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

Wang, Ying and Xu, Xu and Zhao, Wenxia and Li, Nan and McDonald, Samuel A. and Chai, Yuan and Atkinson, Michael and Dobson, Katherine J. and Michalik, Stefan and Fan, Yingwei and Withers, Philip J. and Zhou, Xiaorong and Burnett, Timothy L. (2021) Damage accumulation during high temperature fatigue of Ti/SiCf metal matrix composites under different stress amplitudes. Other. arXiv.org, Ithaca, NY. (https://doi.org/10.48550/arXiv.2102.13575)

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The damage mechanisms and load redistribution of high strength TC17 titanium alloy/unidirectional SiC fibre composite (fibre diameter = 100 µm) under high temperature (350 °C) fatigue cycling have been investigated in situ using synchrotron X-ray computed tomography (CT) and X-ray diffraction (XRD) for high cycle fatigue (HCF) under different stress amplitudes. The three-dimensional morphology of the crack and fibre fractures has been mapped by CT. During stable growth, matrix cracking dominates with the crack deflecting (by 50-100 µm in height) when bypassing bridging fibres. A small number of bridging fibres have fractured close to the matrix crack plane especially under relatively high stress amplitude cycling. Loading to the peak stress led to rapid crack growth accompanied by a burst of fibre fractures. Many of the fibre fractures occurred 50-300 µm from the matrix crack plane during rapid growth, in contrast to that in the stable growth stage, leading to extensive fibre pull-out on the fracture surface. The changes in fibre loading, interfacial stress, and the extent of fibre-matrix debonding in the vicinity of the crack have been mapped for the fatigue cycle and after the rapid growth by high spatial resolution XRD. The fibre/matrix interfacial sliding extends up to 600 µm (in the stable growth zone) or 700 µm (in the rapid growth zone) either side of the crack plane. The direction of interfacial shear stress reverses with the loading cycle, with the maximum frictional sliding stress reaching ~55 MPa in both the stable growth and rapid growth regimes.


Wang, Ying, Xu, Xu, Zhao, Wenxia, Li, Nan, McDonald, Samuel A., Chai, Yuan, Atkinson, Michael, Dobson, Katherine J. ORCID logoORCID: https://orcid.org/0000-0003-2272-626X, Michalik, Stefan, Fan, Yingwei, Withers, Philip J., Zhou, Xiaorong and Burnett, Timothy L.;