Cyclic plastic behavior of unidirectional SiC fibre-reinforced copper composites under uniaxial loads: An experimental and computational study

Silicon carbide continuous fiber-reinforced copper matrix composites (Cu/SiCf) offer huge potential as heat sink material for high-heat-flux applications at elevated temperatures (>300 °C) owing to the beneficial combination of strong, stiff and refractory SiC fibers with a highly conductive and ductile copper matrix. As high-heat-flux components are normally subjected to large temperature fluctuations combined with thermal strain variations, degradation of the Cu/SiCf composites caused by fatigue damages under cyclic loads may affect the structural integrity of the component. In this study, the robustness of the Cu/SiCf composites under cyclic loads at different temperatures was evaluated by means of uniaxial cyclic loading tests. The stability of the cyclic deformation hysteresis curves was used as a measure of material's durability. The experimentally observed global deformation behavior was interpreted with the help of a micromechanics-based theoretical model. It was shown that the Mori-Tanaka type mean field theory could describe the cyclic loading behavior of the composite quite well with a good fitting quality between the measured and simulated saturated cyclic curves. The effects of fiber content, applied strain range and test temperature are discussed.