Regensburg 2010 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 37: Mechanical Properties II
MM 37.4: Vortrag
Mittwoch, 24. März 2010, 15:30–15:45, H16
In-situ tensile testing of Au nanowires — •Burkhard Roos1, Gunther Richter2, Andreas Sedlmayr3, Reiner Mönig3, and Cynthia A. Volkert1 — 1Institut für Materialphysik, Universität Göttingen — 2Max-Planck-Institut für Metallforschung, Stuttgart — 3Institut für Materialforschung, Karlsruhe Institute of Technology
The increase in strength with decreasing size is a ubiquitous phenomenon in metals. Particularly for free standing samples with dimensions below 100 nm, where dislocation storage is hard to envision, a convincing explanation for the size-dependent strength is missing. The goal of this study is to directly observe dislocations in small volumes, using in-situ TEM during deformation. Single crystal Au nanowires with diameters between 40 and 70 nm have been used. During deformation, crystallographic planar defects appear in the wires, remain fixed as the wire is further deformed, and then may eventually disappear. The defects nucleate homogeneously along the wire length and appear and disappear between camera frames, in less than 50 ms. In-situ tensile testing of the wires in an SEM reveals stresses at failure in the range of 0.4 and 1.5 GPa for wires with diameters between 80 nm and 400 nm. The measured stress-strain response exhibits extensive plastic flow. Post-deformation TEM studies indicate that the defects are nanotwins, which may be formed by the nucleation and motion of partial dislocations. Possible explanations for the dependence of partial dislocation nucleation on wire diameter and stress will be discussed.