Kink model for extended defect migration: Theory and simulations

The motion of extended defects in solids is the key to understanding many i mportant physical phenomena. This paper addresses the relationship between defect velocity and driving force. Monte Carlo simulations of linear defect s in two dimensions are performed. The force-velocity relationship is found to he non-linear, in disagreement with commonly used models. A new analyti cal model for the force-velocity relationship is derived that includes the effects of kinks on multiple levels, the non-simultaneity of kink formation , the disappearance of kinks and the non-linear kink force-velocity relatio nship. The resulting force-velocity relationship is relatively simple, but non-linear. This model is shown to yield excellent agreement with the simul ation results over a wide range of driving forces and temperatures, and is readily extendable to a wide variety of defects in two and three dimensions . (C) 2000 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All ri ghts reserved.