Coercivity enhancement of Dy-coated Nd-Fe-B flakes by crystallization

Journal Article · Fri Apr 01 00:00:00 EDT 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3549604· OSTI ID:21538244

Fukunaga, H; Sugimoto, Y; Nakano, M; Yanai, T ^[1]; Ohta, S; Itakura, M; Nishida, M ^[2]

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1. Faculty of Engineering, Nagasaki University, Nagasaki 852-8521 (Japan)
2. Department of Applied Science for Electronics and Materials, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan)

The coercivity of isotropic Dy-coated Nd-Fe-B flakes was enhanced by crystallization and simultaneous diffusion of Dy from their surfaces. Amorphous Dy-coated Nd-Fe-B flakes were crystallized by heating them to 923 K 2over a 2 min period followed by rapid cooling. During crystallization, the Dy on the surface diffused into the flakes. This low-temperature rapid annealing produced flakes with fine grains and the Dy diffusion enhanced their coercivity. The coercivity after crystallization increased with increasing Dy layer thickness, although the remanence decreased when the layer thickness exceeded 3 {mu}m. Thick coatings of over 6 {mu}m resulted in the formation of DyFe{sub 2}, which degraded the magnetic properties of the crystallized flakes. Flakes with a 3-{mu}m-thick coating exhibited excellent magnetic properties after annealing: They had a coercivity of 1880 kA/m and a remanence of 78 emu/g. This coercivity is approximately 500 kA/m higher than that of uncoated flakes, whereas the remanence is comparable to that of uncoated flakes.

• OSTI ID: 21538244
• Journal Information: Journal of Applied Physics, Vol. 109, Issue 7; Conference: 55. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 14-18 Nov 2010; Other Information: DOI: 10.1063/1.3549604; (c) 2011 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
BORON ALLOYS
COATINGS
COERCIVE FORCE
COOLING
CRYSTALLIZATION
DIFFUSION
DYSPROSIUM
HEATING
IRON ALLOYS
LAYERS
MAGNETIC PROPERTIES
NEODYMIUM ALLOYS
SURFACES
TEMPERATURE RANGE 0065-0273 K
THICKNESS
ALLOYS
DIMENSIONS
ELEMENTS
HEAT TREATMENTS
METALS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RARE EARTH ALLOYS
RARE EARTHS
TEMPERATURE RANGE
TRANSITION ELEMENT ALLOYS