On the threshold stress for diffusional creep in pure metals

Abstract

A temperature-dependent threshold stress [sgrave] is often observed for diffusional creep in pure metals and existing experimental data are examined to identify the factors which affect it. The analysis indicates that the threshold stress is inversely proportional to the stacking fault energy. A temperature dependence, characterised by an energy of 22-5 kJ mol⁻¹, is obtained by incorporating the effect of stacking fault energy as well as elastic modulus and Burgers vector in normalising [sgrave]. A model based on grain boundary dislocation climb by jog nucleation and movement is proposed to account for the origin of threshold stress and its temperature dependence.