Damage accumulation during high temperature fatigue of Ti/SiCf metal matrix composites under different stress amplitudes

The damage mechanisms and load redistribution taking place under high temperature (350 °C), cycle fatigue (HCF) of TC17 titanium alloy/unidirectional SiC fibre composites have been investigated in situ using synchrotron X-ray computed tomography (CT) diffraction (XRD) two stress amplitudes. three-dimensional morphology the crack fractures has mapped by CT. At low amplitude, stable growth occurs with matrix deflecting 50-100 µm height as it bypasses bridging fibres. higher loading to peak led a burst giving rise rapid growth. Many occurred 50-300 above/below plane during growth, contrary that stage, leading extensive pull-out on fracture surface. changes loading, interfacial stress, extent fibre-matrix debonding vicinity over after XRD. fibre/matrix sliding extends up 600 (in stable-growth zone) or 700 rapid-growth either side plane. direction shear reverses cycle, maximum frictional reaching ~55 MPa both regimes. In accordance previous studies, is possible degradation strength at elevated responsible for bursts amplitude.