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Thermally assisted and mechanically driven amorphization reactions in tantalum alloys
SINTERED IRON-BRONZE CONNECTING ROD BUSHING ALLOYS
are described. Fracture strength and embrittlement phenomena of the joints were investigated. It is reported that fracture strengths were 34 to 94 MPa, that W.Zhihai. (Central South University of cracks were initiated in the MO rich layer Technology, Hunan, China.) PM Technology, and propagated into the brazing alloy and Vol 14, No 2, 1996, 116-121. (In Chinese.) the C ceramic. The higher was the fracture Properties of sintered Fe-bronze alloys strength the smaller was the ratio of MO to was investigated for wear resistance. The Pd rich phases in the fracture zone. properties are shown to be superior to those of other materials. Surface machining SEPARATION OF TUNGSTEN FROM and fitting of diesel engine connecting rod MOLYBDENUM BY AN ADSORPTION bushes and gudgeon pins are discussed. USING ACTIVATED CARBON PROPERTIES AND STRUCTURE OF COPPER INFILTRATED SINTERED STEEL
G.Bofan et al. (Central South University of Technology, Hunan, China.) Int. J.Refiactory Metals and Hard Mate&Is, Vol 14, No 5/6, 1996, 319-323. D.Yi et al. (University of Science and A new process for separation of W and Technology, Beijing, China.) PM Technol- MO is described. Na tungstate solution, ogv, Vol 14, No 2, 1996, 122-126. (In containing MO, is treated with an alkali Chinese.) sulphide to convert MO into a thiomolybdate which is selectively The effects of Fe powder characteristics, Cu content and heat treatment on adsorped on activated C. W stays properties and structures of Cu iniiltrated dissolved. The process is cost effective. steels were investigated. A sintered steel with some Cu before infiltration and EFFECT OF VACUUN HEATING ON LOW medium to high C had a transverse TEMPERATURE FRACTURE OF rupture strength of 1600 MPa, Rockwell MOLYBDENUM-TITANIUM ALLOYS hardness of 45°C and a density of 7.6 gm.cm-3 after infiltration and heat S.Yoshimura, Y.Hiroaka. (Okayama Univertreatment to a tempered martensite sity of Science, Okayama, Japan.) Int. structure with Cu. Fracture was in the J.Reti-actow Metals and Hard Materials, Vol 14, No 5/6, 1996, 325-333. Cu phase. Investigations of MO-(0.1 to l.O)wt”%Ti-C alloys, to determine C state and interaction IRON BASED ANTI-FRICTION with Ti, are described. Bend tests at MATERIALS liquid N to ambient temperatures were carried out before and after vaccum W.Qingding. (Hunan Powder Metallurgy heat treatment. It is reported that for Ltd. Co., Changsha, China.) PM Tmhnoloa lower Ti (0.1%) the critical temperature Vol 14, No 2, 1996, 127-131. (In Chinese.) The effects of composition and sintering and fracture mode were unchanged by heating. It was deduced that C and conditions on properties of Fe-Cu-Mn antifrlction materials were investigated carbides were segregated at grain boundaries. For l”%Ti alloys the critical and optimum values established. The materials are reported to have good stress decreased and the critical temperature increased after heat properties at low cost. treatment. The fracture mode changed FACTORS INFLUENCING from trans- to inter-granular. It is shown ELECTROMAGNETIC PROPERTIES OF that C was present in the free state in grain boundaries and at interfaces between Ti CARBONYL IRON POWDER oxides and the matrix. W.Binggen. (State Owned Plant No 857, Sichuan, China.) PM Tehnologv, Vol 14, No Tantalum 2, 1996, 145-149. In Chinese. Factors affecting electromagnetic THERMALLY ASSISTED AND properties of carbonyl Fe powder and MECHANICALLY DRIVEN which influence production are described. AMORPHIZATION REACTIONS IN
Molybdenum BRAZING OF MOLYBDENUM AND CARBON CERAMICS WITH PALLADIUM BASE MATERIALS Y.Hiroaka, S,Nishikawa. (Kogi Co. Ltd., Himeki, Japan.) Int. JXefi-acto~ Metals and Hard Materials,Vol 14, No 5/6, 1996, 311-317. Studies of joints between MO and C ceramics, brazed with Pd or Pd-Ag alloys,
38
MPR March 1997
is unstable and the powder is amorphous after 200 hours. This is attributed to lattice defects. The amorphous phase is homogeneous after 400 hours. The heat of formation of the amorphous phase was calculated. Crystallization charactistics were determined with regard to milling time and recrystallization temperature.
