Abstract
Ti2AlC ternary carbide is being explored for various high temperature applications owing to its high strength at high temperatures, excellent thermal-shock resistance, and high electrical conductivity. In this study, isothermal oxidation at 1000�XC, 1200�XC, and 1400�XC for up to 25 hours, as well as 1,000 1-hour cyclic oxidation at 1200�XC were performed in air to examine the oxidation behavior of Ti2AlC. Characteristics of the oxide scale developed in air, including mass change, residual stress in the ��-Al2O3 scale, phase constituents and microstructure, were examined as functions of time and temperature by thermogravimetry, photostimulated luminescence, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy via focused ion beam in-situ lift-out. A continuous and adherent ��-Al2O3 scale underneath a discontinuous-transient rutile-TiO2 scale was identified in the oxide scale developed at 1000�XC and 1200�XC. At 1400�XC, Al2TiO5 was identified as the discontinuous-transient scale above the continuous and adherent ��-Al2O3 scale. The ��-Al2O3 scale thickened to more than 15 ��m after 25 hours of isothermal oxidation at 1400�XC, and after 1,000 1-hour cyclic oxidation at 1200�XC, yet remained adherent and protective. The compressive residual stress determined by photoluminescence for the ��-Al2O3 scale remained under 0.65 GPa for the specimens oxidized up to 1400�XC for 25 hours. The small magnitude of the compressive residual stress may impart the high spallation-resistance of the protective ��-Al2O3 scale developed on Ti2AlC.