Superior twin stability and radiation resistance of nanotwinned Ag solid solution alloy

Face-centered cubic (FCC) metals are in general vulnerable to high-energy ion irradiation. Twin boundaries have been shown to improve the irradiation tolerance of FCC metals. However, nanotwins in monolithic metals are unstable during irradiation. In this study, we show that Fe solute can drastically improve irradiation stability of twin boundaries in Ag. By adding merely 1 at.% of Fe solute atoms into Ag matrix, ultra-high-density twins with an average twin thickness of ∼3 nm form in Ag. In situ Kr ion irradiation studies show that defect size and density in Ag₉₉Fe₁ have been significantly reduced comparing with monolithic coarse-grained Ag and nanotwinned Ag. Furthermore, these extremely fine twins survived heavy ion irradiations. Density function theory calculations suggest that Fe solutes stabilize nanotwins by pinning twin boundaries. The mechanisms of enhanced radiation tolerance enabled by solute-twin boundary networks are discussed.