Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 15: Poster Session

MM 15.53: Poster

Montag, 11. März 2013, 18:00–20:00, Poster E

Atomistic simulation of a severe plastic deformation-induced "high-energy" state of grain boundaries — •Lisa Neier1, Sergiy Divinski1, Anantha Padmanabhan2, Martin Peterlechner1, and Gerhard Wilde11Institut für Materialphysik, Westfälische-Wilhelms-Universität, 48149 Münster — 2University of Hyderabad, India

A comparison of microstructures and properties in materials subjected to the later stages of severe plastic deformation or steady-state superplastic flow indicates several unexpected similarities especially with respect to the interface response on the deformation, such as grain boundary (GB) sliding events, which lead to a suppression of dislocation activity. Making use of this idea, we propose to describe the experimentally observed "high-energy" (or "non-equilibrium") state of general high-angle GBs in SPD-processed materials in terms of the concept of shear localization in the interfaces and choosing oblate spheroids of a few atomic diameters size as the basic units of sliding. Atomistic simulations of these special GBs are performed. In this approach, the GB is generated, oblate spheroids are defined, extra free volume is introduced, and the oblate spheroids are sheared by a given amount. After this preparation, the whole simulation box is sheared. The GB energy as a function of the extra free volume is determined and the arrangement of the (extra) free volume in the grain boundary is analyzed. The simulation data are compared with experimentally available HRTEM images via calculation of HRTEM images corresponding to simulated GBs and subsequent geometric phase analysis of the local strain fields.

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