Improving radiation-tolerance of bcc multi-principal element alloys by tailoring compositional heterogeneities

Molecular dynamic simulations were performed to investigate the displacement cascade process in refractory bcc complex concentrated alloys, including equi-atomic binary, ternary, and quaternary systems made of the elements Mo, Nb, Ta and W. Our simulation results show that more principal elements do not necessarily mean better radiation resistance. Instead, bcc binary MoNb and NbW CCAs, which have low binding energy of interstitial clusters, can also yield good resistance to the generation of radiation-induced defect clusters. At same time, MoNb also have low self-interstitial formation energy range, so there are more Frenkel Pairs than other bcc binary like MoTa and MoW although number of interstitials in clusters of MoNb is least. More importantly, we find the binding energy of interstitial clusters is highly tunable by changing elements combination and tailoring compositional heterogeneities (such as short-range ordering). Such strategies may pave the way for new design concepts of radiation-tolerant alloys.