Effects of Ta and Nb on high-temperature oxidation properties of Ti-6Al-3.5Sn-4Hf-0.4Si-X alloys

In previous studies, we identified Ta and Nb as the crucial elements affecting the high-temperature oxidation resistance of titanium alloys. To investigate their impact on microstructure evolution and oxidation resistance, we employed a constant temperature oxidation method at 700°C. The results demonstrate that Ta and Nb elements effectively inhibit oxygen diffusion and adsorption on the alloy surface, promote the formation of Al2O3 in the oxide film, and enhance its density. Notably, Ti-6Al-3.5Sn-4Hf-0.4Si-3Ta alloy exhibits exceptional antioxidation performance with an oxidation weight gain of only 0.4884 mg/cm2 after 100 hours of constant temperature oxidation at 700°C, an oxide film thickness of merely 1.047 μm, and a significant proportion (36.29 %) of O atoms combined with Al in the oxide film. The statement is in line with our previous computational findings and serves as a research foundation for the advancement of high-temperature titanium alloys. •Ta and Nb promote the formation of Al2O3 and reduce the oxygen content of α-phase oxide.