Multi-component numerical simulation and experimental study of dendritic growth during solidification processing

摘要

A multi-component model was developed to simulate microstructure evolution during solidification of a quinary alloy system. The thermodynamic and kinetic parameters including liquidus slope, partitioning coefficient, diffusion coefficient etc. as functions of temperature and solute concentration were obtained using CALculation of PHAse Diagrams (CALPHAD) modeling. The effect of solute interactions on diffusion and dendrite growth velocity was fully considered in this model. The model was validated by mesh size convergence, and compared with a well-accepted analytical model. The new model was shown to successfully display solidification dendrites and solute redistributions of a quinary Al-Si-Mg-Fe-Mn alloy. The effect of different solute elements on solute diffusion and dendrite growth was analyzed. Additionally, various calculation domains and cooling rates of industrial importance were tested in the simulations. Directional solidification experiments were used for model validation in secondary dendrite arm spacing measurement and simulation. The validated relationship between the secondary dendrite arm spacing and cooling rate in a complex quinary system confirmed the accuracy of this 3-D multi-component model, which provides a critical connection between solidification processing and mechanical property prediction in Integrated Computational Materials Engineering (ICME) of solidification products.