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 9.6: Vortrag
Montag, 20. März 2017, 13:00–13:15, IFW A
Self-diffusion in liquid Al-Ge investigated with quasi-elastic neutron scattering — •Sandro Szabo1,2 and Zachary Evenson1,2 — 1Research Neutron Source FRM II, Garching, Germany — 2Technische Universität München, Munich, Germany
Self-diffusion of atoms in liquid metals can be investigated on an absolute scale with quasi-elastic neutron scattering (QENS). For the Al-Ge system accurate modeling of solidification processes and mass transport in general suffers due to the lack of experimentally determined temperature-dependent diffusion coefficients. We investigate the self-diffusion of Ge in liquid Al-Ge in a wide temperature range at and below the melting point of the respective pure elements. QENS measurements were carried out at the multi-disc chopper time-of-flight spectrometer TOFTOF at the research neutron source Heinz Maier-Leibnitz (FRM II). The QENS results show a standard deviation of the self-diffusion coefficients of only 4 %, which is significantly more precise when compared to classical measurements in long capillaries. In all investigated Al-Ge alloys, the self-diffusivity of Ge follows an Arrhenius behavior over the entire investigated temperature range. At the melting point of pure Ge, the self-diffusivity of Ge in the investigated alloys is higher by some 22-28 % than that of pure Ge. This is in line with existing findings concerning dendrite growth in this system during solidification. Accurate calculations of mass flow, which were previously impeded by the lack of accurate diffusion data, might now be possible.