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Electron microscopy and diffraction of icosahedral and decagonal quasicrystals in aluminium‐manganese alloys
Author(s) -
Thangaraj N.,
Subbanna G. N.,
Ranganathan S.,
Chattopadhyay K.
Publication year - 1987
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1987.tb01351.x
Subject(s) - quasicrystal , icosahedral symmetry , electron diffraction , nucleation , crystallography , materials science , diffraction , manganese , electron microscope , condensed matter physics , phason , aluminium , chemistry , physics , metallurgy , optics , organic chemistry
SUMMARY Electron microscopic observations on the morphology of icosahedral and decagonal quasicrystals in aluminium‐manganese alloys have been interpreted in favour of a heterogenous nucleation mode. The transition of icosahedral quasicrystals from nonfacetted dendrites to facetted particles occurs as a function of composition. While the variety of electron diffraction patterns to be expected from icosahedral quasicrystals has been demonstrated for a number of alloys, subtle intensity differences exist among analogous patterns from Al‐Mn, Al‐Cr, Al‐Mn‐Si and Mg‐Al‐Zn‐Cu alloys. Electron diffraction patterns from decagonal quasicrystals can be understood on the basis of an edge‐centred icosahedron as opposed to a vertex‐centred icosahedron for icosahedral quasicrystals. Truncation from two‐dimensional quasicrystals is discussed.