Oxidation resistance improvement of Ti-50Al intermetallics by pre-oxidizing and subsequent polishing

The oxidation resistance of Ti-50Al intermetallics has been improved by pre-oxidizing at 800°C×48 h in air and subsequently polishing the outer TiO2 layer of the oxide scale. The cyclic oxidation resistance’s at 800°C of the per-oxidized and polished specimens are substantially improved and the oxidation kinetics follow the parabolic rate law. This means that the outermost alumina-rich layer of the pre-oxidized and polished specimens is protective against oxidation at 800°C in air. This characteristic is attributed to the compressive stress relief associated with the removal of the outer TiO2 layer. The stress relief will alleviate cracking or rupture of the scales and simultaneously reduce the stress-assisted diffusion in the scale. At the same time, the catalytic effect of outer rutile titania may also play a detrimental role in the oxidation resistance of TiAl at high temperature.