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Mechanical alloying of fullerene with metallic elements
Ceramic materials PRODUCTION OF CERAMICS BY HIGH SPEED SOLIDIFICATION MELTED IN A SOLAR FURNACE G.T.Adylov, E.P.Mansurova. Ogneupory, No 8, 1993, 14-15. (In Russian.) It is reported that a spinel-mullitecorundum ceramic strengthened with ZrO, had been made by fusion of powders in a solar furnace, rapid solidification and uniaxial compaction. X-ray structural analysis of powders and sintered ceramic is described.
Composite materials TEMPERATURE DEPENDENCE OF BRANCHING STRESS INTENSITY FACTOR AND CRACK LENGTH A.V.Sameljuk et al. (Inst. for Problems of Materials Science, Kiev, Ukraine.) Int. J. Refractory Metals Hard Mater., Vol 15, No 4, 1997, 215-218. Fracture of Cr-O.Swt%La,O, was investigated as a function of temperature and branching cracks in the brittle alloy. The alloy was characterized by cleavage crack branching. Crack length was 50 to 150 pm. Branching crack stress intensity factor and length are controlled by cleavage fracture toughness and increase exponentially with temperature. INTERACTIONS BETWEEN MATRIX AND REINFORCEMENT IN NICKEL ALUMINIDE COMPOSITES A.E.Murut, C.L.White. (Michigan Technological University, Houghton, USA.) Acta Mater., Vol45, No 6, 1997,2547-2563. Interface reactions between N&Al base matrix alloys and Also, or A&O,-ZrO, fibre reinforcements after HIP consolidation and heat treatment were investigated by determination of composition across the reaction zone. Materials HIPed at 900°C had porosity but no reaction zone was detected. At 1200°C full density was attained but with Zr rich precipitates at the fibre/matrix interface. At 1050°C there was some porosity and the least precipitation of interface reaction products. With additional elements, Zr or Cr-Mo-Zr, the alloy additions diffused towards the interface and Al diffused away. The reaction zone was 1 to 10 pm thick depending on experimental conditions.
Electrical and magnetic materials EFFECT OF PROCESS CONDITIONS ON MAGNETIC PROPERTIES OF MIM SOFT MAGNETIC MATERIALS
36 MPR March 1998
H.Miura et al. (Kumamoto University, Kumamoto, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 43, No 7, 1996, 858862. (In Japanese.) It is noted that electronic components in soft magnetic materials have become smaller and more complex. This was discussed with regard to magnetic and mechanical properties and the use of MIM in part manufacture. The effects of MIM process conditions on properties of MIM Fe-Ni and Fe-Si were investigated. Final densities of about 96% were attained. Magnetic properties were similar or inferior to pure Fe. Mechanical properties were higher than other PM materials.
Hard materials and tool steels PHASES STRUCTURE AND MECHANICAL PROPERTIES OF VANADIUM CARBIDE-TUNGSTEN CARBIDE CERMETS S.A.Cho et al. (Inst. of Scientific Research, Caracas, Venezuela.) Int. J. Refractory Metals Hard Muter., Vol 15, No 4, 1997, 205-214. A study, aimed at replacement of WC in WC-lO%Co by VC, is described. Phase relations, microstructure, hardness and fracture strength of sintered materials were investigated. c&o, PCo, WC, V,C,, VsC,, CO~W,C, Co,W,C and graphite were detected according to composition. Alloys with 18 to 36wt%VC were the most promising. Plots of hardness and fracture strength against composition were near parallel. SUPERHARD SUPERLATTICES S.Barnett, A.Madan. (Northwestern University, Evanston, Illinois, USA.) Phys. World, Vol 11, No 1, 1998, 45-48. The question ‘Is it possible to match or exceed the hardness of diamond and cubic boron nitride? is discussed. It is suggested that the hypothetical crystal, hexagonal PC,N,, with short covalent bonds, could be harder than diamond, but this compound has not been synthesized. Limitations to the use of diamond are noted. Emphasis is placed on hard thin films such as multilayered TiN/NbN which is a superlattice when the successive layers are a few nm thick. TiN/NbN has a Vicker’s hardness of 50 GPa, 2.5 times greater than would be expected from a rule of mixtures approximation. Reasons for superlattice hardening are discussed with reference to models and the structure of the multilayer film. TiN and NbN have the same structure and possible development of non-isostructural superlattices, such as TiNPTiB,, are suggested as possible future developments.
