The present proposal concerns a multidisciplinary experimental research program in the field of solidification science with various impacts in nonlinear physics, metallurgy, materials science, and engineering. The problem studied is the formation dynamics of multiphase microstructures in eutectics, which are naturally grown composites that are generally solidification-processed. These microstructures basically consist of nearly periodic arrangements of different crystal phases on the micrometer scale. Because of their low and constant melting temperatures, 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. However, a substantial challenge for eutectic materials is to control the variability of the microstructure on a scale larger than a few tens of a micrometer. If the microstructures were 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.This proposal addresses this problem using real-time experiments and numerical simulations to examine the formation dynamics of Nonvariant EUtectic SOLidification (NEUSOL) microstructures with an emphasis on dynamics of three-phased eutectic patterns and anisotropy effects.Control of the microstructure is essential to obtain a homogeneous structure, which is needed to yield consistent properties and reproducible materials. This project will provide a clear improvement of our fundamental understanding of solidification pattern formation in ternary eutectics and have strong impact on the international community by opening the way to the control, and hence to the optimization of the properties of solidification-processed composite materials.