Hamburg 2001 – scientific programme
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M: Metallphysik
M 33: Postersitzung
M 33.34: Poster
Thursday, March 29, 2001, 15:15–19:00, Foyer S4, CCH
Grain boundary diffusion in nanostructured metals processed by severe plastic deformation: the experimental studies of Ni(Cu) system — •Yurii Kolobov1, Galina Grabovetskaya1, Lubove Puchkarjova1, Maksim Ivanov1, Aleksandr Zhilyaev2, and Ruslan Valiev2 — 1Institute of Strength Physics and Materials Science, 634021, Tomsk, Russia — 2Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, 450000, Ufa, Russia
The copper grain boundary diffusion in nanostructured nickel processed by severe plastic deformation and in nanocrystalline electrodeposited nickel is studied. The results obtained shows high diffusion permeability of nanostructured nickel relative to the same metal in coarse-grained state and in nanocrystalline state after electrodeposition. The experimentally measured activation energy of copper grain boundary diffusion in nanostructured nickel is close to that of free surface diffusion despite the absence of residual porosity in the investigated materials. The discrepancy in the results is explained in terms of a special non-equilibrium state of grain boundaries in severe plastically deformed metals. Non-equilibrium state of grain boundaries is found to be thermally unstable: the long-time room temperature annealings (years of storage) and the short-time annealings at elevated temperatures decrease the grain boundary diffusivity, while the grain size of nanostructured nickel remains unchanged. This work was supported by INTAS99-1216