Research Projects

Ti2AlNb-based alloy, sometimes referred to as orthorhombic alloy, is a class of highly promising lightweight high-temperature materials. This type of alloy is considered to partially substitute the high-density (? = 8~8.5 g/cm3) Ni-based superalloys in the aerospace industry due to its low density, high strength, superior plasticity, high fracture toughness and excellent creep resistance at elevated temperatures. In such applications, the operating temperatures could go beyond 600– 650°C, leading to severe oxidation of the alloy surface. There are three potential approaches to improve high-temperature oxidation resistance: alloying, preoxidation and coating. A two-step voltage-controlled microarc oxidation (MAO) method can be used to produce ceramic coatings on a Ti2AlNb-based alloy. However, after a prolonged exposure to air at elevated temperatures, intermetallics exhibit oxygen induced embrittlement characteristics such as low ductility and brittle fracture. Thus, an understanding of high-temperature oxidation mechanisms is essential for improving the oxidation resistance of materials. A Ti2AlNb based alloy is observed to exhibit fairly good oxidation resistance below 750°C. After reaching 800°C, the oxidation resistance decreased dramatically. Thus, the oxidation behavior and mechanisms are to be investigated at a higher temperature of 800°C and above