Liquid–liquid structure transition in Sn–3.5Ag–3.5Bi melts

Abstract

The liquid–liquid structure transition (LLST) as the function of temperature and time in Sn–3.5Ag–3.5Bi melts was investigated with the help of direct current four-probe method. The LLST which occurs during first cycle heating of two cycles heating/cooling experiments can divide into two different structure changes: irreversible LLST of 650°C isothermal and step reversible LLST at 770°C–806°C on subsequent heating process. Obvious kinetic phenomena are observed during isothermal experiments. Irreversible and reversible LLST are analysed from the viewpoint of short-range order. These results will help to understand the law and mechanism of liquid field, and provide some scientific reference for the innovation of lead-free solder manufacturing.

Keywords:

• Sn–3.5Ag–3.5Bi solder
• liquid–liquid structure transition (LLST)
• electrical resistivity
• short-range order (SRO)

Acknowledgements

This work was supported by the National Natural Science Foundation of China Grant Nos 50371024 and 50571033, by Hefei University of Technology Research Development Fund No. 2009HGXJ0090.