Legislative Affairs, NASA Headquarters, Suite 9L33, Washington, DC 20546 2:30 pm TAX CREDITSIPUBLIC POLICY: Mr. Ken Kay, Podesta Associates, 100 I G Street, NW, Suite 900E, Washington, DC 20001 Abstract not available. 3:00 pm BREAK 3:15pm SUCCESSFUL MODELS: Prof J. Keith Brimacombe, Director, Centre for Met. Process Engineering, University of British Columbia 309-6350 Stores Road, Vancouver BC V6T lZ4 Abstract not available. 3:45pm STATUS-UNIVERSITY-INDUSTRY COLLABORATIVE RESEARCH IN JAPAN: Professor Shuji Hanada, Institute of Materials Research, Tohoku University, Katahira 2-1-1, Sendai, Japan There are two types of universities in Japan; national universities and private universities. Basically, the former are supported mainly by the government (The ministry of education, culture and science-the Monbusho), while the latter partly by the government. Among them, the national universities are active to collaborative research with industry. In this talk the various systems and their activities concerning the research collaboration between national universities and industry will be addressed. In addition some recent topics will be mentioned briefly. From the early 1980s, new systems of joint research with the private sector, endowed chairs and funded research departments and centers for cooperative research were introduced. Consequently, the exchange of researchers between universities and the private sector industries has become quite active, and the sources of research funds for national universities has become diversified. Currently over three thousand outside researchers participate in research activities at universities and the total
amount of funding from industry has become almost as large as the Monbusho grants-in-aid budget. In the system of the joint research with the private sector, national universities receive researchers and funding from private industry. Then university researchers and private industry researchers combine efforts to do joint research on common projects, to enhance the likelihood of achieving excellent results. Under the commissioned research system, scientific researchers in universities are commissioned by industrial firms, government research institutes, local governments or other outside organizations to carry out research by contract. No researchers from the industrial world join in carrying out the research at the universities. In the commissioned researchers system, national universities accept technicians and researchers currently employed in private industry and other outside agencies. They are given guidance in doing research at the graduate level, which helps them to improve their abilities. Endowed chairs can be established within a faculty or department of a national university. Funded research departments can be established in a research laboratory attached to the university or in an inter-university research institute. The wages of the visiting professors or associate/assistant professors, who are appointed by the universities, and the educational and research expenses of the chairs and departments are paid totally from the endowments from the private sectors. Many national universities have Centers for Cooperative Research. These centers employ professors as part-time directors as well as fulltime associate professors and part-time visiting professors. They are equipped with all purpose research facilities and provide technical consultation and training of technicians and researchers, in addition to their functions of engaging in joint and commissioned research. National universities accept donations from both private organizations and individuals to support scientific research and educational activities. Quite recently, the ministry of international trade and industry (MITI-The tsusansho) has started supporting and funding basic research at universities whose results will bring new industries in future.
SYNTHESIS OF LIGHT-WEIGHT METALLIC MATERIALS II: Session II: Metallic CompOSites II Sponsored by: MSD Synthesis/Processing Committee Program Organizers: C.M. Ward-Close, Structural Materials Center, R50 Building, Defense Research Agency, Farnborough, Hampshire, GU14 6TD, United Kingdom; F.H. Froes, University of Idaho, Institute for Materials and Advanced Processes, Mines Bldg 204, Moscow, 10 83844-3026; D.J. Chell man, Lockheed Aeronautical Systems Co., Lockheed Corporation, Marietta, GA 30063-0150; S. S. Cho, Vice President of Rapidly Solidified Materials Research Center, (RASOM), Chungnam National University, Taedok Science Town, Taejon 305-764 Korea
Monday, PM February 10, 1997
Room: 330F Location: Orlando Convention Center
Session Chairpersons:C.M. Ward-Close, Structural Materials Center, R50 Building, Defense Research Agency, Farnborough, Hampshire, GU14 6TD, United Kingdom; S. S. Cho, Vice President of Rapidly Solidified Materials Research Center, (RASOM), Chungnam National University, Taedok Science Town, Taejon 305-764 Korea
2:00pm PRODUCING METHOD AND MECHANICAL PROPERTIES OFTiB 2 PARTICLE REINFORCED HIGH MODULUS STEEL: Kouji Tanaka, Tadashi Oshima, Takashi Saito, Toyota Central Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi, 480-11, Japan In our effort to develop high modulus steel, titanium diboride (TiB2) has proved to be the best reinforcement because of its high Young's modulus and excellent thermodynamic stability in iron-based alloys. In this paper, mechanical properties of the developed steel and the methods applied to practical parts fabrication are discussed. Conventional PIM techniques, including liquid phase sintering to achieve its full density and reaction sintering using low-cost ferro alloy powders, have been successfully utilised. Tensile strength, fatigue strength, and abrasive wear resistance of the developed steel were investigated in order to evaluate its potential application. These mechanical properties revealed a linear improvement with the increase in TiB2 volume
fraction. The developed steel also provided hot workability required in dieforging process. Trial forged parts demonstrated a possibility of producing high performance automobile parts.
structural observation was performed to investigate the effects of reinforcements and squeeze casting condition including applied pressure and preheating temperature of performs etc on the solidification microstructure of the Mg matrix composites. Mechanical properties such as bending strength and fracture toughness were measured to evaluate properties of the squeeze cast Mg matrix composites. In-situ SEM fracture test was performed to observe the fracture process of the Mg matrix composites.
2:20pm A STUDY ON MANUFACTURING METHOD AND ABRASIVE CHARACTERISTICS OF SUBSIEVE SIZE SiCp REINFORCED Al ALLOY COMPOSITE: S. W. Han, S.w. Kim, Department of Metallurgical Eng, Chonbuk National University, Chonju, 560-756, Korea
3:20pm SYNTHESIS OF MoSi-BASED COMPOSITES: S. Walloe, L. Christodoulou, Department of Materials, Imperial College, London SW7 2BP, UK. P. Goodwin, M. Ward-Close, Structural Materials Centre, Defence Research Agency, Farnborough GUl4 6TD, UK
This study aims to manufacture Al a:Ioy composites reinforced by subside size (3 mm, 5mrn, 10mrn) SiCr with duplex process of squeeze-infiltration (1 st process) and squeeze casting (2nd process) developed in this study, to investigate effects of alloying element and heat exposure on the microstructures and heat and wear resistance of AI-Si-X(Cu, Cr, Ni)-SiCr). In the last process, when the melt is infiltrated into SiCr bed. At the same time, melt is flowed to loser part along the gap between mould and SiCr bed. Then, the melt is filtrated into upper-direction conversely. At infiltrating depth of 3040% into SiCr bed, the vertical lamellar infiltration is appeared heterogeneously due to lack of the melt and increase of viscosity. Although pre-composite fabricated by I st process has excellent distribution of SiCp on matrix, the SiCp wt% is high as applying industrial articles. Being modelled, the precomposite and A I alloy are squeeze casted follow melted, agitated in the caster. Through these processes, SiCp wt% is freely controlled as well as the distribution is increased owing to active plain on SiCp during agitation of the 2nd process. AI-12Si-2Mg-3Cu-SiCp has the least wear loss amount among all the composites manufactured in this study. But, AI-12Si-2Mg-3Ni-SiC p has the lowest relative ratio of wear loss amount (wear loss amount after 350°C, 70hr exposure )-(wear loss amount before 350°C, 70hr exposure )/(wear loss amount before 350°C, 70hr exposure) at high sliding speed. Composites with 15wt%(lOmrn)SiCp increased the wear amount with the increase of sliding speed because of change abrasive wear to adhesive or melting wear. But composite with 35wt%(lOmrn SiCp) decreased wear amount with the increase of the sliding speed because abrasive wear with power debris occur in high sliding speed and wear debris with block type occur in low sliding speed.
A study has been undertaken to investigate process parameters controlling the formation of moist composites using elemental powder-based reaction synthesis techniques. The size and shape of reinforcement have been correlated to the processing conditions and the starting powder characteristics.
4:00pm FABRICATION AND MECHANICAL PROPERTIES OF SQUEEZE CAST MG MATRIX COMPOSITES: Y.S. Choi, K.M. Cho, I.-M. Park, Dept of Metal Eng, Pusan Nat Univ. Pusan, South, Korea In the present study, AZ91 Mg matrix composites were fabricated with a variation of the applied pressure using squeeze infiltration technique. Alumna short fibre (Saffil and Kaowool) and aluminium borate whisker were chosen as reinforcements. Performs of reinforcements from the slurries with different binder compositions were consolidated by vacuum suction method. Microstructural observation was performed to investigate the effects of reinforcements and squeeze casting condition including applied pressure and preheating temperature of performs etc on the solidification microstructure of the Mg matrix composites. Mechanical properties such as bending strength and fracture toughness were measured to evaluate properties of the squeeze cast Mg matrix composites. In-situ SEM fracture test was performed to observe the fracture process of the Mg matrix composites.
2:40pm 4:20pm
A STUDY ON THE DEVELOPMENT OF IDGH STRENGTH AND WEAR RESISTANCE INTERMETALLIC COMPOUNDS/ALUMINIUM ALLOY MATRIX COMPOSITES BY SQUEEZE CASTING METHOD: D.C. Choi, S.H. Park, C.w. Won, National University, Chungmann Nation University
PHASE FORMATION AND PROPERTIES OF MECHANICALLY ALLOYED Mg-BASED MULTI COMPONENT LIGHTWEIGHT ALLOYS: J Eckert, N. Schlorke, C.A.R.T. Miranda1, and L. Schultz, Institute fur Festkorper-und Werkstofforschung Dresden, Institute fur Metallische Werkstoffe, D-01171 Dresden, Germany; IPermanentAddress: LU6-Barcelos, Portugal
Recently, particle reinforced A 1 alloy matrix composites accomplished weight reduction by utilising Al alloy matrix and improved wear resistance, heat resistance and mechanical properties. This technique is believed to have advantages compared to the conventional manufacturing process, in that the intermetallic compounds enforcers as well as density and shape of the perform are more easily controlled. In this study, perform composition of25, 40, 50,60 and 75at%AI were manufactured. The perform swelled after the reactive sintering process in the case of25at%AI composition. On the other hand, the perform shrinkage in the case of 6Oat%AI and 75at%Al composition. Microstructures of the composite samples squeeze casted at the mould temperature of 500°C and the Al alloy melt of 610°C were investigated using Xray diffractometer, energy dispersive spectrometer, micro-vickers hardness and etching experiments. In the case of Fe-25at%AI and 40at%AI composites, mixture of the compound and the Al alloy matrix were observed at the top part of the ingot, whereas small amount of Al alloy matrix were dispersed within the compound islands at the bottom part. Composite structure were observed throughout the whole sample in the case of 50at%Al, which is the structure initially intended to obtain.
Multicomponent Mg-Y-Cu lightweight alloys were prepared by mechanical alloying of elemental powder mixtures. The progress of alloying, the resulting phases and their thermal stability were characterised by x-ray diffraction, differential scanning calorimetry (DSC) and thermo-mechanical analysis (TMA). Coexistent amorphous and nanoscale crystalline phases are found for a variety of alloys with different composition. The thermal stability data of the materials as obtained by constant-rate heating DSC and TMA measurements and isothermal annealing experiments are discussed with respect to phase separation in the undercooled liquid state and nucleation and growth of nanocrystalline phases. Some characteristic properties of the glassy phase are presented and discussed with respect to the composition dependence of the glass transition and the crystalline temperature. The results are compared with data for melt-quenched samples. Finally, the influence of processing conditions and contamination effects during milling on the phase formation and the thermal stability of the mechanically attrited powders is critically assessed.
4:40pm 3:00pm FABRICATION AND MECHANICAL PROPERTIES OF SQUEEZE CAST Mg MATRIX COMPOSITES: Yoon-suck Choi, Kyung-mox Cho, lk-min Park, Dept of Metal Eng Pusan Nat Univ. Pusan, Korea
IRON AND ALUMINIUM MICROINANOLAMINATES PROCESSED BY HIGH RATE DEPOSITION: C. Loader, D. Dunford, Z. Kulikowski, C.M. Ward-Close, Structural Materials Centre, Defence Research Agency, Farnborough GU14 6TD, UK
In the present study, AZ91 Mg matrix composites were fabricated with a variation of the applied pressure using squeeze infiltration technique. Alumna short fibre (Saffil and Kaowool) and aluminium borate whisker were chosen as reinforcements. Performs of reinforcements from the slurries with different binder compositions were consolidated by vacuum suction method. Micro-
A model iron-aluminium system was employed to understand the toughness characteristics observed in multi-layered materials. The process for fabricating laminates by physical vapour deposition using either thermal or electron beam evaporation is described. Laminates are deposited onto a rotating collector and are typically around 2 - 4mm thick. In this work a range of lami
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nates were fabricated with layer thickness varying from 10nm to 5mm. Microstructural evaluation of the laminates was performed using SEM, XRD, EPMA and TEM; mechanical property data was generated using tensiles, four-point bend, notched bend and microhardness. Results show strength and toughness increases are obtained in multi layered materials compared to monolithics primarily due to crack deflection and blunting. The effect of changing layer thickness on the strength and toughness is reported.
FE/A 1 laminates of different layer thicknesses were produced by PVD. TEM studies showed that as deposited microstructure depends on the ratio of the nominal thicknesses of the FE and Al layers and on the actual layer thickness. For d f,:d,,=O.4mm the microstructure consisted of nanocrystals of Fe/ Al solid solution with A2 or B2 structure and AI3Fe. For df,:dA ,,,44nm or 2.lmm:0.7mm laminated structures were produced. The laminates consisted of layers of Fe(A2-bcc) and of solid solution of Fe in Al with B2 (ordered bcc) structure which was formed by interdiffusion between the Fe and Al layers. Thermodynamic modelling showed that interdiffusion and interface reaction in the as deposited materials are closely related to the overall heat of mixing. The mechanical properties of the laminates will be related to their microstructures.
5:00pm MICROSTRUCTURE-PROPERTY STUDIES IN Fe-AI LAMINATE MATERIALS: G. Shao, P. Tsakiropoulos, C. Loader, D. Dunford+ and M.C. Ward-Close+ *Department of Materials Science and Engineering, Uni versity of Surrey, Guildford, Surrey GU2 5XH, England, UK +Structural Materials Centre, DRA Farnborough, Hants GU14 6TD, England, UK
ADVANCES IN COATINGS TECHNOLOGIES II: Session III
low pressure plasma spray (LPPS) bond coat. These TBCs have allowed the components to be operated at high gas path temperatures to meet thrust, efficient and life requirements of Pratt and Whitney's gas turbine engines. Details of Pratt and Whitney'S experience on various aspects of TBCs will be discussed.
Sponsored by: MDMD Surface Modification & Coatings Technology Committee Program Organizers: C.R. Clayton, State University of New York at Stonybrook, College of Engineering and Applied Sciences, Stony Brook, NY 11794-2200; J.K. Hirvonen, US Army Materials Technology Lab., Arsenal St., Watertown, MA 02172; A.R. Srivatsa
ANALYSIS OF THERMAL SPRAY METHOD FOR COATING NANOSCALE MATERIALS: Schmuel Eidelman, Xiaolong Yang, Science Applications International Corporation, 1710 Goodridge Drive, McLean, VA
Tuesday, AM February 11, 1997
9:10am
Thermal Spray (TS) system allows delivery of the plating materials to the substrates at high velocities (on the order of I to 1.5 km/sec) and high temperatures. The total pressure of the particle impinging on the surface can reach 10 Gpa for some of the TS systems. Lower sintering temperatures and higher ductility of nanoscale materials open a range of attractive and unique possibilities for high rate deposition of nanostructured coatings. We use a recently developed and validated three dimensional simulation capability to model the TS systems' gas and coating powder flow for the TS process analysis, to illustrate the roots of currently used TS systems' inefficiencies, and to optimize and control the coating process. Examples are given for the TS process designs with improved performance and system efficiency. The use of numerical simulation will be especially crucial for the plating with nanoscale powders.
Room: 315B Location: Orlando Convention Center
Session Chairperson: TBA
8:00am PULSED LASER DEPOSITION OF ELECTRONIC CERAMIC THIN FILMS: D.B. Chrisey, J.S. Horwitz, P.C. Dorsey, L.A. Knauss, R.C.Y. Auyeung, U.S. Naval Research Laboratory, Washington, D.C., 20375-5345 Pulsed laser deposition (PLD) is a unique physical vapor deposition technique that is making available high quality thin films of complex, multicomponent materials for the design and fabrication of advanced electronic devices and protective coatings. Single phase and epitaxial thin films can be deposited in situ. by PLD. Recent applications of PLD include high temperature superconductors, ferroelectrics, magnetoresistive materials and ferrites. Ferroelectric thin films grown by PLD are currently being developed into low loss, frequency agile microwave electronics which exploit the electric field dependence of the dielectric constant. More recently, colossal magnetoresistance with DRH / RH"", - 100,000% has been observed in thin films of rare earth manganites deposited by PLD. These materials have applications in magnetic field sensing and recording as well as electrodes in solid oxide fuel cells and room temperature microbolometers. This presentation will show recent examples applying PLD to high quality electronics ceramic thin films growth for next generation devices.
9:30am ROLE OF INTERDIFFUSION AND HEAT TREATMENTS ON THE ADHESION OF PLASMA SPRAYED NiCrAIY COATINGS: C.S. Richard, G. Beranger, Universite de Technologie de Compiegne, Department de Genie Mecanique, URA 1505 du CNRS, 60206 Compiegne Cedex, France; J. Lu, Universite de Technologie de Troyes, Department de Genie des Systemes Mecaniques, 10000 Troyes, France During service blades and vanes of stationary gas turbines are subject to different kinds of loadings like mechanical and thermal stresses as well as corrosion, oxidation and erosion. Against these phenomena, plasma spraying coatings are frequently used to protect the componenets in the hot parts of these engines. The layers are commonly deposited by Atmospheric Plasma Spraying (APS) and by Vacuum Plasma Spraying (VPS). One of the main parameters in quality of a coating is its adhesion on aNi-based superalloy substrate. This study focused on a NiCrAIY metallic bonding layer and its adhesion on aNi-based supralloy substrate. It looks at the influence of different spraying methods (APS and VPS) and the influence of a post heat treatment on the adhesion of the coatings. In order to determine the interface toughness, a Vickers interfacial indentation test, based on fracture mechanics method, was performed. In APS and VPS cases, the residual stresses were evaluated by a step-by-step drilling method and these were taken into account in the adhesion parameters. The results were supplemented by a microstructural study of the interface in order to understand the role of interdiffusion on adhesion.
8:35 am THERMAL BARRIER COATINGS FOR AIRCRAFT ENGINES - A PRATT AND WHITNEY PERSPECTIVE: S. Bose, Pratt and Whitney, 400 Main Street, East Hartford, CT 06108 The gas temperatures in the turbine section of Aircraft Gas Turbine Engines are hundreds of degrees higher than the melting point of the materials of construction. Exposure to such high temperatures would result in structural failure of the materials from a variety of mechanisms. Yet, in modem engines, the components, generally made a nickel and cobalt based superalloys, survive for extended periods of time. This is accomplished by devising efficient air cooling of the components and by applying Thermal Barrier Coatings (TBCs) to the substrate alloy to reduce metal temperatures to safer levels. Combustor TBCs are processed with air plasma spray (APS) ceramic on APS metallic bond coat. Vanes, exposed to higher temperature and thermal load, require electron beam physical vapor deposition (EB-PVD) ceramic on
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9:50am PLASMA SPRAYED ZIRCONIA BASED COATINGS FOR USE AS AN INSULATING LAYER IN DIE CASTING: M. Giannis, CAST, CSIRO Division Manufacturing Technology, Melbourne, Victoria, Australia
commercial electroplating processes, the chromium is deposited from elec· trolytes in which it is in the hexavalent state. With recent interest in seekir.g alternatives to the toxic Cr"+, a process has been developed to deposit thJ(k chromium coatings from a non-toxic trivalent electrolyte. The coatings deposited from this electrolyte are an alloy of chromium-carbon-oxygen-hydrogen having an amorphous structure, as-deposited. However, with heat tre&tment they are transformed to a crystalline structure of chromium carbide in a chromium matrix. The hardness and resistance to wear increase with the transformation of this coating after heat treatment. The structure of the electrodeposited coatings, will be discussed. Property measurements of microhardness, wear and coefficient of thermal expansion will be discussed for the as-deposited and heat treated coatings.
The casting of light alloys, such as aluminum, requires insulation in the form of a ceramic-based coating applied on the metallic die. This assists in the production of sound castings in gravity and low pressure die casting processes by preventing premature solidification. The currently used coatings are based on ceramic particles and sodium silicate binder slurry applied by spray-gun to the preheated substrate. These coatings were found to be fragile due to the highly porous network of binder an particles. Plasma spraying of ceramic zirconia-based particles was studied for possible use as a die coating. The coatings studied were characterized in terms of composition and microstructure. In addition, thermal properties were determined using experimental and simulation techniques to estimate the heat transfer coefficient at the die coating/casting interface. Zircona-based plasma sprayed coatings had high wear resistance and good heat transfer resistance and would therefore function as an improved die coating.
11:35 am COPING WITH UNINTENDED Cu ENRICHMENT DURING CONVERSION COATING OF MICROSTRUCTURALLY COMPLEXALUMINUM: R.G. Buchheit, Sandia National Laboratories, Albuquerque, NM 87185 Copper is a major alloying element in engineering aluminum alloys. Cu is concentrated in second phase particles distributed throughout the alloy. The interaction of these particles with conversion coating solutions can result in enrichment of Cu on the treated surface. This enrichment has serious negative consequences on subsequent corrosion and adhesion properties. Direct examination using high resolution SEM shows that in 2024-T# Cu is segregated into large (2-6 micrometer) Al2CuMg particles. During surface finishing these particles experience severe dealloying and produce a fine dispersion of Cu-rich clusters that are distributed across the alloy surface facilitating galavanic corrosion during testing or service. Since redistribution of Cu across the surface is possible without ever oxidizing the Cu, mitigation schemes based on Cu complexing agent additions alone may be inadequate. However, mitigation schemes that utilize a Cu complexing agent and a sufficiently oxidizing solution can successfully prevent Cu enrichment and produce significant improvements in corrosion resistance.
10:10 am COATING PHASES OF COMMERCIAL GALVANNEALED COATINGS: Carlos Nelson Elias, Universidade Federal Pluminense, Av. Dos Trabalhadores 420, Vila Santa Cecilia 27260-740 Volta Redonda, RJ-BRAZIL, Jorge Alcala Vera, Institutio Militar de Engenharia, Pr General Tiburcio 80,22290270 Rio de Janeiro, RJ Hot-dip galvannealed steel sheet has been increasingly used in the automotive industry and more recently it has been found that a zinc-iron alloy steel sheet, such as galvannealed would provide even better results. The galvannealed steel sheet is a product with good corrosion resistance, weldability and paintability. Therefore it has been used in the automotive and appliance industries. The properties of galvannealed steel are strongly influenced by the iron content of the coating, especially galling, corrosion resistance, welding and powdering. The galvannealed steel is predominately composed of delta phase. When the soft zeta phase is present in the surface of the coating, it adheres to the die and reduces the performance of steel sheet during deformation. When the hard and brittle gamma phase is at the interface steel-coating, the galvannealed coating fails by powdering. In this work we discuss the formation of Fe-Zn intermetallic compounds in the industrial galvannealed coating.
ADVANCES IN SYNTHESIS AND PROCESSING OF METAL CERAMIC MATRIX COMPOSITES I: Sponsored by : MSD Materials, Synthesis & Processing Committee and Jt. SMD/MSD Composite Materials Committee Program Organizers: l.l. Shaw, Dept. of Metallurgy and Materials Engineering, University of Connecticut, Storrs, CT 06269; E.J. Lavernia, Dept. of Mechanical and Aerospace Engineering, University of California - Irvine, Irvine, CA 92717; S. Krishnamurthy, UES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432-1894; E.S. Chen, U.S. Army Research Office, 4300 S. Miami Blvd., Research Triangle Park, NC 27709
10:30 am BREAK 10:40 am RECENT TRENDS IN ELECTROPLATING: Brian Am Manty, Concurrent Technologies Corporation, Johnstown, PA This paper reports on recent trends and advances in electroplating as a surface finishing technology. It includes a description of environment and worker exposure regulations that have affected the industry. New developments in water and chemical recycling equipment and techniques have substantially reduced the amount of wastes generated during electroplating. Near-zero discharges are now technically and economically feasible for many electroplating shops. Several guidance documents are available to help electroplaters reduce wastes with simple, inexpensive techniques. Alternative electroplating processes and materials are also being developed for processes requiring the use of toxic materials. On-going programs within industry and the government are aimed at reducing the use of cadmium, chromium (hexavalent), lead and cyanide. There is a substantial increase in commercial formulations for alloy electrodeposits, especially where those alloys may be used as a substitute for more toxic coatings.
Tuesday, AM February 11, 1997
Session Chairpersons: Prof. Leon l. Shaw, Dept. of Metallurgy and Materials Engineering, University of Connecticut, Storrs, CT 06269; Prof. Carl C. Koch, Dept. of Materials Science and Engineering, North Carolina State University, Raleigh. NC 27695
8:30 am INVITED PROCESSING OF CONTINUOUSLY REINFORCED Ti-ALI.OY MMCS BY PHYSICAL VAPOR DEPOSITION: P. R. Subramanian, S. Krishnamurthy, and S. Keller, UES, Inc., Materials and Processes Division, 4401 Dayton-Xenia Rd., Dayton, OH 45432-1894
11:05 am STRUCTURE AND PROPERTIES OF FUNCTIONALLY THICK CHROMIUM ELECTRODEPOSITS FROM A TRIVALENT ELECTROLYTE - A " GREEN" TECHNOLOGY: Christian E. Johnson, Jasper L. Mullen National Institute of Standards and Technology, Gaithersburg MD20899
Fiber-reinforced titanium aluminide composites are of particular interest as candidate materials for aerospace structural applications at moderately high temperatures. Conventional techniques for fabrication of these composites pose many technical challenges, and serve as one of the barriers to the practical use of these composite systems. The present work deals with a novel vapor synthesis route, the matrix-coated fiber process, for producing Ti-alloy metal matrix composites (MMCs). In this process, the matrix alloy is directly deposited on continuous SiC fibers by hollow-cathode magnetron sputtering.
Chromium is widely used as an electrochemically applied coating on metal for wear resistance, to reduce friction, or for a desired appearance. In present
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Room: 340B Location: Orlando Convention Center
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The matrix-coated fibers are then consolidated to produce unidirectionally reinforced MMC panels. Details of the processing technique will be presented, along with results on microstructural evolution. Results from room-temperature mechanical evaluation of the MMC specimens will also be presented. This research is funded by the U.S. Air Force as a Small Business Innovative Research Program under Contract No. F33615-94-C-5214. Program Monitor: Dr. Stephen W. Schwenker, USAF Wright Laboratory, Materials Directorate (WLIMLLM), Wright-PattersonAFB, OH 45433-7817.
tion and the size distribution of the dispersoids is critical to the grain refinement mechanisms. The primary goal of the present work is to define a model to estimate these characteristics. The materials considered are aluminum alloys while target dispersoids are primarily oxides. These may be obtained by the reaction of oxygen containing atomization gas mixtures with molten alloy droplets or with minor alloy additives which exhibit a high affinity for oxygen. Droplet position and velocity histories are obtained from the numerical solution of the one-dimensional equation of motion. The energy equation inside the droplet is solved numerically using finite-differences to predict the spatially resolved temperature field. The solid/liquid interface progression rate is estimated using a power law. The effect of the dispersiods on the achievable undercooling is included. This model is then used to determine the parameters controlling the volume fraction and the size distribution of the dispersiods.
9:00am COMBUSTION CHEMICAL VAPOR DEPOSITION (CCVD) OF LaP04 MONAZITE ON ALUMINA FIBERS FOR CERAMIC MATRIX COMPOSITES: T.1. Hwang, M.R. Hendrick, H. Shao, H.G. Hornis, A.T. Hunt, Micro Coating Technologies, 430 Tenth Street, Suite N-108, Atlanta, GA30318
10:15 am BREAK It has been demonstrated that monazite compounds can serve as an oxidation protection and crack deflecting interface coatings to improve the strength and toughness in oxide-oxide ceramic matrix composite. In this study, lanthanum phosphate LaPO. (monatize) was coated on alumina fibers (Nextel 610) using the combustion chemical vapor deposition (CCVDSM) method in the open atmosphere. This study has shown that the CCVD is feasible for applying a dense LaPO. coating while moving the fiber tows through the deposition zone. A systematic stoichiometry study showed that monazite was the predominate phase in the film. Deposition temperatures were controlled to prevent degradation of fibers while maintaining an optimal deposition rate and coating quality. Several interlayer materials were investigated to minimize the reaction and recrystallization of the A1,03 fibers. Since a vacuum chamber is not required for the CCVD process, large scale, continuous coating of fibers is possible.
10:25 am INVITED PLASMA SPRAYED MULTI-LAYERED AND FUNCTIONALLY GRADED MATERIALS: H. Herman, Department of Materials Science and Engineering, State University of New York, Stony Brook, NY 11794 Multi-layered (MLM) and functionally graded (FGM) composites display discrete or continuously varying compositions of metals, ceramics and polymers and/or microstructures over definable geometrical orientations and distances. Plasma spray offers a flexible and economic means for producing non-uniform composites and is used to apply layered and graded deposits to enhance the survivability of thick ceramic coatings (e.g., TBCs). These "graded coatings" are primarily applied to reduce CTE mismatch-related failure. The versatility of plasma spray allows the processing of a wide range of high performance materials, including most metals and refractory ceramics, under a controlled atmosphere if desired. Using plasma spray, it is possible to deposit multiple constituents simultaneously, thus providing a unique means of producing FGMs. Plasma spray MLM/FGM production will be discussed and the characteristics and properties of two FGM systems, Ni-AlP3 and NiCrAIY - zrO" will be presented. This research is supported by NIST-Caterpillar Advanced Technology Program and the INEL University Research Consortium.
9:25am DENSE TITANIUM MATRIX COMPOSITE MONOTAPE FROM EBEAM METAL COATED FIBERS: Herve Deve, Metal Matrix Composites Program, 3M Center, Bldg 60-IN-01, St Paul, MN 55144-1000 The high temperature specific strength and stiffness of titanium matrix composites (TMC's) make them very attractive for the next generation of jet engine components. Significant efforts are now underway at 3M to reduce the cost of TMC's; bring them to a production status; and offer the customer a TMC precursor that will be easy to integrate into titanium components. The recent advances in the production of metal coated fibers by electron beam evaporation have allowed the development of continuous dense monotape. Dense TMC monotape will facilitate the fabrication of complex curved parts such as rings. A dense monotape is a single composite ply made by rollbonding cylindrical metal coated fibers. Continuous roll-bonding allows the low-cost fabrication of TMC tape that do not contain organic binders. Monotapes have been produced that are typically 200 =B5m thick by 10 mm wide and greater than 30 meter long. The flexible composite tape can be easily laid-up on flat or curved parts. Final bonding of the component requires a HIP or diffusion bonding cycle without the complex removal of organic binders. TMC rings with a nearly perfect fiber distribution were fabricated to illustrate the simplicity of use of TMC monotapes.
10:55 am SPRAY FORMING OF TiB, REINFORCED GAMMA TITANIUM ALUMINIDE ALLOYS: B. Li, E.J. Lavernia, Department of Chemical Engineering and Materials Science, University of California at Irvine, Irvine, CA 92697-2575 Gamma titanium aluminide composite with a nominal composition of Ti47Al-2Nb-2Mn + 0.08 wt.% Till, was spray formed using a skull melting technique. Microstructure characteristics of as-received and spray formed Ti47 AI-2Nb-2Mn + 0.08 wt.% TiB" along with the oversprayed powders, were examined by optical microscope and SEM, and rationalized on the basis of numerical analysis. 11:20 am INVITED SOL-GEL SYNTHESIS OF CERAMIC MATRIX COMPOSITES: E.D. Rodeghiero, E.P. Giannelis, Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853
9:50am REACTIVE SPRAY ATOMIZATION AND DEPOSITION OF ALUMINUM ALLOYS: MODELING DISPERSOID VOLUME FRACTION AND SIZE DISTRIBUTION: J.-P. Delplanque, E.1. Lavernia, R.H. Rangel, Department of Mechanical and Aerospace Engineering, Department of Chemical and Biochemical Engineering and Materials Science, University of California, Irvine, California 92697-2575
Sol-gel techniques provided new and powerful means by which to synthesize oxide-based ceramic matrix composites. The advantages of sol-gel approaches relative to conventional powder processing are numerous. First, sol-gel synthesis can achieve extremely fine (nanoscale) microstructures with high degrees of dispersion between the matrix and reinforcement phases. In addition, the chemical compositions of the various phases can be precisely controlled. Furthermore, gel-derived composites are also highly uniform, as a result of eliminating powder mixing and segregation problems. Finally, solgel synthesis can reduce consolidation temperatures significantly, leading to more efficient, economical processing. This talk will present the results of our work in synthesizing both Ni/a-Al,03 metal-ceramic composites and SiC(whisker)/a-AIP3 ceramic-ceramic composites. The unique physical and mechanical properties of these composites in their various forms will be discussed, as well as their potential applications.
Reactive spray atomization and deposition combines atomization, chemical reaction and consolidation into a single step. It offers a unique opportunity for in-situ, continuous control over alloy composition and chemical reaction between atomized droplets and reactive atomization gas. During reactive spray deposition a molten alloy is atomized by using a reactive gas mixture. The atomized droplets are subsequently deposited on a substrate. Chemical reactions occur between the matrix material and the reactive gas during both atomization and deposition. By carefully selecting alloying additive and reactive gas combinations on the basis of containing in-situ dispersoids such as carbides, nitrides, and oxides, leading to grain refinement. The volume frac-
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9:20am MONITORING OF HEAT EXCHANGER PERFORMANCE THROUGH THE SCALING FACTOR: Eugenio C. G. Azevedo Jr., Carlos Eduardo A. Batista, Alumar-Cons6rcio de Alumfnio, BR 135 - Km 18, Distrito Industrial de Pedrinhas CEP 65095.050 - Slio LuisIMA - Brasil
11:50 am NANOCOMPOSITE MATERIALS VIA CHEMICAL ROUTES: Kenneth E. Gonsalves, X. Chen, Department of Chemistry & Institute of Materials Science, University of Connecticut, Storrs, CT 06269 The formation of an AINlPolyimide (PI) nanocomposite was achieved by the rapid solidification of the precursor suspension, followed by compression molding. Such an approach for nanocomposites exhibits improved homogeneity with ultrafine fillers and allows a tailorable composition and property at the nanoscale level. AINIPI nanocomposites with an increased ceramic loading up to 50% by volume were attained and their thermal and mechanical properties, along with the compositional effects, were investigated.
The ALUMAR Refinery was designed to maximize heat recovery, and therefore minimize process steam requirements. Since the increase of alumina production from 0.5 to 1.2 million tons per year, the heat exchangers became a strategic point in the refinery performance. An objective has been to create a tool to improve the performance of the heaters. A continuous method of monitoring individual heaters was developed of calculating the scaling factor using the principles of the heat transfer theory. This paper describes the method and the steps to achieve a significant improvement in the identification and troubleshooting of heat transfer related problems. This method also proved to have a positive effect on the operation and maintenance planning of the heat exchangers in the refining.
ALUMINA &BAUXITE TECHNOLOGY I Sponsored by: LMD Aluminum Committee Program Organizer: F. S. Williams, Alcoa Alumina & Chemicals L.L.C., Point Comfort, TX 77978-0101
Tuesday, AM February 11, 1997
9:45am THE PRECIPITATION MECHANISM OF SODIUM ALUMINOSILICATE SCALE IN BAYER PLANTS: J. Addai-Mensah, A.R. Gerson, K. Zheng, A. 0' dea, R. St. C. Smart, Ian Wark Research Institute, University of South Australia, The Levels, Adelaide, 5095, Australia
Room: 230D Location: Orlando Convention Center
Session Chairman: Jean Doucet, Alcan International Limited, 1188 Sherbrooke Street West, Montreal, Quebec, Canada H3A 3G2
During the dissolution of bauxite ores by caustic soda, a serious and unwanted downstream precipitation of sodium aluminosilicate may occur in heat exchangers, due to the presence of silica impurity dissolved in the Bayer liquor. To date, the mechanism of nucleation and growth of scale occurring on heat transfer surfaces is not fully known. This paper presents the results from studies carried out to investigate the mechanism of formation of sodium aluminosilicate scale on metallic surfaces under conditions close to those in alumina refineries. It is shown that the scale formation may involve two aluminosilicate dimorphs: sodalite and cancrinite. The extent of solution desilication and scale growth was observed to be strongly temperature and carbonate impurity concentration dependent.
8:30am REDUCTION OF THE MOISTURE CONTENT IN MRN BAUXITE, BY TREATMENT WITH DEWATERING AID: Carlos Estevam da Silva, Marcos Fernando Dias Moreira, Mineraclio Rio do Norte S.A. , Porto Trombetas, PA 68275-000 Brazil; Luis Gustavo Esteves Pereira, Mauro Pinto dos Reis, Nalco Brasil Ltda, Av. das Nacoes Unidas, 17891 - 110. Andar, Sao Paulo, - SP - 04795-100 - Brazil MRN must sell their bauxite at a maximum of 12% moisture content to avoid paying a penalty. To meet this target it is necessary to mix dried and wet bauxite; however, that mixing is very costly because of the high drying cost. Thus MRN and NALCO BRASH have worked together to develop a chemical program to reduce the moisture content of wet bauxite. A large number of dewatering aid products were tested on a lab scale. Two products were selected and tried in pilot plant scale. Finally the product 95DWI21 was selected and tried on an industrial scale. The industrial trial was run for three months in the fine and superfine plants with the results that the bauxite moisture was reduced around three percentage points with a dosage rate of 80 glt.
10:10 am BREAK 10:30 am ASPECT OF DEEP DESILICATION WITH LIME AGENT: Qingwei Wang, Gengyou Tian Zhengzhou, Light Metals Research Institute, Shangjie District, Zhengzhou City, Henan, 450041, China; Chongyu Yang, Central South University of Technology, Changsha City, Hunan, 410083, China The formation of hydrogamet (CAS) with low solubility is the essence of desilication of the sodium aluminate solutions with lime addition. The mechanisms of formation ofhydrogamet were studied. It is indicated that desilication with formation CAS is in a form of SCM-type model, i.e. the unreacted core model for spherical particles of unchanging size. The reaction is controlled by diffusion through outer layer. A mathematical model of the kinetics of the process has been developed.
8:55am BQUANT: COST-EFFECTIVE CALCULATIONS OF BAUXITE MINERALOGY: Frank M. Kimmerle, Frank Feret, Alcan International Ltd., Arvida Research and Development Centre, P.O. Box 1250, Jonquiere, QC, G7S-4K8; Barbara Feret, BF Simulation, 3099 St. Patrick St., Jonquiere
10:55 am A STUDY OF DESILICATION OF ALUMINATE SOLUTION WITH HCAC: Peng Zhihong, Li Xiaobin, Department of Metallurgy, Central South University of Technology, Changsha, Hunan, 410083, China
Routine elemental analysis of the major and minor oxides in alumina-bearing minerals, using modern XRF instrumentation yields better than 0.1 % reproducibility at a rate exceeding 100 samples per day. However, the mineralogy required to evaluate the amount of recoverable alumina or other Bayer plant parameters has been far less readily accessible. Empirical fits between elemental composition and simulated plant digests are limited to narrow composition ranges in particular geological deposits. Interpretation of X-ray diffractograms is notoriously slow, influenced by crystallite size, amorphous phases, and preferred orientation effects. Instead, using non-linear programming, the BQUANT software provides quantitative phase analysis based on an elemental mass balance. It can even deal with overburden, clay bottoms and is independent of the exact nature of the geological deposit. Given its rapidity, it is particularly useful for estimating the potential of new deposits. Given its accuracy, it greatly facilitates mine exploitation control.
Because the sintering process is very important in the Chinese alumina industry, it is important to understand and improve on desilication of aluminate solutions from the sintering process. This paper presents a thorough study on a new method of desilication utilizing HCAC (4CaOoAlp30mCO,omH,O) both in theory and practice. The reaction thermodynamics and kinetics study reveal the reaction laws during synthesis of HCAC and desilication with HCAC. All levels of tests and applications indicate that the desilication effect of HCAC is superior to lime. It can achieve lower silica concentrations in the purified solution under the same amount of lime addition. At the same target silica concentration it can decrease the amount of lime addition about 44% and reduce the loss of alumina about 30%. The new method has achieved satisfactory results in the plant after replacing the old method of desilication with lime in Shangdong Aluminium Corporation. It sets a new path for sintering processes in China by improving alumina product quality, decreasing energy consumption, and raising the target of technology and economy.
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atic surveillance and interpretation of all pot parameters and has a major contribution to the highly improved pot performance.
ALUMINIUM REDUCTION TECHNOLOGY III: Smelter Technology
9:45 am DEVELOPMENT OF A 200 kA REDUCTION CELL TECHNOLOGY CD200: Geoff Bearne, Mark Dunn, Comalco Research Centre, P.O. Box 316, Thomastown 3074 Australia; Mike Roberts, Yousef Ali Mohamed, Dubai Aluminium Co. Ltd., P.O. Box 3627, Dubai, United Arab Emirates
Sponsored by: LMD Aluminum Committee Program Organizer: Harald A. 0ye, Institute of Inorganic Chemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway Tuesday,AM February 11, 1997
Room: 230A Location: Orlando Convention Center
In 1990, Comalco and Dubai Aluminium Co. Ltd. (Dubai) joined forces to develop a modern high amperage reduction cell design known as the CD200. This technology was aimed at the 190 to 200 leA operating range. It was designed to be compatible with future expansion plans at Dubai as well as at the Comalco managed New Zealand Aluminium Smelters Ltd. (NZAS) plant, while remaining within the scope of the present anode design. The cell incorporated a cathode lining design and alumina feeding technology which had been successfully demonstrated at NZAS. The bus bar system was developed using computer modelling at the Comalco Research Centre (CRC). Dubai provided the financial investment and operational experience as well as improvements in process control strategies. Five cells were installed in Dubai's potline 4 and these have operated since 1991. During the last five years, there have been changes to the bus bar design and cathode lining, introduction of larger anodes and further enhancements of the process control systems and operating practices. As a result, the operational performance and the power efficiency of the prototype cells have met or exceeded all targets. Subsequently, the technology has been selected for expansions at both NZAS and Dubai. NZAS has installed 48 cells to be operated at 190 leA, with commissioning from mid 1996. 2 is installing 240 cells to be operated at 195 kA, with start up scheduled in September 1996.
Session Chairperson: Jerry Johnson, Alumax Inc., Intalco Plant, P.O. Box 937, Ferndale, WA 98248
8:30am COMMISSIONING OF ALUSAFHILLSIDE SMELTER REDUCTION POTS: lean-PauIAussel, Jean-Claude Frison, Aluminium Pechiney, Licensing Department, BP 7, FR-38340 Voreppe, France; Shaun Kroutz, Gideon Stander, Alusaf Hillside Smelter, P.O. Box 897, RSA 3900 Richards Bay, Republic of South Africa From the 18th of June 1995 to the 21st of June 1996, AlusafHillside Smelter started the 576 AP30 reduction pots of its two potlines. The promising results achieved by the first stabilized pots allowed the Process management team to finely tune the potlines around 310 leA and to achieve current efficiency in excess of 95.5% and energy consumption very close to 13000 kWhlt during the first half of 1996. The results of these first 6 months of operation of the first full potline are discussed. It includes data on the raw materials, the organisation and the training programs of the Reduction Department which were all instrumental in engineering this success. The evolution of the Reduction Process parameters and results described in the paper will be updated for the final presentation with the available data of both potlines.
10:10 am BREAK 10:30 am AN ANALYSIS OF THE ELECTRICAL PREHEAT TECHNIQUE BASED ON THE START·UPOFTHE CD200 PROTOTYPES AT DUBAI ALUMINUM CO. LTD: Mark R. Dunn, Comalco Research Centre, P.O. Box 316, Thomastown 3074 Australia; Q.M.1. Galadari, Dubai Aluminum Co. Ltd., P.O. Box 3627, Dubai, United Arab Emirates
8:55am FROM 110 TO 175 kA: RETROFIT OF YAW RHEINWERK. PART I: MODERNIZATION CONCEPT: D. Vogelsang, I. Eick, M. Segatz, Ch. Droste, YAW Aluminium-Technologie, G.-v.-Boeselager-Str. 25, D-53117 Bonn, Germany
In 1991 the Dubai Aluminum Co. Ltd. And Comalco Research & Technology set up a joint project to develop a 200 kA cell in a facility attached to the end of Dubai 's potline 4 (then under construction). One aspect of this project was the development and assessment of a suitable electrical preheat practice, based on Dubai's current methods. This paper reports on the process used and the extensive monitoring that took place during the preheats. The effect of current distribution control was also quantified in terms of cathode temperature variation.
Modernization of the 210,000 tpy YAW Rheinwerk smelter includes installation of point feeder, alumina conveying system, state-of-the-art pot control system and forsees an increase in amperage of up to 175 leA. For the modernized pots, concepts for the potlining as well as for improvements of the busbar system were developed, based solely on computer simulations. For the layout of the potlining a new three-dimensional thermoelectric cell model was applied that allows prediction of side ledge countours as well as heat and voltage balances. Based on this model the choice of semi-graphitic vs. fully graphitized cathode blocks was evaluate with respect to the anticipated increase in system amperage. Temperature fields and side ledge contours predicted are in good agreement with measurements. The busbar system, designed originally for a current load of 110 leA, was improved in a very efficient manner to cope with the higher amperage. Magneto-hydrodynamic simulations predicted and plant measurements demonstrated significant improvements in cell stability and performance.
10:55 am ELECTRIC POWER CONTRACTS AND OTHER FACTORS AFFECTING SMELTER ECONOMICS: Nolan E. Richards, 117 Kingswood Dri., Florence, AL 35630; Helge O. Forberg, 8A Quail Ridge Court, Owensboro, KY42303 The cost of electric power for smelters varies from less than 15% to more than 35% of operating costs. For a smelter with a high power rate, it becomes important to obtain a premium in the market for finished products, produce a higher proportion of premium grade metal, increase volume supplemented with purchased scrap, reduce other cost factors or negotiate a power contract that would allow power modulation. The large difference in cost of power demand between a peak period, normally between 6 p.m. and 10 p.m., and the no-peak period can give some smelters the opportunity to negotiate advantageous contracts for reductions in demand of 20-30% during the peak period. Provided the smelter can implement the changes necessary in the operating procedures to maintain control of potroom operations during the modulations, the decreased power rate can have a substantial beneficial affect on the plant's economics. Some of the strategies and major changes which could be considered for a reduction plant to improve economics are discussed in this paper.
9:20am FROM 110 TO 175 kA: RETROFIT OF YAW RHEINWERK. PART II: CONSTRUCTION & OPERATION: 1. Gosh,A. Steube, B. Levenig, YAW AluminiumAG, Koblenzer Str. 122, D-41468 Neuss, Germany Construction, start-up and operation of ten retrofitted 165 leA prebaked pilot cells in the Rheinwerk smelter are described. The excellent performance of these pots led to the DM 40 Mill. investment decision to retrofit all three potlines. The hot-change of cells during full potline operation minimizes production losses. The pilot cells are equipped with improved steel shells and lining, modified busbar system and modern pot controller and point-feeding system. To evaluate the most cost-effective solution with best performance, four cells are provided with two point feeders and six cells with three point feeders. The new-developed VAW-ELAS process controlling system with improved algorithms and a user-friendly graphical interface allows system-
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11:20 am CAPACITY CREEP - THE HIDDEN POTENTIAL GROWTH OF ALUMINIUM SMELTING CAPACITY: K. J. Driscoll, CRU International, Ltd., London WCIX OAD, England Given the lack of firm expansion plans for aluminium smelting capacity over the next few years, many people are expecting a smelter bottleneck to develop towards the end of the century. However, CRU believes that a potential source of capacity growth, which we call "capacity creep", is being ignored. As well as new greenfield and brownfield expansions which might fill the new capacity requirements, incremental production gains at existing smelters can be achieved through lower cost upgrades or improvements in operational efficiencies. Indeed, we believe that such capacity creep has historically added around 0.50-0.75% per year to industry capacity, although many of these capacity increases remain undocumented. This paper will present the results of an extensive study of the potential for growth in aluminium smelting capacity, in which we will review how and where capacity creep has occurred, and show that the potential for further capacity creep remains substantial.
11:45 am ORGANISATION AND INFORMATION SYSTEMS: WHERE INTEGRATION COMES: SA Ferre, Aluminium Pechiney, 235 Avenue Alsace Lorraine, 73007 Chambery Cedex, France; P.w. Cowie, Alusaf Limited, 9 West Central Arterial, P.O. Box 897, Richards Bay 3900, Republic of South Africa Managing an aluminium plant within a concurrential environment demands a greater use of leading edge technology. This technology is of course related to the smelting process but also deals with the organisation scheme and the information provided. During the engineering phase and the construction phase of the Alusaf smelter, Aluminium Pechiney has provided Alusaf with theAP30 technology and has elaborated an organisation with its SA partner. The design and the construction of the information systems have been done in partnership between AP and Alusaf. The information system is based on the use of the state-of-the-art technology and more important is really designed to fit the organisation and to evolve with it. It is built using the 4 classic levels of the CIM model. It takes advantage of packages as SAP R/3 and Microsoft Office Suite tools for routine processes and uses specific developments defined by AP and is used by Alusaf to implement value-adding processes.
APPLICATIONS OF SENSORS AND MODELING TO
MATERIALS PROCESSING - III
Sponsored by: Jt. EPDIMDMD SyntheSiS, Control, and Analysis in Materials Processing Committee and EPD Process Fundamentals Committee Program Organizers: S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; R.G. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487; J.C. Malas, Wright-Patterson AFB, OH 45433-6533; L.L. Shaw, Dept. of Metallurgy & Materials SCience, Univ. of Connecticut, Storrs, CT 06269-3136; R. Abbaschian, P.O. Box 116400, 132 Rhines Hall, Univ. of Florida, Gainesville, FL 32611-6400
Tuesday, AM February 11, 1997
Room: 232A Location: Orlando Convention Center
Session Chairs: S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 378316083; J. Chun, Dept of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
8:30am USE OF IMAGING PYROMETRY SENSOR IN METALLURGICAL PROCESSES C. Lorenson, Quadtek, 14737 NE 87th St., Redmond, WA 98052 The SpyrometerTM imaging pyrometer brings a new dimension of imaging capabilities to temperature measurement technology by combining a high temperature video camera with scanning optical pyrometry. This gives operators the ability to observe process conditions while measuring the tem-
perature of virtually any object or region in the field of view. Since the leps tube of the camera can be air or water cooled, it is possible to insert the opt icallens tube inside furnaces giving very good view of many different type> of metallurgical processes. Specific benefits in process knowledge and maintenance tasks for electric arc melting furnaces, anode furnace and casting wheels, flash smelters, reheat furnaces, and torpedo ladles in different types of metal industries will be discussed.
8:55am A COMPUTED TOMOGRAPHY SENSOR FOR SOLIDIFICATION IN METAL CASTING_ 1. Chun, N. Saka, M. H. Hytros, D. Kim, Dept. of Mechanical Engineering, R.c. Lanza, I.M. Jureidini, Dept of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 We have developed a novel method, using X-ray photons and computed tomography (CT), for distinguishing the solidification front in metal casting processes directly and nondestructively. Depending on the metal, the density of the liquid and solid phases may differ anywhere from 4 to 12%. Computed tomography provides an excellent means of mapping this density difference into a two- or three-dimensional image. Using a C 0 60 radioisotope and aNal scintillation detector, CT image reconstruction was performed on pure tin metal in a two-phase state. In addition, CT image reconstruction was done using a 6 MeV linear accelerator and CdW04 scintillation detector array on pure and alloyed aluminum metals while they underwent solidification. As the speed of the data acquisition and image reconstruction improves, this sensor technology offers the possibility of real-time performance and eventual feedback control for the metal casting process.
9:20am LASER ULTRASONIC SENSING OF SOLID-LIQUID INTERFACES DURING BRIDGMAN SINGLE CRYSTAL GROWTH: H.N.G. Wadley, Y.Lu, D. T. Queheillalt, Intelligent Processing of Materials Laboratory, School of Engineering and Applied Science, University of Virginia, Charlottesville, VA 22903 Using a 3-D ray tracing methodology combined with laser ultrasonically measured elastic constant data near the melting point, ultrasonic propagation in cylindrical single crystal bodies containing either a convex or a concave solid-liquid interface have been simulated and used to design new sensmg concepts. Ray paths, wavefronts, and time of flight (TOF) of rays that travel from a source to an arbitrarily positioned receiver have been calculated. Experimentally measured TOF data have been collected using laser generated! detected ultrasound on model systems with independently known interface shapes. Both numerically simulated data and experimental results have shown that the solidification (interfacial) region can be identified from ultrasonic transmission TOF data. Ultrasonic sensing in the diametral plane is the preferred sensing configuration. Since convex and concave solid-liquid interfaces result in distinctively different TOF data profiles, the interface shape (convex or concave) can be readily determined from the TOF data. When TOF data collected in the diametral plane are used in a nonlinear least squares algorithm, the interface curvature has been successfully reconstructed and ultrasonic velocities of both the solid and liquid obtained, the reconstruction errors were found to be less than 5%.
9:45am EDDY CURRENT SENSORS FOR MONITORING THE NUCLEATION AND GROWTH OF CdO.96ZnO.04Te BULK CRYSTALS: Haydn N.G. Wadley, K.P. Dharmasena, Bill W. Choi, Intelligent Processing of Materials Laboratory, School of Engineering and Applied Science, University of Virginia, Charlottesville, VA 22903 Non-contact eddy current sensing methods have been developed and applied to Cdo96ZnO.04Te crystal growth to obtain a better understanding of the melt, solid nucleation, and the growth process. The application of this sensor approach relies on a large difference in liquid and solid electrical conductivities near the melting point and requires knowledge of the relationships between the electrical conductivity, melt composition, and temperature. Using a multifrequency encircling eddy current sensor, the electrical conductivities of three different Cdl.yZnyTe (y = 0.00, 0.045, and 0.08) alloys were measured as a function of temperature in a laboratory-scale vertical Bridgman furnace. The measured solid and liquid electrical conductivities were then used in electromagnetic finite element models to analyze the multifrequency responses of
eddy current sensor designs during the simulated growth of a crystal. Three eddy current sensors were fabricated and installed in a vertical Bridgman furnace and used to monitor many Cdo.96Zno.04Te growth runs One sensor was placed in the vicinity of the ampoule tip to detect undercooling/spontaneous nucleation and two other sensors {"absolute" and "differential" designs) placed to monitor the movement/curvature of the liquid-solid interface during crystal growth. The sensor data was used to characterize the initial melt state, detect the onset of nucleation, determine the growth velocity, and identify the shape of the interface.
10:10 am BREAK 10:20 am ADVANCES IN SENSING COMPOUND SEMICONDUCTOR CRYSTAL GROWTH: l.P. Wallace, Casting Analysis Corp., RT 2 BOX 113, Weyers Cave, VA 24486 Monitoring compound semiconductor crystal growth using multifrequency eddy currents for sensing illustrates some of the extreme problems of measurement and interpretation of that are not often seen in metallic systems monitored through solidification. Using sensor arrays and scanning have produced a qualitative and quantitative basis for understanding some of the high temperature electrical conductivity mechanisms. The implications of these measurements of electrical conductivity variations are important in that they reflect the complex states of stress that will occur on cooling and heat treating following crystal growth. In particular, for the CdTe and the CdZnTe system, the measurements provide some proof of where the changes in majority defect types occur. The complex nature of the melt and the cooling solid coupled with the growth interface data provide a basis for analyzing the major events during growth and cool down.
10:45 am GAUGING OF HOT TUBE, BAR, AND WELDS BY MULTIFREQUENCY EDDY CURRENT: l.P. Wallace, Casting Analysis Corp., C. Iheagwara, Magnetic Analysis Corp., RT 2 Box 113, Weyers Cave, VA 24486 Refinements in sensor design have produced low-cost rugged elements acting as loops coupled with stable detection hardware. This has allowed direct dimensional gauging of nonferrous and ferrous products above the curie point for absolute dimensions and electrical conductivities independently. The software was developed for the analysis of electrical conductivity profiles in CZ silicon crystal growth, then refined for the monitoring of bar properties, and then tube properties. Since in most metal working operations, speeds at the minimum of a few hundred feet per minute are encountered, the design of the gauge was optimized for a rapid measurement. Independently extracting electrical conductivity provides data in some metal system for determining the temperature of the monitored product. Applications in ferrous heat treatment will be discussed.
11:10am A REMOTELY OPERABLE SENSOR FOR PRECISION SURFACE MAPPING USING COHERENT FREQUENCY MODULATED (FM) LASER RADAR: M.M. Menon, R.E. Barry, P.T. Spampinato, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6305; A. Slotwinski, Coleman Research Corporation, Springfield, VA 22150; M.A. Dagher, Rockwell International Corporation, Canoga Park, CA 91303 A coherent FM laser radar based sensor is being developed for remote metrology of plasma facing material surfaces in the International Thermonuclear Experimental Reactor (ITER). The sensor is capable of three-dimensional mapping of the surface under examination, based on a series of precise range measurements. Sub-millimeter accuracy at large ranges (15 m) has been achieved. Other features that are being incorporated include the ability to operate under adverse environmental conditions involving a combination of very high gamma radiation (3x106 radlh), ultra-high-vacuum (<10-7 torr), and high temperature (200°C). The paper will describe the basic principles of the sensor, together with experimental results obtained with the sensor. The paper will also outline the broad capabilities of the sensor, including its ability for remote rendering of "visual quality" images without the need for any external illumination. Research sponsored by the Office of Fusion Energy, U. S. Department of Energy, under contract DE-AC05-960R22464 with Oak Ridge National Laboratory, managed by Lockheed Martin Energy Research Corp.
AQUEOUS ELECTROTECHNOLOGIES: PROGRESS IN THEORY AND PRACTICE III: Fundamental Studies in Aqueous Electrometallurgy Sponsored by: EPD Aqueous Processing Committee, Copper, Nickel, Cobalt Committee, Lead, Zinc, Tin Committee and Precious Metals Committee Program Organizers: D.B. Dreisinger, University of British Columbia, Department of Metals and Materials Engineering, 309-6350 Stores Road, Vancouver, B.C., Canada; E. Ozberk, Sherrill International, Bag 1000, Fort Saskatchewan, AB, T8l 2P2; Mrs. S. Young, BHP Copper Inc., 2400 Oracle Road, Suite 200, Tucson, AZ 85704; R.S. Kunter, Advanced Sciences Inc., 405 Urban Street, Suite 401, lakewood, CO 80228 Tuesday, AM February 11, 1997
Room: 231A location: Orlando Convention Center
Session Chairperson: R.S. Kunter, Advanced Sciences Inc., 405 Urban Street, Suite 401, lakewood, CO 80228
8:30am THE USE OF FRACTAL DIMENSION WITH AN AGGREGATION MODEL TO CHARACTERISE COPPER ELECTRODEPOSITION IN THE PRESENCE OF THIOUREA: S.P. Fox, S.A. Godorr, A.W. Bryson, School of Process and Materials Engineering, Private Bag 3, Wits 2050, South Africa This work is an extension of a previous investigation on the development of surface roughness during electrodeposition of copper. A comprehensive model based on diffusion and migration in a force field together with surface diffusion and sticking probabilities is used to generate profiles which are compared to those produced experimentally. The roughness is characterized by using the technique of fractal geometry which is shown to describe both qualitatively and quantitatively the development of surface morphology during electrodeposition. The work is extended to the deposition of copper in the presence of various concentrations of thiourea. The development of roughness is observed experimentally on the edge of a thin copper disc mounted between two glass plates. This enables photographs to be taken at various stages during growth. The surface outline is digitized using an image analyzer which enables the fractal dimension to be determined as growth proceeds. As expected the presence of thiourea at low concentrations produces a fractal dimension which is closer to unity (i.e. the surface becomes smoother). The original model is modified to include diffusion and migration of thiourea to the surface. It is postulated that the presence of thiourea on a surface site changes the sticking probability of discharged copper ions at this site. This results in increased surface diffusion of the copper, which in turn produces a smoother deposit. Extensive experimental results are presented which show that the model adequately predicts the effect of changes in thiourea concentrations over a wide range of conditions including those that are of relevance in electrorefining practice.
8:55 am DIRECT RECOVERY OF METALS FROM LOADED ORGANIC SOLVENTS: A REVIEW OF RECENT METHODOLOGIES: L.M. Abrantes, A.P. Paiva, Universidade de Lisboa, Faculdade de Ciencias, Departamento de Quimica, Lisboa, Portugal The application of hydrometallurgical methods to the recovery of metal values from ores and concentrates has been receiving a growing interest, either from researchers or from the mining industry. For the concentration/purification of the relatively low concentrated metallic solutions resulting form the leaching of those raw materials, a well established technique often used is solvent extraction (SX); the loaded organic solvent is then conventionally contacted with a suitable aqueous medium, the metal in its final form being usually recovered form this solution by electrowinning. Methods dealing with the direct stripping of metals from loaded organic extractants have recently been investigated, as an efficient stripping is sometimes difficult to achieve for some solvents. Amongst these innovating processes, the electroreductive stripping (2-phase electrolysis) and cementation (galvanic stripping) must be emphasized, the related research works being cautiously reviewed in the
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present paper. Particularly, the possibility of use of a 2 phase electrolysis to recover basic and precious metals is more extensively discussed. Examples are given for the recovery of copper and silver from suitable organic media, namely by direct application of an electrical potential to a mixture of a silver loaded organic phase containing Cyanex 471X - obtained by SX - and a stabilized sodium thiosulfate solution. The overall efficiencies of these one-step techniques are analyzed and compared with the results obtained by conventional stripping procedures. The purity of the cathodic deposits is also considered. The recovery of silver by galvanic stripping involving iron and zinc powders is also preliminarly evaluated, using a similar organic solution as described above. The influence of temperature on the efficiency of the process is also studied, either for concentrated or more diluted organic silver solutions. The literature data and the results reported here on the application of both methods for direct metal recovery from organic phases show promising advantages over the conventional procedures, encouraging a research effort to optimize and establish these alternative processes.
examines the role of lead and sulfide in this system, by considering the species distribution of these components and by conducting potentiodynamic studies in conjunction with surface analyses of a gold (and lead) electrode.
10:30 am STUDY ON WASTEWATER TREATMENT OF CHEMICAL PLATING SOLUTION USING RECOVERING PROCESSES: Y. Kumagai, National Institute of Material & Chemical Research, Laboratory of Organic Materials, Tsukuba, Japan; F.A. Souza, Federal University of Minas Gerais, Department of Metallurgical Engineering, Belo Horizonte, Brazil Electroless plating processes or chemical deposition processes, have been used in many fields such as automobile and electronic industries. These solutions must be disposed or treated even when the components already have high performance and concentrations. Commonly, in these kind of solution among others components, metal ions are in very high concentrations. The cost of the plating process becomes higher and is very difficult to keep the environmental regulations. The main objective of this study was to investigate the ways to recover the bath components, among them, the metal ion, in order to decrease the cost of the process as well as to meet the environmental regulations. Specifically, in this study was investigated the way to recover, from the exhausted bath, the nickel ion, sulfate ion, phosphite ion and organic compounds. In this case, was investigated a solution for electroless for nickel deposition. The metal ion was recovered from the wastewater by chemical plating onto mica powder surface. The phosphite and sulfate ions were recovered from the wastewater by precipitation as calcium salts. The organic acids were recovered by solvent extraction. These recovery process, used for the metal ion, is particularly important because many studies are investigating the use of mica coated with metal in the development of new composite materials.
9:20am KINETICS MECHANISM OF GOLD ELECTROWINNING: J.A. Garcia, Universidad Nacional de San Juan, Argentina, C. Hecker, Universidad de Concepcion, Chile, E. Larenas, Concepcion, Chile To determine the kinetic reaction mechanism, electrochemical experimental techniques of stationary polarization, linear voltammetry and faradaic impedance were used. Gold electrodeposition experiments were realized using an electrolysis cell, provided by a rotary disk of vitreous carbon and or platinum counter electrode of platinum mesh and reference electrode. Using an automatic measurement system voltammograms and Nyquist faradaic impedance spectra were obtained. In this paper, responses for different cases were analyzed through faradaic impedance criteria, considering several kinds of diagrams obtained. The importance diffusion influence of aurocyanide ions and adsorption as controlling steps previous charge transfer was verified. A model of proposed mechanism is discussed.
10:55 am THE EVALUATION OF FOAMING BEHAVIOUR OFSURFACTANTS FOR ACID MIST CONTROL IN METAL ELECTROLYSIS PRO· CESSES: A.M. Alfantazi, D.B. Dreisinger, University of British Columbia, Department of Metals and Materials Engineering, Vancouver, B.C., V6T lZ4, Canada; J. Synnott, M. Boissoneault, Falconbridge Ltd., Kidd Creek Division, P.O. Bag 2002, Timmins, Ontario, P4N 7Kl Canada
9:45am AN INVESTIGATION ON GOLD ELECTROWINNING FROM ACIDIC THIOUREA SOLUTIONS: C.M. Juarez, A.J.B. Dutra, Federa University of Rio de Janeiro, Metallurgical and Materials Engineering Program, Rio de Janeiro, Brazil
Acid Mist Generation is a major concern in zinc, copper and nickel electrowinning industry and there is a strong environmental drive to control its emission in the work environment. Foaming reagents are typically added to the electrolyte to alleviate this problem. In zinc electrowinning, licorice and saponin are examples of foaming reagents used for this purpose. In order for the foaming reagent to be effective, its foaming behaviour must be determined. In this work, a test procedure was developed to study the foaming characteristics of various surfactants for use as foaming agents to control acid mist in aqueous metal electrowinning. This new test was termed a "mini-flotation test" and it was used to study the foaming behaviour of a large number of reagents in an industrial zinc electrolyte under simulated zinc electrowinning conditions (gas sparging). In addition, the influence of important parameters such as current density, electrolyte temperature, reagent addition level and sulfuric acid concentration on the foaming characteristics of the electrolyte for each surfactant were investigated. This study has identified the most important factors that influence foam formation, growth and stability. This method could be used as a process control measure for reagent addition in the cellhouse by generating a calibration curve for the optimum electrolyte conditions.
The use of thiourea as a gold leaching reagent has been extensively studied by many researchers, and it has proved to be promising for some cases as refractory gold ores and electronic gold scraps. Otherwise, the recovery of gold from these solutions did not receive so much attention. In this paper, the electrowinning of gold in acidic thiourea solutions was studied by voltammetry, chronopotentiometry and electrochemical impedance in a conventional threeelectrode cell with a rotating disc electrode. These electrochemical techniques can provide valuable kinetic information to electrowinning practice. Results have shown that gold electrowinning should be carried out at low current densities in order to avoid cathode passivation and side reactions, as formamidine disulfide reduction and hydrogen evolution at higher overpotentials.
10:10 am ELECTROCHEMICAL ASPECTS OF THE DISSOLUTION OF GOLD IN CYANIDE ELECTROLYTES CONTAINING LEAD: D. Mussatti, J. Mager, G.P. Martins, Colorado School of Mines, Department of Metallurgical and Materials Engineering, Golden, CO 80401
11: 20 am ELECTROWINNING COBALT FROM SULPHATE SOLUTIONS: K.c. Lenthall, A.w. Bryson, Mintek, Private Bag X3015, Randburg, 2125, Republic of South Africa
The role of lead (Pb), at low concentrations in high pH cyanide electrolytes, on the dissolution behaviour of gold has now been a topic of scientific and industrial concern for over 50 years. The recent paper by Kondos et al at CANMET (1995) attests to this continuing interest and apparent importance. Nevertheless, the mechanism(s) by which this (and other heavy metal) component influences the electrodics of this electrochemical system has still not been unequivocally demonstrated. Instead, several plausible hypothesis, by pioneering researchers in this field, have been advanced and reiterated over the ensuing years. While it is generally accepted, based on electrode potential calculations, that co-reduction of lead on the gold surface may occur due to cementation (contact reduction) the cemented lead has never been characterized. The subject matter is confounded further when sulfide (or hydrosulfide) species are also a consitutent of the electrolyte. The work to be presented re-
The effects of operating parameters on cobalt electrowinning from sulphate solutions were investigated. Experiments were carried out in a divided fivelitre cell holding two anodes and a single cathode (150 by 105 mm). The cell was operated in a continuous manner and the catholyte conditions (pH and temperature) were controlled. The following parameters were chosen as a base for the investigation: cobalt feed concentration 90 gil, catholyte pH 2.5, temperature 65°C, current density 250 Nm 2• The feed flow-rate was set to achieve a Co of 30 gil. The cobalt concentration in the catholyte was varied from 25 to 65 gil and the current efficiency was found to increase linearly
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from 90 to 96. Varying the catholyte pH from 2 to 2.75 caused efficiency to increase linearly from 91 to 98%, but above pH 2.75 the rate of increase slowed. Efficiency remained at 95% between 35 and 65C. Cathodic current density was varied between 150 and 350 Nm 2 and did not affect efficiency. Only temperature and catholyte H+ were found to affect the nature of the deposit. Below pH 2.5 many small pits occur. Above this pH, the deposit is shinier and has fewer, though larger, pits. The temperature of the catholyte has a marked effect on the deposit since pitting on the metal decreases dramatically below 50C. In order to simulate realistic cell behaviour, control of catholyte pH was relaxed. The feed flow-rate was varied from 2.2 to 4.5 mV min, corresponding to a Co of 30 to 60 gil. The catholyte pH and cobalt concentration were both found to increase with increasing flow-rate, which caused an increase in efficiency from 82 to 99%. The cell is modeled by considering (i) the transport of H+ across the diaphragm, (ii) the effect of Co and H+ on efficiency using Wark's Rule, (iii) the overall mass balance across the cell.
to quantify the influence of nickel on reduction cell anodes as existing information in the literature did not address specifically the affects of varying concentrations of nickel on anodes. The task force prepared resid with identical properties with the exception of nickel content. These resids were then coked, calcined, and formed into anodes in as identical a process as possible. Finally, the anodes were baked and tested to determine the effects on their performance characteristics. The results and conclusions drawn from this process will be communicated in this paper. 9:20am VIBRATED BULK DENSITY (VBD) MEASUREMENT OF CALCINED COKE AND BINDER CONTROL IN PREBAKED ANODE PASTE: A CASE STUDY: Luc Duchesneau, Roland Lessard, Andre Gendron and Germain Brassard, Alcan International Limited, Arvida Research & Development Centre, 1955 Mellon Blvd, P.O. Box 1250, Jonquiere, Quebec, Canada G7S 4K8 Vibrated bulk density is used to establish the binder content in prebaked anode paste. Alcan adopted the calcined coke VBD analytical method from Collier Carbon in 1961 with slight modifications. Recent paste quality problems (sticking in baking furnaces) were associated with a lack of precision in the VBD. The apparatus was identified as the main cause of imprecision (irregular flow when feeding the cylinder with the vibrating spatula, increase of table vibration amplitude over time and cylinder holding system) and an improved semi-automatic version was constructed. This communication describes the critical parts of the apparatus and their impact on the quality of the results. It also discusses calibration approach, analytical performance achieved (a four-fold improvement in reproducibility sigma =0.003) and the impact on the paste production control.
CARBON TECHNOLOGY I: Petroleum Coke Sponsored by: LMD Aluminum Committee Program Organizer: Jean-Claude Thomas, Aluminium Pechiney, Pechiney I Balzac, 92048 Paris La Defense, France Tuesday, AM February 11, 1997
Room: 230C Location: Orlando Convention Center
Session Chairperson: Lester Mc Coy, Great Lakes Carbon Corporation, P.O. Box "C", Pori Arthur, TX 77640
9:45am PETROLEUM COKE DEOILING FOR PROPERTIES DETERMINATION: R.E. Gehlbach, C.T. Leach, and V.A. Benoit, Reynolds Metals Co., 3326 E. Second Street, Muscle Shoals, AL 35661-1258
8:30am CORRELATION OF COKE PROPERTIES, ANODE PROPERTIES, AND CARBON CONSUMPTION: c.r. Leach, D.G. Brooks, R.E. Gehlbach, Manufacturing Technology Laboratory, Reynolds Metals Company, 3326 East Second Street, Muscle Shoals, AL 35661-1258
The presence of petroleum-based dedusting agents applied to calcined petroleum coke for control of fugitive dust precludes obtaining correct analytical results when certain tests are performed. Removal of various dedusting agents in commercial use is difficult and the process (es) employed may also affect the properties obtained. Results are presented for studies of thermal, solvent extraction, and vacuum deoiling methods and their effectiveness for several surface-sensitive tests. While all methods are observed to remove virtually all of the dedusting agents, different types of residues or decomposition products remain on the coke particles and adversely affect test results. Depending on the particular properties to be determined and the desired accuracy of the results, more than one technique may be required.
Researchers often use calcined coke and anode core properties to predict carbon consumption in aluminum reduction cells. This study compared laboratory analysis data and production data from 1992 through 1995 at RMC's Lake Charles Carbon Company and Baie Comeau Reduction Plant. During this period, carbon plant operations produced anodes with a range of properties using various calcined cokes. The results indicate that calcined cokes having a relatively wide range of properties can produce quality prebake anodes that yield low, stable carbon consumptions. Some coke and anode properties that are considered important quality parameters had little or no detrimental effect on carbon consumption. Correlations exist between certain coke and anode properties during time periods where the properties changed significantly.
10:10 am BREAK 10:30 am EFFECTS OF IRON AND SULPHUR ON THE AIR-AND C02 REACTIVITY OF COKES: Trygve Eidet, Department of Electrochemistry, Norwegian Institute of Technology, Elkem ASA, Research, PO Box 8040 Vaagsbygd, N-4602 Kristiansand, Norway; Morten Sorlie, Elkem ASA, Research, PO Box 8040 Vaagsbygd, N-4602 Kristiansand, Norway; Jomar Thonstad, Department of Electrochemistry, Norwegian Institute of Technology, N-7034 Trondheim, Norway
8:55am QUANTIFICATION OF THE INFLUENCE OF NICKEL ON REDUCTION CELLANODES: Max Casada, Venco, P.O. Box 577, State Route 2, South Moundsville, WV 26041 ; Jeff Rolle, A.J. Edmond Co., 1530 West 16th Street, Long Beach, CA 90813; Chris Eppig, Dr. Steve Paspek, BP Oil Company, 4440 Warrensville Center Road, Cleveland, OH 44128-2837; Zeno DeMori, ORMET, P.O. Box 176/State Route 7, Hannibal, OH 43931; Gary Force, BP Oil Company, 200 Public Square, Cleveland, OH 44114; Jaime Mora, Juan Turpial, Venalum, CVG Industria Venezolana DeAluminio, C.A., Zona Industrial Matanzas, Estado Bolivar, Venezuela; David Hester, Conoco Inc., 1000 South Pine, Ponca City, OK 74602; Mirna Chirinos, Francisco Perez, Alcasa, CVG Aluminio Del Caroni S.A., Zona Industrial Matanzas, Estado Bolivar, Venezuela; Julio Velasco, Venco URB Villa Asia, Calle Bombay Manz. 27,# 10, Puerto Ordaz, Bolivar, Venezuela; Eli Epstein, Don Pirolo, Venco, 600 N. Dairy Ashford, Houston, TX 77252
The aim of this work was to investigate the effects of inorganic impurities on the reactivity of cokes and anode materials and at the same time to avoid the uncertainties that are introduced by the often complex background impurity content in industrial anode cokes. An aromatic distillate fraction from the production of coal tar pitch was used as coke precursor and cokes with controlled amounts of impurities were produced in a laboratory coker. Iron was added to the coke precursor as iron (III) acetylacetonate, and sulphur as dibenzothiophene. These organic substances dissolve in the precursor. The effects of iron and sulphur on the reactivities of cokes were measured in air at 500°C and in CO2 at 960°C. Surface studies (SEM, EDX) showed the topography of the surface, what iron phases were present and indicated the impact of iron and sulphur on the reaction.
The concentration of various metallic compounds in crude oils and in the resulting petroleum coke has continued an upward trend as crude reserves continue to change and tend toward being increasingly heavy and sour. Traditionally labeled as a catalyst, nickel has been included with vanadium in the evaluation of its effects on anode reactivity. In 1995, a Task Force was formed
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The main objectives of the project were: Development of an efficient AITiC master alloy. Fundamental research to understand the mechanism of an AITiC grain refiner. Evaluation of test methods for determination of the grain refining efficiency and agglomeration behaviour of TiC as standard test methods. Production scale testing of the developed AlTiC master alloy. The paper presents the results with respect to the above mentioned objectives.
CAST SHOP TECHNOLOGY III: Grain Refinement, Alloy Properties and Thermal Analysis Sponsored by: LMD Aluminum Committee Program Organizer:Wollgang A. Schneider, YAW aluminium AG, Research and Development, Georg-von-Boeselager-Str.25, 0-53117 Bonn, Germany Tuesday, AM February 11, 1997
9:30am THE DEVELOPMENT OF A COMMERCIAL AI-3% Ti-0.15% C GRAIN REFINING MASTER ALLOY: AJ.Whitehead, S.A.Danilak, Shieldalloy Metallurgical Corporation, Newfield, NJ 08344; Douglas A. Granger, Aluminum Company of America, Alcoa Technical Center, Alcoa Center, PA 15069
Room: 230B Location: Orlando Convention Center
Session Chairperson: Stuart R. Thistlethwaite, London & Scandinavian Metallurgical Co. Ltd., Fullerton Road, Rotherham, South Yorkshire, S60 1DL, England
An AI-3% Ti-0.15% C master alloy has been developed and is now being used for ingot grain refinement in Alcoa. A description is given of the development of the high ratio AI-6% Ti-0.02% C master alloy and the progression from this alloy to the more acceptable lower ratio AI-3% Ti-0.15% C alloy. Acceptance for commercial use came only after extensive metallurgical characterization and evaluation of the grain refining performance, including the impact of alloy type and the presence of tramp elements. Details of the production, testing and characterization of this new grain refining master alloy are discussed.
8:30am AITiB GRAIN REFINER - THE CONSISTENT INGREDIENT: P. C. van Wiggen, KBM Master Alloys The use of AITIB grain refiners for a precise control of the metallurgical cast structure has become an integral requirement in the manufacture of present day products. A permanent high standard in the quality and consistency of grain refiners is essential especially when considering their radical impact on the production result. This paper will discuss the consistency of grain refiners in terms of the composition, the production route and the required grain refiner properties. Particular attention will be given to an in-depth comprehension of the AITiB microstructure. The above will be illustrated by microstructures and further supported by a selection of SPC data, process capabilities and (particle) distribution figures taken from various grain refiners. Information concerning recent advancements in the characterisation and process development of AITiB grain refiners will also be incorporated in this paper.
9:50am THE GRAIN REFINEMENT OF AI-Si FOUNDRY ALLOYS: l.A. Spittle, J.M. Keeble, IRC for Materials in High Performance Applications, Department of Materials Engineering, University of Wales Swansea, Swansea SA2 8PP, United Kingdom Whereas small concentrations of Si have been shown to enhance the grain refinement of aluminium by addition of an AI-TI-B master alloy grain refiner, increasing Si contents in excess of 2-3% result in a continuous increase in primary aluminium solid solution grain size. Two explanations of these observations have been proposed to date based on the influence of Si on either the nucleation or growth of the aluminium primary crystals. Neither of these explanations appears to fit all the available grain size data. In an attempt to further clarify the origin of the Si coarsening effect, grain size studies have been performed on AI-Si and AI-Zn alloys as a function of solute content. It appears that the coarsening is a result of the influence of the Si content on aluminium grain nucleation. A coarsening mechanism is suggested based on the coupled influence of Si level on melt undercooling and primary phase freezing range.
8:50am EFFECTS OF TRANSITION METALS ON THE POTENCY OF TiBAI GRAIN REFINERS: A. Green, M.A. Keams, London & Scandinavian Metallurgical Co. Ltd., Fullerton Road, Rotherham, South Yorkshire, S60 lDL, England TiBAI grain refiners are known to be susceptible to fading and poisoning phenomena which can limit their effectiveness in some practical situations.The long-term fading behaviour of good and bad TiBAI grain refiners in 99.7% Al is presented as a function of temperature in the presence of Zr and other transition metals. It is shown that fade occurs more rapidly at higher temperatures and that the effects of Zr and other transition metals display a complex behaviour as a function of temperature. The observations are explained in terms of recent theories on the behaviour of TiBAI grain refiners which propose that potent TiB2 nuclei have TiA13 layers present on certain facets. It is shown that the reported behaviour is consistent with interactions occurring between transition metals and the potent aluminide layer. Results are discussed in terms of key stages in the production of TiBAI grain refiners and lessons for the use of TiBAI in the aluminium industry are highlighted.
10:10 am BREAK 10:20 am MODIFICATION OF SILICON IN EUTECTIC AND HYPER-EUTECTIC AI-Si ALLOYS: Ben Heshmatpour, Shieldalloy Metallurgical Corporation, 12 West Boulevard, P.O. Box 768, Newfield, NJ 08344 Refining of eutectic silicon in hyper-eutectic and eutectic AI-Si alloys is accomplished by using phosphorus-bearing additives. Commercially available copper-phosphorus (CuP) in a variety of forms and concentrations is widely used for this application. Large addition rates are needed for effective silicon modification via CuP. The recently developed ferro-phosphorus (FeP) based tableted product provides significant performance and cost advantages while requiring much smaller addition rates, lower alloy temperature, and short contact times. This paper compares the results for refinement of A390.1, B390.1, and 339.1 alloys using CuP and tableted FeP.
9:10am DEVELOPMENT OF AN IMPROVED AITiC MASTER ALLOY FOR THE GRAIN REFINEMENT OF ALUMINIUM: W. Reif, Institute of Material Science, Technical University Berlin, Str. des 17.Juni 135, D-10621 Berlin, Germany; A. Green, London & Scandinavian Metallurgical Co. Ltd., Fullerton Road, Rotherham, South Yorkshire, S60 IDL, England; P.C .van Wiggen, KBM Master Alloys B.V., Klosterlaan 2, 9936 TE Delfzijl, The Netherlands; W.Schneider, VAW aluminium AG, Research and Development, Georg-von-Boeselager-Str.25, D-53117 Bonn, Germany; D. Brandner, Hoogovens Aluminium-Walzprodukte GmbH, Carl-Spaeter-Str.lO, D-56070 Koblenz, Germany
10:40 am EFFECTS OF RESIDUAL TRANSITION METAL IMPURITIES ON ELECTRICAL CONDUCTIVITY AND GRAIN REFINEMENT OFEC GRADE ALUMINIUM: R. Cook, M.A. Kearns, P.S. Cooper, London & Scandinavian Metallurgical Co. Ltd., Fullerton Road, Rotherham, South Yorkshire, S60 lDL, England
The commercial AITiB master alloys for grain refinement of aluminium contain TiB2 particles, which can be coarse and have the tendency to agglomerate in the melt. As a result of this, quality problems in different products occur.ln Zr and Cr containing alloys TiB2 interacts with these elements leading to inhomogenous grain structure. In order to avoid the above mentioned disadvantages of the grain refinement with TiB2, a co-operative research programme has been carried out, to develop an improved AlTiC grain refiner.
Removal of transition metal impurities is a key step in production of high conductivity EC grade Aluminium. Titanium and Vanadium in particular are generally removed by adding an excess of Boron to precipitate stable borides before decanting the treated metal. It is nevertheless advantageous to add
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sufficient grain refiner to avoid hot cracking of the cast bar without jeopardising electrical conductivity. We report here a study of the effects of residual Vanadium on the efficiency of different grain refining additives and electrical conductivity of the product. It is shown that Vanadium must be below a threshold figure to give adequate grain refinement at levels which do not compromise conductivity. The effects of residual Fe and Si impurities on grain refinement and conductivity are also described and their role is discussed in terms of constitutional supercooling effects. The relevance of the results to the manufacture of EC grade wire is discussed.
(DTA) by using only an acquisition data system coupled to numerical methods in micro-computers. The kind of information provided by this technique includes thermodynamical and thermophysical data, heat transfer parameters, solidification kinetics, and microstructure features. All this information is more than that obtained with the classic DTA, and it is necessary in order to get a real comprehension of the solidification process. CA-CCA has been applied to the study of an AI-Si system to try to characterize it and to predict microstructure, because it is possible with this technique to obtain the evolution of solid during the solidification process and the segregation behaviour of this system.
11:00 am EXPERIMENTAL MEASUREMENT OF ELECTRICAL CONDUCTIVITY OFALUMINUM ALLOYS AT ELEVATED TEMPERATURES: Raphael Craen, Nagy El-Kaddah, Department of Metallurgical & Materials Engineering, The University of Alabama, P.O. Box 870202, Tuscaloosa, AL 35487-0202; Willem Loue, P6chiney CRV, Parc Economique Centr' Alp-BP27, 38340 Voreppe, France
CHEMISTRY AND PHYSICS OF NANOSTRUCTURES AND RELATED NONEQUILIBRIUM MATERIALS III: THERMAL AND THERMODYNAMIC PROPERTIES Sponsored by: Jt. EMPMD/SMD Chemistry and Physics of Materials Committee, MSD Thermodynamics and Phase Equilibria Committee Program Organizers: Brent Fultz, 138-78, California Institute of Technology, Pasadena, CA 91125; En Ma, Louisiana State Univ., Dept. of Mechanical Eng., Baton Rouge, LA 70803; Robert Shull, NIST, Bldg. 223, Rm B152, Gaithersburg, MD 20899; John Morral, Univ. of Connecticut, Dept. of Metallurgy, Storrs, CT 06269; Philip Nash, Illinois Institute of Technology, METM Dept., Chicago, IL 60616
The knowledge of the electrical conductivity of aluminum alloys is critical for the analysis and computer simulation of induction heating and melting operations as well as electromagnetic casters. While accurate conductivity data are available for pure aluminum, there is a paucity of data for aluminum alloys, particularly at elevated temperature. This paper describes an eddy current technique for measuring the electrical conductivity of metallic specimens at high temperatures. In this technique, which is based on measurement of the electric energy dissipation (Joule Heating), the electrical conductivity is determined from measurement of the heating rate of the specimen. The measurement is made by SUbjecting an insulated cylindrical specimen to a uniform axial alternating magnetic field, and measuring temperature of the specimen during heating. The method requires no contact with the specimen, and is capable of providing electrical conductivity data to the melting point of the specimen with an error of less than five percent. Upon validating the technique using pure aluminum, measurements have been conducted on AIMg (5182) andAI-Li (8090) wrought alloys, and on foundry andrheocastAISi (357) cast ingots. The results show that electrical conductivities of Si and Mg alloys are about one half of pure aluminum, and the microstructure of AISi 357 alloy has little effect on the electrical conductivity of the alloy. The Li containing alloy exhibited a much lower conductivity than Si and Mg alloys. Expressions are presented for the conductivities of these alloys up to 450°C.
Tuesday, AM February 11, 1997
Session Chairperson: Robert Shull, NIST, Bldg. 223, Rm B152, Gaithersburg, MD 20899
9:00 am INVITED STRUCTURE, MECHANICAL PROPERTIES, AND FRACTURE IN NANOPHASE SILICON NITRIDE: MILLION ATOM MOLECULAR DYNAMICS SIMULATIONS ON PARALLEL COMPUTERS: Rajiv K. Kalia, Aiichiro Nakano, Andrey Omeltchenko, Kenji Tsuruta, Priya Vashishta, Concurrent Computing Laboratory for Materials Simulations, Physics and Astronomy, Computer Science, Louisiana State University, Baton Rouge, LA 70803
11:20 am DETECTION OF SOLIDIFICATION REACTIONS USING HEAT PIPE TECHNOLOGY: M. Mahfoud, F. Mucciardi, J.E .Gruzleski, Department of Mining and Metallurgical Engineering, McGill University, 3450 University Street, Montreal, Quebec, Canada H3A 2A 7
Structure, mechanical properties, and dynamic fracture in nanocluster-assembled silicon nitride are investigated with molecular-dynamics (MD) simulations involving 1.08 million particles. The simulations reveal that intercluster regions in the consolidated nanophase Si 3N. are highly disordered with 50% undercoordinated atoms. These disordered interfacial regions deflect cracks and give rise to local crack branching. As a result, the nanophase system is able to sustain an order-of- magnitude larger external strain than the crystalline Si3N•. We also investigate the morphology of fracture surfaces in nanophase Si3N•. The MD results for roughness exponents are very close to experimental values [Po Daguier et al., Europhys. Lett. 31, 367 (1995)] even though the materials and length scales are very different.
Thermal analysis is the measurement of changes in the temperature of a material as it is cooled from an elevated temperature. Usually the temperature changes such as those which occur during solidification are recorded as a function of the cooling time to detect various phase transformations. Although the use of thermal analysis to study the solidification of aluminum dates back 30 to 40 years, the physical techniques for performing thermal analysis have hardly evolved. One aspect of research at McGill has focused on developing a novel device based on heat pipe technology for performing thermal analysis of aluminum alloys. The device operates in-situ on a semi-continuous basis. In addition, the new device allows predefined cooling rates to be set and/or changed during the solidification process. This paper describes the use of the device for: a) measuring grain refining of 356 alloy using AI-5% Ti master alloy, b) determination of eutectic modification of 356 and 413 alloys, and c) detection of reactions involving the formation of copper and iron intermetallics in AI-Si foundry alloys.
9:30 am INVITED THERMAL CONDUCTIVITY OF NANOPHASE CERAMICS: Paul G. Klemens, Physics, University of Connecticut, Storrs, CT 06269-3046 Heat conduction of insulators is by lattice waves (phonons), which have a wide frequency spectrum. The mean free path of phonons is limited by anharmonic intereactions and by scattering, principally scattering by point defects, and by grain boundaries and other etended imperfections. Point defects reduce the mean free path and the contribution to the conductivity of high frequency phonons; grain boundaries that of low frequency phonons. These reductions in conductivity will be discussed. They are additive in materials of micron-sized grains, but not in nanophase materials, where the frequency ranges of phonons affected by point defects and by grain boundary scattering may overlap. The effect of phonon scattering on the thermal conductivy will be discussed with reference to solutes, non-stoichiometry, grain size, and radiation damage.
11:40 am COMPUTER-AIDED COOLING CURVE ANALYSIS (CA-CCA), APPLIED TO AN AI-Si SYSTEM: M.A Ramirez A., J.C .Escobedo B., A.H. Castillejos E., A. Flores v., F.A. Acosta G., Centro de Investigaci6n y de Estudios Avanzados del lPN, Unidad Saltillo, P.O.Box 663, 25000 Saltillo, Coahuila, Mexico The computer-aided cooling curve analysis is a new method for thermal analysis that can be used in foundries of low budget and with small investment. This method tries to simulate the classic differential thermal analysis method
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Room: 330C Location: Orlando Convention Center
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11:15 am INVITED FUNCTIONAL CERAMICS USING NANOMETER-SIZED MATERIALS: Manu Multani, Tata Institute of Fundamental Research, Bombay 400 005, India
10:00 am A SIMULATION STUDY ON THE MELTING OF NANOCRYSTALLINE PLATES AND SPHERICAL CLUSTERS: 1.K. Lee, Metallurgical and Materials Engineering, Michigan Technological University, Houghton, MI 49931; B.K. Cheong, W.M. Kim, S.G. Kim, Materials Design Laboratory, Korea Institute of Science and Technology, Seoul, Korea
Working with a range of current ceramic materials with a wide variety of applications, it is shown that considerable improvements can be obtained when one starts with Small Solid State Systems (S4) Materials studied range from doped ZnO varistors, PZT piezoelectrics, YIG microwave materials, and the new superconductors. General principles underlying these changes are shown to be dependent on the dispersion relations of phonons and wavevectors (for ferroelectrics) and magnons and wavevectors (for ferromagnetics). Another S4 rule that we have found applicable for most oxides is the tendency towards higher symmetry and increasing unit-cell-volume with decreasing size of the S4s. These changes may usher in phase transformation(s) and size dependent phase transition temperatures.
As an emerging mass-data storage technology, phase change (PC) optical recording makes use of the difference in reflectivity between the amorphous and crystalline state of chalcogenide thin films. The amorphous state is obtained via laser melting and subsequent rapid cooling. For a better understanding of the melting behavior of such nanocrystalline plates, a LennardJonesian fcc solid is studied using the method of molecular dynamics. Unlike the bulk case, it is shown that a plate melting is accompanied by a gradual change in both the volume and enthalpy. The melting point of a plate decreases as a function ofh**(-n), where h is the thickness and n is 0.7. If the thickness becomes 15 lattice parameters, the melting point reaches a plateau. (111) plates show slightly higher melting points than those for (100) plates. The melting points of spherical clusters with radii ranging from 1.4 to 6.4 lattice parameters show a r**( on) dependence, where r is the radius and n is 0.75.
DEFINING THE CORE MATERIALS CURRICULUM I: State of the Art Sponsored by:TMS Education Committee Program Organizers: Anthony D. Roliett, Materials Science & Engineering Dept., Carnegie Melion University, Pittsburgh, PA 15213; Martin A. Crimp, Dept. of Materials Science and Mechanics, Michigan State UniverSity, East Lansing, MI 48824
10:20 am BREAK 10:35 am EVIDENCE FOR THERMODYNAMIC STABILIZATION OF GRAIN BOUNDARIES IN Pdl",Zr,: C.E. Krill, H. Ehrhardt, R Birringer, Unversitiit des Saarlandes, FBIO Physik, Postfach 151150, Gebaude 43, D-66041 Saarbriicken, Germany
Tuesday, AM February 11, 1997
The rate of grain growth in a crystalline material is proportional to both the mobility and energy of its grain boundaries. Standard techniques for hindering grain growth, such as solute drag, are kinetic in nature: that is, they aim to reduce the mobility term. A thermodynamic approach, however, should be just as effective: a reduction in grain-boundary energy would be accompanied by a corresponding decrease in the driving force for grain growth. According to the Gibbs adsorption theorem, grain-boundary energies can be reduced by introducing a component that tends to segregate to the grain boundaries. We have investigated ball-milled solid solution of Pdl-xZrz for signs of improved stability against grain growth with increasing Zr concentration; the growth rate is observed to drop to very low values for x greater than 0.2. Differential scanning calorimetry has been used to estimate the concentration dependence of the grain-boundary energy, thereby isolating the themodynamic contribution to grain-growth stability from that due to solute drag.
Room: 340D Location: Orlando Convention Center
Session Chairperson: Anthony D. Roliett, Materials Science & Engineering Dept., Carnegie Melion University, Pittsburgh, PA 15213
8:30 am INVITED CURRICULUM DESIGN; INPUTS AND OUTPUTS: Richard Heckel, Dept. of Metallurgy and Materials Engineering, Michigan Technological Univ., 1400 Townsend Drive, Houghton, MI 49931 Undergraduate engineering curricula are designed by faculty committees in accord with accrediting guidelines for content, logical course sequencing and practical limitations for scheduling faculty and laboratory resources. Presently, engineering education is receiving intense scrutiny due to several decades oflarge tuition increases, continuous enrollment declines since the early '80s, constraints in external research support and decreases in the number of employment opportunities for graduates. These trends have already resulted in proposals for new curriculum designs which WOUld, for example, reduce credits needed for graduation, sacrifice discipline-specific content and increase multidisciplinary activities. Presumably, such curricula would broaden appeal, increase engineering enrollments, widen the range of career opportunities and stimulate interest in industrial interactions. Can such curricula provide the optimum balance between the new educational boundary conditions and quality engineering education? To what extent should curriculum design emphasize graduate/employer feedback, student/parent expectations, instructional philosophy/methodology and general skill development (communication, self-directed learning, open-ended problem solving, ethical decision making, etc.)? Tradeoffs and opportunities associated with these issues will be discussed.
10:55 am VIBRATIONAL DENSITY OF STATES OF NANOCRYSTALLINE Ni3Fe PREPARED BY HIGH ENERGY BALL MILLING: H. Frase', L.J. Nagel!, J.L. Robertson2 , B. Fultz', 'California Institute of Technology, mail 138-78, Pasadena, CA 91125; lOak Ridge National Laboratory, Solid Sate Physics Division, P.O. Box 2008, Oak Ridge, TN 37831 We performed inelastic neutron scattering experiments on two states of Ni3Fe: 1) as-milled, when the material had a characteristic nanocrystallite size of 9 nm, and 2) annealed, when the material had a characteristic crystallite size of 30 nm. The nanophase material showed an enhancement by a factor of 2 in its density of states at energies below 15 meV, and some broadening of its longitudinal peak at 33 meV. The large enhancement in the density of states at these low energies appears to require coupling between inter- and intra-crystallite vibrational motions. The inter-crystalline modes would be associated with the vibrations of the crystallites themselves. These measured changes in vibrational DOS predict a difference in vibrational entropy of the bulk and nanocystalline Ni3Fe of about 0.18 kB/atom at high temperatures, with the nanocrystalline materials having the larger vibrational entropy. This work was supported by the U.S. Department of Energy under contract DE-FG0386ER45270.
9:00am THE MATERIALS SCIENCE AND ENGINEERING CORE CURRICULUMAT VIRGINIA TECH: RW. Hendricks, RS. Gordon, Virginia Tech, MSE Dept., Blacksburg, VA 24061-0237 We have developed a core curriculum for an ABET-approved Materials Science and Engineering curriculum incorporating 8 required core course" options in each of the 5 principle fields (ceramics, composites, electronic materials, metallurgy and polymers), and developed an integrated "across-the-curriculum" approach to writing and communication, ethics, and statistic,. Our required core courses, each with laboratory, include physical ceramics, physical metallurgy, electronic materials, and polymer engineering. These "material
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10:15 am INVITED INDUSTRIAL EXPECTATION OF A MATERIALS EDUCATION: AN AUTOMOTIVE VIEW: R. Heimbuch, D. Mattis. J. Hall, General Motors, 30300 Mound Road, NMD-36, Warren, MI 48090-9040
specific" courses are supported by three material-independent courses including X-ray diffraction, thermodynamics and transport processes, and by a capstone engineering design course based on a research project. Oral, written, and graphical communication, statistics, and ethics and integrated in a manner such that the student is led from fundamental concepts through to sophisticated interpretation of each topic. The student is exposed to these "across-the-curriculum" topics during each semester of the three year program of study beginning with the sophomore year.
Competitive pressures have caused the automotive industry to critically examine and modify their engineering processes. The new engineering processes have put a higher value on certain skill sets than in the past. The need for technical competence has not changed - it is a given. The question for the Education Community is how to maintain a strong balanced technical framework while developing other critical skills. The goal should be to enhance the effectiveness of the student as he or she moves into and through their professional career. The authors will share their views around the critical question of "balance" and "critical skills".
9:25 am MATERIALS SCIENCE AND ENGINEERING: THE NEW UNDERGRADUATE CURRICULUM AT DREXEL UNIVERSITY: Alan Lawley, Dept. of Materials Engineering, Drexel University, Philadelphia, PA 19104 In 1994 the new undergraduate Drexel Engineering Curriculum was implemented, emphasizing 'up front' engineering, computer and communication skills, life long learning and teamwork. This common core in the first two years reflects many of the tenets and the philosophy of the E4 experiment ('Enhanced Educational Experience for Engineering Students') which began in 1988. Concurrently, the Department of Materials Engineering has been proactive in the Gateway Coalition, a major component of which is to build on E4 by focusing on the upper level curriculum via the development of advanced engineering science courses. Our new undergraduate major, enacted in 1995, reflects the maturing of the E4 experiment into the core Drexel Engineering Curriculum and the integration of selected engineering science courses (developed under the Gateway Coalition) into the curriculum at the upper level. Evolution of the new curriculum is discussed, including the development of modules in materials education.
10:45 am RESTRUCTURING UNDERGRADUATE EDUCATION AT ILLINOIS INSTITUTE OF TECHNOLOGY; CASE STUDY: METALLURGICAL AND MATERIALS ENGINEERING PROGRAM: Marek Dollar, Mechanical, Materials and Aerospace Engineering Dept., Illinois Inst. of Technology, Chicago, IL 60616. There is a broad recognition at lIT that we live in a time of revolutionary change in undergraduate education. In response, we are developing new ways to recruit and retain a diverse student body, seeking educational relationships with industry, experimenting with new approaches to teaching and learning, and positioning ourselves to meet ABET engineering criteria for the year 2000. The key elements of the undergraduate education restructuring will be presented. They include, but are not limited to, such initiatives as: Interprofessional Projects, project-oriented learning that teams students from different disciplines and professions and constitutes a new instructional tool though which students learn concepts of teamwork, communication and problem solving; Introduction to the Professions, a freshman-level course that in an innovative way bridges the gap between high school experience and the university's environment; Writing Across Curriculum, an institutional structure for integrating writing into engineering courses. Our attempts to increase computer competence, introduce multimedia in the classroom and create undergraduate research opportunities will also be discussed.
9:50am MATERIALS SCIENCE AND ENGINEERING CURRICULA; RETHINKING THE CORE CONTENT - THE CASE FOR A 128 HOUR CORE: Richard L. Porter, Campus Box 7904, North Carolina State University, Raleigh, NC 27695-7904 Most materials educators agree that three major components constitute the undergraduate materials science and engineering curriculum; that presented in the first 2-3 semesters (generally the basic sciences), the real "core," and finally the obligatory senior design or capstone experience. Scattered throughout will be the necessary humanities and social sciences, maybe a communications course or technical writing course. It is as summed that the mathematics, chemistry, physics, and writing have been properly and correctly introduced and students' have mastered the content. There are several problems with this approach; little if any experiential learning, little if any contextual learning for the basic sciences, little integration of engineering sciences with the basic sciences, and in many cases a disconnected core. Although all curricula meet and or exceed ABET criteria, there is little accountability for the actual content and methodology of presenting the material. This paper discusses the entire curricula in context with the intended outcome for materials science and engineering and encourages curricular designers to rethink the entire learning experience, not to simply add more courses for short term accomplishments. At North Carolina State University, our approach has been to introduce different models for first year engineering, ranging from a handson engineering experience linked with freshmen writing, an integrated approach pulling together math, chemistry, and physics, with a year year engineering overview, and recently a new freshmen course linked with the computer literacy course and including a weekly small-group problem solving session. Concurrently, we have administered an attitudes survey at the beginning of the year and again at the end of the semester and year. Students enrolled in these special courses report a greater interest in engineering as a problem solving discipline, they view engineering as an iterative process, and report a higher degree of satisfaction with their first year experiences. Finally, a curriculum will be presented and discussed that builds upon the fundamental basic sciences and integrates the curriculum rather than present it as a linear combination of sub-disciplines.
11:10 am EFFECTIVE USE OF A SMALL FACULTY FOR MAINTENANCE OF A COMPREHENSIVE MATERIALS ENGINEERING PROGRAM: Jeffrey W Fergus, Materials Research and Education Center, 201 Ross Hall, Auburn University, AL 36849 A recent analysis of the materials/metallurgical engineering programs at U.S. universities shows that these programs can be divided into three, approximately equal, groups in terms of faculty size. Specifically, there are 24 programs with 21-90 faculty, 23 programs with 13-20 faculty and 25 programs with 3-12 faculty. The small number of faculty in this latter group presents challenges in terms of maintaining a comprehensive (undergraduate, graduate, research) materials program. This presentation will relate experience with the materials engineering program at Auburn University, which has 7 fulltime faculty, in meeting these challenges. In addition, the contribution of these small programs to the materials engineering discipline as a whole will be discussed.
11:35 am Title TBA: SamuelAllen, Dept. of Materials Science and Engineering, Mass. Inst. of Technology, Cambridge, MA 02139
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DESIGN AND RELIABILITY OF SOLDERS AND SOLDER INTERCONNECTS: Session III: Design and Reliability of Lead-Free Solders and Solder Interconnects Sponsored by: MSD Flow and Fracture; SMD Mechanical Metallurgy; EMPMD Electronics Packaging and Interconnection Materials Committees Program Organizers: R.K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; D.R. Frear, Sandia National Laboratory, Mail Stop 1411, Albuquerque, NM 87185; S.M.L. Sastry, Washington University, Mechanical Engineering Dept., St. Louis, MO 63130; K.L. Murty, North Carolina State University, Materials Science and Engineering Dept., Box 7909, Raleigh, NC 27695; P.K. Liaw, University of Tennessee, Materials Science and Engineering Dept., Knoxville, TN 37996; W.L. Winterbottom, Reliability Consultant, 30106 Pipers Lane Court, Farmington Hill, MI 48331 Tuesday, AM February 11, 1997
Room: 332 Location: Orlando Convention Center
Session Chairpersons: Judy Glazer, Hewlett-Packard Co., Electronic Assembly Development Center, Mail Stop 4U-3, 1501 Page Mill Road, Palo Alto, CA 94304; James F. Maguire, Boeing Co., P. O. Box 3999, Defense & Space Systems Group, Mail Stop 3W-97, Seattle, WA 98124
8:30 am INVITED DESIGNING WITH Pb-FREE SOLDERS: Walter L. Winterbottom, Reliability Consultant, 30106 Pipers Lane Court, Farmington Hill, MI 4833 I As the global competition in the transportation industry intensifies, the focus on quality and time-to-market have become major driving forces in product design and dominant forces in the market place. Although the current designJ development process as practiced in the industry provides a time tested path for new products, leadership in these areas seems to be elusive. A York Times article (March, 1991) notes that Consumers Report ranks the reliability of new American models at about the level of the average Japanese models. In 1988, the Material Systems Reliability Department was organized in the Materials Research Laboratory of Ford Research with the mission to evaluate existing, and develop if necessary, design methodologies capable of the task of providing world leadership in both quality and time-to-market. It was apparent from the outset that a life-cycle design approach must be used to contain reliability, cost, and environmental considerations in a time efficient manner. Further, it became increasingly apparent from the Department's failure mode/root cause identification and testing assistance activities that these issues have to be designed into a product rather than being assured by extensive prototype testing programs. A Design-for-Reliability methodology based upon the development of analytical prototypes which has the capability to fulfill the requirements for world leadership. The methodology is based upon the definition of system failure modes and mechanisms, system model development with verification capable of reliability prediction early in the design process prior to the building and testing of prototype hardware. This 'preventive' approach is based upon quantitative reliability estimates as a key design metric for use in assessing design alternatives. In simplest terms, the approach emphasizes the need to consider products as material systems whose reliability must be thoroughly understood early in the design and development process. The traditional 'build, test, and fix' design approach must be replaced with an approach that relies upon analytical prototypes leading to a single, optimized, prototype hardware build. In the presentation, the Design-forReliability approach will be illustrated using electronic packaging design with lead-free solder interconnects as example. 8:55 am INVITED DESIGN OF NEW SOLDER ALLOYS THROUGH MICROSTRUCTURE CONTROL: Sungho Jin, Lucent Technologies, Bell Laboratories, Room lA-I23, 700 Mountain Avenue, Murray Hill, NJ 07974 The mechanical properties of solder alloys and reliability of solder joints are significantly affected by microstructural features such as grain size, phase distribution, and precipitate morphology. A finer grain size, smaller precipi-
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tates, and a uniformity in phase, precipitate and grain size distribution are often beneficial for improving the strength and ductility as well as the resistance in fatigue and creep failures. The control of microstructure is accomplished by modifications in alloy chemistry and processing conditions. Several examples of microstructural control in lead-free solder systems will be discussed. More forward-looking approaches for further control of microstructure in solder alloys and composites, e.g., by distribution of nano-scale dispersoid particles will also be discussed. 9:20 am INVITED LEAD-FREE SOLDERS FOR ELECTRONIC ASSEMBLY: Fay Hua, Judy Glazer, Hewlett-Packard Co., Electronic Assembly Development Center, Mail Stop 4U-3, 1501 Page Mill Road, Palo Alto, CA 94304 This paper gives an up dated literature review on the metallurgy of lead-free solders for electronic assembly. The review includes newly reported technical data on existing binary Sn-based eutectic alloys: Sn-Ag, Sn-Bi, Sn-Cu and Sn-In. It also reviews the newly developed mUlti-component solder alloys in following systems: Sn-Zn-In, Sn-Zn-Bi, Sn-Zn-Sb, Sn-Ag-Zn, SnAg-Cu(-Sb), Sn-Ag-Bi, Sn-Ag-In(-Sb), Sn-Bi-In, and Sn-Bi-Sb. The characteristics of these alloys described are chemical composition, physical properties, microstructure, and mechanical properties. The manufacturability issues and applications of these lead-free solders in electronic assembly will be presented. 9:45 am INVITED SUMMARY OF RECENT STUDIES OF THE EFFECT OF PROCESSING ON MICROSTRUCTURE OF SOME SOLDER ALLOYS: James Clum J , E. Cotts 2, N. Jiangl, lMechanical Engineering, 2Physics Department, State University of New York at Binghamton, Binghamton, NY 13902 A variety of solder alloys selected from the Sn-based, and In-based systems, have been examined to test for the interaction of composition with processing conditions in controlling alloy microstructure. Rate of solidification, amount of compressive strain, annealing temperature and time were the independent variable studied. Grain size, phase fraction and microhardness have been monitored as measures of microstructural changes. A simple factorially designed experimental plan has been used to conduct and interpret the tests. A major effect of solidification rate and a secondary effect of the interaction between deformation and annealing was observed for most alloys. The effect of alloy composition is reflected primarily in terms of the role ofT,mb,omlTmon microstructural stability. Some other processing related characteristics of these solder alloys will also be discussed such as creep and stress relaxation behavior. The role of microstructure in behaviors such as grain boundary sliding will be illustrated. 10:10 am EVALUATION OF ALTERNATIVES TO LEAD SOLDERS FOR PRINTED WIRING APPLICATIONS: James F. Maguire, Boeing Co., P. O. Box 3999, Defense & Space Systems Group, Mail Stop 3W-97, Seattle, WA98124 This paper describes the first phase of a three year program undertaken by Boeing to evaluate "no lead" materials as a potential replacement for solder in printed wiring assembly applications. This program is looking at a number of different potential replacements including both conductive adhesives and "no lead" solder materials. In addition, the impact of other environmentally driven process changes such as "no clean" soldering and lead free PWB finishes are being tested for compatibility with "no lead" attachment materials. The phases of this program are: Phase I: Initial materials evaluations. processability, stability of electrical performance in environmental exposure, sequential exposure to temperature/humidity cycling and thermal shock environments, compatibility with "standard" finishes (reflowed solder and "deoxidized" copper), down Selection for Phase II testing; Phase II: detailed material performance testing, stability of contact and bulk resistance during environmental exposure, compatibility with high speedIRF applications, * Compatibility with existing PWA processes such as - pre-conformal coat cleaning, rework/repair, down selection for Phase III testing; Phase III: Development of design allow abies and manufacturing processes. This paper will discuss the results of Phase I of this program which evaluated a total of 21 conductive adhesives and 8 commercially available solder alloys with control samples fabricated with Sn63 solder.
10:30 am CREEP AND MECHANICAL PROPERTIES OF Sn-5%Sb SOLDER: Rao K. Mahidhara l , K. Linga Murty' and Fabmy M. Haggag" 'Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; "North Carolina State University, Raleigh, NC 27695; "'Advanced Technology Corporation, Oak Ridge, TN 37830 A knowledge of the mechanical and creep properties of solder materials is required both for alloy development and life-prediction. We report here tensile and creep properties of Sn-5%Sb which is one of the candidate materials for replacing lead-based solders in electronic packaging. The temperature and stress dependencies of the strain-rate are evaluated using both the tensile and creep tests. In addition, the recently developed Stress-Strain Microprobe (SSM) is used to evaluate the strain-rate dependence of stress through automated ball indentation (ABI) tests at ambient. An excellent correlation is noted between creep and ABI data. While creep tests covered low stresses, ABI corresponded to high stresses which revealed breakdown of the Norton-law noted at lower stresses. While creep tests took 5 months time, the ABI tests were completed in a matter of hours although they covered 3 orders of magnitude strain-rates. The utility of ABI technique in solder joints is clearly pointed out and such tests are planned on real joints. ABI tests at elevated temperatures were not performed to-date. Such a facility is now under development and future plans include testing at elevated temperatures on bulk as well as solder joints. 10:50 am BREAK 11:00 am CHARACTERIZATION OF 58Bi-42Sn SOLDERED ON Sn-Pb COATED SURFACE: Zequn Mei, Fay Hua, Judy Glazer, Hewlett-Packard Co., Electronic Assembly Development Center, Mail Stop 4U-3, 1501 Page Mill Road, Palo Alto, CA 94304 As reported in our previous work, solder joints of 58Bi-Sn on 80Sn-20Pb coated surface failed prematurely in thermal cycles between -40°C to 100°C. The failure mechanism was identified to be the dissolving of Pb atoms into the 58Bi-Sn solder joint during soldering, which caused formation of the ternary eutectic 52Bi-30Pb-18Sn with melting point of 95°C. In this paper, study of three types of solder joints will be reported: (I) 58Bi-42Sn soldered on Cu surface, (2) 58Bi-42Sn solder on 80Sn-20Pb coated surface, and (3) 57.5Bi41.5Sn-IPb soldered on Cu surface. These solder joints were aged at 80°C and 110°C. The evolution of the grain or phase sizes and the degradation of mechanical properties will be characterized as function of aging time. Early results indicate that the grains grew much faster in the solder joints containing Pb atoms (types 2 and 3 above), which reduced mechanical strength and ductility, than the solder joints without Pb atoms (type I). Detailed results will be reported in the meeting. 11:20 am MICROSTRUCTURAL STABILITY AND MECHANICAL PROPERTIES OF TIN-SILVER-COPPER SOLDER JOINTS: Iver E. Anderson, Ozer Unal, Ames Laboratory, Iowa State University, 122 Metals Development Bldg., Ames, IA 50011 The properties of a Pb-free ternary eutectic solder alloy, Sn-4.7Ag-1.7Cu (wt.%), which was discovered in our laboratory have been evaluated. This patented alloy has a melting point of 217°C, a fine 3-phase eutectic microstructure, and a very good solderability. The primary goal of this investigation has been to enhance its microstructural stability for high temperature environments, greater than 125°C, and to improve its overall mechanical properties, especially for extended service. Thus, minor modifications were made in the base eutectic alloy to control microstructural aging without degrading solderability. Alloying effects on solder/Cu joints in the as-soldered and aged conditions were studied. Tensile strength and shear strength measurements were made using butt and lap shear joint configurations, respectively, under various loading conditions. The results will be presented and their implications will be discussed. Support from the DOE-BES-DMS under Contract No. W-7405-Eng-82 is gratefully acknowledged .
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11:40 am THERMAL AGING AND IN-BOARD PEEL TESTING OF PB-FREE SOLDERS FOR UNDERHOOD APPLICATIONS: Martin W. Weiserl , Julie A. Kern', Celeste A. Drewien l , Frederick G. Yost" 'Johnson Matthey Electronics, Spokane Assembly Products Group, 15128 E. Euclid Avenue, Spokane, WA 99216; 'University of New Mexico, Mechanical Engineering Department, Albuquerque, NM 87131; 3Sandia National Laboratories, Materials and Process Sciences Center, Albuquerque, NM 87185 The thermal aging and post aging joint strength of four Pb-free solder alloys on a Ag-Pt thick film metalization were studied as the last part of a larger evaluation of solderlflux/metalization systems for use in high temperature under hood automotive application. The solders were the Sn-Ag and Sn-AgCu eutectics and a Bi modified version of each. Solder pastes were reflowed on metalized alumina in a commercial inert atmosphere belt furnace. Aging of both sessile drops and in-board peel test samples was conducted at 134 to 190°C for up to 1000 hours. Addition of Bi and/or Cu increased the intermetallic growth rate and decreased the in-board peel strength. 12:00 am RATE-CONTROLLING MECHANISM DURING PLASTIC DEFORMATION OF 95.5Sn4CuO.5Ag SOLDER JOINTS AT HIGH HOMOLOGOUS TEMPERATURES: Hans Conradi, Z. Guo' and Y H. Pao l , 'Materials Science and Engineering Department, North Carolina State University, Raleigh, N. C. 27695; 'Ford Scientific Research Laboratory, Materials Systems and Reliability Department, 20000 Rotunda Drive, Dearborn, MI48121 The effects of stress and temperature on the creep rate of 95.5Sn4CuO.5Ag solder joints at 22T to 168'C were investigated employing stress-change and temperature-change tests. The resulting plastic deformation kinetics are in accord with those obtained previously in constant strain rate tests. They are better described by an obstacle-controlled dislocation glide kinetics equation than the usual Dorn equation for diffusion-controlled mechanism. The Helmholtz free energy for overcoming the obstacles is 0.28/lb3, where /l is the shear modulus and b the Burgers vector. The activation volume is of the order of 1000 b 3. The plastic deformation kinetics are in reasonable accord with the intersection of dislocations as the rate-controlling mechanism. However, alternative mechanisms are not ruled out. 12:20 pm ALLOY DESIGN OF Sn-Zn-X (X=In, Bi) SOLDER SYSTEM THROUGH PHASE EQUILIBRIA CALCULATIONS: Sueng Wook Yoon l , Jeong Ryong Soh', Byeong-Joo Lee', Hyuck Mo Lee', 'Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Kusung-Dong 373-1, Yusung-Gu, Taejon, Korea 305-701; 'Materials Evaluation Center, Korea Research Institute of Standards and Science, p. O. Box 3, Taedok Science Town, Taejon, Korea 305-606 Thermodynamic studies ofthe Sn-Zn-X (X=In, Bi) system have been carried out in terms of phase equilibria to design Pb-free solder alloys which are drop-in replacement for Sn-37Pb alloy. Based on the result of phase equilibria calculations, several selected alloys were chosen and analyzed by DSC, XRD and EPMA techniques. Microstructures of as-cast and heat-treated alloys were examined as well as the interface between solder joint and Cu substrate by optical microscopy and SEM. Spreading area test and preliminary mechanical test were performed to investigate the possibility as an alternative of eutectic Pb-Sn-solder.
relative misorientation of neighboring grains. In this case, the grain grow~h evolution favors pairs of grains separated by low angle (low energy) grCllIl boundaries. Such low energy boundaries generally separate grains ofthe same texture component. Other effects, such as pinning by surface grooving, pinning by precipitate particles or holes in the film, and solute drag may also be included in the simulations.
EVOLUTION AND ADVANCED CHARACTERIZATION OF THIN FILM MICROSTRUCTURES III: Evolution of Microstructure Sponsored by: MSD Structures Committee, EMPMDThin Films and Interfaces Committee Program Organizers: Eric P. Kvam, School of Materials Engineering, Purdue University, West Lafayette, IN 47907-1289; Steven M. Yalisove, Dept. Materials Science and Eng., HH Dow Bldg., University of Michigan, 2300 Hayward St., Ann Arbor, MI48109-1204; Eric P. Chason, Sandia National Labs., Dept. 1112, MS 1415, PO Box 5800, Albuquerque, NM 87185 Tuesday, AM February 11, 1997
9:50am POST-PATTERNING MICROSTRUCTURE EVOLUTION OF AI-Cu INTERCONNECT LINES: D. P. Field, TexSEM Laboratories, Inc., 226 W. 2230 N., Provo, UT 84604 Optimization of microstructural features in interconnect lines for integrated circuits is becoming increasingly important for device reliability as the minimum feature size continues to shrink. Recent efforts have clearly demonstrated that not only grain size and precipitate morphologies are affected by the patterning and subsequent anneal, but also the crystallographic texture and grain boundary structure evolve during this process. For narrow lines, the (111) fiber texture sharpens and the near-bamboo grain structure is controlled by interface area minimization and grain boundary energy minimization. The current work describes the competing energetics associated with the process. Experimental results using orientation imaging microscopy as the analysis technique on AI-l % Cu interconnect lines are shown to support the analyses.
Room:340C Location: Orlando Convention Center
Session Chairs: J.E. Sanchez, Jr., University of Michigan, Ann Arbor, M148109; C.V. Thompson, Dept. of Materials Science and Engineering, M.I.T., Cambridge MA 02139
8:30 am INVITED GRAIN GROWTH IN POLYCRYSTALLINE TIDN FILMS: C.y'Thompson, Dept. of Materials Science and Engineering, M.I.T., Cambridge MA 02139
10:10 am BREAK 10:30 am INVITED CRYSTALLOGRAPHIC TEXTURE EVOLUTION DURING FILM FORMATION AND ANNEALING IN SPUTTERED Al ALLOYffi AND Al ALLOyrriNffi LAYERS: J. E. Sanchez. Jr., University of Michigan, Ann Arbor, MI 48109; P.R. Besser, 1. Williams, Advanced Micro Devices, Sunnyvale, CA 94088; D.K. Knorr, Rennselaer Polytechnic Institute, Troy, NY 15128
Polycrystalline thin films are used in a wide variety of applications, especially in electronic and magnetic devices and systems. In these applications, the properties, performance and reliability of polycrystalline films are strongly affected by the average grain size, grain shapes, the way in which grain sizes are distributed and the distribution of grain orientations. These vary with deposition technique and with deposition conditions, and can also be modified through post-deposition processing. The factors which affect the structure and crystallographic texture of polycrystalline films will reviewed and categorized. Approaches for process development for application-specific optimized structures will be outlined.
Ti, TiN and Al alloy thin films comprise the basis for patterned metallization interconnects in advanced integrated circuit devices. Ti in particular has been shown to provide increased reliability of the primary Al conductor against electromigration-induced failures. A proposed mechanism is for this improvement is increased Al (III) film fiber texture due to the presence of the Ti underlayer. A review of extensive Al texture characterization by x -ray diffraction methods will be presented for various Ti, TiN, and AI layering schemes and sputter deposition conditions. Factors such as substrate surface energy, substrate roughness, Al grain growth, and "texture inheritance" between layers will be discussed. Deposition and processing schemes for improved Al (III) texture and improved interconnect reliability will be provided.
9:10am NEW MICROSTRUCTURAL CHARACTERISTICS OF POLYCRYSTALLINE GOLD TIDN FILMS: Alexander H. King, Varun Singh, Department of Materials Science & Engineering, State University of New York at Stony Brook, Stony Brook, NY 11794-2275 We have made detailed observations of unsupported gold thin films, using transmission electron microscopy. These films embody a strong [111] fiber texture, as found in many FCC metal thin films. Rotations of individual grains about the [111] surface normal are observed and we present a simple model that mimics this behavior, providing a reasonable explanation for it. We will also present an analysis of the triple junctions in the films showing that symmetry is the most significant factor in determining the energy associated with a triple junction. We will show that supposed "U-lines" do not embody the disclinations that are expected on the basis of Bollmann's analysis. Acknowledgment: This work is supported by the National Science Foundation, under grant number DMR-9530314.
11:10 am THE EFFECT OF MICROSTRUCTURE AND LOCAL MICROSTRUCTURE VARIATIONS ON ELECTROMIGRATION FAILURE DISTRIBUTIONS: Dirk D. Brown, AMD, Sunnyvale, CA 94088; John E., Sanchez, Jr., University of Michigan, AnnArbor, MI 48109; MattA. Korhonen, Che-Yu Li, Cornell University, Ithaca, NY 14850 In narrow metal lines used for chip level interconnects, the electromigration reliability is affected by variations in the microstructure. Electromigration failure distributions were obtained experimentally for six different AI-Cu interconnect widths, ranging from Imm to 8mm. Or each of these line widths, the microstructure was characterized (using TEM) and the initial stress distribution was calculated. This information was used, with a flux divergence model, to simulate the entire failure distribution for each line width. These simulations, when compared to the experimental failure distributions, were used to quantify important material parameters, such as atomic diffusivities and failure criteria. This information, in turn, can be used to accurately extrapolate electromigration data. A detailed failure analysis was carried out on the simulated lines to study the effect of microstructure variations on electromigration failure.
9:30am MODELING OF GRAIN GROWTH IN TIDN FILMS WITH TEXTURE: Harold J. Frost, Johan Grape, Thayer School of Engineering, Dartmouth College, Hanover, NH We have developed our two-dimensional simulation of grain growth to include several effects which apply for the case of large-grained polycrystalline thin films in which the grains completely traverse the film thickness and the grain boundaries are all nearly perpendicular to the plane of the film. To properly include the effects of texture we must include the following factors which differ among individual grains based on crystallographic orientation: surface energies for the film-substrate and film-covering interface; elastic compliances, and the related strain-energy densities when elastic strains are imposed; yield stresses, which limit the elastic strains and strain-energy densities. In this paper we will expand on previous treatments by explicitly allowing for variations in grain boundary energy and mobility, based on the
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1l:30am LOCAL GRAIN BOUNDARY STRUCTURE CHARACTERIZATION IN VOIDED COPPER INTERCONNECTS: R.R. Keller, National Institute of Standards and Technology, Materials Reliability Division, 325 Broadway, Boulder, CO 80303; J.A. Nucci, Cornell University, School ofElectrical Engineering, Phillips Hall, Ithaca, NY 14853; D.P. Field, TexSEM Laboratories, Inc., 226 West 2230 North #120, Provo, UT 84604
size was roughly 60 nm. The deformation temperature is several hundred degrees below those used for sintering microcrystalline powders. Pore elimination is promoted during sinterforging by the deviatoric stress components due to the absence of die- wall constraints. The resultant shear deformation is undoubtedly enhanced by grain boundary deformation modes in nanocrystalline material. Hardness measurements at moderately elevated temperatures are used to develop the constitutive relation for deformation of TiAI. Densification and deformation have been studied as a function of temperature, load and grain size.
We have characterized grain boundary structures and local textures in oxide passivated copper lines which had undergone thermal stress-induced voiding. Grain boundary misorientations and the crystallographic character of boundary planes were determined for individual grain boundaries using electron backscatter diffraction in the scanning electron microscope as well as focussed ion beam images. We have summarized the data for a number of boundaries immediately adjacent to voids and made direct comparisons to boundaries from regions which remained intact. These data were acquired from the same lines, and so represent measurements from material with identical thermal histories. The results suggest that significant variations in local structure exist in narrow lines, and that those local regions associated with more favorable kinetics are more susceptible to void formation and growth.
9:20am ROLE OF MICROSTRUCTURE ON SUPERPLASTICITY IN Y-TiAl ALLOYS: R.S. Mishra, A.K. MukheIjee, Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 A number of y -TiAI alloys exhibit superplasticity. The optimum superplastic temperature is strongly dependent on the grain size. For materials with grain sizes > 10 IJ.m, the superplastic temperatures are above a, transition temperature. On the other hand, superplastic temperatures for materials with grain sizes <5 IJ.m is below 1373K. Surprisingly, however, the state of second phase i.e. ordered a, or disordered a does not influence the kinetics of superplastic deformation and the parametric dependencies remain similar. These observations suggest that the slip accommodation and dislocation climb in g phase as the rate controlling mechanism. Some new results on nanocrystalline yTiAI are presented, which shows the possibility of low temperature superplasticity. The flow stresses in submicrocrystalline and nanocrystalline y-TiAI alloys are consistent with a slip accommodation model.
FUNDAMENTALS OF GAMMA TITANIUM ALUMINIDES III: Processing, Microstructure and Properties Sponsored by: MSD Flow & Fracture and Phase Transformations Committees Program Organizers: Kwai S. Chan, Southwest Research Institute, San Antonio, TX 78228-0510; Vijay K. Vasudevan, Dept. of Materials Science & Engineering, University of Cincinnati, Cincinnati, OH 45221-0012; Young-Won Kim, UES, Inc., Dayton, OH 45432-1894 Tuesday, AM February 11, 1997
9:40am MICROSTRUCTURE AND TENSILE PROPERTIES OF ROLLED GAMMA TITANIUM ALUMINIDE: GopaZ Das, Pratt and Whitney, P.O. Box 109600, West Palm Beach, FL 33410-9600; Helmut Clemens, Plansee AG, Technology Center, A-6600 Reutte, Austria
Room: 330E Location: Orlando Convention Center
Gamma titanium aluminide (Ti-47 AI-2Cr-2Nb-0.2B, Ti-47 AI-2Cr-0.2Si at. %) sheets were produced by near-isothermal rolling of forged material. The microstructures resulting from annealing of the rolled sheets below and above the eutectoid temperatures were studied by a combination of optical, X-ray, SEM, and TEM methods. Transition temperatures including the alpha transus temperature were determined by DTA and annealing experiments. Textures were studied on as-rolled and annealed sheets. Tensile properties of annealed specimens were determined at RT-800°C. Deformation microstructure was analyzed by TEM and fractographs were studied by SEM. In the case ofTi47 AI-2Cr-0.2Si at. % the influence of strain rate on the ductile-to-brittle transition temperature was studied for different microstructures. Additionally, the superplastic behavior was investigated for Ti-47 AI-2Cr-0.2Si (at. %) sheet in the temperature range of lOOO-1100°C. The results will be presented and the underlying deformation mechanisms discussed. The Ti-47 AI-2Cr-2Nb-0.2B sheet material was provided by McDonnell Douglas and AFWLIMLLM and the portion of the work based on Ti-47 AI-2Cr-2Nb-0.2B sheet material was supported by NASA LeRC, Cleveland, OH, under Contract No. NAS3-26385.
Session Chairpersons: James C. Williams, GE Aircraft Engines, 1 Neumann Way, Evendale, OH 45215; Young-Won Kim, UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432
8:25 am OPENING REMARKS 8:30 am INVITED PROCESSING-PROPERTY-MICROSTRUCTURE RELATIONSHIPS IN TiAl-BASED ALLOYS: M H. Loretto, D. Hu, A. Godfrey, T.T. Cheng, I.P. Jones, P.A. Blenkinsop, IRC in Materials for High Performance Applications, The University of Birmingham, Edgbaston B15 2IT, UK A range of TiAI-based alloys has been produced by plasma melting either small buttons (lkg samples) or ingots (up to 50kg). These alloys have been subsequently processed using isothermal forging, extrusion and/or HIPping. Some problems associated with the melting and subsequent processing of these alloys will be discussed and the ways found to overcome these problems outlined. Microstructural data obtained from some of these alloys will be presented which show the relationship between processing route and microstructure, and these observations will be correlated with mechanical properties. It will be shown that the microstructure can be closely controlled by appropriate processing and further that for a range of alloy compositions the properties can be controlled more by processing than by composition. For other alloys the composition is more important.
10:00 am BREAK 10:20 am EFFECT OF EXTRUSION TEMPERATURE ON THE MICROSTRUCTURE OF A POWDER METALLURGY TiAl-BASED ALLOY: L.M. Hsiung, T.G. Nieh, Lawrence Livermore National Laboratory, P. O. Box 808, L-370, Livermore, CA 94551-9900; D.R. Clemens, Advanced Engineering Operations, Pratt & Whitney, West Palm Beach, FL 33410-9600 The microstructure of a PIM Ti-47AI-2Cr-1Nb-lTa (at.%) alloy powder-extruded at different temperatures has been studied. Three different temperatures: one near to the eutectoid temperature (T I ), one within the (ex +y) two phase field (T z), and one at a phase field (T3 ), were employed for the extrusion. The as-prepared powder consists of mainly a phase and small amount of supercooled ~1B2 grains and a fine-grained (y + a,) duplex structure. The observation of stacking faults coexisted with thin y plates within the a, grains reveals that stacking faults are intimately related to the formation of the g plates within the a, phase. A nearly fully lamellar (FL) structure composed of alternating y and a, lamellae is developed for the alloy extruded at T 3• Both lamellar grain size and lamellar interface spacing are finer than those in conventionally processed FL TiAI alloys.
9:00am DEFORMATION OF NANOCRYSTALLINE Ti-48AI: L.S. Kim, T. Klassen, C.J. Altstetter, R.S. Averback, Materials Science and Engineering Department, University of Illinois, 1304 W. Green St., Urbana, IL 61801 When the grain size is a few tens of nanometers, TiAI is ductile at moderately elevated temperatures. Such grain sizes were produced by ball milling of titanium and aluminum powders, which must be consolidated without excessive grain growth. Green compacts ( 80% dense) were sinterforged at temperatures near 650°C, achieving relative densities of 99%. The final grain
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10:40 am SUPER TRANSUS PROCESSING OF Ti-48AI-2Nb-2Cr ALLOYS: G.E. Fuchs, Lockheed Martin Company, P.O. Box 1072, Schnectady, NY 123011072
free autogenous (without filler metal) GTA welds have not been achieved. This paper will discuss the autogenous gas tungsten arc weldability of cast alloy Ti-48AI-2Cr- 2Nb (at. %) and of extruded alloy Ti-46AI-2Cr-2Nb-0.9Mo (at. %) and will compare their resultant fusion zone microstructure and properties. Samples were spot welded without any preheat. Microstructural characterization has been performed using optical microscopy and scanning and transmission electron microscopy equipped with an energy dispersive X-ray spectroscopy (EDS) system. Mechanical properties of the fusion zone will be discussed in terms of Vickers microhardness numbers and tensile testing.
Fine grained lamellar microstructures would be expected to exhibit high strength, high creep strength, high fracture toughness and moderate ductility. This presentation discusses the use of high temperature extrusion to produce fine grained lamellar microstructures in both ingot and powder metallurgy Ti-48AI-2Nb-2Cr alloys. The effect of processing parameters, such as extrusion temperature and cooling rate, on the microstructure and properties are examined. In addition, the thermal stability of the fine grained microstructures was examined by subsequent heat treatments. The results of this study indicate that fine grained lamellar microstructures can be generated in both ingot and powder metallurgy materials. However, the selection of the appropriate processing parameters is required to optimize the microstructure and properties.
GLOBAL EXPLOITATION OF HEAP LEACHABLE GOLD DEPOSITS III: Characterization of Refractory Ores and Evaluating Leachability Sponsored by: EPD Process Mineralogy, Precious Metals, Aqueous Processing Committees; Newmont Mining Corporation, Denver, CO Program Organizers: Donald M. Hausen, Consultant, 1767 S. Woodside Dr., Salt Lake City, UT 84124; David Dreisinger, University of British Columbia, Dept. of Metals & Materials Eng., 309-6350 Storres Rd., Vancouver, BC V6T 1Z4, Canada; Richard Kunter, Advanced Science, Inc., 405 Irvine St., Suite 401, Lakewood, CO 80278; William Petruk, CANMET, 555 Booth St., Ottawa, Ontario J1A 081; Richard D. Hagni, University of Missouri·Rolla; Dept. of Geology & Geophysics, Rolla, MO 65401
11:00 am DENSE IN SITU TiAI IMCS VIA PRESSURE-ASSISTED THERMAL EXPLOSION: I. Gotman, C. Zakine, E. Y. Gutmanas, Department of Materials Engineering, Technion, Haifa 32000, Israel Dense y -TiAI and in-situ TiAI based IMCs were fabricated via pressureassisted thermal explosion. Fine Ti-AI powder blends with and without the addition of BN or NiB were used as the starting reagents. Rapid heating to the ignition temperature of thermal explosion was realized via resistive heating or by placing the reagent compacts into a preheated pressure die. The presence of an additional low temperature phase in the composition with NiB greatly assisted the process of consolidation. The application of a moderate external pressure ($ 200 MPa) during processing was shown to be enough to accommodate negative volume changes associated with reactive synthesis and, thereby, to ensure full density of the final product. Microstructure and phase composition of the materials obtained were characterized employing x-ray diffraction and scanning and transmission electron microscopy (SEM and TEM) with energy dispersive analysis (EDS). The entire procedure of thermal explosion under pressure could be performed in open air without noticeable oxidation damage to the final product. Rapid cooling due to heat transfer into the pressure die allowed to prevent the coarsening of microstructure in the materials synthesized. The formation of a finely distributed reinforcing phase resulted in high mechanical properties of the in-situ TiAI matrix composites.
Tuesday, AM February 11, 1997
Room: 231C Location: Orlando Convention Center
Session Chairpersons: William Petruk, Consultant, Former Chief Mineralogist, CANMET, Ottawa; S.K. Chryssoulis, AMTEL, London, Ontario, Canada
8:30 am KEYNOTE TEXTURES OF GOLD MINERAL PHASES RELATED TO HEAP LEACHING: William Petruk, Consultant, Former Chief Mineralogist, CANMET, Ottawa, Canada KIA 00l Native gold and electrum are the main gold minerals recovered by heap leaching. Recovery depends on ore textures that influence exposure during crushing and grinding in preparation for heap leaching. Textures include gold-bearing veinlets along fractures and microfractures, and gold occurrences along grain boundaries. Small encapsulated gold grains in quartz, pyrite and arsenopyrite are not likely exposed, and generally non-recoverable. Similar submicroscopic forms of gold are not recoverable by heap leaching. Detailed studies have shown that many so-called encapsulated gold grains may occur either along weakly bonded grain boundaries or micro fracture in minerals, which become exposed by fine grinding. Ore textures in various ores will be reviewed. Ore types include gold in arsenopyrite-pyrite-quartz veins, goldchalcopyrite deposits, disseminated gold in sediments, Carlin-type gold ores, gold-pyrite associations, and gold in volcanogenic ores, etc.
11:20 am PROCESSING AND PROPERTIES OF INVESTMENT CAST, NEARBINARY TiAl ENGINE EXHAUST VALVES: Steven G. Dettloff, Wesley R. Thayer, Walter W Milligan, Department of Metallurgical and Materials Engineering, Michigan Technological University, Houghton, MI 49931 Near binary gamma TiAl engine valves were investment cast by the Hitchener process. Effects of IDP temperature, pressure and time on mechanical properties and microstructure were investigated, and the HIP process was optimized for ductility. A IDP + heat treat study was able to separate the beneficial contributions of porosity closure and microstructural development. Effects of iron additions on the optimum aluminum content were noted and will be discussed. We gratefully acknowledge the support of GM Powertrain, Ron Cafferty and Paul Mikkola, who provided the valves and financial support, as well as the National Science Foundation, under grant DMR-92-57465, which is monitored by Dr. Bruce MacDonald.
9:05am MINERALOGIC EVALUATION OF UNLEACHED GOLD IN BIOOXIDIZED LEACH RESIDUES: S.K._Chryssoulis, AMTEL, London, Ontario, Canada N6G 4X6; Rong Yu Wan, Newmont Metallurgical Services, Salt Lake City, UT 84108 Gold associations were established in a biooxidized, chlorinated CIL residue assaying 0.02 oz Ault and in a biooxidized thiosulfate leach residue assaying 0.01 oz Ault. Detailed Mineralogic study involved: assays of screened fractions; light microscopy; ion probe microanalysis to quantify 'invisible' gold in sulfide minerals; proton probe microanalysis to detect submicroscopic gold in chert; and laser microprobe analysis to detect and quantify preg-robbed gold. In the CIL residue most of the gold is preg-robbed (71 %). In the thiosulfate leach residue, gold occurs mainly as submicroscopic disseminations in microcrystalline quartz (chert). In both residues the 'invisible' gold in pyrite accounts for a minor fraction of the gold assay. Quantitative determination of the gold occurrence in the two residue samples established conclusively that gold adsorption on carbonaceous matter in the thiosulfate leach is of minor importance.
11:40 AM AUTOGENOUS GAS TUNGSTEN ARC WELDABILITY OF CAST ALLOY Ti-48AI-2Cr- 2Nb VERSUS EXTRUDED ALLOY Ti-46AI-2Cr2Nb-0.9Mo: v.L. Acoff, D. Bharani, Department of Metallurgical and Materials Engineering, Box 870202, The University of Alabama, Tuscaloosa, AL 35487-0202 In the majority of the engineering applications for which gamma based titanium aluminide alloys are being considered, fusion welding is the primary form of joining. Sound (crack and void free) welds using the gas tungsten arc welding (GTAW) process with matching, or near matching, filler metal have been accomplished. However, procedures for consistently producing crack-
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9:30am PROCESSING OPTIONS FOR HEAP LEACHING CARBONACEOUS SULFIDIC GOLD ORES: G. Ra17Uldorai, President, EnMetAssociates, Inc., 11225 E. Quick Draw Place, Tucson, AZ 85749-9551
HIGH TEMPERATURE SUPERCONDUCTORS III: veco Conductor Development
Sponsored by: Jt: EMPMD/SMD Superconducting Materials Committee Program Organizers: U. Balachandran, Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439; Paul J. McGinn, University of Notre Dame, Notre Dame, IN 46556
This paper addresses processing options for recovering gold from carbonaceous sulfidic gold ores. These include, but not limited to, the following methods: (I) Hypochlorite pretreatment followed by cyanidization; (2) Chemical blanking agents pretreatment followed by cyanidization; (3) Non-cyanide heap leaching techniques; (4)Biological pretreatment followed by cyanidization; (5) Biological pretreatment followed by non cyanide heap leaching. Issues of costs, economics, recoveries, testing methods, state of advancement etc., will be discussed in the paper.
Tuesday, AM February 11, 1997
Room: 315A Location: Orlando Convention Center
Session Chairpersons: P.J. McGinn, University of Notre Dame, Notre Dame, IN; J.L. MacManus-Driscoll, Imperial College of Science, Technology and Medicine, London, UK
10:00 am BREAK 10:10 am GEOLOGY AND CHARACTERISTICS OF GOLD MINERALIZATION IN FOUR SIBERIAN GOLD DEPOSITS, RUSSIA: A.D. Genkin, N.S. Bortnikov, Y.G. Safonov, IGEM, Russian Acad. of Sciences, Moscow, Russia; L.l. Cabri and G. McMahan, CANMET, 555 Booth St., Ottawa, Canada KIA OT!; CJ. Stanley, Natural History Museum, London, U.K; DJ. Fiedl, Physik-Dept., Technische Univ., Munchen, Germany
8:30 am INVITED EFFECT OF COMPOSITION ON GROWTH MECHANISM IN SEEDED-MELT PROCESSED YBa2Cu30 x : D. Shi, K Lahiri, S. Sagar, Dept. of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45221-0012 Single- and multiple-domain levitators of YBa,Cu 30, have been processed using the seeded melt texturing method. It has been found that the growth rate has varied depending upon the undercooling, the temperature gradient, and composition. A systematic study has been carried out to establish the relationship between the growth front velocity and composition, in particular the 211 concentration. For a given undercooling and temperature gradient, the growth rate of the domain can be strongly affected by the 211 density in the matrix. Evidences will be provided to show the important contributions of compositions and 211 morphology to the growth rates of center domain during the seeded melt texturing.
A multidisciplinary investigation (SIMS, EPMA, Mossbauer) was used to characterize gold in four Siberian mesothermal sulfide gold deposits: Olympiadnenskoe and Veduginskoe within the Enisei Mountain Range and Nezhdaninskoe and Sentachan in the Verchoyansk-Kolyma area. It was found that some of the mineralization is refractory in all four deposits, occurring in large part as "invisible" gold in arsenopyrite and a lesser amount in pyrite. The gold concentration and distribution vary considerably, both within and between grains of arsenopyrite, with implications for processing options, such as heap leaching. 10:35am AUGMENT X4 TECHNOLOGY FROM THE LAB TO FEASIBILITY; A CASE STUDY: KM. Schall, KA. Brunk, G.R. Maxwell, Augment Technologies, Denver, CO 80235
8:50 am INVITED EFFECTS OF Ce-BASED ADDITIONS ON THE MICROSTRUCTURE AND MAGNETIC PROPERTIES OF MELT TEXTURED YBa2Cu30 7.;;: P.l. McGinn, A. Banerjee, T. Meignan, Dept. of Chemical Engr., Univ. of Notre Dame, Notre Dame, IN 46556
Gold ores containing oxide copper incur significant cost penalties when leached with cyanide, because 4-5 moles of cyanide are consumed for each mole of leached copper. This equates to -4 Ibs of NaCN per lb of leached Cu. Total cost of excess NaCN consumption plus CN destruction can exceed $4.00 per ton of ore. AuGMENT Technologies has developed and demonstrated a new process that can: 1) economically recover 70-80% of cyanide fed to a mill; 2) produce salable copper cathodes; and 3) reduce the need for cyanide destruction facility. Standard resin processing and electro winning equipment are used to recover the cyanide and produce copper cathodes. Steps have been taken to determine: 1) how to develop resin kinetics, 2) how the AuGMENT Process can be scaled up;3) how much savings is incurred at mill site; and 4) how the novel 'electro-elution' circuit achieves efficient operation.
The effects of CeO, and BaCeO, additions on the microstructure and magnetic properties of melt textured YB~Cu,07_o (Y-123) have been investigated. Both types of additions are effective in reducing the coarsening ofY 2BaCuO, particles in the melt during texturing. Both additions also lead to improvements in the magnetic properties of Y-123 compared to samples without Cebased additions. The Ce-based additions are found to produce a "peak effect" in the magnetic hysteresis loop. The dependence of microstructure and magnetic flux pinning properties on the amount of Ce-based addition will be discussed. 9:10am GROWTH KINETICS OF MELT TEXTURED YBCO SUPERCONDUCTOR: V Selvamanickam, R.S. Sokolowski, Intermagnetics General Corporation, Latham, NY 12110; C.E. Oberly, Wright Patterson Air Force Base, Dayton, OH 45433; K Salama, Y. Zhang, S. Salib, Texas Center for Superconductivity, Houston, TX 77204
11:00am COPPER RECOVERY AND CYANIDE REGENERATION FROM CYANIDE SOLUTIONS: H. Soto and F. Nava, Dept. Mines and Metallurgy, Laval University, Quebec City, Quebec G IK 7P4 A method has been developed to recover cyanide and copper from heap leach cyanide solutions containing copper complexes and thiocyanate. Copper is precipitated as copper thiocyanate or copper cyanide, depending on pH and concentrations of thiocyanate and cyanide in effluents. Precipitates assaying over 50% Cu show good dewatering qualities and separate readily from effluents by filtration. Solutions containing bulk of cyanide are oxidized with ozone to transform remaining thiocyanate to cyanide, resulting in purified cyanide solution that can be recycled. The pH of the effluent is lowered to optimize precipitation and oxidation, and then raised to regenerate the cyanide. Recoveries are in excess of 96% of Cu and CN. Efficiencies of oxidation are 85-90%. Economic evaluation indicates a profitable process for solutions containing more than about 250 ppm copper. A bleed of barren solutions from cyanocidic gold/copper ores could be treated economically by heap leaching, since CN consumed by Cu could be regenerated at no cost.
The growth kinetics of YBCO superconductor have been studied by quench experiments during seeded isothermal melt-texturing. An undercooling of 15°C is found to be necessary to initiate nucleation of YBa 2Cu,o, following peritectic decomposition. A smooth transition is observed in the growth anisotropy with increasing undercooling, with the growth being faster along the caxis at low undercoolings (15 to 25°C) and faster along the a-b plane at high undercoolings (>25°C). Based on these findings, a modified melt-texturing process was developed, where, instead of slow cooling following melting, an isothermal hold was employed in the temperature range where the growth is isotropic. By this modification, the time required to texture 1" diameter disks was reduced to 15 hours which is about 4 to 5 times faster than a typical slow cooling melt-texturing process. Correspondingly, the same magnitude oflevitation force was achieved in a much shorter time in samples quenched during the modified process. Further, this process modification enabled a single do-
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M
main growth over the entire sample thickness of OS', which could not be achieved by the slow cooling process. This research was sponsored by the Air Force Office of Scientific Research.
