TiC_p/W复合材料的断裂行为

FRACTURE BEHAVIOR OF TiC p/W COMPOSITES

利用扫描电镜观察了含３０ ％ ＴｉＣ 颗粒（ 体积分数） 的钨基复合材料在室温和高温的微观断裂过程， 讨论了裂纹萌生、扩展条件及其影响因素。室温下的断裂过程受控于裂纹萌生阶段， 相应的应力－ 挠度曲线表现为线性， ＴｉＣ 颗粒和Ｗ 基体在微观上都呈现脆性断裂。高温下的断裂则存在一个亚稳态的初始裂纹长大和合并过程， 使应力－ 挠度曲线呈现出非线性， 在微观上ＴｉＣ 颗粒呈现脆性断裂，Ｗ 基体呈现韧性撕裂。

A scanning electron microscope(SEM) was employed to investigate the microprocess of fracture at both room temperature and high temperature in tungsten matrix composites containing 30%(in volume) TiC particles. The condition of crack initiating, propagating and the effecting factors have been discussed. The fracture of the composites at room temperature, which was determined by the crack initiating, was brittle, and the corresponding stress deflection curve was linear. SEM observation on the crack path and fracture surface revealed the brittle fracture of both TiC and W matrix. There was a growth and coalescence of the initial substable cracks in the fracture at high temperature, and the stress deflection curves displayed nonlinear characteristics. The rupture of TiC was brittle and the failure of W matrix was a ductile bearing. The strengthening mechanisms at both room temperature and high temperautre were proposed.