The effects of 4 wt% rhenium （Re） addition on isothermal oxidation behavior of Tribaloy T-800 alloy have been studied at 800 °C and 1 000 °C in air. At 800 °C,T-800 shows nonuniform oxidation between dendritic and eutectic areas. Re addition clearly promotes the nonuniform oxidation,leading to considerably higher mass gains than that of T-800 at this temperature. At 1 000 °C exposure,the thickness of scale on T-800 increases significantly,accompanied by severe scale spallation during cooling to room temperature. On the contrary,T-800Re shows a marked decrease of oxide growth rate compared to the linear one of T-800 at 1 000 °C. The scale adhesion is also improved with Re addition at this higher temperature. Therefore,the role of Re depends on the exposure temperature. Re addition gives high oxidation rate at 800 °C,however,the excellent oxidation resistance is obtained by the addition of Re at a higher temperature of 1 000 °C.
