Effect of rapid solidification on structure and properties of some lead-free solder alloys

Abstract

Four of the binary lead-free solder alloys of compositions Sn-0.5Cu, Sn-3.5Ag, Sn-5Sb and Sn-9Zn, were rapidly solidified by melt-spinning technique as a technique for producing new alloy compositions. The results show that rapid solidification causes formation of some intermetallic compounds such as Ag 3Sn and Cu6Sn5 in the two alloys Sn-3.5Ag and Sn-0.5Cu, which cannot be formed at the equilibrium phase diagram at these compositions; contraction in the volume of the unit cell of the tetragonal Sn; reduction of the melting points due to the decrease in the crystalline size of Sn matrix; and formation of some vacancies in the resulting alloys, which cause reduction of the measured density than that calculated by mixture rule and increase the electrical resistivity.