Improvement of Oxidation Resistance of TiAl Intermetallic Compound by Sulfidation Treatment
Takayuki Yoshioka, Toshio Narita
The oxidation resistance was investigated in air at 1173K for the TiAl alloy, which has been pre-sulfidized at 1173K in a H2-H2S gas mixture to form a TiAl3 layer on the alloy surface due to selective sulfidation of Ti, and changes of the TiAl3 into TiAl2 phase as well as their effects on oxidation behavior were considered.
It was found that the pre-formed TiAl3 layer with 20μm thickness was changed into a TiAl2 layer after oxidation at 1173K for 86.4ks. Both the TiAl3 and TiAl2 layers indicated very good oxidation resistance for long time, up to 810ks. These two layers showed re-passivation capability of forming a protective Al2O3 scale.