The effect of copper on the microstructure and mechanical properties of Bio Zn-Cu alloy

In this study, the effect of copper on the microstructure and mechanical properties of the Zn-xCu (x= 1,2 and 3.5 Wt.%) bioalloy were investigated. The extrusion was performed on Zn-xCu alloys with speed of 2 mm/min at a temperature of 240 °C to improve microstructure and mechanical properties. The extrusion ratio was considered to be 5 to 1. In order to investigate the effect of copper on the mechanical properties of this alloy such as yield strength, tensile strength and relative elongation percentage, the extruded specimens were subjected to uniaxial tensile test at room temperature. The results of tensile test showed that the highest yield strength, ultimate strength and elongation were obtained by Zn-3.5Cu alloy which is 215MPa, 234 MPa and 46%, respectively, which meets the general design criteria for cardiovascular stents. Scanning Electron Microscope images showed that as the Cu content increases, more CuZn5precipitates were formed. Microstructural studies show that with increasing the copper content, the secondary phase distribution in the matrix increases and during the extrusion process, the secondary phases are crushed and stretched in the extrusion direction, which increases the yield stress and tensile strength of the alloy with higher copper content.