Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 14: Transport II: Atomic and ionic transport
MM 14.1: Vortrag
Montag, 7. März 2016, 15:45–16:00, H53
Finding ultrafast diffusion in cold-rolled Nickel — •Simon Trubel1, Sergiy Divinski1, Martin Peterlechner1, Christian Simon1, Ehud Almog2, Erhard Schafler3, and Gerhard Wilde1 — 1Institut für Materialphysik, WWU Münster — 2Dep. of Materials Science Engineering, Technion, Haifa — 3Physics of Nanostructured Materials, University of Vienna
Ultrafast diffusion rates have been found in a number of severely plastically deformed (SPD) materials. SPD processing produces an ultrafine grained microstructure while, at certain conditions, is able to modify grain boundaries into a specific (*non equilibrium*) state, at least a fraction of them. This fact was unambiguously shown for nickel of 99.6% purity deformed via ECAP or HPT [1]. At this point, an open question arises - does a critical deformation exist which would correspond to an appearance of such a characteristic state of grain boundaries?
Cold rolled Nickel of the same purity was investigated applying different deformation methods. Partial annealing of cold rolled nickel was found to open diffusion channels with characteristics alike to a porosity network. The formation of these paths was investigated via x-ray diffraction and electron microscopy in combination with calorimetric analysis. Grain boundary self-diffusion was measured applying the 63Ni radioisotope and precision mechanical sectioning. The results are discussed concerning the formation conditions of grain boundaries that would act as ultrafast diffusion paths.
[1] S. V. Divinski, et al. Acta Mater., 59, 1974 (2011).