Large scale phase-field simulations of directional ternary eutectic solidification

Pattern formation in ternary eutectic microstructures is difficult to predict because of the complex interactions between diffusion and surface energies, as well as the large number of possible configurations which three phases can assume. The silver–aluminum–copper (Ag–Al–Cu) ternary eutectic is of particular interest to researchers, but its study is complicated by an unusually large solubility change. Due to this change, it is difficult to observe the patterns that form during the solid–liquid phase transition experimentally. This causes significant differences between the structure that forms during solidification and what is observed after traditional directional solidification processing. In order to model the solidification behavior and pattern formation in representative volume elements, large scale phase-field simulations are employed. Two different parameter sets are used. The first set uses the phase fractions and compositions of the as-solidified structure. The other used phase fractions found at lower temperatures in order to be comparable to experimental microstructures available in the literature. The second set of simulation results is compared quantitatively to experimental micrographs and found to be in good agreement. The predicted three-dimensional microstructures for the as-solidified structure are presented.