Determination of liquid-phase boundaries in Zn-Fe-Mx systems

Iron solubilities in molten Zn-Al alloys were experimentally determined at temperatures from 450 to 480 degrees C, a range relevant to continuous galvanizing operation. The Fe solubility was found to decrease slowly with increasing Al content in regions where zeta (FeZn13) or delta (FeZn7) is the equilibrium compound and rapidly in the region where the eta (Fe2Al5Znx) phase is the equilibrium compound. Analyses of the experimental data indicated that Fe solubility is governed by the thermodynamic properties of the intermetallic compound in equilibrium with the molten Zn-Al alloy. A model was developed to describe the liquid surface in the Zn-rich corner of the Zn-Fe-Al system. The methodology developed in the exercise has proven applicable for the determination of the liquid surface in the Zn-Fe-Ni system.