Self-healing of low angle grain boundaries by vacancy diffusion and dislocation climb

A new analytical model was developed to quantify the role of dislocation climb assisted by vacancy pipe and bulk diffusion in controlling the damage resistance and self-healing of perturbed low angle grain boundaries. Dislocation climb assisted by vacancy pipe diffusion predominantly controls the self-healing process at lower temperatures, while that assisted by bulk diffusion becomes important only at higher temperatures. A relaxation time for the perturbed grain boundary structure was also derived to quantify the time associated with the self-healing process. The extent of this self-healing increases with decreasing grain size, which explains the enhanced damage resistance of nanocrystalline materials.