Atomistic modeling of hardening in spinodally-decomposed Fe-Cr binary alloys
T Suzudo and H Takamizawa and Y Nishiyama and A Caro and T Toyama and Y Nagai, JOURNAL OF NUCLEAR MATERIALS, 540, 152306 (2020).
Spinodal decomposition in thermally aged Fe-Cr alloys leads to significant hardening, which is the direct cause of the so-called 475 degrees C-embrittlement. To illustrate how spinodal decomposition induces hardening by atomistic interactions, we conducted a series of numerical simulations as well as reference experiments. The numerical results indicated that the hardness scales linearly with the short-range order (SRO) parameter, while the experimental result reproduced this relationship within statistical error. Both seemingly suggest that neighboring Cr-Cr atomic pairs essentially cause hardening, because SRO is by definition uniquely dependent on the appearance probability of such pairs. A further numerical investigation supported this notion, as it suggests that the dominant cause of hardening is the pinning effect of dislocations passing over such Cr-Cr pairs. Moreover, this finding has a practical merit, that is, the SRO parameter can serve as a good index of hardening of steels, which is critical for evaluating their lifetime. (C) 2020 The Authors. Published by Elsevier B.V.
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