Molecular dynamics simulations of irradiated defect clusters evolution in different crystal structures

Irradiation damage is an important cause of material failure in in-service nuclear reactors. It is important to explore the resistance to irradiation of metals with different crystal structures. As the formation and evolution of point defects on the atomic scale caused by cascade collisions in the early stages of irradiation are currently difficult to observe experimentally, it is currently possible to simulate the dynamic process of irradiation damage on the atomic scale by means of molecular dynamics (MD) methods. In this paper, some atomic scale numerical simulations are performed to study the irradiation behaviour and displacement cascades in metals with different crystal structures of bcc-Fe, hcp-Ti, hcp-Zr and fcc-Ni by the MD methods. The effect of temperature and the magnitude of the primary knock-on atom (PKA) energy on the generation and evolution of point defects is mainly studied. Results show that an increase in cascade energies from 0.5 keV to 10 keV can significantly promote defect formation for different crystal structures, while ambient temperature (T) has a slight effect on the number of surviving defects. The simulations also illustrate that high-energy cascades can significantly promote the formation of defect clusters. Statistical results of the displacement cascades show that bcc-Fe produces a small number of stable defects, a small cluster size and number relative to fcc-Ni, hcp-Ti, and hcp-Zr structures, which indicates that the bcc-Fe structure has a good radiation resistance. These findings could provide an appropriate idea for obtaining potential radiation-resistant materials for nuclear reactors.