Atoministic modeling of He embrittlement of alpha-Fe grain boundaries

Suzudo, Tomoaki   ; Yamaguchi, Masatake   ; Tsuru, Tomohito   

He-embrittlement is a major concern for the structural material of future fusion devices, such as the first wall of the blanket, and the understanding of its mechanism is critical for the material design. Although previous studies using the first principles calculations reveal that He weakens the strength of some grain boundaries, a countless types of grain boundaries exist and in principle it is not realistic to analyze all of those types. Consequently, it is important to retrieve common features over the different grain boundaries. In the present study, we analyzed He-embrittlement of plenty types of grain boundaries of alpha-Fe and found that the loss of grain-boundary strength roughly scales with He concentration at each grain boundary regardless of the grain boundary type.