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Author Takeshita, T. ♦ Morimoto, K.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ PERMANENT MAGNETS ♦ FABRICATION ♦ NEODYMIUM BORIDES ♦ MAGNETIZATION ♦ IRON BORIDES ♦ POWDERS ♦ MAGNETIC MATERIALS ♦ BONDING ♦ COERCIVE FORCE ♦ PHASE STUDIES ♦ TEMPERATURE DEPENDENCE ♦ TEMPERATURE RANGE 0273-0400 K
Abstract Anisotropic Nd{endash}Fe{endash}B magnet powders can be produced by the hydrogenationdecomposition-desorption-recombination (HDDR) process from Nd{endash}Fe@ xnB{endash}Co{endash}M ({ital M}=Ga, Zr, Nb, Hf, and Ta) alloys. The present status of those HDDR powders and the bonded magnets made from them are reviewed with regards to the powder particle size dependence of their magnetic properties, their magnetic thermal stability, and their magnetization behavior. The results of a mechanistic study on the recombination step are also presented. The magnetic properties of the anisotropic HDDR powder depend relatively little on the powder particle size. Bonded magnets with a density of {approximately}6.20 g/cm{sup 3} and a BH{sub max} of 18.5{endash}20.5 MGOe can be produced from anisotropic HDDR powders with particle sizes of below 300 {mu}m diam. The temperature coefficient of the intrinsic coercive force {sub {ital iH}}{sub {ital c}}, of the bonded magnet is {minus}0.55{percent}/{degree}C in the temperature range from 25 to 100{degree}C. The magnetization force needed for full magnetization of the bonded magnet is about twice the coercive force of the magnet, indicating that the magnetization mechanism is different from that of the rapidly solidified isotropic Nd{endash}Fe{endash}B magnet. In the early stage of the recombination step of the HDDR process (1 min desorption), three phases are produced, i.e., {alpha}-(Fe,Co), spherical NdH{sub 2} and rimlike Nd{sub 2}(Fe,Co){sub 14}B surrounding the NdH{sub 2} particle. Further desorption makes the Nd{sub 2}(Fe,Co){sub 14}B phase grow. {copyright} {ital 1996 American Institute of Physics.}
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 1996-04-01
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 79
Issue Number 8
Technical Publication No. CONF-951101-


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