Atomic caging in multicomponent glass-forming metallic liquids
1 Department of Physics and Materials Science, City University of Hong Kong - Kowloon Tong, Hong Kong
2 Institut Laue-Langevin - BP 156-38042 Grenoble Cedex, France
3 I. Physikalisches Institut, Georg-August-Universitat Goettingen - Goettingen, Germany
Received: 6 February 2015
Accepted: 7 May 2015
We have examined the effect of density on atomic caging in highly dense glass-forming metallic liquids, Ni59.5Nb40.5 and Ni60Nb34.8Sn5.2 using quasielastic neutron scattering. The density of the liquids is unusually high and close to the mode-coupling dynamic transition. The self-correlation function obtained from the QENS data shows stretching and the temperature dependence of the diffusion coefficient shows non-Arrhenius behavior. The mean relaxation time exhibits a non-linear variation with Q2, which is an indicative of a jump diffusion process in these highly dense liquids. We use a simple jump diffusion model to obtain the residence time of Ni atoms in these alloy liquids. The residence time of Ni atoms exhibits a linear dependence with density of these alloy liquids, but shows an abrupt change in the slope approximately at a density of . The present observation indicates that the time at which the atoms are trapped in cages is not a monotonic function of density in hard-sphere–like metallic liquids. Our results indicate the existence of a hidden dynamic transition in glass-forming metallic liquids.
PACS: 61.05.F- – Neutron diffraction and scattering / 61.25.Mv – Liquid metals and alloys / 66.10.cg – Mass diffusion, including self-diffusion, mutual diffusion, tracer diffusion, etc.
© EPLA, 2015