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In situ preparation of alumina reinforced aluminium matrix composites
Powder production PREPARATION OF NANO-COMPOSITE COPPER-ZINC PARTICLES BY GAS EVAPORATION
T.Ohno. (Gifu National College of Technology, Gifu, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 44, No 1, 1997, 106-110. (In Japanese.) It is reported that Cu particles had been coated with Zn. Zn vapour condensed on pre-existing nanosized Cu particles made by gas evaporation. The particles are shown to comprise a Cu-Zn phase with a Zn coating. A four-step mechanism is suggested: growth of Cu particles, remelting by application of heat, condensation of Zn, and diffusion to alloy Cu and Zn.
Fundamentals MODELLING OF GRINDING USING PRINCIPLE OF MAXIMUM ENTROPY
SBernotat et al. (Braunschweig University, Braunschweig, Germany.) Powder Technol., Vol95, No 3, 1998, 248-253. A new method of modelling of comminution processes is introduced. A random function describing particle size reduction is used and calculated by maximizing entropy. Energy for comminution is described by Rittinger’s or Kick’s laws. A parameter needed is estimated from measured particle size distribution and the effects of the amount of energy input. OBJECT MODELLING IN VOLUME AND INVESTIGATION OF CROSSSECTIONAL PROPERTIES
ASevcik, I.Kohutek. (Ustav Materialovehu Vyskumu SAV, Kosice, Slovak Republic.) Pokroky Praskove Metal., Vol 35, No 2, 1997. 33-43. (In Czech.) Relationships between cross-sectional and volume analysis of materials were investigated by computer simulation. Use of the software is outlined and is reported to allow formation of three-dimensional arrays of objects, of various sizes, which are described in cross-section for ordered or random conditions. The objects made up 0.1 to 1.0 ~01% of the model material. ELASTIC MODULI OF NON-COHESIVE PARTICULATE MATERLALS
ASawicki, W.Swidzinski. (Polish Academy of Sciences, Gdansk, Poland.) Powder
54 MPR September 1998
Technol., Vol 96, No 1, 1997, 24-32. Problems in measurement of elastic moduli of granular, non-cohesive particulate materials are discussed with consideration given to test methods. A novel method to overcome shortcomings in the existing tests is proposed. The new technique uses oedometric tests, with additional measurements of lateral stress and measurements during loading and unloading. Results for a range of materials are presented. It is suggested that elastic moduli do not depend on density or stress level, contrary to some accepted opinions.
HARDNESS AIW WEAR OF ALUMINIUM COMPOSITE REINFORCED WITH Sic
K.Fukaura et al. (Himeji Inst. of Technology, Himeji, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 44, No 2, 1997, 198-201. (In Japanese.) It is reported that pure aluminium composites, reinforced with Sic particles, had been prepared from powders by hot pressing, and hardness and wear properties determined. Maximum hardness was at 3O%SiC, 2.7 times greater than for pure Al. Wear resistance increased for low and moderate sliding speeds, mechanisms being adhesive and abrasive. Seizure wear occurred at high sliding speeds. IN SITU PREPARATION OF ALUMINA REINFORCED ALUMINIUM MATRIX COMPOSITES
K.Fukaura et al. (Himeji Inst. of Technology, Himeji, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 44, No 2, 1997, 202-206. (In Japanese.) In situ synthesis of Al-Al,O, composites from Al-CuO and A1-TiO, powders, by hot pressing, was investigated. During processing of Al-3wt%CuO, CuO was reduced to Cu. This dissolved in the Al matrix and Al,O, was precipitated, age hardening being detected after heat treatment. In Al-TiO,, TiO, was reduced, Al,O, was precipitated but TiAl,, which is detrimental to properties, was formed.
