Recent progress in understanding high temperature dynamical properties and fragility in metallic liquids, and their connection with atomic structure

The advent of containerless processing techniques has opened the possibility of high quality measurements of equilibrium and metastable liquids. This review focuses on the structure and dynamics of metallic liquids at high temperature. A clear connection between structure, viscosity, and fragility has emerged from recent containerless experiments and molecular dynamics simulation studies. The temperature-dependent changes of liquid structures are smaller for the stronger liquids. The onset of cooperativity usually occurs above the liquidus temperature at a characteristic temperature T A, where the dynamics change from Arrhenius to non-Arrhenius behavior; this is accompanied by the onset of development of more spatially extended structural order in the liquids. Several metrics for fragility, consistent with the traditional fragility parameter, can be developed from the structural and dynamical properties at high temperature. It is becoming increasingly evident from theory and experiments that the fundamental properties that determine fragility are the repulsive part of the interatomic potential and the anharmonicity.