Electron and Ion Spectroscopic Studies of the Passive Film on Iron‐ Chromium Alloys

Binary iron‐base alloys containing chromium additions of 3, 9, 12, and 18% were passivated in borate buffer ( p H 8.4). The passive films formed on these alloys were investigated by Auger, ESCA, and SIMS techniques. For the Fe‐3Cr alloy passivated in the potential range 0.65–1.45V vs. RHE, the Auger spectra showed negligible Cr in the passivation layer. For the Fe‐9Cr, Fe‐12Cr, and Fe‐18Cr alloys, the Cr content was lower at the surface of the passive film and passed through an apparent maximum within the film. ESCA measurements indicate that the passive film of Fe‐18Cr alloy has a higher content of bound water in the form of OH − than Fe‐3Cr alloy. The SIMS results for the Fe‐Cr alloys generally confirm the relative measurements of Cr in the passive film found from Auger measurements.