Numerical estimation of phosphorus transport for different migration modes in -iron

Ebihara, Kenichi   ; Suzudo, Tomoaki   ; Yamaguchi, Masatake   

It is desired that segregation of phosphorus(P), which is known to to cause GB embrittlement in neutron-irradiated reactor pressure vessel steels, to grain-boundary is estimated for various irradiation conditions. In order to evaluate GB P segregation using the first-principles-based rate theory model, we evaluated the diffusion coefficient(DC) for mixed interstitial dumbbell(MID) in -iron using the first-principles-based kinetic Monte Carlo(kMC) simulation, and compared it with those both for octahedral interstitial P(octP) atoms and for the vacancy(V) migration mode. As results, it was confirmed that DCs of MIDs and octP atoms are much larger than that of V migration mode. In addition, by applying the model incorporating the evaluated DCs to simulation of GB P segregation, it was found that the model needs to be modified. Furthermore, we will describe the investigation of the process of GB P segregation using molecular dynamics simulation.