Steady-state diffusional creep

Abstract

The theory of steady-state diffusional creep is developed for a material in which the grains are large and the dislocations form the principal sources and sinks for vacancies. Under a given applied shear stress p there is an equilibrium length of link in the dislocation network, only slightly longer than that link which provides a dislocation source under the applied stress. The dislocation density increases by the operation of Bardeen-Herring sources, and decreases as dislocations of opposite sign climb towards one another and annihilate. When diffusion occurs predominantly through the bulk of the crystal, the rate of strain is proportional to p ³. At lower temperatures, where diffusion occurs predominantly along the cores of dislocations, the rate of strain is proportional to p ⁵.