Cyclic oxidation behavior of TiC/Ti₃AlC₂ composites at 550-950 °C in air

Bulk TiC/Ti₃AlC₂ composites containing 5 vol% TiC were fabricated by pressure-assisted self-propagating high-temperature synthesis, and their cyclic oxidation behavior was investigated at 550-950 °C in air for up to 40 cycles. The results demonstrated that at temperatures of 750-950 °C TiC/Ti₃AlC₂ composites displayed excellent cyclic oxidation resistance. The oxidation kinetics basically followed a parabolic rate law. As revealed by XRD and SEM/EDS, the scales consisted of an outer discontinuous layer of rutile TiO₂ and an inner continuous layer of α-Al₂O₃. The scales were dense, adhesive to the substrate and resistant to thermal cycling. However, at lower temperatures of 550 and 650 °C, the oxidation kinetics followed a linear rate law with larger oxidation rates. The cyclic oxidation resistance was deteriorated owing to the formation of microcracks and voids in the scales.