Influence of loading orientation on deformation localization of irradiated tungsten

The plasticity of tungsten in low or medium temperature regimes is dominated by the screw dislocation mobility, which is well known to exhibit a strong non-Schmid effect and loading orientation dependence. As a typical plasma-facing material, many questions regarding the role of these plasticity features on the irradiation degradation performance of tungsten remain unanswered. Considering that deformation local-ization is a continuing critical problem in the nuclear application, in the current work, a systematic set of crystal plasticity calculations is designed to quantify the degree of deformation localization in irradiated tungsten, which is found to be sensitive to the loading orientation. The underlying physical mechanisms are carefully analyzed, highlighting the important role of the number of active slip systems, the non -Schmid effect controlled by the evolution of local stress state, and the high resistance stress induced by irradiation defects. Based on the micro-scale physical mechanisms, two physical indicators are proposed to provide guidance for predicting the orientation-dependent deformation localization in irradiated tung-sten, which agrees well with the simulation results.(c) 2022 Elsevier B.V. All rights reserved.