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Cyclic properties of differently heat treated PM steels
carbide eutectics. The implications are discussed.
commercial
IMPROVED TOOL PERFORMANCE BY HEAT SPREADING DIAMOND LAYER IN A MULTI-LAYER COATING
N.Dedelik, B.Lux. (University of Technology, Vienna, Austria.) Int. J. Refractory Metals Hard Mater., Vol 17, No 4, 1999,275-282. Modelling of multi-layer coated cutting tools, with reference to the incorporation of a thick diamond layer, to spread heat and minimize hot spots, is discussed. It is suggested that this could lead to increased cutting speeds without use of coolants. IMPROVED DENSIFICATION OF TITANIUM NITRIDE-NICKEL BY ADDITION OF MOLYBDENUM CARBIDE
J.K.Park, S.T.Park. (Korea Inst. of Science and Technology, Seoul, Korea.) Int. J. Refractory Metals Hard Mater., Vol 17, No 4,1999,295-298. It is reported that the addition of Mo,C to TiN-Ni cermets improved densification, resulting from increased wetting between TIN and Ni. TiN-NiMo,C could be conventionally liquid phase sintered, in vacuum, to full density. Pore formation is attributed to evolution of N due to thermal dissociation of TIN. Addition of VC inhibited TIN grain growth and improved mechanical properties. SYNTHESIS OF TUNGSTEN CARBONITRIDE BY HEATING TUNGSTEN AND CARBON POWDERS IN NITROGEN
K.Hayashi et al. (University of Tokyo, Japan.1 J. Jpn Sot. Powder1 Powder Metall., Vol 46, No 4, 1999, 373-377. (In English.) It is noted that mono-nitrides of W and MO are not synthesized in low pressure N. Attempts to synthesize WN and W(C,N) by heating W or W-C powders in N at 190 MPa are reported. W(C,N) with 20at%N was formed but WN was not.
lntermetallic
materials
PM MANUFACTURE AND CHARACTERIZATION OF PARTS MADE FROM TITANIUM ALUMINIDE BASE ALLOYS
H.Kestler et al. (Plansee AG, Reutte, Austria.) 2. Metallkd., Vol 89, No 11, 1998, 772-778. (In German.) A method of producing near net shape automotive valves from PiAl, Ti46.5at%Al-4%(Cr, Nb, Ta, B), is described. Preforms were made by HIP of
28 MPR July/August 2000
gas atomized dimension. characterized mechanical fatigue.
powders to close to part The was material for structure and properties, including
Metal injection
moulding
MEASUREMENT OF NON-UNIFORM SHRINKAGE OF INJECTION MOULDED COMPACTS
R.Watanabe, Y.Mizuno. Denki Seiko (Electric Furnace Steel), Vol 69, No 2, 1998, 117-130. (In Japanese.) A non-contact system, for in situ measurement of non-uniform shrinkage during sintering of injection moulded and debound stainless steel compacts is described. Effects of process parameters were demonstrated with sufficient accuracy to relate to dimensional tolerances. VISCOSITY AND MELT RHEOLOGY MIM FEEDSTOCKS
OF
Y.Li et al. (Central South University of Technology, Changsha, China.) Powder Metall., Vol42, No 1, 1999,86-89. Viscosity and rheological properties of Fe-2%Ni feedstocks were investigated to determine effects of minor additives in the binder. Mechanical properties and shrinkage of injection moulded test-bars were measured.
PM components PM PROCESSING IMPLANTS
OF SURGICAL
R.M.Pilliar. (University of Toronto, Toronto, Canada.) Int. J. Powder Metall., Vo134, No 8, 1998,33-45. Use of PM to make surgical prostheses is discussed with regard to the need for rigid and reliable implantto-bone fixation. Some successful clinical uses are reviewed and current studies are outlined. The need for biocompatibility of materials and design is emphasized. PREPARATION OF POROUS METALS FROM CERAMIC PRECURSORS
S.M.Landin, D.W.Readey. Ceramic Trans., Vo194, 1999,1042-1122. Uses of porous metals are outlined. A method of making porous metal parts, by reduction of porous oxide ceramic precursors, is described. Control of porosity and pore size, of the metal part, is shown to be possible by control of the ceramic. The ceramic is pressed and sintered in a reactive atmosphere. Porous Ni and Fe, made by this technique, are evaluated.
