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

• Published in: Corrosion science 2018-05, Vol.136, p.106-118
• Main Authors: Zhang, Yu, Gore, Poorwa, Rong, Wei, Wu, Yujuan, Yan, Yuanming, Zhang, Ruifeng, Peng, Liming, Nie, Jian-Feng, Birbilis, Nick
• Format: Article
• Language: English
• Subjects: A. Magnesium; Alloys; B. STEM; Beta phase; Bronze; C. Anodic dissolution; C. De-alloying; C. Segregation; Corrosion; Corrosion inhibitors; Corrosion rate; Corrosion resistance; Gadolinium; Localized corrosion; Zirconium base alloys
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2018.02.058

•A quasi-in-situ STEM-EDS approach is used to study micro-galvanic corrosion.•Segregation of oxygen at the interface between the α-Mg matrix and β phase is detected following corrosion.•The re-deposition of Ag is observed on the nanoscale.•The Ag addition contributes to enhanced localised corrosion. 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.