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Title: Neutron diffraction study of the martensitic transformation and chemical order in Heusler alloy Ni1.91Mn1.29Ga0.8

In this study, Heusler alloys of Ni-Mn-Ga compositions demonstrate ferromagnetic shape memory effect in the martensitic state. The transformation temperature and the chemical order depend strongly on the composition. In the current work, the structure and chemical order of the martensitic phase of Ni1.91Mn1.29Ga0.8 were studied using neutron diffraction; the diffraction pattern was refined using the FullProf software. It was determined that the structural transition occurs around 330 K. At room temperature, 300 K, which is below the martensite transformation temperature, all the Bragg reflections can be described by a monoclinic lattice with a symmetry of space group P 1 2/m 1 and lattice constants of a = 4.23047(7) [Å], b = 5.58333(6) [Å], c = 21.0179(2) [Å], beta = 90.328(1). The chemical order is of critical importance in these alloys, and it was previously studied at 363 K. Analysis of the neutron diffraction in the monoclinic phase shows that the chemical order is maintained during the martensitic transformation.
 [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4]
  1. Western Michigan Univ., Kalamazoo MI (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Aalto Univ. School of Chemical Technology, Espoo (Finland)
  4. Kotelnikov Institute of Radio Engineering and Electronics, Moscow (Russia)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Materials Today: Proceedings
Additional Journal Information:
Journal Volume: 2; Journal Issue: S3; Journal ID: ISSN 2214-7853
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
Sponsoring Org:
Country of Publication:
United States
36 MATERIALS SCIENCE chemical order; Ni-Mn-Ga alloy; magnetic shape memory; neutron diffraction; Rietveld method; structure refinement