THE RATE-DEPENDENT DEFORMATION OF A TUNGSTEN HEAVY ALLOY

The rate-dependent deformation of a liquid-phase-sintered W-Ni-Fe (90%W-7%Ni-3%Fe) heavy alloy was investigated. The results of high strain rate tests (obtained using a compression Kolsky bar) combined with quasi-static data indicate that the compressive flow stress of this tungsten heavy alloy increases by perhaps 25% over a range of strain rates from 10(-4) s-1 up to about 7.0 x 10(3) s-1. The material appears to exhibit little or no strain hardening during these dynamic compressive deformations. Microhardness tests were performed on the two phases (the tungsten grains and the matrix) of the material both in the virgin state and after deformation at high strain rates to various levels of strain. The results from the microhardness measurements appear to indicate a greater hardening of the matrix phase than of the tungsten grains with increasing deformation.