Loss of coherency of growing particles by the prismatic punching of dislocation loops

Abstract

Many workers have suggested that a growing precipitate can lose coherency by punching of dislocation loops if the shear stress in the matrix is sufficiently large. This suggestion is investigated for the ellipsoidal particle using the approach of Eshelby (1957). It is found that the maximum value of the shear stress depends only on the transformation strains e_ij , T. Critical values of e_ij T for prismatic punching to occur are suggested for a number of particle morphologies.