10:40 am MACROSEGREGATION OF 211 PARTICLES DURING ZONE MELT TEXTURING OFYI23: H. Balwada, P.I. McGinn, Dept. of Chemical Engr., Univ. of Notre Dame, Notre Dame, IN 46556
9:30 am INVITED IDGH CRITICAL CURRENTS IN IDGH-ANGLE GRAIN BOUNDARIES IN YBCO SUPERCONDUCTOR: K. Salama, S. Sathyamurthy, A.S. Parikh, Texas Center for Superconductivity, 3201 Cullen Blvd., University of Houston, Houston, TX 77204-5769
The phenomenon of 211 particle pushing by the solidification front during zone melt texturing has been studied. In the presence of second phase additions of PtO, and BaCe0 3 , 211 particle refinement occurs. This refinement results in macroscopic segregation of 211 particles to the periphery of the sample rod. This phenomenon has been observed in samples textured with additions of PtO, (.2 wt% and .5 wt%) and BaCe0 3 (2 wt%) at speeds of 0.5 mmIhr and 1 mmIhr. Without additions to refine the 211, this phenomenon is not observed. It was also found that higher texturization speeds lead to multiple grain nucleation at the solidlliquid interface. Particle pushing continues to take place under these circumstances, as long as the growth mechanism does not become dendritic, in which case this phenomenon is not obseryed. Effects of various solidification parameters on the extent of211 particle segregation will be discussed.
A serious limitation to applications of YBCO superconductors is the presence of weak links in the form of grain boundaries. The high resistivity of YBCO grain boundaries is mainly attributed to the presence of solidified liquid phase and cracks at these boundaries. Using the liquid phase removal method, YBCO melt textured bars, over 10 cm in length and 0.5 cm' in crosssection, are processed with "clean" grain boundaries free of secondary phases and cracks. Bars processed by this method are found to consist of several large domains separated by clean grain boundaries. The bars are polycrystalline in nature with an average of 5 grain boundaries for every one cm in length. Using transport current measurements, the bars are found to carry currents in excess of 1000 Amps (current limit of source available) at 77 K and self field with very small voltage drop (20 to 50 IlV). Also, the same effect persists in the presence of external magnetic field up to 1.5 T at 77 K. Contrary to previous findings, the misorientation angles of grain boundaries in these samples are found to be significantly high, ranging between 30° and 80°. These results indicate that the high angle grain boundaries in these bars are capable of sustaining very large currents and therefore make them suitable for applications such as current leads and current limiters.
11:00 am INVITED MELT PROCESSING OF SCREEN-PRINTED ReBCO ON SILVER AT REDUCED TEMPERATURES AND OXYGEN PARTIAL PRES· SURES: 1.L. MacManus-Driscoll, N. Zafar, Centre for High Temperature Superconductivity and Dept. of Materials, Imperial College of Science, Technology and Medicine, Prince Consort Road, London, SW7 2BP, UK A thermodynamic approach has been applied to the processing of rare earth barium cuprate superconductors (ReBCO). Studies were made on various ReBCO thick films which had been screen-printed onto Ag substrates. Using a coulometric titration technique, thermodynamic studies and reduced temperature and pressure (RTP) processing methods were carried out the thick film samples of ReB COlAg. The parameters governing the melt processing of ReB COlAg were optimised with a knowledge of phase stabilities and phase relations with respect to both temperature and oxygen partial pressure. Furthermore, accurate control of the oxygen partial pressure enabled the determination of the phase chemistry and the crystal growth rates during processing.
9:50 am INVITED SEARCH FOR NEW SUPERCONDUCTING SYSTEMS RELATED TO THE INFINITE LAYER FAMILY COMPOUNDS: NORMAL PRESSURE SYNTHESIS AND THE ROLE OF DOPING: R. Cloots, S.U.P.RA.S., University of Liege, Chemical Institute B6, Sart-Tilman, B4000 Liege, Belgium; H. Bougrine and M. Ausloos, S.U.P.R.A.S., University of Liege, Physics Institute B5, Sart-Tilman, B-4ooo Liege, Belgium The aim of this paper is to report on investigations on the influence of alkali and rare-earth ions doping in Ca,.xSrxCuO, and Ba,CuP.Ci, (and related compounds), in particular on their synthesis conditions and crystallographic structures. We concentrate the attention on the possibility to induce a charge transfer mechanism between constitutive layers by impurity doping, leading to a possible insulating-metal (superconductor) transition. Electrical resistivity and thermoelectric power measurements are presented in order to verify a possible superconducting behavior.
11:20 am THE FABRICATION AND ANALYSIS OF BULK YBCO FOR USE IN AN INDUCTIVE FAULT CURRENT LIMITER: 1.P'G. Price,* S. A. L. Foulds,* T.e. Shields,* D. 1. Moule, P. D. Evans, J. S. Abell,* *School of Metallurgy and Materials, School of Electrical Engineering, University of Birmingham, Edgbaston, Birmingham, B 15 2IT, UK Fault current limiters (FCL) have the potential of becoming one of the first major applications for high temperature superconductors. To improve commercial confidence in high temperature superconductivity, it is imperative that superconductors are produced and tested in certain applications. In this work, melt processed YBCO rings have been produced for use in an inductive fault current limiter. Various dopants and thermal treatments are utilized to improve the mechanical, electrical, and magnetic properties of the material. Using the FCL, critical current density (Jc) measurements can be made. Several different arrangements of the components of the FCL and the limiting performance are outlined. Characterization of the material is performed using polarized light microscopy, scanning electron microscopy, and pulsed Jc measurements. The final aim of this work is to determine whether bulk YBCO is suitable for use in inductive fault current limiters.
10:10 am BREAK 10:20 am INVESTIGATIONS OF THE CHEMICAL COMPATIBILITY OF SUB· STRATES FOR 123 MELT·TEXTURED CERAMICS: F. Auguste, R Cloots, S.U.P.R.A.S., University of Liege, Chemical Institute B6, Sart-Tilman, B-4OOO Liege, Belgium; G. Moortgat, Centre de Recherche de l'Industrie Beige des Ceramiques, Avenue Gouverneur Cornez 4, B-7ooo Mons, Belgium; H. Bougrine, P. Clippe, M. Ausloos, S.U.P.R.A.S., University of Liege, Physics Institute B5, Sart-Tilman, B-4ooo Liege, Belgium The production of dense superconducting ceramics is affected by the thermal processing and parameters like the oxygenation process and the texture development. One of the serious problems which prevents the formation of useful REBa,CuP,.x-like bulk ceramics (RE =rare earth) for practical applications is the existence of weak links at the grain boundaries. Another annoying feature is that all usual containers or substrates for the growth react with the melt leading to a strong contamination of the "in situ" produced materials. The choice of the substrate is also very relevant for film growth. The cases of SrTi03, MgO, AIP3' and BaZr03crucibles for solution growth of single crystals of REBa,Cup, has been investigated for the production of long length fibers or other complicated shapes of bulk Y or RE-123 materials. The chemical compatibility of the "substrate" towards the Y or RE-123 mixture is reported at various melt-texturing growth stages. For comparison, we looked at three different materials: BaZr03, SrTi0 3 , and MgO.
11:40 am ADVANCES IN THE PROCESSING AND APPLICATIONS OF HIGH TEMPERATURE SUPERCONDUCTING FILMS: A. Gupta, M. Sisodia, RK. Yadava, Dept. of Metallurgical Engineering, Malaviya Regional Engineering College, J aipur 302 017, India High critical temperature (high-T) superconductors have captured the interest of engineers and scientists world wide. For its commercial utilization in the field of microelectronics and electronic systems, they must be fabricated into desirable configurations - thin and thick films. During studies, it has been observed that these superconducting thin films operating at liquid N, temperature offer great possibilities for faster, more sensitive and precise electronics devices. Present paper reviews the fabrication techniques of high-T,
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superconducting thin films which primarily includes pulsed laser deposition, molecular ion beam epitaxy, chemical vapor deposition (CVD) by using epitaxial growth on single crystal substrates (YSZ, MgO, Si, etc.) with excellent microstructural control and properties relationship. In addition to it, thick film fabrication is also discussed with major techniques like screen printing and plasma spraying along with associated processing parameters. Furthermore, advanced applications of each are enumerated at length.
9:30 am INVITED TRANSFORMATION OF THE AMORPHOUS TO THE NANO-CRYSTALLINE STATE: R. Luck, K. Lu*, Max-Planck-Institut fur Metallforschung, SteebstraBe 75, D-70174 Stuttgart, Gertnany, *also with National Laboratory for RSA, Institute of Metal Research, Academia Sinica, Shenyang 110015, China The crystallization of amorphous materials has been studied extensively during the last two decades. However, the fortnation of nanocrystals - that is a crystalline morphology with an average grain size of 5 to 50 nm - from t he amorphous state has been detected few years ago. Since that time it is used more and more. This procedure is perfortned isothertnally below the crystallization temperature. We present data of the kinetics of this process. The transfortnation has been monitored by the measurement of several physical properties; we have applied especially the measurement of magnetic susceptibility. Magnetic measurements are able to detect the onset of the transformation of amorphous Ni-P alloys much earlier than was possible with differential scanning calorimetry. The transfortnation kinetics can be analyzed by means of the Avrarni plot based on the Johnson-Mehl-Avrami equation. The kinetics of further solid state reactions in the nanostructured material can be investigated similarly.
HUME·ROTHERY AWARD SYMPOSIUM FOR BRUNO PREDEL: Thermodynamics of Alloy Formation II: Amorphous State Sponsored by: Jt. EMPMD/SMD Alloy Phase Committee Program Organizers: Prof. VA Chang, Department of Materials Science & Engineering, University of Wisconsin, Madison, WI 53706-1595; F. Sommer, MaxPlanck-Inslitut fur Metallforschung, Ins!. Fur Werkstowissenschaft, Seestrasse 92, 0-70174 Stuttgart, Germany
Tuesday, AM February 11, 1997
Room: 330B Location: Orlando Convention Center
10:00 am BREAK
Session Chairs: R. Schmid-Fetzer Technical Universitaet Clausthal, AG Elektronische Materialien, Robert-Koch-Str. 42, 0-38678 Clausthal-Zellerfeld, Germany
10:15 am INVITED THE EFFECT OF ORDER-DISORDER PHASE TRANSFORMATION ON VOLUME INTERDIFFUSION: E. Rabkin, B. Straumal, W. Gust, Institute fur Metallkunde and Max-Planck-Institut fur Metallforschung, Seestr. 75, D-70174 Stuttgart, Gertnany
8:30am THE SHORT- AND MEDIUM-RANGE STRUCTURE CHARACTERISTIC OF AMORPHOUS ALLOYS: K. Suzuki, K. Shibata, T. Otomo* and H. Mizuseki, Institute for Materials Research, Tohoku University, Sendai, Japan, *National Laboratory for High Energy Physics, Tsukuba, Japan
The volume interdiffusion has been studied in Fe-Si single crystals in the vicinity of A2-B2 ordering and in Cu-Au single crystals in the vicinity of AIL12 ordering. Decreased interdiffusivity rates were found, as expected, in the ordered Fe-Si alloys. In the Cu-Au alloys, however, the interdiffusivity in the ordered region is higher than it could be expected by extrapolation of the diffusivities in the disordered phase. Different approaches were used to calculate the thertnodynamic factor for interdiffusion, and the results obtained are in qualitative agreement with the experimental data. The influence of the variation of the partial molar volumes of the components during the phase transition on the calculated interdiffusivities is discussed.
Atoms in amorphous alloys are combined into a configuration of minimizing the local energy in the short-range structure instead of relaxing the total energy minimum of a system. The short-range order of amorphous alloys often shows similarity to that of their crystalline counterparts. The survival of the local coordination in amorphous alloys is also confirtned by the vibrational density-of-states. However, the medium-range structure of amorphous alloys has an quite unique nature in contrast to the crystalline alloys. The low-energy excitation in amorphous alloys appearing in the energy range of I to 3 meV, which is usually observed as an excess specific heat in addition to the Debye-type harmonic vibration, is contributed from the locally collective motion characterized spatially by the medium-range structure fluctuations. The experimental results mentioned above for Pd-Si, Pd-Ge, Pd-Ni-P and VNi amorphous alloys were observed by pulsed neutron scattering based on accelerators, which is a powerful tool for characterizing the structure of amorphous alloys, because a very wide dynamic range of energy- and momentumtransfer can be surveyed.
10:45 am INVITED THE METASTABLE STATE OF AMORPHOUS ALLOYS: R. Bormann, Institute for Materials Research, GKSS Research Center, D-21494 Geesthacht, Gertnany In the past, the thertnodynamic state of amorphous phases has been of great concern. Due to highly non-equilibrium preparation processes involving rapid quenching and condensation techniques it has been assumed that these alloys are frozen-in liquids where a thertnodynamic description cannot be applied. Recently however, the existence of a metastable state in single-phase and phase-separated amorphous alloys has been confirtned unambiguously by electromotive force (EMF) measurements and characterized by calorimetric and structural investigations. EMF measurements also allow the direct determination of the chemical potentials of the least noble component and thereby (for binary systems) the Gibbs energy of the amorphous phase. By means of thertnodynamic modeling, e.g. by the CALPHAD method, phase diagrams of metastable phases can be calculated for the amorphous phase. These can predict the amorphous phase fortnation during rapid quenching of the melt and during solid-state reactions. The results demonstrate that the fortnation of amorphous alloys is strongly determined by the thertnodynamics of the undercooled liquid and the amorphous phase.
9:00 am INVITED NEUTRON DIFFRACTION STUDIES OF LIQUID ZINTL-ALLOYS UP TO 2000: K.R. Winter, University of Dortmund, Department ofChemistry, Physical Chemistry I, D-44227 Dortmund, Gertnany Neutron diffraction measurements have been carried out on equiatomic liquid Zntl-alloys, such as KPb, CsPb, and NaSn, over a wide temperature interval, ranging from 800 to 2000 K, and at pressures up to 150 bar. In the crystalline state, these are semiconducting compounds containing tetrahedrally coordinated polyanions. The diffraction results indicate the survival of polyanions in the expanded liquid alloys even up to high temperatures, as indicated by the persistence of the peak of S(Q) at Q z lA-I, which is indicative of intertnediate-range order. The position of this peak shifts towards lower Q-values, its height decreases, and its width drastically increases with increasing temperature and correspondingly decreasing density. The experimental results and the corresponding real-space infortnation are compared with the crystal structures in the solid state and with the results of recent abinitio molecular dynamics calculations and computer modelling studies. In addition, we present neutron diffraction data on the effect of pressure on the structure factor of solid CsPb in the rotator phase.
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11:15 am INVITED THERMODYNAMIC CONSIDERATIONS IN THE RATIONALIZATION OF SOLID-STATE AMORPHIZATION BETWEEN METALS AND III-V SEMICONDUCTORS: Y.A. Chang, Department of Materials Science and Engineering, University of Wisconsin, Madison, WI 53706; EY. Shiau, Trace Storage Technology Corp., Hsinchu, Taiwan, China; S.-L. Chen, CompuTherm LLC, Middleton, WI 53562; S. Mohney, Department of Materials Science and Engineering, Penn State University, University Park, PA 16802
8:55am FREEZE DRYING SYNTHESIS OF OXIDE POWDERS: A STEP TO POWDER ENGINEERING: O.A. Shlyakhtin, v.v. Ischenko, O.A. Brylev, N.N. Oleinikov, Department of Chemistry, Moscow State University, 119899 Moscow, Russia Spray freezing of multi component aqueous solutions followed by freeze drying leads to formation of homogeneous salt powders with stable and extensive porous structure. The influence of specific microstructure on the properties of fine powders obtained by thermal decomposition of these precursors remains underestimated. Indeed the decomposition of the native freeze dried salt precursor resulted in the formation of single phase LiCo02 at T=300'C while breaking the aggregates before decomposition led to multiphase product. In the other case carefully controlled influence on the microstructure of the intermediates allowed us to accelerate 3-5 times the rate of grain growth during annealing of Fe,03 and BaZr03 fine powders.
In addition to binary metal/metal systems, solid-state amorphization reactions have been reported to occur in numerous ternary Ill-V semiconductorl metal systems such as GaAslNi, GaAs/Co, InPlNi, InPIPd, InP/Co and InP/ Pt. In this presentation a thermodynamic argument will be presented first to rationalize the occurrence of an amorphous phase in a model binary system. This argument will be used next to rationalize solid-state amorphization in III-V semiconductor/metal systems focusing on the GaAs/Co case. In this system, sufficient thermodynamic information is available.
9:20am FRONTIERS IN PREPARATION OF SI3N4 POWDER BY RFPCVD: Rioyu Hong', Guoliang Zheng', Hongzhong Li', and Jianmin Ding2. 'Inst. of Chern. Metallurgy, Chinese Academy of Sciences, Beijing 100080, China; 2Energy Research Corp., 3 Great Pasture Road, Danbury, CT 06813
INTERNATIONAL SYMPOSIUM ON PROCESSING AND HANDLING OF POWDERS AND DUSTS III: Ceramic Powder Production
Radio frequency plasma chemical vapor deposition (RFPCVD) method is used to prepare ultrafine Si3N4 powder on a large scale. The characteristics of the RFPCVD method are given. It is pointed out that there are three kinds of mathematical models for the RF plasma generator and RFPCVD reactor: thermodynamic, hydrodynamic, and aerosol dynamic models with respective features. Research work on theoretical and technical studies for the preparation of ultrafine Si3N4 powder are given in detail. At last, the existing problems of the RFPCVD technology are given: (1) The thermodynamic, hydrodynamic and technical studies should be combined together. (2) Hydrodynamic modeling should be made for the RF plasma generator and CVD reactor simultaneously. (3) The improvements for preparing the Si3N4 powder should be combined with the aftertreatment of the product and also should be related to its sintered properties. (4) The improvements of the Si3N4 ceramic should be combined with the preparation of composite ceramics or surface modification of Si3N4 particles.
Sponsored by: Jt. EPDIMDMD Synthesis, Control, and Analysis of Materials Processing Committee, Powder Metallurgy, Reactive Metals, and Non-Metallic Materials Committees Program Organizers:Thomas P. Battle, DuPont, Edgemoor, DE 19809; Hani Henein, University of Alberta, Edmonton, AL; Gordon Irons, 1280 Main St West, Hamilton, Ontario L8S 4L7; John Moore, Colorado School of Mines, Dept. of Met and Mails, Golden, CO 80401; Beverly Aikin CWRU - NASA LeRC, 21000 Brookpark Road, MS 106-5, Cleveland, OH 44135; Iver Anderson, Ames Laboratory, Iowa State University, 122 Metals Development Bldg, Ames, IA 500113020; John Pusateri, Horsehead Resources Development, Monaca, PA
Tuesday, AM February 11, 1997
Room: Salon 6 Location: Clarion Plaza Hotel
9:45 am BREAK
Session Chairs: John Moore, Dept. of Met and Matis, Colorado School of Mines, Golden, CO 80401-1887; Iver Anderson, Ames Laboratory, Iowa State University, 122 Metals Development Bldg, Ames, IA 50011-3020
10:00 am PREPARATION OF COMPOSITE PARTICLES BY RAW MATERIAL SOLUTION INJECTION: Hiroyuki Nakamura*, Yun-Fa Chen+, Kunio Kimura*, Hiroshi Tateyama*, Hideharu Hirosue*. *Kyushu National Industrial Institute Japan, +Institute of Chemical Metallurgy, China
8:30am CHEMICAL SYNTHESIS AND PROCESSING OF NANOSTRUCTURED ALUMINUM NITRIDE POWDERS: G.M. Chow', L.K. Kurihara'·2, R. Rayne 3, L. S. Choi4, P. E. Schoen', Naval Research Laboratory, Washington, DC 20375; M.1. Baraton, Laboratory for Ceramics and Surface Treatment, University of Limoges, France; 'Laboratory for Moelcular Interfacial Interactions, Code 6930/Center for BiolMolecular Science and Engineering. 2also at Department of Biochemistry, Georgetown University, Washington, DC; 3Materials Science Division; 'Chemistry Division
Composite particles, which are expected as raw materials for composite, are often prepared by alkoxide method or homogeneous precipitation method. However, using these methods, it seems to be rather difficult to control structure of the coating layer (ex. multi-layered, homogeneously mixed, graduated layered). From this point of view, the presenters tried to prepare composite particles by injecting raw material solution into a dispersion of core particles (diameter: micro meter order). The presenters believe that this method will make it easier to control the structure of coating layer. In this presentation, preparation of alumina-hydrate coated SiC whiskers is investigated. We used SiC whiskers as core particles and aluminum salt (nitrate, chloride, sulfate) solution as raw material solution, relationships between preparation conditions (injection speed, concentration of core particles etc.) and morphology of coated particles were explored. Moreover, application of this method for preparation of double-layer coated particles will be presented.
Nanostructured ceramic AIN materials are fabricated using chemical routes. The precursor powders of aluminum hydroxide are synthesized by hydrolysis of aluminum tri sec butoxide. These precursor powders are calcined and subsequently transformed to nanoscale AlN powders by nitriding in an ammonia environment furnace at temperatures to 11 OO°C. The AIN powders are consolidated to green bodies by cold isostatic pressing. The green bodies are sintered in a nitrogen furnace for densification. Characterization techniques include XRD, TEM, HRTEM, DSC, and surface FTIR. The effects of solvent, pH on the control of particle size, particle size distribution and agglomeration are addressed.
10:25 am REACTIVE SYNTHESIS OF CERAMIC POWDERS: John J. Moore, Dennis W. Readey, Dept. of Met. and Matis Engr., Colorado School of Mines, Golden, CO 80401-1887 Reactive synthesis has been used to synthesize a number of different ceramic powders, such as TiB 2, SiC, Si3N4. This paper will discuss the effect of reaction parameters, e.g., type of synthesis reaction, exothermicity of reaction, reactant particle size, reaction temperature and time, on the control of the size of the product powder, product yield, chemistry and purity.
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10:50 am
also gives a Re0 3phase, II and III give a pseudocubic phase with Re1.,M,O, composition (M=Mo, x ~ 0.25), while IV provides spherical amorphous particles (-1 ~m size) of rhenium metal. The reduction ofl-III in hydrogen atmosphere leads to formation of single-phase metal product (with the a-phase alloy structure) at the temperature about 300-400°C.
SYNTHESIS OF ALUMINUM NITRIDE POWDERS USING DCPLASMA PROCESSING: Paul Prichard, Matthew Besser, Daniel Sordelet, Iver Anderson, Ames Laboratory (USDOE), Iowa State University, Ames, IA 50011-3020
8:50am
Experiments were performed to synthesize AIN powders by reacting Al with N using a conventional dc-plasma as a heat source. Attempts to form AIN powders by feeding Al powder into a nitrogen-rich plasma open to the atmosphere produced mainly aluminum oxide. Subsequent experiments were run inside a chamber which was backfilled with nitrogen. The nitrogen environment suppressed the formation of aluminum oxide, but little AIN was formed by using Al powder as the feedstock material. A furnace and crucible assembly was designed to feed molten Al directly into a convergent nozzle positioned directly at the face of the dc-plasma gun. Powders formed using this arrangement show a significant increase in the level of AIN formation. The presence of AIN was verified by chemical analysis and X-ray diffraction. Results were dependent upon chamber pressure, plasma velocity and molten liquid feed rate. The experimental parameters, equipment design and results will be reported in detail, and a suggested reaction mechanism will be discussed.
SOFT CHEMISTRY ROUTE TO RHENIUM-BASED MATERIALS: Y.G. Kessler, Moscow State University; Moscow, Russia; G.A. Seisenbaeva, D.Y. Drobot, Moscow State Academy of Fine Chemical Technologies, Pro Vernadskogo 86,117571 Moscow, Russia The so called soft chemistry approach is usually based on hydrolytic or pyrolytic decomposition of the complexes of metals with organic ligands. The methoxides of rhenium (I), rhenium and molybdenum (II) and rhenium and tungsten (III) were prepared by anodic oxidation of rhenium metal in methanol in the presence of LiCI as electrolyte and methoxides of countermetals. Acetylacetonate, Re,o,(acac)2 (IV) was obtained by interaction ofre,07 and Hacac in toluene. I and III are insoluble in common organic solvents and air stable in contrast to highly soluble and air and moisture sensitive II. IV is insoluble in hydrocarbons and dissolves in ethers with decomposition. All these compounds are volatile at reduced pressure and decompose in inert atmosphere into mixed low-valent oxides or, in case oflY, into rhenium metal.
11:15 am MECHANOCHEMICAL SYNTHESIS OF ULTRAFINE CERAMIC POWDERS 1. Ding, T. Tsuzuki, P.G. McCormick, Research Centre for Advanced Mineral and Materials Processing, The University of Western Australia, Nedlands, Perth, WA 6907, Australia
9:10am REDUCTION OF AMMONIUM PERRHENAT TO METAL RHENIUM: V.P. Seleznev, D. Mendeleev, University of Chemical Technology of Russia, Miusskaya Sq. 9, Moscow 125047, Russia
The synthesis of ultrafine alumina and zirconia powders by mechanochemical reaction has been investigated using x-ray diffraction, TEM and DSC measurements. Mechanical milling of AICI 3 or ZrCI. with CaO resulted in nanoscale mixtures of the starting phases, with no evidence of the occurrence of any reaction during milling. The formation of separated 10-20 nm particles of g-AI,03 within a CaCl, matrix occurred after heat treating the asmilled AICllCaO mixture above 350°C. Cubic zr02' particles 5-10 nm in diameter, were formed after heat treatment above 300°C. With both reactions, removal of the CaCI, by-product phase was carried out using an appropriate solvent. Measurements of the effect of heat treatment temperature on crystal structure and particle size will be reported.
Ammonium perrhenat was dissolved in organic solvent (the mixture of amide and carboxylic acid) and heated to 60-80°C. Reduction starts after addition of active metal as an initiator in amounts less than stoichiometric. Amorphous metallic rhenium is the product of reduction. Various amides and carboxylic acids as the components of organic solvent for ammonium perrhenat and their volume proportions were investigated. The possibility of ammonium perrhenat reductioin to metal by gaseous organic compounds such as amides and alcohols was also shown.
9:30am BINUCLEAR RHENIUM CLUSTERS AS A BASIS FOR METAL COATINGS AND NEW FUNCTIONAL MATERIALS: A.Y. Shtemenko, Ukrainian State University of Chemical Technology, Gagarin Av. 8, Dniepropetrovsk 320005, Ukrainia
INTERNATIONAL SYMPOSIUM ON RHENIUM AND RHENIUM ALLOYS III: Chemical Processing of Rhenium Compounds and Catalysts
Thermal behaviour of binuclear halogenated and halogencarboxylated Re26+ clusters, synthesized according to elaborated procedures, is studied. It is shown, that the last stage of thermal distribution of the substances in vacuum or inert atmosphere is formation of metal rhenium with content of contaminants 0,0010,01%. Method of obtaining of composite material of "metal-oxide" type is elaborated, providing the best combination of thermophysical and mechanical properties in wide temperature intervals. Density of rhenium framework of the material approaches to that of theoretical and microhardness of 250260 kg/mm2.
Sponsored by: SMD Refractory Metals Committee and MDMD Powder Materials Committee Program Organizer: Dr. Boris D. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036 Tuesday, AM February 11, 1997
Room: 232C Location: Orlando Convention Center
9:50am
Session Chairperson: Prof. Dr. D. V. Drobot, Moscow State Academy of Fine Chemical Technologies, Pro Vernadskogo 86, 117571 Moscow, Russia
THE CATALYTIC PROPERTIES OF SUPPORTED RHENIUM AND RHENIUM HEPTASULFIDE: Margarita A. Ryashentseva, Zelinski Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow, Leninsky prospect 47, Russian
8:30am NANOSCALE RHENIUM OXIDE AND ALLOY POWDERS FROM ORGANIC PRECURSERS: G.A. Seisenbaeva, D.Y. Drobot, Moscow State Academy of Fine Chemical Technologies, Pro Vernadskogo 86, 117571 Moscow, Russia; Y.G. Kessler, Moscow State University; Moscow, Russia; M. Sundberg and M. Nygren, Arrhenius Laboratory, University of Stockholm, Sweden
The catalytic properties of supported rhenium were widely investigated in the reactions of de, hydrogenation, hydrogenation of hydrocarbons and reforming of petrol fractions. Lowpercentage bimetallic supported catalysts containing rhenium and palladium have been developed. A world first publication of these results were in 1960's - a little bit earlier than known Pt - Re reforming catalysts. An effective catalyst, rhenium heptasulfide has been found in the chemical synthesis of S - and N - containing heterocycles compounds. It is a specific selective catalyst for the hydrogenation of the pyridine ring without affecting the benzene ring in aryl-substituted pyridines, including those containing silicon, isoquinolines, annelated pyridine and condensed aromatic compounds. The process of hydrogenation in the presence of alcohols is going on along with N - alkylation on rhenium heptasulfide. Selective hy-
The thermal decomposition of the organic derivatives of rhenium (Re.olOMe),6 (I), ReMo02(OMeh (II), Re..,W,02(OMe)16 (m), Re,05(acac), (IV)) in air at temperatures below 400°C leads in case of I, III and IV to the oxide powders containing fine particles (40-60 A) with Re0 3 type structure included into amorphous matrix, while in case of II a mixture of Re0 3 and MoO l phases was obtained. In an inert atmosphere (N2' Ar) at 300-400°C I
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the used of WMS, IR, ESR, NMR and kinetic spectroscopy methods were revelated. Effective analytical systems were discovered on the basis of these investigations. Perspective methods of optical and potentiometrical sensors, catalytic methods for cone. of alkaline and acid medias with detection hmit down to 0.001 IlgRe/ml, coulometric method for mg Re determination, ICPAES, luminescence, thermochromatographical, spectrophotometric, ESR and other methods were developed. Some of them are in use as FIA detectors. New sorbents, watersoluable polymers with membrane flItration, electrodialysis and electro migration appeared to be the base for effective isolation and preconcentration of Rhenium. Express-testing methods, based on the catalytic properties of "unusual" state of oxidation Rhenium - Re (VI), were created and applied for analytical control on several manufactures (limit of detection up to 0.001 Ilg/ml). The developed methods comprise the basis of analytical control during the reworking of Rhenium-containing ores, technological rests, waste Re-Pt catalysators, volcanic products from Kurila Islands, being used in field conditions, and also for geochronology by Re/Os isotop ratio.
drogenation of various number of physiologically active substances, containing a pyridine ring could afford some alkaloids and their analogs. 9:50 am BREAK 10:10 am CHEMISTRY OF BINUCLEAR RHENIUM CLUSTERS: A.V. Shtemenko, B.A. Bovykin, Ukrainian State University of Chemical Technology, Gagarin Av. 8, Dniepropetrovsk 320005, Ukrainia Binuclear rhenium clusters are the first examples of inorganic substances, which contain multiple metal-metal bond, that is the reason of some special (unique) properties of these compounds. Mechanism of formation of Re 3+ clusters is thoroughly studied by us that became the base of elaboration of new technological methods of synthesis of different types of binuclear Re26+ clusters. On the base of accomplished investigations the perspective of binuclear rhenium clusters application is shown as precursors for obtaining of rhenium and new inorganic materials on it's basis, catalysis and promotors of catalytic systems among them. 10:30 am SOLID STATE CHEMISTRY OF RHENIUM HALOGENIDE AND OXIDES: D.V. Drobot, Moscow State Academy of Fine Chemical Technologies, Pr. Vernadskogo 86,117571 Moscow, Russia; M.B. Varfolomeev, Institute of the Chemical Problems of Microelectric, Pr. Vernadskogo 86, 117571 Moscow, Russia
LIGHT WEIGHT ALLOYS FOR AEROSPACE APPLICATION IV: Session III: Composites Sponsored by: SMD Non·Ferrous Metals Committee Program Organizer: Eui W. Lee, W.E. Frazier, Code 4342, Naval Air Warfare Center, Patuxent River, MD 20670; K. Jata, WUMLLM, WPAFB, OH 45433; N.J. Kim, Center for Advanced Aerospace Materials, POSTECH, Pohang, 790-784, Korea
Results of the investigations of the phase equilibriums in the systems Re-OHal (Hal = Cl, Br, I) individual phases M(ReO')3 (M = metals of the III group) in systems Re-O-M and corresponded crystallohydrates M(ReO')3nH,0 (n 3; 4; 4,5 and 8) are discussed. By experimental dates P-T-x diagrams of binary systems are obtained and it is shown that oxohalides Re20.CI, (Hal = CI, Br) can be obtained. By means of vapour pressure measurements thermodynamic dates for sublimation and vaporisation processes of individual phases are obtained. Thermostability of ReI3., and lower rhenium iodides is investigated. The processes of chlorination of Re(IV) and Re(VI) oxides are investigated. Total results are the importance for CVD processes and technology of Re compounds purification. The methods of controlled synthesis Re03, ReHal" ReO)falx' M(ReO.)3 and M(ReO.)3 nH,O are described. Crystall structure and thermal stability of M(ReO')3 and M(ReO')3 nH20 are investigated. It is shown that crystal! structure of M(ReO4)3 nH20 depends on the size of ri forM3+.
Tuesday, AM February 11, 1997
=
Room: 330A Location: Orlando Convention Center
Session Chairperson:J.E. Benci, Wayne State University, Dept. of Materials Science and Engineering, Detroit, MI 48202
8:30am DEFORMATION BEHAVIOUR OF 7075AII SiCP COMPOSITE DUR· ING MULTI·PASS DEFORMATION AT HIGH TEMPERATURES: A. Razaghian, D. Yu, T. Chandra, Department of Materials Engineering, Wollongong University, Wollongong, NSW, 2522, Australia
This report presents the results of studies the process of electrodialysis of rhenium-containing solutions. It contains experimental data obtained by studying transport of rhenium and impurity elements through different membranes and selection of optimal electromembrane system, electrode materials and ion-exchange membranes. The received data have allowed to develop methods of electrodialysis conversion of potassium perrhenate to superpure ammonium perrhenate and preparation of highpurity concentrated perrhenic acid by treatment of contaminated salts. It is found that the method of electrodialysis is very efficient for recovery of rhenium from complicated sulphuricacid solutions containing molybdenum, iron, zinc, lead and other elements. The described methods are successfully used at Russian enterprises.
Hot deformation behaviour of 7075 aluminium alloy containing 15 vol% of SiC particles (average size of 14 am) and the monolithic alloy was studied at 300 and 400°C at constant strain rate ofls-l under condition of uniaxial compression. The effect of delay between two consecutive passes on the high temperature mechanical strength and microstructural development was examined. The results showed that the fractional softening (%FS) increased in both reinforced and monolithic alloys when the deformation temperature increased from 300 to 400°C, but monolithic alloy showed a slightly higher FS compared to composite under identical deformation conditions. TEM examination revealed that the monolithic alloy and composite contained almost similar substructures after either single or double pass deformation at a given temperature irrespective of interpass hold time. However, some subgrain growth was observed in these materials during holding after deformation at 400°C, but this was not the case at 300°C. The absence of subgrain growth at lower temperature can be attributed to pinning effect by fine dispersions present in the matrix. The structural study also showed that static recrystallization did not occur in these materials during hold time between passes, and the fractional softening occurs mainly due to static recovery.
11:10 am PROGRESS IN ANALYTICAL CHEMISTRY OF RHENIUM: Ludmilla V. Borisova, v.1. Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 117975 Moscow, Kosygin Str. 19, Russia
8:55am WEAR PROPERTIES OF PARTICULATE REINFORCED ALUMI· NUM ALLOYS: Yeang-gi Cha, Su-young Kim, Ikmin Park, Kyung-mox Cho, Dept. of Metallurgical Eng. Pusan National University, Pusan 609-735, Korea
Rhenium speciations in various solutions, which are important for process and analytical chemistry have been studied for many years. Model systems, containing Rhenium, different ligands and reductors, equilibrium diagrams of Rhenium compounds were studied. Analytical forms of Rhenium compounds and their properties (oxidative-reductive, complexability, catalytical and etc.), their composition, structure, mechanism and reaction kinetics with
Wear properties of cast AI-SiCp composites were characterized under dry and lubricated conditions. Wear tests were performed employing biock-on-roller type and pin-on-disk type machines. Test conditions including applied load, sliding speed and sliding distance were changed for wear tests. Wear behavior was investigated by analyzing worn surfaces and debris, mainly as a function of the sliding speed. Results show that there exist transi-
10:50 am USAGE OF ELECTRODIALYSIS METHOD FOR PREPARING HIGH-PURITY RHENIUM CHEMICAL COMPOUNDS: A.v. Elutin, M. V. Istrashkina, Z.A. Peredereeva, State Research Centre-State Institute of Rare Metals-GIREDMET, 5 B. Tolmachevsky Per., Moscow 109017, Russia
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tion speeds at which the minimum wear rate occurs for both dry and lubricated conditions. However the appearance of wear transition is not well defined for the lubricated wear. It was found that SiCp reinforcement affects wear at the low sliding speeds and the softening of Al matrix dominates wear at the high sliding speeds. Main wear mechanism is abrasive wear although some amounts of adhesive wear are observed especially at the high sliding speeds.
forced with fibers annealed at low temperatures. On the other hand, the composite with fibers annealed at higher temperatures had improved tensile strength, and showed much smaller dimples around the fibers and relatively less fiber pull-out. In-situ SEM fracture study was performed to understand the micro fracture-process of the composite. 10:35 am THE INFLUENCE OF SOLUTIONIZING TIME AND TEMPERATURE ON THE BONDING CHARACTERISTICS AND MICROSTRUCTURES BETWEEN THE PARTICLES AND MATRIX IN COMPOSITES WITH 6061 AND 2014 ALLOYS REINFORCED WITHALUMINA PARTICLES: Daniel Salas, Javier Ponce, Erica Corral, S.K. Varma, Department of Metallurgical and Materials Engineering, The University of Texas at El Paso, El Paso, TX 79968-0520
9:20am FATIGUE CRACK GROWTH BEHAVIOR OF DIE-CAST AND CAST SiC PARTICULATES REINFORCED ALUMINUM COMPOSITES: Song-Hee Kim, Iee-Jeoung Kim, Department of Materials Engineering, Kangwon National University, Chunchon, Kangwondo, Korea, 200-701 The fatigue crack growth rate (FCGR) of SiC particulates reinforced aluminum matrix composites containing 10vol.% and 20vol.% of SiC fabricated by the casting and the die-casting processes have been studied over a wide range of stress intensity factor for various load ratios. The effect of volume fraction of SiC on FCGR was also investigated for the die-cast and cast composites. Fracture toughness was found to affect the fatigue crack growth behavior at the higher level of stress intensity factor range; however, at lower level, fatigue crack roughness related with the volume fraction of SiC reinforcement was more responsible for the fatigue crack growth. Die-cast composite with 20vol.% of SiC showed the superior fatigue crack propagation resistance at the lower level of AK, but the inferior resistance at the higher level of AK due to the decreased ductility and fracture toughness.
The influence of solutionizing time and temperature on the microstructural development and bonding characteristics between the matrix and the particles will be characterized in composites with 6061 and 2014 aluminum alloys reinforced with 0.10, 0.15 and 0.20 volume fractions of Ai20 3 particles (VFAP) solutionized at 520, 530, and 540°C for different times up to 20 hours to produce various grain sizes after quenching. The different heat treated samples after solutionizing v,lill be SUbjected to room temperature tensile fracture at various strain rates (attainable in an Instron tensile testing machine) and the fracture surfaces will be characterized by SEM and related to the UTS. The samples deformed to various true strains will be analyzed in the TEM to determine the influence of solutionizing time on the microstructural development during the deformation. The results on the composites will be compared with similar treatments performed on the alloys in their monolithic forms in order to determine the deformation mechanisms in the composites. This research has been supported by the National Science Foundation through the grant number HRD-9353547.
9:45am HIGH STRAIN RATE SUPERPLASTICITY OF DISCONTINUOUS FIBER REINFORCED PUR ALUMINUM COMPOSITES: Tsunemichi Imajl, Sumito Kojima', Isao Tochigi3, Gilles L'Esperance4, Bande Hong3, Daming Jiang'; I National Industrial Research Institute of Nagoya, 1 Hiratecho, Kita-ku, Nagoya 462, Japan; 'Nagoy Minucipal Industrial Research Institute, 4-3-4 Rokuban-cho, Atsuta-ku, Nagoya 456, Japan; 3Ecole Poly technique de Montreal, PO Box 6079, Station "A", Montreal (Quebec) Canada; 4Harbin Institute of Technology, Harbin 150001, China
11:00 am HOT DEFORMATION BEHAVIOR OF (SiCw+SiCp)/AA2124 COMPOSITES: feon-Chul foo, Byung-Chul Ko, and Joon Park, Department of Metallurgical Engineering, Inha University, Inchon 402-751, Korea
High Strain Rate Superplasticity (HSRS) of metal matrix composite has a great potential to apply to components and structures in automobile and aerospace industries and even semi-conductor packings since the composites exhibits excellent mechanical, physical and thermal properties. IN90 pure aluminum (AI) alone and AlNIlN90 pure Al composite made by PM method, and ~-Si3N4w/99.99% pure Al composite fabricated by squeeze casting were hot-rolled after extrusion and the superplastic characteristics were investigated to clarify the deformation mechanism. IN90 Al alone hot-rolled about 773K could produce the m value of more than 0.3 and 300-450% at the strain rate of about 0.0Is· 1 and at 913-923K and also has threshold stress in the strain rate less than O.Ols·l. ~-Si3N4w/99.9% pure Al composite exhibits the m value of 0.47 and the total elongation of about 200% at the strain rate of 0.5s· 1 and at 903K. The results indicate that the HSRS could occur by grain boundary sliding without interfacial sliding at liquid phase, because the optimum temperature to produce the HSRS is just below incipient melting temperature.
The hot deformation behavior of 15 vol. % (SiC w + SiCp ') reinforced AA2124 composites was investigated by hot torsion tests. The AA2124 Al based composites with different volume fractions of SiCw and SiC p reinforcements were fabricated by the powder metallurgy. Detailed analyses of flow curves and deformed microstructures were made to identify the hot restoration mechanism, such as dynamic recrystallization or dynamic recovery. Also, the dependence of flow stress and ductility on temperature and strain rate was studied. From the flow curves and microstructures of the hot deformed composites, it has been found that dynamic recrystallization was responsible for the hot restoration of the composites. The flow stress of the hybrid composites was higher than that of the monolithic AA2l24 alloy. The flow stress and ductility of the hybrid composites were investigated with respect to the ratio of SiC w and SiC p , reinforcements. 11:25 am ANALYSIS OF RESIDUAL STRESSED IN Ti-ALLOY, SCS-x MMC's BYNANOINDENTATION: K.L. Kendig l.', R. Gibala l, D.B. Miracle3, B.S. Majumdar3; IDepartment of Materials Science and Engineering, University of Michigan, Ann Arbor, MI; 'Materials Directorate, Wright Laboratory, Wright-Patterson Air Force Base, OH; 3UES Inc., Dayton, OH
10:10am FRACTURE BEHAVIOR OF COBALT COATED Al,03SHORT FIBER REINFORCED 2024 Al COMPOSITE: K.H. Baik*, E.S. Lee, and S. Ahn, Advanced Materials Division, Research Institute of Industrial Science and Technology, San 32, Hyojadong, Pohang, Kyungbuk 790-330, Korea; *Dept. of Materials Science, Oxford University, UK
Knowledge of variation of residual stresses aids in prediction of composite deformation and failure. Hardness measurements with high spatial resolution using extremely low load indentations, such as by nanoindentation techniques, may be an indicator of such variation of residual stresses. In this work, nanoindentation was used to determine hardness as a function of radial position from a fiber for a Ti6AI-4V, SCS-6 SiC fiber composite and a Ti-15V3AI-3Cr-3Sn, SCS-O SiC fiber composite, each in the as-consolidated condition. Residual stress predictions from a finite element model were compared to the hardness distributions obtained by nanoindentation. A small difference in nanoindentation hardness was found between the two phases of the Ti6AI-4V matrix in the Ti-6AI-4V, SCS-6 composite, which likely masked any effects of residual stress on hardness. The Ti-15V-3AI-3Cr-3Sn, SCS-O system was chosen to avoid this complication and to allow more direct correlation between predicted residual stress and nanoindentation hardness.
The effect of chemical reaction at coating/fiber interface on the fracture behavior of 2024 Al alloy reinforced with Co coated Al,03 fibers were investigated. AI,03 fibers were coated with metallic Co by sol-gel process using Co acetate compound. The coated fibers were annealed at temperatures ranging from 300 to 1000°C in vacuum to generate interfacial reaction between the Co coating and the AlP3 fiber. Regardless of the annealing temperatures, a fair amount of solute Co was detected near the Al,03 fiber surface ensuring the good bonding between the coating and the fiber. AlgCO, and CO,03 phases were formed at high annealing temperatures. SEM fractography of the composite showed the change of fracture behavior as a result of the interfacial reaction. Fiber debonding was frequently observed in the composite rein-
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LOW ENERGY PROCESSES IN ELECTRONIC MATERIALS: Energetic Beam I: Deposition and Synthesis
MATERIALS, COATINGS AND PROCESSES FOR IMPROVED RELIABILITY OF HIGH TEMPERATURE COMPONENTS III: Coatings and Oxidation Coatings
Sponsored by: EMPMD Thin Films and Interfaces Committee Program Organizers: Rajiv K. Singh, University of Florida, 317 MAE, PO Box 116400, Gainesville, FL 32611-6400; O.w. Holland, Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831; Steve Pearton, University of Florida, 343 NSC, PO Box 116400, Gainesville, FL 32611-6400; Roy Clarke, Department of Applied Physics, University of Michigan, Ann Arbor, MI48109-1120; D. Kumar, University of Florida, PO Box 116400, Gainesville, FL 32611
Sponsored by: SMD High Temperature Materials Committee Program Organizers: Dr. N.S. Cheruvu, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228; Dr. K. Dannemann, GE Power Generation Engineering, One River Road, Schenectady, NY 12345
Tuesday, AM February 11, 1997
Session Chairperson: Dr. K. Dannemann, GE Power Generation Engineering, One River Road, Schenectady, NY 12345
Room: 314B Location: Orlando Convention Center
Session Chairperson: Rajiv K. Singh, University of Florida, 317 MAE, PO Box 116400, Gainesville, FL 32611-6400
8:30 am INVITED ATOMIC VERSUS MOLECULAR BEAMS FOR DOPING OF III-V MATERIALS DURING GROWTH IN ULTRAHIGH VACUUM: C.R. Abernathy, University of Florida, PO Box 116400, Gainesville, FL 32611 9:00 am INVITED RECENT ADVANCES IN CARBON NITRIDE AND RELATED HARD COATING MATERIALS: Y.P. Chung, North Western University, 2145 Sheridan Rd., Evanston, IL 60208 9:30 am INVITED MEASUREMENTS AND SIMULATION OF BEAM-ENHANCED EPITAXIAL GROWTH PROCESSES: E.H. Chason, Sandia National Laboratory, Albuquerque, NM 87185 10:00 am BREAK Session Chairperson: Roy Clarke, Department of Applied Physics, University of Michigan, Ann Arbor, MI 48109-1120
10:15 am INVITED MICROSTRUCTURAL EVOLUTION IN LOW ENERGY BEAM PROCESSING OF THIN FILMS: Krishna Rajan, Rensselaer Polytechnique Institute, Dept. of Materials Science & Eng., MRC-IIO, Troy, NY 121803590 10:45 am INVITED UHV SPUTTER-DEPOSITION OF ULTRATHIN MAGNETIC FILMS AND MULTILAYERS: l.R. Childress, University of Florida, PO Box 116400, Gainesville, FL 32611 11:15 am DEPOSITION OF DIAMOND FROM ALCOHOL PRECURSORS IN AN ELECTRON CYCLOTRON RESONANCE PLASMA: Donald R. Gilbert, Rajiv K. Singh, University of Florida, PO Box 116400, Gainesville, FL32611 11:30 am INVITED SPUTTER DEPOSITION OF PHOSPHORS FOR ELECTROLUMINESCENT FLAT PANEL DISPLAY: Mark R. Davidson, Paul H. Holloway, Balu Pathangey, University of Florida, University of Florida, PO Box 116400, Gainesville, FL 32611
Tuesday, AM February 11,1997
Room: Salon 3 Location: Clarion Plaza Hotel
8:30am THE EFFECT OF THICKNESS AND TOTAL SULFUR CONTENT ON PWA1480 OXIDATION: A SCALE ADHESION MAP: l.L. Smialek, NASA Lewis Research Center, Cleveland, OH 44135 The cyclic oxidation resistance of advanced superalloys is dramatically improved when the typical sulfur impurity levels are reduced from about 3-10 ppmw to below 1 ppmw. Optimum scale adhesion can be obtained when the sulfur content is reduced below a discreet critical level. To demonstrate this phenomenon, coupons of PWA1480 were desulfurized by a hydrogen annealing process. The degree of desulfurization was controlled by sample thickness and annealing time and temperature, but did not strictly follow a DtJLl diffusion parameter dependency. From an initial sulfur value of 6 ppmw, 15 different sulfur levels were produced ranging from 0.05 to 4 ppmw. Cyclic oxidation resistance in 11 OO°C tests improved directly with the degree of desulfurization, reaching an optimum below about 0.2 ppmw. Furthermore, at equivalent sulfur levels, thick samples were prone to greater weight loss than thin samples. The results are discussed in terms of an adhesion map based on the equivalent number of interfacially segregated monolayers of sulfur. 8:50am ENVIRONMENTAL DEGRADATION OF GAS TURBINE MATERIALS IN STEAM: Y. Patel, D.C. Tamboli, V. Desai, Mechanical Materials and Aerospace Engineering Department, University of Central Florida, Orlando, FL 32816; N.S. Cheruvu, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228 Steam has been proposed as an efficient cooling medium for the hot section components in the advanced gas turbines as an option for more efficient cooling allowing them to operate at higher efficiency. However, the effects of steam and its impurities such as NaCI and Na,S04 on the environmental degradation of gas turbine superalloys is little known. Three common gas turbine superalloys; X-45, IN-738 and Inconel-617 were exposed to steam at higher temperature. Cylindrical specimens with central bore were kept at elevated temperature and exposed to three steam environments flowing through the bore. The three environments are (a) steam generated from deionized water, (b) steam generated from deionized water with 5ppm each ofNaCI and Na,S04 and (c) steam generated from deionized water with 50ppm each of N aCI and Na,S04. The respective exposure times were 1450, 2950 and 3900 hours. IN738 showed severe internal oxidation in steam without contaminants. In contaminated steam the hot corrosion damage was maximum in Inconel-617. X45 showed less oxidation damage than IN-738 and less hot corrosion than Inconel-617. 9:10am THE OXIDE LAYER PHASE STRUCTURE OF MCRALY-COATINGS: N. Czech, W. Stamm, Siemens AG Power Generation Group, and B. Kolarik, Fraunhofer-Institute for Chemical Technology During service blades and vanes of stationary gas turbines are subjected to high temperatures. The increase in surface temperatures causes a more severe attack on the MCrAlY-coatings. These coatings are taken for bond coats for thermal barrier coatings as well. The production of a homogeneous oxide
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layer during service is necessary for a good oxidation protection and for a good adhesion to the ceramic. We will present in-situ X-ray measurements on 8% and 12% AI containing MCrAIY-coatings with and without Re at three different temperatures versus time. At lower temperatures mainly a two phase mixture of CrpJ and AIPJ is detectable with different size distributions for the coatings with 8% and 12% AI. On microsections the ~-phase depletion is analyzed. At IOS0°C a pure AIPJ oxide layer is established. No Re can be found in the top layer. 9:30am THE EFFECT OF RHODIUM WEIGHT PERCENT ON THE OXIDATION RESISTANCE OF PLATINUM RHODIUM MODIFIED ALUMINIDE COATINGS ON MAR M-509 AND FSX-414 COBALT BASE ALLOYS: 1. Kimmel, Z. Mutasim, Solar Turbines, Inc., 2200 Pacific Highway, San Diego, CA 92186-S376 Cobalt based alloys such as Mar-M S09 and FSX-414 are coated with a precious metal aluminide (platinum-rhodium-aluminide) to provide enhanced oxidation and hot corrosion resistance in gas turbine applications. The role of rhodium in the aluminide coating is not well understood. There is limited data suggesting that it provides added oxide adherence and reduced refractory element diffusion from the base alloy too the coating interface, thus reducing the tendency of spallation during high temperature exposure. However, too high of a rhodium content decreases the ductility of the coating and, after cyclic oxidation, may result in coating cracking and spallation. The objective of this study is to evaluate platinum-rhodium-aluminide optimum rhodium weight percentage on Mar-M S09 and FSX -414 cobalt based alloys. Metallurgical evaluation was performed on platinum rhodium aluminide coatings with varying rhodium weight variation between 0% and 10%. Oxidation tests were performed at 2000°FIlOOO hours, 2100°F/l000 hours (100 hour cycles). Characteristics such as coating thickness, composition, microstructure, and weight changes were evaluated for the as-coated and oxidized specimens using SEM and EDX analysis. 9:50 am BREAK 10:20 am HIGH TEMPERATURE OXIDATION OF NICKEL BASED SUPERALLOYS IN STEAM: V. Desai, D.C. Tamboli, Mechanical Materials and Aerospace Engineering Dept., University of Central Florida, Orlando, FL 32816; N.S. Cheruvu, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228 An improvement in the cooling of hot gas path components of the has turbines has been sought by replacing air with steam as a cooling medium. However the materials problems associated with steam at high temperature are unknown for gas turbine superalloys. This information is very crucial for the reliability and life prediction of the gas turbine components. In this study, oxidation in steam has been studied for four nickel based superalloys commonly used in the gas turbines, IN738, Inconel617 and CMSX-4. The study was carried out at four different test temperatures within the range of 800°C to 950°C for times up to 1400 hours. The oxidation tests were also carried out in air to provide a comparison between the oxidation in steam and air. The results indicated higher internal oxidation in IN738 compared to other two alloys. The oxidation attack observed in IN738 was higher in steam compared to air, whereas in other alloys reverse was the case. 10:40 am NITRADATION AND MECHANICAL DEGRADATION OF COAT· INGS IN GAS TURBINE BLADES: 1. Kameda, T.E. Bloomer; Ames Laboratory & CATD, Iowa State University, Ames, IA 50011; S. Sakurai, Mechanical Engineering Research Laboratory, Hitachi Ltd., 3-1-1, Saiwai Hitachi 317, Japan In-service environmental attack and mechanical degradation of CoNiCrAIY coatings in gas turbine blades have been investigated using a scanning Auger microprobe (SAM) analysis and small punch (SP) testing technique. Coating degradation was found to strongly depend on the location of blades operated for 21000h under liquefied natural gas. SAM analyses revealed extensive formation of AIN and Ni enriched in inner (concave) coatings but not in outer (convex) ones. The oxidation and carbonization also occurred more substantially in near surface regions of the inner coating. SP specimens were pre-
pared from the inner and outer coatings in order that the specimen surface could be located near surface or interface coatings. SP tests demonstrated that the oxidation and nitridation in the inner coating produce significant mechanical degradation. Brittle cracking in the inner coating occurred at low strains «3%) up to 9S0°C though near interface coatings showed a little higher ductility. The outer coatings near the surface and interface showed higher RT ductility (>6%) than the substrate and a rapid increase in the ductility above 800°C. The coating degradation mechanism is discussed in light of the distribution of operating temperatures. 11:00 am DIFFUSION AND OXIDATION BEHAVIOR OF ELECTRODEPOS· ITED NI-AL PARTICLE COMPOSITE COATINGS: D.F. Susan, K. Barmak, A.R. Marder, Lehigh University, Department of Material Science and Engineering, Bethlehem, PA 18015 The high temperature diffusion and oxidation behavior of electro-deposited Ni matrix!AI particle coatings was studied to determine the relationships between coating microstructure and high temperature behavior. The coatings, containing up to approximately 20 vol. % Al particles, were deposited on nickel substrates and heat treated at 635,800, and 1000°C for up to 100 hours. Upon heat treatment at 63S and 800°C, a two phase structure of NiJAI (1') and y solid solution develops with small Kirkendall voids also present. At 1000°C, the coating contains only a solid solution in agreement with the NiAI phase diagram. The microhardness of the coating was found to increase with increasing Nail content. Both as-plated and heat treated coatings were oxidation tested in air at 800, 900, and 1000°C for up to 900 hours. Results indicate that the Al content is sufficient to form a protective AlP, scale on the coatings during isothermal exposure at these temperatures. 11:20 am HIGH TEMPERATURE OXIDATION BEHAVIOR OF NIOBIUM ALUMINIDE INTERMETALLICS WITH MOLYBDENUM SILICIDE AND NICKEL ALUMINIDE PROTECTIVE COATINGS: Y. Li, W.O. Soboyejo, R.A. Rapp, Ohio State University, Department of Material Science and Engineering, Columbus, OH 43210 Niobium aluminide intermetallics can exhibit attractive combination of hightemperature strength retention and room-temperature ductility/damage tolerance. Preliminary studies have also shown that niobium aluminides have moderate oxidation resistance at temperatures up to - 7S0°C in the uncoated condition. However, their oxidation kinetics are not fully understood. In this study, the high-temperature oxidation resistance of niobium aluminide intermetallics (Nb-1SAl-IOTi, Nb-1SAI-2STi, Nb-15AI-40Ti and Nv-12.SAI-41 Ti1.SMo) was studied using uncoated and coated alloys. Protective coatings were formed via in-situ chemical reactions designed to promote the siliciding an aluminizing of Mo and Ni substrate layers, respectively. The isothermal and cyclic oxidation behavior of coated and uncoated materials in air were then studied in the temperature range between 6S0 and 850°C. The oxide scales and internal layers were analyzed using XRD, SEM and EDX. The implications of the results are assessed for potential high-temperature applications of niobium aluminide intermetallics. 11:40 am ELECTRO-SPARK ALLOYED HEAT RESISTANT COATINGS ON THE WC·CO BASE: A.D. Verkhoturov, S.v. Nikolenko, N.V. Lebukhova, Institute of Materials of Russian Academy of Sciences, Khabarovsk, Russia Electro-spark alloying of the metallic surfaces is one of the most perspective coating technologies, among the many other current coating processes. The main advantages of this method include the possibility of depositing any current conducting materials on the surface; high adhesive strength of the layer, and the simplicity of the process. Electro-spark coatings usually have a relatively low continuity of 60-90%; defects (pores, microfractures), heterophase structure. In spite of that, it is possible to achieve, by using refractory alloys as electrodes, a stable effect of increasing heat-resistance. The research conducted by the Institute of Material Science of the Russian Academy of Sciences (Khabarovsk, Russia) showed that electrode materials which examine increasing heat-resistance, can be put in the following order (based on the main component): boride-carbide-nitride. The highest hardness (20-24 GPa) and wear resistance among coatings on steel, is achieved with a hard alloy with tungsten carbide-cobalt base (WC-92%, Co-8%). For increasing Wc-Co
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alloy electro-spark coatings', deposited on the parts working in high temperature and wear conditions, resistance to high-temperature oxidizing, we propose including self-fluxing materials or heat-resistant intermetallics in the alloy. The research in new materials, that include additives of Ni-Cr-B-Si and Ni3Al (0, 5-25%) to the Wc-Co alloy, was also conducted. We have studied the characteristics of macro- and microstructure of materials and coatings, as well as their chemical compositions, electrode material transfer kinetics, and the optimal conditions of alloying the surfaces. Kinetics of high-temperature oxidizing and phase composition of the interaction products, were examined using a differential thermal analysis in non-isothermal conditions method.
MATERIALS FOR SPALLATION NEUTRON SOURCES II: Radiation Effects, B Sponsored by: Jt. SMDIMSD Nuclear Materials Committee Program Organizers: M.S. Wechsler, North Carolina State University, L.K. Mansur, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6376; C.L. Snead, Brookhaven National Laboratory, Upton, NY 11973-5000; W.F. Sommer, Los Alamos National Laboratory, Los Alamos, NM 87545
Tuesday, AM February 11, 1997
Room: Salon 4 Location: Clarion Plaza Hotel
Session Chairperson: W. F. Sommer, Los Alamos National Laboratory, Los Alamos, NM87545
terial is available). First results for specimens obtained from (1) and (2) "vill be reported. 9:30am SIMULATION IRRADIATIONS OF TARGET AND STRUCTURE COMPONENTS FOR SPALLATION NEUTRON SOURCES: E. Camus, N. Wanderka, H. Wollenberger, Hahn-Meitner-Institut, D-14109 Berlin, Germany Beside damage levels up to 10 dpa per month, the spallation reaction induces high levels of transmutation products, mainly hydrogen (up to 0.5 at.% per month) and helium (up to 0.1 at.% per month). Dual-beam irradiations with heavy ions, protons, and/or helium ions with energies up to 300 keY make it possible to introduce such damage levels and high hydrogen or helium contents within hours. We present experimental results on the microstructure evolution and on mechanical properties of simulation irradiated steels and tantalum. The cavity microstructure is investigated by means of transmission electron microscopy (TEM). Field-ion microscopy with atom probe (FIMAP) shows fine scale radiation-induced segregation. Hardness measurements on specimens implanted at low temperature with heavy ions, protons, and/or helium have been performed and reveal a drastic increase of hardness. Both the displacement rate and the hydrogen or helium implantation rate used in simulation irradiations are orders of magnitude higher than those produced in spallation environments. Data correlation, with special emphasis on the influence of the hydrogen or helium implantation rate, is discussed. 10:00 am BREAK
8:30am RESISTIVITY CHANGES IN SUPERCONDUCTING-CAVITYGRADENb FOLLOWING IllGH-ENERGYPROTON IRRADIATION: c.L. Snead, A. Hanson, G.A. Greene, C.J. Czajkowski, Brookhaven National Laboratory, Upton, NY 11973-5000
10:20 am TRIPLE ION-BEAM STUDIES OF RADIATION DAMAGE EFFECTS IN A IllGH POWER SPALLATION NEUTRON SOURCE ENVIRONMENT: L.K. Mansur, K. Farrell, E.H. Lee, G.R. Rao, J.D. Hunn, P.M. Rice, M.B. Lewis, S.w. Cook, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6376
Niobium superconducting rf cavities are proposed for use in the proton LINAC for spallation neutron applications. Because of accidental beam loss and continual halo losses along the acceleration path, the concern of the degradation of the superconducting properties with accumulated irradiation arises. Residual-resistivity-ratio (RRR) specimens ofNb, with a range of initial RRR's, were irradiated at room temperature at energies from 200 Me V to 2000 MeV. Four-probe resistance measurements were made at room temperature and at 4.2 K both prior and after irradiations. Proton fluences ranged from 5 x 10 14 to about 5 x 1016 p/cm2 • These room-temperature results simulate the resistance changes to be expected in LINAC operation for the cavities having been exposed to the radiation and then cycled through an anneal to room temperature. The defect structures produced have been characterized using both scanning and transmission microscopy. Implications of the results to proposed cavity operation and recent results on cavity irradiations will be presented.
The unique Triple Ion-Beam Facility (TIF) at ORNL allows researchers to mimic significant features of the NSNS irradiation environment by producing displacement damage and injecting He and H simultaneously. In this work, therefore, austenitic EC316LN and ferritic 9Cr2WVTa alloys were irradiated using the T1F to investigate radiation damage effects. Irradiations were carried out using 4 MeV Fe++, 400 keY He+, and 200 keY H+ simultaneously to accumulate 50 dpa, 10,000 appm He, and 50,000 appm H, respectively. Irradiations were carried out at temperatures from 50 to 200°C. The specific ion energies were chosen to maximize the damage and the gas accumulation at the same depth of -111m. Microstructure and surface hardness of irradiated specimens were evaluated by TEM and the Nanoindenter, respectively. This report summarizes damage microstructure as a function of irradiation depth from cross-sectioned TEM specimens and hardness variation of the bombarded surfaces.
9:00am POST-IRRADIATION TESTING OF TARGET COMPONENTS AFTER SERVICE IN LAMPF: F. Carsughi l , H. Derz2, G. Pott2, w.p. Sommer3, H. Ullmaier 1, M. Zaslawsky3; lInstitut fiir Festkorperforschung, D-52425 Jiilich, Germany; 2Heissen Zellen des Forschungszentrum Jiilich, D-52425 Jiilich, Germany; 3LosAIamos National Laboratory, Los Alamos, NM 87545 Radiation damage is considered to be the most critical load for the lifetime of components in or close to the proton beam penetrating the target of high power spallation sources. Specimens irradiated in operating medium-power spallation devices are at present the only source of direct information on the behavior of materials in a spallation environment. Within an international cooperation, the following specimens will be investigated in the hot cells at KFA Jiilich: (1) A hemispherical LAMPF window made of INCONEL 718, (2) A spherical LAMPF water degrader made of INCONEL 718 and 316 SS, (3) Two curved PSI windows made of DIN 1.4926 SS and irradiated in LAMPF, and (4) A complete target from ISIS consisting ofTa plates in a 304 SS housing. After cutting and preparation of different types of miniaturized specimens the following tests will be performed: 3 point bending tests, ball punch tests, microhardness measurements, scanning (and possibly transmission) electron microscopy, and tensile tests (only for ISIS specimens where ample ma-
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10:50 am IRRADIATION DAMAGE OF FERRITICIMARTENSITIC STEELS: FUSION PROGRAM DATA APPLIED TO THE SPALLATION NEUTRON SOURCE APPLICATION: R.L. KIueh, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6376 Ferritic/martensitic steels in the target structure of a spallation neutron source will experience many of the extreme conditions expected in a fusion power plant (i.e., high-energy neutrons that produce large amounts of displacement damage and transmutation helium). Thus, studies of the steels for fusion are relevant for the spallation neutron source application. The ferritic/martensitic steels are candidates for fusion because of superior swelling resistance, better liquid-metal compatibility, higher thermal conductivity, and lower thermal expansion than austenitic steels. The mlljor problem with ferritic/martensitic steels involves the effect of irradiation on fracture, as determined by a Charpy impact test. Fast reactor irradiation produces an increase in the ductile-brittle transition temperature and decrease in the upper-shelf energy. The effect saturates with fluence for fast-reactor irradiation, but the saturation values observed for irradiation in a fast reactor do not apply for irradiation in a mixedspectrum reactor under conditions where transmutation helium is generated simultaneously with displacement damage. This helium effect is one of the critical issues that needs to be understood, since high helium concentrations
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will be generated in conjunction with the displacement damage in a fusion reactor-and in the target of a spallation neutron source, should a ferriticl martensitic steel be chosen for that application.
in halide melts which were confirmed by experiments reported in another paper. The reviewed data on sulfide capacities are presented together with calculations of sulfur partition achievable with different slags.
11:20 am ACTIVATION OF MATERIALS PROPOSED FOR USE IN SUPERCONDUCTING LINACAPPLICATIONS: A. Hanson!, c.L. Snead!, G.A. Greene!, C.J. Czajkowskjl, K.c. Chan2, H. Safa3 ; !Brookhaven National Laboratory, Upton, NY 11973-5000; 2Los Alamos National Laboratory, Los Alamos, NM 87545; 3DSMIDAPNIAISEA, C. E. SACLAY, 91191 Gif sur Yvette, France
9:20am SULFUR SOLUBILITY IN CaCI 2-CaF, and BaF2-BaCI, MELTS: S. Simeonov, R Sridhar, J .M. Toguri, Department of Metallurgy and Materials Science, University of Toronto, Toronto, Ontario, Canada M5S 3E4. CaF, additions are made to oxide based slags used for steel desulfurization to aid in sulfur removal. It is commonly held that CaF2 by itself does not possess sulfur removal capability but enhances fluidity of CaO based slags which helps desulfurization. Recently BaF2 additions to CaO and BaO based slags have been studied to improve their sulfide capacity. To better understand the sulfur removal mechanism, sulfur solubility measurements were carried out on CaCI 2-CaF2 and BaCI 2-BaF2 melts. Results showed that contrary to earlier expectation they have high sulfur solubility and higher than that for sodium silicate slags which are used for desulfurization. The conventional sulfide capacity definition based on exchange of oxygen and sulfur ions in slag used for defining desulfurization power of slags do not apply to such melts as there are no oxygen ions present and no oxygen ion transfer takes place.
Linacs are proposed for spallation neutron sources which are capable of relatively high beam currents. Associated with the transport of these high currents will be relatively high beam losses to the linac structures from the beam halo and occasional mis-steering. A series of irradiations have been conducted at the Saturne, France, accelerator in which specimens of steel, copper, NbTi, aluminum, and niobium were exposed to protons with energies from 400 to 2000 MeV. Gamma activation measurements were made for various times subsequent to the end of the beam. Absolute and relative activity levels have been achieved on which estimates of the exposure levels to maintenance personnel can be made. Particular attention was given to Nb because of its prominence in scenarios that call for superconducting rf-cavity linacs. For Nb the activation products for the various irradiations were determined and compared with code predictions.
9:45am ASPECTS OF SLAG OPTIMIZATION IN SMELTING OF Cu-Ni SULFIDE CONCENTRATES: A.A. Hejja, R.H. Eric, School of Process and Materials Engineering, University of the Witwatersrand, Johannesburg, Private Bag 3, WITS 2050, South Africa
MATERIALS PROCESSING FUNDAMENTALS SYMPOSIUM I
The first part of tItis study deals with the importance of surface tension of slags produced in the smelting of sulfide concentrates. Theoretically the method of determining the surface tension of slags was laid down by Boni and Derge. The values obtained experimentally for a series of main oxide components were grouped into a useful correlation incorporating experimental constants for the relevant oxides present in the slag, some of these giving the surface tension value for the particular slag. These estimated values were coupled with or incorporated into the slag viscosity plots to show the correlation between the two factors. This is also important from a refractory attack point of view in the furnace operation. In the second part an attempt is made toward the optimization of slag composition relevant both for electric and reverberatory smelting processes. Using the knowledge of the viscosity and electrical conductivity of the slags at the temperature of furnace operation, the mode of optimization is based on Besselt function correlations which utilize the trend of the mostly parabolic plots of viscosities and conductivities. The results obtained by tItis method agree well with the optimum slag compositions being used in established operations derived from years of practical experience for various slags used in the furnaces. However, due to extensive turbulence in suspension and gas injected bath smelting processes, the outlined methods cannot be used for these processes. Also great caution should be exercised in their application for three electrode circular furnaces with separate slag cleaning.
Sponsored by: Jt. EPDIMDMD Synthesis, Control, and Analysis in Materials Processing Committee, EPD Process Fundamentals, Aqueous Processing, Copper, Nickel-Cobalt, Pyrometallurgy, Lead, Zinc, Tin Committees, MSD Thermodynamic & Phase Equilibria Committee Program Organizers: R.G. Reddy, Department of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL 35487-0202; S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; P.R. Taylor, Department of Metallurgical and Mining Eng., University of Idaho, Moscow, ID 83743 Tuesday, AM February 11, 1997
Room:231B Location: Orlando Convention Center
Session Chairpersons: M. E. SchleSinger, Department of Metaliurgical Engineering, University of Missouri-Rolla, 1870 Miner Circle, Rolla, MO 65409-0340; Dr. S. Wang, ASARCO Inc., Technical Services Center, 3422 South 700 West, Salt Lake City, UT84119
8:30am SULFIDE CAPACITY OF FeO-BASED SLAGS: RG. Reddy, W. Zhao, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487
10:10 am BREAK 10:20 am
Sulfide capacities of FeO-based silicate slags were calculated a priori using the Reddy-Blander model. Experiments were done using encapsulation method for several slag systems as a function of compositions and temperatures. The experimental results agree with the predicted data very well. The predicted sulfide capacity data was used in calculation of the sulfur distribution ratio in the slags and metal.
SOLUBILITY OF BISMUTH AND LEAD IN IRON AND IRON-CARBON ALLOYS: Lewen Chang, Sandeep Malhotra, Mark E. Schlesinger, Department of Metallurgical Engineering, University of Missouri-Rolla, 1870 Miner Circle, Rolla, MO 65409-0340 The thermodynamic properties of Fe-C-Bi and Fe-C-Pb alloys are of interest for a variety of reasons related to steel production and recycling; however, experimental data on phase equilibria in these systems are scarcer. Experimental procedures will be described for an ongoing research program measuring the activities of Bi and Pb in solid and liquid Fe and Fe-C alloys. Preliminary results will be presented, with the primary goal of using measured solubilities to derive model parameters for calculating bismuth and lead activities as a function of temperature and alloy composition.
8:55am SULFIDE CAPACITY OF SLAGS: R Sridhar, S. Simeonov, 1.M. Toguri, Department of Metallurgy and Materials Science, University of Toronto, Toronto, Ontario, Canada, M5S 3E4 During the experimental studies on sulfide capacities of non-ferrous metallurgical slags it was found that the choice of the thermodynamic data base is important for calculating the sulfur potential in such measurement. It was also found that some of the earlier sulfide capacity measurements required recalculation. The available sulfide capacity for different slag systems were reviewed after recalculations. This analysis suggested high sulfur solubility
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10:45 am THERMODYNAMICAL INVESTIGATIONS OF METALLURGICAL AND MATERIALS PROCESSES AND PHENOMENA: Vladimir Mindin, AFp, 111 East Shore Road, Manhasset, NY 11030; Yakov Mindin, Polytechnic University, Six MetroTech Center, Brooklyn, NY 11201 The report presents results of thermodynamical investigation of wide range of complex systems, including carbo thermal reduction of silica, silicon carbide obtaining from different precursors, anode processes during molten salts electrolysis, tin atomization in AAS, interaction in copper-, manganese- and sulfur- containing systems, Special attention is paid to thermodynamical approach to investigation and estimation of multi component multi element compositions stability. Environmental topic in the report is presented by discussion of two important issues: (a) problem of radioactive wastes interaction -with environment, and (b) investigation on thermodynamic stability of exhaust from different sources. Also are discussed very important problems of informational support (thermodynamics data accuracy) of complex systems thermodynamics simulation. 11:10 am OXYSULPHIDE IN METALLURGY OF NICKEL AND COBALT: LD. Reznik, A.V. Tarasov, T.A. Kharlakova, State Research Institute of Non-Ferrous Metals, Acad. Korolyov Street, 13, Moscow, Russia, 129515; E.N. Selivanov, Institute of Metallurgy of the Ural's Branch of the Russian Academy of Sciences, 101 Amundsen Street, Ekaterinburg, Russia, 620147 On blowing nickel matte in a converter without quarts, first the oxidation of metallic iron and a part of FeS occurs without evolving sulfur dioxide, the formed FeO dissol ves in a sulfide smelt and form a homogeneous Oxysulphide smelt. On further increasing the FeO content, the Oxysulphide separates into 2 layers. Based on the laboratory investigation of FeO-(FeS+FeO) - (Ni 3S2+NiO) ternary phase we have identified the separation region at 1250oC. The boundaries of the separation region have the form of an arc and the composition of the separated Oxysulphide layers is defined by the canodes. In the nickel or copper-nickel matte - calcium oxidesilica slag system at 1250T three layers, namely sulfide, Oxysulphide, and slag may be formed. A high slag basicity due to the presence of CaO can serve to enhance the activity of FeO; a low nickel content in the matte corresponds to a high concentration of FeS therein; FeO from slag and FeS from the matte form a homogeneous FeO-FeS solution, i.e. an Oxysulphide layer. The investigation on the "Camebakes" apparatus and by the nuclear gamma-ray resonance spectroscopy method of the phase composition in a slowly cooled Oxysulphide layer has shown the presence of four phases. wustite, troilite, ferronickel grains, and calcium oxidesilica inclusions. Knowledge of regulaties in the oxysulphides formation makes it possible to use them in pyrometallurgy of nickel and cobalt or preventing their formation.
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NON-LINEAR FRACTURE PROCESSES IN BRITTLE: CRYSTALLINE SOLIDS II: Layered Systems Sponsored by: ASM-MSD Flow and Fracture and SMD Mechanical Metallurgy Committees Program Organizer: J.K. Shang, Department of Materials Science and Enginee'i1g, University of Illinois, Urbana, IL 61801; P. K. Liaw, Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996-2200; S.X. Mao. Department of Mechanical Engineering, University of Calgary, Calgary, Alberta. Canada, T2N 1N4 Tuesday, AM February 11, 1997
Room: 232B Location: Orlando Convention Center
Session Chairperson: P.K. Liaw, Department of Materials Science and Engineering, University ofTennessee, Knoxville, TN 37996-2200
8:30 am INVITED RELIABILITY OF FERROELECTRIC CERAMIC MULTILAYER DEVICES: Z. Suo, X. Gong, Mechanical and Environmental Engineering Department, Materials Department, University of California, Santa Barbara, CA93106 In a multilayer actuator, each internal electrode terminates an edge inside the active ceramic. Around the edge, the nonuniform electric field generates an incompatible strain field, which, in its turn, generates stresses and may cause the ceramic to crack, leading to device failure. The industry has been exploring alternative electrode configurations to alleviate the stress concentration. The effort has been empirical and benefited little from numerical simulations. An inherent difficulty is that the actuator ceramics have nonlinear electro-mechanical interactions, of which no unified mathematical description is now available. This talk describes the basic phenomena, and a crack nucleation model that includes essential features of this nonlinearity. The model shows that, everything else being fixed, a critical layer thickness exists, below which a multilayer actuator will not crack around its internal electrode edges. 9:00am NON-LINEAR FRACTURE PROCESSES IN LAMINATED METAL COMPOSITES: Don Lesuer, Bob Riddle, Chol Syn, L-342, Lawrence Livermore National Laboratory, Livermore, CA 94551 Numerous fracture processes exist in layered materials. These processes, which include crack bridging, crack deflection, stress redistribution and local plane stress deformation, will, in general, increase the fracture toughness of layered materials over that observed for non-layered materials. However, their specific influence on toughness (namely their influence on initiation toughness, growth toughness and R-curve behavior) is a function of the specific fracture mechanism active during crack growth. Many of these mechanisms compete with one another. The active mechanism(s) are strongly dependent on the material properties of the component layers, laminate architecture (such as volume fraction of the component materials and layer thickness), and interface properties. This paper will discuss the various fracture mechanisms in laminated metal composites (LMCs) containing alternating layers of ductile and brittle materials. The layers between these component materials have sharp interfaces. Specific systems include LMCs of an aluminum matrix composite and a monolithic aluminum alloy as well as ultrahigh-carbon steel and brass. Simulations of crack growth in these materials have been done u~ing finite element analysis to study the non-linear fracture processes involved. The influence of component material properties, interface properties and laminate architecture on these processes will be described.
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9:30am A QUANTIFICATION OF THE FABRIC STACKING SEQUENCE EFFECT ON THE MECHANICAL PROPERTIES OF A 2-D WOVEN NICALON FIBER FABRIC REINFORCED SiC COMPOSITE: Wei Zhao, Peter K. Liaw, Dept. of Materials Sciences and Engineering, The University of Tennessee, Knoxville, TN 37996-2200; Nianni Yu, Dept. of Engineering Sciences of Mechanics, The University of Tennessee, Knoxville, TN 37996-2200; Elizabeth R. Kupp, David P. Stinton, The Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 The mechanical behaviour of continuous fiber reinforced ceramic matrix composites is affected by several factors, such as: the type and thickness of fiber/ matrix interface, the fiber strength statistical distribution and degradation after processing, the fabric stacking sequence of the laminate etc. For a 2-D plain woven Nicalon fiber cloth reinforced silicon carbide (SiC) with a SiC interfacial coating, little attention has been paid to the stacking sequence effect. In this paper, the fabric stacking sequence effects on the stress-strain distribution in flexural laminate bars, and the elastic properties of the laminate are calculated. A theoretical calculation model is established based on a combination of the classical laminated plate theory and an undulation model depicting fiber continuity and undulation shape, which is first developed by Chou et al. A closed-form FORTRAN program is compiled. Different combination of fiber lamina orientation and their stacking sequence are studied. 10:00 am BREAK 10:30 am INVITED TOUGHENING AND FATIGUE PERFORMANCE OF BRITTLE AND SEMI-BRITTLE STRUCTURAL MATERIALS: John J. Lewandowski, Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106 Significant efforts are being devoted to the cost effective processing of advanced structural materials with unique combinations of stiffness, strength, toughness, and fatigue resistance. Such efforts are necessarily multi-disciplinary and often combine the skills of academic investigators in Materials Science and Engineering, Mechanical Engineering, and Civil Engineering, as well as other related disciplines with those from both the materials producer and user community. Recent work at CWRU in conjunction with a variety of collaborators has begun to investigate the factors controlling the magnitude of performance enhancement possible in brittle and semi-brittle systems where a variety of approaches to toughening are being explored. The presentation will overview recent research by the P.I. and his collaborators on a number of different materials systems where toughening is being accomplished via the incorporation of ductile/tough reinforcements. The presentation will follow with documenting the fatigue performance of such systems. 11:00 am INTERFACIAL INTERLOCKING FROM POROUS OXIDES: Z. Zhang, Z. Xing, J. K. Shang, Department of Materials Science and Engineering, University of Illinois, Urbana, IL 61801 Surface oxides on metals are often highly porous and the pore structure depends on oxidant and kinetics of oxidation. In this work, the oxide structure on aluminum-alloy surface was modified by chemical and electrochemical processes to produce different pore sizes and morphology. Interfacial bonds were then formed from these porous oxides and the crack growth resistance of the interfaces measured in air and corrosive environments. Significant differences were found among interfaces with different oxide microstructures. Micromechanical models were developed to determine the interlocking resistance from porous oxides. Based on the model, the role of interfacial interlocking in interfacial crack growth is discussed. 11:30 am NOTCHED TENSILE PROPERTIES OF CERAMIC MATRIX COMPOSITES: F.W Zok, High Performance Composites Center, Materials Department, University of California, Santa Barbara, CA 93106-5050 Fiber-reinforced ceramic matrix composites (CMCs) are being developed for a variety of high temperature components for gas turbine engines. Many of these components are complex in shape and will be subjected to local stress
concentration under normal service conditions. The presentation will focus on the effects of stress concentrating features such as sharp slits and circular holes on the tensile properties of CMCs. Modeling and experimental efforts aimed at improving our understanding of the relationship between the mechanisms of inelastic deformation and their effects on notched strength will be reviewed. Results on MASlNicalon and woven SiC/SiC systems indicate that the conditions for fracture in the regions around holes are stochastic in nature and depend on the volume under stress. An approach for implementing weakest link statistics for predicting notched properties will be outlined. Recent work has revealed that inelastic deformation is also attainable in all-oxide CMCs with strong interfaces and porous matrices. The notched properties of these materials will be presented and their behavior compared with that of systems with weak interfaces. Research sponsored by ARPA-URI, Grant NOOO14-92-J-1808.
RARE EARTHS; SCIENCE, TECHNOLGY AND APPLICATIONS III: Magnets Sponsored by: LMD Reactive Metals Committee Program Organizers: R.G. Bautista, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno, Reno, NV 89557; C.O. Bounds, RhonePolenc Rare Earths and Gallium, CN 7500, Prospect Plains Rd., Cranbury, NJ 08512; Timothy W. Ellis, Lulicke and Soffa Industries, Inc., 2101 Blair Mill Rd., Willow Grove, PA 19090; BarryT. Kilbourn, Molycorp, Inc., Executive 46 Office Center, 710 Route 46 East, Fairfield, NJ 07004
Tuesday, AM February 11, 1997
Room: Salon 8 Location: Clarion Plaza Hotel
Session Chairpersons: KNona C. Liddell, Department of Chemical Engineering, Washington State University, Pullman, WA 99164; Garry W. Warren, Department of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL 35487
8:30am RECENT DEVELOPMENTS IN RARE-EARTH-BASED ADVANCED PERMANENT MAGNET MATERIALS: FACTORS AFFECTING ACQUISITION AND STABILITY OF COERCIVITY: L.L. Lewis, Materials Science Division, Department of Applied Science, Brookhaven National Laboratory, Upton, NY 11973-5000, C.H. Sellers, Idaho National Engineering Laboratory, Lockheed Idaho Technologies Co., Idaho Falls, ID 83415-2211, V. Panchanathan, Magnequench International, Inc., 6435 Scatterfield Road, Anderson, IN 46013 The basic relationships that link the microstructural properties of advanced permanent magnet materials to the magnetic hysteretic properties such as the magnetic hysteretic properties such as the coercivity are subtle and often difficult to quantify. These difficulties are magnified when the magnetic materials are fabricated by methods such as rapid solidification, which has the potential to produce non-equilibrium phases and structures in a nano-scaled matrix. 9:00am Nd-Fe-B POWDERS FOR BONDED MAGNETS - AN OVERVIEW: V. Panchanathan, Magnequench International, Inc., 6435 Scatterfield Road, Anderson, IN 46013 The rapidly solidified Nd-Fe-B powders form the entire basis of the bonded magnet industry. At present the rapid solidification is carried out exclusively by melt spinning, a technique in which a stream of molten alloy is directed onto the outer surface of a rapidly spinning wheel, producing flake like particles having highly stable and magnetically hard microstructure. These particles are comminuted into powder before being processed into bonded magnets. These powders are magnetically isotropic. These powders are magnetically isotropic. The bonded magnets made using these powders range in energy product of 5 MGOe for injection molded magnets to about 12 MGOe for compression molded varieties.
9:30am MAGNETISATION MECHANISMS IN EXCHANGE COUPLED MAGNETS: R. Street, Research Centre for Advanced Mineral and Materials Processing, The University of Western Australia, Nedlands, WA 6907, Australia
RECENT ADVANCES IN FRACTURE III: Fracture During Metal Working: A Symposium Dedicated to Professor Emeritus Frank A. McClintock
Nanocrystalline composites containing grains of hard (typically REffM alloys) and soft (typically oc-Fe) magnetic materials exhibit the commercial useful property of remanence enhancement. The modelling of remanence enhancement in terms of inter- and intra- grain magnetic exchange coupling will be explained. The results of measurements of the magnetic properties of Nanocrystalline remanence enhanced magnets prepared by mechanochemical and melt quenching processes will be described.
Sponsored by: MSD Flow and Fracture; SMD Mechanical Metallurgy Committee Program Organizers: Dr. R.K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; Dr. A.B. Geltmacher, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D.C. 20375; Dr. K. Sadananda, Naval Research Laboratory, Code 6323, 4555 Overlook Drive SW, Washington D.C. 20375; Dr. P. Matic, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D.C. 20375
10:00 am BREAK
Tuesday, AM February 11, 1997
10:30 am RARE EARTH·BASED GIANT MAGNETOSTRICTIVE MATERI· ALS: S.F. Cheng, Naval Surface Warfare Center, Silver Spring, MD 20903; A.E. Clark, Clark Associates, Adelphi, MD 20783
Room: 314A Location: Orlando Convention Center
Session Chairpersons: Dr. Wilfred Simons, Army Research Office, P.O. 12211, Research Triangle Park, NC 27709; Dr. A. B. Geltmacher, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375
Among the many extraordinary features of the rare earths are their magnetic and magnetoelastic properties. The rare earths, e.g. Th, Dy, Nd, Sm, are known worldwide for their large magnetocrystalline anisotropy and magnetization, which has led to the importance of magnetic rare earths as vital ingredients of modern permanent magnets. In this paper, we focus on the strain dependence of these giant effects which gives rise to huge magnetostrictions, magnetomechanical couplings, and E effects. Magnetostrictions greater than 10-3 have been measured at temperatures as high as 250°C. At low temperatures Magnetostrictions reaches - 10. No other solid state material can match these values.
8:30 am INVITED DUCTILE FRACTURE IN STEELS AND ALUMINIUM ALLOYS: John F. Knott, School of Metallugy and Materials, The University of Birmingham, Edgbaston, Birmingham Bl5 2TT, UK Ductile fracture mechanisms in these alloys, of such importance to modern civilization, are set in the context of the main applications for which they are used. Thin-sheet applications encompass two main aspects: prevention of localized shear fracture in sheet-forming, promotion of reproducible shear fractures in the "ripping" of "ring-pulls" on beverage cans or in the stamping-out of milk-bottle tops from oil. Both aspects relate to the generation of throughthickness shear fractures. In thick-section applications, it is necessary to address local fracture mechanisms in the combination of steep strain-gradient and high hydrostatic tension ahead of a notch or pre-crack. The prime micromechanisms are microvoid coalescence and "fast (in-plane) shear" linkage resulting from a (plane-strain) localization of flow. Behaviour in steels and high-strength aluminum alloys is contrasted and recent findings on "mixedmode" shear fracture criteria are discussed. Attention is drawn to a number of applications for which "plane-stress" and "plain-strain" methodologies must be combined.
11:00 am AQUEOUS CORROSION STUDY OF RAPIDLY SOLIDIFIED NdFeB PERMANENT MAGNETS WITH TiC ADDITIONS: M. Arenas, G. W. Warren, Department of Metallurgical & Materials Engineering, University of Alabama, Tuscaloosa, AL 35487, C.P. Li, K. W. Dennis, and R. W. McCallum, Dept. of Materials Sci. & Engineering, Iowa State Univ., Ames Laboratory, Ames,IA 50011 A corrosion study of a bonded NdFeB permanent magnet material alloyed with titanium carbide additions has been undertaken. Bonded magnets produced by rapid solidification of the alloy and consolidation in a polymer matrix are attractive due to lower cost, greater durability, and useful shape-forming ability. Melt spinning is used to produce ribbons of the desired composition. The ribbons are formed by the ejection of molten alloy onto the surface of a rotating wheel. The samples tested were ribbons of different composition and wheel speed. Commercial epoxy was used as a bonding medium.
8:55 am INVITED MODELLING LARGE DEFORMATION AND FAILURE IN MANt'FACTURING PROCESSES USING INTERNAL STATE VARIABLES: Doug Bammann, Mechanics and Simulation of Manufacturing Processes Department, Mail Stop 9405, Sandia National Laboratories, Livermore, CA 94551 A state variable model for describing the fine-deformation behavior of metals is described. A multiplicative decomposition of the deformation gradient into elastic, volumetric plastic (damage), and deviatoric plastic parts is considered. With respect to the natural or stress-free configuration defined by this decomposition, the thermodynamics of the state variable theory is investigated. This model incorporates strain rate and temperature sensitivity, as well as damage, through a yield surface approach in which the state variables folIowa hardening minus-recovery format. The microstructural underpinnings of the model are presented along with a detailed description of the effects which each model parameter has on the predicted response. Issues associated with the implementation of this model into finite element codes are also discussed. A range of problems involving damage at various loading rates are presented including hydroforming, prediction of forming limit diagrams from limiting dome height studies and cracking during welding processes. In each case, experiments are well described by predictions based on this model.
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9:20 am INVITED THE EFFECT OF HYDROSTATIC PRESSURE ON THE ROOM TEMPERATURE FORMABILITY OF METAL SHEETS: Henry Piehler, Consortium for the Advancement of Deformation Processing Research, Department of Materials Science and Engineering, Carnegie Mellon University, Wean Hall 2323, Pittsburgh, PA 15213
10:45 am INVITED IMPROVED PROPERTIES OF HSLA AND DUAL-PHASE STEELS: Gareth Thomas, Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 97420-1760 and National Center for Electron Microscopy, Lawrence Berkeley Laboratory, Berkeley, CA 94720 The utilization of controlled rolling and quenching from the finish roll allows the design of composite microstructures, whereby the advantages of the second phase are optimized while the less desirable features of this phase are simultaneously mitigated by the presence of the other constituent phase. The size, morphology, distribution, shape and volume fracture of the second phase critically control the mechanical properties, especially fracture and fatigue of the dual phase systems. As a consequence, these structures offer a degree of metallurgical flexibility that is absent in single phase structures or in many precipitation strengthened systems, for attaining optimum sets of mechanical properties. Examples are presented here of martensite/austenite (-2 - 5%) mixtures designed for optimum combinations of high strength, toughness, and wear properties in medium carbon steels, e.g., for mining and agricultural applications; low carbon martensite/ferrite (-80%) structures for high strength, cold formability, improved low temperature ductility, and attractive improved corrosion resistance in concrete. In all cases these steels can be produced on line in a hot mill by controlled rolling and direct quenching.
The effect of pressure on the room temperature formability of6111 T4 aluminum and B 21 S titanium sheets was evaluated in stretching, drawing, as well as plane strain. The sheet formability tests were performed using the patented Carnegie Mellon hot triaxial deformation system in conjunction with a specially developed 2 in diameter hemispherical punch and forming fixture. The strain state was varied by using different sample widths and lubrication conditions. Tests were conducted at ambient pressure and constant pressures of up to 70 MPa (10 ksi). Increasing all pressures used in forming increased the formability of the al sheets along all forming paths. The largest pressureformability increase in the Al sheets occurred in plane strain. Biaxial stretching tests on the B 21 S sheets revealed that the formability actually decreased under a pressure of 10 ksi compared to the formability at ambient pressure. This pressure-induced formability decrease was accompanied by a change in fracture path and its mechanism is currently being investigated. 9:45 am INVITED MICROSTRUCTURAL EFFECTS ON CAVITATION AND FRACTURE IN SUPERPLASTIC METALS: Amit K. Ghosh, Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109
11:10 am EXPERIMENTAL AND THEORETICAL ANALYSIS OF THE CAVITATION AND FAILURE BEHAVIOR OF A SUPERPLASTICALLY DEFORMED NEAR-GAMMA TITANIUMALUMINIDE ALLOY: Carl M. Lombard', Perikles D. Nicolaou2, Amit K. Ghosh3 , S. Lee Semiatin', 'US Air Force Wright Laboratory, WLIMLLM, Room 101, Building 665, Wright Patterson Air Force Base, OH 45433; 2UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432; 3Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109
Cavitation leads to flow localization and fracture during superplastic forming process. In this paper, several approaches on the micro mechanical aspects of cavitation are critically examined. With plasticity effects present, constrained diffusional and plasticity-induced growth of cavities have been proposed in the dislocation creep regime. In the superplastic regime, however, cavitation behavior is considerably complicated by the predominance of grain boundary sliding and grain rotation effects. Consequently the amount of grain boundary sliding strain has a major effect on the degree of cavitation through cavity initiation, growth and coalescence. Dynarnics of cavitation and its effect on strain localization leading to fracture has been examined. Also detailed quantitative aspects of cavity initiation on cavity growth have been carefully documented to separate the phenomenon of continuous nucleation of new voids from the cavity growth process. It appears that dynamic grain growth which influences grain boundary sliding in a major way, also influences cavitation. Thus flow localization and fracture are critically affected by microstructural evolution effects such as dynamic recrystallization and dynamic grain growth. Illustrative examples will be given from various metallic system.
The uniaxial hot tension behavior of a near-gamma titanium aluminide alloy sheet (Ti-45.5AI-2Cr-2Nb) was determined in the as-rolled condition (initial grain size - 3 to 5 /lm) and a rolled-and-heat treated (1177°C/4 hours) condition (initial grain size - 10 to 12 /lm). Microstructure evolution, cavitation rates, and failure modes were established via constant strain rate tests at 10.4 to 10.2 sec" and test temperatures between 900 and 1200°C. For both initial microstructural conditions, the failure mode was established as predominantly cavitation/fracture controlled. Cavity growth rates was greatest at lower temperatures and in the heat treated specimens; the higher cavitation rates in the heat treated specimens led to elongations only approximately one-half those of the as-rolled material. Experimental results were then compared with a 'force equilibrium approach' theoretical analysis of the isothermal hot tension test under cavitating conditions. Model results delineated the competition between failure controlled by localized necking versus fracture, the latter being defined by a critical volume fraction of cavities. The validity of the modeling approach was confirmed through the analysis of the experimental results and data from the literature.
10:10 am INVITED MECHANISMS OF DUCTILE FRACTURE IN CRACK-TIP FRACTURE PROCESS ZONES: Peter F. Thomason', Department of Metallurgy and Materials Science, University of Cambridge, Cambridge CB2 3QZ; 'on leave from University of Salford
11:30 am THE EFFECT OF HYDROSTATIC AND SHEAR STRESSES ON THE HOT WORKING BEHAVIOR OF BULK METALS: Henry Piehler, Consortium for the Advancement of Deformation Processing Research, Department of Materials Science and Engineering, Carnegie Mellon University, Wean Hall 2323, Pittsburgh, PA 15213
The strength and toughness of engineering alloys, under conditions where general yielding and subcritical crack growth precede catastrophic fracture, are critically depend on nucleation, growth and coalescence of microvoids in fracture process zones that are generally subject to high mean-normal stresses. It is shown that, at these high mean-normal stress levels, microvoid nucleation and coalescence can become the controlling process of ductile fracture in crack-tip plastic zones, with negligible dilatational void-growth prior to microvoid coalescence on the fracture surface. This effect is direct result of high mean-normal stresses promoting the micro void coalescence process when the microvoids are still relatively small and widely spaced; thus virtually all dilational void-growth is confined to the final void-coalescence fracture surface, and the result of plastic limit-load failure (or internal microscopic necking) between adjacent microvoid nuclei.
The effect of pressure on the hot workability of a Ti-49.5AI-2.5Nb-1.1Mn (at 0) titanium aluminide was evaluated using both isothermal compression and isothermal hydrostatic upsetting tests. Tests were conducted at 1050°C to strains of the order of one with and without pressure of 260 MPa to evaluate the effect of pressure on flow stress response, fracture retardation, and hot worked microstructure. The samples deformed without pressure exhibited noticeable cracks on the bulged free surface as well as internal deformationinduced voids; the superimposition of pressure suppressed both these types of deformation damage. Pressure was observed to have a neglible effect on the flow stress response, which could be adequately described by the von Mises criterion in all cases. Similarly, pressure had a negligible effect on dynamic recrystallization and microstructure under the conditions investigated. Preliminary results on pore closure in Osprey processed IN 718 subsequently deformed by isothermal hydrostatic upsetting are also presented.
10:35 am BREAK
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11:50 am THE EFFECT OF MATERIALS PROCESSING ON FRACTURE OF METALS: Clyde L. Briant, Division of Engineering, Brown University, Providence, RI 02912 Thermomechanical processing of metals is often used to improve the fracture properties of materials. When materials are processed at room temperature, one can often achieve good control over resulting properties because one can avoid dynamic recovery and recrystallization. However, when processing is carried out at elevated temperature, dynamic changes can occur and make control difficult. In this paper we report on work in which refractory metals were processed at elevated temperatures try to achieve optimum fracture strength as measured in four point bending. The results will show that there is an optimum processing range to achieve fracture resistance. If the material is processed at too Iowa temperature internal cracks that occurred during processing will cause failures. If the processing temperature is too high, recrystallization occurs and the material will fail by low energy brittle fracture .. 12:10 pm THE INFLUENCE OF INCLUSIONS ON THE FRACTURE TOUGHNESS OF AerMet 100: J. W. Morris, Jr., 1. Chan and K. Sato, Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 97420-1760 and, Center for Advanced Materials, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 AerMet 100 is an ultra-high strength alloy recently that was recently commercialized by Carpenter Technology. The alloy is a secondary hardening, Fe-Ni-Co-Cr-Mo alloy that is age-hardenable to yield strength above 250 ksi, and fractures in a ductile mode at ambient temperature even after hardening to peak strength. The alloy is currently under investigation for potential use in aircraft landing gear. As expected from its ductile fracture mode, the fracture toughness of AirMet 100 is strongly dependent on the density of inclusions with sizes greater than about 211m. As the inclusion spacing increases from -0.2 to -0.8 mm, the fracture toughness rises by roughly 70%, from -110 ksi,lin. Metallurgicar analysis shows that the large inclusions in these alloys are primarily rare earth (La, Ce, Nd) oxysulfides. The rare earth elements are present in the low concentration in the alloy, and, presumably, represent intentional additions to getter metalloid impurities such as sulfur. Research has shown that substantial improvements in toughness can be obtained by filtration before solidification. The toughness of AerMet 100 can be further improved by modifying, the alloy heat treatment the alloy heat treatment to alter the distribution of hardening precipitates. A brief pre-age at 51O°C prior to the standard aging at 485°C significantly increases the fracture toughness, particularly in the case of the low-toughness sample. 12:30 pm STEREO-SECTION FRACTOGRAPHIC STUDY OF FRACTURE BEHAVIOR OF A Ti6Al4V ALLOY: Xian J. Zhang1and R. L. Tregoning', IDepartment of Mechanical Engineering, University of Maryland, College Park, MD 20742; 'Fracture and Fatigue Branch, Naval Surface Warfare Center, 3ALeggett Circle, Annapolis, MD 21402 The stereo-section fractography (SSF) technique has been employed to study the relationship of surface microfractographic features and internal microstructures. In this way, a direct correspondence is established between various fracture modes and microstructural details beneath the fracture surface of fracture toughness and fatigue specimens of an 0 Ti6Al4V alloy. The measurements show a one to one relation between surface and internal features. It was found that ductile holes formed along grain boundaries and also, cleavage facets cut through grains. It was evident that the microscopic texture formed in the solidification process affects the fracture mechanisms and hence, the fracture toughness of the alloy. Thus, the SSF technique is demonstrated as a very useful tool for the study of fracture behavior of materials.
SHAPING AND FORMING OF HIGH PERFORMANCE POWDER PRODUCTS: Session II Sponsored by: MOMO Powder Materials Committee Program Organizers: Dr. William E. Frazier, Naval Air Warfare Center Aircraft Division, Patuxent River, MD 20657; Prof. Henry R. Piehler, Dept. of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213; Dr. Jeffrey Waldman, Dept. of Materials Engineering, Drexel University, Philadelphia, PA 19104; Dr. Phillip Parrish, MATSYS Inc. Arlington, VA 22209
Tuesday, AM February 11, 1997
Room: Salon 7 Location: Clarion Plaza Hotel
Session Chairpersons: Dr. Jeffrey Waldman, Dept. of Materials Engineering, Drexel UniverSity, Philadelphia, PA 19104; Dr. William E. Frazier, Naval Air Warfare Center Aircraft Division, Patuxent River, MD 20657
8:00am P/M APPLICATIONS IN THE AUTOMOTIVE INDUSTRY: Alan Lawley, Dept. of Materials Engineering, Drexel University, Philadelphia, PA 19104 The North American automotive industry is now a major user of PIM products. In the last sixteen years the weight of PIM parts in a family vehicle has increased from 7.7 to 13.7 kg. and this trend is expected to continue. The results of a recent Delphi Study predict substantial growth over the next decade in power train applications (camshaft lobes, conrods, bearing caps, transmission gears, valve seat inserts, and valve guidelines). In this presentation, three PIM automotive case studies are examined in terms of the technical and economical factors that resulted in commercial viability: (i) the pressed and sintered main bearing cap, (ii) the warm formed turbine hub, and (iii) the powder forged connecting rod. Potential new PIM automotive applications are also discussed. 8:30am HIPPING OF PIM PRODUCTS: James H. Hahn, Pressure Technology Inc., Warminster, PA 18974 Abstract not available. 8:55 am NET SHAPE PROCESSING OF NAVY AIRCRAFT MATERIALS: William E. Frazier, Naval Air Warfare Center Aircraft Division, Patuxent River, MD 20657 New and emerging Navy aircraft systems must satisfy the demanding performance requirements of the 21st Century, and yet, be affordable. This paper examines how advanced, net-shape technology is being implemented and how it can be used to reduce the cost and enhance the performance Navy aircraft. 9:20am PRESSURE CYCLING ENHANCED DENSIFICATION IN SEVERAL COMPOSITE COMPACT SYSTEMS: Ching-Yaa Huang, O.S. Daehn, Dept. of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210 Recently, it has been observed that pressure cycling can significantly enhance densification of composite powder compacts in the constrained uniaxial consolidation. The simple explanation for this is that differential compressibility in the constituents of composites drives plasticity in the deformable phrase and the net compressive stress biases the resulting strain to fill porosity in compacts. In the present paper, several composites powder systems including Pb, Zn, Al matrices and AIP3P, TiO,p' SiC w ' reinforcements have been studied in room temperature consolidation in static and cyclic loading. Effects of pressure cycle maximum stress, amplitude, and period on the densification of composite powder compacts are observed and analyzed in terms of matrix strength as well as reinforcement properties including size, shape, and agglomeration. Some simple ideas are able to explain the observed results .
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9:45 am
to make hollow parts with thin walls. Potential applications for this technology include titanium and beryllium components including fan blades, inlet guide vanes, nozzle hardware, prosthetic devices, and intermetallic and composite components. This effort uses recent advances in process modeling and in-process sensing technologies to reduce the lead time and number of iterations required to make a net shape component. This is turn will make components more cost effective. The areas being exploited include rapid prototyping from CAD files to generate patterns and molds, numerical simulation of the electroforming process to optimize shield design and uniformity of canister thickness, and numerical simulation of HIP consolidation to predict final component dimensions.
HIGH-NITROGEN AUSTENITIC STAINLESS STEEL POWDERS PORDUCED BY GAS ATOMIZATION: G.O. Rhodes, W.B. Eisen, Crucible Research Center, 6003 Campbells Run Rd., Pittsburgh, PA 15205 Nitrogen is increasingly being utilized as an interstitial alloying element in stainless steels due to the intrinsic benefits imparted on the strength and corrosion resistance properties. Using an alloy design model, austenitic stainless steel powders consisting of about 6-12% manganese, 22% nickel, 25-28% chromium, 4-8% molybdenum and having 0.6 to 1.25% nitrogen have been produced using nitrogen gas atomization. The nitrogen contents attained are substantially higher than predicted at a temperature of 1600°C and nitrogen partial pressure of 100kPa using current thermodynamic models. The powders are subsequently consolidated to full density by hot isostatic pressing (HIP), and in the solution annealed condition the materials exhibit tensile yield strengths of up to 700 MPa with good tensile ductility and excellent corrosion resistance. The development and evaluations of the new steel are described in comparison to other established super austenitic stainless steels and nickel base corrosion resistant alloys.
11:25 am ENHANCEMENT OF SINTERING KINETICS IN NANOCRYSTALLINE ALUMINA POWDERS BY ELECTRIC PULSING: R.S. Mishra, A.K. Mukherjee, Dept. of Chemical Engineering and Material Sciences, University of California, Davis, CA 95616 Plasma activated sintering (PAS) involves application of electric pulsing before the sintering cycle. A comparative study has been carried out on nanocrystalline alumina powders with y and a starting phases. The results obtained with and without electric pUlsing clearly establish the enhanced sintering kinetics due to prior electric pulsing. These results are explained on the basis of dielectric properties of the powders. In addition the present results show that the powder with a-phase sinters better. High densities (>98%) can be obtained in less than 10 minutes at 1573 K. The time and temperature are significantly lower as compared to the conventional sintering parameter of 1773 K and 3 h. The reason for slower sinterability of powder with y-phase is linked to formation of vermicular structuring during transformation to a-phase. Examples of obtaining sintered products with simple shape in one step using PAS would be shown.
10:10am SELF SINTERING AND BONDING USING ELECTROEXPLODED NANOSIZE ALUMINUM POWDERS: Henry R. Piehler l, Gennady V. Ivanov 2, Frederick Tepper3, lDept. of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213; 2Institute of Petroleum Chemistry, Academy of Sciences, Tomsk, Russia; 3Argonide Corp., Gateway Towers, Pittsburgh, PA 15222 Aluminum powders approximately 100 nanometers in diameter, made by the process of electroexplosion of wire in argon, have stored surface and strain energy that is released at threshold temperatures well below the melting point. This energy release and accompanying temperature increase allows self sintering and bonding to occur at relatively low temperatures. We studied the self sintering of nanosize aluminum powders made by electroexplosion by heating cold compacted pellets to 450°C, at which point they exothermed with the generation of light and sufficient heat to partially melt the pellets. Preliminary results are also reported for bonding conventional aluminum powders and sheets using the energy release and temperature increase from exotherming nanosize electroexploded aluminum powders.
STRUCTURE AND PROPERTIES OF BULK AMORPHOUS ALLOYS III Sponsored by: Jt. EMPMO/SMO Alloy Phases Committee, MSO Thermodynamics and Phase Equilibria Committee, MSO Atomic Transport Committee, MOMO Solidification Committee, Lawrence Livermore National Laboratory and Los Alamos National Laboratory Program Organizers: Patrice E.A. Turchi, Chemistry and Materials Science Department (L-268), Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551; Ricardo B. Schwarz, Center for Materials Science (MSK765) , Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545; John H. Perepezko, Department of Materials Science and Engineering, University of Wisconsin, Madison, WI 53706
10:35 am FREE FROM FABRICATION OF HIGH STRENGTH METAL COMPONENTS & DIES: c.c. Bampton i , K. NewelJI, S. Fowser2, lRockwell Science Center, Thousand Oaks, CA 91358; 2Rocketdyne, DeSoto Avenue, CA91303 A two-staged method has been developed for free form fabrication of nickel and iron based alloy parts directly from alloy powders without the need for tooling or machining. The method provides shape and property control equal or superior to investment castings in the same base alloys. A major advantage of the approach is the ability to utilize commercially available selective laser sintering systems with virtually no modification from their standard configurations as intended for plastic model generation direct from CAD data bases. We have demonstrated the feasibility of shape, dimension and property control for complex, low production volume rocket engine components and for tools and dies intended for higher volume commercial production applications in fully hard commercial steels and superalloys. A new finite element model has been developed specifically to aid in control of sinter densification without distortion or cracking.
Tuesday, AM February 11, 1997
Room: 340A Location: Orlando Convention Center
Session Chairperson: Prof. John H. Perepezko, Department of Materials Science and Engineering, University of Wisconsin, Madison, WI 53706
8:30am COMPUTER SIMULATIONS OF THE STRUCTURAL, DYNAMIC, ELECTRONIC AND MAGNETIC PROPERTIES OF AMORPHOUS ALLOYS: 1. Hafner, Institut fiirTheoretische Physik, Technische Universitat Wien, Wiedner Haupstrasse 8-10/136, A-1040 Wien, Austria
11:00 am
There is hardly any area in materials science where the necessity to supplement the experimental information acquired in the laboratory by the results of computer experiments is felt as urgently than for liquid and amorphous materials. The classical example is the structure: whereas laboratory experiments describe a one-dimensional projection of the three-dimensional structure, the computer-simulation delivers the full set of the atomic coordinates. During the last years, a wide variety of computational tools have been developed. These techniques can essentially be classified in three groups: (a) Ab initio local-density Junctional techniques in the spirit of the Car-Parrinello method. While in this approach no further assumption beyond the reduction of the many-electron Hamiltonian to an effective one-electron form is re-
DEVELOPMENT OF A MANUFACTURING PROCESS FOR AFFORDABLE, COMPLEX NET SHAPE PIM COMPONENTS: Ellen W. Robare, Clifford M. Bugle l, Tony E. Zahrah, Phillip A. Parrish 2, lDynamet, Inc. Washington, PA 15301;2MATSYS, Inc., Arlington, VA 22209 This paper describes the background and progress of a research and development effort called Rapid Net Shape Forming. This effort involves the development and reduction to practice of a process, known as the MetalShell process, for manufacturing complex net shape powder metal components. The process involves the use of electroformed nickel to create a net shape HIP canister. One of the outstanding features of the process is that it can be used
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on-site and many-body interactions which build up the configurational part of the total energy are computed. With this energetics, Monte Carlo simulations based on the Kawasaki spin-exchange dynamics are performed to predict chemical short-range order in amorphous alloys. The relaxation of the lattice is performed with TB-molecular dynamics simulations, and the overall scheme can be reiterated to self-consistency. Advantages of this global scheme are discussed and application to Zr-Ni alloys are presented. Work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under contract No. W-7405-ENG48. Partial support from NATO under contract CRG 941028 is gratefully acknowledged.
quired, the massive computational effort restricts the application to models with at most a few hundred inequivalent atomic sites. (b) A variety of tightbinding (TB) based techniques (ranging from TB molecular dynamics (MD) and Monte Carlo (MC) to tight-binding-bond approaches to many-atom forces) allow to treat larger systems, albeit at lower accuracy. (c) Classical MD and MC based on effective interatomic pair and volume forces derived via effective-medium approximations, pseudo-potential theory, TB-moment expansions ...etc. In this talk I shall attempt to review the state-of-the-art of the computer-modeling of the structural, dynamic, electronic and magnetic properties of amorphous alloys. This work has been supported by the Bundesministeriurn fur Wissenschaft, Forschung und Kunst through the Center for Computational Materials Science.
11:30 am FREE VOLUME, PERCOLATION,AND GLASS TRANSITIONS: Mo Li, W.M. Keck Laboratory of Engineering Materials 138-78, California Institute of Technology, Pasadena, CA 91125
9:10am AB INITIO STUDIES OF THE ELECTRONIC STRUCTURE AND ENERGETICS OF BULK AMORPHOUS ALLOYS: G.M. Stocks, D.M.C. Nicholson, Y. Wang, X.-D. Wang, C.L. Fu, W.A. Shelton, Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008-6114, Oak Ridge, TN 37831-6114; J.C. Swihart, Physics Department, Indiana University, Bloomington, IN 47405
Free volume model is examined systematically and quantitatively in a model binary liquid using molecular dynamics simulations. It is found that at the glass transition, the liquid-like cells undergo a percolation transition. However, further analysis shows that free volumes do not exhibit any cooperative behavior at the percolation threshold. The continuous change in thermodynamic and transport properties suggests that the glass transition is kinetic in nature. Implication of the percolating properties of the free volumes in transport properties of undercooled liquids will also be discussed.
We present results of first-principles LDA calculations of the electronic structure and energetics of NiJd40P2o and Zr,;oAI!SNi"s bulk amorphous alloys based on large unit cell (about 300 atoms) structural models of the amorphous state. The calculations are made tractable by the order-N locally selfconsistent multiple scattering (LSMS) method implemented on massively parallel computers. For the Zr2Ni-based system, we have also studied the energetics and bonding of some competing stable and metastable ordered phases into which the amorphous state decomposes. The implications of these calculations for understanding the unusual stability of bulk amorphous alloys will be stressed. Work sponsored by ORNL Laboratory Directors Research and Development fund, BES-DMS and OCTR-MICS USDOE, under contract DE-AC05-960R22464 with Lockheed-Martin Energy Research Corporation.
STRUCTURE AND PROPERTIES OF INTERNAL INTERFACES III: Interfacial Diffusion and Transformations Sponsored by: Jt. EMPMDISMD Chemistry & Physics of Materials Committee, MSD Computer Simulation Committee Program Organizer: Diana Farkas, Dept. of Materials Science and Engineering, Virginia PolytechniC Institute and State University, Blacksburg, VA 24061; Elizabeth A. Holm, Sandia National Lab, Physical and Joining Metallurgy, MS 1411, Albuquerque, NM 87185-0340; David J. Srolovitz, Dept. of Materials Science & Engineering, University of Michigan, Ann Arbor, M148109-2136
9:50am ELECTRONIC STRUCTURE AND RELATED PROPERTIES OF METALLIC GLASSES: LINEAR MUFFIN- TIN ORBITALS CALCULATIONS: S.K. Bose, Physics Department, Brock University, St. Catharines, Ontario L2S 3AI, Canada
TuesdaY,AM February 11, 1997
We describe various aspects of electronic structure calculation for metallic glasses using the Linear Muffin-Tin Orbitals (LMTO) scheme. A method of calculating the electronic transport properties based on the LMTO-recursion method and the Kubo-Greenwood formula is discussed. The practical limitations of the method and the ways to overcome them are presented. We discuss calculations of the magnetic properties within the framework of multiple scattering formalism assuming collinear magnetic structure and using the Linear Muffin-Tin Orbitals Green's Function (LMTO-GF) method. Results for the effective exchange coupling parameters and local magnetic moments for amorphous Fe and Co are discussed with special emphasis on the dependence of these quantities on the local and global features of the structure. A simple interpolation scheme, based on the electronic properties of the pure components, is proposed for estimating the spin fluctuation effects in transition metal glasses.
Room: 330G Location: Orlando Convention Center
Session Chairperson: David N. Seidman, Northwestern University, Materials Science and Engineering Dept.lMLSB, 2225 North Campus Drive, Evanston, IL 60208-3108
8:30 am INVITED TEMPERATURE AND CONCENTRATION DEPENDENCE OF GRAIN BOUNDARY-DIFFUSION OF 63Ni IN PURE AND BORONDOPED Ni3Al: Stefan Frank!, Jorg Riising2 and Christian Herzig!, 1Jnstitut fur Metallforschung, Universitiit Miinster, Germany, 2now: Hahn-MeitnerInstitut, Berlin, Germany Knowledge about the diffusion behaviour in the grain boundaries of pure and of boron-doped Ni3Al is of basic importance to improve our understanding of the boron-effect and the mechanical properties of polycrystalline Ni3Al. We report on a first study of grain boundary diffusion in pure and doped Ni-rich Ni3AI polycrystals. Diffusion penetration profiles were determined by a serial sectioning technique using a precision parallel grinding device. The low energy ~-decays of the 63Ni tracer were detected by liquid scintillation counting. The high efficiency allowed to significantly increase the detectable concentration range of the measured profiles and provided the basis for investigating grain boundary self-diffusion in Ni3Al in a meaningful way. For comparison grain boundary self-diffusion in pure Ni was re-investigated in true type R -kinetic. It is known that the temperature dependence of the grain boundary diffusion parameter P= BDgb of 63Ni in pure Ni and in both Ni3Al materials is of the Arrhenius type. The absolute values of P follow the sequence P Ni>P Ni3AI>P Ni3Al+ B. The remarkably higher activation enthalpy Qgb (Ni3AI) in comparison with Qgh (Ni) can be attributed to the grain boundary structure of the strongly ordered Ni3AI compound. Ni-diffusivity in the
10:30 am BREAK 10:50 am REAL-SPACE ELECTRONIC STRUCTURE APPROACH TO CHEMICAL ORDER IN AMORPHOUS ALLOYS: P.E.A. Turchi, Lawrence Livermore National Laboratory (L-268), P.O. Box 808, Livermore CA 94551; D. MAYOU, LEPES-CNRS, 25 Avenue des Martyrs, BP 166, F-38042 Grenoble Cedex 9, France A recently developed real-space approach for studying the electronic structure properties of materials which exhibit both chemical and topological disorders is presented, within the tight-binding framework. For a chemically random alloy, we show that the Coherent Potential Approximation (CPA) equations can be solved self-consistently in real-space with the same accuracy as is currently done in reciprocal space, in the case of homogeneous and inhomogeneous systems. Based on the orbital peeling technique, effective
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doped alloy is about 2-3 times lower than in pure Ni3Al. A prospective reason for the decreased diffusivity is the segregation of B and the thereby enhanced cosegregation of Ni in the grain boundaries. The strong segregation of boron leads to a certain blocking of diffusion paths of the Ni atoms. High angle grain boundary energies in pure and R-doped Ni3Al are derived from the diffusion data applying the Borisov et al.relation. The effect of stoichiometry on grain boundary self-diffusion in Ni3Al was investigated for compositions between 73 and 78 at% Ni. A V-shaped concentration dependence of P with a minimum at near 75 at% Ni was observed which becomes very distinct at lower temperatures. At e.g. 1066 K P increases by about one order of magnitude from stoichiometric to Ni-rich Ni3Al. This behaviour is related to the change in composition and state of order of grain boundaries in non stoichiometric NiJAI.
was much more complicated that the original Ivantsov equation. In a recent publication by us" the advantage of the modem development of computational thermodynamics was taken and the Ivantsov equation was then used directly with the actual composition after taking into account the interfacial energy and the finite interfacial mobility. It was pointed out by a reviewer that this approach was not self evident if it is identical to Trivedi's modification. In the present report, we will formulate a consistent framework to describe the phenomena.
10:10 am MICROSTRUCTURAL CHARACTERIZATION OF TiAl3 PRODUCT LAYERS IN AICuSiffi AND AICuffi REACTION COUPLES: C. Wauchope, J.E. Sanchez, Jr., University of Michigan, Ann Arbor, MI48109; P.R. Besser, R. Alvis, Advanced Micro Devices, Sunnyvale, CA 94088
9:10am CALCULATIONS OF DIFFUSION AND SEGREGATION IN AI-Cu GRAIN-BOUNDARIES: X.Y. Liu, J.B. Adams, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 105 South Goodwin Avenue, Urbana, IL 61801; Wei Xu, Lawrence Livermore National Laboratory, University of California, Livermore, CA 94551 We have studied the atomistic mechanisms of electromigration in AI-Cu, in specific, the diffusion of atoms and segregation of Cu atoms in the Al grainboundaries with a newly developed EAM interatomic potential constructed by the Force-Matching Method. The potential parameters are fitted to available experimental data plus ab initio force database. The energetic and structural properties of Cu segregation and the effect in atomic diffusion path and activation barriers are studied. The grain-boundary calculations, in agreement with ab initio results, show that the Cu segregation is dominated by size effects in the AI-Cu system, i.e., Cu atoms segregate to sites which are locally compressed. In the case of aLII tilt boundary, this predicts that the Cu will segregate to sites away from the symmetric center of the boundary.
Metallization interconnects in advanced integrated circuits are typically fabricated from Al alloy (500-1000nm)tri (20-50nm) multilayer thin films. The Ti provides several effects in the Al layer; improved reliability against electromigration-induced failure, reduced Al grain size, increased Al (111) fiber texture, and reduced Al thickness due to Ti+Al reaction to form TiAI J. The TiAI J reaction occurs during thermal processing and device fabrication, and leads to increased line resistance as the Al thickness is reduced. We present detailed cross-section transmission electron microscopic analysis of TiAI J layers formed in AICuSitri and AICuffi reaction couples. Results show that the Al alloytriAIJ and TiAIJtri interfaces are "clean" and free of intermediate phase layers. In addition local energy dispersive x-ray spectroscopy (EDS) analyses show Si partitioning in the TiAl3region in AICuSifTI samples. The TiAIJ grain size is roughly independent of Al alloy type, and depends primarily on total TiAI J thickness. These results are described in terms of models which describe the effects of Cu and Si alloying additions on the TiAl3 formation kinetics, in particular to the Ti+Al reaction rate dependence on the TilAICuSi thickness ratio.
9:30am
10:30 am BREAK
ATOMISTIC SIMULATION OF GRAIN BOUNDARY STRUCTURE AND DIFFUSION IN B2 NiAI: Yuri Mishin, Diana Farkas, Virginia Polytechnic Institute and State University, Materials Science and Engineering Department, Blacksburg, VA 24061
10:50 am INVITED STRUCTURE, COMPOSITION AND THERMAL STABILITY OF METAUCERAMIC INTERFACES: Manfred Riihle, Max-Planck-Institut flir Metallforschung, Seestr. 92, D-70174 Stuttgart, Germany
We modify the existing embedded-atom potentials for NiAI by fitting them to self-diffusion data for pure Ni and Al and to the triple-defect model for this compound. Using the modified potentials and molecular statics we calculate the structure, excess energy and cohesive energy of [00 1] tilt grain boundaries in NiAI. The calculations are performed for 25 orientations with $\sigma$ values from 5 to 185. For each orientation the lowest-energy stoichiometric boundary structure is established. Low-$\Sigma$ orientations are associated with minima of the boundary energy and maxima of the cohesive energy. The boundary structures obtained are analyzed in terms of the structural unit model. For two lowest-energy boundaries, $\Sigma=5$ (210) and $\Sigma=13$ (230), we simulate tracer self-diffusion in the boundary core both parallel and normal to the tilt axis. We assume the vacancy mechanism and calculate the vacancy formation and migration energies in the boundary core. To calculate the boundary diffusion coefficients we use the technique proposed recently by one of us [Phil. Mag. A 72, 1589 (1995)]. This technique combines the matrix method with Monte Carlo simulations of individual vacancy-tracer encounters. The effective activation energy is calculated in a wide temperature range and compared with the spectrum of individual jump energies in the boundary. The results are discussed in terms of the grain boundary mass transport and its effect on high temperature properties of NiA.
Metallceramic interfaces play a crucial role in different areas of materials science such as metallic interconnects in semiconductors, adhesion of oxide scales on metal substrates, thermal barrier coating, composites and bonding between bulk parts of metals and ceramics. It is of great interest to correlate the microstructure of those interfaces to their properties. The possibilities of getting information on the structure and composition of metallceramic interfaces will be discussed for several systems. The focus will be mainly on model systems (CuJAIPJ' NilAIP3' Nb/AIPJ) but also applications for real materials will be discussed. Segregation of impurities may lead either to an increase or decrease of the adhesion. Therefore, it is crucial to determine those impurities as accurately as possible. Metal/ceramic interfaces are often exposed to high temperatures at different atmospheres. Therefore, the thermal stability under service conditions is of great interest. The paper will describe recent advances and possibilities of determining the structure, composition and chemical reactions at those interfaces by conventional transmission electron microscopy, high-resolution transmission electron microscopy and analytical electron microscopy. The results of experimental studies will be compared to results of ab-initio first principles calculations and to experimental studies on the adhesion of metal films on ceramic substrates.
9:50am
11:30 am
THE IVANTSOV GROWTH EQUATION AND INTERFACIAL KINETICS: Zi-Kui Liu, Y. Austin Chang, Department of Materials Science and Engineering, 1509 University Avenue, University of Wisconsin-Madison, Madison, WI 53706
THE Al/Ni AND AlICu INTERFACIAL REACTIONS UNDER THE INFLUENCE OF ELECTRIC CURRENT: Wen-Chyuarn Liu, Sinn-wen Chen, Department of Chemical Engineering, National Tsing-Hua University, Hsin-Chu, Taiwan 30043, China
The growth equation of parabloid was first derived by Ivantsov' and later modified by Trivedi' to take into account the interfacial energy and finite interfacial mobility (interfacial kinetics). The modification was done by first considering the effects of the interfacial kinetics and the interfacial energy and curvature, and then solving the diffusion equations on the composition at the interface. Though the modification was necessary, the growth equation
Electromigration has been observed and quite extensively investigated in the integrated circuit devices with the electric current density higher than 105 AI cm2• The electric current density in the electronic packaging was usually lower and the effect of electromigration has not been discussed. This study investigated the effect of weaker electric current, up to 103Alcm2, upon the chemically-driven interfacial reactions in the AlINi and AlICu systems by analyz-
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ing their reaction couples. The reaction couples would be heated by the passing-through electric current. The temperatures of the reaction couples increased with the increasing electric density. Annealed at the same temperatures, similar results were found for the reaction couples with and without the passingthrough electric current. Same intermetallics, such as APNi and APNi2 , were formed at the interfaces, and the thickness of the reaction layers was the same. It was concluded that the electric current density up to 103 Alcm2 has little effect upon the interfacial reactions in the Al/Ni and AI/Cu systems.
sidual stress. The choice between a hand forging/die forging or plate is often dictated by the height of the final part. Since plate can be more efficiently stress relieved - by stretching - it is the preferred choice whenever the thickest available plate can accommodate the part. In the last couple of years, plate producers have strived to raise the upper limit of the thickness range from, say, 150 mm to 250 - 300 mm. In so doing, might exceed the capacity of existing stretching presses, which necessitates the use of an alternative stress-relieving method e.g. stepwise cold compression. With respect to the resulting residual stress level, one could ask the question to which extent the relative advantage of plate over forging is preserved in this case. An earlier investigation of the relationship between stress-relieving of die forgings, residual stresses and distortion during machining is recapitulated to give a background to the present work, which involves measurement of through-thickness stress variations in 100 and 150 mm thick plate, stress relieved by stretching, and in cold compressed plate of 200 mm thickness.
SYNTHESIS OF LIGHT-WEIGHT METALLIC MATERIALS II: Metallic Compounds III: Alloying, Thermomechanical Processing and Microstructural Control
9:10am TEXTURE CONTROL OF ALUMINUM ALLOY SHEETS: C.-H. Choi, K.-H. Kim, D.N. Lee, School of Materials Science and Engineering and Center for Advanced Materials Research, Seoul National University, Shinrimdong, Kwanak-ku, Seoul 151-742, Korea
Sponsored by: MSD Synthesis/Processing Committee Program Organizers:C.M. Ward-Close, Structural Materials Center, R50 Building, Defense Research Agency, Farnborough, Hampshire, GU14 6TD, United Kingdom; F.H. Froes, University of Idaho, Institute for Materials and Advanced Processes, Mines Bldg 204, Moscow, ID 83844-3026; D.J. Cheliman, Lockheed Aeronautical Systems Co., Lockheed Corporation, Marietta, GA 30063-0150; S. S. Cho, Vice President of Rapidly Solidified Materials Research Center, (RASOM), Chungnam National University, Taedok Science Town, Taejon 305-764 Korea Tuesday, AM February 11, 1997
In order to achieve good deep drawability it is imperative to obtain well developed {l1l }texture which gives rise to the higher plastic strain ratio. It is difficult to obtain the texture from conventional rolling and annealing processes. Therefore an unconventional rolling process which causes shear deformation has been introduced in addition to the conventional rolling process. Various combinations of the conventional and unconventional rolling processes and the annealing process have been theoretically and experimentally studied to obtain the well developed {Ill }texture which in turn gave rise to a substantial increase in the plastic strain ratio.
Room: 330F Location: Orlando Convention Center
Session Chairpersons: P. Grant, University of Oxford, Department Of Materials, Parks Road, Oxford OX1 3PH, UK UK; D. Upadhyaya, University of Idaho, Institute for Materials and Advanced Processes, Mines Bldg 204, Moscow, ID 83844-3026
9:30am THERMO-MECHANICAL BEHAVIORS OFAI-Ni-MmAMORPHOUS ALLOYS: S.J. Hong, H.S. Kim, c.w. Won, S.S. Cho, B.S. Chun; Department of Metallurgical Engineering and RASOM, Chungnam National University Kung-dong, Yuseong-gu, Tacjeon 304-750, KOREA; P.Warren, B. Cantor, OCAMAC, Department of Materials University of Oxford Parks Road, Oxford, OXI 3PH, UK
8:30am THERMODYNAMICS OF VACUUMTHERMIC REDUCTION OF LIGHTWEIGHT MAGNESIUM-LITHIUM ALLOY: Dajian Wang, Department of Metallurgy, Kunming University of Science and Technology, Kunming, Yunnan 650093, China The principles of preparation of light weight alloy of Mg-Li alloy with a lowdensity less than Ig1Cm3 with vacuumthermic reduction are described according to the preliminary laboratory-scale results. The process involves the use of ferrosilicon and aluminium to reduce magnesia and lithium oxide concurrently in a vacuum furnace to mixing gas of metallic magnesium and lithium due to the higher pressures for both magnesium and lithium. The metallic vapours are cooled at the lower temperature part of the furnace. Thermodynamic analysis of related reactions and their equilibrium constants revealed the probabilities of reactions and preferable reductants of ferrosilicon or aluminium. The alloying effects at low pressure of reduced magnesium and lithium and their evaporation may significantly dominate the progress of the process. Based on the calculation determination of activity coefficients of components in Mg-Li binary, the thermodynamic aspects for both reduction process and vaporisation process are systematically analysed in the paper.
The Al-M-Mm (Mm=misch metal) alloys have been produced by a gas atomization, a sing roll melt spinning and a twin roll spinning methods. These alloys have amorphous structure, finely mixed structure consisting of aluminium phase, intermetallic compounds homogeneously embedded in the ultrafine "rained aluminium matrix and intermetallic compounds in the large "rained aluminium matrix depending on the process variables. The alloy powders and ribbons have been warm compacted to various relative densities at various temperatures. The cylindrical and ring shapes compacts have been upsetted at various temperatures and the plastic deformation behaviours have been investigated using TEM, DSC and XRD. The density distribution, load, deformed geometry, friction coefficient, interparticle bonding behavior have been compared with the theoretically calculated ones. The forming limit diagrams have obtained from the ring compression tests. 9:50am MICROSTRUCTURES AND MECHANICAL PROPERTIES OF AZ91 AND AM60 MG ALLOYS BY TWIN ROLL PROCESS: S.S. Cho, B.S. Chun, c.w. Won, B.S. Lee, H. Baek, K.H. Yim, Department of Metallurgical Engineering and RASOM, Chungnam National University Kung-Dong, Yusong-gu, Taejon 304-750, KOREA EH. Froes, Institute for Materials and Advanced Process, University of Idaho, Mines Building, Room 321 Moscow, Idaho 83844-3026
8:50am STRESS RELIEVING METHODS FOR THICK ALUMINIUM ALLOY PLATE: EVALUATION BY X-RAY DIFFRACTION RESIDUAL STRESS MEASUREMENT: Bernt Jaensson,_ CSM Materialteknik AB, Box 13200, S-58013 Linkoping, Sweden; Alfred Heinz, Hoogovens Aluminium Walzprodukte GmbH, Postbox 920, D-56009 Koblenz In the design of metallic structural parts for aircraft there are, basically, two approaches that can be taken: either the part is built up from a number of individually formed elements which are joined by riveting or adhesive bonding, or the part is sculptured from a single forging or piece of plate. In this situation, designers of small aircraft tend to use the first approach, while integrally machine parts are dominant in the structure of large aircraft. However, the balance between the two options is also changing with time, in that presentday aircraft engineers are increasingly favouring the sculpturing method. Contributing to this trend is the availability of numerically controlled highspeed milling machines, as well as forgings and plate with low levels of re-
It is well known that Mg alloys are quite attractive for structural use in aerospace and automotive industry due to the light weight. The properties of RS AZ91 and AM60 Mg alloys by twin roll cast will be compared with commercial ingot metallurgy alloys. The process including flake production, degassing, cold compaction and hot consolidation will be discussed. The Corrosion behavior will be also discussed. 10:10 am BREAK
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10:30 am MECHANICAL PROPERTIES OF Mo-AI ALLOYS BY TWIN ROLL PROCESS: S.S. Cho, B. S. Chun, C.w. Won, S.D. Kim, B.S. Lee, H. Baek, Department of metallurgical Engineering and RASOM, Chungnam National University Kung-Dong, Yusong-gu, Taejon 304-750, Korea; F.H. Froes, Institute for Materials and Advanced Process, University ofIdaho, Mines Building, Room 321 Moscow, Idaho 83844-3026
the form of powder by attritor mill and then vacuum hot pressed IDS(intermetailic-dispersion-strengthened) Al alloys prepared in this way were analyzed in terms of phase stabilities and microstructures through XRD, SEM and TEM methods. 11:30 am EFFECTS OF MICROALLOYING WITH Ce, Ni AND Si ON THE BEHAVIOUR OF INGOT ALUMINIUM ALLOY: C912 (AI-Zn-mgCu): Y.L.Wu', G.G. Li', F.H. Froes' andJ. Liu', 'BIAM, POBox 81, Beijing 100095, China; 'IMAP, University of Idaho, Moscow, Idaho 83844-3026; 3Alcoa Technical Center, 100 Technical Drive, Alcoa Center, PA 15069-0001
Rapid solidification processing(RSP) has been exploited to improve mechanical properties of materials. This study will focus on the process including the production of flake by twin roll cast, degassing, cold compaction and hot extrusion. The properties of experimental Mg-AI alloys are compared with ingot metallurgy alloys. The corrosion and wear behavior will be discussed.
The present paper will discuss the effects of rnicroalloying with Ce, Ni and Si on the behaviour of the ingot aluminium alloy C912 (AI-9Zn-2Cu-2Mg). The relationship between the chemistry, processing, microstructure and mechanical behaviour will be present for direct chill cast ingots which were subsequently extruded. Preliminary results show that this alloy class can exhibit attractive combination of strength and corrosion resistance.
10:50 am NUMERICAL ANALYSIS OF MICROSEGREGATION IN ALALLOY WELD METALS: C.H. Lee, E. P. Yoon; RASOM, Dept. of Met. Eng., The Hanyang University, Seoul, Korea, 133-791 During solidification of alloys under rapid thermal excursion of welds, the solute redistribution brings out microsegregation. The microsegregation causes the formation of non-equilibrium second phases, shrinkage and porosity degrading properties and forming solidification crack. Therefore, it has been required to predict microsegregation quantitatively. To predict the degree of microsegregation, more exact and appropriate computer simulation technique has been being actively used during last two decades. In this study, an advanced two dimensional model was suggested on the basis of the previous one and two dimensional models. In the new model, both primary and secondary arm regions were defined for the analysis region. Before calculation of microsegregation, the analysis region was determined by the theoretical equation for the primary and secondary arm spacing. The growth in the primary arm region was assumed to be a planar for effective calculation. Especially, for the growth of a secondary arm, a simple and effective mathematical function was established to show the growing pattern(polynomial interface). The solute diffusion in the solid phase was calculated by finite difference method (FDM). The solid-liquid interface movement was considered to be in local eqUilibrium state indicated by the phase diagram.
11:50 am PHASE STABILITY OF AI66Mn. (Ti, Zr)zs-DISPERSION STRENGTHENED ALLOY: S.Z. Han, S.1. Park, S.-J. Kim*, H.M. Lee, Dept. of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Kusung-Dong 373-1, Yusung-Gu, Taejon, Korea 305-701 In addition of Mn to the tetragonal AI,(Ti,.xZrx) phase produced cubic Ll,type A166Mu. (Ti, Zr)" phase with a small amount of second phases such as AI,Mn, and AI,Zr, still existing in the as-cast state. Second phases disappeared when intermetallic compunds were homogenized at 1000°C for 26 hours. After homogenization, intermetallic compunds were mixed with pure Al in the form of powder by attritor mill and then vacuum hot pressed. IDS (intermetallic-dispersion-strengthened) Al alloys prepared in this way were analyzed in terms of phase stabiliites and microstructures through XRD, SEM and TEM methods. 12:10 pm SOLIDIFICATION PROCESSING FOR THE PRODUCTION OF FINE GRAIN ALUMINUM ALLOY MATERIALS: Akira Sato, Garo Aragane, Yoshiaki Osawa, and Susumu Takamori; National Research Institute Far Metals, Tsukuba, Ibaraki 306 Japan
11:10am PHASE STABILITY OF Ab66Mn.(TI, Zr)zs-DISPERSION-STRENGTHENED AI ALLOY: Seung-Zeon Han, Seong II Park, ·Seon-Jin Kim, HyuckMo Lee, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Kusung-Dong 373-1, Yusung-Gu, Taejon, Korea 305-701; *Department of Materials Engineering, College of Engineering, Hanyang University, Hacngdang-Dong 17, Seongdong-Gu, Seoul, Korea 133-791
It is well-known that metallic materials having fine grain crystal structures possess high mechanical properties, ie., high strength and at the same time high toughness. A new process named "Rapid solidification with vigomus agitation" is developed to produce large ingots having fine grain and homogeneous structures. The molten alloys are rapidly solidified with watercooled copper molds and at the same time stirred vigorously by graphite rods during falling down of the melt through the gap between the mold and the rod. The results obtained using Al-Si alloys are as follows. The mean grain size of primary crystals in slurry become smaller with increasing the intensity of cooling and the rotation speed of stirring rod. Prim
The addition of Mn to the tetragonal AI,(Ti'.xZrx) phase produced cubic Ll,type AI66 Mn.(TiZr)2, phase with a small amount of second phases such as AI,Mn, and AI2Zr, still existing in the as-cast state. Second phases disappeared when intermetallic compounds were homogenized at lOOO°C for 24hr. After homogenization, intermetallic compounds were mixed with pure A 1 in
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aids in cold forming of steel and increases the lubricant power of oil applied to the pieces subjected to friction and wear. The influence of galvannealed morphology on the phosphate crystal feature is not well understood. In this work, a tricationic phosphate coating was applied to a surface of a low carbon steel and an interstitial free steel with galvannealed coating. Our paper will discuss the structural and mechanical properties resulting from this treatment.
ADVANCES IN COATINGS TECHNOLOGIES II: Session IV Sponsored by: MDMD Surface Modification & Coatings Technology Committee Program Organizers: C.R. Clayton, State University of New York at Stonybrook, College of Engineering and Applied Sciences, Stony Brook, NY 11794-2200; J.K. Hirvonen, US Army Materials Technology Lab., Arsenal St., Watertown, MA 02172; A.R. Srivatsa Tuesday, PM February 11, 1997
2:30pm PROGRESS TOWARD THE DEVELOPMENT OF DENDRIMERBASED PROTECTIVE COATING: Larry A. Milco, Donald A Tomalia, Michigan Molecular Institute, 1910 W. St. Andrews Road, Midland, MI 486402696
Room: 315B Location: Orlando Convention Center
Session Chairperson.' TBA
There is a considerable demand for thin film coatings to which other substances will not stick. Coatings are required to protect surfaces from soils, stains, ice, graffiti, insects, oils, corrosion and chemical and biological contaminants. Moreover, as legislative pressures to remove volatile organic solvents from coating formulations persist, the demand for alternative waterborne systems continues to increase. The incorporation of dendritic polymers in non-stick coating formulation is a highly viable approach to overcoming the limitations associated with conventional polymer systems. Non-stick coatings were prepared by crosslinking dendrimers with linear polymers. The high advancing and receding contact angles and low contact angle hysteresis of water and hexadecane on the coatings are indicative of the non-stick (low adhesion) properties of these surfaces.
1:30pm ELECTRODEPOSITED Ni-Al PARTICLE COMPOSITE COATINGS: D. F. Susan, K. Barmak, A.R. Marder Department of Materials Science and Engineering, Lehigh University Bethlehem, PA 18015-3195 Electrodeposited metal matrix/metal particle composite coatings (EMMC's) were deposited, heat treated, and characterized. Nickel matrix/aluminum particulate coatings deposited on a nickel substrate was chosen as a model system. The microstructure of the as-plated and heat treated coatings was characterized using light optical microscopy (LOOM), SEM, quantitative image analysis (QIA), and EPMA. A schematic model is presented for coating morphological development during codeposition of small, electrically conducting particles. The heat treated coatings consist of a two phase mixture of y solid solution and Ni3Al (gamma-prime) with small Kirkendall voids also present. The hardness of the heat treated coatings increased with increasing Ni3Al content and remained constant with extended heat treatment time. Oxidation tests were performed isothermally in air at 800, 900, and 1000 C for up to 900 hrs. and the depth of the oxidation attack was determined. Throughout the investigation, the Ni-Al coatings were compared to conventional pure Ni coatings deposited under similar conditions.
3:05pm PULSED LASER DEPOSITION OF COLLAGEN AND APATITE/COLLAGEN COMPOSITE BIOCOMPATIBLE THIN FILMS: lA. Conklin, C.M. Cotell, Surface Modification Branch, Code 6671, U.S. Naval Research Laboratory, Washington, D.C. 20375 Thin films comprising either collagen or a composite of hydroxyapatite (HA) and collagen were deposited by pulsed laser deposition (PLD) on various substrates. Films were deposited using either a KrF (248nm) or ArF (l93nm) excimer laser and the substrates were maintained at room temperature. Collagen films were characterized by SEM, Fourier transform infrared (Ff-IR) spectroscopy and gel electrophoresis. The functional groups on the collagen molecule remained intact through the laser ablation process, but there was evidence for some loss of secondary structure. In addition, the surface morphology was a function of the laser fluence and the gas environment during PLD. Less denaturation of the molecule was observed when the ablation was at 193nm than at 248nm. For the composite films, the target material consisted of a 70/30 (by weight) mixture of apatite/collagen, the same ratio found in bone. The resulting composite films were a homogenous mixture of amorphous collagen and highly crystalline apatite.
1:50pm FORMATION OF TIDN COLORED FILM ON STAINLESS STEEL: G.S.Gupta, Dept. of Mining, Minerals and Materials Engineering, The University of Queensland, St.Lucia, Queensland - 4072, Australia Formation of colored film on type 304 stainless steel has been studied using chromic acid and potassium dichromate solutions. Permanent colors have been obtained using immersion and electrolytic (potentiostatic) methods. The effect of different parameters on the coloring process including temperature, coloring methods, solution composition, stirring, surfactant etc., have been noted. Moderate temperature of the solution, electrolytic method, use of surfactant and stirring of the solution were found to enhance the coloring process. A coloring solution which is strongly oxidized and acidic in nature is recommended. It is advisable that after the extended use of the coloring solution, fresh solution should be used.
3:40 pm BREAK 4:00pm PROTEINS FROM OYSTER SHELL AS MODELS FOR BIODEGRADABLE COMMERCIAL POLYMERS: A.P. Wheeler, Department of Biological Sciences, Clemson University, Clemson, SC 29634
2:10pm TRICATIONIC PHOSPHATE COATING ON GALVANNEALED STEEL SHEET: Carlos Nelson Elias, Mila Marques Justo, Escola de Engenharia Metaurgica de Volta Redonda, Av dos Trabalhadores 420, 27260 740 Volta Redonda, RJ - Brazil
Virtually all minerals formed by organisms are composites, containing an organic phase (matrix) which enhances the mechanical properties of the inorganic phase and which presumably controls mineral growth. The matrix of the CaC03 shell of oysters contains soluble, highly anionic proteins which in vitro adsorb to mineral and in so doing alter mineral growth. Based on the surface reactive properties of these proteins, synthetic analogs have been made which have properties that make them candidates as inhibitors for mineral scale and corrosion and as dispersants. Synthesis of a simple matrix protein analog, polyaspartic acid, is possible on a significant scale using dry thermal polymerization and aspartic acid as the only reactant. Thermal polyaspartic acid is highly biodegradable when compared to polymers currently used for commercial surface reactive applications.
The galvannealed compared to galvanized steel sheet has excellent paint adhesion, weldability and corrosion resistance after painting. However, the coating tends to cause exfoliation when undergoing severe deformation. This coating is used in the automobile industry. Since the mass loss is very large, it accumulates on the metal mold and results in severe damage to the surface quality of the formed panel affecting press workability and damaging the tool. Nevertheless, phosphating is the most widely used pretreatment, since it serves as an excellent paint base, increases corrosion resistance to metal paints,
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4:20pm THE APPLICATION AND SUBSEQUENT CROSS-LINKING OF A BIOLOGICAL POLYMER ON ALUMINUM METAL: Douglas C. Hansen, Naval Research Laboratory, Washington, D.C. 20375-5343
ADVANCES IN SYNTHESIS AND PROCESSING OF METAL CERAMIC MATRIX COMPOSITES II: Sponsored by : MSD Materials, Synthesis & Processing Committee and Jt. SMDIMSD Composite Materials Committee Program Organizers: L.L. Shaw, Dept. of Metallurgy and Materials Engineering, University of Connecticut, Storrs, CT 06269; E.J. Lavernia, Dept. of Mechanical and Aerospace Engineering, University of California - Irvine, Irvine, CA 92717; S. Krishnamurthy, UES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432-1894; E.S. Chen, U.S. Army Research Office, 4300 S. Miami Blvd., Research Triangle Park, NC27709
Biological polymers that are used by organisms in the formation of structural materials and protective coatings are widespread in nature. An example of such a polymer is the protein utilized by the blue mussel Mytilus edulis as a varnish coating on its byssal threads. This protein is of high molecular weight (>100,000) and is unique in containing the catecholic amino acid L-dopa. This protein exhibits high affinity for metals and acts as a substrate for the enzyme catechol oxidase, which catalyzes the two electron oxidation of catechol to o-quinone. This reaction is essential in the formation of a two component sclerotized resin. The adsorption of this protein onto pure aluminum (99.99999%) and subsequent cross-linking of the adsorbed protein results in a significant shift in the critical pitting potential and polarization resistance of the treated aluminum. Atomic Force Microscopy (AFM) measurements clearly show that treatment of the protein adsorbed onto Highly Ordered Pyrolytic Graphite (HOPG) with catechol oxidase results in a stable, varnishlike coating.
Tuesday, PM February 11, 1997
Room:340B Location: Orlando Convention Center
Session Chairpersons: Prof. Enrique J. Lavernia, Department of Mechanical and Aerospace Engineering, University of California, Irvine, CA 92717; Dr. Benji Maruyama, Wright Laboratory/NIST, 2230 10th ST STE 1, WPAFB, OH 45433
4:40pm ADSORPTION OF ADHESIVE PROTEINS FROM THE MARINE MUSSEL, MITILUS EDUUS, ON POLYMER FILMS IN THE HYDRATED STATE USING ANGLE DEPENDENT XPS AND AFM: A.M. Baty, P.K. Leavitt, C.A. Siedlecki, B. J.Tyler, P.A.Suci, R.E. Marchant, G.G.Geesey. Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717-0398
2:00 pm INVITED PRESSURE INFILTRATION TECHNIQUE FOR SYNTHESIS OF ALUMINUM-FLY ASH PARTICULATE COMPOSITES: P.K. Rohatgi, R Q. Guo, H. Iksan, R. Asthana, Materials Department, University of Wisconsin, Milwaukee, WI 53201 Aluminum - fly ash composite was prepared by pressure infiltration technique. Loosely packed beds of cenosphere fly ash (above 55 vol% in the composite) can be successfully infiltrated by molten aluminum under pressure in the range of 0.3-0.7 MPa, and the density of the composite is 1.4 g / cm 3 compared to the density 2.68g/cm3 for aluminum. Cenosphere fly ash particles are very light materials (density: 0.4 - 0.6 glcm3 ). The microstructure of composite showed that there was uniform distribution of fly ash particles in the aluminum matrix. The mechanism of pressure infiltration and the reaction between aluminum and fly ash during infiltration and solidification will be discussed. Selected properties including hardness, microhardness, and compressive strength of aluminum - fly ash composites were determined and the results are presented in this paper.
