| Abstract Scope |
This study investigates adding Zn to as-cast Mg–0.6Ca–0.5Sc alloy to improve strength while preserving corrosion resistance for load-bearing implants. As-cast Mg–0.6Ca–0.5Sc alloys with 0, 3, and 5 wt.% Zn (denoted 0Zn, 3Zn, and 5Zn) were tested in 0.9 wt.% NaCl solution, using electrochemical testing and pre/post-corrosion characterisation to link microstructure to corrosion response. Zn addition reduced grain size from 230 μm to 107 μm in 5Zn and raised Vickers hardness from 67 HV to 140 HV. The 3Zn alloy showed the best corrosion resistance, while 5Zn partially lost this protection due to a higher fraction of cathodic Zn-rich second-phase particles. Kelvin probe force microscopy confirmed the matrix/second-phase Volta potential difference rose from 46 mV in 0Zn to 77 mV in 5Zn, indicating stronger micro-galvanic coupling. The 5Zn Mg(OH)₂ film was discontinuous and disrupted. The 3Zn composition is optimum, providing both higher strength and better corrosion resistance than the base alloy. |