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Iron and steel
PM LITERATURE REVIEW
Processing, Vol 10, No 1, 1997,35-47. It is reported that gas atomized AlMn-Si powders, with high Al contents, contain nm and usi: precipitates which enhance the strength of extruded alloys. Volume fraction of precipitates increases with Mn content and is a maximum in AI-6wt%Mn-1 %Si and is higher in small particles below 10 uiti. The morphology of the precipitates is described. Particles of precipitate are retained on extrusion. Mechanical properties are given as 0.2% proof stress, 436 MPa, tensile strength, 486 MPa, Young's modulus, 83 GPa, 20% elongation and Vickers hardness 144. These materials are considered to be a cheaper alternative to reinforced composites.
MICROSTRUCTURE AND ELEVATED TEMPERATURE STRENGTH OF ALUMINIUM ALLOY
A.Inoue et al. (Tohoku University, Sendai, Japan.) J. Jpn Soc. Powder Powder Metall., Vol 45, No 9, 1998,817823. (In Japanese.) A range of sintered Al-V-Fe alloys, with additions ofTi, Cr or Si, were investigated to determine the presence of quasi-crystalline phases and their effects on elevated temperature strength and microstructure. Properties are given: tensile strength, 430 to 570 MPa; 3 to 7% elongation; Vickers hardness, 150 to 190; and Young's modulus, 80 to 91 GPa.
Beryllium
MECHANICAL PROPERTIES AND THERMAL STABILITY ON ALUMINIUM-CHROMIUM-IRON ALLOYS
MODELLING HOT ISOSTATIC PRESSING OF BERYLLIUM
A.Ziani, G.Michot. (Ecole des Mines, Nancy, France.) Int. J. Non-Equilibrium Processing, Vol 10, No 1, 1997, 59-82. Mechanical properties of Al-3at%Cr(0,1 or 3)%Fe, extruded from gas atomized powders, are presented and compared with other Al alloys. The alloys were developed for high temperature service.
P.I.Stoev. (Kharkov.) Russian Metallurgy (Metally), No 3, 1998, 73-77. (In English.) The compression rate of Be powder in HIP is calculated by analysis of structural and continuum modelling. Constants for the equation are determined. The feasibility of using continuum modelling for compaction of Be powder is discussed.
MECHANICAL PROPERTIES OF ALUMINIUM-CHROMIUM-RARE EARTH BASE ALLOYS
A.Inoue et al. (Tohoku University, Sendai, Japan.) Jpn. Soc. Powder Powder Metall., Vol 45, No 8, 1998, 738743. (In Japanese.) Mechanical properties of hot powder extruded Al-Cr-rare earth-Co alloys were investigated. AI-3at%Cr-1 %Ce1.5%Co had a tensile strength of 592 MPa with 7.3% elongation. Substitution of misch-metal for Co had little effect on mechanical properties. Strength was increased and elongation reduced by addition of Mn and Ti instead of Co. PROPERTIES AND STRUCTURE OF ALUMINIUM DISPERSION STRENGTHENED WITH OXIDE AND CARBIDE
UMartin et al. (Technical University Berg Akademie, Freiberg, Germany.) Metall., Vol 52, No 9, 1998, 508-513. (In German. The mechanical properties and microstructures of PM Al alloys, dispersion strengthened with Al 2 0 S or Al 4C S' were investigated. The materials were mechanically alloyed, cold pressed, hot extruded and subjected to a range of heat treatments. Effects of test temperature on hardness, tensile and compressive properties were studied. Creep properties are discussed.
