Transmission electron microscopy on Hf- and Ta-carbides sintered with TaSi2
Transmission electron microscopy on Hf- and Ta-carbides sintered with TaSi2
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DOI：
10.1016/j.jeurceramsoc.2011.07.003
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发表时间：
2011-12
影响因子：
5.7
通讯作者：
L. Silvestroni;D. Sciti
中科院分区：
文献类型：
--
作者：
L. Silvestroni;D. Sciti
采用X射线衍射、扫描电镜和透射电镜对含15vol%TaSi2的Hf-和Ta-碳化物热压烧结体的显微组织进行了表征，以探讨其致密化机理。碳化物的显微组织由方形晶粒和亚晶粒组成，内部由原始MC晶粒组成，外部由外延生长的（M，Ta）C固溶体组成，这两个区域之间的成分失配和热膨胀系数的差异由45°晶界和位错协调。在三重结处，检测到Ta_5Si_3和Ta_4.8Si_3C_（0.3）以及Hf杂质。观察到晶界是干净的。随后将含有TaSi 2的复合材料的微观结构与添加相同量的MoSi 2烧结的复合材料进行比较。
The microstructure of hot pressed Hf- and Ta-carbides with 15vol% of TaSi2was characterized by X-ray diffraction, scanning and transmission electron microscopy in order to investigate the densification mechanisms. The microstructure of the carbides was constituted by squared grains and subgrains were recognizable only by transmission electron microscopy: the inner part was constituted by the original MC grain and the outer area by a (M,Ta)C solid solution which grew epitaxially on it. The compositional misfit and the difference of the coefficients of thermal expansion between the two regions were accommodated by 45° grain boundaries and dislocations. At the triple junctions, Ta5Si3and Ta4.8Si3C0.3, with Hf impurities were detected. The grain boundaries were observed to be clean. The microstructure of the composites containing TaSi2was subsequently compared to composites sintered with addition of the same amount of MoSi2.