The adsorption of Mussel Adhesive Protein (MAP) from the marine mussel Mytilus edulis has been investigated on polystyrene (PS) and poly (octadecyl methacrylate) (POMA) surfaces using angle dependent XPS and AFM. XPS analysis was performed at LN temperatures without dehydrating the samples and at room temperature following dehydration. The analyses indicate that adsorbed MAP is stabilized on the surface of the PS through specific interactions preventing the protein from losing lateral spatial distribution across the surface upon dehydration. The adsorbed MAP on the POMA surface is representative of a loosely bound protein layer that is adsorbed through nonspecific types of interactions allowing the protein to lose much of its lateral distribution when dehydrated. These data demonstrate that the surface chemistry ofthe polymer films influences protein-protein and protein-surface interactions, and that hydration plays a significant role in structuring proteinsurface interactions.
2:30pm WETTABILITY OF NICKEL COATED GRAPHITE BY ALUMINUM: S. W. [p, R. Sridhar, J.M. Toguri, Department of Metallurgy and Materials Science, University of Toronto, Toronto, ONT, Canada M5S 3E4; T. Stephenson, INCO Limited, J. Roy Gordon Research Laboratory, 2060 Flavelle Boulevard, Mississauga, ONT, Canada L5K lZ9 Graphite is a very attractive candidate for aluminum MMC's. However, aluminum does not wet graphite. Thus the production of aluminum-graphite composite is difficult. Nickel is a material known to be wetted by aluminum. INCO Limited recently has developed a novel technique for coating graphite fibres with nickel. It was found that such coating promotes aluminum wetting on the fibres. To determine the wettability of aluminum on nickel coated graphite, the sessile drop technique along with a high temperature x-ray setup was used. Samples of graphite, electrolytic nickel, and nickel coated graphite were examined. Contact angles determined for these samples showed that graphite is non-wetting while the nickel coated graphite provided better wetting than electrolytic nickel. The nickel-aluminum interface of the samples were examined microscopically using SEM.
2:55 pm MICROSTRUCTURAL INVESTIGATION OF INERT GAS ATOMIZED SiC/Al-Li-Cu-Mg-Zr ALLOY BASED MMC POWDERS: S. Ozbilen, Gazi University, Faculty of Technical Education, Department of Metals Education, Teknikokullar, Arkara, Turkey Variable amount SiC short fibres hardened & Al-Li-Cu-Mg-Zr alloy based MMC powders were produced by inert gas atomization under Ar, in a pilot plant down-draught atomizer with a Mannessman type nozzle. Melt temperature was 875°C and gas pressure was 1.85 MPa. Powder based alloy matrix
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toughness and strength which can be achieved by incorporating a minimum amount of fine, well distributed porosity, and must also be chemically and microstructurally stable at high temperatures. Composites based on this concept have been synthesized using vacuum infiltration of aqueous mullite-alumina slurries into woven polycrystalline alumina fiber preforms, followed by precursor impregnation and sintering. Initial evaluation of these materials shows promising behavior under tension and potential for notch insensitivity and thermal stress tolerance. Current understanding of the underlying mechanisms as well as microstructural design and processing issues relevant to the attainment ofthis behavior will be discussed. Research sponsored by DARPA under URI Grant NOOO14-92-J-1808.
CM was sieved dry. SEM and TEM investigation was used for microstructural characterization. Emphasis was given to the effect of PM processing route on the nature of bonding between matrix and second phase fiber particles. 3:20pm IN SITU PROCESSING OF TiB/Cu-ALLOY COMPOSITES BY REACTIVE PRESSURELESS INFILTRATION (RPI): v. Shtessel, M. Koczak (deceased), Department of Materials Engineering; R. Mutharasan, Department of Chemical Engineering, Drexel University, Philadelphia, PA 19104 The process of Reactive Pressureless Infiltration (RPI) for in situ synthesis of Cu-MnffiBz composites from elemental powders has been investigated. Primary factors, which alter phase composition and microstructure of the MMCs are enthalpy and relative free energy of reinforcement formation, initial powder size, processing temperatures and matrix wettability of the reinforcement. The Cu-MnffiBz composite material was synthesized by matrix assisted displacement reactions, where the desired reinforcement forms gradually as a result of liquid infiltration and reaction. A weak boride former, e.g. Mn, is mixed with B in the bottom layer and infiltrated with Cu-Ti alloys. The process involves two consecutive steps: (1) formation of weak boride, e.g. Mn + 2B -> MnB z; (2) displacement reactions, e.g. MnB z + Ti-Cu -> TiB z + CuMn. This route is advantageous due to improved wettability ofMn compounds by copper. Composites with 5, 7 10, 15, 20 and 30v/o of TiB z have been produced and their microstructures and mechanical properties are being evaluated. Typical microstructures illustrate an even distribution of 0.5 - 5 micron particulates of TiB z. Possible mechanisms of the microstructure development during the process of reactive infiltration were analyzed. The study demonstrates that TiB z forms by interfacial reaction: Ti + M,BZ = TiB z + Mn. A kinetic model of the process has been proposed. The model enables us to determine the infiltration rate, the thickness of reacted layer as a function of time, the rate of reaction of TiB z formation, the concentration profile of each component in the reactive layer. The model shows good agreement with experimental results. The RPI process is a promising technique for in situ, netshape manufacturing of Cu-based MMCs. This research is supported by Office of Naval Research.
4:50pm DENSE IN-SITU TiBlfiN AND TIB/TiC CMCS: REACTIVE SYNTHESIS AND PROPERTIES: I. Gotman, F. Olevsky, E. Y. Gurmanas. Department of Materials Engineering, Technion-Israel Institute of Technology, Technion City, Haifa 32000, Israel In-Situ TiB/TiN and TiB/TiC CMCs were fabricated from fully dense BNTi and B.C-Ti powder blends with and without the addition of Ni powder. Three different methods were used: pressureless and pressure-assisted displacement reaction synthesis and thermal explosion under pressure. Application of a moderate external pressure (:5 200 MPa) was shown to be sufficient to ensure full density ofTiB/TiNlNi and TiB/TiClNi composites. The addition of Ni powder allowed to significantly reduce the ignition temperature of thermal explosion due to the formation of the low temperature Ti-Ni eutectic phase. Thus, the preheating temperature or thermal explosion, as well as the processing temperatures of displacement reaction synthesis (:5 1200°C) were considerably lower than those typical of current methods used for the processing/consolidation of CMCs. Microstructure and composition of materials obtained were characterized by x -ray diffraction and scanning and transmission electron microscopy (SEM and TEM). Mechanical properties were evaluated by measuring microhardness, fracture toughness and three-point bending strength. High fracture toughness of TiB/TiNlNi and TiB/TiClNi CMCs was obtained indicating that fine Ni dispersions are effective in dissipating the energy of propagating cracks. 5:10pm FIBER FRAGMENTATION DURING PROCESSING OF METALLIC MATRIX COMPOSITES: Nicole M. Gorey, Donald A. Koss, John R. Hellman, Department of Materials Science and Engineering, Penn State University, University Park, PA 16802
3:45 pm BREAK 3:55 pm INVITED BREAKTHROUGH OF CONTINUOUS FIBRES REINFORCED CERAMIC COMPOSITES FOR INDUSTRIAL APPLICATIONS: M. H. van de Voorde, European Union, Joint Research Center, Institute for Advanced Materials, 1755 ZG Petten, The Netherlands
ALUMINA &BAUXITE TECHNOLOGY II
Long fibre Ceramic Composite Materials form the materials for the technology of the 21 st century; this will be demonstrated on the hand of a number of industrial applications. A resume will be given of the ceramic composites used in space applications. An overview of the "inorganic fibres" and "continuous fibres ceramic composite materials" is planned with indications of their advantages and problem areas. This data base generation, and engineering properties as joining, machining and NDE. Developments will be highlighted to made cost competitive ceramic composites with high temperature stability, corrosion resistant and good mechanical properties for long duration. The breakthrough of mew technologies with CFCC's use will be sketched. The needs for Research, Development and Technology on CFCC are pinpointed and indications for a European programme given. The market trends are also resumed.
Sponsored by: LMD Aluminum Committee Program Organizer: F. S. Williams, Alcoa Alumina & Chemicals L.L.C., Point Comfort, TX 77978-0101 Tuesday, PM February 11, 1997
Room: 230D Location: Orlando Convention Center
Session Chairman: D. J. Donaldson, Consultant, 18160 Cottonwood Road #158, Sunriver, OR 97707
2:00pm LAYERED DOUBLE HYDROXIDES FOR TREATMENT OF BAYER PROCESS LAKE WATER: A. J. Perrotta, Alcoa Technical Center, Alcoa Center, PA 15069-0001, F. S. Williams, Alcoa Alumina & Chemicals, L.L.c., Point Comfort, TX 77978-0101, L. Stonehouse, Alcoa of Australia, K winana R&D, Western Australia
4:25pm PROCESSING OF DAMAGE-TOLERANT, ENVIRONMENTALLYSTABLE, ALL-OXIDE CERAMIC COMPOSITES: e.G. Levi, J.Y. Yang, BJ. Dalgleish, Materials Department, University of California, Santa Barbara, CA 93106
Layered double hydroxides (LDHs) or the so-called anionic clays are the analog of the extensively studied family of cationic smectite clay minerals. The successful treatment of Bayer lake waters requires the removal of anions, both inorganic and organic; thus, the utilization of these anionic clays are ideally suited for this process. Insitu crystallization of layered double hydroxides have resulted in the removal of anions from Bayer lake water at two different refineries. Data on the removal of anions and their selectivity for intercalation in the layered double hydroxide indicates that the order of
Ceramic composite systems based on all-oxide constituents are of interest for high temperature applications owing to their inherent oxidative stability but must also be designed to exhibit damage tolerance. One microstructural design concept relies on crack deflection through a porous matrix rather than at fiber/matrix interfaces, which is the more conventional approach to toughening in CMC's. The requisite matrix must have an optimum combination of
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removal is C0 3 , CP4' S04' The monovalent chloride ion is least preferred but also can be extracted at significant levels at the higher level of treatment. The total organic carbon (TOC) is also lowered significantly. Measurements on succinate and malonate, both diacids, show a significant reduction at the higher levels of treatment. Successful regeneration of hydrocalumite show the thermal products of mayenite and calcium oxide which can then be recrystallized in lake water with concomitant further reduction in anion content. Additional experiments using ultrasonic radiation show an enhanced carbonate removal through increased calcite formation. 2:25pm TECHNICAL PECULIARITIES AND VIABILITY OF HYDROTHER· MAL TREATMENT OF RED MUD: Karoly SoIymar, Janos Steiner, J6zsef ZOldi, ALTAK Consulting Ltd. H-1l25 Budapest, Zsolna u.3l-33. Hungary The regeneration of the chemically bound caustic soda and alumina from red mud was studied in laboratory and pilot plant scale between 260 and 320°C as a function of caustic soda concentration and final NC ratio of the liquor, lime dosage and retention time. The pilot plant tests have been carried out in a tube digester facility of 3.0 m3/h designed by HUNGALU ALUTERV-FKI Ltd. and the test work was performed in cooperation with the team from the Almasfuzit6 Alumina Refinery. At 260-320°C iron-rich iron-aluminiumhydrogamets (Ca-Al-Fe-hydrosilicates) were" ":-.11ed allowing 90-95% Nap and 20-70% AlP, content of red mud to be recovered as a function of the final NC ratio with a specific lime consumption of 2.5-3.0 kg CaO/kg regenerated NaOH. The tube digester was found as an adequate equipment. The viability of the process highly depends on the price ratio of the caustic soda and burnt lime. The latest development in red mud separation also increased the viability of the hydrothermal treatment of red mud. 2:50pm EXPLOITING THE RHEOLOGY OF BAUXITE RESIDUE IN TAIL· INGS DISPOSAL STRATEGIES: N. Pashias, D.V. Boger, Advanced Minerai Products Research Center and Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3052, Australia This paper demonstrates how an understanding of the complex rheological properties of bauxite residue suspensions can be exploited in the implementation of a dry disposal strategy. Comparative data are presented for bauxite residue generated from three refineries in Australia and from refineries in Jamaica, Suriname, and Brazil. The necessary properties for optimum handling of the residue at high concentrations and for dry stacking and/or slope deposition are established. 3:15 pm BREAK 3:35pm MOBILITY ON MUD: Danys Morin, Societe d'electrolyse et de Chimie Alcan Ltee, Vaudreuil Works, Jonquiere, Quebec The Vaudreuil Alumina plants use deep thickeners to prepare their red mud for disposal in a 60 ft. high wet stack. Management of this stack requires four-seasons access to the pipework and occasional dust suppression procedures. From peak to foothills the stack can display all the phases of fluidity present in the mud. Vaudreuil has developed a family of vehicles to provide the required access from a 25 tonne amphibian to spread gypsum on the mud to control dusting, to a 1.5 tonne tractor-trailer for personnel transport. This paper describes the units in detail and explains how the characteristics of the mud can be used to give a good load-bearing capacity. 4:00pm OPTIMIZATION OF GRINDING OF ALUMINAS IN THE ROTARY· VIBRATION MILL AND THEIR EFFECT ON PHYSICAL PROPER· TIES OF MOULDERS: Mariusz A. Wojcik, Tomasz Gajda, University of Mining and Metallurgy, Faculty of Materials Science and Ceramics, avo Mickiewicza 30,A-3, 30-059 Cracow, Poland; Ansgar Luttermann, Fachhochschule Munster, Fachbereich Chemieingenieurwesen Stegerwaldstrasse 39,d-48565 Steinfurt, Germany The properties of high alumina ceramics are strongly influenced by the properties of the starting raw materials such as the grain size distribution and their morphology. Due to this, the grinding operation is an important step in the
process of ceramic mass production. The investigations presented show that compared to other mills, the use of a rotary vibration mill will reduce time of grinding, the energy consumption and yield finer powders. The aim of these investigations was to obtain alumina powders with d50 approximately 3 urn and d90 close to 10 urn. Two different starting materials were tested. The process of grinding was performed according to various parameters such as filling ratio, amount of grinding media, alumina and water, ball set and frequency. The influence of ratios between the grinding media, alumina and water are shown. The influence of ball size, time and frequencies on the kinetics of grinding are shown. Finally the effect of alumina grinding on the physical properties such as green and fired density and shrinkage are shown and discussed in this paper. 4:25pm RESULTS OF TESTS OF THE FINE GRINDING OF ALUMINA IN THE ROTARY· VIBRATION MILL WITH LOW FREQUENCY OF VIBRATION: Jan Sidor, MariuszA. Wojcik, University of Mining and Metallurgy, Faculty of Materials Science and Ceramics, avo Mickiewicza 30, a-3, 30-059 Cracow, Poland Results of the investigations of the fine grinding of alumina (below 0.5-2/-lm) were presented in this paper. Tests were carried out in the laboratory rotaryvibration mill with a low frequency of vibration below 16 Hz at two sets of work. In the first set, the mill chamber had both rotary and vibration movements, while in the second one, the mill chamber made only the vibration movement such as in the case of a classic vibration mill. Results show that it is possible to obtain a high purity alumina with low energy consumption in both sets.
ALUMINIUM REDUCTION TECHNOLOGY IV: Lining and Cathodes Sponsored by: LMD Aluminum Committee Program Organizer: Harald A. 0ye, Institute of Inorganic Chemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway
Tuesday, PM February 11, 1997
Room: 230A Location: Orlando Convention Center
Session Chairperson: Dave Belitskus, Alcoa Technical Center, Alcoa Center, PA 15069
2:00 pm IMPROVEMENTOFTHEALUNUNUmWCELLLll«NGBEHAVIOUR BY USING SiC: M.M. Ali, A.A. Mostafa, R&D Management, The Aluminium Company of Egypt, Naga Hamadi, Egypt Now, the finite element analysis techniques (FEA) are widely used in the aluminium reduction cells. For example, to select new lining materials or to better understanding of the aluminium cell behaviour, through the use of modelling concepts. One of the important studies is the thermal model of the aluminium reduction cells. A 2-D FEA model has been established, tested and verified to study the thermal balance of the cell. This paper presents a study for using a new lining material. The effect of this material on the ledge profile and thermal distribution were discussed. 2:25pm PROPERTIES OF A COLLOIDALALUMINA·BONDED TiB 2-COAT. ING ON CATHODE CARBON MATERIALS: H.A. @ye, Institute of Inorganic Chemistry, The Norwegian University of Science and Technology, 7034 Trondheim, Norway; V. de Nora, 1.-J. Duruz, G. Johnston, MOLTECH S.A., 9 Route de Troinex, 1227 Carouge, Geneva, Switzerland Laboratory studies of colloidal alumina-bonded TiB2 have been carried out. The following properties have been demonstrated: Thermal expansion some· what higher than carbon materials, electrical conductivity of the same order as graphite, porosity of coating z 30 %, resistance to sodium is high if the coating is protected by infiltrated aluminium, strong adherence of the coating to carbon materials even after thermal cycling, high abrasion resistance of the
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4:25pm
coating, wettability of the coating by liquid aluminium, the coating's action as a barrier to sodium penetration. The barrier action to sodium is the ability to form a stable liquid aluminium layer in the pores of the coating which will slow down the reaction: Al (I) + 3 NaF (in electrolyte) = 3 Na (in C cathode) + AlF3 (in electrolyte) as the sodium stabilizing C is no longer in close contact with the bath.
IDENTIFICATION OF NONLINEAR SWELLING PRESSURE DISTRIBUTION OF ALUMINUM REDUCTION CELL: H. S. Sayed, Structural Eng. Dept., Cairo University, Egypt; M. M. Megahed, Mechanical Eng. and Prod. Dept., Cairo University, Egypt; F. Dawi, S. Abdella, R&E Dept., EgyptAlum Co, Nagi Hammadi, Egypt The swelling pressure has the most significant effect on determining the cathode life among other loads applied on the steel casing of the aluminium reduction cell. In previous research, an identification technique is applied to determine the average swelling pressure value that is exerted on the side wall of the cell. The identification technique made use of the measured deformation of the cathode steel casing at different elapsed times (after 88 and 615 days) on an existing cathode that belongs to EgyptAlum. A new set of measurements has been conducted at different elapsed time (after 1055 days). This new set of measurements has been conducted at different elapsed times (after 1055 days). This new set of measurements gives a unique opportunity to reassess the identified swelling parameters. On the other hand, the distribution of the swelling pressure along the cathode interface with the vertical steel walls of the cell, has a significant effect on the performance of the steel casing. In this paper, the distribution of the swelling pressure, the interface of the carbon blocks and the steel casing, are identified. A nonlinear elasto-plastic model for the steel casing using combination of shell and beam elements is developed. The carbon blocks are modeled using solid and truss elements. The model utilizes Dewing model that describes the swelling pressure as a function of the elapsed time and confined swelling strain rate to determine the swelling pressure distribution. The swelling pressure is initiated using a predetermined free and confined swelling rate. As a nonlinear analysis progress with item, the confined swelling rate of the previous time step is used to assess the swelling pressure at the interface for the subsequent steps. The swelling pressure distribution is then determined at any elapsed time.
2:50pm PENETRATION FORCE. OF BATH COMPONENTS INTO POT LININGS DESCRIBED BY NONEQUILlBRIUM THERMODYNAMICS: Stig F. Johansson, Skamol als, 0stergade 58-60, DK-7900 NykjZlbing Mors, Denmark; Signe Kjelstrup, The Norwegian University of Science and Technology, Department of Physical Chemistry, N -7034 Trondheim, Norway From principles of irreversible thermodynamics, a simple expression is developed for the driving force for transport of bath constituents across a nonisothermal matrix into the refractory lining in aluminium electrolysis furnaces. The expression shows that the transport outwards of aggressive substances is favoured by the temperature gradient. Possible applications are demonstrated for 3 penetrating gases with a variety of applied and proposed refractory materials. Common to all results is a possible reduction of the rate of penetration into barriers by a smaller temperature gradient due to the entropies of reaction. This can be accomplished by proper heat insulation below. A set of conclusions regarding the resistance of chemical barriers to penetration by bath components completes the paper.
3:15 pm BREAK 3:35pm FLUORIDE ATTACK ON ALUMINO-SILICATE REFRACTORIES IN ALUMINIUM ELECTROLYSIS CELLS: Jf/lm Rutlin, Tor Grande, Department ofInorganic Chemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway
4:50pm MODELLING OF DYNAMIC LEDGE HEAT TRANSFER: Chuck C. Wei, John J.J. Chen, Barry J. Welch, The University of Auckland, Chemical & Materials Engineering Dept., Auckland, New Zealand; Vaughan R. Voller, University of Minnesota, Dept. of Civil & Mineral Engineering, Minneapolis, USA; M.P. Taylor, New Zealand Aluminium Smelters Company Ltd., Invercargill, New Zealand
The phase relations in the system sodium fluoride - mullite are relevant to chemical reactions that take place in fireclay based refractory materials used in the bottom lining of aluminium electrolysis cells. The solid-liquid phase relations have been investigated by means of differential thermal analysis, powder X-ray diffraction analysis and microscopy. At sub solidus temperatures the four compounds sodium fluoride, cryolite, nepheline and ~-alumina have been found at excess amount of sodium fluoride. At lower concentration of sodium fluoride, corundum is formed at the expense of ~-alumina. The solidus temperature was observed at 857±5°C which corresponds well with results in systems with higher aluminium fluoride content. An apparent eutectic was observed at 12±O.5 mole% mullite. Nepheline and cryolite are the two main components of the melt crystallizing at the solidus temperature. The liquidus temperature at the solubility limit was observed at 943°C and at 7.5±O.5 mole% mullite. The present results are discussed in relation to the deterioration mechanism of alumino-silicate refractories.
Cell disturbances such as anode effect and process operations such as feeding, anode changing and metal-tapping often cause variations in the heat balance of a reduction cell, resulting in deviations from the optimum operating conditions. A dynamic ledge heat transfer model built on an earlier one-dimensional dynamic simulation by the authors and based on the finite difference method was used to solve the transient heat conduction with phase change in the sidewall/ledge region. Fixed-grid and deforming-grid spacings were respectively superimposed on the sidewall and ledge region in order to track the moving front. Various aspects of the process dynamics with respect to the variation of ledge thickness and sidewall shell temperature were considered.
4:00pm PYROHYDROLYSIS OF SPENT POTLINING: Vladimir Blinov, Tor Grande, Harald A. 0ye, Department of Inorganic Chemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway Due to the toxic nature of spent potlining (SPL) this is becoming one of the major environmental concerns for the aluminium industry today. SPL also represents a major recovery potential because of its fluoride and energy content. The Elkem SPL recycling process is one of several technically feasible alternatives for treatment and recycling of SPL. In this process the fluorides can potentially be recovered by a pyrohydrolysis of the oxyfluoride silicate slag from the Elkem process. The thermodynamic aspects of this pyrohydrolysis are discussed in the present work. Chemical activity of fluorides in actual oxyfluoride silicate melts has been determined by means of high temperature mass spectroscopy and the Knudsen effusion method. Only sodium fluoride was observed as volatile species for dry melts. The chemical activity of sodium fluoride in several melts could therefore be determined by the Knudsen effusion method. Together with data on the activity of sodium oxide, the present activity data of sodium fluoride enable a calculation of the equilibrium pressure of HF during pyrohydrolysis of SPL.
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2:50pm MONOLITHIC MICRO-SPECTROMETER FOR LOW-COST LIQUID AND GASEOUS CONSTITUENT PROCESS MONITORING: S. Rajic, C.M. Egert, Engineering Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-8039
APPLICATIONS OF SENSORS AND MODELING TO MATERIALS PROCESSING - IV Sponsored by: Jt. EPDIMDMD Synthesis, Control, and Analysis In Materials Processing Committee and EPD Process Fundamentals Committee Program Organizers: S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; R.G. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487; J.C. Malas, Wright-Patterson AFB, OH 45433-6533; L.L. Shaw, Dept. of Metallurgy & Materials Science, Univ. of Connecticut, Storrs, CT 06269-3136; R. Abbaschian, P.O. Box 116400,132 Rhines Hall, Univ. of Florida, Gainesville, FL 32611-6400 Tuesday, PM February 11, 1997
A monolithic miniature spectrometer suitable for a variety of sensing applications including industrial process monitoring has been developed. The device consists of a solid structure with a volume less than 6 cubic centimeters. All optical components of the spectrometer including two aspheric mirrors, a diffration grating, and entrance and exit surfaces are fabricated onto the surface of the structure. All light paths are internally contained within the structure. The result is a small, rugged spectroscopic sensor ideally suited for use as a process monitor. Due to its monolithic nature, the device requires no post-fabrication alignment; nor can it be knocked out of alignment during use. The prototype device discussed here was produced in PMMA by precision diamond turning; however, lower cost manufacturing approaches involving injection molding (using diamond turned molds) are under development to produce an affordable sensor. Due to its rugged monolithic design, small footprint, and low cost, the monolithic micro-spectrometer is ideally suited for distributed process monitoring applications often required for industrial processes. It is expected that specific sensor designs will be required for specific applications so as to maximize the performance and resolution over the operating range. The performance of this device as well as the design tradeoffs necessary to optimize performance for given applications will be discussed in the report.
Room: 232A Location: Orlando Convention Center
Session Chairs: J.C. Malas, Wright-Patterson AFB, OH 45433-6533; V.L. Acoff, Dept. of Metallurgical and Materials Engineering, The UniverSity of Alabama, Tuscaloosa, AL 35487
2:00pm ELECTRONIC PROTOTYPING: TOWARDS VIRTUAL MATERIALS RESEARCH: S. R. LeClair, Wright Laboratory, Materials Directorate, Wright-Patterson AFB, OH 45433-7746; S. L. Thaler, PanAptics, Inc., 12906 Autumn View Dr., St. Louis, MO 63146-4331
3:15 pm BREAK
The most significant first step toward electronic prototyping (EP) in the research community has been the pursuit of intelligent processing (i.e., closedloop process control), effectively using in situ sensors to monitor both process parameters (energy input), material behavior (changes in bulk structure, temperature, etc.), and characterize materials at the atomic scale, wherein material properties such as strength, residual stresses, composition, phase, compressibility, modulus, etc., are monitored and controlled in real-time. Of interest are the identity of interrelationships between sensed variables which enable fault detection - discover and monitor, in real-time, an evolving taxonomy (a set oflinear and other meaningful relationships) which can be classified as "faults"; process stability analysis - establish a measure of stability, in real-time, by assessing process response/noise in the context of energy input, apparatus actuation, and the control algorithm requisite variety; and response time - establish a measure of performance, in real-time, of "sensoractuator" limits to affect specific processing requirements. Yet these capabilities are merely near-term - the more interesting, longer term capability is the pursuit of process discovery, i.e., how these relationships and measures might provide insight into explaining phenomena of interest and/or enable the development of a material or process model in situ.
3:25pm AN ULTRASONIC SENSOR FOR IDGH TEMPERATURE MATERIALS PROCESSING: Rollie E. Dutton, Materials Directorate, Wright Lab., WLIMLLM, Bldg 655 Ste I, Wright-Patterson AFB, OH 45433-7817; David A. Stubbs, University of Dayton Research Institute Structural Integrity Division, 300 College Park, Dayton, OH 45469-0120 A sensor has been developed and tested that is capable of emitting and receiving ultrasonic energy at temperatures exceeding 900°C (1652 f) and pressures above 150 MPa (22,500 psi). The sensor works with standard ultrasonic pulser-receivers and has a demonstrated capability of measuring workpiece deformation during hot isostatic pressing (HIP). Details of the sensor design, performance, and the coupling of ultrasonic to the workpiece are described. Ultrasonic data acquired by the sensor, in situ, during HIP runs are presented.
3:50pm TWO METHODS FOR EMBEDDING OPTICAL FIBERS IN METAL COMPONENTS: LJ. Talarico!, S.W. Allison!, c.A. Blue 2, H.M. Meyer III', L. Riester2; !EngineeringTechnology Division, Oak Ridge National Laboratory; 2Metals and Ceramics Division, Oak Ridge National Laboratory; 'Development Operations, Y-12 Plant; Oak Ridge, TN 37831
2:25pm ACCURATE, RELIABLE CONTROL OF PROCESS GASES BY MASS FLOW CONTROLLERS: J. Hardy, T. McKnight, Instruments and Controls Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6003
Manufacturing or embedding optical fiber sensors in composite materials such as graphite-epoxy, cementitious, plastic or ceramic components is of growing importance to a variety of smart materials and structures applications. A variety of fiber optic sensors can measure strain, pressure, and temperature by observing changes in an output signal fluorescence spectrum or a shift in output signal peak wavelength. The ability to measure these parameters on the surface of, as well as within, a part could provide experimental data for evaluating models, perhaps identifying some inferior parts on-line, and monitoring operating behavior. Some examples are monitoring cure and assessing thermal damage in polymer matrix composites by measuring changes in the epoxy fluorescence spectrum and monitoring densification during powder pressing. Other potential applications include engine diagnostics, condition based maintenance of aircraft and vehicle components, and monitoring and control in the metal forming and materials processing industries.
The thermal mass flow controller, or MFC, has become an instrument of choice for the monitoring and controlling of process gas flow throughout the materials processing industry. MFCs are used on CVD processes, etching tools, and furnaces and in the semiconductor industry are used on 70% of the processing tools. Reliability and accuracy are major concerns for the users of MFCs. Calibration and characterization technologies have been developed and implemented for mass flow devices. A test facility is available to industry and universities to test and develop gas flow sensors and controllers and evaluate their performance related to environmental effects, reliability, reproducibility, and accuracy. Additional work has been conducted in the area of accuracy. A gravimetric calibrator was invented that allows flow sensors to be calibrated in corrosive, reactive gases to an accuracy of 0.3% of reading. This paper will present possible sources of error in MFC process gas flow monitoring and control, and will present an overview of corrective measures which may be implemented with MFC use to significantly reduce these sources of error.
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4:15pm EXAMINATION ON THE USE OF ACOUSTIC EMISSION FOR MONITORING METAL FORGING PROCESS: A STUDY USING SIMULATION TECHNIQUE: WM. Mullins, TMC, Inc., WLIMLIM, WPAFB, OH 45433-7746; R.D. Irwin, Dept of Electrical Engineering and Computer Science, Ohio University, Athens, OH; J.C. Malas, III, S. Venugopal, Materials Process Design, Materials Directorate, Wright Laboratory, WPAFB, OH45433-7746 Physical models for acoustic emission (AE) are introduced and expressions are derived to predict AE activity from such parameters as applied stress, strain, and strain rate. These models are then incorporated into a visco-plastic finite-element simulation program, and the acoustic emission event rate generated during metal-forming operations are predicted. Simulation results are presented for upsetting operations on a typical C-Mn type steel for various friction and die geometry conditions. The AE model predictions compare well with the available experimental results reported in the literature and demonstrate that AE signatures can be reliably simulated. The signatures predicted for metal forging are fairly insensitive to changes in certain processing parameters. This suggests that AE event rate monitoring may not be well suited for monitoring changes in microstructure and friction during forging operations. Some very preliminary studies of event spectral analysis have been performed which show that AE spectral features may be sufficiently dependent on structure and loading to warrant further examination for application to monitoring metal-forging processes.
4:40pm SHEAR MODE EMAT AS A SENSOR FOR COMPOSITE LAMINATE FABRICATION: David K. Hsu, Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011 The polarization direction of shear mode ultrasound interacts strongly with the fiber direction in a composite laminate. Using conventional piezoelectric ultrasonic transducers, we have shown that cross-polarized shear waves were effective for sensing ply orientation errors and ply sequence anomalies. In this paper, we extend the technique to use electromagnetic acoustic transducers (EMAT), particularly for green (uncured) graphite epoxy composite laminates. Preliminary results will be shown and potential applications for quality control will be discussed.
AQUEOUS ELECTROTECHNOLOGIES: PROGRESS IN THEORY AND PRACTICE IV: Electrometallurgical Plants and Equipment Sponsored by: EPD Aqueous Processing Committee, Copper, Nickel, Cobalt Committee, Lead, Zinc, Tin Committee and Precious Metals Committee Program Organizers: D.B. Dreisinger, University of British Columbia, Department of Metals and Materials Engineering, 309-6350 Stores Road, Vancouver, B.C., Canada; E. Ozberk, Sherritt International, Bag 1000, Fort Saskatchewan, AB, T8l 2P2, Mrs. S. Young, BHP Copper Inc., 2400 Oracle Road, Suite 200, Tucson, AZ 85704; R.S. Kunter, Advanced Sciences Inc., 405 Urban Street, Suite 401, lakewood, CO 80228
Tuesday, PM February 11, 1997
Room: 231A location: Orlando Convention Center
Session Chairperson: A. Kasaaian, Elkem Metals Co., P.O. Box 299, Marietta, OH 45750
2:00pm IMPURITY CONTROL AND TANKHOUSE MODERNIZATION AT KOSAKA COPPER REFINERY: S. Kawamura, Kosaka Smelting and Refining Company, Kosaka, Akita, 017-02, Japan Abstract not available.
2:25pm THE USE OF POLYMER CONCRETE IN ACID CONTAINMENT
EQUIPMENT FOR ELECTROMETALLURGICAL PLANT PRAC· TICE: GJ. Karcas, Corrosion Technology International, Gent, Belgium Various non-ferrous Metals such as Copper, Nickel, Lead, Zinc and Precious Metals are produced via electrorefining and electro winning processes. Apart from controlling electro-chemical conditions for the production of these metals, there has always existed the challenge of controlling the severely deleterious effect of the aqueous environment which serves as the medium for the production of these metals. The practice of acid containment in electrometallurgical operations has entered the world of high technology with the advent of advanced acid resistant materials such as Vinyl Ester Resin which is either combined with concrete to form Polymer Concrete or used to coat or line various acid containing vessels and surfaces. The North and South American copper industry has indulged quite heavily in the use of polymer concrete cells, electrolyte storage tanks, and the use of Vinyl Ester Resin for corrosion protective systems. Electrolytic cell and electrolyte storage tank construction has undergone a transformation from a multiple part configuration to a single piece unit. The combination of a wood, steel, or concrete frame with a lining made of lead, asphalt, rubber or plastic has been historically successful in providing protection from chemical and mechanical attack in electrolytic cells and electrolyte storage tanks all over the world. These combinations have now entered the world of obsolescence as materials such as polymer concrete have proven to provide exceptional corrosion and mechanical protection with greatly reduced maintenance requirements. Polymer concrete cells and electrolyte storage tanks fall into the category of modern tankhouse equipment which includes anode preparation machines and stainless steel cathodes, all of which playa vital role in improving quality and productivity while lowering operating costs. Polymer Concrete Cell" and other modern equipment, are succeeding in the difficult, yet important, task of driving electrometallurgical plants into the next millennium.
2:50pm POSSIBILITIES TO LOWER ENERGY USE IN ELECTROWINNING BY MODIFICATIONS OF LEAD ANODES: O. Forsen , J. Aromaa, Helsinki University of Technology, Laboratory of Corrosion and Material Chemistry, Vuorimiehentie 2, FIN-02l50, Espoo, Finland Lead alloys are most common anodes in metal electrowinning processes from acid solutions, even though their oxygen overpotential is very high. New inventions like mixed metal oxide anodes are not widely used, the main reasons being possibly doubts on the anode operation and large capital investments on the existing lead anodes. The main reaction on lead anodes in sulphate solutions is oxygen evolution, and on the lead dioxide film it has a high overpotential. In this paper we have studied possibilities to decrease the energy consumption in metal electrowinning by lowering the anode overpotential. Samples from currently used anode material were coated with different lead alloys using plasma spraying and detonation coating. Also modifications on the anode microstructure by melting and controlled cooling and additions of certain ions to the electrolyte were studied. Most of the studied procedures were able to lower the anode potential about 100 - 150 mV at the operating current density of 500 Nm 2• Rapid cooling during the anode casting was found to be the simplest and thus also the least expensive way to lower the anode potential.
3:15 pm STUDIES RELATING TO THE DEVELOPMENT OF AN ANODE FOR LEAD ELECTROWINNING: DJ. Robinson, Dremco Inc., Point Roberts, WA; TJ. O'Keefe, University of Missouri, Rolla, MO The pyrometallurgical method of recycling car batteries suffers from a potential for air pollution violations, which prompts the desire for a viable hydrometallurgical alternative. Several Processes have been proposed, including leach-electrowinning routes using HBF4 and/or H zSiF6 based electrolytes, along with anodes of PbO, on inert substrates. A study has been carried out to evaluate the proposed systems, with the intention of demonstrating a six month life of an electrolyte-anode combination. The work, which focused on the use of H zSiF6 , has indicated that there was no acceptable anode, and has lead to the development of a technique to produce smooth, glassy, adherent coatings on graphite, and to the development of an anode composed of a series of copper cored graphite rods. The paper will present results on leaching and electro winning experiments, as well as the description of a flowsheet for a pilot plant that will be used to produce one tone per day of refined lead from
spent battery paste. 3:40 pm BREAK 4:00pm APPLICATION OF ELECTROCHEMICAL MEMBRANE METHODS IN HYDROMETALLURGY OF COPPER: A.S. Mustafinova, A.A. Zharmenov, Chemical-Metallurgical Institute, Karaganda, Republic of Kazakstan Production of electrolytic copper is characterized by large volumes of acidic spent solutions the utilization of which requires considerable expenditures of neutralizing agents. At present, an economically substantiated technology does not exist for treatment of sulfuric acid rinse solutions and spent copper electrolyte which will allow for repeated use of the acid and the metal salts. Therefore, for this aim the most advantageous is the use of electromembrane methods. In the paper there is stated the essence of developed technologies which are distinguished by low waste and provide the extraction from the solutions of metallic copper, nickel and sulphuric acid. There are also considered methods of copper electrolyte processing allowing to regulate its composition by that or another component (H2S04 , Cu, Ni, As). On the base of the detailed study of the behaviour of various types of ion- exchanger membranes in copper-, nickel-, zinc-, arsenic- bearing sulphate solutions there is realized the selection of the most suitable membranes (MK-40 I, MA-4II, MB-2 and MKLIIMAL-2). Some variants of electromembrane processing of spent solutions of the hydrometallurgy process have passed productions tests on a number of copper-electrolyte enterprises of the countries of CIS (cooperation of Independent States). These tests showed high efficiency of developed methods. 4:25pm ELECTROMETALLURGY, PAST, PRESENT, AND FUTURE: F. Habashi, Laval University, Department of Mining and Metallurgy, Quebec City, Quebec, GIK 7P4, Canada While pyrometallurgy is an ancient art and hydrometallurgy can be traced to the Middle Ages, electro metallurgy is the most recent technology since it started only after the discovery of electric current in the ninteenth century. Davy, Faraday, and Bunsen laid the foundation of this technology which had a great impact on other areas of metallurgy, e.g., the liberation of aluminum for the first time from its salts. Once aluminum was available, it was used to liberate other metals from their oxides. Electrometallurgical processes, however, are capital intensive. Improvement of the present technology should be intensely investigated.
CARBON TECHNOLOGY II: Binder Pitch
the filler coke also appear to influence the ultimate size of the crystallites formed in the binder matrix at the end of the carbonisation cycle. It appears that there is a variable degree of interaction between the filler coke and the pitch, with extent of the interaction depending on the properties of the two components. The results so far reinforce the importance of consistency in raw materials preparation and in the baking process if uniform anodes are to be produced. 2:25pm ABSORPTION OF OXYGEN FROM AIR INTO COAL TAR PITCH: Jaromir Cibulec, Daniel Kostal, DEZA Corporation, P.O. Box 28, 757 28 Valasske Mezirici, Czech Republic Changes in the properties of coal tar pitch during contact with atmospheric oxygen were studied. There were found to be changes in the content of toluene insolubles and the melting point. These changes are dependent on the quantity of the absorbed oxygen and on the temperature of the pitch during absorption. As the reaction of the air with the pitch is very rapid, reaction speed is controlled by the speed of absorption of oxygen into the pitch. When surface of the pitch is motionless, the rate determining step of the reaction is controlled by the rate of absorption of the oxygen into the pitch which is dependent on the diffusion coefficient of molecular oxygen in air. When the surface of the pitch is agitated, the reaction rate is controlled by the rate of reaction of the oxygen with the pitch. The mechanism of the reaction is described and a practical application is discussed. 2:50pm X-RAY AND MICROSCOPY INVESTIGATIONS ON THE CATALYST· CARBONIZED STRUCTURE OF COAL TAR PITCH· PETROLEUM COKE PILOT ANODES: Jilai Xue and Harald A. Oye, Institute of Inorganic Chemistry, the Norwegian University of Science and Technology, N7034 Trondheim, Norway The carbonization has important impacts on the energy consumption and the productivity in anode baking. It was found that the coke yield of the coal tar pitch binder in its mixtures with petroleum coke increased with addition of catalysts, such as S, AIFJ , and FeCp, (CO)•. Then the structures of the samples taken from the carbon pilot anodes with and without above additions were further investigated using X -ray diffraction and microscopic techniques. The remained S, Al and Fe in the carbons after heat treatments were also analysed. The coke yield, L, value, and porosity will be presented against various heat treatment temperatures for different additions. The possibility of obtaining the carbon anodes by lower baking temperatures with the required structure will be discussed based on above results. 3:15 pm BREAK
Sponsored by: LMD Aluminum Committee Program Organizer: Jean-Claude Thomas, Aluminium Pechiney, Peychiney/Balzac, 92048 Paris la Defense, France
3:35 pm COAL· TARIPETRO INDUSTRIAL PITCHES: E.R. McHenry, Koppers Industries, 1005 Wm. Pitt Way, Pittsburgh, PA 15238
Tuesday, PM February 11, 1997
Throughout the 20th Century coal tar has been the dominant raw material for producing industrial pitches in North America. However, the coal tar supply in North America has been decreasing due to closure of metallurgical and foundry coke-oven batteries. Because of lower carbon yield, petroleum-based pitches have only limited usage. To increase the raw material base and provide more flexibility in characteristics, coal tar/petro pitches are being developed. The evaluation of the coal-tar/petro industrial pitches is reported.
Room: 230C Location: Orlando Convention Center
Session Chairperson: Jaflar G. Ameeri, Aluminium Bahrain, P.O. Box 570, Manama, Baharain
2:00pm TRACKING THE CARBONISATION PATHWAY OF DIFFERENT PITCHES AND PITCH COKE MIXTURES BY CRYSTALLITE HEIGHT (Lc) MEASUREMENT: N.R. Turner, Bitmac Limited, Scunthorpe Works, Dawes Lane, Scunthorpe, North Lincolnshire, DNI5 6UR, UK Pitches with a range of properties, e.g. Q.I. content, were carbonised to a final temperature of 1080°C. The same pitches were co-carbonised with finely divided petroleum coke. Lc has been measured at the end of the carbonisation cycles and at intermediate points to track the status of carbonisation for different pitches and pitch/filler coke combinations. The original pitch Q.I. content and pitch aromaticity appear to influence the carbonisation pathway of the pitch and the pitch-coke mixtures according to Lc data. The properties of
4:00pm PETROLEUM PITCH, A REAL ALTERNATIVE TO COAL TAR PITCH AS BINDER MATERIAL FOR ANODE PRODUCTION: Roger Marzin, Carola Acuna, Intevep S.A., Departamento de Refinacion, Apdo. 76343, Caracas 1070 A, Venezuela; Maria de Oteyza, Maraven, S.A., Nuevos Desarrollos, PO Box 829, Caracas 10lOA, Venezuela; Raymond C. Perruchoud, R&D Center, Le Chable, P.O. Box 157, CH-3960 Sierre, Switzerland A petroleum pitch, specially developed for aluminum anodes was produced, at commercial scale, as a real alternative to coal tar pitch. Using a highly aromatic refinery stream and well designed process conditions, it is possible to produce the right chemical composition needed for a high quality binder
material for anodes. Through a Dynamic Process Optimization study, the paste formulation and parameters were adjusted to produce full size anodes with 100 % petroleum pitch. The performance of baked anodes were similar to coal tar pitch anodes, with the advantage of a much lower content of cancerogenic Polycyclic Aromatic Hydrocarbons (PAH). Comparative green and baked anode properties, PAH emissions and storage stability test for molten pitch are presented.
CAST SHOP TECHNOLOGY IV: Metal TreatmentFluxing Sponsored by: LMD Aluminum Committee Program Organizer:Wolfgang A. Schneider, VAW aluminium AG, Research and Development, Georg-von-Boeselager-Str.25, 0·53117 Bonn, Germany
4:25pm
Tuesday, PM February 11, 1997
REDUCTION OF POLYCYCLIC AROMATIC HYDROCARBONS (PAH) IN ANODES BY USING PETROLEUM PITCH AS BINDER MATERIAL: A COMPARAISON OF ANODE PROPERTIES AND ANODE BEHAVIOR OF PETROLEUM AND COAL TAR PITCH ANODES: Dr. Ulrich Mannweiler R&D Carbon Ltd. Winterthurerstrasse 92, CH-8006 ZUrich, Switzerland; Raymond C. Perruchoud, R&D Carbon Ltd., Le Chable, P.O. Box 157, CH-3960 Sierre, Switzerland; Roger Marzin, Intevep S.A., Departamento de Refinacion,Apdo. 76343, Caracas 1070 A, Venezuela
Room: 230B Location: Orlando Convention Center
Session Chairperson: Julian V. Copenhaver, NSA • A Division of Southwire, P.O Box 500, Hawesville, KY 42348
2:00pm ON THE EFFICIENCY OF IN-LINE DEVICES TO CLEAN THE MELT: P. Pouly, E. Wuilloud, Alusuisse Technology and Management Ltd., Technology Center Chippis, 3965 Chippis, Switzerland
Petroleum pitch as binder material of anodes has the great advantage, that the content of cancerogenic Polycyclic Aromatic Hydrocarbons (PAH) compared to coal tar pitch is practically inexistent. In applying the correct content of pitch and through optimization of all process parameters during anode manufacturing, full size anodes with coal tar pitch (CTP) and petroleum pitch (PP) have been prepared in an anode plant. While baked anode properties for coal tar and petroleum pitch anodes are very similar, the PAH content can be reduced by 98 %. In this paper the behavior of representative lots of coal tar and petroleum pitch anodes in 100 kA electrolysis cells and the properties of the resulting anode butts will be described.
Rotating impellers for injecting gas into aluminium melt are an often used inline device to remove impurities. However, the treatment efficiency is seldom investigated, as the precise effect of flotation is not well understood. Moreover, the interpretation of the results obtained by measuring the inclusion content is not always obvious. For these reasons, it is sometimes observed that rotors work in an erroneous way. This paper illustrates how the variation of some parameters can affect, either in a good or a bad way, the efficiency of rotating impellers. The problematic of measurement techniques with some of their limitations will also be exposed. A special emphasis will be laid on inclusion removal.
4:50pm TESTS OF PITCH PRODUCED FROM THE MIXTURE OF COAL RESIN AND REMAINDERS AFTER OIL PYROLYSIS: ML Itskov, E.A. Yanko, Russian National Aluminium-Magnesium Institute (VAMI), 199026 St. Petersburg, Russia; V. V. Krukov, Central Investigations Laboratory, 101000, Moscow, Russia
2:20pm THE FLUID MECHANICS IN THE HIlO HYCAST REACTOR: Bodil Hop, Frede Frisvold, Stein Tore Johansen, SINTEF Materials Technology, N-7034 Trondheim, Norway; Bjl1lm Rasch, Hydro Aluminium a.s R&D Centre, N-6600 SunndalSl1lra, Norway
Actually the main type of binding materials, used in the anode paste production is a coal tar pitch. This binder provides the necessary quality of anode, but its using is related to increased emissions of cancerogenous matters, especially, benzapyrene, into the anode paste and aluminium reduction plants. The cancerogenous danger could be considerably reduced if using, as a binding material in the anode paste production, pitch produced at the distillation of the mixture of coal resin and remainders after oil pyrolysis, called "modified pitch". This report gives the results of laboratory investigations and industrial tests of anode paste, produced with using above mentioned binder, in the aluminium reduction. The laboratory investigations and industrial tests on Soderberg pots have shown, that by using the modified pitch we succeeded to produce anode paste of satisfactory qUality. In this case we achieve a considerable reducing of the emissions of cancerogenous matters, namely benzapyrene, from the surface of anode.
The flowfield in the HlIO HYCAST reactor is investigated both theoretically and experimentally. The paper demonstrates how fluid flow calculations can be used to interpolate between experimental velocities. The experiments are performed by a two component Laser Doppler-technique in a reactor which has one single baffle. In the 3-dimensional computation a rotating grid for the rotor is imposed on the stationary grid for the reactor body. The flow effects caused by the baffie are discussed in relation to metallurgical performance. The turbulent dissipation rate is translated into bubble sizes and the result is compared to experimental bubble sizes. The paper discusses the reasons for deviations between predicted and experimental velocities.
2:40pm IN-LINE FLUXING WITH HIGH SPEED MULTIPLE DISPERSER ROTORS: D.C. Chesonis, H. Yu, Aluminum Company of America, Alcoa Technical Center, 100 Technical Drive, Alcoa Center, PA 15069; M. Scherbak, Aluminum Company of America, Ingot Technology Group, 900 South Gay Street, Knoxville, TN 37902 The impurity removal efficiency of in-line fluxing equipment depends strongly on the interfacial area between the gas bubbles and the molten metal. High interfacial areas can be generated by direct shearing of the gas bubbles using rotating dispersers. Placing multiple dispersers on a single rotor shaft and injecting gas into the metal at each disperser increases this direct shearing, improving the efficiency of the in-line fluxing unit. Small dispersers can operate at high gas loading and high speed without vortexing. Small dispersers also allow smaller metal treatment units, reducing floor space requirements and metal holdup. This paper will summarize the theory behind the direct shearing approach and will present data illustrating the difference in trace element removal for single, double, and triple disperser rotors. Comparisons with other in-line fluxing equipment will also be presented.
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3:00pm EVOLUTION OF THE ALPUR® ROTOR TOWARDS IMPROVED PERFORMANCE: Isabelle Ventre, Jean-Marie Chateau, Pechiney Aluminium Engineering, Centr' Alp-725 rue Aristide Berges, F-38340 Voreppe, France
both salt systems removed the oxide film from the metal. NaF, KF and Na3AIF6 additives were the most effective salts at stripping away the oxide layer and promoting coalescence. As the concentration of MgCI2 increased, the ability of the droplets to coalesce decreased significantly. 4:30pm KINETICS OF MAGNESIUM REMOVAL FROM ALUMINUM ALLOYS BY CHLORINE FLUXING: Qian Fu, 1. W . Evans, Dept. of Materials Science and Mineral Engineering, University of California, Berkeley CA 94720
The ability of a rotary injector to efficiently reduce dissolved hydrogen and impurities in an in-line treatment box is directly related to its ability to create an intimate dispersion of tiny bubbles of treatment gases within the aluminum melt. This is achieved through a combination of shearing effect of the injected gas flow and strong pumping of the metal contained in the box. The pumping action of the rotary injector can however create some metal recirculation loops within the box and cause undesirable turbulences at the surface of the metal inside the box. To address this issue the design of the Alpur® rotor was improved and optimized which resulted in drastic improvement of the surface conditions without affecting the intrinsic performance of this injector. We review in this paper the basic criteria for this optimum rotor design and assess through water modelling and testing in aluminum the overall benefits for the operation.
Chlorine fluxing (sparging chlorine-argon mixtures into the melt) is a standard procedure for eliminating magnesium from AI-Mg alloys. The kinetics of the reactions/mass transport involved have not been extensively studied in the past. The paper describes an ongoing investigation of those kinetics. Much of the work to date has been using laboratory-scale melts with magnesium removal measured by analysis of samples. Techniques have been developed to measure both bubble frequency and bubble residence time in the melt, enabling estimation of the total interfacial area and, consequently, the intrinsic kinetics of the phenomena involved. It is observed that, above the melting point of MgCI2, there exists a "critical Mg concentration". Above this critical concentration the reactions are sufficiently fast that all entering chlorine is converted to MgCI2 and there are negligible chlorine emissions. Below this concentration, Mg mass transport in the alloy appears to be rate-controlling. The results are interpreted in terms of a mathematical model for fluxing. The paper also describes the preliminary results of experiments on a larger scale (few tens kg alloy) in which bubble probes are used to detect the dispersion of gas injected into the melt and measure the interfacial area.
3:20pm QUANTIFIED QUALITY AND EFFICIENCY IMPROVEMENTS AT SAPA, LTD.: Stephen 1. Rose, SAPA Ltd., Saw Pit Lane, TibshelfDerbyshire DE55 5NH, England; David W. Busch, Foseco Inc., 777 Old Saw Mill River Road, Tarrytown, NY 10591-6729 SAPA, Ltd. is a 3 press aluminium extrusion operation specializing in quality flat and hollow product with a small remelt facility for in house generated scrap. In 1994 a decision was made to improve the overall quality of the in plant remelt facility. The fust capital improvement was the installation of a SNIF Sheer P-60U two nozzle degassing system with immersion heaters. This unit was started up in December of 1994. A new melter with an exhaust collection system was brought on line in September of 1995. This paper will describe how improved melt treatment produced measurable economic benefits downstream.
4:50pm INTERFACIAL TENSION BETWEEN ALUMINUM AND CHLORIDE-FLUORIDE MELTS: A. SUny, Institute ofInorganic Chemistry, Slovak Academy of Sciences, SK-84236 Bratislava, Slovakia; T.A. Utigard, Department of Metallurgy and Materials Science, University of Toronto, M5S 3E4 Toronto, Canada
3:40 pm BREAK
A technique was developed for the measurement of the interfacial tension between liquid metals and molten salts at elevated temperatures. The technique is based on the measurement of the capillary depression ocurring when a capillary, which is moved vertically down through the molten salt layer, passes through the salt/metal interface. The depression is measured by simultaneous video recording of the immersion height of the alumina capillary and the position of a liquid meniscus in a horizontal tube connected to the alumina capillary. The interfacial tension was measured in the following systems: aluminium and an equimolar melt of NaCl and KCI with several salt additions at 1000 K, aluminium and NaCI-NaP at 1123 K, and aluminium and NaCI-KF at 1123 K and aluminium and equimolar melt of NaCI-KCl with additions of NaP, KF, LiF, BaP" SrF" CaP" Na,AIF6, MgF, andAIF,. It was found that the interfacial tension decreases with increasing NaP, KF, LiF, CaP2, BaF2 and SrF2 additions, remains unchanged with AIF3 additions and slightly decreases with MgF, and Na,AIF. additions. Aluminium and equimolar melt of NaCI-KCl with additions of LiCI, AICl3, BaCI" CaCI" MgCl,. All above chlorides slightly increase the interfacial tension in the system. Obtained data are compared with the ones found in literature and some conclusions for the aluminium refining and recycling were derived.
3:50pm CHLORINATION OF TiB2 GRAIN REFINED ALUMINIUM: T. Gudmundsson, G. Saevarsdottir, T.I. Sigfusson, Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavik, Iceland; D.G. McCartney, Department of Materials Engineering & Materials Design, University of Nottingham, United Kingdom The effects of fluxing grain refined molten aluminium with Ar/CI2 gas mixtures have been studied both in the laboratory and during experimental casthouse trials. Samples taken during gas fluxing were subjected to chemical analysis and examined in the scanning electron microscope (SEM). Detailed chemical analysis of agglomerates was undertaken in the SEM using energy dispersive X-ray analysis and the elements Na, K and F were found to be associated with TiB2 clusters. Results will be presented in detail and discussed in the context of previously published work on grain refiner characterization and wettability of TiB2 in liquid AI/salt mixtures. 4:10pm COALESCENCE BEHAVIOUR OF ALUMINUM DROPLETS UNDER A MOLTEN SALT FLUX COVER: K.l. Friesen, T.A .Utigard, Department of Metallurgy and Materials Science, University of Toronto, 184 College Street, Toronto, Ontario, CanadaM5S lA4; C. Dupuis, 1.P .Martin,Arvida Laboratories and Development Centre, Alcan International Ltd., 1955 Mellon Blvd., Jonquiere, Quebec, Canada G7S 4K8
5:10pm A COMPARATIVE STUDY ON THE EFFICIENCIES OF Na,SiF6 AND AlF3 FOR DEMAGGING MOLTEN ALUMINUM BY SUBMERGED POWDER INJECTION: A. Aores-Valdez, M.A. Hinojosa-SanMiguel, A.H. Castillejos-Escobar, E. Macias-Avila, F.A. Acosta-Gonzalez, Centro de Investigaci6n y de Estudios Avanzados del lPN, Unidad Saltillo, P.O. Box 663, 25000 Saltillo, Coahuila, Mexico
The formation of a suspension of aluminum droplets in salt fluxes used during the refining and recycling of aluminum, leads to decreased aluminum recovery. To enhance the coalescence and recovery, it is required to remove the oxide layer formed on the surface of these small aluminum drops. Coalescence behaviour of aluminum droplets under a molten salt flux cover was investigated using a hot stage microscope at a temperature of740°C. Two salt systems were studied: i) an equal weight mixture of NaCI-KCI with chloride and fluoride additives and ii) the MgCI2-KCl system with fluoride additives. Chloride salts did nothing to enhance coalescence but fluoride additions to
A comparative study on the efficiencies of Na,SiF6 and AIF, for demagging molten aluminum by submerged powder injection is reported. Experimental trials carried out at a scale of 250 Kg molten metal furnace capacity showed that the higher efficiencies, - 70%, were attained by the use of the Na,SiF6 powder. The basic parameter to establish the comparison between the two demagging agents was the powder size, maintaining constant the other important parameters, e.g., initial magnesium content, carrier gas flow-to-powder flow ratio, pressure of the carrier gas, temperature of the bath, the dimen-
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sions of the reactor and the shape and dimensions of the injection lance. The removal efficiency was monitored analyzing the magnesium content in both the metal and the slag. The fumes produced were also analyzed, having found that the N~SiF6Powders have the inconvenience of giving place to the generation of highly toxic SiF4 fumes.
Electron Microscopy with computer length, It will be also shown that in several cases, the particle size in the image do Dot correspond with the true particle size. A method to correct this problem will be discussed. 3:00 pm INVITED NANOSTRUCTURED MATERIALS VIA CHEMICAL ROUTES: Kenneth E. Gonsalves, Department of Chemistry & Institute of Materials Science, University of Connecticut, Storrs, CT 06269
CHEMISTRY AND PHYSICS OF NANOSTRUCTURES AND RELATED NON EQUILIBRIUM MATERIALS IV: Synthesis and Microstructure
This talk will focus on the chemical synthesis and processing of nanostructured materials. The precursor chemistry for the synthesis of nanostructured metals' ceramics, polymers, biomaterials, semiconductors and nanocomposites will be outlined and selected examples presented. Issues such as material purity, homogeneity, agglomeration and scale-up will be addressed.
Sponsored by: Jt. EMPMD/SMD Chemistry and Physics of Materials Committee, MSD Thermodynamics and Phase Equilibria Committee Program Organizers: Brent Fultz, 138-78, California Institute ofTechnology, Pasadena, CA 91125; En Ma, Louisiana State Univ., Dept. of Mechanical Eng., Baton Rouge, LA 70803; Robert Shull, NIST, Bldg. 223, Rm B152, Gaithersburg, MD 20899; John Morral, Univ. of Connecticut, Dept. of Metallurgy, Storrs, CT 06269; Philip Nash, Illinois Institute ofTechnology, METM Dept., Chicago, IL 60616 Tuesday, PM February 11, 1997
3:30 pm BREAK 3:45pm TEM AND HRTEM OF NANOSTRUCTURED M50 TYPE STEEL PREPARED BY HOT PRESSING OF CHEMICALLY SYNTHESIZED POWDERS: G. M. Chow!, c.R. Feng', Naval Research Laboratory, Washington, DC 20375; S.P. Rangarajan, X. Chen, K.E. Gonsalves, Institute of Materials Science, University of Connecticut, Storrs, CT 06269; C.c. Law, Pratt & Whitney, United Technologies Corporation, East Hartford, CT 061 08. 'Laboratory for Molecular Interfacial Interactions, 'Materials Science Division
Room: 330C Location: Orlando Convention Center
Session Chairperson: En Ma, Louisiana State Univ., Dept. of Mechanical Eng., Baton Rouge, LA 70803
Nanostructured M50 type steel materials were prepared by hot pressing the precursor powders chemically synthesized using two different techniques, namely, thermal decomposition and co-reduction. During the hot press process, the precursor powders were transformed to nanocrystalline phases with the precipitation of carbides. Simultaneously the crystalline powders were densified. The densified samples were studied using both conventional and high resolution transmission electron microscopy. The effects of hot pressing temperature, time and pressure on the evolution of nanostructures, grain growth and defects formation are discussed.
2:00 pm Invited COMBUSTION FLAME SYNTHESIS OF NANOPHASE MATERIALS: B.H. KearI, G. Skandan" N. Glumac' and Y. Che', 'Ceramics, 'Mechanical & Aerospace Engineering, Rutgers University, NJ, Nanopowder Enterprises, Inc. Piscataway, NJ Non-agglomerated nanopowders are becoming increasingly important for a number of commercial applications including UV-scattering, chemical mechanical polishing (CMP), displays and catalysis, among others. We have developed a continuous nanopowder production process, called Chemical Vapor Condensation (CVC), which involves precursor pyrolysis and condensation in a reduced pressure environment. We have introduced a flat-flame combustor unit, operable at low pressures, as a heat source in place of the original hot wall reactor. The temperature profile is uniform across the entire face of the burner, therefore, the reactants experience the same processing history and the powder has a uniform particle size distribution. The modified process, called Combustion Flame-Chemical Vapor Condensation (CF-CVC), has been used to produce a range of non-agglomerated nanoparticles (3-50 nm average particle size) of single phase, multiphase, and multicomponent materials. Examples include AIPJ, SiO" TIO" AIP/SiO, and Eu: Y,OJ' The as-synthesized powder is fully pyrolyzed (characterized by TGA), has a high surface area (SiO, > 300 m'/g: TiO, > 80 m'/g), and is non-agglomerated (TEM and BET pore size distribution). In addition, when the superheated particles leaving the combustion flame impinge on a heated substrate, in situ sintering can occur. Nanoporous or dense films or multilayered thin film structures can be synthesized. We have demonstrated the scalability of the process by increasing the burner diameter. Design consideration, processing parameters, powder characteristics and the commercial potential for the powders will be discussed. This work is supported in part by the Office of Naval Research contract #NOOOI4-95-C-0283.
4:05pm SYNTHESIS OFNANOSTRUCTURE W/CuiCoALLOY BY THERMOCHEMICAL METHOD: Gil-Geun_Lee, Gook-Hyun Ha, Dong-Won Lee, Byoung-Kee Kim, Korea Institute of Machinery & Materials, 66 SangnamDong, Changwon, Kyungnam 641-010, Korea Nanostructure W/CU/Co alloy was developed by thermochemical processing method using metallic salt precursors as the starting material for improving thermal, electrical and mechanical properties. Nanostructure WICU/Co powder have loosely agglomerated homogeneous clusters of nanoscale size We"" 50 nm), Cu. and Co particles. The density and microhardness of the sintered nanostructure W/CU/Co increased with increasing of Co content from 0.1 to 0.7wt.%, but electrical conductivity drastically decreased with addition of Co. Full density for nanostructure W/CU/Co was achieved when sintered at 1473K for 20 minutes in H, atmosphere with addition ofO.5wt.%Co. It was proved that optimum Co content is under O.5wt. % when based on the relations between electrical conductivity and density. It is shown that nanostructure WICU/Co have higher sinterability and better electrical conductivity than conventional W/Cu/Co. 4:25 pm MOSSBAUER EFFECT STUDY OF MECHANICALLY ALLOYED rFf:3ZnlO and r l -FesZn21 CUBIC INTERMEDIATE PHASES: Oswald N.c. Uwakweh, Zhentong Liu, Materials Science & Engineering, University of Cincinnati, Cincinnati, OH 45221-0012
2:30pm EVIDENCE OF SURFACE ROUGHNESS IN NANOSTRUCTURES: M. Jose Yacaman, Institute de Ffsica, Universidad Nacional Aut6ma de Mexico, Apdo, Postal 20-364, 01000 Mexico, D.F., Mexico
The Mossbauer effect measurements of as-ball milled mechanically alloyed Fe-Zn intermediate phases ofr-FeJZnJO and r-Fe5Zn21 compositions exhibit characteristic spectra consisting of triplets. Each is characterized with an Fesite with a high quadrupole splitting measuring 0.94 mrnIs, together with three other doublets. In the aged states, both compositions show spectra free of the Fe-site with the large quadrupole splitting. This suggests that both have similar metastable states, while their separate transformation paths to stable equilibrium states yield distinct crystal structures as found in the literature.
Nanostructured Materials present very unique properties which has allow several technological applications. In the case of chemical reactions nanostructured materials have been used as catalyst. It is know that reduction of the particle size to a few nanometers produce an increased catalytic activity. The origin of this activity has been attributed to the increase surface area. We will show in this paper that nanoparticles present an increased surface roughness. This roughness increases the number of kink which provide an excellent site for promoting chemical reactions. In order to characterized the roughness we have used a new technique which combines High Resolution 124
4:45pm NEUTRON DIFFRACTION & PHASE EVOLUTION OF MECHANICALLY ALLOYED s-FeZn 13 INTERMETALLIC: Oswald N.c. Uwakweh, Zhentong Liu, Materials Science & Engineering, University of Cincinnati, Cincinnati, OH 45221-0012; Brian Chakoumakos, Stephen Spooner, Oak Ridge National Laboratory, Solid State Division, Oak Ridge, TN 37831-6393
of the theses of this presentation is that some of the "relics" are indeed "holy relics" which if they are discarded by "reforming zealots" may lead to a crisis in the curriculum. A second thesis, is that indeed some of the elements of the curriculum must be changed in order to better prepare our students for the changing directions of the field. In this presentation the important elements which should remain are discussed as are some new themes that currently are not universally present in our curricula. Suggestions on how these "old" and "new" themes are to be integrated into the overall curricula will close out the presentation.
High Energy Ball-Milling is used to synthesize s-FeZn13 Intermetallic. The mechanically alloyed phase in the as-millet state is determined to be metastable, while the characteristic stages associated with the stable equilibrium transformation are identified based on DSC measurements. The as-milled material is described in terms of mechanical mixture of the elemental constituents, while the equilibrium state is confirmed to have a C2/m space group, with lattice parameters of a =13.40995 A; b =7.60586 A, c =5.07629 A, and 0 ~ = 127 18'. The atomic positions of Fe and Zn are compared with reported values.
3:20pm UNDERGRADUATE ENGINEERING AND MSE EDUCATION AT THE UNIVERSITY OF MICHIGAN: J.w. Jones, R. Gibala, Dept. of Materials Sci. and Engineering, Univ. of Michigan, Ann Arbor, MI 481092136 The College of Engineering at the University of Michigan has begun an ambitious program to restructure its undergraduate curriculum. The new curriculum will increase freshman year participation in engineering and provide an active program for each student to learn communication skills throughout the curriculum, while increasing flexibility within all discipline-specific curricula. Furthermore the new approach calls for the restructuring of courses into 4 credit-hour units, thereby enabling students to complete their studies in 4 years by selecting 4 courses of 4 credit hours in each of 8 semesters for a total of 128 credit hours. The impact of this new curriculum template on Materials Science and Engineering education at Michigan will be described. Emphasis will be placed on proposed changes in laboratory and design courses to accommodate a strong and professionally administered engineering communications segment. The approaches used to provide breadth and depth in the MSE curriculum will also be described. Finally, the impact of these college-wide changes on MSE's role in providing an introductory materials education to non-MSE majors will be described.
DEFINING THE CORE MATERIALS CURRICULUM II: Looking Forward Sponsored by: TMS Education Committee Program Organizers: Anthony D. Rollett, Materials Science &Engineering Dept., Carnegie Mellon University, Pittsburgh, PA 15213; Martin A. Crimp, Dept. of Materials Science and Mechanics, Michigan State University, East Lansing, MI 48824
Tuesday, PM February 11, 1997
Room: 340D Location: Orlando Convention Center
Session Chairperson: Martin Crimp, Dept. of Materials Science and Mechanics, Michigan State University, East Lansing, MI 48824
3:45 pm INVITED TITLE TBA: Harold Weinstock, Air Force Office of Scientific Research, 110 Duncan Avenue, Bolling AFB DC 20332-0001
2:00 pm INVITED TITLE TBA: James C. Williams, General Electric Aircraft Engines, 1201 Edison Drive, Cincinnati, OH 45216
4:15pm PANEL DISCUSSION: Participants to be announced. A summary of the symposium as completed by the Panel Discussion is planned to be submitted for publication in the JOM.
2:30pm THE STRUCTURE OF MATERIALS ENGINEERING; A NEW MODEL FOR MATERIALS ENGINEERING CURRICULA: Blair London, Linda S. Vanasupa, Robert H. Heidersbach, Materials Engineering Department, California Polytechnic State University, San Luis Obispo, CA 93407 We have developed a new model for the materials engineering curriculum designed around a structure that must be carefully "built" during our program. The model clarifies the materials engineering curriculum, representing a new organizational structure that incorporates the broad concepts yet allows room for technological changes. We used four guiding principles: (1) the curriculum must impart certain core competencies to the students, (2) the courses are either four or five units (quarter system), many with a strong laboratory emphasis, (3) the sequence of courses is logical and can be clearly communicated, and (4) it must be accredited. The model can be summarized by the major physical features of the building. The foundation includes an introduction to materials engineering and a course on the structure of solids. The pillars represent the four basic parts of materials engineering (thermodynamics, kinetics, mechanical properties, electronic properties) that are common to, and "hold up", all other aspects of the field. The roof consists of basic courses in metals, ceramics, polymers, and composites along with several technical electives. Finally, the building shows the capstone Senior Project as the culmination of their undergraduate education. 2:55pm MATERIALS SCIENCE CURRICULUM: HOW WE SHOULD BE CHANGING IT: David Laughlin, Dept. Materials Science & Engineering, Carnegie Mellon Univ., Pittsburgh, PA 15213 The Materials Science curriculum in many Universities is a direct descendant of their Metallurgy or Metallurgical Engineering curriculum. As such, they often have in them "relics" of the past that seem to some to be outdated. One
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the void (Coble creep mechanism [Wong et. al., v.l12, 1990, pp.l04-109]). Distributed void growths along grain boundaries further propagates into a macrocrack and percolation models are employed to study this growth of microcracks into a macrocrack. Existing, well established macrostructural fracture mechanics methods, such as the C- conservation integral, are used to model the macrocrack propagation.
DESIGN AND RELIABILITY OF SOLDERS AND SOLDER INTERCONNECTS: Session IV: Reliability of Solder Interconnects Sponsored by: MSD Flow and Fracture; SMD Mechanical Metallurgy; EMPMD Electronics Packaging and Interconnection Materials Committees Program Organizers: R.K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; D.R. Frear, Sandia National Laboratory, Mail Stop 1411, Albuquerque, NM 87185; S.M.L. Sastry, Washington University, Mechanical Engineering Dept., St. Louis, MO 63130; K.L. Murty, North Carolina State University, Materials Science and Engineering Dept., Box 7909, Raleigh, NC 27695; P.K. Liaw, University of Tennessee, Materials Science and Engineering Dept., Knoxville, TN 37996; W.L. Winterbottom, Reliability Consultant, 30106 Pipers Lane Court, Farmington Hill, MI 48331
Tuesday, PM February 11, 1997
2:25 pm INVITED THE NIST SOLDER INTERCONNECT DESIGN TEAM PROGRAM: James A. Warren, Carol A. Handwerker, Metallurgy Division, Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 The NIST Solder Interconnect Design Team has been found to address several pressing issues in the design and fabrication of circuit board. Having met frequently over the past three years, in partnership with academic and industrial researchers, the Team has established an agenda for solving solder joint shape, and the consequential thermal/mechanical properties of the formed joint. Our ultimate goal is to provide the industrial community with a suite of useful software tools for solder interconnect design, and to provide solved test problems (available electronically on the World Wide Web), that can be modified to suit the needs of the particular user. With this in mind we are actively supporting the development of software which will interface the public domain program Surface Evolver, which has been shown to be quite capable at computing equilibrium meniscus shapes. A discussion of the outstanding problems, as well as the software tools under development will be presented.
Room: 332 Location: Orlando Convention Center
Session Chairpersons: Paul T. Vianco, Sandia National Laboratories, Department 1831, Mail Stop 0340, P.O. Box 5800, Albuquerque, NM 87185; James A. Warren, Metallurgy Division, Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899
2:00 pm INVITED MICROSTRUCTURAL CREEP DAMAGE MODELFORPOLYCRYSTALLINE VISCOPLASTIC MATERIALS: Abhijit Dasgupta, CALCE Electronic Packaging Research Center, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742
2:50 pm INVITED MODELING NON-ISOTHERMAL INTERMETALLIC LAYER GROWTH IN THE 63Sn-37Pb SYSTEM: Paul T. VianeD, P.L. Hopkins, K.L. Erickson, D.R. Frear, R. Davidson, Department 1831, Mail Stop 0340, P.O. Box 5800, Sandia National Laboratories, Albuquerque, NM 87185
Fatigue failures in visco-plastic interconnects, such as solder joints, are a potentially reliability hazard in surface-mount electronic packages under cyclic thermal and mechanical loading environments. The intermittent nature of the observed failures suggests that solder joint failures may in fact account for a significant fraction of field removals which could not be duplicated (CND) during root-cause failure analysis. Proper design and reliability assessment are thus crucial to ensure the fatigue endurance of electronic packages. Accurate modeling of damage within the solder joint under cyclic thermal and mechanical loading conditions is important not only for accurate predictions of fatigue life but also for designing fatigue resistant microstructures for new emerging solder compositions. A micromechanical model is proposed in this study to model the fatigue damage mechanisms in solder joints during temperature and vibration loading. The problem is complex since most eutectic solders behave in a highly viscoplastic manner at room temperature due to the relatively high homologous temperature. Further the microstructure of solder changes significantly due to dynamic recrystallization processes and hence microstructural evolutions need to be tracked and implemented in the damage model. The advantage of the proposed model is inherent in its capability to capture the physics of the underlying microstructural damage mechanisms as opposed to existing phenomenological models. The model will be partitioned into two parts to address the different damage mechanisms caused by both plasticity and creep deformations. The plasticity induced damage mechanisms will dominate at low temperatures and high strainrates while the reverse is true for creep induced mechanism. Both mechanisms will compete in a general loading such as combined vibration and temperature cycling. The two competing mechanisms will be analyzed and the effects individually captured. In the paper the damage due to creep deformations will be addressed. Damage due to plastic deformations will be presented in a future paper. The model development in this paper will involve the creepinduced damage mechanism which will dominate during high temperature portion of thermal cycling. Due to cyclic thermal energy, dislocations will be more mobile and will have a lesser tendency to pile-up and create a stress concentration region. Hence plasticity induced due to pile-up of dislocations is assumed to be negligible. Void nucleations at triple points due to grain boundary sliding and creep-cavitation is assumed to be predominant cause of failure by creep. Stress concentrations at grain-boundary triple points is modeled by considering grain-boundary sliding [Zubelewicz, 1. Mech. Phys. Solids, v.4l, No. II, 1993, pp. 1711-1722]. Void instability [Huang et. al., to be published, 1996] is used as a metric for creep-fatigue damage initiation. A void growth along grain boundary is modeled by diffusion of vacancies into
The reliability of mechanical and electronic systems can be acutely dependent on the integrity of the soldered joints used in their assembly. During product manufacture, intermetallic layers from in reaction zones between the dissimilar materials of solder joints. Thermal cycling during service can cause further growth of the intermetallic layer, which may jeopardize the mechanical integrity of the joint as well as its capacity for rework or repair later on. Models describing service-related changes to solder joint microstructure are essential to understanding and predicting the long-term mechanical reliability and serviceability of these interconnects. In previously published work (J. Electronic Materials, v. 23, No.8, 1994, pp. 721-729) a model describing the diffusion-controlled growth of multiple intermetallic layers and the displacement of the interfaces between layers was developed and implemented in a one-dimensional computer code based on the method-of-lines. The model can accommodate cases involving: (I) finite initial layer thickness, (2) ratelimiting interfacial reactions, (3) multiple and variable diffusion coefficients, and (4) finite material boundaries. Additionally, the effects of nucleation can be modeled empirically. A transformation of spatial coordinate circumvented the need to remesh the growing and (or) shrinking layers. Results from the one-dimensional code were verified by comparing the numerical output with analytical solutions for simple systems involving two, three, and five layers. The computer code was then applied for analysis of intermetallic layer growth from solder aging experiments performed with lOOSn and 63Sn-37Pb solders. The analysis indicated that intermetallic layer growth was consistent with bulk diffusion mechanism involving Cu and (or) Sn and variable diffusion coefficients that reflect some enhanced diffusion during early growth. In this work, non-isothermal solder-aging experiments were done with the 63Sn37Pb/Cu system using two temperature histories: a low frequency history consisting of 4 cycles per day between -50 and 170°C, and a high frequency history consisting of 72 cycles per day and the same limits. Thicknesses of both the Cu,Sn and Cu6Sn5 intermetallic layers were determined as a function of time for both temperature histories. An enhanced version of the previously developed model was used to predict the non-isothermal intermetallic layer growth for both temperature histories. Arrhenius expressions for diffusion coefficients in both the Cu,Sn and Cu6Sn5 layers were determined using experimental data from previous isothermal studies. This paper describes the non-isothermal experiments and a comparison of calculated and observed layer growth as a function of time. This work was performed at Sandia National Laboratories and supported by the U.S. Department of Energy under contract DE-AC04-94AL8500'
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3:15 pm BREAK
ratio but is independent of the other material parameters and the slenderness ratio. The nonlinear stiffness results presented in the paper may be used to create more efficient finite element models of entire assemblies by replacing each column with a single nonlinear spring element. When used in conjunction with an appropriate Coffin-Manson relationship, the maximum shear strain curves presented herein may be utilized to estimate column fatigue life.
3:25 pm INVITED SOLDER JOINT FORMATION, SIMULATION AND RELIABILITY PREDICTION: Xiaohua Wu, Kai Hu, Xinyu Dou, Gary Mui, Chao-pin Yeh, and Karl Wyatt, Applied Simulation and Modeling Research (ASMR), Corporate Software Center (CSC), Motorola Inc" 1303 E. Algonquin Road, Mail Stop: ILOIIANX2, Schaumburg, IL60196
4:40pm EFFECT OF ASSEMBLY STIFFNESS AND TEMPERATURE CYCLE PARAMETERS ON THERMOMECHANICAL RESPONSE OF SOL. DER JOINTS: Ahmer Syed, Delco Electronics Corporation, MIS TlOO-26, 700 East Firman Drive, Kokomo, IN 46904
The fatigue-induced solder joint failure of surface mounted electronic devices has become one of the most critical reliability issues in electronic packaging industry. Solder joint reliability performance has been found to be highly dependent on the solder joint configuration, which, in tum, is governed by bond pad size, component weight, alloy material, and leadframe structure, as well as solder reflow characteristics. The objective of this work is to develop numerical models: I) to simulate the solder joint formation during the reflow process; 2) to determine the stress/strain distribution within the joint; and 3) further predict the reliability (fatigue life) of the solder joints. The solder joint formation process during solidification stage can be simulated using the Surface Evolver software tool developed by University of Minnesota. The thermomechanical stress-strain analysis can then be carried out using ANSYS to study selected critical design/manufacturing parameters such as leadframe geometry, pad size and dimensions, solder paste volume, leadframe placement misalignment, etc. This effort also involves the development of interface linking Surface Evolver and ANSYS.
Grain boundary sliding and matrix creep are recognized as the main contributors to creep behavior of eutectic SnlPb solder joints in thermomechanical loading. The relative contribution and dominance of these mechanisms in the total response is governed by the external (temperature, assembly stiffness, CTE mismatch) as well as the internal shape (shape, size and thickness of the solder joint) factors. This paper examines the effect of external factors on the grain boundary and matrix creep response of solder joints. Experimental as well as numerical techniques are employed to compare which mechanism dominates under several different assembly stiffness and temperature profile conditions. A fatigue life prediction model which accounts for different mechanisms is used to determine the impact of grain boundary sliding and matrix creep on solder joint fatigue life.
3:50 pm INVITED COMPUTATIONAL CONTINUUM MODELING OF SOLDER JOINT INTERCONNECTS: Steve Burchett, M.K. Neilsen, D.R. Frear, 1.1. Stephens, Department 9117, Mail Stop 0443, P.O. Box 5800, Sandia National Laboratories, Albuquerque, NM 87185
5:00pm BEHAVIOR OF SOLDER JOINTS UNDER COMPLEX DISPLACEMENT LOADING: Matthew G. Bevan, Manfred Wutting, The John Hopkins University, Applied Physics Laboratory, John Hopkins Road, Laurel, MD 20723
The most commonly used solder for electrical interconnects in electronic packages is the near eutectic 60Sn-40Pb alloy. This alloy has a number of processing advantages (suitable melting point of 183°C and good wetting behavior). However, under conditions of cyclic strain and temperature (thermomechanical fatigue) the microstructure of this alloy undergoes a heterogeneous coarsening and failure process that makes prediction of solder joint lifetime complex. A visco-plastic, microstructural dependent, constitutive model for solder has been developed and implemented into a finite element code. With this computational capability, the thermomechanical response of solder interconnects, including microstructural evolution, can be predicted. This capability was applied to predict the thermomechanical response of various solder interconnects to determine the effects of variations in geometry and loading. In this paper, the constitutive model will be briefly discussed and response predicted by the constitutive model will be compared to material test results. Finally, the results of computational studies to determine the effect of geometry and loading variations will be presented. This work was performed at Sandia National Laboratories, and supported by the U. S. Department of Energy under Contract No. DE-AC04-94AL8500.
In many applications, solder is exposed to a complex fatigue spectrum composed of thermal effects, shock and vibration. In the laboratory; however, solder is usually tested using simple wave forms generated by mechanical testers or by thermal cycling. In order to apply laboratory results to predict the real world fatigue, several crucial steps are necessary. One of these steps is understanding how to combine the effects of simple displacement (or stress) waves to predict the effects of complex waves. One method of combining waves is to use a linear damage accumulation model employing rainflow analysis. Briefly, rainflow analysis establishes an envelope to strain (or stress) range of the waveform, and then measures the reversals within the range. Damage from the envelope is added to the damage from the individual reversals within the envelope to calculate the damage of the whole cycle. The linear damage accumulation model is not valid for all loading conditions. Damage is accumulated in a linear fashion, assuming there is no wave-towave interaction. For Mode I (tensile) loading, this assumption is known to be false. Six mechanisms for-wave-to-wave interaction are known. The waveto-wave interaction can significantly accelerate or delay fatigue crack propagation. In contrast, Mode III (tearing) loading has shown no wave-to-wave interaction. Very little research has been done to investigate damage accumulation in solder. The paper looks at single solder joints in shear. First the fatigue behavior of the solder joints is characterized using sine waves under displacement control. Then by looking at sums of waves with a constant displacement envelope, the damage from minor waves may be separated from damage from the major, envelope wave. The results show that the linear damage accumulation model (using rainflow analysis) is accurate as long as the minor waves remain in the elastic range. Once the minor waves begin to generate plastic deformation, the damage accumulates more rapidly than predicted.
4:15 pm INVITED AN ELASTOPLASTIC BEAM MODEL FOR COLUMN-GRID-ARRAY (CGA) SOLDER INTERCONNECTS: Steven M. Heinrich l , 1. A. Swanson! and P. S. Lee', 'Department of Civil and Environmental Engineering, Marquette University, Milwaukee, WI 53233; !Rockwell Automation,AlIen-Bradley Co., Milwaukee, WI 53233 A semi-analytical model is developed and implemented to analyze the deformation of solder columns in column-grid-array (CGA) assemblies. Each solder column is modeled as a prismatic beam of circular cross-section, subjected to end shearing deflections caused by thermal mismatch between the module and the circuit board. The solder is idealized as an elastic-perfectly plastic material whose yielding is governed by the Von Mises criterion. Since the columns are relatively short, transverse shear deformation has been incorporated into the beam model. The results generated with the model indicate the following: (a) yielding is governed by bending for slenderness ratios (height-to-diameter) ofhld<:l1 {3; (b) the nonlinear stiffness relationship for a sheared column, presented in dimensionless form, reduces to a single curve which is valid for arbitrary values of slenderness ratio (<:11 {3) and material parameters; (c) the dimensionless relationship between maximum shear strain (in the Tresca sense) and the relative end deflection depends on Poisson's
5:20pm THERMOMECHNICALFATIGUE TESTING OF SOLDER ALLOYS: Mark A. Palmer, P.E. Redmond, R.W. Messler, Jr., Materials Science and Engineering Department, Rensselaer Polytechnic Institute, Troy, NY 12180 Thermomechanical fatigue (TMF) is one of the most common sources of failure in solder joints. TMF occurs due to thermal cycling, as a cyclic stress is induced on the solder joint due to thermal expansion mismatch. Due to the complicated nature of thermomechanical fatigue, directly testing a material's resistance to TMF is not straight forward. A novel test apparatus has been developed which allows the direct measurement of stress due to thermal cy-
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cling. The TMF behavior of three alloys. eutectic Sn-Bi, Sn-Pb, and Sn-Ag as examined by this apparatus will be presented. The data will be compared with that generated by other test methods.
3:00pm CHARACTERIZATION OF GRAIN BOUNDARIES IN Al INTERCON· NECTS BY ORIENTATION IMAGING MICROSCOPY: C. Wu, c.L. Bauer, B.L. Adams, W.W. Mullins, Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA
EVOLUTION AND ADVANCED CHARACTERIZATION OF THIN FILM MICROSTRUCTURES IV: Evolution of Microstructure
Characterization of microstructure (grain orientation, grain-boundary inclination, microtexture, etc.) in thin-film interconnects is especially important because grain size usually approximates film thickness, thereby enhancing short-circuit diffusion induced by electric fields (electromigration), mechanical stress (stress voiding), temperature gradients (thermomigration), and capillarity (grain-boundary grooving). In this research, grain boundaries in polycrystalline Al interconnects have been characterized by orientation imaging microscopy and analyzed in terms of the interconnectivity of triple junctions. In general, results indicate that a variety of thermodynamic and kinetic properties can be extracted by rapid acquisition and processing of large data sets and correlated with the (five) degrees of crystallographic freedom of individual grain boundaries. Research supported, in part, by the National Science Foundation under Grant DMR-93 19896.
Sponsored by: MSD Structures Committee, EMPMD Thin Films and Interfaces Committee Program Organizers: Eric P. Kvam, School of Materials Engineering, Purdue University, West Lafayette, IN 47907-1289; Steven M. Yalisove, Dept. Materials Science and Eng., HH Dow Bldg., University of Michigan, 2300 Hayward St., Ann Arbor, MI48109-1204; Eric P. Chason, Sandia National Labs., Dept. 1112, MS 1415, PO Box 5800, Albuquerque, NM 87185
Tuesday, PM February 11, 1997
Room: 340C Location: Orlando Convention Center
3:20pm REAL· TIME MEASUREMENTS OF MICROSTRUCTURAL EVOLU· TION IN Ag THIN FILMS ON Si02: Eric Chason, Jerry Floro, Sandia National Laboratories, Albuquerque, NM 87185-1415; Steven C. Seel, Carl Thompson, Massachusetts Institute of Technology, Cambridge, MA
Session Chairs: J.P. Sullivan, J.A. Floro, Sandia National Labs, Albuquerque, NM 87185
2:00 pm INVITED EVOLUTION OF GRAIN STRUCTURE IN THIN FILM REACTIONS: K. Barmak, Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015
Understanding and controlling the microstructure in thin metal films used for IC interconnects is essential for maintaining high reliability. Although the microstructure of AI films has been heavily studied, the switch to Cu for interconnects in the future will lead to different microstructural evolution than in current technology. In order to study the kinetics of grain growth and texture evolution, we have developed an in situ X-ray system that can measure the concurrent evolution of (Ill) and (100) textured crystallites during annealing. We present results from the annealing of Ag films, which have similar elastic properties to Cu. This work was supported by the U.S. Department of Energy under contract DE-AC04.
The granular nature of polycrystalline thin films is playing an increasingly important role in their performance as the dimensions of the grains and those structures in which the thin films are used become comparable. Consequently, greater attention is being paid to the factors that affect the grain structure of thin films and its evolution. This paper will address the evolution of grain structure during the reaction of polycrystalline thin films. Experimental evidence from calorimetry, x-ray diffraction and transmission electron microscopy studies of a number of thin film systems will be reviewed and the role of reactant phase microstructure in these reactions will be highlighted. Theoretical models that combine nucleation and growth processes in the formation of the product phase will be presented and the impact of heterogeneous boundary nucleation on the evolution of grain structure in thin film reactions will be discussed.
3:40 pm BREAK 4:00 pm INVITED STRESS RELAXATION AND THERMAL EVOLUTION OF FILM PROPERTIES IN AMORPHOUS CARBON: J.P. Sullivan, Sandia National Labs, Albuquerque, NM 87185 Large stress relaxation is observed in amorphous carbon films deposited by pulsed-laser deposition which are subsequently thermally annealed. In the as-deposited state, the films exhibit very high compressive stress, > 6 GPa, which has been thought to be either necessary or unavoidable in order to form a high percentage of 4-fold coordinated (diamond-like) carbon bonds and which can also hamper important electronic applications of these films. Stress measurements performed in situ and ex situ following thermal annealing up to 600°C indicate the stress may be reduced nearly two orders of magnitude. The stress relaxation is not dominated by interfacial relaxation nor is it accompanied by large scale changes within the film (e.g. graphitization) as indicated by in situ and ex situ electrical measurements, ex situ X-ray reflectivity, Raman spectroscopy, and experiments using different substrates. The bonding structure and mechanisms of thin film evolution in these unique amorphous films will be discussed. Work at Sandia was supported by an LDRD through the U.S. DOEunder contract no. DE-AC04-94AL85000 and by a CRADA.
2:40pm THE MICROSTRUCTURAL DEVELOPMENT OF THIN FILM COP· PER GOLD ORDERED INTERMETALLIC COMPOUNDS: Jonathan Gorrell, Paul Holloway, Dept. of Material Science and Engineering, University of Florida, Gainesville, FL 32611-6400; Hal Jerman, EG&G IC Sensors, 1701 McCarthy Blvd., Milpitas, CA 95035 Recent developments in microelectromechanical systems (MEMS) have created a need for stronger metal thin films that are resistant to stress relaxation. Intermetallic compounds are noted for their strength and resistant to creep, but these properties have rarely been studied in thin films of intermetallics. We have sputter deposited layered structures of copper and gold so that the intermetallic compounds Cu3 Au, CuAu and CuAu J would form. The samples were initial heated to 475°C to allow intermixing of the copper and gold layers and the evolution of the intrinsic and extrinsic stresses were characterized during the process. The samples were then annealed at temperatures where the intermetallic phases would form. The intermetallic phases were tested for strength and stress relaxation using a Tencor Flexus 2320. The microstructure and composition were examined with TEM, EDX, Electron Microprobe, and X-Ray diffraction. This data allows us to relate strength and resistance to stress relaxation to microstructure and the heat of formation of the various copper gold intermetallic compounds.
4:40pm MICROSTRUCTURE AND TEXTURE DEVELOPMENT IN CUBIC BORON NITRIDE THIN FILMS: D.L. Medlin, P.B. Mirkarimi, G.P. Cardinale, K.P. McCarty, Sandia National Laboratories, Livermore CA 94551 Cubic boron nitride (cBN) is an sp'-bonded material with many properties and applications that are similar to diamond. Although cBN can be synthesized in bulk form at high temperature and pressure, synthesis in thin film form requires the simultaneous bombardment of the growing film with a high flux of energetic ions. cBN films grow with a unique. layered microstructure in which sp2-bonded graphitic boron nitride initially forms near the substrate
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interface, and nucleation and growth of the sp'-bonded cubic phase occurs further up in the film. Both the graphitic and cubic layers exhibit strong preferential crystallographic orientations: the graphitic layer possesses a strong in-plane [0002J orientation, whereas the cBN possesses an in-plane [111J orientation. This preferential orientation is consistent with an alignment between the cBN {III} planes and the basal planes of the layer of highly oriented graphitic boron nitride that forms in the initial stages of film growth. This relationship provides insight into the mechanisms controlling the initial nucleation of cBN and subsequent microstructural evolution of the films. This work is supported by the U. S. Department of Energy under contract DEAC04-94AL85000 and in part by OBES-DMS. 5:00pm CHARACTERIZATION OF SrRu03 THIN FILMS: MICROSTRUCTURE / PROPERTY RELATIONSHIP: F. Chu, Q.x. Jia, C. Adams, T.E. Mitchell, Materials Science and Technology Division, Mail Stop K 765, Los Alamos National Laboratory, Los Alamos, NM 87545; Q. Zhu, Physics Department, Brookhaven National Laboratory, Upton, NY 11973 Metallic oxide SrRuO J thin films have been grown using pulsed laser deposition on LaAl0 3 substrates at different substrate temperatures. The surface morphology and microstructural properties of the SrRuO/LaAl0 3 system have been studied using high resolution synchrotron x-ray diffraction, conventional x-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Electrical properties of SrRu03 thin films with different microstructures have been measured. It is found that films deposited at 250°C are amorphous, and show semiconductor-like temperature dependence of electrical conductivity. Films deposited at 425°C are crystalline with very fine grain size (lOO-200A), and show both metallic and semiconductor-like temperature dependence of the electrical conductivity in different temperature regions. Synchrotron x-ray diffraction and transmission electron microscopy unambiguously indicate that epitaxial [001] and [110] growth of the orthorhombic films takes place for deposition temperature above 650°C, where the [OOlJ texture is dominant. Films deposited at 775°C show a resistivity of 280 mW-cm at room temperature. Microstructures of epitaxially grown films and possibilities for improving the thin film growth are discussed, based on geometric considerations for both film and substrate. The optimized deposition conditions to grow SrRu03 thin films on LaAI0 3 substrates have been found. Possible engineering applications of SrRu0 3 thin films with different microstructures are discussed.
FUNDAMENTALS OF GAMMA TITANIUM ALUMINIDES IV: Microstructure- Property Relationships-Strength, Plasticity and Toughness Sponsored by: MSD Flow & Fracture and Phase Transformations Committees Program Organizers: Kwai S. Chan, Southwest Research Institute, San Antonio, TX 78228-0510; Vijay K. Vasudevan, Dept. of Materials Science & Engineering, University of Cincinnati, CinCinnati, OH 45221-0012; Young-Won Kim, UES, Inc., Dayton, OH 45432-1894 Tuesday, PM February 11, 1997
Room: 330E Location: Orlando Convention Center
Session Chairpersons: Chain T. Liu, Oak Ridge National Laboratory, Metals & Ceramics Div., PO Box 2008, Oak Ridge, TN 37831-6115; G.T. (Rusty) Gray, III, Los Alamos National Laboratory, Los Alamos, NM 87545
1:55 pm OPENING REMARKS 2:00 pm INVITED THE ROLE OF GRAIN SIZE AND SELECTED MICROSTRUCTURAL PARAMETERS IN STRENGTHENING FULLY-LAMELLAR TiAI ALLOYS: D.M. Dimiduk, Wright Laboratories Materials Directorate, WLIMLLM, WPAFB, Dayton, OH 45433; P.M. Hazzledine, T.A. Parthasarathy, UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432; S. Seshagiri, SYSTRAN, Inc., 4126 Linden Ave., Dayton, OH 45432 More than five years ago wrought processing was first used to produce fullylamellar microstructures in TiAI alloys having grain sizes less than -400mm. These alloys exhibit an improvement in overall balance of properties, especially at high temperatures. More recently, such microstructural forms led to exceptional yield strengths (>1000Mpa at low temperatures), while maintaining attractive high-temperature properties. The improvements appeared to be attained principally through an unusually high apparent sensitivity of strength on grain size. Studies reported an apparent value for the slope of the "Hall-Petch plot" approaching 5 Mpa-Jm for fully lamellar gamma alloys, while that for single phase or duplex microstructures is near unity. The present investigations examine the slope of the Hall-Petch plot for fully lamellar microstructures, paying particular attention to the lamellar microstructural variabies. Results show that a,-lamella thickness and spacing, and y -lamella thickness can vary over more than two orders-of-magnitude. These in tum influence the value of cm in the Hall Petch plot, and often change concomitantly with grain size in processing. Nonetheless, the corrected value of the HallPetch constant exceeds a magnitude of 2 Mpa-Jm; and it is strain dependent. The investigations also examine dislocation activity, flow behavior, glide barriers and slip multiplicity for polysynthetically twinned or PST crystals (single-grain analogue of fully lamellar material), then map this behavior into an explanation of the yield behavior of high strength fully lamellar gamma alloys. 2:30 pm INVITED BULK, DEFECT, AND INTERFACIAL PROPERTIES OF TiAI AND Ti3AI: M.H. Yoo, C.L. Fu, Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
,
Available theoretical and experimental data on the elastic constants, point defect properties, shear fault energies, and ideal cleavage energies of TiAI and Ti3AI are reviewed, including the recently calculated y /y and a/yinterfacial energies. Enhanced slip by ordinary dislocations along pseudo-twin and rotational y /y and the <4yinterfaces is a contributing factor to the strong plastic anisotropy of a fully lamellar microstructure. According to the calculated interfacial fracture energies, cleavage cracking is to occur on o.,/y boundaries and the least likely on true-twin boundaries. The roles of misfit dislocations, kinetics of dislocation-interface interactions, and hydrogen embrittlement in deformation and fracture of two-phase TiAI alloys are discussed. This research was sponsored by the Division of Materials Sciences, U.S. Department of Energy, under contract number DE-AC05- 960R22464 with Oak Ridge National Laboratory, managed by Lockheed Martin Energy Research Corporation.
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3:00pm INTERNAL STRESSES IN LAMELLAR nAl: P.M. Hazzledine, UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432; M.A. Grinfeld, Department of Mechanical and Aerospace Engineering, Rutgers University, P.O. Box 909, Piscataway, NJ 08855; D.M. Dimiduk, Wright Laboratories Materials Directorate, WUMLLM, WPAFB, Dayton, OH 45433
4:20pm PLASTIC INSTABILITIES IN Y -TiAl AND THEIR RELATION TO WORK HARDENING AND TOUGHNESS: Franfois Louchet, Groupe Physique du Metal, LTPCM- UMR.CNRSIINPGIUJF, B.P. 75, Domaine Universitaire, 38402 - St Martin d'H'eres, France Flow stress anomaly in y -TiAI is associated, as in many other intermetallics, to a strain rate sensitivity (SRS) close to zero, to plastic instabilities, and to a high work hardening rate (WHR). In situ TEM observations also show ajerky motion of groups of cusped ordinary screw dislocations (1), in agreement with macroscopic instabilities. The present paper investigates these instabilities in the framework of the Local Pinning Unzipping (LPU) model (2), in which the flow stress anomaly and the low value of the SRS are predicted as a consequence of a balance between dislocation exhaustion and multiplication rates. This balance is applied here to groups of N dislocations, and results in a non linear equation in N, from which the minimum stress required to deform the material at a given strain rate can be determined. The corresponding average value of N is obtained as a function of temperature. The consequences of the temperature dependence of N on both WHR and toughness are discussed. Possible consequences on the particular dramatic brittleness of PST materials loaded perpendicular to lamellar boundaries (3), in which slip in y-TiAI takes place across lamellae, can also be contemplated as a function of these instabilities, and particularly in terms of the variations with temperature of the number N of dislocations in pile-ups. (1). S. Farenc and A. Couret, Mat. Res. Soc. Symp., 1993, vol. 288, p. 465. (2). F. Louchet et B. Viguier, Phil. Mag. A, 1995, vol. 71, p.l313. (3). M. Yamagushi, H. Inui, K. Kishida, M. Matsumoro and Y. Shirai, Mat. Res. Soc. Symp., 1995, vol. 364, p.163.
Internal stresses necessarily develop in multilayered coherent materials with mismatched lattice parameters as the individual layers adjust to their neighbors. In Ti-Al the layers consist of ~ plates and six orientation variants of gamma plates which occur in an apparently random sequence. The internal stresses in anyone layer are affected by the orientations of all its neighbors. We have calculated, in closed form, the stresses present in one layer of a stack of gamma layers in which the sequence of variants is in any order and of any length and in which the thicknesses of each layer may take any value. In addition we have calculated the stresses in a stack of alternating ex, and g layers of arbitrary thicknesses. The results are applicable directly to an idealized form of PST TiAl in which the domain size is large and the lamellae thickness is small. The relaxation of internal stresses which occurs in thick lamellae and by the formation of domains is discussed. The consequences of both these relaxations to the plastic strength of PST TiAI are examined. 3:20pm RELATIONSHIPS BETWEEN MICROSTRUCTURE/COMPOSITION AND MECHANICAL PROPERTIES OF GAMMA TITANIUM ALUMINIDES: WOo Soboyejo, Y. Ni, C. Mercer, Dept. of Materials Science and Engineering, Ohio State University, 2041 College Road, Columbus, OH 43210; A.B.O. Soboyejo. Dept. of Aerospace Engineering, Applied Mechanics and Aviation, Ohio State University, 155 W. Woodruff Ave., Columbus, OH 43210; R. Armstrong, Dept. of Mechanical Engineering, University of Maryland, College Park, MD 20742
4:30pm MORPHOLOGICAL ASPECTS OF 1/2<110] UNIT DISLOCATIONS IN YAND (ex, +y) TiAl ALLOYS: Sriram Seshagiri, SYSTRAN Corporation, 4126, Linden Ave., Dayton, OH 45432; Dennis M. Dimiduk, Materials Directorate, WLIMLLM, WPAFB, OH 45433; Vijay K. Vasudevan, Dept. of Materials Sci. & Eng., Univ. of Cincinnati, Cincinnati, OH 45221
Quantitative relationships will be presented for the prediction of basic mechanical properties (yield/ultimate tensile strength, fracture toughness and plastic elongation to failure) at room- and elevated- temperature. These include Hall-Petch relationships between basic mechanical properties and the average equiaxed grain sizellamellar packet size. Multiple linear regression expressions are also presented for the prediction of the effects of grain/packet size, lamellar volume fraction and composition. The observed grain size dependence of mechanical properties is shown to be consistent with Hall-Petch exponents predicted for dislocation/dislocation and dislocation/grain boundary interactions in duplex ex, + y alloys. The implications of the empirical relationships are assessed for the engineering of balanced mechanical properties in gamma titanium aluminides.
The b= 112< II 0] unit dislocations are a dominant part of the deformation substructure in both single phase (y) and two-phase (ex,+y) TiAI alloys, at ambient temperatures and above. These dislocations have been characterized in a coarse-grained (-300 mm) single-phase binary TiAI alloy. The results show that these dislocations undergo double cross-slip, resulting in numerous pinning points Gogs) and mixed character dislocation segments bowed about these pinning points, giving rise to a cusped morphology. The linear pinningpoint density in single-phase alloys increases with deformation temperature from -2-5 mm- J at RT, to -10 mm- J at higher temperatures, with an attendant increase in the yield strength of the alloy. In two-phase (ex,+y) fully-lamellar polycrystals and PST crystals the, g lamellae thicknesses are typically -I mm, which is approximately the same order as the free-segment length of the unit dislocations in the single-phase alloys. Hence, the morphological evolution of 112<110] unit dislocations in the fully lamellar material, wherein deformation propagation is constrained by the lamellae dimensions, is of particular interest. Transmission electron microscopy observations pertaining to these aspects, and their implications on strength and plasticity, will be discussed in the presentation.
3:40 pm BREAK 3:50 pm INVITED TEMPERATURE DEPENDENT DEFORMATION IN GAMMA TITANIUM ALUMINIDES S.H. Whang, Z.M. Wang, Q. Feng, C. Wei, Polytechnic University, Six Metrotech Center, Brooklyn, NY 11201 Deformation of gamma titanium aluminides may be best described by the lack of sufficient ductility at RT as well as intermediate temperatures, and the anomalous yielding at high temperatures. Such deformation behavior is mainly attributed to unusual behavior of two independent slip systems: superdislocation slip and ordinary dislocation slip, both of which simultaneously operate over the entire temperature range in the polycrystalline alloys. For this reason, the study on the role of individual slip system is required to carry out deformation experiments with single crystals of a y -TiAI alloy. In y -Ti-56AI, the yield stress curves of superdislocation slip show positive temperature dependence over two distinct temperature regimes while those for ordinary dislocation slip exhibit a single temperature range. These distinct temperature regimes can be explained with the characteristic features of the dislocation structures which were obtained from the postmortem examinations of the deformed specimens conducted by TEM. The thermodynamic aspects of both cross-slip configurations of superdislocations will be presented based on anisotropy strain energy calculations. Finally, the CRSS values depend on deformation orientation in superdislocation slip, in consistent with the cross-slip models. The details of the orientation dependence will be discussed.
4:50pm TENSILE/COMPRESSIVE PROPERTIES OF SINGLE CRYSTAL GAMMA Ti-55.5%AI ALLOY: Marc Zupan, Kevin J. Hemker, Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, MD 21218 Understanding of the deformation mechanisms that lead to the flow strength anomaly of Ni,Al has been greatly enhanced by the measurement of the orientation dependence of flow stress and tension/compression asymmetry. To date, lack of high quality single crystals sufficiently large to facilitate mechanical testing have precluded such studies of y TiAI. High quality single crystals of y-Ti(55.5% )Al have been grown using an optical float zone furnace, which provides a containerless growing environment. These crystals have been oriented and cut into microsample tension/compression specimens with a gage area of 250 mm x 250 mm and effective gage length of 300 mm. These specimens have been deformed using a microsample testing machine which applies loads on the order of I lb. and strain using an inter-
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ferometric strain gage. Stress-strain curves will be reported for a variety of orientations, temperatures and as a function of the sense of applied load. Experimental results will be discussed within the current context of current dislocation theories.
usefulness of heap leaching. Even in Nevada, difficulties can be encountered which call for special operating procedures. This paper discusses general climatologicallimitations and some of the techniques used to extend heap leaching into colder conditions. A case history of the Pikes Peak operation in Colorado examines "Valley-fill" technology as an ideal cold-climate solutions, where topographical conditions permit.
GLOBAL EXPLOITATION OF HEAP LEACHABLE GOLD DEPOSITS IV: Environmental, Climatology and Community Considerations in Heap Leaching
3:30 pm BREAK 3:40pm CYANIDE SOLUTION DETOXIFICATION JAR TESTS: c.H. Bucknam, Senior Coordinator, Newmont Metallurgical Services, Salt Lake City, UT 84108
Sponsored by: EPD Process Mineralogy, Precious Metals, Aqueous Process· ing Committees; Newmont Mining Corporation, Denver, CO Program Organizers: Donald M. Hausen, Consultant, 1767 S. Woodside Dr., Salt Lake City, UT 84124; David Dreisinger, University of British Columbia, Dept. of Metals & Materials Eng., 309·6350 Storres Rd., Vancouver, BC V6T 1Z4, Canada; Richard Kunter, Advanced Science, Inc., 405 Irvine St., Suite 401, Lakewood, CO 80278; William Petruk, CANMET, 555 Booth St., Ottawa, Ontario J1A 081; Richard D. Hagni, University of Missouri-Rolla; Dept. of Geology & Geophysics, Rolla, MO 65401
Tuesday, PM February 11, 1997
Environmental regulatory requirements for discharge of solutions and closure of operations for the gold mineral processing industry have been moving towards meeting USEPA inorganic drinking water standards. Use of jar tests for water treatment process development is suitable for preliminary scoping work, conducted in a research laboratory for optimization studies, and at the site of the water treatment. Experimental methods utilize standard jar test equipment in effort to produce solutions that meet standards for USEPA inorganic drinking water, after chemical treatment of cyanide solutions. The materials tested included gold-bearing pregnant solutions from heap leach op· erations, gold plant barren solutions from Merrill·Crowe zinc cementation gold recovery process and final gold heap-leach wash solutions after carbonin-column recovery. Experiments include cyanide destruction with sodium hypochlorite, and arsenic co-precipitation coupled with mercury precipitation.
Room: 231C Location: Orlando Convention Center
Session Chairpersons: R.R. Beebe, Consultant, Tucson, AZ; C.H. Bucknam, Senior Coordinator, Newmont Metallurgical Services, Salt Lake City UT
2:00 pm KEYNOTE COMMUNITY ASSISTANCE. AN INTEGRAL PART OF DOING BUSINESS IN THE MINING INDUSTRY: Leonard Harris, Consultant and Former General Manager, Minera Yanacocha, Peru; and Rosa H. Harris, President for Life of the Ladies Association of Minera Yanacocha (ADAMINYA), Lone Tree, CO 80124
4:05pm GREENSTONE RESOURCES LTD_· SANTA ROSA PROJECT: Randy Martin, Chief Operating Officer and Executive Vice President, Greenstone Resources Ltd., Toronto, Ontario, Canada M5E IS2 Greenstone Resources Ltd. constructed and operates the Santa Rosa open pit, heap leach gold mine in Veraguas, Panama. The project was commissioned in 1995 at a designed capacity of 1.8 million tons per year. The ore exhibits a long leach up to three years, and requires three stage crushing to minus 3/8 inch to achieve on average a 74% gold recovery. The crushing plant is required to handle high volumes of clay and the circuit includes a Barmac Crusher. Panama receives over 3 meters of rain annually and Greenstone is using innovative means to control the project's water balance. Greenstone has developed a successful approach to operating a low grade (1.5 gm AuIT) deposit under difficult operation conditions.
It is becoming increasingly obvious to mining and exploration companies,
when operating overseas, that their activities should not conflict with the interests of the surrounding communities. The world's largest heap leach operation, Minera Yanacocha, has installed community assistance programs in Peru, concerned with health, education, electrification, agricultural assistance and road improvements. The programs are conducted with joint venture government and non government organizations and a ladies association composed of the employees' wives and female staff. 2:40pm WINTER HEAP LEACHING AT PEGASUS GOLD'S BEAL MOUN· TAIN MINE: J.E. Micheletti, T.J. Weitz, Beal Mountain Mining, Inc., Anaconda, MT 59711
4:30pm THE PLASTIC INFLUENCE AND ITS APPLICATION IN LEACH· ING PROCESSES FAVORING COST AND ENVIRONMENTAL 1M· PACTS: Juan B. Cabezas, J.B.e. (Minermat Inc.) Consultorks, Santiago, Chile
Pegasus Gold's Beal Mountain Mine is located near the Continental Divide, SW Montana. Conventional surface mining utilizes crushing, heap leaching, carbon absorption/desorption, electro winning and refining to produce approximately 60,000 oz gold annually. A leach pad sits at 2,300 meters (7,500 ft) elevation. Winters are long and cold with average snow accumulations of 1-2 meters; temperatures fall below minus 40°C and wind chill temperatures below 70°C. The Beal Mountain staff has developed special tools and procedures for burying drip emitter lines, and managing the heap and process solutions to allow for uninterrupted gold recovery during the winter season. Management of water balance and spring runoff is critical to the operations' success, due to mountainous terrain, high precipitation and proximity to a fishery and elk herd. The mine has an extensive network of land application disposal (LAD) and stormwater control systems to assure environmental protection and regulatory compliance.
The favorable characteristics and workability of plastics as a replacement of wood, lead, stainless steel, asphalt and other materials are described. Various types of plastics have proven to be the most favorable choice for handling a variety of acidic, alkaline and organic solutions, as well as pulps, chemical wastes, slurries or tailings for impoundments. The material origin of various plastics, methods of manufacturing and specifications applied to leaching solutions are discussed, including availability and costs. Examples of select plastics are considered for use as alternatives of other materials under severe environmental requirements.
3:05pm OVERCOMING CLIMATOLOGY LIMITATIONS ON HEAP LEACH· ING: J.J. Komadina, Executive Vice President, Pikes Peak Mining Company, Victor, CO; R.R. Beebe, Consultant, Tucson, AZ 85751·2048 Heap leaching of gold ores has enjoyed wide acceptance in the arid and semiarid regions of the western U.S., Australia and South America. There are areas, however, where cold weather or excessive precipitation can limit the
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AgNiMg matrix. Short sample i values (I mV/cm) of up to SO,OOO Alcm' (4.2 K, B = 0) and 3000 Alcm' (77 K, B = 0) have been achieved in AglBi2212 multicore wires of I mm diameter. For AgNiMg/Bi-2212 multicore wires of 1.5 mm diameter maximum zero field j, values of 55,000 and 2000 Alcm' have been reached at 4.2 and 77 K, respectively. First results for the j, values in Bi-22l2 wires of long lengths will be presented.
HIGH TEMPERATURE SUPERCONDUCTORS IV: BSCCO and TBCCO Conductor Development Sponsored by: Jt. EMPMD/SMD Superconducting Materials Committee Program Organizers: U. Balachandran, Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439, Paul J. McGinn, University of Notre Dame, Notre Dame, IN 46556
Tuesday, PM February 11, 1997
3:00 pm INVITED HOT·DEFORMATION TREATMENTS OF Y123 AND Bi2223 MATE· RIALS: Q. Y. Hu, D. Yu, H.K. Liu, T. Chandra, S.x. Dou, Centre for Superconducting and Electronic Materials, University ofWoliongong, Wollongong, NSW 2500, Australia
Room: 315A Location: Orlando Convention Center
Session Chairpersons: K. Togano, National Research Institute for Metals, Tsukuba, Japan; R. D. Blaugher, National Renewable Energy Laboratory, Golden, CO
Yl23 and Bi2223 bulks were hot compressed isothermally in a temperature range of 7S0-S50°C under constant stresses of 15-50 MPa for 60 min. It was found that the mass density of the bulk Yl23 and Bi2223 superconductors has been increased. This was achieved by reducing the enclosed voids in the materials under the pressure at high temperature. In addition of high mass density, texture structure in the superconductors has also been improved by hot compressing which in turn increased critical current of both materials. Ag-sheathed Bi2223 wires were hot-rolled into thin tapes at about SOO°C at a four-high laboratory rolling machine with attachment of a tube furnace. It was found that hot-rolled tapes had higher core mass density but sausaging was severer than cold-rolled samples. Apart from the hot rolling, the Bi2223 tapes were also hot compressed under the condition of uniaxial loading and it was found that the treatment enhanced the core density, resulting in the improvement of the critical current of the samples.
2:00 pm INVITED THE EFFECT OF PROCESSING ON THE MICROSTRUCTURE OF Bi,8r,CaCup/Ag SUPERCONDUCTOR: K. Togano, H. Kumakura, H. Kitaguchi, H. Fujii, National Research Institute for Metals, Tsukuba 305, Japan; T. Hasegawa, Y. Hikichi, Showa Electric Wire and Cable Co., Ltd., Kawasaki 210, Japan The Bi,Sr,CaCuP/Ag(2212) conductors with high J, can be fabricated by applying partial melting process, in which the 2212 phase melts incongruently. However, the presence of nonsuperconducting solid phases in the liquid makes it very difficult to achieve an ideal grain alignment of 2212 phase on cooling. In this paper, we report detailed studies on the distribution of nonsuperconducting phases and its effect on the nucleation and growth behavior of 2212 crystals. As one of the methods to control the distribution, we applied centrifugal gravity fields of up to -100 g to the samples during melting process. Gravity effect was more significant for thick 2212 conductor, for which interface effect was less dominant. The improvement of grain alignment for the multilayered Ag/2212 conductors and the results of J, measurement will be presented.
3:20 pm INVITED EFFECT OF pO" C,AND Ag ON THE DECOMPOSITION PATHWAYS IN THE Bi·Sr·Ca·Cu·O: R. W McCallum, L. Margulies, K.W. Dennis, M.J. Kramer, Ames Laboratory, Iowa State University, Ames, IA 50011 The promise of usable forms of high temperature superconducting wires and tapes rests on developing techniques for processing highly textured materials. Understanding the effect of Ag and pO, on the chain of peritectic reactions initiated during melting is necessary in order to optimize the processing parameters of Bi-Ca-Sr-Cu-O-Ag composites. Previously, work on the solubility of Ag in the Bi2212 melt revealed a large liquid immiscibility gap and a eutectic on each side of this gap. In addition, the sub-liquidus phase reactions in this system were examined in greater detail for 0.01, 0.2, and 1.0 bar pO,. This work showed that the peritectic reactions varied as a function of pO,. The role of Ag was shown only to depress the peritectic decomposition temperatures. C was shown to have only a very minor effect for near stoichiometric materials. This work is currently being extended to the Bi222l + Ag system. Supported by U.S. Department of Energy, under Contract No. W7405-Eng-S2.
2:20pm REACT-WIND-AND-SINTER TECHNIQUE FOR THE MANUFACTURE OF POWDER-IN· TUBE Bi,Sr,CaCu,Ox COILS: 1. Schwartz, S. Boutemy, National High Magnetic Field Laboratory, ISOO E. Dirac Dr., Tallahassee, FL 32310 Heat treating powder-in-tube Bi,Sr,CaCu,O, coils such that short sample properties are obtained in large quantities is an important challenge. The windand-react technique suffers from poor temperature control due to the coil thermal mass and the sensitivity of the superconductor to the peak temperature and cooling rates. With the react-and-wind approach, however, optimum conductor performance is not obtained since it is degraded by strain during winding. A new technique is being developed at the NHMFL: the react-windand-sinter technique. Long lengths of powder-in-tube conductor are reacted by pulling the tape through a furnace with a controlled atmosphere. The temperature profile is controlled to emulate the partial-melt step of the conventional heat treatment. This method allows a more uniform reaction in long lengths of conductor. The tape is then insulated and wound into the desired coil shape and sintered isothermally. This repairs the cracks and achieves high phase purity and grain alignment. Here we report progress on this approach for HTS coils.
3:40 pm BREAK 3:50 pm INVITED THICK·FILM PROCESSING FOR TL·OXIDE WIRE AND TAPE: R.D. Blaugher, R.N. Bhattacharya, D. Ginley, P. Parilla, D. Schulz, National Renewable Energy Laboratory, Golden, CO S0401 Thick-film processing using techniques such as dip coating, ink spraying and electrodeposition represent promising approaches for fabricating HTS wire or tape for the Tl-oxide superconductors. The wire and tape processing for long lengths of the Tl-oxides, in contrast to the Bi-materials, is not as well advanced due primarily to a lower level of effort. The Tl-oxides, moreover, offer the potential for operation at 77K in practical magnetic fields of 3-5 T, which is supported by measurements on the irrreversibility behavior of the TI-1223 single layer compound with Pb and Sr substitution. Thick-film processing methods such as electrodeposition and ink spraying present a viable approach for producing a cost effective HTS wire or tape with technologically acceptable transport properties. This paper will review the progress in the Tl-oxide wire and tape processing for thick-film techniques. The relative merits of conventional mixed-oxide and highly reactive sub-micron precursor as prepared by electrodeposition will be discussed. The prospects and predicted cost for a "long length" thick-film process using electrodeposition and ink spraying will also be presented.
2:40 pm INVITED DEVELOPMENT OF LONG LENGTH Bi-2212 SUPERCONDUC· TORS: R. Wesche, EPFL, Centre de Recherches en Physique des Plasmas, CH-5232 Villigen PSI, Switzerland Superconducting AgNiMg and Ag/Bi-22l2 multicore wires of up to 40 m length have been fabricated by the powder-in-tube method. The optimum heat treatment conditions and the critical temperature have been found to depend on the wire diameter and the matrix material. In addition, the cooling rates are of importance for the achievable T, values. Generally, the AgNiMgsheathed wires behave like thinner Ag/Bi-2212 wires. Maximum T, values of ~92 K have been achieved for both matrix materials. These observations suggest very rapid grain-boundary assisted diffusion of oxygen through the
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4:10pm THE EFFECTS OF CARBON ON TlBlIzCa,Cu30 x PHASE FORMATION IN THE Tl(F)-Ba-Ca-Cu-O SYSTEM: Y.S. Sung, X.F. Zhang, PJ. Kostic, DJ. Miller, Materials Science Division and Science and Technology Center for Superconductivity, Argonne National Laboratory, Argonne, IL 60439
geneous current flow in these materials is discussed with the help of results for laser slicing and magnetooptic imaging experiments. Lastly, the advanced applications of each are discussed.
HUME-ROTHERY AWARD SYMPOSIUM FOR BRUNO PREDEL: Thermodynamics of Alloy Formation III: Modeling and Phase Diagram Calculation
The effects of carbon on TIBa2C~Cupx phase formation in the TI(F)B~C~C~O, system have been investigated. Samples of varying carbon content were prepared by controlling the carbon content in the B~C~Cu,oz precursor powders that were mixed with TIF and reacted to form the superconducting phase. The samples were characterized by x-ray diffraction, scanning and transmission electron microscopy, and DC magnetization. It was found that carbon induced the formation of the TI2B~C~Cu30y phase. While TlB~C~Cupx was the primary phase at low carbon contents, TIJ3a2C~CUpy became the dominant phase at high carbon contents, in spite of a 1:2:2:3 (TI:Ba:Ca:Cu) starting composition. For intermediate carbon levels, there was a strong tendency to form superlattices as a result of intergrowth between TIBa2Ca2Cu,ox and TI2B~C~Cu,oy. This work was partially supported by the U.S. Department of Energy, Basic Energy Sciences-Materials Sciences, under Contract No. W-31-109-ENG-38 and by the National Science Foundation through the Science and Technology Center for Superconductivity under Contract No. DMR 91-20000.
Sponsored by:Jt. EMPMD/SMD Alloy Phase Committee Program Organizers: Prof. VA Chang, Department of Materials Science & Engineering, University of Wisconsin, Madison, WI 53706-1595; F. Sommer, MaxPlanck-Institut fur Metallforschung, Ins!. Fur Werkstowissenschait, Seestrasse 92, 0-70174 Stuttgart, Germany Tuesday, PM February 11, 1997
Room: 330B Location: Orlando Convention Center
Session Chair: F. Sommer, Max-Planck-Institut lOr Metallforschung, Institut lOr Werkstoffwissenschait, Seestr.75, 0-70174 Stuttgart, Germany
2:00 pm INVITED RECENT ADVANCES IN THE THERMOCHEMICAL INVESTIGATION OF SELECTED AI-Ni-R (R RARE EARTH METALS) ALLOYS: G. Borzone, N. Parodi, R Ferro, Dipartimento di Chimica e Chimica Industriale, Divisione di Chimica Inorganica e Metallurgia, Universita di Genova, 1-16146 Genova, Italy
4:30 pm INVITED USE OF PARTIAL MELTING IN Tl-1223 COIL PRODUCTION: J.e. Moore, S. Fox, MJ. Naylor, S.K. Wivell, C.RM. Grovenor, University of Oxford, Dept. of Materials, Parks Road, Oxford OXI 3PH, UK
=
We have investigated a number of practical aspects in the manufacture of demonstrator coils from TI-1223 PIT tape. Coils have been fabricated using a wind and react method from 5 m tapes with an insulating MgO coating, giving engineering Je values of 2500 Acm·2. However, the performance of these sintered tapes in external magnetic field is at present poor. Previous work has suggested that only improved grain alignment can overcome this weak link problem and we have chosen to investigate a melt processing route in order to achieve this. A considerable effort has been put into correlating the effects of process variables (melt T, heating and cooling rates) on the microstructure in PIT samples. We will discuss the choice of precursor powder, composition of 1223 and heating schedule which gives the best properties in small coils.
The aluminum-based intermetallic compounds are the subject of growing interest for their combination of properties such as low density, good resistance to corrosion and heat, etc. For the AI-transition metal alloys, we may mention that the addition of rare earths to AI-rich alloys can bring about a si!;lnificant modification of macro- and microstructure resulting in improvement in strength, thermal stability, etc. Several applications of selected AI-M-R (Mtransition metal) alloys for their typical characteristics such as magnetic properties and hydrogen storage capability may be worthy of note. The knowledge of their thermodynamic properties may therefore be useful in gaining information on stable and metastable phases of these systems. To this end, we have begun a systematic study on the reactivity of the AI-R and AI-Ni-R alloys using calorimetric techniques, x-ray diffraction and microscopy analyses. The results so far obtained for selected AI-Ni-R alloy compositions will be illustrated and discussed.
4:50 pm INVITED MODIFICATION OF Bi-2223 PRECURSORS BY POWDER ENGINEERING METHODS: O.A. Shlyakhtin, A.L. Vinokurov, V. V. Ischenko, N.N. Oleinikov, Dept. of Chemistry, Moscow State University, 119899 Moscow, Russia
2:30pm THERMODYNAMIC MODELLING AND APPLICATIONS OF THE Ti-AI-N PHASE DIAGRAM: K. Zeng and R. Schmid-Fetzer, Techn. Universitaet Clausthal, AG Elektronische Materialien, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld, Germany
Reactivity of Bi-2223 precursors is rather sensitive to the microstructure of the last ones, i.e., to the size of 2212 particles and spatial distribution of minor phases. The primary way to change precursor microstructure is connected with the change of precursor synthesis technique. Relying on our studies of particle size evolution during synthesis and thermal treatment of oxide powders, we propose a method of fine and directed modification of precursor microstructure in frames of the same synthesis technique. This method is based on the mechanical and ultrasonic treatment of precursor powders at the intermediate stages of their synthesis by chemical methods.
The Ti-AI-N phase diagram has been assessed and a consistent set of thermodynamic functions has been developed. Three ternary line compounds, 1:,Ti 3AINo.56 , 1:, - Ti,AIN08" 1:3-Ti3AI,N" and the interaction parameters of the ternary solution phases uTi and ~Ti have been modelled. The experimental phase equilibria at 1573 K can be well reproduced. Inconsistencies are detected at lower temperatures, which are also related to the observed melting behavior of the ternary phases. These inconsistencies and the current approach to determine the Gibbs energies of the ternary phases are discussed in detail. Applications of the proposed thermodynamic model include the diffusion path of the TilAIN contact system at 1473 K, the reactions of AI+TiN powder mixtures in AI-matrix composites and AlffiN interface reaction.
5:10pm RECENT ADVANCES IN POLY CRYSTALLINE OXIDE SUPERCONDUCTORS: PROCESSING, PROPERTIES,AND APPLICATIONS: M. Sisodia, A. Gupta, RK. Yadava, Dept. of Metallurgical Engineering, Malaviya Regional Engineering College, Jaipur 302 017, India This talk will review some of the processing techniques adaptable to high-Te superconductor fabrication with much emphasis on desirable geometries, improved properties, microstructure control, and its associated practical problems that result in its good performance in magnetic fields. It has been observed that the improvement and optimization of Je is hindered by the formation of jospehson weak links at grain boundaries, flux creeplflux flow effects, and anisotropic properties in polycrystalline high-Te superconducting materials. Although the oxide superconductors in polycrystalline form have very poor in-field Je , it can be improved by studying the current flow. The inhomo-
3:00pm APPLICATION OF EVALUATED THERMODYNAMIC DATA FOR LIGHT METALALLOY SYSTEMS TO CASTING AND HEAT-TREATMENT PROCESSES: P. Spencer, B. Meurer, I. Hurtado, T. Buhler, S. Fries, Lehrstuhl flir Theoretische Hiittenkunde, Rheinisch-Westfalisch-Techniche Hochschule Aachen - RWTH, D-52056 Aachen The critical thermodynamic evaluation of alloys formed from the components AI, Cu, Mg, Si, Zn to produce technologically important constitution
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information will be described. Isothermal sections and isopleths relevant to phase formation in commercial alloys will be presented. The use of the evaluated data to investigate phase formation sequences and enthalpy effects during solidification under equilibrium and non-equilibrium conditions will be discussed and simulations of heat-treatment processes taking into account the influence of diffusion rates on the development of phase constitution will be described.
INTERNATIONAL SYMPOSIUM ON PROCESSING AND HANDLING OF POWDERS AND DUSTS IV: Ceramic Whisker Production, Safety and Health Issues in Powder/Dust Processing Sponsored by: Jt. EPDIMDMD SyntheSis, Control, and Analysis of Materials ProceSSing Committee, Powder Metallurgy, Reactive Metals, and Non-Metallic Materials Committees Program Organizers: Thomas P. Battle, DuPont, Edgemoor, DE 19809; Hani Henein, University of Alberta, Edmonton, AL; Gordon Irons, , 1280 Main St West, Hamilton, Ontario L8S 4L7; John Moore, Colorado School of Mines, Dept. of Met and Matis, Golden, CO 80401; Beverly Aikin, CWRU - NASA LeRC, 21000 Brookpark Road, MS 106-5, Cleveland, OH 44135; Iver Anderson, Ames Laboratory, Iowa State University, 122 Metals Development Bldg, Ames, IA 500113020; John Pusateri, Horsehead Resources Development, Monaca, PA
3:30 pm BREAK 3:45pm UNIFIED SOLUTION MODEL FOR BINARY, TERNARY AND HIGHER ORDER METALLIC, CERAMIC SYSTEMS, AQUEOUS SOLUTIONS, POLYMER BLENDS AND FOR PHASE DIAGRAM CALCULATIONS: M. Hoch, Dept. of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45221 The Hoch-Arsphofen model has been applied to binary, temary and higher order metallic, ceramic systems, aqueous solutions, polymer blends and used for phase diagram calculations. The model is an expansion of the regular solution model: it assumes that in a binary system the A-B bond properties depend on the surroundings. The model was derived from ternary and quaternary systems, and no ternary or higher order interaction parameters are needed. An equati~~ for Cp(L-s) has been developed, based on Tg , the theoretical glass transitIOn temperature, where, below the melting point, the entropy of the liquid equals that of the solid, and the Gibbs energy difference G(L-s) is a maximum. Examples of all four types of systems are presented.
Tuesday, PM February 11, 1997
Room: Salon 6 Location: Clarion Plaza Hotel
Session Chairs: Beverly Aikin, CWRU - NASA LeRC, 21000 Brookpark Road, MS 106-5, Cleveland, OH 44135; Thomas Battle, DuPont White Pigments and Mineral Products, Edge Moor Plant, Edge Moor, DE 19809
2:30pm SYNTHESIS AND PROPERTIES OF POTASSIUM HEXATITANATE WmSKERS: Zuomei lin, Lisheng Wang, Jifen Huang, Dept. of Metal Materials, Chengdu University of Science and Technology, Chengdu, P. O. Box 610065, Sichuan China
4:15pm INTERACTIONS BETWEEN INTERSTITIAL ATOMS AND VACANCIES IN METALS: Rex B. McLellan, Department of Mechanical Engineering and Materials Science, Rice University, PO Box 1892, Houston, TX 77251-1892
The optimum conditions for synthesizing potassium hexatitanate whiskers (hereinafter called as PHW) were systematically examined using fast-cooling melt method. The intermediate and final products were determined by xray diffraction analysis, SEM and differential thermal analysis. A synthetic mechanism of PHW by melt method was proposed. The physical properties of obtained PHW were measured. A ratio of whisker length to whisker diameter is preferably 50 to 200. A PVC resinous composition containing 10-30% of obtained PHW is believed to show that the mechanical properties, heat resistance and abrasion resistance are much improved. For example, the tensile strength is 1.9 times larger than that of PVC resinous matrix and thermal deforming temperature is raised from 84°C to I20°C.
The statistical mechanics of interactions between dissolved interstitial atoms and lattice vacancies in metals is discussed. Interstitial atoms occupy sites nearest-neighbor to a monovacancy creating "decorated" vacancies. The effect of such clusters on the thermodynamic properties of the solid solution and the kinetics of the migration of both lattice atoms and interstitial solutes is considered. Specific calculations will include C - austenite and systems involving hydrogen in palladium-based binary matrixes. 4:45pm ENERGETICS OF ALLOY FORMATION WITHIN STATISTICAL THERMODYNAMICS AND ELECTRON THEORY: R.N. Singh, Department of Physics, Sultan Qaboos University, PO Box 36 AI-Khod, Postal Code 123, Oman
2:55pm SYNTHESIS OF Ti(N,.xCx) WHISKERS: Niklas Ahlen, Mats lohnsson and Mats Nygren, Department of Inorganic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden
The deviations of the thermo-physical functions from the additive rule of mixing as a function of concentration, temperature and pressure is a key to the understanding of the energetics of alloy formation. Within the framework of statistical thermodynamic model, a suitable link is established between the bulk observable properties and the nature of atomic interactions in strongly and weakly correlated systems. It helps to analyze the role of enthalpic and entropic effects on alloy formation. The implications of basic interactions (i.e. electron-electron, ion-ion and electron-ion) on formation energy are also discussed from electronic theory. Pairwise interactions calculated from the first principle theory are found to have a direct correspondence to the order energy which occurs as a free parameter in various thermodynamic models.
A route for synthesis of Ti(N,.,C,) whiskers (0:0; x:O; 1), in a yield of 70-90 vol% has been established. The whiskers are:O; 1 j.lm in diameter and 10-30 j.lm in length. They are straight and have smooth surfaces. The Ti(N,.,C,) whiskers have been synthesized carbothermally via a Vapour-Liquid-Solid (VLS) growth mechanism in the temperature region 1200-1600°C. The starting materials consisted ofTiOz, C, an Ni-catalyst, and NaCl used as precursor for Cl. The synthesis of TiC whiskers are made in anAr (g) atmosphere while the Ti(N,.,C,) whiskers are prepared in N z (g) which besides preventing oxidation also acts as nitrogen source for the whiskers. The main impurities in the whisker product are minor amounts of unreacted carbon, oxygen and remnants of the Ni-catalyst. The VLS-mechanism is complex and involve formation of gaseous TiCl, species, which are transported to the catalyst. However, the overall reaction is a straightforward carbotherrnal reduction/nitridation reaction.
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3:20pm RECEPTION OF CERAMIC FIBERS FROM JOINTLY PRECIPITATED HYDROXIDES: Maximilian N. Kopylovich, Alexey K Baev, and Alexander A. Chernik. Department of Analytical Chemistry, Byelorussian State Technological University, 13a Sverdlov Street, Minsk, 220630 Republic of Belarus
plasma spray operation at Los Alamos National Laboratory using side-byside, laser-induced breakdown spectroscopy (UBS) sampling with conventional industrial hygiene techniques. We used results of the sampling data to reevaluate work practices and engineering controls associated with the plasma spray operation. As a consequence, work practices have changed, and new engineering controls and facility design changes will be implemented. These revised engineering controls include modifications to the beryllium spray chamber and design of auxiliary equipment used during routine spray chamber maintenance.
The coprecipitation method is perspective for reception of ceramic fibers. The essence of the method consists of a joint precipitation of hydroxides or salts with the subsequent branch, washing, drying and heating of a precipitate. The joint precipitation of hydroxides has a number of features. The hydroxides of metals can interact at the moment of a joint precipitation that results in occurrence of solid solutions. It was proven that in many systems containing by 2 and more hydrolyzed metal ions under certain conditions the formation of heteronuclear hydroxocomplexes occurs in solutions. The further interaction of specified hydroxopolymers causes formation of complex polynuclear structures reach the size of colloidal particles. The latters are Xray amorphous and they are a prestructure of the future material. Such prestructure can be transformed into a final crystal product at lower temperature and smaller duration of heat treatment in comparison with oxide technology accepted in manufacture of ceramic fibers at present. It will allow to expand a palette of ceramic fibers and to lower their cost price.
INTERNATIONAL SYMPOSIUM ON RHENIUM AND RHENIUM ALLOYS IV: Component Design and Fabrication of Rhenium and Its Alloys (Part I) Sponsored by: SMD Refractory Metals Committee and MDMD Powder Materials Committee Program Organizer: Dr. Boris D. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria., OH 44036 Tuesday, PM February 11, 1997
3:45pm MEASUREMENT AND MONITORING OF AIRBORNE PARTICLES - TECHNIQUES AND REGULATIONS: Martin Harper, PhD, SKC, Inc., 863 Valley View Road, Eighty Four, PA 15330
Room: 232C Location: Orlando Convention Center
Session Chairpersons: Jan-C. Carlen, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036; Dr. R.H. Tuffias, Ultramet, 12173 Montague St., Pacoima, CA 91331
Measurement of the nature and number of suspended particles in breathing air is used in health effect studies and to demonstrate compliance with government (OSHA, MSHA, EPA) regulations. The characteristics of the aerosol (e. g. fibrous, biological, metaliferous) and the requirements of the regulations govern the choice of technique. Three health-based size distributions are recognized (inhalable, thoracic, and respirable), but the definition of the fractions has varied over time. Current size separation and sampling equipment for aerosols includes impingers, elutriators, filters, impactors, cyclones, and various direct-reading instruments based on, for example, light scattering, or particle motions. Factors which influence the choice include sensitivity, accuracy, portability and ease of use, calibration requirements, cost, and government regulations. Some instruments are well matched to the healthbased size fractions, and others less so. The history and current state of regulations will be reviewed, and the types of instruments will be described.
2:00pm JOINING AND FABRICATING RHENIUM USING EXPLOSIVE METAL WORKING TECHNIQUES: Donald 1. Butler, Sr. Project Engineer, Northwest Technical Industries, Inc., 2249 Diamond Point Road, Sequim, WA98382 Rhenium has many unique and interesting properties, but some of those same properties make Rhenium difficult to fabricate and weld. Explosive metal working also has some interesting capabilities. Northwest Technical Industries, under contract from the NASA Lewis Research Center, has been successful using the explosive welding technique to join Rhenium to metals such as Tantalum, Molybdenum, TZM Molybdenum, Vanadium and C 103 Niobium. This paper will describe the explosive welding process and present the results of the work that has been completed with Rhenium. Also, this paper will describe how explosives can be used to form metal parts and explore the potential of using explosive metal forming techniques with Rhenium.
4:10pm DUST EXPLOSIBILITY PARAMETERS FOR METAL POWDERS: C. James Dahn, Safety ConSUlting Engineers, Inc., 2131 Hammond Drive, Schaumburg, IL 60173
2:20pm STATE OF THE ART FABRICATION PROCESSES FOR IRIDIUM! RHENIUM THRUST CHAMBERS: R. Tujfias, Uitramet, 12173 Montague St., Pacoima, CA 91331
The processing, manufacture and handling of powdered metals can employ widely varying process conditions which affect the potential for ignition, the explosion output and resultant collateral damages. This paper presents an overview of the factors (i.e., particle size distribution, particle cloud density, degree of turbulence, oxygen content and ambient temperature) which impact the minimum ignition energy requirement and explosive output of metallic powders. Processing conditions which strongly affect the output of an explosion, as measured in terms of maximum pressure achieved and maximum rate of pressure rise, are presented. Parameters influencing the energy requirements for ignition of an explosion will be emphasized. Dust cloud characterization under controlled conditions can be utilized to predict and, when necessary, to minimize powdered metal processing hazards.
Chemical vapor deposition (CVD) has been used to fabricate rhenium liquid rocket combustion chambers since 1977. CVD iridium was first applied to rhenium chambers for high temperature oxidation protection in 1984. Since that time, CVD iridium/rhenium (IrlRe) chambers have been successfully hot-fire tested at various facilities in both nitrogen tetroxide/monomethyl hydrazine (NTOIMMH) and oxygenlhydrogen (O,IH,) bipropellants, at mixture ratios ranging from 4 to 17, for a total of nearly 200 hours. An alternate processing method is to form the rhenium by powder metallurgy and apply the iridium by electroplating. Hot-fire testing of this processing method to date includes 43 seconds in NTOIMMH and approximately 11 hours in 021H2 at a mixture ratio of about 3, an oxidizing potential that may actually be benign to unprotected rhenium. This paper will discuss alternate processing methods and their relationship to fabricating IrlRe combustion chambers, as well as test methods for evaluating their efficacy.
4:35pm CONTROL OF BERYLLIUM POWDER AT A DOE FACILITY: Gerald C. Langner, KL. Creek, R.G. Castro, Industrial Hygiene Section, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 Although only a small percentage of the general population and work force will face exposure to airborne beryllium, the effects of this exposure to the individual can be permanent and devastating. One effect, chronic beryllium disease (CBD), a granuloma and fibrotic lung disease with latency, can be developed after inhalation exposures to beryllium. In this study, the principal investigators conducted a hazard characterization of the beryllium powder
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2:40pm DEVELOPMENT OF BONDED RHENIUMlNb-l %Zr TUBING FOR THE SP-lOO SPACE NUCLEAR REACTOR: Michael Kangilaski, Advanced Methods and Materials, 1798 Technology Drive, #251, San Jose, CA 95110; E.D. Sayre (retired); D.C. Wadekamper, T.1. Ruffo, General Electric Company, San Jose, CA The SP-lOO Space Nuclear Reactor design required a rhenium barrier between the uranium nitride nuclear fuel and the niobium alloy cladding. For higher strength and thermal performance it was deemed desirable to metallurgically bond the rhenium tube to the Nb-I %Zr tube. The bonding was achieved by brazing both ends of the rhenium and Nb-l %Zr tubes with a special braze adapter and then hot isostatically pressing (HIP) the brazed assembly. A considerable amount of effort went into developing a two stage HIP cycle for the bonding. A relatively low pressure was chosen in the first stage to assure that the weaker Nb-I %Zr tube collapsed uniformly onto the rhenium tube without any deformation occurring in the stronger rhenium tube. Avoidance of deformation in the rhenium was necessary because rhenium has low ductility at the HIP'ing temperature of 1350°C. In the second stage the temperature and pressure were increased to assure metallurgical bonding of the rhenium and Nb-I %Zr tube. 3:00pm A HISTORY OF RHENIUM IN HIGH-PERFORMANCE BIPROPELLANT ROCKET ENGINES: RH. Tuffias, RB. Kaplan, Ultramet, 12173 Montague St., Pacoima, CA 91331; M.A. Appel, Jet Propulsion Laboratory (retired), California Institute of Technology, Pasadena, CA In the late 1 970s, the Jet Propulsion Laboratory (JPL) contracted Ultramet to provide oxidation protection for a carbon composite rocket engine thrust chamber using the liquid bipropellant fluorinelhydrazine, an application for which rhenium was selected. In the late 1990s, the first rhenium thrust chamber will fly in space. This paper will discuss the period between these two milestones and those that made it possible. 3:20 pm BREAK 3:40pm DIRECTED LIGHT FABRICATION OF RHENIUM COMPONENTS: John O. Milewski, Dan 1. Thoma, Gary K. Lewis, Materials Science and Technology Division, Los Alamos National Laboratory, P.O. Box 1663, MS G770, Los Alamos, NM 87545 Directed Light Fabrication (DLF) is a direct metal deposition process that fuses powder, delivered by gas into the focal zone of a high powered laser beam to form fully dense nearnet shaped components. This is accomplished in one step without the use of molds, dies, forming, pressing, sintering or forging equipment. DLF is performed in a high purity inert environment free from the contaminants associated with conventional processing such as oxide and carbon pickup, lubricants, binding agents, cooling or cleaning agents. Applications using rhenium have historically been limited in part by its workability and cost. This study demonstrates the ability to fuse rhenium metal powder, using a DLF machine, into free standing rods and describes the associated parameter study. Microstructural comparisons between DLF deposited rhenium and commercial rhenium sheet product is performed. This rese liTh combined with existing DLF technology demonstrates the feasibility of forming complex rhenium metal shapes directly from powder.
assumed to occur, since a permanent deformation takes place This limit is referred to as the yield strength. Typical yield strengths for engineering materials such as steel are roughly 60-80% of the material's ultimate strength. For these materials, then, a linear analysis permits a design range up to 60-80% of the ultimate capability of the material. As long as the material is operated in this range, the relationship between stress and strain remains constant. Rhenium, on the other hand exhibits a "classical yield strength" that can be as low as 10% of its ultimate strength, and its stress-strain relationship varies based on its previous stress history. If a structural design is based on this classical yield strength, 90% of the capability of the material is effectively discarded. Room temperature yield strength data for CVD (chemically vapor deposited) rhenium have included values as high as 45,000 psi and as low as 8,000 psi. Rocket engine designers are currently in a quandary as to the meaning of this data and how to use it to design components. This paper will discuss some of the strength data and present alternatives. 4:20pm MATERIALS PROPERTY TEST RESULTS OF RHENIUM: Melvin L. Chazen, TRW Space & Technology Division, One Space Park, Bldg. 0 I-I 050, Redondo Beach, CA 90278 The use of rhenium as a material of construction for high performance liquid apogee/ perigee or delta-V engine applications is very beneficial as the engine performance is less limited by operating wall temperatures due to the performance. Rhenium has a very high melting point (>5700F) but does require protection from oxidation from the products of combustion. Iridium has been demonstrated as a successful high temperature protective coating (melting point >4400P). There are two methods of producing rhenium thrust chambers for high performance engines which have been successfully demonstrated which are chemical vapor deposition of iridium lined rhenium and powder metallurgy rhenium coated with iridium. An investigation was conducted to determine the material properties of both CVD and PM rhenium which was sponsored by NASA-LeRC on the SSRT program. Material property tests consisted of tensile, ultimate, modulus and low cycle fatigue at room temperature, 1500F and 2500F with a minimum number of tensile tests at 2700-3500F and high temperature creep at 3000F This paper presents these results which indicate that both CVD and FM rhenium are usable for flight engines. In addition a summary of the results of engine tests with experimenta PM rhenium will be presented. 4:40pm JOINING OF RHENIUM AND ITS ALLOYS: Sunder S. Rajan, Hughes Aircraft Company, Electron Dynamics Division, 3100 West Lomita Blvd., Torrance, CA 90509-2999 The processing parameters used to join rhenium and selected alloys containing rhenium are described. Resistance and laser welding as well as brazing processes as applied to these materials are reviewed. The metallurgical factors governing the choice of the process parameters and their influence on structural integrity are illustrated. The influence of alloy selection, use of proper filler materials and the factors governing their selection are reviewed. Experience has shown that pure rhenium, MolyRhenium and TungstenlRhenium alloys can be successfully joined by either welding or brazing processes.
