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MM: Fachverband Metall- und Materialphysik

MM 26: Poster Session

MM 26.1: Poster

Dienstag, 23. März 2010, 14:45–16:30, Poster C

Ultra-fast diffusion paths in nickel after ECAP — •Gerrit Reglitz, Sergiy Divinski, and Gerhard Wilde — Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany

The concept of so called "non-equilibrium" grain boundaries describes a specific (highly defected) type of grain boundaries in materials, which are produced by severe plastic deformation like ECAP (equal channel angular pressing) or high-pressure torsion. These specific grain boundaries are supposed to have a high density of extrinsic (excess) grain boundary dislocations, and, thus, higher excess grain boundary energy, larger free volume and enhanced diffusivity. To investigate the different types of grain boundaries in Ni after severe plastic deformation by ECAP the self-diffusion experiments were carried out by using the ⁶³Ni isotope in combination with a parallel sectioning technique. The results of these investigations highlight the existence of different types of grain boundaries in this material with completely unequal diffusion characteristics. The kinetic properties are dramatically affected by a preliminary heat treatment. The concept of the "non-equilibrium" grain boundaries in severely deformed materials is critically discussed on the basis of the present data. Support by DFG is gratefully acknowledged.