Molecular dynamics study of phosphorus migration in 3(111) and 5(0-13) grain boundaries of -iron

Ebihara, Kenichi   ; Suzudo, Tomoaki   

Phosphorus atoms in steels accumulate at grain boundaries via thermal and/or irradiation effects and induce grain boundary embrittlement. Quantitative prediction of phosphorus segregation at grain boundaries under various temperature and irradiation conditions is therefore essential for preventing embrittlement. To develop a model of grain boundary phosphorus segregation in -iron, we studied the migration of a phosphorus atom in two types of symmetrical tilt grain boundaries (3[1-10](111) and 5[100](0-13) grain boundaries) using molecular dynamics simulations with an embedded atom method potential. The results revealed that, in the 3 grain boundary, phosphorus atoms migrate three-dimensionally mainly in the form of interstitial atoms, whereas in the 5 grain boundary, these atoms migrate one-dimensionally mainly via vacancy-atom exchanges. Moreover, de-trapping of phosphorus atoms and vacancies was investigated.