Microstructure, mechanical properties and corrosion behavior of quaternary Mg-1Zn-0.2Ca-xAg alloy wires applied as degradable anastomotic nails

The microstructure, mechanical properties and corrosion behavior of quaternary degradable Mg-1Zn-0.2Ca-xAg (x=1, 2, 4 wt.%) alloy wires, intended as anastomotic nails, were investigated. It was found that these Ag-containing alloy wires mainly consist of Mg matrix and Ag17Mg54 phase, characterized by SEM, EDS, XRD and TEM. Tensile and knotting tests results demonstrate the superior mechanical properties of these alloy wires. Especially, Mg-1Zn-0.2Ca-4Ag alloy exhibits the highest mechanical properties, i.e. an ultimate tensile strength of 334 MPa and an elongation of 8.6%. Moreover, with increasing Ag content, the corrosion rates of these alloy wires remarkably increase due to the formation of more micro-galvanic coupling between Mg matrix and Ag17Mg54 phase, shown by mass loss and scanning Kelvin probe force microscopy (SKPFM) results. The present alloy can be completely degraded within 28 d, satisfying the property requirements of anastomotic nails.