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Novel PM techniques for refractory metals and hard materials
and metallography characterize the powders.
were used to raw and milled
FORMATION OF TITANIUM AND SILICON CARBIDES BY MECHANICAL ALLOYING
M.S.el-Eskandarany et al. (Al-Azhar University, Cairo, Egypt.) J. Jpn. Sot. Powder Powder Metall., Vol 43, No 5, 1996, 579-583. (In English.) It is reported that MA has been used to synthesize TiC and Sic from elemental powders. Phase formation was monitored. Single phase Ti-56at%C formed after 5.5 hours with a particle size of 500 nm and a grain size of 20 nm. Stoichiometric Sic formed after 300 hours. MECHANICAL ALLOYING OF ALUMINIUMWITH BISMUTH OR LEAD
T.Aizawa et al. (Tokyo University, Tokyo, Japan.) J. Jpn. Sot. Powder Powder Metall., Vo143, No 5, 1996,602 607. (In Japanese.) It is noted that alloys, with large differences in specific gravities and melting points of the components, are diffcult to fabricate. It is reported that high speed MA has been used to process B&Al and Pb-Al powders. It is shown that homogenization and refinement took place within the number of MA cycles used. MECHANICAL ALLOYING OF COPPER-NICKEGIRON POWDERS
Y.Tanaka et al. (Sanyo Special Steels, Japan.) Mater. Trans. JIM, Vol37, No 5, 1996, 1073-1077. Energy effects during MA of Cu-NiFe powders were investigated in a variable speed planetary ball mill, It is shown that the powders can be alloyed to a single face centred cubic phase by high energy milling. Low energy milled powders can be homogenized by heat treatment. Spinodal decomposition of the powders occurred at 500°C. Mechanisms and properties are presented.
pressed composites had been infiltration sintered to high densities of 99.2% and Vicker’s hardness of 210, 405 and 366, respectively. Solids loading of the MIM feedstocks was 52~01%. At a density near 99% a transverse rupture strength near 1500 MPa and a fine microstructure were attained for injection moulded and infiltration sintered W-15%Cu.
14TH INTERNATIONAL PIANSEE SEMINAR. The Abstracts which follow are from papers which were presented at the Seminar, which was held in Reutte, Austria, in May 1997.
PROCESSING OF HIGH STRENGTH HIGH CONDUCTIVITY TUNGSTENCOPPER COMPOSITE
B.Bryskin, E.K.Ohriner. (Oak Ridge National Laboratory, USA.) It was reported that a W-40wt%Cu alloy had been fabricated by liquid phase sintering and further deformation. Full density was attained by hot extrusion or cold rolling. Some deformation methods did not change grain aspect ratio. High hardness was attained at grain sizes below 5 pm. A work hardened structure could be developed which was thermally stable. Tensile strengths up to 1120 MPa were reported. IMPROVEMENT OF HIGH TEMPERATURE DIMENSIONAL STABILITY OF TUNGSTEN-COPPER COMPOSITES
Y.Kuang et al. (Central Iron and Steel Research Inst., Beijing, China.) It was reported that a W-Cu alloy part had contracted during testing. Composition, fabrication, structure and properties were analysed. The shrinkage was attributed to a second stage of sintering and poor high temperature strength. A method to improve high temperature dimensional stability was suggested and was reported to be successful. PROCESSING AND PROPERTIES OF ULTRAFINE TUNGSTEN CARBIDECOBALT HARDMETALS
INJECTION MOULDING AND INFILTRATION SINTERING OF SUPERFINE GRAIN TUNGSTENCOPPER
B.Yang, R.M.German. (Pennsylvania State University, Pennsylvania, USA.) Int. J. Powder Metal, Vol 33, No 4, 1997, 55-63. It is reported that W-(10, 15 and PO)wt%Cu, injection moulded or die 40
MPR February1998
D.F.Carroll. (Dow Chemical Co, Midland, Michigan, USA.) An investigation of processing, structure and properties of ultrafine WC-Co was described. Conditions to give minimum grain size were established. It was shown that, by control of milling time, %C, grain growth inhibitors and sintering temperature, a superior product can be made.
