Interfacial debonding and transverse properties of a Tiβ21s/SCS-6 composite

The transverse tensile and fatigue properties of a Tiβ21s/SCS-6 composite have been tested in the as-received condition, and after ageing at a temperature of 520°C for 8 hours. Interfacial debonding during the transverse tension has been defined using a combination of techniques of acoustic emission measurements, surface replication, repeated loading and unloading schedules, elevated temperature tests, and a theoretical analysis based on Eshelby's equivalent inclusion method. An intrinsic interfacial strength is deduced from experimental measurements, and this conclusion is supported by theoretical analysis and the trend of transverse behaviour with test temperature. The transverse fatigue crack growth resistance is dominated by that of the matrix, while the interfacial properties have a marked effect on the lives of fatigue crack initiation and short crack growth when the applied stress is lower than a certain level. Finite element calculations have been used to rationalise such observations.