Effects of Cu Content on the Mechanical, Degradable, and Antibacterial Properties of the As-Cast Zn-3Al-xCu Alloys

Degradable zinc alloys are a new type of medical material that has great potentials to be used in bone implants. In this work, a series of degradable Zn-3Al-xCu ( x = 0, 0.5, 1.0, and 1.5 wt.%) alloys were designed, and the effects of copper content on the mechanical, degradable and antibacterial properties were systematically investigated. These include microstructural observation, tensile, electrochemical, immersion, and antibacterial tests. The results showed that Cu addition contributed to the grain refinement effect, and the grain size of Zn-3Al-1.5Cu alloy could reach a minimum of 5 μm. A tensile test showed that Cu addition improved the mechanical properties of the Zn-3Al-Cu alloys with ultimate tensile strength (UTS) reaching up to 209.30 ± 1.91 MPa and elongation up to 9.11 ± 0.48%. The in vitro immersion examination showed that the degradation rate of the Zn-3Al-xCu alloys accelerated with increasing Cu content, and the fastest corrosion rate of 0.025 ± 0.0005 mm/y was achieved for the Zn-3Al-1.5Cu alloy. Moreover, the antibacterial tests also displayed that the Zn-3Al-xCu alloys exhibited a significant antibacterial effect against S. aureus , and their inhibition zone diameters improved from 0.2 ± 0.1 to 4.9 ± 0.4 mm.