Abstrait

Role of Atomic Bonds on the Structure and Dynamical Properties of Glass-Forming Metallic Alloy Liquids

Gangopadhyay Anup Kumar

Bulk metallic glasses have attracted much attention over the last two decades because of their superior physical (mechanical, magnetic, to name a few) properties compared to the crystalline counterparts. Like other glasses (oxides, molecular, and polymers), the dynamical properties (viscosity, diffusion coefficient) of the equilibrium and supercooled (metastable liquid below the melting temperature) metallic liquids change by 12-14 orders of magnitude between the melting and glass-transition temperatures. This talk will focus on the dynamical and structural properties of these equilibrium and supercooled liquids measured by our group. Such measurements have been possible by applying a novel electrostatic levitation (ESL) technique that allows contactless measurements to be made on levitated liquid drops under high-vacuum conditions in contamination-free environments. These measurements reveal a deep connection between chemical bonds, liquid structure, and dynamical properties. A particularly interesting result is that the basic mechanism of glass-transition starts in the liquid at a “crossover” temperature far above the glass transition and equilibrium melting temperatures.