High temperature plastic deformation of two V-Ga alloys with A15 structure

A study of high temperature plastic deformation has been undertaken on alloys of V-18 at. pct Ga and V-23 at. pct Ga. The materials were prepared by arc melting, homogenizing, and transformation annealing, resulting in polycrystalline A15 structure. Through compression testing and load-relaxation testing, plastic deformation has been studied over a strain rate range from 10^-6 to 10^-2/s and a temperature range from 1000 to 1300 °C. Flow stress decreases with increased temperature and decreased strain rate. Stress-strain rate relations may be fitted with a power law creep expression. The flow stress is influenced by the length of the 1150 °C transformation anneal; longer anneals result in a decrease in flow stresses projected from load relaxation testing. Analysis of compressive yield strength data places the activation energy for A15 V-Ga creep roughly in the 400 kJ/mol range.