Local atomic structure in iron copper binary alloys: An extended X-ray absorption fine structure study

Understanding the clustering process and the evolution of the precipitate structure of copper in Fe–Cu system is an important step in the description of material hardening and the embrittlement process normally observed under irradiation conditions. In this work, an extended X-ray absorption fine structure (EXAFS) spectroscopy characterization of Fe–0.3 wt%Cu and Fe–1.0 wt%Cu binary model alloys has been performed in order to investigate the local structure around Cu and Fe atoms in the matrix. The effect of thermal ageing was studied on one Fe–Cu specimen containing 1.0 wt% Cu annealed at 775 K for a duration of 1 h. The near-neighbour environment of Cu and Fe was examined by determining the best-fit structural parameters after curve fitting to the first-few-shells EXAFS functions. The results provide an indication of the formation of sub-nanometer-size Cu clusters in Fe matrix for the specimens examined. The average structural parameters estimated from the EXAFS data are presented and discussed.