Hexagonal structural block consisting of 2 nm decagonal clusters in Al60Cr20Fe10Si10 alloy

Abstract Hexagonal structural blocks are a basic structural unit in quasicrystals and their approximants. We identified a large hexagonal structural block with an edge length of 1.91 nm in an Al 60 Cr 20 Fe 10 Si 10 alloy using atomic-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The hexagonal structural block contained 2-nm decagonal clusters with perfect ten-fold symmetry. Four large approximants composed of the hexagonal structural block were deduced from HAADF-STEM images. Furthermore, some irregular polygons were identified and their generation was readily explained based on the overlap of the hexagonal structural blocks.