Effects of Proton Irradiation on Microstructure and Mechanical Properties of Nanocrystalline Cu-10at%Ta Alloy

Duplex nanocrystalline Cu-10at%Ta is attractive for extreme environments because of its grain size stability at high homologous temperatures, owing to dispersed Ta nanoclusters. This study is an initial investigation into the microstructural and mechanical stability of Cu-10at%Ta under irradiation. Proton irradiation is carried out to 1 displacement per atom (dpa) at 500°C. The Cu-10at%Ta exhibits grain size stability throughout irradiation and resistance to the formation of irradiation-induced defects. However, Ta nanoclusters undergo ballistic dissolution. Nanoindentation reveals there is no significant irradiation hardening, consistent with the relatively irradiation-stable microstructure. Ballistic dissolution of Ta nanoclusters is discussed in the context of Orowan strengthening.