4:00 pm THE IMPACT OF THE MECHANICAL PROPERTIES OF RHENIUM ON STRUCTURAL DESIGN: A.1. Sherman, A.1. Fortini, B.E. Williams, R Tuffias, Ultramet, 12173 Montague St., Pacoima, CA 91331 Pushed by extreme aerospace requirements, exotic materials with unusual properties are being pressed into service. One such material is rhenium. With a density of 21 g/cm" it is an unlikely material for structural applications, but with an ultimate strength of 20,000 psi at 2ooo°C, it is the strongest metal at this temperature and comparable in strength to carbon composites up to 2500°C. In order to design structural parts, it is necessary to be able to model their load! deflection relationship. Such analysis typically assumes that the material is elastic and conforms to Hooke's Law (stress being linearly proportional to strain). When the material becomes inelastic or plastic, failure is
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LIGHT WEIGHT ALLOYS FOR AEROSPACE APPLICATION IV: Session IV: Composites Sponsored by: SMD Non·Ferrous Metals Committee Program Organizer: Eui W. Lee, W.E. Frazier, Code 4342, Naval Air Warfare Center, Patuxent River, MD 20670; K. Jata, WUMLLM, WPAFB, OH 45433; N.J. Kim, Center for Advanced Aerospace Materials, POSTECH, Pohang, 790·784, Korea Tuesday, PM February 11, 1997
Room: 330A Location: Orlando Convention Center
Session Chairperson: N.J. Kim, Center for Advanced Aerospace Materials, POSTECH, Pohang, 790·784, Korea
2:00pm CREEP BEHAVIOR OF ALUMINUM STRENGHENING WITH VERY HIGH VOLUME FRACTIONS OF SUBMICRON ALUMINA PAR· TICLES: C. Verdon, D.C. Dunand, Department of Materials Sciences and Engineering, Room- 8-328, Massachusetts Institute of Technology, Cambridge, MA02139 High-temperature mechanical properties of dispersion strengthened cast aluminum containing 0.3 /lm alumina particles were investigated. Compression creep tests were performed on samples containing three different volume fractions of oxide dispersoids, i.e. 25%, 33% and 43%, in the temperature range between 450°C and 600°C. Both as-cast materials, whose grain size in the range of centimeter, and extruded materials, which exhibit submicron grains, were tested. In the coarse-grained materials, the deformation is controlled by dislocation creep, whereas the deformation of the fine-grained materials is controlled either by diffusional creep or by dislocation creep, depending on temperature and stress. The high values of the apparent stress exponents and of the apparent activation energy indicate a threshold stress for both creep regimes. Experimental results are discussed with respect to existing dispersion strengthening models. 2:25pm STRUCTURE AND PROPERTIES OF Si PARTICULATE REIN· FORCED ALUMINUM MATRIX COMPOSITES: S.1. Song, D.H. Kim, Dept. of Metallurgical Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-ku, Seoul, 120-749, Korea; J.S. Kim, Materials Engineering & Test Dept., Hyundai Motors Company, 700 Yangchung-dong, Jung-ku, Vlsan, 681-791, Korea To obtain a homogeneous distribution of fine Si particles in aluminum matrix, Si particulate reinforced aluminum matrix composites have been processed by using PIM method. 20-40/lm size Si particulates and Al alloy powders were mixed, degassed and extruded at 350°C for pure Al matrix composites and at 400°C for 2024 and 6061 matrix composites. Wear properties of the composites have been discussed in terms of the observed microstructural characteristics and physical properties such as tensile properties and thermal expansion coefficients. 2:50pm THE DEVELOPMENT OF LIGHT COMPOSITE MATERIALS WITH LOW COEFFICIENT OF THERMAL EXPANSION: M. Smagorins\Ci, S. Grenier, P.G. Tsantrizos, PERMA, 1744 William, Montreal, Quebec, Canada, H3J IR4 The aerospace industry uses several types of AI-based composite materials. The main criteria for their application are light weight, high strength and hardness, low CTE, and high dimensional stability (capability to keep dimensions unchanged under thermal load). Theoretical formulas were developed to calculate the CTE of binary composites, as well as the ideal diameter of the strengthening particles for composites working under stringent physical engineering conditions. The calculations which were performed permitted to select the volume fraction and the dimension of the reinforcing particles which offer the most potential. Based on these calculations, composites containing 40% of reinforcing particles were selected and produced using the Vacuum Plasma Spraying (VPS) method. The VPS net-shape forming of composites
was shown to possess distinct advantages over conventional manufacturing processes. The VPS technique can be used to fabricate advanced composites with complex shapes, high density (97-98% of the theoretical density) and, uniform particles distribution of various ceramic materials (size and composition). Plastic deformation and heat treatment result in further density improvement, which in tum significantly improves the mechanical properties of the composites. 3:15 pm MICROSTRUCTURES AND MECHANICAL PROPERTIES OF DIE CAST SiCp/AI COMPOSITES: Tae-Won Lee, Jun-Ho Seo, Chi-Hwan Lee, Department of Metallurgical Engineering, Inha University, Inchon, Korea This study was focused to investigate the effect of die casting parameters on the microstructure and mechanical properties of SiCp (10 and 20 vol%)lAI composites. Die casting was performed using the mold preheated at 130°C under the pressure of 916 kg/m3 and pouring temperature of 650-700°C. In this work, two-stage injection system, which was composed of slow and high speed injections, was used to prevent the input of air during injection. The speeds of slow and high speed injections were 0.3-0.6 and 1.4 mis, respectively. It was found that the SiC particles were homogeneously distributed in refined Al matrix. This results from the rapid mixing of Al and SiC particles during injection and the low segregation due to fast solidification rate. These microstructures provided good room-temperature mechanical properties. 3:40pm FABRICATION AND TENSILE PROPERTIES OF SiC p ,AZ91 Mg COMPOSITES BY HOT EXTRUSION: Doo-Myun Lee, Chi-Hwan Lee, Department of Metallurgical Engineering, Inha University, Inchon, Korea The tensile properties and microstructural evolution of hot-extruded SiCp/ AZ91 Mg matrix composites have been investigated as functions of extrusion parameters and SiC particulate size. Also, the effect of SiC particulates on. the grain size of matrix in the composites was studied. The AZ91 Mg alloy powders prepared by wet attrition milling from Mg machined chips were hot-pressed with and without SiC particulates, hot-extruded and then solution-treated. The microstructural observation revealed that both the composites and Mg alloy have equiaxed grains due to the dynamic recrystallization during hot extrusion. The tensile strength of the both alloys increased with increasing extrusion ratio, and the strength of the composites were higher than that ofthe Mg alloy without reinforcement. It was found that the tensile strength of the both materials decreased after solution-treatment; the decrease in tensile strength of the composites was considerably smaller than that of the Mg alloy. The grain growth of the matrix in the composites was inhibited by the introduction of the SiC particulates, resulting in the improvement in the yield strength of the composites. 4:05 pm IMPROVED HIGH CYCLE FATIGUE PROPERTIES OF TITANIUM·BASED PARTICULATES COMPOSITES: I. Hagiwara, S. Emura, Y. Kawabe, National Research Institute for Metals 1-2-1 Sengen, Tsuluba 305, Japan The titanium-based particulates composites are known to exhibit superior physical and mechanical properties compared to the unreinforced alloy. In cases where TiB or TiC is used as the reinforcing particulates, it has been reported that the fatigue fracture originates neither from the interior of particulate nor from the particulate/matrix interface, put rather from the matrix. Therefore it is suggested that the high cycle fatigue strength of the composite is strongly dependent on the matrix microstructure. In the present work, the effect of the matrix microstructure on the high cycle fatigue strength was studied for blended elemental P/M Ti-6AI-2Sn-4Zr-2Mo/lOTiB and Ti-6Al-1.7fe-O.lSi/10 TiB composites. It was found that the composites with a fine acicular a-~ two-phase microstructure showed an improved high cycle fatigue strength over those for conventionally processed composites with colony matrix microstructure.
4:30pm INFLUENCE OF FIBRE STRENGTH DISTRIBUTION ON THE FATIGUE BEHAVIOUR OF A TIB2 Is/SCS-6 COMPOSITE: J. Liu, J.G. Pursell, P. Bowen, IRC for High Performance Materials/School of Metallurgy and Materials, The University of Birmingham, Edgbaston, Birmingham B 15 2IT, UK
Session Chairperson: C.R. Abernathy, University of Florida, PO Box 116400, Gainesville, FL 32611 3:45pm EFFECT ON ION DAMAGE ON THE ELECTRICAL AND OPTICAL BEHAVIOR OF p-TYPE GaAs AND InGaP: K.N. Lee, J. Lee, J. Hong, SJ. Pearton, C.R. Abernathy, W.S. Hobson*, University of Florida, PO Box 116400, Gainesville, FL326ll; *Bell Laboratories, 600 Mountain Ave., Rrn. 7-B-207, Murray Hill, NJ 07974
The fatigue behaviour of silicon carbide fibre reinforced titanium matrix composites (TMCs) has been the subject of numerous studies. Bridging is found to he the dominant mechanism leading to the decrease in the crack growth rate us the fatigue crack grows. However, once the bridging fibres fail, the benefit of bridging will diminish. The influence of statistical fibre strength distribution on matrix cracking in fibre composites has been modeled by assuming the strength of the fibres falls in a two-parameter Weibull distribution. However, recent studies have shown that the fibre strength in TMCs is bimodal. The aim of this paper is to study the effects of fibre strength, and especially of those fibres with lower Weibull modulus. on the fatigue behaviour of a Ti,32l s/SCS-6 composite. First, single fibre tensile tests were conducted to evaluate the fibre strength distribution in both as-received uncl fatigued specimens. The fracture surfaces of the fibres showing different strengths were examined using a SEM to distinguish low-strength fibres fractographically. Fatigue tests were also conducted on single edge notched specimens. Different maximum loads and notch sizes were employed so that different fibre stresses were obtained. Acoustic emission, and direct current potential drop techniques were used to detect fibre failure and to monitor the crack growth. respectively. After the fatigue tests, the percentage of low-strength fibres in the specimens was again estimated fractographically. The influence of fibre distribution was also modeled by characterizing the fibre strengths using two two-parameter Weibull distributions. The results show that the percentage of the low-strength fibres plays an important role in determining the fatigue behaviour of the composite. Under identical loading condition, specimens with more low-strength fibres are. of cause, more likely to fail. and this has been quantified.
4:00 pm INVITED PLASMA ASSISTED PHYSICAL VAPOR DEPOSITION OF METAL NITRIDE THIN FILMS: w.J. Meng, General Motors Research and Development Center, 30500 Mound Rd., Warren, MI 48090 4:30pm THE ROLE OF ION ENERGY IN DETERMINING THE STRUCTURALAND ELECTRICAL QUALITY OF InN GROWN BY ECRAND RF-MOMBE: S.M. Donovan, J.D. Mackenzie, c.R. Abernathy, SJ. Pearton, P.C. Chow , J. Van Hovel, University of Florida, PO Box 116400, Gainesville, ' FL 32611; 'SVT Associates, 7620 Executive Dr., Eden Prairie, MN 55344 4:45pm EFFECT OF ION ENERGY ON THE OPTICAL PROPERTIES OF RARE EARTH DOPED m-NITRIDES GROWN BYRF-MOMBE: J.D. Mackenzie, S.M. Donovan, D. Salgado, L. Abbaschian, C.R. Abernathy, SJ. Pearton, U. Hommerich ' , P.c. Chow2, J. Van Hove 2, J. Zavada3 , University of Florida, PO Box 116400, Gainesville, FL 32611; 1Hampton University, 2SVT Associates, 7620 Executive Dr., Eden Prairie, MN 55344; 3US Army Research Office
MATERIALS, COATINGS AND PROCESSES FOR IMPROVED RELIABILITY OF HIGH TEMPERATURE COMPONENTS IV: Life Prediction, NDE and Repairs
LOW ENERGY BEAM PROCESSES IN ELECTRONIC MATERIALS: Shallow Junction and Low Energy Implantation
Sponsored by: SMD High Temperature Materials Committee Program Organizers: Dr. N. S. Cheruvu, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228; Dr. K. Dannemann, GE Power Generation Engineering, One River Road, Schenectady, NY 12345
Sponsored by: EMPMD Thin Films and Interfaces Committee Program Organizers: Rajiv K. Singh, University of Florida, 317 MAE, PO Box 116400, Gainesville, FL 32611-6400; O.w. Holland, Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831; Steve Pearton, University of Florida, 343 NSC, PO Box 116400, Gainesville, FL 32611-6400; Roy Clarke, Department of Applied Physics, University of Michigan, Ann Arbor, MI48109-1120; D. Kumar, University of Florida, PO Box 116400, Gainesville, FL 32611 Tuesday, PM February 11, 1997
Tuesday, PM February 11, 1997
Room: Salon 3 Location: Clarion Plaza Hotel
Session Chairperson: W. S. Walston, G E. Aircraft Engines, 1 Neumann Way, M85, Cincinnati, OH 45215
Room: 314B Location: Orlando Convention Center
2:00 pm INVITED STATUS, ISSUES AND CHALLENGES IN LIFE ASSESSMENT METHODOLOGY OF HOT SECTION COMPONENTS OF INDUSTRIAL TURBINES: K.G. Kubarych, Solar Turbines, 2200 Pacific Highway, P.O. Box 85376, San Diego, CA 92186
Session Chairpersons: O.w. Holland, Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
2:00 pm INVITED RECENT ADVANCES INTO UNDERSTANDING THE ROLE EXTENDED DEFECTS PLAY DURING TED: K. Jones, University of Florida, P.O. Box 116400, Gainesville, FL 32611
Abstract not available. 2:50pm LIFE PREDICTION BASED ON CRACK GROWTH BEHAVIOR FOR GAS TURBINE NOZZLES: N. Isobe, S. Sakurai Mechanical Engineering Research Laboratory, Hitachi Ltd., Japan; K. Kumada, Hitachi Works, Hitachi Ltd., Japan
2:30 pm INVITED DEFECT-ENGINEERED SHALLOW JUNCTIONS: Elaine G. Roth, O.w. Holland, Oak Ridge National Laboratory, Oak Ridge, TN 37831
Life prediction method for gas turbine nozzles was discussed. In gas turbine nozzles, crackings due to cyclic thermal strain generating with start-up and shut-down of turbines limit the life of components. This thermal strain is usually compression and holded during steady operation time. Therefore, it will be necessary to consider the effect of compressive creep or relaxation to the evaluation of crack growth behavior in nozzles. We conducted crack growth tests at 900D C using a strain wave form including compressive strain hold. Test results showed that crack growth rate in compressive strain hold tests
3:00 pm INVITED LOW ENERGY IMPLANTATION: A. Agarwal, Bell Laboratories, 600 Mountain Ave, Murray Hills, NJ 07974 3:30 pm BREAK
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were faster than that in no strain hold tests. A fracture mechanics approach was carried out to evaluate this compression hold effects. By using creep Jintegral, a good correlation for crack growth data was obtained. A crack growth analysis considering stress gradient in the component was also carried out and we discussed about its accuracy using inspection data for 25MW class gas turbine nozzles.
4:30pm EFFECTS OF SUBSTRATE CURVATURE AND ROUGHNESS ON RESIDUAL STRESSES IN OXIDE FILMS: 1.K. Wright, R.L. Williamson, Idaho National Engineering Laboratory, P.O. Box 1625, Idaho Falls, ID 834152218 Finite element simulations are used to examine residual thermal stresses and strains in protective AIP3 scales on Fe 3Al specimens, both during cooling from oxide formation temperatures and during subsequent thermal cycling. Geometrically, the simulations focus on regions of local curvature, either due to corners or substrate surface roughness. A variety of substrate corner radii and film thicknesses are considered. The effects of substrate material behavior are investigated by not only considering the actual elastic-plastic response of the aluminide substrate, but also the limiting cases of purely elastic and perfectly plastic material behavior. When plasticity is permitted, the substrate is able to deform to accommodate stresses at the corner, and the film is in tension along the outside surface and compression near the interface. These tensile stresses are of concern for coating integrity, since corners are observed experimentally to be sites of oxide cracks and spallation.
3:10pm RELIABLE TBC'S FOR THE INDUSTRIAL GAS TURBINE DESIGN: W Beele, W. Stamm, SIEMENS/KWU, Wiesenstr. 35, D-45473 Mulheiml Ruhr, Germany This paper reviews the TBC-design as meanwhile established in aircraft technology and highlights the reasons why a reliable industrial gas turbine TBCdesign has to differ in various material system properties. The development steps for Industrial Gas Turbine-(IGT-)TBC-systems will be presented as well as fundamental research activities like cyclic oxidation tests with enlarged high temperature aging periods, and first design results will be given in some real components examples. The actual use of TBC's in existing gas turbine designs is characterized by: TBC's were developed and approved by SIEMENS in a large test program including several types of cyclic and static high temperature oxidation and corrosion testing, the investigation of the mechanical properties for modeling issues and the review of the P&W-development steps and results for the aircraft application.
4:50pm REPAIR WELDING OF 1.0CR-IMO-0.25V BAINITIC TURBINE ROTOR: YoungKun Oh, Kia Motors Corporation, Production Engineering RID Department, J.E. Indacochea, GwangSoo Kim
3:30 pm BREAK
Weld repair of ASTM A-470 class 8 high pressure steam turbine rotor steel has been performed to extend the service life of older fossil units. Multipass SAW, MIG and TIG welding have been employed. Microhardness of the base metal was VHN 253, however it dropped to VHN 227 at the heat affected zone close to unaffected base metal for SAW. This area of hardness drop is called "softening zone" and has a width of 0.5-0.6mm. During creep rupture test, failure occurred around the softening zone and rupture time was 772.4hr at 19ksi and 593°C. At ruptured area, spherical types of coarsened carbides, which were revealed molybdenum rich M6C were observed. Based on creep rupture life, SAW and/or high heat input TIG process provide the best creep rupture life and it could operate about 8-10 years.
3:50pm NON-DESTRUCTIVE EVALUATION OF HIGH TEMPERATURE OXIDATION DAMAGE USING ELECTROCHEMICAL TECHNIQUES: D.C. Tamboli, A.K. Rawat, V. Desai, Mechanical Materials and Aerospace Engineering Department, University of Central Rorida, Orlando, FL32816 Electrochemical techniques have been widely used as life prediction tools in corroding structures and coatings for aqueous corrosion. However, there has not been much attention given to the applicability of these techniques in assessing high temperature oxidation damage. In the high temperature oxidation, the metallic substrate is covered with an oxide film which has semiconducting properties. Electrochemical techniques such as electrochemical polarization and electrochemical impedance spectroscopy reveal vital information about the electronic transport properties of this oxide film by monitoring the response of the system to applied D. C. and A. C. potentials respectively. The protective properties of an oxide are largely dependent on the electronic and ionic transport through the oxide layer. In the ex -situ studies, the oxidized specimens are immersed in a highly reversible redox electrolyte. The parameters such as polarization resistance, open circuit potential changes and the oxide band gap potential obtained using these techniques showed good qualitative corroboration with the observed oxidation damage in the alloys studied.
5:10pm MATHEMATICAL MODELLING OF ELECTRON BEAM EVAPORATION: Adam Powell, Gerardo Trapaga, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; Paul Minson, Intel Corporation, Rio Rancho, NM 87114 Mathematical models of vapor and melt pool transport phenomena in electron beam evaporation are used to design an optimal beam scanning pattern to achieve a desired evaporant flux distribution at the substrate. The vapor transport model uses the Direct Simulation Monte Carlo method to calculate evaporant flux distribution at the substrate from the temperature distribution at the source, the activities of source species, background gases and system geometry. The source temperature distribution is adjusted manually in order to produce the desired flux distribution at the substrate. The melt pool model then calculates the heat flux distribution which the scanning electron beam must impart to the molten source surface in order to produce the desired temperature distribution, accounting for thermal losses to radiation and evaporation. Finally, a surface heat transfer model is used to calculate minimum beam local heating by the scanning beam.
4:10pm PREDICTIONS OF MICROSTRUCTURE CHANGES IN COATED TURBINE BLADES DURING SERVICE: X. Qiao, J.E. Morral, Department of Metallurgy and Materials Engineering, University of Connecticut, Storrs, CT 06269-3136 With mCTRA software, it is possible to predict microstructural changes in coated turbine blades during service. In the present work, this technique is illustrated by calculating the microstructures that will form between a nickel base 1+1' alloy and MCrALY type ~+1 alloys. It is shown that a number of different microstructures can form initially, depending on the coating composition. As the average composition of the coating varies during service, the microstructure may change several times. These variations can be illustrated on an "Interdiffusion Microstructure Map."
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3:00pm IN SITU STUDIES OF AQUEOUS CORROSION OF TARGET AND STRUCTURAL MATERIALS IN WATER IRRADIATED BY AN 800 MEV PROTON BEAM: D.P. Butt, G.S. Kanner, L.L. Daemen, R.S. Lillard, Los Alamos National Laboratory, Los Alamos, NM 87545
MATERIALS FOR SPALLATION NEUTRON SOURCES III: Corrosion Sponsored by: Jt. SMD/MSD Nuclear Materials Committee Program Organizers: M.S. Wechsler, North Carolina State University, L.K. Mansur, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6376; C.L. Snead, Brookhaven National Laboratory, Upton, NY 11973-5000; W.F. Sommer, Los Alamos National Laboratory, Los Alamos, NM 87545
Tuesday, PM February 11, 1997
Radiation enhanced, aqueous corrosion of solid spallation-neutron-source targets, such as tungsten, or target cladding or structural materials, such as superalloys and stainless steels, is a significant concern in accelerator-driven transmutation technologies. In this paper we describe methods for control and in situ monitoring of corrosion in accelerator cooling water loops. Using electrochemical impedance spectroscopy, we have measured the corrosion rates of aluminum 6061, copper, Inconel 718, and 304L stainless steel in the flow loop of a water target irradiated by a milliamp, 800 MeV proton beam. We also briefly describe our second generation experiments, scheduled to begin in early 1997. In these experiments we will measure the corrosion rates of tungsten, tantalum, Inconel 718, aluminum 5053, and 316L, 304L, and HT-9 stainless steel. We also discuss our laser diagnostic techniques for directly observing the production of corrosive radiolysis products as well as corrosion products near the surface of target materials.
Room: Salon 4 Location: Clarion Plaza Hotel
Session Chairperson: L. K. Mansur, Oak Ridge National Laboratory
2:00pm LIQUID METAL COMPATIBILITY OF STRUCTURAL MATERIALS WITH LIQUID LEAD-BISMUTH AND MERCURY: l.R. Weeks, Brookhaven National Laboratory, Upton, NY 11973-5000
3:30 pm BREAK
Both liquid mercury and liquid lead-bismuth eutectic have been proposed as possible target materials for spallation neutron sources. During the 1950's and 1960's a substantial program existed at Brookhaven National Laboratory as part of the Liquid Metal Fuel Reactor program on the compatibility of bismuth, lead, and their alloys with structural materials. Subsequently, compatibility investigations of mercury with structural materials were performed in support of the development of Rankine-cycle mercury turbines for nuclear applications. The present talk will review our understanding of the corrosion/mass-transfer reactions of structural materials with these liquidmetal coolants. Topics to be discussed include the basic solubility relationships of iron, chromium, nickel, and refractory metals in these liquid metals, the results of inhibition studies, the role of oxygen on the corrosion processes, and specialized topics such as cavitation corrosion and liquid-metal embrittlement. Emphasis will be placed on utilizing the understanding gained in this earlier work in the development of heavy-liquid-metal targets for spallation neutron sources.
3:50pm STATIC CORROSION OF MARTENSITEIFERRITE AND AUSTENITIC STEELS IN MERCURY AT 300T: Y. Dai, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland Mercury corrosion will be one of the critical problems for a spallation neutron source using Hg as target material. Preliminary results of static corrosion tests on 316L austenitic steel and on MANET and F82H martensiticlferritic steels will be presented. Smooth and notched Coring-shaped specimens were prestressed before putting them into Hg. The tests were performed at 300"C and interrupted after different durations. After cooling down to room temperature, the change of morphology of specimen surfaces was examined. For 316L specimens after 160 hrs of corrosion, Hg covered all surfaces. However, for F82H and MANET, there was almost no Hg on surfaces after 500 hrs, but surfaces were covered with Hg after an additional 500 hrs. F82H had the thickest oxide layer (about 0.5 11m thick after 1000 hours), MANET was next, and 316L had the thinnest oxide layer. The mechanisms for wetting and oxidation will be discussed.
2:30pm MODELING AND OPTICAL STUDIES OF THE WATER-METAL INTERFACE IN SPALLATION NEUTRON SOURCE TARGETS: L.L. Daemen, GJ. Kanner, R.S. Lillard, D.P. Butt, T.O. Brun, w.F. Sommer, Los Alamos National Laboratory, Los Alamos, NM 87545
4:20pm SURFACE OXIDES AND THE BEHAVIOR OF ALUMINUM COMPONENTS IN THE APT TARGETIBLANKET SYSTEM: M.R. Louthan, Jr., Savannah River Technology Center, Aiken, SC 29808
In spallation neutron sources neutrons are produced when a beam of highenergy particles (e.g., 1 GeV protons) collides with a (water-cooled) heavy metal target such as tungsten. The resulting spallation reactions produce a complex radiation environment (which differs from typical conditions at fission and fusion reactors) leading to the radiolysis of water molecules. Most water radiolysis products are short-lived but extremely reactive. When formed in the vicinity of the target surface they can react with metal atoms, thereby contributing to target corrosion. We will describe the results of calculations and experiments performed at Los Alamos to determine the impact on target corrosion of water radiolysis in the spallation radiation environment. Our computational methodology relies on the use of the Los Alamos radiation transport code, LAHET, to determine the radiation environment, and theAEA code, FACSIMILE, to model reaction-diffusion processes. The experiments make use of ultra-fast Raman spectroscopic techniques. Laser Raman spectroscopy enables us to identify the chemical species formed in water and at a metal surface during irradiation, as well as to observe the growth of corrosion products at the water-metal interface.
The mechanical properties of the aluminum alloys in the accelerator production of tritium (APT) targetlblanket system are sensitive to exposure and processing history. Several of the APT applications require exposure to flowing, hot water under heat transfer conditions. The thermal conductivity of the protective film is low and limits the temperature drop across the aluminum. This reduction in heat transfer will raise metal-oxide interface temperature and playa major role in the corrosion processes. Under heat transfer conditions, the oxide-metal interface temperature will increase both oxide thicknesses and service temperatures for aluminum. Interrelationships among service, oxide development and water chemistry are similar to those for reactor service and this paper relates anticipated performance in the APT system to reactor experience.
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breakdown of the silicate network structure on the addition of metal oxides to the melts. The predicted values are in good agreement with the experimental values over the whole temperature and composition range.
MATERIALS PROCESSING FUNDAMENTALS SYMPOSIUM II
3:15pm COPPER DEOXIDIZATION BY BUBBLING HYDROGENINITRO· GEN MIXTURES THROUGH THE MELT: Claudio Parra De Lazzari, Jose Deodoro Trani Capocchi, Department of Metallurgical and Materials Engineering, Escola Politecnica de Universidade de Sao Paulo, Sao Paulo SP - Brazil
Sponsored by: Jt. EPD/MDMD Synthesis, Control, and Analysis in Materials Processing Committee, EPD Process Fundamentals, Aqueous Processing, Copper, Nickel·Cobalt, Pyrometallurgy, Lead, Zinc, Tin Committees, MSD Thermodynamic & Phase Equilibria Committee Program Organizers: R.G. Reddy, Department of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL 35487-0202; S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; P.R. Taylor, Department of Metallurgical and Mining Eng., University of Idaho, Moscow, ID 83743 Tuesday, PM February 11, 1997
The determination of the governing step of the deoxidization rate and the effects of the hydrogen content of the mixtures (C), the diameter of the delivery orifice (q» and the Reynolds number of the orifice (Ro,) on the productAy keg was investigated. ~ is the total surface area of the interface between the bubbles and the melt keg, is the mass transfer coefficient in the gas phase. The design of the experiments was based on a two levels statistic fractionated factorial planning Oxygen in the melt was measured as a function of time. In the prevailing experimental conditions it was found that the governing step of the deoxidization rate was the transport of hydrogen in the gaseous phase and that Ay kejg increases with C, q> and Reo.
Room: 231B Location: Orlando Convention Center
Session Chairpersons: R.G. Bautista, Mackay School of Mines, University of Nevada, Reno, NV 89557: G. Ramadorai, EnMet Associates Inc., 11225 E. Quick Draw Place, Tucson, AZ. 85749
2:00pm PRODUCTION OF THERMAL SPRAY·QUALITY METAL AND AL· LOY POWDERS BY PLASMA PROCESSING: P.V. Ananthapadmanabhan, K.P. Sreekumar, N. Venkatramani, Laser & Plasma Technology Division, Bhabha Atomic Research Centre, Bombay-400 085, India; Patrick R. Taylor, Department of Mining & Metallurgical Engineering, University of Idaho, Moscow, ill 83844
3:40 pm BREAK 3:50pm CHEMICAL WEAR OF REFRACTORIES IN THE SLAG LINE OF VOD LADLES FOR THE PRODUCTION OF STAINLESS STEELS: B. Blanpain, P. Wollants, Department of Metallurgy and Materials Engineering, K.U. Leuven, de Croylaan 2, B-3001 Leuven, Belgium, and B. Hallemans, ALZ, Genk-Zuid zone 6A, B-3600 Genk, Belgium
Feedstock powders of metals, alloys and ceramics for thermal spray applications have to meet several specifications. Particle shape, size and distribution, powder flow characteristics and density are the important factors that need to be controlled, in order to ensure high spray efficiency and better coating properties. Thermal plasma technology can be effectively utilized to produce metal, alloy and ceramic powders for spray applications. The present paper describes plasma spheroidisation of commercially available aluminum powder and nickel-aluminum powder blend in a plasma reactor. Results show that the processed powder particles bear spherical morphology with excellent flow characteristics, ideal for thermal spray applications.
The slag line in vacuum oxygen decarburization (VOD) ladles is a severe environment for refractory materials during the refining of stainless, steels. Magnesia-chrome bricks are currently the refractory materials of choice for this application. The actual performance of a fixed quality of magnesia-chrome bricks is however largely dependent on the conditions during the VOD process cycle. This presentation addresses the aspects of chemical interaction between the slag phase and the magnesia-chrome refractory materials. Asdelivered and postmortem bricks have been analyzed by optical microscopy, x-ray diffraction and scanning electron microscopy. Different phenomena were observed such as slag penetration and oxide reduction. These experimental observations are the basis for a modeling of the slag/magnesia-chrome reaction. The aim is to investigate alternate, viable VOD processing routes which are less demanding on the refractory materials.
2:25pm NON·ELECTROLYTIC DEPOSITION OF SILVER ON TO TUNGSTEN·POWDER PARTICLES: Jae-Ho Lee, Hong lk University, Department of Metallurgy and Materials Engineering, 721 Sangsu dong, Mapo-gu, Seoul 121-791, Korea; G .P. Martins, Colorado School of Mines, Department of Metallurgical and Materials Engineering, Golden, CO 80401
4:15pm PHASE EQUILmRlA IN THE OXIDE-SATURATED Ca·Mg-O SYS· TEM: Xiaoping Xu, Mark E. Schlesinger, Department of Metallurgical Engineering, University of Missouri-Rolla, 1870 Miner Circle, Rolla, MO 654090340
For some electronic applications where a dispersed electrically-conductive particulate phase is employed, the conductivity of the surface (or near-surface region) of the particles provides for the primary mechanism which determines its electrical conductivity. Particles of a less expensive material, which may have desirable thermal-expansion properties, when coated with silver offer a means of also obtaining desirable electrical properties at a lower cost. The research conducted was focused primarily on the development of silvercoated tungsten particles for thick-film polymeric conductors. The ammoniacal electrolyte was formulated from silver-nitrate, glycine inhibitor and formaldehyde reductant. The reduction, and subsequent deposition, of silver occurred selectively on the surface of the tungsten particles. Coated particles were assessed by SEM imaging. The thickness of the silver coating was estimated to be approximately lOOnm on the basis of a mass account and the coating being uniform. The electrical conductivity of a silver-coated tungsten-powder pellet was found to be similar to that of a silver-powder pellet, of identical geometry.
Recent research results have claimed that previously accepted Gibbs energies of formation of CaO and MgO are in error, and that MgO is actually more stable than CaO at lower temperatures. The potential impact of this on the existing thermodynamic database and on calculations using t-.Go, values for these oxides is considerable. However, the newly calculated values remain controversial. Equilibration of pure CaO and MgO with a metal phase at temperatures between 1100' and 1200'C allows the new t-.Go, values to be "tested," using a previously derived thermodynamic model for liquid CaMg alloys to calculate activities in the metal phase. The fit between actual and predicted alloy compositions determines the likelihood that the new thermodynamic values are valid.
2:50pm VISCOSITY MODELING OF TERNARY ALUMINO SILICATE MELTS: Z. Zhang, R.G. Reddy, The Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487-0202
4:40pm REDUCTION OF MoO PELLETS BY CARBON-SATURATED LIQUID IRON: Jose Roberto de Oliveira, Marcelo Breda Mourdo, Paulo dos Santos Assis and Jorge Alberto Soares Tenorio, Dept. of Metallurgical and Materials Engineering, University of Sao Paulo, 05508-900, Sao Paulo, Brazil
Viscosity of CaO-aluminosilicate ternary melts were estimated using a structure based modeL The model considers depolymerization effects and related
The goal of this study was to investigate the reduction of MnO pellets by carbon saturated liquid iron. The effects of the initial Mn and Si content in the
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bath were explored. The tests were performed in laboratory apparatus, where MnO pellets reacted with a saturated liquid iron bath. The reduction time was taken by measurement of the CO pressure variation with the time. The results showed the effect of initial Mn, C and Si content in the bath. The Kinetics of MnO reduction increases with the decrease in the initial MnO content in the bath. Si in the bath increases the reduction rate of the MnO pellets.
Laboratory, Oak Ridge, TN 37831 The mechanical properties of ceramic matrix composites (CMCs) can be controlled by tailoring the fiber/matrix interface, especially the type of interfacial materials and their thickness. A new NicalonlSiC composite with SiC as an interfacial coating processed by a forced-flow chemical vapor infiltration (FCYI) method at the Oak Ridge National Laboratory demonstrates improved high-temperature oxidation resistance than that with a carbon interfacial coating. However, it is difficult to differentiate the SiC interface from the matrix using scanning electron micrographs, because of nearly identical microstructures and similar chemical compositions of the fiber, the matrix, and the interfacial coating. In this paper, the line-scan chemical analysis technique in scanning electron microscopy (SEM) is used to investigate the SiC interfacial coating. As-received and oxidized specimens are studied. The existence of elements, such as Si, C, 0, and Cl, and their distributions along the fiber/ matrix interface, are detected. The profile of interface chemical composition can be used to identify interface structure as well as thickness. The effect of interface composition on mechanical properties is also studied.
5:05pm PHYSICAL CHEMISTRY OF COPPER AND MANGANESE CO·RE· COVERYFROM COPPER AND MANGANESE ORES AND BY·PROD· UCTS: Yladimir Mindin, AFP, 111 East Shore Rd., Manhasset, NY 11030; Natela Kiknadze, Georgian Technical University, Kostava Str., 69, Tbilisi, Georgian Republic Proposed by outstanding electrochemist and electrometallurgist Raphael Agladze [1911-1989] process of copper and manganese co-electrowinning was enhanced to the pre-electrowinnning stages: (a) low temperature co-leaching of copper and manganese containing materials, and (b) to high- temperature co-roasting of the same materials, with consecutive leaching. The both (a) and (b) approaches gave very impressive results in depth of recovery and other parameters. The report presents results of experimental investigations of the processes mentioned above as well as results of thermodynamic investigations of co-roasting process, and co-leaching process computer modeling. Some special topics such as control of co-leaching process are also discussed. The processes novelty was recognized by four former USSR patents.
3:00pm CRACK NUCLEATION ON ELASTIC POLYCRYSTAL SURFACE IN CORROSIVE ENVIRONMENT: Z. Suo, H. Yu, Mechanical and Environmental Engineering Department, Materials Department, University of California, Santa Barbara, CA 93106 This paper analyzes a process of crack nucleation on the surface of a ceramic subject to a stress parallel to the surface, in an environment where the ceramic evaporates slowly and deforms elastically. Both grain boundary tension and elastic stress concentration cause the surface to groove along its intersections with the grain boundaries. Two behaviors are identified. If the applied stress is small, the grooves approach an invariant shape, and the ceramic erodes by gross mass loss. If the applied stress is large, the grooves sharpen into crack fronts, and the ceramic breaks by decohesion. The models relate crack nucleation threshold and time to the applied stress, surface and grain boundary tensions, chemical free energy, grain size, and kinetic parameters. Surface self-diffusion is also included in the analysis.
NON-LINEAR FRACTURE PROCESSES IN BRITTLE CRYSTALLINE SOLIDS III: Ceramic Systems Sponsored by: ASM·MSD Flow and Fracture and SMD Mechanical Metallurgy Committees Program Organizer: J.K. Shang, Department of Materials Science and Engineering, University of Illinois, Urbana, IL 61801; P.K. Liaw, Department of Materials Science and Engineering, University oiTennessee, Knoxville, TN 37996-2200; S.x. Mao, Department of Mechanical Engineering, University of Calgary, Calgary, Alberta, Canada, T2N 1N4 Tuesday, PM February 11, 1997
3:30 pm BREAK
Room: 232B Location: Orlando Convention Center
4:00pm ROLE OF GRAIN BOUNDARY PHASE DURING HIGH·TEMPERA· TURE FATIGUE· CRACK GROWTH IN CERAMICS: 1. K. Shang, D. Yao, C. Huang, Department of Materials Science and Engineering, University of Illinois, Urbana, IL 6180 I
Session Chairperson: S.X. Mao, Department of Mechanical Engineering, University of Calgary, Calgary, Alberta, Canada, T2N 1N4
Role of grain boundary phase on high-temperature fatigue-crack growth were examined in a TiB/SiC composite and polycrystalline aluminas of different purities at 800 - lloo°C. The low-purity alumina and the composite contained a continuous film of glassy phase on the grain boundary while the high-purity aluminas contained either little or no continuous grain boundary phase. In the low-purity alumina and the composite, fatigue crack growth rate increased drastically as the cyclic frequency was decreased. The cyclic crack growth rate was slower that the creep crack growth rate at the same maximum stress intensity. In contrast, fatigue crack growth in the high-purity alumina was relatively insensitive to cyclic frequency and the fatigue crack growth rate was faster than the creep crack growth rate for the same maximum stress intensity. The difference in the fatigue crack growth behavior is explained in terms of the different fatigue crack growth mechanisms in these ceramics.
2:00 pm INVITED CREEP DEFORMATION AND RUPTURE OF Alz0 3 UNDER STATIC AND CYCLIC LOADING: Darrell Socie, Department of Mechanical Engineering, University of Illinois, Urbana, IL 61801 Results of the tension and torsion tests on a commercial grade of vitreous bonded, 99.8% AlP3' show that creep deformation is enhanced significantly under shear stress. Microstructural observations show that extensive grain boundary sliding occurs in the torsion specimens and gives rise to a large initial creep deformation. Evidence of cavity formation is found throughout the specimen. Little evidence of grain boundary sliding or cavitation was found in the tensile specimen even though the tensile stress was four times larger. The combined action of one tensile stress s, and one compressive stress, -0"3' doubles the grain boundary shear stresses to 21:. This results in more grain boundary sliding and early cavity formation under shear loading. In addition the compressive stress will cause a wedging action on individual grains that will result in a grain facet stress of O"n' This stress will be added to the tensile stress, 0", ' to enhance cavity coalescence and microcrack growth.
4:30pm THE MECHANICAL BEHAVIOR OF CONTINUOUS FIBER REIN· FORCED CERAMIC COMPOSITES (CFCCs): N. Miriyala, P. K. Liaw, C. J. McHargue, The University of Tennessee, Knoxville, TN 37996; L. L. Snead, Oak Ridge National Laboratory, Oak Ridge, TN 37831
2:30pm AN INVESTIGATION OF FIBER/MATRIX INTERFACE OF A NICALON FIBER REINFORCED SILICON CARBIDE COMPOSITE WITH A SILICON CARBIDE INTERFACIAL COATING: Wei Zhao, Peter K. Liaw, David C. Joy, Dept. of Materials Sciences and Engineering, The University ofTennessee, Knoxville, TN 37996-2200; Elizabeth R. Kupp, David P. Stinton, The Metals and Ceramics Division, Oak Ridge National
The mechanical behavior of two Nicalon fabric reinforced ceramic matrix composites, with alumina and silicon carbide as the matrix materials, respectively, were investigated. Four point-bend tests were conducted at ambient and elevated temperatures to study the monotonic and cyclic fatigue behavior. The stress-strain curves were non-linear for both composites, at ambient as well as elevated temperatures. During cyclic loading, the modulus of the
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composite was monitored to serve as a measure of the loss in load bearing capacity of the composites due to cyclic fatigue loading. Progressive damage in the composites was monitored by optical and electron microscopy techniques. The differences in the composite monotonic and cyclic fatigue behavior, depending on the orientation of the fabric plies to the loading direction, and the micromechanisms responsible for the differences, will be the focus of the paper.
3:30pm IMPROVEMENT OF MAGNETIC PROPERTIES OF NANOCOMPOSITE NdFeB MELT SPUN RIBBONS BY ELEMENT SUBSTITUTION: W. C. Chang, S. H. Wu, Department of Physics, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Taiwan, China; B.M. Ma, C. O. Bounds, Rhone-Poulenc, Rhone-Poulenc Rare Earths and Gallium, CN 7500, Cranbury, NJ 08512 The magnetic properties of the nanocomposite NdFeB melt spun ribbons are strongly determined by the remanence, coercivity and the squareness of its demagnetization curve. In this paper, three approaches in improving the magnetic properties of oc-FEINdzFe I4B type nanocomposite melt spun ribbons will be addressed: (I) the effect of Co substitution for Fe on the remanence enhancement (2) the effect of La substitution for Nd on the improvement of remanence and the squareness of the demagnetization curve and (3) the effect of Cr substitution for Fe on the enhancement of the coercivity and the squareness of the demagnetization curve.
RARE EARTHS, SCIENCE, TECHNOLOGY AND APPLICATIONS IV: Melts and Metals Reduction Processing Sponsored by: LMD Reactive Metals Committee Program Organizers: R.G. Bautista, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno, Reno, NV 89557; C.O. Bounds, RhonePolenc Rare Earths and Gallium, CN 7500, Prospect Plains Rd., Cranbury, NJ 08512; Timothy W. Ellis, Lulicke and Soffa Industries, Inc., 2101 Blair Mill Rd., Willow Grove, PA 19090; Barry T. Kilbourn, Molycorp, Inc., Executive 46 Office Center, 710 Route 46 East, Fairfield, NJ 07004 Tuesday, PM February 11, 1997
4:00pm THE MAGNETIC PROPERTIES AND CRYSTALLIZATION PHENOMENA OF MELT EXTRACTED Nd,.sFe.o.l_XBX (X=6 through 11) FILAMENTS: Q. Chen, B. M. Ma, C.O. Bounds, Rhone-Poulenc, Rare Earths and Gallium, CN 7500, New Jersey
Room: Salon 8 Location: Clarion Plaza Hotel
Recently, Nd-lean and/or boron-rich melt spun materials have attracted attention as potential materials for bonded magnet applications. Since the alloys can deviate significantly from the stoichiometric Nd2Fe l4B composition, additional phases are usually present in the products. The size and volume fraction of these phases play important roles in determining the strength of exchange coupling interaction between phases and, consequently, the magnetic properties obtained. It is of interest to know how the Nd and/or boron contents impact the crystallization behavior and the magnetic properties of these materials. An alloy series of N<4.8Fe90.z.,B" where x=6 through II was prepared by a newly developed melt extraction technique at various wheel speeds.
Session Chairpersons: Renato G. Bautista, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno, Reno, NV 89557; K. OsseoAsare, Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802
2:00pm ANODE EFFECT IN NEODYMIUM OXIDE ELECTROLYSIS: Rudolf Keller, Kirk T. Larimer, EMEC Consultants 4221 Roundtop Road, Export, PA 15632 In the electrolysis of neodymium oxide from a molten fluoride electrolyte, anode effects may occur at the carbon anodes, interfering with smooth cell operation. In laboratory experiments, we attempted to circumvent this problem selecting electrolytes with a high oxide concentration, possibly at relatively low rare earth content, but cathodic deposition was not satisfactory. A regime at higher cell voltage was discovered to yield good cell performance, but evolution of considerable amounts of fluorocarbon compounds suggested that a reactive treatment of the off-gases would be necessary for environmental acceptability. Subsequent experimentation at low cell voltage revealed conditions for satisfactory operation without occurrence of anode effects and without any formation of CF4 and CzF6•
RECENT ADVANCES IN FRACTURE IV: Mechanisms of Ductile Fracture: A Symposium Dedicated to Professor Emeritus Frank A. McClintock Sponsored by: MSD Flow and Fracture, SMD Mechanical Metallurgy Committees Program Organizers: Dr. R. K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; Dr. A. B. Geltmacher, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375; Dr. K. Sadananda, Naval Research Laboratory, Code 6323, 4555 Overlook Drive SW, Washington D. C. 20375; Dr. P. Matic, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375
2:30pm THERMODYNAMIC MODELING OF CALCIOTHERMIC REDUCTION OF NdF" P.T. Velu, R.G. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487
Tuesday, PM February 11, 1997
Room: 314A Location: Orlando Convention Center
Session Chairpersons: Professor John W. Hancock, Department of Mechanical Engineering, University of Glasgow, Scotland G12 800, UK; Dr. Peter Matic, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375
Production of neodymium metal by reduction of NdF, with calcium in the presence of calcium chloride is studied. The thermodynamic calculations of the reduction process was carried out using method of minimization of Gibbs energy. Yield of neodymium metal was calculated as a function of temperature and salt composition. Nd increased with increase in temperature and also increase in CaCI 2• Impurity content of the alloy decreased with increase in CaCl2 The calculated data is an excellent agreement with the large scale experimental data.
2:00 pm INVITED MODELING OF DUCTILE FRACTURE: Alan Needleman, Division of Engineering, Brown University, Providence, RI 02912 Analyses offracture are discussed where the initial-boundary value problem formulation allows for the possibility of a complete loss of stress carrying capacity, with the associated creation of new free surface. Hence, fracture arises as a natural outcome of the deformation process without any ad hoc failure criterion being employed. The failure mechanisms modeled are plastic void growth and coalescence, and cleavage cracking (so that the ductilebrittle transition can be analyzed). The role of porosity induced weakening in precipitating shear band failures will be illustrated. However, the main emphasis will be on recent predictions of crack growth, including ductile-brittle transitions and three dimensional effects such as shear-lips.
3:00 pm BREAK
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show that size effect and dispersion can be successfully modeled using both approaches. The fully coupled approach, although more time consuming, is thought to be the most promising since: (1) it is based on fewer assumptions, (2) it can be applied to any geometry (e.g. cracked components); in particular it gives much better results on smooth tensile specimens, (3) it can model the interaction between neighboring heterogeneities clusters.
2:25 pm INVITED NON-LOCAL EFFECTS IN DUCTILE FRACTURE PREDICTIONS: Viggo Tvergaard, Department of Solid Mechanics, Technical University of Denmark, DK-2800 Lyngby, Denmark Continuum studies of ductile fracture have been based on local constitutive relations, which do not represent a material length scale. The resulting numerical predictions show inherent mesh sensitivity, since the softening material behaviour near final failure will tend to give localized damage in regions as narrow as possible within the mesh resolution. Nonlocal constitutive relations, with the delocalization related to the damage mechanism, have been proposed for ductile fracture where damage involves the nucleation and growth of voids to coalescence. The effect of using this nonlocal material model will be illustrated by a number of analyses, including studies of shear band failure, ductile matrix failure in metal matrix composites, and failure involving two size - scales of voids. Based on recent comparisons with cell - model predictions of localization in a void - sheet the relevant material length scale for a ductile fracture model are discussed.
3:15 pm BREAK 3:25 pm INVITED MICROSTRUCTURE MECHANICS DESCRIPTION OF DUCTILE FRACTURING IN POLYCRYSTALS: Ronald W. Armstrong, C.C. Chen, G.R. Irwin, M.E. Natishan, FJ. Zerilli', XJ. Zhang, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742; 'Permanent address: Research and Technology Depth Naval Surface Warfare Center, Silver Spring, MD 20903-5000 Evidence is reviewed of particle size aspects of hole formation and growth, texture effects and grain size influences, for example, as revealed in stereosection fractographs of titanium and steel alloy ductile failure surfaces, in the latter case, near to the condition of cleavage fracturing. The results are related to model considerations of particle debonding and local region strain rate enhancement and plastic instability properties (see e.g. J.P. Gudas, G.R. Irwin et aI., in "Defect Assessment in Components - Fundamentals and Applications", Mechanical Engineering Publications Ltd. London, 1991, pp. 549568), as well as to constitutive equation aspects of plasticity and fracturing.
2:50 PM INVITED NUMERICAL SIMULATION OF DUCTILE RUPTURE: ANALYSIS OF EXPERIMENTAL SCATTER AND SIZE EFFECT: Jacques Besson, A. Pineau, Ecole des Mines de Paris, Centre des Materiaux, CNRS URA 866, 91003, BP 87 Evry Cedex, France Ductile rupture behavior is usually characterized with specimens of various types including smooth and notched bars, compact tension specimens, bending bars. In addition, similar specimens geometries of different sizes are also used. Using different specimen geometries allows to investigate the effect of mechanical parameters such as stress triaxility and amount of plastic deformation on ductile rupture. Changing specimen sizes allows to evaluate experimental dispersion and size effects. Considering these effects is of primary importance for the transferability of laboratory tests carried out on relatively small samples to assess the resistance of relatively large industrial components. Both dispersion and size effect are caused by material heterogeneities which have to be accounted for by modeling. This work presents both experimental data and numerical simulation relative to dispersion and size effects on two very different materials. The fust one is a plane carbon steel containing MnS inclusions which easily debond from the matrix so that rupture is essentially controlled by void growth. The second material is a cast ferrite - austenite duplex stainless stainless steel. Microcracks are continuously nucleated in the embrittled ferrite so that final rupture is essentially controlled by void nucleation. Both materials were tested using axisymmetric smooth and notched bars and Charpy specimens of different sizes. In order to obtain microstructural data, relevant to modeling, both materials were carefully examined. In the first case, initial local void densities (MnS inclusion content) were measured using image analysis. In the second case, local crack nucleation rates were determined by carrying out interrupted tensile tests and determining crack locations. These examinations are needed to get physically based data to be used in the modeling thus reducing the number of "fitting parameters". Modeling of rupture, dispersion and size effects can be done using two different approaches both based on finite element analysis. The first one (uncoupled) consists in carrying out simulations of the mechanical response of structures assuming that the material is undamaged. Subsequently, a local rupture criterion is applied to the structure to determine that the material remains unchanged. Subsequently, a local rupture criterion is applied to the structure to determine its failure probability. It is therefore assumed that damage is small enough not to affect the stress strain distribution in the part. In addition the material is supposed to break according to the weakest link theory. The second approach (coupled) is based on continuum damage mechanics using models for ductile metals such as those proposed by Gurson and Rousselier. In this case, the effect of damage evolution on stress distribution in the parts can be fully accounted for. In addition the effect of defect spatial distribution can also be investigated. No specific assumption has to be made on the onset of rupture. Finite element calculations were carried out for both materials using the Gurson-TvergaardIRousslier constitutive equations. Initial void volume fractions (first material) or microcrack nucleation rates (second material) were randomly distributed in the structures. Dispersion can be modeled by carrying a Monte Carlo type simulation using the same mesh and different random drawings. Size effect is modeled by keeping the element size constant, thus increasing the number of elements for larger structures. The uncoupled approach was also used for the first approach. Results
3:40 pm INVITED MACROCRACK NUCLEATION IN DUCTILE MATERIALS: Owen Richmond, Aluminum Company of America, Alcoa Technical Center, 100 Technical Drive, Alcoa Center, PA 15069 In ductile materials, it is typical of many microcracks and pores to nucleate and grow before some of these coalesce to form dominant macrocrack which leads to ultimate failure. This paper is concerned with quantitative identification of the microstructural regions in which this macrocrack nucleation occurs, and the development of constitutive relations for these regions. These microstructure-based constitutive relations can then be used in macromechanical analyses to evaluate potential improvement in macroscopic behavior due to alterations in microstructure. 4:05 pm INVITED MICROSTRUCTURAL EFFECTS IN DUCTILE FRACTURE: Anthony W. Thompson, Lawrence Berkeley National Laboratory, MS 62-203, One Cyclotron Road, Berkeley, CA 94720 Microvoid coalescence or MVC fracture depends strongly on microstructure. This applies to each of the constituent processes of MVC, namely nucleation, growth and coalescence of voids, and is true for both trans granular and intergranular MVC. Experimental as well as analytical evidence on this point reveals both needs for further experiments, and gaps in analytical understanding. Methods to vary the behavior of MVC processes, such as variations in temperature, or introduction of hydrogen, convey further information (provided MVC fracture is maintained) and have proven valuable in understanding these processes; of particular value are the notch bend tests, in which stress state can readily be varied to identify control of stress, strain, or a combination of the two. 4:30pm A MODEL FOR CRACK INITIATION AND CRACK GROWTH IN DUCTILE MATERIALS: Xi Zhang and Yiu- Wing Mai, University of Sidney, Centre for Advanced Materials Technology, Department of Mechanical and Mechatronic Engineering, Sydney, New South Wales 2006, Australia A refined mathematical model is presented in this paper to account for the effects of void nucleation, growth and coalescence on fracture initiation and subsequent quasi-static, slow and little crack growth in ductile materials under plane strain and mode I condition. A chain of larger voids uniformlydistributed ahead of the crack tip is used to model the discontinuous fracture process and discontinuous nucleation of small voids at second-phase particles is the main cause for crack initiation in high strength and ductility steels. A cumulative damage criterion, which is the ratio of uncracked length be-
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tween the crack tip and the first large void to characterize size, is employed. Effects of crack-tip constraint and material parameters on ductile fracture are discussed in terms of the gradient of the variation of crack-tip constraint within the damage wne. Estimation of upper-bound fracture toughness is established and numerical results show that, with the exception of crack growth there is no obvious constraint effect on ductile crack initiation.
4:50pm DUCTILE CAVITY GROWTH IN NORMALLY BRITTLE MATERIALS: Donald R. Curran, R.E. Tokheim, and T. Cooper, SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025 The term "ductile fracture" can be interpreted in a number of ways, but to a materials scientist who focuses on microscopic mechanisms the meaning is clear: "ductile fracture" means that failure occurs by the nucleation, growth, and coalescence of approximately ellipsoidal microscopic voids in plastically deforming material. To be sure, extremely ductile materials stretched under plane or uniaxial stress conditions may fail in the absence of voids by simple plastic necking. Nonetheless, in most practical engineering applications of failure in ductile materials, microscopic "ductile fracture" playa central role in the failure process. Frank McClintock was one of the pioneers in this area (as well as many others), and his 1968 paper [J. App!. Mech., 35, p.363J, along with papers by C. A. Berg [Proc. Fourth U.S. National Congress Appl. Mech. 2 (1962) 885J, J. R. Rice and D. M. Tracy [J. Mech. & Phys. Solids, 17 (1969) 202J, A. L. Gurson [Trans. ASME, 1. Eng. Mater. & Techno!' (1977) 2J, and M. Y. He and J. W. Hutchinson [J. App!. Mech. 48 (1981) 830J, stimulated much further work. The above papers discussed the conditions for cavity growth in a viscous or plastically deforming material under tension and shear. In the present paper, we take a similar approach, but consider cases in which the cavity growth is driven not only by the externally applied stresses, but also by internal cavity pressure. Such conditions arise when a material is exposed to penetrating radiation from lasers or x-ray sources of sufficient fluence to cause local heterogeneities to vaporize while leaving the matrix material relatively coo!. Under such loading conditions, microscopic cavity pressures of several tens of GPa may be produced, sufficient to cause the surrounding matrix material to flow plastically, even when the matrix material is a normally brittle material like a ceramic. Under some boundary conditions, the expanding cavities may drive the matrix material into tension, producing brittle tensile fractures between cavities. We present a computer model of the above processes, and illustrate the model with several example calculations.
5:10pm HYDROGEN EFFECTS ON THE DUCTILE FRACTURE ON IRONBASED SUPERALLOYS: Neville R. Moody'. I. Baskes' 1. E. Angelo'and T. Tsuji 2 'andia National Laboratories, P.O. Box 969, Mail Stop 9403, Livermore, CA 94551; zhizuoka University, Hamamatsu, Japan Austenitic superalloys can exhibit dramatic reductions in ductility and crack growth resistance when hydrogen triggers a change in failure mode. All failures begin by void growth at fractured matrix carbides. However, void growth is prematurely terminated terminated in hydrogen by second generation void formation at slip band intersections and separation of interconnecting slip band segments. As a first approximation to understanding hydrogen effects on the fracture process, we have combined the Embedded Atom Method with Monte Carlo simulations to model the segregation of hydrogen to dislocation in slip bands and slip band intersections. We will present these results and draw a direct correlation between the segregation of hydrogen to slip band intersections, void formation, and crack growth susceptibility.
5:30pm NEAR-TIP FRACTURE PROCESSES IN DUCTILE MATERIALS: Kwai S. Chan, Southwest Research Institute, San Antonio, TX 78238 Ductile fracture is generally considered to occur via void nucleation, growth, and coalescence mechanisms that result in a dimpled fracture appearance. For many materials, void initiation and growth take place at hard particles or inclusions. However, ductile fracture involving void formation has been observed in materials that contain neither hard particles nor inclusions. In this paper, the near-tip fracture processes in several structural alloys, including AI-, Ti-, and Nb-base alloys, that exhibit ductile fracture in a variety of microstructures with and without hard particles are summarized. Possible mecha-
nisms for the formation of dimpled fracture in these materials are identified. These fracture mechanisms are correlated with the microstructures and the fracture resistance curve to provide a basic understanding of the role of microstructure in the crack-tip fracture process, the transition from ductile to brittle fracture, and the source of fracture resistance.
SHAPING AND FORMING OF HIGH PERFORMANCE POWDER PRODUCTS: SESSION III Sponsored by: MOMO Powder Materials Committee Program Organizers: Dr. William E. Frazier, Naval Air Warfare Center Aircraft Division, Patuxent River, MD 20657; Prof. Henry R. Piehler, Dept. of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213; Dr. Jeffrey Waldman, Dept. of Materials Engineering, Drexel University, Philadelphia, PA 19104; Dr. Phillip Parrish, MATSYS Inc. Arlington, VA 22209 Tuesday, PM February 11, 1997
Room: Salon 7 Location: Clarion Plaza Hotel
Session Chairperson: Prof. Henry R. Piehler, Dept. of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213
2:00pm MECHANICAL PROPERTIES OF LASER FORMED PIM INCONNEL AND STAINLESS STEEL: J. W. Sears, Lockheed Martin KALP, Inc., Schenectady, NY Abstract not available.
2:30pm POWDER INJECTION MOLDING (PIM) OF INCONEL 718 AEROSPACE COMPONENTS: RobertM. Schmees', Joe Spirk02, Juan Valencia', 'Pratt & Whitney, West Palm Beach, FL; zConcurrent Technologies Corp., Johnstown, PA The feasibility and cost benefit of using PIM for the manufacture of aerospace components was investigated. An optimized thermal processing cycle was developed for hydrogen sintering, vacuum sintering, and HIPing the PIM Inconel 718 parts. The parts were subsequently solution and precipitation heat treatment. A tensile, creep, stress rupture, low cycle fatigue, and high cycle fatigue data base was generated. Tensile properties exceeded AMS 5663 minimum specification requirements. The associated cost reduction was greater than 50%. Both J52-P-409 Bushings and F1l9 Aircraft Mounted Nozzle Sidewall Saddle Supports were fabricated out of PIM Inconel 718.
3:00pm ADVANCES IN CUBIC PHASE (AlzCr)3 Ti ALLOY COATING TECHNOLOGY: D.K. Dewald', D.E. Mikkola', 'Waubik, Inc., Hancock, MI49930; 'Dept. of Metallurgical and Materials Engineering, Michigan Technological University, Houghton, MI 49931 Cubic phase alloys of (AI,Cr),Ti are being developed as high temperature, oxidation resistant coatings for Ti-based materials. High quality powders of these alloys have been made by high pressure gas atomization (HPGA) and are now available from a commercial powder manufacture. The powders have been applied to Ti-6AI-4V, Ti-6242, and Ti-47 AI2Cr-2Nb alloy sample pieces using low pressure plasma spray (LPPS) to form coatings 100-150j.l.m thick. Coupons cut from the samples have been subjected to high temperature cyclic oxidation tests. The as applied and oxidation tested coatings have been analyzed for structure and integrity. The results of these tests and analysis, related advancements in coating development, and powder processing will be discussed.
3:30pm MICROSTRUCTURAL ANALYSIS OF MECHANICALLY ALLOYED AND POWDER METALLURGY PROCESSED W·HfC AND W·Ir·HfC PENETRATOR RODS: Christine Kennedy, L.E. Murr, S. Pappu, D. Kapoor!, Dept. of Metallurgical and Materials Engineering, The University of Texas at EI Paso, EI Paso, TX 79968; 'Army Research Development and Engineering Center, Picatinny, NJ 07806
STRUCTURE AND PROPERTIES OF BULK AMORPHOUS ALLOYS IV Sponsored by: Jt. EMPMO/SMO Alloy Phases Committee, MSO Thermodynam· ics and Phase Equilibria Committee, MSO Atomic Transport Committee, MOMO Solidification Committee, Lawrence Livermore National Laboratory and Los Alamos National Laboratory Program Organizers: Patrice E.A. Turchi, Chemistry and Materials Science Department (L-268), Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551; Ricardo B. Schwarz, Center for Materials Science (MSK765), Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545; John H. Perepezko, Department of Materials Science and Engineering, University of Wisconsin, Madison, WI 53706
Tungsten heavy alloys (WHA) as well as depleted uranium (DU) alloys (U0.7S% (Ti) for example) have been the primary materials employed in large caliber, U.S. tank ammunition or kinetic energy (KE) penetrators. Since the deformation behaviors and resulting ballistic performance of these alloys are different, there has been considerable effort to develop alternative and more effective penetrator materials. This study involves the mechanical alloying (MA) and PM processing of tungsten-hafnium carbide (I, 2, and S weight percent) and W-HfC containing 0.1 % Ir as a novel approach to WHA development. Slugs ofW-lHfC, W-SHfC, and W-2HfC-0.Slr and W-SHfC-O.5lr processed from MA powder corresponding to high-speed attritor milling times ranging from 8 to 40 h, have been examined by light metallography and transmission electron microscopy (TEM). These products are remarkably free of disclocations and average (bulk) hardness range from 700 VHN for W-IHfC to 1200 VHN for W-SHfC precursor powders milled 16 h. The corresponding W-SHfC-O.S lr hardness was 12S0 VHN, and there were some interesting metallographic differences between the W-SHfC and W-SHfC-O.S lr. HfC particle size and size distribution measurements have also been made in the TEM, and the effects of attritor milling time on residual hardness and microstructure have been examined.
Tuesday, PM February 11, 1997
Room:340A Location: Orlando Convention Center
Session Chairperson: Patrice E.A. Turchi, Chemistry and Materials Science Department (L-268), Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94551
2:00pm MOLECULAR DYNAMICS SIMULATION OF MECHANICAL PROP· ERTIES OF AMORPHOUS ALLOYS: Tomoyasu Aihara Jr., Tsuyoshi Masumoto, and Yoshiyuki Kawazoe, Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-77, Japan
4:00pm IN SITU METAL MATRIX COMPOSITES UTILIZING INTERME· TALLIC MATRIX COMPOSITE (IMC) REINFORCEMENT: S.L Kampe', lS. Marte', L. Christodoulou2, T. Zarrah 2,'Vrrginia Polytechnic Institute and State University, Blacksburg, VA 24061; 2MATSYS, Inc., Arlington, VA 22209
Macroscopic mechanical properties of materials arise from cooperative dynamics of atoms. However, it is difficult to detect the atomistic dynamical behavior by in situ experiment. We performed a large scale molecular dynamics simulation to study the deformation and fracture processes in Zr-Ni amorphous alloy. Finnis-Sinclair type pair functional potentials is used. Uniaxial strain is applied for a nano-size rod with constant strain rate at various temperatures. Tensile processes are traced by checking the internal energy and by the snapshots for atom configuration. The discrete atomic model reproduces the behavior of the continuum matter. The correlation between the inhomogeneous atom configuration and atomic level stress is analyzed.
A new processing methodology is described whereby metal matrices are reinforced in situ by deformation-processing of metalllMC blends. The IMC "reinforcement" is exemplified by its high strength, attributable to high loadings of dispersed ceramic (e.g. 30-S0 v%) within its intermetallic matrix. Processability of the metallIMC composite is governed by the thermodynamic compatibility of the metal and the intermetallic, and the relative high temperature flow behavior of the metal and the IMe. The methodology will be illustrated through its application to a titanium metal matrix composite, produced by hot extrusion of prealloyed Ti-6AI-4V and IMC (A13Ti + 40 v% TiB2) powders. Microstructures and preliminary mechanical behavior will be presented for composites produced over a range of deformation processing conditions and with varying percentages of IMC reinforcement.
2:40pm METASTABILITY AND PROPERTIES OF METALLIC BULK GLASS FORMING ALLOYS: Hans J. Fecht, Institute of Metallic Materials, Technical University Berlin, Hardenbergstrasse 36, PN 2-3, 0-10623 Berlin, Germany The absence of crystallization over a wide time/temperature window can be utilized to produce bulk metallic glass by relatively slow cooling of the melt. For a number of alloys including the multicomponent Pd-Ni-P, Au-Pb-Sb, Zr-Cu-Ni-AI, and Zr-Ti-Ni-Cu-Be alloys the relevant thermodynamic and thermomechanical properties of the metastable glassy and undercooled liquid states have been measured below and above the glass transition temperature. These measurements include specific heat, viscosity, density and elastic properties as functions of temperature. As a result it becomes obvious that the maximum undercooling for these alloys is given by an isentropic condition before an enthalpic or isochoric instability is reached. Alternatively, these glasses can also be produced by mechanical alloying, thus replacing the thermal disorder by static disorder and resulting in the same thermodynamic glass state. For the "weaker" glasses the isentropic instability also coincides with a divergence of the viscosity. During heating through the undercooled liquid a nanoscale phase separation occurs for most glasses as a precursor of crystallization. Further measurements of the mechanical and tribological wear properties point to the unique engineering applications of this new class of advanced materials.
4:30pm RHEOLOGY OF POWDER INJECTION MOULDED PARTS: Sedat {jzbilen" Gazi University, Faculty Technical Education, Metal Dept., Ankara, Turkey The determination of the variation of pressure against time for PIN feedstocks during their stay in the mould has gained importance in PIM technology, a hot research area of recent years. The possibility of this will case the control of properties of the parts that will be produced with this technology, such that the conditions to increase the productivity of the process can be realized. In the present work, the rheology of 316L stainless steel powdervariable binder mixes were therefore studies. Results of this investigation will be presented.
3:20 pm BREAK
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3:40pm ENVIRONMENTAL EFFECT IN BULK AMORPHOUS ALLOYS: C. T. Liu, L. Heatherly, D.S. Easton, Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6115; C.H. Chen, Health Science Research Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831, Akihisa Inoue, Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-77, Japan
STRUCTURE AND PROPERTIES OF INTERNAL INTERFACES IV: Precipitation and Segregation Sponsored by: Jt. EMPMD/SMD Chemistry & Physics of Materials Committee, MSD Computer Simulation Committee Program Organizer: Diana Farkas, Dept. of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061; Elizabeth A. Holm, Sandia National Lab, Physical and Joining Metallurgy, MS 1411, Albuquerque, NM 87185-0340; David J. Srolovitz, Dept. of Materials Science & Engineering, University of Michigan, Ann Arbor, MI 48109-2136
Recent studies indicate that moisture-induced hydrogen embrittlement is a major cause of low ductility and brittle fracture of many intermetallic alloys in moist air at ambient temperature. This embrittlement involves the reaction of reactive elements in intermetallic alloys with the moisture in air and the generation of atomic hydrogen which penetrates into crack tip and causes loss of tensile ductility. In the current study, bulk amorphous alloys based on Zr-AI-Ti-Cu-Ni were tested in tension at room temperature in various environments. Preliminary results indicate that the tensile fracture strength of about 1400 MPa is not strongly affected by test environments. These results alone do not rule out the possibility that these amorphous alloys may react with moisture during tensile testing. Additional work involving laser desorption spectroscopy will be conducted in order to detect this reaction. Research sponsored by the Laboratory Directed Research and Development Program of the Oak Ridge National Laboratory, U. S. Department of Energy, under contract number DE-AC05-960R22464 with Lockheed-Martin Energy Research Corporation.
Tuesday, PM February 11, 1997
Room: 330G Location: Orlando Convention Center
Session Chairperson: David J. Srolovitz, Dept. of Materials Science & Engineering, University of Michigan, Ann Arbor, M148109-2136
1:30 pm INVITED INFLUENCE OF THE CRYSTALLOGRAPffiC PARAMETERS OF GRAIN BOUNDARIES ON THEIR ENERGETIC, KINETIC AND CHEMICAL PROPERTIES: E. Rabkin, Wolfgang Gust, Max-PlanckInstitut fUr Metallforschung and Institut fUr Metallkunde, Seestr. 75, D-70 174 Stuttgart, Germany
4:20pm SEEBECK PHENOMENON ON AMORPHOUS-CRYSTALLINE INTERFACEANDAMORPHOUS-CRYSTALLINE THERMOCOUPLE: Mikhail V. Finkel, DAATH-Scientific Center, 9926 Haldeman Avenue #36A, Philadelphia, PA 19115; Jim S.-J. Chen, Mechanical Engineering Department, Temple University, 12th & Norris Street, Philadelphia, PA 19122
We review the recent experimental data about the dependence of the grain boundary (GB) energy on the misorientation of adjacent grains and on the inclination of the GB plane. The relationship between inclination dependence of the GB energy and the morphology of faccted twin Gbs in Cu and Ag is demonstrated. The kinetics of development of the faccted morphology at the originally flat twin GB in Cu is studied experimentally. The strong influence of small additions of Bi on the chemical compositions of Gbs in Cu is shown. The effect of atomic ordering on the GB energy is considered. The discontinuous ordering reaction in Fe-50 at.% Co alloy in combination with the analysis of the electron backscattered Kikuchi patterns is used to study the atomic mobility in Gbs in the ordered B2 alloy. It is shown that the low energy special Gbs exhibit also the decreased atomic mobility.
Thermo-electric Seebeck phenomenon on amorphous-crystalline interface in several alloys is studied. The thermocouples, consisting of amorphous and crystalline parts of the same alloy are proposed and investigated. The amorphous-crystalline transition zone formed by heating of amorphous alloys in heterogeneous temperature field serves as a hot junction. It is shown that this zone could be made as narrow as 10-100 rnm. Thermo-Electric Moving Force (TEMF) for thermocouples made from Fe-B, Ni-Fe-Si-B, and Co-Fe-Si-B alloys was measured. TEMF of thermocouple made from Co-Fe-Si-B alloy in its as-cast condition can achieve 8.1 !.l VIK, and it is constant in the range 293 K to 593 K. It is shown that relaxation of the amorphous structure affects the TEMF of amorphous-crystalline thermocouple. (Patent is applied)
2:10pm THE EFFECTS OF GRAIN BOUNDARY MISORIENTATION ON M23C6 PRECIPITATION AND SENSITIZATION IN 304 STAINLESS STEEL: Elizabeth Trillo, L.E. Murr, Department of Metallurgical and Materials Engineering, The University of Texas at El Paso, EI Paso, TX 79968 The correlation between grain boundary misorientation and energy has been the subject of study even before Stickler and Vinckier (in 1963) demonstrated that sensitization behavior is related to the energy of different types of individual boundaries in the sensitizing temperature range of 500-850°C. This research goes beyond these types of studies by attempting to uncover the role of grain boundary misorientation on M23C6 precipitation behavior in 304 stainless steel. The four materials utilizaed in this study having differing carbon contents (0.01, 0.025, 0.05, 0.07%C) and were heat treated at 670°C for 10 and 50 hours. In addition, the 10 hour samples were deformed (0, 10, and 20% true strain) to observe simultaneous strain effects. Electrochemical Potentiostatic Reactivation (EPR) tests were performed to characterize the sensitization behavior, and the precipitation behavior was observed through the transmission electron microscope (TEM) at 200kY. A "critical nucleation energy" was found to be in the range of 16 mJ/m2 to 265 mJ/m' which corresponds to the energies of special boundaries, no precipitation was observed on coherent twin boundaries (#16 mJ/m2). This research supported in part by the Patricia Roberts Harris Fellowship. 2:30pm GRAIN BOUNDARY SEGREGATION AND PRECIPITATION EFFECTS ON ENVIRONMENT-INDUCED CRACKING: S.M. Bruemmer, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA. Environment-induced cracking at internal interfaces has long been explained due to local chemistry differences. Widespread use of high resolution analytical techniques (analytical transmission electron microscopy and scanning
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Auger microscopy) has recently "quantified" this effect by direct correlation's between grain boundary composition and intergranular failure. Examples of this quantification will be presented and critical interfacial compositions identified for various metallic alloys. material susceptibility can often be minimized by controlling segregation and precipitation characteristics at grain boundaries. Compositional anisotropy among internal interfaces, and its effect on cracking, will also be demonstrated and discussed. Work supported by the Office of Basic Energy Sciences, Division of Materials Sciences, U.S. Department of Energy under contract DE-AC06-76 RLO 1830.
4:30pm ADVANCE IN STUDY OF NON-EQUILIBRIUM SEGREGATION ON INTERFACE: Xinlai He, Huaiyang Cui, Department of Materials Physics, University of Science and Technology Beijing, 100083, Beijing, China Equilibrium segregation of solute on interface has been recognized quite a long time. In recent years, there are more interests in non-equilibrium segregation, for example, the boron non-equilibrium segregation on grain boundaries during cooling, annealing and pre-strained treatment has been studied systematically. In 1991, by means of Particle Tracking Autoradiograph (PTA) technique, it was found that boron non-equilibrium segregates on moving boundaries during recrystallization in low carbon steels (X.L.He). In Fe-3%Si alloy with b.c.c. structure, it was observed that no detectable boron segregation on boundaries during continuous cooling and annealing but a stronger boron segregation on moving boundaries during recrystallization (S.H.zhang, 1992). Recently, in Fe-30%Ni with f.c.c. structure, a significant segregation of boron was shown on recrystallizing boundaries while segregation of boron was hardly observed on primary grain boundaries during recrystallization at high temperature (H.Y.Cui, 1995). These investigations indicate that three characteristics relate with the moving boundary segregation: (1)the segregation accompanied with motion of boundary (2)the degree of the segregation was higher than that at thermodynamical equilibrium (3)the velocity of moving boundary and addition of alloy elements influenced on the segregation process. In order to explain the phenomenon, based on the interaction between dislocations and the moving boundaries during recrystallization, a dislocation relaxation and widening grain boundary mechanism of solute segregation on moving boundaries was proposed.
2:50pm SELECTIVE PRECIPITATION ON GRAIN BOUNDARY: l. lang, Y.B. Lee', I.H. Kuk, K.A.E.R.I., P.O. Box 105 Yusong, Taejon, KOREA; 'Korea Univ. I Anam-dong, Sungbuk-gu, Seoul, KOREA Ni-Cr-Fe Alloy (UNS N06690) is being widely used as corrosion resistant tubing material in nuclear power plants and believed beneficial to stress corrosion resistance to have intergranular chromium carbide precipitates (semicontinuously or continuously). Alloys were prepared through VIM and ESR and tubular products were fabricated by pilgering process. Several solution heat treatments were conducted at a relatively rapid heating and cooliug rate. Selective precipitation of chromium carbide along grain boundary was observed in this alloy. Even along a single grain boundary carbide precipitates were revealed as very discretely distributed in association with twins. Distribution and orientation relationship of precipitates with grain boundary in association with twins were analyzed through electron microscopy and explained with CSL model. 3:10 pm BREAK
SYNTHESIS OF LIGHT-WEIGHT METALLIC MATERIALS II: Metallic CompOSites IV: Alloying, Thermomechanical Processing and Microstructural Control
3:30 pm INVITED ATOMISTIC STUDIES OF SOLUTE-ATOM SEGREGATION AT GRAIN BOUNDARIES IN METALS: SIMULATION AND EXPERIMENTS: David N. Seidman, Northwestern University, Department of Materials Science and Engineering, Evanston, IL 60208-3108
Sponsored by: MSD Synthesis/Processing Committee Program Organizers: C.M. Ward-Close, Structural Materials Center, R50 BUilding, Defense Research Agency, Farnborough, Hampshire, GU14 6TD, United Kingdom; F.H. Froes, University of Idaho, Institute for Materials and Advanced Processes, Mines Bldg 204, Moscow, ID 83844-3026; D.J. Cheliman, Lockheed Aeronautical Systems Co., Lockheed Corporation, Marietta, GA 30063·0150; S. S. Cho, Vice President of Rapidly Solidified Materials Research Center, (RASOM), Chungnam National University, Taedok Science Town, Taejon 305-764 Korea
I review our studies of the relationship between the atomic structure of grain boundaries (GB) and solute-segregation in binary metallic alloys. The principal experimental tool utilized to measure segregation is atom-probe microscopy. This is used in conjunction with Monte Carlo techniques (Metropolis algorithm and overlapping distributions MC) to explore the multidimensional GB phase space. Experimentally we determine the five macroscopic degrees of a GB employing transmission electron microscopy and then determine the Gibbsian interfacial excess of solute of the same GB employing atom-probe microscopy. The simulational approach uses lattice statics calculations to determine initially the lowest energy GB structures and then MC simulations to calculate their Gibbsian excesses. The effects of both the macroscopic and microscopic degrees of freedom are studied. It is demonstrated that the Gibbsian excess is a complicated function of both the macroscopic and microscopic degrees of freedom. Also a GB' s atomic structure determines the partition between segregation at dislocation's cores and in the elastic stress fields of GB dislocations. It is concluded that none of the geometric criteria discussed in the literature is capable of predicting the propensity for GB segregation. This research is supported by the National Science Foundation, Division of Materials Research.
Tuesday, PM February 11, 1997
Room: 330F Location: Orlando Convention Center
Session Chairpersons: P. Grant, University of Oxford, Department Of Materials, Parks Road, Oxford OX1 3PH, UK UK UK; M.A. Iman, US Navy Naval Research Lab, Materials Science & Technology Div., Washington, D.C. 20375
2:00pm FABRICATION OF TiNi INTERMETALLIC COMPOUNDS BY SELFPROPAGATION HIGH· TEMPERATURE SYNTHESIS PROCESS (SHS): Suk-Kwon Ko, Joong-Chai Jung, Jong-Hyeon Lee, ChangWhan Won, Rapidly Solidified Materials Research Center(RASOM), Chungnam National University, Yuseong, Taejon, 305-764 Korea
4:10pm INTERFACE ENGINEERING FOR SINTERING CORDIERITE GLASS-CERAMIC COATINGS ON MOLYBDENUM: ThomasA. Kuhr, Guo-Quan Lu, Dept. of MSE, VPI & SU, Blacksburg, VA 24061
TiNi intermetallic compounds were manufactured by the self-propagating high-temperature synthesis process. The effects of chemical composition(NiI Ti=0.5 -2.0 molar ratio), compaction pressure and preheating temperature on the reaction were investigated. As the molar ratio ofNi, compacting pressure and preheating temperature were increased, the combustion temperature and its velocity were increased. In the every mole ratio ofM, without preheating, secondary phases such as Ti,Ni, TiNi3' Ti3Ni4 as TiNi were found in the products according to the XRD analysis. At the same condition, the products prepared by of 200 were TiNi single phases by perfect reaction. Hence, the reasons to form the different phases during the reaction and the forming mechanism of TiNi for combustion reaction were discussed.
An economical technology for laying down thick ceramic coatings on a metal substrate is to tape-cast a ceramic slurry on the metal surface followed by binder bum-out and sintering. We used the technology to produce cordierite coatings on molybdenum for use as electrostatic wafer chucks. A critical issue in the production was adhesion between the two materials after the coatings were sintered at temperatures ranging from 900°C to 1000°C. To solve the problem, thin metallic interlayers were deposited by electroplating on Mo surface before tape-casting. We will discuss the selection and processing of several interlayer materials that significantly enhanced adhesion between the ceramic coating and metal substrate.
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2:20pm RAPID SYNTHESIS OF NANOSTRUCTURAL INTERMETALLICS AND THEIR BULK MECHANICAL PROPERTIES: S.M. Pickard, A.K. Ghosh, Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109-2136 A PVD process has been developed to produce bulk intermetallics at high rate by direct vacuum evaporation. Independent elemental sources are directly heated using 5kW electron beams and the evaporate is deposited as a nanolaminated (layered) structure at a rate of I-mrnlminute on a rotating substrate. Insitu reaction occurs on the heated substrate to produce a homogenous nanograined bulk intermetallic deposit. The deposit can be further thermomechanically processed to produce optimum mechanical properties. TIAl, NiAI binary and ternary alloy systems has been chosen for initial evaluation of potential mechanical property and processing advantages of bulk PVD. Both relatively thin 9140-180mm) and relatively thick (2.3) mm) layers of intermetallic alloys, have been formed. Hardness characterisation of the -deposited film shows a Vickers hardness value which is 2-3 times higher than the expected value for an as cast alloy. An initial flow stress of 700-800 MPa has been observed for the TlAl, which is higher than that of conventional cast material, with delimitation failure of the layered material. Tests on the bulk material using 3-Point banding indicate and rupture strength of 450500MPa for Ti-30a% AI, with linear-elastic loading response to failure, indicative of extrinsic defect controlled strength. Elevated temperature tensile tests are being conducted on the intermetallics to determine rate sensitivity. 2:40pm DEVELOPMENT OF Nb3Al Mo AND Nb3Al TiCr BASED ALLOYS: E. Passa, G. Shao, P. Tsakiropoulos, Dept. of Materials Science and Engineering, University of Surrey, GU2 5XH, UK Abstract not available.
4:00pm SYNTHESIS OF MoSi, BASED COMPOSITES: S. Walloe, L. Christodolou, P.S. Goodwin, C.M. Ward-Close: Dept. of Materials Imperial College, Prince Consort Rd., London SW7 2BP MoSi 2 is a promising candidate for future high temperature structural applications because of its high melting point, excellent high temperature oxidation resistance and low density. However, MoSi, also suffers from poor room temperature fracture toughness and inadequate elevated temperature strength. Various attempts have been made to produce a MoSi,-based composite to improve properties, but have often resulted in oxygen pick-up which forms deleterious Si02 • This paper reports work undertaken to investigate process parameters controlling the production of MoSi 2 composites using a reaction synthesis technique. Elemental Mo, Si and C powders were used as starting materials and were processed to produce a SiC - reinforced MoSi 2 composite by in-situ reaction. The effect of additional components in the synthesis reaction on the final oxygen content of the material was also investigated. The size, shape and distribution of the SiC reinforcement have been characterised as a function of the starting powders and the processing conditions used. 4:20pm OXIDATION BEHAVIOUR OF Nb3AI-xMo ALLOYS: E. Passa, G. Shao, P. Tsakiropoulos. Department of Materials Science and Engineering, University of Surrey, Guildford, Surrey GU2 5XH, England, UK Phase selection and microstructural refinement in Nb-17Al-xMo (x=20,30,40) alloys can be controlled via alloy design and solidification processing route. The formation of ordered (B2) or disordered (A2) phases in the as cast microstructures of cold hearth processed ingots and cold hearth melt overflow processed ribbons will be briefly reviewed. DSC and TG studies of the ingots and ribbons will be discussed with emphasis on the oxidation behaviour of the alloys. It will be shown that additions of Mo can improve the oxidation behaviour of Nb3A 1.
3:00pm COMPRESSIVE STRENGTH AND FATIGUE PROPERTIES OF BEAl ALOYS: R. Schneeberger, B. Bavarian, School of Engineering and Computer Science, California State University at Northridge, Northridge, CA 91330; R. Hayes, Metals Technology, Inc. 19080 Nordhoff St, Northridge, CA 91330
4:40pm GRAIN SIZE CONTROL AND PROPERTIES OF TiAl-BASED ALLOYS: S. Davey, P. Gouma, A. Godfrey, D. Hu, P.A. Blenkinsop, M.H. Loretto,JRC in Material for High Performance Applications, The University of Birmingham, Edgbaston B 15 2TT, UK
Both 40 and 62 wt% beryllium compositions were evaluated for ambient and elevated temperature compressi ve strength at low and high strain rates. Data indicated a strong influence of beryllium percentage along with an increase of yield point for fast strain rates of 0.5-3 in/in/minute. Fatigue properties of a ternary Be-AI-Ag cast and extruded material were determined for full reversal and standard tension fatigue conditions. Typical SoN curve behaviour including endurance limit was observed.
The production of TiAl-based alloys with small grain sizes has been approached in two distinct ways. Firstly, by addition ofB-containing compounds to the melt and secondly via atomisation and subsequent processing. These route coupled with hot extrusion, allow control of the microstructure of these alloys so that a wide range of properties can be obtained. Results for several different alloys will be presented and the influence of composition on control of microstructure and hence of properties will be illustrated.
3:20pm CREEP BEHAVIOUR OF TWO BERYLLIUM-ALUMINIUM ALLOYS: R. Schneeberger, B. Bavarian, School of Engineering and Computer Science, California State University, Northridge, 18111 Nordhoff St, Northbridge, CA 91330; R. Hayes, Metals Technology, Inc 19080 Nordhoff St, Northridge, CA 91330.
5:00pm MICROSTRUCTURE AND MECHANICAL PROPERTIES OF GAMMA TITANIUMALUMINIDE STRIP: Gopal Das, Pratt & Whitney, POBox 109600, West Palm Beach, FL-3341O-9600
Creep testing performed on 40 and 62 wt% beryllium compositions of a power metallurgy composite alloy at several elevated temperatures indicated a dependence of steady state creep rates and times to rupture on beryllium content, test direction, stress, and test temperature. A stress exponent of 8.5 for 40% beryllium and 10 for 62% beryllium was obtained form tests at 550 degrees F 630 degrees F. Activation energies for creep were somewhat higher than for self-diffusion in either pure metal, and exhibited significant anisotropy. 3:40 pm BREAK
Thin ganuna titanium aluminide (Ti-45A 1-2Cr-2Nb at. %) series, 20 mils thick, were produced by the melt overflow rapid solidification technology (MORST) process. The microstructure resulting from heat treatments was studied by a combination of optical, X-ray, SEM and TEM methods. Transition temperatures including the alpha transits temperature were determined by DTA. Textures of gamma TiAI strips were studied on as-cast and heat treated specimens. The microhardness was measured for specimens subjected to different heat treatments. Tensile properties of heat treated specimens were determined at RT-760°C along the strip growth direction and perpendicular to it. The material failed in a brittle manner at RT for both orientations. It started to yield at 650°C and at 760°C, it failed in a ductile manner. The strain-to-failure along the direction perpendicular to strip growth direction was poor. Deformation microstructure was analysed by TEM and fractographs were studied. Results will be compared with those of investment cast and wrought ganuna titanium aluminised. This work was supported by NASA LeRC, Cleveland, OH under Contract No. NAS3-26385.
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9:30am DAMAGE MECHANISM IN SOLID PARTICLE EROSION OF FeAlAl203 THERMAL SPRAY COATINGS: Brian Schorr, Arnold Marder, Lehigh University, Bethlehem, PA 18015; Daniel Sordelet, Iowa State University, Ames Laboratory, Ames, IA 50011
ADVANCES IN COATINGS TECHNOLOGIES II: Session V Sponsored by: MDMD Surface Modification & Coatings Technology Committee Program Organizers: C.R. Clayton, State University of New York at Stonybrook, College of Engineering and Applied Sciences, Stony Brook, NY 11794-2200; J.K. Hirvonen, US Army Materials Technology Lab., Arsenal St., Watertown, MA 02172; A.R. Srivatsa Wednesday, AM February 12, 1997
The effect of microstructure and splat cohesion on the erosion damage mechanism of FeAI-AI203 plasma and high velocity oxy-fuel (HVOF) coatings was studied. The AI203 content in the cermet pre-sprayed powders was varied from 0-80%. Microstructural evaluation revealed a good correlation between the AI203 in the pre-sprayed powders and the final as deposited plasma coatings. In addition, increased porosity was measured as the AI203 content of the coatings increased. It was found that plasma sprayed coatings tend to fail via splat delamination due to poor cohesion and high porosity, providing accelerated weight loss compared to HVOF and wrought alloys. The addition of AI203 to the plasma sprayed FeAI increased the erosion rate of the tested coatings. Examination of the eroded surfaces revealed cracking of the AI203 which led to undercutting of the FeAI matrix. In contrast, partial removal of splats by gouging as well as cracking occurred in the HVOF coatings.
Room: 315B Location: Orlando Convention Center
Session Chairperson: TBA
8:00am TRIBOLOGICAL MEASUREMENT METHODS FOR COATINGS: Stephen M. Hsu, National Institute of Standards and Technology, Gaithersburg, MD20899
9:50am PLASMA NITRIDING OF TOOL STEELS: Sun K. Kim, Department of Metallurgical Engineering, University of Ulsan, Ulsan, Kyung Nam, Korea 680-749
Coatings are increasingly being used as a means to protect materials from harsh environments. As the coating technology becomes more sophisticated, the requirement for new and better measurement techniques to understand wear mechanisms and coating effectiveness soars. For functionally gradient coatings, the issue of measuring local properties vs global properties in determining the extent of compositional change necessary to achieve a particular performance level is critical. For very thin hard coatings on relatively soft substrates, the deformation and yielding of the substrate affect the coating effectiveness. This paper presents some new and novel techniques that can be used to measure the coating properties under rubbing conditions.
In order to produce composite surface layers by combining nitriding and coating of titanium compounds, nitriding of tool steels to obtain only diffusion layer on surface is desirable. In this paper, results on experiments to obtain a diffusion layer with zero or minimum amount of compound layer were presented. With SKDI1, SKD61 and SKH9 tool steels, experimental process parameters such as hydrogen and nitrogen gas ratios, temperature, pressure and time were changed to obtain an optimum condition.
8:35am PLASMA·ASSISTED DEPOSITION OF TRIBOLOGICAL COATINGS: K. Sridharan, RA. Breun, A. Chen, J.R Conrad, RP. Fetherston, J. Firmiss, J.P. Hockers, J.S. Kim, R.I. Matyi, M.M. Shamim, C. Tan, E.A. Treptow. University of Wisconsin, Madison, WI 53706
10:30 am MICROSTRUCTURE,WEAR RESISTANCE,AND HIGH TEMPERATURE OXIDATION RESISTANCE OF BORONIZED GAMMA·nAl: Soosik Kim, Youngsic Yoon, Hansam Kiml, Kyeongsoon Park2,Met. Eng. Dept., Inha Univ., Inchon, Korea, lMetal1. Eng. Dept., Inha Tech. College, Inchon, Korea, 2Materials Eng. Dept., Chung-ju National Univ., Chungju, Korea
A variety of alloy and compound coatings can be synthesized using plasmabased techniques. At high target bias voltages, implantation of ions into the target can be achieved to dose levels sufficient to bring about beneficial surface modification. The range of compositions achievable, low processing temperatures and environmental cleanliness makes this technique potentially attractive for a number of applications. The paper will focus on the design and development of wear resistant coatings using the plasma source ion implantation method operated in the ion-assisted deposition mode. Results of microstructural characterization and tribological evaluation of these coatings will be presented. The work is supported by the US Army Grant No. DAAn0494-G-0283 and NSF Grant No. DMI-9528746.
Ti-45.0 at%AI-1.6% Mn intermetallic compounds, which were fabricated by reactive sintering, were boronized in the temperature range 1150 to 1250 C under a flow of Ar gas in a graphite pack with boron carbide (B 4C) powders. Energy dispersive x-ray spectroscopy (EDXS) and x-ray diffraction (XRD) were used to investigate the phase present in the coating layer. The coating layer was composed ofTi2B, TiB, and AI2Ti4C2phases. The formation mechanism of the above compounds in the coating layer was investigated. Some vacancies were found below the coating layer. The thickness of the coating layer increased with increasing boronizing temperature and time. The activation energy of formation of the coating layer was calculated to be 320 KjI mole. The microhardness of the coating layer was extremely high (700-800 Hv), compared to that (3OO-400Hv) of the substrate, improving the resistance to wear and high-temperature oxidation.
9:10am A COMPARATIVE ANALYSIS OF MECHANICAL PROPERTIES IN COATED SYSTEMS BY INSTRUMENTED INDENTATION: Larry SeitZJ1uln, Code 6170 Naval Research Laboratory, Washington, DC 20375
10:10 am BREAK
Vickers indentation was performed on a variety of coating-substrate combinations. Force-displacement curves were obtained by continuously monitoring the loading and unloading of the indentor. Different methodologies for analyzing the data (i.e. shape effect vs contact depth as well as regression vs polynomial fitting) were compared. Mechanical property profiles of the coated system were obtained from both the loading and the unloading curves, and the properties determined from both curves were compared. Analysis of the unloading curve readily yields hardness and elastic modulus data, while analysis of the loading curve yields additional information. The potential for using instrumented indentation as a quality control tool for coated systems will be discussed.
10:50 am THE WEAR-RESISTANCE OF nNi INTERMETALLICS WITH TiN COATING: H.C. Lin, H.M. Liao, J.L. He, K.M. Lin, K.c. Chen, Department of Materials Science, Feng Chia University. Taichung, Taiwan 407, China The wear resistance of TiNi intermetallics with TiN coating was studied by wear test, hardness measurement, XRD and microstructure observation. Both TiN and Ti2Ni layers are found to form on the surface of ion-nitrided TiNi intermetallics. These layers can improve the wear-resistance of these TiNi intermetallics. The effects of nitriding temperatures, TiNffi2Ni thickness and applied wear-load on the wear behavior of TiNi intermetallics are investigated in this paper. Meanwhile, the major wear mechanisms in these ionnitrided TiNi intermetallics are also discussed.
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formed only after post annealing the milled powder mixtures and the annealing temperature had a strong effect on the formation of the composite powders. Based on the results from XRD, TEM, DTA and TGA, the formation mechanisms of the composite powders will be discussed.
ADVANCES IN SYNTHESIS AND PROCESSING OF METAL CERAMIC MATRIX COMPOSITES III: Sponsored by: MSD Materials, Synthesis & Processing Committee and Jt. SMDI MSD Composite Materials Committee Program Organizers: L.L. Shaw, Dept. of Metallurgy and Materials Engineering, University of Connecticut, Storrs, CT 06269; E.J. Lavernia, Dept. of Mechanical and Aerospace Engineering, University of California - Irvine, INine, CA 92717; S. Krishnamurthy, UES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432-1894; E.S. Chen, U.S. Army Research Office, 4300 S. Miami Blvd., Research Triangle Park, NC27709
9:50 am INVITED SYNTHESIS OF METAL MATRIX COMPOSITES BY MECHANICAL ALLOYING: F.H. Froes, C. M. Ward-Close, E.G. Baburaj, A. Vassel, College of Mines & Earth Research, University of Idaho, Moscow, ID 83844
Wednesday, AM February 12, 1997
10:30 am AN INVESTIGATION OF THE VACUUM HOT PRESSING BEHAVIOR OF SILICON CARBIDE FIBERS COATED WITH NANOCRYSTALLINE Ti-6AI-4V: Joseph M. Kunze, Triton Systems, Inc., 114 Turnpike Road, Chelmsford, MA 01824; Haydn N. G. Wadley, Intelligent Processing of Materials Laboratory, Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22903
Abstract not available. 10:20 am BREAK
Room: 340B Location: Orlando Convention Center
Session Chairpersons: Dr. Edward S. Chen, U.S. Army Research Office, 4300 S. Miami Boulevard, Research Triangle Park, NC 27709; Dr. Douglas B. Gundel, Systran Co., Inc., 4126 Linden Ave., Dayton, OH 45432
8:30 am INVITED INTERMETALLIC MATRIX COMPOSITES PREPARED BY MECHANICAL ATTRITION: A REVIEW: Carl C. Koch, Department of Materials Science & Engineering, North Carolina State University, Raleigh, NC 27695
The vacuum hot pressing of silicon carbide monofilaments coated with nanocrystalline Ti-6A 1-4V has been studied and modeled. In the experiments, surprisingly high identification rates were observed, even at processing temperatures and pressures well below those used for processing conventional Ti-6AI-4Y. From the cross sections of partially consolidated specimen, the evolution of coated fiber-fiber contacts and pore shapes were determined. The pores were found to be cusp-shaped throughout the consolidation process. Columns of coated fibers were observed to form which resulted in regions oflocally high fiber volume fraction. In the model, the initial densification was based upon a micromechanical contact analysis for a metal coated fiber. Final stage densification was analyzed by modifying the Qian et al strain rate potential for a power law creeping body containing isolated cusp-shaped pores. Simulations of the VHP experiments were performed using this model which incorporated time and temperature dependent microstructure relations. Overall, the simulations compared well with the experimental density data, although the load supported by the regions of locally high fiber volume fraction resulted in the model slightly overestimating the observed densification time response.
The interest in intermetallic matrix composites has grown in recent years due to the realization that monolithic intermetallics would not likely satisfy the balance of properties needed for advanced aerospace systems. Processing of intermetallic matrix composites is a critical issue and a number of methods have been explored to fabricate such composites with either continuous or discontinuous reinforcements. While the latter category in general provides less improvement in mechanical behavior, this is the type of composite where mechanical alloying may provide an inexpensive processing route. Intermetallic systems to be discussed include Ni3Al, NiAl, Ti3Al, TiAl, and MoSi2 • Early work on oxide dispersions in intermetallics by mechanical alloying, dispersions introduced by cryomilling, and nanocrystalline intermetallic composites will be covered by this review. The possibility of superplastic forming of nanocrystalline intermetallic matrix composites will also be considered.
10:55 am MODEL-BASED SIMULATION OF THE CONSOLIDATION PROCESSING OF METAL COATED FIBERS: D.M. Elzey, R. Vancheeswaran, H.N G. Wadley, Intelligent Processing of Materials Laboratory, Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22903
9:00am MECHANICAL ALLOYING OF INERT GAS ATOMIZED AI-Li-CuMg-Zr ALLOY/SiC SHORT FIBERS REINFORCED MMC POWDERS: S. Ozbilen, Gazi University, Faculty of Technical Education, Department of Metals Education, Teknikokullar, Arkara, Turkey
The metallization of structural ceramic fibers by physical vapor deposition, sputtering, etc., followed by consolidation (e.g. hot isostatic pressing) offers an attractive route for the manufacture of continuous fiber-reinforced metal matrix composites (MMC's). Recent models for describing the evolution of key microstructural features (such as porosity, interfacial reaction zone thickness and fiber microbendinglfracture) during consolidation are described, and are combined to simulate changes in the composite's microstructural "state" during arbitrary consolidation process schedules. Results are presented for PVD Ti-6AI-4V -coated SiC monofilament fibers consolidated by vacuum hot pressing which illustrate the presence of optimal solutions to the process path planning problem. An optimization scheme is briefly described which allows identification of the consolidation process cycle providing maximum relative density with minimum fiber and interfacial damage. In addition to the process schedule, optimal quality is shown to depend strongly on the fiber/matrix combination, the initial coated fiber packing geometry and the (evolving) matrix microstructural state.
MMC powders of Al-Li-Cu-Mg-Zr alloy base with variable amount SiC short filamentary reinforcement were produced in a pilot plant down-draught atomizer with a Mannessman type nozzle under Ar. Powder based alloy matrix composite powders were ground in a mechanical alloying attritor not only for introducing deformation but also to investigate the influence of this new and unique processing route on the microstructure and properties of the material system under investigation.
9:25am SYNTHESIS OFNANOSTRUCTURED SiC/Si3N. COMPOSITE POWDERS THROUGH REACTION MILLING: Z.-G. Yang, L. Shaw, Department of Metallurgy and Materials Engineering, University of Connecticut, Storrs, CT 06269 In this study, synthesis of SiC/Si3N. nanocomposite powders through reaction milling was investigated. Graphite and silicon powders were used as the source of carbon and silicon respectively, while the source of nitrogen was from either nitrogen or ammonia gases. Various compositions of the starting powder mixtures for forming nanopowders spanning from pure SiC to pure Si3N. were investigated. It was found that nanocrystalline SiC powders could be synthesized at ambient temperature by milling silicon and graphite powders in argon atmosphere. However, the formation of SiC was retarded when milling was conducted in nitrogen or ammonia atmosphere. Crystalline Si3N.
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11:20 am MODEL-BASED SIMULATION OF THE CONSOLIDATION PROCESSING: R.Vancheeswaran, H. N. G. Wadley, Intelligent Processing of Materials Laboratory, Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22903
ALUMINA & BAUXITE TECHNOLOGY III Sponsored by: LMD Aluminum Committee Program Organizer: F. S. Williams, Alcoa Alumina & Chemicals 1.1.C., Point Comfort, TX 77978-0101
The performance of fiber reinforced titanium matrix composites (TMC) made by consolidation of spray deposited monotapes is strongly influenced by the processing conditions used. This high temperature consolidation step must simultaneously minimize fiber microbending/fracture, the interfacial reaction product layers at the fiber-matrix interface and at the same time eliminate matrix voids (i.e. increase the relative density). These three microstructural variables have conflicting dependencies upon the consolidation process variables (temperature, pressure and time), and it has been difficult to identify process pathways by trial and error that lead to composites of acceptable quality (where the fiber damage and reaction layer thickness are kept below some bounds. while matrix porosity is eliminated). Models for predicting the microstructure's dependence upon process conditions (i.e. the time varying temperature and pressure) are combined with consolidation equipment dynamics to simulate the microstructure evolution and to assess the relative "process ability" of several silicon carbide fiber/titanium alloy matrix systems during their consolidation. We introduce the idea of process failure surfaces and show how this simulation tool in conjunction with a model predictive control (algorithm), is able to design "locally" optimal process cycles that minimize fiber damage, reaction product layer thickness and porosity. The approach is then used to path plan process schedules that will steer away from these damage surfaces for a variety ofTMC systems.
Wednesday, AM February 11, 1997
Room: 230D Location: Orlando Convention Center
Session Chairman: David Riner, Reynolds Metals Co., PO Box 9911, Corpus Christi, TX 78469
8:30am OPTIMIZATION OF ALUMINA PLANT OPERATION WITH RESPECT TO MARKET CONDITION: P. Das, National Aluminium Company Ltd., Damanjodi, Dist. Koraput, Orissa 763008, India In international markets, wide fluctuations of alumina prices have been found to be a common phenomenon over the years. It has been observed that almost all the buoyant cycles have essentially been followed by recessionary market conditions. Hence, during the periods when alumina prices are relatively low, for survival it becomes obligatory on the part of the management to strike an operational philosophy suitable for achieving minimum cost of production. However, during buoyant market conditions it is wise to make attempts for maximization of production by suitable optimization of process parameters even if there is a marginal increase in unit cost of production. Since such attempts are directly related to the profitability of the organization, a careful study should be made taking into consideration all interrelated factors. This paper highlights the areas of an alumina plant where changes in process parameters, permissible on technoeconomic consideration, could be made for optimization of production and profitability.
11:45 am STUDIES ON SINTERED ZIRCON-REINFORCED ALUMINUM ALLOY MATRIX COMPOSITES: 1. U. Ejiofor, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487; B.A. Okorie, Department of Metallurgical and Materials Engineering, Enugu State University of Technology, P.M.B. 01660, Enugu, Nigeria; and R. G. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487
8:55 am DEVELOPMENT OF SOFTWARE FOR BAYER PROCESS ALUMINA PLANTS: C. Misra, V. Soi, Alumina Technology Associates, 714 Pine Valley Drive, Pittsburgh, PA 15239
Zircon, ZrSi04 , is a thermally stable mineral. Owing to its abundance, high hardness, excellent abrasion/wear resistance and low coefficient of thermal expansion, researchers are investigating its use for medium strength, tribological applications. In the present study, the conventional low-cost, double compaction powder metallurgy route in the synthesis of AI-13.5Si-2.5 Mg alloy(wt%) reinforced with ZrSi04 , was investigated. The mechanical, physical and tribological properties were determined following the development of optimum conditions of compaction and sintering. At 0.15Vf , the UTS, 0.2% YS. and hardness improved by 4%, 12.8% and 88% respectively while the adhesive wear rate and the coefficient of friction reduced by 99.55 and 35.5% respectively. At a critical volume fraction of zircon, between 0.03 and 0.05, a significant improvement in wear resistance was observed. The use of optical microscopy, EPMA, SEM and x-ray analysis revealed the phases and possible reactions at the matrix-reinforcement interface, fracture mode and compositions of fractured surfaces which are related to measured mechanical properties and, the influence of the reinforcement phase on wear rate. Further structural analysis showed that the improvement in mechanical properties is attributed largely to the load-bearing ability and intrinsic hardness of zircon than to particulate dispersion effects. An attempt was made to model the strength of the composites.
PC based software packages have been developed to assist in the operation and management of Bayer process alumina plants. Software packages for digestion, residue washing and precipitation areas have been designed for use by plant operators to formulate operating policy and are integrated with existing or new process control systems. As example, important features and structure of software developed for the precipitation system are discussed in more detail.
9:20am DYNAMIC MODELING OF YIELD AND PARTICLE SIZE DISTRIBUTION IN CONTINUOUS BAYER PRECIPITATION: Jerry L. Stephenson, Alcoa Technical Center, 100 Technical Drive, Alcoa Center, PA 15069; Chris Kapraun, Alcoa Alumina & Chemicals, L.L.c., Point Comfort Operations, State Highway 35, Point Comfort, TX 77978 Process engineers at Alcoa's Point Comfort refinery are using a dynamic model of the Bayer precipitation area to evaluate options in operating strategies. The dynamic simulator, a joint development effort between Point Comfort and Alcoa Technical Center, predicts process yield, particle size distributions, and occluded soda for a given flowsheet of the precipitation and classification circuit. In addition to rigorous material and particle population balances, the model includes mechanistic kinetic expressions for particle growth, agglomeration, nucleation, and attrition. The kinetic parameters have been tuned to Point Comfort's data with excellent matches between the model results and plant data. The model is written for the ACSL package with specially developed input/output graphical user interfaces which provide a user-friendly tool. Features such as a seed charge controller enhance the model's usefulness for evaluating operating conditions and process control approaches.
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9:55am INCREASING THE ACTIVITY OF SEED USED FOR PRECIPITATION OF THE SODIUM-ALUMINATE LIQUOR: Bi Shiwen, Yang Yihong, Fu Gaofeng, Wen Jie, Ju Aihua, Department of Nonferrous Metallurgy, Northeastern University, Shenyang, 110006, China
plains cathodic overvoltage, the sodium content of the aluminum, current efficiency and the relationship of each to metal pad stability (magneto-hydrodynamic stability). 8:55 am ON THE COMPOSITION OF SOLID DEPOSITS FROZEN OUT FROM CRYOLITIC MELTS: Asbj¢rn Solheim, Lisbet I. R. St¢en, SINTEF Materials Technology, N-7034 Trondheim, Norway
The activity of seed is one of the most important factors in the precipitation of the sodium-aluminate liquor. The industrial aluminum-oxide-hydrate is treated with sulfuric acid to increase its activity, and then it is used as the seed of precipitation. It is demonstrated that the seed has the ability to increase the rate of precipitation. The reason of this phenomenon is analyzed.
Thermodynamically, the primary crystallization product formed by cooling a melt containing cryolite, AlF3, AlP3 and CaF2 is expected to be cryolite with minor amounts of CaF2 and AIF3 in solid solution. In practice, however, any deposit frozen out from such melts may contain considerable amounts of bath constituents other than cryolite. The factors governing the composition of the freeze are studied theoretically and by experiment. Besides solid solution, the composition depends on two factors, 1) diffusion of bath constituents from the surface of the deposit towards the bulk of the melt, and 2) dendritic crystal growth with subsequent trapping of bath between the crystals. The condition which gives dendrite formation is formulated. Based on this criterion, a deposit frozen out from melts containing excess AIF3and alumina would contain more AlF3 than a deposit frozen out from a melt containing excess AlF3 alone. This was confirmed by experiment.
10:10 am BREAK 10:30am SECONDARY NUCLEATION OF ALUMINUM TRIHYDROXIDE IN BAYER SODIUM ALUMINATE SOLUTION: Xue Hong, Bi Shiwen, Shuai Shiwu, Van Yihong, Li Dianfeng, Department of Nonferrous Metallurgy, Northeastern University, China; Chen Wankun, The Great Wall Aluminum Company of China In this paper, secondary nucleation of aluminum trihydroxide in Bayer sodium aluminate solution was discussed by picture analysis and scanning electron micrograph. The effects of temperature, seed size and aluminate concentration on secondary nucleation are determined with growth time. As this study has shown, the nucleation rate depends upon the experimental conditions of supersaturation, temperature and seed size or surface area. The nucleation can promote the formation of relatively large particles under an opportune condition.
9:20am THE GAS UNDER ANODES IN SMELTING CELLS. Part I: MEASURING AND MODELLING BUBBLE RESISTANCE UNDER HORIZONTALDE-ORIENTED ELECTRODES: T. M. Hyde, B. 1. Welch, Department of Chemical Engineering, University of Auckland, New Zealand With a continuing drive to reduce energy and the tighter operating tolerances of modern aluminium smelting cells, there is an ever increasing need for a precise cell voltage equation. Precise correlation exists for the electrical conductivity in smelting cells, the reverse is not the case for the added resistance effect of gas bubbles. Where it has been allowed for, the models used have been based on those proposed for vertically oriented electrodes. Furthermore the measurements on which the model is based can be influenced by other electrochemical changes while the shape and dispersion and gas bubble differ from those expected in aluminium smelting cells based on model studies. An apparatus and high speed switching data acquisition technique have been developed to allow the ohmic resistance of a molten salt electrolyte to be isolated from all other contributors. Ceramic objects of known geometry, size and volume, rest in the electrolyte immediately under the upper electrode (anode) thus simulating gas bubbles. The technique developed enables the measurement of the direct increase in resistance due to the introduced volume of non-conducting simulated gas. The bubble parameters examined included volume, electrode coverage, depth and shape. The resulting data have been tested against existing models.
10:55am BAYERITE - ALUMINIUM TRIHYDROXIDE: Maurycy M. Pyzalski, Technical University of Mining and Metallurgy, Faculty of Ceramics and Material Engineering, Ave. Micklewicz 30, A-3, 30 - 059 Cracow, Poland The physico-chemical properties of Bayerite, which was obtained in semicommercial scale using new technology, were investigated in detail. The properties of another polymorphic form of aluminum trihydroxide, i.e., hydrargillite (Gibbsite) obtained by means of Bayer's and Grzymek's methods were also evaluated in a similar way. The results thus obtained allow characterization of the properties of hydroxides. They also put a new light on their formation and polymorphism.
ALUMINIUM REDUCTION TECHNOLOGY V: Fundamentals Sponsored by: LMD Aluminum Committee Program Organizer: Harald A. 0ye, Institute of Inorganic Chemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway
Wednesday, AM February 12, 1997
9:45am THE GAS UNDER ANODES IN SMELTING CELLS. Part II: GAS VOLUME AND BUBBLE LAYER CHARACTERISTICS: R. Aaberg, V. Ranum, The Norwegian University of Science and Technology, 7034 Trondheim, Norway; K. Williamson, B. J. Welch, Department of Chemical & Materials Engineering, The University of Auckland, New Zealand
Room: 230A Location: Orlando Convention Center
Session Chairperson: Jeff Keniry, Comalco Research, 15 Edgars Road, Thomastown, VIC 3074, Australia
Recent physical models have suggested that the gas bubbles formed under anodes in smelting cells tend to coalesce and release as large bubbles predominantly. Whilst it is well established that the gas bubbles increase the cell resistance, and correlations proposed include the gas volume or bubble layer depth and surface coverage. However, the volume and degree of coverage of the electrodes have been subject to speculation rather than accurate measurements. In this investigation, using a larger than normal laboratory cell, it has been confirmed that the gas released is consistent with the physical models with most of the gas being evolved in discreet large bubbles. The release frequency is similar to the dominant frequency found in operating cells. The average gas volume under an anode prior to release is between 0.4 and 0.5 cm3per cm2 of electrode. From combined resistance studies it has been calculated that approximately two thirds of the anode is covered with gas at release with an average bubble thickness of 5 mm.
8:30am UNDERSTANDING BOUNDARY-LAYERS: Warren Haupin, 2820 Seventh Street Road, Lower Burrell, PA 15068 Understanding the physics and chemistry of boundary-layers, the thin stagnant zones that form at each bath interface, clarifies many cell phenomena. A non-wetting boundary at the anode causes the anode effect. The effect of bath velocity on the boundary-layer thickness and its effect on the heat transfer coefficient coupled with bath temperature and bath composition explains the formation and loss of frozen ledge and its relationship to heat losses from the cell walls. Similarly, the boundary-layer at the bath-aluminum interface ex-
10:10 am BREAK
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10:30 am
Examples of some of the measurements made with these systems will be presented.
MICROPYRETICALLY SYNTHESIZED POROUS NON-CONSUMABLE ANODES IN THE Ni-Fe-Cu-AI SYSTEM: J. A. Sekhar, H. Deng, J. Liu, International Center for Micropyretics, Department of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45221-00 12; Y. de Nora, MOLTECH S.A., 9, Route de Troinex, 1227 Carouge, Geneva, Switzerland
APPLICATIONS OF SENSORS AND MODELING TO MATERIALS PROCESSING· V
A micropyretically synthesised porous Ni-Fe-Cu-Al intermetallic composite electrode has been developed for use as a non-consumable anode in the Hall Heroult cell. The oxidation behavior in air and under electrolysis conditions have been studied. The electrode is noted to be resistant to the corrosive conditions encountered during electrolysis for up to 300 hour tests in 10 Amp and 100 Amp cells. The synthesis procedures for the manufacture of the electrodes and the beneficial influence of the pores are discussed. Preliminary results on the metal contamination during electrolysis are also presented.
Sponsored by: Jt. EPDIMDMD SyntheSiS, Control, and Analysis in Materials Processing Committee and EPD Process Fundamentals Committee Program Organizers: S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; R.G. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487; J.C. Malas, Wright-Patterson AFB, OH 45433-6533; L.L. Shaw, Dept. of Metallurgy & Materials Science, Univ. of Connecticut, Storrs, CT 06269-3136; R. Abbaschian, P.O. Box 116400, 132 Rhines Hall, Univ. of Florida, Gainesville, FL 32611-6400
10:55 am
Wednesday, AM February 12, 1997
APPLICATION OF NONEQUILIBRIUM THERMODYNAMICS TO THE LEDGE SURFACE OF ALUMINIUM ELECTROLYSIS CELLS: Ellen Marie Hansen, Signe Kjelstrup, Department of Physical Chemistry, The Norwegian University of Science and Technology, N-7034 Trondheim, Norway
Room: 232A Location: Orlando Convention Center
Session Chairs: J.M. Toguri, Dept of Metallurgy and Materials Science, Univ of Toronto, 184 College Street, Toronto, Ontario, Canada, M5S 1A4; U. Pal, Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Room 4-134, Cambridge, MA 02139
Nonequilibrium thermodynamics for surfaces has been applied to the interface ledge - electrolyte in aluminium electrolysis cells. The method describes the interface as a layer of finite thickness 0, having a bath-like part and a ledge-like part, with properties differing from the bulk properties. The method can explain the heat transfer coefficient for the interface in a new way, namely as a combination of the thermal conductivities in the two parts of the interface. Examples are given to show how the temperature ')ump" between the two bulk phases may either be located in the ledge-like part of the interface, in the bath-like part, or in both. In analysis of ledge growth, the possibility of different surface temperatures should be taken into account, because this temperature may, together with the temperatures close to the interface on both sides, determine the rate of freezing or melting. It is also shown how the simple steady state model can be expanded into a dynamic one.
8:30am MEASUREMENT OF GAS COMPOSITIONS USING SOLID ELECTROLYTES: R.Y. Kumar, D.J. Fray, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, United Kingdom Sensors are required to measure gaseous species such as SOx' NOx, HCl, and water vapour at elevated temperatures. There are very few solid electrolytes which respond to these gases, and furthermore, the species are usually present with other gases to which the electrolyte may respond. In addition, for long periods of operation, a stable reference is required. In order to meet these challenges, sensors consisting of two electrolytes in intimate contact have been developed. To measure HCl, a proton-conducting electrolyte is interfaced with strontium chloride. The reaction for the cell: (-) Pt, Air + HCl(g»)/ SrClj/SrCe0 3 + 10 mole % Ndpp Air + HCl(g)' Pt( +). At the various interfaces, the reactions are: anode: 2CI- + SrHCI = SrCl, + HCI(g) + 2e-interface: 2H+ + 2Cl- = 2HCI(interface) cathode: HC\inte"ace) + srClz + 2e- = SrHCl + 2CI- overall cell reaction: HCl(in«"..,.) =HCl(g). The net result is that the potential is independent of the oxygen potential of the gas and the reference is given by the interaction of the two electrolytes. There is no need for an external reference which overcomes the problems of forming gas thigh seals at elevated temperatures. Other examples of this approach for the measurement of SOx, NOx, CO" and Hp will be given.
11:20 am PHYSICO-CHEMICAL PROPERTIES OF Na 3AIF6-AIF3-LiF-CaF, SYSTEM UNDER THE SAME SOLVABILITY OF AI,03: Li Dexiang, Chen Jianshe, Li Guohua, Department of Nonferrous Metallurgy, Northeastern University, Shenyang, 110006, China; Ma Xiufang, Beijing Nonferrous Metal Research Institute, Beijing, China The concept of properties of electrolyte melts under the same solvability of alumina at nonequal temperature, that is, the properties of melts under equal solvability of alumina dissolving in the electrolyte at the temperature which is 20°C above the liquidus, were put forward. Based on this theory, the physicochemical properties, such as the initial crystallization temperature, solvability of alumina, conductivity, density of (2.23-3.0) NaP·AlF3- (0-5%) LiF - (015 %) CaP, system were studied. The results will provide more scientific basis for choosing the optimum electrolyte composition in aluminium electrolysis.
8:55am DEVELOPMENT AND APPLICATION OF OXYGEN SENSORS IN COPPER METALLURGY: S. Seetharaman, Du Sichen, A. Jakobsson, Division of Theoretical Metallurgy, Royal Institute of Technology, S-I00 44 Stockholm, Sweden
11:45 am
Oxygen concentration cells with stabilized zirconia electrolytes are widely used today to measure the activity of oxygen in liquid metals. In the case of liquid copper, the activity of oxygen in the molten metal as well as the effect of a third element on the same have been extensively studied using galvanic cells of the type (-) Pt, W orcermetlCu-O-M/!Zr02 (stabilized)/! AO, A/Pt (+, where M is the third element in molten copper and AO / A represents a suitable oxide/metal reference electrode. The effect of a number of "third elements" like Mn, Zn, As, Se, and Te on the oxygen activity in liquid copper have been studied by this method. The Mn and Zn interact very strongly with oxygen in Cu ( ), while, in the case of arsenic, the interaction parameter is nearly zero. The behavior of Se and Te in liquid copper with respect to the effect on the activity of oxygen is unique. At oxygen levels of the order of 10" these elements lower the activity coefficient of oxygen in the melt, while, at lower oxygen levels, the interaction parameter values are positive. These results are discussed in the light of some of the theoretical models for solute interactions in liquid metals. The application of these sensors in flash smelt-
MEASUREMENTS OF HF IN STACKS AND POT ROOMS USING A REMOTE SENSING EYE-SAFE LASER INSTRUMENT: H.I. Schiff, Unisearch Associates, Inc., 222 Suidercroft Rd., Concord, Ontario, Canada
UK 185 A remote sensing system for continuous measurement of HF and other gases has been developed based on eye-safe turnable gases. The laser, its controls and data acquisition system are contained in a small instrument which can be located anywhere in the plant, such as the control room. The optical beam is transported to one or more stacks or ducts by fibre optics which may be kilometres in length. It is then directed across the stack and returned by a retroreflector to the same optical fibre and retroreflector combination for potroom or roof-top monitoring. The use of optical multiplexing permits a single instrument to make simultaneous measurements at a number of locations providing a very cost effective system which can operate in any environment. Systems have been installed in four Canadian smelters and one in the UK.
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ing, converter, and casting sections of copper production are discussed along with their implications on process optimization.
10:45 am NOVEL SOLID STATE SENSOR FOR MEASURING ARSENIC IN MOLTEN METALS: G.M. Kale, Dept of Mining and Mineral Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom; D.l. Fray, Dept. of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3 QZ, United Kingdom
9:20am APPLICATION OF RAMAN SPECTROSCOPY TO HIGH-TEMPERATURE ANALYTICAL MEASUREMENTS. l.P. Young, S, Dai, Y. Lee, H. Xiao, Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6142
A novel solid state sensor for measuring arsenic dissolved in molten metals has been developed based on a novel solid electrolyte conducting K+ ions. The solid state sensor can be schematically represented as: (-)Mo, Zn-Asl /K323 SEI /K-~Fez03+Fez03+02' Fe-Cr(+). The open circuit emf of the above sensor was measured in molten zinc containing less than 0.1 wt % As at a temperature of 823K. The emf of the sensor was found to vary linearly as a function of InX As ' where XAs is the mole fraction of As in An(l). The ionic conductivity of the novel solid electrolyte (K-323) was measured over a range of temperature (370
There are numerous analytical applications of scatter--emission and absorption spectroscopy to liquids and solids in the temperature range of 0° to 350°C; process control is made impossible by using fiberoptic probes and Raman spectroscopy, for example, in these measurements. We have developed a unique all-silica fiberoptic probe which can have analytical applications in the temperature range where silica is a solid, 0° to 1600°C, and in chemical situations where it is inert. We have also developed techniques to use the ratio of the Stokes/anti-Stokes Raman emission of diamond to measure temperature in the range of 400 to lOOO°C. We will discuss our results of such measurements in molten chloride and fluoride salts, other liquids, and solids. We will also describe our plans for temperature measurements by Raman spectroscopy through optical fibers in the range of 1000 to 2500°C, a range that can include molten metals such as steel.
11:10 am MEASUREMENT OF NITROGEN AND SULPHUR IN MOLTEN METALS USING SOLID ELECTROLYTES: Y.c. Avniel, T.E. Warner, D.1. Fray, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, United Kingdom
9:45am SOLID STATE CURRENT-POTENTIAL SWEEP SENSOR FOR THE IN-SITU MONITORING OF COMPOSITION AND TRANSPORT PROPERTIES IN HIGH TEMPERATURE METALLURGICAL SLAGS: S.C. Britten, V. Stancovski, U. Pal, Dept of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 4-134, Cambridge, MA 02139
One of the major problems of the iron and steel industry is the presence of phosphorus, sulphur, nitrogen, and silicon. Careful control and removal of these elements is required, and an on-line measurement of the concentration during removal would greatly improve the efficiency of the process. The oxygen content of molten metals is usually measured by using a sensor based upon stabilized zirconia, in which the oxygen ion is mobile. However, for nitrogen and sulphur, stable ionically conducting solid electrolytes for nitrogen and sulphur do not exist. The approach adopted in this work is to use electrolytes which conduct alkali and alkaline earth elements. For example, when a sodium ion conducting electrolyte is placed in a situation where sodium is not present, the sodium comes to equilibrium with the species which forms the most stable compound with sodium. Examples are given where sodium, strontium, and calcium beta alumina respond to sulphur and oxygen. R~gions of response to a given species depend upon the concentration of other species in the melt and the standard free energy of formation of the various compounds. In the case of nitrogen measurement, it proved necessary to develop a new electrolyte, based upon rare earth oxides, in which nitrogen is soluble in the anion lattice. Results are presented for the measurement of sulphur and nitrogen partial pressures and for these species in molten iron and steel.
An in-situ solid-state electrochemical technique for measuring the concentrations of easily dissociable oxides in slags at temperatures between 1200 to 16oo°C is being developed. The technique consists of using a stabilized zirconia solid electrolyte, which conducts oxygen ions, to separate a reference gas compartment from the slag of interest. Using a potentiostat, a direct current potential sweep is applied between the inner and outer compartments of the electrolyte, driving oxygen ions from the slag into a reference gas. With the use of open circuit reference electrodes, the resulting magnitude of the current potential profile reveals the concentration of dissociable oxides such as those of iron, manganese, and chromium. The open circuit potential recovery indicates the type of oxide present and its thermodynamic activity within the slag. The technique should therefore determine multiple properties of several different oxides with only one measurement. The limits imposed by the electronic short-circuit property of the zirconia electrolyte on the sensitivity of the technique are also under investigation. 10:10 am BREAK 10:20am APPLICATIONS OF SENSORS IN MOLTEN SALT TECHNOLOGY FOR METAL PROCESSING: P.T. Velu, R.G. Reddy, Dept of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487 The use of emf measurements to derive classical thermochemical data has been in use for many years. The reaction associated with electrochemical process is harnessed in a galvanic cell and energy involved measured in terms of electromotive force. The property requirements of sensor electrodes used differ for various aqueous, molten salt, and solid electrolyte systems. The electrodes for molten salt electrolytes need special care for construction. This paper describes the studies carried using an AgIAgCI reference electrode. This electrode was used to measure the solubility of compounds in molten salt electrolytes. The results obtained using this electrode are in excellent agreement with the values from chemical analysis method.
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9:20am A NOVEL ELECTROMETALLURGICAL PROCESS FOR THE TREATMENT OF REFRACTORY GOLD CONCENTRATES: N. de Jager, MJ. Nicol, University of the Witwatersrand, School of Process and Materials Engineering, Johannesburg, South Africa
AQUEOUS ELECTROTECHNOLOGIES: PROGRESS IN THEORY AND PRACTICE: New Processes and Products
In order to liberate gold from refractory gold ores and concentrates it is necessary to oxidize the surrounding sulphide minerals, typically pyrite and arsenopyrite. Traditional methods of oxidation include pressure leaching, roasting and bacterial oxidation. In recent years, bacterial oxidation has found increasing favour, although it is by no means completely satisfactory and is subject to large residence times. It is also extremely sensitive to operating conditions. Similarly, pressure leaching and roasting have their own particular disadvantages. A novel process has been developed as an alternative to the traditional methods whereby electro-generated ferrate [iron (VI)] ions in alkaline solution are used to oxidize a pyrite concentrate. This process has been observed to proceed fairly rapidly and could prove to be a more economically viable process, as well as being more environmentally acceptable. As an added benefit, operating in an alkaline environment is advantageous for downstream cyanidation processes. Iron (VI) is a relatively unknown species, due mainly to its instability in acidic solutions. However in alkaline solution it has been observed to be sufficiently stable for use as an oxidant when kept under the correct conditions. Iron (VI) is most conveniently manufactured electrolytically via the dissolution of high-carbon iron anodes in strongly alkaline solutions. Some literature has been published on the electrolytic generation of iron (VI) and relatively high efficiencies have been observed by both the authors and other researchers. This study utilizes both electrochemical techniques and leaching experiments to examine the kinetics and mechanism of the oxidation of pyrite by iron (VI). Cyclic voltarnmetry, rotating disk voltammetry and potential step experiments have been used to investigate the mechanism and kinetics of the oxidation process. Other potentiodynamic and poteniostatic techniques have also been employed. Leaching experiments have been used to provide a more detailed investigation into the kinetics ofthe process.
Sponsored by: EPD Aqueous Processing Committee, Copper, Nickel, Cobalt Committee, Lead, Zinc, Tin Committee and Precious Metals Committee Program Organizers: D.B. Dreisinger, University of British Columbia, Department of Metals and Materials Engineering, 309-6350 Stores Road, Vancouver, B.C., Canada; E. Ozberk, Sherrill International, Bag 1000, Fort Saskatchewan, AB, T8l 2P2; Mrs. S. Young, BHP Copper Inc., 2400 Oracle Road, Suite 200, Tucson, AZ. 85704; Dr. R.S. Kunter, Advanced Sciences Inc., 405 Urban Street, Suite 401, Lakewood, CO, 80228
Wednesday, AM February 12, 1997
Room: 231A location: Orlando Convention Center
Session Chairperson: D.B. Dreisinger, University of British Columbia, Department of Metals and Materials Engineering, 309-6350 Stores Road, Vancouver, B.C., Canada
8:30am INDUSTRIAL IN-PULP Co-Ni ALLOY ELECTRO-WINNING AT THE GECAMINES·SHITURU PLANT: K. Twite, J.-M. Dereydt, K. Mujinga, Gecamines Shituru PlantILikasi, Bd. du Souverain 30, 32, BIl70 Brussels, Belgium; P. Louis, Union Miniere, Allee de la Frenaie, B 1300 Wavre, Belgium GECAMINES is a large mining concern and the world's leading cobalt producer having some of the richest cobalt deposits in the world. Cobalt is associated in the ore with copper as sulphides and oxides and in some locations with nickel too. Specific hydrometallurgical processes have been developed by GECAMINES which had done an important contribution to the development of the cobalt hydrometallurgy. In the Shituru plant, cobalt is obtained from an unique in-pulp electrolysis process, while in Luilu, cobalt is electrolyzed in a clear acidic solution giving a purer deposit. In the beginning of 1996 Shituru started the treatment of mixed Cu-Co-Ni Shinkolobwe hydrates obtained as by-product of an uranium solvent extraction plant. A typical analysis of this feedstock is: Cu: 2%, Co: 8%, Ni: 4%. The nickel sulfide depolarized cementation process developed previously by GECAMINES was inefficient to treat such a high level of Nickel contamination and it was decided to produce alloyed Cobalt-Nickel cathodes in the Shituru tankhouse. As anticipated from laboratory tests as previous studies and publications, a lower Nil Co in the deposit was obtained compared to the NilCo ratio solution, despite the nickel reversible electrochemical potential is somewhat higher than the one of cobalt (-0.25 V vs -0.28 V). In this paper, the process flow-sheet and production data are given. Cobalt alloy with 5 - 20 % Ni was obtained at a production level of 300 t per month. The process developed is a first industrial realization in this way, bringing a new contribution to cobalt hydrometallurgy.
9:45am ELECTROLYTIC RECOVERY OF MERCURY FROM LOW CON· CENTRATION BRINE SOLUTIONS: M. Rockandel, Universal Dynamics Ltd., Vancouver, Canada Universal Dynamics Ltd. of Vancouver, Canada has developed, patented and commercialized the "REMERC" process for the treatment of mercury contaminated sludges and soils. Mercury is extracted into an acidified and oxidizing, sodium chloride brine solution. REMERC was initially developed to treat mercury contaminated EPA listed wastes (KI06) generated by the chloralkali industry. More recent work has expanded the capability of REMERC to include remediation of mercury contaminated sites, equipment and building materials. In the process mercury is currently recovered from solution by cementation on iron powder in an agitated reactor. The process recovers high purity elemental mercury (99.9% purity). Cementation typically recovers about 90-95% of the mercury in 30 minutes. Higher recovery is not necessary because of the recirculation of the leach solution. When treating highly contaminated chloralkali wastes (5-13% mercury content), REMERC will reduce the mercury laden solutions from 400-1,000 mg/l mercury to 50-100 mg/l. In the treatment of less concentrated wastes «1,000 mglkg mercury) such as those encountered in site remediation, the treated solutions will generally contain 10-20 mg/l mercury. Cementation while being simple and able to achieve the required recovery has the undesirable properties of; requiring a solid-liquid separation and adding iron to solution which must be precipitated, ultimately increasing the weight of residue to landfill. The potential advantages of electrolysis were recognized early in the development of REMERC. Mercury electrolysis is well known in gold and chloralkali processing. Initial testwork utilized a liquid mercury cathode and a coated titanium anode both common to chloralkali producers. The mercury cathode appeared susceptible to polarization and solution impurities significantly affected performance. Agitation of the mercury pool improved performance but it was still not possible to achieve the reduction objectives. Current efficiencies were low, near 10%, and it was apparent that a relatively large cathode pool would be required to limit the current density. A number of electrode combinations with and without a membrane were then tested in a vertical electrode configuration but the desired performance was not obtained. In 1995 Universal Dynamics working with Dremco Ltd. of Arizona, USA
8:55am ELECTROLYTIC PROCESSING OF MANGANIFEROUS SILVER ORES IN ACIDIC NITRATE MEDIUM: O. Rutten, S. Van Sandwijk, G. Van Weert, Department of Raw Materials Technology, Delft University of Technology, Mijnbouwstraat 120, 2628 RX Delft, The Netherlands Cathodic and anodic reactions in the acidic nitrate medium were studied in reference to the electrolytic production of manganese dioxide from pyrolusite (MnO z) ores by reductive leaching. Two USA ores were investigated. The reductant for MnO z is produced cathodically and can either be nitrous acid or nitrogen oxide gas. In this work emphasis was placed on the nitrous acid leach. Manganese and silver are solubilized, iron is not. Cathodic regneration of nitrous acid was investigated in the range of 0.5 to 3.0 M nitric acid, 0.0 to 0.1 nitrous acid on graphite, platinum and platinized titanium cathodes at 20 to 80°C. It was established that the formation of the nitrosyl ion (NO+) is a prerequisite for the cathodic reduction of nitric acid. At cathode potentials < +700 mV (SHE), cathodic reduction of nitrous acid to nitric oxide takes place. Anodic deposition of manganese is as flaky .f.J-MnOz, similar to that produced in sulphate electrolytes. A conceptual flowsheet is presented and discussed.
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11:20 am
began the development of a plate and frame style electrolytic cell. The objective of the electrolytic process was to achieve similar removals to those obtained by cementation, while producing high purity elemental mercury (>99.9% purity) and chlorine at the anode. Although current efficiency is a relatively minor concern the design objective was to achieve at least 50% CEo The current efficiency goal would require operation of the cell at current densities approaching the limiting current flow. The final cell current densities would therefore be in the range of 0.1 - 1.0 Aim'. Operation of a laboratory scale cell has demonstrated that the operating objectives can be achieved with a cell consisting of closely spaced shiny titanium cathodes and ruthenium oxide coated titanium anodes. Numerous variables were observed to be important including; inter electrode velocity, current density, pH and chlorine stripping. The cell has been tested on solutions generated by two REMERC operations, solution produced during site remediation pilot testing and on more highly concentrated solutions generated by oxidation of calomel generated at Cominco Metals, Norzink facility in Trail, B.C.
ACID RECOVERY AND PURIFICATION USING ABSORPTION RESIN TECHNOLOGY: M. Sheedy, Prosep Technologies Inc., Pickering, Ontario, Canada Strong mineral acids, principally sulphuric, are widely used as electrolytes for the electrorefining and electrowinning of metals. Impurities in these electrolytes are controlled by continuously bleeding solution form the tank house. In addition to the contaminant these bleed streams contain high levels of sulphuric acid and the metal being recovered. Subsequent treatment of these bleed streams often requires neutralization which generates large volumes of solid waste. Absorption resin technology employing a novel ion exchange technique known as Recoflo allows the separation of the mineral acid from dissolved metal salts. The recovered acid is suitable for recycle back to the electrolyte circuit. The metal salt and other contaminants leave the process free of sulphuric acid. In this process, known commercially as the APU, ion exchange resin is used to sorb sulphuric acid while excluding the metal salts. The purified acid is then removed by washing the resin with water. The process has been extensively used for the recovery of waste pickling acids in the steel industry and anodizing solutions in the aluminum industry. In the mining industry the process has been successfully evaluated for the separation of excess sulphuric acid from copper electrolytes, the removal of magnesium and manganese contaminants from zinc electrolytes, and antimony, bismuth and nickel from copper electrolytes.
10:10 am BREAK 10:30am RECOVERY OF Cu'+ AND Cd'+ FROM DILUTE AQUEOUS SOLUTIONS BY ION FLOTATION AND ELECTROLYSIS: EM. Doyle, University of California at Berkeley, Department of Materials Science and MineraI Engineering, Berkeley, CA 94720-1760; K. Sreenivasarao, Argonne National Laboratory, Energy Systems Division, Argonne, IL 60439
11:45 am ELECTRODEPOSITION OF THIN MULTILAYER MAGNETIC MATERIALS: Z. Liu, K.c. Liddell, Washington State University, Department of Chemical Engineering, Pullman, WA 99164-2710
Copper and cadmium metal has been recovered from dilute (3 X 104 moll dm3 ) chloride solutions by ion flotation with dodecysulfate, followed by electrolysis. This approach should facilitate treatment of effluents too dilute for effective direct electrolysis. The adsorption density of metal dodecylsulfate complexes on bubble surfaces was estimated from surface tension data, and compared well with experimentally-observed metal removal kinetics, and ultimate recoveries. Copper and cadmium were recovered by electrolyzing the foamate, using steel wool cathodes and a graphite anode. The stability constants of the copper and cadmium dodecysulfate complexes are estimated, and used to analyze the thermodynamics of electrolysis. Dodecysulfate was unaffected by the electrolysis process, and hence could be recycled to ion flotation. A conceptual flowsheet for an overall effluent-treatment process is presented.
High-quality multilayers exhibiting giant magnetoresistance have been made by electrodeposition. The thickness of the individual layers was varied by changing the duration of the deposition pulses. Smooth and adherent layers as thin as lA were made and characterized.
AUTOMOTIVE ALLOYS I: Fundamental Studies Sponsored by: LMD Aluminum Committee Program Organizers: Dr. Subodh K. Das, ARCO Aluminum, Inc., P. O. Box 32860, Louisville, KY 40232; Dr. George J. Kipouros, Technical UniverSity of Nova Scotia, Department of Mining and Metallurgical Engineering, P. O. Box 1000, Halifax, Nova Scotia, Canada B3J2X4
10:55am NITROX METALS CORPORATION'S PROCESS FOR DIRECT LEACHING OF COPPER CONCENTRATES: R.N. O'Brien, E. Peters, Vancouver, B.C., V6N 2Gl
Wednesday, AM February! 2, 1997
It has been discovered that copper concentrates can be leached in strong (4060%) sulfuric acid with air as the primary oxidant, if nitric acid is present as a catalyst. Chalcopyrite is rapidly decomposed at temperatures well below the boiling temperature of the lixiviant (l50C.) and the resulting copper and ferric salts are precipitated as CuSO. H,O or CuSO.3 H,D and FeH(SO.),4H,D. Other metal sulfides such as zinc, lead, nickel, etc. are also converted to sulfates that are nearly insoluble. Sulfur is partially converted to elemental and partially to sulfuric acid. Reduction products of nitric acid can be recovered from the distillate with good recovery. Conversion of as-received copper concentrates is largely complete in about 1 hour. A number of process flow sheets are possible, and one that utilizes existing solvent extraction and electrowinning technology is considered economically feasible. This flow sheet involves (a) separation of metal sulfates and unleachable residues from excess acid by centrifuge, (b) water leaching of salts with partial neutralization (with limestone) of excess acid, to a tenor of 10 g/l Cu'+, (c) solvent extraction of copper using one of the LIX reagents, and (d) precipitating most of the ferric iron from raffinate with more limestone, so that it can be used as recycled water in step (a). Gold and silver are retained in a water insoluble small volume residue also containing any elemental sulfur formed, while minor elements like arsenic, antimony, etc. are retained by the strong sulfuric acid that is centrifuged from solids in step (a). These can be removed from this solution using methods previously developed for the purification of copper electrorefining electrolytes.
Room:340A Location: Orlando Convention Center
Session Chairperson: Dr. Subodh K. Das, ARGO Aluminum, Inc., P. O. Box 32860, Louisville, KY 40232
8:30am PREDICTING THE FORMABILITY OF ALUMINUM AUTOBODY SHEET ALLOYS: J. Daniel Bryant, Tatsuhito Koya, Armand J. Beaudoin, Reynolds, Metals Corporate Research and Development, Fourth and Canal Streets, P.O. Box, 27003, Richmond, VA 23261 While aluminum alloys based on the Al-Si-Mg-Cu system are currently being used in the production of a number of automotive body panels, the continuing demands for improved formability in these alloys have led alloy developers to the study of novel compositions and processing practices. Predicting stamping performance for a wide range of alloy variants, however, remains a difficult problem. Uniaxial tension tests, while providing reproducible assessments of mechanical behavior, are performed in a strain state that is quite different from that encountered in most stamping operations. As such, more elaborate, and often and less reproducible, methods of assessment are often employed, such as limiting dome height measurements and the construction of forming limit curves. In the present work, we have analyzed the tensile behavior of a series candidate alloys and used these data to predict the forming limit curve over a range of strain states. Using a modified form of the Voce work-hardening model, a Marciniak-Kuczinski simulation has been constructed and used to predict the forming limit curve minimum (FLC o)'
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These predictions are then related to experimentally determined forming limit curve data for the candidate alloys. The comparison of predicted and measured forming limit curve data indicates that the model can be successfully used to predict mechanical behavior under a state of plane strain using uniaxial tensile data. The results of the model indicate that the slope of the workhardening curve, particularly at high strain values, is intimately related to the forming limit curve minimum. These correlations provide alloy developers with an inexpensive method of comparing the formability new alloy variants by more thoroughly exploiting the data concealed within the full uniaxial tensile curve.
failure occurs parallel or perpendicular to the principal stresses. In addition, the displacement control routine may have a large effect on the total elongation that can be expected during forming operations. Tests were performed to evaluate failure in aAA5083 base alloy, by the following methods: 1) uniaxial tension tests at a constant true strain rate were interrupted at 80%, 60,G, 40%. and 5% of the maximum load, and microstructurally evaluated to identify the failure path and 2) tests were 'performed with various displacement control routines, and the elongation to failure was measured. The following displacement routines were used: smooth test, two-step strain test, multi-bump strain rate tests with various sizes of bumps scheduled at various intervals, and variable load oscillation tests.
9:00am 10:30 am BREAK
TOOL WEAR DURING MACHINING OF AA356 ALUMINUM ALLOYS: Zhongnan Dai, J.G. Morris, Light Metals Research Labs, Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506
11:00 am EVOLUTION OF ALUMINUM MICROSTRUCTURES IN THE ALUMINUM EXTRUSION PROCESS: Woiciech Z. Misiolek, Aluminum Processing Program, Rensselaer Polytechnic Institute Troy, New York 12180-3590
As a casting material, AA356 Aluminum alloy is widely used in the automotive industry. During machining, the tool wear mechanism for this alloy is significantly different from that for steel. For different as-cast metallurgical microstructures, materials with harder dispersed particles and stronger matrices show higher resistance to seizure because of an increase in the pressure requirement above which seizure occurs. This results in better machinability. On the other hand, hard particles act as small cutting edges on the tool materials, thereby causing tool wear due to the particle'S abrasive characteristics. The wear characteristics of cutting tools were investigated in this study. Scanning electron microscopy, optical microscopy, EDX analysis were used to identify wear mechanisms. The results obtained show that there are a number of different wear mechanisms that contribute to tool damage, and hence, to tool-life. The role of the as cast microstructure on tool wear was also studied in order to determine under what structural states tool wear would be reduced.
The final microstructure and its uniformity is responsible for the physical properties and surface quality of the extruded profiles. Extrusion is time dependent process and its deformation variables such as, deformation zone and dead zone geometry as well as extrusion speed and temperature, change in time. The final microstructure depends on the above mentioned extrusion parameters as well as billet microstructure and post processing treatment. Metal flow conditions are influenced by the process parameters. Both physical and numerical process modeling techniques have been applied to predict metal flow behavior during extrusion through dies with different geometries. Additional information, allowing understanding of microstructure evolution, can be obtained from the crystallographic characterization of the typical deformation zone regions such as dead metal zone, main deformation zone and recrystallized zone on the billet-container interface using the electron backscattering diffraction (EBSD) technique. This technique has been utilized to follow in detail the orientation aspects of the deformed grains in extruded aluminum. This analysis provides information which can be used in the die and process design to improve metal flow uniformity and therefore the microstructure of the final product. It also allows prevention of the typical extrusion defects like surface tearing.
9:30am THE EFFECTS OF PRE-AGING TREATMENTS ON FORMABILITY AND PAINT BAKE RESPONSE IN ALUMINUM AUTOBODY SHEET ALLOYS: J. Daniel Bryany, Reynolds Metals Company, Corporate Research and Development, Fourth and Canal Streets, P. O. Box 27003, Richmond, VA 23261
11:30 am METALLURGICAL SAMPLE PREPARATION AND IMAGEANALYSIS TECHNIQUES USED FOR THE EVALUATION OF AUTOMOTIVE MATERIALS: Matthias Hoffman, George A. Blann. Buehler Ltd., 41 Waukegan Rd., P.O. Box One, Lake Bluff, IL 60044; William R. Creech, BMW Manufacturing Corp., Greer, SC
The use of heat treatable aluminum alloys for automotive body panels is presently increasing, due to aluminum's attractive combination of low density and compatibility with current production methods. In these applications, the automotive paint bake cycle is used to impart a modest artificial aging response, referred to as the paint bake response (PBR), in the alloys following stamping. Unfortunately, the short duration of the paint bake cycle (as dictated by production demands) is generally insufficient to exploit more than a small fraction of the age hardening potential of the alloys. Reynolds Metals Company has developed a thermal treatment which has been shown to be effective in increasing the paint bake response by up to a factor of four, while at the same time improving the formability of alloys and reducing the natural aging rate. Through the use of atomic resolution microscopy and differential thermal calorimetry, the mechanism of pre-aging can be shown to be the result of changes in the precipitation sequence of metastable variants of Mg2Si, resulting in an increase in the precipitation kinetics during the paint bake cycle and a finer distribution of strengthening precipitates in the painted component. Through the use of pre-aging, our research has shown that 6XXX autobody sheet alloys may be produced which have both superior stamping performance as well as higher strengths in the stamped and painted components, resulting in automotive body panels with up to 50% higher dent resistance.
This paper focuses on the commercial application of aluminum alloys and composite materials used in the automotive market. Today's automotive materials require a high degree of reliability. Therefore, efficient and accurate material testing and characterization methods are essential. Automotive alloys and composite materials often times are evaluated for microstructural properties. This work focuses on the developments in the metallurgical Q & A and research lab by highlighting the latest advancements using automated and semi-automated sample preparation techniques. The interpretation and quantitative analysis of these microstructures Ts accomplished by utilizing automated image analysis techniques. Image Analysis allows for an efficient as well as accurate analysis of dimension measurements, constituent analysis, porosity measurements, etc.
10:00 am THE EFFECT OF THE DISPLACEMENT CONTROL ROUTINE ON THE ELONGATION TO FAILURE AND FAILURE MORPHOLOGIES IN SUPER PLASTIC AA - 5083: A.L. Lund, S.G. Pitman, MA Khaleel, M.T. Smith, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA99352 It has been noted in the literature that superplastically formed Al alloys fail by cavitation. The morphology of the final cavitated fracture region may be important in determining optimum forming conditions, by determining whether
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CARBON TECHNOLOGY III: Anode Productionl Performance
10:30 am AN APPROACH FOR A COMPLETE EVALUATION OF RESISTANCE OF A MATERIAL TO THERMAL SHOCK - PART 2 : APPLYING TO AN INDUSTRIAL PROBLEM AT ALBA: Bernard Samanos, Christian Dreyer Aluminium Pechiney, LRF BP 114, 73303 Saint Jean de Maurienne Cedex, France; A. Hameed G. Abbas, Jaffar G. Ameeri, Aluminium Bahrain, 570 Manama, Bahrain
Sponsored by: LMD Aluminum Committee Program Organizer: Jean-Claude Thomas, Aluminium Pechiney, Pechiney/Balzac, 92048 Paris la Defense, France
Wednesday, AM February 12, 1997
Room: 230C Location: Orlando Convention Center
This article presents in detail the steps taken to successfully resolve the problem of anode breakage due to thermal shock et ALBA. These steps can be essentially characterized as follows: 1) establishment of a method of accounting for anode breakages, 2) parametric studies on benchscale anodes, 3) effects on the process. Characterizing anodes in terms of resistance to thermal shock, following the method described in Part I, allowed us to appreciate the importance of each of the adjustable parameters of the process. The applied solution draws on a new grain size distribution formulation.
Session Chairperson: Boris M. Triko, Aluminum Company of America, 1000 Riverview Tower, 900 South Gay Street, Knoxville, TN 37902-1848
8:30am GREEN PASTE POROSITY AS AN INDICATOR OF MIXING EFFICIENCY: Per Stokka, Norsk Hydro Research Centre, N-3901 Porsgrunn, Norway
10:55 am ANODE PROPERTY DEVELOPMENT DURING HEAT TREATMENT: Mona Jacobsen, Department of Thermal Energy and Hydro Power, the Norwegian Institute of Science and Technology, N-7034 Trondheim, Norway; Oyvind Gundersen, Department of Engineering Cybernetics, The Norwegian Institute of Science and Technology, N-7034 Trondheim, Norway
Variations in green paste porosity were studied as a function of pitch content and mixing parameters. Porosity in paste from paste plants operating with different mixing systems, was measured and used to indicate the efficiency of the mixing. Changes in paste porosity during remixing in the laboratory were also studied.
