The effect of Ta on oxidation resistance of TiC/hastelloy composites

The oxidation resistance is pivotal to TiC/hastelloy composites applied for high-temperature structural components. In this paper, the effect of Ta on oxidation resistance of TiC/hastelloy composites was investigated. Composites with different Ta contents were prepared by reactive infiltration method, and the oxidation test was held at 800 °C for 100 h in air. The result indicates that as Ta content increases from 1 to 8 wt%, the mass gain decreases from 0.48 to 0.30 mg cm −2 , demonstrating that the oxidation resistance of composites is optimized. The oxide scale changes from sandwich structure to thinner bilayer with CrTaO 4 . Ta decreases the initial oxidation rate of TiC and metal matrix, while Ta promotes the formation of continuous Cr 2 O 3 layer. After oxidation, Ta mainly dopes in TiO 2 and Cr 2 O 3 with 1 wt% Ta, while CrTaO 4 is found in oxide scale with 8 wt% Ta. Ta-doped TiO 2 inhibits the inward diffusion of O, and CrTaO 4 suppresses the outward diffusion of Ni, Ti and Cr. Therefore, the oxide scale with CrTaO 4 on TiC/hastelloy composites exhibits better protective effect.