Low-cycle fatigue behavior and damage progression of a fiber reinforced titanium matrix composite

The low-cycle fatigue behavior and damage progression of a SiC fiber reinforced Ti–6Al–2Sn–4Zr–2Mo-0.1Si matrix composite was investigated systematically. The fatigue life increased from 4 to 52388 cycles when the maximum stress decreased from 1500 MPa to 1100 MPa. The modulus calculated from the stress-strain response exhibited little variation for all the specimens during the fatigue process. Fractographic observations showed that the fatigue cracks initiated internally and propagated preferentially in the internal sputtered matrix instead of the unreinforced matrix in the external layer for the cylindrical specimen. The proportion of the fatigue region in the fracture surface increased as the applied stress level decreased. The internally-progressed damage, especially breaks of bridging fibers, was well characterized in situ by the acoustic emission system. © 2020 The Authors