(1. 北京有色金屬研究總院， 北京 100088;
2. 中國科學院 金屬研究所 固體原子象開放研究實驗室， 沈陽 110015;
3. 清華大學 核能技術設計研究院， 北京 100084)
摘 要: 使用AEM和HREM研究了添加納米SiC顆粒和同時添加納米SiC顆粒及SiC晶須的兩種Si3N4復合陶瓷材料的微觀組織和斷裂機制。結果表明，部分SiC顆粒分布在Si3N4晶內(nèi)，SiC晶須分布在Si3N4晶粒之間，SiC顆粒和晶須與Si3N4界面之間不存在第二相組織，非晶組織大多分布在Si3N4三叉晶界。斷裂裂紋主要沿晶界和相界面擴展，也可能穿過少數(shù)Si3N4晶粒。當裂紋擴展遇到SiC顆粒和/或SiC晶須時，會發(fā)生轉彎，產(chǎn)生分枝裂紋或微裂紋并在Si3N4晶內(nèi)和Si3N4晶粒的斷裂表面引起晶格畸變，這降低了裂紋擴展能量，從而改善復合陶瓷材料的斷裂強度和斷裂韌性。
關鍵字: Si3N4復合陶瓷； 微觀組織； 裂紋擴展；斷裂機制
（1. General Research Institute for Nonferrous Metals， Beijing 100088， P.R.China;
2. Laboratory of Atomic Imaging of Solid， Institute of Metal Research，The Chinese Academy of Science， Shenyang 110015， P.R.China;
3. Institute of Nuclear Energy Technology, Tsinghua University，Beijing 100084， P.R.China）
Abstract:The microstructure and fracture mechanism of the Si3N4composite ceramics with the addition of nano SiC powder， and nano SiC powder and SiC whisker were studied with AEM and HREM. A part of SiC particles distribute in the interior of Si3N4 grain， the SiC whiskers distribute between the Si3N4 grains and most of the amorphous structure is at the triple grain junction of the Si3N4. There is no second phase in the interface between the SiC particle， whisker and Si3N4. Fracture cracks expand mainly along the interface， also may pass through small amount of Si3N4 grains. Crack expanding direction is changed and branching crack and microcrack is created when the crack expanding meets the SiCparticle and/or whisker. The lattice distortion is produced in the Si3N4andfractured surface layer of S3N4， that will decrease the expanding energy ofcrackand so improve fracture strength and fracture toughness of the composite ceramics.
Key words: Si3N4 composite ceramic； microstructure； crack expanding； fracture mechanism
