Oxidation behavior of a novel multi-element alloyed Ti2AlNb-based alloy in temperature range of 650–850 °C

Abstract

The oxidation behavior of a novel multi-element alloyed Ti2AlNb-based alloy (Ti–22Al–25Nb–1Mo–1V–1Zr–0.2Si) was studied in the temperature range of 650–850 °C. X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with an energy-dispersive spectroscopy (EDS) were used to identify the phase constituents and microstructure of the scales formed on the specimens after oxidation at different temperatures. Isothermal oxidation tests show that the oxidation rate of the alloyed Ti2AlNb-based alloy is obviously reduced at all temperatures, and the mass gains are very low for this alloy in comparison with those of Ti–22Al–25Nb alloy. The alloying elements Mo, V, Zr and Si have an obvious affect on the oxidation products of the alloys. The improved oxidation resistance for the alloy is ascribed to the introduction of Mo, V, Zr and Si elements, which are beneficial to the selective oxidation of Al to form protective oxides while are disadvantage of the formation of poor oxidation resistance oxides such as AlNbO4.