The role of biological environments on magnesium alloys as biomaterials

Magnesium and magnesium alloys are of special interest as structural materials, since their high specific strength enables them to be applied as implants. During this research, corrosion of magnesium alloys AZ91D and AM50 was investigated in vitro by electrochemistry techniques in solutions replicating the body's environment. Although actual corrosion resistance of a material can only be proven through long-term clinical trials in vivo, accelerated laboratory tests in vitro were used to predict certain effects. The purpose of our research was to find the correlation between biological environments, corrosion exposure, and magnesium alloys. Die-cast magnesium alloys AZ91D and AM50 were used since they have known microstructures. The behavior of these alloys in 0.9% NaCl solution and HANKS' balanced salt solution was studied by electrochemical impedance spectroscopy (EIS) using different physiological solutions, including fetal calf serum (FCS), at different temperatures as well as an external pH control. We have manufactured a unique system to form a bio-reactor in which key parameters of a solution were adjusted, and an electrochemical cell, in which measurements were made. The results show that magnesium alloys can act as biodegradable materials which should be designed based on consideration of microstructure and environmental degradation processes.