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Cold welding effect in silver compacts after acid-assisted consolidation
HSS with 5%VC particles were investigated. Particles below 100 pm and and sintering in N rich gas were used. Hardened and tempered samples gave maximum Vicker’s hardness of 930. Effect of tempering temperature on fracture stress was analyzed. Fractography showed effects of pores and VC particles. T42
DILATOMETRIC STUDY OF M2/3 HIGH SPEED STEEL WITH NIOBIUM AND TENTALUM
CARBIDES
E. Gordo et al. (National Centre for Metallurgical Investigations, Madrid, Spain). A dilatometric investigation of the thermal behaviour of M2/3 HSS with additions of NbC, TaC and Cu3P, as a sintering aid, was described. The objectives were to optimize sintering and heat treatment conditions.
Aluminium
sintering
PARTICLE SIZE EFFECTS IN MULTICOMPONENT ALUMINIUM ALLOYS R.N. Lumley, G.B. Schaffer (University of Queensland, Brisbane, Australia.) Structural evolution during LPS of Al alloys was investigated with regard to composition and effects of additive particle size. It was reported that larger prticles increased the amount of liquid phase. Structural development was shown to be influenced by interactions between alloy elements and was discussed in terms of solubility and diffusion effects. SINTERING OF HIGH TEMPERATURE RESISTANT PM ALUMINIUM ALLOYS J. Duszczuk et al. (Technological University, Delft, The Netherlands.) AI-BO%Si-X alloys were discussed with reference to automotive applications. Gas atomized A1-20%Si-5%Fe-2%Ni powders were characterized and fabricated by uniaxial pressing or CIP and sintered at a range of temperatures in N or air. Structure and properties were described. N atomized powder gave better part properties than air atomized powders.
Machinability ENHANCED MACHINABILITY OF VALVE GUIDES MADE FROM PM MATERIALS K. Hayashi et al. (Hitachi Powdered Metals Co. Ltd., Chiba, Japan.) It was noted that valve guides need wear resistance in service but machinability during manufacture. PM guides made from Cu-Sn-C-P steel were reported to have adequate wear resistance but machinability needed improvement. Machining enhancers, including MnS, were investigated. Machinability was shown to be enhanced without loss of wear resistance.
MACHINABILITY OF SINTERED 316L STAINLESS STEEL U. Kutsch, P. Beiss (Inst. for Materials Science, Germany.) Investigation of the effects of MnS content, sintering atmosphere and cutting conditions on dry drilling machinability of 316L stainless steel was described. MnS improved machinability in terms of tool life and cost per hole. The results were reported to allow quantified minimization of production costs. INFLUENCE OF MACHINING PARAMETERS ON MACHINABILITY OF SINTERED STEELS L. Hultman (Hans AB, Hans, Sweden.) Complexities of machining were discussed with reference to cutting conditions and work material characteristics. A range of cutting operations were carried out on several sintered steels. Cutting forces, surface finish, wear patterns and other factors were determined for different tools and machining parameters. Recommendations were given.
Powder production MONODISPERSE METAL POWDERS OF CONTROLLED SIZE AND SHAPE MADE BY POLYOL PROCESS K. Tekaia-Elhsissen, P.Y. Silvert (University of F’iccardy, France.) The need for metal powders on high purity and uniform size and shape was noted. Production of metal powders by reduction of a metal salt in a non-aqueous solvent, polyol, was described with reference to stages in the process, dissolution of the salt, reduction, nucleation and growth of particles and effects of reaction parameters. It was reported that a range of metal and alloy powders with controlled size and shape had been made. POWDER PRODUCTION METHODS FOR HYDROGEN STORAGE MATERIALS MJ. Hohmann, H.J. Klemmer (ALD Vacuum Technologies GmbH, Germany.) The potential of PM technologies for mass production of materials for H storage was noted. The paper reviewed methods for production of rapidly solidified high purity material of defined fine grain size, which are required for H storage, including melt spinning, atomization and crushing of bulk materials. Results were presented.
