Grain refinement in heavy rare earth element-free sintered Nd–Fe–B magnets by addition of a small amount of molybdenum

Journal Article · Thu May 07 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4916496· OSTI ID:22409963

Kim, Jin Woo; Lee, Won Suk; Byun, Jong Min; Kim, Se Hoon ^[1]

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1. Korea Automotive Technology Institute (KATECH), Cheonan-si 330-912 (Korea, Republic of)

We employed a modified refractory-metal-addition method to achieve higher coercivity and remanence in heavy rare earth element (HREE)-free Nd–Fe–B sintered magnets. This process involved inducing the formation of a homogeneous secondary phase at the grain boundaries during sintering, making it possible to control the intergrain diffusion by adding small amounts of Mo, a refractory metal. To control the microstructure of the secondary phase effectively, a metal organic compound of the refractory metal was coated on the surfaces of the particles of an HREE-free Nd–Fe–B powder. The average grain size after this process was 5.60 μm, which was approximately 1.8 μm smaller than that of the HREE-free sintered Nd–Fe–B magnets (7.4 μm). The coercivity of the magnets prepared through this process could be increased from 11.88 kOe to 13.91 kOe without decreasing their remanence.

• OSTI ID: 22409963
• 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

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
APPROXIMATIONS
BORON ALLOYS
COERCIVE FORCE
DIFFUSION
GRAIN BOUNDARIES
GRAIN REFINEMENT
GRAIN SIZE
IRON ALLOYS
MAGNETIC MATERIALS
MAGNETS
MOLYBDENUM
MOLYBDENUM ADDITIONS
NEODYMIUM ALLOYS
ORGANOMETALLIC COMPOUNDS
POWDERS
SINTERING
SURFACES