X-ray photoelectron spectroscopy study of the carburization of the nickel-based alloy Haynes 214

X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to investigate the surface composition and the microstructure of Haynes 214 Ni-based alloy after 500 h cyclic exposure to two carburizing atmospheres: CH4 (2%)–H2 (98%) at 800 °C, and CH4 (10%)–H2 (90%) at 1100 °C. The depth distribution of various elements in the surface region was obtained by XPS after successive cycles of argon etching. The results showed that during the treatment at 800 °C chromium diffuses to the surface and forms carbides particles that partially cover the surface of the alloy. The uncovered parts of the surface were depleted from chromium and enriched with aluminum and silicon oxides. After exposure at 1100 °C a continuous alumina layer was formed and no carbides were detected. The XPS depth profiles showed that the region below the alumina/alloy interface was depleted from chromium and enriched with iron.