Corrosion characteristics of two rare earth containing magnesium alloys

Magnesium (Mg) based alloys have received prevalent attention, especially in the biomedical, aerospace and automotive industries due to their low density, moderate strength and natural ability to degrade. However, widespread use of Mg-based alloys as degradable biomedical implants still remains a significant technological challenge because of their rapid corrosion kinetics that leads to premature loss of mechanical integrity. Addition of certain alloying elements such as Zinc and Rare Earth Elements (REs) improve the mechanical and corrosion response of Mg alloys. In this paper, the mechanical and corrosion characteristics of two commercially available RE containing Mg alloys, ZE41 and EZ33 are studied. Results obtained using hydrogen evolution, weight-loss measurements, and electrochemistry (PD and EIS) in comparison with pure Mg data are presented here. These initial findings indicate that although, ZE41 and EZ33 have the same primary alloying elements, due to the addition of REs, differences in composition, nature of precipitates and passivating layer play a key role in positively impacting the corrosion behavior and hence, the corrosion rate.