| Abstract Scope |
Refractory alloys are of interest for aerospace applications due to their high melting points and strengths at elevated temperatures. However, refractory metals are notorious for their poor oxidation resistance, as their single-cation oxides are non-protective. Recently, complex refractory oxides have been proposed to be more protective. This work focuses on forming TiNb2O7 and Zr6Nb2O17 from the oxidation of alloys in the binary Nb-Ti and Nb-Zr systems. Five Nbx-Ti(100-x) and Nbx-Zr(100-x) alloys (x=20, 34, 50, 60, 80 at%) were produced and oxidized in 1% O2-Ar at 1050°C for 20 h to explore the relationship between oxide scale and alloy composition. Micro x-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy were employed to characterize the oxide scales. Nb80Ti20 grew only Ti-Nb-O complex oxides and no Nb-Zr oxide scale consisted of only Zr-Nb-O complex oxide. Critical Nb compositions that define a maximum or minimum mass gain were found in both systems. |