2011 Volume 51 Issue 1 Pages 93-98
Micro-beam X-ray fluorescence (XRF) and X-ray absorption fine structure (XAFS) techniques have been applied, for the first time, to the cross sections of a rust layer on a weathering steel exposed for 38 years to the atmospheric environment. Elemental mapping and Fe–K edge XAFS spectra were measured with a spatial resolution of about 3 μm by an X-ray micro beam formed by a K–B mirror with the synchrotron radiation. Cr distribution, including layered patterns in the rust layer, was clearly observed by the micro-beam XRF imaging. The combination of micro-XRF and extended X-ray absorption fine structure (EXAFS) analysis on identical analytical points has demonstrated that the crystallinity of α-FeOOH is strongly related to the Cr concentration. The XRF and XAFS results are presented and discussed in terms of the analytical techniques and the relationship between the crystal structure of the rust and the Cr concentration.