Influence of water vapour on the oxidation behaviour of TiAl based multielement alloys

The isothermal oxidation behaviour of Ti-44Al-4Nb-4Mn-1B, Ti-44Al-4Nb-4Zr-1B and Ti-44Al-8Nb-1B alloys has been studied in Air-H2O environment under atmospheric pressure. The presence of H2O leaded to a significant increase in the oxidation kinetics of TiAl-based alloys and changed the crystal morphology and structure of the oxide scales. Moreover, Air-H2O environment strengthened the anisotropy of defects in the oxides, resulting in the directional growth of TiO2. In addition, the difference of the added elements (Mn, Zr, Nb) leaded to different oxidation behaviors of TiAl-based alloys in the Air-H2O environment, which was obviously different from the influence of these elements in the air or oxygen environment. In particular, the high Nb content not only did not improve the oxidation resistance of the TiAl alloy, but also caused serious internal oxidation at the oxide scale-substrate interface in Air-H2O environment.

Automated summary

The presence of water vapor significantly increased the oxidation kinetics of TiAl-based alloys and changed the morphology of the oxide scales; Air-water vapor environment enhanced the directional growth of TiO2; The different added elements led to different oxidation behaviors of TiAl-based alloys in this environment.