Effect of rare earth Yb and Ce on high temperature oxidation resistance of TiAl alloys

TiAl alloys added with the trace rare earth elements were prepared by spark plasma sintering (SPS). The effects of rare earth elements Yb and Ce on the high temperature oxidation resistance of TiAl alloys were investigated. The microstructure, morphology, and phase composition of TiAl alloys were analyzed by metallographic microscope, scanning electron microscope, and X-ray diffraction. The high temperature oxidation resistance of the alloys was studied by high temperature oxidation experiment. The results show that the relative density of TiAl alloys prepared by SPS is up to 99%. The oxidation kinetics curves of 800 ℃ high temperature oxidation approximately follow the parabolic rule. After the high temperature oxidation at 800 ℃ for 10 h, the mass gain of Ti‒45Al, Ti‒45Al‒0.3Yb₂O₃, and Ti‒45Al‒0.3CeO₂ are 14.63 g·m^‒2, 7.02 g·m^‒2, and 8.19 g·m^‒2, respectively. The high temperature oxidation resistance of the TiAl alloys with the rare earth elements addition is obviously improved, and the high temperature oxidation resistance of Ti‒45Al‒0.3Yb₂O₃ is increased by about 1 time compared with that of Ti‒45Al. The oxidation products of TiAl alloys have the typical layered structure, the outermost layer is TiO₂, and the second layer is TiO₂+Al₂O₃ mixed oxide.