STP723

    Fatigue Behavior of Silicon-Carbide Reinforced Titanium Composites

    Published: Jan 1981


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    Abstract

    The low cycle axial fatigue properties of 25 and 44-fiber volume percent SiC/Ti(6Al-4V) composites were measured at room temperature and at 650°C. At room temperature, the S-N curves for the composites showed no anticipated improvement over bulk matrix behavior. Although axial and transverse tensile strength results suggest a degradation in silicon-carbide fiber strength during composite fabrication, it appears that the poor fatigue life of the composites was caused by a reduced fatigue resistance of the reinforced Ti(6Al-4V) matrix. Microstructural studies indicate that the reduced matrix behavior was due, in part, to the presence of flawed and fractured fibers created near the specimen surfaces by preparation techniques. Another possible contributing factor is the large residual tensile stresses that can exist in fiber-reinforced matrices. These effects as well as the effects of fatigue testing at high temperature are discussed.

    Keywords:

    metal matrix composite, SiC/Ti(6-4), low cycle fatigue, ultimate tensile strength, modulus, Poisson's ratio, microstructure, fiber flaws, residual stresses, mechanisms, composite materials, fatigue (materials)


    Author Information:

    Bhatt, RT
    Materials scientist and head, National Aeronautics and Space Administration, Lewis Research Center, ClevelandOhio,

    Grimes, HH
    Materials scientist and head, National Aeronautics and Space Administration, Lewis Research Center, ClevelandOhio,


    Paper ID: STP27625S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP27625S


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