Regensburg 2013 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 36: Topical Session: TEM-Symposium - Structure-Property / In-Situ II
MM 36.3: Talk
Wednesday, March 13, 2013, 12:15–12:30, H25
In situ TEM deformation of Au nanowires — •Burkhard Roos1, Bahne Kapelle1, Torben Erichsen1, Gunther Richter2, and Cynthia A. Volkert1 — 1Institut für Materialphysik, Universität Göttingen — 2Max-Planck-Institut für Intelligente Systeme, Stuttgart
Increasing strength with decreasing size is a common phenomenon in metals, and is often explained in terms of dislocation pile-ups and interactions. However, for free standing samples with dimensions below 150 nm, dislocation storage is hard to envision and a convincing explanation for the high strength is still 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 250 nm have been used for this study. Stacking faults appear during tensile deformation as a result of the nucleation and motion of partial dislocations. The stacking faults form homogenously along the wire length on {111} planes. The stacking faults thicken into nanotwins through the sequential activation of partial dislocations on neighbouring (111) planes. Post-deformation TEM studies show that fracture occurs at a nanotwin. In contrast bending of identical wires leads to the nucleation of full dislocations. A quantitative model based on classical nucleation theory will be presented which explains the observed difference in deformation mode. Implications for different materials and loading geometries will be discussed.