Atomistically-informed hardening and kinetics models of helium bubble in irradiated tungsten

Abstract

In fusion reactor environment, helium bubble acts as a crucial inducement to the performance degradation of plasma facing tungsten, leading to irradiation hardening and embrittlement. The dislocation interacted with helium bubble directly controls the service reliability and safety of irradiated materials. However, the fundamental question regarding the mechanism and quantitative model of this interaction between dislocation and helium-bubble remains largely unexplored. Based on systematic molecular dynamics studies, the interaction mechanism phase diagram is built as a function of helium bubble characters for different types of dislocations. The atomistically-informed mechanism-based models of irradiation hardening and dislocation-helium bubble reaction kinetics are developed, which consider the climb behavior of edge dislocation, the temperature dependent mobility of screw dislocation, as well as the effects of helium-to-vacancy ratio and size of helium bubble. These models can be directly used in micro and meso scale simulations, such as discrete dislocation dynamics and crystal plasticity models. Furthermore, the models well predict the macroscopic experimental results.