Projects

MEL group focuses on experimental projects related to the formation dynamics of ternary eutectic microstructures with an emphasis on three-phased eutectic patterns and anisotropy. This includes a multidisciplinary experimental research program in the field of solidification science with various impacts in nonlinear physics, metallurgy, materials science, and engineering. Eutectics are naturally grown composites, which are generally solidification-processed. The eutectic microstructures basically consist of nearly periodic arrangements of different crystal phases on the micrometer scale. Because of their low melting points, and the remarkable mechanical, optical, and electrical properties that they owe to their fine microstructures, eutectics are extensively used in metallurgical industries including casting and soldering. In brief, they are solidification-processed high-performance composites. However, a substantial disadvantage of eutectic materials is apparently the uncontrollable variability of their microstructural features on a scale larger than a few tens of a micrometer. Would these microstructures be perfectly periodic on a macroscopic scale, the solid would present extraordinary properties. However, for as yet unknown reasons, eutectic microstructures always exhibit a large density of defects, which destroy the long-range periodicity and reduce the quality of the material.

Solidification is usually studied under directional solidification condition, where a sample is pulled at fixed velocity V, toward the cold side of an imposed unidirectional thermal gradient G. A fundamental property of directional out-of-equilibrium patterns is their multi-stability. They are not subjected to any selection principle, meaning that a continuum of steady patterns, including branches of periodic, symmetric, or symmetry-broken solutions, can be reached under the same solidification conditions, depending on the history through which these conditions were reached. Due to this history dependency, special attention has been paid to the initial stages of eutectic grain formation and to perturbations during growth. Furthermore, the stable steady-state microstructures in thin (2D), thick (3D), and intermediate-thick (quasi-2D) specimens differ substantially.

 

Ongoing Projects

Completed Projects