Observation of distinct atomic relaxation process in a phase-separated metallic glass-forming melt

¹ Department of Physics and Materials Science, City University of Hong Kong - Kowloon Tong, Hong Kong
² Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut - CH-5232 Villigen, PSI, Switzerland
³ State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, 100083, PRC

^(a) smavilac@cityu.edu.hk (corresponding author)

Received: 6 July 2014
Accepted: 22 October 2014

Abstract

We have investigated the atomic relaxation processes in phase-separated alloy melts using quasielastic neutron scattering. Among the three alloy melts studied (i.e., Al₃₀Cu₂₀Sn₅₀, Al₃₀Cu₃₀Sn₄₀ and Y₂₈Ti₂₈Al₂₄Co₂₀), Y₂₈Ti₂₈Al₂₄Co₂₀ is not only a phase-separated melt but also vitrified upon quenching. In this glass-forming melt, we have observed dissimilar relaxation processes in the different phases of the melt: a collective atomic transport process in the phase that exhibits a slow relaxation process and an atomic jump diffusion process in the phase that displays a fast relaxation process. Interestingly, the temperature dependence of the diffusion process in the former phase is a non-Arrhenius process, which is similar to that observed in many fragile glass-forming liquids. In contrast, the temperature dependence of the diffusion process is an Arrhenius process in the later phase, which is a characteristic of non–glass-forming simple liquids.