Measurement and alalysis of micro-stress distribution in all oxide composite with structural change of matrix

采用高速扫描型荧光显微镜测量了Al_2O_3纤维增强Al_2O_3基复合材料在纤维-基体界面附近的微应力分布。成功地获得了复合材料界面附近的二维应力图。应力分布表明，应力场表现为(i)纤维与基体热失配应力、（ii） Al_2O_3各向异性应力和（iii）外加应力的叠加。对不同晶粒尺寸Al_2O_3/Al_2O_3复合材料断裂试验中的微应力分布进行了原位测量。裂纹扩展的界面应力和起裂应力与Al_2O_3基体的晶粒尺寸有关。对于给定的材料体系，获得了优化基体结构（特别是晶粒尺寸）以最大化抗断裂性能的指导。

Micro-stress distribution near fiber-matrix interface of Al_2O_3 fiber-reinforced Al_2O_3 matrix composite has been measured by a high-speed scanning type fluorescence microscope. Two-dimensional stress mapping near the interface of the composite was successfully obtained. The stress distribution indicated that the stress field was expressed as superimpose of (i) stress by thermal mismatch between fiber and matrix, (ii) stress by anisotropy of Al_2O_3 and (iii) stress by applied stress. In situ measurement of micro-stress distribution in fracture test of Al_2O_3/Al_2O_3 composites with different grain sizes was performed. The interfacial stress and the initiation stress for the crack propagation depended on the grain size of the Al_2O_3 matrix. The guide for optimizing matrix structure (particularly grain size) to maximize the fracture resistance was obtained for a given material system.