Publication detail

Low temperature a/b nanotwins in Ni50Mn25+xGa25−x Heusler alloys

STRAKA, L. VEŘTÁT, P. DRAHOKOUPIL, J. ZELENÝ, M. KOPEČEK, J. SOZINOV, A. HECZKO, O.

English title

Low temperature a/b nanotwins in Ni50Mn25+xGa25−x Heusler alloys

Type

journal article in Web of Science

Language

en

Original abstract

We have found low temperature a/b nanotwins having (110) twinning plane in a five-layered modulated martensite phase of Ni50Mn25+xGa25−x (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/Å2. 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.

English abstract

We have found low temperature a/b nanotwins having (110) twinning plane in a five-layered modulated martensite phase of Ni50Mn25+xGa25−x (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/Å2. 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.

Keywords in English

nanotwinning, magnetic shape memory alloy, Heusler alloys

Released

09.08.2018

Publisher

Springer Nature

ISSN

2045-2322

Volume

8

Number

1

Pages from–to

11943–-

Pages count

11

BIBTEX


@article{BUT149142,
  author="Ladislav {Straka} and Jan {Drahokoupil} and Petr {Veřtát} and Martin {Zelený} and Jaromír {Kopeček} and Alexei {Sozinov} and Oleg {Heczko},
  title="Low temperature a/b nanotwins in Ni50Mn25+xGa25−x Heusler alloys",
  year="2018",
  volume="8",
  number="1",
  month="August",
  pages="11943---",
  publisher="Springer Nature",
  issn="2045-2322"
}