Development of Co-Ni-Al-V-Ta-Cr-based superalloys with high-temperature strength and excellent oxidation resistance

In this study, the effects of V on the microstructure, lattice misfit, solvus temperatures, and oxidation behaviors of the Co-Ni-Al-V-Ta-based superalloys are investigated. The results show that all these alloys exhibit the gamma'/gamma two-phase structures. More importantly, the gamma' solvus temperature increases, and the oxidation resistance is significantly improved with the reduction of V concentration. Subsequently, the Ti (2 at.%) was added into Co-40Ni-10Al-4Ta-1V-12Cr alloy to further raise the properties of the superalloy. It is found that the Co-40Ni-10Al-4Ta-1V-12Cr-2Ti alloy exhibits a higher solvus temperature reaching 1200 C of the gamma ' phase, a low density of 8.48 g/cm3, a low lattice misfit of only +0.37 %, as well as exceptional oxidation resistance and mechanical properties.