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Plenarvortrag Mi., 16:30–17:00 M-PV2
Structure and Dynamics of Undercooled Metallic Melts
Andreas Meyer 1
1 Deutsches Zentrum für Luft und Raumfahrt, Institut für Raumsimulation, 51170 Köln
We investigate the atomic motion in multicomponent melts on a Ni-, Zr-, Ti- and Albasis
with quasielastic neutron scattering in order to clarify the microscopic transport
mechanisms. The high-resolution energy and momentum information emerging from
quasielastic neutron scattering experiments allows to study the interplay between structure,
viscous flow and atomic diffusion. Our results reveal non-trivial mechanisms of
mass transport in these systems. However, in spite of a pronounced chemical short
range order on intermediate length scales, the mass transport in these systems is dominated
by packing effects like in other hard-sphere like liquids.
In a recent experiment we succeeded to process liquid droplets of 6-8 mm in diameter
in an electromagnetic levitation device on the neutron time-of-flight spectrometer
ToF-ToF of the FRM-II [1]. This containerless processing of the samples not only
gives access to experiments on high temperature and chemically reactive liquids, but
also allows for undercooling the samples several 100 K below their liquidus. The undercooling
and the corresponding slowing down of dynamics allows for a stringent test
of theoretical descriptions of dynamics in liquid matter.
[1] A. Meyer, S. Stüber, D. Holland-Moritz, O. Heinen, T. Unruh, to be published