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M: Metallphysik

M 36: Nanoskalige Materialien IV

M 36.5: Fachvortrag

Friday, March 30, 2001, 12:00–12:15, S5.3

Diffusion and properties of bulk nanostructured metals and nanocomposites — •Yurii Kolobov — Institute of Strength Physics and Materials Science, 634021, Tomsk, Russia

The main features of grain boundary diffusion of substitution impurities from external source (coating) in nanostructured (processed by severe plastic deformation) metals (nickel, copper, titanium) in comparison with coarse-grained and nanocrystalline (electrodeposited nickel) ones are considered. The physical reasons of the essential (by some orders of magnitude) increase of grain boundary permeability in nanostructured state related to coarse-grained metals and bicrystals are discussed. The idea of dispersed strengthening (by oxides and carbides nanoparticles) for the improvement of structure thermostability and the prohibition of softening effects, connected with the simultaneous influence of temperature, loading and diffusion from external environment, is substantiated. As example, the results of original investigations of mechanical properties, structure thermostability and creep, including under the action of grain boundary diffusion fluxes of impurities from external source (coating) are presented. The possibility of superplastic state of nanostructured metals is studied. The features of superplasticity of nanostructured materials compared with fine-grained ones are discussed. This work was supported by INTAS99-1216