Effect of TiB_2 on the oxidation behavior of Ta-W alloy
ZHAO Cheng-hui;CHEN Yu-hong;YI Zhou-chang;LI Lu;WANG Hong-ye;School of Material Science and Engineering, North Minzu University;
Ta-W and Ta-W-TiB_2 alloys were prepared by hot pressing sintering. The oxidation behavior of Ta-W and Ta-W-TiB_2 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-TiB_2 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 Ta_2O_5 solid solution, and the oxidation products of Ta-W-TiB_2 alloys are the Ta_2O_5 solid solution and TiO_2. The stable TiO_2 improves the antioxidant capacity of the alloy at 700～800 ℃. However, the destruction of TiO_2 at 900 ℃ greatly weakens the protection ability of oxide layer to protect the substrate.