Si-TaSi_2共晶自生复合场发射材料的定向凝固组织特征  

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

作　　者：崔春娟[1] 张军[1] 苏海军[1] 王红[1] 刘林[1] 傅恒志[1] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,西安710072

出　　处：《无机材料学报》2007年第5期1019-1023,共5页Journal of Inorganic Materials

基　　金：国家自然科学基金(50102004);航空科学基金(04G53048)

摘　　要：采用电子束悬浮区熔装置(EBFZM)制备了Si-TaSi_2共晶自生复合场发射材料,系统地研究了Si-TaSi_+2共晶的定向凝固组织特征.当凝固速率在0.3～9.0mm/min范围内变化时,均可获得Si-TaSi_2共晶自生复合材料,具有高精确取向的TaSi_2纤维在硅连续基体中均匀分布.随着凝固速率的增大,TaSi_2纤维的直径和平均间距减小,面密度和体积分数增大.采用零功率法考察了不同凝固速率时的固-液界面形貌.当凝固速率由0.3mm/min变化到5.0mm/min时,固-液界面经历了平界面→浅胞状界面→胞状界面→平界面的演化过程.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 T aSi2 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 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 0.3mm/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.

关 键 词：定向凝固 电子束悬浮区熔 Si-TaSi2共晶自生复合材料 固-液界面 

分 类 号：TG244[金属学及工艺—铸造] O782[理学—晶体学]