Investigations of the electrical resistivity of liquid Sn–20 wt-%Sb alloy as a function of temperature were carried out by dc four probe method. An abnormal change on the resistivity–temperature curve was observed in temperature interval of 850–980°C, which indicated that temperature induced liquid–liquid structure transitions (TI-LLST) occurred with temperature rising. Further explorations of effects of TI-LLST on solidification showed that the undercooling for primary or peritectic phase crystallisation increased for the samples solidified from the melt experienced the TI-LLST, and the size of primary phase decreased markedly.

The electrical resistivity-temperature curve (ρ-T ) of Sn-0.7Cu-xBi (wt.%) melts was measured, and anomalous changes were observed on the ρ-T curve at the temperature far above the corresponding liquidus. The results reveal that the melts have experienced a temperatureinduced liquid-liquid transition (LLT), and the transition is reversible after the first cycle heating. Based on the result of LLT, solidification experiments and spreadability testing were carried out on the Sn-0.7Cu-xBi alloy to investigate the effect of LLT on the solidification and wettability. The results show that the microstructure was refined, and the wettability was improved when the solder samples solidified from the melt experienced LLT.K e y w o r d s : Sn-0.7Cu-xBi solders, liquid-liquid transition, solidification, wettability