Atomic structure of pre-Guinier-Preston zones in Al alloys

We propose X‐ray absorption (XAS) measurements as a novel approach to determine the atomic structure of pre‐Guinier–Preston zones. These nano‐clusters are formed during very early stages of aging AlCu alloys, immediately after solution heat treatment and quenching. X‐ray absorption near‐edge structure (XANES) spectra were taken from technical aluminum alloys at the copper K edge, revealing the local atomic environment of copper. The spectra of – after solution heat treatment – freshly quenched and of artificially aged alloys differ significantly from each other. We compare the measured XANES spectra with those calculated by the FEFF‐8 code. We show the importance of employing realistic, i.e. relaxed, atomic coordinates around the scattering atom type from ab‐initio calculations with SIESTA. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) The Letter by Staab et al. combines first principles calculations using the numerical ab‐initio method SIESTA with the analysis of X‐ray absorption near‐edge structure (XANES) spectra. The work clearly elucidates the microscopic structure of pre‐Guinier–Preston zones – nanometer‐sized Cu precipitates – in AlCu alloys.