Sulfidation–Oxidation Behavior of FeCrAl and TiCrAl and the Third-Element Effect

Short-term sulfidation–oxidation exposures were conducted under high pS₂ and low pO₂ conditions for TiCrAl and FeCrAl alloys at 600 and 800 °C. Low mass gains and submicron Al-and Ti-rich oxide scales were formed on TiCrAl at 600 °C, while high mass gains and FeS-based scale formation were observed for FeCrAl. Based on the good behavior of TiCrAl, third-element effect additions of Cr are not inherently detrimental under sulfidation–oxidation conditions. Rather, differences in the mechanistic action of the third-element addition of Cr between FeCrAl and TiCrAl alloys and its relevance to low oxygen potential sulfidation–oxidation environments were the key factors in determining whether or not a protective alumina scale was established.