Abstract
Electromagnetic levitation-based containerless solidification was employed to study the undercooled solidification behavior of the intermetallic compounds CoSi2 and α-FeSi2. In-situ observation was conducted by using a high-speed video recorder. While dendrite growth was observed for CoSi2 regardless of undercooling temperature, the solid-liquid interface of α-FeSi2 significantly changed from faceted to dendritic growth with increasing undercooling. An EBSP study was performed for splat-quenched samples to examine crystallographic texture. The microstructure of CoSi2 featured eight-fold dendrites due to its cubic structure. On the other hand, α-FeSi2 formed six-fold dendrites despite the tetragonal structure of α-FeSi2. Crystallographic and thermodynamic consideration based on the results revealed that the solidification mechanism leading to six-fold symmetry resulted from the three different crystals growing in the ＜110＞ direction of the (111) plane of the metastable cubic phase of γ-FeSi2. The differences between the solidification structures were attributed to different degrees of crystallographic anisotropy.
