Key experiments and thermodynamic revision of the binary Al-Sr system

The Al-rich Al-Sr phase equilibria are in the focus of this study. The temperature of the (Al)-SrAl4 eutectic reaction is determined to be 655.6 °C by carefully calibrated and controlled differential scanning calorimetry (DSC) experiments. The solid solubility limit of Sr in (Al) at 640 °C is determined for the first time by using atom probe tomography to be not higher than 45 wt. ppm. The thermodynamic description of the complete Al-Sr system has been advanced by incorporation of these new data using the Calphad method based on a selected previous modeling of the system. In addition, the descriptions of all intermetallic phases were revised to avoid the artifact of kink point appearing on the heat capacity curves of the compounds at melting or transition temperatures of the elements, which is unphysical. The new modeling shows significant improvement on the Al-rich side of the Al-Sr system, forming a sound foundation for developing multicomponent Al-alloy database.