On physical nature of creep acceleration effect in submicrocrystalline materials

An analysis of special features of manifestation of the creep acceleration effect in polycrystalline metals and alloys in the presence of grain-boundary diffusion fluxes of an impurity from an external medium is made. It is noted that in certain cases where the diffusion properties of sub-boundary regions differ greatly from those within the boundary and in the bulk of the grain (e.g., in materials with submicrocrystalline structure (grain size 0.1–0.5 µm) and/or in the case of diffusion along the grain boundary of a strongly segregating impurity), conventional theoretical methods of calculation of the temperature-temporal range of the occurrence of the above effect have to be corrected. Based on the analysis of the experimental data, feasible solutions to the problem are discussed.