Microstructures of Directionally Solidified Si-TaSi_2 Eutectic in situ Composite for Field Emission

The directionally solidified Si-TaSi_2 eutectic in situ composite for field emission was pre- pared with the electron beam floating zone melting (EBFZM) technique.The microstructure charac- teristic of Si-TaSi_2 eutectic was systematically investigated.The Si-TaSi_2 eutectic in situ composite, which has high-aligned and uniformly-distributed WaSi_2 fibers in the Si matrix,can be obtained when the solidification rate changes from 0.3mm/min to 9.0mm/min.With the increase of the solidification rate,the diameter and the inter-rod spacing of the TaSi_2 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 0.3mm/min to 5.0 mm/min,the solid/liquid in- terface morphology has the following evolution processing:planar interface→shallow cell interface→cell interface→planar interface.