First-principles-based equilibrium Monte Carlo simulations of Cr-rich cluster stability in Fe-Cr-Al alloys; Effects of Al content and vacancies on the transition from promotion to suppression

Abe, Yosuke  ; Kubo, Atsushi; Ukai, Shigeharu  ; Tsuru, Tomohito   

Understanding the stability of Cr-rich precipitates (CrRPs) is key to developing radiation-resistant ODS Fe-Cr-Al alloys. This study uses first-principles-based equilibrium Monte Carlo simulations to assess how Al content and irradiation-induced vacancies affect CrRP formation and atomic-scale structure. CrRP formation peaks at around 12 at.% Al, showing a non-monotonic trend. Higher Al levels cause segregation at CrRP-matrix interfaces and internal Al incorporation, leading to structural disorder and reduced stability. Vacancies alone have limited impact but co-segregate with Al near interfaces, potentially affecting diffusion and interfacial integrity under irradiation. These findings provide atomic-level insights for designing advanced Fe-Cr-Al alloys and guiding mesoscale modeling.