Modified interatomic potential for simulating Ti3AlC2 under irradiation at the sub-angstrom range

Abstract

MAX phases are promising materials for nuclear reactor components and advanced nuclear energy systems due to their tolerance of irradiation and capability of working under extreme conditions. When exploring the damage mechanism of the MAX phase under irradiation using molecular dynamics simulations, the reliability of the results largely depends on the accuracy of the interatomic potential. While the conventional Tersoff potential is capable of studying the equilibrium state properties of covalently bonded systems, its description of short-range atomic interactions often leads to biased results. In this study, we introduce a modified interatomic potential model that accurately captures short-range interactions for the Ti3AlC2 MAX phase. This model couples the Ziegler–Biersack–Littmark potential with the potential function from first-principles calculations at the repulsive region and the Tersoff potential at the equilibrium region. It is then employed in collision simulations of Ti3AlC2 under irradiative environment. It is found that the modified potential can well reproduce recently reported stress–strain relationship of Ti3AlC2 nanowires under tension. The calculated phonon dispersion relationship and kinetic energy transfer during collision are all consistent with first-principles calculations. A large Ti3AlC2 model containing 22 968 atoms is also constructed to investigate the structural reconstruction under irradiation. The results demonstrate good capability of our modified model in studying Ti3AlC2 under extreme conditions.