Regensburg 2002 – wissenschaftliches Programm
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M: Metallphysik
M 23: Symposium on Structurally Complex Alloy Phases V (SCAP V)
M 23.2: Fachvortrag
Donnerstag, 14. März 2002, 17:30–17:45, H16
Complex compounds in Al-Cr-Fe system — •Valerie Demange1, Jaafar Ghanbaja2, Francis Machizaud3, and Jean-Marie Dubois3 — 1Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, — 2UHP Faculte des Sciences Bd des Aiguillettes, 54500 Vandoeuvre-les-Nancy, France — 3LSG2M Ecole des Mines Parc de Saurupt 54042 Nancy, France
The Al-Cr binary system is well known to show several stable or metastable complex compounds which are related to quasicristalline phases and are therefore called approximants. Approximants, on their part, represent a class of highly complex intermetallic compounds. For the Al-rich corner of the Al-Cr-Fe ternary system, it has been shown that the solubility of the third element in the binary structures is large, in particular for the structures of the Al-Cr system, like Al8Cr5 (rhombohedral) and Al9Cr4 (cubic) γ-brass phases. We have studied this part of the ternary diagram and observed several new approximants of the decagonal phase. These phases possess orthorhombic and monoclinic structures and show mutual orientation relationships. We have furthermore investigated the structural features of the γ-brass phases which are closely related to orthorhombic approximants. Finally, a cubic superstructure of the γ-brass was obtained by annealing an Al-Cr-Fe thin film. This superstructure which shows a pseudo-tenfold symmetry can be considered like an approximant of the decagonal phase as well.