PRODUCTION OF A HARD METAL ROLLER BY HIP DIFFUSION BONDING
F.Chen et al. Rare Metal/Mater. Eng., Vol 27, No 3, 1998,177-181. (In Chinese.) Fabrication of a roller, consisting of a Fe alloy base core and a cemented carbide case, by HIP diffusion bonding, is reported. Structures and performance of the roller are described. The case/core interface and some cracking are analysed.
Refractory
alloys
HIGH TEMPERATURE HEAT RESISTANT CHROMIUM-TITANIUMCARBON ALLOYS
B.D.Bryskin et al. (Inst. for Problems of Materials Science, Kiev, Ukraine.) Int. J Refract. Metals Hard Mater., Vol 17, No 4,1999,259-263. Structure and mechanical properties of eutectic Cr-Ti-C alloys, for application at 200 to 1200°C are reviewed and reported to be of practical value. The high possibility of improving temperature strength by alloying with Fe, SC, La, MO or Re is discussed.
Miscellaneous POWDER METALLURGY ANDREAS LIBAVIUS
AND
V.Dufek. (Consultant, Prague, Czech Republic.) Pokroky Praskove Metal., Vol 36, No 4,1998,46-50. (In Czech.) The paper reports that information concerning early production and use of metal powders is to be found in Alchemia, by A.Libavius, published in 1597. TECHNICAL COST MODELLING NEAR NET SHAPE PM MANUFACTURING
OF
R.V.Bhatkal, T.Hannibal. JOM (J. of Metals), Vol 51, No 7, 1999,26-27. The competitiveness of PM processes is analysed by technical cost modelling which compares process costs for a given product. Knowledge of the regions of competitive advantage is shown to provide a focus for application and funding and allows investment in the lowest cost process route for specific applications. PM’98. The Abstracts that follow are from papers presented at the 1998 Powder Metallurgy World Congress which was held in Granada, Spain, in
PM steels CYCLIC PROPERTIES OF DIFFERENTLY HEAT TREATED STEELS
PM
(University of K.H.Lang et al. Karlsruhe, Karlsruhe, Germany.) Mechanical properties of sintered, tempered and quenched and isothermally transformed 4%Ni-05%Mo0.5%C steels, at 7.21 g.cme3 density, and a similar 0.7%C sinter hardened steel, at 7.12 g.cm-“, were investigated. The structures are described. Tempered martensite, retained austenite, bainite, zones of Ni segregation and surface decarburization were found in the samples. Optimization of quenching and tempering gave the best combination of properties over other specimens. EFFECTS OF CARBON ON MECHANICAL PROPERTIES OF ULTRA-HIGH BORON STEELS
J.A.Jimemez et al. (CENIM, CSIC, Madrid, Spain.) Deformation characteristics at elevated and ambient temperatures, of a high B steel, 2.2%B, and a high C-B-Cr were steel, 1.3%X!-0.8%B-1.67&r, investigated. Samples were prepared by HIP for 2 hours at 180 MPa and 700°C. Structures were on a pm scale. Properties were affected by cooling rate only for the C-B-Cr steel. Superplasticity was detected in both steels. Creep data was consistent with grain boundary sliding and slip-creep models. HIGH PERFORMANCE PM FERROUS MATERIALS MADE USING MULTICOMPONENT
FINE POWDER
M.Yoshida, Y.Seki. (Kobe Steel Ltd, Huogo, Japan. 1 Martensite in steels and hardenability were discussed with reference to mechanical properties. It was reported that a high strength l.O%Mo-0.5%Ni steel had been made, using a fine multicomponent powder, with strength up to 1000 MPa. PM PREALLOYED STEELS AND PROCESS TECHNOLOGY
R.Link. (QMP Metal Powders GmbH, Miinchengladbach, Germany.) New applications for PM parts, requiring high performance, were shown to need high static and dynamic strength given by use of prealloyed steel powders in combination with appropriate heat treatment. Sinter hardening of steels containing MO, or MO and Ni, was reported to allow direct production of steel with martensitic or bainitic structures. Production of case hardening 3.5%Mo steel was illustrated. The steel was sintered at a high temperature in the c1 phase zone, without a liquid phase. Properties were described. DEVELOPMENT
OF A HIGH
STRENGTH PM STEEL WITHOUT QUENCHING
T.Tsutsui et al. (Hitachi Powdered Metals Co Ltd, Chiba, Japan.) It is reported that a steel with a martensitic structure had been produced at a cooling rate typical of a conventional sintering furnace. The steel had increased hardenability due to addition of alloying elements. The was designed for high powder compressibility and the composition determined by consideration of the ideal critical diameter to give a structure 95% martensite and 5% bainite when cooled at 0.15”C.s~‘. The application was a spiral bevel gear for a power tool.