CEMENTED CARBIDE FROM MICRON SIZE TO NAN0 SIZE
R.Porat et al. (Israel Inst. of Technology, Haifa, Israel.) Properties and sintering of WC-Co were investigated. It was reported that as grain size changes from micron to submicron size there is an increase in densification, hardness and fracture properties. It was noted that the reduction in grain size is accompanied by increased grain growth. SYNTHESIS OF TUNGSTEN AND MOLYBDENUM DISILICIDES BY MECHANICAL ALLOYING
E.I.Ivanov, E.J.Schapker. (Tosoh SMD Inc, Grove City, Ohio, USA.) Mechanical alloying of W-Si and MoSi powders was investigated. A W container and balls were used for the W-Si and hardened steel for Mo-Si. W-Si first formed a nanoscale mixture with a grain size of 10 nm. WSi, or MoSi, were formed on heating or prolonged milling. Differential scanning calorimetry was used to investigate the stability of the compounds. The powders were consolidated by HIP. The materials were used as targets. Sputtering from the targets was reduced by diminished grain size. NOVEL PM TECHNIQUES FOR REFRACTORY METALS AND HARD MATERIALS
R.M.German. (Pennsylvania State University, Pennsylvania, USA.) The use of injection moulding technology, for refractory metals and hard materials, was discussed. Feedstocks with large proportions of solid and small amounts of binder are moulded. The powders need to be de-agglomerated and of a size to suit the process, The mouldings are debound and sintered. The paper discussed the process with regard to powder characteristics, applications and properties of sintered parts. DIAMOND AND CUBIC BORON NITRIDE COATINGS FOR TOOLS
C.P.Klages et al. (Fraunhofer Inst., Braunschweig, Germany.) Diamond and cubic BN coatings on cutting tools were discussed with reference to problems of adhesion of coating to substrate. It was reported that this had been resolved for hardmetal and ceramic tool materials but not for coating of steel alloys for which further work was required.
were used to raw and milled
FORMATION OF TITANIUM AND SILICON CARBIDES BY MECHANICAL ALLOYING
M.S.el-Eskandarany et al. (Al-Azhar University, Cairo, Egypt.) J. Jpn. Sot. Powder Powder Metall., Vol 43, No 5, 1996, 579-583. (In English.) It is reported that MA has been used to synthesize TiC and Sic from elemental powders. Phase formation was monitored. Single phase Ti-56at%C formed after 5.5 hours with a particle size of 500 nm and a grain size of 20 nm. Stoichiometric Sic formed after 300 hours. MECHANICAL ALLOYING OF ALUMINIUMWITH BISMUTH OR LEAD
T.Aizawa et al. (Tokyo University, Tokyo, Japan.) J. Jpn. Sot. Powder Powder Metall., Vo143, No 5, 1996,602 607. (In Japanese.) It is noted that alloys, with large differences in specific gravities and melting points of the components, are diffcult to fabricate. It is reported that high speed MA has been used to process B&Al and Pb-Al powders. It is shown that homogenization and refinement took place within the number of MA cycles used. MECHANICAL ALLOYING OF COPPER-NICKEGIRON POWDERS
Y.Tanaka et al. (Sanyo Special Steels, Japan.) Mater. Trans. JIM, Vol37, No 5, 1996, 1073-1077. Energy effects during MA of Cu-NiFe powders were investigated in a variable speed planetary ball mill, It is shown that the powders can be alloyed to a single face centred cubic phase by high energy milling. Low energy milled powders can be homogenized by heat treatment. Spinodal decomposition of the powders occurred at 500°C. Mechanisms and properties are presented.
pressed composites had been infiltration sintered to high densities of 99.2% and Vicker’s hardness of 210, 405 and 366, respectively. Solids loading of the MIM feedstocks was 52~01%. At a density near 99% a transverse rupture strength near 1500 MPa and a fine microstructure were attained for injection moulded and infiltration sintered W-15%Cu.
