On the generation of dislocations at misfitting particles in a ductile matrix

Abstract

Abstract The nucleation of a shear dislocation loop from the interface of a misfitting spherical particle in a deformable matrix is considered. The equilibrium shapes and positions of the nucleated dislocation have been calculated. There are two critical levels of misfit. The lower critical level, which is dependent on the particle size, must be reached before nucleation can occur. Above the upper critical level, which is virtually independent of the particle size, nucleation will always occur. Experimental measurements of the critical misfit show that the upper critical level describes the spontaneous generation of dislocations at coherent particles, whereas the lower level describes their generation at incoherent particles. Possible reasons for this are discussed.