Molecular dynamics simulation of mechanical properties of NiCo alloy under primary cascade damage

Investigating the performance of single-phase solid solution alloys (SP-CSAs) after cascade damage is of significant importance for their industrial applications. This study employs molecular dynamics simulations to investigate the cascade process of a typical NiCo SP-CSA at different primary knock-on atom (PKA) energies and the subsequent effects on mechanical properties. It is found that as the PKA energy increases, the number of defects increases linearly, the size of the defect clusters grows, and most of the defects are caused by the displacement of Ni atoms. However, the yield strain and yield strength of the cascaded NiCo alloys decreased significantly during the subsequent tensile process, and the decrease increased with the increase of PKA energy. This is mainly because cascade-induced point defects become nucleation sites for dislocations with the application of strain, leading to premature plastic deformation of the alloy and altering their deformation modes. This ultimately results in significant degradation of mechanical properties. These findings offer theoretical insights for designing new reactor materials with enhanced irradiation resistance.