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Title: Atomic structure of pre-Guinier-Preston zones in Al alloys
Author(s): T. E. M. Staab Person, M. Haaks Person, C. Zamponi Person, H. Modrow and K. Maier Person
Journal: Phys. Status Solidi: RRL
Year: 2007
Volume: 1
Issue: 5
Pages: 172--174
DOI: 10.1002/pssr.200701090
File URL: http://onlinelibrary.wiley.com/doi/10.1002/pssr.200701090/abstract
Abstract: 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. Atomic structure of a pre-GPZ from SIESTA: a small disk of five Cu atoms (red) on a 100 plane in fcc Al (blue). Note that Al atoms in direct neighborhood of copper relax towards the small Cu disk. (online colour at: www.pss-rapid.com) (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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