Berlin 2018 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 39: Topical session (Symposium EPS and MM): Mechanical Properties at Small Scales

MM 39.1: Vortrag

Mittwoch, 14. März 2018, 15:15–15:30, H 0107

Observation of dislocation interactions with an asymmetric grain boundary in Cu by high frame-rate in-situ TEM — •Nicolas J Peter¹, Vasfi B Özdöl², Colin Ophus², Chrsitian H Liebscher¹, Christoph Kirchlechner¹, Andrew Minor², and Gerhard Dehm¹ — ¹Max-Planck Institut für Eisenforschung GmbH, Düsseldorf, Germany — ²National Center for Electron Microscopy, Berkeley, USA

In-situ TEM nanomechanical testing enables direct visualization of plasticity mechanisms for deformation experiments at small scales. For instance, dislocation source operation and dislocation-dislocation interactions were studied in single crystalline materials to resolve the mechanisms controlling size scaling effects. However, far less studies are focused on unraveling dislocation interactions with interfaces, although understanding these plasticity mechanisms is important for structural materials. In the present study the atomic grain boundary structure of an artificially grown bicrystal was characterized by high-resolution STEM. Nano pillars containing the boundary and from adjacent grains were FIB-machined and tested in-situ inside a TEM equipped with a direct electron detector at a framerate of 400 fps. Fully and partially annealed samples were tested to investigate and reduce the impact of FIB damage that strongly affects the initial dislocation densities. Stable dislocation loop emission and dislocation glide were found to be main plasticity features in the single crystal references. Dislocation absorption, emission and pinning at the grain boundary were observed in the bicrystals and will be discussed in the talk.