Stress-induced absorption and emission of point defects by grain boundaries

Abstract

AbstractIt is postulated that the emission and absorption of point defects take place by dislocation climb in grain boundaries which contain structural arrays of dislocations accommodating misorientations either from single crystal or perfect coincidence orientations. In the absence of any extrinsic dislocation structure, the climb required will result in perturbations to an equilibrated array and the forces required to stabilize these perturbations are estimated by considering elastic interactions between the dislocations. This leads to a threshold driving force for point defect emission or absorption which may be manifested as a threshold stress for diffusional creep. Effects of the grain boundary dislocation structure on the threshold stress are investigated and the energy associated with an array perturbation is estimated.