Effects of surface and boundary diffusion on void growth

Abstract

The coupled equations for boundary and surface diffusion that control the growth of a void along a grain boundary have been solved numerically for the limiting case where the slope of the cavity surface is always small. The resulting solutions are compared with asymptotic results for the same problem that have been developed earlier by other authors. It is shown that existing expressions for “crack-like” and “quasi-equilibrium” growth provide an excellent description of void growth over the entire range of possible conditions. The numerical results illustrate the transition between the two modes and the evolution of the cavity profile during growth. In particular, a wedge-shaped cavity is predicted to develop as a void grows across a grain boundary, even in the absence of crystallographic effects.