Fatigue damage and its localization in particulate metal matrix composites

A series of high and low cycle fatigue tests have been conducted on Al2O3 particulate-reinforced 6061 aluminum alloy composite(Al2O3/6061 Al). Fatigue damage in the composite, as observed by optical and scanning electron microscopes, is primarily in the form of particle debonding, fractured particles and matrix cracks. Mesoscale reinforcement defects, such as a clump of large particles, cause damage localization which may lead to short crack initiation and extension. The cyclic plastic strain amplitude appears to be an appropriate low cycle fatigue damage parameter as indicated by the hysteresis loop variation of strain-controlled cylindrical specimens.