Effect of Cu additions on the structural and mechanical properties of Sn–Zn alloy

Highly pure Sn, Zn, and Cu were used to get Sn–8.6 wt.% Zn and Sn–8.6 wt.% Zn–(0.5–2 wt.%) Cu alloys prepared by the normal cast technique. The ingot was homogenized then swaged into wire of 0.8 mm in diameter and sheets of 1.5 mm thick. From the analysis of X-rays diffraction patterns, for Sn, binary and tertiary (with 1 wt.% Cu) alloys the average crystallite size and lattice strain were calculated. The samples were subjected to different axial loads and a torsion stress applied simultaneously. The accompanying elongation measured was found to increase with increasing both the axial load and the average shear strain but decreased with increasing Cu content. The large crystallite size of Sn was reduced by adding Zn, but adding Cu increased the crystallite size of the binary alloy. The maximum strength was reached with 1 wt.% Cu, while 0.5 wt.% Cu caused no significant variation of strength.