42 MPR December 1999
'ron and steel EFFECTS OF DENSITY AND SINTER· ING TEMPERATURE ON HIGH STRENGTH STEEL
R.I.Stephens et al. (University of Iowa, Iowa City, USA.) Powder Metall., Vol 41, No 3, 1998,205-210. Density and sintering effects were investigated for Fe-0.5%C-0.85%Mo0.12%Ni-.13%Mn-0.09%Cu-0.75%Zn stearate which was either pressed, sintered, machined and heat treated or was double pressed and double sintered to densities of 7.0 and 7.4 g.cm", Fracture toughness, fractography and fatigue properties were studied. Fracture toughness was higher at the higher density and at the higher of two sintering temperatures, 1120 and 1315°C. On the macroscopic scale fractures were brittle, but had ductile dimpling on the microscopic scale. MICROSTRUCTURAL EVOLUTION OF IRON SINTERED WITH AMORPHOUS IRON-SILICON-BORON
F.A.Filho et al. (IPENIUSP, Sao Paulo, BraziL) Powder Metall., Vol 41, No 4, 1998,255-259. It is reported that the addition of amorphous Fe-Si -B powder to Fe powder increases sintering shrinkage and results in higher density. Studies of Fe4%(Fe-10%Si-165%B) are described. The
Fe-SiB powder was prepared by milling melt spun ribbons which were characterized and shown to be amorphous. The mixed Fe-CFe-Si-B) powders were pressed and sintered under a range of conditions. Fe 2B was found in the sintered alloys. There was an oxide film at the Fe/additive interface. The oxide could be reduced by addition of a small amountofC. MICROSTRUCTURE AND MECHANICAL BEHAVIOUR OF PRESSED AND SINTERED GAS AND WATER ATOM· IZED STAINLESS STEEL POWDERS
ULindstedt, B.Karlson. (Chalmers University of Technology, Goteborg, Sweden.) Powder Metall., Vol 41, No 4, 1998,261-268. Microstructures and mechanical characteristics of 316L stainless steel, single pressed and vacuum sintered from gas or water atomized powders were investigated. The gas atomized powders were mixed with an organic binder to facilitate pressing. After sintering at 1200°C the densities were similar. Sintering at 1350°C gave higher density in the gas atomized powder, attributed to formation of ferrite, resulting in improved mechanical properties. There was less densification in the water atomized powder sintered at 1350°C. The presence of oxides at prior particle boundaries was noted in the water atomized materials. The gas atomized materials are shown to have more diffuse yielding and strain hardening to be independent of porosity. Both materials strain hardened continuously up to fracture. COMPOSITION AND STRUCTURAL MODIFICATIONS TO ALUMINIUMSTAINLESS STEEL INTERFACE
B.Brevaglieri et al. (La Sapienza University, Rome Italy.) Metal Science Technol., Vol 15, No 1, 1997,3-10. An investigation of changes in the structure of 316L stainless steel, with an Al coating, after heat treatment, is described. During heat treatment Al diffuses into the steel. Where there is N in the steel, in the form of CrsN, AIN is formed. Pores in the steel become coated with mixed Al-Cr films instead of Cr 2 0 S in the uncoated steels. Al is shown to improve the corrosion resistance after heat treatment. This is attributed to improved passivation. EFFECT OF RESIDUAL PORES ON MAGNETIC PROPERTIES OF PM FERRITIC STAINLESS STEELS
K.Kusaka et al. (Daido Inst. of Technology, Nagoya, Japan.) Jpn. Soc. Powder Powder Metall., Vol 45, No 7, 1998,685-691. (In Japanese.)
