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Study of the ordered structures of the Au–Mn system by high voltage–high‐resolution electron microscopy. III. Two‐dimensional antiphase structure of Au 3 Mn type
Author(s) -
Terasaki O.,
Watanabe D.
Publication year - 1982
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s002188988201200x
Subject(s) - orthorhombic crystal system , crystallography , alloy , materials science , electron microscope , resolution (logic) , condensed matter physics , chemistry , crystal structure , physics , optics , metallurgy , artificial intelligence , computer science
High‐resolution structure images of the 23.5 and 24 at.% Mn alloys annealed at 573 K were studied by 1 MV electron microscopy. It was shown that the 24 at.% Mn alloy consists of two‐dimensional antiphase structure (2 d ‐APS) of Au 3 Mn with the boundaries parallel to the (100) and (010) planes. The average domain sizes were measured as M 1 = 1.04 and M 2 = 2.41, and an orthorhombic structure model with M 1 = 1 and M 2 = 2.5 was proposed for the ideal structure of the 2 d ‐Au 3 Mn. From the 23.5 at.% Mn alloy, the structures corresponding to the intermediate state between the 2 d ‐Au 3 Mn and the 2 d ‐APS(I), which consists of lozenge‐ and parallelogram‐shaped domains and exists in the alloys with 21–23 at.% Mn, were observed. It was concluded that the statistical order of appearance of the stable ordered phases with increasing Mn content in the composition range of 20–24 at.% Mn is Au 4 Mn → Au 22 Mn 6 → Au 31 Mn 9 → 2 d ‐APS(I) → 2 d ‐Au 3 Mn (so called Watanabe structure).