Long-range tiling structures in a highly ordered Al–Ni–Ru decagonal quasicrystal with 1.6 nm periodicity and its closely related approximant

Abstract

By means of high-resolution electron microscopy, tiling structures constructed by arrangements of atom clusters in a wide region (>100×100 nm 2) have been directly determined for the Al–Ni–Ru decagonal quasicrystal with 1.6 nm periodicity formed in the Al 75Ni 15Ru 10 alloy annealed at 800°C and for its closely related approximant in the as-cast Al 70Ni 20Ru 10 alloy, respectively. It has been found that the Al–Ni–Ru decagonal quasicrystal with 1.6 nm periodicity is a highly ordered quasicrystal and its structure is characterized by an aperiodic pentagonal tiling without any detectable linear phason strain. The approximant, which exhibits both periodic and quasiperiodic features in its electron diffraction pattern, is characterized by a pentagonal tiling containing a series of long chains of pentagons. The observed tilings for the Al–Ni–Ru decagonal quasicrystal and the approximant are compared with the theoretical tiling in the perpendicular space.