Regensburg 2019 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 25: Poster Session II

CPP 25.3: Poster

Dienstag, 2. April 2019, 14:00–16:00, Poster B1

Camphor/Succinonitrile -- a model system for metal alloys subjectedto a temperature gradient — •Felix Sommer1, Marcel Schraml1, Bastian Pur1, Werner Köhler1, Gerhard Zimmermann2, and Laszlo Sturz21Physikalisches Institut, Universität Bayreuth — 2Access e.V. Aachen

Hypoeutectic Succinonitrile/Camphor alloys serve as model systems for the solidification of binary metal alloys. The development of the solidification patterns strongly depend on the solute transport at the solid-liquid interface, which is often assumed to be diffusional, even in a thermal gradient. Under such nonequilibrium conditions in a thermal gradient, diffusive flows are characterized by complex cross-coupling phenomena between concentration and temperature gradients. As a consequence, the local composition can significantly shift away from its initial concentration, resulting in unexpected solidification patterns. In order to better understand these mechanisms, we have studied diffusion and thermodiffusion of camphor/succinonitrile binary mixtures around the eutectic composition in the liquid phase. We have been able to determine diffusion, thermodiffusion and Soret coefficients by means of optical beam deflection and photon correlation spectroscopy. For the evaluation of the experiments, precise measurements of the optical contrast factors were performed. Our results prove a significant cross coupling between temperature and composition.

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