Severe Plastically Deformed Mg–Zn–Zr–RE Alloy Developed as a Biomaterial

Mg alloys have high corrosion rate that inhibits their application as biomaterial. For safe use as biomaterial, it is essential to control their corrosion rates. In Mg alloys, microgalvanic coupling between the α-Mg matrix and secondary precipitates can exist which results in increased corrosion rate. To address this challenge, we engineered the microstructure of a biodegradable Mg–Zn–RE–Zr alloy by severe plastic deformation process such as friction stir processing (FSP), improving its corrosion resistance and mechanical properties simultaneously. Subjecting the alloy to FSP resulted in refined grains, basal texture and broken and uniformly distributed secondary precipitates. In vitro corrosion of base material showed microgalvanic coupling between precipitate and matrix, resulting in unstable surface layer. The processed alloy showed uniform corrosion owing to formation of stable surface film formation, due to the refined grains, texture, and distribution of precipitates. The results show promising potential of Mg alloy as biomaterial.