A steady-state model for diffusion-controlled fracture

Elevated temperature cracking associated with embrittlement from intergranular diffusion of impurities is studied using cohesive zone model for small-scale creep, diffusion and damage. The constitutive equation for the cohesive zone is coupled with stress-assisted diffusion of impurities into the grain boundary. A Kachanov-type damage model is used to describe the effect of impurity concentration on grain boundary strength. Numerical studies reveal the influence of various material parameters and loading conditions on the cracking process.