3D Discrete Dislocation Dynamics Applied To Dislocation-Precipitate Interactions

Abstract

The 3D Discrete Dislocation Dynamics (DDD) method has been applied to investigate the effects of precipitates on the plasticity of FCC single crystals. A method to represent the internal interfaces by a series of facets with a pre-defined strength has been proposed. For a full account of the mutual elastic interactions between dislocations and second-phase particles, the coupling method with a finite element method is extended. In addition, a new parallel 3D DDD code has been developed using the standard Message passing Interface (MPI) in order to fulfill the computational demand of this work, which was not feasible even though the computing efficiency of the serial 3D DDD algorithm has been improved by revisiting the ’box method’ The image stresses due to a three-dimensional particle were computed using the FEM/DDD coupling code. The numerical results has been compared to the corresponding analytical solutions. The second application deals with the effect of the elastic modulus mismatch on the flow stress and the subsequent hardening behavior. The image stresses were found to affect significantly the work hardening and the the local events such as cross slip and climb. Finally, the fatigue of precipitatehardened materials was simulated using the new parallel DDD code. Major effects of shearable and non-shearable particles on the fatigue properties were well reproduced by the simulations, and the simulation results showed good agreements with the available experimental observations in a qualitative way. The mechanism of the intense slip band formation is proposed from the observation of the simulated dislocation microstructure.