Dresden 2009 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 20: Poster Session I
MM 20.8: Poster
Dienstag, 24. März 2009, 14:45–16:30, P4
Analysis of GPB zones of AlMgCu alloys — •Iris Kohlbach1, Björn Korff1, Benedikt Klobes1, Torsten Staab2, Matz Haaks1, and Karl Maier1 — 1Universität Bonn, HISKP, Nussallee 14-16, 53115 Bonn — 2Fraunhofer ISC, Neunerplatz 2, 97082 Würzburg
In contrast to the textbook example AlCu, early precipitation stages of AlMgCu alloys are not well understood. The first structures for early precipitates were proposed by Bagaryatsky in 1952 [1]. He suggested a local atomic order similar to the S-phase. However, this has not been confirmed until today. We studied Guinier-Preston-Bagaryatsky (GPB) zones by a comparison of several experimental und numerical methods. According to Bagaryatsky's original suggestion we calculated total and binding energies of several MgCu structures in the Al-matrix using the ab-initio code SIESTA. Unstable structures having negative binding energies are sorted out. Employing the resulting relaxed coordinates we computed positron annihilation (PAS) parameters and XAFS spectra using the codes DOPPLER and FEFF-8, respectively. These data are finally compared with experimental PAS results obtained in Bonn and XAFS spectra measured at BESSY in Berlin. We will present our suggested structures of early precipitates in AlMgCu alloys and introduce the relevant methods.
[1] Y. Bagaryatsky, Dokl. Akad. Nauk CCCP 1952, Tom 87 No. 4 559-562