Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 9: Topical session: Dynamics, relaxation and deformation in deeply supercooled metallic liquids and glasses II - Undercooled Melts
MM 9.2: Vortrag
Montag, 20. März 2017, 12:00–12:15, IFW A
Influence of the Chemical Short-Range Order on the Atomic Dynamics in Binary Glass-Forming Melts — •Benedikt Nowak1, Dirk Holland-Moritz1, Fan Yang1, Thomas Voigtmann1, Tobias Kordel1, Thomas Hansen2, and Andreas Meyer1 — 1Institute of Materials Physics in Space, German Aerospace Center (DLR), 51170 Cologne, Germany — 2Institut Laue-Langevin (ILL), 38042 Grenoble, France
The dynamical behaviour of atoms and their short-range order are crucial for understanding the glass-forming ability of metallic melts. To investigate the short-range order (SRO) we measured partial structure factors for the melts of Zr-Ni by combining electrostatic levitation with neutron diffraction and isotopic substitution [1]. Mode coupling theory (MCT) allows us to establish structure-dynamics relations using partial structure factors as an input [2]. The self-diffusion coefficients derived by MCT show the same trends with respect to composition and temperature dependence compared to experimental results.
MCT results highlight that diffusion is partly coupled, exhibiting a distinct composition dependence of the ratio of diffusion coefficients. Compared to a hard-sphere model, we show that such a composition dependent decoupling is due to the strong chemical interaction between Zr and Ni atoms. This can be understood by the fraction of different atomic nearest-neighbour pairs, derived from the measured partial structure factors.
[1] D. Holland-Moritz et al., PRB 79, 064204 (2009) [2] Th. Voigtmann et al., EPL 82, 66001 (2008)