Berlin 2015 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 52: Nanomaterials III: Nanoporous Gold and Phase Transformations
MM 52.1: Vortrag
Donnerstag, 19. März 2015, 11:45–12:00, H 0106
In situ mechanical testing of nanoporous gold: new insights into plasticity of nanostructures — •Nadiia Mameka1, Jürgen Markmann1,2, and Jörg Weissmüller1,2 — 1Helmholtz-Zentrum Geesthacht — 2Technische Universität Hamburg-Harburg
Surface plays a significant role in plasticity of nanoscale objects. This has been well documented by the size-dependent strength in recent studies on nanowires. Our research aims to contribute towards identifying the underlying processes for the observation by employing nanoporous gold (np-Au), as a material with large specific surface area in a network of nanowires or nanoligaments. The millimeter-seized np-Au samples were tested in situ in compression under potentiostatic control in aqueous electrolytes. The amount of the surface area was tuned by structural coarsening, while the state of the surface was controlled by application of an electrical potential E.
The electrode polarization of the Au-electrolyte interface results in an effective strengthening of np-Au by negative charging and specific adsorption at the surface. The overall flow stress σF as well as its potential-induced changes Δ σF / Δ E scale with the ligament size. Remarkably, when normalized by the actual stress, the flow stress-potential coupling parameter Δ σF / Δ E exhibits no size-dependence. This finding implies an important link between phenomena responsible for strengthening by electric potentials and strengthening by structural size. In this respect possible relevant mechanisms that control the plastic deformation will be discussed.