A micromechanical model for polycrystalline creep with grain boundary cavitation

Summary  A micromechanical model is developed to describe effects such as combined power-law creep and diffusion, grain boundary sliding and cavitation in polycrystals. Several aspects of creep-constrained cavitation are taken into account such as diffusion in a cage of creeping matrix material and cavitating facets in a cage of creeping grains. Grain boundary sliding is modelled by distributed micro-shearcracks. It is shown that the different physical mechanisms and their interactions are functions of a well-defined material parameter λ, which can be related to the material length scale L introduced by Rice. Received 18 January 2000; accepted for publication 17 May 2000