Dresden 2009 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 23: Topical Session Heterogeneous Nucleation and Initial Evolution of Microstructure - Poster

MM 23.6: Poster

Tuesday, March 24, 2009, 14:45–16:30, P4

Binary Mixtures of Charged Colloidal Suspensions and their Role as Model Systems — •Nina J. Lorenz¹, Patrick Wette², Thomas Palberg¹, Hans Joachim Schoepe¹, and Tsuneo Okubo³ — ¹Institute of Physics, University Mainz, Germany — ²Institute for Raumsimulation DLR Cologne, Germany — ³Cooperative Research Centre, Yamagata University, Yonezawa, Japan,

We investigate colloidal charged sphere mixtures in aqueous dispersion, exploring their possible use as conveniently accessible models for metallic binary mixtures. Using static and dynamic light scattering, torsional resonance spectroscopy and optical microscopy we investigate the structure, elasticity and solidification kinetics of mixtures with different size- and charge ratio. We find a rich variety of binary phase diagrams similar to those in metal systems including spindle, azeotropic and eutectic types [1, 2]. Eutectic-like behaviour is found for large asymmetries in the mixtures and demixing confirmed by diffusion experiments. The independent solidification of the segregating components is monitored with time resolved elasticity measurements. In addition we find interesting morphologies not unlike those in metal eutectics, but still considerably altered due to the different system dynamics. [1] T. Palberg, N. Lorenz, H.J. Schoepe, P. Wette, I. Klassen, D. Holland-Moritz, D.M. Herlach, in D. Herlach et. al.: Solidification in multicomponent melts, VCH-Wiley Weinheim, 2008, pp. 185-212, Solidification experiments in single component and binary colloidal melts [2] N. Lorenz, J.Liu, T. Palberg: Phase behaviour of binary mixtures of colloidal charged spheres, Colloids Surf. A 319, 109 (2008)