8:55am
Change of weight, density, permeability and porosity of anode specimens were measured after being baked to temperatures between 300 and 1250°C. Test specimens were cut from a green anode and analysed prior to the baking to study green property variations. Density variations in the green anode were significant and influenced the permeability measured in the green specimens. In mathematical modeling of the baking process, anode property models for description of heat and mass transport phenomena in the anodes are required. As basis for the derivation of the property models, the anode was considered to be a composite medium consisting of pitch coke, filler coke and pores. The filler coke was divided into a coarse and fine size fraction. The fine fraction mix with the binder pitch to constitute the binder matrix. It was assumed that the binder matrix was uniformly distributed on the surface of the remaining coarse filler particles. The models were compared and verified against the data.
POTENTIALITIES IN THE PASTE PLANT: S. Wilkening, YAW Aluminium-Technologie GmbH, P.O. Box 2468, 53114 Bonn, Germany Over the last decade much progress in paste plant technology originated from computerized process control, improved process philosophy and P & ID's as well as full level 2 operation. This paper will focus on materials aspects to get out more from the intrinsic properties of coke and pitch. Proposals will be made how to utilize in a better way the structural properties of petroleum coke and the fluid and carbonization properties of binder pitch. Potential changes in equipment and lay-out will also be discussed. 9:20am VERTICAL ANODE CRACKING - THE VALCO EXPERIENCE: NorbertA. Ambenne, VoltaAlumium Company Ltd (VALCO), P.O. Box 625, Tema, Ghana, West Africa
11:20 am ANODE IMPREGNATION SYSTEM FOR ALUMINIUM REDUCTION CELLS: Georges Berclaz, Avenue St-Fran~ois, 3968 Veyras/Sierre, Switzerland; Vittorio de Nora, Jean-Jacques Duruz, Gaynor Johnston, MOLTECH, 9 Route de Troinex, CH 1227 Carouge-Geneva, Switzerland
During the period 1990 - 1995 the VALCO aluminum smelter experienced a serious anode cracking problem. Approximately 12 % of the anodes split mainly along a particular set of anode stubs. About half of these splits resulted in carbon pieces falling into the reduction cell with attendant operating difficulties. This cracking phenomenon started when the plant was converted from 41.5 to 48 inches longer anodes with the extra length added to one end of the anode. Results of the investigations revealed that several operating variables contributed to anode cracking in varying degrees. These factors include mix profile in anode former mold, anode stub-to-gap ratio, anode setting practices, pot condition, anode symmetry, and moisture content in anode aggregate. This paper discusses these factors and how they affected anode cracking at Valco.
The minimization of anode carbon consumption in aluminium reduction cells has an important technical, environmental and economical impact. The basic anode elements, such as coke and pitch, do not always have the desired properties and there is an increasing need to protect the anodes against oxidation by air and CO 2. A solution based on boric acid impregnation of the upper part of the anode has been tested at the industrial scale. Anodes have been impregnated using specially designed equipment to place the protection in the appropriate part of the anode and to avoid metal contamination. Results are shown for different levels of impregnation. Comparison to metal spraying protection is also analyzed.
9:45am AN APPROACH FOR A COMPLETE EVALUATION OF RESISTANCE OF A MATERIAL TO THERMAL SHOCK - PART 1 : APPLYING TO THE CASES OF ANODES AND CATHODES: Christian Dreyer, Bernard Samanos, Aluminium Pechiney, LRF BP 114, 73303 Saint Jean de Maurienne, Cedex, France The aim of this article is to describe a new method for characterizing a material in terms of resistance to thermal shock. Such characterization takes into account the criteria of thermal shock resistance to initiation (Kingery criterion) and propagation (Hasselman criteria). It can be applied equally well to hard or soft thermal shock. This new approach has the following main advantages : I) characterization of the material in terms of thermal shock is complete, 2) thermal shock tests or empirical formulae, the validity of which are often hard to establish, become unnecessary. Examples of the use of this new approach are presented for anodes and cathodes.
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CAST SHOP TECHNOLOGY V: Cast House Safety Sponsored by: LMD Aluminum Committee Program Organizer: Wolfgang A. Schneider, VAW aluminium AG, Research and Development, Georg-von-Boeselager-Str.25, 0-53117 Bonn, Germany
Wednesday, AM February 12, 1997
Room: 230B Location: Orlando Convention Center
Session Chairperson: Seymour G.Epstein, The Aluminum Association Inc., 900 19th St., N.w., Washington DC 20006
8:30am UPDATE ON MOLTEN METAL INCIDENT REPORTING: S.G. Epstein, The Aluminum Association Inc., 900 19th St., N.W., Washington, DC 20006 Millions of pounds of molten aluminum are handled every day, safely and without incident, in nearly every segment of the aluminum industry. However, there are inherent hazards in handling any molten material and explosions involving molten aluminum and water or other oxidizing contaminants continue to occur in plants throughout the world. While these are infrequent events that often result in little or no damage to equipment or injury to personnel, an awareness of the possible consequences of an explosion is critical to maintaining a safe casthouse. The aluminum industry has made an extensive effort to gain an understanding of molten metal explosions, the factors that promote them, and how they might be prevented. The effort has included laboratory studies, conducted over the past 45 years, and thorough investigations of plant incidents. As part of this effort, the Aluminum Association established in 1985 a world-wide molten metal incident reporting program to obtain and share information on plant incidents. Presently, there are more than 230 participants in the program representing about 300 plants located in about 20 countries. Findings from the nearly 1200 reports submitted to date are reviewed in this paper. 8:55am INVESTIGATION OF COATINGS WIllCH PREVENT MOLTEN ALUMINUMIWATER EXPLOSIONS - PROGRESS REPORT: R.T. Richter, D.D. Leon, T.L. Levendusky, Aluminum Company of America, Alcoa Technical Center, Alcoa Center, PA 15069 The aluminum industry has used Porter International 7001 (Tarset Std.) successfully as a protective coating in casting pits for over 20 years to prevent molten aluminum and water explosions until it was withdrawn from the market in 1994. The Aluminum Association contracted with Alcoa in 1995 to identify and test alternate coating materials which would be an acceptable replacement for Tarset Std. This paper will report the status of the program which was initiated in September 1995 and will be concluding in late 1996. Included in this paper are the screening and selection processes of the candidate coatings, results of initial molten aluminum/water explosion tests and the selection of the best performers for final explosion tests. 9:20am PROMOTING AWARENESS OF POTENTIAL HAZARDS INALUMINUM SCRAP: D.C. Pierce, C.H. Kenney, Reynolds Metals Company, 6601 West Broad Street, Richmond, VA 23261 There are a variety of potential safety hazards in any industrial activity and this includes the melting of aluminum scrap. The source of most hazards in scrap aluminum is the moisture or contamination that the scrap contains. Melting internal or purchased scrap remains the prevailing cause of molten metal incidents today. Everyone who handles scrap aluminum, from the first collection through to the melting, needs to be aware of the potential hazards. Facilities need to use a variety of approaches to increase safety awareness in all the operations. Scrap collectors, suppliers and brokers must be mindful of what the scrap hazards are, and the receiving plants must take steps to keep the hazards out of their casthouses. One of the new tools that plants have available is a fax -notification system operated by the Aluminum Association for information on scrap that has been rejected by another facility for safety
or health reasons. This system is felt to offer an important safety enhancement, because scrap dealers have been known to resell unsafe scrap after it has been rejected. Although the Scrap Rejection Notification System is currently operational, its success will be measured by how infrequently it is needed. 9:45 am BREAK 9:55am NEW GUIDELINES FOR SOW CASTING AND MELTING: a.N. Chaffin, Quality Challenges, Midlothian, VA23112; lE. Jacoby, Consultant, 3398 North Hills Road, Murrysville, PA 15668 The aluminum industry has experienced many incidents of explosions as a result of wet or contaminated sows being charged into molten metal. The presence of moisture in the cavity of a sow is often impossible to detect and therefore the sow is assumed to be safe. However, this undetected moisture can cause a serious explosion if it is submerged into molten aluminum. The Aluminum Association has prepared guidelines for sow casting, inspection and melting to help facilities protect themselves from the potential hazards associated with melting sows. The guidelines and this paper consider mold designs, casting, transportation & storage, inspection and melting operations. Recommendations are offered which can be used in conjunction with each plant's practices. The recommendations can help both the casting facility and the melting plant work toward a decrease in the possibility of an incident involving the melting of sows. 10:20 am THE SEARCH FOR PROTECTIVE CLOTHING FOR WORKERS EXPOSED TO THE HAZARDS OF MOLTEN ALUMINUM AND MOLTEN BATH: Ronald R. McHaney, Kaiser Aluminum and Chemical Corporation Bums are one of the leading causes of work injuries within the aluminum industry. Some physical and chemical properties of molten aluminum - low emissivity and viscosity - contribute to the potential for injury-producing incidents. Other properties, including high heat of fusion and shrinkage characteristics during cooling, add complexity to the task of identifying suitable protective clothing for workers exposed to the hazards of molten aluminum and bath. This presentation will address the initiative to identify protective clothing for workers exposed to those hazards and the progress that has been made including the development and application of the American Society for Testing Materials (ASTM) designation: F955, "Standard Test Method for Evaluating Heat Transfer Through Materials for Protective Clothing Upon Contact with Molten Substances". In addition, I will discuss the need to consider worker comfort and the potential for heat stress in the selection process. 10:45 am PANEL DISCUSSION: All Speakers
CAST SHOP TECHNOLOGY VI: Solidification of Cast Alloys Sponsored by: LMD Aluminum Committee Program Organizer: Wolfgang A. Schneider, VAW aluminium AG, Research and Development, Georg-von-Boeselager-Str.25, 0-53117 Bonn, Germany
Wednesday, AM February 12, 1997
Room: 240A Location: Orlando Convention Center
Session Chairperson: John Grandfield, Comalco Research Centre, P.O.Box 316, Thomastown, Victoria 3074, Australia
rapid production of components close to the final "near net shape" with a very good casting yield. Depending on the property requirements of the final product, it is often necessary to control casting soundness. Internal porosity can cause a loss of pressure tightness, a critical factor in parts such as engine blocks and manifolds which are required to keep various gases and fluids. The development of criteria functions should allow the prediction of the thermal conditions required to maintain porosity below some critical predetermined level. In order to determine criteria functions, it is necessary to acquire thermal data during casting solidification. A low pressure casting machine and die were instrumented to obtain "in situ" thermal analysis curves during the solidification of flat plates of thickness varying from 1/8" to 3/4" in Sr modified and unmodified 6290, 356 and 319 alloys. The paper describes that effort and some of the results obtained.
9:30am 8:30am MODELLING OF SOLIDIFICATION IN AI-ALLOYS: Nigel Saunders, Thermotech Ltd The Surrey Research Park, Guildford GU2 5YG and IRC in Materials for High Performance Applications, University of Birmingham, Birmingham BI5 2TT, United Kingdom Solidification in AI-alloys is a complex process usually occuring under nonequilibrium conditions with the possible formation of metastable low melting point eutectics and non-equilibrium phases. However, it has recently been shown that it is possible to use thermodynamic phase diagram calculations to simulate the non-equilibrium solidification of complex AI-alloys under so-called 'Scheil' conditions. Excellent results can be obtained for features such as fraction solid transformed as a function of temperature, phase formation, latent enthalpy and Cp of solidification etc. All of these features are important input into modelling of solidification processing particularly for software packages which simulate heat flow during casting. The paper will present the results of 'Scheil' simulations for a wide range of commercial AI-alloys showing comparison with experimental results for fraction solid transformed and phase formation. The use of subsequently derived Cp and heat evolution parameters in casting simulation packages will be discussed and examples of its application shown.
8:50am THE APPLICATION OF EFFICIENT PARALLEL PROCESSING TO FINITE ELEMENT MODELING OF FILLING, SOLIDIFICATION, AND DEFECT PREDICTION FOR ULTRA-LARGE SHAPE CASTINGS: David Snyder, Aluminum Company of America, Alcoa Technical Center, 100 Technical Drive, Alcoa Center, PA 15069; David Waite, Consultant, Coralville, IA; Alpesh Amin, HP/Convex Corporation, Atlanta, GA
A TECHNIQUE FOR THE ESTIMATION OF INSTANTANEOUS HEAT TRANSFER AT THE MOLDIMETAL INTERFACE DURING CASTING: Michael Trovant, Stavros Argyropoulos, Department of Metallurgy & Materials Science, University of Toronto, 184 College Street, Toronto, Ontario, Canada M5S 3E4 Many current advancements responsible for improving the accuracy of solidification algorithms have resulted from the incorporation of additional complex casting related phenomena into the numerical calculation scheme. More recently, however, the proper specification of boundary conditions has been found to playa critical role in limiting model inaccuracy. Of particular interest to casting are the temperature boundary conditions, which when adopted by many models appear to be the most troublesome. Temperature boundary conditions can vary significantly with time and position along the face of the casting and accurate heat transfer coefficients are notoriously difficult to obtain experimentally for all points on the mold/metal interface, especially when the influence of thermal contraction is acknowledged. A novel technique which minimizes the error associated with selecting boundary conditions without experimentation is proposed. Advanced knowledge of the air gap formation and its correlation to the heat transfer coefficient at the mold/metal interface is used to formulate a coupled mathematical model which determines the increase of the air gap and predicts the instantaneous cooling conditions at a given mold wall. The objective is to allow the modeler to estimate effect of thermal contraction on the heat loss at mold/metal interfaces without resorting to experimentation.
9:50am MECHANISM OF DENDRITE FRAGMENTATION IN CASTINGS: Shan Liu, Shu-Zu Lu, A .Hellawell, Michigan Technological University, Dept. of Metallurgical and Materials Engineering, Houghton, MI 49931
Finite element modeling has become widely to used simulate the filling, solidification, and defect formation in casting processes. For extremely large, complex parts, typical of automotive structural applications, the high cost of tooling makes process modeling an extremely useful tool. However, as the size and complexity of casting part geometry increase, the computational requirements for modeling become formidable. To address the challenge for modeling ultra-large shape castings, a finite element code was developed to efficiently take advantage of shared-memory parallel computing systems. This paper gives a brief description of the mathematical models which describe the casting processes. The implementation of the models and the numerical issues regarding memory architecture, parsing of computations, cpu synchronization, and overhead minimization for parallel processing are discussed. Examples are presented for filling and solidification analyses of permanent mold, tilt-pour, and die casting models run on an 8-CPU HP/Convex SPP1000 computer.
A temperature gradient stage was designed with a controlled deceleration mechanism to simulate the columnar growth in castingslingots where the growth velocities and temperature gradients at a dendritic front undergo a continuous decrease during solidification. Transparent materials of SCN -H20 and NH4CI-H20 systems were used so that the solidification process with various decelerations could be directly observed and video recorded. It is observed that fragmentation of secondary arms is directly related to the deceleration and this provides an intrinsic resource for the formation of equiaxed grains in castings where convection may be available for transportation of the fragments to the open liquid. The responses of a dendritic array to the deceleration, including primary spacing adjustment and tip radius adjustment etc., are also observed and discussed.
9:10am
THE VISUALIZATION OF THE PARTICLE CONTENT OF LIQUID ALUMINUM ALLOYS: N.D.G. Mountford, A. Simionescu, I.D. Sommerville, Department of Metallurgy & Materials Science, University of Toronto, Toronto, Ontario, Canada M5S 3E4
IN-SITU TEMPERATURE MEASUREMENTS IN LOW PRESSURE PERMANENT MOLD CASTING: Florence Paray, Joe Gruzleski, Department of Mining and Metallurgical Engineering, McGill University, 3450 University Street, Montreal, Quebec, Canada H3A 2A7; Joe Clements, Grenville Castings Ltd., Merrickville, ONT, Canada KOG INO; Bahadir Kulunk, Timminco Metals, Research and DeVelopment Center, Haley, ONT, Canada KOJ I YO The low pressure casting process has an increasing popularity as it allows a
10:10 am BREAK 10:20 am
Aluminum alloys can contain heterogenous impurities which will affect the strength of the final product and result in either failure during manufacture or in service. Pulsed ultrasound, conveyed down metal guide-rods from energized piezo-electric crystals, is passed into the liquid metal and reflections from any impurities can be recorded by special counting devices. Small par-
a matrix of secondary grains and eutectic phases. The primary dendritic grains evolved to become non-dendritic after reheating the slugs to semisolid temperature. The slugs were subsequently thixoformed at a temperature corresponding to a primary solid fraction of about 50% into thin plates and alternator pulleys. Special wear tests on the pulleys showed that they were comparable to steel pulleys. The material is potentially suitable for those applications demanding good wear resistance, light weight and low cost.
ticles of the order of 10 to 15 11m can be resolved and their behaviour such as in settling recorded. Sequential tests using particles of identified size and distribution such as SiC and TiA13 demonstrated the systems reproducibility. Such changes in composition resulting from imposed turbulent transfer with the associated pick up of very small oxide particles could also be shown. The effect of "sludge" formation such as that found in die-casting applications due to intermetallic phase precipitation could also be measured. This could be of value in process control of die casting systems. The developed system is adaptable to on line quality measurement and the recording of molten aluminum cleanliness in crucibles, ladles, furnace wells, launders and other transfer systems.
CHEMISTRY AND PHYSICS OF NANOSTRUCTURES AND RELATED NON EQUILIBRIUM MATERIALS V: Mechanical Properties
10:40 am FRACTAL ANALYSIS: POROSITY IN ALUMINUM CAST ALLOY: Bo-Tao Lee, Shu-Zu Lu, A. Hellawell, Michigan Technological University, Dept. of Metallurgical and Materials Engineering, Houghton, MI 49931
Sponsored by: Jt. EMPMDISMD Chemistry and Physics of Materials Committee, MSD Thermodynamics and Phase Equilibria Committee Program Organizers: Brent Fultz, 138-78, California Institute of Technology, Pasadena, CA 91125; En Ma, Louisiana State Univ., Dept. of Mechanical Eng., Baton Rouge, LA 70803; Robert Shull, NIST, Bldg. 223, Rm B152, Gaithersburg, MD 20899; John Morral, Univ. of Connecticut, Dept. of Metallurgy, Storrs, CT 06269; Philip Nash, Illinois Institute ofTechnology, METM Dept., Chicago, IL 60616
Porosity is a very common defect inAI-Si cast alloy. To examine the porosity, a fractal analysis was conducted to characterize the pores using two numbers, Fractal Dimension, D, and Shape Factor, IX. This analysis was based on the measurement of perimeters/areas of all individual pores using an image analyzer with changing magnifications. The result indicates that two types of pores, i.e., rough/shrinkage pores and smooth/hydrogen pores, can be distinguished by these fractal numbers. The shrinkage pores show a larger value of fractal dimensions whereas the hydrogen pores have a fractal dimension close to one. Combined with analysis for silicon particles, it is suggested numerically that shrinkage pores are more likely associated with the silicon phase that is not well modified, showing a rather coarse flake structure, and the hydrogen pores are in the regions where modification was well done with fine silicon particles.
Wednesday, AM February 12, 1997
Room: 330C Location: Orlando Convention Center
Session Chairperson:Walter W. Milligan, Metallurgical and Materials Engineering, Michigan Technological University, Houghton, MI 49931
9:00 am Invited SYNTHESIS AND MECHANICAL PROPERTIES OF NANOCRYSTALLINE INTERMETALLICS AND MULTIPHASE MATERIALS: l.A. Eastman', M. Choudry',2, M.N. RittnerP, C.I. Youngdahl',3, M. Dollar2, J. R. Weertman3, R.I. DiMelfi4, and L.I. Thompson','Materials Science Division, Argonne National Laboratory, 9700 S. Cass Ave., Bldg. 212, Argonne, IL 60439, 2Mechanical, Materials, and Aerospace Engineering, Illinois Institute of Technology, Chicago, IL 606163, Materials Science and Engineering Department, Northwestern University, Evanston, IL 602084• Reactor Engineering Division, Argonne National Laboratory, Argonne, IL 60439
11:00 am NUMERICAL SIMULATION OF DIE FILLING IN SEMISOLID METAL PROCESSING: Andreas N. Alexandrou, Franfois Bardinet, Mechanical Engineering Department, Worcester Polytechnic Institute, Worcester, MA 0 1609; Willem Loue, Pechiney CRY, Centre de Recherche de Voreppe BP27, 38340 Voreppe, France Semisolid Metal Processing is gaining interest very rapidly. This manufacturing approach offers distinct advantages over other near-net-shape technologies, like a more homogenous microstructure and less porosity and thus excellent mechanical properties. A perfect control of the die filling during processing is however necessary, especially in the case of semisolid forming of aluminum, where a non-controlled die filling can lead to oxide inclusions. Numerical simulation would be a powerful tool, as it would allow to predict die filling and the optimization of die design. However, the constitutive behaviour of such semisolid metals is rather complex. Their non-Newtonian behaviour does not depend only on the volume fraction of liquid, but also on the metal's history prior to processing and the processing conditions. In this paper, a Bingham power-law relation is presented, capable of describing correctly the rheological behaviour of the semisolid metal. This constitutive equation is then introduced in a modified version of the casting simulation package SIMULOR. Simulation results on the filling of a 2-D cavity under various conditions are shown. Issues related to die design of dies, using numerical simulation will also be addressed.
The mechanical behavior of nanocrystalline intermetallic and multiphase materials has been investigated using disk bend, tensile, and compression techniques. Materials such as NiAI, TiAI, AI-A13Zr, and Cu-SiOx were synthesized by the gas-condensation technique using electron beam heating. Disk bend tests of nanocrystalline NiAI and TiAI showed evidence of improve ductility at room temperature in these normally extremely brittle materials. In contrast, tensile tests of multiphase nanocrystalline AI-A13Zr samples showed significant increases in strength, but substantial reductions in ductility with decreasing grain size. Results from compression tests of nanocrystalline Cu and Cu-SiOx will also be described. Implications for the operable deformation mechanisms in these materials will be discussed. *This work was supported by the U.S. Department of Energy, BES-Materials Science, under Contract W-31-109-Eng-38, the Alcoa Corporation, and by AFOSR Grant # FY9620-92-J. 9:30am INFLUENCE OF PROCESSING ON INTERNAL STRUCTURE OF NANOCRYSTALLINE Ni: B.R. Elliott, and J. R. Weertman, Northwestern University, Evanston, IL , Metallurgy Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-0001
11:20 am SOLIDIFICATION PROCESSING OF ALUMINUM CASTING ALLOY REINFORCED WITH CERAMIC MICROSPHERES FOR TIDXOFORMING: P.D.D. Rodrigo, K. Xia, N. Setargew, Materials Group, Department of Mechanical and Manufacturing Engineering, University of Melbourne, Parkville, Victoria, Australia 3052; P. Fitzgerald, G. Withers, Cyco International, 1297 Nepean Highway, Cheltenham, Victoria, Australia 3192
Different processing routes can vary the internal structure of nanocrystalline compacts. As a result a single grain size measurement is insufficient to interpret mechanical property results. Blind comparison between samples with different processing histories may be hazardous since their internal structures (grain size distribution, grain boundary character, pore size distribution, adsorbed or chemically bonded impurities) are shown to vary. In particular, annealing samples to grow the grain size for producing Hall-Petch plots is shown to drastically change the pore size distribution and density in powder compacted samples that are not outgasssed prior to compaction. Improvements in processing, particularly compaction procedure, are illustrated by microscopy, XRD, SANS, PGAA, FNAA, archimedes density, and indenta-
A cast aluminum matrix composite based on an AI-Si-Mg alloy has been developed. The reinforcement was in the form of hollow microspheres, a ceramic by-product from coal power stations. The particles were incorporated into the aluminum alloy melt by mechanical stirring either in the semisolid state or full liquid state. The composite melt was cast from full liquid temperature to produce slugs for thixoforrning. A variety of compositions, reinforcement volume fractions and processing parameters were used. The as-cast microstructure consisted of fine, equiaxed dendritic primary grains in
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tion tests. It is shown that with care and knowledge of the process inert gas condensed and compacted samples can be produced with few extrinsic defects.
COMPOSITES-MECHANICAL PROPERTIES & PROCESSING
9:50am MECHANICAL PROPERTIES OF NANOCRYSTALLINE Ni: B.R. Elliott, J.R. Weertman, Northwestern University, Evanston, IL
TMS General Abstract Session Wednesday, AM February 12, 1997
The influence of improved processing on the internal structure of n-Ni has lead to improved mechanical properties. Correlation between the internal structure (including grain size, pore size distribution, and impurities) and results of a variety of mechanical properties measurements will be presented including hardness, tensile and compression tests. Some comparison will also be made between samples produced by traditional inert gas condensation (IGC) and the newer jet blown arc IGC. (JBA-IGC). Possible deformation mechanisms will be discussed in light of the structure and property measurements.
Room: 2400 Location: Orlando Convention Center
Session Chairperson: M.A. Self, Mechanical Engineering Dept., Tuskegee University, Tuskegee, AL 36088
8:30am DOUBLE CANTILEVER BEAM TEST APPLIED TO MODE I COMPOSITE DELAMINATON: A COMPARISON OF ANALYSIS METHODS FOR FIBER BRIDGING MATERIALS: W. Richards Thissell, Anna K. Zurek, Los Alamos National Laboratory (LANL), MST-5, G755, Los Alamos, NM 87545; Frank Addessio, Todd O. Williams, T-3, B-216, Los Alamos, NM 87545
10:10 am A CRITICAL ASSESSMENT OF THE WILLIAMSON-HALL METHOD FOR THE DETERMINATION OF RESIDUAL STRESS IN NANOCRYSTALLINE STRUCTURES: F.S. Miller, D.C. Van Aken, Metallurgical Engineering, E.W. Bohannan, J.A. Switzer, Chemistry, The University of Missouri-Rolla, Rolla, MO 65409
The double cantilever beam (DCB) test is widely used to characterize the mode I delamination and bridging behavior of laminated continuous fiber composite materials. Many composite systems exhibit significant large scale fiber bridging that is not included in the derivation of the analysis methods. The bridging contribution to fracture energy is statistical in nature. A comparison is made of several analysis methods for applicability to systems exhibiting significant fiber bridging. A general DCB analysis method is described that takes into account loading pin effects, material orthotropy, crack root inelasticity, and large scale deformation behind the crack faces. Some material system specific characteristics that lead to enhanced fiber bridging are described.
An important aspect of the processing<->microstructure<->property relationships is the characterization of nanocrystalline structures by x-ray diffraction. The Williamson-Hall analysis is often used to deconvolute the line broadening effects of grain size and residual stress. In this study, CulCup nanocrystalline films were produced by electro deposition. This technique produces a composite structure consisting of pure Cu and Cu20 grains each with diameters in the range of 10 to 20 nm. Electro deposited films were characterized by x-ray diffraction to determine both grain size and residual stress. The Williamson-Hall analysis was tested by direct measurement of the grain size by TEM and by using thermal treatments to vary the state of residual stress in the films.
8:50am HYGRO-MECHANICAL BEHAVIOR OF A CLASS OF SWELLINGTYPE THREE-DIMENSIONALLY BRAIDED COMPOSITES: Surya R. Kalidindi, Abdel Abusaifeh, Materials Engineering Department Drexel University, Philadelphia, PA 19104
10:30 am BREAK 10:45 am MECHANICAL PROPERTIES OF CU/Ag MULTI-LAYER COMPOSITES: Qing Zhai, Augusto Morrone, Fereshted Ebrahimi, Materials Science & Engineering, University of Florida, Gainesville, FL 32611
A new class of swelling-type composite materials using three-dimensionally braided graphite or Kevlar fibers have been designed and processed for potential applications in bone implants. These composites derive their swelling from the hydrophillic nature of the matrix material used in their production. A combined experimental and modeling study was undertaken to study the hygro-mechanical behavior of this class of materials. The properties of interest included the swelling strains, elastic properties, yield strengths, and impact strengths. Note that these properties for the braided composites are highly anisotropic. Furthermore, the mechanical properties are strongly affected by the amount of absorbed water. Cylindrical samples of braided composites were produced with varying fiber volume fractions, braid angles, fiber type (graphite and Kevlar), matrix cross-linking (to control the degree of swelling in the composite), and fiber architecture (uniaxial, rectangular braided, and circular braided). Swelling strains at saturation were measured in these samples. Simple compression tests were performed on these samples in at least two principal material directions in both dry and saturated conditions. Elastic moduli and yield strengths were extracted from these tests. Cylindrical samples of the matrix material (without fibers) were also produced and utilized to fully characterize the hygro-mechanical behavior of the matrix material. Constitutive models have been proposed to predict the various hygromechanical properties of the 3-D braided composites in both dry and saturated states as a function of the fiber and matrix properties, fiber volume fraction, and fiber orientations. A weighted average of the currently employed isostrain and isostress models in literature for this class of materials was found to consistently yield better predictions for the anisotropic elastic moduli, when compared to the predictions of either of these models. The weighting factor was found to be dependent primarily on the fiber and matrix materials (i.e. independent of the type of loading, fiber volume fraction, and fiber orientation) and has been interpreted as an interaction parameter between the various fiber and matrix systems. These models were then extended to predict the swelling behavior and yield strengths of the 3-D braided composites. The accuracies of the proposed models were evaluated by comparisons against
When materials microstructure reaches nanometer scale, their properties often appear to be unusual, which cast much consideration these days. Specifically, the extraordinarily high strength has been the subject of many recent investigations. The nanomaterials discussed in this paper is a CuiAg multilayered composite, which is produced by electrodeposition in a single-bath cyanide solution. In this paper the effects of copper layer thickness and heat treatment on interfacial structure and mechanical properties of CulAg multilayered composites are presented. Tensile testing was used to investigate the mechanical properties of the samples. SEM, X-ray diffraction and TEM were used to analyze the relation between the mechanical properties and microstructure of these composites. 11:05 am STABILITY OF NANOCRYSTALLINE ALLOYED AND MULTILAYER PVD NITRIDE FILMS: R. A. Andrievski, Institute for New Chemical Problems, Russian Academy of Sciences, Chernogolovka, Moscow Region, 14232 Russia The alloyed and multilayer films of TiN, ZrN, NbN, and CrN with nanocrystalline structure prepared by arc deposition were investigated by XRD, electron microscopy and microhardness measurements. A general tendency of the microhardness to increase with decreasing layer thickness was found in TiN-NbN(ZrN) systems. The unmonotonous change has been revealed in TiN -CrN one. The influence of spinodal decomposition, recrystallization, and heterodiffusion on the films' properties is also demonstrated and discussed in detail. R.A.Andrievski, I A.Anisimova, V.P.Anisimov et ai, Thin Solid Films 261(1995) 83.
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ever a new aluminum alloy matrix composition promises to combine all the desired features of the matrix. Data will be presented showing retention of high longitudinal strengths while also achieving much higher transverse and monolithic strengths. The specifics of this system will be discussed as well as directions for optimization.
experimental measurements described above as well as the predictions from a finite element simulation of the response of a representative unit-cell of the braided composite. These comparisons revealed that the proposed models are reasonably accurate in their predictions. 9:10am RF MAGNETRON SPUTTERING OF MoSiz + X SiC COMPOSITE TO FilMS: S. Gonodaryan', J.J. Moore', T.R. Ohn02, 'Advanced Coatings and Surface Engineering Laboratory, Dept. of Met. and Materials Eng., Colorado School of Mines; 2 Dept. of Physics, Colorado School of Mines, Golden, CO 80401-1887
10:10 am BREAK 10:20 am STRUCTURE AND PROPERTIES OF ALUMINUM BASED PARTICULATE COMPOSITES SYNTHESIZED BY MECHANICAL ALLOYING: J.M. Molnar, T.H. Courtuey, Department of Metallurgical and Materials Engineering, Michigan Technological University, Houghton, MI 49931
A critical component of a prototype coating system being developed to protect molybdenum against high temperature oxidation (i.e. at 1600°C for 500 hours) is a functionally graded layer based on MoSi 2+ x SiC (where x is the variable mole fraction of SiC in the film). Different approaches for synthesizing composite films include sputtering from elemental or compound targets, reactive sputtering, and direct sputtering of composite targets. This paper will explore the feasibility of synthesizing composite films by RF magnetron sputtering of a composite target. Results of compositional depth profiling using Auger Electron Spectroscopy, microstructural evaluation and X-Ray diffraction analyses of the films will be presented. In particular, the diffusion of silicon and carbon in to the substrate will be characterized using a "ballcratering" technique followed by auger electron spectroscopy (AES). This technique will help to overcome the disadvantages associated with ion-beam sputtering during depth profiling (e.g. different sputter yields for the constituent elements, interface broadening effects, etc.).
Aluminum-based particulate composites have potential application in services requiring high strength combined with low density. We have used mechanical alloying followed by hot isostatic pressing (HIPing) to fabricate a series of AI-Si-C particulate composites. Pure Al or AI-Si eutectic powder was mixed with graphite and SPEX milled for varying times. Consolidation of the mechanically alloyed powders was done by HIPing at 180MPa (26 ksi) which resulted in afully dense composite. Aluminum carbide (AI4C3)is formed during consolidation. Formation of SiC is a possibility as well. Maximum hardnesses following HIPing correspond to an approximate yield strength of 990 MPa (144 ksi). Properties as they depend upon processing conditions and the resulting microstructure are discussed. This work was supported by the Army Research Office. 10:40 am THERMOMECHANICAL PROCESSING OF SUPERPLASTIC SICP/ 6061 ALUMINUM ALLOY COMPOSITE MADE BY A VORTEX METHOD: Tsunemichi Imai' and Takeo Hikosaka2, 'National Industrial Research Institute of Nagoya, I Hirate-cho, Kita-ku, Nagoya 462, Japan; 21ndustrial Research Institute, Aichi Prefectural Government, Nishishinwari Hitotsugi, Kariya City, Aichi 448, Japan
9:30am EFFECT ON COMBINED LOADING ON CRACK-TIP DEFORMATION OF GRAPHITE/EPOXY COMPOSITES: M.A. Self, C.M. Hargrove, Mechanical Engineering Dept., Tuskegee University, Tuskegee, AL36088 An experimental investigation of the crack displacement and failure modes of graphite/epoxy plates [0/±45/90l2, under tensile loading with central cracks at various angles (15°, 30°, 60°, 75°, and 90°) was carried out. A mixed mode state of stresses developed at the center of the crack as a result of the crack orientation. Laser Speckle technique, a high sensitive noncontact technique, was employed to measure Crack Opening Displacement (COD) and Crack Shearing Displacement (CSD) of the crack emanating from the normal and tangential stresses at the crack center. Damage zones of the material at different crack orientation were examined and evaluated. The critical stress intensity factors for mode I and mode II were obtained from COD and CSD at failure. Detail studies were performed to investigate the behavior of the material during loading application and the effect of the angles on the stress distribution. The data obtained were compared with the Linear Elastic Fracture Mechanics (LEFM) solutions. The comparisons suggested a correlation within ±8 percent deviation. It was concluded from this investigation that the theoretical analysis could be applied to obtain the fracture properties of graphite/epoxy composites.
Thermomechanical processing to produce the HSRS for the SiC/6061 Al alloy composite fabricated by a vortex method before squeeze casting and extrusion was investigated. The SiC/6061 Al composites hot-rolled in rolling strain per passes of 0.05-0.3 and at 573K indicate the m value of 0.4-0.6 and the total elongation of 200-300% in the strain rate of 0.08- 1.3 sol and at 853K. The total elongations of the composite hot-rolled at 523 and 623K decrease to less than 150%. The flow stress of the composite heat treated by T6 after rolling increased and the total elongation decreased as compared with those of the composite without T6 due to reaction between SiC and matrix. The fracture surface of the composite has a partially liquid phase and filaments and it is thought that an interfacial sliding at the liquid phase contributes to the HSRS in addition to grain boundary sliding in the SiC/6061 Al composite fabricated by a vortex method. 11:00 am COMPATmlLITY OF SEVERAL REINFORCEMENTS WITH Ti-A1 AND DEVELOPMENT OF THE COMPOSITES: Chikura Fujiwara, Nagoya Aerospace Systems Works, Mitsubishi Heavy Industries, Ltd., 10, Oye-Cho, Minato-Ku, Nagoya, 455 Japan
9:50am INCREASING THE OFF-AXIS AND MONOLITHIC STRENGTHS IN CONTINUOUS FmER REINFORCED ALUMINUM MATRIX COMPOSITES: Colin McCullough, Paul R. Nisson*, Steven R. Pittman Bill E. Birkholz, MMC Program, 3M Company, St. Paul, MN 55144-1000; *3M / MMC Production Plant, Middleway, WV 25430
Titanium aluminide matrix composites have received considerable attention due to their potential to have high specific strength and stiffness at high temperature. And SiC fibers are considered to be promising candidates for reinforcement of the composites. SiC/TiAI composites, however, are difficult to be fabricated in good state because of severe reactions at the interface being taken place during fabrication process. One of the most effective means to suppress the excessive reaction is to apply the diffusion barrier coating on the surface of SiC fiber. Another solution to fabricate a TiAI matrix composite is to apply the reinforcement which has good compatibility with matrix, TiAI. Several candidates for diffusion barrier coating between SiC fiber and TiAI were evaluated, then W and HfC showed excellent effects on suppress excessive interfacial reaction, while other candidates such as AIP3' Zr, B 2 , Ce2 0 3 were not effective. Based on these results, a desirable interface model of organic polymer derived SiC reinforced TiAI composite is proposed. Other fibers were evaluated as reinforcements of TiAI matrix composites. Then it was found that W, W-Re, Re were good in compatibility with TiAI and consolidated with TiAI in good state. As a result, W-3%RelTiAI showed 680 Mpa at 1373K.
Tremendous progress has been made in the properties of aluminum alloys reinforced with 60-70 vol. % of continuous alumina fibers, with tensile strengths routinely averaging 250 ksi (1.7 GPa) in the longitudinal direction. The choice of matrix and its resulting microstructure is critical in obtaining such strengths and the matrices used at 3M to date are a pure Al and an AI2%Cu alloy. This leads to design considerations in composite performance (transverse and shear strengths) and in any unreinforced areas. To date, the pure Al and AI-2%Cu matrix composites have transverse strengths of 25 ksi (170 MPa) and 40 ksi (275 MPa) respectively. While these values have applications, higher strengths may be desirable. Also unreinforced areas could benefit greatly from higher yield strengths. Use of traditional higher strength alloys is seriously restricted due to both the reactivity with the fiber and their segregation behavior which dramatically reduces longitudinal strength. How-
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11:00am
Ceramic particulates reinforced composite is considered to be an effective way for improving the mechanical properties ofTi alloys and Ti-AI intermetallics. In the present study, Ti-24AI-llNb(at%)110wt%TiB in-situ composites were prepared by the blended elemental powder metallurgy method. The tensile and high cycle fatigue properties of the composites were found to be much superior to those of the unreinforced matrix. Modification of the matrix microstructure was performed by annealing the composite at 1573K and air cooling, which resulted in a very fine Uz+~ microstructure. The mechanical properties, particularly the fatigue property, were further improved by this microstructural modification technique.
base indicates that flip chips are the most reliable interconnection scheme in the industry since its inception. Moreover, the combination of C-4 mounted die and alumina multilayer ceramic (MLC) substrates provided the highest overall package reliability. This paper will discuss several key technical attributes such the joint controlled collapse feature, self-centering and throughput which is independent of die VO count. Joint design, process, compositional and metallurgical factors will be discussed in the context of the very significant effect they have on reliability as welL Flip chip technology is flexible, having been successfully utilized with several generations of chip carriers. Important also is the ability to predict the thermal-mechanical (fatigue) behavior of C-4 joints. When attached to ceramic carriers, the failure rate of flip chip joints obey a distance-from-neutral point (DNP) dependence defined by the Coffin-Manson (C-M) relationship. Modifications to the CoM relationship necessary for this application will also be discussed. It will be shown that the technology is sufficiently extendible to satisfy the trends of smaller, lighter, faster, denser, etc. which are expected to continue in the future. New developments such as chip underfill and future trends including DCA and their reliability implications will also be discussed.
11:20 am A STRUCTURE DESIGN OF CARBON FffiER REINFORCED ALUMINUM MATRIX COMPOSITE: Jiwen Wang ,Geyang Li, Tao Hong, Pengxing Li, Anjing Yang, Dept. of Mat. Sci., Shanghai Jiao Tong University, Shanghai, 200030, China
8:55 am INVITED A NEW RELIABILITY ASPECT OF HIGH DENSITY INTERCONNECTIONS: Jorma Kivilahti, Helsinki University of Technology, Materials and Manufacturing in Electronics, Vuorirniehentie 2A, Fin-02150 Espoo, Finland
A process which combines fiber coating and particles hybridizing together has been utilized for the structural optimization of carbon fiber reinforced aluminum matrix composite. SiC coating was derived by Sol-gel method and SiC particle hybridizing was processed in Sol-gel solution simultaneously. Squeeze-cast process was used to get bulk composite materials. SEM analysis of the material showed a well fiber distribution in Al matrix by particles hybridizing. Mechanical properties of the composite were improved especially for the axial strength. HRTEM research indicated the coating to be an effective barrier of the interface reaction. CI Al interfacial reaction was also studied meantime which revealed that pan-based carbon fiber reacted heavily with aluminum matrix. The nucleation and growth of the reactants were discussed.
Increasing importance of portability in telecommunication and consumer electronics is activating the research and development work on reliable, costeffective fine-pitch interconnections and substrate technology alternatives. However, high density interconnections may produce increasing difficulties, e.g. in paste printing, component alignment and acceptable residual levels. Moreover, increasing rnicrojoint densities are related to decreasing solder joint volumes, and therefore, it is even more likely that the whole solder volume will take part in the reactions, for example, between a solder, Flip Chip (FC) bump and substrate metallisation. Similar consequences of the miniaturization are encountered in the bump-limiting metallurgy; the total volumes (or thicknesses) of the diffusion barriers and adhesion layers and the original filler, alike, can transform into the matrix of intermetallics, which due to their inherent brittleness make the microjoints mechanically too weak to withstand thermal stresses. Accordingly, for confirming adequate reliability of rnicrojoints it is essential to have better understanding and control on metallurgical compatability of dissimilar materials being in contact with each other. In this communication results of metallurgical studies on various FC bumpsolder-substrate metallization reactions are presented. As specific examples, the bump-solder-substrate interactions have been studied experimentally with Au- as well as with Ni-bumped test chips, which were reflow-soldered with the eutectic SnPbAg filler at 235°C for various times onto Au/Ni- and Cuconductors on the FR-4 substrates. The electrical properties, structural integrity and evolution of microstructures (i.e., intermetallics, Pb-rich solution or eutectic structure) of reflow-soldered Flip Chip joints were examined in detail with the conventional tests and materials characterization methods. For studying the metallurgical compatibility and controlling the reaction kinetics between Au, Ni and eutectic SnPb and SnPbAg, the wedge-shaped diffusion couple experiments which more clearly illustrate the effect of solder layer thickness on the volume fraction of the intermetallics in the microjoints, were conducted using the RMA flux as well as a vacuum furnace. The thermodynamics of the AuSnPb, NiSnPb and CuSnPb systems were critically modeled and used for rationalizing the observed bump-solder-substrate reactions in the Flip Chip joints as well as in the diffusion couples. On the basis of metallurgical considerations a new Pb-free solution to this "small-volume-problem" is also addressed.
THE EFFECT OF MATRIX MICROSTRUCTURE ON THE MECHANICAL PROPERTIES OF Ti3AVTiB PARTICULATE COMPOSITES: Satoshi Emura, Masuo Hagiwara and Yoshikuni Kawabe*, National Research Institute for Metals, 1-2-1 Sengen Tsukuba Ibaraki 305 Japan; *Chiba Institute of Technology, 2-17-1 Tsudanuma Narashmo Chiba 275 Japan
DESIGN AND RELIABILITY OF SOLDERS AND SOLDER INTERCONNECTS: Session V: Interconnect Design and Reliability in Electronic Packages I Sponsored by: MSD Flow and Fracture; SMD Mechanical Metallurgy; EMPMD Electronics Packaging and Interconnection Materials Committees Program Organizers: R.K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; D.R. Frear, Sandia National Laboratory, Mail Stop 1411, Albuquerque, NM 87185; S.ML Sastry, Washington University, Mechanical Engineering Dept., St. Louis, MO 63130; KL Murty, North Carolina State University, Materials Science and Engineering Dept., Box 7909, Raleigh, NC 27695; P.K. Liaw, University of Tennessee, Materials Science and Engineering Dept., Knoxville, TN 37996; WL Winterbottom, Reliability Consultant, 30106 Pipers Lane Court, Farmington Hill, MI 48331 Wednesday, AM February 12, 1997
Room: 332 Location: Orlando Convention Center
Session Chairperson: Sung K. Kang, IBM Corp., T. J. Watson Research Center, Room 37-250, P.O. Box 218, Yorktown Heights, NY 10598; Professor Jorma Kivilahti, Helsinki University of Technology, Materials and Manufacturing in Electronics, Vuorimiehentie 2A, Fin-02150 Espoo, Finland
9:20 am INVITED ELECTRONIC PACKAGING DESIGN FOR RELIABILITY: William L. Olson, Motorola Corporate Manufacturing Research Center, 1301 East Algonquin Avenue, Room 1014, Schaumburg, IL 60196
8:30 pm Invited FLIP CHIPSOLDER INTERCONNECTIONS - A RELIABILITY PERSPECTIVE: Karl Puttlitz, IBM Microelectronics, B/330-IAX44-173, GFKA, Rt. 52, Hopewell Junction, NY 12533
Consumer electronics products continue to increase rapidly in complexity while shrinking in size. This trend is driving development of a variety of new electronic packages that provide much higher interconnect density/in2 of PCB surface - without compromising the product's reliability or quality. This challenge has resulted in a proliferation of packaging alternatives including PBGA's, COB, micro-BGA, CSP and DCA. Selecting the most appropriate
The solder ball flip chip or so-called C-4 connection was introduced by IBM nearly three decades ago as an alternative to manual wire bonding whose productivity and reliability were not acceptable at the time. A very large data
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package for a given product requires careful engineering of the product's features, reliability and cost. My presentation will review the various semiconductor packaging approaches with an emphasis on design for high value and reliability. Results will be presented for a new multi-flip chip BGA package which provides excellent interconnect reliability for reasonable cost.
and substrate. The package is modeled as a multilayer structure (dielectric filmlelastomeridie) where the low modulus elastomer layer behaves like an adhesive bond in shear. The analysis enables tailoring the compliant layer (modulus and thickness) to achieve targeted assembly reliability goals. Both mechanical models capture the reliability impact of the design parameters and materials in a quantitative manner. They can be easily implemented as PC-based design-for-reliability tools to conduct parametric studies on chip, board and assembly parameters.
9:45 am INVITED A STUDY ON THE SOLDER JOINT RELIABILITY OF THE OPTOELECTRONIC PACKAGING WITH FLIP-CHIP BONDING: long Tae Moon, GJ. Joo, M K. Song, K.E. Pyun, H.M. Park, Semiconductor Research Division, Electronics and Telecommunications Research Institute, 161 KajonjDong, Yusong-Gu, Taejeon, 305-350, Korea
10:35 am BREAK 10:45 am INVITED QUALIFICATION TEST FOR SOLDER ATTACHMENT OF CHIPSCALE BGA PACKAGING: Vern Solberg, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134
The optical transmitter and receiver modules were fabricated by applying flip chip bonding process. It was possible that the degree of alignment accuracy controlled below 1 ~ by the force of solder self-alignment. To minimize parasitic capacitance and inductance induced from the solder joint, the reflowed solder ball on Si substrate was varied from 100 11m to 5 11m. The Pb-In, PbSn, In-Sn and In-Ag alloys as the bonding materials were deposited above UBM on the Si substrate by using thermal evaporation method. During the reflowing process, the behavior of solder ball formation, and the intermetallic compounds between the UBM and solder composition were inspected with various heating rates and the use of flux. During the flip chip bonding process, the solder joint shape and the gap between Si substrate and optical devices were controlled by means of a various temperature profiles and bonding force. The solder joints reliability of the flip chip bonded optical submodules were evaluated by shear, thermal shock, and thermal cycling test. In the case of the thermal shock test, the range of temperature was from 25°C to the liquid N 2• Thermal cycling numbers were 1000 cycles from -40°C to 120°C. These samples were analyzed by optical microscopy, SEMIEDS and TEM.
Chip-scale package family for silicon products can be combined to help the engineer and designer meet the most demanding goals for electronic miniaturization,. The significant advantage to employing the miniature Chip-Scale Packaging (CSP) technology is three-fold: higher component density, more efficient assembly automation and enhanced product performance. Bare or unpacked die may be considered for miniaturization, however, a significant advantage a packaged device has over bare die is the ability to test and screen the product before surface mount technology, chip-scale BGA devices have proved efficient, rugged and easily adapted to existing high volume SMT manufacturing processes. Of primary concern to anyone utilizing a new technology is finished product reliability. In this paper, the author will describe several chip-scale device structures, the operational environments they are expected to withstand and the results of, long-term thermal stress testing of the 46 I/O I1BGA Flash Memory packages that have been reflow solder attached to conventionallarninated circuit structures. Topics covered include: Standards for CSP Technology, Assembly Process Methods, Defining Product Use Environment, Planning the Assembly Test Strategy. Although many of the products being introduced in the miniature chip scale package are compatible with existing surface mount assembly processes, the contact size and pitch are relatively small. And although high assembly yields have been achieved, developing a reliable product using chip-scale devices requires uniform solder paste printing and continued assembly process monitoring.
10:10 am INVITED RELIABILITY CHALLENGES AND MODELING OF MINIATURIZED SOLDERED ASSEMBLIES: lean-Paul Clech, EPSI Inc., P. O. Box 1522, Montclair, NJ 07042 Miniaturized electronic packages have emerged that bring about new reliability challenges and, in some cases, have revived the concerns of Leadless Chip Carriers (LCCCs) on organic substrates: 1) most of these packages are leadless; 2) their Coefficient of Thermal Expansion (CTE) is low because of the high silicon contents of shrinking or disappearing packages; 3) the assembled packages may have a low stand-off height (for miniaturization purposes); 4) typical assemblies are very fine-pitch with micro-solder joints having smaller load bearing or crack propagation areas than conventional surface mount assemblies. The above attributes may be detrimental to long term solder joint integrity and suggest that reliability be looked at carefully, more so than with conventional surface mount assemblies. This talk will present thermal stress and reliability models that can help tackle those problems and ensure that assembly reliability is built-in during the early stages of product design. Two examples of engineering models of miniaturized assemblies will be discussed that enable rapid assessment of the impact of package geometry and materials on assembly reliability. The first example is a model of flipchip assemblies with underfill. The model quantifies the solder joint relief provided by the underfill layer and its effect on assembly stiffness. The mechanics of flip-chip with underfill are unique since they involve an increase in assembly stiffness to provide for solder joint strain relief. The analysis is that of a multilayer structure (boardiunderfilVdie) that deforms under thermal loads and 'external' forces and moments exerted by the solder joints. Predicted shear strains in the underfill layer are in good agreement with moire measurements. In the limiting case where the shear modulus of the encapsulant is very low, the model converges to Hall's axisymmetric model for conventional LCCC assemblies. The analysis also gives interfacial stress distributions, a useful feature to assess whether the encapsulant/die and substrate interfaces are overstressed. Various parametric studies are conducted showing that the encapsulant modulus must be high enough to provide adequate strain relief in the solder joints, in agreement with experimental results and advanced finite element studies. Increasing the encapsulant modulus stiffens the assembly, because of mechanical coupling between the die and substrate, but the increased stiffness is overshadowed by much larger reductions in the solder joint strains. The second example is that of a micro-BGA construction where a compliant elastomer layer provides for decoupling between the die
11:10 am INVITED RELIABILITY OF ENCAPSULATED SYSTEMS FOR FLIP-CHIP ASSEMBLIES: Cindy M. Melton, Daniel R. Gamota, Motorola, Interconnect & Assembly Technology Research Group, Corporate Manufacturing Research Center, Room 1014, 1301 East Algonquin Road, Schaumburg, IL 60196 Encapsulant materials for flip chip on board assemblies were developed to address the issues of thermal mismatch between the various materials used in this assembly methodology. Several experimental encapsulant materials with enhanced flow properties, shorter cure schedules, and lower stresses have been studied for their effect on manufacturability and their behavior as a compliant structure surrounding the solder joints. Materials characterization studies were performed on the various encapsulants to determine the glass transition temperatures (T.), tensile elastic and loss modulii (E' and E"), flow profiles, coefficients of thermal expansion (CTE), radii of curvature, stress relaxation as functions of temperature and moisture, and apparent strengths of adhesion. In addition, reliability tests were conducted using FR4 substrates populated with die and underfilled with the various encapsulants to determine the relationship between materials properties and, package and solder joint reliability responses.
11:35 am INVITED DESIGN OF FLIP-CHIP MCMlBGA PACKAGING FOR OPTIMUM SOLDER JOINT RELIABLITY: T. Dixon Dudderar, Yinon Degani, B. J. Han, V. Reddy Raju, Lucent Technologies, 700 Mountain Avenue, Room IA105, Murray Hill, NJ 07974 It is well recognized that the thermal strains associated with material incompatibilities have been the root cause of many failures in both single chip microelectronic packages and in their soldered connections to circuit boards, etc. In so far as solder joints are concerned, flip chip interconnections and the joints under unleaded packages such as BGAs are in many ways "worst case"
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examples. This paper will describe in detail the unique choices of materials properties and encapsulation structure designed to provide a flip-chip soldered Multichip Module in a BGA package qualified for commercial telephone applications which was both highly reliable and cost effective.
9:40 am INVITED GLANCING-ANGLE ION BOMBARDMENT FOR MODIFICATION AND MONITORING OF SEMICONDUCTOR SURFACES: J.G.C. Labanda, S.A. Barnett, Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208; Lars Hultman, IFM, Linkoping University, S-581 83 Linkoping, Sweden
12:00 pm DAMAGE INTEGRAL APPROACH TO PREDICT FATIGUE DAMAGE OF FLIP CHIP SOLDER JOINTS IN FIELD CONDITIONS BASED ON ACCELERATED TESTS: MattA. Korhonen, S. Rzepka, Che -Yu Li, Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853
Using glancing-angle ion bombardment for surface modification rather than conventional near-normal incidence ions has the advantages of reducing damage and implantation projected ranges, reducing channeling, reducing sputtering, and preferentially removing surface asperities leading to flat surfaces. The effect of bombardment conditions on the surface morphology and perfection of GaAs(OOI), InP(OOl) and Si(OOl) surfaces are reported. Air-exposed surfaces were cleaned and smoothened to near atomic flatness without damage for optimal conditions: for example, with GaAs this was observed for 1000 eV Ar ions incident at 15° from the surface plane at a dose of2xlOl6 ions/cm2. For a given set of bombardment conditions, ion damage (observed as small dislocation loops in a 20-30 nm thick surface layer) decreased with decreasing ion incidence angle, and was eliminated below a critical angle. Sputtering yield, measured using film thicknesses and changes in reflection high-energy electron diffraction oscillations, decreased with decreasing incidence angle. The low sputtering yield and minimal damage make a glancingangle geometry ideal for real-time characterization by ion scattering spectroscopy. Surface composition measurements on single monolayers of InAs on GaAs showed that the glancing-angle Ar beam did not did not measureably change the In coverage over relatively long times.
At the advent of direct chip attach, thermal fatigue life of flip chip joints between the chip and FR-4 board is becoming a serious reliability concern. Differences in the temperature and/or in the coefficients of thermal expansion of the chip and substrate lead to significant stresses which lead to fatigue damage and eventual failure in interconnects. Conventionally, the solder lives have been estimated by Coffin-Manson type relations. However, this largely empirical approach becomes often inadequate when we compare thermal histories that a widely different, as they are in cases of accelerated thermal cycling, power cycling, and service conditions. In this study, we apply a damage integral approach, where the momentary fatigue damage rate is calculated based on the specified thermal loading and solder material constitutive equations, and then integrated over the entire history. We evaluate the stress, strain, and damage rate for three type of thermal histories, (1) accelerated thermal cycling, (ii) power cycling, and (iii) field conditions, and seek to correlate the ensuing damage in accelerated tests and typical field conditions.
10:20 am INFLUENCE OF PROCESSING PARAMETERS ON THE STABILITY OF MAGNETRON SPUTTERED DEPOSITED GROUP VI THIN FILMS: M.J. O'Keefe, Avionics Directorate, Wright Laboratory, WPAFB, OH45433
EVOLUTION AND ADVANCED CHARACTERIZATION OFTHIN FILM MICROSTRUCTURES V: Morphology Sponsored by: MSD Structures Committee, EMPMD Thin Films and Interfaces Committee Program Organizers: Eric P. Kvam, School of Materials Engineering, Purdue University, West Lafayette, IN 47907-1289; Steven M. Yalisove, Dept. Materials Science and Eng., HH Dow Bldg., University of Michigan, 2300 Hayward St., Ann Arbor, MI48109-1204; Eric P. Chason, Sandia National Labs., Dept. 1112, MS 1415, PO Box 5800, Albuquerque, NM 87185
Wednesday, AM February 12, 1997
Sputter deposition of metallic thin films is commonly used to fabricate electrically conducting contacts and interconnects on semiconductor devices. For military applications, the stability of the patterned metal under adverse environmental conditions, such as prolonged exposure to elevated temperatures, can significantly influence the reliability of the device. In this investigation the influence of magnetron sputter deposition processing parameters on the stress, adhesion, resistivity and crystal structure Group VI (i.e .. Cr, Mo, W) thin films was studied. The influence of elevated temperature on the stability of the films was evaluated, in part, using a Tencor Flexus-2900 thin film stress measurement system. Results from the study indicate that minor changes in processing conditions can significantly affect the as-deposited and elevated temperature properties of the films.
Room:340C Location: Orlando Convention Center
Session Chairs: A. Zangwill, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332; S.A. Barnett, Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208
10:40 am BREAK 11:00 am INVITED KINETIC ROUTES TO COHERENT ISLANDS: Andrew Zangwill, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332; Harvey T. Dobbs & Dimitri D. Vvedensky, Blackett Laboratory, Imperial College, London SW7 2BZ, UK
9:00 am INVITED LOW-ENERGY ION AND HYPERTHERMAL NEUTRAL BEAMS FOR FILM GROWTH: EFFECTS ON NUCLEATION, MICROSTRUCTURE EVOLUTION, EPITAXIAL THICKNESS, ROUGHENING,AND STRAIN RELAXATION: Joe Greene, Materials Science Dept., Univ. of Illinois, Urbana, IL61801
The Stranski-Krastanov growth morphology ofheteroepitaxy consists of three dimensional islands that nucleate on top of a few strained layers of film material that wet the substrate. It is well understood on the basis of energetic considerations that such islands can be entirely free of misfit dislocations, i.e., coherent, until they grow rather large. But the kinetic processes that govern their formation are far less clear. Motivated by recent scanning tunnelling microscopy studies of this phenomenon for Ge/Si( 111), InAs/GaAs(OO I), and InSb/GaAs(OO I), we present a combination of atomistic Monte Carlo simulations and mean-field rate theory designed to reveal the kinetic pathways to coherent islands. Particular emphasis is placed on the role of interface alloying and the dynamics of the wetting layers.
Low-energy (10-100 eV) ion and hyperthermal neutral irradiation during filmgrowth from the vapor phase are used to provide new chemical reaction pathways, modify film growth kinetics, and, hence, controllably alter film properties. During low-temperature epitaxial growth from hyperthermal Si beams, critical epitaxial thicknesses were increased by up to an order of magnitude over those obtained with MBE due to enhanced interlayer mass transport and more effective filling of interisland trenches. For heteroepitaxial Si1-xGex growth on Si(OOl), AFM and XTEM studies show that strain-induced roughening, which occurs at elevated growth temperatures, is strongly suppressed at Ts between 300 and 400°C, with no indication oflow-temperature kinetic roughening. The use of low-energy primary- ion beam sources in which ion energy and ion/neutral flux ratios can be varied independently during the growth of AI, Cu, and TiN polycrystalline layers on Si02 will be shown to provide dramatic differences in nucleation rates, mosaicity, preferred orientation, strain, and microstructure evolution.
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11:40 am MORPHOLOGICAL INSTABILITIES AND EVOLUTION OF THIN FILMS: H. Wong, P.W. Voorhees, MJ. Miksis, S.H. Davis, Northwestern University, Evanston, IL 60208
the crack-wake ligaments resulted in lower fracture resistance in materials under cyclic loading than those under monotonic loading. *Supported by the AFWL Materials Directorate through Contract No. F33615-92-C-5951. 9:20am MICROMECHANICS OF FATIGUE AND FRACTURE IN LAMELLAR TiAl: Bimal K. Kad, Robert J. Asaro, Department of Applied Mechanics & Engineering Science, University of California-San Diego, La Jolla, CA 92093
The driving force for morphological evolution of thin films increases as the size of the films decreases. Thus, to further miniaturize microelectronic and optoelectronic devices, the morphological instability and evolution of thin films need to be understood. We study the linear instability of two film shapes commonly encountered in experiment: a strip on a substrate, and a hole in a uniform film on a substrate. We assume that the instability is driven by capillarity and the film evolves via surface diffusion. The contact angle is fixed at a value between 0 and 180 degree. We find that both film shapes are unstable to certain disturbances. We also simulate numerically the evolution of the film shapes triggered by an unstable disturbance to reveal new stable steady states. The implications of these results on the long term stability of solidfilm devices will be discussed. *Supported by NSF and DOE.
Finite element based numerical procedures, incorporating physically based crystal plasticity models, are employed to study the evolution of non-uniform deformation, under monotonic and fully reversed (R=-l) cyclic loadings, in lamellar TiAl microstructures. The impetus for such efforts is to gather fundamental insight into microstructure sensitive deformation mechanisms, and to extract additional information, not obtainable from traditional mechanical property measurements. Such an effort is particularly desirable to help track various aspects of plastic anisotropy of specific layers, and microconstituents as implicit in polycrystalline aggregates. Computational efforts are directed to address constant strain, as well as constant stress amplitude loading schemes in the low cycle fatigue regime. Irreversible deformation twinning effects are fully accounted for in the fatigue maximum of 100 cycles. We will present several examples of experimentally observed, and numerically computed results, to identify hot spots for strain localization in monotonic and fully reversed loadings, and prescribe microstructural remedies to alleviate such effects.
FUNDAMENTALS OF GAMMA TITANIUM ALUMINIDES V: Microstructure-Property Relationships-Fatigue, Fracture and Damage Modeling Sponsored by: MSD Flow & Fracture and Phase Transformations Committees Program Organizers: Kwai S. Chan, Southwest Research Institute, San Antonio, TX 78228-0510; Vijay K. Vasudevan, Dept. of Materials Science &Engineering, University of Cincinnati, Cincinnati, OH 45221-0012; Young-Won Kim, UES, Inc., Dayton, OH 45432-1894 Wednesday, AM February 12, 1997
9:40am MICROCRACK NUCLEATION AND PROPAGATION IN TiAI: Zhe
lin, George T. Gray III, Los Alamos National Laboratory, Los Alamos, NM 87545
Room: 330E Location: Orlando Convention Center
Microcrack nucleation and propagation in a PST-TiAI crystal and a duplex y -TiAI alloy at high and quasi-static strain rates and temperatures from 196°C to 12oo°C was investigated under compression loading. In PST crystals, two microcracking habit planes, the {II O} planes for translamellar cracking and the (111) interface plane for interlamellar cracking, were observed when the <110> directions in the lamellar interfaces were perpendicular to the loading direction. However, three microcracking habit planes were observed when the <321> directions in the lamellar interfaces were perpendicular to the loading direction. Most microcracks were found to nucleate at/near the lamellar interfaces and propagate into the laths along their habit planes to form translamellar cracks. In the fine-grained duplex microstructure, both grain interior microcracks and grain boundary microcracks were observed. The grain interior microcracks occurred primarily within the equiaxed grains and appeared to be formed by shear displacements along the maximum shear planes. An attempt to correlate the microcrack formation with the crystal deformation modes and crystal orientations is made and the microcrack nucleation and propagation mechanisms in TiAI are analyzed.
Session Chairpersons: Robert O. Ritchie, Dept. of Materials Science and Mineral Engineering, University of California, Berkeley, CA 94720; Kwai S. Chan, Southwest Research Institute, San Antonio, TX 78228-0510
8:25 am OPENING REMARKS 8:30 pm INVITED FATIGUE AND FRACTURE OF TiAI PST CRYSTALS: Y. Umakoshi, Department of Materials Science and Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565 Japan Orientation and temperature dependences of cyclic hardening, fatigue life and fracture mode of TiAI PST crystals were investigated. Deformation twins and vein-like structure containing high density of ordered dislocations were formed below 500°C depending on the type of ordered domain in the yphase. The vein-like structure was responsible for strong cyclic hardening, while deformation twins were formed at the initial stage of fatigue and did not contribute the hardening. Formation of twins and vein-like structure was suppressed at 700°C and fatigue life rapidly decreased showing cyclic softening. Deformation twins produced extrusions on the specimen surface and played an important role for crack initiation and fatigue failure. Effect of additional third elements such as V and Nb on the cyclic hardening and fatigue life will also be presented.
10:00 am BREAK 10:10 am INVITED DAMAGE MODELING OF GAMMA TITANIUMALUMINIDES: M.l. Pfuff, B.D. Wittkowsky, GKSS-Forschungszentrum Geesthacht GmbH and SFB 371, Institut flir Werkstofforschung, Max-Planck-Str., D-211502 Geesthacht, Germany A common feature of Gamma TitaniumAluminides is the heterogeneous character of their microstructure. This heterogeneity causes failure processes to be progressive, with a continuous transition between a diffused and a localized mode of damage, the relative contribution of both modes to failure being determined by the degree of randomness of microstructural heterogeneity. At room temperature the failure is preceded by the formation of microcracks which control the strain to failure either by microcrack coalescing or by the nucleation of a critical-size crack. The size and local distributions of microcracks reflect the heterogeneity of microstructure, and depend on stress state, size and geometry of the specimens. The results of model calculations are presented, which are based on mesoscale lattice of beams models used in statistical physics in order to treat the relationships between microcracking and failure. A comparison of the numerical results to the experimental findings emphasizes the significant role microstructural heterogeneity plays during the failure process of Titanium Aluminides.
9:00am FUNDAMENTAL ASPECTS OF FATIGUE FRACTURE IN TiAl ALLOYS: Kwai. S. Chan, Southwest Research Institute, San Antonio, TX 78238; D.S. Shih, McDonnel Douglas Aerospace, SI. Louis, MO 63166 The fatigue mechanisms in a TiAl alloy heat-treated to the lamellar and equiaxed microstructures were studied to determine the effects of microstructure on the initiation of microcracks and their subsequent growth into large cracks. The results indicated microcracks initiated at grain/colony boundaries and at slip bands. Most microcracks were arrested after nucleation, but a few grew at K below the large crack thresholds. The populations of nonpropagating and propagating cracks varied with life fractions. Ligaments in the wake of a fatigue crack were prone to fatigue failure. The destruction of
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10:40 am LARGE-SCALE MOLECULAR DYNAMICS SIMULATIONS OF THREE-DIMENSIONAL FRACTURE IN A y-TiAI ALLOY: S.J. Zhou, D.M. Beazley, P.S. Lomdahl, B.L. Holian, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545
11:40 am FINITE ELEMENT ANALYSIS OF GRAIN BOUNDARY CAVITATION IN FULLY LAMELLAR TITANIUM ALUMINIDE INTERMETALLIC ALLOY: Anirban Chakrabort, James C. Earthman, Materials Science and Engineering, University of California, Irvine CA 92697
We have carried out new large-scale molecular-dynamics (MD) simulations of fracture in a titanium-aluminum alloy, using the methods we developed in previous MD simulations, where we studied dislocation emission from a crack in a three-dimensional thin film of embedded- atom-method copper, comprising 35 million atoms. In that first study, we observed a variety of dislocation emission modes in a sample that was sufficiently thick that we could be sure that the results did not depend on the thickness. The sequence of dislocation emission in the crack blunting process strongly depends on the crystallographic orientation of the crack front and differs strikingly from anything previously conjectured. This finding is essential to establish a precise dislocation emission criterion (i.e. intrinsic ductility criterion). We will report on similar calculations for the TiAI system, with emphasis on the crack-tip plasticity and interaction between a crack and lamellar interfaces.
Creep constrained grain boundary cavitation in fully lamellar form of titanium aluminide intermetallic alloy has been studied using finite element techniques. Two different forms of fully lamellar models are considered. Cavitation is modeled in the presence of grain boundary sliding for the case of straight former grain boundaries and cavitation without grain boundary sliding is considered for fully lamellar microstructure with serrated former grain boundaries. Effect of interaction of cavitating facets on rupture life has been studied. A comparison between the fully lamellar forms and a dual phase equiaxed microstructure having the same phase ratio (a.,/y) is also made to examine the relative susceptibility of these microstructures to high temperature damage.
11:00 am ATOMISTIC SIMULATIONS OF FRACTURE IN TiAl: Julia Panova, Diana Farkas, Department of Materials Science and Engineering, Virginia Polytechnic Institute, Blacksburg, VA 24061 Atomistic simulations of fracture in Llo TiAI were carried out using EAM interatomic potentials and molecular statics. We studied the behaviour of semiinfinite cracks under mode I loading in different crack-tip orientations. From the [1-10](11) crack tips we observed extensive dislocation emission, involving the formation of several planar faults, such as APB, CSF and SISF. We found that the edge dislocations with 112[110] Burgers vector that were emitted from [001](10) cracks were very compact and mobile. No planar fault formation was involved in the dislocation emission from this crack geometry. Cracks with [001](00) orientation were observed to cleave near the Griffith value of loading in a purely brittle manner. 11:20 pm ON THE CORRELATION BETWEEN MECHANISMS OF PLASTICITY AND FRACTURE IN Ti-48 At. % AlALLOYS: J.M.K. Wiezorek, P.M. DeLuca, MJ. Mills, H.L. Fraser, Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210 The technologically most relevant two-phase (Y-fJ) TiAI compounds contain a significant volume fraction of morphologically lamellar grains. Interestingly, a change in the predominant fracture mode has been observed from transgranular at room temperature to intergranular at elevated temperature for both equiaxed and duplex microstructures. It has previously been suggested that the segregation of alloying additions and/or impurities to grain boundaries during exposure at elevated temperature could be responsible for this change in fracture characteristics. However, the origin for the observed fracture mode change has not been ascertained to date. In this study binary Ti48at. %Al alloys of equiaxed, duplex and fully lamellar microstructure have been deformed in tension to various degrees of strain up to fracture, at both room and elevated temperature. The active fracture modes have been identified by SEM fractography. Moreover, the deformation modes active in these two phase TiAI compounds during tensile loading have been determined by TEM. Thin foils for the TEM characterization have been obtained from cuts perpendicular and parallel to the load axis at various locations in the gage sections as close as 10 !lm from the actual fracture surface. The results of these investigations are discussed specifically with respect to the origin of the reported fracture mode changes, and the mechanisms fundamentally underlying the plasticity and fracture of these (y-a) TiAI compounds. This work has been supported by a grant from the National Science Foundation with Dr. Bruce MacDonald as program manager.
GLOBAL EXPLOITATION OF HEAP LEACHABLE GOLD DEPOSITS V: Laboratory Evaluation of Heap Leachability Sponsored by: EPD Process Mineralogy, Precious Metals, Aqueous Processing Committees; Newmont Mining Corporation, Denver, CO Program Organizers: Donald M. Hausen, Consultant, 1767 S. Woodside Dr., Salt Lake City, UT 84124; David Dreisinger, University of British Columbia, Dept. of Metals & Materials Eng., 309-6350 Storres Rd., Vancouver, BC V6T 124, Canada; Richard Kunter, Advanced Science, Inc., 405 Irvine St., Suite 401, Lakewood, CO 80278; William Petruk, CANMET, 555 Booth St., Ottawa, Ontario J1 A 081; Richard D. Hagni, University of Missouri-Rolla; Dept. of Geology & Geophysics, Rolla, MO 65401
Wednesday, AM February 12, 1997
Room: 231C Location: Orlando Convention Center
Session Chairpersons: Jan D. Miller, Professor, Univ. of Utah Met. Engineering Dept., Salt Lake City, UT; and Philip Thompson, President, Dawson Metallurgical Laboratories, Inc., Salt Lake City, UT
8:30 am KEYNOTE PROJECTING LABORATORY AND PILOT TEST DATA INTO OPERATING REALITY: Robert R. Beebe, Consultant, Former Vice President, Newmont Mining Corporation, P.O. Box 32048, Tucson, AZ 857512048 Laboratory and pilot-scale tests are almost invariably required before metallurgical development can proceed. Difficulties with sampling, as well as with classical chemical and physical scale-ups are normally anticipated and relatively well-understood, but more subjective factors also come into play, including misunderstandings of the operating scheme chosen, wrong "lessons" learned from similar operations, failures to handle data appropriately, and even arbitrary intervention by management. The paper examines some of these subjective factors and suggests ways to guard against them. Several anecdotal case studies are used as examples, including when and where to heap leach or to mill specific types of gold ore. 9:05 am PREDICTING PRODUCTION HEAP LEACH CYCLE TIMES FROM LABORATORY COLUMN TEST DATA: Philip Thompson, President, Dawson Metallurgical Laboratories, Inc., Murray UT 84157-0685 Carefully planned Laboratory test programs provide valuable data regarding the amenability of low grade gold ores to heap leaching. Several problems are encountered in laboratory column simulation of gold heap leaching. A problem most commonly associated with column testwork is the limit on test column height. Most laboratories use a 3 to 5 meters (or 9 to 15 feet) high column as a standard test due to building ceilings and sample size limitations, etc. The problem with this column height is that most commercial heaps are at least 10 to 15 meters (25-35 feet) high, with some heaps reaching 100-200 meters (225-450 feet). This paper presents a data interpretation method
whereby the data from test columns of virtually any height can be used to predict a first approximation leach cycle time for commercial heaps. Other important factors, e.i. sample preparation protocol, preliminary bottle roll testing, column diameter requirements, and leach solution analysis, are also discussed.
HIGH TEMPERATURE SUPERCONDUCTORS V: BSCCO Conductor Development Sponsored by: Jt: EMPMD/SMD Superconducting Materials Committee Program Organizers: U. Balachandran, Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439; Paul J. McGinn, University of Notre Dame, Notre Dame, IN 46556
9:25am AGGLOMERATION PRACTICE AT KENNECOTT BARNEYS CANYON MINING COMPANY, BARNEY CANYON, UT: Philip L. LeHoux, Chief Metallurgist, Kennecott Barneys Canyon, Magna, UT 84044
Wednesday, AM February 12, 1997
Kennecott Barneys Canyon Mining Company has been a gold heap leaching facility in operation since 1989. In 1994, a flotation plant was commissioned to remove sulfide minerals from refractory sulfide ore. Tailings from the plant are mixed with oxide heap leach material in order to produce a geotechnically stable agglomerate from which the gold is leached and recovered in a conventional heap leach cyanidation process. The experience to arrive at an effective blending methodology is discussed.
Room: 315A Location: Orlando Convention Center
Session Chairpersons: L.R. Motowidlo, IGC Advanced Superconductors, Waterbury, CT; J. Schwartz, National High Magnetic Field Laboratory, Tallahassee, FL
8:30 am INVITED Bi-2212/Ag HTSC MAGNETS FOR HIGH FIELD GENERATION: H. Kitaguchi, H. Kumakura, K. Togano, T. Kiyoshi, K. Inoue, National Research Institute for Metals, 1-2-1 Sengen Tsukuba 305, Japan; M. Okada, K. Tanaka, Hitachi Ltd., 7-1-1 Ohmika, Hitachi 319-12, Japan; J. Sato, Hitachi Cable Ltd., 3550 Kidamari, Tsuchiura 300, Japan
9:50 am BREAK 10:00 am ZARAFSHAN NEWMONT J.V. MURUNTAU HEAP LEACH OPERATION, UZBEKISTAN: Sevket Acar, Senior Metallurgist, Newmont Metallurgical Services, Salt Lake City, UT 84108; Tim Acton, Newmont Gold Company, One Norwest Center, 1700 Lincoln St., Denver CO 80203
Two kinds of compact superconducting magnet have been fabricated with Bi-2212/Ag multifilamentary tapes. These magnets are stacked double pancake type and made by a wind and react process. One of them has the dimensions of 55 mm in height, 49 mm in outer diameter, and 12.5 mm in clear bore. The magnet was inserted in a 21-T-class superconducting magnet system and tested in various field at 4.2 K. In zero bias field, the magnet carries 400 A (criterion: 10. 13 Wm) and generates 2.5 T. In the bias field of 21.1 T, the magnet successfully generates 1.76 T with the current of 281 A, i.e., the total field reaches 22.8 T which is the highest field ever achieved with a superconducting magnet. Transport current properties in bias fields for the other magnet with the outer diameter over 90 mm are also reported.
ZarafshanlNewmont is a 50125125 joint venture between Newmont Gold and two entities of the Republic of Uzbekistan, the State Committee for Geology and Mineral Resources, and Navoi Mining and Metallurgical Combinat. ZarafshanlNewmont joint venture consists of a heap leaching operation, which will process 220 million metric tons of existing stockpiles ofIow-grade oxide ore averaging 0.036 oz AuIT from the Muruntau mine. Net recovery over the 17-year life of the project is expected to be 4.8 million ounces of gold. The plant started in October 1993, and the operations commenced on May 25, 1995. The crushing plant consists of four stages of crushing and screening to produce 95% -3.35 mm product followed by heap leaching and gold recovery by Merrill-Crowe process. The Dore metal is refined at the Muruntau refinery. All gold produced by the joint venture is sold on the world market.
8:50 am INVITED EFFECTS OF MECHANCIAL STRAIN ON Bifir2CaC~O/AgX COMPOSITE CONDUCTORS: J. Schwartz, B.C. Amm, H. Garmestani, Y. Hascicek, D.K. Hilton, National High Magnetic Field Laboratory, Tallahassee, FL 32310
10:25 am PROCESS MINERALOGY OF HEAP LEACHABLE ORE DEPOSITS: J.G. Davidson, N.A. McKay, Lakefield Research Ltd., Lakefield, Ontario KOL2HO
The development of powder-in-tube Bi,Sr,Ca".,)CU.Ox technology has progressed such that high critical current density (J) conductors are produced by many researchers. An important issue that remains, however, is the effects of mechanical strain. While it is evident that large strains induce irreversible damage, applications may be limited by fatigue at low strain values due to crack propagation. Here we report upon the effects of cyclic fatigue on Je of Ag and Ag-alloy clad Bi,Sr,CaCupx as measured by electrical transport and magnetic hysteresis. Measurements of the constituent and composite mechanical properties and bulk Bi,Sr,CaCu,Ox fracture toughness are also reported. As Je may be limited by microcracks before straining, studies of crack propagation and mechanical strain effects may also provide insight into the fundamental limits to transport Je• Results are interpreted within this framework as well.
Heap leachable ore deposits from many countries have been submitted for process mineralogical evaluation and laboratory testwork. Numerous factors must be addressed and integrated by the mineralogist, geologist, metallurgist and engineer. Projects encompass grass roots exploration, preliminary petrographic analysis, predictive and process mineralogy, dye penetration analysis of rocks and thin sections, metallurgical beneficiation testwork and plant optimization studies. The significance of mineralogical factors, such as geological controls, degree of oxidation, dye amenability, liberation, deleterious minerals, refractoriness, and the impact of mineralogy on gold recovery and process considerations, will be presented.
9:10 am INVITED PROPERTIES AND PROCESSING OF MULTIFILAMENTARY PIT FORMED USING THE CTFF PROCESS: M.D. Sumption,' S.x. Dou,' N. V. Vo,' and E.W. Collings.' 'MSE, The Ohio State University, Columbus, OH, USA; 'CSEM, The University ofWollongong, NSW, Australia Multifilamentary Bi2212 strands with up to 37 filaments have been formed using Continuous-Tube-Forming-Filling (CTFF). The CTFF process is used for the initial monocore, which is then res tacked via a conventional PIT process, and these strands are then rolled into tapes. A sterling Ag outer shell is used, but the matrix region used pure Ag. Self field Je at 4.2 K is 9.16 kA/cm'. The resulting filaments are aspected, with dimensions 7.5 x 370 mm. A vibrating sample magnetometer has been used to measure M-H loops (losses). Losses were measured, and it was possible to separate out; (i) critical state losses, (ii) eddy current losses, (iii) logarithmic type creep influences on the losses, and (iv) exponential type creep influences on the losses.
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9:30 am INVITED Bi,Sr,Ca,Cu,0x MULTIFILAMENT WIRES AND TAPES FOR MAGNET APPLICATIONS UP TO 20 K: L.R. Motowidlo, G. Galinski, G.M. Ozeryansky, F. Krahula, R.S. Sokolowski, IGC Advanced Superconductors, Waterbury, CT 06704
9:00am TECHNOLOGY ADVANCEMENTS IN RESISTANCE WELDING OF ALUMINUM FOR AUTOMOTIVE APPLICATIONS: Chon L. Tsai, Ohio State University, 1960 Kenny Road, Columbus, OH 43210-1063 A strategic plan for advancing the resistance welding technology for aluminum based materials will be presented. The purpose of tbis work is to identify the critical issues associated with tbe current technology and to develop innovative approaches to advancing tbe technology for automotive applications.
Long lengtbs of Ag-alloy sheatbed Bi,Sr,Ca,Cu,Ox (2212) multifilament wires and tapes have been fabricated and heat treated. Sample lengtbs of one to two meters are cut after melt processing and wound into standard holders used to test NbTi for MRL The performance characteristics of tbe 2212 conductors, tbat is the critical current density, tbe overall critical current density, and tbe n-values of a number of samples as a function of tbe applied magnetic field (0-9 Tesla) at 4.2 K will be reported. Work supported by IGC Advanced Superconductors.
9:20am JOINING ALUMINUM MATERIALS USING ULTRASONIC IMPACTORS: Glenn Freitas, Aztex, Inc., 303 Bear Hill Road, Waltbam, MA02l541196
9:50am IMPROVEMENTS IN BizSr,CaCu,Ox CONDUCTOR VIA DOPANTS: J. Schwartz,' A. Bhargava,' B. Boutemy,l and W. Wei,' 'National High Magnetic Field Laboratory, 1800 E. Dirac Dr., Tallahassee, FL 32310; 'University of Queensland, Brisbane, Qld 3072, Australia
The joining approach being presented here uses ultrasonic impactors to insert steel pins directly to join aluminum to aluminum or aluminum to composite materials. The concept does not require any machining or preparation of tbe aluminum components to be joined. Using tbis process, inexpensive mill products, sheet, extrusions, etc. can be used directly witbout additional machining to create complex structures. More importantly, tbis process will produce very high performance structures similar to tbe weight efficiency of co-cured carbon composites at a fraction of tbe cost.
An important characteristic of high temperature superconducting materials is tbe ability to carry large J, at high magnetic field. As a result, tbe NHMFL anticipates using HTS conductor for tbe highest field region of tbe 1 GHz NMR magnet system. Two obstacles to high field J, over long lengtbs are poor flux pinning and carbon-induced bubbling and tunneling. Here we report progress on these two challenges via fine-scale additives to tbe starting powder. To address tbe flux pinning issue, we are investigating nano-scale MgO additions. By growing tbe 2212 grains around tbe MgO particles, pinning centers are directly incorporated in tbe superconducting grains. To prevent bubbling and tunneling from CO, gas tbat forms during melt processing we are investigating Ba-O additions. By trapping tbe carbon in BaC0 3, CO, formation is prevented. We report magnetic and electrical measurements of J" extensive microscopy, and x-ray diffraction of tapes formed with tbese approaches.
9:40am THERMAL SPRAYING OF ALUMINUM AS AN ADHESIVE BOND PRETREATMENT: Guy Davis, DACCO SCI, Inc., 10260 Old Columbia Road, Columbia, MD 21046 DACCO SCI, Inc., (DSI) evaluates two-wire arc tbermal spray coatings as an adherent pretreatment. This work will build on previous experience of DSI with plasma spray coatings as treatments for aluminum adherents. These treatments exhibit performance equivalent to tbe best chemical treatments but are environmentally benign. Thermal spray processes generate no gaseous or liquid wastes and minimal solid wastes. Additionally, tbey are robust processes tbat are capable of being preformed on localized areas in tbe field or depot during repairlrefurbishment operations. Alternatively, parts may be sprayed in advance and stored indefinitely prior to use. The two-wire arc process is considerably cheaper and less complicated tben tbe plasma spray process.
10:10 am INVITED CRITICAL CURRENT DENSITY, HYSTERESIS LOSSES AND STRUCTURE ALONG HTSC WIRES: P. V. Bratukhin, LA. Rudnev, Moscow State Engineering Physics Institute (Technical University), Kashirskoe sh. 31,115409, Moscow, Russia
10:00 am BREAK Critical current density hysteresis and losses were measured along Bi-HTSCI Ag wire. X -ray diffraciton analysis of tbe same samples allowed to observe structure features connected witb critical current distribution along wire lengtb.
10:20 am UTILIZATION OF RECYCLED AND UNRECOVERABLE ALUMINUM SCRAPS IN MANUFACTURING CELLULAR CONCRETE: Jiann- Yang (Jim) Hwang, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931-1295
INNOVATIONS IN ALUMINUM I
In manufacturing cellular concrete, finely divided metallic aluminum powder is used to react witb hydroxides, forming minute bubbles of hydrogen gas throughout tbe concrete mixture. Traditionally, high cost pure aluminum powder is used in manufacturing cellular concrete which greatly increases tbe cost of tbe products. To use traditionally unrecoverable aluminum wastes, a pretreatment process will be employed to separate magnetic metal and dirt from the stream and to grind tbe main stream waste into aluminum powder. The effect of moisture content in tbe waste on grinding quality will be examined and evaluated. The effects of tbe amount of recycled aluminum and tbe alkalies concentration in the mixture will be studied. Finally, tbe mechanical and physical properties of tbe cellular concrete will be examined and evaluated.
Sponsored by: LMD Aluminum Committee Program Organizer: Robin Conger, Pacific Northwest National Laboratory, P.O. Box 999, K8-11, Richland, WA 99352 Wednesday, AM February 12, 1997
Room: 232B Location: Orlando Convention Center
Session Chairperson: Sara Dillich, U.S. Department of Energy, 1000 Independence Ave. S.w., Mail Stop 6A-116, Washington, DC 20585
8:30am ALUMINUM INDUSTRY/GOVERNMENT PARTNERSHIP FOR COLLABORATIVE R&D: Hank Kenchington, U.S. Department of Energy, 1000 Independence Avenue S.w., Washington, DC 20585
10:40 am SOLID-STATE SPRAY FORMING OF ALUMINUM NEAR-NET SHAPES: Ralph Tapphorn, Howard Gabel, Innovative Technology, Inc., P.O. Box 8392, Las Cruces, NM 88006
In 1996, tbe U.S. Department of Energy signed a contract witb the aluminum industry to establish a research partnership for collaborative research and development. The partnership will identify appropriate areas for joint R&D that can improve the quality of life in the United States and promote the manufacture of competitively priced and ecologically sustainable aluminum products. To implement tbe partnership, DOE will work witb tbe aluminum industry to develop a technology roadmap that delineates and prioritizes tbe technological needs for global competitiveness into tbe 21 st century.
Solid-state spray forming (SSF) is a promising new technology for saving energy in tbe production of aluminum near-net shapes. Because SSF does not require melting of the feedstock, IT! anticipates producing aluminum parts at significantly lower energy input tban conventional alternatives require. The light weight, high strengtb, and recyclable features of tbese parts will propa-
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gate this energy savings through the life of the parts. SSF is potentially applicable to the production of aluminum metal matrix composites, also in nearnet shapes; and provides the compelling possibility of producing MMCs with non-traditional strengthening phases, including nonophase particles. 11:00 am THE ALUMINUM INDUSTRY OF THE FUTURE: John Green, TheAluminumAssociation,900 19th Street, N.W., Washington, DC 20006 On behalf of the U.S. aluminum industry, Dr. Green will describe the industry's vision of the future as published in The Aluminum Association's report titled "ALUMINUM INDUSTRY: INDUSTRY/GOVERNMENT PARTNERSHIPS FOR THE FUTURE." The report describes how the aluminum industry will maintain and build its competitive position in worldwide markets through research and development. Dr. Green will also solicit comments on the newly developed technology roadmap for the aluminum industry.
INTERNATIONAL SYMPOSIUM ON RHENIUM AND RHENIUM ALLOYS V: Processing, Structure and Properties of Rhenium and Its Alloys (Part I) Sponsored by: SMD Refractory Metals Committee and MDMD Powder Materials Committee Program Organizer: Dr. Boris D. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036
Wednesday, AM February 12, 1997
Room: 232C Location: Orlando Convention Center
Session Chairpersons: Prof. Gerhard EWelsch, Materials Science and Engineering, Case Western Reserve University, 514 White Bldg., Cleveland, OH 441067204; Michael Kangilaski, Advanced Methods and Materials, 1798 Technology Drive, #251, San Jose, CA 95110
8:30am STRESS- RUPTURE STRENGTH OF RHENIUM AT EXTREMELY HIGH TEMPERATURES: B. Fischer, D. Freud, Jena Polytechnic, Tatzendpromenade I b, D-07745 Jena, Germany; D. Lupton, w.e. Heraeus, GmbH, Heraeusstrasse 12-14, D-63450 Hanau, Germany For the safe high - temperature use of rhenium we have the task of measuring the stress - rupture strength at extremely high temperatures. For stress - rupture tests on high melting metals we designed and built a test system that allows measurements to be made at temperatures up to 3,OOO°C under an inert atmosphere. Using this test unit we determined stress - rupture diagrams of rhenium in several material conditions in the range of 2, 100°C to 3,OOO°e. The discussion of the measured values is based on me/allographic test results, scanning electron microscopy (SEM) images of rhenium samples after the stress - rupture tests, the determination of trace impurities using secondary ion mass spectrometry (SIMS) and the results of the residual gas analysis of rhenium. 8:50am INFLUENCE OF COLD ROLLING ON PLASTIC RESPONSE OF PM AND CVD RHENIUM: G. Subhash, B.J. Koeppel, Mechanical Engineering-Engineering Mechanics Department, Michigan Technological University, Houghton, MI 49931 Plastic response of rhenium (Re) produced by powder metallurgy (PM) and chemical vapor deposition (CVD) was investigated under uniaxial compression. The PM Re was also cold rolled by 50% and 80% reduction (denoted as PM50 and PM80, respectively) in thickness. Both cold rolled and CVD Re have been found to have a strong basal texture. Cylindrical specimens from the above four types of Re (i.e., PM, PM50, PM80 and CVD) were subjected to uniaxial compressive loads in the range of strain rates from Ix10·3 S·I to 9.5 X 103 S·I. Low strain rate experiments were performed in an Instron machine and high strain rate experiments were performed in a split Hopkinson pressure bar. The deformed specimens were metallographically prepared and
etched to study microstructural changes and identify the micromechanisms of deformation. Rhenium exhibited a two stage hardening in its plastic response. It revealed a high strain hardening rate and a strong strain rate sensitivity of flow stress. Increased cold work in the PM Re resulted in an increase in the initial yield stress with a concurrent reduction in the hardening rate and failure strain. CVD Re exhibited a distinctly higher hardening rate and ultimate flow stress than the above cold rolled PM Re. After accumulating a certain amount of plastic strain, the deformation in the specimens localized leading to formation of shear bands at an angle to the loading axis. Fracture immediately followed the shear bands. Twinning was found to be a dominant deformation mode in both PM and CVD Re. Extensive twinning was observed in larger grains of CVD Re. Twins in fine "rained PM specimens were less common and occurred primarily in the regions close to the shearband. Based on the experimental results and microscopic investigations, the micromechanisms of deformation responsible for the observed behavior of Re will be discussed. 9:10am STEADY STATE CREEP RATES OFW-4Re-0.32HfC: John 1. Park, MS E506, Los Alamos Laboratory, Los Alamos, NM 87545; Dean L. Jacobson, Dept. of Chern, Bio. and Materials Engineering, Arizona State University, Tempe, AZ 85287-6006 Second phase particle-strengthened tungsten alloy, tungsten-4w/o rhenium0.32w/o hafnium carbide (W-4Re-0.32HfC), was creep-tested at temperature ranges of 2200 to 2400K and stress ranges of 40 to 70 Mpa in a vacuum of better than 1.3 x 10-6 Pa (1 x 10-8 torr). The resulting steady state creep rates were applied to three particle-strengthened creep models and compared. The three creep models were Ansell-Weertman, Lagneborg, and Roesler-Arzt. None of the three models precisely predicted the steady state creep rates ofW-4Re0.32HfC. However, the recovery creep model of Lagneborg qualitatively fit the creep rates. 9:30am TEMPERATURE AND LOAD DEPENDENCE ON THE HARDNESS OF ROLLED RHENIUM SHEETS BEFORE AND AFTER ANNEALING: K. Peter D. Lagerlof, Seog-Young Yoon, Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106; Boris D. Bryskin, Jan-C. Carlen, Rhenium Alloys, Inc., Elyria, P.O. Box 245, OH 44036 The microhardness of rolled rhenium sheets was determined as a function of indentation load and temperature. Sheets of rhenium were produced from rhenium metal powder by pressing, presintering and sintering, followed by cold rolling. After a production anneal to define the structure of the starting material, sheet samples were deformed using cold rolling to about 30% strain in 5% deformation increments without intermediate annealings. One of the deformed samples was annealed at 1600°C for 20 minutes. The temperature dependence of the microhardness between room temperatures and 900°C (using 50° increments) was studied using a Nikon Model QM hot hardness tester equipped with a Vickers indentor. The load dependence of the microhardness was investigated using both a Vickers anda Knopp indentor, and the indentation size effect (lSE) was best explained using the normalized Meyer's law. The hardness of the annealed rhenium sheet approached that of the as-rolled sheets at large indentation loads because of workhardening under the indentor during indentation. The hardness at "zero load" (obtained from extrapolation of the load dependence of the hardness) suggests that the hardness is controlled by two different mechanism having different thermal activation. The activation energy of the mechanism controlling the hardness at low temperatures is approximately 0.02 e V whereas that at high temperatures is approximately 0.5 eY. The transition temperature between the two controlling mechanisms occurs at about 250°e. 9:50 am BREAK
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223K. That sheets manifested the fracture toughness in the rolling plane by factor of five higher as compared with the initial sheets.
A REVIEW OF THE INTERACTION OF COLD WORK AND ANNEALING IN THE PROCESSING OF RHENIUM: O.S. Es-Said, Mechanical Engineering Department, Loyola Marymount University, Los Angeles,CA 90045; R.H. Titran, NASA Lewis Research Center, 21000 Brookpark Road, Mail Stop 49-1, Cleveland, OH 44135
LIGHT WEIGHT ALLOYS FOR AEROSPACE APPLICATION IV: Session IV: Ti Alloys
Twinning is a dominant deformation mode in both PM and CVD rhenium. Although severe work hardening occurs during cold rolling, extensive twinning enables rhenium to retain moderate ductility. It is believed that as the deformation process progresses, twinning becomes the predominate mode contributing to the plastic deformation of rhenium. At all deformations, the hardness and strength of rhenium decreases at annealing temperatures corresponding to the temperature of the onset of recrystallization. It is known that the recrystallization temperature of rhenium decreases with increasing amounts of cold work, from 1 750°C for 5% deformation to 1 200°C for 40-60% deformation. This strong dependence exist because the nucleation of recrystallization occurs at the intersection of twin crystals and growth proceeds on the bases of the twins. When a polycrystalline material is deformed, the individual grains tend to orient themselves so that the active slip systems become more favorably oriented with respect to the direction of the principal strain. This leads to crystallographic anisotropy or preferred orientation. In a recent study, the effect of rolling mode on PM rhenium was evaluated. Samples rolled at a 45° direction showed a higher work hardening rate than samples rolled along the width and length of rolled sintered bars. This paper will review the interactions of cold work and annealing on the work hardening, recrystallization, and texture of rhenium.
Sponsored by: SMD Non-Ferrous Metals Committee Program Organizer: Eui W Lee, WE. Frazier, Code 4342, Naval Air Warfare Center, Patuxent River, MD 20670; K. Jata, WUMLLM, WPAFB, OH 45433; N.J. Kim, Center for Advanced Aerospace Materials, POSTECH, Pohang, 790-784, Korea
Wednesday, AM February 12, 1997
Room: 330A Location: Orlando Convention Center
Session Chairperson: Sao Woo Nam, Dept. of Materials Science & Eng., Korea Adv.lnst. of Science and Technology, Taejon 305-701 Korea
8:30am AN EVALUATION OF THE DAMAGE TOLERANCE CHARACTERISTICS OF Ti-Ai2Sn-2Zr-2Mo-2Cr SHEET: T.D. Bayha, Lockheed Martin Aeronautical Systems, Marietta, GA 30063; D.L. Yaney, Lockheed Martin Missiles and Space Palo Alto, CA 94304 Ti-6AI-2Sn-2Zr-2Mo-2Cr (Ti-6-2-2-2-2) is an alpha-beta titanium alloy typically utilized in thick section, damage tolerance-driven aerospace applications. This alloy was developed for deep hardenability, with high strength, and moderate fracture toughness. Ti-6-2-2-2-2, research efforts to date have been primarily focused on rolled plate and forged products; however, there is interest in developing thin sheet material for wing skin applications. A rolling practice to produce Ti-6-2-2-2-2 sheet materials for conventional and superplastically formed structure has been developed. The work described here characterizes the properties, microstructure, and fracture behavior or Ti6-2-2-2-2 solution treated and aged sheet samples subjected to tensile and cyclic loadings. Tensile and fatigue crack growth tests were performed over a wide temperature range (-65°F to 500°F) to assess the suitability of the sheet in various applications. Crack growth testing was performed utilizing two R-ratios at each temperature of interest. Test data indicates that the crack growth behavior of Ti-6-2-2-2-2 is superior to Ti-6AI-4V sheet in the Paris regime under comparable test conditions. A complete metallurgical analysis utilizing both scanning electron and transmission microscopy was conducted to develop property/microstructure relationships, and selected test specimens were examined to provide insight regarding fracture mechanisms with respect to typical cyclic loading conditions.
10:30am SOLID SOLUTION MOLYBDENUM-RHENIUM ALLOYS: Lynn B. Lundberg, Materials Consultant, 2832 W. 33mN., Idaho Falls, ID 83402; Boris D. Bryskin, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036 It has been known for many years that the brittleness commonly seen in commercial-pure molybdenum around room temperature can be greatly reduced or eliminated by alloying with rhenium within the solubility range fro rhenium in molybdenum. Molybdenum-based solid solution alloys with rhenium represent a technically important class of refractory metal alloys whose behavior is reviewed in this paper. Mechanical and physical properties are reviewed as well as the fabrication characteristics of the alloys. Data from the vast amount of research performed on molybdenum-rhenium alloys in the former Soviet Union and more recently in Russia are referenced, summarized and reviewed. For the area of advanced materials' applications such analysis is appropriate to make intelligent decisions on how to proceed.
10:50 am AN OVERVIEW OF WoRe ALLOYS FOR TEMPERATURE MEASUREMENT APPLICATIONS: D.A Toenshoff, R.D. Lanam, EngelhardCLAL, 700 Blair Road, Carteret, NJ 07008
8:50am EFFECT OF aJ~ VOLUME FRACTION ON THE SUPERPLASTIC DEFORMATION BEHAVIOR OF Ti-6AI-4V ALLOY: J.S. Kim, D.M. Li, C.S. Lee, Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
Two Tungsten-Rhenium alloy pairs are the predominant combinations used in the measurement of temperatures up to 2400°C and higher under protective inert or vacuum conditions. These alloy pairs are W-3Re vs. W-25Re and W-SRe vs. W-26Re. Other combinations are used in regional areas or for special applications. These include W vs. W-25Re and W-5Re vs. W-20Re. A historical review of the materials and the evolution of their use will be given. A discussion of alternate materials e.g. Ir vs. Ir-40Rh to measure high temperatures will be included. The effect of composition and environment on the EMF characteristics will be summarized. The future use ofW-Re alloys for temperature measurement applications will be projected.
Present investigation has been made to study the superplastic deformation behavior of Ti-6AI -4V alloy with respect to the variation of aJ~ volume fraction. Load relaxation tests were employed at 600 and 800°C, to obtain stress-strain rate curves for the microstructures of 3 and 161lm grain sizes. Superplastic deformation test was also carried out to confum the results of load relaxation test. The experimental results were analyzed by the theory of inelastic deformation which consists of two mechanisms, i.e., one is the grain matrix deformation and the other is the phase/grain boundary sliding. Grain matrix deformation is dominant at 600°C and well described by the state equation when permeability parameter, p, is 0.15. Phase boundary sliding is dominant at 800°C and also consistent with the viscous flow equation with M g=2.
11:10 am THE MECHANICAL PROPERTIES OF WoRe MADE BY PM METHOD: N. Danilenko, V. Panichkina, Yu. Podrezov, O. Radchenko, Frantsevich Institute for Problems of Materials Science, 3 Kljijanovskogo Str. 252680 Kiev, Ukraine The tungsten sheets made by using the powder metallurgy method displayed low plasticity and were apt to delamination in the rolling plane. In order to improve plasticity of the sheets and suppress delamination the additions of the WoRe and HfO powders were employed. On the basis of such compositions the tungsten sheets were obtained which were plastically deformed at
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CHARACTERIZATION OF INTERMETALLIC PRECIPITATES IN A wj3 TITANIUM ALLOY: X.D. Zhang', l.M.K. Wiezorek', D.l. Evans', L. Fraser', 'The Ohio State University, Department of Materials Science and Engineering, 2041 College Rd, Columbus, OH 43210; 'Materials Directorate, Wright Laboratory, WUMLIM, Wright Patterson AFB, Dayton, OH 45433
INVESTIGATION OF THE CREEP DEFORMATION MECHANISM OF THE LAMELLAR TiAIALLOY MADE BY HOT EXTRUSION OF A BLENDED ELEMENTAL POWDER MIXTURE: Soo Woo Nam, Han Seo Cho, Sun-Keun Hwang' and Nack I. Kim', Dept. of Mat. Sc. & Eng., Korea Advanced Institute of Sci. & Tech. Taejon 305-701, 'Inha University, and 'Pohang Univ. of Sci. & Tech., Korea
A two phase o.-~ titanium alloy, Ti-6AI-2Mo-2Cr-2Sn-2Zr-0.2Si (Ti-6-2222S), has recently been reconsidered as a structural material for aircraft applications. This alloy exhibits specific strength and fracture toughness superior to that of Ti-6AI4Y. However, similar to other alpha-beta titanium alloys, microstructural stability is one of the major concerns regarding industrial application of Ti-6-22-22S. For instance, precipitation of additional phases during long term high temperature exposure is predicted to affect significantly the performance of components in service. Three different precipitates have been observed in Ti-6-22-22S alloys, namely silicides, ro and a, phases. The presence of intermetallic precipitates, such as 0." in the parent a matrix has been reported to result in brittle behaviour of the wj3 alloys due to the formation of intense planar slip on {1O I U} prismatic planes. The present paper presents results of the characterization of intermetallic a, precipitates in the a phase ofTi-6-22-22S by methods of scanning ant transmission electron microscopy (SISM and TEM respectively). The precipitation of a,precipitates has been studied as a function of heat treatment conditions in order to examine the microstructural stability and growth behaviour. The observed dispersion of small, brittle intermetalllic precipitates is expected to have a detrimental effect on the fracture performance of Ti-6-22-22S. Hence, it is important to ascertain the origin of this precipitation phenomenon. The a, precipitates have been characterized chemically and structurally by high spatial resolution microanalysis and high resolution electron microscopy.
Creep properties of the lamellar structured Ti-46.6AI-1.4Mn-2Mo (at.%) alloy, which is made by hot extrusion of a blended elemental powder mixture, are investigated in air environment over the temperature range from 750°C to 900°C at constant stress levels ranging from lOOMPa to 250MPa. Average grain size of 150l1m is measured and the grain boundary phase is distributed inhomogeneously before the creep tests. The dislocation climb controlled creep deformation is suggested on the basis of the measured average activation energy for creep of 388kJ/mol and normalized stress exponent of 4.3 within the temperature range from 775°C to 900°C at stress level ranging from 150MPa to 250MPa. However, activation energy of90kJ/mol within the temperature range of 750°C-775°C and stress exponent of I.3 at 800°C within the stress range of 100-150MPa are measured. Microstructural studies conducted on the creep fractured specimens showed the secondary cracks along the lamellar grain boundaries and these secondary cracks are assumed to be formed by pore nucleation, growth and coalescence during the tertiary stage.
10:30 am MECHANICAL BEHAVIOR OF BINARY AND TERNARY-ALLOYED A~Ti: J.C. Ma, J.E. Benci, Department of Materials Science and Engineering, Wayne State University, Detroit, MI 48202
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Polycrystalline binary AI,Ti was produced via casting or powder metallurgy and then further processed yielding material in six conditions. The yield strength as a function of test temperature and the room temperature fracture toughness were measured for these six material conditions. The fracture toughness values were determined from the critical load necessary to initiate cracks with a Vickers indenter. Both properties show a strong dependence on processing condition. Off-stoichiometric al,±yTil±"Y and ternary-alloyed AI,Ti + X were also produced, and samples in the as-cast and cast & annealed conditions were prepared. The composition of the off-stoichiometric alloys was varied between 63 and 71 at% aluminum in 2% increments. Ternary-alloyed AI,Ti contains approximately 2 at% of either Si, V, Cr, Mn, Fe, Ni, Cu, Nb, Mo or W. The room temperature hardness and fracture toughness and the room and elevated temperature yield strength were measured for each composition in both the as-cast and cast & annealed material conditions. The effect of thermal mechanical processing, such as hot forging, on the room temperature properties was also investigated.
CRACK PROPAGATION IN GRADIENT MICROSTRUCTURES IN TITANIUM ALLOYS: A. Berg, l. Kiese, L. Wagner, Technical University of Brandenburg at Cottbus, 03013 Cottbus, Germany Fatigue crack nucleation, microcrack growth and long crack growth are often oppositely affected by microstructural changes. For example, refining the microstructural unit size, e. g., grain size, improves the material's resistance to crack nucleation and microcrack growth, while long crack characteristics often deteriorate. To obtain optimum resistance of a component to various stages of fatigue life, microstructural gradients were developed in the near-a titanium alloy TIMETAL 1100 and the metastable ~ alloy Ti-3AI-8V-6Cr-4Mo-4Zr (Beta C) by thermomechanical treatments. In TIMETAL 1100, the prior ~ grain size of fully lamellar microstructures was varied from about 100 11m at the surface of the component to about 500 11m in the bulk, while for Beta C, the degree of age-hardening was varied over the cross section resulting in hardness values ranging from 700 HV 0.1 at the surface to 300 HV 0.1 in the bulk. Fatigue tests were performed in 3-point bending using a servohydraulic tt sting machine. Optical microscopy was used to study fatigue crack nucleation and crack growth. The results are compared with non-gradient references.
10:50 am MICROSTRUCTURAL EVOLUTION DURING HIGH TEMPERATUREDEFORMATIONOFy-TiAIINTERMETALLICCOMPOUNDS: Hee Y. Kim, Woong H. Sohn, Soon H. Hong, Dept. of Mat. Sci. & Eng., Korea Advanced Institute of Science and Technology, Taejon, 305-701, Korea
9:50am MECHANICAL AND THERMOMECHANICAL SURFACE TREATMENTS TO ENHANCE BCF STRENGTEI IN HIGH-STRENGTH-~ TITANIUM ALLOYS: J. Kiese, W. Walz, L. Wagner, Technical University of Brandenburg at Cottbus, 03013 Cottbus, Germany
The microstructural changes during high temperature deformation behavior ofTi-(46,48)AI-2W and Ti-47AI-2Cr-4Nb intermetallic compounds have been investigated by isothermal compression tests at temperatures ranged lOOO°C-1200°C with strain rates ranged 10·'-10·'s-'. The stress-strain curve exhibited a peak stress then the flow stress decreased gradually into a steady state with increasing strain. The stress-strain curves showed a flow softening which is attributed to the dynamic recrystallization. The dependences of flow stress on temperature and strain rate were formulated using Zener-Hollomon parameter. The activation energies were measured as 437kJ/mol, 374kJ/mol and 300kJ/mol and the stress exponents were measured as 5.8, 5.3 and 4.9 for Ti-46AI2W, Ti-48AI-2W and Ti-47AI-2Cr-4Nb, respectively. The dynamically recrystallized microstructures were investigated and the relationships between recrystallized grain size and temperature compensated strain rate was discussed. The texture evolution during high temperature deformation was analyzed using the orientation distribution function (ODF). The controlling mechanisms during high temperature deformation of TiAI intermetallic compounds with varying temperature, strain and strain rate were discussed.
Shot peening and deep rolling with and without subsequent heat treatments were performed on various microstructures of the high-strength metastable ~ titanium alloys Ti-3AI-8V-6Cr-4Mo-4Zr and Ti-lOV-2Fe-3AI to improve the fatigue behavior. To evaluate optimum process parameters, a wide range of Almen intensities, rolling forces and annealing temperatures was chosen. The change in surface layer properties was evaluated by TEM, X-ray diffraction, optical microscopy and micro hardness measurements. Smooth and notched (K+ = 3.0) specimens were tested in rotating beam loading and the fatigue behavior was compared to the electrolytically polished reference. The results are explained in terms of the resistance to fatigue crack nucleation and microcrack growth as affected by the changes in near surface dislocation structure, residual compressive stresses and extensive precipitation hardening.
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9:05 am INVITED ROLE OF ENERGETIC SPECIES DURING LASER ABLATION THIN FILM GROWTH: David P. Norton, Oak Ridge National Laboratory, Oak Ridge, TN 37831
11:10 am COMPARISON OF FATIGUE CRACK GROWTH RESISTANCE OF GAMMA ALUMINIDES AND Ti-BASED ALLOYS: S. Lesterlin. C. Mabru, C. Sarrazin, G. Henaff, J. Petit, Laboratoire de Mechanique et de Physique des Materlaux, URA CRNS 863 ENSMA, BP 109, 86960 Futuroscope, France
9:40 am INVITED ROLE OF THE CO2 LASER IN DUAL-LASER ABLATION: Sarath Witanachchi, University of South Florida, Tampa, FL 33620
Gamma aluminides present attractive properties for high temperature structural applications and could be adopted against traditional titanium alloys. The resistance to fatigue crack growth is critical against traditional titanium alloys. The resistance to fatigue crack growth is critical for aeronautical applications. In this paper, the fatigue behavior of long cracks in Titanium Aluminides (lamellar and fully y) is compared, based on microstructure, temperature and environment criteria, with five conventional Titanium alloys in different thermomechanical conditions. At room temperature, higher threshold (related to enhanced near-threshold contribution of crack closure) and lower K,c contributes to much more steep propagation curves on TiAI. At high temperature in air, the crack growth regime identifies on Ti alloys as a corrosion-fatigue mechanism assisted by water vapor is shown to be also oporative for TiAI alloys. In all the cases, the propagation of fatigue cracks in both types of materials seems to be governed by the same mechanisms and the TiAI alloys appears to be more sensitive to moisture than Ti based alloys.
10:15 am BREAK Session Chairperson: J. Narayan, North Carolina State University, Burlington Labs, Raleigh, NC 27695-7916 10:30 am APPLICATIONS OF EXCIMER LASER PROCESSING OF THIN FILMS: G. Radhakrishanan, Aerospace Institute, PO Box 92957, MS M2241, Los Angeles, CA 90009 11:00 am INVITED GROWTH AND CHARACTERIZATION OF SELF-DOPED COLOSSAL MAGNETO RESISTIVE MANGANITE THIN FILMS: D. Kumar, Rajiv K. Singh, University of Florida, PO Box 116400, Gainesville, FL32611
11:30 am ENVIRONMENTALLY ASSISTED FATIGUE CRACK PROPAGATION IN Ti 6246 at 500°C: J. Petit, C. Sarrazin-Baudoux, S. Lesterlin, Y. Chabanne, Labora~ire de Mechanique et de Physique des Materlaux, UFA CNRS 863, ENSMA, BP 109, 86960 Fuuturoscope, France
11:30 am EFFECT OF ELECTRODES ON THE FERROELECTRIC CAPACITOR FOR DEVICE APPLICATIONS: M.R. Alam, A. Kumar, A. Mangiaracina, I. Ahmed, University of South Alabama
The fatigue and crack propagation behavior ofTi 6246 alloys elaborated with a fine Windmanstatten microstructure, has been investigated at 500°C. Tests were performed in air, high vacuum (l(}4 Pa), low vacuum (lPa) and humidified Argon (loo Pa and atmospheric pressure). Partial pressures of water vapour and oxygen were controlled by mean of hygro-metals and mass spectrometer. Crack closure was detected using a capacitive gauge mounted at the mouth of the notch of CT specimens. The enhancement of the crack growth rates in the mean-threshold area and the mid-rate range observed in the different environments in comparison to high vacuum, is clearly related to the presence of water vapor even at very low partial pressure. Critical conditions (partial pressure, frequency, closure, load ratio) for the occurrence of water vapor assisted corrosion-fatigue, creep-fatigue and stress-corrosion are explored, and the specific role of oxygen and water vapor is discussed on the basis of microfractographic observations, fracture surface analysis (R.B.S. technique) and closure measurements.
MATERIALS FOR SPALLATION NEUTRON SOURCES IV: Neutronics Sponsored by: Jt. SMDIMSD Nuclear Materials Committee Program Organizers: M.S. Wechsler, North Carolina State UniverSity, L.K. Mansur, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6376; C.L. Snead, Brookhaven National Laboratory, Upton, NY 11973-5000; W.F. Sommer, Los Alamos National Laboratory, Los Alamos, NM 87545 Wednesday, AM February 12, 1997
Session Chairperson: C. L. Snead, Brookhaven National Laboratory, Upton, NY 11973-5000
8:30am PRE-CONCEPTUAL DESIGN AND PRELIMINARY NEUTRONIC ANALYSIS OF THE PROPOSED NATIONAL SPALLATION NEUTRON SOURCE: J.O. Johnson, J.M. Barnes, L.A. Charlton, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6363
LOW ENERGY PROCESSES IN ELECTRONIC MATERIALS: Laser DepOSition & Processing Sponsored by: EMPMD Thin Films and Interfaces Committee Program Organizers: Rajiv K. Singh, University of Florida, 317 MAE, PO Box 116400, Gainesville, FL 32611-6400; O.W. Holland, Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831; Steve Pearton, University of Florida, 343 NSC, PO Box 116400, Gainesville, FL 32611-6400; Roy Clarke, Department of Applied Physics, University of Michigan, Ann Arbor, MI 48109-1120; D. Kumar, University of Florida, PO Box 116400, Gainesville, FL 32611 Wednesday, AM February 12, 1997
Room: Salon 4 Location: Clarion Plaza Hotel
The Department of Energy has initiated a pre-conceptual design study for the National Spallation Neutron Source (NSNS) and given preliminary approval for the proposed facility to be built at Oak Ridge National Laboratory. The pre-conceptual design of the NSNS consists of an accelerator system capable of delivering a 1-2 GeV proton beam, with 1 MW of beam power, in an approximate 0.5 microsecond pulse, at a 60 Hz frequency onto a single target station. The NSNS will be upgraded in stages to a 5 MW facility with two target stations (a 60 Hz station and a 10 Hz station). There are many possible layouts and designs for the NSNS target stations. This paper gives a brief overview of the proposed NSNS with respect to the target station, as well as the general philosophy adopted for the neutronic design of the NSNS target stations. A reference design, based upon experience at existing sources and on designs for proposed new, high power, sources is presented, and some of the preliminary design neutronic results for the NSNS are briefly discussed.
Room: 314B Location: Orlando Convention Center
Session Chairpersons: J.R. Childress, University of Florida, PO Box 116400, Gainesville, FL 32611
8:30 am INVITED LASER PROCESSING OF ADVANCED MATERIALS: J. Narayan, North Carolina State University, Burlington Labs, Raleigh, NC 27695-7916
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CALCULATED NEUTRONIC PERFORMANCE AND RADIATION DAMAGE PARAMETERS FOR THE UPGRADED MANUELLUHAN, JR., NEUTRON SCATTERING CENTER TARGET SYSTEM: P.D. Ferguson, GJ. Russell, EJ. Pitcher, J.D. Court, Los Alamos National Laboratory, Los Alamos, NM 87545
PROGRESS REPORT ON THE ACCELERATOR PRODUCTION OF TRITIUM MATERIALS PROGRAM: S.A. Maloy, w.P. Sommer, Los Alamos National Laboratory, Los Alamos, NM 87545 Progress will be reported on the status of an irradiation by 800 MeV protons and spallation neutrons to determine the change in mechanical properties of materials to be used in the APT project. Materials will be irradiated for 8-9 months at the Los Alamos Radiation Effects Facility (LASREF). The irradiation matrix, developed by members of several laboratories nationwide, consists of specimens of candidate materials, scaled components and a closedloop water system to measure rates of corrosion in irradiated water. The objectives are to determine the performance (particularly, mechanical and corrosion properties) of materials in APT-prototypic proton and neutron radiation and temperatures, to test manufacturing processes for producing components, and to develop a surveillance program to monitor the properties of materials during the life of the APT targetlblanket.
The upgraded MLNSC target system is designed to be a split target with two tiers of moderators. The original suite of moderators serving 12 flight paths has been optimized and an additional pair of moderators, one water and one LIf" have been added in a new upper moderator tier serving 4 additional flight paths. The upper moderators are coupled and viewed in backscattering geometry, as opposed to the decoupled moderators in the existing MLNSC target system which are viewed in transmission. Fabrication of this new target system is currently in progress and installation is expected in 1998. The neutronic performance of the target system s presented in the form of time and energy spectra for each of the planned moderators with comparisons to the existing MLNSC moderators. Results of several studies, including moderator thickness, upper target length, and reflector material, are presented. For the upper and lower targets, target canister material, and moderator structural material, we present neutron and proton energy spectra, helium production, and DPA calculations. Existing accelerator materials damage data are referenced, where applicable, to draw general conclusions on component lifetime.
MATERIALS PROCESSING FUNDAMENTALS SYMPOSIUM III Sponsored by: Jt. EPDIMDMD Synthesis, Control, and Analysis in Materials Processing Committee, EPD Process Fundamentals, Aqueous Processing, Copper, Nickel-Cobalt, Pyrometallurgy, Lead, Zinc, Tin Committees, MSD Thermodynamic & Phase Equilibria Committee Program Organizers: R. G. Reddy, Department of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL 35487-0202; S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; P.R. Taylor, Department of Metallurgical and Mining Engineering, University of Idaho, Moscow, ID 83843
9:30am CALCULATED NEUTRONIC PERFORMANCE OF ALONG-PULSE SPALLATION SOURCE: G.J. Russell, EJ. Pitcher, P.O. Ferguson, J.D. Court, OJ. Weinacht, Los Alamos National Laboratory, Los Alamos, NM 87545 Neutronic performance studies of a Long-Pulse Spallation Source (LPSS) at the Los Alamos National Laboratory show that a I-MS LPSS has world-class neutronic performance with low technical risk. An LPSS uses coupled moderators (moderators that communicate neutronically at all energies with an adjacent reflector). There are potential gains of about a factor of 6 in timeaveraged neutron brightness for a coupled moderator compared to a decoupled one; however, this gain comes at the expense of putting "tails" on the neutron pulses. The particulars of a neutron pulse from a moderator (e.g., rise time, peak intensity, pulse width as measured by the standard deviation or fullwidth at half maximum of the pulse, and decay constant(s) of the tails) are crucial parameters for instrument design/performance at an LPSS. Moderator neutronic performance can be altered in a variety of ways: a)target material and geometry; (b) moderator material and geometry; c) target-moderator geometry; d) reflector material; e) presence of decouplers and flight path liners; and t) the proton pulse width. We will discuss the neutronic performance of an LPSS and describe the variety of neutronic optimization studies that have been done to improve the neutronic performance of such a neutron source.
Wednesday, AM February 12, 1997
Room: 231B Location: Orlando Convention Center
Session Chairpersons: KNona Liddle, Washington State University; V. Ramachandran, ASARCO, Inc., 3422 S. 700 W., Salt Lake City, UT 84119-4191
8:30AM THERMAL PLASMA ENHANCED CHEMICAL VAPOR INFILTRATION: PATRICK R. TAYLOR, BANQIU WU, Edgar E. Vidal, University of Idaho, Department of Metallurgical & Mining Engineering, Moscow, ID 83844-3024 A novel method for chemical vapor infiltration, using thermal plasma technology, has been developed. The use of a thermal plasma source may allow much greater infiltration rates than conventional CVI. Precursors that are fed into the flame region of the plasma are vaporized and forced to flow through a porous preform, at a controlled temperature, where condensation or chemical reactions occur. Exploratory experiments, using silica and methane as precursors and graphite felt for the preform, have been performed. The change in the pressure drop across the preform, as infiltration occurred, is compensated by the use of a vacuum pump on the discharge of the reactor. The product was characterized using SEM and x-ray diffraction. A uniform infiltration rate of SiC was observed along the width of the preform.
10:00 am BREAK 10:20 am NEUTRONIC DESIGN OF THE APT MATERIALS IRRADIATION AT THE LOS ALAMOS SPALLATION RADIATION EFFECTS FACILITY: P.D. Ferguson', W.P. Sommer', M. S. Wechsler', GJ. Russell', EJ. Pitcher', R.B. Kidman'; 'Los Alamos National Laboratory, Los Alamos, NM 87545; 'North Carolina State University, Raleigh, NC 27695-7909
8:55am SOME KINETIC ASPECTS OF THE GASEOUS CHLORINATION OF TITANIUM-BEARING RAW MATERIALS: C.A. Silva, D.H. Gameiro, y.A. Leao, I.A. Silva, C.S. Paulo, Escola de Minas da UFOP, Departamento de Metalurgia, Praca Tiradentes 20, 35400-000, Ouro Preto, MG, Brazil
The APT project is in the process of qualifying materials for use in the target! blanket assembly. As part of the process, an eight month irradiation of prospective target, blanket, beam entry window, and structural materials is taking place at LASREF in the 800-MeV, I rnA proton beam. The irradiation is configured to produce samples at prototypic APT radiation environments, as well as samples at reduced damage rates to provide information as to how the materials age in an APT environment. In addition, three prototype lead blanket modules are being irradiated along with several aluminum tubes filled with 3He to experimentally determine the extent of tritium implantation in the APT system and to explore possible mitigation techniques. In this paper, we detail the methodology of the neutronic design of the irradiation. Neutron and proton spectra are presented for several irradiation locations and materials, as well as calculated gas production and dpa estimates.
The kinetics of chlorination of titanium-bearing raw materials has been investigated. For comparison purposes pellets of controlled macro-porosity, made of analytical grade TiO, and anatase concentrate (Brazil), have been exposed to different combinations of gas composition - CO, CO" CI, - , gas flowrate and temperature. A thermogravimetric technique and an adapted grain model have been used in order to assess the influence of the several experimental parameters upon the chlorination behavior.
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9:20am KINETICS OF OXYCHLORINATION OF CHROMIUM (III) OXIDE: I. Gaballah, N. Kanari, Mineral Processing and Environmental Engineering, LEM, CNRS URA 235, ENSG, INPL, BP 40,54501 Vandeuvre, France
11:10 am MICROSCOPICAL STUDY OF ROASTED NICKEL CONCENTRATES PRODUCED IN SIMULATED FLASH SMELTING CONDITIONS: Satu Stromberg, Ari Jokilaakso, Satu Jyrkonen, Department of Materials Science and Rock Engineering, Helsinki University of Technology, Espoo, Finland and Tilna Jokinen, Outokumpu Research Oy, Pori, Fin- land
The oxychlorination kinetics of pure Cr,03 with CI,+O, is studied by ThermoGravimetric Analysis (TGA) in non and isothermal conditions up to IOOO'C. The final reaction product is CrO,CI,. The reaction Of Cr,03 with CI,+O, chlorination gas mixtures starts at about 500'C. The apparent activation energy of the oxychlorination reaction of Cr,03' as well as the apparent reaction orders with respect to the reactive gases are determined. The reaction rate is maximum for a Cl,l 0, molar ratio equal to 4.
Four different nickel concentrates were oxidized in a laboratory scale Laminar flow furnace in simulated flash smelting conditions. The major nickeland iron-bearing minerals in the concentrates were pentlandite, violarite, gersdorffite, and pyrite and pyrrhotite, respectively. Thermal decomposition, ignition and oxidation behavior of nickel and iron sulfides were examined by using optical and scanning electron microscopy. General reactivity of the concentrates was monitored with sulfur removal which was most effective in violarite-based concentrate. Penlandite-concentrates needed higher experimental temperatures for complete desulfurisation and gersdorffite-based concentrate contained 5 - 10 % of the original sulfur even at the most oxidizing conditions studied (l IOOOC, 50 vol-% 0,). The reactivity of the iron minerals were found to depend on the other minerals present in the concentrate. In this paper, observed reaction products and mineralogical changes are presented and preliminary conclusions of possible reaction mechanisms of nickel-bearing minerals are discussed.
9:45am CHLORINATION: A POTENTIAL APPROACH FOR THE BENEFICATION OF CHROMITE: N. Kanari, I. Gaballah, Mineral Processing and Environmental Engineering, LEM, CNRS URA 235, ENSG, INPL, BP 40,54501 Vandeuvre, France One of the criteria to define the market value of chromite concentrate is its chromium to iron ratio. Changing this ratio for a definite chromite is impossible by physical processing. This study investigates the possibility of increasing this ratio through the carbochlorination of chromite concentrate by CI,+CO between 500' to 900'C. The evolution of the reaction products' characteristics is determined by SEM, XRD and chemical analysis. The carbochlorination of a chromite concentrate at 600'C leads to the selective partial elimination of iron allowing a higher CrIPe ratio of the treated concentrate. A flow-sheet for the benefication of chromite is suggested.
MICROSTRUCTURE/PROPERTY RELATIONSHIPS· CORROSION AND DEFORMATION I
10:20 am BREAK
TMS General Abstract Session
10:20am ARSENIC VOLATILIZATION FROM ENARGITE CONCENTRATE: R. Padilla, Y. Fan, M. Sanchez, and I Wilkomirsky, Department of Metallurgical Engineering, University of Concepcion, Casilla 53-C, Concepcion, Chile
Wednesday, AM February 12, 1997
Room: 240C Location: Orlando Convention Center
Session Chairperson: S.K. Varma, Dept. of Metallurgical and Materials Engineering, University ofTexas at EI Paso, EI Paso, TX 79968
A thermogravimetric study has been conducted to follow the decomposition and volatilization of arsenic from enargite concentrate in nitrogen and slightly oxidizing atmospheres, Temperature has a large effect on the rate of volatilization of arsenic. Fractional volatilization of arsenic as high as 95% were reached in less than 30 min. at 650°C in nitrogen atmosphere, while in slightly oxidizing atmosphere the same volatilization could be achieved in less than 20 min. It was found that As volatilizes as sulfide in nitrogen atmosphere and as a mixture of sulfide and oxide in atmospheres containing 1% oxygen.
8:30am IDENTIFICATION OF CONSTITUENT PARTICLES IN 2024-T3 AND 7075-T6 ALUMINUM ALLOYS: Ming Gao, Robert P. Wei, Dept. of Mechanical Engineering and Mechanics, Lehigh University, 7 Asa Dr., Bethlehem, PA 18015; Jerry Feng, Metallurgy Division, Naval Research Laboratory, Washington, DC 20375 Constituent particles in 2024-T3 and 7075-T6 aluminum alloys were identified by analytical electron microscopy (AEM) to aid the understanding of particle-induced pitting corrosion. Convergent beam electron diffraction (CBED) was used, in conjunction with energy dispersive x-ray spectroscopy (EDS), for determining their structure and composition. Typical phases in these alloys (CuA12, CuMgAl2 and Fe4CuA123) were identified. In addition, a complex rhombohedral phase, with composition close to (Fe, Cu, Mn, Si)AI, was also identified. Detailed aspects of these particles are described, and their role in pitting corrosion are discussed. * Research supported by the Air Force Office of Scientific Research, Grant F49620-93-1-0426, and the Federal Aviation Administration, Grant 92-G-0006.
10:45 am OXIDATION OF COPPER MATTE PARTICLES IN SIMULATED FLASH CONVERTING CONDITIONS: Kirsi M. Rijhilahti, Ari Jokilaakso, Department of Materials Science and Rock Engineering, Helsinki University of Technology, FIN-02150 Espoo, Finland; Hong Yong Sohn, Manuel Perez-Tello, Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT 84112 The oxidation characteristics of solid copper matte particles under simulated Kennecott-Outokumpu Flash Converting conditions are presented. This project is concerned with the determination of the effects of operating variables on the reaction of the particles. Experiments were carried out in a large laboratory-scale flash furnace with 72 wt% Cu matte by varying initial particle size, temperature, oxygen partial pressure, oxygen to matte mass-ratio and residence time. Chemical analysis and optical and scanning electron microscopy were used to study the oxidation, morphology and mineralogy. Fractional conversion and sulfur removal, in general, slightly decreased with initial particle size while higher oxygen to matte mass-ratio mainly resulted in higher fractional conversion and more efficient sulfur removal. The fractional conversion values represented the overall extent of oxidation more closely than degree of sulfur removal.
8:50am TEM STUDIES OF PARTICLE-INDUCED CORROSION IN 2024-T3 AND 7075-T6 ALUMINUM ALLOYS: Robert P. Wei, Ming Gao, , Dept. of Mechanical Engineering and Mechanics, Chi-Min Liao, Dept. of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015 To better understand particle-induced pitting corrosion in aluminum alloys, thin- foil specimens of 2024-T 3 and 7075-T6 aluminum alloys, with identified constituent particles, were immersed in aerated 0.5 M NaCI solution and then examined by transmission electron microscopy (TEM). The results clearly showed matrix dissolution around the iron and manganese containing particles (such as, Fe4CuAI23). Matrix dissolution was also observed around CuAl, particles, while CuMgAl, particles tended to dissolve relative to the matrix. These results are consistent with previous SEM observations of pitting corrosion, and are discussed in terms of the electrochemical characteristics of the
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particles and the matrix. Research supported by the Air Force Office of Scientific Research, Grant F49620-93-1-0426, and the Federal Aviation Administration, Grant 92-G-0006.
10:10 am BREAK 10:30 am THE MICROSTRUCTURE AND PROPERTIES OF NITROGEN GAS ATOMIZED ALLOY 690: G.E. Fuchs, Lockheed Martin Company, P.O. Box 1072, Schenectady, NY 12301-1072
9:10am RELATIONSHIP BETWEEN THE SOLUTIONIZED MICROSTRUCTURES AND THE TRANSIENT CURRENT RESPONSE FROM SCRATCH TEST EXPERIMENTS IN 6061 ALUMINUM ALLOY AND A COMPOSITE CONTAINING ALUMINA PARTICLES: Shane Andrews, S.K. Varma, Department of Metallurgical and Materials Engineering, The University of Texas at EI Paso, EI Paso, TX 79968-0520
Alloy 690 exhibits excellent resistance to stress corrosion cracking (SCC) and is frequently used in steam generator applications. In order to achieve the desired microstructure for SCC resistance in A690, high temperature solution annealing heat treatments are required. These heat treatments, though, can result in extensive grain growth and relatively low strength. Powder metallurgy processing and the addition of nitrogen during atomization results in an alloy with significantly improved microstructural control and properties. This study examines the microstructure and properties of a nitrogen gas atomized A690 heat consolidated by HIP and extrusion. The effects of consolidation temperature and subsequent hot working is also discussed.
The sensitivity of the scratch technique towards understanding the corrosion behavior of 6061 aluminum alloy reinforced with 0.1 volume fraction of alumina particles and in the monolithic form has been explored. Identical solutionizing treatment in the two materials shows different transient current responses. The depassivation and repassivation kinetics appear to differ considerably during the impact and continuous scratches since a balance between the two results in stabilized value of peak current during continuous scratching experiments only. The total charge density increases linearly with solutionizing time for both materials while grain growth law (square of the grain diameter is directly proportional to the solutionizing time) is valid for up to 25 hours of solutionizing time. Near surface microstructures have been examined with the help of TEM as well as SEM. This research has been supported by the National Science Foundation through the grant number HRD9353547.
10:50 am THE BRITTLE·TO·DUCTILE TRANSITION IN NiAl SINGLE CRYS· TALS: S. Shrivastava, F. Ebrahimi, Materials Science & Engineering Department, University of Florida, Gainesville, FL 32611 Intermetallic compound NiAI has the potential to be used as a turbine blade material for aerospace applications due to its low density, high thermal conductivity, and good oxidation resistance. However, it suffers from insufficient toughness at low temperatures. The purpose of the present study was to investigate the effects of displacement rate on the brittle-to-ductile transition (BDT) in NiAl single crystals. Double-notched-tensile specimens with [110] tensile axis were used for fracture toughness testing. The results of this study show a strong strain rate dependence of BDT temperature, however, the low temperature toughness level was insensitive to the applied displacement rate. Fracture paths of the specimens fractured at different temperatures and strain rates were analyzed and the crack initiation and propagation mechanisms were investigated. In this paper, the process of BDT in NiAI single crystal will be discussed in terms of thermally activated deformation processes and their effects on crack initiation and propagation.
9:30am SCC BEHAVIOR OF SENSITIZED ALLOY 600 LASER-SURFACE ALLOYED WITH Cr·NJ POWDER: Joung Soo Kim, Jin Kuk Shin, Sun Ki Woo, Jeong Hun Suh, Yun Soo Lim, 11 Hyun Kuk, Korea Atomic Energy Research Institute P. O. Box 105, Yusung, Taejun, Korea In order to prevent and/or mitigate intergranular stress corrosion cracking(IGSCC) occurring in sensitized Alloy 600, the surface of the material was alloyed with Cr or Cr-Ni powder using a CO,laser beam. The thickness of the alloyed region was measured to be around 200 250 11m. The Microstructure and the compositional variations of the alloyed layers were analysed with a transmission electron microscope (TEM) and analyzed using EDX attached to the TEM. The alloyed molten metal was observed to solidify epitaxially from the boundary between the melted and unmeted(matrix) regions, like the microstructure of sensitized Alloy 600 surface-melted by a CO, beam. The compositional change in the alloyed layer was very small, i.e. very homogeneus. The surface-alloyed specimens were tested in a sodium tetrathionate (Na,S40J solution at room temperature using a CERT technique. IGSCC was completely prevented by the surface-alloying using a CO, laser beam, i.e. the specimen was ruptured and the fracture surface was observed to consist of dimples, which is a typical morphology of specimen fractured by ductile failure(rupture). The relationship between the microstructure and the susceptibility to IGSCC will be discussed.
11:10 am PRECIPITATION BEHAVIOR OF GAMMA PRIME AND SIGMA PHASE OF HIGH STRENGTH STAINLESS STEEL FOR SEA WA· TERAPPLICATIONS: Minoru Suwa, Hideto Kimura, Materials and Processing Research Center, NKK Corporation, I Kokancho, Fukuyama, 721, Japan The effect of y' -Ni,(Ti, AI) and a phase precipitation on the mechanical properties and the corrosion resistance to sea water was investigated in Fe(2025)%Cr-35%Ni-(4.5-6)%Mo-2%Ti-0.3%Alalloys. Though the hardness of the alloy increases after y 'and a phase precipitation, pitting-corrosion resistance is deteriorated by a phase, while deterioration by y , phase precipitation is little. The precipitation of 1 is found to occur almost simultaneously with a phase in 25%Cr-4. 5%Mo alloy. However, in 20%Cr-6%Mo alloy, the aging condition for y , phase to precede cr phase is found, which achieves both Vickers hardness of 320, and critical pitting temperature(CPT) of 323K.
9:50am CORROSION·FATIGUE AND STRESS· CORROSION CRACK GROWTH IN PRECIPITATION·HARDENABLE STAINLESS STEELS: P.S. Pao, C.R Feng, RA. Bayles, Naval Research Laboratory, Washington, D.C. 20375; G.R Yoder, Office of Naval Research, Arlington, VA 22217
11:30 am MICROSTRUCTURE CHANGE IN SILICON NITRIDE DURING SUPERPLASTIC DEFORMATION: Naoki Kondo', Eiichi Sato', Furnihiro Wakai', 'National Industrial Research Institute of Nagoya, Hirate-cho, Kitaku, Nagoya, Aich 462, Japan; 'The Institute of Space and Astronautical Science, Yoshino-dai, Sagamihara, Kanagawa 229, Japan
The effect of load ratio on the corrosion-fatigue crack growth kinetics and the stress-corrosion cracking of the precipitation-hardenable stainless steels PHI38Mo, 15-SPH, and 17-4PH in a 3.5% NaCI solution were investigated. All three PH-class stainless steels exhibit good stress-corrosion cracking resistance with stress-corrosion cracking thresholds in excess of70 MPaVm. These steels also demonstrate good corrosion-fatigue cracking resistance in a 3.5% NaCI solution as the crack growth rates in a 3.5% NaCI solution are less than twice the rates in ambient air. The corrosion-fatigue cracking thresholds progressively decrease as the load ratio (R) increases from 0.10 to 0.90. PH138Mo exhibits anomalous corrosion-fatigue crack growth kinetics and a concomitant change in fracture mode at R=0.90. The observed crack growth behavior, the deformation microstructure, and the significance of high load ratio corrosion fatigue will be discussed.
Three dimensional (3-D) microstructures of £ = 1.34 (280 % deformed) silicon nitride nitride specimen were calculated using the stereological analysis. The grain radius slightly increased during deformation. The aspect ratio remained almost constant up to £ = 0.88, and then, largely increased. The orientation angle decreased monotonously. A dominant deformation modes are considered to be grain sliding (£ = 0.88-1.34). Grain rotation and alignment also act as sub-dominant deformation mode all through the deformation.
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concept of partial crack closure was adopted in the analysis of crack growth rates, fatigue crack growth rates were a good agreement with, in spite of variation of stress ratio.
MICROSTRUCTURE/PROPERTY RELATIONSHIPS· DEFORMATION II
9:30am COMPRESSIVE STRENGTH AND FATIGUE PROPERTIES OF BEAl ALLOYS: R. Schneeberger, B. Bavarian, School of Engineering and Computer Science, California State University at Northridge, Northndge, CA 91330; R. Hayes, Metals Technology, Inc., 19080 Nordhoff St., Northridge, CA91330
TMS General Abstract Session Wednesday, AM February 12, 1997
Room: 2408 Location: Orlando Convention Center
Session Chairperson: David H. Carter, Los Alamos National Laboratory, MS G770, Los Alamos, NM 87545
Both 40 and 62 wt. % beryllium compositions were evaluated for ambient and elevated temperature compressive strength at low and high strain rates. Data indicated a strong influence of beryllium percentage along with an increase of yield point for fast strain rates of 0.5-1 inch/minute. Fatigue properties of a ternary BeAl-Ag cast and extruded material were determined for full reversal and standard tension fatigue conditions. Typical S-N curve behavior including endurance limit was observed.
8:30am A TEM STUDY ON THE MICROSTRUCTURALEFFECTS ON PLASTIC DEFORMATION IN ALUMINUMALLOY2219: Carlos D. Rincon, Roy Arrowood, Department of Metallurgical and Materials Engineering and Materials Research Institute, The University of Texas at El Paso, El Paso, TX 79968-0520
9:50am CREEP BEHAVIOR OF TWO BERYLLIUM-ALUMINUM ALLOYS: R. Schneeberger, B. Bavarian, School of Engineering and Computer Science, California State University, Northridge; 18111 Nordhoff St., Northridge, CA 91330; R. Hayes, Metals Technology, Inc., 19080 Nordhoff St., Northridge, CA91330
A fundamental transmission electron microscopy (TEM) investigation is being conducted on the effects of microstructure on the plastic deformation of 2219-T87 aluminum. A previous study showed inhomogeneous and locally extreme work hardening in the heataffected-zone (HAZ)- regions in Variable Polarity Plasma Arc (VPPA) 2219-T87 butt welds, which strongly suggests that the HAZ microstructure plays a major role in the deformation and fracture process. Due to the small size of these butt welds, it can be quite difficult to accurately quantify the stress-strain behavior of the HAZ. Therefore, precipitate structures similar to ones found in the HAZ are being produced by heat treatment of tensile specimens machined from 2219-T87 plate. Heat treatments involve varying the aging time and temperature to obtain GP zones followed by the precipitation of transition phases. Uniaxial tensile tests will be performed on the heat treated specimens at low strain rates (0.01 mine-I and 5.0 min-I') at room temperature in order to quantify the effect ofprecipitate structure on the stress-strain behavior. This work was supported by the General Electric Faculty of the Future Program.
Creep testing performed on 40 and 62 wt. % beryllium compositions of a powder metallurgy composite alloy at several elevated temperatures indicated a dependence of steady state creep rates and times to rupture on beryllium content, test direction, stress, and test temperature. A stress exponent of 8.5 for 40% beryllium and 10 for 62% beryllium was obtained from tests at 550 degrees F. A lower stress exponent of 6.7 was found for 62% beryllium at 630 degrees F. Activation energies for creep were somewhat higher than for selfdiffusion in either pure metal, and exhibited significant anisotropy. 10:10 am BREAK 10:20 am NEUTRON DIFFRACTION STUDY OF THE CO-DEFORMATION BEHAVIOR OF BERYLLIUM-ALUMINUM: David H. Carter, Los Alamos National Laboratory, MS G770, Los Alamos NM 87545
8:50am COMPREHENSIVE FLOW STRESS DETERMINATION IN EXTRUDED ALUMINUM PRODUCTS: Michael S. Paulson, Roger N. Wright, Materials Science and Engineering Department, Rensselaer Polytechnic Institute, Troy NY 12180
Neutron diffraction measurements of internal elastic strains during mechanical deformation are performed on Be-50%AI. The material is produced from hot isostatically pressed powder which is rapidly solidified using a gas atomization process. Under rapid solidification, Be-AI undergoes liquid phase separation, and upon complete solidification two intimately interpenetrating phases exist. The resulting microstructure can be described as a three-dimensional interpenetrating composite, where each phase is continuous. Strain measurements are taken at the Los Alamos Neutron Scattering Center (LANSCE) using a pulsed neutron source, which provides time-of-flight diffraction data. The elastic strains in the individual phases are measured as a function of applied stress. This data is used to quantify the deformation behavior of each phase. The A 1 phase is highly constrained by the Be phase due to the morphology of the composite as well as the high stiffness and low Poisson's ratio of Be. The results provide more insight into the overall deformation behavior of Be-AI.
Physical modeling of the aluminum extrusion process e reductions is difficult due to the large reductions and the complex extrudate shapes. Conventional machines flow stress specimens are not likely to be representative of the metal as it is extruded. A method of directly testing the total cross section is needed to properly represent extrudate flow stresses for process modeling purposes. Such a method is presented, as applied to rapidly heated commercial aluminum extrudates at temperatures and strain rates pertinent to die exit conditions. Resulting constitutive equations are compared to those developed for starting billet stock from the same lot of metal. Sponsored by the Rensselaer Aluminum Processing Program. 9:10am EFFECT OF REDISTRIBUTING RESIDUAL STRESS ON THE FATIGUE BEHAVIOR OF SS330 WELDMENT: Yong-BokLee, Chin-Sung Chung, Dept. of Mechanical Eng., Hong-Ik University of Seoul; Nam-Ik Cho, Dept. of Mech. Eng. Chon-Ju Tech. College; and Ho-Kyung Kim, Dept. of Automotive Eng., Seoul National Polytechnic University, 172 Kongnungdong, Nowon-ku, Seoul, Korea
10:40 am DEFORMATION OF Al,oPd21Mn. ICOSAHEDRAL QUASICRYSTAL WITH DECAGONAL PHASE LAMELLAE: Hisatoshi Hirai, Mater. Eng. Dept., Kyushu National Indust. Res. lnst., 807-1 Shuku, Tosu, Saga 841, Japan; Fuyuki Yoshida, Hideharu Nakashima, Dept. Mater. Sci. & Tech., Grad. Sch. Eng. Sci., Kyushu Univ., Kasuga, Fukuoka 816, Japan
Effect of residual stress and its redistribution in weldment on the fatigue crack propagation was investigated. Fatigue tests were conducted using center notched specimens machines from welded plats. The residual stress and its redistribution were measured by a magnetizing stress indicator and hole drilling method. The residual stresses were found to be redistributed during crack propagation. Crack growth rates were predicted and compared with the experimental results. It has been found that the predicted crack growth rates have a better agreement with the experimental results when the redistributing residual stress, rather than residual stress, was considered. Also when the
In our previous work, we prepared AI,OPd2IM~ icosahedral quasicrystal by zone melting technique. The obtained sample contained fine lamellae of decagonal phase AI 69Pd\3Mn I8 . The Vickers indentation test revealed that the existence of fine lamellae and annealing improved the fracture toughness of the sample to be about 2.1 Mpam In which is about 1.5 times as large as those without lamellae. In this paper, we will report the results of high temperature creep test of the sample with fine lamellae. We will also discuss the effects of
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decagonal lamellae on the high temperature plastic deformation of icosahedral phase, if possible. Detailed results will be presented at the meeting.
netic ordering temperature due to the application of an external magnetic field. For many lanthanide materials the temperature increase is sufficiently large that one can utilize these materials as magnetic refrigerants. The best materials are those which order ferromagnetically and contain a heavy lanthanide metal Gd, Th, Dy, Ho, or Er, and possibly Nd, since the available magnetic entropy, and therefore, the cooling power is proportional to the total quantum number, 1. Generally antiferromagnetic, ferromagnetic and spin glass behaviors are not nearly as effective as ferromagnetic ordering. Studies to date have indicated that the MCE can be used as a method for the ligquefaction of cryogenic gasses, freezers for food processing plants, supermarket chillers and large scale building air conditioning.
11:00 am THE PROCESSING AND PROPERTIES OF PIM Fe-Mn-AI ALLOYS: Chun Sien Lin, Materials Research Laboratory, ITRl, Hsinchu, Taiwan; ShihChin Chang, Dept. Materials Science and Eng., Tsing Hua University Hsinchu, Taiwan Powder metallurgy processing of Fe-Mn-AI alloys was studied. FeMn-AI alloy powder was produced by mechanical alloying of commercially available pure Fe, Mn, Al and C powder. The effect of ball milling, composition, pressure and sintering conditions on the microstructure and mechanical properties of resulted specimens were studied. For standard Fe-30Mn-IOAI-IC composition, 12 hour ball-milling is enough for producing the fcc structure of FeMn-Al alloy after compaction and sintering at a temperature of 1240 C or higher. It is found that the hardness, strength and ductility of the sintered specimens increase with sintering density. The specimen compacted with 800 MPa and sintered at 13260 C for one hour in Ar have a sintered density of 6.18 glcm3 (94.3% of theoretical density), hardness of HRC 32, and 0.2% offset yield strength of 1026 MPa. These mechanical properties are comparable to that of conventional casted material and are much better than that of the PIM carbon or stainless steels.
