The influence of surface Fe on the corrosion of Mg

Iron is a common impurity in magnesium alloys, and is acknowledged to accelerate Mg corrosion, contributing to Mg's poor corrosion resistance. However, an atomistic understanding of this acceleration effect is still incomplete. Here we use Density Functional Theory simulations performed with the Quantum Espresso package to investigate several Fe/Mg models, calculating the associated work functions, atomic charges, and H and Fe absorption energies. Compared with a pure Mg slab, we find that Fe's existence increases the work function and decreases the H adsorption energy. Furthermore, a general trend is observed that the Fe absorption energy decreases with increasing interaction between Fe atoms on the Mg substrate. Based on these results, a mechanism based on charge redistribution is put forward to explain how Fe accelerates the corrosion of Mg. Our findings provide insight into Mg's corrosion process at the atomic level that might inform future measures to prevent corrosion.

Automated summary

This study investigates the effect of iron impurities on the corrosion of magnesium alloys using Density Functional Theory simulations. The presence of iron is found to increase the work function of magnesium and decrease the adsorption energy of hydrogen. Furthermore, it is observed that the absorption energy of iron decreases with increasing interaction between iron atoms on the magnesium substrate. These findings provide insight into the atomic-level mechanism of magnesium corrosion.