Diffusion creep in metals and ceramics: Extension to nanocrystals

The fundamental aspects of diffusion creep are examined with reference to creep parameters and microstructural development. It is demonstrated that there is strong microstructural support for diffusion creep, although the theoretical and experimental creep rates are likely to agree only to within an order of magnitude. This discrepancy arises partly from uncertainties in the diffusion coefficients, and also from a lack of consideration of the stochastic nature of grain size distribution. Models developed for creep in nanocrystals are examined critically. Currently, there is no good experimental evidence for the occurrence of conventional diffusion creep in nanocrystals.