Investigating ion release using inline ICP during in situ scratch testing of an Mg-Li(-Al-Y-Zr) alloy

• Published in: Electrochemistry communications 2019-02, Vol.99, p.46-50
• Main Authors: Yan, Yuanming, Zhou, Peng, Gharbi, Oumaïma, Zeng, Zhuoran, Chen, Xiaobo, Volovitch, Polina, Ogle, Kevin, Birbilis, Nick
• Format: Article
• Language: English
• Subjects: Electrochemistry; In situ; Magnesium; Magnesium‑lithium alloy; Online ICP
• ISSN: 1388-2481; 1873-1902
• DOI: 10.1016/j.elecom.2019.01.001

An electrochemical flow cell was constructed to permit the application of a mechanical scratch to the exposed material while monitoring the open circuit dissolution rates of the elemental alloy components. Elemental dissolution rates were determined where measured downstream using inductively coupled plasma atomic emission spectrometry (ICP-AES). The technique is demonstrated with Mg-Li(-Al-Y-Zr) alloy exposed to 0.01 M NaCl. A mechanical scratch was applied manually using a non-conductive and non-contaminating sapphire lancet without interrupting the on-line measurement. The ion dissolution rate from the newly exposed surface was significantly higher than the dissolution rate from the remaining surface area, corresponding to a high local current density. Notably, the increase in the dissolution rate from the scratched area occurred gradually after the scratch; then subsided within 200 s after the scratch, indicating that this particular Mg-alloy can repassivate by the formation of a surface film after a scratch was applied. This is the first reported use of an in situ scratch cell coupled with ICP-AES. •The development of an open flow cell techniqe could permit in situ scratching of an alloy surface.•Ion release arising from surface scratching and subsequent repassivation were capable of being monitored.•It was revealed that the Mg-Li(-Al-Y-Zr) alloy can repassivate in response to a defect.