Study on the Correlation Between Solidification-Solution Treatment Microstructure and Process Parameters of Superalloy via Integrated Multi-Component Phase-Field Simulation

Nickel-based single-crystal superalloys demonstrate remarkable mechanical properties at elevated temperatures. Solidification and solution treatment are critical steps in determining the properties. To explore the influence of solidification parameters and element content on the solidification and solution treatment process, we developed a coupled phase-field model for solidification and solution treatment, integrated with CALPHAD thermodynamics. This model was employed to investigate the microstructure evolution during directional solidification and solution treatment. An L16(4³) orthogonal experimental design was employed to examine the effects of Re content, pulling rate, and temperature gradient. Solidification results showed that the pulling rate and temperature gradient reduce primary dendrite arm spacing λ₁∝ G^-0.31.V^-0.25, while pulling rate dominates cellular-dendritic transition via enhanced interface supersaturation. Re content exacerbates Al segregation by lowering its distribution coefficient, and pulling rate alleviates Re segregation by shortening diffusion distance. Solution treatment results that the solution temperature depends on the solidus temperature of severely segregated regions; Al achieves near-complete homogenization, while Re retains residual segregation. Pulling rate mitigates both elements’ residual segregation, and Re content exerts opposite effects on Al and Re segregation. Pulling rate is the core regulatory factor for the entire process. This conclusion provides theoretical support for optimizing alloy processes to improve microstructural uniformity.