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MM: Fachverband Metall- und Materialphysik

MM 32: Transport II - Microstructure/Grain boundaries

MM 32.3: Talk

Tuesday, April 1, 2014, 16:15–16:30, IFW B

Diffusion and microstructure in ultrafine grained nickel — •Simon Trubel, Sergiy Divinski, Martin Peterlechner, Gerrit Reglitz, Matthias Wegner, Christian Simon, and Gerhard Wilde — Institut für Materialphysik der Westfälischen Wilhelms-Universität

Ultrafine grained and nanocrystalline materials produced by methods of severe plastic deformation (SPD) have roused a growing interest in science and technology. Previous experiments on Nickel of 99.6% purity show ultra-fast diffusion rates in severely deformed materials created by equal channel angular pressing (ECAP) [1]. Further investigations on pre-annealed ECAP-Nickel were conducted to analyse the nature of its recovery on a microscopic scale. In order to analyse the impact of the strain path and particularly of the hydrostatic component of the applied stress, the material of the same starting ingot has also been applied to high pressure torsion (5 turns, 2 GPa applied pressure). Grain boundary self-diffusion has been analysed by applying the 63Ni radioisotope in combination with high-precision parallel grinding. The results of the diffusion measurements and of measurements by electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) are discussed with respect to modifications of grain boundary structures and characteristics by SPD.