Stretched and compressed exponentials in the relaxation dynamics of a metallic glass-forming melt

Abstract

The relaxation dynamics of glass-forming systems shows a multitude of features that are absent in normal liquids, such as non-exponential relaxation and a strong temperature-dependence of the relaxation time. Connecting these dynamic properties to the microscopic structure of the system is very challenging because of the presence of the structural disorder. Here we use computer simulations of a metallic glass-former to establish such a connection. By probing the temperature and wave-vector dependence of the intermediate scattering function we find that the relaxation dynamics of the glassy melt is directly related to the local arrangement of icosahedral structures: Isolated icosahedra give rise to a flow-like stretched exponential relaxation whereas clusters of icosahedra lead to a compressed exponential relaxation that is reminiscent to the one found in a solid. Our results show that in metallic glass-formers these two types of relaxation processes can coexist and give rise to a surprisingly complex dynamics, insight that will allow to get a deeper understanding of the outstanding mechanical properties of metallic glasses.

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• The microscopic origins of stretched exponential relaxation in two model glass-forming liquids as probed by simulations in the isoconfigurational ensemble
• Dynamics of disordered quantum systems with two- and three-dimensional tensor networks
• Unveiling the early stage evolution of local atomic structures in the crystallization process of a metallic glass
• Temperature dependence of fast relaxation processes in amorphous materials
• Concentrated suspensions of Brownian beads in water: dynamic heterogeneities trough a simple experimental technique
• Compositional Effects on Structure, Dynamics, Thermodynamic and Mechanical Properties of Zr-Cu-Al alloys
• Graph-Dynamics correspondence in metallic glass-forming liquids
• Griffiths-like region explains the dynamic anomaly in metallic glass-forming liquids
• Global population crisis scenarios predicted by a general nonlinear dynamical model