Model for the microstructure of oxide eutectics and comparison with experimental observations

The properties of eutectic materials depend strongly on their microstructure. In the case of oxide systems, which exhibit complex microstructures due to the tendencies of the two phases to grow in a faceted manner, conventional eutectic growth theory has been unable to give a detailed account of the process of microstructure formation. We describe here a cellular automata-based model that is able to reproduce key features and general trends observed experimentally in our investigations of oxide eutectic fibers of Al₂O₃/R₃Al₅O₁₂, Al₂O₃/RAlO₃, and related systems, where R is one of a series of rare earth elements. The most important parameters controlling the type of microstructure that develops are the volume fractions and faceting tendencies of the two components. The model provides guidelines for the design of materials with optimized microstructures for particular applications.