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Thermoelectric properties of mechanically alloyed iron silicide with silicon carbide
ROLE OF CARBON DURING SINTERING OF INJECTION MOULDED IRON-NICKEL ALLOY COMPACTS H.Jinushi et aE. (Fukuyama University, Fukuyama, Japan.) J. Jpn. Sac. Powder Powder Metall., Vo143, No 5, 1996,656662. (In Japanese.) An investigation of sintering of injection moulded Fe-4wt%Ni-up to 0.8%C compacts, made from carbonyl Fe and Ni and graphite, with regard to C and 0 contents, is described. It is shown that C is used up in reducing metal oxides. Densities up to 95% were attained.
Nickel EFFECTS OF HOT WORKING ON CREEP RUPTURE OF HOT EXTRUDED PM NICKEL BASE ALLOY T.Isomoto, H.Nagai. (Osaka University, Suita, Osaka, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 43, No 5, 1996,663-668. (In English.) The effects of hot working on tensile and creep properties of a PM Ni alloy were investigated and compared with cast and wrought materials. The ductility of the PM alloy above 800°C was improved by hot work. Creep was not affected by the extrusion ratio but was improved by hot forging. Oxide inclusions from powder particle surfaces were aligned in the working direction by extrusion but were redistributed by nonuniform hot forging.
7bngsten FRACTURE BEHAVIOUR AND FRACTURE TOUGHNESS OF SINTERED TUNGSTEN ALLOYS H.Takemata et al. (Japan Steel Works Ltd, Muroran, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 43, No 5, 1996,643-648. (In Japanese.) Fracture toughness of W-Ni-Fe alloys was investigated with regard to strength. It is reported that K,, decreased with increase in tensile strength. In low strength alloys cracks formed by coalescence of voids in the binder and by cleavage of W particles in alloys of higher strength. Fracture toughness If,_ depended on specimen size, increasing with size because of the larger amount of stable crack extension. The relationship between Charpy and dynamic fracture toughness was also investigated.
Coatings ELASTIC PROPERTIES OF TITANIUM NITRIDE HARD FILMS AT AMBIENT AND ELEVATED TEMPERATURES 38 MPR February 1998
W.Pang et al. (University of the Witwatersrand, Johannesburg, South Africa.) Int. J. Refractory Metals Hard Mater., Vol 15, No l/3, 1997, 179-185. Acoustic waves were used to investigate TiN films, of various thicknesses, on high speed steel, using Brillouin scattering. The results are discussed on the basis of a model for supported layer modes, elastic properties of film and substrate and interface boundary conditions, Good agreement is reported for films above 90 urn thick. PLASMA SPRAYING OF GRADIENT MATERIALS WITH BORIDE INTERLAYER V.Brozek et al. (Ustav Anorganicke Chemie, Praha, Czech Republic.) Pokroky Praskove Metal., Vol 34, No 4, 1996, 5-9. (In Czech.) Air plasma spraying and diffusion annealing techniques for boronizing of steels are discussed. Plasma spraying uses a powder to deposit B on the substrate and annealing allows diffusion of B to a suitable depth. Boride penetration into the steel surface is shown to increase adhesion of a later ceramic layer and adjusts for thermal expansion.
Composite materials SILVER-METAL OXIDE AND SILVERTUNGSTEN CARBIDE COMPOSITE MATERIALS S.Stolarz, K.Wojtasik. (Inst. Metali Niezelaznych, Gliwice, Poland.) Metall. Proszkow, Vol 29, No 314, 1996, 23-32. (In Polish.) Optimum process conditions for preparation of Ag-metal oxide materials are presented for Ag-CuO, Ag-Fe oxide, and Ag-PbO. Ag-ZnO, Ag-Cr,O, Preliminary parameters for Ag-WC are given. Materials were pressed from mixed powders, sintered and re-pressed. Properties and density of final products are described.
Electrical and magnetic materials CONSOLIDATION OF MANGANESEALUMINIUM-CARBON ALLOYS BY PM A.Okawa et al. (Sanyo Special Steels, Japan.) Mater. Trans. JIM, Vo137, No 5, 1996,1210-1213. A PM method for fabricating a MnAl-C anisotropic magnet material is described. Gas atomized powders and warm extrusion are used. Consolidation mechanisms, evolution of magnetic properties and effect of die shape on magnetic anisotropy were investigated.
