MD and OKMC simulations of the displacement cascades in nickel

The molecular dynamics (MD) method was used to investigate the displacement cascades with primary knock-on atom (PKA) energies of 2–40 keV at 100 and 600 K. The migration energy of defects and their clusters was calculated by nudged elastic band (NEB) method. Object kinetic Monte Carlo (OKMC) was used to simulate the evolution of defects in Ni under annealing. In each annealing stage, the recombination mechanism was discussed and evolution of the defects under different cascade conditions was compared. It was found that the defects generated in high-temperature cascades are more stable than those in the low-temperature cascades. In addition, almost all the defects are annihilated during annealing process at low PKA energy. At PKA energy of 20–40 keV, however, a large number of defects would remain after annealing.