- Email: [email protected]
Electromigration and electroplastic effect in aluminium matrix silicon carbide composites
carbides during sintering. Tests in boiling 16%H2S04-6%CuS04 were too aggressive for PM alloys and the H2S04 was reduced to 0.5% which gave a useful test solution. Heat treatment at 8160C before sintering at 12900C reduced intergranular corrosion.
Nickel Specimen temperature and sinterability of nickel powder in spark plasma sintering M.Tokita et al. (Irtrmi Technology Co. Ltd., Kawasaki, Japan.) J.Japan Sot. Powder/Powder Met&, Vol47, No 8, 2000, 887-891. In English.
Sample temperature and sintering behaviour of Ni powder, processed by spark plasma sintering, were investigated. Microstructural examination showed that rapid densification was attributable to promotion of neck growth and plastic deformation of Ni particles. With a, graphite, die temperature of 8OOoC the centre of the specimen was at 93OoC. The difference between die and sample temperatures increased exponentially with die temperature. The gap was reduced by thermal insulation of the die and there was then a linear increase in the temperature difference.
Tungsten
A.Dutta et al. (De-fence Metallurgical Laboratory, Hyderabad, India.) PM Science and Technology Briefs, Vol.2, No 2, 2000, 14-18.
Processing of ceramics and composites by rapid prototyping
Adiabatic shear, which gives a self sharpening effect in kinetic energy penetrators, is discussed with regard to the phenomenon in depleted U and W-Ni-Fe heavy alloys, the environmental disadvantage of U and the lesser adiabatic shear in W-Ni-Fe. Parameters to characterize the localization of shear, the ratio of strain softening to strain rate sensitivity, was investigated.
S.Bose et al. (Washington Srate University, Pullman, USA.) PM Science and Technology Briefs, Vol2, No 2, 2000, 19~21.
Ceramic materials Sintering behaviour and mechanical properties of centrifugally compacted alumina H.Y.Suwki
et al. (Hiroshima University, HigashiJapan.) J.Japan Sot. Powder/Pow&r Metall., Vol47, No 8, 2000, 866-873. In Japanese. Hiroshima,
Samples of 2 types of A1203 powder, grain size 0.2mm, specific surface 10.4 and 15.lm2.gm-1 and differing in impurity content were centrifugally compacted in a slurry at 11500rpm and sintered at 11500C to 15500C for 1.5 hours. The samples were shown to be well compacted. Mechanical properties and structures are discussed with regard to characteristics of powder and sintered compacts.
Characteristics of mechanically alloyed tungsten-nickel-iron powder during annealing
Comparison of pressure-cast and centrifugally compacted alumina compacts
J.Fan et al. (Central South Unwersity of Technology, Changsha, China.) lnt. J. Refract.MetalslHard Mater., Vof 19, No 2, 2001, 73-77.
H.Y.Suzuki et al. (Hiroshima University, HigashiHiroshima, Japan.) J.Japan Sot. Powder/Powder Met&, Vol47, No 8, 2000, In Japanese.
Elemental W-N&Fe powders were mechanically alloyed for 20 hours to a nanocrystalline state. Structural changes during annealing were investigated. Stress relaxation, recovery and grain growth, precipitation of Ni-Fe from a supersaturated W solid solution crystallization of amorphous phases and microstructural changes were detected. Large grains grew above 1 IOOC. Milling increase solubility of W in the g phase.
Characterisation of tungsten oxides
Residual defects in centrifugally compacted or pressure-cast from slurry, and sintered A1203 compacts were investigated. Samples 500mm thick were sliced from material heat treated at 8OOoC for 1 hour. The slices were soaked in CH212 and examined by optical microscopy. The densities of the two materials were similar but the pressure-cast material had large pores that were larger as the viscosity of the slurry increased. Pore size in centrifugally compacted material was reduced as the centrifugal force increased.
L.Jiqiao et al. (Central South University of Technology, Changsha, China.) lnt. J. Refwct.Metals/Hard Mater., Vol 19, No 2, 2001, 79-84.
Production of amorphous-crystalline silica composite by hip
Four W oxides, ammonium W bronze, hydrogen W bronze, violet and blue W oxides, were investigated for porosity characteristics, fractal dimensions and surface area. The results are considered to show the importance of oxide powder characteristics in reduction and doping processes.
Adiabatic shear in tungsten heavy alloys at high strain rates
40
MPR February
2002
S.lto et al. (Science University of Tokyo, Noda, Japan.)J.Japan Sot. Powder/Powder Me&l., Vol47, No 8, 2000, 882-886. In Japanese.