PM LITERATURE REVIEW
Magnetic properties of two ferri tic stainless steel were investigated as func tions of powder particle size and sintering conditions, 1100 to 1300°C for 20 minutes to 4 hours. It is reported that: magnetic properties are affected by particle size and sintering conditions; magnetic induetion and eleetrical resistivity were influenced by sintered density; sintered grain and pore size and shape determined permeability and coercivity for a given density. Pore morphology did not greatly affect mechanical properties. CONTROL OF POROSITY AND MICROSTRUCTURE IN SINTERING OF ATOMIZED CAST IRON POWDER
H .Tomino et at. (Kagawa Industrial Technology Centre, Takamatsu, -Japan. ) Jpn. Soc. Powder Powder Metall., Vol 45, No 8, 1998 , 703-708. (In Japanese. ) Pulsed eleetric current sintering was applied to atomized hypo-eutectic cast iron powder. It is reported that: pulse current sintering allowed attainment of higher density than vacuum sintering. The microstructure depended on sintering temperature and was independent of sintering pressure. MECHANICAL PROPERTIES OF POROUS SINTERED ATOMIZED CAST IRON POWDER
H.Tomino et al. (Kagawa Industrial Technology Centre, Takamatsu, Japan.) Jpn . Soc. Powder Powder Metall. , Vol 45, No 8, 1998, 715-720. (In Japanese. ) Relationships between bend strength and density of vacuum sintered and pulsed electric current sintered atomized hypo-eutectic cast iron were studied. In vacuum sintered material bend strength depended on powder particle size and %C. In the pulsed current sintered alloy bend strength did not depend on particle size, %C or sintering conditions. Bend strength was higher in the vacuum sintered alloy at equal den sities. EFFECTS OF DENSITY AND TEST CONDITIONS ON FATIGUE OF mGH STRENGTH PM STEEL
T.Prucher et at. (Burgess-Norton Manufacturing Co, Geneva, USA) Powder Metall., Vol 41, No 4, 1998,274-280. The effects of density and sintering temperature on ambient temperature variable amplitude fatigue of a high strength low alloy steel, FL4405, were investigated using smooth, notched and pre-cracked samples. Specimens were sintered at 1120 or 1315°C to densities of 7.0 and 7.4 g.cm". Increased density reduced pore size and volume and the higher temperature gave rounded pores. All final fractures were macroscopically brittle but contained microscopic ductile pimples. Increased density increased
fa tigue re si stance but the higher temperature gave a sma ll inc rea se. TWO PHASE CO-EXISTENCE IN MECHANICALLY ALLOYED IRON· COPPER
P.J.Schilling et at. (Un iver sity of New Orleans, New Orleans, USA. ) Acta Mat er., Vol 47, No 8, 1999 ,2525-2537. Fe-(20 to 50 )at%Cu powders were mechanically alloyed under cryogenic conditions. A novel X-ray technique, Xray absorption near edge structure, is used to show the presence of two supersaturated solid solutions, one body-centred cubic and one face-centred cubic, with near to identical compositions. A mechanism to explain this, in terms of extended solubility caused by the milling, free energies of the phases, and nucleation and growth barriers to the a to y and y to a transformations was given. YOUNG'S MODULUS OF PULSE CUR· RENT SINTERED ATOMIZED CAST IRON POWDER
H.Tomino et at. (Kagawa Industrial Technology Centre, Takamatsu, -Iapan.) Jpn. Soc. Powder Powder Metall. , Vol 45, No 8, 1998 , 709-714. (In Japanese.) It is reported that atomized hypoeutectic cast iron had been either vacuum sintered or pulsed electric current sintered. Structures were investigated and Young's modulus measured. It is shown that Young's modulus depended on porosity and por e shape for both sintered materials and was higher for the vacuum sintered material. FLOWABILITY OF SEGREGATION FREE IRON POWDER WITH LUBRICANT CONTAINING WAX
Y.Ozaki et al. (Ka wa saki Steel Corp, Chiba, Japan.) J. Jpn So c. Powder Powder Metall ., Vol 45, No 9, 1998, 849853. (In Japanese.) Adhesive forces dominating the flowability of segregation-free Fe powders are identified as electrostatic, van del' Waals and liquid bridge forces. These are calculated and the adsorption isotherm for water on the Fe powder was measured. It is shown that the van der Waals forces between Fe powder and lubricant particles and between lubricant and lubricant powders are the main factors that determine flowability at relative humidities below 91%.
Lead EXPANSION FORMING OF METALLIC FOAM PARTS FROM FOAMABLE BEADS OR WIRE
Y.Tada, I.Tsutsui. (Univer sit y of Tokushima, Tokushima, Japan.) J. Jpn
Soc. Powder Powder Metall.,VoI45, No 9, 1998 , 790-795. (In Japanese.) It is reported that foamed Pb-30%Sn alloys had been made from Pb-Sn powder and a dense organic granular foaming agent which produced foaming gas on heating. Process conditions were outlined. Beads and wires of the foamed material were produced.
