Computational Study of the Effect of Aluminum Content on the Thermodynamic Properties and Phase Stabilityof Mg-Al-Zn Alloys

This study investigates the effect of varying aluminum (Al) content on the thermodynamic properties and phase stability of Mg-Al-Zn alloys using Computational Materials Science techniques. Three Mg-Al-Zn alloys were modeled with 3 wt%, 6 wt%, and 9 wt% Al, while the zinc (Zn) content was fixed at 1 wt% and magnesium (Mg) made up the remaining balance. Phase fraction diagrams were generated using the JMatPro software to analyze the phase transformations and their evolution with temperature. Additionally, the phase compositions and thermodynamic behavior of the alloys at a fixed temperature of 300 °C were examined. The chemical potential (Mμ) of each element was calculated to assess the energy state and stability of Mg, Al, and Zn in the alloys. Furthermore, the activity values of the elements were determined to evaluate their deviations from ideal behavior and effective thermodynamic concentrations within the alloys. The results reveal that increasing Al content significantly influences the phase stability and transformation behavior of the Mg-Al-Zn system. Higher Al concentrations led to a greater proportion of the intermetallic phase (Mg17​Al12) at 300 °C, which in turn affected the chemical potential and activity of the constituent elements. This computational investigation provides insights into the role of Al in tailoring the thermodynamic properties and phase constitution of Mg-Al-Zn alloys, offering valuable guidance for alloy design and optimization in lightweight structural applications.