Molecular Dynamics Simulations of Displacement Cascade in Ni-Based Concentrated Solid Solution Alloys

Single-phase concentrated solid solution alloys (SP-CSAs), including high-entropy alloys, have received extensive attention due to their excellent irradiation resistance. In this work, displacement cascade simulations are conducted using the molecular dynamics method to study the evolution of defects in Ni-based SP-CSAs. Compared with pure Ni, the NiCr, NiCo, and NiCu alloys exhibit a larger number of Frankel pairs (FPs) in the thermal peak stage, but a smaller number of surviving FPs. However, the NiFe alloy displays the opposite phenomenon. To explain these different observations for NiFe and other alloys, the formation energy and migration energy of interstitials/vacancies are calculated. In the NiFe alloy, both the formation energy and migration energy barrier are higher. On the other hand, in NiCr and other alloys, the formation energy of interstitials/vacancies is lower, as is the migration energy barrier of interstitials. The energy analysis agrees well with previous observations. The present work provides new insights into the mechanism behind the irradiation resistance of binary Ni-based SP-CSAs.