It is reported sisting
that a composite
of fine aquartz
crystals
material
con-
and amorphous
Si02 had been made by HIP to imitate natural agate. Fracture toughness, Klc, was 0.56MNm-3/2. This was increased, in the synthetic material, to 0.63MNm-3/2 by use of PbCl2 as a nucleation enhancer.
It is noted that there may a long and costly lead time between design and production of parts using ceramic and composite materials. This can be reduced by using rapid prototyping techniques, which do not require expensive tooling. Fused deposition is reported to be available for ceramic and metal matrix-ceramic composites with controlled porosity. Processing is summarised.
Composite materials Particle dispersed ceramic composite CXu, X.Ai. ( Shundong University, jimn, China.) Int. Refract.Metals/HardMater., Vol 19, No 2, 2001,85-88. It is reported
that a reinforced
ceramic
J.
com-
had been developed. Structure, mechanical properties and cutting performance are evaluated. Mechanical properties were shown to be high, notably flexural strength and fracture toughness with good performance in continuous and interrupted cutting of carbon steels. posite,
based
on Al203,(W,X)C,
Electromigration and electroplastic effect in aluminium matrix silicon carbide composites N.G.Dnrinvach, J.A.Rice. (Marquette University, Mdwntrkee, USA.) J .Metals (JOM),Vol 52, No 5, 2000, 40-42.
PM Al-Sic composites were subjected to pulses on high density AC during transverse rupture testing. Increased strength due to electromigration is reported. Decrease in flow stress during plastic deformation was detected and is attributed to electroplasticity.
Synthesis and evaluation of titanium-aluminium-carbon composite materials T.Yama.snki et al. (Kyoto University, Kyoto, Japan.) J.Japan Sot. Powder/Powder Met&, Vol 47, No 8. 2000, 921,926. InJapanese. It is reported that a composite material had been made from elemental Ti-Al-C powders by reaction synthesis, at 66OoC, and pseudo-H IP. Processed Ti-45at%Al-lO%C consisted of a TiAl matrix and fine Ti3AIC particles. Mechanical properties were higher than X46at%Al.
Preparation and properties of sintered nickel-zinc ferrite-silicon carbide composite T.Fujii et al. (Okoyama Unwersity, Okayama, Japan.) J.Japan Sot. Powder/Powder Metall., Vol 47, No 8, 2000, 927-930. In Japanese.
www.metal-powder.net
Nickel Specimen temperature and sinterability of nickel powder in spark plasma sintering M.Tokita et al. (Irtrmi Technology Co. Ltd., Kawasaki, Japan.) J.Japan Sot. Powder/Powder Met&, Vol47, No 8, 2000, 887-891. In English.
Sample temperature and sintering behaviour of Ni powder, processed by spark plasma sintering, were investigated. Microstructural examination showed that rapid densification was attributable to promotion of neck growth and plastic deformation of Ni particles. With a, graphite, die temperature of 8OOoC the centre of the specimen was at 93OoC. The difference between die and sample temperatures increased exponentially with die temperature. The gap was reduced by thermal insulation of the die and there was then a linear increase in the temperature difference.
Tungsten
A.Dutta et al. (De-fence Metallurgical Laboratory, Hyderabad, India.) PM Science and Technology Briefs, Vol.2, No 2, 2000, 14-18.
Processing of ceramics and composites by rapid prototyping
Adiabatic shear, which gives a self sharpening effect in kinetic energy penetrators, is discussed with regard to the phenomenon in depleted U and W-Ni-Fe heavy alloys, the environmental disadvantage of U and the lesser adiabatic shear in W-Ni-Fe. Parameters to characterize the localization of shear, the ratio of strain softening to strain rate sensitivity, was investigated.
S.Bose et al. (Washington Srate University, Pullman, USA.) PM Science and Technology Briefs, Vol2, No 2, 2000, 19~21.
Ceramic materials Sintering behaviour and mechanical properties of centrifugally compacted alumina H.Y.Suwki
et al. (Hiroshima University, HigashiJapan.) J.Japan Sot. Powder/Pow&r Metall., Vol47, No 8, 2000, 866-873. In Japanese. Hiroshima,
Samples of 2 types of A1203 powder, grain size 0.2mm, specific surface 10.4 and 15.lm2.gm-1 and differing in impurity content were centrifugally compacted in a slurry at 11500rpm and sintered at 11500C to 15500C for 1.5 hours. The samples were shown to be well compacted. Mechanical properties and structures are discussed with regard to characteristics of powder and sintered compacts.
