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Powder production
Powder production TITANIUM POWDER PRODUCTION BY INJECTION OF TITANIUM CHLORIDE INTO MOLTEN MAGNESIUM T.N.Deura et al. (Kobe Steel Ltd, Kobe, Japan.) Metall. Mater. Trans. B, Vol29B, No 12, 19981167-1174. A process for continuous production of Ti powder is described and evaluated. The process is based on reduction of TiCl, by molten Mg, which floats on a molten salt mixture. TiCl, gas is bubbled through the salt and is reduced at the lower surface of the Mg. Ti particles can be recovered at the bottom of the salt mixture and are small enough to be used for PM processing. FORMATION OF FINE NICKEL PARTICLES BY DISCHARGE ELECTROLYSIS IN MOLTEN NICKEL CHLORIDE Y.Ito et al. (Kyoto University, Kyoto, Japan.) J: Jpn Sot. Powder Powder Metall., Vol45, No 12,1998,1142-1147. (In Japanese.) It is reported that fine Ni powders had been produced by discharge electrolysis in a fused LiCl-KCl-NiCl, electrolyte under Ar. Particles were near spherical and the size depended on the concentration of NiCl, in the electrolyte and the discharge conditions.
Sintering PHENOMENA OBSERVED IN THE SPARK PLASMA SYSTEM
An inverse technique, devised from modification of the annealing-evolution algorithm, has been developed for particle sizing and evaluated by numerical tests. It is shown that the technique is effective and has high stability against random noise and low sensitivity to particle shape.
No 11,1998,1092-1097. (In Japanese.) It is reported that hollow Al12wt%Si parts had been made by pulse current pressure sintering round a ceramic core. The alloy densified to 99%. Hexagonal BN was found to be the best material for the core as it could easily by removed after sintering.
EVALUATION OF POROSITY AND PROPERTIES OF SINTERED COMPACTS BY SOUND VELOCITY
SYNTHESIS OF NANOCRYSTALLINE ALUMINIUM-NICKEL BY ROD MILLING
M.Yuasa et al (Science University of Tokyo, Noda, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 45, No 12, 1998, 1116-1121. (In Japanese.) Sound velocities were measured in sintered compacts by an acoustic pulse method to determine the effects of porosity on elastic moduli and mechanical properties. At equal porosities elastic moduli increased with increased sintering temperature. Acoustic microscopy was used to predict fracture position. Relationships between elastic moduli, tensile strength and porosity at fracture position were established. Porosity was above average at the fracture location. Elastic moduli and tensile strength were shown to have been underestimated.
(Chonnam W.N.Myung. H.G.Kim, National University, Kwangju, Korea.) Int. J. Non-Equil. Process., Vol 10, No 314, 1998,305-314. Al-40at%Ni powders were rod milled and characterized. After 200 hours the powder contained N&Al, and NiAl phases and after 800 hours only NiAl. Powder milled for 800 hours had a crystallite size of 5.7 nm. Strain increased with milling time and was 7.07~10~~ after 200 hours milling.
Aluminium
H.J.Fecht, F.Miani. (University of Udine, Udine, Italy.) Int. J. Refractory Metals Hard Mater., Vol 17, No 1-3, 1999, 133139. Energy transfer during synthesis of nanophase alloys and compounds was evaluated for Fe-Cu and Fe-C using Mijssbauer spectroscopy and X-ray diffraction. Energy effects in the two systems were modelled and thermochemical estimates made. Kinetic data is discussed. An estimate was made of the mechano-chemical energy transferred in the nanocrystalline powders.
AMORPHIZATION AND SINTERING OF ALUMINIUM-CHROMIUM ALLOY BY MECHANICAL GRINDING
Fundamentals
K.Ozaki et al. (National Industrial Research Inst., Nagoya, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 45, No 11,1998,1076-1080. (In Japanese.) Amorphous Al-(5 to 15)at%Cr powder was prepared by grinding rapidly solidified ribbons. A quasi-crystalline phase was detected in (7 to 13)%Cr ribbons and Al-(10 to 15)%Cr milled powder was fully amorphous. Al was present in milled powder at less than lO%Cr with the amorphous phase. Compacts were prepared from the powder by pulsed current pressure sintering at 300°C and 500 MPa. Porosity at lO%Cr was 3.3% and at 15%Cr, 20.7%. This was attributed to mass flow of Al to triple points in the microstructure.
MODIFICATION OF ALGORITHM FOR PARTICLE SIZING BY LIGHT SCATTERING
FABRICATION OF HOLLOW PARTS BY PULSE CURRENT PRESSURE SINTERING
M.Ye et al. (Southeast University, Nanjing, China.) Powder Technol., Vol 104, No 1,1999,80-83.
T.Nagae et al. (Toyama Industrial Technology Centre, Takaoka, Japan.) J. Jpn Sot. Powder Powder Metall., Vol45,
M.Omori. (Tohoku University, Sendai, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 45, No 11, 1998, 1055-1060. (In Japanese.) Synonyms for the Spark Plasma System - Spark Plasma Sintering and Plasma Activated Sintering - are noted. The system is characterized by generation of the plasma, which has not been directly identified and in which several phenomena are involved. Some metallic and non-metallic systems were plasma sintered and the results are described.
