Microstructures of directionally solidified Si-TaSi₂ eutectic in situ composite for field emission

The directionally solidified Si-TaSi₂ eutectic in situ composite for field emission was prepared with the electron beam floating zone melting (EBFZM) technique. The microstructure characteristic of Si-TaSi₂ eutectic was systematically investigated. The Si-TaSi₂ eutectic in situ composite, which has high-aligned and uniformly-distributed TaSi₂ fibers in the Si matrix, can be obtained when the solidification rate changes from 0.3 mm/min to 9.0 mm/min. With the increase of the solidification rate, the diameter and the inter-rod spacing of the TaSi₂ fibers are decreased, while the density and the volume fraction of the fibers are increased. The solid/liquid interface is studied by the zero power method as well. When the solidification rate varies from 0.3 mm/min to 5.0 mm/min, the solid/liquid interface morphology has the following evolution processing: planar interface → shallow cell interface → cell interface → planar interface.