Rapid screening alloying elements for improved corrosion resistance on the Mg(0001) surface using first principles calculations.

Abstract

The poor corrosion resistance of Mg alloys is a major challenge for their applications. The corrosion of Mg alloys is mainly controlled by the anodic dissolution of Mg and the cathodic hydrogen evolution reaction (HER), which is closely related to the stability and the hydrogen adsorption of the Mg surface. In this work, the effects of alloying elements (As, Ge, Cd, Zn, Ga, Al, and Y) on the stability and the hydrogen adsorption of a Mg(0001) surface have been studied based on first principles calculations. We have developed a horizontally integrated approach to evaluate their effects on corrosion resistance using parameters such as the surface energy, vacancy formation energy, Bader charge, electron density distribution, and the adsorption free energy of H atom at different adsorbed sites. We found that the doped atoms could significantly change the surface atomic structure and electron transfer on the Mg surface. These behaviors modified the energy required to detach the nearest neighbors of doped atoms from the Mg surface, the adsorption free energy of H atoms, and the stable adsorption sites of H atoms on the Mg surface, which regulate the corrosion resistance of Mg alloys. Interestingly, we found that Y doping on the Mg surface increased the corrosion resistance and our new method had tremendous potential in the rapid screening of alloying elements that could improve the stability of Mg alloys and inhibit the hydrogen evolution reaction.