Simulation of irradiation-induced grain boundary phosphorus segregation by first-principles-based rate theory model including trapping and detrapping processes

Ebihara, Kenichi   ; Suzudo, Tomoaki   ; Yamaguchi, Masatake   

The quantitative estimation of phosphorus (P) segregation at grain boundaries (GBs) under irradiation is required to secure the integrity of nuclear structural materials. The model for estimating irradiation-induced GB P segregation is developed by considering P atoms migrating via octahedral interstitial sites and using the diffusion coefficients evaluated by kMC simulations based on the first-principles calculation. Because the trapping and the detrapping processes of P atoms at GBs are excluded in the model, however, the model cannot estimate the GB P coverage. In this study, we considered incorporating these processes into the model on the basis of the result of the MD simulations. We also examined the temperature dependence of GB P coverage. As results, the GB P segregation was successfully simulated by the model. We also obtained the result showing thermal segregation in the high-temperature region which cannot be simulated by the previous model.