In-Situ Observation Of Solidification Behaviour From Undercooled alpha-Fe2Si5 Melt Using An Electromagnetic Levitator

Fe2Si5 melts were deeply undercooled using an electromagnetic levitator and their growth velocity was measured by a high speed video camera in order to reveal the solidification behavior of intermetallic compounds. The growth morphology drastically changed depending on the under-cooling, DeltaT. The faceted planes were observed on the surface of the sample at DeltaT 5 ~ 50K. With increasing undercoolings, the morphology changed into typical facet dendrite. Especially at the high undercooling of DeltaT -100K, a dendrite of hexagonal symmetry clearly formed. The growth velocities were measured as a function of undercooling and compared with the classical dendritic growth theory. The interfacial kinetics is thought to be crucial for the solidification of Fe2Si5.