Non-isothermal Creep of Metal Matrix Composites

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This research extends existing models of creep deformation in metal matrix composite (MMC) materials to include limited fiber/matrix interfacial adhesion, matrix materials exhibiting work hardening and anisotropy, and three dimensional microstructures. Experiments and simulations are anticipated for aluminum/silicon carbide and copper/tungsten MMC systems, according to a four part plan. (1) Important constituent and interface properties are measured using several novel experiments and the microstructural configurations are determined using metallographic techniques. (2) Finite element simulations are carried out to predict non-isothermal creep rates in the two MMC systems. These simulations will be expanded later to include a wider range of microstructures, constituent and interface properties, and temperature/load paths. (3) The non- isothermal deformation rates for the two MMC systems are measured in uniaxial tension and biaxial tension as functions of temperature/load paths. (4) The experimental results and model predictions for the two systems are compared and a consistent model for evaluating the creep-based lifetimes of MMC systems with non-isothermal histories are developed. %%% Currently there is a strong interest in materials suitable for moderately elevated temperature structural applications requiring low density, high static strength, and good creep resistance. MMC materials exhibit some of these properties and promise great improvements in component lifetimes and performance.