Effect of Re segregation on irradiation damage behavior of Mo-Re alloys

Mo-Re alloys, with their exceptional mechanical properties, emerge as attractive candidates for high-temperature nuclear reactor applications. Nevertheless, a significant challenge they face is radiation-induced embrittlement. Here, the effects of Re solid-solution on the formation and evolution of the defects, induced by primary knock-on atoms with a recoil energy of 30 keV, are quantitatively examined via molecular dynamics (MD) simulations. With help of home-made machine learning potential of high accuracy, our MD simulation results reveal a non-monotonic relationship between the Re effect and radiation tolerance, wherein radiation tolerance initially increases and then decreases with Re concentration. The reduction in radiation tolerance is attributed to inherent Re segregation. Microscopically, regions with local Re nanosegregation can effectively capture self-interstitial atoms, hindering Frenkel pair recombination and facilitating defect aggregation, dislocation multiplication and pinning, thereby enhancing radiation damage. Moreover, radiation cascade events further intensify Re segregation, amplifying this damage effect. Our findings thus highlights the importance of homogenization heat treatment in tailoring radiation-tolerance for Mo-Re alloys.