The Dynamics of Coarsening in Liquid-Solid Mixtures: Facets and Curvature Flow

John Gibbs, Northwestern University

The focus of this work is to quantify the coarsening behavior of two-phase materials; specifically, to measure the rate of change of curvature and to characterize the coarsening process in systems in which the interfaces are faceted. A family of binary Al-Cu alloys are used to study the curvature evolution, and Al-Si alloys are used to study dynamics in a faceted interface system; to create a two-phase state, the materials are heated until a mixture of liquid and solid phases coexist. The primary tool used to characterize these materials is X-ray computed tomography because it enables in-situ, 3-D measurements of interfacial locations. Being a non-destructive test means that the interface curvature (which drives coarsening) and resulting motion can be tracked over time to fully characterize the cause and effect relationships of coarsening dynamic. The goals of this project are to use the curvature measurements to help formulate and validate equations that describe coarsening dynamics of diffusion-limited materials and to make initial observations of faceted-interface materials.

Abstract Author(s): John W. Gibbs & Peter W. Voorhees