Abstract
In this study, lean quaternary magnesium alloys with nominal compositions (wt%) of Mg-1Zn-0.5Mn-0.3Ce (Mg-Zn-Mn-Ce), Mg-1Zn-0.2Ca-0.3Ce (Mg-Zn-Ca-Ce) and Mg-1Zn-0.2Ca-0.5Mn (Mg-Zn-Ca-Mn) were produced using permanent mould direct chill casting and the corrosion behaviours up to 168 h of immersion in phosphate buffer solution (PBS) at 37 °C were investigated. Various techniques were employed to conduct corrosion tests, including weight loss, hydrogen evolution, inductively coupled plasma optical emission spectroscopy (ICP-OES) to quantify the amount of released Mg during both static immersion tests and downstream analysis using a flow cell, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The obtained data was analysed in detail to compare the corrosion resistance of the three magnesium alloys and the effectiveness of the various test methods. Among the studied alloys, the Mg-Zn-Mn-Ce alloy exhibited the highest dissolution rate during the initial immersion period. However, a substantial improvement in the corrosion resistance was observed for this alloy, especially after 24 h of immersion due to the formation of a dense and compact protective surface film. Additionally, the Mg-Zn-Ca-Mn alloy displayed better corrosion resistance compared to the Mg-Zn-Ca-Ce alloy for immersion durations up to 24 h, above which it significantly decreased.
DOI Link to Publication