Oxidation properties of TiB₂/Ti composites

TiB₂/Ti composites were fabricated by powder metallurgy. The isothermal oxidation behavior of TiB₂/Ti composites sintered at different temperatures (800 , 900 , 1000 and 1100℃) at 600 , 700 , 800 and 900℃ in air were investigated. The reaction product s in the oxidation layer were examined by XRD. The surface morphology and cross2sectional microst ructure of the oxidation layer were analyzed by SEM. The results show that an oxidation layer mainly consist s of rutile-TiB₂, Fe₂O₃, Al₂O₃and B₂O₃. No other Ti oxides are observed within the oxidation layer. Oxidation kinetics curves of TiB₂/Ti composites at 800℃ in air show that the oxidation speed is rapid at the beginning of oxidation, but with the increase of oxidation time the oxidation speed becomes slow due to the formation of an oxidation film. With the increase of volume fraction of TiB₂ reinforcements and sintering temperature, the oxidation resistance of TiB₂/Ti composites can be increased. It is attributed to the formation of the thin and dense oxidation film.