Cytotoxicity and Corrosion Behavior of Magnesium and Magnesium Alloys in Hank's Solution after Processing by High‐Pressure Torsion

It is well‐known that processing by severe plastic deformation using high‐pressure torsion (HPT) promotes grain refinement and increases the strength of magnesium and its alloys. The present research is conducted to evaluate the effect of such processing on cytotoxicity and corrosion behavior in Hank's solution by using samples of commercial purity magnesium and AZ31, AZ91, and ZK60 magnesium alloys. All samples are subjected to electrochemical testing and hydrogen evolution testing before and after processing by HPT and the results show that this processing improves the corrosion resistance of pure magnesium, has no significant effect on the AZ31 and AZ91 alloys but reduces the corrosion resistance of the ZK60 alloy. The observations support the conclusion that grain refinement improves the corrosion resistance of metals with a tendency for passivation but impedes the resistance of metals without passivation. In addition, in vitro cytotoxicity tests are performed on the processed materials and show cell viability in all samples. The results demonstrate that HPT processing may be used to improve the performance of magnesium and its alloys as biodegradable implants.