Titanium THE ROLE OF DISLOCATION PIPE DIFFUSION IN SINTERING OF IE TITANIUM K.I.Vasu et al. (Indian Inst. of Science, Bangalore, India.) Powder Metallurgy, Vol 39, No 2, 1996, 133142. Sintering of p Ti was investigated by dilatometry. Shrinkage did not follow normal time exponent behaviour. An equation linking shrinkage with time and activation energy of 62 to 90 kJ.mol-’ were calculated. Anomalous diffusion is given as the reason and this is analyzed with regard to dislocation density. It is shown that a high dislocation density is generated at the u/p transition and this, coupled with slow recovery at sintering necks, allows dislocation pipe diffusion. HIP SINTERING OF AMORPHOUS TITANIUM-NICKEL ALLOY POWDERS S.Ito et al. (Science University of tokyo, Tokyo, Japan.) JJapan Sot. Powder and PowderMetallurgy,Vol42, No 4, 1995,496500. (In Japanese.) It is reported that amorphous TiSOat%Ni powders had been HIP-sintered above 700°C to obtain equilibrium phases. At QOOC TiNi, Ti2Ni and TiNi were detected by X-ray. At 700C the amorphous structure was mostly retained with a density of 94%. Vicker’s hardness was 900 and 800 at 700°C and 900°C respectivly. Alloys sintered at the lower temperature had higher corrosion resistance.
Ceramic materials CUTTING PERFORMANCE OF HIGH PURITY ALUMINA CERAMIC TOOLS
S.Tashima et al. (Hiroshima University, Horoshima, Japan.) J-Japan Sot. Powder and Powder Metallurgy,Vol42, No 4, 1995, M.S.El-Eskandarany. (Tohoku University, 464-468. (In Japanese.) Sendai, Japan.) Metal and Mater. ZYans It is reported that a high speed A, Vol27A, No 10, 1996, 3267-3273. centrifugal process has been developed for It is reported that MA had been used to fabrication of high purity Al203 from a process elemental Ta-33at%Al powders and slurry. Green compacts were sintered at monitored by a range of techniques. 1230°C for 1.5 hours. Cutting performance Initially, layered structures were formed in was evaluated and it is shown that the the intermixed Ta-Al powders which material has high wear resistance and amorphized on heating at 400°C. After toughness when compared with other 100 hours the layered structure degrades Alz03 materials. by diffusion yielding a solid solution which TANTALUM ALLOYS
are described. Fracture strength and embrittlement phenomena of the joints were investigated. It is reported that fracture strengths were 34 to 94 MPa, that W.Zhihai. (Central South University of cracks were initiated in the MO rich layer Technology, Hunan, China.) PM Technology, and propagated into the brazing alloy and Vol 14, No 2, 1996, 116-121. (In Chinese.) the C ceramic. The higher was the fracture Properties of sintered Fe-bronze alloys strength the smaller was the ratio of MO to was investigated for wear resistance. The Pd rich phases in the fracture zone. properties are shown to be superior to those of other materials. Surface machining SEPARATION OF TUNGSTEN FROM and fitting of diesel engine connecting rod MOLYBDENUM BY AN ADSORPTION bushes and gudgeon pins are discussed. USING ACTIVATED CARBON PROPERTIES AND STRUCTURE OF COPPER INFILTRATED SINTERED STEEL
G.Bofan et al. (Central South University of Technology, Hunan, China.) Int. J.Refiactory Metals and Hard Mate&Is, Vol 14, No 5/6, 1996, 319-323. D.Yi et al. (University of Science and A new process for separation of W and Technology, Beijing, China.) PM Technol- MO is described. Na tungstate solution, ogv, Vol 14, No 2, 1996, 122-126. (In containing MO, is treated with an alkali Chinese.) sulphide to convert MO into a thiomolybdate which is selectively The effects of Fe powder characteristics, Cu content and heat treatment on adsorped on activated C. W stays properties and structures of Cu iniiltrated dissolved. The process is cost effective. steels were investigated. A sintered steel with some Cu before infiltration and EFFECT OF VACUUN HEATING ON LOW medium to high C had a transverse TEMPERATURE FRACTURE OF rupture strength of 1600 MPa, Rockwell MOLYBDENUM-TITANIUM ALLOYS hardness of 45°C and a density of 7.6 gm.cm-3 after infiltration and heat S.Yoshimura, Y.Hiroaka. (Okayama Univertreatment to a tempered martensite sity of Science, Okayama, Japan.) Int. structure with Cu. Fracture was in the J.Reti-actow Metals and Hard Materials, Vol 14, No 5/6, 1996, 325-333. Cu