Temperature dependence of coercivity in melt-spun and die upset neodymium-iron-boron

Journal Article · Tue May 01 00:00:00 EDT 1990 · Journal of Applied Physics; (USA)

DOI:https://doi.org/10.1063/1.344775· OSTI ID:6837248

Pinkerton, F E; Fuerst, C D ^[1]

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1. Physics Department, General Motors Research Laboratories, Warren, Michigan 48090-9055 (USA)

We compare the temperature dependence of the intrinsic coercivity {ital H}{sub {ital ci}} between 5 and 600 K in rapidly quenched Nd-Fe-B ribbons and a die upset Nd-Fe-B magnet. At room temperature, ribbons have higher coercivity than the die upset magnet, but have a smaller technical temperature coefficient of coercivity {beta} between 25 and 125 {degree}C: {ital H}{sub {ital ci}}=15.1 kOe and {beta}={minus}0.38%/{degree}C for the ribbons, while {ital H}{sub {ital ci}}=10.4 kOe and {beta}={minus}0.64%/{degree}C for the die upset magnet. Because the die upset magnet has a stronger temperature dependence, the {ital H}{sub {ital ci}}({ital T}) curves converge at low temperature. The ribbons can be phenomenologically modeled using {ital H}{sub {ital ci}}({ital T})={ital cH}{sub {ital A}}({ital T}){minus}{ital N}{sub eff}4{pi}{ital M}{sub {ital s}}({ital T}), the two terms representing the strength of domain wall pinning at grain boundaries and the effective local demagnetizing field, respectively. The model parameters {ital c}=0.25 and {ital N}{sub eff}=0.26 are significantly smaller than the corresponding values obtained in sintered Nd-Fe-B magnets. This model is less successful in describing {ital H}{sub {ital ci}}({ital T}) for the die upset magnet. Their qualitatively different behaviors indicate that different mechanisms of domain wall pinning are responsible for coercivity in ribbons and die upset magnets.

• OSTI ID: 6837248
• Journal Information: Journal of Applied Physics; (USA), Vol. 67:9; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
IRON BORIDES
MAGNETIC PROPERTIES
NEODYMIUM BORIDES
COERCIVE FORCE
GRAIN BOUNDARIES
HIGH TEMPERATURE
LOW TEMPERATURE
MATHEMATICAL MODELS
MEDIUM TEMPERATURE
PERMANENT MAGNETS
TEMPERATURE DEPENDENCE
ULTRALOW TEMPERATURE
VERY LOW TEMPERATURE
BORIDES
BORON COMPOUNDS
CRYSTAL STRUCTURE
IRON COMPOUNDS
MAGNETS
MICROSTRUCTURE
NEODYMIUM COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties