タングステン系焼結合金の機械的性質に及ぼす微細構造の影響

概要

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This report describes the effects of microstructure on mechanical properties of sintered W-Ni-Fe alloys. Tungsten heavy alloys have a useful combination of density and mechanical properties for several applications. The microstructure consists of a rounded tungsten phase (typically 50 μm in diameter) surrounded by a matrix phase containing dissolved tungsten. This paper focusses on the density, strength and ductility variations at high tungsten concentrations (91.3 to 97.0 wt%W).<BR>Following the increase of W content, contiguities between W grains become higher, and when W content ex-ceeds 97.0 wt%, tensile strength and elongation decrease drastically. During tensile testing, cracks form on the surface of the specimens at W-W grain boundaries. The chemical additions are measured for heavy alloys which increase the solubility of tungsten in the matrix during sintering.<BR>These results were discussed in terms of microstructures, size of fracture source, toughness of alloy, etc..
社団法人粉体粉末冶金協会の論文