9:00am RARE EARTH RAW MATERIALS AND APPLICATION MARKETS: A BALANCING ACT: J.M. Tourre, Rhone-Poulenc Rare Earth and Gallium 25 Quai Paul Dourmer, 92408 Courbevoie Cedex, France 1995 has seen a continuation of a positive trend in the Rare Earth industry. The availability of greater diversity of raw materials has brought additional flexibility to the producers permitting better economics. China remains the major raw material source; Chinese concentrate producers have increased capacity in 1995 (Baotou, Sichuan, etc .. ). China's role in the Rare Earth industry will continue to evolve; the acquisition of a majority equity position in Magnequench by San Huan will have significant impact on both the Rare Earth and Magnet markets. Chinese producers are increasing the quality of their products and realize their true values. The Chinese market, itself, is also changing as the internal needs for the separated rare earths grow.
11:20 am LOAD RELAXATION AND SUPERPLASTIC DEFORMATION BEHAVIOR OF APb-SnALLOY: Tae Kwon Ha, Young Won Chang, Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
9:30am THE COMMERCIAL SIGNIFICANCE OF MIXED-LANTHANIDE DERIVATIVES: Barry T. Kilbourn, Molycorp, Inc., Fairfield, NJ
The deformation characteristics of Pb-Sn eutectic alloy, a typical microduplex superplastic material, has been investigated. For this purpose, a series of load relaxation tests has been conducted to obtain the flow curves under the condition of a constant structure and the results have consequently been analyzed based on the recently proposed internal variable theory of structural superplasticity. The effects of grain size and volume fraction of constituent phases on superplastic deformation behavior of this eutectic alloy has also been examined. The boundary sliding in this two phase alloy was characterized as a viscous flow process with the power index value of Mg =0.5. This value is much less than the previously reported value ofMg = 1.0 for GBS obtained in several single phase alloys. The optimum strain rate is found to shift into a faster region as the grain size decreases.
It is not widely appreciated that, currently, the largest consumption -byfar of lanthanides is in mixed-lanthanide forms. Such forms are based on ei-
ther "natural-ratio" or "modified natural-ratio" materials, where the "naturalratio"
is the inherent blend of the Ln elements in the dominant ore bodies. The reason for the choice of mixed-lanthanides is simple-such forms are the most economical. The same economics will obviously apply to new technologies under development such as, for example, solid oxide fuel systems based on lanthanide-containing ceramics and nickel-lanthanide hydride battery systems. Their commercialization depends on the availability and the economic accessibility of suitable raw materials, and, in many cases, that will mean using mixed-lanthanide derivatives-not pure lanthanide compounds. The production process from ore to mixed-lanthanide derivatives will be traced.
RARE EARTHS, SCIENCE, TECHNOLOGY AND APPLICATIONS I: Separation and Processing
10:00 am BREAK
Sponsored by: LMD Reactive Metals Committee Program Organizers: R.G. Bautista, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno, Reno, NV 89557; C.O. Bounds, RhonePolenc Rare Earths and Gallium, CN 7500, Prospect Plains Rd., Cranbury, NJ 08512; Timothy w. Ellis, Lulicke and Soffa Industries, Inc., 2101 Blair Mill Rd., Willow Grove, PA 19090; BarryT. Kilbourn, Molycorp, Inc., Executive 46 Office Center, 710 Route 46 East, Fairfield, NJ 07004 Wednesday, AM February 12, 1997
10:30 am Re-BASED METAL HYDRIDES AND NiMH RECHARGEABLE BATTERIES: L. Y. Zhang, Ph.D., Energizer Power Systems, Gainesville, FL 32614 The current status of metal hydride alloys for NiMH batteries was systematically reviewed. Extensive application-oriented R&D has successfully made the NiMH batteries an important part, with growing potential, among rechargeable batteries. The rare earth-based metal hydrides (AB,) have been considered the best alloy material for use in the negative electrode in NiMH batteries. However, being in demand for high performance by electronic markets, the still young NiMH industry is facing serious technical challenges in developing better products. Among other efforts to respond to the challenges, advanced AB, alloys are in great demand: the capacity enhancement race requires new or improved alloys processing higher volumetric capacity; high corrosion resistance when subjected to electrochemical cycling. Finally, price competition mandates MH materials with ow cost.
Room: Salon 8 Location: Clarion Plaza Hotel
Session Chairpersons: Renato G. Bautista, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno, Reno, NV 89557; K. OsseoAsare, Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802
8:30am MAGNETIC REFRIGERATION: KarlA. Gschneidner, fr. and Vitalij K. Pecharsky, Ames Laboratory and Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011-3020
11:00 am HIGH PERFORMING Sm(Co,Fe,Cu,Zr), POWDERS FOR THE BONDED MAGNET APPLICATION: W. Gong, B. M., Ma and C. O. Bounds, Rhone-Poulenc, Rare Earths and Gallium, CN 7500 Cranbury, NJ 08512
Magnetic refrigeration is based on the magnetocaloric effect (MCE), i.e. the temperature change (usually an increase) of a magnetic material near its mag180
The outstanding thermal stability and high energy product make Sm (Co,Fe,Cu,Zr), type alloys attractive for advanced applications. The near netshape production of Sm(Co,Fe,Cu,Zr), bonded magnets make them potentially superior to any magnets made by sintering. Although pioneering work done by Shimoda et al. And other investigators provide insights on the nominal compositional selection and process control of this alloy system, additional work is still necessary to improve our understanding of alloy behavior at various processing stages and to increase the production yield during powder processing. In this paper we report on the development of anisotropic Sm(Co,Fe,Cu,Zr), alloy powders for the bonded bonded magnet application.
mens moves the transition curve towards the DT curve but as little as 20 degrees for some materials. This leaves the DT specimen as the simplest existing specimen whose transition behaviour would approximate that of a structure. Data will be presented for 350WT and A517 steels. Refinement of the DT specimen to include an EDM notch as opposed to a machined and pressed notch may marginally reduce cost of testing. Relying on a shear lip width transition curve as opposed to an energy based transition curve can reduce the cost considerably. Data will be presented to show that shear lip width is related to the fracture energy of specimens over a wide range of temperatures, compositions and weldment locations. Finally data will also be presented to show that the relationship between shear lip and energy is independent of specimen thickness between 16 mm and 25 mm thickness.
RECENT ADVANCES IN FRACTURE V: Hydrostatic Pressure and Notch Effects on Ductile Fracture: A Symposium Dedicated to Professor Emeritus Frank A. McClintock
9:20 am INVITED A COMPUTER SIMULATION OF THE EFFECTS OF LOADING PATH ON THE MECHANICAL PROPERTIES OF POROUS COPPER: Anthony Kee, Peter Matic, Jennifer Morris and Andrew Geirmacher, Mechanics of Materials Branch, Code 6382, Naval Research Laboratory, 4555 Overlook Drive SW, Washington D.C. 20375
Sponsored by: MSD Flow and Fracture, SMD Mechanical Meta"urgy Program Organizers: Dr. R. K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; Dr. A. B. Geltmacher, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375; Dr. K. Sadananda, Naval Research Laboratory, Code 6323, 4555 Overlook Drive SW, Washington D. C. 20375; Dr. P. Matic, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375 Wednesday, AM February 12, 1997
The present research examines the local stress and strain rates generated during loading in porous copper specimens produced by the GASAR gas-eutec~ tic process, developed by Shapovalov and Timshenko. Two-dimensional explicit finite element simulations are performed on a representative microstructure taken from a 21.5 percent pore volume fraction bulk sample which contains high aspect ratio pores. The fraction bulk sample which contains high aspect ratio pores. The models investigate the role of multiple pore interactions and their effect on the mechanical properties of the porous materials. Previous research has shown the dependence of bulk strength and ductility on factors such as pore density, spacing, constraint and axial offset for uniaxial tensile loading. The present study extends the effort by applying biaxial and shear boundary conditions to the specimen, which simulates the effects of strain path on the deformation and fracture behavior of the porous materials. From these finite element models, the shape of the yield surface has been determined for the porous materials.
Room: 314A Location: Orlando Convention Center
Session Chairpersons: Professor Viggo Tvergaard, Department of Solid Mechanics, Technical University of Denmark, DK-2800 Lyngby, Denmark; Professor Peter K. Liaw, Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996
8:30 am INVITED
9:45am HIGH SPEED TEMPERATURE AND OPTICAL MEASUREMENTS OF DUCTILE FAILURE EVENTS IN METALS: Ares J. Rosakis, G. Ravichandran, Raman P. Singh, Graduate Aeronautical Laboratories, California Institute of Technology, Pasadena, CA 91125
DAMAGEACCUMULATIONANDDUCT~EFRACTURE-GLOBAL
AND LOCAL PERSPECTIVES: F. Zok 1, D. Lahaie2and John D. EmburY, IDepartment of Materials Science, University of California, Santa Barbara, Santa Barbara, CA 93106; 2Department of Materials Science and Engineering, McMaster University, 1280 main Street, Hamilton, Ontario, L8S 4L7, Canada
An experimental investigation has been conducted to study dynamic crack initiation in precracked highly ductile steel specimens. The specimens are fabricated out of 4340 mild steel and 304 stainless steel and SUbjected to dynamic three point bend loading by impacting them in a drop weight tower at various loading rates. This dynamic impact of the pre-cracked steel specimens results in deformation followed by fracture initiation at different loading rates. During the dynamic deformation and failure process the time history of the transient temperature and deformation fields around the crack tip are recorded experimentally. The transient temperatures are recorded using high speed infrared detectors, while the deformation fields are obtained using the optical method of Coherent Gradient Sensing (CGS) in conjunction with high speed photography. The experimental information is used to extract fracture parameters of interest, such as the time history of the dynamic J -integral (l"(t)) and its critical value at initiation (JdIni,'atio.) This is the first time that a noncontact temperature measurement is used to evaluate Jd(t). The applicability and accuracy of this technique is validated through comparison with the simultaneously performed CGS optical measurements. Finally, the data provided by the two techniques is used to identify various ductile failure mechanisms and quantify the fracture initiation toughness in terms of JdIniliation at different loading rates.
This presentation will consider the quantification of damage accumulation in metals and composites. Consideration will be given to the influence of hydrostatic pressure and strain path on nucleation and damage accumulation process. Models of fracture based on the influence of damage accumulation on both the stability of plastic flow and the attainment of critical damage levels will be discussed. In the final portion of the presentation, the use of damage accumulation in relation to the design of hydrostatic extrusion processes will be discussed. 8:55 am INVITED PREDICTION OF DUCTILE BEHAVIOUR IN WELDED STRUCTURES (DUCTILE TO BRITTLE TRANSITION BEHAVIOUR, SHEAR LIP, NOTCH ACQUITY, AND SPECIMEN SIZE): James R. Matthews, Dockyard Laboratory, Department of National Defence, Defence Research Establishment, Atlantic, Dartmouth, Nova Scotia B2Y 3Z7, Canada Design of ships against fracture requires, at the simplest level, that the minimum service temperature of the ship coincide with the upper shelf of the structural ductile to brittle transition curve for the steel and weldments. Material specifications in shipping standards often have no requirement for notch toughness and when they do specify toughness the specimen is of insufficient size and notch acquity to reflect the structural transition behaviour and to guarantee that the structure will be ductile at the lowest service temperatures. Consequently minimum standards should be adopted and specimen size and notch acquity requirements should be sufficient to predict ductile behaviour. In this paper, it will be shown that the transition behaviour for Charpy six specimens can be 50 to 100c C below that for larger DT specimens. It will he shown that replacing the standard notch with an EDM notch in Charpy speci-
10:05 am ANALYSIS OF FA~URE MODES IN IMPULSIVELY LOADED PRENOTCHED STEEL PLATES: Ramesh C. Batra, N.V. Nechitailo, Department of Engineering Science and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0219 We analyze transient plane-strain thermomechanical deformations of a prenotched 4340 steel plate impacted by a 4340 steel projectile in the direction of two parallel notches, and study the influence of the impact speed and notch
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tip radius on the localization of the defonnation. The plate configuration is identical to that in Kalthoff's experiments (1987, 1988). There is no failure or fracture criterion included in our work. However, the computed evolution of stress and plastic strain fields strongly suggest that with an increase of impact speed and decrease in notch tip radius, there is a failure mode transition from a tensile crack opening at approximately 70° to the notch ligament to an adiabatic shear band propagating at (-5°) - (-15°) to the notch ligament. This is in qualitative agreement with Kalthoff's findings. 10:25 am BREAK 10:35 am EFFECT OF STRAIN RATE ON THE FRACTURE TOUGHNESS REFERENCE TEMPERATURE To FOR FERRITIC STEELS: Kim Wallin, Materials and Structural Integrity Department, VTT Manufacturing Technology, P.O. Box 1704, FIN-02044 VTT, Finland The new master curve concept for describing materials fracture toughness in the transition region, with the help of a reference temperature To' is a candidate for structural integrity assessment codificaton. Nonnally, T)s determined for (quasi) static strain rates, while often dynamic values are required. The master curve concept can of course be applied also to dynamic tests, but this would require a double amount of testing. Therefore, if the effect of strain rate on To can be quantified with sufficient accuracy, the applicability of the master curve concept for structural integrity assessment codification would be strongly enhanced. For this purpose, fracture toughness data found in the literature was analyzed with the master curve concept, and, using the ZellerHollomon strain rate parameter, a simple semiemperical expression for the strain rate dependence of To was developed. The error of the expression is only of the order ±20% covering yield strength levels from 200 to 1400 MPa. 10:55 am DYNAMIC PLASTICITY OF DUCTILE MATERIALS AT THE MESOSCOPICAL SCALE LEVEL: Yuri l. Mescheryakov, Institute of the Mechanical Engineering Problems, Russian Academy of Sciences, Saint-Petersburg, V. O. Bolshoi 61,199178, Russia Dynamic tests of ductile materials (copper, aluminum, ductile steels) were carried out under uniaxial strain conditions to detennine the criterion of transition between translational (shear banding) and rotational modes of deformation. All the basic processes defining the mode of plastic defonnation were found to occur at the mesoscopical scale level (0.1 - 10 ~) and depend on the particle velocity distribution at that level. The later has been recorded with a velocity interferometer modified for measuring both average mesoparticle velocity and particle velocity dispersion simultaneously. The kind of kinematical mechanism (translational or rotational) is detennined by difference between longitudinal and transverse components of the mesoparticle velocity dispersion. This conclusion results from theoretical analysis of rotational motion of medium by using the mesomechanics approach. 11:15 am FLOW AND FAILURE OF HIGH DENSITY MATERIALS IN BALLISTIC IMPACTS: Lee S. Magness}, Jr., Deepak Kapoor2 and Moon Chung2, 'V. S. Anny Research Laboratory, Aberdeen, MD 21005; 2V. S. Anny Annament Research, Development and Engineering, Picatinny Arsenal, Dover, NJ 07806 High-density alloys and composites are employed as the penetrator core materials in modern armor-piercing projectiles. During ballistic impact with an armored target, the length of the penetrator core is eroded or back-extruded as a cavity is opened in the armor. The core material is defonned to very large strains at strain-rates exceeding 1()4 per second. The hydrostatic component of the stresses on the penetrator can exceed 5 GPa (1 Msi), suppressing void nucleation and growth as a fracture mechanism. However, plastic localization and failures (shear bands) are promoted by the high rate, adiabatic deformation. The ballistic perfonnances of a number of high-density alloys and composites are compared. Defonnation and failure behaviors are categorized via optical metallographic examinations of penetrators recovered from ballistic impacts.
11:35 am ANALYTICAL MODELING OF THE SHEAR MODE AND OPENING MODE OF DUCTILE FRACTURE: G. Rousselier and G. Barbier, Electricite de France, Research Division, Les Renardieres, F-77250 Moretsur-Loing, France Strain localization in the vicinity of a surface is a precursor to ductile fracture of materials. It can be analyzed by considering the stability of a linear perturbation. For a broad class of materials: plastic, rate-dependent, with void-growth damage and loading conditions: three-dimensional, thennomechanical and dynamic, a closed-fonn solution is obtained for the stability condition. From this condition, a mode of ductile fracture can be predicted: shear or opening. In a plastically incompressible material, the shear mode of fracture only is obtained; it results from a competition between strain hardening and thennal softening. In a void-growth damaging material, the opening mode is promoted by stress triaxiality. The analytical results are in agreement with experimental observations and numerical results from the literature. 11:55 pm LOADING RATE INFLUENCE OF FRACTURE TOUGHNESS IN INSTRUMENTED PRECRACKED CHARPY-TYPE TESTING: Thomas Varga and Friedrich Loibnegger, Technische Versuchs- und Forschungsanstalt, Technische Vniversitat Wien, A-I040 Wien, Karlspaltz 13, Austria The usual loading rate of impact testing is near to 0.5 mls. As it will be demonstrated, force-time and force-deflection diagrams show at least at the beginning strong oscillations. Investigations on realistic loading rates showed, however, in most practical cases effective loading rates below 0.1 mls. The loading rate of precracked Charpy-type testing is by using the Schnadt pendulum 0.1 mls. Because of this factor in nearly every situation a loading rate of 0.1 mls seems to be sufficient. If the loading rate is reduced from about 5 mls to 0.1 mls the force-deflection-diagram can be evaluated without parasitic oscillations. The measurement of fracture toughness, K;d' Jd and the calculation of CTOD becomes therefore easier. If the steels tested are sufficiently brittle, an extrapolation to the fracture toughness of larger sections becomes possible. Otherwise side grooving may help in obtaining realistic fracture toughness values. A comparison between fracture toughnesses measured at high and at low loading rates will be demonstrated. HSLA-steels, thennomechanically treated, will be used for the comparison. 12: 15 pm EXPERIMENTAL AND NUMERICAL STUDY OF THE INFLUENCE OF STRAIN HARDENING EXPONENT AND STRESS TRIAXIALITY ON CRACK INITIATION IN NOTCHED ROUND COPPER BARS: T. Pardon', I. Doghri" and F. Delannay', 'Vniversite Catholique de Louvain, Department des sciences des materiaux et procedes, PCIM, place Sainte Barbe 2, B-1348 Louvain-Ia-Neuve, Belgium; "Vniversite catholique de Louvain, Department de mecanique, MEMA, avenue G. Lemaitre 4-6, B-1348 Louvainla-Neuve, Belgium Local fracture criteria were applied to notched round copper bars with different notch radii. Four damage models were used in finite element simulation: the Rice & Tracey, Gurson & Tvergaard, Perrin & Leblond and Lemaitre & Chaboche models. Coalescence criteria such as a constant critical void growth rate or void volume fraction or a sophisticated stress dependent critical void radius (Thomason model) were analysed. The physical parameters of the models were identified by combining microscopic investigations supported by image analysis, damage quantification (especially, density measurements) and mechanical testing. Part of the bars were annealed in order to achieve a different strain hardening exponent without changing the inclusion distribution. The validity of the predicted void coalescence criteria is evaluated for different strain hardening exponents and different stress triaxilities.
12:35 pm DUCTILE FRACTURE TOUGHNESS EVALUATION AT HIGH STRAIN RATES USING STRETCH ZONE: M. Nari Bassim1 James R. Matthews2, 'Department of Mechanical and Industrial Engineering University of Manitoba, Winnipeg, Manitoba, Canada R3T SV6; 2Department of National Defence, Defence Research EstablishmentAtiantic, Dartmouth, Nova Scotia, Canada B2Y 3Z7.
9:00 am INVITED NUMERICAL INVESTIGATION OF MULTI-PHASE FLOW INDUCED POROSITY FORMATION IN SPRAY DEPOSITED MATERIALS: J.-P. Delplanque, E.J. Lavernia, R.H. Rangel, Department ofChemical Engineering and Materials Science, University of California,Irvine,Irvine, CA 92697-2575
Fracture studies of high strength low alloy steels, at very high loading (strain rates) of up to equal to 107 were conducted using specially designed Split Hopkinson Bar equipped with a swing arm mechanism capable of fracturing CT specimens with a thickness of 12.7 mm. While it was possible to reproduce the load-displacement curves for the specimens, evaluation of the fracture toughness was mostly obtained from post-test examination of the stretch zone ahead of the crack using scanning electron microscopy. Several factors affecting the stretch zone were identified including the effect of fatigue precracking as well as the method of measurement of the stretch zone (nine point vs. three point approach). Significant differences in the stretch zone were observed which are attributed to the extent of the constraint factor ahead of the crack due to fatigue precracking which demonstrates the occurrence of some nonlinearity in the initial part of the J -Stretch Zone Width relationship.
Several mechanisms have been recently identified as responsible for porosity formation in spray deposited materials. These mechanisms may be categorized according to their underlying fundamental nature; chemical (e.g., porosity generated by a foaming agent), physical (e.g, solidification shrinkage porosity), or dynamical (e.g., liquid-jet overflow). This investigation focuses on the latter category: pore formation mechanisms related to liquid metal flow and interactions between the flowing liquid metal and the irregular solid formed by the previously deposited droplets. These mechanisms are investigated using a combination of analytical models and detailed numerical simulations. The numerical model is based on a Navier-Stokes solver combined with the Volume Of Fluid method to track free surfaces. A multi directional algorithm is used to simulate the solidification process. The model case considered is that of liquid metal flooding of a random dense particle packing made of solidified droplets. Particular attention is devoted to cases where there is insufficient liquid to fill all the interstices and to capillary effects.
SPRAY FORMING - EXPERIMENT, ANALYSIS, AND APPLICATIONS I: Process Analysis
9:20am CALCULATION OF POWDER SIZE IN CENTRIFUGAL ATOMISATION AND SPRAY FORMING: Huiping Li, P. Tsakiropoulos, Department of Materials Science and Engineering, University of Surrey, Guildford, Surrey GU2 5XH, England, UK
Sponsored by: MDMD Shaping and Forming Committee, Jt. EPDIMDMD Synthesis Control & Analysis in Materials Processing Committee Program Organizer: Dr. Prabir K. Chaudhury, Concurrent Technologies Corporation, 1450 Scalp Avenue, Johnstown, PA, 15904; Prof. Enrique J. Lavernia, Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92717 Wednesday, AM February 12, 1997
A model of the flow of melts on rotating disks has been combined with models based on wave theory to predict the size of powder particles in centrifugal atomisation - spray forming. The analysis considers the role of process parameters and materials properties on powder size. The dependence of powder particle size on disk diameter and rotating speed as well as type of melt are calculated and compared to experimental results.
Room: 330B Location: Orlando Convention Center
9:40am NUMERICAL SIMULATION OF GAS ATOMIZATION IN SPRAY FORMING PROCESS: Huimin Liu, Concurrent Technologies Corporation, 1450 Scalp Avenue, Johnstown, PA 15904
Session Chairperson: Prof. Enrique J. Lavernia, Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92717; Dr. Prabir K. Chaudhury, Concurrent Technologies Corporation, 1450 Scalp Avenue, Johnstown, PA, 15904
The spray forming process is emerging as a cost-effective manufacturing route for net and near-net shape preforms in a wide range of materials. In the past, numerical simulations have been made to model the melt delivery, the spray deposition, and the consolidation stages in the spray forming process. However, the atomization stage, particularly gas flow in the nozzle-close region and melt break-up kinetics, have not been adequately simulated. Atomization is a key stage in the spray forming process because it determines the size, size distribution, and initial conditions of the particles, hence, influences particle velocity, temperature, cooling rate, microstructure, and thus the mechanical properties of the spray-formed preforms. This work uses numerical tools to model atomization mechanisms. The full compressible Navier-Stokes equations are solved to simulate the gas flow in the nozzle-close region. The melt flow and heat transfer are modeled on the basis of the boundary layer theory and the modified van Driest and Cebeci mixing-length turbulence model. The information on the flow and temperature fields obtained from the numerical simulation is then used to investigate melt break-up and droplet formation during atomization.
8:30 am KEYNOTE THERMO-FLUID ISSUES IN SPRAY FORMING: Michael M. Chen, University of Michigan, Ann Arbor, MI, 48109-2125; Dawn White Ford Scientific Laboratories, Dearborn, MI, Chuan Li, University of Michigan, Ann Arbor, MI, 48109-2125 A critical review on the heat transfer and fluid mechanical issues of spray forming will be presented. The paper will focus on those thermo-fluid issues which have important influence on the spray and solidification processes as well as the properties of the product, combining the perspectives of materials and manufacturing scientists and specialists in heat transfer and fluid mechanics. Among the topics to be considered are atomization, dynamics of sprays, including oversprays, droplet solidification, splat formation due to impact of liquid droplets and partially solidified particles with the substrate, heat transfer and solidification in the formed part, and residual stress formation. Emphases will be placed on current levels of understanding of the physics from a first principles point of view, semi-quantitative estimates of the length and time scales of interest, and current capabilities for accurate modeling and prediction. Recommendations for future research and development will also be made, based on results of the survey.
10:00 am BREAK 10:20 am MODELING OF OSPREY SPRAY METAL FORMING PROCESS: T.R. Govindan, The Pennsylvania State University, Applied Research Laboratory, P.O. Box 30, North Atherton Street, State College, PA 16804-0030 A detailed computational model of the spray metal forming process is being developed. The model provides process figures of merit, identify process control parameters, and help process design in support of the process development activity. The core of the model is an Eulerian-Lagrangian flow solver in which the gas phase is treated in an Eulerian framework involving the Reynolds Averaged Navier-Stokes equations and the droplets are treated as a discrete
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phase involving single particle dynamics. Statistics are generated from the discrete phase by computing a large sample of particle "trajectories" in the force field due to the gas phase. In turn, particle statistics generate forces in the gas phase equations. Models are used in the discrete phase for particle drag, heat transfer, and solidification. The computer code is capable of handling complex three-dimensional geometries. Results will be presented showing details of the two-phase flow in a typical Osprey spray chamber; gas flow velocity and temperature distributions, gas flow and droplet interactions, droplet cooling curves and deposition profiles. Computed results will be compared with available experimental data.
atomizing gas flow. During spraying of mild steel with nitrogen, the nitrogen content of droplets sampled at various locations within the spray cone is investigated. The results of the in-flight interaction of the sprayed dropletes with the ambient atmosphere are discussed. 11:40 am THE ROLE OF ALUMINA PARTICULATE IN MICROSTRUCTURAL AND FORGING PROPERTIES OF SPRAY ATOMIZED AND DEPOSITED Fe-AI ORDERED INTERMETALLIC COMPOUNDS: L. Martinoz, M. Amaya, O. Flores, Instituto de Fisica, UNAM, A.P. 48-3, 62251, Cuernavaca, Morelos, Mexico; D. Lawrynowics, R.J. Lavernia, Department of Chemical Engineering & Materials Science, University of California, Irvine, CA 92697-2575
10:40 am INVESTIGATION OF THE PROCESS PARAMETERS CONTROLLING THE MICROSTRUCTURAL CHARACTERISTICS AND THE POROSITY OF SPRAY DEPOSITED TANTALUM ALLOYS: l.-P. Delplanque, W.D. Cai, R.H. Rangel, EJ. Lavernia, Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697-2575
Spray atomization and deposition, hot isostatic pressing, and forging at high temperatures were used for processing FeAl intermetallic compounds alloyed with Boron and fine alumina particulates. Extensive optical microscopy, SEM, and TEM studies, as well as mechanical properties characterization are described. The alumina particulate play a role in refining and stabilizing the material microstructure and improves forgeability. The advantages of spray atomization and deposition are discussed. Work supported by CONACYT grant 3878A.
An induction skull melting (ISM) spray forming process was used to investigate the spray atomization and deposition of tantalum alloys. Several systems were considered in order to tackle the scientific issues inherent to the spray forming of refractory metals in a gradual manner. Optical microscopy, X-ray diffraction and scanning electron microscopy were used to characterize the spray formed materials and oversprayed powders. A theoretical and numerical analysis of the deposition and solidification of tantalum alloy droplets was conducted concurrently. This approach is based on a multi-directional solidification model combined with a Navier Stokes solver for flows with interfaces. Various droplet size and impact velocities consistent with the experiments were considered. The simulation results and the experimental data were compared and analyzed in order to identify the critical process parameters controlling the microstructure and porosity of as-deposited tantalum alloys.
STRUCTURE AND PROPERTIES OF INTERNAL INTERFACES V: Interfaces and Plastic Deformation Sponsored by: Jt. EMPMD/SMD Chemistry & Physics of Materials Committee, MSD Computer Simulation Committee Program Organizer: Diana Farkas, Dept. of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061; Elizabeth A. Holm, Sandia National Lab, Physical and Joining Metallurgy, MS 1411, Albuquerque, NM 87185-0340; David J. Srolovitz, Dept. of Materials Science & Engineering, University of Michigan, Ann Arbor, M148109-2136
11:00 am DROPLET ENTHALPY MEASUREMENT BY CALORIMETRY FOR CONTROLLED SPRAY FORMING: C. Tuffile, A. DiVenuti, Department of Mechanical Engineering, Tufts University, Medford, MA01255; T. Ando, Department of Mechanical, Industrial and Manufacturing Engineering, Northeastern University, Boston, MA 02115; lH. Chun, Laboratory for Manufacturing and Productivity, Massachusetts Institute of Technology, Cambridge, MA02139
Wednesday, AM February 12, 1997
Room: 330G Location: Orlando Convention Center
Session Chairperson: Diana Farkas, Dept. of Materials Science and Engineering, Virginia PolytechniC Institute and State UniverSity, Blacksburg, VA 24061-0237
8:30 am INVITED MAKING LINKS BETWEEN GRAIN BOUNDARY CHARACTER DISTRIBUTIONS AND POLYCRYSTALLINE PROPERTIES: Alexander H. King, Department of Materials Science and Engineering, State University of New York at Stony Brook, Stony Brook, NY 11794-2275
A non-adiabatic calorimetric method was developed and used to determine the enthalpy of droplets in a spray as a function of flight distance with the purpose of providing critical information for the controlled spray forming using uniform-droplet sprays (UDS). A UDS consists of droplets that are uniform in size and thermal history and can be used to produce a variety of novel deposit microstructures in a controlled manner. Such controlled spray forming, however, requires thorough characterization of the thermal state of the uniform droplets. The calorimetric method developed accounts for the heat loss that occurs while collecting the droplets in the calorimeter, and uses a data acquisition system for in-situ determination of droplet enthalpy. Comparison of measured droplet enthalpy values and those predicted by model calculations shows a very good agreement.
Automated orientation analysis makes it possible to perform an "epidemiological" kind of materials research in which the occurrence of certain types of grain boundary is associated with certain types of polycrystalline property. What is left out of many studies of this kind, however, is the causal link that relates a certain grain boundary character distribution to a particular polycrystalline behavior. In this presentation, I will caution that focusing upon the grain boundary character in terms of "small-angle," "coincidence-related" and "general" categories can be misleading. I will provide a number of examples to show that these are not always the important (or desirable) features of the grain boundary character distribution, drawing my illustrations from work on high-Tc superconductors and metallic polycrystalline thin films. Finally, if time permits, I will comment upon the characterization of triplejunctions and show, once again, that currently popular types of characterization are seriously misleading. Acknowledgment: This work is supported by the National Science Foundation, under grant number DMR-9530314.
11:20 am SIMULATION OF THE SPRAY FORMING PROCESS USING A WIRE-FED LASER TECHNIQUE: T. Seefeld, E. Schubert, G. Sepold, Universitat Bremen, VerfahrenstechniklFB4, Postfach 330440, D-28334 Bremen, Germany The spray forming process offers advantages for both material properties and process technology. A deeper understanding of the spray forming process, with particular concern to the complex disintegration phase and the formation of the deposit. The present work introduces an experimental set-up to investigate the in-flight behavior of sprayed droplets. In a chamber with controlled atmosphere, a spray cone is wire. This process allows to skip the complete melting unit of a spraying facility and facilitates maintaining a spraying experiment for a desired period of time (a couple of minutes generally) and changing the set of parameters for the next experiment within minutes in order to save time diameter and feed rate, laser beam power and intensity, and
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9:10am THE STRUCTURE OF DEFORMATION INDUCED HIGH ANGLE BOUNDARIES: D.A. Hughes, Materials and Engineering Sciences Center, Sandia National Labs., Livermore, CA 94550
10:10 am EFFECT OF THE MAGNITUDE OF GRAIN BOUNDARY DISLOCATION BURGERS VECTORS 0 DISSOCIATION OF EXTRINSIC GRAIN BOUNDARY DISLOCATIONS: S.G. Song, 1.S. Vetrano, S.M. Brummer, Structural Materials Interfaces, Pacific Northwest National Laboratory, Richland, WA 99352
Internal interfaces develop during deformation at the places where grains subdivide. Some of these interfaces develop into high angle boundaries that subsequently have a large effect on the materials properties including local crystallographic textures, flow strength and annealing behavior. The structure of very high angle boundaries (>30=BO) formed during deformation by dislocations and texture processes was examined using transmission electron microscopy and convergent beam diffraction. The large misorientation angles that develop by these processes are similar to those angles encountered in ordinary grain boundaries. These boundaries are characterized according to their angle/axis pair, boundary plane, tilt/twist character, thickness, sigma value and their association with trapped glide dislocations. In general these boundaries have a complex character and are not low sigma boundaries. The structure of these deformation induced boundaries is then compared to that of equilibrium grain boundaries such as those that form during recrystallization. This work supported by U.S. DOE under contract No. DE-AC04-94AL8500.
The concept of Burgers vectors of secondary grain boundary dislocations (SGBDs), resulting from the dissociation of extrinsic grain boundary dislocations (EGBDs), in general grain boundaries can be extrapolated from those of GBDs in CSL boundaries. Increasing CSL boundary index results in the decrease in magnitude of the basis vectors of the corresponding DSC lattice on which the Burgers vectors of the SGBDs are determined. There exists a critical size of the elementary Burgers vectors of the dissociated grain boundary dislocations. Below this value, an EGBD disappears eventually after the SGBDs resulting from the dissociation spread to a sufficient distance that is dependent on temperature and instrument parameters. On the other hand, the resulting SGBDs are always visible if their Burgers vectors are above the critical size. 10:30 am BREAK
9:30am ANALYSIS OF TWINS AND STACKING DEFECTS IN THE CUBIC LAVES PHASE OF THE Hf-V-Nb ALLOY SYSTEM: D.E. Luzzi, D.P. Pope, A. Goldberg, G. Rao*, Dept. of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104-6272;*PresentAddress: Applied Materials Corporation, Santa Clara, CA
10:50 am INVITED CONTROL OF METAL PRECIPITATE MORPHOLOGY BY SOLID STATE REACTIONS: Monika Backhaus-Ricoult, CECM-CNRS, 15 Rue G. Urbain, F 94 407 Vitry sur Seine Internal reduction of transition metal doped mixed oxides yields formation of fine dispersion of metal particles within the oxide matrix. Selection of special reaction parameters like oxygen partial pressure gradient, reaction temperature, chemical composition of the mixed oxide and the type of matrix oxide and dopant allows to control the microstructure of the reduced scale, the morphology of the metal precipitates and the fine-structure of the metal-ceramic interfaces down to an atomic scale. Experimental results for different mixed oxides containing magnesia, alumina or zirconia will be reported. Growth and thermodynamical equilibrium shapes of the precipitates will be presented. Precipitate morphology, relative orientation relationship and interface fine structure will be interpreted in terms of the diffusion field (which allows the metal precipitation), the chemical reaction at the precipitate interface, the interface energy and its anisotropy and the mechanical response of the system to solid state reaction related stresses.
The brittle nature at low temperatures of Laves phase intermetallic compounds remains a major obstacle to the use of these complex-structured materials for their excellent high temperature properties. Deformation by twinning is seen as a possible mechanism by which to obtain acceptable levels of ductility and toughness at low temperatures. In this paper, the microstructures of a cubic HfV'+Nb Laves phase is studied before and after compressive deformation using conventional and high-resolution electron microscopy. The Laves phase occurs as precipitates within a matrix of a V-Nb bcc solid solution. In the underformed material, narrow stacking defects with thicknesses of from one to three times the (111) interplanar spacing are seen lying on the (111) crystallographic planes. The distribution of these defects is anisotropic on the mesoscopic scale with spacings ranging from approximately 2 nm to over 200 nm. The deformed material shows extensive twinning of the Laves phase precipitates. The twins occur in clusters and twin bands as small as 2 nm in width are seen. Analysis of the structure of the stacking defects and twins and comparisons between the meso scopic distributions of stacking defects in the undeformed materials and twins in the deformed materials will be presented.
11:30 am INTERFACIAL DEBONDING IN MULTI-LAYER THIN FILM SYSTEMS: X.H. Liu, C.F. Shih, Division of Engineering, Brown University, Providence, RI 02912
9:50 am DISSOCIATION MECHANISMS FOR EXTRINSIC GRAIN BOUNDARY DISLOCATIONS: S.G. Song, 1.S. Vetrano, S.M. Bruemmer, Pacific Northwest National Laboratory, Richland, WA 99352
To improve the reliability of electronic devices, it is important to understand the interfacial debonding of multi-layer thin film systems. The interfacial fracture energy can be measured experimentally using a sandwich four-point bending specimen. This interfacial fracture energy includes both the intrinsic debonding energy of the metal/ceramic interface and the plastic dissipation in the metal layers. The plastic dissipation makes a substantial contribution to the interfacial fracture energy. In contrast to the plastic dissipation, which depends on the layer thickness, the intrinsic debonding energy is a material property of the interface and is important in the evaluation of interface adhesion and design of multi-layers. A micromechanical model is used to investigate interfacial debonding. From the model the intrinsic debonding energy can be obtained using the measured interfacial fracture energy. The effects of interfacial adhesion and metal layer properties on the interfacial fracture energy are discussed.
The plastic deformation of grain boundaries (GBs) is central to the understanding of a wide range of materials behavior including superplasticity and creep. In analogy to the bulk deformation carried out microscopically by lattice dislocations, GB deformation cannot occur without the involvement of grain boundary dislocations (GBDs). The present investigation examines the stability of extrinsic GBDs in AI alloys. It is found that the dissociation of extrinsic GBDs not only is a function of temperature but also of other variables such as solute content and GB structures. Given a boundary structure, the Burgers vectors of the secondary GBDs, resulting from the dissociation of extrinsic GBDs in general GBs, can be predicted based on the DSC-lattice. The visibility of the secondary dislocations varies with the magnitude of their Burgers vectors. The GBD stability of different boundary misorientations is compared so that common properties of grain boundary plastic behavior can be drawn. Work supported by the Materials Division, Office of Basic Energy Sciences, U.S. Department of Energy under Contract DE-AC06-76-RLO 1830.
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9:10am HIGH TEMPERATURE DEFORMATION BEHAVIOUR OF MECHANICALLYALLOYEDAI-10Ti-XSIALLOY: C.J. Choi, w.w. Park, Department of Materials Processing, Korea Institute of Machinery and Materials, 66 Sangnam-Dong, Changwon, Kyungnam 641-010, S.Korea ; 1.K. Park, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1 Kusong-Dong, Yusong-Gu, Taejon 305-701, S. Korea
SYNTHESIS OF LIGHT-WEIGHT METALLIC MATERIALS II: Session V: Powder Processing I Sponsored by: MSD SynthesisIProcessing Committee Program Organizers:C.M. Ward-Close, Structural Materials Center, R50 Building, Defense Research Agency, Farnborough, Hampshire, GU14 6TD, United Kingdom; F.H. Froes, University of Idaho, Institute for Materials and Advanced Processes, Mines Bldg 204, Moscow, ID 83844-3026; D.J. Chellman, Lockheed Aeronautical Systems Co., Lockheed Corporation, Marietta, GA 30063-0150; S. S. Cho, Vice President of Rapidly Solidified Materials Research Center, (RASOM), Chungnam National University, Taedok Science Town, Taejon 305-764 Korea Wednesday, AM February 12, 1997
The creep property of mechanically alloyed AI-I0Ti-xSi (in wt%, x=O,2 4) alloy was investigated in a wide range of stress (60-3IOMPa) and temperature (3OO-450°C). Creep mechanisms were analyzed in some details and compared with each other. Two distinctive creep mechanisms have been observed depending on the testing stress and temperature, ie, Coble creep at low stresses and temperatures and dislocation creep at high stresses and temperatures. True creep activation energies in dislocation creep regime were calculated using modified semi-emperical creep equation. The calculated values were in good agreement with that for self lattice diffusion in pure aluminium. The diffusional (Coble) creep regime significantly enlarged to high stress and temperature region with an increase of Si content due to an increasing volume fraction of dispersiods.
Room: 330F Location: Orlando Convention Center
Session Chairpersons: T.H. Sanders, Georgia Institute of Technology, Atlanta, GA 30332-0245; G. Das, Pratt and Whitney, POBox 109600, West Palm Beach, FL33410-9600
8:30am STABILITY OF NANOCRYSTALLINE MICROSTRUCTURES IN A Ti-47_5A1-3Cr ALLOY PRODUCED BY MECHANICAL ALLOYING AND HOT ISOSTATIC PRESSING: N. Srisukhumbowomchai, M.L. Ovecoglu', O.N. Senkov, and F.H. Froes, Institute for Materials and Advanced Processes, University ofIdaho, Moscow, ill 83844-3026, USA; 'Department of Metallurgical Engineering, Faculty of Chemistry & Metallurgy, Istanbul Technical University, Maslak, Istanbul 80626, Turkey
9:30am MECHANICAL ALLOYING OF Ti-Ni BASED MATERIALS USING THE HORIZONTALATTRITOR: H. Zoz I, D. Emst2,I.S. Ahn3, W.H. Kwon4 ,IZOZ GmbH, D-57482 Wenden, Germany; 2University of Siegen, D57068 Siegen, Germany; 3Gyeonsang National University, Chinju, Gyeongnam, 660-701 Korea The production of large quantities of contamination free mechanically alloyed powders from titanium and nickle based materials has proven to be a major challenge. Feasibility of such a goal can be carried out, at laboratory level, by any milling device like the very common planetary ball mill. In this case however, the possibility of a subsequent scaling up for larger production is hindered by the intrinsic limits of a planetary ball mill design. On the contrary the horizontal Zoz attritor can be experimented at laboratory level using small volume chamber-units (0.25, 0.5, and 2.1) and, for industrial production, using the large volume units (up to 400 1) based on the same conceptual design. Therefore, experiments have been conducted on blended elemental Ti-Ni compositions in the proportions Ti-51.5Ni, Ti-50Ni, Ti-49.sNi and Ti48.5Ni (at %) using a Zoz attritor with a small unit-chamber (0.51). Due to the inherent ductility of the powder, the material has the tendency to adhere to the grinding unit and the grinding media. Further, in order to avoid high contamination and to make the process realistic from an economical point of view, the milling time has to be reduced to a minimum. The above points identify a Critical Milling Behaviour (CMB) of the system under investigation that must be kept under control to achieve the wanted goal. It will be shown by the present paper that by adopting a suitable milling and discharging procedure (Cycle Operation by Operation Cycle and Discharging Cycle) low contamination and good yield have been substantially achieved. This is investigated by chemical analysis, by scanning electron microscopy and xray diffraction.
Fully dense nanocrystalline Ti-47.5AI-3Cr intermetallic compacts were produced by mechanical alloying and hot isostatic pressing. Grain growth behaviour of these compacts was studied in the temperature range of 725 to 1100 °C for annealing times of 0 to 500 hours, using analytical transmission electron microscopy techniques. The temperature and time dependencies of the grain sizes and the grain size distributions were determined, allowing the evaluation of the prevailing transport mechanism responsible for the growth of nano-sized grains to be defined. 8:50am PHASE FORMATION AND PROPERTIES OF MECHANICALLY ALLOYED Mg-BASED MULTICOMPONENT LIGHTWEIGHT ALLOYS: J. Eckert, N. Schlorke, C.A.R.T. Miranda l , and L. Schultz Institute fur Festk"rper-und Werkstofforschung Dresden, Institute fur Metallische Werkstoffe, D-Oll71 Dresden, Germany; IPermanent Address: LIJO-Barcelos, Portugal Multicomponent Mg-Y-Cu lightweight alloys were prepared by mechanical alloying of elemental powder mixtures. The progress of alloying, the resulting phases and their thermal stability were characterised by x-ray diffraction, differential scanning calorimetry (DSC) and thermo-mechanical analysis (TMA). Coexistent amorphous and nanoscale crystalline phases are found for a variety of alloys with different composition. The thermal stability data of the materials as obtained by constant-rate heating DSC and TMAmeasurements and isothermal annealing experiments are discussed with respect to phase separation in the undercooled liquid state and nucleation and growth of nanocrystalline phases. Some characteristic properties of the glassy phase are presented and discussed with respect to the composition dependence of the glass transition and the crystalline temperature. The results are compared with data for melt-quenched samples. Finally, the influence of processing conditions and contamination effects during milling on the phase formation and the thermal stability of the mechanically attrited powders is critically assessed.
9:50am MICROSTRUCTURAL EVOLUTION OF MECHANICALLY ALLOYED AND HOT ISOSTATICALLY PRESSED NANOCRYSTALLINE Ti-47.5A1-3Cr ALLOY DURING ANNEALING AT 120°C AND AIR COOLING: M.L.Ovecoglu t , O.N.Senkov, N.Srisukhumbowomchai, N. Hoo, C.M. Ward-Close, P. Goodwin, P.Tsakiropoulos, EH. Froes, Institute for Materials and Advanced Processes University of Idaho, Moscow, ill 83844-3026; IDepartment of Metallurgical Engineering, Istanbul Technical University, Maslak, Istanbul 80626, Turkey; DRA Farnborough, Hampshire, UK; University of Surrey, Guildford, Surrey, UK Mechanical alloying and hot isostatic pressing techniques were employed to synthesise a fully dense Ti-47.sAl-3Cr alloy containing equipped nanocrystalline yTiA 1 grains. Isothermal annealing was conducted at 1200°C (above the eutectoid transformation temperature) at holding times of 5, 10, 25 and 35 hours. Analytical transmission electron microscopy investigations revealed the presence of a dual structure comprising a./r laths and equipped g grains some of which were twinned. The grains coarsened during annealing and the a./r laths were formed during cooling as a result of the eutecroid
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transformation. At the maximum annealing time studied (35 hours), the average grain size of grains was about 2 mm and the width of the a.,Ir laths was 0.3mm.
11:30 am MICROSTRUCTURE· PROPERTY STUDIES IN AL·8Fe·4Ni·2 5Zr ALLOYS: P Keramidas, P Tsakiropoulos. Department of Materials Science and Engineering, University of Surrey, Guildford, Surrey GU2 5XH, England, UK
10:10 am BREAK 10:30am CHARACTERISATION OF A Ti·48AJ·2Nb·2Cr ALLOY SYNTHE· SIZED FROM MIXED GAS ATOMIZED AND MECHANICALLY ALLOYED POWDERS: O.N. Senkov, N. Srisukhumbowarnchai, M.L Ovecoglu', N. Hoo, C.C. Ward-Close', P. Goodwin', P. Tsakiropoulos', F.H. Froes, Institute for Materials and Advanced Processes, University of Idaho, Moscow, ID 83844-3026; 'Department of Metallurgical Engineering, Istanbul Technical University, Maslak, Istanbul 80626, Turkey; 'DRA Farnborough, Hampshire, UK; University of Surrey, Guildford, Surrey, UK
The microstructures of shill cast ingots, gas atomised powders and extruded bars of AI-8Fe-4Ni-2.5Zr (wt%) were studied. Phase selection in the wedge shaped ingots and in the gas atomised powder particles will be discussed. The microstructures of the as extruded and heat treated alloy will be presented and related to the hardness, tensile properties and texture of the alloy. The latter will be compared to the properties of AI-8Fe-4Ni and the effects of Zr addition on the properties of the alloy will be discussed. 11:50 am STRUCTURE AND PROPERTIES OF RAPIDLY SOLIDIFIED AI·Li· Cu·Mg ALLOYS CONTAINING Zr AND Ag: V.G. Pushin, L.1. Kaigorodova, E.!. Selnikhina, Institute of Metal Physics, Ural Division of Russian Academy of Sciences, + 1620219, +0+ I Ekaterinburg, Russia
Gamma TiAI based compacts were synthesized by hot isostatic pressing (HIP'ing) a mixture of pre-alloyed Ti-48AI-2Nb-2Cr gas atomized and mechanically alloyed powders. Mechanical alloying of the initial powder was performed in a SPEX mill for 15 hours. HIP'ing was conducted at 850°C under 206 MPa pressure. '!\vo different volume proportions of the gas atomized and mechanically alloyed powders were utilized in the HIP'ing process. This allowed production of microstructures in HIP'd compacts: a homogeneous nanocrystalline structures, when 100% mechanically alloyed powder was used, and a bimodal structure consisted of the mixture of micron-sized and nono-sized grains, when the compacts were IDP'd from a blend of the gas atomized and mechanically alloyed powders. Evolution of the microstructure during mechanical alloying and HIP'ing was studied by XRD, SEM and TEM techniques.
Rapidly solidified Al-Li-Cu-Mg alloys prepared by argon atomization process were investigated. Using cold compaction and canning, the powder was hot extruded into a bar of diameter 17 mm. Compared with traditional ingot metallurgy alloys, the microstructure and properties of rapidly solidified powder metallurgy alloys has been significantly improved. The effects of adding minor Zr, Ag or rare earth (RE) Nd and La on the Al-Li-Cu-Mg alloys are different. Minor Zr and Ag can efficiently accelerate the ageing process and increase the strength and hardness of alloys. Minor RE raises the ductility. The microstructure of alloys forms due to precipitation process of metastable binary phase Al(3)Li, ternary Tl-phase Al(2)CuLi with hexagonal crystal structure, and also tetragonal metastable phases on base of Al(2)Cu. These three coexistent channels of phase transformations are responsible for strengthening of alloys during subsequent ageing. The particle size of atomized powder for alloys was in the range of 1O-15Onm, but after optimal thermo-mechanical treatments the microstructure of alloys has been significantly dispersed and more refined. The grains are more homogeneous and have a nano-scale size on the average. In this state particles of this phase has a globula form and preferably heterogenuons nucleation at consequent aging.
10:50am FLOW AND COOLING CHARACTERISTICS OF AL·SI DROPLETS! PARTICLES DURING GAS ATOMIZATION: Seong-Yeon Yoo, SangYoon Lee; Rapidly Solidified Materials Research Center, Department of Mechanical Design Engineering, ChungnamNationaI University, Taejon, 305764,KOREA There are two important parameters in gas atomization - particle size and cooling rate. These two parameters are mainly controlled by gas flow and heat transfer between gas and droplets!particles. The purpose of this research is to investigate flow structure, cooling rate and trajectory of Al-Si droplets! particles by numerical simulation. Gas flow is simulated using finite volume method, and particle trajectory is simulated using Eulerian method. RosinRarnmler formula is used for the particle size distribution. Gas field influences particle trajectory, reversely particles alter the gas field. So momentum and heat exchange between gas and particles are calculated by iterative method. Particle trajectory is found to depend on particle size, the location of particle formation, and turbulent motion of gas. Cooling rate of particles is calculated by taking into account latent heat of melt and local heat transfer between particle and gas. Small particle cools down rapidly, while large diameter particles solidifies very slowly.
THE INCREASING IMPORTANCE OF SECONDARIES &RESIDUES IN PRIMARY &SECONDARY CU/Ni SMELTING: Its Technical, Economic and Environmental Effects Sponsored by: EPD Copper, Nickel, Cobalt Committee Program Organizers: Norbert L. Pi ret, Piret & Stolberg Partners, 1m Licht 12, D· 47279 Duisburg, Germany; Paul B. Queneau, Hazen Research, Inc., 4601 Indiana St., Golden, CO 80403 Wednesday, AM February 12, 1997
11:10am PREPARATION OF Ti POWDER BY A MECHANICAL MILLING INDUCED REDUCTION REACTION: E.G. Baburaj, Kevin T. Hubert, Carl Powell, C. Suryanarayana and F.H. Froes, IMAP, University of Idaho, Moscow, ID 83844-3026
Room: 340D Location: Orlando Convention Center
Session Chairpersons: N.L. Piret, Piret &Stolberg Partners, 1m Licht 12, D-47279 Duisburg, Germany; Paul B. Queneau, Hazen Research, Inc. 4601 Indiana St., Golden, CO 80403
A displacement reaction between TiC I 4and Mg, induced by mechanical milling, has been employed for preparation of fine Ti powder. The present work shows the possibility of considerable reduction in milling time by the use of pre-milled Mg which enhances the reactivity due to an increase in surface area and surface activity. The milled product has been leached repeatedly to obtaining pure Ti. The reaction products before and after leaching have been examined by XRD, SEM, and TEM. The product after leaching, as determined by XRD is pure Ti. The particle size, as observed by TEM is in the range of 5-200nm. The EDX analysis of individual crystals or agglomerates using TEM, does not show the presence of chloride. Small amount of oxygen and nitrogen as impurities have been detected. Further work on the analysis of the powder is in progress.
8:30 am INVITED WASTE DISPOSAL BY RESIDUE RECYCLING AT KGHM POLSKA MIEDZ SA: Helena Byrdziak, Jerzy Dobrzanski, Jan Garbaczewski, Janusz Piatkowski, KGHM Polska Miedz SA, P-59300 Lubin, UI. Sklodowskiej 48, Poland KGHM Polska Miedz SA, existing since seventies, operates three underground mines and three smelters with local production of over 400,000 mtpy of electrolytic copper. Its impact on the environment, very serious in the past, has been gradually reduced, In general, recently emission into the air and water has been put under control. Nowadays tailings and residues disposal has turned to be the subject of first environmental importance. The total bulk of tailings
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is enormous as copper ore contains only about 2% of copper, so 98% of extracted material must be disposed gradually in each step of technology. The main Streams are tailings from the flotation, slags, captured dust from dedusting systems and gaseous compounds like S02 and CO. Much effort has already been done and is still being done to utilize them for by-products production or to dispose them within the process by recycling. The most effective measures taken up so far and present activity towards waste disposal are presented.
CHANGES IN THE DUST HANDLING SYSTEM AT HUDSON BAY MINING & SMELTING CO., LTD: Keith McTaggart, Hudson Bay Mining & Smelting Coo., Ltd, P.O. Box 1500, Flin Flon, Manitoba R&A 1N9, Canada The waste gas cleaning system of the Hudson Bay Mining & Smelting copper smelter in Flin Flon, MB, consists of an electrostatic precipitator followed by a baghouse. These units collect the copper and zinc bearing dusts, respectively, from the gas streams of the reberberatory furnace and PierceSmith converting furnaces. A process change in 1993 led to the rapid destruction of the existing baghouse fibreglass filter bags, shortening their life-span from 15 to 3 months. A decision was made in September 1994 to replace this type of filter media with an expanded polytetrafluoroethylene (PTFE) membrane filter supplied by WL. Gore Associates, Inc. Following the original installation a dramatic increase in dust capture was observed, however high pressure drops across the filter material lead to decreased flow through the off-gas handling system, limiting ventilation of the process. This increase in pressure drop across the PTFE bags was a function of the PTFE material and the inability of the baghouse shaker system to release the dust layer from the PTFE bags. Recently acoustic horns have been tested as a replacement to the shaker cleaning mechanism. Preliminary results indicate a dramatic reduction in pressure drop across the bags and a subsequent increase in process ventilation. This allows for fewer production interruptions caused by fugitive process emissions. The final acoustic horn results will be presented.
9:00am RECYCLING OF PRINTED CIRCUIT BOARDS BY SMELTING WITH OXIDIZINGIREDUCING TOP BLOWING PROCESS: Andrea Bernardes, Isrun Bohlinger, Diosnel Rodriguez, Wolfgang Wuth, Technical University Berlin, Institute of Metalllurgy, Straj3e des 17. Juni 135, D-10623 Berlin, Germany Printed circuit boards (PCBs) of varying compositions have been converted by incineration, followed by smelting to an environmentally stable slag and a copper-nickel-tin alloy, containing the precious metals. The environmentally compatibility of the slag was established according to the German Standard DIN 38414, Part 4. The concentration of toxic elements in the lixiviates was found to be lower than the threshold value for drinking water (CE-Standards). In each experiment the charge was 500 g scrap from PCBs and 100 g flux. The products were a king of mullite slag, poor in iron, which was recirculated, and an alloy containing up to 0.3% gold. With a burner the process gas was combusted without soot formation and the generated mixed zinc-lead oxide fume containing silver was separated as flue dust.
11:00 am INVITED THE ECONOMIC AND ENVIRONMENTAL BENEFITS OF AUSMELT TECHNOLGY IN SECONDARY COPPER SMELTING AND CONVERTING: Edward N. Mounsey, Ausmelt Ltd., 12 Kitchen Rd., Dandenong 3175, Victoria, Australia; Norbert L. Piret, Piret & Stolberg Partners, 1m Licht 12, D-47279 Duisburg, Germany
9:30 am INVITED COPPER FROM COPPER BEARING SCRAP, A MOVING TARGET: Albert W Spitz, Robert A. Spitz, Michael Saltzburg, 560 Bedford St., B-12, Abington, MA 02351 Profitably recovering copper and precious metals from copper bearing scrap is a demanding and frustrating combination of art, science and economics. With fluctuating markets, varying raw materials and increasingly stringent environmental regulations requiring process revisions, practically everything is changing. The volatile copper market constantly shifts the percentage of copper in the scrap that can be economically processed. Scrap that has value one day may incur a disposal cost the following day. Also with less copper in the scrap, more residuals, slag, fume, etc. are generated which frequently present disposal problems and infrequently generate income. The ever increasing amounts of electronic scrap add value to the copper produced by virtue of the precious metals present. Printed circuit board materials create more slag and organic off gases which must be treated. Finally, the emphasis on reducing emissions of organics and other metals, especially lead, is a continuing challenge. Stack gases, fugitive emissions and ambient air quality all demand constant surveillance.
The requirements to smelt secondary copper more economically, to process a wide range of materials with large fluctuation in size and composition and to cope with the increasingly stringent environmental constraints have put considerable pressure on existing conventional secondary copper smelters. The Top Submerged Lance (TSL) process, developed and commercialized by Ausmelt Ltd over the past 20 years, offers a low cost technology, which is particularly suitable for the treatment of copper-bearing scrap and residues, because of its low investment, use of cheap fuel and reductant, high rate of recovery of metals and low slag losses, potential use of oxygen, high flexibility with regard to feed material, applicability to high and low throughputs, absence of dioxins in the process gas, simplicity of handling of feed, process gas and slags. This presentation outlines the application of Ausmelt technology in secondary copper smelting, producing converter grade copper ready for anode furnacing, both for a new installation and for a retrofit of the smelting or converting stage of an existing smelter. The economic and environmental benefits of its application are highlighted.
10:00 am BREAK
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metallic layer into the substrate to produce a compositionally and structurally distinct surface alloy. The surface that results from these treatments often displays interesting characteristics. For example, a Grade-2 Ti sample, which pits at a potential of 1.7V, is immune to pitting up to 2V following ion beam treatment. This talk will discuss the changes in electrochemical behavior of several alloys following ion beam treatment.
ADVANCES IN COATINGS TECHNOLOGIES II: Session VI Sponsored by: MDMD Surface Modification & Coatings Technology Committee Program Organizers: C.R. Clayton, State University of New York at Stonybrook, College of Engineering and Applied Sciences, Stony Brook, NY 11794-2200; J.K. Hirvonen, US Army Materials Technology Lab., Arsenal St., Watertown, MA 02172; A.A. Srivatsa
Wednesday, PM February 12, 1997
3:00pm CORROSION INHIBITION MECHANISMS IN EPOXY COATED ALUMINUM: R. D. Granata, RC. MacQueen RR. Miron, M.M. Madani Zettlemoyer, Center for Surface Studies, Lehigh University, 7, Asa Drive, Bethlehem, PA 18015
Room: 315B Location: Orlando Convention Center
Corrosion inhibition mechanisms in model systems were evaluated for use in barrier-type protective polymeric coatings systems. Emphasis was on complaint, low VOC coatings applications technologies such as powder coatings, UV-cured and electrocoating systems on aluminum substrates. Candidate inhibitor systems wee studied using low VOC epoxy polymer and porous polymer films on conversion coated, aluminum alloy 2024. Inhibition in these systems was observed in short exposure times. The model defect systems were studied using electrochemical impedance and positron annihilation lifetime spectroscopies. The positron lifetime measurements determined free volume cavity sizes and concentrations through which corrosion-active species diffuse. Electrochemically active and inactive (positron accessible) regions within the polymer matrix were monitored versus water saturation. Corrosion inhibitors modified the polymer matrix barrier properties in regions adjacent to the filler particles. Inhibition processes will be discussed relative to known mechanisms.
Session Chairperson:TBA
1:30pm THE USE OF ION BEAM SURFACE MODIFICATION TECHNIQUES FOR CORROSION PROTECTION: P.M. Natishan, E. McCafferty, GK Hubler, B.D. Sartwell. Naval Research Laboratory, Washington, DC 20375 Ion beam alloying techniques overcome many of the problems associated with conventional alloying and provide a means to produce new and unique corrosion resistant alloys. These techniques can be used to tailor metal surfaces to enhance the corrosion resistance of the surface without affecting the bulk properties of the metal. In addition, novel metastable phases unattainable by conventional alloying can be produced, and scarce or critical materials can be conserved since only the surface of the metal is alloyed. This paper will discuss advances in and issues related to various ion beam alloying techniques including ion implantation, ion beam mixing and ion beam assisted deposition as related to their application to corrosion protection.
3:20 pm BREAK 3:40pm CYCLIC OXIDATION BEHAVIOR OF AN ALUMINIDE COATING FORMED ON DE SULFURIZED Ni-BASED SUPERALLOYS BY CHEMICAL VAPOR DEPOSITION: Y. Zhang!, w.Y. Lee2, K.M. Cooley2, LG. Wright2, P.K. Liaw!; !Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996; 2Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
2:05pm CORROSION RESISTANT ALLOYS AND COATINGS PRODUCED BY PHYSICAL VAPOR DEPOSITION: Barbara Shaw, Elzbieta Sikora, Tim Miller, Department of Engineering Science and Mechanics, Penn State University, University Park, PA 16802 Evaporation techniques, such as PVD and CVD are increasing in popularity as methods for tailoring surface properties for specific engineering applications. One of the attributes of PVD is the ease with which graded, layered and nonequilibrium coatings and alloys can be produced. Not surprisingly, defects, coating morphology and deposit composition strongly influence deposit properties such as strength and corrosion resistance. As an example of how passivity enhancing species influence corrosion resistance, the addition of 8 at% Mo to Al (via electron beam PVD) was found to increase the pitting potential 600mV over that of pure AI. Similar enhancements have been observed with AI-Ta alloys. In addition to the constant composition deposits, graded and layered coatings can also be used to improve corrosion resistance and mechanical properties. In this presentation, the results of an ongoing investigation of nonequilibrium Al and Mg deposits ( both constant and graded composition deposits) produced via electron beam PVD will be presented and discussed.
The cyclic oxidation behavior of Ni-based superalloys can be significantly improved by lowering the level of sulfur impurities in the alloys to below - 1 ppm. This presentation addresses the feasibility of preparing a low-sulfur bond coat, which would be compatible with desulfurized single-crystal superalloys and therefore could be attractive for possible use in advanced thermal barrier coating applications. Rene N5 substrates containing - 3 ppm and - 0.4 ppm sulfur were aluminized using a chemical vapor deposition technique. The level of sulfur incorporated into the aluminide coating was measured as a function of coating thickness by glow discharge mass spectroscopy. The effects of the sulfur content on the cyclic oxidation behavior of the aluminized substrates and the morphological stability at the scale-coating interface were studied and compared. 4:00pm AN XPS STUDY OF THE ROLE OF NITROGEN IN OXYANION FORMATION DURING AQUEOUS CORROSION OF MOLYBDENUM AND CHROMIUM NITRIDE COATINGS: G. Halada, C. Clayton, Department of Materials Science and Engineering, State University of New York at Stony Brook, NY 11794-2275; 1. Beatty, 1. D. Demaree, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005-5069
2:40pm THE ELECTROCHEMICAL BEHAVIOR OF METAL SURFACES SUBJECTED TO PULSED ION BEAM SURFACE TREATMENT: N.R. Sorensen l , RG. Buchheit!, K.S. Grabowski2, T.R Renk!, M.O.Thompson3; !Sandia National Laboratories, P.O. Box 5800 Albuquerque, NM 87185; 2Naval Research laboratory, Code 6670, Washington, DC 20375; 3Department of Materials Sciences, Cornell University, Ithaca, NY 14853
A dual electrode electrochemical approach, in combination with variable angle X -ray Photoelectron Spectroscopy, was used to determine the role of nitrogen in the generation of oxyanionic species, MoOl and CrO.'", from MoN and CrN coatings. During simultaneous anodic polarization of a coupling of Fe and either pure Mo and Cr or their respective nitrides in deaerated O.IM HCl, the presence of nitrogen was found to enhance the formation of molybdate and chromate oxyanions. These oxyanions deposited back onto the nitride surfaces as insoluble salts formed with cations released from the iron electrode. The increased formation of oxyanions is postulated to be the result of deprotonation of electrolyte in contact with the nitride coating and a subse-
Pulsed high energy ion beams have been used to thermally treat metal surfaces to alter their electrochemical response. Two general processing regimens have been explored: 1) rapid melt and resolidification (RMR) and 2) ion beam mixing (IBM). RMR uses the pulsed ion beam to melt and in some cases ablate the top most several microns of the surface. Subsequent solidification is sufficiently fast (> 106K/s) for nonequilibrium structures and compositions to be attained. IBM uses the ion beam to mix a previously applied
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quent shift in pH to higher values. In addition to acting as a kinetic barrier, the oxyanionic species act as an electrostatic barrier to the ingress of the CI· anions which cause pitting.
companied by the formation of transient liquid phases. These factors can reduce the required processing parameters (time, temperature and pressure) needed to produce dense products by reactive synthesis techniques compared to conventional powder metallurgical approaches. This paper characterizes the reactions that occur and resultant microstructures of TiAI based composites fabricated from ternary mixtures of elemental Ti, Al and B or Si powders. Mixtures of the elemental powders were prepared corresponding to TiAI reinforced with 0, 10 25, 60 and 100 vol. pct. Ti sS4 or TiB 2• The powders were consolidated by reactive hot-pressing (at 1000"C and 20 MPa for I hr). It was found that the composites produced from Ti, Al and Si powders were dense, and the elemental powders transformed to the target phases of TiAI and TisSi 3. Whereas, composites produced from the Ti, Al and B powders were porous and inhomogeneous, that is several aluminide (TiAI, Ti3AI and TiAI3) and boride phases (TiB 2, AIB ,2 , TiB) formed during hot-pressing. The different behavior observed by the two ternary systems can be attributed to both reaction sequence and phase diagram considerations. First, Differential Thermal Analysis (DTA) revealed that an endothermic reaction associated with the formation of AI-Si eutectic occurs prior to the initiation of an SHS reaction within the mixtures ofTi, Al and Si powders. No such pre-reaction melting occurred within the mixtures of Ti, AI, and B powders. Thus, the "extra" transient liquid phase that formed during the reaction between Ti, Al and Si systems enhances diffusion (hence homogenization) and densification within this system during reaction processing. Also, an examination of phase diagrams reveals that there exists no AI-Si compounds to compete with the formation of titanium-aluminide and titanium-silicides during reactions between Ti, Al and Si powders. However, there are several aluminum-boride phases that can compete with the formation of titanium-aluminide and titanium-boride during reactions between Ti, Al and B powders. The implications of this study is that TiAI-based composites can be designed for densification during reactive processing.
4:20pm A STUDY OF THE PASSIVATION MECHANISM IN IDGHLY CORROSION RESISTANT "STAINLESS STEEL" ALLOY COATINGS FORMED USING THE JVDTM PROCESS: Clive R. Clayton, M.E. Monserrat, G .P. Halada, Dept. of Materials Science and Engineering, SUNY at Stony Brook, NY 11794; Jamie Di, Takashi Tamagawa, Arun R. Srivatsa, Bret L. Halpern, Jet Process Corporation, 24 Science Park, New Haven, CT 06511 Recently we reported the formation of highly corrosion resistant "stainless steel" based alloy coatings formed using the JVDTM process. In this paper, a detailed study aimed at obtaining a fundamental understanding of the passivation mechanisms operating in these alloy coatings is reported. Passivation behavior of the coatings was determined by electrochemical polarization in 4.0M and 0.1 M solutions respectively. The surface chemistry of the coatings was studied using XPS and correlated to the observed passivation behavior.
ADVANCES IN SYNTHESIS AND PROCESSING OF METAL CERAMIC MATRIX COMPOSITES IV: Sponsored by: MSD Materials, SyntheSiS & Processing Committee and Jt. SMDI MSD Composite Materials Committee Program Organizers: L.L. Shaw, Dept. of Metallurgy and Materials Engineering, University of Connecticut, Storrs, CT 06269; E.J. Lavemia, Dept. of Mechanical and Aerospace Engineering, UniverSity of California -Irvine, Irvine, CA 92717; S. Krishnamurthy, UES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432-1894; E.S. Chen, U.S. Army Research Office, 4300 S. Miami Blvd., Research Triangle Park, NC27709 Wednesday, PM February 12, 1997
2:55pm REACTIVE SYNTHESIS OF NiAI-Nb COMPOSITE FROM ELEMENTAL POWDERS: L. Farber, A. Lawley, I. Gotman, Department of Materials Engineering, Drexel University, Philadelphia, PA 19104; I. Gotman, E. Y. Gutmanas, Department of Materials Engineering, Technion, Haifa 32000, Israel
Room: 340B Location: Orlando Convention Center
Session Chairpersons: Dr. S. Krishnamurthy, UES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432; Prof. Carlos G. Levi, Materials Department, University of California, Santa Barbara, CA 93106
A NiAI matrix composite reinforced with Nb particles was synthesized in the solid state from blends of ultrafine elemental Ni, Al and Nb powders. The fabrication method involved consolidation of elemental powder blends to full density followed by heat treatment. The maximum processing temperature did not exceed 800°C. Kinetics and the sequence of phases formation during synthesis were investigated. For Ni-AI-Nb blends, consumption of Al with the formation of Ni-AI intermetallic phases only was detected in the temperature range 425°C-550°C. Subsequent heat treatment at 800°C resulted in rapid completion of the synthesis reaction with the formation of the NiAI matrix. No reaction occurred between Nb particles and the matrix during synthesis. The phase stability of the composite in the 800°C-II OO°C temperature range was investigated. Mechanical properties of the synthesized material are discussed in the context of resulting microstructure.
2:00 pm INVITED SYNTHESIS AND PROCESSING OF CERAMICS, INTERMETALLICS, AND COMPOSITES BY FIELD-ACTIVATED COMBUSTION SYNTHESIS: Zuhair A. Munir, Division of Materials Science & Engineering, Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616-5294 Abstract not available. 2:30pm SYNTHESIS OF IN-SITU TiAI-BASED COMPOSITES FROM ELEMENTAL POWDERS: D.E. Alman, J.A. Hawk, U.S. Department of Energy, Albany Research Center, Albany, Oregon 97321
3:20pm FeAI-TiC AND FeAI-WC COMPOSITES - MICROSTRUCTURE AND MECHANICAL PROPERTIES: R. Subramanian" J.H. Schneibel, Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6115
Alloys and composites based on the intermetallic compound TiAI are emerging as an important class of light-weight, high-temperature structural materials. Recently, it has been recognized that these alloys have applications in industries, such as the automotive industry, where cost is frequently a major concern in materials selection. However, for these alloys to be used in this type of application, new low cost methods for high volume component fabrication are required. One potential fabrication approach is reactive synthesis (also termed combustion synthesis). This technique involves initiating an selfpropagating, high-temperature synthesis (SHS) reaction within an intimate mixture of elemental powders. This process has been used to fabricate intermetallics, ceramics and in-situ composites in the form of powders and dense monoliths. SHS reactions tend to initiate at low homologous temperatures of the forming compound (for aluminides near or at the melting point of AI, 660T), and tend to go to completion in a short period of time (i.e., a few seconds). For some compounds, particularly aluminides, the reaction is ac-
For applications of TiC- and WC-based cermets in corrosive environments, a potential binder material is an intermetallic, iron aluminide. In this investigation, it is shown that iron aluminide (Fe-40 at %AI) bonded TiC and WC composites can be processed to almost full density (> 99 %) with carbide volume fractions ranging from 0.3 to 0.85 by conventional liquid phase sintering and pressureless melt infiltration techniques. The melt infiltration process was successful in the fabrication of composites with carbide volume fractions greater than 0.7 and important aspects of this technique will be dis· cussed. Mechanical property data such as bend strength, hardness and fracture toughness will be presented and interpreted in terms of the composite microstructures. For FeAI-WC composites containing 60 vol. % WC, room temperature three-point bend strengths and fracture toughness values reached 1680 MPa and 20 MPam '12 , respectively. Consistent with the high fracture toughnesses, the fracture surfaces showed evidence of ductile deformation of
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the FeAl binder. Research sponsored by the Laboratory Directed Research and Development Program of the Oak Ridge National Laboratory, and by the Division of Materials Sciences, U.S. Department of Energy, under Contract No. DE-ACOS-960R22464 with Lockheed Martin Energy Research Corporation, Inc. This research was also supported in part by an appointment to the ORNL Post-Doctoral Research Associates Program administered jointly by the ORISE and ORNL.
5:10pm FIBER FRAGMENTATION DURING PROCESSING OF METALLIC MATRIX COMPOSITES: Nicole M. Gorey, Donald A. Koss, John R. Hellmann, Department of Materials Science and Engineering, Penn State University, University Park, PA 16802 Fiber fragmentation can be a serious problem during the processing of metallic matrix composites. This research focuses on the fracture of continuous sapphire fibers during composite consolidation. During the latter stages of consolidation, matrix flow along the fibers may cause fiber fracture even in the absence of fiber bending. Fiber fragmentation by this mechanism has been examined using a theoretical analysis which predicts the extent of composite flow as a function of processing parameters and the resulting fiber fragmentation lengths. In order to validate the analysis, a model composite system, which consisted of a tin matrix and degraded sapphire fibers, has been "hot pressed" at room temperature to simulate elevated temperature consolidation of sapphire-reinforced Ni-base composites. A comparison of observed and predicted fiber fragmentation lengths indicate good agreement. The analysis can readily be applied to predicting conditions that should be used to prevent extension-induced fiber fracture during high temperature consolidation of structural composites. The research was supported by NASA.
3:45 pm BREAK 3:55 pm DEOXYGEN IN SILICIDE FORMATION: Chi-Fung Lo, Darryl Draper, Materials Research Corporation, Orangeburg, NY 10962 A preliminary study on the deoxygen behavior of tungsten-, molybdenumand tantalum-silicide formations using powder technique was performed. During the synthesis under vacuum, the transformation of amorphous to crystalline silicon and the formation of silicides were monitored by X-ray diffraction. The oxygen content in the materials at various phase-transformation stages was measured. The results indicated that, independent of the synthesized metals, no significant change in the oxygen content was found until the formation of metal-disilicides. Via the formation of disilicides, the oxygen decreased from 1000-3000 ppm to less than SOO ppm. In this study, the exothermic behavior of silicon phase transformation and the silicide formations was also investigated.
ALUMINA & BAUXITE TECHNOLOGY IV Sponsored by: LMD Aluminum Committee Program Organizer: F. S. Williams, Alcoa Alumina & Chemicals L.L.C., Point Comfort, TX 77978·0101
4:20pm TITANIUMIl'ITANIUM CARBIDE COMPOSITE FORMATION BY GAS·SOLID IN·SITU REACTION: Yong Jin Kim, Hyungsik Chung, Department of Materials Processing, Korea Institute of Machinery and Materials, 66 Sangnam Dong, Changwon, Kyungnam 641-010, S-Korea; Suk-Joong L. Kang, Department of Materials Science and Engineering, KoreaAdvanced Institute of Science and Technology, 373-1 Kusong-Dong, Yusong-Gu, Taejon 30S-701, S-Korea
Wednesday, PM February 12,1997
Room: 230D Location: Orlando Convention Center
Session Chairman: J. L. Anjier, Kaiser Aluminum and Chemical Corp., Box 337, Gramercy, LA 70052
Sponge titanium powder was die compacted and reacted with carbonaceous (CH.) gas at the temperature range of 700-1,OOO°C. Layered TiC film was formed uniformly on the surface of the powders in the green compact. The thickness of the TiC layer varied with the reaction temperature and time. The reacted compacts were sintered in a vacuum up to 14S0°C. During the sintering, the TiC layer in the power surface was broken into small fragments and the fragment changed gradually into round shaped particles with increasing the sintering temperature. The relative sintered density over 94% was obtained at the sintering temperature of 13S0°C for 2hrs. Ti/fiC composite containing up to SO vlo of TiC was successfully made by the in-situ reaction and sintering. The volume of TiC in the sintered body mainly depends on the reaction temperature, time and Ti powder size. But the gas flow rate during the reaction affected little to TiC volume in the sintered composite.
2:00pm FCB RETROFITTING OF ALUMINA ROTARY KILN: WHEN DRAS· TIC FUEL SAVING MEETS INCREASED CAPACITY: Vincent Giroud, Andre' Pinoncely, FCB- subsidiary of the Fives Lille Group, Mineral Processing and Carbon Plant Division, 32, rue fleury Neuvesel, BP 24-69702 Givors Cedex. Alumina calcination using rotary kilns is an expensive operation. In 1972 an innovative concept of kiln retrofitting was introduced which greatly enhanced the overall thermal efficiency while preserving most of the existing capital equipment. As a result, nine kilns have been retrofitted over the last eighteen years, gradually highlighting the wide range of possible arrangements and the relevant strong process and mechanical reliability. This paper draws up the main features of these retrofits, namely the substantial energy saving and the correlative increased capacity. Long-term observations also demonstrated that alumina quality remains as consistent as previously with no significant impact on the calcined alumina size distribution. The latest retrofitting pattern including new cyclones and ducting arrangements are presented yielding a fresh look for a still useful technology.
4:45pm PROCESS·STRUCTURE RELATIONSHIPS FOR TAPE CASTING OF CONTINUOUS FIBER·REINFORCED MMC'S: Shin Yu and Dana M. Elzey, Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA 22903 The tape casting process offers a potentially cost-effective manufacturing route for continuos fiber-reinforced metal matrix composites. However, the ultimate performance is limited by the presence of microstructural defects, which evolve to an extent which depends sensitively on the constituent materials and processing conditions used. Results of an experimental study are reported in which the evolution of several important microstructural defects have been investigated for various processing conditions. These observations have been used as a basis for the development of predictive process-structure models for the tape casting of MMC's. The models may be used to explore processibility and cost issues for hypothetical matrix/fiber composite systems and processing conditions.
2:25 pm ALUMINA CALCINATION WITH THE MULTI·PURPOSE CAL· CINER: Jorgen Ilkjaer, Lars Bastue and Benny E. Raahauge, FLS Minerals NS, Alumina & Bauxite Technology, Vigerslev Alle 77, DK-2S00 Valby Copenhagen, Denmark The Gas Suspension Calciner (GSC) and the rotary kiln are both well proven technologies for calcination of alumina. The GSC is mainly used for production of smelter grade alumina and the rotary kiln for special grade alumina. A multi-purpose calciner which combines these two technologies has been designed, constructed and commissioned in the summer of 1996. By combining these two calcination technologies it is possible to produce a wide range of alumina qualities only by changing a few parameters in the operation using a Fuzzy II Logic Control System and a CemScanner.
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nificantly lower than that for the sintering method and approaches the Bayer technology indices.
2:50pm PREDICTING MOISTURE CONTENT ON ALUMINAS FROM MEASUREMENT OF WATER ISOTHERMS: A. R. Gillespie, Comalco Research Centre, Thomastown, Vic., Australia; M. M. Hyland, 1. B. Metson, University of Auckland, Auckland, New Zealand
4:50pm FEATURES OF ALUMINA PRODUCTION TECHNOLOGY FROM ALUMINOSILICATE RAW MATERIAL WITH POTASSIUM'S HIGH CONTAIN: V.A. Lipin, N. N. Tikhonov Russian National Aluminium-Magnesium Institute (VAM!), 88, Sredny pr., St. Petersburg, 199026, Russia
Water adsorption isotherms on alumina can play an important predictive role in aluminium smelting since the level of moisture on the alumina influences its handling, feeding and dissolution characteristics, along with the potential for generation of emissions. Measurements of adsorption isotherms of water on smelter aluminas indicate moisture pick-up and loss is rapid, with initial rates of change in adsorbed water in excess of 0.1 wt% per minute, meaning the ex-situ measurements are not likely to be accurate. Adsorption and desorption curves, to water pressures in excess of 20 Torr, indicate near complete reversibility. The discrepancy is attributed to the irreversible formation of Al(OH)3' Analysis of the shape of the curves suggest several distinct mechanistic regimes within the adsorption curve.
Aluminosilicate raw materials have large differences in chemical and mineralogical structure, particularly in the relationship between sodium and potassium. Large deposits of raw materials with high portions of potassium alkalis are known and have been studied for the purpose of the industrial processing by the sintering and hydrometallurgical methods. Technological features of the processing of the high-potassium aluminosilicate raw materials utilize for the most part the processes of sintering, leaching and desilication. The optimum molecular ratios of the main components before sintering were found in each case. Distribution of alkaline metals between liquid and solid phases during leaching and desilicating was determined. Utilizing experimental data, equations have been developed predicting the dependence of desilicating indexes from chemical composition of processing ores. These relationships aid in choosing the most effective conditions for research of promising raw materials.
3:15 pm BREAK 3:35pm ALUMINA QUALITY TESTING PROCEDURE: R. G. Haverkamp, B. J. Welch, Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand; S. Bouvet, Pechinay Centre de Recherches de Voreppe, Voreppe, France; P. Homsi, Aluminium Pechiney, St. Jean de Maurienne, France
ALUMINIUM REDUCTION TECHNOLOGY VI: CELL STUDIES
A laboratory method for comparing characteristics of alumina dissolution in molten cryolite is described. The method uses fast modified linear sweep voltarnmetry combined with thermal analysis to determine the dissolution rate of alumina in a molten cryolite electrolyte. Practical aspects of the method are discussed. Emphasis is on consistent alumina feeding and stirring and a careful monitoring of the alumina moisture content.
Sponsored by: LMD Aluminum Committee Program Organizer: Harald A. 0ye, Institute of Inorganic Chemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway Wednesday, PM February 12, 1997
4:00pm SINTERING AND HEAT CONDUCTIVITY OF ALUMINA: Terje 0stvold, 0yvind T. Gustavsen, Heidi Mediaas, Institute of Inorganic Chemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway; Torstein Haarberg, Hydro Aluminium, Technology Centre Ardal, N-5870 0vre Ardal, Norway
Room: 230A Location: Orlando Convention Center
Session Chairperson: Elmar Sturm, Hamburger Aluminiumwerk GmbH, P.O. Box 950165, 0-21129 Hamburg, Germany
2:00pm ON THE BATH FLOW, ALUMINA DISTRIBUTION AND ANODE GAS RELEASE IN ALUMINIUM CELLS: Ove Kobbeltvedt, Department of Electrochemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway; Bjlilrn P. Moxnes, Hydro Aluminium. Technology Centre Ardal, N-5870 0vre Ardal, Norway
Heat conductivities are measured in alumina powders treated with 0-7 wt% NaAlF4 at varying temperatures up to 900°C. The y~a transition of alumina, triggered by addition of NaAlF4 , was found to be essential for the observed increase in heat conductivity. A maximum heat conductivity was measured at 3.5 wt% NaAlF4 for aluminas heated to 700°C and at -2 wt% NaAlF4 for heat treatments at 800 and 900°C. The heat conductivity was also measured versus temperature after the samples had been sintered. A decrease in heat conductivity with increasing sample temperature was observed. A mathematical model for the thermal conductivity of porous materials was applied and tested against the measured data, confirming the importance of sintering with respect to thermal conductivity. The relevance of the present findings concerning heat balance of industrial smelting cells is discussed.
The bath flow was studied in prebake cells. The measurements were performed by recording the drop in bath temperature subsequent to alumina feeding as well as by measuring the wear of quartz rods immersed in the bath. The horizontal flow rate varied between 3 and 20 cm/s. It was found that the horizontal bath flow and consequently the alumina distribution pattern are determined mainly by a combined effect of the magnetic fields and the width of the channels above the working surface of the anodes. The quantity of anode gas which was drained into the centre channel was measured at different locations in a cell. The result showed that the distribution of the anode gas in the bath is strongly associated with the magnetic fields.
4:25pm RECOVERING ALUMINA, SILICA AND BYPRODUCTS FROM COAL ASH THROUGH THE USE OF PROCESS FOR SILICON PREEXTRACTION: Victor L. Rayvnan, 933 Regal Road, Encinitas, CA 92024; SolomonA. Shcherban, 110 Bennet Avenue, # 3H, New York, N.Y. 10033
2:25pm ALUMINA DISTRIBUTION IN POINT-FED HALL-HEROULT CELLS: K. T¢rklep. K. Kalgraf, T. Nordblil. Elkem a1s Research, P.O. Box 8040 Vaagsbygd, N-4602 Kristiansand, Norway
The large volume of coal combustion wastes cause a problem of great concern in environmental protection. Only about a quarter of these wastes are being used today, generally for construction materials production. At the same time, many million tons of aluminum and silicon contained in coal ash are lost in landfills annually. Of all the large number of processes for recovering alumina and byproducts from aluminum and silicon-bearing wastes only one, the lime-soda sintering process, has been commercially used on nepheline residue and red mud. To approach ash composition similar to these abovementioned wastes, a process for silicon pre-extraction has been developed and pilot plant tested. The method reduces the material stream trough the sintering kiln in half and produces high pure silica alongside the alumina and calcium silicate. The heat consumption for the new process is estimated sig-
We describe the alumina concentration distribution in point-fed Hall cells in terms of finite physical elements. The need arose in the development of the New Slilderberg technology at Elkem Aluminium ANS, but the technique is applied to prebake pots as well. The concentration at any point in the bath is computed from the dynamical equilibrium between consumption and transport of alumina (directly or indirectly dissolved) and presented as contour plots. Necessary inputs are the velocity field in the bath and the turbulent diffusivity, either measured or calculated. We prefer to measure both by injecting a small amount of a molten radioactive tracer and follow the distribu-
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tion of this tracer in situ. Measured velocity fields have been found to vary significantly between presumed identical pots and over time. This is mainly ascribed to convective coupling with the metal, where the boundary conditions and hence the driving forces may well differ between pots and change with time. Contrary to extant models, our approach permits experimental verification through comparison of predicted and measured oxide concentrations at various locations in the pot under investigation. 2:50pm METAL PAD WAVE ANALYSIS USING FAST ANODE LOWERING METHOD: H. Q. Tang and N. Urata, Kaiser Aluminum & Chemical Corporation, Center for Technology, P.O. Box 877, Pleasanton, CA 94566 In order to study the metal pad wave in aluminum reduction cells, the two step fast anode lowering method was developed and applied to the operating cells. The metal pad waves after anode lowering were measured and analyzed. The period and shapes of the metal pad waves were determined by performing Fourier transform analysis of the measured data. The MHD wave. equations were solved for cells of different magnetic fields to simulate the metal pad waves caused by this fast anode lowering. The period and shapes of the predicted steady state waves were in good agreement with the measured waves, although the measured wave had more transient nature. The cell stability was evaluated based on the metal pad wave analysis. 3:15 pm BREAK 3:35pm IMPURITY TRANSPORT MECHANISMS IN ALUMINIUM REDUCTION CELLS: M. Webster, Xiaoling Liu, Coma1co Research Centre, Thomastown, Victoria, Australia; J. Metson, Department of Chemistry, University of Auckland, New Zealand The purity of aluminum from pre-bake reduction cells is affected by the quantity of impurities introduced with the raw materials and the fraction of these reporting to the metal. The transport of Ti, V, Ga, Si, Fe and Ni from the reduction cell to the duct emissions stream has been studied for point feeder and bar break cells. Samples of material from bath, cell cover and duct emissions have been examined and analysed for a range of impurities. For elements with volatile, bath generated fluoride compounds, the impurity content of the cover and duct samples is proportional to the carbon content. Carbon grains with thick (> 10 micron) impurity rich surface coatings are observed in both the loose cover samples and particles from bath skimmings. Thus a possible mechanism for the transport of these impurities may be postulated. 4:00pm PSEUDO RESISTANCE CURVES FOR ALUMINIUM CELL CONTROL - ALUMINA DISSOLUTION AND CELL DYNAMICS: Halvor Kvande, Hydro Aluminium a.s, P.O. Box 80, N-1321 Stabekk, Norway; Bjprn P. Moxnes, Jprn Skaar, Per A. Solli, Hydro Aluminium a.s, Technology Centre Ardal, P.O. Box 303, N-5870 0vre Ardal, NorwayThe pseudo resistance was measured as a function of the alumina concentration in the bath in five different types of cells. The pseudo resistance showed a minimum value of 5.0 to 5.5 mass% AI 20" when the bath samples were analyzed by the LECO method. To the left of the minimum point on the curve the slope increased gradually until the anode effect occurred at 1.6 to 2.2 mass% AI 20" while a nearly linear curve was found in some of the measurements. The difference in pseudo resistance determined just prior to the anode effect and at the minimum point, corresponded to a voltage difference between 100 and 300 mY. Immediately after the alumina feeding rate was reduced from overfeeding to underfeeding, a so-called "hysteresis effect" could be observed. This was characterized by a sudden decrease in cell voltage of about 100mV in less than 30 minutes, in spite of practically constant bath composition and temperature in this time period. This effect may be caused by dissolution of alumina sludge in the bath phase above the metal pad, accumulated during the long overfeeding period of several hours, needed to reach concentrations to the right of the minimum point on the curve.
4:25pm THE INFLUENCE OF SODIUM ON THE ALUMINIUM REDUCTION CELLS: Mohamed O. Ibrahiem, Mohamed M. Ali, R&D Department, Aluminium Company of Egypt, Naga Hamadi, Egypt Sodium always present in Hall-Heroult cells, has a decisive influence on cell performance and pot failure. In this paper, sodium was studied from three points of view. The fust is the sodium mass balance. Alumina and cryolite are the major sources of sodium inputs to the electrolytic process, where 56.8 % and 40.7 % of sodium come from them, respectively. The second point is the sodium content in aluminium metal. Measured sodium content in aluminium of 203 kA prebaked cells is lower than that of 155 kA Spderberg due to lower bath ratio, higher excess aluminium fluoride, and higher magnetic fields. The third point is the study of sodium concentrations in failed carbon cathodes at different ages. This concentration at 3194 days is 8.5 %, 7 %, and 1 % higher than that at 40,60, and 1369 days, respectively. 4:50pm STUDY ON CATHODIC PROCESS OF Na+ IN THREE-LAYER ELECTROLYTIC REFINING OF ALUMINIUM: Li Guohua, Li Dianfeng, Zhao Xiangguo, Wang Qingna, Department of Nonferrous Metallurgy, Northeastern University, Shenyang, 110006, China The Current-Voltage Method is adopted to study the cathodic process of Na+ in three-layer electrolytic refining of aluminium. The electrolyte studied is NaP-AIF3-BaCl 2-NaCI molten system, whose composition is: NaP/AIF3 moleratio is 1.5-3.0, adding amount of NaCI is 0-8%, BaClz content is 60%. It is demonstrated that Na+ is not able to deposit on the aluminium cathode at the temperature range of 740-800°C while the cathodic current density is 0.4-0.8 Alcm2• This conclusion provides an important basis for modifying the electrolyte in three-layer electrolytic refining of aluminium.
APPLICATIONS OF SENSORS AND MODELING TO MATERIALS PROCESSING· VI Sponsored by: Jt. EPDIMDMD Synthesis, Control, and Analysis in Materials Processing Committee and EPD Process Fundamentals Committee Program Organizers: S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; R.G. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487; J.C. Malas, Wright-Patterson AFB, OH 45433-6533; L.L. Shaw, Dept. of Metallurgy &Materials Science, Univ. of Connecticut, Storrs, CT 06269-3136; R. Abbaschian, P.O. Box 116400, 132 Rhines Hall, Univ. of Florida, Gainesville, FL 32611-6400 Wednesday, PM February 12, 1997
Room: 232A Location: Orlando Convention Center
Session Chairs: L.L. Shaw, Dept. of Metallurgy & Materials Science, Univ. of Connecticut, Storrs, CT 06269-3136; R. Abbaschian, P.O. Box 116400, 132 Rhines Hall, Univ. of Florida, Gainesville, FL 32611-6400
2:00pm SPECTROSCOPIC METHODS FOR CONTROL OF THIN FILM GROWTH: A.G. Jackson, SJ.P. Laube, 1. Jones, TMC, Inc., Materials Directorate, Wright Laboratory, WPAFB, OH 45433 Control of thin films during the growth process is dependent on several difficult-to-monitor parameters, including flux of film material, pressure, substrate temperature, composition, and thickness. One means for easing this difficulty is to take advantage of emission spectra associated with the process and the film. For pulsed laser deposition (PLD) the ion cloud generated by the laser has characteristic emission spectra that can be used to control the deposition. Raman spectroscopy affords the possibility of real-time control by sensing characteristic peaks associated with film composition and thickness. These spectroscopic methods offer a real-time alternative to process control that is very attractive because of the ability to accurately control films to achieve the engineered structures and properties sought. Examples are presented to illustrate the capabilities of these methods for this film preparation.
2:25pm RAMAN SPECTROSCOPY FOR DETERMINING YBCO THIN FILM PARAMETERS IN SITU: David P. Lubbers, Univ. of Cincinnati, Cincinnati, OH; John D. Busbee, A.G. Jackson, TMC, Inc., Materials Directorate, Wright Laboratory, WPAFB, OH 45433; Rand R. Biggers, David C. Liptak, SOCHE, Dayton, OH
3:50pm SOLID-STATE ALUMINUM SENSOR FOR USE IN MOLTEN ZINC: J. W Fergus, S. Hui, Materials Research and Education Center, 201 Ross Hall, Auburn University, AL 36849 Aluminum is an important alloying addition to the zinc used in the hot-dip galvanization of sheet steel to control the properties and appearance of the resulting coating. Optimization of the galvanization process requires control of the alloy concentration, which can be improved through the use of chemical sensors. Aluminum sensors, based on molten electrolytes, are commercially available but are not widely used because of their high cost. One approach to reducing the cost is to use a solid electrolyte, which can simplify the sensor design and, thus, reduce the cost of fabrication. In this paper, the development of an aluminum sensor based on a solid fluoride electrolyte, specifically magnesium fluoride, will be described.
This paper describes the application of Raman spectroscopy for characterizing superconducting YBCO thin film parameters. Attenuation of the substrate Raman spectrum as a function of material deposited is established. Also, a correlation between film quality and Raman spectrum is explored. The identification and discrimination of superconducting and nonsuperconducting phases of YBCO is presented. The critical temperature (Tc) of a film as a function of its oxygen content is also established using Raman peak ratios. These results provide significant implications toward the use of Raman spectroscopy for in situ monitoring and control of the PLD process. Film quality can be controlled via optimization of film oxygen content and reduction of improper YBCO phases. Film thickness can be controlled by monitoring the response of the substrate material. Also, the PLD process can be studied and modeled using this powerful observation tool.
4:15pm APPLICATIONS OF Al SENSORS IN CONTINUOUS GALVANIZING: N. Qiang, N.-Y. Tang, G.R. Adams, Cominco Ltd., Product Technology Centre, Sheridan Science and Technology Park, Mississauga, Ontario L5K IB4 Canada
2:50pm INTELLIGENT PROCESSING OF MATERIALS: AN APPLICATION TO POLYMER COMPOSITES: J.F. Maguire, M.A. Miller, Materials Development Dept., Southwest Research Institute, San Antonio, TX
Aluminum is the most important alloy addition to Zn baths for controlling the reaction kinetics between the steel substrate and molten Zn in continuous galvanizing operations. The control of effective bath Al content is particularly critical for galvannealing where a high bath Al content may lead to incomplete alloying during postannealing, and a low bath Al content may result in other problems, such as an excessive bottom dross accumulation and difficulties in coating thickness control. The amount of Al in a galvanized coating has a strong influence on coating properties and the overall product quality. Yet, due to the complexity of the Zn-Fe-Al ternary system, the measurement and accurate of Al sensors has made the real-time measurements of bath Al contents possible. To facilitate their application, a computer interface and a palm-size data logger have been developed. Plant applications indicated that the sensor possessed sufficient accuracy for process monitoring and control. Potential benefits of Al sensor applications include improvements in process control and product quality, reductions in product transition periods for dual product lines, and a reduction in the overall production cost.
The process control of polymeric components is a difficult problem in modern process control. These materials consist of a chemically reactive resin which impregnates a reinforcing fiber. The resin is subject to aging phenomena and is found that frequent adjustments of the process are needed in order to assure quality of the product. In order to increase quality and reduce manufacturing delays the manufacturing process was analyzed from a physicochemical standpoint and intelligent control system was developed and implemented. It was determined that integration of a novel advanced sensor technology based on in situ Raman and Rayleigh light scattering with a state-ofthe-art chemical kinetic and polymer transport model of the polymerization process would provide real (sensor) and virtual (model) information on which material process control decisions could be based. The sensor information provides chemical and physical analytic data in real-time. This data is analyzed and compared with the predictions of the model and adaptive control decisions are implemented. The control system was interfaced with customized processing hardware via a programmable logic controller (PLC) employing conventional ladder logic. The system has been tested extensively and has been able to process adaptively advanced composite components fabricated from quartz reinforced polyimides. Finally, the process logic control algorithms, which rely on the physical and chemical state of the material based on sensor information, are generic to any chemically reactive resin with minor modifications to initial parameter values.
AQUEOUS PROCESSING TMS General Abstract Session Wednesday, PM February 12, 1997
Room: 240B Location: Orlando Convention Center
Session Chairperson: George Demopoulos, Dept. of Mining and Metallurgical Engineering, McGill University, Montreal, Quebec, Canada H3A 2A7
3:15 pm BREAK 3:25pm ALUMINUM SENSOR FOR STEEL GALVANIZING BATHS: R.Sridhar, J.M. Toguri, Dept. of Metallurgy and Materials Science, University of Toronto, Toronto, Ontario M4S 3E4, Canada
2:00pm A PYRIDINE-BASED TRIDENTATE CHELATING SOLVENT EXTRACTION SYSTEM FOR SELECTIVE EXTRACTION OF NICKEL AND COBALT: Batric Pesic 1, and Taili Zhou 2, lUniversity of Idaho, College of Mines-McClure Hall, Moscow, ID 83843; 2The Shepherd Chemical Co., 4900 Beech St., Cincinnati, OH 45212
The aluminum content of zinc galvanizing baths is an important parameter for producing good quality steel sheets for automotive applications. The present method of bath sampling and chemical analysis measures the total aluminum content of the bath which includes dissolved aluminum and aluminum in entrained dross. Also, this method does not provide quick analysis for process control purposes. It has been reported that the measurement of dissolved aluminum is essential to obtain a good zinc coating on steel. Laboratory experiments have shown that an electrochemical cell consisting of an aluminum electrode, an ionic fused salt and an electrode like Mo (inert to Zn) dipping in the zinc bath has good potential for quick dissolved aluminum measurements. Such a sensor can be ready adopted for process control. These results will be discussed.
A novel pyridine-based tridentate chelating extractant, 2,6bis-[5-nnonylpyrazo-3-yll pyridine (BNPP), has been developed and characterized. The solvent extraction ofNi and Co by a mixed system ofBNPP and dinonyl naphthalene sulfonic acid (DNNSA) was studied as a function of pH, diluent, temperature, and DNNSA concentration. Stripping of Ni and Co was examined as a function of HCl and H2S04 concentration. The novel system can extract Ni and/or Co selectively against Fe, Mn, Ca, Mg, and Al from acidic sulfate solutions at a pH as low as 0.5. Separation ofNi and Co can be achieved either during loading, or during stripping stages of solvent extraction. The extractant system is stable and can be regenerated with acid. The novel solvent extraction system was also tested on the real solutions produced by leaching of cobalt bearing concentrates, (1) cobaltite concentrate from Blackbird Mine, Idaho, and (2) siegenite concentrate from Lead-Belt, Missouri. A
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flowsheet for recovery of cobalt and nickel has been proposed based on these studies. The review of the current status of solvent extractants for cobalt and nickel will be given by comparative presentation with our novel extractantion system.
ing on crystallization of hematite that is currently underway at McGill University will be outlined. 3:20 pm BREAK
2:20pm DIELECTRIC STUDIES ON PbS-KEX-K2Cr20 7 SYSTEM UNDER FLOTATION CONDITIONS: Antonio Huerta, Juan Genesca, Armando Solis, Dept. de Ingenieria Metalurgica, Fac.de Qulmica, Universidad Nacional Autonoma de Mexico. Cd. Universitaria, CP.04S1O, Mexico
3:30pm INFLUENCE OF HYDROLYSIS - PRECIPITATION MEDIUM ON THE NATURE OF ALUMINIUM HYDROXIDE GELS AND Al,O, POWDER CHARACTERISTICS: M. Thiruchitrambalam, V.R. Palkar*, V. Gopinathan. P. Ramakrishnan, M.S. Multani*. Dept. of Metallurgical Engineering and Materials Science, LI.T, Bombay - 76; *Tata Institute of Fundamental Research, Bombay -5, India
The effects of potassium ethyl xanthate used as collector and dichromate potassium a depressor on a PbS mineral were studied by the recently accepted technique in Mexico, high frequency impedance (transformed to dielectric values). Results of dielectric values at 100 MHz suggested that is possible to obtain from isotherm adsorption the adequate industrial collector concentration being this in the range of IE-3 to SE-3M of KEX. The e' values (320420) in the PbS-KEX system was increased as the KEX concentration was lowered). In the other hand the PbSK,Cr20 7 system showed higher values of e' (420-510) as the K 2Cr20 7 concentration was increased. The PbS-KEXK,Cr20 7 system was evaluated, obtaining the KEX concentration dominion on K,CrZ07•
Aluminium hydroxide gels have been widely used in applications like sorbents and catalyst supports. Thermal treatment of aluminium hydroxide gels i.e., calcination and/or sintering, first leads to dehydration and then a series of phase changes. Once dehydration is complete several transition aluminium oxides namely y, Ii and 6 appear, and finally aNz03 is formed at about 1200°C. In the current investigation boehmite (AIOOH) a bayerite (AI(OH)3) have been prepared in the presence of water-glycerol solutions. The results indicate that the precipitation media have considerable influence on the nature of aluminium hydroxide precipitate. Aluminium hydroxide gels thus prepared were characterised by TEM and XRD. Calcined powders were examined by XRD for phase content, by SEM for morphology and BET method for specific surface area. Calcination of aluminium hydroxide gels prepared by Hot water hydrolysis-Controlled precipitation technique yielded agglomerate free, spherical aAlp3 powder. AlP3 was also prepared by calcining the aluminium hydroxide gels at 600°C and characterised by XRD, TEM and BET method.
2:40pm GYPSUM CRYSTALLIZATION IN ACIDIC WASTEWATER TREATMENT: A Review of Current Practice and a View on Process Improvement: S. Ornelon, G.P. Demopoulos, McGill Department of Mining and Metallurgical Engineering, 3450 University St., Montreal, Canada H3A 2A7 Acidic sulphate-containing wastewater streams are currently neutralized with lime before discharge to the environment. The most common neutralization process design involves a one-step neutralization followed by a settling tank that separates an ultra-fine, low solids density gypsum by-product. The final gypsum quality is undesirable as it is voluminous and has a high surface area that sorbs metal ions. The paper will critically review the current practice of gypsum precipitation. It will also report the progress of a project which uses crystallization principles and supersaturation control to develop a new process. The new process design utilizes a model that was constructed to predict gypsum solubilities in H 2SO.-ZnS04-FeS04-MnSO.-MgS04 solutions from 2S-60°C. By maintaining a low gypsum supersaturation with a series of CSTR's and providing gypsum seed with a solids recycle, the generation of high solids density gypsum is favoured. Early results will be presented, as well as results on Zn2+ adsorption.
3:50pm CONTINUOUS BACTERIAL LEACHING OF A LOW-GRADE MANGANESE DIOXIDE ORE: S. Agatzini Leonardou. J.G. Zafrratos, Laboratory of Metallurgy, Department of Mining and Metallurgical Engineering, National Technical University of Athens, Athens, Greece The leaching of a Greek low-grade manganese dioxide ore, not amenable to conventional mineral processing operations, was studied using a mixed culture of Thiobacillus sp. bacteria. The experiments were carried out in specially designed continuously aerated and stirred tank reactors arranged in twotank series. The first tank of each series was loaded with an elemental sulfur culture suspension while the second was loaded with a manganese ore high density slurry. The bacterial culture had been previously adapted to grow on elemental sulphur and also in the presence of manganese ore and dissolved manganous ion. A two level full factorial design, was constructed in order to study the effects of the ferric ion concentration in the leach solution, the "elemental sulphur weight to ore weight" ratio, the ore pulp density and the composition of the dispersed gas. The responses which were investigated included percentage manganese recovery, co-dissolution of iron and manganese dissolution rate. Parameters with constant values throughout the experiment were the leach solution pH, the nutrient medium composition, the dilution rate and the ore and sulphur grain sizes. It was found that the ferric ion concentration was the most significant factor and had a positive effect on the final percentage extraction of manganese from the ore and also on the rate of manganese solubilisation from the ore. The effects of the other factors studied are discussed in detail.
3:00 pm ANALYSIS OF THE HEMATITE PRECIPITATION PROCESS FROM A CRYSTALLIZATION POINT OF VIEW: T.C.-M. Cheng, G.P. Demopoulos, McGill Department of Mining and Metallurgical Engineering, 3450 University St., Montreal, Canada H3A 2A7 Iron removal and disposal in zinc and nonferrous hydrometallurgical plants at large constitutes one of the major environmental challenges to the industry. So far three technologies have been used by the zinc industry to effect iron rejection, namely the Jarosite, the Goethite, and the Hematite Processes. Among them, it is the Jarosite Process that has dominated the scene. However jarosite residues tend to be voluminous (only 25% Fe content) and highly toxic due to incorporation of Zn, Cd, Pb, and other heavy metals, not to mention the relatively high Zn losses. The industry addresses the heavy metal release problem by further stabilizing jarosite prior to disposal as is done, for example, in the Jarofix Process. On the other hand, hematite residues produced by the Hematite Process have a very high iron content and low zinc losses but come with a relatively high operating cost. At present, commercial produced hematite residues are still considered a waste because of the impurities contained in them whereas the two major troublesome impurities are sulfur and zinc. Hematite technology may become more attracti ve if the produced hematite is clean enough to be used as a feed material for iron-steel making. In this paper, the practice of industrial hematite precipitation and the relevant technical literature are reviewed with the objective to identify the critical processing parameters which are responsible for the contamination of hematite with sulfur and zinc. The analysis is done from a crystallization theory standpoint. The role of supersaturation control or lack of it is emphasized in the analysis. Finally, the main elements of a research program focus-
4:10pm Ni, Co & Cr RECOVERY FROM NICKEL LATERITE LEACH LIQUORS BY BIOSORPTION USING IMMOBILISED ALGAL BIOMASS: S. Agatzini - Leonardou, J.G. Zafrratos, Laboratory of Metallurgy, Department of Mining and Metallurgical Engineering, National Technical University of Athens, Athens, Greece The objective of this work was to prove repeated loading capacities of physically stabilized algal biomass from Spirulina platensis and Chlorella sp. for the removal and recovery of cobalt, nickel and chromium from laterite heap leach liquors. The testwork was carried out on a bench scale in small columns and proved that it is possible to immobilize the biomass on the highly porous surface of pumice stone. Nickel and cobalt could be removed from pure aqueous solutions of each metal by cyanobacterial biomass of the species Spirulina platensis and Chlorella sp. immobilized on the mineral. Nickel and also cobalt biosorption was sensitive to the initial solution pH. The maximum amount
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of cobalt was retained on the biomass at pH 6.0, while nickel was removed most effectively at pH 5.5. Repeated loading capacities of physically stabilized algal biomass from Spirulina platensis and Chlorella sp. were proven effective for the removal and recovery of cobalt and nickel from solutions resembling diluted laterite heap leach liquors. A lifetime of at least 5 loading cycles of the immobilized biosorbent material was obtained. The loading capacity of the immobilized biomass for nickel was comparatively lower than the capacity of the same biomass for cobalt. Cobalt recoveries up to 80% were achieved after 5 loading cycles under unoptimized conditions whereas nickel was removed completely (100%) under the same conditions. The described process might be applicable to recover cobalt from diluted laterite heap leach solutions.
3:00pm APPLICATION OF THE METAL COMPRESSION FORMING PROCESS FOR THE PRODUCTION OF AN ALUMINUM ALLOY COMPONENT: R.M. Purgert, Precision Metal Forming Co., P.O. Box 25441, Garfield Heights, OH 44125; S. Viswanathan, Metals and Ceramics Division, Oak Ridge National Lab, Oak Ridge, TN 37831-6083 Metal Compression Forming (MCF) is a variant of the squeeze casting process, in which molten metal is allowed to solidify under pressure in order to close porosity and form a sound part. However, the MCF process applies pressure porosity and form a sound part. However, the MCF process applies pressure on the entire mold face, thereby directing pressure on all regions of the casting and producing a uniformly sound part. The process also enhances the solidification rate of the metal promoting a very fine grain structure which results in improved properties. Consequently, the process is capable of producing parts with properties close to that of forgings, while retaining the near net shape, complexity in geometry, and relatively low cost of the casting process. The paper will describe the casting process development involved in the production of a 356 alloy engine mounting bracket, including the use of a filling and solidification model to design the gating and determine process parameters. Tensile and fatigue properties of the component will also be presented and correlated with those of forged components. *Research sponsored by the U.S. Department of Energy under contract DE-AC05-960RT22464 with Lockheed Martin Energy Research Corporation.
AUTOMOTIVE ALLOYS II: Process-Product Applications Sponsored by: LMD Aluminum Committee Program Organizers: Dr. Subodh K. Das, ARCO Aluminum, Inc., P. O. Box 32860, Louisville, KY 40232; Dr. George J. Kipouros, Technical University of Nova Scotia, Department of Mining and Metallurgical Engineering, P. O. Box 1000, Halifax, Nova Scotia, Canada B3J2X4 Wednesday, PM February 12, 1997
Room:340A Location: Orlando Convention Center
3:30 pm BREAK
Session Chairperson: Dr. George J. Kipouros, Technical University of Nova Scotia, Department of Mining, and Metallurgical Engineering, P. O. Box 1000, Halifax, Nova Scotia, Canada B3J2X4
4:00pm SYNTHESIS AND PROPERTES EVALUATION OF CHAR-REINFORCED AI-Si ALLOY COMPOSITES: J.U. Ejiofor, R.G. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, P.O. Box 870202, Tuscaloosa, AL 35487, B.A. Okorie, Department of Metallurgical and Materials Engineering, Enugu State University of Technology P.M.B. 01660, Enugu, Nigeria
2:00pm A NEW RESISTANCE SPOT WELDING TECHNIQUE FOR ALUMINUM ALLOYS: Hua-Xin Li, Mark T. Smith, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352
The application of carbon-reinforced aluminum composites in electromechanics has continued to attract new research investigations. The factors of interest range from low cost and availability of materials to lowtemperature processing methods. This study has investigated the conventional double-compaction, powder metallurgy processing of AI-13.5Si-2.5Mg alloy (wt. %) reinforced with coconut shell chars. The mechanical, physical and relevant tribological properties were determined after achieving the optimum compaction and sintering conditions. Use of optical microscopy, EPMA, SEM and energy dispersive analysis were made in characterising the matrix-reinforcement interfaces, the fracture surfaces and the nature of the adhesive dry wear. At 0.02V, of the char, the alloy exhibited properties suitable for antifriction applications. Increased additions of the chars resulted in largely reduced strength, hardness and sintered density. This is attributed to poor bonding of the char particles with the matrix alloy. Parallel investigations with palm-kernel shell char as the filler phase yielded identical results. Initial formation of AI,C3 in the composites was detected at a sintering temperature of 600°C. Reinforcement of the alloy with chars activated in CO2 to various bum-off percentages were found to yield marginal results.
A new technique is developed to overcome or minimize the inherent problems associated with aluminum RSW. Test results on I mm thick 6061 aluminum alloy sheets have shown that the new method can dramatically improve almost all of the problems encountered using conventional RSW. By using the new method, the following improvements have been achieved: I) reducing/eliminating electrode contamination; 2) eliminating/minimizing surface indentation and deformation; 3) increased weld nugget size by 200% with same welding parameters; 4) maintaining consistent weld nugget size; and 5) no cleaning is needed, particularly at faying surfaces. Peeling strength is high and failure in peeling testing occurs in base metal around weld nugget. Metallographic investigation shows favorable oval nugget shape on cross section, which can improve weld nugget high peeling strength. The ratio of major axis to minor axis is 7 with major axis being 6.5 mm long. Weld nugget mechanical properties such as tension-shear strength is being evaluated and will be presented. 2:30pm THERMOMECHANICAL PROCESSING OF 5XXX ALLOYS FOR GRAIN SIZE CONTROL AND STRESS-CORROSION CRACKING RESISTANCE: 1.S. Vetrano, A.L. Lund, M.T. Smith, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352
4:30pm ALUMINUM FRONT TRANSVERSE CROSSMEMBER: CHOICE OF THE MATERIALIPROCESS AND DESIGN OPTIMIZATION: Dr.lng S. Durante, Dr. Ing. A. Fuganti Centro Ricerche FIAT, Strada Torino, 50-1100430rbassaro-TO
The utilization of aluminum alloys for lightweight automotive structures can be increased by improved formability and a reduction of stress corrosion cracking (SCC) problems associated with magnesium additions greater than about 3%. We have utilized a series of thermomechanical treatments on several 5xxx alloys (5052, 5082, 5083, 5454 and 5754) to alter the dispersoid density and size, as well as the distribution of eutectic constituents. The aim has been to optimize grain size for specific forming operations and post -formed properties. In addition, the role of the grain size and particle distribution, as well as the magnesium content and microstructure, on the SCC resistance has been investigated. It was found that the grain size could be controlled by the distribution of the dispersoid particles, with a minimum grain diameter of 8 Jim achieved in the 5083. The effect of grain size on SCC susceptibility was also evaluated.
A simultaneous engineering activity was aimed at defining the suitable materiaVprocess and design of a new front transverse crossmember for new Alfa Romeo high level car. The required objectives of weight reduction and stiffness increase drove towards an aluminum alloy solution with a complex shape design having a squared section. The alloy A356 was chosen as best candidate because it assures a good compromise between mechanical properties and castability. In fact his part is considered a safety component where high values of toughness are required. Moreover due to the necessity to obtain a monolytic component, in order to reduce the cost, the choice of an high castability alloy was considered of primary importance. A bench marking activity among different processes (Thixoforming, Squeeze casting, Lost Foam, Low Pressure Die Casting, VRC-PRC) was performed in order to se-
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lect the best compromise in terms of obtainable dimensional tolerances, reliability, productivity and costs. On the basis of the process features a design of the component was carried out having as reference a previous solution made in steel. The calculated performances were: stiffness increase of about 80%,weight saving of about 33%, with respect to the steel solution.
3:35pm AUTOMATIC STUB STRAIGHTENING SYSTEM Jon Hjaltalin Magnusson, ALTECH Ltd., Borgartun 18, 105 Reykjavik, Iceland; William Cannon, Portland Aluminium Ltd., Portland, Victoria 3305, Australia For improving the economy and environment aluminium smelters have increased the automation of diverse tasks. An automatic system has been developed for the task of straightening anode rod stubs instead of cutting them off the rod yoke and welding new onto the yoke. The stub toe-in problem cannot be eliminated, but significant degree of control can be implemented to eliminate its adverse effects and increase the useful life of the stubs and reduce the considerable cost of reparation and stub material. This paper describes the cause of the stub bending in the electrolitic cells together with the details of the new automatic stub straightening system based on preheating the stubs with induction heating coils prior to straightening in a hydraulic cylinder press. Implementation of this straightening system at Portland Aluminium in Australia is also described, where the system was installed in February 1996. The system is installed "in-line" in the P&F overhead monorail and the bending of the stubs is measured automatically for deciding if the straightening is required or not. It will be shown how this system improves the useful life of the stubs leading to significant operational savings for the smelter.
CARBON TECHNOLOGY IV: Anode Plant Sponsored by: LMD Aluminum Committee Program Organizer: Jean-Claude Thomas, Aluminium Pechiney, Pechiney/Balzac, 92048 Paris la Defense, France
Wednesday, PM February 12, 1997
Room: 230C Location: Orlando Convention Center
a
Session Chairperson: Prof. Vasar Kocaefe, Universite du Quebec Chicoutimi, Chicoutimi, Quebec, Canada G7H2B1
2:00pm BUTTS CLEANING AT SLOVALCO IMPLEMENTED BYTECHMO: J. Ifju, F. Zannini, F. Marchetti, M. Fontolan, Techmo Car S.P.A., Via R. Colpi, 15/l7 35010 Limena (PD) Italy
CASTING & SOLIDIFICATION TMS General Abstract Session
The best use of anode carbon and bath materials withdrawn from the smelting process by anode changing involves their recycling. In order to provide optimal composition of recycled carbon and bath, a butt cleaning technology is required with the aim to avoid their contamination by each other. A technology and equipment has been elaborated for implementing above objective. Some optimization was fulfilled in order to meet the requirements of the new aluminium smelter implemented by Hydro Aluminium technology, taking into account very tough requirements to the material quality, as well as fitting a piece of equipment into the technology flowsheet planned.
Wednesday, PM February 12, 1997
Room: 231A Location: Orlando Convention Center
Session Chairperson: Dan J. Thoma, Los Alamos National Laboratory, Materials Science Technology Division, MS G770, Los Alamos, NM 87545
2:00pm OPTIMIZATION OF THE ANGULAR WIDENING OF A CAST PLATE: J. Stetina, F. Kavicka, Technical University of Brno, Mechanical Engineering Dept., Technicka 2,61669 Brno, CZECH REPUBLIC; J.M. Khodadadi, Mechanical Engineering Dept., Auburn University, Auburn, AL 36849-5341
2:25 pm DUST CONTROL TECHNOLOGY FOR ANODE BUTT RECYCLING: Nathalie Perreault, Betz Water Management Group, Casier Postal 232, Baie Comeau, Quebec, Canada G4Z 2G9; Eric Grondin, Engineering Environment and Water Treatment, Reynolds Metals, 100 route Maritine, Baie Comeau, Quebec, Canada G4Z 2H7
A 2-D numerical model was used to analyze the temperature field of a vertically cast 17oox6oox40mm plate with different angles of widening in its cross section (0 to 4.4°). From the side of the widening, the plate was either isolated (using Plastizol) or non-isolated. A non-isolated plate has an optimum angular widening of 3° and the widening of 2° lies on the boundary of the origins of internal defects (e.g. shrinkages). The isolated plate has an optimum angle of widening of 2°. Using the calculations it is possible to predict that the plate itself will have the same internal quality with a widening of 3 ° after crystallization without isolation as with 2° of widening with the isolation. The knowledge gained in this study can lead to the reducing of the volume of liquid metal needed and to the lowering of costs for working the surface. (Authors are grateful to the US-Czech Science and Tech. Program for support of this research.)
There are several dust control problems in the Aluminium industry, amongst them is the process of recycling anode butts. In general, prior to being recycled, the butts are cleaned, taken off the hexapod rods and stored and/or shipped to be processed as new anodes. A particular area of concern for fugitive dust during the anode preparation process is anode butt stripping inside the anode rodding room. This process generates a lot of carbon dust. It has been both a health and safety issue, as well as cleaning burden for operating personnel. This paper presents different alternatives, both mechanical and chemical, for controlling fugitive dust, and a decision process for using chemical treatment. In addition, the theory behind the chemical application and a case history will also be presented. 2:50pm EFFICIENT ANODE-COLLAR CAST IRON MICROSTRUCTURE: Michael Barstow, 1152 Southvale Road, Pittsburgh, PA 15237
2:20pm TEXTURE EVOLUTION IN y-TIAI SHEETS PRODUCED VIA THE MELT OVERFLOW RAPID SOLIDIFICATION PROCESS: M.L. Weaver, Center for Nonlinear and Nonequilibrium Aeroscience, Florida A&M University, 1800 E. Paul Dirac Rd., Rm. A337, Tallahassee, FL 32306-4005; H. Garmestani, Dept. of Mechanical Engineering, FAMU-FSU, College of Engineering, FloridaA&M University, Tallahassee, FL 32306; G. Das, United Technologies, Pratt & Whitney, P.O. Box 109600, West Palm Beach, FL 334109600
Cast iron is used to secure the steel stub of an anode rod to a carbon block for aluminum reduction cells. The quality is measured by the millivoltage drop across the stub-carbon interface. The electrical resistivity of cast iron varies with it's microstructure, which changes with temperature. Cast iron cannot be simply specified by analysis since it is section sensitive, and the microstructure is affected by minor elements, time, and rate of cooling. If the metallurgical control is limited, collars will develop variable electrical efficiencies. Recycling cast iron callors also causes a change inthe minor element analysis (S,P) which will change the microstructure / electrical resistivity. A cast iron designed for optimum fluidity with low level minor elements will provide lower electrical resistance than one with buildup of Mn, S. Other melting efficiencies are predicted.
The production of y- TiAI foils by conventional ingot metallurgy involves casting ingots, hot forging ingots into billets, followed by several hot rolling, heat treatment, and surface grinding sequences. These methods, however, can result in production losses in excess of 50%. Recently, researchers at NASA-Langley and Ribtec have developed the Plasma Melt Overflow Process which combines plasma arc skull melting in a water cooled copper crucible with Melt Overflow Rapid Solidification Technology (MORST) allow-
3:15 pm BREAK
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ing near-net-shape processing of strips that can be hot pack rolled to foil gauge with minimal production losses. Preliminary results indicate that foils produced via this method exhibit finer more uniform microstructures, higher strength, and higher ductility than comparable ingot metallurgy foils. In this investigation texture evolution has been evaluated in y-TiAI alloys sheets produced via this technique. The results are compared with recent studies of texture in conventionally processed y- TiAI.
3:50pm MICROSTRUCTURAL EVOLUTION IN AI-Cu-Si ALLOY MELT SPUN RIBBONS: K.-P. Cooper, J D. Ayers, H.N. Jones, R. Vardiman, Naval Research Laboratory, Code 6321, Washington, DC 20375-5343 Several AI-Cu-Si alloys were melt spun to produce stable, fine grain microstructures that would be amenable to superplastic deformation and consolidation. Scanning electron microscopy of the ribbon cross-sections showed two distinct alternating microstructural morphologies suggesting transitions in solidification behavior. One consisted of intimately interlocked Al and AI2Cu (9) phases with dispersed Si. The other consisted of equiaxed dendritic Al with inter- dendritic 9 and Si. The latter was found usually in the middle portion of the ribbon cross-section. The solidification mechanism for the interlocked structure is not understood, but its formation may have involved multiple nucleation of the phase or a degeneration of a more regular, but unknown, initial structure as the ribbon cooled to ambient temperature. The equiaxed dendritic structure probably arose as a result of independent nucleation events in the supercooled liquid ahead of the solid-liquid interface. Transmission electron microscopy revealed AI grain sizes varying from l!Lm near the wheelside to 8 !Lm with subgrains near the free surface and different shapes and sizes for 9 and Si in the interlocked and dendritic regions.
2:40pm LIQUID METAL-SOLID METAL REACTIONS WITH INTERMEDIATE INTERMETALLIC COMPOUND FORMATION: Robert J. Hanrahan Jr., Dan J. Thoma, LorenA. Jacobson, Los Alamos National Laboratory, Materials Science Technology Division-MST-6, TA 3, MS G770, Los Alamos, NM, 87545 The study of liquid metal reactions have in most cases involved systems where the solid is dissolved by the liquid. The case where an intermetallic compound forms between the two metals has not been thoroughly investigated. As an example of this class of system we have chosen to study the reaction of Beryllium (solid) - with Rare Earths (liquid). Although most of the Be-RE phase diagrams are poorly defined in terms of solubility and the location of the eutectics, all have been characterized to the extent of having a single intermetallic compound with a melting point in excess of 1500°C and two simple eutectics with minimal solubility range in the solid phases. The intermetallic in each case is the same structure, Mbe 13 • The reaction kinetics, measured using the thickness of the intermetallic layer at various times, can be described by a parabolic model suggesting that the reaction is controlled by diffusion through the intermetallic. Variations in kinetics are observed between the various systems which are analyzed considering factors such as melting point of the liquid (eutectic temperature), Be solubility in the liquid, and compositional range of the intermetallic.
4:10pm HEAT TRANSFER AND SOLIDIFICATION IN UPCASTING OF COPPER: K. Harkki, L. Holappa, Helsinki University of Technology, Laboratory of Metallurgy, Vuorimiehentie 2, FIN-02150 Espoo Finland An extensive study has been conducted to find out heat transfer and solidification behaviour in the copper upcasting mold. The casting direction in the upcasting process is vertically upwards and it has applications for copper and copper based alloys. The study combined industrial scale measurements, mathematical modeling and me/a110graphic examination of the cast rod samples. The industrial scale measurements involved temperature measurements with 14 thermocouples inserted in the copper jacket of the mold. Also temperature measurements of the cooling water were carried out. Axial heat flux profiles were determined quantitatively from the temperature measurements and they were used as boundary condition for the mathematical model calculations. The heat flux was observed to have a maximum value near the meniscus and to decrease rapidly with increasing distance up to the mold. Temperature profiles in the cast rod were simulated using a model based on finite element method. The results of the simulations were utilized for further understanding of the heat transfer and solidification process in the mold. Copper rod samples were examined to evaluate crystal growth of the cast copper rod. The results of the investigation work can be utilized to optimize the copper upcasting process.
3:00pm POTENTIAL OF SQUEEZE CASTING ALUMINUM (AI) AND ALUMINUM-REINFORCED METAL MATRIX COMPOSITES (AI-MMC) FOR BOTH THE AUTOMOTIVE AND ARMY GROUND VEHICLE APPLICATIONS: Paul J. Huang, Army Research Laboratory, AMSRLMA-B, APG, MD 21005; Robert Purgert, Precision Metal Forming Co., P.O. Box 25441, 9545 Midwest Ave., Garfield, OH 44125 The main driving forces for lightweight materials for the automotive industry and military applications are cost effectiveness, high-strength, and wear resistance. Precision Metal Forming Company (PMF) has developed a new and innovative squeeze casting process called metal compression forming (MCF). MCF integrates the deceptively simple concept of solidification of metal under direct pressure with closed die forging and low-pressure permanent-mold fill technologies. This hybrid process therefore combines the advantages of traditional direct squeeze casting and low-pressure permanent-mold casting. This study discusses property advantages attained with this process over traditional aluminum casting processes.
4:30pm RISERING EFFECT ON THE MICROSTRUCTURE OF ASTM F-75 INVESTMENT CASTINGS: M. Castro, L.F. Ramirez, M. Herrera, H. Maucha, M. Mendez, J. Mendez, Centro de Investigacion y Estudios Avanzados del IPN-Unidad Saltillo, Carr. Saltillo-Monterrey Km. 13, 25000 Saltillo, Coahuila, Mexico
3:20 pm BREAK 3:30pm KINETIC COMPETITION DURING DUPLEX PARTITIONLESS SOLIDIFICATION: Donald R. Allen, John H. Perepezko, Dept. of Mat. Science and Eng., University of Wisconsin - Madison, Madison, WI 53706
As-cast mechanical properties in dentritic alloys, as Co-based materials, are strongly dependent on the porosity level developed during the solidification process. High ductility levels can only be achieved when the porosity is completely eliminated. In such a high reactive materials, to avoid the problems conveyed by the high temperatures required to produce sound porosity-free castings, it is necessary to explore other solutions as those applied in conventional casting process for defect elimination. In this study, we report the effect of different size risers on the porosity formation in investment cast ASTMF-75 alloys. The liquid metal at 1430°C was poured into cylindrical ceramic molds preheated at 900°C. The morphology as well as the location of the porosity changed with the riser size. An intergranular porosity situated in the center section was observed when it was applied to the biggest size riser. When using the smallest size riser, an additional elongated, and peripherically situated porosity appeared. The observed changes in porosity are associated with the microstructural changes; while in the former case the grains are equiaxed, in the second case the grains are columnar. As the dendritic arm spacing showed that the cooling rate was very similar in both cases, the results are explained considering the nucleation mechanisms.
A structure composed of both partitionless face-centered cubic (fcc) and bodycentered cubic (bcc) phases has been observed following high undercooling solidification of nickel-vanadium (Ni-V) alloys for the composition range 4751. 7 at. % V. Transmission electron microscopy analysis has identified regions in which fcc and bcc grains on the order of 100 nm in size coexist in a duplex structure. Splat-quenched foils were analyzed both in plan view and cross section. This structure has revealed a unique set of kinetic conditions that can allow for duplex solidification, since similar nucleation and growth rates are required for a range of compositions. A nucleation and growth kinetics analysis has been developed to describe the conditions under which this structure may form. The duplex partitionless structure previews an entirely new class of microstructures achievable during high undercooling solidification processing. The support of NASA (NAG8-1278) is gratefully acknowledged.
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4:50pm THE CONTROL OF DENDRITE TIP GROWTH RATE ASA WAY TO PROMOTE GOOD MICROSTRUCTURES IN DENRITIC ALLOYS: H. Mancha, F. Cepeda, M. Herrera, J. Mendez, M. Castro, M. Mendez, Centro de Investigacion y de Estudios Avanzados del IPN-Unidad Saltillo, Carr. Saltillo-Monterrey Krn. 13-Apdo. Postal 663, 25000 Saltillo, Coahuila, Mexico
process. They also impose severe complications for alloy down-gauging. This paper presents the morphological aspects of the major inclusions commonly seen in AA31 04 can stock alloy. The potential sources which may introduce inclusions in the alloy are also described. Some case studies are conducted to isolate the inclusions for characterization. The results can be utilized for understanding the mechanism of the inclusion formation and selection of proper materials in dealing with the molten alloy prior to ingot casting in order to minimize or eliminate the potential inclusion sources.
As-cast mechanical properties, in particular ductility, of equiaxed and dendritic alloys such as Co-based alloys and AI-based alloys are strongly dependent on size and spatial distribution of second phase particles. In this paper, we present the results of a mathematical modeling study on the solidification process of these type of alloys. The effect of cooling parameters and nucleating conditions, in the grain growth kinetics of denritic structured grains, are presented and compared with experimental results. High nucleation rates as well as low cooling rates produce small grain size with large intergranular second phase particles. On the opposite side, low nucleation rates and high cooling rates allow the formation of large grain size with small fractions of intergranular second phase particles and high volume fractions of intragranular smaller second phase particles. These intragranular particles have a different chemical composition to those located in grain boundaries. In the case of Cobased alloys, it seems to be necessary to complete elimination of large intergranular lamellar structured carbides to obtain the 8 percent elongation to fracture established by the ASTM F-75 international standard. The grain growth kinetics control, based on the control of the dendrite tip growth rate, offers a way to obtain grain microstructures that allow the best as-cast mechanical properties. The same principle is applicable to the AI-based alloys. The mathematical model predictions on volume fraction and spatial distribution of second phase particles are discussed and compared with the experimental results.
2:20pm USE OF MULTIPLE MOLTEN METAL QUALITY INDICATORS TO ASSESS IMPACT OF FILTRATION AND FLUXING MODIFICATIONS ON INTERNAL QUALITY OF PLATE PRODUCTS: Michael M. Niedzinski, Reynolds Metals Company, McCook Sheet & Plate Plant, 1st Avenue & 47th Street, McCook, IL 60525-3294 Feasibility of modifying the molten metal filtration system used on aircraft plate alloys was examined using LiMCA, LAlS, AISCAN and Ramsley tests with attempts to correlate to final ultrasonic quality of the final product. Simultaneously, impact of alternate fluxing system on an ultrasonic quality was examined using aforementioned tests. Sensitivity of the tests vis-a-vis practice changes is discussed. 2:40pm EVALUATION OF THE EFFICIENCY OF CERAMIC FOAM AND PARTICLE BONDED CARTRIDGE FILTRATION SYSTEMS: N.J. Keegan, Foseco International Ltd., 285 Long Acre, Nechells, Birmingham B7 5JR, United Kingdom; W Schneider, H.-P. Krug, VAWaluminiumAG, Georg-von-Boeselager-Str.25, D-53117 Bonn, Germany; V. Dopp, Foseco GmbH, Postfach 1220, D-4280 Borken, Germany
5:10pm MODELLING QUENCHED IN SHORT-RANGE ORDER IN METALLIC ALLOYS: A. Varschavsky, E. Donoso, Universidad de Chile, Facultad de Ciencias Flsicas y Matematicas IDIEM, Casilla 1420, Santiago, Chile
A joint programme was set up between Foseco and YAW aluminium AG in order to establish data on the relevant positions of fine foam ceramic filters and more specifically, to investigate the performance characteristics of bonded particle tube cartridge filter systems. The object of this work was to generate fundamental data on the filtration efficiency of a number of in-line treatment units used singly and in combination. The impact of these treatments on metal quality was determined by LiMCA, PoDFA and LAIS for carefully controlled plant conditions. This paper expands on the result of the fust phase of the programme which was presented to TMS in 1996. It goes on to present results of inclusion size distribution removal data for medium and fine pore CFF's and for the cartridge tube filter. Results of metallographic examination of spent tubes and ceramic foam reported along with PoDFA data of typical metal. After summarizing the relative efficiencies of each of these systems it also includes results of the impact of a degassing unit run alone and in combination with a ceramic foam filter.
Using a rate vacancy loss equation and an overall rate constant for order establishment, a model for describing the roles of quench temperature, quench rate and vacancy sink density is proposed. This model allows computation of the retained value of the first short-range order parameter of quenched binary alloys and the prediction that the most highly disordered state obtainable occurs with quenches from intermediate temperatures. Numerical results were tested against experimental data based on energetic analysis of differential scanning calorimetric traces pertaining to a reordering process towards the equilibrium state. Kinetic evaluations of these traces yield experimental estimates of quenched-in vacancy concentrations. Good agreement between modelled and experimental assessments was obtained in Cu at. % Zn alloy.
3:00pm CHARACTERISTICS OF PARTICULATE CAPTURED BY A RIGID TUBE FILTER: Glenn Mabry, We. Setzer, KB Alloys Inc., Corporate Technology, 3293 McDonald Road, Robards, KY 42452; John Kaems, Aluminum Company of America, Alcoa South Plant, 300 North Hall Road, Alcoa, TN 3770 I; Douglas Granger, Aluminum Company of America, Alcoa Technical Center, Alcoa Center, PA 15069
CAST SHOP TECHNOLOGY VII: Metal Treatment • Inclusion Removal Sponsored by: LMD Aluminum Committee Program Organizer: Wolfgang A. Schneider, VAW aluminium AG, Research and Development, Georg-von-Boeselager-Str.25, D-53117 Bonn, Germany Wednesday, PM February 12, 1997
Spent rigid tube filter sections were examined following a number of alloy 3004 casts. Examination revealed the presence of the phases normally found in 3004 which formed during solidification, as well as the capture of salt, oxide and grain refiner particulate. Chemical and SEM analysis revealed that, for the most part, two mechanisms of filter blockage appear to be operative. In addition to filter cake buildup, on a portion of the tube, some of the 1-2 micron grain refiner particulate have reacted within the filter body forming coarser complexes. The blockage mechanisms and their impact on filter life and filter design and usage are discussed.
Room: 230B Location: Orlando Convention Center
Session Chairperson: Gregory J. Hildeman, Aluminum Company of America, Alcoa Technical Center, 100 Technical Drive, Alcoa Center, PA 15069
2:00pm MORPHOLOGICAL ASPECTS OF INCLUSIONS IN AA3104 D&I CAN STOCK ALLOY: Xiangwen Wang, Manufacturing Technology Laboratory, Corporate Research & Development, Reynolds Metals Company, 3326 E. 2nd St., Muscle Shoals, AL 335661 Metallic and non-metallic inclusions have long been recognized as one of the most important quality issues for aluminum can body alloys. Existence of the inclusions is often the cause of pinholes and high tear-off rate in the canmaking
199
3:20pm INFLUENCE OF AI-Ti GRAIN REFINER ON THE FILTER LIFE: T. Yoshida, K. Kakimoto, Mitsui Mining & Smelting Co. Ltd., TKR Division, 2-26-6 Higashinihonbashi, Chuo-ku Tokyo 103, Japan; A. Hane, T. Nishizaka, K .Hoshino, Mitsui Mining & Smelting Co. Ltd., Corporate R&D Center, 1333-2 Haraichi, Ageo-shi Saitama 362, Japan It has been known that grain refiner such as AI-Ti and AI-Ti-B would influence on the filter life in molten aluminum filtration. A new experimental technique was conducted to make clear the influence of AI-Ti master alloy on a filter life of Rigid Media Filter (RMF). It is shown that the concentration of titanium in the grain refiner and holding time after adding the grain refiner affect the filter life. 3:40 pm BREAK 3:50pm DEPOSITION OF PARTICLES TO A BUBBLE: Elin Haugland, Thorvald A. Engh, Norwegian University of Science and Technology, Department of Metallurgy, Alfred Getz Vei 2b, N-7034 Trondheim, Norway Experiments have been performed to study turbulent deposition of particles to a bubble. Water, containing particles, flowed down through a column. Bubbles were let into the column through a glass capillary tube in the lower part of the column, and then held at the capillary tube. The experiments were carried out with quartz particles in both clean distilled water and in water which amine was added. The bubble was allowed to rise into a collector tube. To determine the amount of particles collected by the bubble, the water/particle dispersion was filtered and the remaining mass was weighted. Velocities and turbulence were measured by laser doppler velocimetry. Particle-bubble collisions were studied with a high-speed videocamera. The results indicate that particle collection on the bubbles reaches saturation. The particles seem to have a certain residence time at the bubble surface, before they leave the bubble. 4:10pm ENHANCED FLOTATION OF INCLUSIONS TO BUBBLES DUE TO TURBULENCE: Rune Gammelsceter, Stein Tore Johansen, SINTEF Materials Technology, N-7034 Trondheim, Norway; Knut Bech, The Norwegian University of Science and Technology, N-7034 Trondheim, Norway Experimental results indicate that turbulence may enhance the flotation rate of non-metallic inclusions to bubbles significantly. In this paper possible flow phenomena responsible for such effects are investigated. We recognize that the turbulent flow consists of a spectrum of eddy sizes. The eddies larger than the bubble diameter can only displace the bubble. Only the smaller eddies contribute to an enhanced turbulent deposition of inclusions. The turbulent flow over single bubbles are computed and the turbulent trajectories of inclusions approaching the bubbles are calculated. The resulting collection efficiencies are discussed and compared to available experimental results.
was developed to predict the rate of inclusion removal in induced current systems. The experimentally determined rate was found to be in good agreement with theoretical predictions. The scale-up of the system for industrial applications will be discussed. 4:50pm CONSISTENCY OF INCLUSIONS IN PURE MAGNESIUM: Per Bakke, Dag Ove Karlsen, Norsk Hydro a.s., P.O. Box 2560, N-3901 Porsgrunn, Norway; Jean-Alain Laurin, Andre Provost, Norsk Hydro Canada Inc., 7000 boul. Raoul-Duchesne, Becancour, Quebec, Canada GOX IBO In order to examine the consistency of metal quality with respect to oxide inclusions, salts and intermetallic particles, filter samples were taken randomly from the casting chamber during normal production of pure magnesium at Norsk Hydro Canada in 1995. The contents of oxide particles, oxide films, salts and intermetallic particles were measured by optical microscopy and image analysis of the sliced and polished filter samples. The results indicate that the contents of oxide particles, oxide films, salts and intermetallic particles are low and consistent; normally well below I mm3/kg for all types of inclusions. Oxide inclusions and intermetallic particles are usually smaller than 50 11m and 20 11m, respectively. The filter sampling method and analysis technique used in the quantitative microscopy are discussed in some detail, emphasising advantages and drawbacks. The impact of the most common inclusions in pure magnesium on aluminium alloy quality is discussed from a thermodynamic point of view. 5:10pm THE EFFECTS OF MAGNESIUM, ATMOSPHERE COMPOSITION, AGITATION AND TEMPERATURE ON THE SURFACE OXIDE FlLM FORMATION AND MELT INCLUSION CONTENT IN AI-Mg ALLOYS: Daryoush Emadi, Mihriban Pekguleryuz, Alcan-UQAC Chair in Solidification and Metallurgy of Aluminum, University of Quebec at Chicoutimi, Local 4-333 Chicoutimi, Quebec, Canada G7H 2BI To obtain high quality ingots, the generation of inclusions must be prevented during the various stages of liquid metal manipulation. In an attempt to understand the nature of oxide film generation, the oxidation behaviour of AIMg melts with different Mg contents of 1 wt%, 3 wt% and 5 wt% were studied in air, argon and carbon dioxide. Moreover, the effects of agitation and temperature on the nature of melt surface oxide films were investigated. For each condition, the growth process and the morphology of the surface oxide films behaved differently. In addition, this study used the Liquid Metal Cleanliness Analyzer (LiMCA) and Porous Disk Filtration Apparatus (PoDFA) to investigate the effect of melt agitation and Mg content on the melt inclusion content. The results indicate that agitation and magnesium increase both the melt inclusion content and the average inclusion size. In addition, the oxide film removal from the surface of the melt affects the melt oxidation behaviour significantly.
4:30pm KINETICS OF INCLUSION REMOVAL FROM MOLTEN ALUMINUM UNDER AN APPLIED ALTERNATING MAGNETIC FIELD: Ashish D.Patel, Nagy EI-Kaddah, Department of Metallurgical & Materials Engineering, The University of Alabama, P.O. Box 870202, Tuscaloosa, AL 35487-0202 Electromagnetic filtration is an emerging technology for purification of molten metals. This particle separation method relies on the huge difference in the electrical conductivity of the metal and non-metallic inclusions to drive the motion of the under an applied force field. The principle of electromagnetic separation will be briefly reviewed together with methods of generating a force field in molten metals. Also described is an induced current separator for the removal of non-metallic inclusions from molten aluminum. The key feature of this system is that the force field has no stirring component, which is necessary to prevent particle entrapment within flow eddies. The system was used to investigate the kinetics of inclusion removal from molten aluminum using 100 and 200 11 size particles at low applied magnetic field of 0.015 T. The results show complete removal of these inclusion particles under these conditions and particle migration in the melt occurs in a direction opposite to the force field, as predicted by the theory. Analytical expression
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CHEMISTRY AND PHYSICS OF NANOSTRUCTURES AND RELATED NONEQUILIBRIUM MATERIALS VI: Mechanical Properties Sponsored by: Jt. EMPMD/SMD Chemistry and Physics of Materials Committee, MSD Thermodynamics and Phase Equilibria Committee Program Organizers: Brent Fultz, 138-78, CalifDrnia Institute DfTechnDIDgy, Pasadena, CA 91125; En Ma, LDuisiana State Univ., Dept. Df Mechanical Eng., BatDn RDuge, LA 70803; RDbert Shull, NIST, Bldg. 223, Rm B152, Gaithersburg, MD 20899; JDhn MDrral, Univ. Df CDnnecticut, Dept. Df Metallurgy, StDrrs, CT 06269; Philip Nash, IIlinDis Institute DfTechnDlogy, METM Dept., Chicago, IL 60616
Wednesday, PM February 12, 1997
Room: 330C Location: Orlando Convention Center
Session Chairperson: Philip NaSh, Illinois Institute of Technology, METM Dept., Chicago, IL 60616
2:00 pm INVITED MECHANICAL BEHAVIOR OF BULK NANOSTRUCTURED Fe/Cn ALLOYS: Walter W. Milligan, John E. Carsley, Stephen A. Hackney, Metallurgical and Materials Engineering, Elias C. Aifantis, Mechanical Engineering and Engineering Mechanics, Michigan Technological University, Houghton, MI 49931 The mechanical behavior of bulk iron alloys containing 10% copper was investigated. Grain sizes were varied by processing, and ranged from 45 nm to 900 nm. Deformation in all cases occurred by intense localized shear banding as the first and only mechanism of plastic deformation, from the yield point until fracture or buckling. Mechanical response was elastic-perfectly plastic. Shear band angles and an asymmetry of the yield strength in tension and compression both indicated the possibility of a pressure-sensitive yield criterion. Continuum models based on this approach proved promising. Shear band widths increased with microstructural coarseness, and were correlated successfully with a gradient plasticity approach. A number of similarities between the behavior of these alloys and amorphous materials such as metallic glasses and amorphous polymers will be discussed. 2:30 pm INVITED DEFORMATION MECHANISMS IN METALLIC NANOLAMINATES: Tim Foecke, Metallurgy Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-0001 It has been seen that the introduction of a nanolayered microstructure can increase the yield strength and hardness of a material to many times that of a conventional microstructure. The deformation mechanisms that operate (or fail to operate) at such a small length scale is not understood and is only beginning to be investigated. An in situ TEM deformation experiment has revealed a dislocation generation mechanism that operates in Cu/Ni single crystal nanolaminates. Dislocation loops nucleated at several locations within a Ni layer at the Cu/Ni interface, and were seen to expand until they intersected the next interface. Two Orowan bows were then seen to expand in opposite directions along the layer. Discussion will include possible nucleation sites and thin film artifacts, as well as presentation of otherTEM observations of fracture and deformation in metallic nanolaminates. 3:00 pm INVITED DEFORMATION AND FRACTURE BEHAVIOR OF HIGH· STRENGTH AI.4(V2,Ti)4Fe2 ALLOYS CONSISTING OF NANOGRANULAR AMORPHOUS AND Al PHASES: Akihisa Inoue, Hisamichi Kimura and Kenichiro Sasamori, Institute for Materials Research, Tohoku University, Sendai 980-77, Japan A new mixed structure consisting of nanogranular amorphous and fcc-AI phases was formed in melt-spun AI94 V4Fe2 and A1 94V2Ti2Fe, alloys and the complete replacement of V by Ti causes the change into a mixed structure of nanogranular Al phase surrounded by an amorphous phase. The structural change appears to result from the difference in solidification processes, i.e., the formation of the amorphous phase as a primary phase, followed by the Al
phase for the V-containing aUoys and the primary formation of the Al phases and then the amorphous phase for the V-free alloy. The former type is a unique process which is observed in the limited alloys containing V with icosahedral-forming ability and low diffusivity. The coexistence of the nanogranular amorphous phase is expected to affect significantly the mechanical strength, deformation behavior and fracture mode. These mixed phase aUoys have good bending ductility and exhibit high tensile strength of 1390 MPa for AI94V4Fe2. 1370 MPa for AI94V,Ti,Fe, and 1320 MPa for AI 94Ti 4Fe, at room temperature. The fracture mode is analogous to that for amorphous alloys. At the meeting, we will report the detailed results on the temperature dependence of mechanical strength, deformation behavior and fracture mode for the nanogranular amorphous alloys. 3:30 pm BREAK 3:45pm FATIGUE BEHAVIOR OF NANOCRYSTALLINEAND ULTRAFINEGRAINED Cn: S.R. Agnew', R.Z. Valiev2 , J.R. Weertman', 'Northwestern University, Evanston, Illinois, 'Institute for Metals Superplasticity Problems, Russian Academy of Sciences, Ufa, Russia One of the tests that can give insight into the deformation mechanisms of nanocrystalline and ultrafine-grained metals is fatigue. In the past, we investigated the microstructural stability of nanocrystalline (-20nm) Cu under cyclic loading. We observed good stability of the microstructure using XRD. An SEM study revealed extrusions on the surface, similar to those of persistent slip bands, oriented in the direction of maximum shear. The presence of extrusions suggests deformation by a shearing process. To augment our understanding of this phenomenon, we have begun studying the fatigue behavior of UFG Cu with a grain size of about 200nm. There we have observed similar extrusions as in the previous study. We are investigating the microstructural stability of this metal using the TEM. We will discuss our experimental results and their contribution to our understanding of the deformation mechanisms operative in pure FCC metals with ultra-fine microstructures. 4:05pm COHERENT SOLUBILITY LIMITS OF i-TYPE PHASES IN FOUR BINARY Ni-BASE ALLOYS: F. Li and A.J. Ardell, Department of Materials Science and Engineering, University of California, Los Angeles, CA 900951595 The eqUilibrium solubilities of coherent phases can be affected by the initial solute concentration of the alloy, Xo' This differs completely from incoherent equilibrium, wherein the solubility limits are independent of Xo' To investigate the relationship between coherent equilibrium solubility and Xo' Ni-AI, Ni-Ga, Ni-Ge and Ni-Ti alloys, each with several different values of Xo' were prepared by arc melting, rolling into sheet, solution, treating, and aging for times up to 1632 h at 500°C. The variation of solute concentration in the Nirich matrix, X, with aging time, t, was followed using measurements of the ferromagnetic Curie temperature. The equilibrium solubilities, X""' were estimated by plotting the data as X vs. t- 1I3 and extrapolating to t ll3 =0 (t =00), thus presupposing that coarsening of the expected y' -type phases in all four alloys is responsible for the variation ofX. X"" is unequivocally dependent on Xo' but whereas X"" in the Ni-AI, Ni-Ga and Ni-Ti alloys increases with increasing Xo as predicted theoretically by Ardell and Maheshwari, X"" in the Ni-Ge alloy system decreases. TEM is currently in progress to confirm the identity and state of coherency of the precipitate phases present. This work is supported by the National Science Foundation 4:25 pm INVITED SYNTHESIS, STRUCTURE AND PROPERTIES OF Cn/Nb NANOLAYERED COMPOSITES: H. Kung, A.J. Griffin, Jr., Y.C. Lu, M.E Hundley, T.-E.Mitchell, M. Nastasi, Los Alamos National Laboratory, MS K765 Los Alamos, NM The effect of composition wavelength (A) on the structure, electrical resistivities and mechanical properties ofCu/Nb nanolayered composites were evaluated. The as- sputtered multilayers, with A varying between 2sA and lOooA, exhibit a strong Kurjudmov-Sachs orientation relationship between the close packed planes and directions of the fcc Cu and bec Nb: { III lei 1<11l>{110 INb • As -decreases to IIA, the entire multilayer shows bcc structure. The Cu grows pseudomorphicallY on the bcc Nb which acts as a tem-
plate for the normally fcc Cu. The layers are heavily strained and there .is.a high density of dislocations present. As A increases from I1A to 25A. It IS suspected that there is enough loss of coherency to transform bcc Cu martensitically to fcc Cu. The mechanical and electrical properties of nanolayered CulNb composites with Cu in either fcc or bcc structure will be reported.
electronic circuits. However, some water flux and fusing fluid formulations contain ingredients which can have deleterious effects on the reliability of a product under certain operating and use conditions. There is a failure mechanism known as conductive anodic filament formation (CAP) which has been observed in PWBs boards treated with certain water soluble fluxes. This failure mode involves a debonding of the epoxy-glass interface and the formation of a conductive filament which grows along this interface from anode to cathode. This paper will report on those chemicals which tend to enhance this failure mode and will make recommendations on assuring the reliability of electronic assemblies.
