Abstract:Developing low-cost, high-performance nickel-based single crystal superalloys has become an inevitable trend to fulfill the performance requirements of advanced gas turbine blades. In this study, the cyclic oxidation behavior of two novel low-Re single crystal superalloys, A1 and A2, was systematically compared with that of the commercial DD5 alloy at 1100?°C for 100?h. The oxidation resistance of the target alloys was assessed via the static weight gain method. The oxidation kinetics, evolution of oxidation products, and oxide scale structure were comprehensively analyzed using XRD, SEM, and EDS. The results show that a continuous and dense Al?O? layer with a thickness of approximately 7?μm is formed on the surface of A1 alloy. This alloy exhibits the lowest mass gain (average oxidation rate K''= 0.0081?g/(m2·h)) and the minimal oxide scale spallation (G''= 0.28?g/m2), indicative of its superior oxidation resistance among the three alloys. For the A2 alloy, due to its insufficient Cr content (6.5%), NiO and spinel preferentially form and dominate the oxidation path. This leads to the formation of a loose multilayer mixed oxide scale with a discontinuous inner Al?O? layer, accompanied by severe scale spallation (G''= 15?g/m2), resulting in the poorest oxidation resistance. Although the DD5 alloy has a relatively higher Cr content (7%), the absence of synergistic regulating elements such as Hf, coupled with its high Re content (3%), gives rise to the lack of a continuous inner Al?O? layer and the occurrence of internal nitridation. Accordingly, its oxidation resistance is inferior to that of A1 but superior to that of A2. The synergistic effects of alloying elements during the oxidation processes induce distinct differences in the oxidation mechanisms of the three tested alloys.