Investigations of the short-range order in melts of quasicrystal-forming Al-Cu-Co alloys by EXAFS

It was predicted by Frank that an icosahedral short-range order prevails in undercooled metallic melts. This suggestion bases upon the fact that the icosahedron has the lowest energy per atom of all clusters, if the atomic interactions are described by Lennard-Jones potentials. The proposed icosahedral short-range order might even be more pronounced for melts forming quasicrystalline phases, which themselves are built from polytetrahedral structural units. In this work, the short-range order of quasicrystal-forming Al-Cu-Co melts is studied by extended X-ray absorption, fine structure investigations at K-absorption edge of Co. The analysis of the spectra indicates that the absorbing Co-atom is mainly surrounded by aluminium atoms. (C) 2000 Elsevier Science B.V. All rights reserved.