多元系合金で発生する元素偏析が粒界移動現象に及ぼす影響に関する系統的検討

抄録

Molecular dynamics simulations of grain boundary (GB) migration with high-entropy alloys, which are multi-component alloys composed with five or more than five elements with near equimolar concentrations, are performed to systematically investigate the effects of dynamic GB segregation on GB migration resistance. Bicrystal models with (FeNiCrCo)_1-αCu_α alloys, where the concentration of Cu is changed in the range of α = 0～1 and the other four elements are kept equimolar concentrations each other, are used as model alloys. In these models, Cu tends to segregate to GBs. The same simulations are conducted with pure Cu and a Fe_0.8Cu_0.2 binary alloy as references. First, GB velocity dependence of GB migration resistance is investigated with the equimolar HEA (α = 0.2). The velocity dependence seems to occur with the similar mechanism for binary dilute alloys, elemental segregation of Cu to moving GBs, which has been reported in a previous study. Next, the analyses of the composition dependence of GB migration resistance are conducted with the non-equimolar HEAs. The migration resistance increases with the dynamic GB segregation. This suggests that the dynamic GB segregation can contribute to an increase in the GB migration resistance in the HEAs.