Abstract
Liquid structure plays significant role in solid microstructure and mechanical properties during material processing. In this paper, the temperature dependence of electrical resistivities in liquid Sn-0.7Cu-xBi alloys has been investigated with DC four-probe method. The results show that anomalous changes can be observed on resistivity-temperature curves at certain temperatures in two experimental cycles, which indicate the existence of liquid structural transitions in the melts at elevated temperature, and the transitions are reversible after first cycle heating. The content of Bi has a noticeable influence on the turning temperature and resistivity-temperature curve shape. The anomalous behaviour of the electrical resistivity - temperature curve is analysed from the viewpoint of short-range order. These results will help to enrich the phenomenology of liquid field, and provide some scientific reference to the innovation of lead-free solder manufacturing.

Key words
lead-free solder, electrical resistivity, liquid structural transition, Sn-Cu-Bi alloys

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