34
MPR April 2000
iron and steel EVALUATING MECHANO-CHEMICAL POWER TRANSFER IN SYNTHESIS OF IRON-COPPER AND IRON-CARBON
FATIGUE BEHAVIOUR OF SINTERED MOLYBDENUM STEEL (Technical H.Danninger et al. University of Vienna, Vienna, Austria.) 2. Metallkunde, Vol 89, No 2, 1998, 135141. (In English.) 1.5%Mo-0.7%C steel was prepared from elemental powders by pressing and sintering. Un-notched samples were push-pull fatigue tested at 20 kHz for over lo8 cycles. Heat treatment is endurance and shown to increase fatigue limit. porosity to reduce also influenced Sintering conditions fatigue properties.
Sintering PHENOMENA OBSERVED IN THE SPARK PLASMA SYSTEM
An inverse technique, devised from modification of the annealing-evolution algorithm, has been developed for particle sizing and evaluated by numerical tests. It is shown that the technique is effective and has high stability against random noise and low sensitivity to particle shape.
No 11,1998,1092-1097. (In Japanese.) It is reported that hollow Al12wt%Si parts had been made by pulse current pressure sintering round a ceramic core. The alloy densified to 99%. Hexagonal BN was found to be the best material for the core as it could easily by removed after sintering.
EVALUATION OF POROSITY AND PROPERTIES OF SINTERED COMPACTS BY SOUND VELOCITY
SYNTHESIS OF NANOCRYSTALLINE ALUMINIUM-NICKEL BY ROD MILLING
M.Yuasa et al (Science University of Tokyo, Noda, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 45, No 12, 1998, 1116-1121. (In Japanese.) Sound velocities were measured in sintered compacts by an acoustic pulse method to determine the effects of porosity on elastic moduli and mechanical properties. At equal porosities elastic moduli increased with increased sintering temperature. Acoustic microscopy was used to predict fracture position. Relationships between elastic moduli, tensile strength and porosity at fracture position were established. Porosity was above average at the fracture location. Elastic moduli and tensile strength were shown to have been underestimated.
(Chonnam W.N.Myung. H.G.Kim, National University, Kwangju, Korea.) Int. J. Non-Equil. Process., Vol 10, No 314, 1998,305-314. Al-40at%Ni powders were rod milled and characterized. After 200 hours the powder contained N&Al, and NiAl phases and after 800 hours only NiAl. Powder milled for 800 hours had a crystallite size of 5.7 nm. Strain increased with milling time and was 7.07~10~~ after 200 hours milling.
Aluminium
H.J.Fecht, F.Miani. (University of Udine, Udine, Italy.) Int. J. Refractory Metals Hard Mater., Vol 17, No 1-3, 1999, 133139. Energy transfer during synthesis of nanophase alloys and compounds was evaluated for Fe-Cu and Fe-C using Mijssbauer spectroscopy and X-ray diffraction. Energy effects in the two systems were modelled and thermochemical estimates made. Kinetic data is discussed. An estimate was made of the mechano-chemical energy transferred in the nanocrystalline powders.
AMORPHIZATION AND SINTERING OF ALUMINIUM-CHROMIUM ALLOY BY MECHANICAL GRINDING
Fundamentals
K.Ozaki et al. (National Industrial Research Inst., Nagoya, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 45, No 11,1998,1076-1080. (In Japanese.) Amorphous Al-(5 to 15)at%Cr powder was prepared by grinding rapidly solidified ribbons. A quasi-crystalline phase was detected in (7 to 13)%Cr ribbons and Al-(10 to 15)%Cr milled powder was fully amorphous. Al was present in milled powder at less than lO%Cr with the amorphous phase. Compacts were prepared from the powder by pulsed current pressure sintering at 300°C and 500 MPa. Porosity at lO%Cr was 3.3% and at 15%Cr, 20.7%. This was attributed to mass flow of Al to triple points in the microstructure.
MODIFICATION OF ALGORITHM FOR PARTICLE SIZING BY LIGHT SCATTERING
FABRICATION OF HOLLOW PARTS BY PULSE CURRENT PRESSURE SINTERING
M.Ye et al. (Southeast University, Nanjing, China.) Powder Technol., Vol 104, No 1,1999,80-83.
T.Nagae et al. (Toyama Industrial Technology Centre, Takaoka, Japan.) J. Jpn Sot. Powder Powder Metall., Vol45,
M.Omori. (Tohoku University, Sendai, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 45, No 11, 1998, 1055-1060. (In Japanese.) Synonyms for the Spark Plasma System - Spark Plasma Sintering and Plasma Activated Sintering - are noted. The system is characterized by generation of the plasma, which has not been directly identified and in which several phenomena are involved. Some metallic and non-metallic systems were plasma sintered and the results are described.
34
MPR April 2000
iron and steel EVALUATING MECHANO-CHEMICAL POWER TRANSFER IN SYNTHESIS OF IRON-COPPER AND IRON-CARBON
FATIGUE BEHAVIOUR OF SINTERED MOLYBDENUM STEEL (Technical H.Danninger et al. University of Vienna, Vienna, Austria.) 2. Metallkunde, Vol 89, No 2, 1998, 135141. (In English.) 1.5%Mo-0.7%C steel was prepared from elemental powders by pressing and sintering. Un-notched samples were push-pull fatigue tested at 20 kHz for over lo8 cycles. Heat treatment is endurance and shown to increase fatigue limit. porosity to reduce also influenced Sintering conditions fatigue properties.