Oxidation behavior of a γ-TiAl-based alloy implanted by silicon and/or carbon

Abstract

A study has been made of isothermal oxidation behavior of a γ-TiAl-based alloy, Ti–48Al–1.3Fe–1.1V–0.3B (at.%), implanted with silicon and/or carbon ions at 1173K, C+Si double implantation and following annealing at 1123K for 10.8ks. The isothermal oxidation was tested at 1173K for 349.2ks in air. Si or C implantation was carried out with a dose of 3.0×1021ions/m2 and at the acceleration voltage of 50 and 70kV. As-implanted specimen and the specimen oxidized under specified conditions were characterized by Auger electron spectroscopy (AES), X-ray diffractometry (XRD) and scanning electron microscopy (SEM).High-temperature Si implantation at 1173K shows better oxidation resistance than that implanted at room temperature (RT) for the long-term oxidation. The C introduction by C+Si double implantation weakened the beneficial effect of Si, and the following annealing improved its oxidation resistance. Si doping in the TiAl alloy could facility the Al2O3 formation in the early stage of the oxidation through the enhancement of the Al activity, and C doping is harmful because of a porous oxide scale. From this study, it is indicated that high-temperature implantation at 1173K is effective to thicken the Si-modified layer and thus, a strong and long-term Si modification effect. No cooperation effect of C and Si can be observed for C+Si double implantation to intensify the Si beneficial effect.