Effect of Microstrocture on Mechanical Properties of Sintered Tungsten Base Alloys

Abstract

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).
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.
These results were discussed in terms of microstructures, size of fracture source, toughness of alloy, etc..