H.Kimura
Sendai,
bon and steel STRUCTURE AND MAGNETIC PROPERTIES OF SINTERED IRONCHROMIUM WITH ADDED P
Ahminium
NON-EQUILIBRIUM PHASES MECHANICALLY GROUND ALUMINIUM WITH Cr OR V
Powder Metall., Vol44, No 2, 1997, 207212. (In Japanese.) It is reported that Al-Cr and Al-V powders, some with additions of Ce, Co and/or Fe, had been subjected to grinding. Morphology, mechanical structure and thermal stability were Non-equilibrium and investigated. amorphous phases were found in Al rich alloys. Amorphization was easier in atomized powder than in powders made by crushing ingot materials.
IN
et al. (Tohoku University, Japan.) J. Jpn. Sot. Powder
et al. (Daido Inst. of Technology, Nagoya, Japan.) J. Jpn. Sot. Powder Powder Metall., Vo144, No 2, 1997, 179184. (In Japanese.) The effects on structure and magnetic properties of adding 0.4 to 1.2%Fe-P to sintered 12.5%Cr magnet steel were investigated. Maximum values of magnetic properties for alloys sintered at 1200°C for 1 hour were found at 0.6% Fe-P, for DC properties, and 0.8% for AC. Density was increased by longer sintering times which increased DC properties. AC properties declined at first with longer times, and then increased. These changes are attributed to liquid phase sintering. T.Kato
Molybdenum IMPURITY-INDUCED EMBRI’FI’LEMENT OF BEAT AFFECTED ZONE IN WELDED
MO
et al. (Inst. for Problems of Materials Science, Kiev, Ukraine.) Znt. J. Refractory Metals Hard Mater., Vol 15, No 516, 1997, 325-339. Strength, plasticity, fracture and grain boundary segregation in Mo50wt.ppmC-6ppmO-5ppmN and MoBOppmC-50ppmO-6ppmN-1OOOppmZr were investigated as functions of heat treatment furnace annealing or rapid heating and quenching. Quenching is shown to cause microcracking and over-saturation of impurities at grain boundaries, segregation being double that in annealed alloys. The heat treatments were used to simulate conditions in heat affected zones of welded materials. Possible mechanisms are discussed. A.V.Krajnikov
T.Ohno. (Gifu National College of Technology, Gifu, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 44, No 1, 1997, 106-110. (In Japanese.) It is reported that Cu particles had been coated with Zn. Zn vapour condensed on pre-existing nanosized Cu particles made by gas evaporation. The particles are shown to comprise a Cu-Zn phase with a Zn coating. A four-step mechanism is suggested: growth of Cu particles, remelting by application of heat, condensation of Zn, and diffusion to alloy Cu and Zn.
Fundamentals MODELLING OF GRINDING USING PRINCIPLE OF MAXIMUM ENTROPY
SBernotat et al. (Braunschweig University, Braunschweig, Germany.) Powder Technol., Vol95, No 3, 1998, 248-253. A new method of modelling of comminution processes is introduced. A random function describing particle size reduction is used and calculated by maximizing entropy. Energy for comminution is described by Rittinger’s or Kick’s laws. A parameter needed is estimated from measured particle size distribution and the effects of the amount of energy input. OBJECT MODELLING IN VOLUME AND INVESTIGATION OF CROSSSECTIONAL PROPERTIES
ASevcik, I.Kohutek. (Ustav Materialovehu Vyskumu SAV, Kosice, Slovak Republic.) Pokroky Praskove Metal., Vol 35, No 2, 1997. 33-43. (In Czech.) Relationships between cross-sectional and volume analysis of materials were investigated by computer simulation. Use of the software is outlined and is reported to allow formation of three-dimensional arrays of objects, of various sizes, which are described in cross-section for ordered or random conditions. The objects made up 0.1 to 1.0 ~01% of the model material. ELASTIC MODULI OF NON-COHESIVE PARTICULATE MATERLALS
ASawicki, W.Swidzinski. (Polish Academy of Sciences, Gdansk, Poland.) Powder
54 MPR September 1998
Technol., Vol 96, No 1, 1997, 24-32. Problems in measurement of elastic moduli of granular, non-cohesive particulate materials are discussed with consideration given to test methods. A novel method to overcome shortcomings in the existing tests is proposed. The new technique uses oedometric tests, with additional measurements of lateral stress and measurements during loading and unloading. Results for a range of materials are presented. It is suggested that elastic moduli do not depend on density or stress level, contrary to some accepted opinions.
