An Experimental Survey of Anodically Enhanced Cathodic Kinetics of Magnesium Alloys

The anodically enhanced cathodic kinetics behavior of 18 different Mg alloys encompassing high-purity Mg, Mg-Al, Mg-Zn, Mg-Sn, and Mg-RE (RE = rare earth element)-based alloys was studied via global and local electrochemical methods in unbuffered 0.6 M NaCl. The total cathodic enhancement observed for Mg-Al and Mg-Sn alloys was found to decrease with increasing primary alloy content, whereas the cathodic activity of Mg-Zn-based alloys increased with alloying content. Furthermore, a lower fraction of secondary phases expressed as a volume fraction present generally led to lower susceptibility toward anodically enhanced cathodic kinetics. The variations in enhanced cathodic activity were attributed to the identity of the primary alloying element, microstructure, and nature of the dissolution product film.