Thermal spraying spray forming
and
ELECTROMAGNETIC CONTROL OF LIQUID METAL JETS FOR SPRAY FORMING AND ATOMIZATION
D.J.Short et al. (University of Cambridge, Cambridge, UK.1 The need to control the flow of metal to the atomizer, and thus determine droplet size and microstructure of powder or sprayed deposit was noted. Experimental work to this end was described. The technique was to use electromagnetic flow control involving and partial magnetic levitation magnetic field concentration to give a metallurgically clean method of modulating, stabilizing and positioning the molten metal stream. The technique was said to have implications in processing materials such as Ti and Ti alloys. EFFECTS OF GAS ATOMIZATION PARAMETERS ON SPRAY FORMING OF NICKEL BASE SUPERALLOYS (Beijing Inst. of G.Zhang et al. Aeronautical Materials, Beijing, China.1 Spray forming, as an alternative to conventional PM processes, was discussed with regard to use of N and Ar and concerns about N content and porosity. Studies, to attain dense spray formed products with low N contents and porosity, by optimization of spraying parameters, were described. Effects of a wide range of variables were investigated. It was shown that process variables influence type, size and distribution of porosity. Microstructures were also correlated with process conditions. STRUCTURAL CHARACTERIZATION OF SPRAY FORMED CEMENTED TUNGSTEN CARBIDE J.M.Guilemany et aL. (Centre de Projeccio Termica, Barcelona, Spain.) Ni-Cr-B-Si WC-12%Co/4Ovol% materials, made from two thermal spray
powders, were reported to have good properties for abrasion and wear. The WC-Co and Ni-Cr-B-Si powders were mixed and high velocity oxy-fuel sprayed on to a Cr-Mo steel substrate. The powders and the deposit were characterized for microstructure with the object of determining interactions between the two materials both in the flame and the deposit.
Nanocrystalline materials COMBUSTION FLAME SYNTHESIZED NANOPARTICLES
B.H.Kar et al. (Rutgers University, Piscataway, USA. 1 Applications of nanostructured particles, with particle sizes of 3 to 50 nm, were discussed with respect to properties of powders and fabricated materials. Novel chemical and physical methods of making metal, oxide and cermet nanoparticles are reviewed with emphasis on chemical vapour condensation. Powder characteristics in situ are described. A one-step deposition of process for without coatings, nanostructured using a powder intermediate, was outlined. METAL NANOPOWDERS FOR POLYMER MATRIX COMPOSITES G.Bernd, H.Schafer. (Fraunhofer Inst., Bremen, Germany.) It is reported that Ag powders, 0.1 to 0.15 pm in size, had been produced by inert gas atomization, with low levels of gaseous impurity which resulted in formation of a spongy deposit with porosity of 60 to 80%. This can be infiltrated even by viscous organic liquids. This was shown to give a method of making electrically conducting adhesives with a metal filling factor as of various low as 5~01%. Effects parameters are described. Mechanical properties were outlined. CONSOLIDATION OF REACTIVELY BALL MILLED ALUMINIUM-TITANIUM POWDERS K.S.Lee, K.Moon. (Hanyang University, Seoul, Korea.) Al-T1 powders were mechanically alloyed in H to a grain size less that 20 nm. Samples were consolidated by various methods and characterized to find the best method that would preserve the nanocrystalline structure. Hot extrusion, plasma activated sintering and high pressure sintering, at 4.5 GPa, were investigated. The object was to reduce process time to limit grain growth.
