Long-term in vitro corrosion behavior of Zn-3Ag and Zn-3Ag-0.5Mg alloys considered for biodegradable implant applications

•Additions of Ag and Mg provided grain refinement and multiphase microstructure.•Investigated Zn alloys degraded mainly via intergranular and micro galvanic corrosion.•Refined Zn grains and evenly distributed small precipitates provided uniform corrosion.•Precipitates of the ε-Zn3Ag phase corroded slower than Zn and remained in the pits.•The corrosion rate of the Zn-3Ag-0.5Mg alloy after 180-day immersion was 21.6 µm/year.