Structural study of an Al73Ni22Fe5 decagonal quasicrystal by high-angle annular dark-field scanning transmission electron microscopy

K. Saitoh, M. Tanaka, P. Tsai

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    10 Citations (Scopus)

    Abstract

    A water-quenched Al73Ni22Fe5 decagonal quasicrystal was investigated by the selected-area electron diffraction, convergent-beam electron diffraction and high-angle annular dark-field scanning transmission electron microscope methods. The alloy shows very sharp spots and nearly no diffuse scattering in the diffraction patterns, belongs to centrosymmetric space group P105 / mmc and is constructed almost by one type of 2 nm diameter atom cluster having mirror symmetry with a highly quasicrystalline order arrangement. Although a small number of 2 nm atom clusters having five-fold symmetry exists, which are similar to those observed in melt-quenched Al70Ni15Fe15, the structure of Al73Ni22Fe5 is considered to basically be the same as that of water-quenched Al72Ni20Co8, which is constructed only by mirror symmetry clusters arranged with a very high quasiperiodicity. The number of valence electrons per atom (e/a) of the present alloy (1.92) is very close to that of Al72Ni20Co8 (1.90), but differs from those of phases constructed by only the five-fold symmetry clusters. This implies that these alloys are Hume-Rothery electron compounds, whose structures are determined primarily by e/a value.

    Original languageEnglish
    Pages (from-to)197-203
    Number of pages7
    JournalJournal of Electron Microscopy
    Volume50
    Issue number3
    DOIs
    Publication statusPublished - 2001

    Keywords

    • Convergent-beam electron diffraction
    • Decagonal quasicrystal
    • High-angle annular dark-field imaging
    • Z-contrast imaging

    ASJC Scopus subject areas

    • Instrumentation

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