Dresden 2006 – wissenschaftliches Programm
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MM: Metall- und Materialphysik
MM 42: Diffusion II
MM 42.3: Vortrag
Freitag, 31. März 2006, 11:30–11:45, IFW B
Study of Electrochemical Dissolution of Ternary Ag-Au-Dy Alloy — •VISWANATH RAGHAVAN NADAR1, HARALD RÖSNER1, DOMINIK KRAMER1, and JÖRG WEISSMÜLLER1,2 — 1Forschungszentrum Karlsruhe, Institut für Nanotechnologie, Karlsruhe, Germany — 2Technische Physik, Universität des Saarlandes, Saarbrücken, Germany
We report results for the microstructure evolution during the dealloying of Ag-Au-Dy ternary alloys. The nature of the transport path during the formation of the nanoporous structure in dealloyed Ag-Au is the subject of current research, and in particular the role of bulk diffusion is debated. By exploring the dealloying of a supersaturated solid solution we aim at verifying the suggestion of an enhanced bulk diffusion coefficient due to excess vacancy injection at the dissolution front: the conceivable formation of solvent-rich precipitates in the alloy ahead of the dissolution front would support an enhanced diffusivity. In fact, the results for Ag-Au-Dy supersaturated in the rare earth Dy are not incompatible with this expectation. The suction-cast specimens were selectively dealloyed in 1M HClO4 solution at different durations and investigated at each stages ex-situ using TEM, XRD and AC magnetometer. The material is two phase in its initial state, with a Ag-rich ternary solid solution as the majority phase and a Au- and Dy-rich ternary intermetallic as the minority phase. During dealloying a repartitioning of Dy between the solid solution and the ternary compound is found, a process which may suggest accelerated bulk transport, since Dy would oxidize immediately when brought in contact with the electrolyte.