Improvement of magnetic properties and intergranular microstructure of Nd{endash}Fe{endash}B magnets by intergranular addition of MgO oxide

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.364974· OSTI ID:496486

Chen, Z; Yan, A; Wang, X ^[1]; Hadjipanayis, G C ^[2]

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1. School of Materials Science and Engineering, Xi`an Jiaotong University, Xi`an 710049, People`s Republic of (China)
2. Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States)

In this work we have studied in detail the effect of MgO on magnetic properties and intergranular microstructure. We have found that both coercivity and thermal stability can be remarkably enhanced by the intergranular addition of MgO. For Nd{sub 22}Fe{sub 71}B{sub 7} magnets with 2 wt{percent} MgO addition, the coercivity at room temperature and 180{degree}C are enhanced from 17.0 and 3.2 kOe to 22.1 and 5.2 kOe, respectively, and the reversible and irreversible flux loss from room temperature to 180{degree}C is reduced from 25.4{percent} and 5.2{percent} to 20.5{percent} and 0.5{percent}, respectively. Microstructural studies reveal that a new intergranular Nd{endash}O{endash}Fe{endash}Mg phase with a composition close to Nd{sub 70}O{sub 23}Fe{sub 3}Mg{sub 2} appears in the magnets with MgO addition. The improvement of magnetic properties by the MgO addition is believed to be due to the appearance of a Nd{endash}O{endash}Fe{endash}Mg intergranular phase, which probably hinders the propagation of the domain walls between Nd{sub 2}Fe{sub 14}B grains. It is further found that the addition of Mg or O alone into the intergranular regions of the magnets does not lead to the formation of this Nd{endash}O{endash}Fe{endash}Mg intergranular phase, and thus, cannot substantially improve the coercivity and the thermal stability of the magnets. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 496486
• Report Number(s): CONF-961141--
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 81; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BORON ALLOYS
COERCIVE FORCE
FERROMAGNETIC MATERIALS
GRAIN BOUNDARIES
IRON ALLOYS
LOSSES
MAGNESIUM COMPOUNDS
MAGNETIC PROPERTIES
MANGANESE OXIDES
MICROSTRUCTURE
NEODYMIUM ALLOYS
PERMANENT MAGNETS
STABILITY