Atomistic modeling of hardening in thermally-aged Fe-Cr binary alloys

Suzudo, Tomoaki   ; Nagai, Yasuyoshi*; Toyama, Takeshi*; Takamizawa, Hisashi ; Nishiyama, Yutaka ; Caro, A.*

The hardening in phase-separated Fe-Cr binary alloys is a direct cause of so-called 475C embrittlement. We here conduct a series of atomistic simulations with reference experiments to establish a model of the hardening phenomenon caused by spinodal decomposition. The result indicated that the hardness predicted by the simulations linearly scales with the short-range order (SRO) parameter and have a good agreement with those by the experiments. We also found that the linear relation is aging-temperature independent while the relation of the hardening to the well-known variation parameter varies with the annealing temperature. This finding has a practical merit, that is, the SRO parameter can be a good index to monitor ongoing hardening of steels and to estimate their lifetime.