Nickel EFFECT OF SINTERING ENVIRONMENT ON SPECIFIC SURFACE OF SINTERED POROUS NICKEL COMPACTS
Y.Kunieda et at. (Suzuka National College of Technology, Suzuka, Japan.) J. Jpn. Soc. Powder Powder Metall.,Vol 45, No 9, 1998, 796-800. (In Japanese.) The effects of characteristics of Ni powder and the sintering atmosphere on the specific surface area of sintered porous Ni compacts were measured by an interfacial impedance method. Specific surface wa s larger for finer Ni powders and for material sintered by capsule-free HIP.
Platinum group metals FORMATION OF AMORPHOUS ALLOYS OF PLATINUM OR PALLADIUM WITH ALUMINIUM OR ZIRCONRJM
T.Tsuzuki, T.Arakawa.. (Kinki University in Kyushu, Iizuka, Japan.) J. Jpn Soc. Powder Powder Metall.,Vol 45, No 8, 1998 , 754-757. (In Japanese.) Pt- (Al or Zr) and Pd-(Al or Zr) powder mixtures were mechanically alloyed and the process was monitored by X-ray diffraction. A PdAl intermetallic compound was detected early in the milling process. Other alloys became amorphous. Crystallization was investigated by differential thermal analysis, X-ray diffraction and changes in electrical re sistivity.
Titanium CORROSION OF TITANIUM-MOLYBDE· NUM ALLOY IN CAUSTIC SODA SOLUTION
K.Nakahara et at . (Nippon Tungsten Co Ltd, Japan.) J. Jpn Soc. Powder Powder Metall. , Vol 45, No 8, 1998,769-774. (In Japanese. ) Corrosion of sintered Ti-(O, 10,20,30 and 40)wt%Mo, in a range of concentrations of NaOH solution, was investigated. Corrosion rate is reported to increase with increase in %Mo and concentration of NaOH. Ti-40%Mo corroded at ten times the rate of pure Ti in 103 mol .mf solution . Corrosion was shown to be intergranular in Ti-(20, 30 and 40)%Mo after immersion tests.
MPR December 1999 43
Processing, Vol 10, No 1, 1997,35-47. It is reported that gas atomized AlMn-Si powders, with high Al contents, contain nm and usi: precipitates which enhance the strength of extruded alloys. Volume fraction of precipitates increases with Mn content and is a maximum in AI-6wt%Mn-1 %Si and is higher in small particles below 10 uiti. The morphology of the precipitates is described. Particles of precipitate are retained on extrusion. Mechanical properties are given as 0.2% proof stress, 436 MPa, tensile strength, 486 MPa, Young's modulus, 83 GPa, 20% elongation and Vickers hardness 144. These materials are considered to be a cheaper alternative to reinforced composites.
MICROSTRUCTURE AND ELEVATED TEMPERATURE STRENGTH OF ALUMINIUM ALLOY
A.Inoue et al. (Tohoku University, Sendai, Japan.) J. Jpn Soc. Powder Powder Metall., Vol 45, No 9, 1998,817823. (In Japanese.) A range of sintered Al-V-Fe alloys, with additions ofTi, Cr or Si, were investigated to determine the presence of quasi-crystalline phases and their effects on elevated temperature strength and microstructure. Properties are given: tensile strength, 430 to 570 MPa; 3 to 7% elongation; Vickers hardness, 150 to 190; and Young's modulus, 80 to 91 GPa.
Beryllium
MECHANICAL PROPERTIES AND THERMAL STABILITY ON ALUMINIUM-CHROMIUM-IRON ALLOYS
MODELLING HOT ISOSTATIC PRESSING OF BERYLLIUM
A.Ziani, G.Michot. (Ecole des Mines, Nancy, France.) Int. J. Non-Equilibrium Processing, Vol 10, No 1, 1997, 59-82. Mechanical properties of Al-3at%Cr(0,1 or 3)%Fe, extruded from gas atomized powders, are presented and compared with other Al alloys. The alloys were developed for high temperature service.
