Control of lamellar eutectic orientation via template-directed solidification

Template-directed solidification of eutectics has shown promise in the synthesis of functional mesostructured materials. While eutectic systems form microstructures with a high degree of order, the structure can be further dictated by the template that introduces additional interfaces and modulates mass and heat transfer. In this study, AgCl-KCl lamellar eutectic was solidified within lithographically fabricated pillar templates and the results were compared with phase-field simulations. It was observed that the boundary effects from the template drive changes in the orientation of lamellae within the template. The system's selection of lamellar orientation was dictated by the minimum undercooling condition. We studied a range of ratios between the eutectic lamellar spacing and the pillar geometry, and determined the parameter space in which the template drives the eutectic to change its orientation. The ability to understand and deterministically control the orientation of a eutectic through use of a template is crucial to realization of specific eutectic mesostructures for photonic, heat-transfer, interfacial engineering, sensing, and energy storage applications.