Comparison of Nb- and Ta-effectiveness for improvement of the cyclic oxidation resistance of TiAl-based intermetallics

► Oxidation of Ti-45.2Al-7.2Nb and Ti-44.8Al-6.6Ta (in at. %) alloys at 800-1000°C in air was studied. ► It was observed that both alloys show similar and excellent oxidation resistance at 800-900°C. ► At 1000°C, a strong oxide spallation is observed, mainly on the Nb-containing alloy. The Ta-containing alloy shows significantly better oxidation resistance at 1000°C. ► Despite the similarity of both ternary additives, chemical microanalysis of scales revealed that there are significant differences in element distributions between the alloys. ► Tantalum was shown to slow down the oxidation more efficiently than niobium.