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

DOI: 10.1016/j.actamat.2021.116976 DOI Help

Authors: Ying Wang (The University of Manchester) , Xu Xu (The University of Manchester) , Wenxia Zhao (Beijing Institute of Aeronautical Materials) , Nan Li (Beijing Institute of Aeronautical Materials) , Samuel A. Mcdonald (The University of Manchester) , Yuan Chai (The University of Manchester) , Michael D. Atkinson (The University of Manchester) , Katherine J. Dobson (University of Strathclyde) , Stefan Michalik (Diamond Light Source) , Yingwei Fan (Beijing Institute of Aeronautical Materials) , Philip J. Withers (The University of Manchester) , Xiaorong Zhou (The University of Manchester) , Timothy L. Burnett (The University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acta Materialia , VOL 16

State: Published (Approved)
Published: May 2021
Diamond Proposal Number(s): 20226

Open Access Open Access

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

Journal Keywords: Metal matrix composites (MMC); High-temperature fatigue; X-ray diffraction (XRD); X-ray computed tomography (CT); high cycle fatigue (HCF)

Diamond Keywords: Alloys

Subject Areas: Materials, Engineering

Instruments: I12-JEEP: Joint Engineering, Environmental and Processing

Added On: 12/05/2021 08:33


Discipline Tags:

Aerospace Materials Science Engineering & Technology Composite Materials Metallurgy

Technical Tags:

Diffraction Imaging Tomography