Mechanical alloying INFLUENCE OF MECHANICAL ACTIVATION ON INTERACTION IN MOLYBDENUM-SILICON E.Y.Nesterova et al. (Inst. of Steels and Alloys, Moscow, Russia.) Lzv. V.U.2. Tuestn. Metall., No 1, 1996, 71-74. &I Russian.) Processing of Mo-Si powders in a planetary mill was investigated. Particle size reduction, change in particle shape, internal energy, interaction between MO and Si, heat release and self-propagation synthesis are considered. MECHANICAL ALLOYING OF FULLERENE WITH METALLIC ELEMENTS K.Masuyama et al. (Toyohashi University of Technology, Toyohashi, Japan.) J. Jpn Sot. Powder Powder Metall., Vol43, No 6, 1996,731-737. (ln Japanese.) It is reported that Al, Cu or Fe had been mechanically alloyed with fullerenes (Cc, or C,,). Fullerene is shown to have high stability even after long milling. The MA powders were plasma sintered, carbides forming with Fe and Al. In MA Cufullerene the Cu particles were very small. STRUCTURAL CHANGE IN GRAPHITE BY MECHANICAL MILLING K.Nagano et al. (Nagoya University, Nagoya, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 43, No 6, 1996, 738741. On Japanese.) An investigation of structural changes in graphite during MA is described. The layered structure was amorphized and the nearest neighbour coordination number decreased with increase in milling time. MICROSTRUCTURAL DEVELOPMENT IN MECHANICALLY ALLOYED AND HEAT TREATED NICKEL ALUMINIDE P.Gmhle, EArtz. @lax-Planck Inst., Stuttgart+ Germany.) Acta Mater., Vol 45, No 1, 1997, 201-211. It is reported that, to increase the creep strength, NiAl had been mechanically alloyed with an oxide dispersoid and heat treated to recrystallize. Powders and consolidated materials were characterized. It is shown that coarsening of the dispersoids can be inhibited by allowing abnormal matrix grain growth. It is shown that the contlicting demands of small dispersoids and large grains can be controlled in processing. MILLING OF SYSTEMS WITH POSITIVE HEAT OF MIXING TEMPERATURE EFFECT IN Cu-Ag U.Herr et al. (University of Illinois at Urbana-Champaign, USA.) Acta Muter., Vol45, No 7, 1997,2921-2930.
Composite materials TEMPERATURE DEPENDENCE OF BRANCHING STRESS INTENSITY FACTOR AND CRACK LENGTH A.V.Sameljuk et al. (Inst. for Problems of Materials Science, Kiev, Ukraine.) Int. J. Refractory Metals Hard Mater., Vol 15, No 4, 1997, 215-218. Fracture of Cr-O.Swt%La,O, was investigated as a function of temperature and branching cracks in the brittle alloy. The alloy was characterized by cleavage crack branching. Crack length was 50 to 150 pm. Branching crack stress intensity factor and length are controlled by cleavage fracture toughness and increase exponentially with temperature. INTERACTIONS BETWEEN MATRIX AND REINFORCEMENT IN NICKEL ALUMINIDE COMPOSITES A.E.Murut, C.L.White. (Michigan Technological University, Houghton, USA.) Acta Mater., Vol45, No 6, 1997,2547-2563. Interface reactions between N&Al base matrix alloys and Also, or A&O,-ZrO, fibre reinforcements after HIP consolidation and heat treatment were investigated by determination of composition across the reaction zone. Materials HIPed at 900°C had porosity but no reaction zone was detected. At 1200°C full density was attained but with Zr rich precipitates at the fibre/matrix interface. At 1050°C there was some porosity and the least precipitation of interface reaction products. With additional elements, Zr or Cr-Mo-Zr, the alloy additions diffused towards the interface and Al diffused away. The reaction zone was 1 to 10 pm thick depending on experimental conditions.
Electrical and magnetic materials EFFECT OF PROCESS CONDITIONS ON MAGNETIC PROPERTIES OF MIM SOFT MAGNETIC MATERIALS
36 MPR March 1998
H.Miura et al. (Kumamoto University, Kumamoto, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 43, No 7, 1996, 858862. (In Japanese.) It is noted that electronic components in soft magnetic materials have become smaller and more complex. This was discussed with regard to magnetic and mechanical properties and the use of MIM in part manufacture. The effects of MIM process conditions on properties of MIM Fe-Ni and Fe-Si were investigated. Final densities of about 96% were attained. Magnetic properties were similar or inferior to pure Fe. Mechanical properties were higher than other PM materials.
