Thermodynamic description of the Al–Fe–Mg–Mn–Si system and investigation of microstructure and microsegregation during directional solidification of an Al–Fe–Mg–Mn–Si alloy

Abstract The thermodynamic database for the Al –Fe–Mg–Mn– Si system is developed based on the constituent binary, ternary, and quarternary systems. The computed phase diagrams agree well with the experimental data. The obtained database is used to describe the solidification behavior of Al 356.1 (91.95Al–0.46Fe–0.3Mg–0.32Mn–6.97Si, in wt.%) and Al 356.2 (92.77Al–0.08Fe–0.35Mg–6.8Si, in wt.%) under equilibrium and Gulliver–Scheil non-equilibrium conditions. The reliability of the established thermodynamic database is also verified by the good agreement between calculation and experiment for both equilibrium and Gulliver–Scheil non-equilibrium solidifications. Microstructure and microsegregation of the directionally solidified Al 356.1 alloy are investigated with a growth rate of 0.04445 cm s–1 and a temperature gradient of 45 K cm–1. Fractions of solids formed are measured by using quantitative image analysis of back-scattered electron, and solute redistribution in the primary (Al) is determined by means o...