Liquid-liquid phase separation and solidification behavior of Al-Bi-Sb immiscible alloys

Abstract

Abstract In this study, the liquid-liquid phase separation of three kinds of ternary immiscible Al-Bi-Sb melts was investigated with resistivity and thermodynamics method. The resistivity-temperature curves showed the abrupt and anomalously changes with rising temperature, corresponding to the anomalous peaks of DSC curves, which confirmed the occurrence of the liquid-liquid phase separation. The effects of composition on the liquid-phase separation and final solidification morphology of Al-Bi-Sb alloys were investigated. The compositions of Al70Bi24Sb6, Al60Bi32Sb8 and Al55Bi36Sb9 all fell into liquid miscibility gap. The core-shell structure of Al-rich core covered by Bi-rich could form in three kinds of Al-Bi-Sb alloys by casting in copper mold. Unlike the core shell morphology of Al70Bi24Sb6 and Al60Bi32Sb8, the Al-rich phase distributed randomly on the Bi-rich matrix in the solidification morphology of Al55Bi36Sb9 alloy, which was attributed to the difference of Stokes effect and miscible temperature gap. This study is expected to provide a beneficial guidance and reference for preparing the monotectic alloy with core-shell structure via liquid-liquid phase separation.