Regensburg 2007 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 32: Diffusion and point defects I
MM 32.3: Vortrag
Donnerstag, 29. März 2007, 10:45–11:00, H6
Grain boundary phase transitions in Cu--Bi alloys studied by radiotracer grain boundary diffusion measurements — •Sergiy Divinski1, Henning Edelhoff1, Guido Schmitz1, Christian Herzig1, and Boris Straumal2 — 1Institut für Materialphysik, University of Münster, Münster, Germany — 2Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Russia
Bismuth addition to copper is known to cause a catostrophic embrittlement of the material. Moreover, strong Bi segregation at copper grain boundaries may result in the formation of a liquid-like layer even in the Cu-rich single-phase region of the corresponding bulk phase diagram [1]. Since the grain boundary diffusion depends very sensitively on the boundary structure, the rate of grain boundary diffusion can serve as a unique probe of phase transitions occurring when alloying Cu with Bi.
In the present investigation, grain boundary diffusion and segregation of Bi in polycrystalline Cu--Bi alloys are investigated by the radiotracer serial sectioning technique using the 207Bi isotope. An observed non-Arrhenius temperature dependence of grain boundary diffusion of Bi is discussed in relation to the prewetting phase transition at grain boundaries in the Cu--Bi system.
1. S.V. Divinski, M. Lohmann, Chr. Herzig, et al. Phys. Rev. B. 71 (2005) 104.