1996 WORLD CONGRESS DER METALLURGY. The
ON POWabstracts
which follow are of papers which were presented
at the Congress
held in Washington, 1996.
which wss
DC, UsA, in Jane
lsostatic pressing ADVANCED
DIFFUSION
BONDED
HIP
COMPOSITES
P. Durdoth, H. Seilstorfer (Seilstorfer GmbH, Germany). Production of parts with wear and corrosion resistant coatings was discussed. Coatings were Fe, Ni or Co based hardmetals. Due to the difficulty of machining hardmetals the importance of near net shape forming was emphasized. It was suggested that PM technologies and HIP diffusion bonding in combination provided a production route for parts which cannot otherwise be made. EFFECT OF PROCESS AND HIP PARAMETERS ON PROPERTIES OF PM COMPOUND STRUCTURES A. Jokinen, J. Limatainen (VlT Manufacturing Technology, Finland). Economics of PM part production were discussed with regard to the use of expensive materials only in areas where needed to meet service conditions. It was shown that HIP makes it possible to make parts containing different materials at full density with good bonding between materials. A range of compounds, such as stainless/low C alloy, was investigated using a range of methods. Structures and properties were described DENSIFICATION OF UDIMET700 BASED POWDER COMPOSITES DURING HOT ISOSTATIC PRESSING A.M. Laptev et al. (Inst. for Materials and Energy Technology, Germany). A theoretical and experimental study of densification of UDIMET700 based composites with 5 or 10% A1203 or TiBZ was described. The theoretical study used creep theory for porous materials. Input data were determined for compression tests and HIP experiments. The reinforced and plain alloys were compared to determine effects of A1203 and TiBz on creep properties. Experiments were shown to validate the theoretical calculations. COLD WELDING EFFECT IN SILVER COMPACTS AFLER ACID-ASSISTED CONSOLIDATION L. Levin et aL. (Ben-Gurion University, Israel). It was reported that acid treatment of Ag powder promotes consolidation into cohesive solids. The mechanical properties showed enhanced values which were attributed to cold welding effects. Scanning electron microscopy showed fracture characteristics at particle/particle contact zones. The study showed the possibility of powder compaction at ambient temperature to give solids with moderately high strength.
MPR December 1996 37
DILATOMETRIC STUDY OF M2/3 HIGH SPEED STEEL WITH NIOBIUM AND TENTALUM
CARBIDES
E. Gordo et al. (National Centre for Metallurgical Investigations, Madrid, Spain). A dilatometric investigation of the thermal behaviour of M2/3 HSS with additions of NbC, TaC and Cu3P, as a sintering aid, was described. The objectives were to optimize sintering and heat treatment conditions.
Aluminium
sintering
PARTICLE SIZE EFFECTS IN MULTICOMPONENT ALUMINIUM ALLOYS R.N. Lumley, G.B. Schaffer (University of Queensland, Brisbane, Australia.) Structural evolution during LPS of Al alloys was investigated with regard to composition and effects of additive particle size. It was reported that larger prticles increased the amount of liquid phase. Structural development was shown to be influenced by interactions between alloy elements and was discussed in terms of solubility and diffusion effects. SINTERING OF HIGH TEMPERATURE RESISTANT PM ALUMINIUM ALLOYS J. Duszczuk et al. (Technological University, Delft, The Netherlands.) AI-BO%Si-X alloys were discussed with reference to automotive applications. Gas atomized A1-20%Si-5%Fe-2%Ni powders were characterized and fabricated by uniaxial pressing or CIP and sintered at a range of temperatures in N or air. Structure and properties were described. N atomized powder gave better part properties than air atomized powders.
Machinability ENHANCED MACHINABILITY OF VALVE GUIDES MADE FROM PM MATERIALS K. Hayashi et al. (Hitachi Powdered Metals Co. Ltd., Chiba, Japan.) It was noted that valve guides need wear resistance in service but machinability during manufacture. PM guides made from Cu-Sn-C-P steel were reported to have adequate wear resistance but machinability needed improvement. Machining enhancers, including MnS, were investigated. Machinability was shown to be enhanced without loss of wear resistance.
