First-principles study on the corrosion resistance of iron oxide surface and grain boundary in austenitic steel to lead-bismuth eutectic

In this paper, the corrosion properties of austenitic steel with and without protection of Fe3O4 scale was investigated based on first-principles calculations. The results show that lead-bismuth eutectic (LBE) is only adsorbed at some local positions on Fe3O4 scale, but is stably adsorbed at various sites on the Fe surface. The adsorption of LBE reduces the escape energy of Fe on Fe3O4 scale and pure Fe surface, and pure Fe surface is more susceptible to LBE corrosion. Moreover, the interaction between common alloying elements (Ni, Cu, Mo, Mn, Cr, Nb, V, Si, and Al) and oxygen atoms are investigated. Among them, Ni and Cu are weakly bound to O and most prone to escape from the Fe3O4 scale. Mo, Mn, and Cr have a significant escape tendency, while Nb, V, Si, and Al are not susceptible to escape. LBE will embrittle the grain boundary (GB) under failure of oxide layer. Ti, Cr and Ni all improve the strength of the GB structure, but the strengthening effect is limited, and GB embrittlement is dominated by Pb and Bi.