Molecular Dynamics Study of Irradiation-Induced Defect and Dislocation Evolution in Strained Nickel

Abstract

Molecular dynamics simulations were performed to quantify how elastic tensile strain alters irradiation damage in fcc Ni single crystals subjected to cumulative overlapping displacement cascades initiated by 5 keV PKAs at 300 K. Each cascade produces (54) Frenkel pairs on average, in close agreement with the NRT estimate, and a sequence of 10 cascades corresponds to low irradiation dose in the present cell. Comparing representative cascades (1, 5, and 10) shows that all ballistic and heat-spike recovery processes complete within ((Formula presented.) 10) ps, validating a 20 ps cascade window. Tensile strain systematically increases retained defect populations relative to the unstrained case, consistent with elastic stabilization of interstitial-rich configurations. The heat-spike duration and peak disorder decrease monotonically with strain, indicating faster local energy dissipation under stress. Dislocation analysis reveals a strong bias toward Shockley-partial loops; Hirth, stair-rod, Frank, and perfect components remain secondary. Total and Shockley dislocation densities converge to a steady-state saturation of ((Formula presented.)), and their strain dependence is well captured by a Kocks–Mecking description with a saturation density of ((Formula presented.)) in normalized units. These results demonstrate robust strain–irradiation coupling in fcc metals at low doses.