The role of β1′ precipitates in the bio-corrosion performance of Mg-3Zn in simulated body fluid

Mg-Zn alloys are promising candidate materials for medical applications. The bio-corrosion performance of Mg-3 wt% Zn has been studied at 37 °C in simulated body fluid (SBF) using immersion tests and electrochemical measurements. Heat treatments (solution treatment and ageing) were used to alter the microstructure and adjust the volume fraction of precipitates. It has been found that, in the solution treated sample, the dissolution of (α-Mg + MgZn) eutectic phases led to a low corrosion rate (3.05 ± 0.20 mL/cm2/day). The volume fraction of precipitates increases with ageing time at 160 °C and causes the corrosion performance to deteriorate because of micro-cathodic effects. Thus the aged sample with the largest volume fraction of precipitates exhibits the worst corrosion resistance (4.65 ± 0.01 mL/cm2/day).