The superior oxidation resistance of 60NiTi aircraft bearing alloy by introducing TiN and Ni3Ti multiple-layer structure

To improve the oxidation resistance of 60NiTi alloy, the TiN layer was introduced at the outermost of 60NiTi alloy. The results showed that the 60NiTi alloy exhibited the superior oxidation resistance owing to the construction of TiN layer, regardless of oxidation temperatures. After high-temperature oxidation (900°C), the oxidation layer of the solution treated and nitrided 60NiTi alloys consisted of a multilayer structure comprising: TiO 2 +NiTiO 3 +Ti oxide (Holes), Ni-rich+Ti 2 O 3 +Ti rich oxide (Holes), and Ni 3 Ti, from the outermost to the matrix. The amount of NiTiO 3 oxides is less and the volume percentage of Ti 2 O 3 oxide is more in the nitrided 60NiTi alloy, compared to the solution treated 60NiTi alloy. Density functional theory (DFT) calculations revealed that the O 2- adsorption capacity of (200) TiN was significantly weaker than that of (110) NiTi , which further confirmed that the introduction of TiN layer was beneficial for enhancing the high-temperature oxidation resistance of 60NiTi alloy.