Corrosion Behavior and Mechanism of Carbon Ion-Implanted Magnesium Alloy

Carbon ion implantation was conducted on an AM60 magnesium alloy with fluences between 1 × 10¹⁶ and 6 × 10¹⁶ ions/cm² and an energy of 35 keV. The microstructure and electrochemical properties of the samples were systematically characterized by X-ray photoelectron spectroscopy, X-ray diffraction, Raman scattering, scanning electron microscopy, transmission electron microscopy, and electrochemical methods. These studies reveal that a 250 nm-thick C-rich layer is formed on the surface and the Mg₂C₃ phase embeds in the ion-implanted region. The crystal structure of the Mg₂C₃ was constructed, and an electronic density map was calculated by density-functional theory calculation. The large peak in the density of states (DOS) shows two atomic p orbitals for Mg₂C₃. The main electron energy is concentrated between -50 and -40 eV, and the electron energy mainly comes from Mg (p) and Mg (s). The electrochemical experiments reveal that the E_corr is -1.35 V and I_corr is 20.1 μA/cm² for the sample implanted with the optimal fluence of 6 × 10¹⁶ ions/cm². The sample from C ion implantation gives rise to better corrosion resistance.