FATIGUE DAMAGE MODE OF (Al₂O₃)_f/Al COMPOSITE

The S-N curve of strongly-bonded (Al₂O₃)_f/Al composite wire was determined under tension-tension loading. To understand the fatigue damage mode of the composite, interrupted tests were carried out at different stresses. The fatigue fractograph and microstructures of samples were examined using SEM. The endurance limit of the composite was about 750MPa, which is much higher than about 600 MPa of the SCS-6 fiber reinforced Ti matrix composites. The composite possesses fatigue damage modes of both Ti and resin matrix composites. At high stresses, the initiation and growth of a single crack result in the failure of the composite, while at low stresses the fatigue damage mode includes fiber splitting and transverse propagation of numerous matrix cracks at beginning and single crack propagation at the final stage. The fiber splitting is a controlling mechanism of the composite and the higher endurance limit of the composite can be attributed to it.