Influence of the Oxygen Induced Surface Segregation Process of Solutes on the Anti-corrosion Properties of the Fe–Cr and Fe–Cr–Si Alloys.

The influence of the oxygen-induced surface segregation process of Cr and Si solutes on the anti-corrosion properties of Fe–Cr and Fe–Cr–Si alloys was studied using X-ray photoelectron spectroscopy (XPS) and ⁵⁷Fe transmission Mössbauer spectroscopy (TMS). To select the optimal procedure for preparation of the studied alloys with the highest possible surface concentrations of both solutes, the samples were prepared by various thermal treatments. The XPS results clearly show that despite the initial surface segregation during the samples preparation, the additional thermal treatment at 900 K greatly enhances this process. Moreover, it was proved that to get the most efficient segregation, the surfaces of the alloys must be covered by oxygen during the additional annealing. The samples with the highest surface concentration of Cr and Si solutes were oxidized in air at 870 K, and their anti-corrosion properties were characterized by TMS. It was found that the additional thermal treatment at 900 K significantly improved the corrosion resistance of all studied alloys. Furthermore, it can be concluded that it is possible to reduce the Cr and Si content in properly prepared alloys without deteriorating their anti-corrosion properties. [ABSTRACT FROM AUTHOR]