About γ-brass phases in the Al–Cr–Fe system and their relationships to quasicrystals and approximants

Abstract

We have identified two γ-brass phases in the Al–Cr–Fe system by X-ray diffraction and transmission electron microscopy. These structures (rhombohedral and cubic) are closely related to each other and can co-exist in the same alloy together with approximants of quasicrystals. In particular, a long-period superlattice, typical of γ-brass phases, was characterized in the cubic structure. This superstructure is constituted of inversion domains separated by boundaries lying at (

10) planes. The displacement vector between like domains was determined from high resolution microscopy data. This study deals also with a description of some structural links between γ-brass phases and approximants of decagonal and icosahedral quasicrystals.

Acknowledgements

The authors thank J.B. Ledeuil for microprobe analysis. They gratefully acknowledge the financial support offered to one of us (V. D.) by Région Lorraine and Saint-Gobain Recherche as well as by the French Ministry of Research and New Technologies under contract “ERT Quasicristaux Industriels”.