Effect of TiB₂ on the oxidation behavior of Ta-W alloy

Ta-W and Ta-W-TiB₂ alloys were prepared by hot pressing sintering. The oxidation behavior of Ta-W and Ta-W-TiB₂ alloys at the temperature of 700, 800, and 900℃ were studied. The composition and morphology structure of the oxide layer were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy spectrum analysis (EDS). The results show that, the relative density of Ta-W and Ta-W-TiB₂ alloys prepared by hot pressing sintering is beyond 97%. In the oxidation temperature range, the oxidation kinetics curves of all alloys follow the linear rate law, and the oxidation rate increases with the increase of oxidation temperature. The oxidation products of Ta-W alloys are the Ta₂O₅ solid solution, and the oxidation products of Ta-W-TiB₂ alloys are the Ta₂O₅ solid solution and TiO₂. The stable TiO₂ improves the antioxidant capacity of the alloy at 700~800℃. However, the destrvuction of TiO₂ at 900℃ greatly weakens the protection ability of oxide layer to protect the substrate.