The results of the latest works on internal friction and superplasticity in nano- and microcrystalline (NMC) metallic materials are presented. It is shown that for a wide range of NMC materials (pure metals and industrial alloys) there exist some general patterns in the behavior of the temperature dependences of internal friction and elongation to failure at superplastic deformation. A new maximum has been found in the temperature spectrum of internal friction in NMC materials caused by the structural instability of these materials during the heating. A high efficiency of the internal friction method is demonstrated in determining the temperature intervals of recovery and recrystallization processes, dominating recrystallization micromechanism, optimum temperatures of superplastic deformation and estimating the activation energy of grain-boundary diffusion. The proposed model of grain-boundary internal friction is highly effective in describing behavior patterns of NMC materials.
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