Solidification microstructure of Bridgman-grown Si–TaSi2 eutectic in situ composite

• The microstructure of Si–TaSi2 eutectic was investigated.
• The solid/liquid interface morphology evolvement of Si–TaSi2 was studied.
• A high thermal gradient and liquid metal cool method were used during experiment.
• A homogeneous Si–TaSi2 eutectic with good alignment of TaSi2 fiber was obtained.

Directionally solidified Si–TaSi2 eutectic in situ composite was fabricated by Bridgman growth technique with a high temperature gradient. The microstructure and solid/liquid interface morphology evolvement were systematically investigated. The grown Si–TaSi2 presents typical semiconductor–metal eutectic structure with the TaSi2 regularly and uniformly embedded into Si matrix. As the solidification rate increases from 6 to 150 µm/s, the fiber diameter and eutectic spacing rapidly decrease, whereas the rod density increases. The eutectic spacing and solidification rate obey the relationship of λV0.53=73.7 μm1.53/s0.53. Under the optimal solidification parameter (V=100 µm/s), the fiber diameter is 1.37 μm, average eutectic spacing is 3.83 μm, and rod density is 3×106 rod/cm2, which well satisfy the requirement of Spindt field emission arrays. Furthermore, the solid/liquid interface undergoes an evolvement of planar-shallow cell–cell with the increase of solidification rate.