The investigation of corrosion mechanisms of magnesium alloys in artificial body fluid

Metals are indispensable materials used in almost all sectors. However, metallic materials lose their properties over time due to corrosion, a dynamic process that takes place in all environmental conditions and even in the human body. The fluid medium in the human body contains various ions, such as water, dissolved oxygen, chloride, and hydroxide, making it a highly corrosive environment for metals used as biomaterials, although metallic materials are still used as biomaterials due to their advantages. One such metal is magnesium and its alloys, which are prone to corrosion in both physical and physiological environments. In this study, the effect of chemical surface modification with NaOH and H2O2 on the corrosion mechanism of AZ31, AZ61, AZ63, and ZM21 magnesium alloys, which have been studied as biomaterials in recent years, was investigated in simulated body fluid (SBF). The corrosion mechanism was elucidated by pH measurements, hydrogen gas output measurements, and electrochemical methods such as Electrochemical Impedance Spectroscopy (EIS), Tafel Extrapolation (TP), and Dynamic Electrochemical Impedance Spectroscopy (DEIS). The morphological changes on the alloys' surface were then determined using Scanning Electron Microscopy (SEM), Energy Dispersion Spectrometer (EDAX), X-Ray Diffraction Method (XRD), Atomic Force Microscopy (AFM), Optical Profilometer (OP), and Atomic Absorption Spectroscopy (AAS). The results of these methods were used to further understand the corrosion behavior of magnesium alloys as potential biomaterials. The findings obtained indicate that among the investigated samples in the SBF solution, the most corrosion-resistant alloys are, respectively, AZ61, AZ63, AZ31, and ZM21. It is also observed that the chemical surface modification enhances the corrosion resistance of all alloys, with H2O2 (AZ31, AZ61, AZ63) and NaOH (ZM21) being effective in certain samples.