9421780 Chang This research advances the methodology of phase diagram calculations recently formulated by the principal investigators. The calculations include ternary and quaternary systems and integrates these calculations with solidification models to predict the paths of solidification. The phase diagram of the quaternary system aluminum-magnesium-zinc-copper (Al-Mg-Zn-Cu) and the solidification paths of selected Al-rich alloys are to be calculated and verified by related experiments. Phase diagram calculations for the quaternary system includes the constituent ternaries, Al-Cu-Zn, Cu-Mg-Zn, and Al-Mg-Cu. Solidification path calculations are carried out for selected Al-rich alloys using the Schiel model and modified Schiel model, which includes back diffusion in the solid. The solidification experiments emphasize several alloys on the Al-rich side of the Al-Mg-Cu alloy system. %%% A knowledge of the thermodynamics and phase equilibria of multi-component alloy systems is vital in developing advanced materials and in improving the processing and manufacturing of advanced materials. ***
