A coupled dislocation dynamics-continuum barrier field model with application to irradiated materials

A new computational methodology for 3-dimensional (3D) Discrete Dislocation Dynamics (DDD) in barrier-strengthened materials is developed. We couple the discrete 3D DDD framework with the Finite Element Method (FEM) solution of a continuum field equation for the evolution of dispersed barriers. Coupled model parameters are obtained from detailed statistical analysis of 3D DDD simulations of single dislocation-barrier interactions. We develop a crystal lattice based continuum material point arrangement method to precisely distribute localized plastic strain as a result of dislocation-barrier interactions, enabling the method to be crystal-structure sensitive. The model is demonstrated by an application to the study of the physics of dislocation channel formation and plastic instability phenomena in irradiated materials. The results are shown to be in agreement with experiments on the magnitude of radiation hardening and the onset of plastic instability. Plastic flow localization in irradiated materials was shown to be more prevalent at high irradiation dose. The method enables future studies of the plastic deformation in precipitation-strengthened alloys, hydrogen-embrittled materials, and the plasticity of irradiated materials.