Effect of Microstructure Refinement on the Corrosion Behavior of the Bioresorbable Mg-1Zn-0.2Ca and Mg-1Ca Alloys

This paper presents a comprehensive study of the effect of the processing by high-pressure torsion (HPT) on the corrosion behavior in Ringer's solution for two popular bioresorbable magnesium alloys-Mg-1Ca and Mg-1Zn-0.2Ca. Three states were studied for each alloy-the initial homogenized state, the as-HPT-processed state and the state after subsequent annealing at 250 and 300 degrees C. It is shown that HPT processing results in a very strong grain refinement in both alloys down to a mean grain size of about 210 nm for the Mg-1Ca alloy and 90 nm for the Mg-1Zn-0.2Ca alloy, but their corrosion resistance values differ significantly (by an order of magnitude). The conducted precision scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction studies demonstrate that such a difference in the corrosion behavior is conditioned by a difference in the morphology and origin of the nano-sized particles of second phases, as well as by a change in the electrochemical properties of the particle-alpha-Mg pair. The obtained results are discussed from the perspective of the innovative applications of biodegradable Mg alloys for the manufacture of advanced medical implants and products.

Automated summary

This paper presents a comprehensive study on the effect of high-pressure torsion (HPT) processing on the corrosion behavior of two bioresorbable magnesium alloys in Ringer's solution. The study shows that HPT processing can significantly refine the grain size of the alloys and has different effects on their corrosion behavior.