A study of microstructure and microsegregation of aluminum 7050 alloy

An Al 7050 alloy containing 11 components was directionally solidified with two cooling rates of 0.45 and 0.9 K s−1. The microstructure and microsegregation in the solidified alloy were experimentally determined by metallography, scanning electron microscopy, image analysis, X-ray map and EPMA. The microstructures of the alloy solidified with the two cooling rates exhibited dendritic structures. Al, Sigma, S, θ, Mg2Si, Al7Cu2Fe and Al13Fe4 were found in the solidified structure. The volume fractions of solids and solute concentration gradients in the dendrites were studied experimentally by image analysis and an area scan technique, and numerically by using a modified Scheil model, respectively. The model predictions were coupled with robust phase diagram calculation package panengine. The calculated results from the modified Scheil model were in good agreement with the measured data. The PanAluminum–Aluminum Database was used to obtain the needed Gibbs free energies of all phases during the modeling.