Fatigue behaviors of C/Mo double-coated SiC fiber-reinforced Ti6Al4V composites with varied interfacial microstructure.

Fatigue crack propagation behaviors of the as-prepared and thermally exposed (700 °C/196 h, 800 °C/196 h) C/Mo double-coated SiC fiber-reinforced Ti6Al4V composites were investigated. The results show that interfacial microstructure evolution has significant effect on fatigue crack propagation behaviors. As for the as-prepared and 700 °C/196-h thermally exposed composites, fiber-bridging accompanied with interfacial debonding can decrease the crack growth rate significantly, while the latter one has lower crack growth rate at the early fatigue crack propagation stage, as the diffusion of Mo atoms makes the matrix close to the interface have more ductileβ-Ti. However, fiber-bridging phenomena disappeared with the altered interface in the composite after 800 °C/196-h thermal exposure. Fatigue fracture analysis further reveals that multistep deflections of crack in interface contribute to the improvement of interface toughness. The formation of ductileβ-Ti layer resulted from the diffusion of Mo atoms is beneficial to blunt the crack tip. [ABSTRACT FROM AUTHOR]