The thermodynamic database for the multi-component Al-Fe-Mg-Mn-Si-Cu-Zn-Ti system is developed based on the constituent binary, ternary, and quaternary systems. In particular, the quinary Al-Fe-Mg-Mn-Si system is modeled in detail. The computed phase equilibria are in good agreement with the experimental data. The obtained thermodynamic database is then used to describe the solidification behaviors of the alloys Al 356.1 (Al-0.46wt%Fe-0.3wt.%Mg-0.32wt.%Mn-6.97wt.%Si), Al 356.2 (Al-0.08wt.%Fe-0.35wt.%Mg-6.8wt.%Si), and Al 518.2 (Al-0.16wt.%Fe-7.6wt.%Mg-0.01wt.%Mn-0.1wt.%Si) under equilibrium and non-equilibrium (Scheil-Gulliver model) solidifications. The reliability of the established thermodynamic database is justified by the good agreement between calculation and experiment for both equilibrium and non-equilibrium solidifications. A user-friendly phase diagram calculation engine, PanEngine, is employed in the thermodynamic calculations. The micromodel, which includes solid back diffusion, undercooling, and coarsening, is coupled with PanEngine to predict the microstructure and microsegregation of two solidified alloys, Al 356.1 and alloy Al-4.5wt.%Cu-1wt.%Si-0.5wt.%Mg. Microsegregation in alloy Al 356.1 was experimentally investigated with directional solidification and electron probe microanalysis (EPMA) techniques. Calculated results using the micromodel agree well with the experimental values in the solidification range where only primary (Al) is solidified, while the results computed by using Scheil-Gulliver model show some deviations from the experimental data.
E-mail: yong-du @mail.csu.edu.cn