Development of a low-density Co-Ni-Al-Ta-Cr superalloy with high mechanical performance and superior oxidation resistance

In this study, a Co-30Ni-10Al-6Ta-10Cr alloy was designed based on CALPHAD (Calculation of Phase Diagrams) method targeting high gamma ' phase fraction and solvus, and optimal thermal processing window. Experimental results concurred with the calculations and validated Cr as a gamma phase-forming element in Co-Ni-Al-Ta-based alloys. The incorporation of Cr in the alloy helps mitigate lattice misfit, coarsening rate, and alloy density, while enhancing microstructural stability. A certain amount of Cr led to the development of a superalloy with both high mechanical performance gamma' solvus and low density. Moreover, the oxidation resistance of the Co-Ni-Al-Ta-based high -temperature alloy can be substantially elevated by the introduction of Cr. At 1000 C-degrees, the Co-30Ni-10Al6Ta-10Cr alloy displayed comparatively low oxidation weight gain, which signifies its excellent oxidation resistance. This is mainly attributed to the formation of continuous (Co,Ni)(Al,Cr)(2)O-4 spinel oxide layers during prolonged oxidation.