Change in the Morphology of Alloy Corrosion Products Based on the FeAl Intermetallic Phase After Oxidation in Water Vapor at a Temperature of 700 °C for up to 2000 h

The surface of the Fe40Al5Cr0.2TiB alloy, after oxidation in steam at 700 °C, showed a varied morphology dependent on oxidation time. Initially, a fine, acicular oxide layer formed, which over time transformed into a more compact, lumpy structure corresponding to the α-Al2O3 phase. EDS analysis confirmed the dominance of aluminum and oxygen in the oxidation products, and XRD studies revealed the presence of the α-alumina phase. Optical profilometry revealed a significant increase in roughness parameters (Ra and Rz) after long-term exposure (2000 h), which correlates with the thickening and sinterization of the oxide layer. The obtained results indicate that in a water vapor environment, a stable α-Al2O3 phase can already be formed at a temperature of 700 °C, and its development leads to increased roughness.