Influence of Si element on the ultra-high temperature oxidation behavior of Co-20Re-25Cr alloy under low oxygen pressure

The incorporation of low concentrations of silicon has been shown to have a significant effect on the oxidation behaviour of superalloys, but this effect has not been studied at low oxidation pressure. Silicon had a significant effect on the oxidation behavior of superalloys, but its positive role under low oxygen pressure has not been examined in detail. This study investigated the ultra-high temperature oxidation behavior of Co-20Re-25Cr ternary alloys with and without 3.0 at.% Si under 3.0 × 10 ⁻⁵ Pa O ₂ . The results showed that the Co-20Re-25Cr-3Si alloy exhibited enhanced oxidation resistance. This improvement was attributed to silicon, which promoted the rapid formation of a protective Cr ₂ O ₃ layer within a short period. The specific mechanism by which silicon affected the oxidation process was further analyzed and discussed. These findings were crucial for advancing the application of Co-Re-Cr-based alloys in aerospace.