Improving the oxidation resistance of Ti3SiC2 by forming a Ti3Si0.9Al0.1C2 solid solution Original Research Article

The oxidation behavior of the Ti3Si0.9Al0.1C2 solid solution in air was investigated at 1000–1350 °C. The parabolic rate constants of Ti3Si0.9Al0.1C2 were decreased by 2–4 orders of magnitude compared with those of Ti3SiC2 at 1000–1300 °C. At 1000–1100 °C, the oxide scales displayed a continuous α-Al2O3 inner layer and a discontinuous TiO2 (rutile) outer layer. At 1200–1300 °C, the continuous inner layer was still α-Al2O3, but the outer layer was a mixture of TiO2 (rutile) and Al2TiO5. The oxide layers were dense, adherent and resistant to thermal cycling. However, the oxidation resistance of Ti3Si0.9Al0.1C2 deteriorated at 1350 °C because of the depletion of α-Al2O3. This depletion was caused by the extensive reaction between TiO2 (rutile) and α-Al2O3 to form Al2TiO5. The high activity and diffusion of Al and the low solubility of oxygen in the solid solution were the key factors for the formation of a continuous α-Al2O3 layer during high-temperature oxidation.