Formation process and structural changes of iron rust

Recent works on formation processes of iron corrosion products are reviewed. Although green rust (GR) is sometimes observed as intermediate corrosion products of iron based alloys, it is easily transformed to ferric oxyhydroxides such as goethite and lepidocrocite through the aerial oxidation. This is because GR contains ferrous ions which are oxidized to ferric ions in aqueous solution. In particular, the characteristic features of the structure and transformation of GR are overviewed in this paper.