Response to comment on "Grain Boundary Decohesion by Impurity Segregation in a Nickel-Sulfur System"

Yamaguchi, Masatake   ; Shiga, Motoyuki   ; Kaburaki, Hideo

Geng et al. claim in their comment that the segregation energy of sulfur atoms in a nickel grain boundary should be calculated not on average as we did but incrementally. From their own calculations using the incremental binding energies, they concluded that the two-monolayer (GB0 4/4, GB2 4/4) segregation that bring about the reduction of the tensile strength by one order of magnitude has only 1% occupation possibility. However, they miss the point that there are many paths to the (GB0 4/4, GB2 4/4) configuration. In our re-examined calculations, one path has the 50% possibility of the occupation even if we use the incremental binding energies. Furthermore, there may be other paths that have larger possibility. To begin with, Geng et al.'s claims are not meaningful because the prediction of the occupation possibility using the simple McLean's model is not quantitative but qualitative. On the other hand, they claim that another two-monolayer (GB1 4/4, GB2 4/4) configuration brings about the reduction of the tensile strength by one order of magnitude. Their results may be miscalculations, because that is not the case in our re-examined calculations. Furthremore, they suggest a new mechanism of the strong decohesion due to the directional change of the Ni-S bonds. However, they do not show any clear evidence.