Liquid phase separation and core–shell morphology of Al75Bi9Sn16 immiscible alloy

ABSTRACTIn this paper, the liquid phase separation (LPS) of liquid immiscible Al75Bi9Sn16 alloy was investigated with calorimetric, thermal analysis and resistivity methods. Based on the fact that the resistivity depends on the composition of two separated liquid phases, the interface area between two separated liquid phases and the volumetric fraction of Sn–Bi-rich liquid x, the LPS can be divided into three stages: nucleation in the range from 1028 to 984 K; diffuse growth and Brownian coagulation in the range from 984 to 925 K; Marangoni migration, Stokes aggregation and coalescence in the range from 925 to 866 K. In addition, the Sn–Bi-rich@Al-rich core–shell structure was formed in Al75Bi9Sn16 alloy, resulting from the Marangoni migration. Based on the results in this study, an efficient method was developed to investigate the thermodynamics and kinetics of LPS of immiscible alloys.