Pitting corrosion of a Rare Earth Mg alloy GW93

• Published in: Journal of materials science & technology Vol. 33; no. 9; pp. 954 - 960
• Main Authors: Song, Yingwei, Shan, Dayong, Han, En-Hou
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2017
• Subjects: alloys; corrosion; Mg alloys; Oxide; Oxide films; phases; Pitting; Pitting corrosion; Second; Second phases; Second phases; Pitting corrosion; Oxide films; Mg alloys
• ISSN: 1005-0302; 1941-1162
• DOI: 10.1016/j.jmst.2017.01.014

Pitting corrosion of magnesium （Mg） alloys is greatly associated with their microstructure, especiallysecond phases. The second phases in traditional Mg alloys such as AZgl are electrochemically noblerthan Mg matrix, while the second phases in Rare earth （RE） Mg alloy GW93 are more active than Mgmatrix. As a result, the pitting corrosion mechanism of Mg alloy GW93 is different from the traditionalones. This paper aims to clarify the pitting corrosion mechanism of Mg alloy GW93 through the studies ofVolta potential by Scanning Kelvin Probe Force Microscopy （SKPFM）, corrosion morphology by ScanningElectron Microscope （SEM）, and corrosion resistance by electrochemical tests. Results reveal that thepitting corrosion of GW93 includes three stages, first, dissolution of the second phases, followed bycorrosion of Mg matrix adjacent to the dissolved second phases, and finally, propagation of corrosion pitsalong the depth direction of the dissolved second phases. Anodic second phases and enrichment of CI-in the thick corrosion product films dominate the propagation of pitting corrosion.