Dislocation annihilation and acoustic emission during plastic deformation of crystals

In this paper a soliton description of the dislocation annihilation component of acoustic emission (AE) during plastic deformation of crystals is presented. Based on the soliton nature of dislocation motion, a new model for an elementary AE source is proposed. This source is related to the mechanism of annihilation of a dislocation kink-antikink pair into a breather on account of acoustic losses. First, the dynamics of a dislocation system interacting with acoustic waves is investigated on the basis of a rather simple microscopic lattice model. It is shown that this interaction can be described by a d'Alembert wave equation coupled with a damped sine-Gordon (sG) equation. Within the framework of this model, the emission of sound waves by annihilating dislocation kinks is considered in detail and the dislocation annihilation component of the AE is calculated and expressed in terms of the shear deformation strain. The results of the proposed model support the hypothesis that the annihilation of dislocations rather than the nonstationary motion can be the main source of the AE during plastic flow of metals and allow a better interpretation of existing experimental data.