Hume-Rothery effects in amorphous and quasicrystalline Al-Cu-Fe

A detailed comparison of the amorphous and the quasicrystalline state of Al -Cu-Fe is presented. The samples were prepared amorphously at low temperatu re. After several annealing steps within the amorphous phase they were tran sformed into the quasicrystalline state at T=700 K. The atomic structure as well as electronic transport properties for both phases have been investig ated. Electron diffraction measurements of amorphous Al-Cu-Fe show the atom ic structure as electron induced. The dominant structural peak shifts nearl y parallel to 2k(F):, the diameter of the Fermi-sphere, as a function of co mposition. At the corresponding composition its position is exactly coincid ing with one of the two most dominant peaks of the icosahedral phase, indic ating that this phase is Hume-Rothery stabilized as well. The electrical co nductivity as well as the Hall coefficient indicate strong similarities bet ween both phases. In the amorphous phase magnetic effects are observed. (C) 2000 Elsevier Science B.V. All rights reserved.