He Implantation Responses in Cu-W Nanocomposites

Nanocomposites of immiscible elements fabricated via physical vapor co-deposition develop far-from-equilibrium microstructure, which is manifested by their high density of phase and grain boundaries. These interfaces are defect sinks and affect the radiation responses of these materials. We investigate the helium (He) implantation response of copper (Cu)-tungsten (W) nanocomposites prepared via co-deposition at 400, 600, and 800 °C. As the co-deposition temperature increases, the phase boundary density decreases while the grain boundary density increases. All nanocomposites exhibit approximately 70% He retention, in comparison to the near-full He retention in single-phase Cu and W. These results indicate that both phase and grain boundaries provide pathways for rapid He removal, with phase boundaries being approximately twice as effective as grain boundaries.