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Surface properties of magnesium improved by Sr ion implantation

Strontium (Sr) ion implantation was conducted to improve the surface properties of pure magnesium through a metal vapor vacuum arc (MEVVA) ion implantation. The x-ray photoelectron spectroscopy investigation demonstrated a Sr-implanted layer of approximately 30 nm in thickness formed on the pure Mg surface and Sr element content as a function of the depth in modified layer was similar to a Gaussian distribution. The atomic force microscopy analysis indicated that the roughness value of the pure Mg apparently decreased and the surface became smoother subsequently to Sr ion implantation. Besides, the nanoindentation measurements demonstrated that the elastic modulus and hardness value of the Sr-implanted Mg were both higher than those of pure Mg. Furthermore, compared with untreated Mg, the Sr-implanted Mg exhibited a more positive corrosion potential and a lower corrosion current density in electrochemical tests, and fewer corrosion damage after 12 h immersion tests in SBF. The results suggested that the corrosion resistance and mechanical properties of pure Mg could be improved through Sr ion implantation.