Hard materials and tool steels PHASES STRUCTURE AND MECHANICAL PROPERTIES OF VANADIUM CARBIDE-TUNGSTEN CARBIDE CERMETS S.A.Cho et al. (Inst. of Scientific Research, Caracas, Venezuela.) Int. J. Refractory Metals Hard Muter., Vol 15, No 4, 1997, 205-214. A study, aimed at replacement of WC in WC-lO%Co by VC, is described. Phase relations, microstructure, hardness and fracture strength of sintered materials were investigated. c&o, PCo, WC, V,C,, VsC,, CO~W,C, Co,W,C and graphite were detected according to composition. Alloys with 18 to 36wt%VC were the most promising. Plots of hardness and fracture strength against composition were near parallel. SUPERHARD SUPERLATTICES S.Barnett, A.Madan. (Northwestern University, Evanston, Illinois, USA.) Phys. World, Vol 11, No 1, 1998, 45-48. The question ‘Is it possible to match or exceed the hardness of diamond and cubic boron nitride? is discussed. It is suggested that the hypothetical crystal, hexagonal PC,N,, with short covalent bonds, could be harder than diamond, but this compound has not been synthesized. Limitations to the use of diamond are noted. Emphasis is placed on hard thin films such as multilayered TiN/NbN which is a superlattice when the successive layers are a few nm thick. TiN/NbN has a Vicker’s hardness of 50 GPa, 2.5 times greater than would be expected from a rule of mixtures approximation. Reasons for superlattice hardening are discussed with reference to models and the structure of the multilayer film. TiN and NbN have the same structure and possible development of non-isostructural superlattices, such as TiNPTiB,, are suggested as possible future developments.
Mechanical alloying INFLUENCE OF MECHANICAL ACTIVATION ON INTERACTION IN MOLYBDENUM-SILICON E.Y.Nesterova et al. (Inst. of Steels and Alloys, Moscow, Russia.) Lzv. V.U.2. Tuestn. Metall., No 1, 1996, 71-74. &I Russian.) Processing of Mo-Si powders in a planetary mill was investigated. Particle size reduction, change in particle shape, internal energy, interaction between MO and Si, heat release and self-propagation synthesis are considered. MECHANICAL ALLOYING OF FULLERENE WITH METALLIC ELEMENTS K.Masuyama et al. (Toyohashi University of Technology, Toyohashi, Japan.) J. Jpn Sot. Powder Powder Metall., Vol43, No 6, 1996,731-737. (ln Japanese.) It is reported that Al, Cu or Fe had been mechanically alloyed with fullerenes (Cc, or C,,). Fullerene is shown to have high stability even after long milling. The MA powders were plasma sintered, carbides forming with Fe and Al. In MA Cufullerene the Cu particles were very small. STRUCTURAL CHANGE IN GRAPHITE BY MECHANICAL MILLING K.Nagano et al. (Nagoya University, Nagoya, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 43, No 6, 1996, 738741. On Japanese.) An investigation of structural changes in graphite during MA is described. The layered structure was amorphized and the nearest neighbour coordination number decreased with increase in milling time. MICROSTRUCTURAL DEVELOPMENT IN MECHANICALLY ALLOYED AND HEAT TREATED NICKEL ALUMINIDE P.Gmhle, EArtz. @lax-Planck Inst., Stuttgart+ Germany.) Acta Mater., Vol 45, No 1, 1997, 201-211. It is reported that, to increase the creep strength, NiAl had been mechanically alloyed with an oxide dispersoid and heat treated to recrystallize. Powders and consolidated materials were characterized. It is shown that coarsening of the dispersoids can be inhibited by allowing abnormal matrix grain growth. It is shown that the contlicting demands of small dispersoids and large grains can be controlled in processing. MILLING OF SYSTEMS WITH POSITIVE HEAT OF MIXING TEMPERATURE EFFECT IN Cu-Ag U.Herr et al. (University of Illinois at Urbana-Champaign, USA.) Acta Muter., Vol45, No 7, 1997,2921-2930.