Interfacial bond strength and fracture energy at room and elevated temperature in titanium matrix composites (SCS-6/Timetal 834)

Push-out experiments in the temperature range from room temperature to 530°C have been performed. On the basis of the measured maximum load to break the fibre/matrix bond and the load to overcome frictional shear stresses finite element analyses are performed to derive an interfacial shear strength and interfacial fracture energy for the different test temperatures. The thus derived material properties decrease at increasing test temperature. In the analyses the in-homogeneity of the (shear) stress distribution plays an important role for the thermal as well as for the mechanical stress distribution. Although only the energy concept requires principally an initial debond length, it is shown that without an initial defect the shear strength concept leads to unrealistic results. The results presented are valid if it can be accepted that during specimen preparation an initial debonded zone of 12-18 μm at the surface is introduced.