Characterisation of iron archaeological analogues using micro diffraction under synchrotron radiation. Application to the study of long term corrosion behaviour of low alloy steels

Last progresses in synchrotron radiation focusing allow the characterisation on microscopic samples. The use of X Ray micro diffraction (μXRD) in two corrosion studies (indoor atmospheric corrosion and in soil corrosion) concerning iron archaeological artefacts is presented. This analytical method permits to locate and identify very precisely the constitutive phases of the corrosion products. For the atmospheric corrosion study, semi quantitative data were presented to assess the proportion of the different identified phases in the rust layers. For the in soil corrosion study, the precise distribution of corrosion products formed on the nine analysed artefacts is given.