THERMOELECTRIC PROPERTIES OF MECHANICALLY ALLOYED IRON SILICIDE WITH SILICON CARBIDE H.Nagai et al. (Osaka University, Suita, Osaka, Japan.) J. Jpn. Sot. Powder Powder Met&., Vo143, No 5, 1996, 608612. (In Japanese.) It is reported that FeSi, with Sic dispersoids and doped with Mn or CO had been prepared by MA. Thermo-electric properties were determined. Sic had little effect on thermoelectric power. Electrical and thermal conductivity were reduced. Sic inhibited grain growth. IMPROVEMENT OF MAGNETIC PROPERTIES OF SAMARIUM-IRONNITROGEN POWDER BY GRINDING H.Nagai et ~2. (Osaka University, Suita, Osaka, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol43, No 5, 1996, 619623. (In Japanese.) It is reported that mechanical grinding followed by nitriding, without crystallization, had been used to prepare Sm-Fe-N powders. Grinding in NH, gave a powder with O.O35%N. The ground alloy was too distorted to have good magnetic properties, and short time grinding in NH, followed by nitriding was used. Magnetic properties are described. MECHANICAL ALLOYING AND MAGNETIC PROPERTIES OF SAMARIUM-COBALT-IRON POWDERS H.Nagai et al. (Osaka University, Suita, Osaka, Japan.) J. Jpn. Sot. Powder Powder Metal, Vol43, No 5, 1996, 629633. (In Japanese.) An investigation of the effects of MA SmCo(Fe) nanocomposite magnetic powders is described. After milling and low temperature vacuum annealing the powder had a grain size of 10 to 30 nm and good magnetic properties. Fe enhanced remanance. aFe was absorbed into the SmCo phase at 800°C with reduction in coercivity and remanance. The shape of the demagnetization curve depended on %Fe. The enhanced magnetic properties were attributed to an exchange interaction between hard and soft magnetic phases. MAGNETIC PROPERTIES OF MECI-IANICALLY ALLOYED uIRON/NEODYMIUM-IRON-BORON MAGNETS K.Makita et al. (Sumitomo Special Metals Co Ltd, Osaka, Japan.) J. Jpn. Sot. Powder Powder Metal, Vol 43, No 5, 1996,634-639. (In English.) Two-phase (magnetically hard and soft) alloys based on aFe/Nd-Fe-B are
Nickel EFFECTS OF HOT WORKING ON CREEP RUPTURE OF HOT EXTRUDED PM NICKEL BASE ALLOY T.Isomoto, H.Nagai. (Osaka University, Suita, Osaka, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 43, No 5, 1996,663-668. (In English.) The effects of hot working on tensile and creep properties of a PM Ni alloy were investigated and compared with cast and wrought materials. The ductility of the PM alloy above 800°C was improved by hot work. Creep was not affected by the extrusion ratio but was improved by hot forging. Oxide inclusions from powder particle surfaces were aligned in the working direction by extrusion but were redistributed by nonuniform hot forging.
7bngsten FRACTURE BEHAVIOUR AND FRACTURE TOUGHNESS OF SINTERED TUNGSTEN ALLOYS H.Takemata et al. (Japan Steel Works Ltd, Muroran, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 43, No 5, 1996,643-648. (In Japanese.) Fracture toughness of W-Ni-Fe alloys was investigated with regard to strength. It is reported that K,, decreased with increase in tensile strength. In low strength alloys cracks formed by coalescence of voids in the binder and by cleavage of W particles in alloys of higher strength. Fracture toughness If,_ depended on specimen size, increasing with size because of the larger amount of stable crack extension. The relationship between Charpy and dynamic fracture toughness was also investigated.
