Regensburg 2004 – wissenschaftliches Programm
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M: Metallphysik
M 8: Phasenumwandlungen I
M 8.1: Vortrag
Montag, 8. März 2004, 14:45–15:00, H4
Precipitates in Al-Li: The existence of a precursor phase — •Stefan Müller1, Walter Wolf2, and Raimund Podloucky3 — 1Universität Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen — 2Materials Design s.a.r.l., 44.av.F.-A. Bartholdi, 7200 Le Mans, France — 3Universität Wien, Institut fuer Physikalische Chemie, Liechtensteinstr. 22A, A-1090 Wien
Although it is generally believed that the δ′ phase of Al3Li is directly formed from the fcc-based α solid solution by quenching and aging the sample, X-ray small angle scattering results report the existence of a precursory structure in the early stage of the decomposition. By combining density functional theory calculations with a mixed-space cluster expansion and Monte-Carlo simulations we will show that the existence of such a precursor phase sensitively depends on the chosen Li-concentration. Our calculations allow to predict the ground-state diagram, short-range ordering, the size-shape-temperature relation of the L12 precipitates, as well as the coherent phase boundaries for both the precursor phase and the δ′ phase.