Micromechanical analysis of fiber and titanium matrix interface by shear lag method

The model based on fracture mechanics is developed to evaluate the fracture toughness Γ of the fiber/matrix interface in titanium alloys reinforced by SiC monofilaments. Theoretical model for single fiber push-out testing is obtained by shear-lag method. The influences of several key factors (such as the applied stress needed for crack advance, crack length, and interfacial frictional shear stress) are discussed. Using the model, the interfacial toughness of typical composites including Sigma1240/Ti-6-4, SCS-6/Ti-6-4, SCS-6/Timetal 834, SCS-6/Timetal 21s, SCS-6/Ti-24-11 and SCS-6/Ti-15-3 are successfully predicted compared with previous results of these composites. It is verified that the model can reliably predict the interfacial toughness of the titanium matrix composites as well as other metal matrix composites, due to interfacial debonding usually occurs at the bottom face of the samples in such composites.