Dresden 2014 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 32: Transport II - Microstructure/Grain boundaries
MM 32.1: Talk
Tuesday, April 1, 2014, 15:45–16:00, IFW B
Wetting and pre-melting phase transitions in Cu(Bi) alloys studied by tracer diffusion — •Henning Edelhoff1, Boris Straumal2, Sergiy Divinski1, and Gerhard Wilde1 — 1Institute of Materials Physics, University of Münster, Münster, Germany — 2Institute of Solid State Physics, Chernogolovka, Russia
It is well known that segregation of impurity elements to grain boundaries (GB) can cause a severe change of the material properties. In some systems, e.g. for the Cu-Bi one, the solute (Bi) excess at Cu GBs leads to grain boundary embrittlement (GBE). Due to increasing amounts of GBs in ultrafine grained and nanocrystalline materials and the potential enrichment of Bi in copper-based materials for microelectronic applications, evoked by the usage of Pb-free solders like Sn-Bi or Sn-Ag-Bi in the chip technology, the understanding of the GBE phenomenon in general and in the Cu(Bi) system particularly is of great importance.
Previously, GB diffusion of Cu and Bi in Cu(Bi) alloys has been investigated and kinetic enhancement corresponding to a pre-wetting phase transition was reported [1]. The question arises how the atomic transport of other solutes is influenced by the phenomenon of GBE in the Cu(Bi) system. In this work the GB diffusion of Ag, as one of the main elements in Pb-free solder alloys, in Cu(Bi) alloys is investigated by the radiotracer technique. The effect of segregation, grain size and GB wetting transition on the kinetics of Ag GB diffusion is discussed.
[1] S.V. Divinski, M. Lohmann, Chr. Herzig, B. Straumal, B. Baretzky, W. Gust, Phys. Rev. B., 71, 104 (2005)