Experimental Investigation of the Equlibria in Mg-Al-(Ca,Sr) Systems

摘要

The phase diagrams of Mg-Al-Sr and Mg-Al-Ca systems were investigated experimentally by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. 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 phase changes involved in these systems. The temperature ranges for the phase change peaks have been determined. Enthalpy of melting and enthalpy of formation of the compounds are also reported. Comparison between these results and the thermodynamic findings will be discussed. These results along with the XRD analysis are used to establish the equilibria in Mg-Al-Sr and Mg-Al-Ca systems. XRD was used to identify the phases in the studied samples. Al_4Sr and Al_2Ca were found to be the dominating phases in Mg-Al-Sr and Mg-Al-Ca systems, respectively.