Phase-field simulations of spiral growth during directional ternary eutectic solidification

A wide variety of growth patterns has been observed during the directional solidification of three-phase ternary eutectics in multi-component alloys. One hypothesized pattern is the spiral growth of two rod-like phases rotating around each other, which are embedded in a matrix phase. Possible evidence of spiral growth is found experimentally in longitudinal micrographs of the ternary eutectic system Ag–Al–Cu. The phase-field method allows the study of such spatially complex microstructures in order to gain deeper insights into the three-dimensional pattern formation of ternary eutectics. Based on the simulation parameters, which produced a high tilt angle in 2D lamellar growth, determined via systematic parameter studies, multiple spirals are detected in large-scale 3D simulations. Through the presented phase-field simulations, the possibility of the existence of spiral growth in ternary eutectics, reported from experiments, is confirmed.