Roles of the micro‐arc oxidation coating on the corrosion resistance and mechanical properties of extruded Mg–2Zn–0.5Zr–1.5Dy (mass%) alloy

Aiming to enhance the biodegradable magnesium alloys' poor mechanical properties and corrosion resistance in aggressive chloride mediums, micro‐arc oxidation coatings with oxidation times range from 3 to 15 min were prepared on the surface of extruded Mg–2Zn–0.5Zr–1.5Dy (mass%) alloy. Assessments were carried out using electrochemical experiments, hydrogen evolution experiments, and tensile tests, respectively. The results show that the micro‐arc oxidation coating is porous and mainly consists of the MgO phase. When the oxidation time increases from 3 to 15 min, the thickness and the pore size of the coating increase, while the coating's porosity decreases. The coating with the oxidation time of 15 min can effectively prevent the formation of pitting holes on the surface of the alloy, which remarkably reduces the decay rate of ultimate tensile strength, yield strength, and elongation of the alloy after immersion in simulated body fluid for 0–28 days, and keep the alloy with higher and more stable corrosion resistance. This increases the application possibility of extruded Mg–2Zn–0.5Zr–1.5Dy alloy as a biodegradable material.