P.I.Stoev. (Kharkov.) Russian Metallurgy (Metally), No 3, 1998, 73-77. (In English.) The compression rate of Be powder in HIP is calculated by analysis of structural and continuum modelling. Constants for the equation are determined. The feasibility of using continuum modelling for compaction of Be powder is discussed.
MECHANICAL PROPERTIES OF ALUMINIUM-CHROMIUM-RARE EARTH BASE ALLOYS
A.Inoue et al. (Tohoku University, Sendai, Japan.) Jpn. Soc. Powder Powder Metall., Vol 45, No 8, 1998, 738743. (In Japanese.) Mechanical properties of hot powder extruded Al-Cr-rare earth-Co alloys were investigated. AI-3at%Cr-1 %Ce1.5%Co had a tensile strength of 592 MPa with 7.3% elongation. Substitution of misch-metal for Co had little effect on mechanical properties. Strength was increased and elongation reduced by addition of Mn and Ti instead of Co. PROPERTIES AND STRUCTURE OF ALUMINIUM DISPERSION STRENGTHENED WITH OXIDE AND CARBIDE
UMartin et al. (Technical University Berg Akademie, Freiberg, Germany.) Metall., Vol 52, No 9, 1998, 508-513. (In German. The mechanical properties and microstructures of PM Al alloys, dispersion strengthened with Al 2 0 S or Al 4C S' were investigated. The materials were mechanically alloyed, cold pressed, hot extruded and subjected to a range of heat treatments. Effects of test temperature on hardness, tensile and compressive properties were studied. Creep properties are discussed.
42 MPR December 1999
'ron and steel EFFECTS OF DENSITY AND SINTER· ING TEMPERATURE ON HIGH STRENGTH STEEL
R.I.Stephens et al. (University of Iowa, Iowa City, USA.) Powder Metall., Vol 41, No 3, 1998,205-210. Density and sintering effects were investigated for Fe-0.5%C-0.85%Mo0.12%Ni-.13%Mn-0.09%Cu-0.75%Zn stearate which was either pressed, sintered, machined and heat treated or was double pressed and double sintered to densities of 7.0 and 7.4 g.cm", Fracture toughness, fractography and fatigue properties were studied. Fracture toughness was higher at the higher density and at the higher of two sintering temperatures, 1120 and 1315°C. On the macroscopic scale fractures were brittle, but had ductile dimpling on the microscopic scale. MICROSTRUCTURAL EVOLUTION OF IRON SINTERED WITH AMORPHOUS IRON-SILICON-BORON
F.A.Filho et al. (IPENIUSP, Sao Paulo, BraziL) Powder Metall., Vol 41, No 4, 1998,255-259. It is reported that the addition of amorphous Fe-Si -B powder to Fe powder increases sintering shrinkage and results in higher density. Studies of Fe4%(Fe-10%Si-165%B) are described. The
Fe-SiB powder was prepared by milling melt spun ribbons which were characterized and shown to be amorphous. The mixed Fe-CFe-Si-B) powders were pressed and sintered under a range of conditions. Fe 2B was found in the sintered alloys. There was an oxide film at the Fe/additive interface. The oxide could be reduced by addition of a small amountofC. MICROSTRUCTURE AND MECHANICAL BEHAVIOUR OF PRESSED AND SINTERED GAS AND WATER ATOM· IZED STAINLESS STEEL POWDERS
ULindstedt, B.Karlson. (Chalmers University of Technology, Goteborg, Sweden.) Powder Metall., Vol 41, No 4, 1998,261-268. Microstructures and mechanical characteristics of 316L stainless steel, single pressed and vacuum sintered from gas or water atomized powders were investigated. The gas atomized powders were mixed with an organic binder to facilitate pressing. After sintering at 1200°C the densities were similar. Sintering at 1350°C gave higher density in the gas atomized powder, attributed to formation of ferrite, resulting in improved mechanical properties. There was less densification in the water atomized powder sintered at 1350°C. The presence of oxides at prior particle boundaries was noted in the water atomized materials. The gas atomized materials are shown to have more diffuse yielding and strain hardening to be independent of porosity. Both materials strain hardened continuously up to fracture. COMPOSITION AND STRUCTURAL MODIFICATIONS TO ALUMINIUMSTAINLESS STEEL INTERFACE
B.Brevaglieri et al. (La Sapienza University, Rome Italy.) Metal Science Technol., Vol 15, No 1, 1997,3-10. An investigation of changes in the structure of 316L stainless steel, with an Al coating, after heat treatment, is described. During heat treatment Al diffuses into the steel. Where there is N in the steel, in the form of CrsN, AIN is formed. Pores in the steel become coated with mixed Al-Cr films instead of Cr 2 0 S in the uncoated steels. Al is shown to improve the corrosion resistance after heat treatment. This is attributed to improved passivation. EFFECT OF RESIDUAL PORES ON MAGNETIC PROPERTIES OF PM FERRITIC STAINLESS STEELS
K.Kusaka et al. (Daido Inst. of Technology, Nagoya, Japan.) Jpn. Soc. Powder Powder Metall., Vol 45, No 7, 1998,685-691. (In Japanese.)
