Oxidation Behavior of Ta-Ti-Al-W Alloy at 1000℃

The Ta-25Ti-18Al-6.5W alloy was prepared by vacuum suspension melting method to investigate the oxidation behavior of Ta-Ti-Al-W alloy at 1000℃. The phase composition and microstructure of as-sintered and oxidized specimens were characterized by XRD, SEM, and EDS. Results show that the oxidation kinetics of the alloy follows the parabolic law at first, and then changes into the linear law. During the oxidation process, Ta can be oxidized preferentially, and the enrichment areas of TiO2 and Al2O3 are observed in the surface of oxide scale, because of the higher diffusion rates of Ti and Al. In the initial stage, the oxidation is controlled by external diffusion of alloying elements. The oxidation layer is mainly composed of the TiO2 and solid solution of Ta2O5, WO3, TiO2, Al2O3. With increasing the oxidation duration, the oxides scale which controls the oxidation process shows different layer structures: an outer layer mainly composed of TiO2 and Al2O3, a Ta2O5ss solid solution inner layer and a transition layer with less oxygen content. © 2021, Science Press. All right reserved.