Quasi-in-situ STEM-EDS insight into the role of Ag in the corrosion behaviour of Mg-Gd-Zr alloys

The present paper reports a quasi-in-situ STEM-EDS approach for studying the role of Ag in the corrosion behaviour of Mg-Gd-Zr alloys. Following corrosion, the segregation of O at the interface of the α-Mg matrix and the β phase was observed. Furthermore, Ag-rich particles and the re-deposition of Ag were also observed on the nanoscale. Based on quasi-in-situ STEM-EDS observations herein, the partitioning of Ag into the β phase leads to enhanced localised corrosion, whilst the subsequent formation of Ag-rich particles during the corrosion process leads to enhanced rate of corrosion propagation, with accompanying oxy-hydroxide formation observed upon the Mg-Gd-Ag-Zr.