Abstract
An Al-Ni-Ru decagonal quasicrystal with 0.4 nm periodicity, which has a good long-range basic quasiperiodic order, was observed to form in rapidly solidified Al-Ni-Ru alloys. Its structure has been studied by means of high-resolution electron microscopy and high-angle annular detector dark-field techniques, and compared with that of a superlattice Al-Ni-Ru decagonal quasicrystal formed by conventional solidification. The results reveal that the rapidly solidified Al-Ni-Ru decagonal quasicrystal with 0.4 nm periodicity has a new basic structural state which is characterized by a mixture of 2 nm atomic columnar clusters with and without pentagonal symmetry.