DESIGN AND RELIABILITY OF SOLDERS AND SOLDER INTERCONNECTS: Session VI: Interconnect Design and Reliability in Electronic Packages II
2:50 pm INVITED INFLUENCE OF COMPONENT SOLDERABILITY ON RELIABILITY OF SOLDER JOINTS: Colin Lea, National Physical Laboratory, Teddington, Middlesex TWll OLW, UK
Sponsored by: MSD Flow and Fracture; SMD Mechanical Metallurgy; EMPMD Electronics Packaging and Interconnection Materials Committees Program Organizers: R.K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; D.R. Frear, Sandia National Laboratory, Mail Stop 1411, Albuquerque, NM 87185; S.M.L. Sastry, Washington University, Mechanical Engineering Dept., St. Louis, MO 63130; K.L. Murty, North Carolina State University, Materials Science and Engineering Dept., Box 7909, Raleigh, NC 27695; P.K. Liaw, University of Tennessee, Materials Science and Engineering Dept., Knoxville, TN 37996; W.L. Winterbottom, Reliability Consultant, 30106 Pipers Lane Court, Farmington Hill, MI 48331 Wednesday, PM February 12, 1997
The commonest mode of service failure of solder joints on circuit board electronics assemblies is low-cycle fatigue cracking from differential expansion during power-up and power-down of the equipment. The resistance of a solder joint interconnection to fatigue cracking is governed by both its microstructure and its geometry. In turn, these are both governed by the soldering process and the manner in which the molten solder wets and flows on the component metallisation; the component's solderability. Data will be presented, for surface mount assemblies, that relate component/circuit board solderability to solder fillet shape, and in turn to solder joint reliability. The best fillet geometry varies markedly between the many different styles and compositions of metallisation found on surface mounting components. Furthermore, the pass/fail criteria of solderability measurements are not necessarily related to the required solder fillet geometry for best reliability. Both infra-red reflow and wave soldering have been used, since the use of solderability on solder fillet shape may be quite different for the different manufacturing routes.
Room: 332 Location: Orlando Convention Center
Session Chairpersons: Puligandla Viswanatham, Texas Instruments Inc., Circuit Card Assemblies, 2501 South Highway 121, Mail Stop 3450, Lewisville, TX 75067; Walter L. Winterbottom, Reliability Consultant, 30106 Pipers Lane Court, Farmington Hill, MI 48331
3:20 pm INVITED SOLDERABILITY AND SURFACE MOUNT (SM) SOLDER JOINT SHAPE PREDICTION: D.J. Lewis}, M. Notisl, C. Munie 2. Donna M. Noctor, IMaterials Science and Engineering Department, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015; 2Lucent Technologies, Naperville, IL 60563; 3Lucent Technologies, Bell Laboratories, Room 22W208eo, 555 Union Boulevard, Allentown, PA 18103
2:00 pm INVITED ISSUES AFFECTING RELIABILITY OF SURFACE MOUNT SOLDER JOINTS: Sung K. Kang, IBM Corp., T.J. Watson Research Center, Room 37-250, P.O. Box 218, Yorktown Heights, NY 10598 Surface mount technology (SMT) has been practiced as the principal soldering method for the assembly of printed circuit boards (PCB) last ten years. SMT packages connected by solder joints occupy more than two thirds of a PCB real estate. SMT packages consist of both conventional formats such as small outline package (SOP), small outline 'J' leads (SOl), plastic leaded chip carriers (PLCC), or quad flatpack (QFP), and fairly new packages such as thin small outline package (TSOP), tape carrier package (TCP), chip-onboard (COB), ball grid array (BGA), and many more. In this talk, recent developments of SMT soldering technologies are briefly reviewed, followed by discussion of several technical issues affecting the reliability of SMT solder joints. The subject matters to be discussed include solder joint defects, microstructure, interfacial reactions, thermal fatigue, and Pb-free solders.
As a part of a program supported at AT&T Network Systems for continuous improvement in solderability, solderability modeling, and solderability specifications, an assembly trial was performed to determine the correlation of assembly yield to different combinations of solder volume, component coplanarity, component aging, and solder alloy. Through the use of wetting balance data and assembly yield statistics, soldering process charts correlating assembly yield to solder volume and coplanarity show that severe lead surface finish degradation would require (unmanufacturable) component coplanarities ofless than 1 mil to maintain 100% assembly yield. The 132110,25 mil pitch, BQFPs were pre-conditioned using high temperature and humidity to degrade lead surface finish. Standard tin-lead solder and three commercially available lead-free solders were used to vary the solder wetting characteristics. To determine a process window for solderability, solder volume was varied by using two different stencil thicknesses, and coplanarity was measured to determine the effect of mechanical tolerance. Electrical continuity and visual inspection showed that assembly yield decreased with decreasing solder volume, poorer mechanical tolerance, and increased component aging time. Wetting balance data showed trends for aging conditions, but a correlation to coplanarity was not found. Contact angle results indicate that tin-lead had best wetting properties however this conflicts with assembly trial results where tin-lead had the higher failure level than the lead-free alloys. The goals of this project were: to further define a process window for solderability with tolerances for volume and coplanarity distributions; (2) to refine solderability specifications; and (3) to verify a computer model used to assess solder joint geometry and joint quality based on solder alloy and component lead properties. Assembly yield was examined based on different combinations of solder volume, component coplanarity, component aging, and solder alloy.
2:25 pm INVITED RELIABILITY CONSIDERATIONS WHEN CHOOSING WATER SOLUBLE FLUX FOR ELECTRONIC ASSEMBLY: Laura Turbini, Georgia Institute of Technology, School of Materials Science and Engineering, 778 Atlantic Drive, Atlanta, GA 30332 There is a need for a fundamental understanding of the interaction of processing chemicals such as fusing fluids, soldering fluxes and cleaning agents with printed wiring board substrates. This need is driven by two factors: (I) the increased density oftoday's electronic products creates voltage gradients which are high enough to enhance degradation modes which are not important for less dense circuitry, and (2) the elimination of chlorofluocarbons (CFCs) and other ozone depleting cleaning agents due to their destructive effect on the stratospheric ozone layer has lead to a proliferation of new soldering fluxes and cleaning agents whose interactions with the printed wiring board (PWB) are not well characterized. Water soluble fluxes have been effectively used in high volume electronic manufacturing operations for a number of years. Their use has increased dramatically as they provided an opportunity to eliminate CFCs in the cleaning process. They provide excellent soldering with low defect levels and with a proper cleaning process can produce highly reliable
3:45 pm BREAK
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3:55 pm INVITED A SIMPLE DESIGN TOOL FOR EVALUATING LOW CYCLE SOLDER FATIGUE OF PACKAGE TO BOARD INTERCONNECTIONS: Ted Carper, Robert Von Mayr and Puligandla Viswanatham, Texas Instruments Inc., Circuit Card Assemblies, 2501 South Highway 121, Mail Stop 3450, Lewisville, TX 75067
5:05pm MECHANICAL AND CREEP CHARACTERISTICS OF Sn-3.5Ag FOR SOLDER-JOINT RELIABILITY: Hong Yang'+, P. Deane', P. Magill' and K.L. Murty+', 'Microelectronics Center of North Carolina, Research Triangle Park, NC 27709; +North Carolina State University, P.O. Box 7909, Raleigh, NC 27695
Low cycle solder joint fatigue analysis is an important aspect of assessing the package to board solder interconnection performance of circuit card assemblies. A simple analysis tool that takes into account the significant environmental conditions for storage, operation, transportation, etc., and calculates the number of cycles to failure for a given set of input parameters is described. These parameters include coefficient of thermal expansion (CTE) of individual elements of the assembly structures, temperature, duration, number and frequency of cycles. Both leadless and leaded component configurations are included in the design of this tool. Lead stiffness for leaded components are calculated using equations published in the literature.
Constant-load creep and stress relaxation tests of Sn-3.5Ag solder alloy were performed at high homologous temperatures from 25°C to 180°C. Single lap shear tests were conducted on joined flip chip packages with 33X 33 area array of Sn-3.5Ag solder bumps. Tensile creep tests were performed on bulk solder specimens. The steady-state strain-rates span 7 orders of magnitude ranging from 10-9 to 10- 12 (I/s). The apparent activation energy of creep was found to be 0.57 ev. The stress exponent (n) in the power-law creep equation is found to be about 10 which is unusually high compared to that for many other metals. A constitutive equation relating stress, temperature and strainrate for Sn-3.5Ag solder alloy was established. Low-temperature dislocationclimb deformation mechanism (with dislocation-pipe diffusion) is believed to be dominant in the medium-to-high stress region with power-law breakdown at very high stresses. Numerical simulations of a flip chip package were performed to characterize the failure modes. The effects of different design parameters were studied with regard to strain accumulation and stress distribution in the package under thermal cycles. Recommendations are made for design optimization. This work has been supported by the Microelectronic Center of North Carolina.
4:20 pm INVITED RELIABILITY INVESTIGATION OF BALL GRID ARRAY ASSEMBLIES FOR SPACE FLIGHT APPLICATIONS: Sharon Walton, Kirk Bonner, Electronic Packaging and Fabrication Section, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA91109 JPL, in a partnership with an industrial consortium, is engaged in the investigation of reliability and quality issues of Ball Grid Array Packages as they may be applied to space flight electronics. Performing tests to determine the solder joint reliability of assemblies using BGAs under temperature cycling is proving to be a real challenge for test engineers. It was recognized early in the program that a large number of the BGA solder joints would be under test simultaneously and that some sort of computer based assistance would be required to accurately track the failures and the time at which they occurred. JPL has been using the National Instrument LabVIEWTM software and SCXI hardware to set up our system. The data acquisition program, DAQ.VI, was written around LabVIEW, a graphics based operating system. The program controls the temperature chambers, gathers data from the interface cards, logs data, and provides operator interface. This system can monitor over 1500 channels for electrical continuity and 32 channels for temperature. This softwarelhardware system greatly simplifies the task of monitoring and tracking failures and the conditions when the failures occurred of a large number of solder joint channels through the automatic gathering and recording of the test results onto a personal computer data base.
5:25pm LEAD FINISH COMPARISON OF THREE LEAD FREE SOLDERS versus EUTECTIC SOLDER: Mark A. Kwoka, Dawn M. Foster, Harris Corporation, Semiconductor Sector, P.O. Box 883, Melbourne, FL 32902 The use of lead in electronics manufacture will probably be disallowed in the not too distant future. While data is currently being taken regarding the material properties of lead free solders, very little has been published regarding how the new lead free solders will respond to existing methods of solderability assessment. This study will provide an I. C. component lead finish comparision of three selected lead free solders with standard 63/37 Sn/Pb solder using wetting balance and "Dip and Look" solderability test techniques. In addition, an association between board level soldering performance, wetting balance and "Dip and Look" solderability test parameters of the lead free solders will be established.
4:45 pm SOLDER JOINT INTEGRITY IN TESSERA'S J.lBGA TM PACKAGE: Rao K. Mahidhara l Vern Solberg, Tom DiStefano l and Steve Greathouse2, ITessera Inc., 3099 Orchard Drive, San Jose, CA 95134; 2Intel Corp., CH6315,5000 W. Chandler Blvd., Chandler, AZ 85226
EVOLUTION AND ADVANCED CHARACTERIZATION OF THIN FILM MICROSTRUCTURES VI: Morphology
Chip-scale packages (CSP) are miniaturized IC packages that are being developed for applications ranging from memory chips to advanced high-performance processors. Adaptable to volume manufacturing, this type of package offers the performance and size advantages of a bare die, while conforming to the established infrastructure for electronic assembly. Tessera 's ~GA belongs to this new family of CSP, wherein the need to underfill the device has been eliminated. The reliability of solder joints in Tessera's J.LBGA package is presented. Modeling studies on solder joint integrity have been conducted via finite element analysis (PEA) to predict stress and strain distributions at the solder ball-joint interfaces and potential failure points. The modeling work is complimented by studies involving ball shear testing and, intermetallic growth via opticallSEMlEDAX techniques following long time static annealing and temperature cycling. These reliability studies are suggestive that Tessera's J.LBGAs are robust packages.
University, West Lafayette, IN 47907-1289; Steven M. Yalisove, Dept. Materials Science and Eng., HH Dow Bldg., University of Michigan, 2300 Hayward St., Ann Arbor, MI 48109-1204; Eric P. Chason, Sandia National Labs., Dept. 1112, MS 1415, PO Box 5800, Albuquerque, NM 87185
Sponsored by: MSD Structures Committee, EMPMD Thin Films and Interfaces Committee Program Organizers: Eric P. Kvam, School of Materials Engineering, Purdue
Wednesday, PM February 12, 1997
Room:340C Location: Orlando Convention Center
Session Chair:E.P. Kvam, School of Materials Engineering, Purdue University, West Lafayette, IN 47907-1289
2:00 pm INVITED NEW INSIGHTS INTO THE STRESS DRIVEN 2D TO 3D TRANSITION: D.E. Jesson, Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6030 An understanding of the stress driven 2D to 3D transition is central to many key issues in materials science including the growth of planar but strained semiconductor layers and the fabrication of quantum dots. We will overview our current understanding of the transition and identify the conditions under which stress driven instabilities occur during film growth. Nucleation mecha-
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nisms of roughening compete with instabilities and this will be illustrated by annealing experiments which demonstrate the fonnation of rippled surface morphologies by cooperative nucleation events.
EXEMPLARY PRACTICE IN THE EXTRACTIVE METALLURGY OF COPPER
2:40 pm INVITED SPONTANEOUS COMPOSITION MODULATION IN SEMICONDUCTOR ALLOYS: Joanna Mirecki Millunchick, Sandia National Laboratory, Albuquerque, NM 87195-0601
Sponsored by: EPD Copper Nickel Cobalt Committee Program Organizers: J.E. Hoffman, Jan H. Reimers and Associates USA, Inc., P.O. Box 420545, Houston, TX 77242-0545 Wednesday, PM February 12, 1997
Lateral composition modulation (CM) has been observed to occur spontaneously in III-V semiconductors, producing quantum wires. CM is presumed to originate from surface undulations arising from compositional inhomogeneity, as well as lattice mismatch between the epilayer and the substrate. We observe CM in homogeneous alloys or in short period superlattices. Samples were characterized using cross-sectional transmission electron microscopy (XTEM), polarized photoluminescence spectroscopy (PPL), reflection difference spectroscopy (RDS), and magneto-luminescence (ML). For example, XTEM micrographs of InAs/GaAs superlattices show contrast due to CM only in the projection, with a period 150A. PL measurements show that emission is red-shifted and polarized with a ratio of up to 4. InAlAs buffer layers, on the other hand, have much higher polarization ratios (up to 10), indicating that these films may also be compositionally modulated. XTEM images of nominally lattice-matched InxGal-xAs I InxAll-xAs superlattice structures grown on InP (001) show that only the InAlAs layers exhibit contrast due to CM along the direction, in agreement with polarized PL results. The modulation period for such a structure deposited at Ts=475°C, for example, is 50A. Preliminary temperature-dependent PL and ML results for InAlAs epilayers show that the emission is independent ofT and B, suggesting carrier confinement due CM. These phenomena are under investigation in an effort to determine the dependence of the material system on CM. Finally, a model of the effect of CM on the band structure will be discussed. Supported by U.S. Department of Energy, OERIBES Division of Materials Science Grant No. DEAC02-83-CHl0093.
Room: 340D Location: Orlando Convention Center
Session Chairperson: J.E. Hoffman, Jan H. Reimers and Associates USA, Inc., P.O. Box 420545, Houston, TX 77242-0545
This session will present five papers describing the major unit processes of copper extractive metallurgy. The five unit processes are: smelting, converting, fue refining and casting, electrolytic copper refining, and copper solvent and electro winning. As set forth in the title of this seminar, the companies participating were chosen as exemplars of the finest practice in their particular area of copper extractive metallurgy. The goal of this session is to provide an accurate description and clear understanding of these unit processes. This session will provide a overall knowledge of the extractive metallurgy of copper, particularly useful to those outside the copper industry. 2:00pm EXEMPLARY PRACTICE IN THE FLASH SMELTING OF COPPER SMELTER CONCENTRATES: Gerald Roose, Phelps Dodge Mining Company, Hidalgo Smelter, P.O. Box 67 Playas, NM 88009 2:25pm EXEMPLARY PRACTICE IN THE PIERCE SMITH CONVERTING OF COPPER MATTE: Andreas Specht, NORDDEUTSCHE AFFINERIE Aktiengesellschaft Hamburg, Gennany
3:20pm STRUCTURAL STABILITY OF LOW TEMPERATURE GROWN InGaAs/GaAs HETEROSTRUCTURES: Chanro Park, C.G. Park, Dept. of Materials Science and Engr., Pohang University of Science and Technology, Pohang 790-784, Korea; C.D. Lee, S.K. Noh, Materials Evaluation Center, Korea Research Institute of Standards and Science, Taejon, 305-340, Korea
2:50pm EXEMPLARY PRACTICE IN THE FIRE REFINING AND ANODE CASTING OF COPPER: Allen Levert, Robert Matthews, INCO Ltd., Copper Cliff Copper Refinery, Copper Cliff, Ontario, Canada POM IND 3:15 pm BREAK
Microstructural evolution of the InGaAs/GaAs heterostructures grown by MBE at low temperatures (2oo-250°C) has been studied using double crystal x-ray diffraction and transmission electron microscopy. Dislocation fonnation was suppressed at low growth temperatures, and the layers sustained metastable structures which would undergo microstructural change at high temperatures. Misfit dislocations fonned at InGaAs/GaAs interfacial region during annealing relieved accumulated strain caused by lattice mismatch between the InGaAs and GaAs. Arsenic precipitates fonned during the annealing process also played an important role for strain relaxation by fonning misfit dislocations along matrix!As interface. Structural stability of the low temperature grown layers in discussed in tenns of the microstructural evolution observed at various growth and annealing temperatures.
3:30pm EXEMPLARY PRACTICE IN THE ELECTROLYTIC REFINING OF COPPER: Harry Tallert, ASARCO Amarillo Copper Refinery, Amarillo, Texas; Michael King, V. Ramachandran, ASARCO, Technical Services Center, Salt Lake City, UT 3:55pm EXEMPLARY PRACTICE IN THE SOLVENT EXTRACTIOIN AND ELECTROWINNING OF COPPER: Name to be supplied, MagmalBHP Copper Company, 200 Redington Rd., San Manuel, AZ 85631
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minimum strain rate regions and tertiary creep were investigated. Creep tests conducted at 550°C, 550°C and 700°C were stopped at different stages and specimens were prepared for TEM observations. No evidence of the subgrain formation has been found in any of the creep tests. Faulted dipoles and superdislocations, as well as a few ordinary dislocations, were present in the microstructure of the early stage of the creep tests. At longer creep times, faulted dipoles were annihilated and superdislocations were found to fonn "roof' like barriers. TEM observations of faulted dipoles and superdislocations were correlated, where appropriate, with computer simulations. The density and the degree of bowing of the "cusps" on ordinary dislocations increased dramatically with increasing creep strain. The configuration of the "cusps" fonned on the ordinary dislocations were studied with weak-beam TEM and were compared to those found in the yielding and the prestraining studies of the same alloy.
FUNDAMENTALS OF GAMMA TITANIUM ALUMINIDES VI: Microstructure-Property Relationships-Creep and Environmental Effects Sponsored by: MSD Flow & Fracture and Phase Transformations Committees Program Organizers: Kwai S. Chan, Southwest Research Institute, San Antonio, TX 78228-0510; Vijay K. Vasudevan, Dept. of Materials Science & Engineering, University of Cincinnati, Cincinnati, OH 45221-0012;Young-Won Kim, UES, Inc., Day1on, OH 45432-1894 Wednesday, PM February 12, 1997
Room: 330E Location: Orlando Convention
3:10pm MICROSTRUCTURE EVOLUTION AND CREEP DEFORMATION OF A Mo-CONTAINING NEAR-GAMMA ALLOY : Eric Ott, Tresa Pollack, Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213
Session Chairpersons: Patrick L. Martin, Rockwell International Science Center, 1049 Camino Dos Rios, Thousand Oaks, CA 91360; Kevin J. Hemker, Dept. of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218-2686
1:55 pm OPENING REMARKS
The addition of Mo in near-gamma alloys promotes the fonnation of the beta phase. The presence of the beta phase stabilized by Mo as well as other alloy additions including Nb and Cr has been shown to result in good hot working characteristics. Microstructural evolution of a Ti-46.4AI-2Nb-2Cr-0.8Mo fine grained wrought alloy during annealing and subsequent heat treatment will be reported with a specific emphasis on the effects of the betaIB2 phases on the development of gamma and lamellar microstructures. Results of creep testing and subsequent microscopy of near-gamma and duplex microstructures will also be discussed and compared to that of a similar Ti-48AI-2Nb2Cr type alloy containing no Mo.
2:00 pm INVITED REDUCTION OF PRIMARY CREEP IN TiAI ALLOYS BY PRESTRAINING: Jian N. Wang, L.M. Hsiung, T.G. Nieh, Lawrence Livennore National Laboratory, L-370, P.O. Box 808, Livennore, CA 945519900 In some engineering applications, TIAI components are limited to undergo less than 0.3-0.5% creep distortion. However, existing fully lamellar TiAI alloys defonn to this strain within a short period of time during primary creep. Thus, the reduction of primary creep has become a key issue. Present experiments show that this creep can be significantly reduced by prestraining. A sample pres trained at a high stress could undergo no forward defonnation at a subsequent low stress even after a long period of time. Microstructural examination indicates that the motion of misfit dislocations along interfacial and thennal twin boundaries is the dominant mode of defonnation at low stress. The mobility of these dislocations after prestraining and the physical origin of this effect will be discussed.
3:30 pm BREAK 3:50pm CREEP DEFORMATION OF NEARIFULLY LAMELLAR Ti-48AIBASED ALLOYS: G.B. Viswanathan, V. K. Vasudevan, Dept. of Mat. Sci. &Eng., Univ. of Cincinnati, Cincinnati, OH 45221
Cast gamma titanium aluminides are gaining acceptance as potential replacements for superalloy and steel components in many applications. One particular alloy with W, Mo and Si additions has shown exceptional primary creep resistance. Quantitative microscopic comparisons were made between microstructures in the grip sections and the defonned gage section in creep specimens defonned to 0.5% strain, using optical, SEM and TEM techniques. The lamellar spacing in lamellar grains systematically decreased after creep defonnation. Precipitates containing refractory elements nucleated and grew at a faster rate in the defonned part of the specimen, as compared to the defonned region, and the precipitates were generally smaller and more homogeneously nucleated. Precipitates have been identified to be silicides or beta phase. These observations indicate that strain assisted nucleation of precipitates accounts for much of the excellent creep resistance.
In this study, the creep properties of the binary Ti-48AI and quarternary Ti48AI-2Cr-2Nb alloys are investigated for the near and fully lamellar microstrutures in the temperature range of 700-815°C and stress of 103-240 MPa. The creep behavior of all the tested microstructures is best described by the power law creep. Activation energy (Q) between 350-370 KJ/mole and stress exponent (n) in the range of 5.0-8.0 was obtained for the binary Ti48AI alloy. The corresponding values for the Ti-48AI-2Cr-2Nb alloy were -315 KJ/mole and -5.0. The effect of grain size and the lamellar spacing on the creep behavior is discussed. Defect analysis through weak beam dark field imaging was carried out to elucidate the dislocation mechanisms in the crept samples. Observations of the crept samples with the fully lamellar structure in the binary alloy indicate that both 112<110] and 112<112] dislocations are active, that the deformation is highly anisotropic and that the lamellar interfaces obstruct slip (depending on the orientation). The combination of low creep rates with a high stress exponent for the fully lamellar structures is thought to be caused by the combined effect of anisotropic defonnation and lamellar boundaries obstructing slip; the dislocations that are piled up at the interfaces overcome these obstacles by local climb, which is reflected in the Q values near that of self-diffusion of Ti in TiAI. The fonnation of substructures within the y laths and the lamellar interface structures before and after creep will be discussed.
2:50pm EVOLUTION OF MICROSTRUCTURE DURING THE ELEVATED TEMPERATURE CREEP OF SINGLE-PHASE GAMMA Ti47Als,Mnz ALLOY: Min Lu, Kevin J. Hemker, Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, MD 21218
4:10pm DEVELOPMENT AND EVALUATION OF AN OXIDATION-RESISTANT COATING ALLOY FOR GAMMA TITANIUM ALUMINIDES: M.P. Brady, W.J. Brindley, J.L. Smialek, MS 106-1, NASA Lewis, Cleveland, OH 44135
Mechanical experiments have shown that single-phase gamma TiAI does not exhibit steady-state creep. Instead, the microstructure evolves along the creep curves. To investigate microstructure/property relations, constant stress creep tests on single-phase polycrystalline gamma Ti47AI51Mn2 were conducted at temperatures below and above the peak temperature (600°C). Primary creep,
A two-phase y (TiAl) + Laves (Ti[Cr,A!],) oxidation-resistant coating alloy, Ti-51.25AI-12.25Cr at. %, has been developed for the y+ IX, class of titanium aluminides. The composition of the coating alloy was selected so that the microstructure consists of the g phase, and a minor volume fraction of the oxidation-resistant Laves phase. By basing the microstructure on the y phase,
2:30pm CHANGES IN MICROSTRUCTURE DURING PRIMARY CREEP IN A Ti-47AI-2Nb-1Mn-0.5W-0.5Mo-0.2Si ALLOY: D.Y. Sea, T.R. Bieler, Department of Materials Science and Mechanics, Michigan State University, East Lansing, MI 48824-1226; D.E. Larsen, Howmet Corporation, Whitehall, MI49461
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the mechanical properties and substrate compatibility are optimized. The volume fraction of the Laves phase is kept to a minimum because it is extremely brittle. The Ti-51.25AI-12.25Cr coating alloy was applied to the y+ Uz alloy, Ti- 48AI-2Cr-2Nb, by low pressure plasma spray (LPPS). Oxidation tests at 800°C and 1000°C in air indicated that the coating successfully protected the substrate from oxidation. The oxidation behavior and mechanical properties of the coating alloy will be discussed.
of oxygen between oxide and substrate alloy, and alloy grain size were determined as a function of temperature and oxygen pressure. The results for the two alloys are discussed and compared with one another and with those from similar studies on unalloyed V reported in the literature. Work supported by the U.S. Department of Energy, Office of Fusion Energy Research, under contract W-31-109-Eng-38. 2:20pm OXIDATION BEHAVIOR OF AI3Ti INTERMETALLICS: R.G. Reddy, X. Wen, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487
4:30pm VERY LONG TERM OXIDATION OF Ti-48AI-2Cr-2Nb AT 704°C IN AIR: I.E. £oeci, M.P. Brady, R.A. MacKay, 1.W. Smith; MSI06-5, NASA Lewis, Cleveland, OH 44135
The oxidation kinetics of AI, Ti intermetallics have been studied at the temperature range of 1123K to 1273K in pure dry oxygen. The oxygen diffusion rates were investigated using TGA method. Parabolic rate constants were calculated and compared with other research results. The oxidation scales were analyzed using SEM, EDS and X-ray diffraction. A continuous A1203 scales with a little Ti02 (rutile) were formed on the intermetallic surface. The AI,Ti intermetallic exhibited excellent oxidation resistance among the Ti-AI base intermetallics.
The alloy Ti-48AI-2Cr-2Nb was exposed from 500 h to 9000 h at 704 C in air. A complex, mixed aluminaltitania scale, rather than a protective alumina scale, was formed. After 9000 h, this scale was approximately 15 microns thick. A continuous Ti-rich nitride layer was formed at the alloy/scale interface. The alloy ahead of this nitride layer was depleted in Ti and enriched in AI. Comparisons with the oxidation behavior of binary TiAI alloys, and implications of the scale microstructure for mechanical properties will be discussed. 4:50pm RECENT DEVELOPMENTS ON THE OXIDATION OF TiAI: R. Wheeler, R. BaneIjee, H.L. Fraser, Department of Mater. Sci. and Eng., Ohio State University, Columbus, OH 43210
2:40pm SUPERHEATING BEHAVIOR OF NiAI: N. Kullcarni, Dept. of Materials Science & Eng., University of Florida, 245 Rhines Hall, Gainesville, FI32611; K. T. Hong, Division of Metals, Korea Inst. of Science & Tech (KIST), 39-1 Hawolkog-dong, Sungbook-Gu, Seoul, Korea 136-791
The high level of Al in TiAI based alloys does not always relate to slow oxidation kinetics. While protective alumina scales are formed during high temperature exposures in an oxygen environment, mixed AIP/Ti02 scales are formed when similar tests are conducted in air. In this latter case, the surface corrosion products form a complex layered structure which governs oxidation rates. In a Ti-48AI-2Cr (at. %) alloy oxidized in air at 800°C for 1 hour, two distinct layered microstructures are observed. One is composed of an Al depleted underlayer and a mixed AI,o/Ti0 2 outerlayer. The other is composed of the same depleted layer with a multicomponent, multilayered outerscale. This second microstructure is characteristic of a nitrogen effect found to be associated with increased oxidation kinetics. Detailed TEM analyses has been conducted to identify the reaction products present in the scale. The deduced reaction paths suggest a rate behavior based on both interfacial reactions and the inward and outward anion and cation diffusion.
The intermetallic compound NiAI, when processed in a microgravity environment under electromagnetic levitation, exhibited a unique superheating effect up to 65 degrees over the melting point. This superheating behavior appeared to be related to the high supercoolings (200-250 degrees) experienced by molten NiAI samples that rapidly solidified in the rnicrogravity levitation environment. The superheating observed appeared to be permanent and reduced asymmetrically for compositions that deviated from stoichiometry. On reaching the maximum or critical superheating temperature, an anomalous transformation occurred that caused the temperature of the sample to drop to its melting point, after which melting commenced. It appears that this transformation is an order-disorder type, that is explicitly associated with the superheating behavior in NiAI. 3:00pm A STUDY OF POTENIAL EUTECTIC BRAZE ALLOYS IN THE AuAg-Ge TERNARY SYSTEM: P.T. Vianco, J.J. Stephens, C.A. Walker, Sandia National Laboratories, Albuquerque, NM 87185-0367
5:10pm CLOSING REMARKS: Kwai S. Chan, Southwest Research Institute, San Antonio, TX 78228-0510
Despite the need for low vapor pressure alloys with brazing temperatures in the 400-600°C range, there are in fact very few commercially available alloys to use in this range. This study was motivated by the need to develop a brazing process with a maximum allowable brazing temperature of 500°C. A survey of ternary phase diagrams, combined with previous experience with the binary 88wt.% Au-12 Ge alloy, led us to select the Au-Ag-Ge ternary system for further study. We have found that the 77.32 wt.% Au-12.62 Ag10.06 Ge composition is a eutectic alloy with a eutectic temperature of -447°C. Hermetic seals to metallized alumina tensile buttons (ASTM FI9 design) have been obtained with this system. This talk will present results braze joints strength results, along with a discussion of the as-solidified microstructure of this alloy. This work conducted at Sandia National Laboratories, supported by U.S. Dept. of Energy under contract number DE-AC04-94AL85000.
GENERAL METALLURGY TMS General Abstract Session Wednesday, PM February 12, 1997
Room: 231C Location: Orlando Convention Center
Session Chairperson: J.J. Stephens, Sandia National Laboratories, Albuquerque, NM 87185
2:00pm EFFECTS OF TEMPERATURE AND OXYGEN PRESSURE ON OXIDATION KINETICS OF V-4wt. % Cr-4wt% Ti AND V-swt. % Ti ALLOYS: M. Uz, Chemical Engineering Department, Lafayette College, Easton, PA 18042; K. Natesan, Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439; N. Barbosa 1II, Chemical Engineering Department, Lafayette College, Easton, PA 18042
3:20 pm BREAK 3:30pm THERMAL AND PROCESS MODELING OF MICROFIBROUS MANUFACTURING IN A SINTERING FURNACE: I.M. Shire, I.M. Khodadadi, Mechanical Engineering Department, 8.1. Tatarchuck, Chemical Engineering Dept., Auburn University, Auburn, AL 36849
We conducted comparative investigation to determine the effects of temperature and oxygen pressure on the oxidation behavior and microstructure of V4wt.% Cr-4wt.% Ti and V-5wt.% Cr-5wt.% Ti Alloys. The samples were cut from I-mm-thick cold-rolled sheet stock and annealed at 1050°C for 1 h before their use in oxidation studies. The oxidation experiments were performed at oxygen pressures of 760, 0.1, 5 x 1(}4, and 5 x 1(}6torr and at temperatures of ",350 to 700°C. Oxidation models, oxide type and thickness, partitioning
Mathematical modeling and numerical simulation of the thermal field for the operation of a continuous belt hydrogen furnace used for sintering applications of micro fibrous materials are presented. Particular emphasis is placed on metallic fibers being sintered into a web-like matrix. Utilizing thermal energy balance and simplified heat transfer equations, the mathematical model
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is capable of predicting the instantaneous temperature of products as they pass through the furnace. The manufacturing process is optimized with respect to the belt speed, furnace zone temperature setting and sintering material configuration.
EFFECT OF SEM TILTING ON MEAN INTERLAMELLAR SPACING CALCULATIONS OF PEARLITE IN EUTECTOID STEEL: Sedat Ozbilen, Gazi Univ. Fac. Tech. Educ. Metal Dept., Teknikokullar, Ankara, Turkey
3:50pm Eutectoid steel with a composition ofO.59%C-0.69%Mn-1.19%Si-0.022%P and 0.061%S (in wt%) was cast before austenitisation at 850°C. Samples were furnace cooled to obtain coarse pearlitic mean interlamellar spacing of 0.57~m measured from SEM micrographs of samples. To observe the effect of SEM tilting on "mis" of pearlite samples of Ix lxO.4cm were annealed at 700°C for 115 hr. SEM micrographs with and without 30° tilt on samples were taken. Results of metallographic investigation will be presented.
DIFFUSION IN SILICIDES OF Mo AND W: P.C. Tortorici, M.A. Dayananda, Purdue University, School of Materials Engineering, 1289 MSEE Building, West Lafayette, IN 47907-1289 Diffusion studies were carried out with Si in contact with Mo and W at selected temperatures between 900°C and 1350°C for the formation and growth of silicides of Mo and W. Interdiffusion between MoSi, and Mo and between MoSi, and W was also studied for the development of silicide layers, such as MO,Si3, M03Si, (Mo,W),Si 3, W,Si 3 and nonplanar interface morphologies. Integrated interdiffusion coefficients calculated for the various silicide layers from concentration profiles are presented. The relative diffusion behavior of Si, Mo and W in selected silicide layers will be discussed in the light of diffusion structures and marker motion.
INNOVATIONS IN ALUMINUM I Sponsored by: LMD Aluminum Committee Program Organizer: Robin Conger, Pacific Northwest National Laboratory, P.O. Box 999, K8-11, Richland, WA 99352
4:10pm FOCUSED ION BEAM MILLING AND MICROMANIPULATION FOR CROSS-SECTION TEM SPECIMEN PREPARATION: L.A. Giannuzzi, Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd., Orlando, FL 32816-2450; S.R. Brown, Kirk Resources, 9333 S. John Young Parkway, Orlando, FL 32819; R.B. Irwin, EA. Stevie, Lucent Technologies, 9333 S. John Young Parkway, Orlando, FL 32819
Wednesday, PM February 12, 1997
Room: 232B Location: Orlando Convention Center
Session Chairperson: Larry Boxall, Fluor Daniel/C1 071, 100 Fluor Daniel Drive, Greenville, SC 29607-2762
2:00pm
A technique for cross-section transmission electron microscopy (TEM) sample preparation of mutt-layered and difficult materials as described. A focused ion beam (FIB) device is used to slice an electron transparent specimen from an area of interest. Micromanipulation procedures are then used to transport the electron transparent specimen from the bulk sample to a formvar/carbon coated copper grid for subsequent TEM analysis. The versatility of this technique is demonstrated by presenting cross-sectioned TEM specimens from a wide range of materials. TEM specimens that have been produced with the FIB method include a multi-layered thin film electronic device, a metallic diffusion couple, and a ceramic fiber.
CLOSED-LOOP NITROGEN-CHLORINE DEGASSINGIFLUXING OF LIQUID ALUMINUM ALLOYS: L.S. Fan, RobertA. Rapp, Ohio State University, Department of Material Science and Engineering, 116 W. 19th Ave., Columbus, OH 43210 The need to degas liquid aluminum alloys to reduce dissolved hydrogen prior to solidification to form any product is indigenous to all aluminum processing plants. Likewise, to produce aluminum sheet and some other products, dissolved sodium and calcium must be fluxed by reaction with chlorine. Today, the combined degassing and fluxing is often achieved by the bubbling of a nitrogen-chlorine gas mixture into the melt, with release of the product HCI and unreacted Cl, into the environment. This work introduces a proprietary concept to accomplish the degassing/fluxing of aluminum melts by the usual nitrogen-chlorine gas mixture, but with recirculation of the chlorine within a closed-loop system so that it is not released to the environment. Reaction of HCI and CI, from the degassing product gases with copper oxide pellets in a fixed bed lead to their conversion to copper chlorides, and the H,O(y) product is safely vented to the environment. Ambient air is used to regenerate the reactant copper oxide from the product copper chloride.
4:30pm IMPROVEMENT OF COATING ADHERENCE OF HOT-DIP GALVANIZED SHEET STEELS CONTAINING SILICON: fong-Sang Kim, Jin-Hwan Chung, Kwangyang Research Labs., Pohang Iron and Steel Company, P.O. Box 22 Suncheon, Korea The effects of silicon in steels on the coating adherence of hot-dip galvanized steel sheets have been investigated to reduce the weight of automobile body. The presence of a stable silicon oxide formed on the steel surface has shown to be very detrimental to proper wetting by liquid zinc. A critical silicon concentration depended on the operating conditions such as mechanical pretreatments, furnace conditions and alloying composition of zinc bath.
2:30pm DEGASSING LIQUID ALUMINUM ALLOYS BY ARGON IN CLOSED CIRCUIT: RobertA. Rapp, L. S. Fan, Ohio State University, Department of Material Science and Engineering, 116 W. 19th Ave., Columbus, OH 43210
4:50pm OXIDATION AND DECARBURISATIOIN KINETICS OF AN EUTECTOlD STEEL DURING STATIC SPHEROIDISATION: Sedat Ozbilen, Gazi Univ. Fac. Tech. Educ. Metal Dept., Teknikokullar, Ankara, Turkey
The large reduction in the solubility of dissolved hydrogen in aluminum as it is solidified to form ingots, strip, sheet or cast products necessitates that the liquid metal is degassed prior to casting. Pure argon is frequently injected into the liquid alloy through a submerged lance or bubbler, so that dissolved hydrogen enters the argon bubble prior to discharge into the environment. This work introduces a proprietary concept to achieve the same argon degassing of liquid aluminum alloys, with recirculation of the argon in a closed loop such that the cost of the argon is saved. In practice, the hydrogen entrained by the argon from the liquid alloy would be oxidized to form H,O(y) by reaction with a fixed bed of copper oxide pellets and the H,O(y) product would be extracted by a desiccator bed. When the reactant bed of copper oxide is mostly reduced to copper and the desiccator approaches saturation, a relay is activated, causing a redirection of the gas flow which replaces the spent reactants with newly regenerated ones.
Eutoid steel with a composition ofO.59%C-0.69%Mn-I.19%Si-0.022%P and 0.061 %S (in wt%) was austenitised at 805°C after casting. Samples were furnace and air cooled to obtain fine (0.26~m) and coarse (0.57~m) mean interlamellar spacing of pearlite. Samples of Ix 10.4cm was annealed at 600°C and 700°C for varying times up to 2200 hr. x-ray diffraction, SEM investigation, wet chemical analysis and theoretical erf calculations were carried out to observe and measure the response of the eutectoid steel to oxidation and decarburisation.
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2:50pm ENERGY AND OTHER COST SAVINGS THROUGH NOVEL, STATIC DEGASSING IN RECYCLED ALUMINUM PRODUCTION: DavidA. Larsen, Blasch Precision Ceramics, Inc., 580 Broadway, Albany, NY 12204 A novel method of producing ceramic degassing components through freezecasting and injection molding is employed to manufacture components used in the production of recycled aluminum metal, where contaminant levels are higher than normal, resulting in lower than normal grade metals. Recycled aluminum degassing operations based on today's standard practice are inadequate for the task, requiring either costly rotary components which require high maintenance, and operating costs, or large pore ceramic porous plugs which fail to deliver the necessary fine gas bubble pattern reliably and continually.
3:10 pm BREAK
INTERNATIONAL SYMPOSIUM ON RHENIUM AND RHENIUM ALLOYS VI: Component Design and Fabrication of Rhenium and Its Alloys (Part II) Sponsored by: SMD Refractory Metals Committee and MDMD Powder Materials Committee Program Organizer: Dr. Boris D. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036 Wednesday, PM February 12, 1997
Room: 240D Location: Orlando Convention Center
Session Chairpersons: Jan-C. Carlen, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036; Dr. R.H. Tuffias, Ultramet, 12173 Montague St., Pacoima, CA 91331
3:30pm EVALUATION OF ANEWMATERIALFORHALL-HEROULT CELL CATHODES: Thomas l. Mroz, Advanced Refractory Technologies, Inc., 699 Hertel Avenue, Buffalo, NY 14207
2:00pm EVALUATION OF A RHENIUM COATING ON A MOLYBDENUM SUBSTRATE: Amber M. Dalley, C. Bagnall, Concurrent Technologies Corporation, 1450 Scalp Avenue, Johnstown, PA 15904; R.W. Buckman, Jr., Refractory Metals Technology, Pittsburgh, PA 15236
A new, non-oxide material has recently been identified which exhibits electrical resistance 2 orders of magnitude less than graphite, and which can be formed by reaction hot pressing or sintering at relatively low temperatures. Additionally, this material is easily machined, and exhibits good oxidation resistance and excellent thermal shock resistance. It appears to be a good candidate for Hall cell cathode applications. Additionally, there appears to be an opportunity to inexpensively surface treat this material to obtain TiB z integral coatings. We will evaluate the corrosion resistance of this material with and without the TiB z coating and further evaluate the parameters required to produce the TiB z coating.
The high melting point and high rate-of work-hardening properties of rhenium make it an ideal choice for high temperature wear surface applications. The expense of rhenium makes it more cost effective as a coating rather than as the monolithic metal. This paper reports on preliminary studies of a chemical vapor deposited coating of rhenium on a molybdenum substrate. Key issues studied include as-deposited adherence and metallurgical bond integrity after various thermo-mechanical treatments. Coating quality and compatibility with the substrate after thermal cycling are examined.
3:50pm
2:20pm
DISPOSAL OF HALL-HEROULT CELL POT-LINING: l.R. Divine, ChemMet, Ltd., P.O. Box 4068, West Richland, WA 99353-2309 The proposed disposal process provides an energy efficient mechanism for recovering salts from the pot-lining and disposing of the carbonaceous liner itself. The proposed method is to grind the spent pot-liner into small particles and then oxidize them. The method which appears most likely to be successful is to grind to about 1 mm diameter, heat to about 1300 K in an "inert" atmosphere of CO z, and then react with steam. The resulting mixture of CO and Hz can be used as fuel in a boiler to generate steam, preheat the spent potliner, or provide co-generation for feeding electrical power back into the grid or into the aluminum process.
4:10pm AN ALUMINA CONCENTRATION SENSOR: lames Oxley, Oxley Research Inc., 25 Science Park, New Haven, CT 06511 This work concerns development of a novel electroanalytical sensor to monitor the depletion in alumina concentration which occurs during electrowinning of aluminum from molten cryolite-alumina baths. The concept relies on the use of an inert indicator electrode which responds directly to variations in dissolved alumina concentration. The electrical signal thus produced can be used in a control algorithm to enable the automatic feeding of alumina to the bath, thereby avoiding the occurrence of "anode effect".
RHENIUM AND IRIDIUM: Evan K. Ohriner, Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 378316083 Rhenium is used together with the metal iridium in a number of applications. Iridium has been used as coating for rhenium rocket thrusters and as an oxidation-resistant coating in a number of other applications. The high strength of rhenium at elevated temperature is combined with the oxidation resistance and high melting point of iridium. The use of the two metals together is advantageous due to the absence of any stable intermediate compounds. Coating life and properties are effected by solubility and diffusion rates. Rhenium and iridium alloying additions both improve the ductility of tungsten. The high solubility of rhenium in iridium is also being taken advantage of to produce iridium-based materials with a reduced electron work function. The uses of rhenium in conjunction with iridium are discussed. Managed by Lockheed Martin Energy Research under contract DE-AC05-960R22464 with the U.S. Department of Energy.
2:40pm DEVELOPMENT OF THE PARAMETERS OF THE PROCESS OF MANUFACTURING COMPLEX SHAPE PARTS FROM RHENIUM POWDER: Eugene P. Kratt, Victor N. Samarov, Laboratory of New Technologies, PO Box 31, 103001 Moscow, Russia,; Boris D. Bryskin, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036 The research was aimed at developing the parameters of the process of manufacturing hollow parts from rhenium and rhenium alloy powders. With this purpose, the hot isostatic pressing technique was proposed. Tool design and choice of material for the tool were the main problems of the research. On the basis of the fulfilled experiments a rational scheme of manufacturing hollow complex shape parts with minimal allowances was developed. the parameters of this scheme are made the basis of the technology of manufacturing rocket engine nozzle type parts.
208 .,• • • • • • •· • •I ••• • •_.I...I •• IIII@lliiil..... lIlIl"-I".'
3:00pm PREPARATION OF TEFLON PIPES WITH METALLIZED LAYER: E.G. Rakov, D. Mendeleyev University of Chemical Technology of Russia, Miusskaya Sq. 9, Moscow 125047, Russia
4:20pm PRODUCTION OF RHENIUM-POWDER WITH A JET MILL AND ITS INCORPORATION IN RADIOACTIVE MICROSPHERES FOR THE TREATMENT OF LIVER TUMORS: Urs Hafeli, Gayle Pauer, Roger Macklis, The Cleveland Clinic Foundation, Desk T28, 9500 Euclid Ave., Cleveland, OH 44195; Randall German, Penn State University, 118 Research Building West, University Park, PA 16802-6809
The method of deposition of thin rhenium layers on inner wall of teflon pipes (tubes) by means of filling the pipes by volatile rhenium compound and subsequent chemical reduction of this compound inside teflon pores was developed. The method allows to diminish permeability of teflon for gases or liquids and to change its electric properties: the inner layer becomes electroconductive. Such teflon pipes and details are necessary for neutralization of static electric charges in some devices. The depth of metallized layer, as it was shown by microscopic examination of pipe cross sections, did not exceed some tenth of millimeter. The method allows to deposit -metallized layers of definite configuration.
Metallic rhenium powder of 325 mesh is readily available. Well characterized powder of micrometer size, however, is less easy to obtain. In this presentation, we describe how we prepared rhenium powder with an average particle size of 1-2 ).tm, starting from 325 mesh material and using a jet mill. The particle size distribution was confirmed by light and scanning electron microscopy, and laser diffraction. The change in density and surface characteristics (porosity) was also analyzed. Biodegradable poly (lactic acid) microspheres were prepared, by a solvent evaporation method, from the resulting rhenium particles and were neutron activated in a nuclear reactor to directly yield 1861188Re-microspheres, useful for the treatment of liver tumors. Biodistribution data in rats as well as first treatment results of Novikoff tumors are presented.
3:20 pm BREAK
INTERNATIONAL SYMPOSIUM ON RHENIUM AND RHENIUM ALLOYS VII: Applications for Radioactive Rhenium
4:40pm RADIOIMMUNOTHERAPYWITH RHENIUM-186 AND RHENIUM188: Alan R. Fritzberg, Fu-Min Su, NeoRx Corporation, 410 W. Harrison, Seattle, WA 98119
Sponsored by: SMD Refractory Metals Committee and MDMD Powder Materials Committee Program Organizer: Dr. Boris D. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036 Wednesday, PM February 12, 1997
The radioisotopes of rhenium, Re-186 and Re-188, have physical properties that make them attractive for radiotherapy via antibody mediated targeting. Rhenium186 has a half life of 3.78 days, maximum beta energy of 1.07 MeV and imageable gamma rays. Rhenium-188 has a half life of 17 hours, maximum beta energy of 2.12 MeV and irnageable gamma rays. Rhenium-I 86-with its longer half life is appropriately matched with the larger antibody forms, IgG of 150 kD molecular weight and its F(ab')2 fragment of 100 kD ·size. Rhenium-I 88 with its shorter half life may be preferred in instances of rapid tumor uptake and shorter tumor retention. N ,S amide thiolate chelating agents such as mercaptoacetylglycylglycyl-y-aminobutyrate have been developed for the attachment of the rhenium radioisotopes to antibodies. With this agent, over 150 patients with solid tumors have been treated with up to 550 mCi of Re-186. Several have had partial responses (> 50% decrease in tumor size).
Room: 240D Location: Orlando Convention Center
Session Chairperson: Dr. Urs O. Hafeli, Project Scientist, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195
3:40pm DEVELOPMENT OF A METALLIC RADIOACTIVE RHENIUM SOURCE FOR THE TREATMENT OF RESTENOSIS AFTER ANGIOPLASTY: Urs Hafeli, Eric Lee, Jay Ciezki, Roger Macklis, The Cleveland Clinic Foundation, Desk T28, 9500 Euclid Ave., Cleveland, OH 44195
INTERNATIONAL SYMPOSIUM ON RHENIUM AND RHENIUM ALLOYS VIII: ProceSSing, Structure and Properties of Rhenium and its Alloys (Part II)
Radioactive Rhenium sources can be prepared in a nuclear reactor by bombarding the non-radioactive metal with neutrons. In a n;y-reaction, the two ~ emitters 186Re and lssRe are produced with high yield. One application of thus prepared radioactive Rhenium wires is the prevention and treatment of restenosis after balloon angioplasty. For this brachytherapeutic application, the source must be very stable, enclosed and safe to handle. The necessary encapsulation of the radioactive source was done by plasma coating with a 240 nm layer of titanium, as confirmed by scanning electron microscopy. This resulted in a highly radiochemically stable source. The response of endothelium and smooth muscle cells to a radioactive Rhenium-wire and its dosimetry was determined in an in vitro cell model. Our results confirmed that radioactive sources made from 186Re and, even more so, 188Re, are excellent candidates for restenosis inhibition because of their narrow treatment range, sharp dose gradient, inexpensive preparation, excellent stability, easy shielding and conveniently short treatment times.
Sponsored by: SMD Refractory Metals Committee and MDMD Powder Materials Committee Program Organizer: Dr. Boris D. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036 Wednesday, PM February 12, 1997
Room: 232C Location: Orlando Convention Center
Session Chairpersons: Dr. Evan K. Ohriner, Metals and Ceramics Division, Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, TN 37831-6083; Forrest Hall, Hoskins, 10776 Hall Road, P.O. Box 218, Hamburg, MI 48139-0218
4:00pm PRODUCTION OF RHENIUM-186 AND RHENIUM-188 AT ORNL HFIR: Saed Mirzadeh, A.L. Beets, EE (Russ) Knapp, Nuclear Medicine Group, Health Science Research Division, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN 37831-6229
2:00pm METALLO GRAPHIC TECHNIQUE FOR INCREASED GRAIN BOUNDARY DELINEATION OF RHENIUM ALLOYS: Mitchell A. Jacobs, Jozef Fedko, Metallurgical Services Inc., Maywood, IL 60153 Current metallographic preparation techniques for rhenium alloys have been based on the etch and back polish technique due to the soft nature of the rhenium alloys. To date the etch and back polish technique has adequately removed the flowed rhenium material to reveal the microstructure. Recent technology has allowed new polishing media to provide better removal of the flowed material. The resulting microstructure exhibits two dimensional relief in a slightly overetched condition. The significantly increased grain boundary delineation permits better review of the grain size.
Both 186Re and 188Re are of interest for various therapeutic applications. In this presentation, we will discuss the development of targets and chemical processing for large scale production of 186Re, 188Re and 188W (the parent of 188Re). These radioisotopes are currently produced at the hydraulic tube irradiation facility (HT) of High Flux Isotope Reactor (HFIR). In addition, the experimental and theoretical production yields of 186Re, 188Re and 188W will be presented. Supported by OHER DOE, contract DE-AC05-860R22464 with Lockheed Martin Energy Research Corp.
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2:20pm ION· IMPLANTATION DOPED RHENIUM AND REFRACTORY METALS: G. Welsch, P.T. Szozdowski, R.M. Collins, Materials Science and Engineering, Case Western Reserve University, 514 White Bldg., Cleveland, OH 44106-7204; KT. Kim, Research Institute ofIndustrial Science and Technology, P.O. Box 135, Pohang, 790-600, Korea
rhenium decreased gradually with increasing temperature while the elongation decreased drastically (from 20% to 5%) as the temperature increased from 1100 to 1200°C. The elongation remained below 5% at temperatures up to 2000°C. Tensile tests were also performed on rhenium -1% tungsten and rhenium-2% iridium. Both alloys were stronger than pure rhenium with the rhenium- 1% tungsten alloy being the strongest. Limited creep and creep rupture tests were performed in the 1025 to 1225°C range. The creep tests, with relatively low stresses, indicated a very low stress exponent of 1.3.
Rhenium and other refractory metals in various product forms can be doped with potassium to stabilize an overlapping recrystallized grain structure for high temperature creep strength. Doping has been performed by ion-implantation into the surface layers of flat sheets. During fabrication of pressurebonded or roll-bonded multi-layer composites the dopant was incorporated along strategically located internal planes. The dopant is arranged in planar arrays of fine bubbles which play the role of fenceposts as they anchor grain boundaries during recrystallization and grain growth. Doped layer composites can be heated to over 2000°C and maintain an overlapping "brick layer" grain structure whereas undoped layer composites develop grains and grain boundaries that transverse the entire width of the composite. Acknowledgment: The research was funded by The National Science Foundation.
4:00pm MICROSTRUCTURE CHARACTERISTICS OF Mo·Re ALLOYS SIN· TERED AT MEDIUM TEMPERATURES: Rodolfo L. Mannheim, Jorge L. Garin, Department of Metallurgical Engineering, Universidad de Santiago de Chile, Casilla 10233, Santiago, Chile Mixtures of molybdenum and rhenium powders with particle size distribution bearing 2~lm average, were prepared in a planetary mill to yield the Mo25%Re and M050%Re compositions. Tablets were then obtained by compaction at various pressures in the range of 300 to 800 MPa. The pieces were subject to sintering at temperatures of 1400 to 1700°C, under protecting atmosphere of Ar-IO%H, to avoid oxidation of the component metals. The solution of rhenium in the molybdenum matrix was followed by means of Xray diffraction: it was found that at all sintering temperatures rhenium was totally dissolved in the Mo-25%Re, while small amounts of an intermediate phase were detected in the case of the Mo-50%Re alloy, in good agreement with the phase diagram. The densification of the sintered parts increased with temperature and compaction pressure up to values around 90%. The microstructure of the specimens was observed by means of scanning electron microscopy, while the homogeneity of the sintered alloys was corroborated by EDX line-scan analysis. The microstructure showed well defined equi-axed grains with some microporosity distributed across the surface. A few initial tests on cold rolling of the resulting specimens were conducted with very promising results; in fact, owing to the fine particle size of the powders, the sintering temperature can be lower than those normally utilized in the refractory metals industry.
2:40pm THE INFLUENCE OF ROLLING DIRECTION AND ANNEALING ON THE TEXTURE OF RHENIUM SHEETS: Boris D. Bryskin , Jan-C. Carlen, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036; K. Peter D. Lagerlof, Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106; Neil Goldfine, JENTEK Sensors, Inc., Boston, MA 02135 The hardness, density, dimensional change and texturing of rolled rhenium sheet was studied as a function of rolling direction and total strain. Sheets of rhenium were produced from rhenium metal powder by pressing, presintering and sintering, followed by cold rolling and annealing steps. Four different samples were investigated; (i) uni-directiona11y rolled sheet fed in a single rolling direction (sample I-I), (ii) uni-directionally rolled sheet fed in opposing rolling directions (sample 1-2), (iii) cross-directionally rolled sheet fed in opposing rolling directions (sample 2-1), and (iv) cross-directionally rolled sheet fed in opposing rolling directions at 45° to the original sheet (sample 22). Texturing, and the effect of annealing at 1573-1923 K on the revealed microstructure, was qualitatively determined using comparative x-ray diffraction techniques and Vickers microhardness indentation. Also, a new eddycurrent based technology called the Meandering Winding Magnetometer (MWM) was used to measure the anisotropic properties of the rolled sheets. This technique provides a relatively low cost alternative for quality assessment. The MWM technique is described along with the measurement results.
4:20pm EFFECT OF IRRADIATION ON THE TENSILE PROPERTIES OF RHENIUM: James A. Horak, Lockheed Martin Energy Systems, Inc., K-25 Technical Support Organization, P.O. Box 2003, MS7353, Oak Ridge, TN 37831; Michael Kangilaski, Advanced Methods and Materials, 1798 Technology Drive, #251, San Jose, CA 95110 Because of their capability for producing high power densities without interruption for long time periods (years) small, fast neutron energy spectrum nuclear reactors are candidates for applications such as orbiting satellites, lunar and Mars terrestrial power stations and manned trips to Mars. To provide high efficiency in the conversion of thermal energy to electrical energy, these reactors must operate at high temperatures (e.g.> I OOO°C) and they are cooled with liquid metals such as lithium. Because of its high temperature strength and excellent chemical compatibility with lithium, rhenium (Re) has been considered for use in nuclear reactors for space power. In a space reactor the Re would be subjected to fast neutron irradiation to fluences of more than I x 1O"n/cm'(E, > O.lMeV) during several years of operation. The current work was performed to provide information on the tensile properties of Re as a function of test temperature and the effects of neutron irradiation at high temperatures on these properties. Ductility of Re is high (-40%) at low temperatures but decreased abruptly to less than 5% at temperatures about -900°C. The work hardening coefficient is very high at room temperature and decreases slowly with increased test temperature. Fast neutron iradiation at approximately 1000, 1100, and 1300°C to fluences of 8 x 10'1 and 4 x 1O"n/cm' resulted in increases in strength and decreases in ductility for tests at room temperature, at the irradiation temperature, and at fifty degrees above the irradiation temperature. These effects decreased with increased irradiation temperature and increased with increased fluence. Also, irradiation lowered by more than 200°C the temperature of the abrupt increase in ductility.
3:00pm SYNTHESIS AND APPLICATION OF ARTIFICIAL GRAIN STRUC· TURES IN POTASSIUM·IMPLANTED RHENIUM: R.M. Collins, G. Welsch, Materials Science and Engineering, Case Western Reserve University, 514 White Bldg., Cleveland, OH 44106-7204 Layer composites of rhenium (re) were made by the chemical vapor deposition (CVD) process. The Re layers range from 0.05 to 0.10 mm in thickness. Between Re layer depositions, potassium atoms were injected into the metal matrix by ion implantation to a depth of 600 angstroms and a peak concentration of 1 at%. At high temperatures, the implanted atoms cluster and form bubbles that remain stable and act as barriers that pin grain boundaries thus producing a means for creating artificial grain architectures. The grain structure of the implanted CVD layer composites is compared to that of the unimplanted CVD composite. Room temperature tensile tests show that the artificial grain architecture increases the overall tensile strength of the CVD rhenium composite. 3:20 pm BREAK 3:40pm TENSILE AND CREEP PROPERTIES OF RHENIUM AND RHENIUM ALLOYS: Michael Kangilaski, Advanced Methods and Materials, 1798 Technology Drive, #251, San Jose, CA 95 110; M.M. Paxton, Westinghouse Hanford Company, Richland, WA Tensile properties of rhenium sheet, produced by powder technology techniques, were established from room temperature to 2000°C. The strength of
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4:40pm
teristics of Be when present in a continuous matrix of aluminum. Furthermore, it is necessary to examine the effect of the aluminum on the inhibition of initiation of cleave in the Be-AI alloys. In the present paper, we will present the results on the microstructural characterization of mechanically tested samples using SEM and TEM. The deformation behavior has been studied by SEM based fractography and TEM based on defects analyses. The observed fracture mechanisms will be discussed in terms of dislocation mobilities in the Al and the BE phase respectively.
HIGH TEMPERATURE MECHANICAL PROPERTIES OF Cr-Re ALLOYS: N. Brodnikovsky, V. Pisarenko, A. Rakitsky, A. Sameljuk, Frantsevich Institute for Problems of Materials Science, 3 Krjijanovskogo Str. 252680 Kiev, Ukraine The microstructure and mechanical characteristics of cast alloys Cr-35 Re and Cr-18 Re have been investigated within the wide temperature interval (20-1300°C ). It was found that under uniaxial tension within 20-600°C the plasticity of the alloys run into 10-20, whereas it decreased when the temperature rose above 700°C. The appearance of the plastic intercrystalline fracture at the temperatures above 900°C resulted in the sharp decrease of strength and plasticity of the alloys. It was established that small quantities of impurities CN, C, 0) contained in source materials effected the fracture mechanisms substantially. The additives of Fe to the alloys under investigation did not altered plastic characteristics at high test temperatures. The other perfomed research permitted to consider that the Cr-Re alloys can be obtained with high mechanical properties and within the temperature interval 700-1300°C.
2:50pm EFFECT OF ALLOYING ELEMENTS ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF SQUEEZE CAST Mg-AI-Zn-X ALLOYS: Jae Joong Kim, Do Hyang Kim*, Sang Hyuk Kim, Nack J. Kim, Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang, 790-784, Korea, *Dept. of Metallurgical Eng., Yonsei Univ., Shinchon-dong, Seodaemun-ku, Seoul, Korea Mg alloys offer the potential for significant weight savings in aerospace components because of their low density. Nevertheless, there is a strong need for Mg alloys with much improved mechanical properties. The main objective of the present research is to improve the mechanical properties of Mg alloys by squeeze casting and by alloy modification. The addition of Si results in the formation of Mg2Si in two morphologies; polygon and chinese script. While the polygonal Mg2Si improves the mechanical properties of Mg alloys, the chinese script Mg2Si promotes the brittle fracture along the Mg2Silmatrix interface, resulting in poor ductility. Microalloying elements have been added to modify the morphology of chinese script Mg2Si. It has been shown that the additions of Ca or P eliminate the chinese script Mg2Si so that all of the Mg2Si particles are present in polygonal form, resulting in the improvement of mechanical properties.
LIGHT WEIGHT ALLOYS FOR AEROSPACE APPLICATION IV: Session VI: Process and Analysis Sponsored by: SMD Non-Ferrous Metals Committee Program Organizer: Eui W. Lee, W.E. Frazier, Code 4342, Naval Air Warfare Center, Patuxent River, MD 20670; K. Jata, WUMLLM, WPAFB, OH 45433; N.J. Kim, Center for Advanced Aerospace Materials, POSTECH, Pohang, 790-784, Korea
Wednesday, PM February 12,1997
Room: 330A Location: Orlando Convention Center
3:15pm
Session Chairperson: K. Jata, WUMLLM, Wright Patterson Air Force Base, OH 45433
PHENOMENOLOGICAL MODELING OF SUPERPLASTICITY: E Booeshaghi, H. Garmestani, P. N. Kalu, Department of Mechanical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL
2:00pm
There has been an increased interest in the mechanics and materials field to improve the constitutive relations for the superplastic deformation of advanced materials. This interest has been stimulated partly due to the discovery of high strain rate superplasticity, and partly due to the availability of powerful computers. In this paper, an attempt was made to develop new type of constitutive relations to elucidate superplasticity. Although the model was derived from Hart's model, it incorporates detailed microstructural parameters and can be extended to multiaxial deformation. An attempt was made to use the model to explain the deformation mechanisms in superplastic AI-Li 7475 and AI-Li 8090 alloys. Load relaxation and jump strain rate tests were employed in this investigation. Microstructural characterization was carried out by optical nicroscopy and orientation Imaging Microscopy.
EFFECT OF PROCESSING VARIABLES ON MECHANICAL PROPERTIES OF RHEOCAST AZ9ID Mg ALLOYS: C.D. Vim, K.S. Shin, School of Materials Science and Engineering and Center for Advanced Aerospace Materials, Seoul National University, Shinrim-dong, Seoul, Korea Rheocast ingots of an AZ9 ID magnesium alloy were produced with different processing conditions. Processing variables included stirring rate (V s) and stirring temperature (Ts). The microstructures of the rheocast AZ91D magnesium alloys were similar to those of composite materials consisted of soft primary particles distributed in the hard matrix. A detailed examination was made on the relation between processing variables and mechanical properties. With increasing Vsand Ts, the size and the solid volume fraction of the soft primary particles decreased and the hardness and the UTS of the rheocast alloys increased. The mechanical properties of the rheocast alloys were analyzed quantitatively as a function of microstructural parameters such as the size and the solid volume fraction of the primary particles.
3:40pm WATERJET ABRASIVE APPLICATIONS FOR LIGHT WEIGHT ALLOYS: Lin Zhong Lee, Laser Applications, Inc., Westminster, MD 21157 As the aerospace applications of light weight alloys expand, waterjet abrasive process is a viable approach to manufacturing. This technology utilizes high pressurized water and an abrasive passing through a nozzle that is capable of cutting most materials up to 9" thick. It provides precision cutting of any contour, shape, and size which will allow engineers and designers the freedom to create more complex designs. The main components of a waterjet system consist of an ultra-high pressure intensifier, a cutting head, and a CNC controller. The jet parameters consist of the water pressure, orifice size, nozzle size, abrasive type, abrasive flow rate and cutting head feedrate. The kinetic energy is created from the mass of the water and abrasive exiting the nozzle at twice the speed of sound. At this high velocity, the jet stream acts like a solid medium that erodes the material. The efficiency of the waterjet is dependent on the initial energy leaving the nozzle and the energy required to remove the material. Therefore, it is easier to cut a soft and thin material than a hard and thick material. Through this process, superior edge quality is achieved with no heat affect zone (HAZ), no metal contamination, no distortion, no slag, and no delamination.
2:25pm DEFORMATION MECHANISMS AND MECHANICAL BEHAVIOR OF A NOVEL IN-SITU Be-AI COMPOSITE: X.D. Zhang', J.M.K. Wiezorek', G. Meyrick', EC. Grensing', H.L. Fraser', 'Department of Materials Science and Engineering, The Ohio State University, 2041 College Rd., Columbus, OH 43210; 'Brush Wellman, 14710 West Portage River South Rd., Elmore, OH 43416 There has been considerable interest in the production of light weight composite materials for aerospace applications. One of the promising candidates is an in-situ composite consisted of Be and AI. This material combines a high elastic modulus, low density with a relatively high melting point. Unlike the brittle Be, which does not undergo extensive plastic deformation prior to failure, the Be-AI alloys examined in the present study exhibit a remarkable formability. Both extruded and rolled products have been prepared successfully. However, the mechanisms responsible for these attractive characteristics of the Be-AI alloys have not yet been identified. Thus, it is timely and important to ascertain the active deformation modes governing the deformation charac-
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4:05pm MICROMECHANICALANALYSIS OF ADHESION STRENGTH FOR A BRITTLE FILM COATED SUBSTRATE: Jeung-hyun Jeong, Hae-Seok Park, Jeong-Hoon Ahn and Dongil Kwon, School of Materials Science and Engineering, Seoul National University, Seoul 151-742, Korea
LOW ENERGY PROCESSES IN ELECTRONIC MATERIALS: Plasma Etching Sponsored by: EMPMD Thin Films and Interfaces Committee Program Organizers: Rajiv K. Singh, University of Florida, 317 MAE, PO Box 116400, Gainesville, FL 32611-6400; O.w. Holland, Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831; Steve Pearton, University of Florida, 343 NSC, PO Box 116400, Gainesville, FL 32611-6400; Roy Clarke, Department of Applied Physics, University of Michigan, Ann Arbor, MI48109-1120; D. Kumar, University of Florida, PO Box 116400, Gainesville, FL 32611
In this work, we attempted to estimate the interface adhesion strength through the stress analysis in a brittle film coated substrate by two methods: scratch method and film cracking method. Firstly, in a scratch test, the critical load used as a qualitative estimate of adhesion is converted into work of adhesion by analyzing the stress field beneath the indenter, which results from three contributions, i.e., the static indentation added by the blister stress field, the friction between the indenter and film, and the residual stress. Secondly, in uniaxial loading of a brittle film coated soft substrate, the adhesion dependency of the development behavior of the transverse film cracks is analyzed specifying the film tensile stress and the interface shear stress which induce film cracking and interface failure, respectively. Then, the interface adhesion is quantified as interface shear strength because the stoppage of film cracking with further straining means the interface failure by the excessive interface shear stress, and the saturated value of crack spacing and strain can be used for the qualitative comparison of adhesion.
Wednesday, PM February 12, 1997
Room: 314B Location: Orlando Convention Center
Session Chairpersons: S.J. Pearton, University of Florida, 343 NSC, PO Box 116400, Gainesville, FL 32611-6400
2:00 pm INVITED EFFECT OF DRY ETCHING ON III-NITRIDES SURFACE: F. Ren, S.I. Pearton*, C.R. Abernathy*, J.R. Lothian, Bell Laboratories, 600 MountainAve., Rm. 7-B-207, Murray Hill, NJ 07974; *University of Florida, 343 NSC, PO Box 116400, Gainesville, FL 32611-6400
4:30pm ELECTROMAGNETIC PULSED CALIBRATION OF THIN ALUMINUM ALLOYS SHELLS: Sergey F. Golovashchenko, Moscow State Technical University, visiting at Ford Motor Company Scientific Lab Material Science Department, 20000 Rotunda Dr., P.O.Box 2053,MD3182, SRL, Dearborn, MI 48121-2053
2:30 pm INVITED GaAs SURFACE CHEMISTRY AND SURFACE DAMAGE IN A CI/ Ar HIGH DENSITY PLASMA ETCHING PROCESS: Charles R. Eddy, Jr., O.J. Glembocki, D. Leonhardt, V.A. Shamamian, R.T. Holm, J.E. Butler, Naval Research Laboratory, S. W. Pang, University of Michigan, Ann Arbor, MI 48109-1120
Pulsed electromagnetic field have been used to size thinwalled shells inside calibration dies. This works even when the shell have been formed by bending sheet metal and closed by a welding seam. Deformation is accomplished by a high-voltage discharge of capacitors through a coil inside the shell. Experimental results for AI-Cu-Fe-M high strength alloy rings are presented. They show a significant improvement of the accuracy of shell dimensions with increasing pressure amplitude. Results of the numerical simulation of the shell-die contact interaction are obtained assuming that shell is elasto-plastic and the die is elastic. Solid mechanics equation of motion and elasto-plastic flow role have been used to simulate this process. This simulation takes account of multiple impacts, spring back, stress waves in shell and die and has been experimentally validated.
3:00pm HIGH DENSITY ELECTRON CYCLOTRON RESONANCE ETCHING FOR METALS: K. Jung, J. W. Lee, Y. Park, J.R. Childress, SJ. Pearton, University of Florida, P.O. Box 116400, Gainesville, FL 32611
4:55pm THERMAL ANALYSIS OF AGED BINARY Al-Li ALLOYS: Sedat Ozbilen, Gazi University, Faculty of Technical Education, Metal Educational Department, Teknikokullar, Ankara, Turkey
3:45 pm BREAK
3:15 pm INVITED DAMAGE EVOLUTION IN DRY-ETCHED GaAs: Comparison Between Reactive Ion Etching and Low Energy Electron Enhanced Etching: M.S. Goorsky, H.P. Gillis, A.M. Andrews, University of California, Los Angeles, CA
Session Chairperson: F. Ren, Bell Laboratories, 600 Mountain Ave., Rm. 7B-207, Murray Hill, NJ 07974
Al-Li binary alloys with nominal Li contents of 0.1, 1.0,2.8 (in wt%) were aged naturally (for 3 months) and artificially (not only for 2 months both at 65% and 100°C but also for 2 days at 190°C) after water quenching to 25°C following solutionizing at 530°C for 20 minutes. Ageing behaviour of these binary alloys were studied by Vicker's Hardness measurements and DSC/ DTA thermal analysis. The results of this investigation will be presented.
4:00 pm INVITED SEMICONDUCTOR MATERIALS PROCESSING UTILIZING AN INDUCTIVELY COUPLED PLASMA BEAM SOURCE: C. Constantine, Plasma Therm, Inc.; R.I. Shul, Sandia National Laboratories; S.I. Pearton, University of Florida, Gainesville, FL 32611 4:30 pm INVITED NANOMETER-SCALE STUDIES OF NITRIDE/ARSENIDE HETEROSTRUCTURES PRODUCED BY NITROGEN PLASMA EXPOSURE OF GaAs: Rachel S. Goldman " " B.G. Briner3, R.M. Feenstra',M.L. O'Steen', R.J. Hauenstein" lPresent address; University of Michigan, Ann Arbor, MI; 'Camegie Mellon University, Pittsburgh, PA; 3FritzHaber-Inst. Der Max-Plank-Gescllschaft, Germany; 'Oklahoma State University 5:00pm COMPARISON OF ECR PLASMA CHEMISTRIES FOR ETCHING OF InGaPAND AIGaP: J. Hong, J.W. Lee, C.R. Abernathy, S.J. Pearton, C. Constantine', W.S. Hobson', and F. Ren', University of Florida, Gainesville, FL; 'Plasma Therm Inc.; 'Bell Laboratories
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5:15pm COMPARISON OF DRY ETCHING OF II-V SEMICONDUCTORS IN IcVAr AND Ibr/Ar ELECTRON CYCLOTRON RESONANCE PLASMAS: I. W Lee, J. Hong, E.S. Lambers, c.R. Abernathy, S.J. Pearton, University of Florida, PO Box 116400, Gainesville, FL 32611; W.S. Hobson, F. Ren, Bell Laboratories
2:50pm MECHANICAL PROPERTIES AND MICROSTRUCTURAL CHARACTERIZATION OF THE COMMERCIAL ALUMINUM ALLOY 6063 UNDER DIFFERENT HOMOGENIZING THERMAL TREATMENTS: J.R. Rendon, C.v.G Venalum, Puerto Ordaz, Venezuela, B. Hidalgo, Universidad de Oriente, Cumana, Venezuela, Mokka N. Rao, Universidad Nacional Experimental de Guayana, Puerto Ordaz, Venezuela Cylinders of commercial aluminum alloy 6063 were homogenized under different conditions. The experimental results indicate that the general mechanical behavior as related to curves of 0.2% yield strength, ultimate tensile strength, and ductility versus homogenizing process is the same in both cases. These mechanical properties as compared to those required by plant specifications, tend to be better with increasing values of %Mg 2Si in the alloy, as expected. The electron microscopy investigations revealed that in both homogenizing processes the resulting microstructure consist of significant spheroidizing of the alpha phase (AIFeSi) and fine - needle type structures of the beta phase. The alpha phase was also present in a Chinese scripture type structure. Furthermore, the slow cooling within the furnace resulted in the nucleation and growth of Mg 2Si precipitates generally along the grain boundaries.
MATERIALS PROCESSING FUNDAMENTALS SYMPOSIUM IV Sponsored by: Jt. EPDIMDMD Synthesis, Control, and Analysis in Materials Processing Committee, EPD Process Fundamentals, Aqueous Processing, Copper, Nickel-Cobalt, Pyrometallurgy, Lead, Zinc, Tin Committees, MSD Thermodynamic & Phase Equilibria Committee Program Organizers: R.G. Reddy, Department of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL 35487-0202; S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; P.R. Taylor, Department of Metallurgical and Mining Engineering, University of Idaho, Moscow, ID 83843 Wednesday, PM February 12, 1997
Room: 231B Location: Orlando Convention Center
3:15pm THE FIRST EXPERIENCE WITH FORMATION OF "NATURAL" METAL-MATRIX COMPOSITE BY THE APPROPRIATE THERMOMECHANICAL TREATMENT OF POLYCRYSTALLINE METALS: A. Korbel, W. Bochniak, F. Ciura, H. Dybiec, K. Piela, The Department of Structure & Mechanics of Solids, Academy of Mining and Metallurgy, Mickiewicza 30, 30-059 Krakow, Poland
Session Chairpersons: P.R. Taylor, University of Idaho, Dept. of Metallurgical & Mining Engineering, Moscow, ID 83844-3024; J. R. Groza, Chemical Engineering and Materials Science Dept., University of California at Davis.
2:00pm ZIRCONIUM CARBIDE SYNTHESIS IN A HIGH TEMPERATURE PLASMA REACTOR: Patrick R. Taylor, Banqiu Wu and Edgar E. Vidal, University of Idaho, Department of Metallurgical & Mining Engineering, Moscow, ID 83844-3024
The progress in understanding of the nature of strain localization in metallic materials and in particular understanding of the role of external (deformation conditions) and internal (material substructure) factors in the development of the tendency toward concentration of plastic flow within transgranular shear bands has laid at the background of the pointed in the title idea. Following this idea, a practical possibility of replacement a homogeneous in a micro scale mode of deformation by transgrasnular shear bands gives a chance to change the arrangement of dislocation substructure in the material from that typical for homogeneous deformation into a long wavelength (transgranular), pseudo-periodic dislocation walls. The presence or formation of such a substructure in a thermodynamically unstable matrix may result in formation of the products of phase transformation along shear bands, giving rise to a composite like structure. The experimental verification of the idea is the main aim of the work. The spectrum of different materials undergoing (post or during shear banding) different phase transformations: precipitation from supersaturated solid solution in AI-base alloys, martensitic transformation in Fe-Ni alloy, austenite-ferrite and austenite perlite transformation in the plain carbon steel and a - ~ transformation in Cu-Zn brass has been studied by use of the optical and electron microscopy. The effect of this way induced structures on some mechanical properties (strength of materials, shape memory effect in Fe-Ni alloy) is also shown in the work.
Zirconium carbide powder has been synthesized from zircon concentrate and methane using a high temperature plasma reactor. A non-transferred DC plasma torch was used as heat source. A high temperature filter consisting of graphite felt was designed, built and operated to separate the zirconium carbide from silicon carbide during the process. Characterization of the collected powders was done by wet chemical analysis using Atomic Absorption (AA), Scanning and Transmission Electron Microscopy (SEM and TEM) and xRay Diffraction (XRD). It was found that the zirconium carbide purity was around 95% with silicon carbide being the primary impurity. The powders had particle sizes between 30 and 80 nm. Based on the XRD pattern a lattice parameter of 4.6932A was calculated for the zirconium carbide. The effect of several experimental variables is presented as well as a mathematical model that describes the temperature and velocity profiles in the reactor. 2:25pm PRECIPITATES ROLE IN SUPERPLASTICITY OF HIGH PERFORMANCE COPPER ALLOYS: Ken R. Anderson, Joanna R. Groza, Chemical Engineering and Materials Science Dept. University of California at Davis, A.T. Dumitrescu, Metallurgical Research Institute, Bucharest, Romania
3:40 pm BREAK 3:50pm STUDIES ON GROWTH MECHANISMS AND CHARACTERISTIC FACTORS FOR THE HYDROTHERMAL PREPARATION OF AQUARTZ CRYSTAL POWDERS: KeeJeung Lee, Kyung Won Seo, Young Mok, Department of Chemical Engineering, Ajou University, 5 WonchonDong, Paldal Gu, Suwon 442-749 Korea; Hyo Shin Yu, Korea Institute of Geology, Mining & Materials, Resources Utilization & Materials Division, 30 Kajung-Dong, Yusung Gu, Taejon, 305-350, Korea
High strength, high thermal conductivity copper alloys are in continuous demand for a variety of applications such as actively cooled structures, electric and electronic parts, molding tools or welding electrodes. The goal of the present work is to understand the interrelationship between processing and microstructure of these alloys to promote superplastic behavior. Chemistry and processing variations were applied to achieve precipitation of different dispersoids in the copper matrix. High temperature, high strain rate deformation was performed to characterize the superplastic behavior. Precipitate identification and microstructural studies were correlated to mechanical properties.
In this study the characteristic factors and formation mechanisms for the hydrothermal preparation of a-quartz crystal powders were investigated to find the optimum synthetic conditions. The degree of a-quartz crystal face development depended on the relative growth rate of a particular form that varies considerable with the degree of supersaturation, the reaction temperature, the concentration of mineralizers, and the presence of seed crystals in the feedstock. Alkali hydroxides and alkali halides were found to be effective in the reactions as mineralizers, which added in order to increase the solubility of the feedstock. The fine a quartz crystal powders were obtained in the tem-
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perature range of 250-500°C and pressure range of 100-300 atm. As the concentration of mineralizers increased, the particle size of crystalline powders became smaller with lower reaction temperatures. The fractional size distribution of synthetic crystal powders was depended on the hydrothermal conditions. As the reaction time and the amount of seed crystals increased, the width of particle size distribution became narrower. The weight mean particle size was in the range of 1 to lO).lm. The characterization of the products were carried out using XRD, SEM, PSA, FTIR, Raman Spectrometer.
METALLURGY OFTHE LESS COMMON METALS II: Thermodynamics and Phase Equilibria Sponsored by: MSD Thermodynamics and Phase Equilibria Committee, SMD Non-Ferrous Metals Committee Program Organizers: Prof. J.E. Morral, Univ. of Connecticut, 97 N. Eagleville Road, Storrs, CT 06269-3136; Dr. Harish Merchant, Gould Electronics, Inc, 35129 Curtis Blvd., Eastlake, OH 44095-4001; Dr. Frederick G. Yost, Sandia National Labs., MS0340, Dept. 1831, Albuquerque, NM 87185-0340
4:15pm THE INTRA GRANULAR FERRITE PLATE AND ITS NUCLEATING INCLUSIONS IN HAZ OF X-60 PIPE STEEL: Jiang Guo Chang, Zhu Yu Ru, Guo Shu Qiang, Xu Jian Lun, Department of Materials, Shanghai University, 149 Yan Chang Road, Shanghai 200072, China; Wang Yue Qlang, Pan Li Ying, Yu Di Wei, Bao Shan Iron & Steel Corporation
Wednesday, PM February 12, 1997
Room: 240A Location: Orlando Convention Center
Session Chairpersons: Prof. J. E. Morral, Univ. of Connecticut, 97 N. Eagleville Road, Storrs, CT 06269-3136; Dr. H. Merchant, Gould Electronics, Inc, 35129 Curtis Blvd., Eastlake, OH 44095-4001
To improve the HAZ toughness of X-60 pipe steel the intragranular ferrite plate (IFP) technology was used. The characteristics of IFP is claimed to be much fine ferrite plates appear inside the original austenite grains. By means of a suitable Re, Zr, Ti additions in a bath with a higher initial oxygen potential, and a good control over the peak temperature as well as the cooling rate during welding simulation, one get a %IFP in volume over 50%, and the toughness goes up from 55 J to 160 J. It was found that the inclusions most effective on nucleating IFP are some deformable complex silicates which either entrapping Re, Zr, Ti oxides or containing these elements. The more the evenly distributed and effectively nucleating inclusions, the more the %IFP in volume, and the finer the microstructure of the HAZ, so the better the relevant toughness. Generally, these silicates behave as fine spheres along a line. The present authors revealed that these fine spheres result from the remelting of the silicates due to temperature raising up in the process of welding simulation. These silicates used to get a higher sulfur capacity, so MnS deposits might be observed on the periphery of the silicates. IFP was proved to be directly rooted in the [Mn] depleting zone which locates beside MnS deposits.
2:00 pm Invited EXPERIMENTAL AND OPTIMIZED BINARY SYSTEMS OF POSTTRANSITIONAL ELEMENTS: B. Legendre, Y. Feutelais and E. Dichi, Laboratoire de Chimie-Physique Minerale et Bioinorganique, Faculte de Pharmacie, 5 rue J.B. Clement, 92296 Chatenay-Malabry, France
Post transitional elements present a lot of physical properties, especially in the fields of electronic and opto-electronic. Thus the knowledge of binary and ternary phase diagrams is of great importance both for the elaboration of alloys and for their application. One of the characteristics of the elements of post transition is a low melting point and for a large number of them a high vapor pressure. For this last reason it is of great interest to include the gas phase with the condensed phases and to calculate the pressure dependence of the phase diagram. In this lecture, we present experimental data and the result of the optimization for some systems such as: cd-Ge, Cd-Te, Zn-Te, Cd-ZnTe, Ge-Te, Si-Te, Au-Te. All of these binary systems are included in a database (POSTRANS) compatible with Thermocalc.
4:40pm ZIRCONIUM PURIFICATION IN THE PROCESS OF METAL RAW MATERIALS IODINATION: Z.B. Moukhametshina, V.I. Adamovich,A.M. Chekmarev, Mendeleev University of Chemical Technology of Russia, Miusskaya sq., 9, Moscow 125047, Russia
2:30pm PHASE EQUILIBRIA AND THERMOCHEMISTRY OF THE IN-SE SYSTEM: C. Mallika, C.H. Chang, A. Davydov, BJ. Stanbery, TJ. Anderson, Dept. of Chemical Eng., Univ. of Florida, Gainesville, FL 32611
The process of various zirconium alloys iodination by the iodine vapor was investigated. The nature of impurities, conditions of iodination, iodine flow rate, and zirconium tetraiodide condensation rate effect on the metal impurities transfer process was analyzed, both qualitative and quantitative correlations were established. Impurities were classified according to their transfer extent. Another classification of impurities transport dependence on iodination process temperature was also offered Obtained results were compared with impurities transport data in the process of iodide refining available in literature. Some impurities transport mechanisms and iodide-refined metals improvement possibility by means of iodination conditions control were discussed.
The phase diagram and thermochemistry of the In-Se system have been studied by several investigators, however, the liquid mixture behavior is not well understood. The following galvanic cell: wi In(l),lnp3(s) II In20 3(s),[ln]In. S,(, '" II C IW was used to determine the activity of In in In-Se liquid alloys in the compositional range 0.10
Group III arsenides and antimonides are extremely important materials used in the manufacture of high speed and high frequency electronic devices, In the III-V semiconductor family As-Ga-In-Sb, there are four ternary subsystems, By selecting different compositions within these subsystems, electrical and optical properties of the material can be changed in order to satisfy different applications. In this work, experimental phase diagram information and thermochemical data available in the literature for the As-Ga-Sb and As-In-Sb 214
4:10pm
systems have been critically assessed as a preliminary step towards the study of the As-Ga-In-Sb system. Thermodynamic descriptions of the phases that are consistent with selected experimental data have been produced using the ternary optimizing program TERGSS and thermodynamic descriptions of the binary and unary phases from previous assessments. Phase equilibria and thermodynamic properties are presented which have been calculated from the optimized coefficients using MTDATA. This information can be used for optimizing materials growth conditions and device manufacture.
APPLICATION OF KNUDSEN EFFUSION MASS SPECTROSCOPY FOR THE STUDY OF THERMODYNAMIC AND PHASE DIAGRAM PROPERTIES OF TRANSITION METAL-TELLURIUM SYSTEMS: M. Sai Baba, Dept. of Chemistry, Texas A&M Univ., College Station, TX 77843; R. Viswanathan, Materials Chemistry Div., Chemical Group, Indira Gandi Centre for Atomic Research, Kalpakkam - 603 102, Tamil Nadu, India Knudsen effusion mass spectrometric technique has been employed to study the thermodynamic and phase diagram properties of transition metal-tellurium systems. Preferential evaporation of these metal tellurides has been made use of to generate the nonstoichiometric telluride phases in situ. From the variation of tellurium activity as a function of composition, homogeneity ranges of the nonstoichiometric metal tellurides have been arrived at. By applying Gibbs-Duhem integration the thermodynamic activity of the second component could be arrived at. From the activities, partial molar Gibbs free energies were derived. Some of the metal tellerium systems studied include Fe-Te, Cr-Te, Mo-Te and Mn-Te. In this paper we describe some of our results with emphasis on the usefulness of Knudsen effusion mass spectrometric method for deriving such information.
3:10pm POTENTIOMETRIC DETERMINATION OF THE THERMODYNAMIC STABILITY OF SB,03: R. Lowery, C. Mallika, and TJ. Anderson, Dept. of Chemical Engr., Univ. of Florida, Gainesville, FL 32611 Precise values of thermodynamic properties of SbP3 are required to synthesize and characterize the alloys of antimony for applications in thermoelectric devices and semiconductor technology. The Gibbs energy formation of Sb20 3 has been reliably reported in the literature using solid electrolyte emf measurements. This work is extended to determine the phase equilibrium temperatures in Sb/SbP3 system. The galvanic cell used in this study can be represented as WI CI Sb(s or I),SbP3(s or I LYSZ_ Cup,CulW The oxygen potential for the biphasic mixtures were derived from the cell potential data over the temperature range 790 to 983 K. Phase transition temperatures of 845.5 K (Sb,03' orthorhombic to Sb,03' cubic), 905.6 K (Sb,s to Sb,l) and 930.0 K (Sb,03,cubic to Sb,03,1) were obtained from discernible breaks in the emf-T plots. These results agree well with calorimetric values. A value of -712.4 kJ/mol calculated by third-law treatment for DHo'.298 (SbP3' orthorhombic) reasonably agrees with literature data.
4:30pm THE INTERFACIAL REACTIONS IN THE As-Se/Zn COUPLES: MingHorng Lin, Sinn-wen Chen, Dept. of Chemical Engr., National Tsing-Hua University, Hsinchu, Taiwan 30043, China; Jinn-lung Wang, Chemical Systems Research Div., Chung-Shan Institute of Science and Technology, LungTan, Taiwan, China The As-Se-based chalcogenide glasses are IR transparent, and are considered an ideal braze to the ZnSe and ZnS substrates in the IR detector. The interfacial reactions between As-Se and Zn are investigated for fundamental understanding. Three different kinds of reaction couples were prepared, and they were As-50at%Se/Zn at 350°C. As-50at%SelZn at 370°C, and As-60at%Sef Zn at 350°C annealed for various length of time. The cross sections of the reaction couples were analyzed by using OM and EPMA. Two phases were formed at the interface, and the diffusion paths were glasslZnSelAs,zn,lZn. The growth rates of the intermetallic layers were also determined by using as image analyzer. The growth rates followed the parabolic law for the type I and type III couples which indicated a diffusion-controlled mechanism.
3:30pm PREDICTING OF THE THERMODYNAMIC PROPERTIES FOR THE TERNARY SYSTEM Ga-Sb-Bi: DraganaZivkovic, Zivan Zivkovic, Univ. of Belgrade, Technical Faculty, 19210, Yugoslavia, Jaroslav Sestak, Czech Acad. of Sciences, Inst. of Physics, 18040 Praha, Czech Republic Ternary system Ga-Sb-Bi belongs to the group of alloy systems containing semi-conducting compounds, which are important from both the scientific and practical point of view. While binary systems Ga-Sb, Bi-Sb and Ga-Bi are mostly thermodynamically determined, there are only a few data about the thermodynamics of the investigated ternary system Ga-Bi-Sb. Because of the experimental difficulties in thermodynamic determination of this system, connected with the oxidation and volatizing of the present components at investigation temperatures, thermodynamic predicting is applied, and results of the comparative determination of thermodynamic properties in ternary system Ga-Sb-Bi by using following methods: Toop, R-function and general solution model, are given in this paper. Activities, activity coefficients, partial and integral molar quantities for all components in five quasibinary sections of the ternary system Ga-Sb-Bi are determined at temperature 1073K.
4:50pm THE ATMOSPHERIC OXIDATION OF TELLURIUM: Marc Suys, Ecole Polytechnique de Montreal, Dept. of Chemical Engr, C.P. 6079, centre-ville, Montreal (Quebec), Canada DA, H3C 3A7; A. Roy and J. L'Ecuyer, Noranda Advanced Materials, 4950 Levy, Saint-Laurent (Quebec), Canada, H4R2PI Tellurium forms technologically important alloys which are being used increasingly in the semiconductor industry (CdTe,Bi2Te3). As such, control of the purity of the source TE metal is critical. Therefore, the understanding of the atmospheric oxidation of tellerium cannot be neglected, as it can be a source of oxygen incorporation in the metal, and thus in the alloys. We have studied, by X-Ray Photoelectron Spectroscopy (XPS), the oxidation of crushed tellerium under various conditions of humidity and air exposure. The rate of oxidation of tellerium is relatively slow: 30 A of tellerium dioxide is detected on the surface of a sample after 8 days of direct air exposure. Our results tend to suggest that the rate-limiting step is the transport of the oxidizing reactant to the tellerium surface. We have also observed that the oxidation reaction is dependent on the relative humidity, as has been reported previously, for thin films, by various authors.
3:50pm THERMODYNAMIC PROPERTIES AND VAPOR-LIQUID EQUILIBRIUM RELATIONS OF INDIUM-CONTAINING BINARIES: Dajian Wang, Kunming University of Science and Technology, Yunnan, 650093, China To establish the vapor-liquid equilibrium composition relations of In-Sn, InPb, In-Zn, the Miedema's cellular model of heat of formation of binary liquid alloys are employed to correlate the activity coefficients of each component in the binary. Based on the dissimilar Wigner-Seitz atomic cells model, a quantitative analysis of heats of mixing and solution of binary alloys was Miedema. Tanaka deduced the relation between mixing enthalpy and excess entropy of liquid binary alloy. Through the correlation between the heat of formation and excess Gibbs free energy, the activity coefficients and their practical pressures can be analyzed. The obtained results have met the needs of activity coefficients of each component in above alloys in the applications of vacuum separation techniques, as well as in the development of lead-free solder of In-Sn binary or related multicomponent systems.
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of an SEM or were attached to the SEM. Contributions of Kromp, Weiss, Strickler, Kikukawa, Jono, Aachi, Davidson, Hoeppner and others will be reviewed. In addition the past 25 years has seen the development of numerous in-situ systems. This has led to much greater understanding of fatigue crack nucleation and microstructurally dependent propagation. These studies and observations will be reviewed in the paper.
RECENT ADVANCES IN FRACTURE VI: Fatigue Fracture: A Symposium Dedicated to Professor Emeritus Frank A. McClintock Sponsored by: MSD Flow and Fracture; SMD Mechanical Metallurgy Program Organizers: Dr. R. K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; Dr. A.B. Geltmacher, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D.C. 20375; Dr. K. Sadananda, Naval Research Laboratory, Code 6323, 4555 Overlook Drive SW, Washington D.C. 20375; Dr. P. Matic, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375 Wednesday, PM February 12, 1997
2:50 pm INVITED DISLOCATION-CRACK INTERACTIONS DURING FATIGUE CRACK GROWTH: K. Sadananda l , N. Louat2 A. K. Vasudevan3 , 'Naval Research Laboratory, Code 6323, 4555 Overlook Drive SW, Washington D. C. 20375; 2Fairfax Materials Research Inc., 5613 Marble Arch Way, Alexandria, VA22315; 3Code 332, Office Naval Research, N. Quincy Road, Arlington, VA 22217
Room: 314A Location: Orlando Convention Center
Fatigue crack growth occurs due to irreversibility associated with the plastic flow under cyclic load. Although crack growth occurs by plastic flow, the use of elastic fracture mechanics parameter to quantify crack growth may still be justified since material for the most part is under elastic loading, normally termed as small scale loading. In the past, concepts such as plasticity induced crack closure have crept into the literature and led to massive confusion in the literature in understanding and quantifying fatigue crack growth. We present new unifying concepts using dislocation models that accounts, load-ratio effects, so-called anomalous effects of short cracks, over-load and under-load effects, as well as concepts that connect the crack nucleation through Kitagaawa diagram.
Session Chairpersons: Professor Robert O. Ritchie, Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 974201760 and, Center for Advanced Materials, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; Dr. Michael F. Henry, General Electric CR&D, P.O. Box 8, K1MB229, Schenectady, NY 12309
2:00 pm INVITED MECHANISMS OF FATIGUE FRACTURE IN METALLIC, CERAMIC, AND INTERMETALLIC MATERIALS: Robert O. Ritchie, Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 97420-1760 and, Center for Advanced Materials, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
3:25 pm INVITED FATIGUE FRACTURE STRIATION FORMATION AND ITS RELATION TO CRACK TIP BEHAVIOR: Campbell Laird and Pedro Peralta, Department of Materials Science and Engineering, University of Pennsylvania, 3231 Wanut Street, Philadelphia, PA 19104
From his early micro-mechanical modeling of fatigue-crack propagation in anti-plane shear to his later hypothesis for the existence of a fatigue threshold, Frank McClintock has made many seminal contributions to the understanding of fatigue fracture in metallic materials. In this presentation, current thinking on the mechanics and mechanisms of fatigue is examined, with particular emphasis on the similarities and differences between metal fatigue and the failure of monolithic and composite intermetallics and ceramics under cyclic loading. This is achieved by considering the process of fatiguecrack growth as a mutual competition between intrinsic mechanisms of crack advance ahead of the crack tip (e.g. alternating shear), which promote crack growth, and extrinsic mechanisms of crack-tip shielding behind the tip (e.g., crack closure and bridging), which impede it. The widely differing nature of these mechanisms and their specific dependence upon the alternating and maximum driven forces (e.g., ilK and Km,,) provide a useful distinction of the process of fatigue-crack propagation in the different classes of materials.
The mechanisms of fatigue striation formation are reviewed in terms of ductile and brittle fracture processes. Depending on these processes, fatigue striations can show considerable morphological variations, which are explained in terms of detailed slip processes and dislocation structures as well as fracture mechanisms. The problem of striation formation during intergranular crack propagation is also treated with respect to new results obtained on bicrystals having misorientation. These results are helpful for understanding how striation formation is related to the geometry and crystallography of slip at the crack tip. 3:50 pm BREAK 4:00 pm INVITED INFLUENCE OF MICROSTRUCTURE ON LOW CYCLE FATIGUE FRACTURE: S. L. Mannan, K. Bhanu Sankara Rao, Materials Development Division, Indira Gandhi Center for Atomic Research, Kalpakkam 603 102, India
2:25 pm INVITED OBSERVATIONS ON THE NUCLEATION AND MICROSTRUCTURALLYDEPENDENT CRACK PROPAGATION IN STRUCTURAL METALLIC MATERIALS: David W. Hoeppner, Department of Mechanical Engineering and Quality and Integrity Design Engineering Center, University of Utah, 3209 MEB, Salt Lake City, UT 84112
High temperature low cycle fatigue (LCF) has been an area of great interest in the last decades because of its relevance in nuclear and aerospace industrial applications. In general, the cyclic deformation and fracture of alloys engineered for high performance applications depend critically on the stability of initial microstructure during cyclic loading and on the slip mode, both of which in tum depending on temperature, govern the cyclic stress response and the mode of crack initiation and propagation. In order to attain adequate fatigue resistance in high temperature materials, a thorough understanding of quantitative relationship between initial microstructure and the fracture mode is required. Grain size, degree of prior cold work, thermal ageing that occurs prior to and during service are the major structural parameters that influence LCF of austenitic stainless steels while the size and distribution of i and carbides control the cyclic deformation and fracture in nickel base superalloys. Low cycle fatigue studies have been conducted on 304SS to examine the effects of grain size (75, 310 and 700 f..lm), cold work (0,10,20 and 30%) and thermal ageing (923K: 1000 h, 3000 h, 5000 h) on LCF fracture over a very wide temperature range (300-1023 K). Fine grained material exhibited better endurance in terms of total and plastic strain amplitudes at all temperatures. The temperature dependence of fatigue life showed a complex behaviour. Medium and coarse grained alloy displayed a continuous reduction in life with increase in temperature with recovery in life at elevated temperatures.
In the mid 1800's Sorby used the optical microscope to study fatigue deformation of materials and started an activity that continues with some vigor today. The early investigators of fatigue deformation wanted to learn the mechanism(s) of fatigue crack nucleation and propagation. This progress was aided by many investigators including Frank McClintock. McClintock and other investigators inspired many investigators to pursue the observation of fatigue deformation so that improved understanding of fatigue mechanisms could be attained. However, many studies that were made were "static". That is, materials were exposed to cyclic loading and then viewed with the observational technique. While this allowed some progress to be made, this did not deal with the actual deformation(s) that were occurring and thus progress in understanding fatigue was very limited. However, some investigators did mount microscopes on fatigue machines and make what became known as "in-situ" observations. Some of the contributions made will be reviewed as background of this paper. The development of the scanning electron microscope has changed the understanding of cyclic deformation response in engineering and model materials. Starting in 1970 numerous investigators around the world developed fatigue machines that were either placed in the chamber
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The effects of grain size on life were rationalised on the basis of martensite transformation, dynamic strain ageing, oxidation and creep in the temperature range of their operation, The superior fatigue resistance of fine grained material has been attributed to the occurrence of trangranular fracture at all the temperatures. Cold work has been found to be both beneficial and harmful for fatigue life depending on the temperature. LCF life decreased with increasing PCW at and below 823 K, whereas at 923 K, PCW levels greater than 10% cold work exhibited recovery in life due to the reduced incidence of intergranular cracking. Thermal ageing prior to LCF testing promoted transgranular cracking and improved fatigue resistance. The influence of microstructure (A: free from carbides and y, B: peak aged spherical y of 18 nm diameter and C: overaged spherical y of 35 nm diameter) on strain controlled LCF behaviour of Nimonic PE-16 superalloy has been studied at 923 K. Coffin-Manson plots describing the plastic strain amplitude versus life showed that Microstructure A had maximum fatigue resistance while C displayed the least. Microstructure B showed a two slope behaviour in the Coffin-Manson plot. For this condition samples cycled at low strain amplitudes exhibited much shorter lives than would be expected by extrapolation from high strain portion of the plot. Microstructure A exhibited crack initiation in planar slip bands, followed by trans granular propagation marked by fatigue striations. In B, the fracture mode at high strains was transgranular, while at low strains propagation by both trans and intergranular (mixed mode) was observed. Alloy C displayed cleavage facets very frequently on the fracture surface, and crack propagation was mixed mode at all strain amplitudes. The microstructural dependence ofLCF behaviour and fracture modes have been rationalised on the basis of operative deformation mechanisms, degree of slip homogenization and the evolving microstructure during cyclic deformation. The degree of homogeneity was assessed by slip band spacing measurements on tested samples. These studies on 304SS and Nimonic PE-16 emphasise the need for optimisation of microstructure for maximizing fatigue resistance.
5:15 pm INVITED MICROMECHANICS OF FATIGUE AND FRACTURE IN LAMELLAR TiAl: Bimal K. Kad, Robert J. Asaro, Department of Applied Mechanics & Engineering Sciences, University of California at San Diego, La Jolla, CA92093 While phenomological correlations, or simple rules of mixtures, are an important initial step in predicting the composite bulk response, the complexities of inhomogeneous deformation in layered morphologies, strain partitioning and incompatibilities between the respective micro-constituents, and discrete interface slip characteristics present formidable challenges for microstructural design. Thus, finite element based numerical procedures, incorporating phyically based crystal plasticity models, are employed to study the evolution of non-uniform deformation, under monotonic and fully reversed cyclic loadings, in lamellar TiAI microstructures. The impetus for such efforts is to gather fundamental insight into microstructure sensitive deformation mechanisms, and to extract additional information, not obtainable from traditional mechanical property data measurements. Such an effort is particularly desirable to help track various aspects of plastic anisotropy of specific layers, and micro-constituents are implicit in polycrystalline aggregates. We will present several examples of experimentally observed, and numerically computed results, to identify hot spots for strain localization in fully reversed loadings, and prescribe microstructural remedies to alleviate such effects. 5:40pm STEADY-STATE FATIGUE CRACK GROWTH IN COMPOSITE LAMINATES: J. Tong, Department of Mechanical and Manufacturing Engineering, University of Portmouth, Anglesea Building, Anglesea Road, Portmouth POI 3DJ, UK Matrix crack growth behaviour under mechanical fatigue loading has been studied in a quasi-isotropic GFRP laminate. Detailed experimental observations have been made on the growth of individual cracks and the accumulation of cracks in ±45°C as well as 90' plies. The results show that when the crack length is sufficiently long compared with the layer thickness, the growth of fatigue cracks in off-axis layers is essentially independent of crack length, a phenomenon termed as steady-state cracking. A generalised plane strain finite element model has been constructed and used to relate the crack growth rate to the associated strain energy release rate. A good correlation has been achieved which indicates that strain energy release rate may be the appropriate parameter to characterise stable matrix growth behaviour in composite laminates.
4:25 pm INVITED CORROSION FATIGUE BEHAVIOR OF METALS AND ALLOYS: David J. Duquette, Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 The qualitative aspects of the effects of corrosion on the fatigue behavior of metals and alloys have been recognized for more than 60 years. However, for much of that time, corrosion was assumed to lower fatigue resistance, simply by either inducing stress raisers in the form of pitting, or by reducing the cross-sectional area of a component. Modern research has shown that there may be a ..:omplex synergism between corrosion and the cyclic deformation response of metallic materials. This synergism may affect precrack deformation, crack nucleation and/or crack propagation. This presentation will address this synergism, and attempt to demonstrate that neither simple corrosion models for crack initiation, nor superposition models where corrosion rates and fatigue crack propagation rates are numerically added, are adequate to represent corrosion fatigue damage.
SPRAY FORMING - EXPERIMENT, ANALYSIS, AND APPLICATIONS II: Experiments Sponsored by: MDMD Shaping and Forming Committee, Jt. EPDIMDMD Synthesis Control & AnalYSis in Materials Processing Committee Program Organizer: Dr. Prabir K. Chaudhury, Concurrent Technologies Corporation, 1450 Scalp Avenue, Johnstown, PA, 15904; Prof. Enrique J. Lavernia, Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92717
4:50 pm INVITED ON LOAD-INTERACTION EFFECTS IN FATIGUE CRACK GROWTH: Arthur J. McEvily, Department of Metallurgy and Institute of Materials Science, U-136, University of Connecticut, Storrs, CT 06268 Load sequence effect can exert a strong influence on the rate of fatigue crack growth. For example, a large spike overload can result in a period of crack growth retardation after the overload. In order to calculate the number of delay cycles resulting from such an overload, a constitutive equation is needed, and it has been proposed that the following equation provides a generally valid constitutive relationship for the rate of fatigue crack growth: daldN =A (M,r M,jJth)2 where a is the crack length, N is the number of cycles, A is a material constant, M'ff is the effective range of the stress intensity factor, M,jJth is the effective range of stress intensity factor at threshold. This equation can only be used if crack closure effects are accounted for. Examples of the use of the equation to calculate the number or retardation cycles following an overload as a function of specimen thickness will be given. In addition, the application of the equation to the study of short crack growth involving high-low and low-high load sequences will also be demonstrated.
Wednesday, PM February 12, 1997
Room: 330B Location: Orlando Convention Center
Session Chairperson: Professor Jose Luis Estrada Haen, Instituto Politecnico Nacional, Unidad Profesional Adolfo Lopez Mateos, Mexico
2:00 pm KEYNOTE EXPERIMENTAL BASED DETECTION OF THE SPLASH LIMITS FOR THE NORMAL AND OBLIQUE IMPACT OF MOLTEN METAL PARTICLES ON DIFFERENT SURFACES: M. Berg, J. Ulrich, Universitat Bremen, VerfahrenstechnikIFB4, Postfach 330440, D-28334 Bremen, Germany Understanding of the impact of single molten metal particles contribute to reduce the overspray during the spray deposition processes. The impact of molten Pb- and Sn-particles with a flat solid surface is investigated experi-
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than the level of oxygen in commercially produced RSIPM Al alloys. There is no experimental evidence available about the distribution of Al,03 in spray formed Al alloys. We have studied the size and distribution of pores and the distribution of oxides in spray formed AI-Cr-Zr alloys. The fracture surfaces of the as sprayed and forged deposits were examined by AES and SAM. Cratered regions on the in situ fracture surfaces were identified and a localized 2nm thick AI,03 film on their surface was measured by high resolution AES. The fracture path followed areas rich in AI,03'
mentally. The impact process is monitored by a high speed video system. At each measurement all temperatures (particle, target, and ambient) are taken as the weight of the particle before and after impact. By means of the image processing, the final diameter of the splat is found and evaluated regarding physicla properties, impacting diameter, impact power, and target surface roughness. By the weight difference of a particle before and after the impact, amount of splashing material is detected. The impact diameter, the impact speed, and the spreading diameter are also observed by the high speed, and the spreading diameter are also observed by the high speed video system. The results are presented in the form of diagrams with dimensionless numbers such as the ratio of the maximum spreading diameter, d, to the initial particule diameter, D. Other numbers such as Weber, We, or Reynolds, Re, in connection with dID ratio give the possibility of comparing all experimental results with each other. A critical dimensionless number above which splashing exists has been discussed.
3:30 pm BREAK 3:50pm STUDY OF MICROSTRUCTURE AND PROPERTIES OF SPRAY FORMED AI-Cr-Zr ALLOYS: A.F. Norman, P. Tsakiropoulos, Department of Materials Science and Engineering, University of Surrey, Ouildford, Surrey OU2 5XH, UK
2:30pm MICROSTRUCTURE CHARACTERIZATION OF AI-Si AND AIMMCS PROCESSED BY SPRAY ATOMIZATION AND DEPOSITION: Jose Luis Estrada, Enrique Nicolas, Instituto Politecnico Nacional, Unidad Profesional Adolfo Lopez Mateos, MEXICO; Enrique J. Lavernia, Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92717
The technical problems and cost associated with the multi-step PM processing of RS Al alloys have hindered their successful development. Spray forming can obviate these problems by means of the integral inert gas atomisation and deposition operation in which the alloy exists in particulate form only for a few milliseconds. Spray forming experiments have been performed on AICr-Zr alloys studied previously by the combined RSIPM route. The microstructure and the tensile properties of the forged and heat treated deposits will be compared with the RSIPM alloy. The latter exhibits superior properties, not matched by the spray formed alloy.
The spray atomization and deposition process is described as applied to AI-Si alloys and AI-Si metal matrix composites. This process shown to be similar to powder metallurgy (PIM) in that advanced alloys can be manufactured. However, many difficulties inherent in PIM are avoided, including oxide film formation and the need for degassing. In the spray atomization and deposition process atomized droplets exist for only a few milliseconds before being deposited to form high density preforms. The primary metallurgical characteristics of AI-12w/oSi, AI-17w/oSi, AI22w/oSi and AI-alloy based MMCs reinforced with SiC particulates preforms are presented. Characterization of the preforms consisted of the description of the production technique, descriptions of the microstructures by light microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Auger electron spectroscopy. The volume percentage of reinforced particles was determined. Both the spray depositedAI-Si alloys and the AI-Si metal matrix composites exhibited a rapid solidified matrix microstructure and the spray deposited MMCs a relatively uniform distribution of reinforcements.
4:10pm ABOUT SELECTION AND DESIGN OF ELECTRODE MATERIALS FOR ELECTRO-SPARK ALLOYING OF STEELS: A.D. Verkhoturo, S.v. Nikolenko, Institute of Materials, Far Eastern Branch of Russian Academy of Sciences, Khabarovsk, Russia Earlier, we have proposed several parameters of selecting and designing electrode materials for electro-spark alloying (ESA) of metallic surfaces. These parameters were developed according to the necessity of achieving the maximum depth, continuity, the least stress in the alloyed layer (AL), as well as the least roughness. However, the developed principles account only for the "geometrical" characteristics of AL, without accounting for the technological characteristics, and the current manufacturing demands: higher productivity of the ESA process, creating the optimal conditions for the AL forming. Considering all of the above this paper discusses: I) The scientific principles of designing and selecting the multi-component electrode materials, that account for the electrode space composition, as well as the composition-structure-characteristics relationship of electrode materials on the physical-chemical characteristics of AL and allowing to decrease fragile destruction of electrode material in the total erosion phenomena. 2) "Technological" scheme of AL forming, that accounts for effect of physical-chemical properties of electrodes, parameters of ESA process on physical-chemical and exploitational properties of AL and allowing to receive coatings with given characteristics. According to these principles several new electrode materials have been created, using tungsten carbide and titanium base with self-fluxing and mineral additives that allow to greatly increase wear and heat resistance of construction and instrumental steels.
2:50pm TUNGSTEN BORIDE SYNTHESIS IN BURNING: S. V. Nikolenko, v.v. Oostischev, Institute of Materials, Far Eastern Branch of the Russian Academy of Sciences, Khabarovsk, Russia Nowadays, a great theoretical and practical interest is observed towards tungsten boride, that can be explained by its' specific physical, chemical and mechanical properties. This paper discusses the process of tungsten boride extraction by alumothermy from the tungsten-containing mineral (sheelite concentrate) derived from the original product by enriching. The experiments were conducted in air and vacuum. The study of the extracted products has shown that their composition differs and depends on the synthesis conditions. For example, if we use BP3' in relation W : B = I : 2; I : 3; I :4, as a boride element, then we get the lower borides as the synthesis products: W,B, WB and metallic tungsten. The use of boron oxide with coal gives W,C together with W,B 5 • Including boron carbide guarantees that we shall receive the higher boride W,B 5, independently from the environment of the reaction, due to the high speed of the burning. The conducted set of experiments, shows the possibility of synthesizing tungsten boride-base powders from the enriched mineral raw materials, which can be used for electro-spark and laser deposition of wear and heat resistant harding coats on construction and instrumental steels.
4:30pm CHARACTERIZATION OF CONTINUOUS PRODUCTION OF ALUMINUM ALLOYS DURING LINEAR SPRAY ATOMIZATION AND DEPOSITION: Y. Zhou, EJ. Lavernia, Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697-2575; S.w. Lee, V.O. McDonell, O.S. Samuelsen, Dept. of Mechanical Engineering and Aerospace, University of California, Irvine, CA 92697-2575; R.L. Kozarek, Processing Design and Smelting Division, Aluminum Company of America, Alcoa Center, PA 15069
3:10pm POROSITY AND OXIDE DISTRIBUTION IN SPRAY FORMED AICr-Zr ALLOYS: M. Baker, A. Hellwig, A.F. Norman, P. Tsakiropoulos, Department of Materials Science and Engineering, University of Surrey, Ouildford, Surrey OU2 5XH, UK
The linear spray atomization and deposition is a potential near-net shape technique for continuous production of aluminum alloys. Possible benefits of linear spray atomization and deposition are: a) deposit geometry improvement, b) high productivity, c) high aspect ratio, and d) low overspray yield. In the present study, characterization of metal sprays using phase Doppler particle analyzer (PDPA), such as droplet velocity distribution, droplet size, droplet size distribution and spatial distribution, was carried out. The droplet size
In spray formed Al alloys porosity is common and typically about 2 to 8% depending on alloy and product form and the oxygen content is typically less
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distribution of aluminum alloy powders were also studied using the mechanical sieving method to compare with the results obtained using PDPA. The plot of the axial velocity with droplet diameter reveals the relationship that smaller droplets have higher axial velocity than do lager droplets. The results also indicate that the axial velocity exhibit the bimodal behavior when atomization pressure approaches a certain critical value and this bimodal behavior behaves increasingly with higher atomization pressure. The Sauter mean diameter obtained using PDPA and the mass median diameter using the mechanical sieving show a decreasing trend with increasing atomization pressure.
STRUCTURE J"ND PROPERTIES OF INTERNAL INTERFACES VI: Energetics and Fracture Sponsored by: Jt. EMPMD/SMD Chemistry & Physics of Materials Committee, MSD Computer Simulation Committee Program Organizer: Diana Farkas, Dept. of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061; Elizabeth A. Holm, Sandia National Lab, Physical and Joining Metallurgy, MS 1411, Albuquerque, NM 87185-0340; David J. Srolovitz, Dept. of Materials Science & Engineering, University of Michigan, Ann Arbor, M148109-2136
4:50pm SPRAY ATOMIZATION AND DEPOSITION OF GAMMA TITANIUM ALUMINIDE ALLOYS: B. Li, EJ. Lavernia, Department of Chemical Engineering and Materials Science, University of California at Irvine, Irvine, CA,92697-2575
Wednesday, PM February 12, 1997
Room: 330G Location: Orlando Convention Center
Session Chairperson: Jeff Rickman, Dept. of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18105-3195
Spray forming of gamma titanium aluminides had been investigated experimentally and numerically. Three different nominal compositions had been successfully spray formed. The microstructure of spray formed Ti-47 Al consists of fine, equiaxed fully lamellar ~+y structure, with an average linear grain size of 60 11m and an average interlamellar spacing of 0.3 11m. These microstructural characteristics led to a higher creep resistance, in a temperature-stress regime of 780 to 850 DC and 180 to 320 MPa, relative to fully lamellar 1-TiAl obtained through conventional casting + heat treatment processes. A two dimensional modeling of the momentum and thermal behavior of atomized droplets of y-TiAI predicted that the two dimensional droplet size distribution in the spray cone changes from being heterogeneous to being almost homogeneous as axial flight distance increases. The modeling results also indicated that the two dimensional distribution of the fraction solidified in the spray cone is heterogeneous. The fraction solidified in the spray at any given axial distance increases with increasing radial distance from the spray axis.
1:30 pm INVITED ESTIMATION OF GRAIN BOUNDARY ENERGETICS FROM MI· CROSTRUCTURALDATA: BrentAdams, w.w. Mullins, Dept. ofMateri· als Science and Engineering, Carnegie-Mellon University, Pittsburgh, PA 15213-3890; David Kinderleherer, Mathematics Department, Carnegie-Mellon University, Pittsburgh, PA 15213 Abstract not available. 2:10pm THE RELATIONSHIP BETWEEN GB SEGREGATION AND FRAC· TURE STRENGTH: R.G. Faulkner, L.S. Shvindlerman, Institute of Poly· mer Technology and Materials Engineering, Loughborough University, Loughborough, Leics LEll 3TU, Institute for Solid State Physics, Russian Academy of Science, Chernogolovka, 142432, Moscow, Russia
5:10pm COARSENING KINETICS OF SOLID PARTICLES IN THE SPRAY· FORMED ALUMINUM ALLOY PREFORMS: Ram B. Bhagat, Maurice F. Amateau, The Pennsylvania State University, Applied Research Laboratory, P.O. Box 30, North Antherton Street, State College, PA 16804
A thermodynamic analysis is performed of the effects of segregation and grain boundary structure on grain boundary free energy in metallic solids. This leads to a definition of the reduction in grain boundary free energy caused by a given level of segregant. In tum this allows the prediction of grain boundary fracture strength assuming a ductile material intergranular fracture mecha· nism as proposed by McMahon and Vitek. The net result is that intergranular fracture strengths can be predicted as a function of the segregation patterns existing for the material's specific thermal history, the grain boundary sigma value, and the interplanar spacing on the boundary plane. A knowledge of the binding energy of the segregant atoms to the boundary is required but this is shown to be calculable on the basis of atomic misfits for metallic lattices. The results are compared with available data from Lim and Watanabe on GB fracture in Al·Sn-Zn materials.
The coarsening kinetics of solid particles in the semi-solid aluminum alloys have been reported to follow a parabolic or a cubic law. Considering the gasdynamic nature of the spray forming process, the high-velocity impact on the substrate is most likely to cause extensive deformation of the semi-solid and even the fully solidified droplets leading to dendrite fragmentation and grain multiplication followed by homogenization and coarsening both during the solidification and subsequent cooling until the temperature falls to a low value. In this investigation, we have developed a growth kinetics relationship based on our experimental results of the heat treatment of select spray·formed aluminum alloys. The calculated rate constant (as a function of temperature) is used in conjunction with a two-dimensional finite element analysis for tran· sient heat transfer to determine the growth of a solid particle in the semi-solid state at any time. The results of this study are useful in understanding the kinetics of grain growth and in obtaining equiaxed, fine-grained microstructures in the aluminum alloys.
2:30pm THE ROLE OF GRAIN BOUNDARY ARBON FILMS IN THE RATE· DEPENDENT, INTERGRANULAR FRACTURE OF NICKEL·COP· PER: MarjorieAnn E. Natishan, Matthew Wagonhoffer, Mechanical Engi· neering Department, University of Maryland, College Park, MD 20742 As part of an ongoing investigation to bound the service conditions of inter· granular failure in nickel-copper alloy K-500 containing grain boundary precipitates of carbon, previously tested stress-rupture specimens were examined to document and characterize the deformation associated with grain boundary failures. Of particular interest was defining the role of the grain boundary carbon precipitates in the rate-dependent intergranular fracture process under ambient conditions. The failed creep/stress rupture specimens were sectioned perpendicular to the fracture surface and prepared for optical and electron microscopy of the microstructure adjacent to the primary fracture. High resolution microscopy revealed voids opened along the grain boundaries at carbon precipitate/nickel grain boundary interfaces. It is postulated that voids nucleate along these interfaces due to the combined driving force of the applied local stress resulting from dislocation accumulation at grain boundary/carbon interfaces and vacancy diffusion to these high energy sites. The intergranular failure then results from crack propagation along intergranular paths weakened by void formation.
219
strength alloy is stressed in the presence of surface-absorbed impurities. Oxygen-induced cracking of nickel-based alloys at high temperatures (relevant to gas turbine engines) is thought to be an example of this phenomenon. A precipitation-hardened Cu-0.26%Be, which can be heat-treated to a wide range of strengths, is being used as a low-temperature model material for dynamic embrittlement. This alloy was found to be resistant to cracking at 200°C in an inert atmosphere but was highly susceptible to grain boundary cracking in air. Preliminary tests indicate that the failure time is highly stress-dependent, but there is an incubation time for the cracking, presumably related to crack nucleation. Crack growth rate studies are being done to eliminate the effect of the variable nucleation time. The oxygen partial pressure and yield strength dependence of the cracking mechanism are also being studied.
2:50pm ATOMISTIC STUDIES OF SEGREGATION AND FRACTURE IN AI· Mg ALLOYS: X. Y. Liu, J.B. Adams, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 105 South Goodwin Avenue, Urbana, IL 61801 High Mg content (>5%) AI-Mg alloys are known to cause edge cracking during the hot working. We investigated one possible explanation, that Mg segregation to grain-boundaries can embrittle them. The extent of Mg segregation to a wide variety of grain-boundaries in Al alloys with 10% Mg is determined with the EAM. These results are consistent with our previous surface segregation studies, which are consistent with experimental studies of surface segregation. The Griffith ideal work of fracture is determined by rigidly cleaving both pure AI andAI-Mg alloys; the presence of 20-40% Mg at interface is found to lower the work of adhesion by 10%. Segregation of Mg to surface (for slow fracture, i.e., below the threshold for catastrophic failure) suggests a further reduction of 20% in the work of adhesion. Dynamic studies of fracture are also carried out with Molecular Dynamics, to determine the effect of plastic deformation.
SYNTHESIS OF LIGHT-WEIGHT METALLIC MATERIALS II: Session VI: Powder Processing II Sponsored by: MSD SynthesisIProcessing Committee Program Organizers:C.M. Ward-Close, Structural Materials Center, R50 Building, Defense Research Agency, Farnborough, Hampshire, GU14 6TD, United Kingdom; F.H. Froes, University of Idaho, Institute for Materials and Advanced Processes, Mines Bldg 204, Moscow, ID 83844-3026; D.J. Chellman, Lockheed Aeronautical Systems Co., Lockheed Corporation, Marietta, GA 30063-0150; S. S. Cho, Vice President of Rapidly Solidified Materials Research Center, (RASOM), Chungnam National University, Taedok Science Town, Taejon 305-764 Korea
3:10 pm BREAK 3:30 pm INVITED ATOMISTIC SIMULATION OFNANOCRYSTALLINE MATERIALS: S.R. Phil/pot, P. Keblinski, D. Wolf, Materials Science Division, Argonne National Laboratory, Argonne, IL 60439; H. Gleiter, Forschungszentrum Karlsruhe, 76021 Karlsruhe, Germany
Wednesday, PM February 12, 1997
Molecular-dynamics simulations have been used to synthesize and characterize fully dense, three-dimensional, "relaxed" nanocrystalline fcc metals and silicon. The high-energy grain boundaries in these nanocrystalline materials are found to be highly disordered. In the case of silicon the structures of the highly-constrained grain boundaries, triple lines and point grain junctions were found to be highly disordered and similar to the structure of amorphous silicon. Computer simulations of the behavior of an idealized model nanocrystalline material expose important parallels that exist in the dynamical properties of nanocrystalline materials and glasses. Both types of heavily disordered, metastable microstructures exhibit low- and high-frequency lattice-vibrational modes not seen in the perfect crystal, giving rise to similar thermodynamic properties at low temperatures, most notably a pronounced anomaly in their specific heats and a free-energy based phase transition from the nanocrystalline state to the glass below a critical grain size. Based on a free-energy argument, we suggest that below a critical grain size nanocrystalline materials should be unstable with respect to the amorphous phase. Work supported by the U.S. Department of Energy, BES Materials Sciences, under Contract W-31-109-Eng-38 and by the A. v. Humboldt and Max-Planck Foundations (Max-Planck Research Award program).
Room: 330F Location: Orlando Convention Center
Session Chairpersons: L. Christodulou, Imperial College, Prince Consort Rd., London SW7 2BP; O. Senkov, University of Idaho, Moscow, ID 83844-3026
2:20pm REACTIVE PROCESSING OF ALUMINIUM METAL· MATRIX COMPOSITES: MJ. Capaldi', lL.F Kellie2 and lV. Wood', *Department of Materials Engineering and Materials Design, University 0 Nottingham, UK; 2 London & Scandinavian Metallurgical Co Ltd, Rotherham, UK Two distinct processes have been used to produce in situ reactions in aluminium in order to form composites with varying amounts and types of additive. The first involves fluoride salt reactions which result in the production of TiB2 particulate finely distributed in a wide range of aluminium base alloys (both cast and wrought). The particulate concentration is limited to about 12 vol % before problems of inclusion entrapment and porosity become evident. Brief details of the process and properties after conventional and pressure die casting will be reported. The second process uses a self-propagating high temperature synthesis reaction to make carbides, nitrides, borides or mixtures. A particular reaction to be reported will be for A 1+TiC. Details of the SHS reactions involved will be correlated with processibility and properties.
4:10pm THE EFFECT OF GRAIN BOUNDARY CHARACTER ON TIME DEPENDENT CRACK PROPAGATION IN A Ni·BASE SUPERAL· LOY: P.F. Browning', M.E Henry', K. Rajan2, 'General Electric Corp. Res. & Dev., P.O. Box 8, Schenectady, NY 12301; 2Rensselaer Polytechnic Institute, Dept. of Materials Engrg., Troy, NY 12180
2:20pm REACTIVE MILLING AND SINTERING OF ALUMINIUM BASE POWDER METALLURGY COMPONENTS: C.C. Degnan, lY. Wood, Department of Materials Engineering and Materials Design University of Nottingham, UK
An investigation of the effect of grain boundary character in the Ni-base superalloy Rene 88DT on environmentally assisted crack propagation in high temperature, gaseous environments will be presented. When tested at elevated temperature under hold time fatigue or sustained loading conditions in gaseous environment, crack propagation can occur intergranularly in this alloy, and hence may be influenced by grain boundary character. Automated microanalytical techniques have been applied to the crack tip area, with the intent of determining whether intergranular cracking occurs more readily along certain types of grain boundaries. The Coincident Side Lattice approach has been taken to characterize the misorientation between adjacent grains.
A form of mechanical alloying has been employed to create a range of structures in aluminium +X powders. The emphasis has been on partial mixing so that the energy of mixing can subsequently be utilised during sintering. A similar process has been employed to make intermetallica and sintering aids. The prime objective of the work is to allow conventional pressing and sintering to be employed for making high strength structurally sound powder metallurgy components.
4:30pm DYNAMIC EMBRITTLEMENT IN BERYLLIUM·STRENGTHENED COPPER: Ranjani C. Muthiah, CJ. McMahon, Jr., University of Pennsylvania, Philadelphia, PA; Amitava Guha, Brush Wellman Inc., Cleveland, OH
2:40pm THERMOMECHANICAL STUDY IN COMBUSTION SYNTHESIZED TI-Ni SHAPE MEMORY ALLOY: EM.H. Zarandi, K. Sadrnezhaad, Sharif University of Technology, Tehran, Iran 11365-9466
Dynamic embrittlement refers to the quasi-static diffusion-controlled decohesion, usually along grain boundaries, that can occur when a high-
The thermal explosion mode of self-propagating high-temperature Synthe-
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sis, by which time and energy can be saved and the cast product has the least interstitial contamination and high homogeneity, is used to successfully producing Ti-Ni shape memory alloys. The specimens, after hot and cold rolling, are solution treated and aged. The Rhombohedral(R)-phase transformation is observed in the Ti-50.03 at %Ni alloy. Ms (I) and T R(2) have their maximums at ageing temperatures of 773 and 723 k, respectively, and rise with Ni-contents. The rate of rising of TR' in aged specimens, depends on the composition and in the Ti-50.33 at %Ni alloy, in spite of the Ti-50.23 at %No alloy, Msis more than As(3)After cold rolling of solution treated specimens, more than 50 percent reduction in thickness, and ageing treatment the rate of variations of MsandAs versus ageing temperature decreases and up to ageing temperature of 723 k, T R is higher than that is in the not cold worked specimens. Also variations of Ms with amount of old working strains does not show uniform behaviour. All Round Shape Memory Effect occurs completely in the Ti-50.33 at %Ni alloy. 1- Start temperature of martensitic transformation; 2-Start temperature of R-phase transformation; 3-Start temperature of reverse martensitic transformation.
the energy balance between the input energy by centrifugal force and the increment of total surface energy of metallic liquids. The calculated mean size of powders agrees relatively well with that of the experiments. Also, the effects of rapid solidification undercooling, solidification rate and crystallisation behaviours can be evaluated effectively through the processes. The possibility of the customised not only size and morphology control but microstructure control was also shown. Both of the new methods can be applied to continuous powder making processes without oxygen contamination. 4:20pm Ti-6Al-4V HOLLOW SPHERE FOAMS: C. Uslu, J.K. Cochran, KJ. Lee* and T.H. Sanders, Jr, Georgia Institute of Technology, Atlanta, GA 303320245: *Ceramic Fillers, Inc., Atlanta, GA 30318 Structural foams, formed to near-net-shape by bonding monoxides hollow metal spheres at points of contact, offer the possibility of strong, light-weight, reasonably priced materials. The technology of making titanium hollow sphere foams has been developed using the coaxial nozzle powder slurry technique. Titanium hydride hollow powder spheres of 3 mm diameter and 20 mm wall thickness were fabricated from a high solids content acetone slurry. The powder shells were controlled atmosphere sintered and point contact bonded using the initial alloy hydride powder to form hollow sphere foams that were 20% of theoretical density. The sphere wall microstructures obtained by pressureless, solid-state sintering of the hydride alloy were compared to the conventional alloy microstructures and quantitative measures of sintering kinetics were established. Initial mechanical properties such as compressive yield strength and modulus will also be considered.
3:00pm STRUCTURAL METAL FOAMS FROM BONDED ALUMINIUMALLOY HOLLOW SPHERES: N.E. Naxter, J.K. Cochran, T.H. Sanders Jr., Georgia Institute of Technology, Atlanta, GA 30332-0245 The demand for ultra low density structural materials that are economical is increasing. The feasibility of bonding monosized hollow spheres at points of contact to fabricate net-shaped foams with isotropic properties has been demonstrated. Currently, research efforts are focusing on adapting existing technology developed at Georgia Tech to fabricated low density hollow metal spheres. Spheres are fabricated directly from the melt using a coaxial nozzle process. Molten aluminium is injected through the outer orifice of the nozzle with gas passing through the centre orifice. As instabilities form on the liquid jet, surface tension serves to pinch off hollow monosized spheres Parameters such as melt and nozzle temperature, liquid and gas flow rates, and temperature gradient of the drop zone are controlled. As in-depth study relating sphere cooling rates to microstructural evolution and corresponding mechanical properties has been undertaken and the results of these investigations will be the subject of this presentation.
4:40pm METAL FOAMS FROM FUGITIVE BURNOUT: A.R. Nagel, J.K. Cochran, T.H. Sanders, Jr, KJ. Lee* MSE-Georgia Institute of Tech Atlanta GA, 30332-0253; Ceramic Fillers Inc., Atlanta, GA Metallic foams are being made from powders using naturally occurring organic fugitive burnout material. Most forms are fabricated by introducing pores from a gas phase into a liquid system. This tends to produce pores of irregular cell size due to pore coalescence. The object of this effort is to introduce porosity utilising a fugitive solid phase to allow greater precision in forming pore systems. The foams being investigated are nickel and titanium alloys formed from slurries with starches as the fugitive materials. Starches are inexpensive and clean burning sacrificial materials. Because replication of fugitive starches requires fine particle size powders, brittle precursor powders (i.e. metal hydrides or oxides) are initially used to form the foam and subsequently decomposed or reduced to form metallic foams. Using particle packing and theological theories, the percolation value of closed cell porosity should be increased, and the microstructure of the foam should be made more uniform. Porosity and mechanical properties are being characterised for comparison to other forma geometries.
3:20pm DENSIFICATION OF RAPIDLY SOLIDIFIED ALUMINIUM ALLOY POWDERS: Eui-Seok Kim, Hyong-Seop Kim, Byong-Sun Chun, Rapidly Solidified Materials Research Centre, Chungram National University, Yuseong, Taejon, 305-764, Korea Rapidly solidified aluminium alloy powders have excellent physical and mechanical properties, such as high strength, high heat resistance, wear resistance, high modulus of elasticity and low thermal expansion. But the oxide layers on the particles and the sensitive microstructure to temperature make it difficult to densificate them. Thus, it is necessary to break up the oxide layers on the particles and weld each one strongly without microstructure deformation. This study not only provides the densification condition of rapidly solidified aluminium alloy powders, the microstructure and properties but also compare the experimental results to the FEM results.
5:00pm MODELING AND CONSOLIDATION OF NANOCRYSTALLINE ALUMINUM: J.S. Idasetima, R.B. Bhagat, M.F. Amateau, The Pennsylvania State University, Applied Research Laboratory, Box 30, New ARL Building, State College, PA 16804
3:40 pm BREAK 4:00pm SOLIDIFICATION BEHAVIOURS AND POWDER MAKING MECHANISMS OF THE EMULSIFIED METALLIC POWDERS: Chang-ki Min, Kyong-tae Nam, Woo-young Yoon, RASOM, Dept. of Metallurgical Engineering, Korea University, 1,5 Ka, Anam-dong, Sungbuk-ku, Seoul, 136-701, Korea
The consolidation of nanograined powder metals presents a major problem of grain growth to micrometer size thereby lowering the potential benefits expected of the nanocrystalline microstructures. The aim of this investigation is two fold: (a) to present our results of consolidating nanograined alumium powder in conjunction with process modeling using Ashby's HIP program. The preliminary modeling results suggest that the nanograined aluminum powder can be consolidated into full density with minimal grain growth without using any grain growth inhibitor by optimizing combined sintering and vacuum hot pressing. The predicted hot pressing temperature for aluminum nanopowders (20-200 nm) ranges from 300 to 400 K for a fixed pressure of 19 MPa; time being less than 10 minutes. Boundary diffusion mechanisms dominate in both stage 1 and stage 2 of the densification. The as-received nonograined powder and the fabricated specimens have been characterized by optical, scanning, and transmission electron microscopy, x-ray diffraction and microprobe analysis. Density and microhardness of the consolidated specimens are also reported and discussed.
New metallic powder making processes, named "Centrifugal Emulsification Process (CEP)" and "Mixer and Settler (MS)" have been developed to synthesize rapid solidified metallic powders. The underlying principle of CEP and mS was to emulsificate the liquid metals with inorganic oil (or salt) using centrifugal force. Through CEP and mS processings, the high temperature metals as well as the low temperature alloys are fabricated. The mean particle size and size distribution could be controlled by various processing parameters that could be managed easily. The morphology of the particles could also be customized using spherodization vs. Solidification time ratio in CEP. The powder formation mechanisms in CEP and MS were rationalised through
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9:25am POWDER METAL-MATRIX COMPOSITES: SELECTION AND PROCESSING: M. J. Tan and Zhang Xi, School ofMech. & Prod. Eng., Nanyang Technological University, NanyangAvenue, Singapore 2263
ADVANCES IN SYNTHESIS AND PROCESSING OF METAL CERAMIC MATRIX COMPOSITES V Sponsored by: MSD Materials, Synthesis & Processing Committee and Jt. SMDI MSD Composite Materials Committee Program Organizers:L.L. Shaw, Dept. of Metallurgy and Materials Engineering, University of Connecticut, Storrs, CT 06269; E.J. Lavemia, Dept. of Mechanical and Aerospace Engineering, University of California -Irvine, Irvine, CA 92717; S. Krishnamurthy, UES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432-1894; E.S. Chen, U.S. Army Research Office, 4300 S. Miami Blvd., Research Triangle Park, NC27709
Thursday, AM February 13, 1997
There has been growing interest in the last decade in the development of metal-matrix composites (MMCs) for the aerospace industries because of their attractive physical and mechanical properties, and enhanced elevated temperature capabilities. However, some of the fabrication techniques (e.g. using powder metallurgy) for this new class of MMCs are hampered by (i) the poor distribution of the reinforcements, and (ii) the limited room temperature ductility of the composites and hence formability. This presentation reports work done to address the above two problems by (i) an analysis based on size difference of matrix and reinforcement particles, taking into account the processing parameters, and (ii) introducing an innovative way of extruding brittle composites to increase its formability. By mainly considering the size difference effect of matrix powder and reinforcement particle, a critical value of reinforcement size is proposed to predict whether a uniform distribution of reinforcement is possible in powder metallurgy of particulate reinforced metal matrix composites. A uniform distribution of reinforcement could be expected only when the reinforcement size dr is not less than a critical value de which is a function ofreinforcement size d, and volume fraction V f and reduction ratio of secondary processing, R. In extrusion, a Front Pad Extrusion Method was used to avoid fir-tree cracking on the surfaces of extrudates, especially the brittle metal composites. By this method, the MMCs were successfully extruded without any surface cracking, and all the extrudates were found to be covered by a thin layer of the pad material. This was illustrated using a schematic flow pattern of the extrudate and pad material in the dead metal zone during extrusion. Furthermore, decreased pressure requirements were necessary for extrusions using the front pad extrusion method.
Room:340B Location: Orlando Convention Center
Session Chairpersons: Prof. Leon L. Shaw, Dept. of Metallurgy and Materials Engineering, University of Connecticut, Storrs, CT 06269; Dr. David E. Alman, U.S. Department of Energy, Albany Research Center, Albany, Oregon 97321
8:30 am INVITED COMMERCIAL PROCESSING OF METAL MATRIX COMPOSITES:
W. C. Harrigan, Jr., Alyn Corporation, P. O. Box 16249, Irvine, CA 92623 Discontinuously reinforced metal matrix composites are a class of materials that exhibit a blending of properties of the reinforcement and the matrix. The reinforcement can be ultrahigh strength whiskers, short or chopped fibers or particles. Each of the reinforcements have property or cost attributes which dictates use in a given situation. Commercial producers have concentrated on composites with particles because of cost issues. These composites have been made by a number of manufacturing techniques. These include powder metallurgy, casting and spray deposition. The technique that has consistently produced high property composites has been powder metallurgy. Recent work in this area has been on refining techniques that offer lower cost manufacturing. Scale-up of facilities to produce vacuum hot pressed composite billets has been completed with the help of DOD funds through a Defense Procurement Act Title 3 program. Several companies have been working with a CIP-Sinter process to produce lower cost billet stock. This talk will review the recent cost reduction programs and the implications of these programs on the commercialization of these composites.
9:50am CHARACTERIZATION OF CulCu,O COMPOSITES PRODUCED BY ELECTROCHEMICAL DEPOSITION: F. S. Miller, D. C. VanAken, Dept. of Metallurgical Engineering, E. W. Bohannan and J. A. Switzer, Dept. of Chemistry, The University of Missouri, Rolla, MO 65409 Nanocrystalline composites of copper metal and cuprous oxide were produced at room temperature by electrodeposition from an alkaline copper lactate solution. The phase composition can be continuously changed by controlling the cathode current density. At current densities below 0.1 mA/cm2 nearly pure cuprous oxide is produced and at 2.5 mA/cm2 nearly pure copper is produced. At intermediate current densities composite structures are formed. These thin films show unique optical properties that are related to the 10 to 20 nm grain diameter of Cu20 produced by electrodeposition. During deposition of the composite material the electrode potential oscillates spontaneously at fixed current density. Microstructural information obtained by TEM indicates the formation of a metastable compound that may be related to the electrode potential oscillations. This work has been funded in part by the National Science Foundation under contract DMR-92-02872.
9:00am SYNTHESIS OF INTERMETALLIC-CERAMIC COMPOSITES BY A NOVEL PROCESSING TECHNIQUE: K. Raviprasad, Toyohashi University of Technology, Dept. of Production Systems Eng., Tempaku-cho, Toyohashi,441,Japan The requirement of different kinds of materials having desired properties has led to the development of non-equilibrium processing techniques. Recently, it has been shown that metal-intermetallic composites can be synthesized easily by heat treating prior rolled dissimilar metal foils. The synthesis of metalintermetallic composite is an attempt at bestowing materials with dual advantage of room temperature ductility of metals and the high temperature strength of intermetallics. The same technique can be applied effectively for the synthesis of intermetallic-ceramic composites. The present study reports the results of the synthesis of intermetallic-ceramic composites (FeAI-Alp3' Fe3AIAIP3' NiAI-AIP3 and Ni3AI-AI2 0 3) by rolling Fe or Ni foils with partially oxidized Al foils and following it by suitable heat treatment to produce the intermetallic compound. The materials are characterized by hardness, X-ray diffraction, SEM and TEM. The many fold advantages of the technique are that the volume fractions of the intermetallic and ceramic phases are easy to control and producing the final product without any size limitations in the bulk form.
10:15 am BREAK 10:25 am SPATIALLY VARIED INTERFACES AS A PROBE OF INTERFACE FAILURE MECHANISMS IN Ti-MATRIX COMPOSITES: Benji Maruyama, Wright LaboratorylNIST, 2230 10th ST STE 1, WPAFB, OH 45433; Douglas B. Gundel, Systran Co., Inc., 4126 Linden Ave., Dayton, OH 45432; Sunil Warrier, Universal Energy Systems, 4401 Dayton-Xenia Rd., Dayton, OH 45432 Spatially Varied Interfaces is a design concept for composite synthesis whereby the interface mechanical response is tailored to the composite needs by varying the interface properties in patterns of weak and strong areas. In the SiCfl Ti-alloy system, random patterns have been fabricated, along with bands, longitudinal stripes and helices. To be presented are results of transverse tensile and longitudinal fatigue crack growth experiments where selected regions of the interface are systematically strengthened or weakened, and the perturbation of the failure process is measured to gain a better understanding of the stress states and interface failure mechanisms. This work was con-
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ducted in the Metals & Ceramics Division of the Materials Directorate at Wright Laboratory.
ture toughness studies. This work was performed at Materials Directorate Wright Laboratory, Wright-Patterson AFB, OH.
10:50am THE PROPERTIES AND MICROSTRUCTURE OF AI-BASED COMPOSITES REINFORCED WITH CERAMIC PARTICLES: M. Samgorinski, S. Grenier, A. Cavasin, T. Brzezinski, G. Kim, P.G. Tsantrizos, PERMA, 1744 William, Montreal, Quebec, Canada H3J lR4
ALUMINUM DROSS & SALT CAKE PROCESSING Sponsored by: EPD Extraction and Processing Division Program Organizer: Annette Revet, IMC Kalium Belle Plaine, P.O. Box 7500, Regina, SK S4P
AI-based composite materials which were produced by Powder Metallurgy (PM) and Vacuum Plasma Spraying (VPS) are presented in this article. The objective was to produce materials with low coefficients of thermal expansion (CTE), tailored to approach that of steel (= 13 x 10-6 KI), and to improve the mechanical properties of the matrix. Composite materials based on Al are used in different fields where weight and thermal stability are key requirements, such as aerospace components, electronic packaging, high precision instrumentation, and automobile engine components. The nature, size and the relative quantities of the different reinforcing phases were considered in calculations involving the optimization of the main characteristics of the composites. Fine dispersed powders (5-20 11m) of Si,N., AlN, TiB" Alp" 2AI,o,.2SiO" B.C and SiC were used as the strengthening phases, while pure AI, 6061 and Al-Si alloy were used as the matrix. The dimensional and relaxation stability were investigated for several composites. The influence of plastic deformation and heat treatment on the structure and properties of VPS deposited composites were also investigated. It was found that a combination of plastic deformation and heat treatment (annealing or quenching with aging) increased the mechanical properties, on average, by a factor of 1.5 to 2.
