Application of quantitative X‐ray photoelectron spectroscopy (XPS) imaging: investigation of Ni‐Cr‐Mo alloys exposed to crevice corrosion solution

This paper explores quantitative X‐ray photoelectron spectroscopy imaging on three different Ni‐Cr‐Mo Hastelloy® alloys (BC‐1, C‐22 and G‐30) with differing Cr and Mo contents. The alloys were subjected to a simulated critical crevice corrosion solution. Ni‐based alloys have been shown to exhibit excellent resistance to a range of corrosive media due to the formation of an inert oxide layer, primarily containing Cr and Mo. However, these alloys may rapidly corrode in the crevice environment produced by seams, gaskets or deposits of debris on the alloy surface. Understanding how the oxide film is influenced by the Cr and Mo content is crucial in determining an optimal alloy composition that reduces or suppresses the possibility of crevice corrosion. The protective oxide films are very thin in nature, generally several nanometers. XPS imaging was used to monitor changes in oxide film composition and to correlate the distribution of Cr and Mo to the grain structure of the alloys.