High-temperature oxidation behavior and anti-oxidation mechanisms of (TiC + (TiZr)₅Si₃)/TA15 composites

This study investigates the high-temperature oxidation behavior of TA15 alloy and (TiC + (TiZr)₅Si₃)/TA15 composites (both sintered and hot-rolled) in the temperature range of 600–800°C. After 100 h of oxidation at 600°C, both composites exhibited comparable oxidation resistance, with a weight gain approximately 50 % lower than that of the TA15 alloy. At 700°C, the weight gain decreased by 27.4 % for the sintered composite and 17.8 % for the hot-rolled composite, indicating that plastic deformation slightly affected oxidation resistance. At 800°C, the reductions were 37.9 % and 30.6 %, respectively, and oxide spallation occurred in all samples. Hot-rolling introduced high-density dislocations and subgrain boundaries, which facilitated oxygen diffusion, thereby reducing oxidation resistance. Compared to the TA15 alloy, the introduction of TiC and (TiZr)₅Si₃) reinforcements effectively suppressed oxygen inward diffusion and oxide growth, improving the oxidation stability of the composites. These reinforcements also pinned the oxide layer, enhancing its adherence during thermal oxidation. The sintered composite exhibited the best oxidation resistance. Cross-sectional analysis of the oxide layer revealed a multilayered structure, consisting of an amorphous carbon outer layer, an Al₂O₃+TiO₂ mixed layer, a TiO₂+Ti₆O/Ti₃O+SiO₂ mixed layer, and a Ti-Al-N ternary phase layer adjacent to the substrate.