Corrosion properties of bioresorbable Mg-Zn-Zr-Ce alloy in coarse-grained and ultrafine-grained states

The results of the study of corrosion properties of a bioresorbable Mg-Zn-Zr-Ce magnesium alloy in coarse-grained (CG) and ultrafine-grained (UFG) states are presented. A solution of 0.9 wt.% NaCl (NaCl) and phosphate-buffered saline (PBS) is used as the corrosion medium. An ambiguous corrosion behavior of the alloy depending on its structural state and type of corrosion medium is revealed. The most favorable corrosion performance is observed for the UFG state of the Mg-Zn-Zr-Ce alloy held in the PBS solution for a period of 14 days. The mass gain of UFG alloy samples in this solution is 0.2%, while the mass loss of CG alloy samples is 0.5%. In the NaCl solution, the mass loss of UFG and CG alloy samples is comparable, being 0.3%. A distinctive feature of the corrosion behavior of the Mg-Zn-Zr-Ce alloy in both CG and UFG states in NaCl is the uneven dissolution of the samples compared to their dissolution in PBS. It is shown that the corrosion layer of the UFG alloy after tests in both PBS and NaCl twice as thin as the corrosion layer of the CG alloy, which is attributed to the formation of a passivation layer on the surface of the UFG samples due to the defect structure.