PM LITERATURE REVIEW
Magnetic properties of two ferri tic stainless steel were investigated as func tions of powder particle size and sintering conditions, 1100 to 1300°C for 20 minutes to 4 hours. It is reported that: magnetic properties are affected by particle size and sintering conditions; magnetic induetion and eleetrical resistivity were influenced by sintered density; sintered grain and pore size and shape determined permeability and coercivity for a given density. Pore morphology did not greatly affect mechanical properties. CONTROL OF POROSITY AND MICROSTRUCTURE IN SINTERING OF ATOMIZED CAST IRON POWDER
H .Tomino et at. (Kagawa Industrial Technology Centre, Takamatsu, -Japan. ) Jpn. Soc. Powder Powder Metall., Vol 45, No 8, 1998 , 703-708. (In Japanese. ) Pulsed eleetric current sintering was applied to atomized hypo-eutectic cast iron powder. It is reported that: pulse current sintering allowed attainment of higher density than vacuum sintering. The microstructure depended on sintering temperature and was independent of sintering pressure. MECHANICAL PROPERTIES OF POROUS SINTERED ATOMIZED CAST IRON POWDER
H.Tomino et al. (Kagawa Industrial Technology Centre, Takamatsu, Japan.) Jpn . Soc. Powder Powder Metall. , Vol 45, No 8, 1998, 715-720. (In Japanese. ) Relationships between bend strength and density of vacuum sintered and pulsed electric current sintered atomized hypo-eutectic cast iron were studied. In vacuum sintered material bend strength depended on powder particle size and %C. In the pulsed current sintered alloy bend strength did not depend on particle size, %C or sintering conditions. Bend strength was higher in the vacuum sintered alloy at equal den sities. EFFECTS OF DENSITY AND TEST CONDITIONS ON FATIGUE OF mGH STRENGTH PM STEEL
T.Prucher et at. (Burgess-Norton Manufacturing Co, Geneva, USA) Powder Metall., Vol 41, No 4, 1998,274-280. The effects of density and sintering temperature on ambient temperature variable amplitude fatigue of a high strength low alloy steel, FL4405, were investigated using smooth, notched and pre-cracked samples. Specimens were sintered at 1120 or 1315°C to densities of 7.0 and 7.4 g.cm". Increased density reduced pore size and volume and the higher temperature gave rounded pores. All final fractures were macroscopically brittle but contained microscopic ductile pimples. Increased density increased
fa tigue re si stance but the higher temperature gave a sma ll inc rea se. TWO PHASE CO-EXISTENCE IN MECHANICALLY ALLOYED IRON· COPPER
P.J.Schilling et at. (Un iver sity of New Orleans, New Orleans, USA. ) Acta Mat er., Vol 47, No 8, 1999 ,2525-2537. Fe-(20 to 50 )at%Cu powders were mechanically alloyed under cryogenic conditions. A novel X-ray technique, Xray absorption near edge structure, is used to show the presence of two supersaturated solid solutions, one body-centred cubic and one face-centred cubic, with near to identical compositions. A mechanism to explain this, in terms of extended solubility caused by the milling, free energies of the phases, and nucleation and growth barriers to the a to y and y to a transformations was given. YOUNG'S MODULUS OF PULSE CUR· RENT SINTERED ATOMIZED CAST IRON POWDER
