Structure and High-Temperature Oxidation of Ti-Al-Nb and Ti-Al-Ta Intermetallics

Ti-Al based intermetallics are prospective high-temperature materials showing low weight combined with a relatively high strength, high creep resistance and good oxidation resistance at high temperatures. Beside Ti and Al, these materials commonly contain other additives modifying their properties. In the present work, structure and oxidation resistance of two Ti-Al-Nb and Ti-Al-Ta alloys are studied. The alloys are prepared by vacuum arc melting and oxidation is conducted in air at 800-1000 degrees C. It is found that there are significant differences in the structure depending on the ternary additive. There are also differences in oxidation behavior and these differences are discussed in relation to oxidation mechanism.