Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 20: Poster Session I

MM 20.3: Poster

Dienstag, 24. März 2009, 14:45–16:30, P4

Diffusion of Gold in Lead Investigated by Neutron Activation Analysis — •Dirk Böckmann and Nicolaas Stolwijk — Universität Münster, Institut für Materialphysik, 48149 Münster

Fast impurity diffusion in lead has been extensively studied in the 1960s and 1970s. In this context, Pb:Au served as a prototype system. In particular, it was concluded from measurements of Pb self-diffusion enhancement factors in Pb(Au) alloys that the high Au diffusivity cannot be reconciled with the vacancy mechanism. Alternative models interpreted Au transport in terms of fast moving interstitial-type defects including conventional interstitials Au_i, Au_i-vacancy pairs, or Au-Au diplons (dumbbells), however, without providing convincing evidence. Specifically, the role of substitutional Au_s was not sufficiently clarified. Our experiments aim at identifying the mechanism of Au diffusion in Pb by looking closely at the concentration dependence and time evolution of the Au penetration profiles. To this aim, we utilise the suitability of the Pb:Au system for neutron activation analysis (NAA), which allows for the detection of diffusion profiles on an absolute concentration scale. First results are discussed within the framework of interstitial-substitutional diffusion involving Au_i-Au_s exchange with the aid of vacancies.