phase. Investigations of MO-(0.1 to l.O)wt”%Ti-C alloys, to determine C state and interaction IRON BASED ANTI-FRICTION with Ti, are described. Bend tests at MATERIALS liquid N to ambient temperatures were carried out before and after vaccum W.Qingding. (Hunan Powder Metallurgy heat treatment. It is reported that for Ltd. Co., Changsha, China.) PM Tmhnoloa lower Ti (0.1%) the critical temperature Vol 14, No 2, 1996, 127-131. (In Chinese.) The effects of composition and sintering and fracture mode were unchanged by heating. It was deduced that C and conditions on properties of Fe-Cu-Mn antifrlction materials were investigated carbides were segregated at grain boundaries. For l”%Ti alloys the critical and optimum values established. The materials are reported to have good stress decreased and the critical temperature increased after heat properties at low cost. treatment. The fracture mode changed FACTORS INFLUENCING from trans- to inter-granular. It is shown ELECTROMAGNETIC PROPERTIES OF that C was present in the free state in grain boundaries and at interfaces between Ti CARBONYL IRON POWDER oxides and the matrix. W.Binggen. (State Owned Plant No 857, Sichuan, China.) PM Tehnologv, Vol 14, No Tantalum 2, 1996, 145-149. In Chinese. Factors affecting electromagnetic THERMALLY ASSISTED AND properties of carbonyl Fe powder and MECHANICALLY DRIVEN which influence production are described. AMORPHIZATION REACTIONS IN
Molybdenum BRAZING OF MOLYBDENUM AND CARBON CERAMICS WITH PALLADIUM BASE MATERIALS Y.Hiroaka, S,Nishikawa. (Kogi Co. Ltd., Himeki, Japan.) Int. JXefi-acto~ Metals and Hard Materials,Vol 14, No 5/6, 1996, 311-317. Studies of joints between MO and C ceramics, brazed with Pd or Pd-Ag alloys,
38
MPR March 1997
is unstable and the powder is amorphous after 200 hours. This is attributed to lattice defects. The amorphous phase is homogeneous after 400 hours. The heat of formation of the amorphous phase was calculated. Crystallization charactistics were determined with regard to milling time and recrystallization temperature.
Titanium THE ROLE OF DISLOCATION PIPE DIFFUSION IN SINTERING OF IE TITANIUM K.I.Vasu et al. (Indian Inst. of Science, Bangalore, India.) Powder Metallurgy, Vol 39, No 2, 1996, 133142. Sintering of p Ti was investigated by dilatometry. Shrinkage did not follow normal time exponent behaviour. An equation linking shrinkage with time and activation energy of 62 to 90 kJ.mol-’ were calculated. Anomalous diffusion is given as the reason and this is analyzed with regard to dislocation density. It is shown that a high dislocation density is generated at the u/p transition and this, coupled with slow recovery at sintering necks, allows dislocation pipe diffusion. HIP SINTERING OF AMORPHOUS TITANIUM-NICKEL ALLOY POWDERS S.Ito et al. (Science University of tokyo, Tokyo, Japan.) JJapan Sot. Powder and PowderMetallurgy,Vol42, No 4, 1995,496500. (In Japanese.) It is reported that amorphous TiSOat%Ni powders had been HIP-sintered above 700°C to obtain equilibrium phases. At QOOC TiNi, Ti2Ni and TiNi were detected by X-ray. At 700C the amorphous structure was mostly retained with a density of 94%. Vicker’s hardness was 900 and 800 at 700°C and 900°C respectivly. Alloys sintered at the lower temperature had higher corrosion resistance.
Ceramic materials CUTTING PERFORMANCE OF HIGH PURITY ALUMINA CERAMIC TOOLS
S.Tashima et al. (Hiroshima University, Horoshima, Japan.) J-Japan Sot. Powder and Powder Metallurgy,Vol42, No 4, 1995, M.S.El-Eskandarany. (Tohoku University, 464-468. (In Japanese.) Sendai, Japan.) Metal and Mater. ZYans It is reported that a high speed A, Vol27A, No 10, 1996, 3267-3273. centrifugal process has been developed for It is reported that MA had been used to fabrication of high purity Al203 from a process elemental Ta-33at%Al powders and slurry. Green compacts were sintered at monitored by a range of techniques. 1230°C for 1.5 hours. Cutting performance Initially, layered structures were formed in was evaluated and it is shown that the the intermixed Ta-Al powders which material has high wear resistance and amorphized on heating at 400°C. After toughness when compared with other 100 hours the layered structure degrades Alz03 materials. by diffusion yielding a solid solution which TANTALUM ALLOYS