In vitro corrosion behavior of the extruded Mg–4Zn–1Mn alloy in different physiological solutions for biomedical applications

The extruded Mg–4Zn–1Mn alloy was prepared and its in vitro corrosion behavior in different physiological solutions of simulated body fluid (SBF), artificial saliva (AS) and artificial urine (AU) was investigated for biomedical applications. The microstructural characterization by optical microscope (OM), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS) showed that the alloy with an average grain size of approximate 20 ​μm was mainly composed of α-Mg matrix phase along with some MgZn₂ and α-Mn precipitates. The results of electrochemical corrosion and immersion corrosion tests revealed a distinct corrosion behavior for the alloy in different solutions with increasing immersion time. The corrosion morphologies were featured with flocculent precipitates in the SBF, flower-like clusters in the AS and columnar crystals in the AU. The alloy exhibited highest corrosion resistance and lowest corrosion rate in the AS compared with the SBF and the AU, which was attributed to the formation of a stable corrosion products layer.