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iron using kinetic Monte Carlo based on first-principles calculationEbihara, Kenichi; Suzudo, Tomoaki; Yamaguchi, Masatake
no journal, ,
no abstracts in English
-ironEbihara, Kenichi; Suzudo, Tomoaki; Yamaguchi, Masatake
no journal, ,
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.
Ebihara, Kenichi; Suzudo, Tomoaki; Yamaguchi, Masatake
no journal, ,
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.