Hamburg 2001 – wissenschaftliches Programm
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M: Metallphysik
M 11: Diffusion und Punktdefekte III
M 11.6: Fachvortrag
Montag, 26. März 2001, 16:30–16:45, S12
Tracer Diffusion Measurements of Ag Segregation in Cu Grain Boundaries in Poly- and Bicrystals — •S. Divinski, M. Lohmann, and Chr. Herzig — Institut für Materialphysik, Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster
Grain boundary (GB) diffusion of 110mAg in Cu poly- and bicrystals was measured within the temperature interval from 452 to 962 K. The combined measurements on Cu polycrystals in conditions of so-called B- and C-type regimes of GB diffusion penetration allowed us to determine the temperature dependence of Ag GB segregation. The segregation enthalpy Hs for Ag in Cu grain boundaries was found to be Hs=−39.5 eV. The initial parts of the present penetration profiles turned out to be of sophysticated nature with a pronounced curvature in the coordinates lnc vs. y6/5 (here c is the concentration and y the depth). This feature is explained via the effect of GB motion during Ag GB penetration. Probable non-linear segregation effects were ruled out for Cu polycrystals due to the extremely small Ag tracer concentration in GBs in this case. The measurements on Cu bycrystals were carried out to avoid the effect of moving boundaries and to provoke non-linear segregation effects. There is a correlation between the distinct curvature of the Ag penetration profiles in Cu bicrystals and the increased absolute concentration of the Ag tracer atoms in the single boundary in such a sample.