H.Tomino et at. (Kagawa Industrial Technology Centre, Takamatsu, -Iapan.) Jpn. Soc. Powder Powder Metall. , Vol 45, No 8, 1998 , 709-714. (In Japanese.) It is reported that atomized hypoeutectic cast iron had been either vacuum sintered or pulsed electric current sintered. Structures were investigated and Young's modulus measured. It is shown that Young's modulus depended on porosity and por e shape for both sintered materials and was higher for the vacuum sintered material. FLOWABILITY OF SEGREGATION FREE IRON POWDER WITH LUBRICANT CONTAINING WAX
Y.Ozaki et al. (Ka wa saki Steel Corp, Chiba, Japan.) J. Jpn So c. Powder Powder Metall ., Vol 45, No 9, 1998, 849853. (In Japanese.) Adhesive forces dominating the flowability of segregation-free Fe powders are identified as electrostatic, van del' Waals and liquid bridge forces. These are calculated and the adsorption isotherm for water on the Fe powder was measured. It is shown that the van der Waals forces between Fe powder and lubricant particles and between lubricant and lubricant powders are the main factors that determine flowability at relative humidities below 91%.
Lead EXPANSION FORMING OF METALLIC FOAM PARTS FROM FOAMABLE BEADS OR WIRE
Y.Tada, I.Tsutsui. (Univer sit y of Tokushima, Tokushima, Japan.) J. Jpn
Soc. Powder Powder Metall.,VoI45, No 9, 1998 , 790-795. (In Japanese.) It is reported that foamed Pb-30%Sn alloys had been made from Pb-Sn powder and a dense organic granular foaming agent which produced foaming gas on heating. Process conditions were outlined. Beads and wires of the foamed material were produced.
Nickel EFFECT OF SINTERING ENVIRONMENT ON SPECIFIC SURFACE OF SINTERED POROUS NICKEL COMPACTS
Y.Kunieda et at. (Suzuka National College of Technology, Suzuka, Japan.) J. Jpn. Soc. Powder Powder Metall.,Vol 45, No 9, 1998, 796-800. (In Japanese.) The effects of characteristics of Ni powder and the sintering atmosphere on the specific surface area of sintered porous Ni compacts were measured by an interfacial impedance method. Specific surface wa s larger for finer Ni powders and for material sintered by capsule-free HIP.
Platinum group metals FORMATION OF AMORPHOUS ALLOYS OF PLATINUM OR PALLADIUM WITH ALUMINIUM OR ZIRCONRJM
T.Tsuzuki, T.Arakawa.. (Kinki University in Kyushu, Iizuka, Japan.) J. Jpn Soc. Powder Powder Metall.,Vol 45, No 8, 1998 , 754-757. (In Japanese.) Pt- (Al or Zr) and Pd-(Al or Zr) powder mixtures were mechanically alloyed and the process was monitored by X-ray diffraction. A PdAl intermetallic compound was detected early in the milling process. Other alloys became amorphous. Crystallization was investigated by differential thermal analysis, X-ray diffraction and changes in electrical re sistivity.
Titanium CORROSION OF TITANIUM-MOLYBDE· NUM ALLOY IN CAUSTIC SODA SOLUTION
K.Nakahara et at . (Nippon Tungsten Co Ltd, Japan.) J. Jpn Soc. Powder Powder Metall. , Vol 45, No 8, 1998,769-774. (In Japanese. ) Corrosion of sintered Ti-(O, 10,20,30 and 40)wt%Mo, in a range of concentrations of NaOH solution, was investigated. Corrosion rate is reported to increase with increase in %Mo and concentration of NaOH. Ti-40%Mo corroded at ten times the rate of pure Ti in 103 mol .mf solution . Corrosion was shown to be intergranular in Ti-(20, 30 and 40)%Mo after immersion tests.
MPR December 1999 43