Atomic dynamics in binary Zr-Cu liquids

¹ Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR) 51170 Köln, Germany
² Heinz Maier-Leibnitz Zentrum (MLZ) and Physics Department, Technische Universität München Lichtenbergstr. 1, 85748 Garching, Germany

^(a) fan.yang@dlr.de

Received: 3 July 2014
Accepted: 27 July 2014

Abstract

We studied Cu self-dynamics and liquid density of Zr_66.7Cu_33.3, Zr_35.5Cu_64.5, Zr₃₆Cu₆₄, and Zr_38.2Cu_61.8 liquids using a combination of containerless processing techniques and quasielastic neutron scattering. We show that the composition dependence of the Cu self-dynamics is qualitatively controlled by the liquid packing density. It is hence monotonic within a narrow composition range and not sensitive to small composition variations. Similarly, replacing Cu by Ni results in a slower atomic dynamics in the Zr-Ni liquids, as a consequence of the more dense packing. This is in contrast to the strong composition dependence of the glass-forming behaviour, and the better glass-forming ability of the Zr-Cu over Zr-Ni alloys, which usually favours sluggish liquid dynamics. Thus, in the Zr-Cu case, the glass-forming ability is not directly correlated with liquid dynamics and packing density.