MPR July/August
2000 31
commercial
IMPROVED TOOL PERFORMANCE BY HEAT SPREADING DIAMOND LAYER IN A MULTI-LAYER COATING
N.Dedelik, B.Lux. (University of Technology, Vienna, Austria.) Int. J. Refractory Metals Hard Mater., Vol 17, No 4, 1999,275-282. Modelling of multi-layer coated cutting tools, with reference to the incorporation of a thick diamond layer, to spread heat and minimize hot spots, is discussed. It is suggested that this could lead to increased cutting speeds without use of coolants. IMPROVED DENSIFICATION OF TITANIUM NITRIDE-NICKEL BY ADDITION OF MOLYBDENUM CARBIDE
J.K.Park, S.T.Park. (Korea Inst. of Science and Technology, Seoul, Korea.) Int. J. Refractory Metals Hard Mater., Vol 17, No 4,1999,295-298. It is reported that the addition of Mo,C to TiN-Ni cermets improved densification, resulting from increased wetting between TIN and Ni. TiN-NiMo,C could be conventionally liquid phase sintered, in vacuum, to full density. Pore formation is attributed to evolution of N due to thermal dissociation of TIN. Addition of VC inhibited TIN grain growth and improved mechanical properties. SYNTHESIS OF TUNGSTEN CARBONITRIDE BY HEATING TUNGSTEN AND CARBON POWDERS IN NITROGEN
K.Hayashi et al. (University of Tokyo, Japan.1 J. Jpn Sot. Powder1 Powder Metall., Vol 46, No 4, 1999, 373-377. (In English.) It is noted that mono-nitrides of W and MO are not synthesized in low pressure N. Attempts to synthesize WN and W(C,N) by heating W or W-C powders in N at 190 MPa are reported. W(C,N) with 20at%N was formed but WN was not.
lntermetallic
materials
PM MANUFACTURE AND CHARACTERIZATION OF PARTS MADE FROM TITANIUM ALUMINIDE BASE ALLOYS
H.Kestler et al. (Plansee AG, Reutte, Austria.) 2. Metallkd., Vol 89, No 11, 1998, 772-778. (In German.) A method of producing near net shape automotive valves from PiAl, Ti46.5at%Al-4%(Cr, Nb, Ta, B), is described. Preforms were made by HIP of
28 MPR July/August 2000
gas atomized dimension. characterized mechanical fatigue.
powders to close to part The was material for structure and properties, including
Metal injection
moulding
MEASUREMENT OF NON-UNIFORM SHRINKAGE OF INJECTION MOULDED COMPACTS
R.Watanabe, Y.Mizuno. Denki Seiko (Electric Furnace Steel), Vol 69, No 2, 1998, 117-130. (In Japanese.) A non-contact system, for in situ measurement of non-uniform shrinkage during sintering of injection moulded and debound stainless steel compacts is described. Effects of process parameters were demonstrated with sufficient accuracy to relate to dimensional tolerances. VISCOSITY AND MELT RHEOLOGY MIM FEEDSTOCKS
OF
Y.Li et al. (Central South University of Technology, Changsha, China.) Powder Metall., Vol42, No 1, 1999,86-89. Viscosity and rheological properties of Fe-2%Ni feedstocks were investigated to determine effects of minor additives in the binder. Mechanical properties and shrinkage of injection moulded test-bars were measured.
PM components PM PROCESSING IMPLANTS
OF SURGICAL
R.M.Pilliar. (University of Toronto, Toronto, Canada.) Int. J. Powder Metall., Vo134, No 8, 1998,33-45. Use of PM to make surgical prostheses is discussed with regard to the need for rigid and reliable implantto-bone fixation. Some successful clinical uses are reviewed and current studies are outlined. The need for biocompatibility of materials and design is emphasized. PREPARATION OF POROUS METALS FROM CERAMIC PRECURSORS
S.M.Landin, D.W.Readey. Ceramic Trans., Vo194, 1999,1042-1122. Uses of porous metals are outlined. A method of making porous metal parts, by reduction of porous oxide ceramic precursors, is described. Control of porosity and pore size, of the metal part, is shown to be possible by control of the ceramic. The ceramic is pressed and sintered in a reactive atmosphere. Porous Ni and Fe, made by this technique, are evaluated.
