MD simulation of primary radiation damage in fcc multi-principal element alloys: Effect of compositional undulation

Fcc single phase alloys with highly concentrated solid solution are competitive candidates for the next-generate radiation-tolerant materials. The present study uses molecular dynamics simulations to study the displacement cascades of NiCoFeCr fcc single-phase concentrated solid-solution alloys (SP-CSAs). The effects of compositional undulation on the generation and evolution of the defects, produced by primary knock-on atoms, are quantitatively analysed. Our simulation results show that the undulation renders considerable compositionally graded interfaces (CGIs) with high threshold energy for displacement, and these CGIs can act as pre-existing defect sinks and confine interstitial defects motion. This increases the recombination rate of residual defects, thus leading to the suppression of Frenkel pairs and large-sized interstitial clusters. In addition, such effect of compositional undulation is correlated with the specific chemical elements, i.e., the Ni-Fe and Co-Fe undulated SP-CSA yield slower radiation damage accumulation. Our findings suggest a new degree of freedom to tailor radiation-tolerance for concentrated solid-solution alloys.