Diffusionally modified dislocation-particle elastic interactions

Abstract

The effects of diffusion on the elastic interactions between dislocations and incoherent second phase particles is examined. In the absence of diffusion, the particle-matrix interface is stressed in the presence of a dislocation. These stresses are related, in part, to the elastic requirements that both the tractions and displacements are continuous across the interface. Diffusion in the interface over length scales comparable to the width of the interface leads to a viscous-like relaxation of the shear tractions resulting in a sliding interface. When interfacial diffusion occurs over distances of order the particle radius, normal stress gradients along the particle-matrix interface may also be relaxed. A solution of the elastic problem of an edge dislocation interacting with a cylindrical particle is obtained in the limit that both of these diffusional relaxation processes have gone to completion. As a result of the diffusional relaxation, a dislocation on any glide plane that intersects the particle is always attracted toward the particle. These results differ from the diffusionless interaction, where attraction occurs only when the shear modulus of the matrix exceeds that of the particle. © 1984.