Atomic insight into iron corrosion exposed to supercritical water environment with an improved Fe-H2O reactive force field

Waterside anti-corrosion of Fe-based alloys is one of the great challenges for supercritical water reactors. Herein, an improved Fe-H2O reactive force field (ReaxFF) is constructed to understanding the Fe corrosion mechanism at the atomic scale. Using molecular dynamics simulations, the corrosion of Fe (1 0 0) and Fe (1 1 0) in supercritical water was investigated. It was found that oxidation and hydrogen evolution reactions occurred along with Fe dissolution; the corrosion rate on Fe (1 0 0) was faster than that on Fe (1 1 0) in the early stage, but the reverse occurred on a longer time scale; and the precipitation of ferrous hydroxide at the initial stage led to the formation of an oxidation layer, where FeO and Fe3O4 were the dominant products. The present ReaxFF can become a crucial tool for corrosion research on Fe-based alloys.