An investigation of the corrosion mechanisms of WE43 Mg alloy in a modified simulated body fluid solution: The influence of immersion time

•A corrosion mechanism of WE43 Mg alloy in m-SBF is provided.•The time-dependent behaviour of impedance parameters is analysed.•Changes in the impedance response are related to four stages of corrosion.•Corrosion rates obtained by EIS, H2 evolution and ICP-OES show a good agreement.•Additional indirect evidence on the presence of a passive inner film is provided.

The corrosion mechanisms and kinetics of WE43 Mg alloy in a modified simulated body fluid (m-SBF) are investigated by electrochemical, hydrogen evolution and analytical techniques. The changes in the impedance response over time are related to four corrosion stages involving the formation of a partially protective corrosion layer and adsorption of Mg intermediates, formation of an inner passive MgO layer with increasing coverage over time, rupture of the corrosion layer and lateral growth of stable pits. ATR-FTIR, XRD and XPS results show the presence of an amorphous carbonated apatite/Mg(OH)2 mixed corrosion layer.