Crystal plasticity investigation of the microstructural factors influencing dislocation channeling in a model irradiated bcc material

A continuum crystal plasticity framework is used to study the effect of microstructure and mesoscopic factors on dislocation channeling and flow localization in an irradiated model bcc alloy. Simulated dislocation channeling characteristics are correlated to the dislocation and defect densities in the substructure, local Schmid factor, and stress triaxiality, in terms of their temporal and spatial evolution. A metric is introduced to assess the propensity for localization and is correlated to the grain-level Schmid factor. It is found that localization generally takes place in grains with a local Schmid factor in the range 0.42 or higher. Surface slip step heights are computed at free surfaces and compared to relevant experiments.