Diffusion-induced creep of polycrystalline and nanostructured metals

Kinetic mechanisms of phenomena to be induced by the diffusion on the grain boundaries in polycrystalline and nanostructured (NS) materials have been analyzed. By way of example of nickel and copper nanostructured (grain size 100+300 nm) it was shown that the effect of diffusion induced loss of stre ngth by creep was much observed at temperatures low than 400 K in compariso n with polycrystalline condition with grain size 20 mu m. It was supposed t hat the physical reason for the decrease in the temperature for the effect to manifest itself is much higher value of diffusion coefficients of impuri ties in nanostructures. (C) 1999 Acta Metallurgica Inc.