Interface enabled defects reduction in helium ion irradiated Cu/V nanolayers

Sputter-deposited Cu/V nanolayer films with individual layer thickness, h, varying from 1 to 200 nm were subjected to helium (He) ion irradiation at room temperature. At a peak dose level of 6 displacements per atom (dpa), the average helium bubble density and lattice expansion decrease significantly with decreasing h. The magnitude of radiation hardening decreases with decreasing individual layer thickness, and becomes negligible when h is 2.5 nm or less. This study indicates that nearly immiscible Cu/V interfaces spaced a few nm apart can effectively reduce the concentration of radiation induced point defects. Consequently, Cu/V nanolayers possess enhanced radiation tolerance, i.e., reduction of swelling and suppression of radiation hardening, compared to monolithic Cu or V.