Berlin 2012 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 33: Topical Session Theory meets Experiment II - Nanocomposites and Microstructure

MM 33.3: Talk

Wednesday, March 28, 2012, 12:15–12:30, TC 006

Deformation mechanisms of twinned Au-nanoparticles under compression: Experiments and Simulation — •Andreas Kelling¹, Cynthia A. Volkert¹, Wolfram Nöhring², and Erik Bitzek² — ¹Institut für Materialphysik, Universität Göttingen, D-37077 Göttingen — ²Lehrstuhl WWI: Allgemeine Werkstoffeigenschaften, Universität Erlangen-Nürnberg, D-91058 Erlangen

The plastic deformation of nanoscale metallic specimens has recently attracted a lot of interest due to the reported changes of deformation mechanisms with reduced size. Here, we present compression experiments and atomistic simulations of gold nanoparticles to study dislocation processes and -storage in nanosized volumes. The particles are 80 and 250 nm in size and have faceted self-similar triangular shapes. They contain a twin boundary parallel to their upper and lower (111) surfaces. The particles are compressed along the [111] axis using a nanoindenter with a flat punch tip up to a strain of 50%. No dislocations were observed before deformation. Post-mortem TEM-analysis of both particle sizes reveals the storage of full dislocations. No difference in dislocation type is observed for the two different particle sizes. Molecular Dynamics simulations of Au particles with the same shapes were performed using different types of indenters and boundary conditions. The processes of dislocation nucleation, reactions, cross-slip and interactions with the twin boundary are studied in detail and analyzed in terms of the overall stress state. Comparison with the experimental microstructure allows us to draw conclusions about the dominant dislocation processes during the deformation of the particles.