Neutron Diffraction Study of a Non-Stoichiometric Ni-Mn-Ga MSM Alloy

Authors

Pnina Ari-Gur, Western Michigan UniversityFollow
V. Ovidiu Garlea, Oak Ridge National Lab
Ashley Coke, Oak Ridge National Lab
Yanling Ge, Aalto University
Ilkka Aaltio, Aalto University
Simo-Pekka Hannula, Aalto University
Huibo Cao, Oak Ridge National Lab
Amila SB Madiligama, Western Michigan University
Victor Koledov, Russian Academy of Sciences

Document Type

Article

DOI

https://doi.org/10.4028/www.scientific.net/MSF.738-739.103

Publication Date

2013

Abstract

The structure and chemical order of a Heusler alloy of non-stoichiometric composition Ni-Mn-Ga were studied using constant-wavelength (1.538 Å) neutron diffraction at 363K and the diffraction pattern was refined using the Fullprof software. At this temperature the structure is austenite (cubic) with Fm space group and lattice constant of a = 5.83913(4) [Å]. The chemical order is of critical importance in these alloys, as Mn becomes antiferromagnetic when the atoms are closer than the radius of the 3d shell. In the studied alloy, the refinement of the site occupancy showed that the 4b (Ga site) contained as much as 22% Mn; that significantly alters the distances between the Mn atoms in the crystal and, as a result, also the exchange energy between some of the Mn atoms. Based on the refinement, the composition was determined to be Ni_1.91Mn_1.29Ga_0.8

Comments

The complete article can be found at https://www.scientific.net/MSF.738-739.103.

WMU ScholarWorks Citation

Ari-Gur, Pnina; Garlea, V. Ovidiu; Coke, Ashley; Ge, Yanling; Aaltio, Ilkka; Hannula, Simo-Pekka; Cao, Huibo; Madiligama, Amila SB; and Koledov, Victor, "Neutron Diffraction Study of a Non-Stoichiometric Ni-Mn-Ga MSM Alloy" (2013). Mechanical and Aerospace Engineering Faculty Publications. 4.
https://scholarworks.wmich.edu/mae_pubs/4