Quantitative Understanding of Solute Concentration Distribution by Microsegregation during Solidification

Microsegregation of solute components during the solidification process leads to solute pile-up in the liquid phase, which considerably influences the formation behavior of inclusions. However, no quantitative evaluation of solute concentration distribution during dendritic growth has been conducted. In this study, we established an in-situ observation method for quantitatively evaluating solute concentration distribution using model materials with fluorescent reagents to clarify how solute pile-up progresses owing to microsegregation. In addition to evaluating the physical properties of the model materials required for this study, we successfully realized a quantitative evaluation of solute concentration distribution during dendritic growth. Numerical analysis, considering the equilibrium partition of solute components and solute diffusion in each phase, reproduced the measured solute concentration distribution in the liquid phase. Thus, the solute concentration distribution was evaluated through both actual measurements and numerical analysis, demonstrating that a relatively simple model can represent the progression of microsegregation.