Comparative investigations of diffusion in coarse-grained (20μm), nanocrystalline (0.04μm) and nanostructured (0.3μm) samples were carried out at homologous temperatures of 0.2 to 0.3. The effects exerted by the grain boundary state and grain boundary diffusion impurity flux, upon the creep mechanisms of nanostructured Ni and Cu at 373 to 473K, were studied. A significant change in the apparent creep activation energy under Cu grain boundary diffusion fluxes was attributed to the contribution of grain boundary sliding to the overall deformation.

Grain Boundary Diffusion and Mechanisms of Creep of Nanostructured Metals. Y.R.Kolobov, G.P.Grabovetskaya, K.V.Ivanov, M.B.Ivanov: Interface Science, 2002, 10[1], 31-6