Surface Segregation Process and Its Influence on High-Temperature Corrosion of Iron-Based Alloys Containing...

The surface segregation process and its influence on high-temperature corrosion of five alloys-Fe_0.95Al_0.05, Fe_0.95V_0.05, Fe_0.90Al_0.05V_0.05, Fe_0.95Ti_0.05 and Fe_0.95Ge_0.05-were studied using X-ray photoelectron spectroscopy (XPS) and ⁵⁷Fe Transmission Mössbauer Spectroscopy (TMS). To prepare the alloys with the highest surface concentration of solutes, the samples were annealed at elevated temperatures to induce the surface segregation process. After that, they were exposed to air at 870 K for 1 and 5 h. It was found that the Fe_0.95Ti_0.05 sample annealed at 1073 K had much better anti-corrosion properties than other alloys studied. This finding can be correlated with the extremely high concentration of titanium on the surface, which was more than four times that of iron. In contrast to other alloys studied in this work, the passive layer formed on the surface of Fe_0.95Ti_0.05 greatly enhanced its resistance to corrosion.