PRODUCTION OF A HARD METAL ROLLER BY HIP DIFFUSION BONDING
F.Chen et al. Rare Metal/Mater. Eng., Vol 27, No 3, 1998,177-181. (In Chinese.) Fabrication of a roller, consisting of a Fe alloy base core and a cemented carbide case, by HIP diffusion bonding, is reported. Structures and performance of the roller are described. The case/core interface and some cracking are analysed.
Refractory
alloys
HIGH TEMPERATURE HEAT RESISTANT CHROMIUM-TITANIUMCARBON ALLOYS
B.D.Bryskin et al. (Inst. for Problems of Materials Science, Kiev, Ukraine.) Int. J Refract. Metals Hard Mater., Vol 17, No 4,1999,259-263. Structure and mechanical properties of eutectic Cr-Ti-C alloys, for application at 200 to 1200°C are reviewed and reported to be of practical value. The high possibility of improving temperature strength by alloying with Fe, SC, La, MO or Re is discussed.
Miscellaneous POWDER METALLURGY ANDREAS LIBAVIUS
AND
V.Dufek. (Consultant, Prague, Czech Republic.) Pokroky Praskove Metal., Vol 36, No 4,1998,46-50. (In Czech.) The paper reports that information concerning early production and use of metal powders is to be found in Alchemia, by A.Libavius, published in 1597. TECHNICAL COST MODELLING NEAR NET SHAPE PM MANUFACTURING
OF
R.V.Bhatkal, T.Hannibal. JOM (J. of Metals), Vol 51, No 7, 1999,26-27. The competitiveness of PM processes is analysed by technical cost modelling which compares process costs for a given product. Knowledge of the regions of competitive advantage is shown to provide a focus for application and funding and allows investment in the lowest cost process route for specific applications. PM’98. The Abstracts that follow are from papers presented at the 1998 Powder Metallurgy World Congress which was held in Granada, Spain, in
PM steels CYCLIC PROPERTIES OF DIFFERENTLY HEAT TREATED STEELS
PM
(University of K.H.Lang et al. Karlsruhe, Karlsruhe, Germany.) Mechanical properties of sintered, tempered and quenched and isothermally transformed 4%Ni-05%Mo0.5%C steels, at 7.21 g.cme3 density, and a similar 0.7%C sinter hardened steel, at 7.12 g.cm-“, were investigated. The structures are described. Tempered martensite, retained austenite, bainite, zones of Ni segregation and surface decarburization were found in the samples. Optimization of quenching and tempering gave the best combination of properties over other specimens. EFFECTS OF CARBON ON MECHANICAL PROPERTIES OF ULTRA-HIGH BORON STEELS
J.A.Jimemez et al. (CENIM, CSIC, Madrid, Spain.) Deformation characteristics at elevated and ambient temperatures, of a high B steel, 2.2%B, and a high C-B-Cr were steel, 1.3%X!-0.8%B-1.67&r, investigated. Samples were prepared by HIP for 2 hours at 180 MPa and 700°C. Structures were on a pm scale. Properties were affected by cooling rate only for the C-B-Cr steel. Superplasticity was detected in both steels. Creep data was consistent with grain boundary sliding and slip-creep models. HIGH PERFORMANCE PM FERROUS MATERIALS MADE USING MULTICOMPONENT
FINE POWDER
M.Yoshida, Y.Seki. (Kobe Steel Ltd, Huogo, Japan. 1 Martensite in steels and hardenability were discussed with reference to mechanical properties. It was reported that a high strength l.O%Mo-0.5%Ni steel had been made, using a fine multicomponent powder, with strength up to 1000 MPa. PM PREALLOYED STEELS AND PROCESS TECHNOLOGY
R.Link. (QMP Metal Powders GmbH, Miinchengladbach, Germany.) New applications for PM parts, requiring high performance, were shown to need high static and dynamic strength given by use of prealloyed steel powders in combination with appropriate heat treatment. Sinter hardening of steels containing MO, or MO and Ni, was reported to allow direct production of steel with martensitic or bainitic structures. Production of case hardening 3.5%Mo steel was illustrated. The steel was sintered at a high temperature in the c1 phase zone, without a liquid phase. Properties were described. DEVELOPMENT
OF A HIGH
STRENGTH PM STEEL WITHOUT QUENCHING
T.Tsutsui et al. (Hitachi Powdered Metals Co Ltd, Chiba, Japan.) It is reported that a steel with a martensitic structure had been produced at a cooling rate typical of a conventional sintering furnace. The steel had increased hardenability due to addition of alloying elements. The was designed for high powder compressibility and the composition determined by consideration of the ideal critical diameter to give a structure 95% martensite and 5% bainite when cooled at 0.15”C.s~‘. The application was a spiral bevel gear for a power tool.
