Icosahedral AlCuFe alloys : towards ideal quasicrystals

Abstract
The topological and chemical long range orders in the icosahedral Al 65Cu20Fe15 alloy have been studied by X-ray powder diffraction. The spectacular enhancement of the quasicrystal-line state by annealing of rapidly quenched samples have been quantitatively measured showing that the final annealed product fits the theoretical predictions of the ideal quasicrystal model within the instrument resolution. Whereas, after annealing at 1 073 K, Al 65Cu2oFe15 is two-phased — that makes difficult any fine study of the structure and the properties of the ideal icosahedral phase — a close composition Al63Cu25Fe12 leads to a single-phased icosahedral structure suitable for single quasicrystal X-ray and neutron diffraction analysis