Dresden 2017 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 44: Topical session: Interface-Controlled Microstructures: Mechanical Properties and Mechano-Chemical Coupling - Nano-porous materials

MM 44.2: Vortrag

Mittwoch, 22. März 2017, 12:00–12:15, IFW B

Nanostructure Formation during Dealloying: Theory and Experiment — •Anastasia V. Straßer and Jörg Weißmüller — Hamburg University of Technology

From an empirical point of view, the corrosion conditions for making high quality nanoporous gold samples by dealloying silver-gold solid solutions are well established. The ligament size and the composition of the nanoporous material can be tuned in a reproducible way. Yet, the mechanisms and driving forces of the nanostructure formation are only partly understood. Our understanding of the process relies on the model by Erlebacher and co., that considers a balance between dissolution of the less noble element and surface diffusion of the more noble element, along with nucleation of corrosion on deeper terraces. From an experimental point of view, alloy corrosion has seen STM (scanning tunneling microscope) studies under conditions of passivation. Since bulk dealloying is achieved in the regime where the dissolution outruns the passivation, additional studies of that regime are of high interest. Here we present a direct atomic scale observation of the nanostructure formation during electro- chemical dealloying using in-situ EC-STM (electrochemical scanning tunneling microscope) in the bulk dealloying regime and the results from the corresponding kinetic Monte-Carlo simulation. Series of pictures showing subsequent steps of the structure formation can be correlated to the corrosion rate. Our results from in-situ STM observations and KMC simulation confirm essential suppositions of the current understanding.