Enhancement of Co212 superalloy through cBN reinforcement: Insights derived from spark plasma sintering

The performance of superalloys is primarily determined by their microstructure, which affects their mechanical properties and durability. In this study, Co212 superalloy composites reinforced with cubic boron nitride (cBN), an ultrahard ceramic, were synthesized using spark plasma sintering (SPS) and thoroughly investigated for their mechanical performance. Incorporating cBN into the Co212 matrix notably affected the microstructure and mechanical performance of the composite. The unreinforced Co212 alloy exhibited the highest shrinkage of 60 % and a density of 8.39 g/cm³. When cBN was added, the shrinkage decreased to 37.5 %, and density dropped to 6.56 g/cm³, owing to the lightweight and hard nature of cBN at 30 wt.%. X-ray diffraction indicated the presence of dual-phase structures (FCC and HCP) and α-Co precipitates at the grain boundaries, which contributed to the strengthening. Microstructural analysis confirmed the uniform dispersion of cBN particles throughout the matrix. Notably, adding 20 wt.% cBN significantly increased nano-hardness to approximately 13.1 GPa and elastic modulus to about 368 GPa, with little change in overall stiffness. These findings demonstrate the potential of Co212–cBN composites for high-performance applications that require exceptional mechanical strength and durability.