In situ structural analysis of corrosion products formed on the surfaces of iron‐based alloys

Abstract

AbstractIn situ X‐ray diffraction measurements were performed for analyzing the constituent species of corrosion products freshly formed on the surfaces of pure iron and iron‐based alloys, namely, iron − 0.58 mass% phosphorus and iron − 3.2 mass% molybdenum. As these elements are often added into corrosion‐resistant steels, their influence on the constituent species of the corrosion products was studied. The sample surfaces were corroded by dropping an NaCl aqueous solution and cyclically exposing them to wet and dry atmospheres. The results revealed that γ‐FeOOH was formed as the main corrosion product on the surface of the iron‐based alloys, and small amounts of species such as green rust (GR), and magnetite were formed depending on the addition of the alloying elements. It is considered that the formation of different constituent species of the corrosion products is influenced by the alloying elements in the corrosion products. It was shown that in situ X‐ray diffraction measurements enable us to obtain information on different species in the corrosion products formed under various conditions. Copyright © 2008 John Wiley & Sons, Ltd.