Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 6: Mechanical Properties II
MM 6.2: Vortrag
Montag, 26. März 2012, 11:45–12:00, H 0106
Existence of Two Twinning-Mediated Plastic Deformation Modes in Au Nanowhiskers — •Erik Bitzek1, Andreas Sedlmayr2, Daniel S. Gianola3, Gunther Richter4, Reiner Mönig2, and Oliver Kraft2 — 1WW1, Department Werkstoffwissenschaften, Universität Erlangen-Nürnberg — 2Institute for Applied Materials, Karlsruhe Institute of Technology — 3Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, USA — 4Max-Planck-Institut for Intelligent Systems, Stuttgart
Single crystalline metallic nanowhiskers have lately attracted substantial interest due to their special mechanical properties. Here we report on in situ tensile experiments and molecular dynamics (MD) simulations on nominally defect-free single-crystalline Au nanowhiskers in [110] orientation. The room temperature experiments reveal strengths on the order of the ideal strength and plastic strains of up to 12%; a direct result of deformation twinning that is shown to govern the plastic flow. This is in clear contrast to the situation in coarse-grained fcc metals, where twinning is only observed at very low temperatures or at very high strain rates. The in situ and post mortem electron microscopy observations furthermore show two broad classes of deformation morphologies that correlate with distinct stress-strain responses. MD simulations show that the mechanism of twin growth can change from layer-by-layer propagation to parallel and accelerated formation of coalescing nanotwins.