Effect of alloying elements on oxidation of TiAl alloys at 1023 and 1073 K

Long-term oxidation behavior of binary Ti-Al and ternary Ti-34.5 mass%Al based alloys with various element additions was studied at relatively low temperatures (1023 and 1073 K) in the laboratory air. The effect of added elements on the oxidation behavior was somewhat different from the previous results obtained at higher temperatures. The addition of Cr, V, Mn, and Fe (in this order) caused degradation in the oxidation resistance. Particularly, Cr was extremely detrimental; the oxidation rate of the Ti-34.5Al-1Cr alloy exceeds that of the Ti-20%Al binary alloy, probably causing a large doping effect in TiO2. On the other hand Nb, Mo and W were beneficial in the order, resulting in a parabolic oxidation behavior up to 3500 h. Differences in the effect between the three elements may be due to the differences in the morphology of Al2O3 formation within the inner scale.