Dresden 2017 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 9: Topical session: Dynamics, relaxation and deformation in deeply supercooled metallic liquids and glasses II - Undercooled Melts
MM 9.3: Vortrag
Montag, 20. März 2017, 12:15–12:30, IFW A
Self-diffusion in liquid gold-silicon investigated using quasi-elastic neutron scattering — •Zach Evenson1, Fan Yang2, Giovanna Simeoni1, and Andreas Meyer2 — 1Maier-Leibnitz Zentrum (MLZ) and Physik Department, Technische Universität München — 2Institute for Materials Physics in Space, German Aerospace Center, Cologne
We use incoherent quasi-elastic neutron scattering to study the atomic dynamics of gold in a eutectic Au81Si19 melt. Despite the glass-forming nature of this system, the gold self-diffusivity displays an Arrhenius behavior with a low activation energy characteristic of simple liquids. At high temperatures, long-range transport of gold atoms is well described by hydrodynamic theory with a simple exponential decay of the self-correlation function. On cooling towards the melting temperature, structural relaxation crosses over to a highly stretched exponential behavior. This suggests the onset of a heterogeneous dynamics, even in the equilibrium melt, and is indicative of a very fragile liquid.