Atomic diffusion mechanisms in a binary metallic meltTh. Voigtmann1, A. Meyer1, D. Holland-Moritz1, S. Stüber2, T. Hansen3 and T. Unruh4
1 Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR) 51170 Köln, Germany, EU
2 Physik-Department E13, Technische Universität München - 85747 Garching, Germany, EU
3 Institut Laue-Langevin - BP 156, 38042 Grenoble Cedex 9, France, EU
4 Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München 85747 Garching, Germany, EU
received 21 February 2008; accepted in final form 22 April 2008; published June 2008
published online 27 May 2008
The relation between static structure and dynamics as measured through the diffusion coefficients in viscous multicomponent metallic melts is elucidated by the example of the binary alloy Zr64Ni36, by a combination of neutron-scattering experiments and mode-coupling theory of the glass transition. Comparison with a hard-sphere mixture shows that the relation between the different self diffusion coefficients strongly depends on chemical short-range ordering. For the Zr-Ni example, the theory predicts both diffusivities to be practically identical. The kinetics of concentration fluctuations is dramatically slower than that of self-diffusion, but the overall interdiffusion coefficient is equally large or larger due to a purely thermodynamic prefactor. This result is a general feature for non-demixing dense melts, irrespective of chemical short-range order.
61.25.Mv - Liquid metals and alloys.
61.05.F- - Neutron diffraction and scattering.
64.70.pe - Metallic glasses.
© EPLA 2008