Abstract

In this work, the ternary Mg-Al-Sr system was investigated experimentally by differential scanning calorimeter (DSC), X-ray Diffraction (XRD) and metallography. The experimental work focused on the critical regions after reviewing the phase diagrams developed by thermodynamic modeling. DSC has permitted real-time measurement of the temperature and enthalpy of the phase transformations. The experimental results were compared with the pertinent thermodynamic findings as well as with the literature data. The thermodynamic calculations are consistent with experimental results in few samples especially in the liquidus temperature, whereas discrepancy was observed in several cases especially in the solid phase transformation temperature that suggests this system should be remodeled. Two ternary eutectic transformations have been observed. XRD was used to identify the phases in the studied samples where Al 4 Sr and (Mg) were found to be the dominating phases. Distinct unknown peaks were observed in the investigated samples. In this investigation, four new phase fields have been tentatively identified. The new phase may be ternary intermetallics or ternary or binary solid solutions. Thermodynamic calculations were also utilized to understand the microstructures and the phase relationships. The microstructural evolution in two post-DSC samples has also been investigated and compared with the as-cast condition.