Coatings ELASTIC PROPERTIES OF TITANIUM NITRIDE HARD FILMS AT AMBIENT AND ELEVATED TEMPERATURES 38 MPR February 1998
W.Pang et al. (University of the Witwatersrand, Johannesburg, South Africa.) Int. J. Refractory Metals Hard Mater., Vol 15, No l/3, 1997, 179-185. Acoustic waves were used to investigate TiN films, of various thicknesses, on high speed steel, using Brillouin scattering. The results are discussed on the basis of a model for supported layer modes, elastic properties of film and substrate and interface boundary conditions, Good agreement is reported for films above 90 urn thick. PLASMA SPRAYING OF GRADIENT MATERIALS WITH BORIDE INTERLAYER V.Brozek et al. (Ustav Anorganicke Chemie, Praha, Czech Republic.) Pokroky Praskove Metal., Vol 34, No 4, 1996, 5-9. (In Czech.) Air plasma spraying and diffusion annealing techniques for boronizing of steels are discussed. Plasma spraying uses a powder to deposit B on the substrate and annealing allows diffusion of B to a suitable depth. Boride penetration into the steel surface is shown to increase adhesion of a later ceramic layer and adjusts for thermal expansion.
Composite materials SILVER-METAL OXIDE AND SILVERTUNGSTEN CARBIDE COMPOSITE MATERIALS S.Stolarz, K.Wojtasik. (Inst. Metali Niezelaznych, Gliwice, Poland.) Metall. Proszkow, Vol 29, No 314, 1996, 23-32. (In Polish.) Optimum process conditions for preparation of Ag-metal oxide materials are presented for Ag-CuO, Ag-Fe oxide, and Ag-PbO. Ag-ZnO, Ag-Cr,O, Preliminary parameters for Ag-WC are given. Materials were pressed from mixed powders, sintered and re-pressed. Properties and density of final products are described.
Electrical and magnetic materials CONSOLIDATION OF MANGANESEALUMINIUM-CARBON ALLOYS BY PM A.Okawa et al. (Sanyo Special Steels, Japan.) Mater. Trans. JIM, Vo137, No 5, 1996,1210-1213. A PM method for fabricating a MnAl-C anisotropic magnet material is described. Gas atomized powders and warm extrusion are used. Consolidation mechanisms, evolution of magnetic properties and effect of die shape on magnetic anisotropy were investigated.
THERMOELECTRIC PROPERTIES OF MECHANICALLY ALLOYED IRON SILICIDE WITH SILICON CARBIDE H.Nagai et al. (Osaka University, Suita, Osaka, Japan.) J. Jpn. Sot. Powder Powder Met&., Vo143, No 5, 1996, 608612. (In Japanese.) It is reported that FeSi, with Sic dispersoids and doped with Mn or CO had been prepared by MA. Thermo-electric properties were determined. Sic had little effect on thermoelectric power. Electrical and thermal conductivity were reduced. Sic inhibited grain growth. IMPROVEMENT OF MAGNETIC PROPERTIES OF SAMARIUM-IRONNITROGEN POWDER BY GRINDING H.Nagai et ~2. (Osaka University, Suita, Osaka, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol43, No 5, 1996, 619623. (In Japanese.) It is reported that mechanical grinding followed by nitriding, without crystallization, had been used to prepare Sm-Fe-N powders. Grinding in NH, gave a powder with O.O35%N. The ground alloy was too distorted to have good magnetic properties, and short time grinding in NH, followed by nitriding was used. Magnetic properties are described. MECHANICAL ALLOYING AND MAGNETIC PROPERTIES OF SAMARIUM-COBALT-IRON POWDERS H.Nagai et al. (Osaka University, Suita, Osaka, Japan.) J. Jpn. Sot. Powder Powder Metal, Vol43, No 5, 1996, 629633. (In Japanese.) An investigation of the effects of MA SmCo(Fe) nanocomposite magnetic powders is described. After milling and low temperature vacuum annealing the powder had a grain size of 10 to 30 nm and good magnetic properties. Fe enhanced remanance. aFe was absorbed into the SmCo phase at 800°C with reduction in coercivity and remanance. The shape of the demagnetization curve depended on %Fe. The enhanced magnetic properties were attributed to an exchange interaction between hard and soft magnetic phases. MAGNETIC PROPERTIES OF MECI-IANICALLY ALLOYED uIRON/NEODYMIUM-IRON-BORON MAGNETS K.Makita et al. (Sumitomo Special Metals Co Ltd, Osaka, Japan.) J. Jpn. Sot. Powder Powder Metal, Vol 43, No 5, 1996,634-639. (In English.) Two-phase (magnetically hard and soft) alloys based on aFe/Nd-Fe-B are