14TH INTERNATIONAL PIANSEE SEMINAR. The Abstracts which follow are from papers which were presented at the Seminar, which was held in Reutte, Austria, in May 1997.
PROCESSING OF HIGH STRENGTH HIGH CONDUCTIVITY TUNGSTENCOPPER COMPOSITE
B.Bryskin, E.K.Ohriner. (Oak Ridge National Laboratory, USA.) It was reported that a W-40wt%Cu alloy had been fabricated by liquid phase sintering and further deformation. Full density was attained by hot extrusion or cold rolling. Some deformation methods did not change grain aspect ratio. High hardness was attained at grain sizes below 5 pm. A work hardened structure could be developed which was thermally stable. Tensile strengths up to 1120 MPa were reported. IMPROVEMENT OF HIGH TEMPERATURE DIMENSIONAL STABILITY OF TUNGSTEN-COPPER COMPOSITES
Y.Kuang et al. (Central Iron and Steel Research Inst., Beijing, China.) It was reported that a W-Cu alloy part had contracted during testing. Composition, fabrication, structure and properties were analysed. The shrinkage was attributed to a second stage of sintering and poor high temperature strength. A method to improve high temperature dimensional stability was suggested and was reported to be successful. PROCESSING AND PROPERTIES OF ULTRAFINE TUNGSTEN CARBIDECOBALT HARDMETALS
INJECTION MOULDING AND INFILTRATION SINTERING OF SUPERFINE GRAIN TUNGSTENCOPPER
B.Yang, R.M.German. (Pennsylvania State University, Pennsylvania, USA.) Int. J. Powder Metal, Vol 33, No 4, 1997, 55-63. It is reported that W-(10, 15 and PO)wt%Cu, injection moulded or die 40
MPR February1998
D.F.Carroll. (Dow Chemical Co, Midland, Michigan, USA.) An investigation of processing, structure and properties of ultrafine WC-Co was described. Conditions to give minimum grain size were established. It was shown that, by control of milling time, %C, grain growth inhibitors and sintering temperature, a superior product can be made.
CEMENTED CARBIDE FROM MICRON SIZE TO NAN0 SIZE
R.Porat et al. (Israel Inst. of Technology, Haifa, Israel.) Properties and sintering of WC-Co were investigated. It was reported that as grain size changes from micron to submicron size there is an increase in densification, hardness and fracture properties. It was noted that the reduction in grain size is accompanied by increased grain growth. SYNTHESIS OF TUNGSTEN AND MOLYBDENUM DISILICIDES BY MECHANICAL ALLOYING
E.I.Ivanov, E.J.Schapker. (Tosoh SMD Inc, Grove City, Ohio, USA.) Mechanical alloying of W-Si and MoSi powders was investigated. A W container and balls were used for the W-Si and hardened steel for Mo-Si. W-Si first formed a nanoscale mixture with a grain size of 10 nm. WSi, or MoSi, were formed on heating or prolonged milling. Differential scanning calorimetry was used to investigate the stability of the compounds. The powders were consolidated by HIP. The materials were used as targets. Sputtering from the targets was reduced by diminished grain size. NOVEL PM TECHNIQUES FOR REFRACTORY METALS AND HARD MATERIALS
R.M.German. (Pennsylvania State University, Pennsylvania, USA.) The use of injection moulding technology, for refractory metals and hard materials, was discussed. Feedstocks with large proportions of solid and small amounts of binder are moulded. The powders need to be de-agglomerated and of a size to suit the process, The mouldings are debound and sintered. The paper discussed the process with regard to powder characteristics, applications and properties of sintered parts. DIAMOND AND CUBIC BORON NITRIDE COATINGS FOR TOOLS
C.P.Klages et al. (Fraunhofer Inst., Braunschweig, Germany.) Diamond and cubic BN coatings on cutting tools were discussed with reference to problems of adhesion of coating to substrate. It was reported that this had been resolved for hardmetal and ceramic tool materials but not for coating of steel alloys for which further work was required.