Intrinsic magnetic properties of L1{sub 0} FeNi obtained from meteorite NWA 6259
- MEDA Engineering and Technical Services, Southfield, Michigan 48075 (United States)
- Chemical Sciences and Materials Systems Lab, GM R and D Center, Warren, Michigan 48090 (United States)
- Department of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115 (United States)
- Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Massachusetts 01003 (United States)
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States)
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)
FeNi having the tetragonal L1{sub 0} crystal structure is a promising new rare-earth-free permanent magnet material. Laboratory synthesis is challenging, however, tetragonal L1{sub 0} FeNi—the mineral “tetrataenite”—has been characterized using specimens found in nickel-iron meteorites. Most notably, the meteorite NWA 6259 recovered from Northwest Africa is 95 vol. % tetrataenite with a composition of 43 at. % Ni. Hysteresis loops were measured as a function of sample orientation on a specimen cut from NWA 6259 in order to rigorously deduce the intrinsic hard magnetic properties of its L1{sub 0} phase. Electron backscatter diffraction showed that NWA 6259 is strongly textured, containing L1{sub 0} grains oriented along any one of the three equivalent cubic directions of the parent fcc structure. The magnetic structure was modeled as a superposition of the three orthonormal uniaxial variants. By simultaneously fitting first-quadrant magnetization data for 13 different orientations of the sample with respect to the applied field direction, the intrinsic magnetic properties were estimated to be saturation magnetization 4πM{sub s} = 14.7 kG and anisotropy field H{sub a} = 14.4 kOe. The anisotropy constant K = 0.84 MJ/m{sup 3} is somewhat smaller than the value K = 1.3 MJ/m{sup 3} obtained by earlier researchers from nominally equiatomic FeNi prepared by neutron irradiation accompanied by annealing in a magnetic field, suggesting that higher Ni content (fewer Fe antisite defects) may improve the anisotropy. The fit also indicated that NWA 6259 contains one dominant variant (62% by volume), the remainder of the sample being a second variant, and the third variant being absent altogether.
- OSTI ID:
- 22410152
- Journal Information:
- Journal of Applied Physics, Vol. 117, Issue 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
Similar Records
De Magnete et Meteorite: Cosmically Motivated Materials
Transition-metal and metalloid substitutions in L1{sub 0}-ordered FeNi
Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
ANNEALING
BACKSCATTERING
ELECTRON DIFFRACTION
FCC LATTICES
HYSTERESIS
IRON METEORITES
IRRADIATION
MAGNETIC FIELDS
MAGNETIC PROPERTIES
MAGNETIZATION
MINERALS
NEUTRON FLUENCE
NICKEL
PERMANENT MAGNETS
PHYSICAL RADIATION EFFECTS
RARE EARTHS
TEXTURE