Characteristics of mechanically alloyed tungsten-nickel-iron powder during annealing
Comparison of pressure-cast and centrifugally compacted alumina compacts
J.Fan et al. (Central South Unwersity of Technology, Changsha, China.) lnt. J. Refract.MetalslHard Mater., Vof 19, No 2, 2001, 73-77.
H.Y.Suzuki et al. (Hiroshima University, HigashiHiroshima, Japan.) J.Japan Sot. Powder/Powder Met&, Vol47, No 8, 2000, In Japanese.
Elemental W-N&Fe powders were mechanically alloyed for 20 hours to a nanocrystalline state. Structural changes during annealing were investigated. Stress relaxation, recovery and grain growth, precipitation of Ni-Fe from a supersaturated W solid solution crystallization of amorphous phases and microstructural changes were detected. Large grains grew above 1 IOOC. Milling increase solubility of W in the g phase.
Characterisation of tungsten oxides
Residual defects in centrifugally compacted or pressure-cast from slurry, and sintered A1203 compacts were investigated. Samples 500mm thick were sliced from material heat treated at 8OOoC for 1 hour. The slices were soaked in CH212 and examined by optical microscopy. The densities of the two materials were similar but the pressure-cast material had large pores that were larger as the viscosity of the slurry increased. Pore size in centrifugally compacted material was reduced as the centrifugal force increased.
L.Jiqiao et al. (Central South University of Technology, Changsha, China.) lnt. J. Refwct.Metals/Hard Mater., Vol 19, No 2, 2001, 79-84.
Production of amorphous-crystalline silica composite by hip
Four W oxides, ammonium W bronze, hydrogen W bronze, violet and blue W oxides, were investigated for porosity characteristics, fractal dimensions and surface area. The results are considered to show the importance of oxide powder characteristics in reduction and doping processes.
Adiabatic shear in tungsten heavy alloys at high strain rates
40
MPR February
2002
S.lto et al. (Science University of Tokyo, Noda, Japan.)J.Japan Sot. Powder/Powder Me&l., Vol47, No 8, 2000, 882-886. In Japanese.
It is reported sisting
that a composite
of fine aquartz
crystals
material
con-
and amorphous
Si02 had been made by HIP to imitate natural agate. Fracture toughness, Klc, was 0.56MNm-3/2. This was increased, in the synthetic material, to 0.63MNm-3/2 by use of PbCl2 as a nucleation enhancer.
It is noted that there may a long and costly lead time between design and production of parts using ceramic and composite materials. This can be reduced by using rapid prototyping techniques, which do not require expensive tooling. Fused deposition is reported to be available for ceramic and metal matrix-ceramic composites with controlled porosity. Processing is summarised.
Composite materials Particle dispersed ceramic composite CXu, X.Ai. ( Shundong University, jimn, China.) Int. Refract.Metals/HardMater., Vol 19, No 2, 2001,85-88. It is reported
that a reinforced
ceramic
J.
com-
had been developed. Structure, mechanical properties and cutting performance are evaluated. Mechanical properties were shown to be high, notably flexural strength and fracture toughness with good performance in continuous and interrupted cutting of carbon steels. posite,
based
on Al203,(W,X)C,
Electromigration and electroplastic effect in aluminium matrix silicon carbide composites N.G.Dnrinvach, J.A.Rice. (Marquette University, Mdwntrkee, USA.) J .Metals (JOM),Vol 52, No 5, 2000, 40-42.
PM Al-Sic composites were subjected to pulses on high density AC during transverse rupture testing. Increased strength due to electromigration is reported. Decrease in flow stress during plastic deformation was detected and is attributed to electroplasticity.
Synthesis and evaluation of titanium-aluminium-carbon composite materials T.Yama.snki et al. (Kyoto University, Kyoto, Japan.) J.Japan Sot. Powder/Powder Met&, Vol 47, No 8. 2000, 921,926. InJapanese. It is reported that a composite material had been made from elemental Ti-Al-C powders by reaction synthesis, at 66OoC, and pseudo-H IP. Processed Ti-45at%Al-lO%C consisted of a TiAl matrix and fine Ti3AIC particles. Mechanical properties were higher than X46at%Al.
Preparation and properties of sintered nickel-zinc ferrite-silicon carbide composite T.Fujii et al. (Okoyama Unwersity, Okayama, Japan.) J.Japan Sot. Powder/Powder Metall., Vol 47, No 8, 2000, 927-930. In Japanese.
www.metal-powder.net