Abstract
The stable Al-Cu-Co, Al-Ni-Co and Al-Ni-Fe decagonal quasicrystalline phases were studied by transmission electron microscopy and powder X-ray diffraction. These phases were found to be isotypic in all three alloy systems. Minor differences in the intensity distributions in their electron diffraction patterns can be attributed to different occupancies of the same atomic positions by different elements. The decagonal phases exhibit the same limits of the electron-to-atom ratio.