Separation mechanism of TiSi2 crystals from a Ti-Si eutectic alloy via directional solidification

TiSi2 crystals were successfully obtained via directional solidification separation of a Ti-Si eutectic alloy under electromagnetic stirring. In order to explore the separation mechanism in detail, experiments were conducted using a high-frequency induction furnace at different downward speeds and by varying the thermal parameters of directional solidification (i.e., temperature gradient, cooling rate, and growth rate) of a crucible loaded with Ti-75 wt%Si melt. The results demonstrate that electromagnetic stirring and the thermal parameters of directional solidification played different roles in the crystal separation of TiSi2. While the electromagnetic stirring enhanced the migration of TiSi2 crystals in the Ti-Si melt and mushy zone, low downward rates (5 μm/s) were beneficial for the growth of TiSi2 crystals and reduced the mushy zone area. Therefore, a low downward rate combined with electromagnetic stirring is favorable for the enrichment of TiSi2 crystals.