Thermodynamic modeling of the Mg-Mn-Zn system based on the refinement of the Mg-Zn and Mn-Zn systems

Based on the critical evaluation of the experimental data in the literature, the Mg-Mn-Zn system was assessed utilizing the CALPHAD (CALculation of PHAse Diagram) method. The binary Mg-Zn and Mn-Zn systems were reassessed to obtain a better thermodynamic description. The solution phases, including liquid, (Mg), (delta Mn), (gamma Mn), (beta Mn), (alpha Mn), and (Zn), were described using the substitutional solution model. The solid Zn was treated as Hcp_A3 not Hcp_Zn in the present work. The compounds with and without solubility range were described by the sub-lattice model and stoichiometric phases. The presently calculated phase diagram and thermodynamic properties of the Mg-Zn system demonstrated obvious improvements in comparison with the previous work. Thermodynamic parameters for the Mg-Mn-Zn system were obtained by extrapolating the binaries and adjusting the ternary parameters based on reliable experimental data in the literature. Comparing the calculated results with the experimental data, a good agreement was achieved, which confirms the reliability of the presently obtained thermodynamic parameters.

Automated summary

This study assessed and described the Mg-Mn-Zn system using the CALPHAD method, and improved the thermodynamic description by reassessing the binary Mg-Zn and Mn-Zn systems. The calculated phase diagram and thermodynamic properties showed significant improvements compared to previous work, and the obtained thermodynamic parameters were reliable based on comparison with experimental data.