LAUSR

We have evaluated the diffusion coef cient of phosphorus in α-iron transported in the form of a mixed dumbbell using a kinetic Monte Carlo simulation based on rst-principles calculations. The evaluated diffusion coef cient has been compared with both that for the migration mode via octahedral interstitial sites and that for the migration mode of the vacancy mechanism estimated previously using a rst-principles-based kinetic Monte Carlo simulation. As a result, we have con rmed that the phosphorus diffusion by the two interstitial migration modes is much faster than that of the vacancy migration mode. In addition, by applying the rate-theory model incorporating the evaluated coef cients to the simulation of irradiation-induced grain-boundary phosphorus segregation, it was made clear that modi cations are required to the previous model for GB P segregation and for evaluating GB P coverage. [doi:10.2320/matertrans.ML201602]