Abstract:Gas nitridation of TiAl based alloys in an ammonia atmosphere was carried out. The evaluation of the surface wear resistance was performed to compare with those of the non-nitrided alloys. It is concluded that high temperature nitridation raised wear resistance of TiAl based alloys markedly. The tribological behaviors of the nitrided alloys were also discussed. The oxidation kinetics of the nitrided TiAl based alloys were investigated at 800～1000℃ in ho t air. It is concluded that nitridation is detrimental to the oxidation resistance of TiAl based alloys under the present conditions. The nitrided alloys exhibit increased oxidizing rate with the prolongation of nitridation time at 800℃. However, alloys nitrided at 940℃ for 50h display a sign of better oxidation resistance than the other nitrided alloys at more severe oxidizing conditions. The parabolic rate law is considered as the basis of the data processing and interpretation of the mass gain vs time data. As a comparison with it, attempts were made to fit the data with the power law. The oxidation kinetic parameter k_n, k_p and n were measured and the trends were discussed.

Key words: intermetallic compound TiAl; nitridation; oxid ation; wear