Diffusion induced plasticity of nanostructured metals
Yu. R. Kolobov Institute of Strength Physics and Materials Science of SB
RAS, 2/1 Academichesky pr., Tomsk, 634021, Russia
The main characteristic features of grain boundary diffusion of
substitution impurities from an external source (coating) in
nanostructured (produced by severe plastic deformation) metals
(nickel, copper, titanium) have been considered in comparison with
respective ones for grain boundaries in coarse-grained and
nanocrystalline (using electrodeposited nickel by way of example)
states. Physical reasons for the enhancement of diffusivity of grain
boundaries in nanostructured state relative to the diffusivity
coarse-grained metals and bicrystals are discussed.
The analysis of peculiarities and physical mechanisms of plastic
deformation development during creep of nanostructured metals and
dispersed hardened nanocomposites including under the action of
directed grain-boundary diffusion fluxes of substitution or
interstitial impurity from an external source (environment) has been
The determining role of diffusion-controlled processes on grain
boundaries in grain boundary sliding development during creep and
superplastic flow of nanostructured metals and alloys in the service
temperature (using Ni, Cu, Ti, Al-Mg-Li, etc. Based alloys by way of
example) is found.
The possibility to realize low-temperature and/or high strain rate
superplasticity of nanosrtuctured metals and alloys has been studied.
The characteristic features of superplasticity of nanostructured
materials relative to respective ones of fine-grained are discussed.