HARDNESS AIW WEAR OF ALUMINIUM COMPOSITE REINFORCED WITH Sic
K.Fukaura et al. (Himeji Inst. of Technology, Himeji, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 44, No 2, 1997, 198-201. (In Japanese.) It is reported that pure aluminium composites, reinforced with Sic particles, had been prepared from powders by hot pressing, and hardness and wear properties determined. Maximum hardness was at 3O%SiC, 2.7 times greater than for pure Al. Wear resistance increased for low and moderate sliding speeds, mechanisms being adhesive and abrasive. Seizure wear occurred at high sliding speeds. IN SITU PREPARATION OF ALUMINA REINFORCED ALUMINIUM MATRIX COMPOSITES
K.Fukaura et al. (Himeji Inst. of Technology, Himeji, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 44, No 2, 1997, 202-206. (In Japanese.) In situ synthesis of Al-Al,O, composites from Al-CuO and A1-TiO, powders, by hot pressing, was investigated. During processing of Al-3wt%CuO, CuO was reduced to Cu. This dissolved in the Al matrix and Al,O, was precipitated, age hardening being detected after heat treatment. In Al-TiO,, TiO, was reduced, Al,O, was precipitated but TiAl,, which is detrimental to properties, was formed.
H.Kimura
Sendai,
bon and steel STRUCTURE AND MAGNETIC PROPERTIES OF SINTERED IRONCHROMIUM WITH ADDED P
Ahminium
NON-EQUILIBRIUM PHASES MECHANICALLY GROUND ALUMINIUM WITH Cr OR V
Powder Metall., Vol44, No 2, 1997, 207212. (In Japanese.) It is reported that Al-Cr and Al-V powders, some with additions of Ce, Co and/or Fe, had been subjected to grinding. Morphology, mechanical structure and thermal stability were Non-equilibrium and investigated. amorphous phases were found in Al rich alloys. Amorphization was easier in atomized powder than in powders made by crushing ingot materials.
IN
et al. (Tohoku University, Japan.) J. Jpn. Sot. Powder
et al. (Daido Inst. of Technology, Nagoya, Japan.) J. Jpn. Sot. Powder Powder Metall., Vo144, No 2, 1997, 179184. (In Japanese.) The effects on structure and magnetic properties of adding 0.4 to 1.2%Fe-P to sintered 12.5%Cr magnet steel were investigated. Maximum values of magnetic properties for alloys sintered at 1200°C for 1 hour were found at 0.6% Fe-P, for DC properties, and 0.8% for AC. Density was increased by longer sintering times which increased DC properties. AC properties declined at first with longer times, and then increased. These changes are attributed to liquid phase sintering. T.Kato
Molybdenum IMPURITY-INDUCED EMBRI’FI’LEMENT OF BEAT AFFECTED ZONE IN WELDED
MO
et al. (Inst. for Problems of Materials Science, Kiev, Ukraine.) Znt. J. Refractory Metals Hard Mater., Vol 15, No 516, 1997, 325-339. Strength, plasticity, fracture and grain boundary segregation in Mo50wt.ppmC-6ppmO-5ppmN and MoBOppmC-50ppmO-6ppmN-1OOOppmZr were investigated as functions of heat treatment furnace annealing or rapid heating and quenching. Quenching is shown to cause microcracking and over-saturation of impurities at grain boundaries, segregation being double that in annealed alloys. The heat treatments were used to simulate conditions in heat affected zones of welded materials. Possible mechanisms are discussed. A.V.Krajnikov