陶瓷基体中不连续细长相的增韧机制与方位角效应

Reinforcing Mechanisms and Their Orientation Effect of Discontinuous Elongated Reinforcements in Ceramic Matrix

对不连续细长相在陶瓷基体中的增韧机制及其方位角效应进行了实验观察。在此基础上，建立了裂纹面桥联机制与细长相方位角之间关系的分析模型。结果表明：裂纹尖端后方裂纹面桥联作用主要受细长相架桥、细长相拔出和细长相根部基体破坏三种机制的支配；拔出机制只有当细长相轴向与裂纹面法线方向的夹角足够小时才可能发生；对于中等大小的夹角，架桥作用可以持续到细长相破断；当夹角足够大时，细长相根部基体发生破坏。

The reinforcing mechanisms and their orientation effect of discontinuous elongated reinforcements in ceramic matrix are observed by SEM for Si3N4 matrix composites. On this basis, a mechanical model is established for analyzing the orientation dependence of the crack-bridging mechanisms. The results indicate that the crack-bridging effect is mainly controlled by the three mechanisms: the elongated phase bridging,the elongated phase pullout, and the matrix damage at the root of elongated phase; only when the included angle between the axis direction of elongated phase and the normal direction of the crack plane is small, can the elongated phase be pulled out; for midding angles, the bridging effect can be continued until the elongated phase breaking; when the angle is large, the matrix damage occurs, and then the bridging effect is cut off.