Low temperature a/b nanotwins in Ni50Mn25+xGa25x Heusler alloys
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Date
2018-08-09
Authors
Straka, Ladislav
Drahokoupil, Jan
Veřtát, Petr
Zelený, Martin
Kopeček, Jaromír
Sozinov, Alexei
Heczko, Oleg
ORCID
0000-0001-6715-4088Advisor
Referee
Mark
Journal Title
Journal ISSN
Volume Title
Publisher
Springer Nature
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Abstract
We have found low temperature a/b nanotwins having (110) twinning plane in a five-layered modulated martensite phase of Ni50Mn25+xGa25x (at. %) Heusler alloys and identified the particular region in phase diagram where the nanotwinning occurs. Evolution of the structure with decreasing temperature was studied by X-ray diffraction using single crystals exhibiting magnetic shape memory effect. The merging of (400) and (040) lines upon cooling for 2.6 < x < 3.5 indicated a/b nanotwinning originating from the refinement of initially coarse a/b twins. Refinement of the twins with decreasing temperature was observed directly using scanning electron microscopy. The prerequisite for nanotwinning is an extremely low twin boundary energy, which we estimated using first-principles calculations to be 0.16 meV/2. As the nanotwinning distorts the relation between the crystal lattice and the X-ray diffraction pattern, it should be taken into consideration in structural studies of Ni-Mn-Ga Heusler alloys.
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Citation
Scientific Reports. 2018, vol. 8, issue 1, p. 11943--.
http://link.springer.com/article/10.1038/s41598-018-30388-8
http://link.springer.com/article/10.1038/s41598-018-30388-8
Document type
Peer-reviewed
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Published version
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Language of document
en