The energy which was required for the emission of a half-rectangular dislocation loop from a mode-I crack tip was investigated. The optimum length/width aspect ratio of the half-rectangular loop, the critical dislocation size, and the activation energy for dislocation emission, were calculated by determining the saddle point of the total energy profile as a function of the length and width. It was found that the activation energy which was deduced for the half-rectangular loop was less than a quarter of that obtained for a semi-circular loop. The effects of the self-energy correction parameter, and of the radius of the dislocation core, upon the activation energy were also analyzed.

T.Zhang: Physica Status Solidi B, 1996, 198[2], 587-97