Deformation behaviour of oxide-dispersion-strengthened silver

Oxide-dispersion-strengthened (ODS) silver was produced by mechanical alloying of pure silverand 5 vol% Cr2O3-powder in air. TEM of the powder and of fully dense specimens after consolidation revealed a duplex structure consisting of pure silver grains and ODS silver grains with dispersoids of ≥40 nm in diameter. Constant extension rate tests in compression were carried out at room temperature (RT) and at 500 °C at strain rates between 10−2 and 10−6 s−1. The yield strength at RT is mainly caused by fine-grain strengthening according to Hall-Petch. At 500 °C, the dispersoids lead to higher flow stress values and a higher stress exponent (n ≈ 11) compared to pure silver (n = 3–5). The deformation behaviour of ODS silver can be explained by a composite model assuming a linear superposition of the creep strengths of pure silver and ODS silver according to their volume fractions. The dispersoids are overcome by localized climb and subsequent thermally activated detachment of dislocations from the departure side of the particles.