MACHINABILITY OF SINTERED 316L STAINLESS STEEL U. Kutsch, P. Beiss (Inst. for Materials Science, Germany.) Investigation of the effects of MnS content, sintering atmosphere and cutting conditions on dry drilling machinability of 316L stainless steel was described. MnS improved machinability in terms of tool life and cost per hole. The results were reported to allow quantified minimization of production costs. INFLUENCE OF MACHINING PARAMETERS ON MACHINABILITY OF SINTERED STEELS L. Hultman (Hans AB, Hans, Sweden.) Complexities of machining were discussed with reference to cutting conditions and work material characteristics. A range of cutting operations were carried out on several sintered steels. Cutting forces, surface finish, wear patterns and other factors were determined for different tools and machining parameters. Recommendations were given.
Powder production MONODISPERSE METAL POWDERS OF CONTROLLED SIZE AND SHAPE MADE BY POLYOL PROCESS K. Tekaia-Elhsissen, P.Y. Silvert (University of F’iccardy, France.) The need for metal powders on high purity and uniform size and shape was noted. Production of metal powders by reduction of a metal salt in a non-aqueous solvent, polyol, was described with reference to stages in the process, dissolution of the salt, reduction, nucleation and growth of particles and effects of reaction parameters. It was reported that a range of metal and alloy powders with controlled size and shape had been made. POWDER PRODUCTION METHODS FOR HYDROGEN STORAGE MATERIALS MJ. Hohmann, H.J. Klemmer (ALD Vacuum Technologies GmbH, Germany.) The potential of PM technologies for mass production of materials for H storage was noted. The paper reviewed methods for production of rapidly solidified high purity material of defined fine grain size, which are required for H storage, including melt spinning, atomization and crushing of bulk materials. Results were presented.
1996 WORLD CONGRESS DER METALLURGY. The
ON POWabstracts
which follow are of papers which were presented
at the Congress
held in Washington, 1996.
which wss
DC, UsA, in Jane
lsostatic pressing ADVANCED
DIFFUSION
BONDED
HIP
COMPOSITES
P. Durdoth, H. Seilstorfer (Seilstorfer GmbH, Germany). Production of parts with wear and corrosion resistant coatings was discussed. Coatings were Fe, Ni or Co based hardmetals. Due to the difficulty of machining hardmetals the importance of near net shape forming was emphasized. It was suggested that PM technologies and HIP diffusion bonding in combination provided a production route for parts which cannot otherwise be made. EFFECT OF PROCESS AND HIP PARAMETERS ON PROPERTIES OF PM COMPOUND STRUCTURES A. Jokinen, J. Limatainen (VlT Manufacturing Technology, Finland). Economics of PM part production were discussed with regard to the use of expensive materials only in areas where needed to meet service conditions. It was shown that HIP makes it possible to make parts containing different materials at full density with good bonding between materials. A range of compounds, such as stainless/low C alloy, was investigated using a range of methods. Structures and properties were described DENSIFICATION OF UDIMET700 BASED POWDER COMPOSITES DURING HOT ISOSTATIC PRESSING A.M. Laptev et al. (Inst. for Materials and Energy Technology, Germany). A theoretical and experimental study of densification of UDIMET700 based composites with 5 or 10% A1203 or TiBZ was described. The theoretical study used creep theory for porous materials. Input data were determined for compression tests and HIP experiments. The reinforced and plain alloys were compared to determine effects of A1203 and TiBz on creep properties. Experiments were shown to validate the theoretical calculations. COLD WELDING EFFECT IN SILVER COMPACTS AFLER ACID-ASSISTED CONSOLIDATION L. Levin et aL. (Ben-Gurion University, Israel). It was reported that acid treatment of Ag powder promotes consolidation into cohesive solids. The mechanical properties showed enhanced values which were attributed to cold welding effects. Scanning electron microscopy showed fracture characteristics at particle/particle contact zones. The study showed the possibility of powder compaction at ambient temperature to give solids with moderately high strength.
MPR December 1996 37