Thursday, AM February 13, 1997
Session Chairs: Annette Revet, IMC Kalium Belle Plaine, P.O. Box 7500, Regina, SK S4P; John Hryn, Argonne National Labs, 9700 South Cass Avenue, Argonne, IL 60439-4815
8:30am ANALYTICAL CHEMISTRY OF ALUMINUM SALT CAKE: Donald G. Graczyk, Alice M. Essling, Edmund A. Huff, Florence P. Smith and Christine T. Snyder, Argonne Chemistry Laboratory/Chemical Technology Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 8:50am QUANTIFYING THE AMOUNT OF OXIDES IN ALUMINUM: D. L. Stewart Jr., K. M. Tomaswick, Alcoa Technical Center, Alcoa Center, PA 15065 9:10am EXPERIMENTAL STUDIES OF PHASE RELATIONS IN THE SYSTEM H,O-NaCl-KCI-MgCI" WITH APPLICATION TO A NEW PROCESS FOR TREATING SALT CAKE: Robert J. Bodnar, Maxim O. Vityk, Fluids Research Laboratory, Department of Geological Sciences, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061; John N. Hryn, Argonne National Laboratory, Energy Systems Division, 9700 S. Cass Avenue, Argonne, IL 60439; John A. Mavrogenes, Research School of Earth Sciences, The Australian National University, Canberra, Australia 0200
11:15 am EFFECT OF MICROSTRUCTURAL ARRANGEMENT ON THE MECHANICAL PROPERTIES OF Nila-AIz03 METAL-CERAMIC COMPOSITES: E.D. Rodeghiero, E.P. Giannelis, Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853-1501 The degree to which a ductile metallic phase can be used to toughen brittle ceramic materials is highly dependent on the microstructural dispersion of the metallic constituent, the metal's aspect ratio and characteristic size, and the amount of constraint imposed on the metal by the ceramic matrix. This talk will focus on the effect of these parameters on the mechanical properties, and in particular the fracture toughness, of Nila-AI,O, composites prepared through both in-situ and conventional approaches. The composites discussed will vary from particulate toughened cermets prepared from chemical and/or powder approaches to complex, anisotropic materials containing Ni foils or fibers. Through evaluation of the experimental evidence and theoretical models, the optimum microstructural arrangement of the Ni phase in the a-AI,O, matrix will be presented.
9:30am CONCENTRATION AND PRECIPITATION OF NaCIAND KCI FROM SALT CAKE LEACH SOLUTIONS BY ELECTRODIALYSIS: Kandipati Sreenivasarao, Filippos Patsiogiannis, John N. Hryn and Edward 1. Daniels, Energy Systems Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439 9:50 am BREAK 10:00 am THE EVOLUTION OF ROTARY MELTING AT RECYCLAGE D' ALUMINUM QUEBEC INC.'S: DIVISION OF PHILIP ENVIRONMENTAL INC.: TWO ALUMINUM DROSS PROCESSING PLANTS: Michael W. Paget, Recyclage D' Aluminum Quebec Inc., 128 Blvd. Comeau, Baie Comeau, QB G4Z 2L6; James F. Heffron, Air Products and Chemicals, Inc., R&D #2, 7201 Hamilton Blvd., Allentown, PA 18195; Pierre Richer, Air Products and Chemicals, Inc., 2090 Steeles Avenue, Brampton, ON L6T lA7
11:40 am FRACTURE TOUGHNESS OF SILICON CARBIDE PARTICULATE REINFORCED ALUMINUM ALLOY COMPOSITES: A.B. Pandey, Materials Directorate Wright Laboratory, WLlMLLM, Wright-PattersonAFB, OH 45433 and Systran Corporation, 4126 Linden Avenue, Dayton, OH 45432; B. S. Majumdar, UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432; D.B. Miracle, Materials Directorate Wright Laboratory, WLIMLLM, WrightPatterson AFB, OH 45433 This study is part of an overall effort to optimize the strength toughness combination in discontinuously reinforced aluminum (DRA) composites for application in aerospace structures. Two different matrix alloys were considered, namely Al-2009 and AI-7091, to represent intermediate and high strength matrices, respectively, and they were reinforced with SiC particles of 4.9 and 10.4 mm. The powders were consolidated directly via blind-die extrusion, thus reducing processing time significantly from conventional vacuum hot pressing techniques. Fracture toughness tests were performed with precracked bend bars, and the J-resistance curves were determined. Damage modes were evaluated in both tensile and fracture toughness samples, in an attempt to understand the factors that may provide intrinsic toughness improvement without significant loss of strength. The mechanical properties and damage modes were compared with control samples of unreinforced materials fabricated using an identical processing route as the composites. Data from these control materials provided an added insight that has often lacked in past frac-
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Room: 231C Location: Orlando Convention Center
10:20 am COMPLETE ALUMINUM DROSS PROCESSING TECHNOLOGY: Peter G. Schirk, CHMM, Director of Engineering & Special Projects, ALTEK International, Inc., 585 Exton Commons, Exton, PA 19341 10:40 am A NEW CONCEPT FOR DIRECT DROSS TREATMENT BY CENTRIFUGING OF HOT DROSS IN COMPACT TYPE ECOCENT MACHINES: Bernd Kos, PhD., FOCON GES.M.B.H. Foundry Consultants, Endresgasse 11, A-8700 Leoben, Austria
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11:00 am SALT-FREE DROSS PROCESSING WITHALUREC® - TWO YEARS EXPERIENCE: Henrik Gripenberg, M,Sc" AGAAB, S-181 81 Lidingo, Sweden; Michael Miillerthann, DipL-Ing" HoogovensAluminium Hiittenwerk GmbH, Schleusenstrasse, D-46562 Voerde, Germany
nism and that the travelling wave instabilities are distinct to those uncovered in previous investigations. We also derive a simple yet general energy criterion which shows which types of motion may extract energy from the background magnetic field. This indicates that a rotating tilted interface is particularly prone to instability, and indeed such motions are often seen in practice.
ALUMINIUM REDUCTION TECHNOLOGY VII: Modelling
SIMULATION OF THE DYNAMIC RESPONSE OF ALUMINIUM REDUCTION CELLS: [mad Tabsh, COMPUSIM Inc., lOO3D 55 Avenue N.E., Calgary, Alberta, Canada T2E 6Wl; Marc Dupuis, GeniSim, 3111 Alger, Jonquiere. Quebec, Canada G7S 2M9
9:45am
Sponsored by: LMD Aluminum Committee Program Organizer: Harald A. 0ye, Institute of Inorganic Chemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway Thursday, AM February 13, 1997
A comprehensive program (ARC/Dynarnic) was developed to simulate the dynamic behavior of aluminium reduction cells during operation. The program uses the mass and energy balance equations to determine the transient evolution of more than 60 process variables. In addition, it simulates various operational and control policies in use during cell operation. This paper describes the use of ARC/Dynamic to study the sensitivity of the cell response to variations in the input parameters. It also looks at the cell performance under various amperage curtailment conditions such as sudden shutdown of the line or scheduled reduction in line amperage. A detailed description of the amperage fluctuation model implemented in the program is presented.
Room: 230A Location: Orlando Convention Center
Session Chairperson: Halvor Kvande, Hydro Aluminium, Hydro Aluminium a,s, P.O, Box 80, 1321 Stabekk, Norway
8:30am APPLICATIONS OF NEW STABILITY CRITERIA TO INDUSTRIAL CELL DESIGN: R.1. Lindsay, P.A. Davidson, Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, CB2 IPZ, UK
10:10 am BREAK 10:30 am MATHEMATICAL MODELLING OF CURRENT DISTRIBUTION AND ANODE SHAPE IN PREBAKE ALUMINIUM CELLS: J. Zoric, I. Rousar, Department of Inorganic Technology, Institute of Chemical Technology, 16628 Prague 6, Czech Republic; J. Thonstad, Department of Electrochemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway
Previous models of the behaviour of interfacial waves in aluminium reduction cells lead to distinct descriptions of the physical mechanisms involved and different stability criteria. We consider the implications of these criteria for cell design. A new wave equation has recently been developed from shallow-water theory, in which the Lorentz force is expressed explicitly in terms of the fluid motion. The simplicity of this new equation leads to a general energy criterion to establish which types of motion may be unstable. By expressing the new equation in matrix form, we obtain some unexpected results. We discuss the implications of some of these results for cell design. Finally, we introduce a new sufficient condition for the stability of standing waves in a finite domain, which does not require solving the governing equations. The use of Gershgorin's theorem allows us to place a lower bound on the critical value of the background magnetic field at which an instability first appears.
1\\'0 approaches were used to determine the current distribution in aluminium cells with prebaked anodes, i.e., primary and secondary current distribution, the latter giving far more realistic results. Current densities obtained for secondary current distribution were used to model the changes in anode shape from the time when a new anode has been set until it achieves the typical rounded off steady state profile. Mathematical modelling of the anode consumption using current densities obtained by the solution of the Laplace equation in 2D space, showed that a constant shape was reached after 6 - 8.6 days, depending on the width of the gap to a neighbouring anode or to the sidewalll side ledge. The calculated steady state shapes were similar to the shapes of anodes taken out of a cell. The current density decreases up along the side of the anode from the nominal value at the underside (0.75 A cm,2) to a minimum near the surface of the electrolyte (0.08 - 0.28 A cm,2), depending on the geometry. The percentage of the current which passes through the sides of the anodes is of the order of 15%. The current density on the anode side facing the periferic channel increases with increasing distance to the sideledge, while the exact shape of the ledge makes little difference. The cathodic current density in the periferic channel goes down to 0.07 A cm,2 for a 30 cm wide channeL
8:55am MAGNETOHYDRODYNAMIC EFFECT OF ANODE SET PATTERN ON CELL PERFORMANCE: M. Segatz, Ch. Droste, D. Vogelsang, VAW Aluminium-Technologie, G.-v.-Boeselager-Str. 25, D-53117 Bonn, Germany Numerical simulation of coupled bath/metal magnetohydrodynamics (MIlD) and MIlD stability analysis allows the optimization of anode set pattern with respect to minimal cell disturbance. The contribution of anode gas induced forces and impact on the flow field are discussed. During a complete anode set cycle the anode current distribution changes significantly due to varying anode resistances, frozen bath and different metal pad heights. Typically the largest disturbance to cell stability occurs during a short time span after the anode change. With steady-state MIlD simulations immediately before and after each anode change - in sequence of the underlying set pattern - the relevant cell current and ACD distribution are determined. The impact of these parameters on cell stability is predicted with a linear MIlD stability analysis for a complete anode change cycle.
10:55 am MATHEMATICAL MODELLING FOR COKE BED PREHEATING OF ALUMINIUM REDUCTION CELL: Shaher A. Mohammed, R&D Dept., Aluminium Company of Egypt, Nagi-Harnmadi, Egypt; Maher M. Abdulwahab, AttiaA. Arif, Omar M. Dahab, Power and Energy Dept., Minya University, Egypt
9:20am
Many methods are available to preheat and bake-out the cathodes of aluminium reduction cells but only few of them are widely used. Resistor coke bed with shunt rheostat is one of the most common methods to preheat the celL To get optimum design parameters for resistance elements and preheating method, a finite element model was built to simulate the process. The effect of starting current, coke bed thickness, rate of increase of current and finally total time needed for preheating, were studied. The obtained results indicated that the practical technique used has to be subjected to some modifications in order to reach satisfactory conditions.
A NEW MODEL OF INTERFACIAL WAVES IN ALUMINIUM REDUCTION CELLS: P. A. Davidson, R.I. Lindsay, Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, CB2 IPZ, UK We develop a new wave equation for the liquid interface in aluminium reduction cells. It differs from previous models in that the Lorentz force is expressed explicitly in terms of the fluid motion. The equation is valid both for open domains and confined domains of arbitrary shape, and its simplicity makes the instability mechanism explicit. Our new equation predicts that both travelling waves and standing waves may become unstable by the same mecha-
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11:20 am
chanical properties that rival and often exceed corresponding properties of other technologies like hot isostatic pressing (HIP) and related processes. This process offers many advantages that will be described in the paper in addition to presenting case histories of property enhancement by PIF, and the mechanism for responsible property enhancement.
HIERARCHICAL INTELLIGENT CONTROL SYSTEM FOR ALUMINUM REDUCTION CELLS: lie Li, Yexiang Liu, Jin Xiao, Department of Metallurgy, Central South University of Technology, Changsha, Hunan 410083, China; Feng Wang, Shengwen Shi, Department of Technology, Liancheng Aluminum Plant, Lanzhou, Gansu 730335, China
9:00am TENSILE PROPERTIES OF 319 ALLOY CASTINGS: S. Viswanathan, W. Ren, Metals and Ceramics Division, Oak Ridge National Labs, Oak Ridge, TN 37831-6083, G.B. Ulrich, Y-12 Plant, Oak Ridge, TN 37831-8096; M.E. Hoover, General Motors Powertrain Division, Saginaw, MI 48605-5073
A hierarchical intelligent control system for aluminium reduction cells has been developed. There are two intelligent levels in the system. The higher level built on the principle of neural network expert system, aims at analyzing medium and long-term change trends of the state of the process, calculating settings for the lower level, interacting with operators and offering operation proposals. The lower level, composed of several subsystems which are set up on the principle of fuzzy control and expert control, is used to realize short-term analyses and real-time control of the process. As the system has a hierarchical and modular structure, its design, realization and testing are simplified. Test-run results verified that, combined together in one system, the controllers have good properties of robustness and adaptability with respect to changes of operating conditions and severe disturbances.
Plate castings of 319 alloy were made over a wide range of thermal conditions by casting in sand molds, molds with end chills, and molds with top, bottom, and end chills. The plates were sectioned along their width into coupons. Odd-numbered coupons were machined into tensile specimens and tested in the as-cast condition. Even-numbered coupons were heat treated to a T6 condition, and then machined and tested. Yield strength, Ultimate tensile strength, and ductility measured by percent elongation were plotted with respect to distance from the chill end of the plate as well as related to porosity and other microstructural features such as dendrite cell spacing. The data shows that tensile elongation is a strong function of porosity. In particular, the data indicates a threshold value of porosity below which a sharp increase in ductility is observed. These effects as well as the effect of heat treatment and dendrite arm spacing are discussed. *Research sponsored by the U.S. Department of Energy Defense Programs, Assistant Secretary, Technology Management Group, Technology Transfer Initiative under contract DE-AC05960R22464 with Lockheed Martin Energy Research Corporation.
11:45 am DETERMINATION OF METAL CURVATURE AND IMPROVED ANODE CONSUMPTION: Jon H. Stefansson, Electrolysis Department, Icelandic Aluminium Co. Ltd., IS-222 Hafnarfjordur, Iceland; Rene von Kaenel, Jacques Antille, Technology Center Chippis, Alusuisse Technology & Management Ltd., CH-3965 Chippis, Switzerland The Alusuisse ISAL smelter in Iceland does not have an in house anode plant. This makes it increasingly important to operate with small and evenly thick anode butts. Since the insertion height is calculated according to the carbon burning rate, it is important to know the difference in metal level according to the position in the pots. Two methods have been used to determine the metal upheaval. The first consists in measuring the height of many enough anode butts since the lower anode level adjusts to the metal level with time. The second method is based on mathematical modelling. Measured values have been compared to calculated values with good agreement. Insertion of the anodes according to metal level has resulted in improved gross anode consumption due to more even butt thickness and stable operation.
9:30am RECENT DEVELOPMENTS IN SQUEEZE CASTING OF MAGNESIUM ALLOYS AND THEIR COMPOSITES: Henry Hu, Alan Luo, Institute of Magnesium Technology (ITM, Inc., Ste-Foy, Quebec, Canada GIP 4N7 Squeeze casting, also known as liquid metal forging, extrusion casting and pressure crystallization, is a process in which molten metal solidifies in a die under an applied high pressure. The concept of squeeze casting was invented in Russia over 100 years ago. Later the process has been exploited in North America, Japan and Europe to produce various automotive components. With the rapid expansion of magnesium applications in the automotive industry, the development of squeeze casting technology for magnesium alloys and their composites has been motivated by incentive to produce high quality magnesium-based components. The present paper reviews recent progress in squeeze casting of magnesium alloys and magnesium-based composites. The effects of process variables on the cast structure and properties of magnesium alloys and magnesium-based composites are discussed. The significant advantages of squeeze cast magnesium alloys and magnesium-based composites are highlighted. The ongoing research work at ITM is presented.
AUTOMOTIVE ALLOYS III: Castings Sponsored by: LMD Aluminum Committee Program Organizers: Dr. Subodh K. Das, ARCO Aluminum, Inc., P. O. Box 32860, Louisville, KY 40232; Dr. George J. Kipouros, Technical University of Nova Scotia, Department of Mining and Metallurgical Engineering, P. O. Box 1000, Halifax, Nova Scotia, Canada B3J2X4 Thursday, AM February 13, 1997
Room: 340A Location: Orlando Convention Center
10:00 am
Session Chairperson: Carl Seidler, Technical Service Manager, ARCO Aluminum, Inc., P.O. Box 32860, Louisville, KY 40232
CAST ALUMINUM-FLY ASH COMPOSITES FOR ULTRALIGHT AUTOMOTIVE APPLICATION: P. K. Rohatgi, R.Q. GUO, Department of Materials, University of Wisconsin, Milwaukee, WI 53211
8:30am
Coal fly ash, an industrial waste by-product, is produced during combustion of coal by thermal power plants. Additions of solid or hollow particles of fly ash into aluminum melt by common foundry techniques reduce the cost and density of aluminum castings while increasing their performance. Fly ash particles are very light materials with density around 2.1 to 2.3 g/cmJ for solid fly ash particles and a density as low as 0.4 to 0.8 g/cmJ for the cenospheres of fly ash which are hollow. In this paper, manufacture and some properties of aluminum-fly ash composites (Ashalloy) have been studied. Aluminum alloy-fly ash (Ashalloy) represents a candidate ultralight material for automotive application. Incorporation of cenosphere fly ash particles, which are hollow with very low density, significantly reduces the density of material. Some of the characteristics of fly ash used for making composite have been described. The fly ash particle shape, size, and density have been determined. Mechanical properties of aluminum alloy - fly ash composites made by stir casting show that the composites have similar hardness, elastic modulus as matrix aluminum alloy, and improved wear abrasive resistance compared to the matrix alloy. Several prototype components of alumi-
A NEW CASTING DEFECT HEALING TECHNOLOGY: Edwin S. Hodge, Thomas W. Reddoch, Format Industries, Inc., Knoxville, TN; Srinath Viswanathan, Oak Ridge National Laboratory, Oak Ridge, TN A new technology is presented for healing of defects in 356 and 201 Aluminum alloys that provides economic upgrading of these cast alloys. This technology uses pneumatic isostatic forging (PIP) to provide a unique capability to produce high quality Aluminum alloy products with enhanced mechanical properties that are uniform throughout the part thus permitting higher design allowables and increased usage of Aluminum alloy castings. The fundamental mechanism underlying PIF is a single mode plastic deformation process that uses isostatic application of pressures for 10 to 30 seconds at temperature. The process can be integrated in-line with other production operations, i.e., using the latent heat from the previous casting step. The results of applying the PIP process indicate lower cost and significant improvement in me-
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num - fly ash composites for automotive applications, small engine and electromechanical machinery have been made and are under trials.
carbon materials. Little has been done to improve the main raw material, ECA. The characteristics of ECA can be strongly affected by calcining conditions and selection of raw anthracites. In this study, different ECA qualities were produced in full scale calciners and the effect of improved ECA quality on cathode materials studied. A lab scale test program was established to evaluate the effect on different baked properties. Important properties for improved cathode performance, like sodium resistance, electrical conductivity and mechanical properties, can be effected by use of selected ECA.
10:30 am BREAK 11:00 am EFFECT OF SECTION THICKNESS AND GATE VELOCITY ON EVOLVED MICROSTRUCTURE AND MECHANICAL PROPERTIES OF HIGH PRESSURE DIE CAST MAGNESIUM ALLOY AZ9ID: Winston P. Sequeira, Gordon L. Dunlop, CRC for Alloy and Solidification Technology (CAST), The University of Queenland, St. Lucia, Qld 4072, Australia, Morris T. Murray, CSIRO Division of Manufacturing Technology, Preston, Vic 3072, Australia
8:55am HIGH PERFORMANCE TECHNOLOGY FOR THE PREPARATION OF CARBON PASTE FOR CATHODES AND GRAPHITE ELECTRODES: Berthold Hohl, Machinenfabrik Gustav Eirich, 0-74732 Hardheim, Federal Republic of Germany
This paper investigates the change that occurs in microstructure and mechanical properties when the section thickness is varied for high pressure die cast Mg alloy AZ9ID. It has been found that yield and ultimate tensile strength increase more than would be expected with decreasing section thickness. This is explained in light of the fine microstructure in the surface layer (skin) that develops during the rapid solidification that occurs in this process. The two stage solidification sequence which leads to the evolution of the unique microstructure in die castings has been supported by evidence from solidification experiments using wedge castings and computer simulation of the shot sleeve. Two different die castings with relatively thick cross sections have been compared in terms of their porosity content and its effect on mechanical properties. Finally, the effects on mechanical properties of thick and thin specimens due to variation of casting parameters such as gate size is also discussed.
The preparation of carbon paste for manufacture of cathodes and graphite electrodes requires the heating-up of the raw materials as well as the following mixing and cooling of the paste. In the last few years, a newly developed plant type has proved successful in practical operation. It consists mainly of an electric resistance heater and a high-performance mixer. The coke fractions are heated up to temperatures between 150 - 200°C by the resistance heater and fed into the high-performance mixer along with liquid pitch. After completed homogenization of the components, the temperature required for the moulding is achieved with greatest accuracy by addition of water and evaporation cooling. One single machine of this type replaces 8-12 conventional batch mixers. The special merits of this process are the minimal maintenance compared to conventional techniques, the reduced energy consumption, the shortened cycle time and the considerably improved environmental protection. The plant is a closed system; dusts and steams are purified in an exhaust air decontamination plant and partially reused. The plant flexibility makes it possible to prepare carbon paste for both cathodes and graphite electrodes with exactly the same equipment by only simply changing the recipe. As an example, the latest state of the art is presented as well as the most significant operating results by means of a plant which was commissioned in 1995 at a great international manufacturer of carbon and graphite products.
11:30 am DUCTILE PRESSURE DIE CASTING FOR AUTOMOTIVE APPLICATIONS: A STATUS REPORT: Hubert Koch, Alois J. Franke, Aluminum Rheinfelden, GmbH, P. O. Box 1140, 0-79601 Rheinfelden, Germany After three years of commercial application of low iron pressure die casting alloys for structural parts, this paper reviews industrial scale experience and looks out to further potential in alloy development. Silafront-36™ (AA 365) and Magsimnl-59 ™both have an iron content below 0.13 wt% ensuring good ductility of the casting while completely avoiding soldering or sticking to the die in manufacturing. This is a breakthrough in pressure die casting where during decades the soldering problem has prevented the application of ductile casting alloys. Silafront-36™ (AA 365) and Magsimal-59™ are used for suspension parts, steering wheels, space frame nodes, motor mounts etc. High pressure die casting and squeeze-casting are the processes applied. Silafront36™ is an AlSi9Mg-type alloy that can be heat treated and welded. Magsimal59™ is of the AlMgMnSi-type and specially designed for applications without heat treatment with extraordinary mechanical and dynamic properties. This paper describes the manufacture of the castings, the application and component properties for both alloys.
9:20am THE OXIDATION OF HETEROGENEOUS CARBON ELECTRODES AND FURNACE LINERS - PART 1: X-RAY DIFFRACTION APPLICATIONS: F. Hiltmann, SGL Carbon AG, Frankfurt-Griesheim, Germany; BJ. James, B.J. Welch, M.M. Hyland, Department of Chemical and Materials Engineering, The University of Auckland, New Zealand The primary purpose of this study is to fully understand the role played by oxidation reactions in the degradation of carbon cathodes and furnace liners such as those used in aluminium smelting cells. While we have developed a sensitive technique for detecting oxidation at low rates, full mechanistic understanding is dependent on supplementary characterisation of the residual unreacted materials. This is complicated by the heterogeneous nature of the electrode materials. This paper presents details of the application of X-ray diffraction for studying the various component materials of these composites, namely pitch, graphite and anthracite. Also presented in this paper is supporting compositional analysis of the heterogeneous carbon samples together with element maps to indicate the distribution of typical trace elements.
CARBON TECHNOLOGY V: Cathode Sponsored by: LMD Aluminum Committee Program Organizer: Jean-Claude Thomas, Aluminium Pechiney, Pechiney/Balzac, 92048 Paris la Defense, France Thursday, AM February 13, 1997
9:45 am THE OXIDATION OF HETEROGENEOUS CARBON ELECTRODES AND FURNACE LINERS - PART II: OVERALL REACTIVITY CORRELATIONS: B.J. James, BJ. Welch, M.M. Hyland, Department ofChemical and Materials Engineering, the University of Auckland, New Zealand; F. Hiltmann, SGL Carbon AG, Frankfurt-Griesheim, Germany
Room: 230C Location: Orlando Convention Center
Session Chairperson: Andre L. Proulx, Alcan International Limilee, 1955 Boulevard Melion, C.P. 1250, Jonquiere, Quebec, Canada G75 4K8
Using the method described previously (Light metals, 1996) the oxidation reactions of carbon cathode materials have been characterised for onset temperature and rate of oxidation at low (less than 550°C) temperatures. Combining the results of composition and structural analysis described in Part I correlations have been made between the inherent structure of the component materials and their onset temperature and relative rates of oxidation thus explaining the preferential nature observed in the oxidation of composite samples. Using the results of polarised light microscopy and scanning electron microscopy the relationship between bulk structure of the heterogeneous samples
8:30am ECA FOR IMPROVED CATHODE PERFORMANCE: Johan A. Johansen, Herman Gran, Elkem Carbon, P.O. Box 8040, Vagsbygd, N-4602 Kristiansand,Norway ECA (Electrically Calcilled Anthracite) is the main raw material for the carbon part of the electrolysis cells. Demand for increased potlife and more efficient cathodes (lower voltage drop) have led to use of more graphite in the
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and their oxidation reactions has been examined with important implications for the performance of these materials in service.
profiles were derived from etch lines achieved from real castings. The flow patterns were studied for different metal distributors comprising horizontal, vertical, inclined spouts and diffusor bag. The effect of the different flow patterns is correlated with results of metallographic analysis. The experiments are reviewed by some aspects of numerical simulation. The results show that physical modelling remains an instructive tool to study the dynamic behaviour of transient flow phenomena.
CAST SHOP TECHNOLOGY VIII: D.C. Casting Sponsored by: LMD Aluminum Committee Program Organizer: Wolfgang A. Schneider, VAW aluminium AG, Research and Development, Georg-von-Boeselager-Str.25, 0-53117 Bonn, Germany Thursday, AM February 13, 1997
9:30am PHYSICAL AND MATHEMATICAL MODELING OF METAL DELIVERY DEVICES FOR EM AND DC CASTING OF ALUMINUM: Dong Xu, J. W Evans, Dept. of Materials Science and Mineral Engineering, University of California, Berkeley CA 94720; Daniel P. Cook, Corporate Research & Development, Reynolds Metals Company, Richmond, VA 232617003
Room: 230B Location: Orlando Convention Center
Session Chairperson: Robert B.wagstaff, Wagstaff, N.3910 Flora Rd., Spokane, WA 99216
A half-section water model of a pilot scale caster (at RMC, Richmond, Virginia) has been constructed at UC Berkeley. A particle imaging velocimetry (PIV) system has been assembled to measure velocities in the model for various simulated nozzle and bag geometries. The PIV system is a relatively inexpensive system using an incandescent light source, rather than the usual high-power laser. A digital camera, microcomputer and software (Optical Flow Systems) track the frame-to-frame movement of neutral-density particles in the water and provide vector maps of the velocity. Measured velocities have been compared to velocities computed using the finite element package F1DAP and show good agreement.
8:30am COMPREHENSIVE EVALUATION OF THREE REFRACTORY MATERIALS FOR HOT-TOP BILLET CASTING SYSTEMS AT GOLDENDALE ALUMINUM COMPANY: J. Martin Ekenes, Consultant, N .3418 Arden Road, Otis Orchards, WA 99027; Larry Bennett, Goldendale Aluminum Company, Craig Johnson, Permatech Inc. The life of refractory components in billet hot-top casting systems is often the factor limiting mold package life. Evaluation of new materials in commercial casting operations requires careful planning in order to assure integrity in data collection. A full scale test spanning a five month period was conducted at Goldendale Aluminum Company comparing two silica based precision castable refractories and a graphite reinforced calcium-silica board. Comprehensive records facilitated testing a variety of hypotheses. This paper describes plan development, implementation, data collection, analysis, and the conclusion drawn.
9:50am INFLUENCE OF FLUID FLOW FIELD AND POURING TEMPERATURE ON THERMAL GRADIENTS IN THE MUSHY ZONE DURING LEVEL POUR CASTING OF BILLETS: G.-U. Gran, w. Schneider, YAW aluminium AG, Research and Development, Georg-von-BoeselagerStr.25, D-53117 Bonn, Germany The occurrence of feathery crystals during experimental casting trials on a level pour casting unit yields a strong relationship as well to the pouring temperature as to the governing fluid flow pattern within the liquid melt pool of the billet. Three-dimensional simulations of the coupled fluid flow and heat transfer problem during the stationary phase of the level pour casting process are used to investigate the variations of the thermal field in the liquid part of the solidifying billet. The calculated flow field patterns and temperatures are discussed in dependency of casting velocity, pouring temperature and size of pouring gate. The resulting thermal gradients in the mushy zone over the circumference of the billet are correlated to microstructure analysis of the corresponding casting trials.
8:50am CALCIUM CONTAMINATION OF MOLTEN AI-Mg ALLOYS BY CALCIUM CARBONATE POWDER: Dennis D. Yancey, Dept. of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; David H. DeYoung, Aluminum Company of America, Molten Metal Processing Center, Alcoa Technical Center, Alcoa Center, PA 15069 A bench-scale study has been conducted to determine the effects of melt temperature, alloy composition, and powdered calcium carbonate quantity on Ca contamination of molten AI-Mg alloys. Calcium carbonate powder is often used in ingot plants as a "caulking" material in troughs, joints, etc. to prevent molten metal leaks. Results of the study show that: (i) at melt temperatures above 1425°F, calcium carbonate markedly increases the concentration of Ca in molten AI-4.5 wt% Mg alloy; (ii) Mg is required for the reaction of CaC03 with the aluminum melt to occur; (iii) for a given quantity of calcium carbonate, within the temperature range of 1400-1550°F, increase in melt temperature increases Ca contamination; (iv) for a given temperature of 1450°F or 1550°F and within 0.008-0.36 wt% CaC03, increase in the quantity of calcium carbonate markedly increases both the rate of Ca contamination and the maximum concentration of Ca obtained in the melt for a 5 hour interaction period. The decomposition of calcium carbonate and the associated Ca contamination of moltenAI-Mg alloy appears to be a kinetically-driven phenomenon.
10:10 am BREAK 10:10 am OPEN MOLD WITHOUTDISTORSION FOR ALUMINUM DC CASTING: MODELING AND TESTING THE OPTIMUM SHAPE AND MATERIAL: B. Hannart, Pechiney Rhenalu, Centr' Alp-BP24, F-38340 Voreppe, France; O. Bonnet, Pechiney CRY, Centr' Alp-BP27, F-38340 Voreppe, France; A. Noraz, Aluminium Pechiney, Centr' Alp-BP27, F-38340 Voreppe, France The thermomechanical behaviour of open molds used for DC casting of aluminum slabs was analysed, and their design was optimized, in order to avoid thermal distorsion. The analysis used a thermomechanical finite element model, describing the mold geometry, the material properties, and the heat transfer between mold, molten metal and cooling water. The deformations observed during and after the casting were realistically reproduced, both in 3D and in 2D. The 2D model, allowing to test new designs in less than 10 minutes, was used to propose several solutions for reducing the residual distorsion of the mold. The different solutions were tested in industrial conditions at Aluminium Dunkerque, and mold distorsions were systematically measured. With the optimum choice of mold geometry and alloy, the residual distorsion was completely eliminated.
9:10am INVESTIGATION OF THE EFFECT OF DIFFERENT METAL FEEDING SYSTEMS ON CAST STRUCTURES USING A WATER MODEL: A. Buchholz, S. Engler, M.-S. Ji, W. Schmitz, Foundry Institute, RWTH Aachen, Intzestr.5, D-52056 Aachen, Germany Forced convection imposed by the feeding system plays an important role in the solidification of continuous casting processes. Convection modifies heat and mass transport and thus has a significant impact on the cast structure. A better understanding of the fluid dynamics promises an improvement of continuous casting processes. To investigate flow patterns and the influence of different inlet systems on cast structures a water model was designed maintaining dynamic similarity between model and real casting equipment. Sump
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11:40 am 3D ANALYSIS OF EM SEMI-LEVITATING AND FREE SURFACE PROBLEMS: M. Ramadan Ahmed, Aluminum Co. of Egypt, 48/50Abd EIKhalek Sarwat St., Cairo, Egypt; S. EI-Masry, Faculty of Engineering & Technology, Helwan, Egypt; Fawaz Moustafa, Ibrahim Moustafa, Egyptalum Company, Nag Hammady, Egypt
10:40 am DIRECT CHILL CASTING OF ALUMINUM ALLOYS: INGOT DISTORSIONS AND MOLD DESIGN OPTIMIZATION: J.-M. Drezet, M. Rappaz, Laboratoire de Metallurgie Physique, Ecole Polytechnique Federale de Lausanne, MX-G, CH-1015 Lausanne, Switzerland During the direct chill (DC) semi-continuous casting of aluminum alloys, the metal experiences high thermal stresses which are partially relaxed by deformation. This deformation is responsible for three main ingot distorsions: butt curl, butt swell and non-uniform rolling faces pull-in. These distortions are detrimental to the productivity of the process because they require butt sawing and more ingot scalping before rolling. On the other hand, residual stresses may induce longitudinal cracking of the cold ingots. Under pseudo steadystate conditions, i.e. after nearly one meter of casting, the solidified shell contracts towards the liquid pool (Pull-in). This contraction which amounts to about 9% at the lateral faces center is only 2% at the ingot corner. If a rectangular mold is employed, the resulting ingot is therefore concave ("bone shape"). To compensate for this non-uniform contraction of the ingot, the sides of the mold are designed with a convex shape, usually with three linear segments. Nevertheless, instead of producing flat rolling sheet ingots, such molds produce W-type ingot cross section. A comprehensive 3D mathematical model based upon the Abaqus software has been developed for the computation of the thermomechanical state of the solidifying strand during DC casting and subsequent cooling of rolling sheet ingots. Based upon a finite element formulation, the model determines the temperature distribution, the stresses and the associated deformations in the metal. This paper concentrates on the non-uniform contraction of the lateral faces and shows comparisons between computed and measured ingot cross-sections after complete cooling. Finally, the influence of the mold design on the final ingot crosssection is assessed and the use of an inverse method for mold design optimization is presented.
Developing an accurate mathematical model for the analysis of electromagnetic (EM) semi-levitating and free surface problems is still in the top of attentions for many researchers working in the field of the EM casting and others near-net-shape product applications. In this paper, a 3D iterative solution based on the Boundary Element technique coupled with a heat transfer analysis is derived for modeling an electromagnetic (EM) caster producing aluminum ingot installed in the Egyptalum Company. The main objective of this work is studying the effects of the EM screen location, the cooling system strategy and the melt withdrawal speed, and the effects of the estimated electrical setting parameters on the EM caster performance and its operation stability. The numerical results show that the location of the screen as well as the melt withdrawal speed have significant effects on the stability and the shape of the formed aluminum ingot. On the other hand, changing the supply frequency from 1500 Hz up to 2500 Hz increases the total electrical power consumed but it has no significant effect on the ingot shape. Finally, measurements showing a comparable reduction of 10% in the total electrical power consumed and a stable equilibrium free surface shape are recorded as the EM caster is tested, in the company, using those concluded setting parameters.
CHEMISTRY AND PHYSICS OF NANOSTRUCTURES AND RELATED NONEQUILIBRIUM MATERIALS VII: Electromagnetic Properties
11:00 am WATER COOLING IN DIRECT CHILL CASTING: CONTROL: John Grandfield, Comalco Research Centre, P.O.Box 316, Thomastown, Victoria 3074, Australia
Sponsored by: Jt. EMPMD/SMD Chemistry and Physics of Materials Committee, MSD Thermodynamics and Phase Equilibria Committee Program Organizers: Brent Fultz, 138-78, California Institute of Technology, Pasadena, CA 91125; En Ma, Louisiana State Univ., Dept. of Mechanical Eng., Baton Rouge, LA 70803; Robert Shull, NIST, Bldg. 223, Rm B152, Gaithersburg, MD 20899; John Morral, Univ. of Connecticut, Dept. of Metallurgy, Storrs, CT 06269; Philip Nash, Illinois Institute ofTechnology, METM Dept., Chicago, IL 60616
Water cooling plays an important role during DC casting. Control of the water cooling is essential for good process performance. In some cases the ability of the water cooling to remove heat limits productivity, and scrap can be generated due to variation in water cooling. The considerable work conducted to date on water cooling in DC casting is reviewed. The boiling theory is covered in a companion paper. Published measurements of cooling intensity and the affect of water cooling on the temperature distribution during casting are analysed. Various mold water system designs are discussed. The effect of variables such as water flow rate, impact velocity, composition, temperature etc are presented. Practical implications for controlling water cooling and the casting process are suggested.
Thursday, AM February 13, 1997
Room: 330C Location: Orlando Convention Center
Session Chairperson: Robert Shull, NIST, Bldg. 223, Rm B152, Gaithersburg, MD 20899
9:00 am INVITED RESISTANCE BEHAVIOR OF Cr-Si-O THIN FILMS: Alan F. Jankowski, Jeffrey P. Hayes, Ronald Musket, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94550; Frederic Cosandey, Chandrasekhar E. Goda, Rutgers University - College of Engineering, P.O. Box 909, Piscataway, NJ 08855; Ronald S. Besser, Victor Westedind and Gregory Cobai, Silicon Video Corporation, 6580 Via Del Oro, San Jose, CA 95119
11:20 am CONSTITUTIVE MODELING OF HIGH-STRENGTH ALUMINUM CASTING: Keh-Minn Chang, Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506; Jerry Harris, Ravenswood Aluminum Corporation, Ravenswood, WV 26506 High strength aluminum 7xxx alloys are susceptible to cracking during casting, and computational simulation is adapted to obtain better understanding and satisfactory control. Constitutive model of thermomechanical properties of the as-cast ingot is necessary for calculation of thermal stress developed after solidification. Considering the potential influence of precipitation, ingot properties are evaluated by a continuous cooling method, which allows controlled cooling at different rates to test temperatures of interest. The results indicate that thermomechanical behaviour of cast ingot remarkably differs from that of final wrought product. The relationship of mechanical properties are correlated with the microstructure of cast ingots.
Thin coatings of Cr-Si-O are assessed for use as a resistor. The submicron thick films are sputter deposited using a working gas mixture of (I-x)Ar(x)02. Several sintered-compacts of metal and oxide powders are commercially prepared for use as the sputter targets. The deposition process yields a range of film compositions which consist of 2-30 at. % Cr and 20-45 at. % Si as measured using Rutherford Back Scattering. A broad range of resistance values (101 to 1014 Ohm-cm) are found as measured by point contact with metal pads deposited onto the Cr-Si-O film surface. The film structure and morphology is characterized using transmission electron microscopy from which the resistance behavior can be correlated to the distribution of metallic-Cr. Thermal aging reveals metastability in the Cr-Si-O film morpholgy and resistance behavior.
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the polyhedral matrix crystallites divided by grain boundaries is characterized by a porosity and secondary phase inclusions, which exist inside grains and between them. In some cases the inclusions of amorphous phase were detected. The peculiarities of high-resolution TEM of investigated ceramic compounds are discussed. The pretransition phenomena and phase martensite-like transformations in high-Tc superconducting ceramics and classical high-Tc intermetallic compounds of type Al5 (V(3)Si, Nb(3)Sn, V(3pe) and C 15(V(2)Zr, V(2P, V12 )Hf) are compared.
9:30am MICROSTRUCTURE AND OPTICAL PROPERTIES OF GaN NANOCRYSTALS IMBEDDED IN A POLYMER MATRIX: M. Benaissa, Instituto Nacional de Investigaciones Nucleares, Mexico; M. JoseYacarmin, Instituto de Fisica-UNAM, Mexico; K.E. Gonsalves, G. Carlson, University of Conneticut, Storrs, CT 06269 Presently, nanostructured GaN composite was prepared using a novel synthetic route. GaN nanocrystals were imbedded in a poly(methyl methacrylate) thin film matrix (GaNIPMMA) and then studied from structural and optical point of views. X-ray powder diffraction and high-resolution transmission electron microscopy were performed to analyze the microstructure while the optical properties were measured by optical absorption and photoluminescence. Microstructural analyses showed that the GaN nanocrystallites imbedded in the PMMA matrix have an average size of about 5.5 nm and crystallize in the zinc blende lattice (lattice constant a close to 0.45 nm) with some nitrogen vacancies and structural imperfections. Optical absorption measurements indicate that the band gap energy of the GaNlPMMA composite is approximately 3.51 eV.
11:05 am LOW FREQUENCY INTERNAL FRICTION STUDIES OF NANOCRYSTALLINE COPPER-IRON MATERIALS: WN. Weins, J.D. Makinson, R.J. DeAngelis, Department of Mechanical Engineering, The Center for Materials Research and Analysis, University of Nebraska, Lincoln, NE 68588-0656 The low-frequency internal friction behavior of mechanically milled copper and copper-30 wt% iron alloys was studied over a temperature range of 1007000K and a frequency range of approximately 1 to 3 Hz. Alloys were prepared by consolidating mechanically milled and alloyed powders using hot isostatic pressing to form compacts from which bars were machined for testing. Samples studied included unmilled copper, milled copper and milled copper-30 wt% iron. All powders were consolidated at 600°C and diffracting particle size of the consolidated material varied from 18-30 nm. The internal friction studies indicated the presence of a large grain boundary peak in all samples at approximately 300°C which increased with decreasing particle and grain size. The presence of iron appears to depress this peak and cause the occurrence of a second smaller high temperature peak in the range of 400500°C, which is believed to be associated with iron in solid solution.
9:50am ANELASTIC AND MAGNETOELASTIC BEHAVIOUR OF BULK NANOPHASE MATERIALS: E. Bonetti, L. Del Bianco, Dipartimento di Fisica and Istituto Nazionale per la Fisica della Materia, viale Berti Pichat 61 21-409128 Bologna, Italy Mechanical spectroscopy techniques have been employed to investigate the anelastic and magnetoelastic behavior of bulk nanophase Fe and Fe-AI prepared by mechanical alloying and FeCuNbSiB granular alloys obtained starting from amorphous precursors through thermal treatments. The different magnetic states of the materials lead to strong modifications of the anelasticity spectra. The experimental results are presented and discussed with specific reference to the following to aspects: a) magnetoelastic coupling and giant DE effect in the FeCuNbSiB system occurring just below the nanocrystallization temperature, b) giant modulus enhancement in bulk iron and iron-aluminum alloys linked to changes of the magnetic behavior connected to grain size reduction and interfacial structure relaxation.
DESIGN AND RELIABILITY OF SOLDERS AND SOLDER INTERCONNECTS: Session VII: Interconnect Design and Reliability in Electronic Packages III Sponsored by: ASM-MSD Flow and Fracture; SMD Mechanical Metallurgy; EMPMD Electronics Packaging and Interconnection Materials Committees Program Organizers: Dr. R. K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; Dr. D. R. Frear, Sandia National Laboratory, Mail Stop 1411, Albuquerque, NM 87185; Professor S. M. L. Sastry, Washington University, Mechanical Engineering Dept., St. Louis, MO 63130; Professor K. L. Murty, North Carolina State University, Materials Science and Engineering Dept., Box 7909, Raleigh, NC 27695; Professor P. K. Liaw, University of Tennessee, Materials Science and Engineering Dept., Knoxville, TN 37996; Dr. W. L. Winterbottom, Reliability Consultant, 30106 Pipers Lane Court, Farmington Hill, MI48331
10:10 am BREAK 10:25am MAGNETIC PROPERTIES OF GRANULAR Co-Cu ULTRATHIN FILMS: A. Cabbibo, Y.D. Park, lA. Caballero, J.R. Childress, Materials Science and Engineering, University of Florida, Gainesville, FL 32611-2066 Ultrathin «lOnm) films and multilayers of granular Co-Cu composites have been prepared by co-sputtering. Nanoscale Co particles are formed in Cu by depositing on heated substrates (TS>IOOC), with the usual increase in magnetic coercivity Hc, and superparamagnetic behavior above a critical blocking temperature (Tb) which depends on the partical size, shape, and local magnetic environment. We find that the confinement of the granular layer to thicknesses near the particle size induces variation in He and Tb due to changes in particle shape, magnetic anisotropy and inter-particle interactions. By varying the composition and thickness of both magnetic layer and interlayer, as well as the deposition conditions, one can identify conditions under which then magnetic granular layers can be fabricated with large anisotropy and therefore increased blocking temperature, without the need for post-deposition high-temperature processing. Such layers are designed to be used in magnetoresistive spin-valve multilayer structures.
Thursday, AM February 13, 1997
Room: 332 Location: Orlando Convention Center
Session Chairperson: Dr. Zequn Mei, Hewlett-Packard Co., Electronic Assembly Development Center, 1501 Page Mill Road, Mail Stop 4U·3, Palo Alto, CA 94304; Professor K. M. Leung, Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Kong Kong 8:30 am INVITED QUALITY AND RELIABILITY OF BGAAND SMT COMPONENTS: Reza Ghaffarian, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109
10:45am ATOMIC STRUCTURE PECULIARITIES AND PHASE TRANSFORMATIONS IN HIGH-Tc SUPERCONDUCTING CERAMIC COMPOUNDS YB~2)Cu(3P(7.X): VG. Pushin, L.1. Yurchenko, T.G. Koroleva, G.Ye. Vedernikov Institute of Metal Physics, Ural Division of Russian Academy of Sciences, S. Kovalevskaya 18,620219 Ekaterinburg, Russia.
Spacecraft electronics including those at the Jet Propulsion Laboratory (JPL), demand production of highly reliable assemblies. JPL has recently completed an extensive study, funded by NASA's code Q, of the interplay between manufacturing defects and reliability of ball grid array (BGA) and surface mount electronic components. More than 400 test vehicles were assembled using ceramic and plastic BGAs, LCCs, J-leads, and gull wing components. These were subjected to thermal cycle testing and solder joint defects were logged prior to testing and solder damage propagation over time was documented. These findings offer valuable information to designers and quality assurance personnel alike on package robustness as well as in better understanding the defects that can actually lead to failure.
Recent results of high-resolution and in situ transmission and scanning electron microscopy, diffraction of X-rays and electrons, physical and mechanical tests on high T-c superconducting ceramic compounds ofYba (2)CU(3P(7. x)' including thick ceramic films synthesided on ZrO(2)' are presented. The main types of atomic structures, structural defects, secondary phase inclusions are systematized. It is shown that grain structure of ceramics in form of
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8:55 am INVITED SOLDER JOINT RELIABILITY AND LIFE PREDICTIONS FOR VARIOUS SMALL OUTLINE PACKAGES MOUNTED ON FR-4 BOARDS: Suresh Golwalkar, Timothy Rothman, Paul Boysan and Robert Surratt, Intel Corporation, 1900 Prairie City Road, Folsom, CA 95630
9:45 am INVITED RELIABILITY FORMULATION FOR ELECTRONIC INTERCON· NECTIONS: Eugene Atwood and Horatio Quintone, IBM Microelectronics, B/330-81A, Route 52, East Fishkill Facility, NY 12533 This paper describes a novel reliability methodology, supported by data, which includes a rigorously derived stochastic formulation. As an introduction to this topic, the paper reviews and critiques methods currently used in the field of electronic interconnection reliability and presents supporting data illustrating the arguments set forth. Plausible physical explanations are presented for each of the factors used in the IBM modified Coffin-Manson acceleration model. The acceleration model is challenged because of its form which assumes linearly independent factors. A review of the log normal and extreme value distributions, commonly used to model system reliability of electronic interconnects, highlights deficiencies and violations of some of the basic mathematical axioms i.e., "closure property". Additionally we present a refutation of "theoretical derivations" that have put forward to establish the validity of the log normal distribution as a model of fatigue fracture mechanisms. With regard to the main topic: today's thermal environments can no longer be defined by simple periodic functions, i.e., a fixed frequency and amplitude, but instead they tend to be "highly no-periodic" and of random nature. The randomness can be a result of the synergy between operating systems, software, use patterns and CMOS technology, e.g. temperature fluctuation patterns resulting from power management schemes defined in today's electronic devices. Present reliability formulations are not tailored to deal with this randomness. A rigorous formulation is presented that accounts for non-deterministic environments. The method treats the problem stochastically including the use of a novel distribution for time-to-fail, SCRIP (Statistics of Crack Initiation and Propagation) developed by the authors et ai, and other system reliability formulations. An additional methodology is proposed which formulates electronic interconnection reliability in the presence of these random environments and extends the use of cycleltime based reliability assessments commonly used in the industry. The method consists of performing a series of renormalizations by discrete auto correlation and convolution integrals which are used to determine to determine the spectral power density function of the random environment.
TSOP or Thin Small Outline Packages have gained wide spread market acceptance throughout the electronic industry. This innovative and small footprint package was designed to fill a need created by the form factor specified for use in PCMCIA standard memory cards. However, with the broad and rapidly escalating acceptance of Flash products in the marketplace, this small outline package is being considered for a multitude of other use conditions. The small form factor of TSOP and accordingly short stiff lead form construction, requires further scrutiny in certain situations - specifically, applications requiring 20+ year lifetimes or others using 60 mil thick multi-layer FR-4 PCB's subject to extreme thermal cycling. Solder joint reliability is predominantly determined by two separate factors. The first being the surface mount process itself. Without a good initial solder joint, you can not expect good solder joint reliability. This fine pitch package (0.5 mm) requires different considerations than the existing 50 mil (1.27 mm) pitch type components.1R reflow profiles, solder volumes, and land pad layouts all contribute to proper fillet formation and a defect free solder joint. One must start with a good SMT process to have reliable solder joints. Second, is the use condition itself. Packagelboard configuration, operation conditions and thermal cycling of the board, drive solder joint reliability. In order to determine if TSOP is the correct package for a given application, various graphical presentations of failure rate versus service life are included in this paper. Solder joint evaluations were performed using various temperature cycle conditions. Data was taken using 64 mil thick FR-4 boards of various layer count and 20 mil thick 4 layer memory cards using 32Id, 40Id TSOP and 44Id PSOP packages. Temperature cycle conditions A, Band C were performed and Weibull probability plots were developed for each condition. Acceleration factors for solder joint fatigue is given by Norris and Landsburg equations. These include frequency transformations, temperature swing transforms, and a factor for variation of isothermal fatigue characteristics of solder joints between test and operating conditions. These equations yield use condition graphs. The graphs provided, show four different operational temperature swing conditions. Express, industrial, consumer, and computer conditions are depicted according to the IPC standards for these use variables. The extreme of the temperature swing and the frequency of swings per day, modulate the solder joint reliability. We have included both temp cycle condition A and B test data and modeled projections based on those. We feel that condition A more directly simulates real life use condition. Conditions Band C were used as highly accelerated conditions to obtain (trends only) swifter, but preliminary, failure predictions. As can be seen from temp cycle A cycling data, 50% failure point takes approximately six months to complete. PSOP data has ben included for completeness. As can be observed from the data, PSOP solder joint reliability, is oustanding for any application and any temperature range.
10:10 am INVITED SOME PHYSICS, KINETICS AND EMPERICAL RELATIONSHIPS RELATED TO FAILURE OF SOLDERED JOINTS: Barry Schlund, Reliability Engineering Department, MIS H2121, Motorola GSTG, 8201 E. McDowell Road, Scottsdale, AZ 85252 The primary purpose of this paper is to provide the physical reasons behind what appears to be many self-contradictions encountered in solder reliability testing and experience. This is accomplished by presenting the underlying physical aspects of solder reliability, including workmanship, metallic and intermetallic bonding, interface mechanisms, diffusion, vacancy and void formation, work-hardening and softening, as well as smooth versus chaotic stress-strain behavior. Also discussed, is the criterion for successful application of finite element analyses in fatigue life calculations. It is hoped that this work will help bridge the gap between practitioners with opposing beliefs, for example those who believe in chaotic stress-strain behavior versus those who believe in smooth behavior. General guidelines for estimating the appropriate input conditions in the absence of accurate life profiles are provided. The use of the tool is demonstrated with several examples. These include: Thin Outline packages, Quad Flat packs, J-Ieaded components, and leadless Chip Carriers. A comparison of observed failures and calculated times to failure is provided.
9:20 am INVITED LIFE STUDIES OF DIE ATTACH SOLDER SYSTEMS: Kathy Frank and Charles Williams, Texas Instruments, 8505 Forest Lane, MS 8719, Dallas, Texas 75266 Large, high power integrated circuits require solder attach to copper-based lead frames for maximum thermal and electrical performance. The large die sizes (above 22000 square mils) place extra stresses on commonly used solder systems. In this study, a series of solders were used to attach a power array die to copper T0220 heat sink. The assemblies were thermal cycled from 50 to 2050 times over -65°C to + 150°C. Evaluation of the solder joints were done electrically by measuring the Dvbe of individual transistors in the power array circuit, and by cross sectional analysis of structures. The solders used included traditional soft solders (Pb/Sn and (Pb/SnlAg), semi-hard solder (Alloy J), and a low temperature alloy (SnlAg). Differences in solder performance were examined in relationship to transistor location and solder structure.
10:35 am BREAK 10:45 am INVITED COMBINED HEAT TRANSFER AND THERMAL LOAD ANALYSIS FOR FATIGUE LIFE PREDICTION OF SOLDER JOINTS OF RESISTORS: Hasan U. Akay, A. Bilgic and N. H. Padyar, Department of Mechanical Engineering, Purdue School of Engineering and Technology, IUPUI, Indianapolis, IN 46202 Despite the studies performed in the last two decades to understand the fatigue behavior of the solder joints used in the electronic packages, the problem still draws big attention among the electronic package manufacturers.
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Fortunately, the studies performed provided a great improvement in the information about the behavior of the solder material under low-cycle-fatigue conditions. Based on the available information about the mechanical and fatigue behavior of solder material under thermal loads, the present authors developed the volume-weighted averaging technique for the fatigue life prediction of solder joints (A. Bilgic, "Fatigue Life Prediction Methods for Thermally Loaded Solder Joints Using the Finite Element Method", Master of Science Thesis, Purdue University, Indianapolis, IN) and H. U. Akay, N. H. Padyar and A. Bilgic, Fatigue Life Predictions for Thermally Loaded Solder Joints Using a Volume-Weighted Averaging Technique, ASME Journal of Electronic Packaging, 1996 (in Review). The method consists of calculating the stresses and strains generated within a specific package by use of the finite element method and then correlating the calculated stress-strain response to the fatigue life by use of an energy-based fatigue life prediction criterion. The method was used to predict the fatigue lives of several arbitrary solder joints and the predictions were compared with the experimental data. The predictions were very encouraging. It is stated that the method does not differentiate between leadless and leaded solder joints or the loading applied on the packages. In addition, the method is very mesh-insensitive, implying that the number of nodes and finite elements used in the mesh has no major effect on the predictions. In this study, we extend our method to the fatigue life prediction of three-dimensional solder joints of resistors. The heating is provided by the power loading applied on the resistor. The differential thermal expansions within an assembly causes the thermal strains and stresses, as in the case in chip carriers. The analysis is performed in two steps: 1) A heat transfer analysis is performed to determine the spatial variations oftemperatures during a power loading cycle; 2) Thermal stress analysis is performed to determine the thermal stresses and strains developed during the structure. The stress-strain response against the applied power loading is then used to predict the fatigue life using the previously developed volume-weighted technique and the fatigue life prediction criterion. The predictions are compared with the experimental data provided by others.
ing. Further discussion of solderability methods and solder ball integrity via ball shear is also given.
11:50 am CRATERING IN 90:10 Pb:Sn CAST COLUMNS FOLLOWING SHEARING IN CAST COLUMN GRID ARRAY (CCGA) PACKAGES: M. Nemirojf, K. Economy', Y. P. Geng 3, T. H. Hao., lCadence Corp., 10850 Via Frontera, San Diego, CA 92128; 'UNISYS Corp., 10850 Via Frontera, San Diego, CA 92128; 3Institute for Mechanics and Materials, University of California, San Diego, CA 92093; 4China Textile University, Shanghai, China Void-like features have been observed on sheared surfaces on 90: 10 Pb:Sn columns in ceramic cast column grid array (CCGA) packages. The feature sizes are typically 3-5 mils across. These features are not voids. They are crater-like fractures caused by the shearing tool. Shearing with a heavy tool causes extensive cratering. Shearing the columns with a razor blade produces far fewer, if any, of these void-like features. These craters are a concern since they can be mistaken for voids which affect the reliability of CCGA devices. The surface of these features are devoid of large (greater than 2-3 micron) tin-rich regions normally in the bulk of the column. The tin-rich regions have lower toughness than the Pb-rich matrix in the two-phase 90:10 Pb:Sn cast column. Cratering can be explained as a mechanism where the shearing tool creates a crack that propagates around these tin-rich regions. Micromechanical models have been established to simulate crack propagation (a) through and (b) around the tin-rich area. The results show that the energy released for case (b) is less than that of case (a) even though case (b) has a longer crack path.
12:10 pm INVITED EXPERIMENTL STUDIES OF SMT SOLDER JOINT RELIABILITY: K. M. Leung, Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Kong Kong SMT solder joints between ceramic chip carriers and printed circuit boards are found in general to suffer large thermal strains and stresses during device operation under repeated power cyclings. A comprehensive study of the thermomechanical behavior of SMT solder joints has been performed under power cycling using different techniques of optical interferometry. This paper will discuss the detailed analysis of these experimental measurements and its implication on fatigue life estimation of SMT solder joints. Other major experimental studies on solder joints reliability performed at the City University will be reviewed as well.
11:10am PROCESS DEVELOPMENT AND RELIABILITY TESTING OF BALL GRID ARRAY STRUCTURES: Matthew G. Bevan, Bruce M. Romenesko, G. V. Clatterbaugh and Harry K. Charles, Jr., The John Hopkins University, Applied Physics Laboratory, John Hopkins Road, Laurel, MD 20723 The ball grid array (BGA) is a major driving force in advanced surface mount packaging. The BGA provides testability, ease of assembly and repair, and the potential to construct efficient packaging structures with dimensions on the order of the chips themselves (chip-scale packages and !!BGAs). The ultimate reliability and applicability of the BGA will depend on many factors centered on the solder balls, the joint design, and the method of reflow. This work presents the preliminary results of an extensive study on BGAs and their associated processing. Initial emphasis is placed on geometric factors and factors influenced by geometry such as pad size and spacing, misalignment and self-righting forces, solder quality and ball size, joint shape, pad bridging, and cleaning. Each of these factors is further confounded by solder type, method of reflow, pad metallurgy, and the underlying substrate. Finite element modeling has been employed to develop the ultimate joint shape, pad arrangement, board via location, and solder volume necessary to produce the most reliable BGA-board assembly. Model results have been verified by system testing involving extensive temperature cycling, isothermal aging, and detailed metallurgical examination of cycled/aged joint cross sections. Resultant predicted joint model strengths are compared to those obtained by mechanical fatigue testing, solder ball shear testing, and the tensile testing of metallurgical specimens prepared with similar reflow kinetics and grain structures as representative joints.
12:30 pm SOLDER JOINT INTEGRITY OF A PWB WHERE AN ELECTROLESS PALLADIUM FINISH WAS USED AS A SOLDERABILITY PRESERVATIVE: George Milad and Kuldip Johal, Autotech (USA) Inc., 12609 Pinecrest Road, Herndon, VA 20171 A thin layer of 6.0 to 8.0 microinches (0.1 to 0.2 microns) of electroless palladium deposited directly on the copper surface of a printed wiring board has exhibited excellent solderability. This new surface offers a series of advantages over the traditional Hot Air Solder Leveling (HASL). It is flat, coplanar, which is a must for successful screen printing of fine featured devices. It is lead free and environmentally friendly. Other than being solderable it is also wire bondable and has applications as a viable surface finish for contact switching or compression contacts. Characteristics of palladium are discussed. Data of solder joint reliability is presented. The data includes an in depth EDX analysis of metallurgy of the interface between palladium coated copper pads and the solder forming the joint, under various accelerated aging conditions. The solder joint has been subjected to 2000 thermal cycles per IPC standard testing procedures. The results indicate no impairment in resistivity of solder joint integrity.
11:30am RELIABILITY OF A CHIP SCALE PACKAGE: Steve Greathouse', Rao K. Mahidhara", Vern Solberg", Joe Fjelstad", Tom DiStefano", 'Intel Corp., CH6-3 15,5000 W. Chandler Blvd., Chandler, AZ 85226; "Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134 Post stress reliability for Chip Scale Packages and their interconnects has been lacking in the industry. An evaluation of the Tessera !!BGA™ package through the solder screening process, reflow profile, and resultant reliability data is given. Reliability data is compared to industry standard goals for stress-
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and morphological details using x-ray diffraction, scanning electron microscopy and transmission electron microscopy. XRD patterns showed continuous decrease in the intensity of Re peaks, with increasing MA time. However the Re peaks continued to be present even after 5 hours of milling. Ten hours of milling showed complete dissolution of Re, as observed by the complete absence of Re peaks in association with W peak shift in accordance with the dissolution of Re in W. Extensive reduction in particle size and chemical homogeneity of the alloy could be established by microstructural and chemical analysis using SEM and TEM. After pressing and sintering of pellets, tests revealed a significant amount of contamination by iron through milling.
INTERNATIONAL SYMPOSIUM ON RHENIUM AND RHENIUM ALLOYS IX: Processing, Structure and Properties of Rhenium and Its A"oys (Part III) Sponsored by: SMD Refractory Metals Committee and MDMD Powder Materials Committee Program Organizer: Dr. Boris O. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036
Thursday, AM February 13, 1997
9:30am THE KEY POINT OF TUNGSTEN-RHENIUM ALLOYS PROCESSING: Ms. Song Lin, 62 Amethyst Way, Franklin Park, NJ 08823
Room: 232C Location: Orlando Convention Center
Session Chairperson: Dr. John A. Shields Jr., Climax Specialty Metals, 21801 Tungsten Road, Cleveland, OH 44117; Dr. Omar Es-Said, Loyola Marymount University, Los Angeles, CA 90045-2699
Tungsten-Rhenium alloys have won an important application in various modern technical fields and achieved great economic- technical effects and primarily produced by powder metallurgy. Nevertheless, the practical uses of tungsten-rhenium alloys sometimes are limited due to some difficulties encountered in their processing and applications. The common troubles are as follows: I). The inhomogeneity of the alloy's composition. 2). The bubbling effect, during sintering of alloy rods. 3). Breaks occurred in winding formation of the alloy wire. 4). The formation of brittle second phases in the alloy. With the purpose to improve the properties of Tungsten Rhenium alloys. A systematic investigation of above mentioned problems are summarized.
8:30am STRUCTURES AND PROPERTIES OF Mo-ReALLOYS: Fumio Morito, National Research Institute for Metals, 1-2-1 Sengen, Tsukuba 305, Japan It is well known that MO-Re alloys exhibit superior properties among Mo based alloys. However Re effect on the structures and properties of Mo has not well understood. The current state of Mo-Re alloys was therefore reviewed not only in the field of high temperatures but also in the application of high performance. Focusing on the effect of Re concentrations in Mo, the structures and properties of the welds produced by electron beam welding were investigated. Bend and tensile behaviors of the welds were evaluated. Microstructures and fracture surfaces of the welds were examined in details by SEMlEDX and TEM. Furthermore formation and distribution of sigma-phase in Mo-Re welds were studied. A role of signa-phase on the structures and properties of Mo-Re alloys was also discussed.
9:50 am BREAK 10:10 am MECHANICAL BEHAVIOR OF DILUTE Mo-Re ALLOY: R.W. Buckman, Jr., Refractory Metals Technology, Pittsburgh, PA 15236 The creep-rupture life of unalloyed molybdenum at 0.65Tm is only increased by an order of magnitude with up to 50% Re addition. A proprietary process, developed for unalloyed molybdenum, results in an increase in creep-rupture life at 0.65Tm by 4-5 orders of magnitude. A Mo-14Re alloy processed by a similar method exhibits comparable creep rupture strength while recrystallized material retains a DBTT significantly below room temperature.
8:50am THE ORIGIN OF THE INHOMOGENEOUS RHENIUM DISTRIBUTION IN POTASSIUM DOPED WoRe ALLOYS: I. Gaal, Research Institute for Technical Physics of the Hungarian Academy of Sciences, H-1325, P.O. Box 76, Budapest, Hungary
10:30 am THE INFLUENCE OF RHENIUM ON STRUCTURE AND STRENGTH CHARACTERISTICS OF THE HIGH-TEMPERATURE STRENGTH EUTECTIC CHROMIUM BASED ALLOYS: L.v. Artyuh, O. A. Bilous, A.A. Bondar, M.P. Burka, S.A. Firstov, N.I. Tsyganenko, T. Ya. Velikanova, Frantsevich Institute for Problems of Materials Science, 3 Krjijanovskogo Str. 252680 Kiev, Ukraine
It is well established that the performance of a potassium doped W-3%Re sintered ingot depends markedly on the homogeneity of the rhenium distribution in the green compact. In the present work, we point out that fine a-grains (d<10f.lm) do not survive the common sintering process and the adverse effects are governed by the inhomogeneous distribution of solute rhenium in the sintered ingots. The origin of the inhomogeneous solute distribution has to be ascribed to the sluggish decay of that solute rhenium envelope that surrounds each a-grains formed in the intermediate states of sintering, because the envelope is broad with respect tot the size of the a-grains. Numerical simulation proves that the rate of the solute homogenization process is governed by the distance distribution of the rhenium-powder particles. The main conclusion is: final homogeneity of the alloy is very sensitive on the powder preparation. The rhenium concentration has been measured by a microporobe with wave length dispersive detector. The radius of the excited volume was about If.lm. By measuring the same area at various times by the reposition of the microprobe, it has been proved that the error in concentration measurement is markedly smaller than the concentration fluctuation over the cross section of the sintered rods. In spite of the marked homogenisation achieved by sintering, the detected long range fluctuations in the solute rhenium concentration amounted to a few per cents in the ingots studied.
In our Institute some data were obtained that chromium-carbide eutectic cast alloys have prospects promising. The eutectic (CR) + (TiC) alloy has Vickers hardness about 100 Kg!mm2 at 1000°C and is harder than traditional commercial alloys on the base of iron, cobalt or nickel in some times about lOOO°C. And what is more that the latter is able to be machined with the former at high temperature. Produced from (Cr) + (TiC) swages allowed to carry out isotherrnic swaging of high-temperature strength Xil220BX alloy (the Nibased material for vane gas-turbine engine) in air at 1150°C and 200 Mpa stress. Molybdenum additions to the eutectic (Cr) + (TiC) alloy were determined to increase high temperature hardness to 1000°C up to 200-300 Kg! mm2. Continuing development the effect of rhenium on the structure and hightemperature hardness of eutectic two-phases (Cr) + (TiC) alloys in Cr-Ti-C and Cr-Mo-Ti-C systems was examined in this investigation. The rhenium additions being 5, 10 and 20 at. & were shown to lead to the formation of limited quantity of third phase, (Cr23Cr;). Highly dispersed eutectic structure became more homogeneous. According to microprobe analysis the rhenium (as molybdenum) is predominatly dissolved in chromium matrix. High-temperature hardness was determined to be increased already with 5 at. % Re additions. The develop is about 100 kg/mm2 at 300-800°C and about 40 Kgl mm2 at 1000°C. It became higher with increasing rhenium content up to 20 at. %. The hardness of five-component alloys was always more than fourcomponent at the whole temperature interval. The maximum was found at maximum rhenium content (450 Kg!mm2 at 900°C). to our mind the develop was achieved due to solid solution strengthening of chromium matrix (wellknown "rhenium effect"). The determined of hardness allows to estimate the strength characteristics using the a=HV13 connection. Therefore the eutectic
9:10am MECHANICAL ALLOYING OF W-25wt.%Re POWDER: EH. Froes, C.R. Clark, C. Suryanarayana, E.G. Baburaj, Institute for Materials and Advanced Processes, University ofIdaho, Mines Building, Room 321, Moscow, Idaho 83844-3026; Boris D. Bryskin, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036-0245 Mechanical alloying (MA) of well characterized elemental W (75 wt. %) and Re (25 wt. %) was carried out in a SPEX Mill at ambient temperature for 1,3,5 and 10 hours. Milled products were examined for structural, chemical
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(Cr) + (TiC) alloys with rhenium alloying are believed to become more perspective for application.
11:50 am POSTER PRESENTATION THE STRUCTURE AND PROPERTIES OF THE ALLOYS OF Re-CrC TERNARY SYSTEM: T. Va. Velikanova, A.A. Bondar, A.V Grytsiv, Frantsevich Institute for Problems of Materials Science, 3 Krjijanovskogo Str. 252680 Kiev, Ukraine
10:50am HIGHALLOYED BINARY AND TERNARY ALLOYS OF TUNGSTEN AND MOLYBDENUM WITH RHENIUM FOR SERVICE IN NITROGEN- AND HYDROGEN-CONTAINING ATMOSPHERE: K.B. Povarova, N.K. Kasanskaia, O.A. Bannikh, I.D. Marchukova, VL. Likov, Baikov Institute of Metallurgy, Russian Academy of Sciences, Leninskii Pr. 49, 117334 Moscow, Russia
Existence of the rhenium effect improving the mechanical properties of the multycomponent chromium alloys (containing the rhenium and carbon together with other elements) specifies our interest in Re-Cr-C ternary system. Constitution and properties of more than 40 alloys prepared by arc melting were investigated by metallography, x-ray diffraction, microprobe and differential thermal analyses and Pirani-Altertum method in total concentration range. Rhenium raises the melting point of bcc chromium based phase (up to 2284°C in binary system Re-Cr). The maximum temperature of melting for the carbon and rhenium saturated chromium in equilibria with (Cr,Re)23C6 and (a-Re 3Cr,) amounts to 1650°C and appear more high then melting temperature for binary alloys containing Cr and Cr23C6phases (1581 °C). Ternary alloys of this two phase field have higher strength and ductility than binary ones. It is in according to data about existence rhenium effect in chromium based alloys. Essential singularity of Re-Cr-C system is immensely high combined solubility of the chromium and carbon in rhenium at high temperatures (about 50 at % Cr at 30 at % C: and 171O°C) and significant solubility of rhenium in chromium carbides (the most solubility Re in Cr23 C6 amounts to 18, in Cr,C 3 and Cr3C, ones do 8 and 6 at. % at, 1655, 1710 and 1760°C, respectively). Rhenium based solid solution forms equilibria with carbon, solid solutions ofrhenium in chromium carbides and (a-Re3Cr2) and thus it specifies the constitution of Re-Cr-C ternary system.
Microstructure, fracture mode and mechanical properties of vacuum melted binary WR-27VM, MR-47VM alloys and ternary MWR-l 0/45VM alloy both deformed and recrystallized are investigated in the temperature range of 201200°C. Conditions for o-phase precipitation hardening are found. The effect of a-phase on the low-temperature ductility and low and high-temperature strength is estimated. Corrosion resistance at 400-1 OOO°C and features of the chanses in surface layer composition in products of ammonia thermal dissotiation are investigated. It is shown that ternary alloy has high low-temperature ductility and strength and moderate high temperature strength as these of MR-47VM as well, as high corrosion resistance in ammonia dissotiation products close to that ofWR-27VM. Mechanisms of surface layer composition changes in corrosion atmosphere are discussed.
11:10 am THE SYNTHESIS OF W-Re POWDER ALLOYS: V.V. Panichkina, VV. Skorokhod, Frantsevich Institute for Problems of Materials Science, 3 Krjijanovskogo Str. 252680 Kiev, Ukraine The fine particle powder technology was used for the production of W-Re alloys. Single phase W-Re powders were obtained by co-reduction of fine particle W-Re oxide blends. The homogeneous disperse W-20%Re powders and the single phase W-80%Re intermetalide powder with particle size in range of 1- 4).lk were synthesized. W-20%Re powder was mixed with the W powder of the same dispersion in order to obtain W-2%Re alloy. The a-phase would not be formed during the sintering because Re in blend is in form of the prealloyed W-20%Re powder. The synthesized W-2%Re ingots were rolled in 2-3 mm sheets. The mechanical characteristics and the structure of the material were investigated. The sheets had higher plasticity due to the 2%Re alloying. The W-80%Re alloy powders were successfully used for the production of long working time impregnated cathodes.
INTERNATIONAL SYMPOSIUM ON RHENIUM AND RHENIUM ALLOYS X: "Rhenium Effect" and Alloy Development Sponsored by: SMD Refractory Metals Committee and MDMD Powder Materials Committee Program Organizer: Dr. Boris D. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036 Thursday, AM February 13, 1997
11:30am
Room: 231A Location: Orlando Convention Center
Session Chairpersons: R.W. (Bill) Buckman Jr., Refractory Metals Technology, P.O. Box 100551, Pittsburgh, PA 15236, USA; Dr. Lynn B. Lundberg, Materials Consultant, 2832 W. 33 rd N., Idaho Falls, 10, USA
NEWMETHODSOFIMPUTTINGRHENIUMANDMANUFACTURE OF TUNGSTEN-AND MOLYBDENUM-RHENIUM ALLOYS: V.V. Khaydarov, P.S. Maksudov, VI. Pack, A.A. Pirmatov, Uzbek Refractory and Heat Resistant Metals Integrated Plant, 702119 Chirchik, Tashkent Region, Republic of Uzbekistan
8:30am RHENIUM ASAN ALLOY ADDITION TO THE GROUP VA METALS: R. W. (Bill) Buckman Jr., Refractory Metals Technology, P.O. Box 100551, Pittsburgh, PA 15236
Uzbek Refractory and Heat Resistant Metals Integrated Plant is a complex enterprise infield of manufacture tungsten, molybdenum, rhenium, and alloys on their basis. There is a special technology of imputing rhenium from molybdenum concentrates, which contains from 300 GR. to 700 GR. rhenium per each 1 ton of concentrate at the enterprise. Moly concentrates are manufactured by method of nitrogen acid imputing. In this case basic point of rhenium transferring into liquids which contains molybdenum, rhenium and nitrogen and sulfur acids. Using such types of liquids, there are well known methods such as extraction and distilled rectification methods of imputing rhenium. And all above mention of methods have low effect. That is why researching in field of sorption technology of imputing rhenium from nitrogen-sulfur liquids. Researching of wide range of low, middle and high basis of anionites determined that the best one is vanil-peridium resin. Using such type of resin in industry we achieved 80% imputing rhenium as ammonium perrenatum. There is wide range of utility possibilities now we can use our own rhenium and produce powder alloys on basis of tungsten and molybdenum. Tungsten alloys are: BP-3; BP-S; BP-20. Molybdenum alloys are: MKP-16; MP-47. Wire produced from tungsten and molybdenum alloys using in thermometry and tube building industry as they have hardest characteristics.
The anomalous effect rhenium has on the ductility of the Group VIA elements Mo, W, and Cr is not observed in the Group VA metals Ta, Nb, and V. The low temperature ductility of the Group VA elements is significantly impaired at rhenium additions greater than about 3 atom percent. However, rhenium has been shown to significantly improve the high temperature creep strength of tantalum alloys and the effect is saturated at about 1.5 atom percent rhenium, a level which does not alter the ductile-to-brittle transition temperature of tantalum alloys significantly.
8:50am UNDERCOOLING EXPERIMENTS ON RHENIUM AND RHENIUM ALLOYS BY DROP-TUBE PROCESSING: Bernard Vinet and Sandrine Tournier, Commissariat a l' Energie Atomique, DTAICEREM-Departement d'Etude des Materiaux, 17 rue des Martyrs, 38054 Grenoble cedex 9, France Solidification of deeply undercooled melts can lead to the same variety of solid state metastabilities as do methods of rapid quenching of the liquid onto cold substrates. Since undercooling is realized at slow cooling rates, containerless processing is often needed to avoid external nucleation sources. In such a way, refractory materials are studied by letting single droplets fall
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through an evacuated high drop-tube as for instance the 48 metre high facility built in Grenoble. In this contribution, an overview is proposed on the most interesting results obtained so far for rhenium and rhenium alloys. Undercooling experiments have been realized on refractory binary alloys showing complex a(D8 b, type CrFe, 30 atoms per cell) and X (A12, type a-Mn, 58 atoms per cell) phases in the equilibrium phase diagram. The studied systems associate a b.c.c. CW, Ta, Mo, Nb) transition metal with a h.c.p. metal, rhenium in the event (Tc, as and Ru should also be considered if only from a phenomenological point of view). A favoured primarily formation of the metastable bcc-structure instead of the direct formation of the stable phase is obtained in the case of the Re-W system. Moreover, a double recalescence phenomenon is obtained in a composition range between 65 and 82 at % W. This result is discussed in connection with the appearance of the metastable A15 phase. In the case of the Re-Ta system, it is shown that the % phase nucleates from the melt.
the increase in the oxygen solubility at dislocations and small-angle boundaries of the substructure and the segregated enriching of intergrain boundaries with oxygen. For the Mo-Re alloys subjected to solid-solution hardening with oxygen it has been found that the phenomenon of mechanical twinning is suppressed and the characteristics of the dislocation structure are changed on plastic deformation. Moreover, in the solid solutions of the Mo 47 % Re alloys, local regions of the short-range order or type M03ReO, complexes with the A 15 structure, stabilized as a result of the diffusion of oxygen atoms, are observed. The role played by the regularities revealed in the realization of the rhenium effect is discussed.
10:30 am THE ROLE OF PRECIPITATES OF CLOSE PACKED PHASES IN THE "RHENIUM EFFECT": Yu. N. Gornostyrev ,M.l. Katsnelson, Institute of Metal Physics, 620219 Ekaterinburg, Russia; A. V. Trefilov, Kurchatov Institute, 123182 Moscow, Russia
9:10am PHYSIKO AND CHEMICAL PRINCIPLES OF RHENIUM ALLOYS DEVELOPMENT: K.B. Povarova, M.A. Tylkina, Baikov Institute of Metallurgy, Russian Academy of Sciences, Leninsky Pr. 49, 117911 Moscow, Russia
The connection of "rhenium effect" (simultaneous increase of the strength and plasticity in W, Mo, Cr by adding rhenium at a concentration close to the solubility limit) with the peculiar structural state of corresponding alloys is discussed. The hypothesis is suggested, according to which the main factor for the appearance of the rhenium effect is the formation of dispersed close packed (of Frank-Kasper type) phases such as W3Re with A15 structure or distorted a-phase. The general problem of the appearance of dispersed FrankKasper phases near the instability boundary of BCC lattice in transition metal alloys is considered in the framework of a simple crystallogeometrical model. It is shown that the precipitates of the phases in BCC host may provide the increase of the solubility of interstitial impurities. The replacement of carbide phases by the precipitates of the Frank-Kasper phases may lead to the improvement of mechanical properties of the alloys.
Physiko-chemical principles of rhenium alloys development are considered and examples are shown of application of these principles to the development of conventional and advanced rhenium alloys. The features of physikochemical interaction of rhenium with elements of Periodic table in binary, ternary and more complicated alloy systems are analysed. Special attention is given to the theoretical analysis of experimental "composition-property" diagrams. The role of electronic structure is discussed as concerns the effect of the chemical composition on some physical and mechanical properties of CrMoe, or WRe-based solid solutions. The stability is estimated of solid solutions, intermetallic compounds, and interstitual phases in rhenium alloys, as well as the tendencies and rates of diffusion processes in multi component heterogenious rhenium alloys. Special rhenium effects responsible for decreasing of cold brittleness phenomena in IV group metals are discussed as well as high strain-hardening rates ofW-and Mo-alloys with Re. Application of Re-contained alloys are observed.
10:50 am FEATURES OF MANUFACTURING AND TREATMENT OF LOW AND ruGH-ALLOYED WoRe ALLOYS: K.B. Povarova, O.A. Bannych, E.K. Zavarzina, Baikov Institute of Metallurgy, Russian Academy of Sciences, Leninsky Pr. 49, 117334 Moscow, Russia Author's experimental data on the effect of rhenium on the microstructure and some physical and mechanical properties ofW-Re alloys, including molybdenum-containing alloys and alloys strengthened by interstitial phases are discussed. On the base of these data as well as on literature data, low-alloyed and high alloyed WoRe-alloys for different operating conditions are developed. Advantages and disadvantages of the vacuum melting and powder metallurgy processes for production of these alloys are discussed. The ways for increase in purity and improve of homogeneous distribution of rhenium in sintered PM-alloys are discussed too. Analysis of numerous experimental data on the effect of plastic deformation and heat treatment on microstructure, fracture mode and mechanical properties of the rhenium alloyed materials shows the possibility to predict mechanical properties of deformed alloys during their thermo-meohanical treatment and for operating in the wide temperature range.
9:30am THE RHENIUM EFFECT IN W- AND Mo- BASE ALLOYS: THE EXPERIMENTAL REGULARITIES AND THE PHYSICAL NATURE: A.D. Korotaev, A.N. Tyumentsev, Yu. 1. Pochivalov, Siberian Physical & Technical Institute, Revolution Sq. 1,634050 Tomsk, Russia The experimental data on the rhenium effect and related phenomena, such as the solution softening, the elastic twinning and superelasticity, the high strengthening capacity of Mo-Re alloys, allowing a strength of'" 9000 Mpa, etc., are critically reviewed. Particular attention is given to the authors' results on the high (~ 4 at.%) solubility of oxygen in Mo-Re alloys, to the segregation of the interstitial on the structure defects, and to the contribution of these factors to the increase of the plasticity. Some considerations are advanced on the reason for the increase in plasticity for alloys with a rhenium content of "'5-10 at. %. The effect of the rhenium alloying on the decrease in the mobility of screw dislocations and the contributions of the Peierls forces to the increase in plasticity are discussed. The problem of the formation of local composition irregularities with an atomic short-range order and a type Al5 lattice and the relevant experimental data are considered. It is supposed that the grain bulk-to-boundary strength ratio is important for high temperature (1300 K) strength and plasticity of Mo-Re alloys to be attained.
11:10 am DISPERSION AND SUBSTRUCTURE HARDENING OF Mo-Re BASE ALLOYS: A.N. Tyumentsev, A.D. Korotaev, Yu. P. Pinzhin, Siberian Physical & Technical Institute, Revolution Sq. 1, 634050 Tomsk, Russia Using the literature and original data on the phenomenon of internal oxidation (10) in low alloys based on Mo and Mo-47 % Re, the basic mechanisms of this phenomenon and the scientifc principles for controlling the parameters of the heterophase structure formed on 10 are discussed. On this basis, new methods for dispersion and combined dispersion and substructure hardening of type Mo-47 % Re - Zr alloys have been developed and used. These methods provide a depth-uniform distribution of the Zr02 oxide stable until '" 2500 K and a high recrystallization temperature ( '" 2300 K). The resulting high-strength state is stable to heat with the large plasticity margin retained. Based on the study of the regularities and mechanisms of the plastic deformation and destruction of internally oxidized Mo-Re-base alloys, the hardening mechanisms with 10 and the potentialities of the methods developed for increasing the heat resistance of the Mo-Re-base alloys have been analyzed.
9:50 am BREAK
10:10 am THE SOLUBILITY OF OXYGEN IN RHENIUM-ALLOYED MOLYBDENUM: A.D. Korotaev, A.N. Tyumentsev, V.V. Manako, Siberian Physical & Technical Institute, Revolution Sq. 1,634050 Tomsk, Russia The regularities of the phase transformations and the variation of the composition of Mo-Re-base alloys in the process of oxygen diffusion alloying were investigated. It has been found that the alloying with rhenium to a concentration of 47 wt.% increases (to'" 4 at.% and more) the solubility of oxygen, reduces (by 2-3 orders) its diffusion coefficient in molybdenum, and prevents
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used to develop a family of two single crystal alloys (CMSX-4. containing 3% Re and CMSX.-l0 containing 6% Re) and a directionally solidified, columnar grain alloy (CM 1 86LC. containing 3% Re) for a variety of turbine engine applications. A range of critical properties of these alloys are reviewed in relation to component turbine engineering performance through engine certification testing and service experience. Industrial turbines are now commencing to use this aero developed turbine technology in both small and large frame units in addition to aero-derivative industrial engines. These applications are demanding with high reliability required for turbine airfoils out to 25,000 hours. with perhaps greater than 50% of the time spent at maximum power. Combined cycle efficiencies of large frame industrial engines is scheduled to reach 60% in the U.S. ATS program. Application experience out to a total 2 million engine hours and 28,000 hours individual blade set service for CMSX-4. first stage turbine blades is reviewed for a small frame industrial engine.
"RHENIUM EFFECT" ON THE IMPROVING OF MECHANICAL PROPERTIES IN Mo, W, Cr AND THEIR ALLOYS: Yu. V. Milman, 0.0. Kurdumova, Institute for Problems of Material Science, 3 Krzhizhanovsky Str., Kiev 252180,Ukraine The current state of science and mechanical properties improving for Cr, Mo and W alloyed by Re (so-called "rhenium effect") is reviewed. The main possibilities for increasing low-temperature plasticity of Cr, Mo and W by Re additions are closely connected with electron structure change during alloying; that is, plasticity is increased when alloying essentially changes the electron structure by disturbing the optimum conditions of the resonance covalent bond and changing the filling of energy bands. The observed growth of the density of electron states at the Fermi level N(EF) is accompanied by lowering of Peierls stress, decrease of staking fault energy ( SFE), increase of activation volume and interstitial solubility, and the involvement of an additional deformation mechanism - twinning. The increase ofN(EF) should not be very sharp for SFE and interstitial solubility to have the optimum value. SFE has to be lowered so that twinning can occur, but the mobility of dislocation screw components should not be impeded. Lowering of SFE is accompanied by growth of activation volume and increase of stress relaxation rate at concentrators. The increase of interstitial solubility should be sufficient to diminish the tendency to impurity segregation on dislocations as well as on grain and sub grain boundaries, but not so great as cause the abrupt hardening of a solid solution. The experimental results devoted to the influence of Re additions on the dislocation structure, mechanical properties and fracture mechanisms are discussed.
8:50am THE SIGNIFICANCE OF RHENIUM FROM PRODUCTION TO USE IN HIGH TEMPERATURE MATERIALS: Paul Forde, H. C. Starck Inc., 45 Industrial Place, Newton, MA 02161-1961 The major use of Rhenium is in catalysts primarily in the petrochemical industry. However, due to increased demands in high temperature turbine applications, Re is becoming a critical alloying element primarily in nickel base, single crystal superalloys. As a member of the refractory metal family of elements, Re is a higher cost member, in pat due to the expense associated with production. This paper briefly address the new significance of Re in superalloy applications, where its use was practically non-existent in polycrystalline alloys. Also included is an overview of the raw materials from which Re is processed as well as the production techniques currently in use.
INTERNATIONAL SYMPOSIUM ON RHENIUM AND RHENIUM ALLOYS XI: Single Crystal TechnologyRhenium and Rhenium Containing Alloys
9:10am MECHANICAL PROPERTIES OF Mo-Re SINGLE CRYSTALS AND BICRYSTALALLOYS: A. Yastrebkov, Yu. Aleynikov, O. Petrova, and Yu. Ivakin, RI SIA "LUTCH", 142100 Podolsk, Moscow Region, Zheleznodorozhnaya 24, Russia
Sponsored by: SMO Refractory Metals Committee and MOMO Powder Materials Committee Program Organizer: Dr. Boris D. Bryskin, R&D Manager, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036,USA
Thursday, AM February 13, 1997
Rhenium influence (at content up to 30 at. %) on the character of the change of the crystal and intercrystalline boundary mechanical properties was studied using single crystal and bicrystal alloy specimens produced by electron beam zone melting. Tensile tests of single crystals were carried out at 20°C, their impact strength was studied at temperatures from -200°C up to +300°C, the depth of microcracks appearing at electrodischarge treatment and hardness was measured. Bicrystal specimens of the alloys having 5,10 and 2Q at. % of Re were tested for impact strength at 20°C, microcrack depth in the crystals and on the intercrystalline boundaries after elecrodischarge treatment was studied. Disorientation angle ranges of the twist intercrvstalline boundaries were 7_9° and 18-21°. It is shown that alloying strengthens crystals and improve their ductility. Single crystal strengthening has not monotonous nature. Minimum of hardness, ultimate strength and yield strength was observed at 3-4 at. % of Re. The alloying decreases microcrack depth after elecrodischarge treatment both in crystals and on the intercrvstalline boundaries however the depth of the last ones is always more.
Room: 232B Location: Orlando Convention Center
Session Chairpersons: Dr. Amber M. Dalley, Concurrent Technologies Corporation, 1450 Scalp Avenue, Johnstown, PA 15904; R.H. Titran, NASA Lewis Research Center, 21000 Brookpark Road, Mail Stop 49-1, Cleveland, OH 44135
8:30am DEVELOPMENT AND TURBINE ENGINE PERFORMANCE OF THREE ADVANCED RHENIUM CONTAININGSUPERALLOYS FOR SINGLE CRYSTAL AND DIRECTIONALLY SOLIDIFIED BLADES AND VANES: Robert W. Broomfield, David A. Ford, Harry K. Bhangu, RollsRoyce Pic., Derby and Bristol, U.K.; Malcolm C. Thomas, Donald J. Frasier, Phil S. Burkholder, Allison Engine Company (Rolls-Royce pic), Indianapolis, IN; Ken Harris, Oary L. Erickson, Jacqui B. Wahl, Cannon-Muskegon Corporation (SPS Technologies Inc.), Muskegon, MI 49443
9:30am THE RHENIUM IMPACT ON THE MASS TRANSFER IN Mo-Re SINGLE CRYSTALS UNDER SHOCK LOADING: S.v. Divinski, L.N. Larikov, M.N. Belyakova, v.v. Zholud, V.F. Mazanko, Institute of Metal Physics, National Academy of Sciences, 36 Vemadsky Str., Kiev-142, 252142, Ukraine
Turbine inlet temperatures over the next few years will approach 1650°C (3OO0°F) at maximum power for the latest large commercial turbofan engines, resulting in high fuel efficiency and power levels approaching 442 kN (100,000 lbs). High reliability and durability must be intrinsically designed into these turbine engines to meet extended over-water, large twin engine aircraft (ETOPS) certification requirements. This level of performance has been brought about by a combination of advances in air cooling for turbine blades and vanes, design technology for stresses and airflow, single crystal and directionally solidified casting process improvements, the development and use of rhenium (Re) containing high y' nickel-base superalloys with advanced coatings, including full-airfoil ceramic thermal barrier coatings. Re additions to cast airfoil superalloys not only improve creep and thermo-mechanical fatigue strength but also environmental properties, including coating performance. Re dramatically slows down diffusion in these alloys at high temperature turbine operation conditions. A team approach has been
An abnormally high depths of marked atom penetration at shock loading have been discovered for Fe and then were observed for a number of metals. In this work, this phenomenon is thoroughly investigated for the Mo-Re single crystals. It was found that Re moderates substantially the mass transfer. The derth of penetration of the Ni-63 isotopes decreases to 17 and 3 percents of that value for pure Mo if the Re content is 10 and 17 at.%, respectively. These results are discussed in a framework of Re impact on generation and migration of interstitials under movement of jugged screw dislocations. Moreover, the Re alloying increases the contribution of twinning to the plastic deformation. A computer model of enhanced mass transfer at shock loading has been proposed and the Re impact was numerically studied.
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sions of crystals were up to 35-40 mm in diameter for tungsten and up to 110 mm for niobium. This report contains experimental data in studying process of growing single crystals of rhenium containing alloys based on molybdenum and tungsten, such as M048%Re alloys and W-27%Re and polycrystalline as cast rods and bars. It was found that this method is very efficient for producing calibrated bars from these alloys which can be used in wire production without mechanical treatment. This technology provides very high yield of metals.
10:10 am STRUCTURE EVOLUTION IN RHENIUM SINGLE CRYSTALS AT ROLLING AND ANNEALING: S.v. Divinski, L.N. Larikov, M.N. Belyakova, V. Rafalovski, Institute of Metal Physics, National Academy of Sciences, 36 Vernadsky Str., Kiev-142, 252142, Ukraine Structure of Re single crystal with the (OOOI }<1120> orientation subjected to rolling has been investigated. Initial orientation is unstable and single crystal is transformed to polycrystalline state. This texture evolution has been analyzed by a computer model. A good agreement with experiment has been achieved. Strain dependence of density of the Re crystal reveals abrupt increase at about 22% of strain, although visible cracks at external surface appear only at -30% of strain. The last value corresponds to pronounced intensifying of the subsequent recrystallization under annealing. Influence of rotational deformation modes have been numerically studied and their substantial impact on axial textures of Re was predicted.
11:30 am GROWTH FEATURES OF WoRe SINGLE CRYSTALS UPON PLASMA ARC MELTING: G.S. Burkhanov, V.M. Kirillova, Baikov Institute of Metallurgy, Russian Academy of Sciences, Leninsky Pr. 49, 117911 Moscow, Russia; B.D. Bryskin, Rhenium Alloys, Inc., 1329 Taylor Street, P. O. Box 245, Elyria, OH 44036-0245 Plasma-arc welding was used to grow high purity W-Re single crystals in a wide concentration range (1-20 wt.% Re). Relationship between solidification (growth rate "R", temperature gradient in liquid phase - "GL', Re concentration - "Co") and growth structure (cellular, dendritic, single- and polycrystalline) ofW-Re alloys was determined and shown as "Co - GLIR -'" diagram. Effect of crystallographic instability was discovered for (W-Re) single crystals with [l1O] and [111] orientation which were changed to preferable [100] growth orientation upon growing. The reason of this orientation and its dynamics were examined. W-Re single crystals of 1st melt were characterized by considerable misorientation of 1st order sub grains from seed to the top of ingot and "striped" microstructure. Such structure and instability of crystallographic growth were examined by concentration undercoolings. The ways for improving ofW-Re single crystals structure perfection are suggested.
10:30 am EFFECTS OF THE RHENIUM ADDITIONS ON THE STRUCTURE AND MECHANICAL PROPERTIES OF THE TUNGSTEN SINGLE CRYSTALS: O.A. Bilous, V.N. Minakov, D. Yeo Ovsienko, E.L Sosnina, V.L Trefilov, LN. Frantsevich Institute for Problems of Material Science, Institute for Physic of Metals, 3 Krzhizhanovsky Str., Kiev 252180, Ukraine The structure and mechanical properties of single crystals Wand binary alloys W-Re that were grown by electron beam zone technology with low carbon concentration (1O-'4-1O-7Torr) in the direction axis <100>±(l+ 1.5°). The yield stress and the ductile-brittle transition temperature of the W and W-Re single crystals of the specimens that were cut normally to the direction of crystals growing have been determined to be lower than in parallel cut ones. That is determined by dislocation structure anisotropy of single crystals. Alloying tungsten single crystal with rhenium results in considerable decrease of cold brittleness temperature Tb was shown. The most effective are the lowest rhenium concentration. Thus, adding of 0.1 at. % Re decreases Tb from 40°C and 4.3 at. % Re only to -60°C in parallely cut specimens, for example. It should be marked, yield stress grows proportionally the rhenium content in alloys.
11:50 am METHOD FOR PRODUCING HIGH-PURITY RHENIUM FOIL: A.V. Eiutin, K.S. Kovalev, T.B. Danilina, State Research Centre-State Institute of Rare Metals-GIREDMET, 5 B. Tolmachevsky Per., Moscow 109017, Russia For some applications, such as manufacturing of the thermionic cathodes of mass spectrometers and other purposes a rhenium foil of 20-40 mcm thickness with a base metal content of 99.99-99.999% is used. For producing of high-purity rhenium foil we use rhenium bars made by EB floating zone melting which have 20-30 mm in diameter, 200-500 mm in length, singlecrystalline structure and 99.999% purity. During the foil production significant advantages may be obtained by using single crystalline billets having a crystallographic orientation that is favorable for deformation. With this approach, it becomes possible to achieve by rolling total reduction value of up to 50-65% as compared to some 5-7% in case of using polycrystalline billets of identical purity, and to obtain after a first annealing a relatively homogeneous fine-grain recrystallized structure that is favorable for subsequent rolling steps. It was shown by practice that the above described method makes possible to produce rhenium foil with 99.99% purity and upwards.
10:50 am STRUCTURE AND PROPERTIES STABILITY OF Re-SINGLE CRYSTALSUPONVACUUMANNEALINGANDTHERMOCYCLING:G.S. Burkhanov, V.M. Kirillova, Baikov Institute of Metallurgy, Russian Academy of Sciences, Leninsky Pr. 49, 117911 Moscow, Russia; B.D. Bryskin, Rhenium Alloys, Inc., 1329 Taylor Street, P. O. Box 245, Elyria, OH 440360245 Electro-beam zone melting was used to grow high purity Re single crystals with different crystallography orientations. Thermo-electrical moving force (t-c.m.f.) of Re-single crystal was found to insignificantly increase upon 4 h vacuum annealing at 2000°C. In this case anisotrophy of Re-single crystal te. m.f. substantially increased. Comparison between Re-single and polycrystals showed that electrical properties of single crystal were stable in contrary of that of the polycrystal. Structure, hardness and specific electrical resistivity of Re-single crystal were established to insubstantially increase upon thermocycling (l600-400°C, 300 cycles). Specimens as 5x5 mm2, 100 mm rectangle (with two sides parallel to basic plane) were cut from Re-single crystal ingot. The shape of this specimens was unchanged upon above mentioned thermocycling. Explanation of stability of Re-single crystal and its application were discussed. 11:10 am USAGE OF EB FLOATING ZONE MELTING FOR PRODUCTION OF RHENIUM ALLOYS WIRE: A.V. Elutin, LA. Yudin, State Research Centre-State Institute of Rare Metals-GIREDMET, 5 B Tolmachevsky Per., Moscow 109017, Russia In the eighties in the former USSR some efforts were made to create modem equipment for producing single crystals of refractory metals by electron beam (EB) floating zone melting. Using this EB furnaces, single crystals of tungsten, molybdenum, tantalum, niobium and rhenium were produced. Dimen-
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9:20am ELECTROCHEMICAL STUDY OF PYRITE OXIDATION IN CHLORIDE SOLUTION: H.K. Lin, Mineral Industry Research Laboratory, 212 O'Neill Building, University of Alaska Fairbanks, Fairbanks, AK 99775-7240; W.C. Say, Department of Material Science, National Taipei Institute of Technology, Taipei, Taiwan
MATERIALS PROCESSING FUNDAMENTALS SYMPOSIUM V Sponsored by: Jt. EPDIMDMD Synthesis, Control, and Analysis in Materials Processing Committee, EPD Process Fundamentals, Aqueous Processing, Copper, Nickel-Cobalt, Pyrometallurgy, Lead, Zinc, Tin Committees, MSD Thermodynamic & Phase Equilibria Committee Program Organizers: R.G. Reddy, Department of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL 35487-0202; S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; P.R. Taylor, Department of Metallurgical and Mining Eng., University of Idaho, Moscow, ID 83743
Thursday, AM February 13, 1997
Pyrite oxidation in chloride solution was investigated with cyclic voltammetry, ac impedance and potential step techniques. The pyrite oxidation in quiescent electrolytes is irreversible and controlled by diffusion. Depression of the semicircle in the complex plane plot has been explained mathematically based on the concept of the equivalent circuit. When the semicircle is depressed, the mathematical formula indicates that the reaction resistance should be obtained from the intersection of the semi-circle with Z' -axis instead of the semi-circle diameter. The peak charging current densities at l.l0 and 0.90 V vs. SHE obtained from the equivalent circuit coupled with the ac impedance measurements match the peak current densities obtained with the potential step measurements.
Room: 231B Location: Orlando Convention Center
Session Chairpersons: R.G. Reddy, Department of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL 35487-0202; J. Hryn, Blvd. 362, Argonne National Labs, 9700 S. Cass Ave., Argonne, IL 60439
9:45am LEACHING OF CHALCOPYRITE IN CuCI-NaCI-0 2 SYSTEM: R Padilla, D. Lovera, M.e. Ruiz, Department of Metallurgical Engineering, University of Concepcion, Casilla 53-C, Concepcion, Chile
8:30am A MATHEMATICAL MODEL TO CHARACTERIZE, THE DISSOLUTION OF SULFIDES IN CuCI2 - CuCI- FeCI3 - FeCI 2 - NaCI - HCI H 20 SYSTEM: CUPRIC CHLORIDE LEACIDNG OF SYNTHETIC NiS: RC. Hubli, T.K MukheIjee, C.K. Gupta, Bhabha Atomic Research Centre, Trombay, Bombay 400085, India, S. Venkatachalam, Department of Met. Engg. and Matis. Sci., I.I.T. Bombay, India; RG. Bautista, Mackay School of Mines, University of Nevada, Reno, NY 89557
The leaching behavior of chalcopyrite concentrate in acidic CUCI 2 NaCl-02 solutions was investigated. Experiments were conducted under continuous flow of oxygen at atmospheric pressures. The results indicated that among the variables temperature has the largest influence on the dissolution of chalcopyrite in this medium, and high dissolution can only be obtained at temperatures near the boiling point of the solution. It was also found that the stirring speed did not influence appreciably the dissolution of chalcopyrite and that an increase in the oxygen flow rate in the leaching reactor increased the dissolution of chalcopyrite. The total chloride concentration affects markedly the dissolution of chalcopyrite up to about 4 M. Copper dissolutions of about 85% were obtained in leaching chalcopyrite of size fraction -65+ 100 # Tyler at lOOT in 2 hours.
Simulation of sulfide dissolution in cupric chloride media using the partial equilibrium approach has been investigated under different process conditions. The following observations may have a significant bearing on the dissolution behavior: The amount of cupric-chloro-hydroxy complexes is low, d % of total Cu(II), when the pH of the lixiviant is around 1.5 but increases at lower H+ concentrations. Under aerated conditions the hydrolysis is higher and control of pH during the dissolution process is necessary, the total initial Cu(II) concentration higher than 0.50 M does little to enhance dissolution but may entail a higher loss of "free" copper, the optimum temperature for cupric chloride leaching is around 373-378 K (100 - 105T) and the presence of small amounts of ferric ion results in increasing the initial rate of dissolution as well as suppressing the hydrolysis of copper. *Acknowledgments: This investigation forms a part of the INDO-US collaborative research programme supported by the Department of Science and Technology, Government of India and the NSF, USA under NSF Grant No. INT-9103106.
10:10 am BREAK
REACTIVE METALS· GENERAL ABSTRACTS
Sponsored by: LMD - Reactive Metals Committee Program Organizers: R.G. Reddy, Department of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL 35487-0202; J. Hryn, Blvd. 362, Argonne National Labs, 9700 S. Cass Ave., Argonne, IL 60439
8:55am LEACIDNG OF A CHALCOCITE CONCENTRATE WITH CUPRIC CHLORIDE-OXYGEN: M. C. Ruiz, S. Honores, R. Padilla, Department of Metallurgical Engineering, University of Concepcion, Casilla 53-C, Concepcion, Chile
10:20 am VAPOR PRESSURE STUDIES OF THE SALT FLUX PHASES: S.Wang, ASARCO Inc., Technical Services Center, 3422 South 700 West, Salt Lake City, UT 84119; RG. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487
This work outlines the results of leaching studies on a copper concentrate containing chalcocite (CU2S) and digenite (Cu.,Ss) with an acid saline solution of cupric chloride oxygenated at ambient pressure. The variables studied included the stirring speed, concentration of cupric ions, concentration of HCl, concentration of chloride ions, oxygen flow rate, temperature and time. The leaching system was found to be very effective for the dissolution of the concentrate. Over 95% of the copper was dissolved in 30 minutes with negligible dissolution of iron. The dissolution of copper increased with the stirring speed up to about 400 rpm and depended little on the total chloride concentration. The oxygen flowrate affected the dissolution of copper only below 0.09 IImin. The concentration of HCl did not influence tile dissolution providing its was sufficient to avoid the precipitation of copper oxychloride. The study of the effect of the temperature showed a maximum in copper dissolution around 90"C.
Physical and chemical properties of the salt flux phase playa significant role in the recycling of UBC and aluminum melting processes. Particularly, the knowledge of several properties such as salt vapor pressure, melting temperature, loss of aluminum, corrosion of refractories are useful for the performance improvements in aluminum industry. In this paper, vapor pressure of sodium and potassium salt fluxes were studied in the pure, binary and ternary systems. The experimental results of vapor pressure studies are presented and the potential application I the industry to the efficiency and the operating advances are discussed. 10:45 am COMPLEXES OF NIOBIUM (IV,V) IN LiF-NaF-KF MELTS WITH VARYING 0 2• CONCENTRATIONS: Flemming Matthiesen and Pia Tolstrup, Jensen Kernisk Lab. A, DTU, 2800, Lyngby, Denmark; TeIje Ostvold, Institutt for Uorganisk Kjemi, NTNU, Gloshaugen, 7034, Trondheim The ternary eutectic LiF-NaF-KF (FLINAK) melt at 700°C was used as a solvent for a study of Nb(IV,V)-O-F complexing. The motivation for this
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study is the electroplating mechanism of Nb from such melts. A 1.8 mol% Nb,o, solubility is observed in this melt. The dissolution mechanism is K+ +NbP, = NbO,F/x + KNbOls) + xF-. When Nap or SrO is added to FLINAK containing 1 mol% Nb(V), a constant concentration of Nb and a concentration of 0" given by the added oxide up to no/nNb =2 is observed. For 2 < nJnNb < 3, the NbO,Fx'" complex reacts to form KNbOls). The solubility data of this compound is matched by literature data. By further additions of 0'-, this solid reacts to form NbOl type complexes. When Nap is added to FLINAK containing I mol% Nb(IV), a constant concentration ofNb and a concentration of 0'- given by the added oxide up to nJnNb=1 is observed. Above this ratio some Na,O still dissolves, but an unknown compound precipitates. At nJnNb =2 the 0'- and Nb(IV) concentrations decrease with increasing oxide additions and reaches a minimum at NJnNb=3 and probably ~Nb03(S) is formed. Up to nJn Nb =3 the melts are coloured, but changes to colourless (white solids when cooled) at nJnNb>3. A melt containing a complex of the type NbOl- is probably formed at these high oxide concentrations. Nap is now completely soluble in the melt.
RECENT ADVANCES IN FRACTURE VII: Fracture at High Temperature: A Symposium Dedicated to Emeritus Professor Frank A. McClintock Sponsored by: MSD Flow and Fracture; SMD Mechanical Metallurgy Committees Program Organizers: Dr. R. K. Mahidhara, Tessera Inc., 3099 Orchard Drive, San Jose, CA 95134; Dr. A. B. Geltmacher, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375; Dr. K. Sadananda, Naval Research Laboratory, Code 6323, 4555 Overlook Drive SW, Washington D. C. 20375; Dr. P. Matic, Naval Research Laboratory, Code 6380, 4555 Overlook Drive SW, Washington D. C. 20375 Thursday, AM February 13, 1997
Room: 314A Location: Orlando Convention Center
11:10 am KINETICS OF ERBIUM OXIDE CORROSION IN MOLTEN CERIUM: C. Lensing, D.L. Olson, B. Misbra, Center for Welding, Joining and Coatings Research, Department of Metallurgical & Materials Engineering, Colorado School of Mines, Golden, CO 80401
Session Chairpersons: Professor Amiya K. Mukherjee, Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616; Professor Kenji Higashi, Department of Mechanical Systems Engineering, Osaka Prefecture University, Sakai, Osaka, Japan
The compatibility between erbium oxide and molten cerium was investigated to understand the high temperature corrosion mechanisms and to provide kinetic data. High and low density erbium oxide samples were immersed into molten cerium at temperatures ranging from 8S0 to 97SoC for 16 to 128 hours. A parabolic rate dependence for corrosion scale formation was observed as well as an intergranular penetration of cerium into erbium oxide was noted. Activation energy for the complete corrosion process is 38.S kCallmole. Two reaction layers formed for the cerium system, viz. cerium oxide particle layer and a layer of erbium oxide-cerium oxide solid solution.
8:25 am INVITED MODELLING OF CREEP CRACK GROWTH: George R. Webster, Department of Mechanical Engineering, Imperial College, London, SW7 2BX, UK Failure in high temperature components which suffer creep can occur by net section rupture, crack growth or some combination of both processes depending on the loading conditions. Failure by crack growth is most likely to occur from sites of stress concentration or in components which contain an initial defect. In many practical situations, cracking is preceded by an incubation period, or at least a transient region of very slow growth, prior to the onset of steady state behaviour. This transient region can occupy the majority of life and it is important that it is taken into account to obtain reliable lifetime predictions. In this presentation non linear fracture mechanics concepts will be used to predict the behaviour. A model involving the build up of damage in a process zone at a crack tip will be employed to describe an incubation period, the transient region and steady state crack propagation rates. The role of superimposed fatigue loading will be examined. The analysis will be applied to characterize high temperature crack growth in polycrystalline, directionally solidified and single crystal materials.
11:35 am DEVELOPMENT OF PROCESSING METHODS FOR STAINLESS STEEL-ZIRCONIUM NUCLEAR WASTE FORMS ALLOYS: S.M. McDeavitt, D.P. Abraham, Argonne National Laboratory, Chemical Technology Division, 9700 South. Cass Avenue, Argonne, IL 60439 Stainless steel-zirconium waste form alloys are being developed at Argonne National Laboratory for the immobilization of metallic materials left behind following the electrometallurgical treatment of spent nuclear fuel. The metal waste form comprises fuel cladding, noble metal fission products (e.g., Ru, Rh, Pd, Zr, and Tc), and other metallic constituents. These metallic wastes are not generated in the electrorefiner; they are present with the spent fuel before treatment. The nominal compositions stainless steel- IS wt% zirconium and zirconium-8 wt% stainless steel are the baseline alloys for stainless steel-clad and Zircaloy-clad fuels, respectively. The selection process for the baseline compositions will be described and the subsequent development of basic alloying procedures will be reviewed (e.g., alloying temperatures, molten metal containment, and heating method). Other process-related issues still under development include microstructural refinement through annealing and molten salt fluxing for surface purity and composition control.
8:50 am INVITED INTERFACIAL DECOHESION FROM SURFACE· ABSORBED EMBRITTLING ELEMENTS: R.C. Muthiah', Y. Xu', C. J. McMahon} and J. L. Bassani', 'Department of Materials Science and Engineering; 'Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA Motivated by problems in high-temperature cracking in superalloys exposed to an oxidizing environment, McClintock and Bassani (1981) developed a model that considered the diffusion along a grain boundary due to a concentration gradient alone and the resulting decohesion in the presence of the time-dependent crack-tip stresses. More recently, Bika and McMahon (199S) extended their ideas to include the influence of the crack-tip stress gradient on the diffusion process. In this paper we develop a model where diffusion is driven both by concentration and stress gradients while those stresses are directly influenced by cracking process. The formulation utilizes a cohesive zone model that couples creep deformation, diffusion, and damage ahead of a crack to predict the cracking due to dynamic embrittlement. This cracking process is being studied experimentally in systems in which the surface-active embrittling element comes either from the material itself, i.e., from surface segregation, or from the surrounding atmosphere. Both polycrystalline and bicrystal specimens are being employed. We have found that a precipitation-hardened copper-beryllium alloy makes an ideal model material for the study of stress-driven oxygen-induced embrittlement in high-strength alloys. The effect of varying the diffusion coefficient as function of direction in bicrystals is being investigated in a copper-tin alloy, in which the embrittlement comes from surface-segregated tin.
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9: 15 am INVITED STRESS INDUCED ELECTRICAL FIELDS AND THEIR INFLUENCE ON HIGH TEMPERATURE FRACTURE IN CERAMICS: Rishi Raj, Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853
10:30 am BREAK 10:40 am CREEP FRACTURE DURING SOLUTE-DRAG CREEP AND SUPERPLASTIC DEFORMATION: Eric M. TalefJ', Donald R. Lesuer" and Chol K. Syn", "Department of Aerospace Engineering and Engineering Mechanics, The University of Texas, Austin, TX 78712; "Manufacturing and Materials Engineering Division, Lawrence Livermore National Laboratory, Livermore, CA 94550
High temperature fracture in ceramics is nearly always controlled by the nucleation and growth of intergranular cavities. The mechanism of growth is stress induced diffusion of point defects. In ceramics the point defects are charged and therefore, their movement can be influenced by local electrical fields. Internal fields can arise near interfaces as a result of net segregation of charged defects to the interfaces. These electrical fields can, in turn, change the defect concentration, thereby, the self diffusivity in the nanoscale region adjacent to the interface. I will discuss, and present results from fundamental experiments that show how these fields can be influenced by applied stress and how these fields participate in the fracture kinetics. Further consideration leads us to speculate on the use of externally applied electrical fields to control nucleation and growth of cavities at grain boundaries.
Creep fracture has been studied in AI-Mg and Al-Mg-Mn alloys undergoing solute-drag creep and in micro-duplex stainless steel undergoing superplastic deformation. Failure in these materials can be controlled by two mechanisms, neck formation and cavitation. The mechanism of creep fracture during solute-drag creep in AI-Mg is found to change from necking-controlled fracture to cavitation-controlled fracture as Mn content is increased. Binary Al-Mg material fails by neck formation during solute-drag creep, and cavities are formed primarily in the neck region due to high hydrostatic stresses. Ternary alloys of Al-Mg-Mn containing 0.25 and 0.50 wt pet Mn exhibit more uniform cavitation, with the 0.5Mn alloy clearly failing by cavity interlinkage. Failure in the micro-duplex stainless steel is controlled by cavity growth and interlinkage during superplastic deformation. Cavitation was measured at several strains, and cavitation is found to increase as an exponential function of strain. An important aspect of cavity growth in the superplastic stainless steel is the long latency time before cavitation occurs. For a short latency period, cavitation acts to significantly reduce ductility below that by neck growth alone. This effect is most pronounced in materials with high strainrate sensitivity, for which neck growth occurs very slowly.
9:40 am INVITED CRITICAL ASSESSMENTS OF CAVITATION FAILURE PROCESS IN HIGH STRAIN-RATE SUPERPLASTIC MATERIALS: Kenji Higashi l , M. Mabuchi 2H. Iwasaki', 'Department of Mechanical Systems Engineering, Osaka Prefecture University, Gakuen-cho, Sakai, Osaka 593, Japan; 2National Industrial Research Institute of Nagoya, Hirate-cho, Kitaku, Nagoya 462, Japan; 'Department of Materials Science, Himeji Institute of Technology, Shosha, Himeji, Hyogo 671-22, Japan A new accommodation process for high-strain rate superplastic flow is analyzed from a viewpoint of the relaxation of stress concentrations at triple junctions of grain boundaries for the alloys and around reinforcement particles for the composites resulting from sliding at boundaries and interfaces. A special process by an accommodation helper such as a liquid phase is required to continue superplastic flow when the stress concentration is insufficiently relaxed by diffusional flow and/or diffusion-controlled dislocation movement under the given deformation conditions. A liquid plays an important role as an accommodation helper in the accommodation mechanisms of high strain-rate superplasticity, that is, in an assistance to relax stress concentrations caused by sliding. However, the presence of a liquid phase does not always lead to the high strain-rate superplasticity. The critical conditions such as optimum distribution, thickness and volume in liquid phase are discussed based on the observation results by transmission electron microscopy and cavitation behavior. Cavitation behavior at various conditions for liquid phases are investigated by a quantitative analysis for high strain rate superplastic materials. It is suggested from theoretical analysis that diffusion-controlled cavity growth is limited and the plastically-controlled cavity growth is dominant when stress concentrations at triple junctions of boundaries and around reinforcements are relaxed by the presence of a liquid phase, so that the cavity growth is significantly slow in a small cavity size range. This view was in agreement with the experimental data of the cavity growth rates.
11:05 am FAILURE BEHAVIOR OF DUCTILE LAYERS IN LAMINATED COMPOSITES: S. Bulent Biner, Ames Laboratory, Iowa State University, 208 Metals Development Building, Ames, IA 500 II In this study, the failure of the ductile layers from collinear, multiple and delaminated cracks that occur in laminated composite systems was studied using a constitutive relationship that accounts for strength degradation resulting from the nucleation and growth of voids. The results indicate that in laminated composites, void nucleation and growth ahead of cracks occur at a much faster growth rate due to evolution of much higher stress values at the interface region. Except for short crack extensions, collinear and multiple cracks develop crack resistance curves similar to that seen for a crack in the ductile layer material as in homogenous isotropic cases. For delaminated crack cases, the fracture behavior is strongly influenced by the delaminating length. The resistance of the ductile layers to crack extension can be significantly reduced by short delamination lengths; however, for large delamination lengths the resistance to crack extension becomes greater than that seen for the ductile material.
11:25 am HIGH TEMPERATURE CRACK GROWTH UNDER MIXED-MODE CONDITIONS: William E. Churley and James C. Earthman, Department of Chemical and Biomedical Engineering, University of California, Irvine, CA92717
10:05 am INVITED ROLE OF DIFFUSIONAL RELAXATION IN FRACTURE OF ALUMINUM MATRIX COMPOSITES DURING CREEP AND SUPERPLASTICITY: Rajiv S. Mishra and Amiya K. Mukherjee, Department of Chemical Engineering and Materials Science, University of California, Davis, CA95616
Results from finite element analyses have long been used to model high temperature crack growth processes beginning with the pioneering work of Bassani and McClintock. Recently, finite element results have been used to to study the mechanisms of high temperature crack growth under mixed-mode loading. Experimental studies of this failure process in high temperature alloys and intermetallics have been performed by measuring crack growth direction and crack growth rate in specially designed specimens under Mode I, Mode II and a range of mixed-mode loading conditions. The focus has been on how certain multi axial stress parameters determined from finite element results can be used to predict both the crack paths and crack growth rates observed experimentally. This approach has led to a better understanding of the dominant crack growth processes in the high temperature materials investigated.
Reinforcement of metallic matrix with second phase ceramic particles can lead to significant increase in creep strength. Some of these composites also exhibit high strain rate superplasticity. The diffusional relaxation of stresses during creep and superplastic deformation plays an important role. For example, the creep fracture behavior depends on the diffusional relaxation rate. Diffusional relaxation models can be used to calculate the critical creep rate. Below the critical creep rate intergranular fracture is observed, whereas above the critical creep rate trans granular fracture is observed. These observations can be explained on the basis of metal/ceramic interface decohesion. The importance of early onset of interfacial cavitation in the analysis of creep data to obtain mechanistic interpretation is discussed. The change in high strain rate superplasticity mechanism with the size of reinforcement is also explained using the diffusional relaxation models.
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11:45 am ON VOID GROWTH IN VISCO PLASTIC SOLIDS UNDER CREEPFATIGUE CONDITIONS: Raj Mohan and F. W. Brust, Engineering Mechanics Department, Battelle Memorial Institute, Columbus, OH 43201 USA The growth of intergranular voids in elastic-viscoplastic solids is studied using an axisymmetric micromechanical model. Numerical unit cell calculations are performed under remote slow as well as fast cyclic loading. Among the many issues examined include the effect of initial void shape, the effect of on boundary diffusion, the effect of primary creep mechanism, the effect of stress triaxiality as well as the role of elastic accommodation. The results of the study demonstrate that the void growth history and void shape evolution are significantly affected by stress triaxiality, material nonlinearity and initial void shape. The importance of accounting for primary creep mechanism, in addition to secondary creep (power-law creep) is demonstrated for cyclic loading conditions. The analyses shed some light on experimentally observed peculiar behavior under balanced cyclic loading. 12:05 pm TWO PARAMETER CHARACTERIZATION OF CRACK TIP FIELDS UNDER THERMOMECHANICALLOADING: Noel P. O'Dowd, Department of Mechanical Engineering, Imperial College, London, SW7 2BX, United Kingdom Two parameter approaches (K-T, J-Q) have been used to account for constraint and geometry in fracture under mechanical testing. This paper examines the effect of thermal loading on the near tip constraint. Finite element analyses of representative thermal loading which give rise to high and low constraint fields (high and low T and Q) have been conducted. As in previous analyses linear elastic, power law hardening materials have been examined. Following the thermal loading the structure is SUbjected to mechanical loading, both tension and bending dominated to assess the effect on the near tip constraint. On subsequent mechanical loading it is observed that the two parameter structure of the fields is maintained and the values of Q stress have been obtained from the analyses. The thermal loading initially has a strong effect on the Q value but at higher loads when the mechanical loading dominates, this effect is much weaker. The ability of a combined thermo-mechanical T stress approach to characterize the variation in constraint is assessed. 12:25 pm HIGH TEMPERATURE FRACTURE OF 6061/AI 20 3 MMC'S DEFORMED AT HIGH STRAIN RATES: P. Ganguly and Warren J. Poole, Department of Metals and Materials Engineering, The University of British Columbia" 309-6350 Stores Road, Vancouver, B.C., V6T lZ4 Canada The deformation of the particulate reinforced metal-matric composites (PRMMC) at high temperatures and high strain rates is of critical importance for a number of industrial forming applications, such as hot rolling and hot extrusion. The ductile fracture mechanism in this regime is the classic void nucleation, growth and coalescence, with the void nucleation arising from particle fracture or decohesion of the matrix-particle interface. To predict the onset of damage, it is important to be able to estimate the stress and strain states in and around the reinforcing particles. However, the situation is complicated by relaxation processes in the matrix, which tend to lower the stresses in the particles and at the matrix-particle interface. Furthermore, at large volume fractions (>0.25), the interaction between adjacent particles becomes significant resulting in substantially larger hydrostatic stresses which can aid or deter the formation of the voids depending on whether the hydrostatic stresses are compressive or tensile. The present work aims at studying the failure of PRMMC at high temperature (200°C to 550°C) and moderately high strain rates (0.1 to 10 s·'). Collar compression testing will be used to evaluate the ductility of these materials. The deformation of the macroscopic sample (i.e. wlo the explicit presence of the particles, but with the mechanical properties of the composite) has been modelled using the FEM code ABAQUS. The deformation at the particle length scale has been then determined by imposing the boundary conditions from the macroscopic model on a unit-cell FEM model with single or multiple particles. Metallographic examination of the fracture sites has also been conducted to aid the interpretation of the fracture mechanism.
SPRAY FORMING - EXPERIMENT, ANALYSIS, AND APPLICATIONS III: Applications Sponsored by: MDMD Shaping and Forming Committee, Jt. EPDlMDMD Synthesis Control & Analysis in Materials Processing Committee Program Organizer: Dr. Prabir K. Chaudhury, Concurrent Technologies Corporation, 1450 Scalp Avenue, Johnstown, PA, 15904; Prof. Enrique J. Lavernia, Department of Chemical Engineering and Materials Science, University of California, Irvine, CA
Thursday, AM February 13, 1997
Room: 330B Location: Orlando Convention Center
Session Chairperson: Dr. D.J. Chell man, Lockheed Martin Aeronautical Systems, Mariena, GA 30063
8:30 am KEYNOTE THE COMMERCIAL SCALE APPLICATION OF SPRAY FORMED MATERIALS: AJ. W Ogilvy, A.C. Lealham, Osprey Metals Ltd., UK Advanced materials produced by the Osprey Process are satisfying an ever wider range of applications. The driving force for process substitution may be either cost, property improvement or novel materials which are unobtainable using any other production route. This paper will discuss examples of spray-formed materials in the aerospace, automotive, metal processing and electronic industries. In each case, the reasons for the successful commercial application of the materials will be discussed. In addition, details of the requirements for large-scale production of spray-formed alloys and process developments to reduce costs and improve product reproducibility will be given. Post processing of the as-sprayed products to satisfy customer requirements will also be covered. 9:00am NAVY RESEARCH AND DEVELOPMENT IN METAL SPRAY FORMING: Richard Rebis, Materials Engineer, Naval Surface Warfare Center, Carderock Division (NSWC-CD), Code 6120, Bethesda, MD 20084-5000; Craig Madden, Director, Manufacturing Programs, NSWC-CD, Code 7206, Bethesda, MD 20084-5000; Patricia Mahoney, Mechanical Engineer, NSWCCD, Code 7220, Bethesda, MD 20084-5000 The Metal Spray Forming Technology Group of the Naval Surface Warfare Center, Carderock Division (NSWC-CD) has conducted research in support of Navy and private industry programs. In the spray forming process, a liquid stream of molten metal is atomized into a spray of semi-solid, semi-liquid particles and the metal spray is subsequently collected onto either a cylindrical or flat substrate that is rotating and translating underneath the spray. Spray forming produces a characteristic fine equiaxed, nearly-full dense microstructure in a near net shape product which can be subsequently processed. NSWCCD has both non-reactive and reactive metal (titanium) R&D spray forming facilities. The non-reactive facility has a 300 lb. Melt capacity and is used to produce nickel, steel, or copper alloy parts. Over 380 runs have been conducted on this R&D plant since 1988. This facility is also used to produce prototype parts in support of the Navy Manufacturing Technology spray forming plant, which is currently operated by Babcock & Wilcox. In 1995, NSWCCD installed a Reactive (Titanium) Metal Spray Forming Facility. The facility utilizes cold wall "skull" induction melting to produce up to 75 pounds of molten titanium (7000) cm3, 424 in 3) for spray deposition. Recent results from both plants will be presented. 9:20am PLASMA SPRAY FORMING OF COMPOSITES: APPLICATIONS AND MARKET ANALYSIS: R.S. Thakur, Materials Procurement Division, Hindustan Motors Company, Indore, India; M. Sisodia, M. K. Bhargava, Dept. of Metallurgical Engineering, Malaviya Regional Eng. College, Jaipur, India 302017 Plasma Spray Forming is a droplet deposition method which involves the steps of melting, rapid solidification, and consolidation into a single operation. The advancement of technology enables the processing a wide range of
metals, intermetallics, and ceramic matrix composites. The advent of Vacuum Plasma Spraying (VPS), which has opened a new dimension in Plasma Spray Forming of these materials, is outlined. The main considerations are being given to fiber reinforced metal matrix composites (MMCs) and ceramic matrix composites for their potential uses in different industrial fields, especially in making automotive engine components like pistons, cylinder liners etc. A brief case study specifically based on its annual production, cost factors, and marketing survey are discussed at length. 9:40am THE INFLUENCES OF AGING PRACTICE ON THE MICROSTRUCTURE AND TENSILE PROPERTIES OF SPRAY CAST AI-3Li-1Cu0.6Mg-0.3Zr ALLOY SHEET: D.L. Yaney, Lockheed Martin Missiles and Space, Palo Alto, CA 94304; DJ. Chellman, Lockheed Martin Aeronautical Systems, Marietta, GA 30063 A spray cast aluminum-lithium alloy with nominal composition AI-3Li-1Cu0.6Mg-0.3Zr (wt. %) has been successfully processed into 0.090 in. thick sheet. Following solutionizing at 540° C, selected combinations of quenching, stretching and aging treatments were evaluated in terms of their effect on the tensile properties of the final sheet product. Transmission electron microscopy was used to characterize the microstructural changes introduced by variations in aging practice. Although the maximum attainable yield strength was observed to increase with decreasing aging temperature, the double aging treatment of 3 hours at 170°C followed by 26 hours at 190°C, originally investigated by Gregson and Flower for similar direct chil cast Al-Li alloys, was shown to be effective in minimizing the in plane anisotropy frequently observed in AI-Li-Cu-Mg-Zr sheet products. 10:00 am BREAK 10:20 am PROPERTIES OF SPRAY FORMED NON-HEAT TREATABLE ALUMINUM ALLOYS: M.F. Amateau, H. Patts, TJ. Eden, The Pennsylvania State University, Applied Research Laboratory, P.O. Box 30, North Antherton Street, State College, PA 16804 Non-heat treatable aluminum alloys rely on a combination of solid solution hardening and plastic deformation to achieve usable strength. TheAI-Mn and AI-Mn-Mg alloys (3000 series) are used in applications requiring a high degree of deep drawing capability. Improved formability an drawability require high degree of ductility which depends upon rolling texture, recrystallization texture, grain size uniformity, and grain morphology. Spray metal forming produces a very fine and controlled starting microstructure which can have a profound effect on subsequent mechanical working and heat treatments. DC cast and spray metal formed AI-Mn and AI-Mn-Mg alloys were deformed to various amounts after which, microstructure and crystallographic texture were determined via x-ray diffraction pole figures. Subsequent recrystallization treatments were applied to evaluate the effect of the spray formed microstructure on recrystallization texture, recystallization kinetics, grain size, grain uniformity and mechanical anisotropy. 10:40 am WEAR MECHANISMS IN SPRAY FORMED SILICON-ALUMINUM ALLOYS: D.S. Lee, M.F. Amateau, J.C. Conway, The Pennsylvania State University, Applied Research Laboratory, P.O. Box 30, North Atherton Street, State College, PA 16804-0030 Aluminum-silicon alloys, especially hypereutectic silicon compositions are finding increasing use in automotive components that are subjected to sliding contact. Conventional DC casting methods for processing these alloys result in unsuitably large primary silicon particles for subsequent extrusion and forging. Three spray cast hypereutectic aluminum-silicon alloys were processed to various states of extrusion, heat treatment and over aging. Wear measurements have been performed using the pin-on-ring configuration in the unlubricated condition sliding velocities of 4.46 mls. The ring mating surfaces were grey iron. As cast B390 aluminum alloy was also wear tested for a standard of comparison. The worn surfaces were examined by scanning electron microscopy, electron beam microprobe analysis, and cross section microscopy to determine the nature and mechanism of wear.
11:00 am THE USE OF TUNGSTEN BORIDE AS POWDER ELECTRODE MATERIAL FOR ELECTRO-SPARK ALLOYING OF STEELS: S. V. Nikolenko, Institute of Material Science, The Far Eastern Branch of Russian Academy of Sciences, Khabarovsk, Russia The current development of technology is followed by the more and more complex demands for construction materials. In many cases the use of a combined material that has both the necessary hardness of the base and the high resistance of the outside layer to the environmental factors and wear is most efficient. This can be achieved by applying different kinds of protective coatings. Electro-spark alloying is one of perspective methods of coating deposition. This paper discusses the process of depositing the tungsten boride base composite powder material using a powerful impulse discharge, developed in a semi-closed volume with an electric field, accomplished by interaction of the powder units with the discharge plasma fed into the electrode space in gaseous environment. The process is conducted on a "Rasryad-3A" set, designed for coating with powder electrode materials. 11:20 am GEOMETRICAL ASPECTS OF THE SPRAY FORMING PROCESS: B. Cantor, Department of Materials, Oxford University, Parks Road, Oxford OXI3PH, UK This paper describes a number of geometrical aspects of the shaping, heat flow, and microstructure in materials manufactured by different variants of the spray forming process. In particular that paper will discuss: (i) the transition from an initial chilled structure to a bulk equiaxed structure as spraying proceeds; (ii) the difference between thermal sprayed splat microstructures and incremental solidification; (iii) the effect of steps and other features on the substrate; and (iv) multiple sprays and multipassing with a single spray and their effect on banded structures.
SYNTHESIS OF LIGHT-WEIGHT METALLIC MATERIALS II: Session VII: Casting, Spray Forming and Plasma Processing Sponsored by: MSD Synthesis/Processing Committee Program Organizers:C.M. Ward-Close, Structural Materials Center, R50 Building, Defense Research Agency, Farnborough, Hampshire, GU14 6TD, United Kingdom; F.H. Froes, University of Idaho, Institute for Materials and Advanced Processes, Mines Bldg 204, Moscow, ID 83844·3026; D.J. Chellman, Lockheed Aeronautical Systems Co., Lockheed Corporation, Marietta, GA 30063-0150; S. S. Cho, Vice President of Rapidly Solidified Materials Research Center, (RASOM), Chungnam National University, Taedok Science Town, Taejon 305-764 Korea Thursday, AM February 13, 1997
Room: 330F Location: Orlando Convention Center
Session Chairpersons: A.K. Ghosh, University of Michigan, Ann Arbor, MI; J.v. Wood, Department of Materials Engineering and Materials Design University of Nottingham, UK
8:30am SPRAY FOAMING OF HIGH PERFORMANCE ALUMINIUM GOES FOR VOLUME PRODUCTION: Klaus Hummert, PEAK Werkstroff GmbH, Velbert, Germany Very recently the major break-through in spray forming of high performance aluminium has been achieved. After many years of intensive alloy and process development, the first long time volume application could be realised. The use of PM aluminium for cylinder liners in gasoline passenger car engines gives strong improvements in the system of piston, piston rings and liner running surface. Furthermore the engine emissions have been reduced drastically. Based on the progress made with respect to technical and economical aspects this first volume production will have great impact on other application in automotive and aircraft industries or for leisure equipment. The paper describes the state of the art spray forming of aluminium based alloys under technical and metallurgical aspects. Examples will be given sev-
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eral applications in different market sections with functionally relevant test results. Finally the economical situation of spray forming will be discussed in comparison to competitive technologies.
gime and isothermally upset-deformed. The effects of the solid fraction during semi-solid deformation, deformation rate, and deformation temperature on the morphology, macrostructure, and stress-strain relationships of semisolid deformed billets were investigated and compared to those of conventional deformed billets. A phenomenological model was developed to help explain the different behaviours of the semi-solid deformed billets.
8:50am FABRICATION OF LOWER THERMAL EXPANSION ALUMINIUM ALLOYS BY SPRAY-CASING PROCESS: Chong-Sung Park, Hyun-Hp Park, Myung-Ho Kim, R.A.S.O.M., Department of Metallurgical Engineering, Inha University, Inchon 402-751, Korea
10:10 am BREAK 10:30 am COMPARISON BETWEEN PLASMA PROCESSED NANOCRYSTALLINE Fe AND ITS PRECURSOR IN POWDER AND COMPACT FORMS: Xiaofu Chen, E.G. Baburaj, Wenxian Zhu*, Patrick R Taylor*, EH. (Sam) Froes, Peter C. Kong+, Institute for Materials and Advanced Processes (!MAP); University of Idaho, Moscow, ID-83844-3026, USA. *Department of Metallurgical and Mining Engineering, University of Idaho, Moscow, Idaho, 83844-3024 USA; +Lockheed Idaho Technologies Company, Idaho Falls, Idaho 83415-2210
Spray-casting process is becoming increasingly attractive as an alternate production route for particulate reinforced metal matrix composites, and the coefficient of thermal expansion (CTE) of the composites can be controlled by altering the level of reinforcement. In this study, performs of A I-Si matrix composites reinforced with SiCp were fabricated by spray-casting process, and the coefficient of thermal expansion (CTE) of the composites were investigated using thermal mechanical analysis (TMA) after hot-extruded. It was found that the CTE of the composite with SiCp reduced with increase in volume fraction of SiC particles, and the A I-Si performs without SiCp also exhibited reduced CTE compared to mold-cast specimen. The effect of the grain and Si phase size, and the aspect ratio of Si phase, as well as the volume fraction of the SiCp on the CTE of the A I-Si composite have also been examined.
Nanocrystalline Fe powder has been produced from 1-4 mm size initial powder, using non-transferred arc plasma processing. Both the processed and initial powders have been consolidated by HIPing at different temperatures to determine the lowest possible processing temperature-time combination which gives rise to full densification. The fine powders and consolidation products have been characterised in detail for particle size, structure and morphology by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and the results have been used as feedback to improve the processing conditions. The particle size of plasma processed Fe powered is in the range of 10-50 nm. The temperature dependent grain growth of plasma processed and starting Fe powders have also been examined in this study.
9:10am PRODUCTION OF CONTINUOUS POLYCRYSTALLINE AI-Cu RIBBONS BY PLANAR FLOW CASTING AND SOLIDIFICATION STRUCTURES: Department of Metallurgical Engineering, Yonseu University, 134 Shinchon-dong, Seodaemun-gu, Scoul, Korea The geometry and microstructures of ribbons spun by planar flow casting have been investigated as functions of processing parameters adapting various kinds of crucial material and slot design. Microstructural transitions from segregation free zones to cellular/dendrite regions increased with increasing wheel velocity and the superheat of molten metal before ejection. X -ray diffraction spectra indicated an increasing tendency towards a (200) preferred orientation on the wheel-side surface of the ribbon with increasing the superheat of molten metal. A model based on a two-dimensional cellular automaton technique coupled with the control volume method was developed for the prediction of dendrite grain structures in planar flow casting. The calculated grain structures were in good agreement with those obtained from experimentation.
10:50 am STUDY OF MICROSTRUCTURE AND PROPERTIES OF SPRAY FORMED AI-Cr-Zr ALLOYS: A.E Norman, P. Tsakiropouios, Department of Materials Science and Engineering, University of Surrey, Guildford, Surrey GU2 5XH, UK The technical problems and cost associated with the multi-step PM processing of RS Al alloys have hindered their successful development. Spray forming can obviate these problems by means of the integral inert gas atomisation and deposition operation in which the alloy exists in particulate form only for a few milliseconds. Spray forming experiments have been performed on A 1Cr-Zr alloys studied previously by the combined RSIPM route. The microstructure and the tensile properties of the forged and heat treated deposits will be compared with the RSIPM alloy. The latter exhibits superior properties, not matched by the spray formed alloy.
9:30am COLUMNAR-EQUIAXED TRANSITION OF SOLIDIFICATION STRUCTURES IN SQUEEZE CASTING: I.S. Cho, c.P. Hong; RASOM, Department of Metallurgical Engineering, RASOM Yonsei University 134 Shinchon-dong, Seodaemun-ku, Seoul 120-749, Korea
11:10 am EFFECT OF ALLOY ELEMENTS ON THE DAMPING CAPACITY OF SPRAY CAST AI-Zn ALLOY: B.C. Moon, Z.H. Lee, Department of Materials Science and Engineering, RASOM, Kaist, Korea
The CET(Columnar-Equiaxed Transition) of solidification structures in squeeze casting of AI-Cu alloys was investigated. The interfacial heat transfer coefficient between the casting and the mold was evaluated using an inverse problem method. Solidification sequences in squeeze casting were simulated using the calculated interfacial heat transfer coefficients. The cellular automaton coupled with the control volume method was developed for the predication of solidification grain structures and was applied to evaluate the CET in squeeze casting. The effects of casting process variables, such as pressure, pouring temperature, mold temperature and inoculation on the CET in squeeze casting were investigated. The solidification parameters, solidification rate and thermal gradient at the solidification front, were also analyzed in regard to their effects on the CET. The calculated results were also compared with those obtained experimentally.
Damping capacity of a material refers its ability to dissipate vibrational energy into thermal energy. In AI-Zn system, damping originates form the interfacial friction between two phases and the damping capacity is proportional to the interfacial area. The microstructure of spray cast alloys are very different from the cast alloys and the damping characteristics of spray cast AI-Zn alloys is expected to be also different. In this study, the effect of third element on the damping behaviour of spray cast AI-Zn alloys was studied. l-Zn-X alloys were made by spray cast and mold cast. Third elements were Cu, Mg and Mn. Uniformly rolled cast and sprayed specimens were solution treated then quenched by water. Specimens were aged at room temperature for 24 hours. Damping capacity was measured by logarithmic decrement of freely decayed vibration of cantilever beam. Damping capacity of spray cast alloys was higher than cast alloys. Dilute tried elements increased the hardness but decreased the damping capacity alightly.
9:50am SEMI-SOLID PROCESSING OF A356 AI ALLOYS: C.P. Chen, C.-Y.A. Tsao, Department of Materials Science and Engineering National Cheng-Kung University Tainan, Taiwan A356 Al alloys were synthesised and processed in the semi-solid state. The alloys with a non-dendrite structure were synthesised via electromagnetic stirring in the semi-solid state and then subsequently cast into billet form. The billets with non-dendrite structure were then reheated to semi-solid re-
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11:30 am PRODUCTION OF CONTINUOUS POLY CRYSTALLINE AI·Cu RIB· BONS BY PLANAR FLOW CASTING AND SOLIDIFICATION STRUCTURES: S.M. Lee, K.Y. Lee, C.P. Hong; RASOM Department of Metallurgical Engineering, Yonsei University 134 Shinchon-dong, seodaemunku, Seoul 120-749, Korea The geometry and microstructures of ribbons spun by planar flow casting have been investigated as functions of processing parameters adapting various kinds of crucible material and slot design. Microstructural transitions from segregation free zones to cellular/dendritic regions were obsened in AlCu alloys. The thickness ratio of columnar layer increased with increasing the wheel velocity and the superheat of molten metal before ejection. X-ray diffraction spectra indicated an increasing tendency towards a (200) preferred orientation on the wheel-side surface of the ribbon with increasing the superheat of molten metal. A model based on a two dimensional cellular automaton technique coupled with the control volume method was developed for the prediction of dendritic grain structures in planar flow casting. The calculated grain structures were in good agreement with those obtained experimentally. 11:50 am OPERATING PARAMETERS FOR THE CONTINUOUS UNIDIREC· TIONAL SOLIDIFICATION OF A 1 % Si ALUMINUM ALLOY DRAWN TO FINE WIRE: M.H. Kim, Chungbuk National University and RASOM, Cheongju Korea; T.S. Song, Chungbuk National University, Cheongju, Korea; H.H. Jo, Korea Academy ofIndustrial Technology, Incheon, Korea; C.S. Kang, Seoul National University, Seoul, Korea; C.R. Loper, Jr., The University of Wisconsin-Madison, Madison, WI Previous studies have demonstrated the technique of producing continuous cast, directionally solidified castings of a limited number of alloys. These procedures have been successful when the casting conditions are established so that the solid-liquid interface is maintained outside of the mold by insuring a mold temperature in excess of the liquidus temperature and a solid-liquid interface located near enough to the mold so that the molten metal surface tension is able to support the liquid phase. Rods varying from 3 to 10 mrn. (0.12 to 0.39 in.) D. have been successfully cast in this manner. This study has expanded that technique to a 1% Si aluminum alloy, and the casting, and the casting conditions which would enable production of an 8 mm. (0.31 in). D. rod having a mirror surface with a highly longitudinally oriented microstructure have established. Furthermore it was demonstrated that this alloy could be wire drawn, without the need of intermediate recrystallization or stress relief, to produce wires of 0.14 to 0.10 mm. (0.0055 to 0.0039 in) D.
UPDATE OF THE PRACTICE OF COPPER ELECTROREFINERY BLEED-OFF TREATMENT Sponsored by: EPD Copper, Nickel, Cobalt Committee Program Organizers: Norbert L. Piret, Piret & Stolberg Partners, 1m Licht 12, 047279 Duisburg, Germany; Ivan M. Santos Moraes, Caraiba Metals, Dias D'Avila, Bahia, Brazil Thursday, AM February 13, 1997
Room: 3400 Location: Orlando Convention Center
Session Chairpersons: N.L. Piret, Piret & Stolberg Partners, 1m Licht 12, 0-47279 Duisburg, Germany; Ivan M. Santos Moraes, Caraiba Metals, Dias D'Avila, Bahia, Brazil
8:30 am INVITED ASPECTS OF IMPURITIES CONTROL AT CARAIBA METALS ELECTROREFINERY: Jose Luiz Rodrigues Bravo, Caralba Metais S.A.(CMSA), Via do Cobre W 3700, A.l.O. - Copec, Dias D' Avila - BahiaBrazil The production of electrolytic copper with assured quality corresponding to international standards in a conventional electrorefinery of a custom smelter, is a hard and cautious task, if no advanced technologies for selective control of electrolyte impurities are available. The improper control of the amount of 1M
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As, Sb and Bi in the anode that enter de tankhouse, attributable either to a bad schedule of concentrate input or to the unavailability of clean concentrates from the international market, as well as the lack of means to maintain the suitable level of these elements in the electrolyte together with other operational circumstances, can result in off-grade copper, as well as affect the starting sheet quality chemically and physically. This paper presents in a practical way the relationship between the operational conditions and the cathode and starting sheet quality produced at CMSA, covering the period of the last five years of operation, discusses the technologies available in the market for antimony and bismuth removal and compares the results of testwork, achieved in the laboratories of CMSA, using two resins not associated with patented technologies. 9:00am REMOVAL OF ANTIMONY AND BISMUTH FROM COPPER ELEC· TROLYTE DEVELOPMENT OFACOMMERCIALPLANTATAMA· RILLO COPPER REFINERY: R.M. Cunningham, Asarco Inc, Amarillo, TX; J.v. Calara & M.K. King, Asarco Technical Services Center, Salt Lake City, UT Asarco operates one of the largest individual copper electrorefineries in the world at Amarillo, Texas. The feed is a mixture of anodes from Asarco smelters and copper purchased from various primary and secondary sources. The variation in feed makes it imperative that the refinery practices state-of-theart quality control to minimize the effects of unwanted impurities. In late 1993, a plant designed to significantly reduce the antimony and bismuth levels in the electrolyte was commissioned. The purification plant uses ion exchange technology in conjunction with a novel stripping system developed by Zeneca Specialties, which permits the recycling of the eluant. Thereby, the extremely high costs of stripping with conventional reagents are avoided. In addition, the environmental impact of treating the eluant for recovery of antimony and bismuth is minimized. This paper outlines the development of the technology and, in particular, describes the operational practices and improvements at Amarillo since the commissioning of the plant. 9:30 am INVITED BLEED· OFF TREATMENT OF HK·SECONDARY COPPER ELECTROREFINERY: Dr. R. F. Dobner, Huttenwerke Kayser AG, Posffach 1560, D44505 Lunen After a short introduction of the electrolysis process at HK and explanations concerning the anodes used, the regulation and buffering of bleed will be described and the principles of technology for processing of bleed will be presented. Modernization aspects, especially installation equipment, and the different types of evaporators used will be described in detail. Besides experience made with acid-resistant materials - stainless steel, enamel, plastics will be reported. Environmental aspects such as water and air pollution will be outlined briefly and in conclusion the quality of products obtained as well as quality control will be presented. 10:00 am BREAK 10:20 am INVITED PROCESS OPTIONS IN THE TREATMENT OF COPPER REFINERY ELECTROLYTE BLEED: James E. Hoffmann, Jan H. Reimers & Associates USA Co., P.O. Box 420545, Houston, TX This paper will briefly review the conventional technologies employed for the treatment of copper refinery electrolyte bleed. The distinction between decopperizing and electrolyte purification will be emphasized. The strengths and weaknesses of conventional practice will be reviewed and a number of process options to addtess the weaknesses of present process technology will be described and evaluated. The effect of process selection upon energy consumption and the environmental aspects of process effluent control will be discussed.
10:50 am IMPROVING THE QUALITY OF THE NICKEL SULFATE HEXAHYDRATE PRODUCED AT CARAiBA BY APPLYING THE QUALITY FUNCTION DEPLOYMENT METHOD (Q.F.D.): Ivan Marcelo Santos Moraes and Group of Q.F.D., Caraiba Metais S.A., Via do Cobre N° 3700, A.I.O. - Copec, Dias D' Avila - Bahia Brazil, CEP 42800-000
sulfate hexahydrate. The team, formed with representatives of the following areas: production, technology, marketing, sales, maintenance, laboratory and TQC office, had also the task of checking the applicability of the method to other products of the company. This paper describes the main steps such as the survey of customer's demands, the preparation of the quality matrix, the planned and the designed quality and the consequent identification of the engineering bottlenecks. It is also shown how these bottlenecks were studied and solved. The application of the method allowed the team to identify means of increasing the production capacity by 40 %, to improve the intrinsic quality of the product (including packaging), and to increase the reliability of the process.
Caraiba Metais has a plant for the purification and the crystallization of the crude nickel sulfate removed from its copper electrolyte purification system. In November 1994, an interdepartmental group was formed to study the Q.F.D method, through its application on the improvement of the quality of the nickel
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