Thermal spraying spray forming
and
ELECTROMAGNETIC CONTROL OF LIQUID METAL JETS FOR SPRAY FORMING AND ATOMIZATION
D.J.Short et al. (University of Cambridge, Cambridge, UK.1 The need to control the flow of metal to the atomizer, and thus determine droplet size and microstructure of powder or sprayed deposit was noted. Experimental work to this end was described. The technique was to use electromagnetic flow control involving and partial magnetic levitation magnetic field concentration to give a metallurgically clean method of modulating, stabilizing and positioning the molten metal stream. The technique was said to have implications in processing materials such as Ti and Ti alloys. EFFECTS OF GAS ATOMIZATION PARAMETERS ON SPRAY FORMING OF NICKEL BASE SUPERALLOYS (Beijing Inst. of G.Zhang et al. Aeronautical Materials, Beijing, China.1 Spray forming, as an alternative to conventional PM processes, was discussed with regard to use of N and Ar and concerns about N content and porosity. Studies, to attain dense spray formed products with low N contents and porosity, by optimization of spraying parameters, were described. Effects of a wide range of variables were investigated. It was shown that process variables influence type, size and distribution of porosity. Microstructures were also correlated with process conditions. STRUCTURAL CHARACTERIZATION OF SPRAY FORMED CEMENTED TUNGSTEN CARBIDE J.M.Guilemany et aL. (Centre de Projeccio Termica, Barcelona, Spain.) Ni-Cr-B-Si WC-12%Co/4Ovol% materials, made from two thermal spray
powders, were reported to have good properties for abrasion and wear. The WC-Co and Ni-Cr-B-Si powders were mixed and high velocity oxy-fuel sprayed on to a Cr-Mo steel substrate. The powders and the deposit were characterized for microstructure with the object of determining interactions between the two materials both in the flame and the deposit.
Nanocrystalline materials COMBUSTION FLAME SYNTHESIZED NANOPARTICLES
B.H.Kar et al. (Rutgers University, Piscataway, USA. 1 Applications of nanostructured particles, with particle sizes of 3 to 50 nm, were discussed with respect to properties of powders and fabricated materials. Novel chemical and physical methods of making metal, oxide and cermet nanoparticles are reviewed with emphasis on chemical vapour condensation. Powder characteristics in situ are described. A one-step deposition of process for without coatings, nanostructured using a powder intermediate, was outlined. METAL NANOPOWDERS FOR POLYMER MATRIX COMPOSITES G.Bernd, H.Schafer. (Fraunhofer Inst., Bremen, Germany.) It is reported that Ag powders, 0.1 to 0.15 pm in size, had been produced by inert gas atomization, with low levels of gaseous impurity which resulted in formation of a spongy deposit with porosity of 60 to 80%. This can be infiltrated even by viscous organic liquids. This was shown to give a method of making electrically conducting adhesives with a metal filling factor as of various low as 5~01%. Effects parameters are described. Mechanical properties were outlined. CONSOLIDATION OF REACTIVELY BALL MILLED ALUMINIUM-TITANIUM POWDERS K.S.Lee, K.Moon. (Hanyang University, Seoul, Korea.) Al-T1 powders were mechanically alloyed in H to a grain size less that 20 nm. Samples were consolidated by various methods and characterized to find the best method that would preserve the nanocrystalline structure. Hot extrusion, plasma activated sintering and high pressure sintering, at 4.5 GPa, were investigated. The object was to reduce process time to limit grain growth.
MPR July/August
2000 31