The Size Effect on Creep Behavior of Nanostructured Metals

Diffusion is one of the main governing processes of creep deformation in materials. Since the diffusion activation energy for nano-structured materials is lower than that for the bulk ones, the diffusion is enhanced at the nano-scale and low dimensional materials with low melting temperature are expected to creep at lower temperatures and stresses. In this paper, a model has been developed to explain the effect of grain size on diffusion and creep phenomena in nanostructures. This model considers the lattice diffusion process as the main motivation of so-called Nabarro-Herring creep deformation in solids. It is shown that the diffusion and creep phenomena considerably depend on the size. The model also makes it possible to investigate the stress and temperature effects as two crucial factors in creep deformation of nano-structured materials. Graphical illustrations of the model have been presented in the case of nanostructured Cu and Ag. Finally, the achieved results of this study have been compared with the results of other related works in the literature.

کلیدواژه ها:

“Nanostructures” ، “Lattice Self-Diffusion” ، “Diffusion Creep” ، “Grain Size”