High Temperature Oxidation and Phase Precipitation Behavior of -Type Ti-Mo-O Alloys

The oxidation behavior of Ti-15Mo-xO(x=0.1, 0.2, 0.3, 0.4, 0.5, wt%) alloys at 873 and 1073 K, and the precipitation behavior of a phase at 837 K were investigated by OM, XRD, EPMA, Vickers hardness tester and first-principles calculation. The results show that the oxidation products are all composed of TiO2, Ti3O and Ti6O at 873 K, the oxygen contents have no significant effect on the oxidation behavior of the alloys, which is mainly controlled by the diffusion of titanium out of the substrate. At 1073 K, the oxidation products of each alloy are TiO2, but the oxygen contents have a significant effect on the oxidation behavior of the alloys. In low oxygen-added alloy, the oxidation process is controlled by the oxidation reaction between oxygen and substrate combined with the oxygen diffusing into the substrate, while with the oxygen contents increase, it is controlled by the oxygen diffusing into the substrate, which enhances the oxidation resistance. The a phase precipitated by aging at 873 K for 10 and 100 h increases with the increase of oxygen contents and aging time, the lattice parameter of molybdenum- rich and oxygen-poor beta phase decreases, and the c axis of oxygen-rich and molybdenum-poor a phase increases, while the a axis is basically unchanged, and the c/a radio increases. The hardness of the alloys increases with the increase of oxygen contents before and after aging. However, under the condition of the same oxygen content, molybdenum and oxygen elements are redistributed in the two phases with the precipitation of a phase, which leads to the decrease of the hardness of the alloys after aging.