Oxidation behavior of TiAl protected by Si+Nb combined ion implantation

The combined ion implantation of Si+Nb at room temperature and at 1173 K with C contamination was employed to improve the oxidation resistance of a γ-TiAl based alloy [Ti–48Al–1.3Fe–1.1V–0.3B (at%)]. The implantation was conducted with a dose of 3.0×1021 ions/m2 and at an accelerate voltage of 50 kV for each element. The isothermal oxidation behavior of above treated alloys was tested at 1173 K for 349.2 ks in air. The oxide scales formed by short-term and long-term oxidation were characterized by AES, SEM and XRD. It was found that the alloy implanted with Si+Nb at 1173 K with C contamination shows excellent long-term oxidation resistance in comparison to that of the room temperature Si+Nb implanted alloy, although the latter also significantly lowers the oxidation rate of non-implanted alloy. A continuous, compact and thus a protective Al2O3 layer was formed in the scale of the alloy implanted with Si+Nb at 1173 K with C contamination after long-term oxidation, and this layer contributed to the best oxidation resistance. It is also indicated that the introduction of Si into Nb modified layer and, in particularly C in conjunction with Nb and Si in the modified layer can further effectively favor the formation of the continuous Al2O3 layer in the scale on alloy during high temperature oxidation.