Oxidation Behavior at 1000-1300 °C in air of Ti2AlC-20TiB2 Synthesized by in-situ Reaction/Hot Pressing

Ti2AlC is considered to be one of the compounds with the best antioxidant properties in MAX phase materials, with potential application prospects in the field of high-temperature structural materials and high-temperature antioxidant protective coatings. However, the low hardness and strength of single phase Ti2AlC limit its wide application in the field of high-temperature material. In order to improve the properties of Ti2AlC, Ti2AlC-20%TiB2 (in volume) composites (referred to as Ti2AlC-20TiB2) were synthesized by the in-situ solid-liquid phase reaction/hot pressing method. Besides, the high temperature oxidation behavior in the temperature range of 1000-1300 degrees C was studied, and the oxidation resistance mechanism at high temperature was analyzed. The results show that the oxidation kinetics of Ti2AlC-20TiB2 composites is logarithmic, exhibiting superior oxidation resistance compared to single phase Ti2AlC. Below 1200 degrees C, the oxide scale is mainly composed of an inner layer of Al2O3 and an outer layer of TiO2, while the outer layer of oxide scale is a mixture of TiO2 and Al2TiO5 at 1300 degrees C. The Al2O3 protective layer formed in the composite is denser than that in single-phase Ti2AlC, which is the key to its excellent antioxidant performance. The addition of TiB2 reduces the grain size of the material and increases the number of grain boundaries for short-circuit diffusion, which facilitates the selective oxidation of Al and accelerates the formation of Al2O3 protective layer. Additionally, B2O3 produced during the oxidation of TiB2 can effectively fill the micropores and repair microcracks, thereby preventing the internal diffusion of O and further enhancing the antioxidant properties of the composites.