Role of Hf and Re on the lattice misfit between γ/γ′of Co-Ti-V superalloys

The relationship between γ′ phase morphology and γ/γ′ lattice misfit degree in Co-Ti-V superalloy with different Hf and Re contents was studied by observation of microstructure and X-ray diffraction analysis. The EDS is used to analyze the relationship between the distribution behavior of each element and lattice misfit between γ/γ′ of Co-based superalloys. The effect of Hf and Re content on the high temperature compression properties of Co-based superalloys was studied by 1000 ℃ high temperature compression test. The results show that the morphology of γ′ phase shifts from square to spherical, and the lattice misfit between γ/γ′ phase decreases with the increment of Hf content.The morphology of γ′ phase changes from square to long strip, the γ′ phase turns coarse, and the lattice misfit between γ/γ′ phase decreases with the increment of Re content. According to the EDS analysis, Co，Hf and Re are enriched in the γ phase, while the Ti and V are enriched in the γ′ phase. With the increase of Re content, the yield strength and ultimate strength of the alloy are increased. The yield strength and ultimate strength of the alloy are decreased firstly and then increased with the increase of Hf content.