1, University of Helsinki, Helsinki, , Finland
We study order transitions and defect formation in a model high-entropy alloy (CuNiCoFe) under ion irradiation by means of molecular dynamics simulations. Using a hybrid Monte-Carlo/molecular dynamics scheme, we generate a model alloy, which is thermodynamically stabilized by configurational entropy at elevated temperatures, but partly decomposes at lower temperatures via copper precipation. Both the high-entropy and the multiphase sample are then subjected to simulated ion irradiation. We analyze the damage accumulation in the studied allow and compared it to an elemental Ni reference system. The results reveal that the high-entropy alloys stabilize at a certain fraction of short-range order even under ion irradiation, independently of its initial configuration. Moreover, the results provide evidence that defect accumulation is reduced in the high-entropy alloy compare to pure Ni. We explain this reduction by the reduced mobility of point defects leading to a steady state of defect creation and annihilation in the course of irradiation. The lattice defects generated by irradiation are shown to act as sinks for Cu segregation.