Monolithic Ag and Ni films and Ag/Ni multilayers with individual layer thickness of 5 and 50 nm were subjected to in situ Kr ion irradiation at room temperature to 1 displacement-per-atom (a fluence of 2 × 1014 ions/cm2). Monolithic Ag has high density of small loops (4 nm in diameter), whereas Ni has fewer but much greater loops (exceeding 20 nm). In comparison, dislocation loops, ∼4 nm in diameter, were the major defects in the irradiated Ag/Ni 50 nm film, while the loops were barely observed in the Ag/Ni 5 nm film. At 0.2 dpa (0.4 × 1014 ions/cm), defect density in both monolithic Ag and Ni saturated at 1.6 and 0.2 × 10 23/m3, compared with 0.8 × 1023/m 3 in Ag/Ni 50 nm multilayer at a saturation fluence of ∼1 dpa (2 × 1014 ions/cm2). Direct observations of frequent loop absorption by layer interfaces suggest that these interfaces are efficient defect sinks. Ag/Ni 5 nm multilayer showed a superior morphological stability against radiation compared to Ag/Ni 50 nm film.
- in situ radiation