Investigation of corrosion behavior of Mg-6Gd-3Y-0.4Zr alloy in Xisha atmospheric simulation solution

The corrosion behavior of Mg-6Gd-3Y-0.4Zr alloy (GW63K Mg alloy) was investigated by using scanning electron microscope (SEM), X-Ray Diffraction (XRD), Scanning Kelvin Probe Force Microscopy (SKPFM), Immersion tests, Raman spectrum analysis and Electrochemical measurements. The results show the main phases in the alloys were Mg matrix phase and the second phases Gd-Y rich phase (Mg24Y5 or Mg-24(Gd, Y)(5)). The Gd-Y rich phase in GW63K Mg alloy was more active than Mg matrix. The corrosion of GW63K Mg alloy included three stages. First, the surface of Mg alloy generated some corrosion products and the Gd-Y-rich-phases are preferentially dissolved; Second, corrosion propagates horizontally around the dissolved Gd-Y-rich-phases; Finally, the corrosion of Mg matrix was along the depth direction of the dissolved second phases. Even generated some pitting or corrosion along the second phases.