Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 40: Topical Session Bulk Nanostrucured Materials IX - Functional Properties II
MM 40.1: Vortrag
Mittwoch, 28. März 2012, 16:30–16:45, H 0106
Crack formation during dealloying of Au25Cu75 — •Yi Zhong1, Haijun Jin2, and Jörg Weissmüller1,3 — 1Helmholtz Zentrum Geesthacht, Institut für Werkstoffforschung, Werkstoffmechanik, Germany — 2Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China — 3Technische Universität Hamburg-Harburg, Institut für Werkstoffphysik und Technologie, Germany
Alloy corrosion has recently evolved into a method for making nanoporous metal materials. The dealloying process, however, often produces cracks which develop during the concurrent shrinkage. Here, we explore a new strategy to reduce the volume shrinkage while retaining small structure size. The idea is to start with a master alloy (e.g., Au25Cu75) which has smaller lattice spacing than that of the nanoporous product (Au), expecting that the lattice expansion during dealloying will compensate the shrinkage. Most interestingly, unlike the monotonically increase of shrinkage with increasing dealloying potential as observed in Au25Ag75, the copper-based system has a maximum volume shrinkage and the highest density of cracks for dealloying at intermediate potentials. Besides, other pretreatment procedures such as High Pressure Torsion (HPT) or cancellation of recovery heating could also effectively eliminate the cracks which usually propagate along grain boundaries. Therefore, at high dealloying potentials one obtains samples with almost no crack and concurrently smaller structure size, offering a unique opportunity to develop new nanoporous materials with combined high functionality.