The Structure of an Al-Ni-Fe Decagonal Quasicrystal Studied by High-Angle Annular Detector Dark-Field Scanning Transmission Electron Microscopy

Abstract

The structure of an Al–Ni–Fe decagonal phase, which was found as a highly-ordered decagonal quasicrystal with periodicity of 0.4 nm in an Al_71.6Ni_23.7Fe_4.7 alloy, has been studied by atomic-scale observations of high-angle annular detector dark-field scanning transmission electron microscopy (HAADF-STEM). It has been found that a large columnar cluster of atoms with a decagonal section of about 3.2 nm in diameter exists as a basic structural unit. A structural model of the cluster is proposed from HAADF-STEM images.