‌Influence of Small Amount of Cu Addition on Microstructure, Deformation Temperature, and the Tensile Behaviour of Sn-9Zn-1.5Ag Lead free Solder Alloy

Sn-9Zn-1.5Ag and Sn-9Zn-1.5Ag-0.7Cu alloys have been inspected under different five strain rates ranging from 5.4x10^-5 S^-1 to 2.9x10^-3 S^-1 and different three temperatures extended from R.T. (298K) to 393 K for two alloys. The   difference in   thermal action, microstructure and stress-strain advantage related with addition of 0.7 Cu wt% was investigated. Transmission electronic microscope (TEM) investigation of samples revealed a homogenous uniform distribution, size refinement of IMCs and β-Sn grains. Addition of 0.7Cu   particles into the Sn-9Zn-1.5Ag   enhanced the yield stress σ_YS by 17% and reducing the ultimate tensile strength UTS by 12%. The addition of adding Cu was found to be   lowering ductility (total elongation) by 19% of the Sn-9Zn-1.5Ag solder due to the refinement of β-Sn grains; this means that Sn-9Zn-1.5Ag-0.7Cu    is more strengthening than Sn-9Zn-1.5Ag. The activation energy of Sn-9Zn-1.5Ag is lower than that of Sn-9Zn-1.5Ag-0.7Cu; therefore first sample is more superplastic.