Effect of liquid-liquid structure transition on solidification of Sn57Bi43 alloy

In this paper, the effect of the liquid-liquid structure transition (L-LST) on the solidification behaviors and morphologies of Sn57Bi43 alloy was further studied. The liquid structure of Sn57Bi43 was studied with resistivity, thermal analysis and viscosity method. The obvious turning point is observed on resistivity-temperature, DSC and viscosity-temperature curves of Sn57Bi43 alloy. The resistivity increases linearly with increasing temperature before the turning point. These results indicate that temperature-induced liquid-liquid structure transition occurs at 943-1093 K and is reversible, which may be formed by large cooperative motions for molecular rearrangements. What is more, the results show that the undercooling of the eutectic phase increases and the microstructure becomes finer after solidifying from the melt experiencing L-LST. The spacing of eutectic phase decreases markedly. Based on these results explored the melt structure from different aspects, the nature of discontinuity of structural phase transition can be explored and the effect of L-LST on solidification of Sn57Bi43 alloy is studied.