Regensburg 2007 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 31: Nano structured materials III
MM 31.3: Vortrag
Donnerstag, 29. März 2007, 12:15–12:30, H4
Kinetic properties of internal interfaces in bulk nanostructured materials: radiotracer investigation — •Sergiy Divinski1, Jens Ribbe1, Guido Schmitz1, Juri Estrin2, Yaron Amouyal3, Eugen Rabkin3, and Christian Herzig1 — 1Institut für Materialphysik, University of Münster, Münster, Germany — 2Technische Universität Clausthal, Lehrstuhl für Physikalische Werkstoffkunde, Clausthal-Zellerfeld, Germany — 3Department of Materials Engineering, Technion - Israel Institute of Technology, Haifa, Israel
Nanostructured materials reveal often hierarchical microstructures. In nanocrystalline Fe-Ni alloy produced by powder metallurgy, the nanosized crystallites were found to be clustered in micrometer-large agglomerates, with grain boundaries between nanocrystallites and interfaces between agglomerates revealing fundamentally different kinetic properties. On the other hand, low-angle and high-angle boundaries typically co-exist in material after a severe plastic deformation procedure. Diffusion investigations in such materials demand a special care. A complete and consistent model of diffusion in such a material was elaborated that allows a systematic experimental investigation of self- and solute diffusion in all possible kinetic regimes.
The radiotracer technique is applied for measuring grain boundary diffusion of Ni and Fe in the nanocrystalline Fe-40Ni alloys produced by powder metallurgy and in nanostructured copper prepared by equal channel angular pressing. Typical boundaries between nanograins were found to reveal diffusivities, which are similar to those in their coarse-grained counterparts. The origin of fast diffusion paths is discussed.