First-principle calculations were performed to study the effect of Nb on the bonding characteristics of TiAl intermetallic compounds with the emphasis on the electronic interactions between Ti (Al) and O atoms. The calculation results suggest that Nb impose different influence on the electronic structure of Ti-riched and Al-riched TiAl intermetallic compounds. For the Ti-riched alloy, Nb not only reduces the electron density of Ti atom near Fermi energy level, but also enhances the interactions between Al (s) electrons and O (p) electrons. By contrast, Nb has marginal effect on the bonding characteristics of the Al-riched TiAl alloy. With the introduction of Nb, the formation energy barrier of TiO2 is increased, while the generation of anti-oxidation membrane (Al2O3) is facilitated due to the decrease of the formation energy barrier. Both aspects are beneficial to improve the oxidation resistance of the TiAl alloy, which is consistent with the experimental results.

Key words: TiAl intermetallic compound, oxidation property, element Nb, electronic structure, first-principle calculation