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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]

Experimental analysis of single-fiber push-out for SiC fiber-reinforced titanium matrix composites (TMCs) is complicated by the incorporation of large thermal residual stresses, strong chemical bond of the fiber/matrix interface and matrix plastic deformation. This paper summarizes the development of push-out test and the characteristics of push-out test for TMCs such as crack initiating at the bottom face and theoretical analysis of the test. Moreover, it deeply analyzes the progresses of interfacial shear strength and fracture toughness, and work focus is pointed out in future. [ABSTRACT FROM AUTHOR]

An analytical model of the push-out test was developed to predict the interfacial fracture toughness of fiber-reinforced matrix composites. Elastic deformation, thermal residual stress, Poisson effect, and energy dissipation due to interfacial friction are all accounted for in the model based on a fracture mechanics approach and a general solution was derived from the analysis. In addition, finite element analysis was performed to validate the analyti-cal model. The results show that the predictions from the analytical model are in good agreement with the finite element results and experimental data on SiC-reinforced Timet-al834 composites. The effects of residual stress, the friction stress, and the debonding crack length on the interfacial fracture toughness were discussed for a better understanding of the interfacial phenomena in push-out test. The analytical model could be applied to other composite systems as well. [ABSTRACT FROM AUTHOR]