Dresden 2009 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 48: Nanostructured Materials IV

MM 48.1: Talk

Friday, March 27, 2009, 10:15–10:30, IFW B

’Non-Equilibrium’ Grain Boundaries in Severely Deformed Materials: Myths vs. Reality — •Sergiy Divinski and Gerhard Wilde — Institut für Materialphysik, Universität Münster, Germany

Recent results on radiotracer diffusion in nanostructured and ultrafine grained materials produced by severe plastic deformation are reviewed. The data reveal a strong hierarchy of short-circuit diffusion paths in these materials – the ultra-fast diffusion paths (the top level of the hierarchy) turn out to be embedded in a network of relatively slower diffusion paths (the bottom level). The ’slow’ paths are shown to represent the relaxed high-angle grain boundaries, which are the fastest short-circuit diffusion paths in annealed coarse-grained counterparts. The nature and origin of the ultra fast paths is examined and discussed in relation to the so-called "non-equilibrium" grain boundaries in severely deformed materials.