Effect of solutes on dislocation motion - a phase-field simulation

Based on recent advances in phase-field models for integrating phase and defect microstructures as well as dislocation dynamics, the interactions between diffusional solutes and moving dislocations under applied stresses are studied in three dimensions. A new functional form for describing the eigenstrains of dislocations is proposed, eliminating the dependence of the magnitude of the dislocation Burgers vector on the applied stress and providing correct stress fields of dislocations. A relationship between the velocity of the dislocation and the applied stress is obtained by theoretical analysis and numerical simulations. The operation of Frank-Read sources in the presence of diffusional solutes, the effect of chemical interactions in solid solution on the equilibrium distribution of Cottrell atmosphere, and the drag effect of Cottrell atmosphere on dislocation motion are examined. The results demonstrate that the phase-field model correctly describes the long-range elastic interactions and short-range chemical interactions that control dislocation motion. (C) 2003 Published by Elsevier Ltd.