Unique irradiation damage behavior and deformation mechanisms in crystalline/amorphous Ag/Cu-Zr nanolaminates

Abstract

Nanolaminated materials due to the abundant interfaces that are efficient sinks for irradiation defects have received broad attention. In this work, Ag/Cu-Zr crystalline/amorphous nanolaminates (C/ANLs) with a wide modulation ratio η from 0.1 to 9.0 were prepared using sputtering magnetron and implanted to a total influence of 1×1017 ions cm-2 He ions to investigate their irradiation damage behavior and mechanical properties. The irradiated Ag/Cu-Zr C/ANLs enable an interesting distribution behavior of He bubbles that only aggregate in the crystalline Ag layers but are absent in the amorphous Cu-Zr layers and interfaces, and become increasingly obvious with reducing η. This is attributed to the synergistic effect of C/A interfaces and amorphous layers as efficient sinks for irradiation defects. The irradiation-induced hardening is found to go through a minimum at η = 3.0, owing to the transformation of strengthening mechanism from He bubbles strengthening in Ag layers as η ≤ 3.0 to free volume annihilation in Cu-Zr layers as η > 3.0. Moreover, the strain rate sensitivity (SRS) m of irradiated C/ANLs firstly decreases rapidly from positive to negative and then increases slowly with raising η, differing from the monotonic η-dependent SRS m of as-deposited C/ANLs. Relevant deformation mechanisms are elucidated based on the dislocation-bubble interactions in terms of pinning effect on dislocations bow-out and dynamic strain aging effect. Our findings could provide valuable insights for the microstructural design of C/ANLs for applications in nuclear reactors.