Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 17: Poster Session
MM 17.20: Poster
Montag, 26. März 2012, 17:00–19:00, Poster B
Atomistic simulation of severe plastic deformation-induced "high-energy" state of grain boundaries — •Lisa Neier1, Sergiy Divinsky1, Anatha Padmanabhan2, and Gerhard Wilde1 — 1Institut für Materialphysik, Universität Münster, Münster — 2University of Hyderabad, India
A comparison of microstructures, properties and transport kinetics in materials subjected to the last stages of severe plastic deformation (SPD) or steady-state superplastic flow indicates a number of unexpected similarities especially with respect to the interface response on the deformation, such as formation of an interface hierarchy, deformation localization, grain boundary sliding events when dislocation activities are suppressed, etc. Making use of this idea, we propose to describe the experimentally observed "high-energy" (or "non-equilibrium") state of general high-angle grain boundaries in SPD-processed materials in terms of the concept of shear localization in the interfaces and choosing oblate spheroids as basic units of sliding.
"Non-equilibrium" grain boundaries in Cu are simulated. The individual simulation steps include generation of a grain boundary; determination of regions corresponding to the oblate spheroids on the boundary plane; introduction of an extra free volume (a fraction of atoms in the oblate spheroids is simply deleted) and shearing of the oblate spheroids by a given amount. By energy minimization, a high-energy state of the grain boundary is found which corresponds to about 4% additional free volume and 0.1 unit shear. The subsequent response of such an interface on the applied shear is analyzed.