PNNL

Abstract

Molecular dynamics computer simulations of 5 keV displacement cascades near cube-on-cube Cu-Ni interfaces have been performed. Both coherent interfaces (with large coherency stresses) and semi-coherent interfaces (with misfit dislocations in the interface) typical of nanolayer metal composites are considered. The primary damage state of cascades from 5 keV recoil atoms in the composite differs from that in cascades generated in pure Cu and Ni. In the semi-coherent case some defect clusters form directly on the misfit dislocations. Excluding these, the defect yields for both interface types are about two-thirds of the average yield of defects for cascades in the pure metals. In single cascades, as well as for overlapping multiple cascades, the numbers of surviving defects in the semi-coherent interface are significantly different in the Cu and Ni layers, but they are the same in Cu and Ni for the coherent case. Anti-site atomic mixing occurs near both types of interfaces, more so in the coherent case.