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Atomic scale analyses of ‐module defects in an NiZr alloy
Author(s) -
Sirindil Abdullah,
Kobold Raphael,
Mompiou Frédéric,
Lartigue-Korinek Sylvie,
Perriere Loic,
Patriarche Gilles,
Quiquandon Marianne,
Gratias Denis
Publication year - 2018
Publication title -
acta crystallographica section a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.742
H-Index - 83
ISSN - 2053-2733
DOI - 10.1107/s2053273318011439
Subject(s) - alloy , materials science , scale (ratio) , atomic units , metallurgy , nuclear engineering , engineering , physics , quantum mechanics
Some specific structures of intermetallic alloys, like approximants of quasicrystals, have their unit cells and most of their atoms located on a periodic fraction of the nodes of a unique ‐module [a set of the irrational projections of the nodes of a ( N > 3‐dimensional) lattice]. Those hidden internal symmetries generate possible new kinds of defects like coherent twins, translation defects and so‐called module dislocations that have already been discussed elsewhere [Quiquandon et al. (2016). Acta Cryst. A 72 , 55–61; Sirindil et al. (2017). Acta Cryst. A 73 , 427–437]. Presented here are electron microscopy observations of the orthorhombic phase NiZr – and its low‐temperature monoclinic variant – which reveal the existence of such defects based on the underlying ‐module generated by the five vertices of the regular pentagon. New high‐resolution electron microscopy (HREM) and scanning transmission electron microscopy high‐angle annular dark‐field (STEM‐HAADF) observations demonstrate the agreement between the geometrical description of the structure in five dimensions and the experimental observations of fivefold twins and translation defects.