Thermodynamic re-assessment and experimental confirmation for the Zn–Mn system

Abstract

The Zn–Mn system has been critically re-assessed based on available experimental data from literature by CALPHAD (CALculation of PHAse Diagram) approach. Solution phases, viz. liquid, (δMn), (γMn), (βMn), (αMn) and (Zn) were described using substitutional solution model. Besides, the ε, αˊ, γ, δ, δ1 and ζ phases were described by the sub-lattice models based on the reported crystallographic information and homogeneity ranges. The β1 phase was treated as a stoichiometric compound since no distinct homogeneity range of this phase was reported. Thermodynamic parameters on the whole system compatible with the databases of Thermo-Calc and Pandat were first obtained. Compared with previous assessments, calculations using the presently obtained thermodynamic parameters achieved a significant improvement. To further verify the reliability of the obtained thermodynamic parameters, eight as-cast Zn–Mn alloys were prepared and the phase compositions and solidified microstructures were analyzed by X-ray diffraction (XRD) and electron probe microanalysis (EPMA). It was shown that the observed experimental results agreed well with the Scheil solidification calculations.