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A Combined TEMSTEM and Micromagnetic Study of the Anisotropic Nature of Grain Boundaries and Coercivity in Nd-Fe-B Magnets
Joint Authors
Zickler, Gregor A.
Fidler, Josef
Bernardi, Johannes
Schrefl, Thomas
Asali, Ahmad
Source
Advances in Materials Science and Engineering
Issue
Vol. 2017, Issue 2017 (31 Dec. 2017), pp.1-12, 12 p.
Publisher
Hindawi Publishing Corporation
Publication Date
2017-01-15
Country of Publication
Egypt
No. of Pages
12
Abstract EN
The nanoanalytical high resolution TEM/STEM investigation of the intergranular grain boundary phase of anisotropic sintered and rapidly quenched heavy rare earth-free Nd-Fe-B magnet materials revealed a difference in composition for grain boundaries parallel (large Fe-content) and perpendicular (low Fe content) to the alignment direction.
This behaviour vanishes in magnets with a high degree of misorientation.
The numerical finite element micromagnetic simulations are based on the anisotropic compositional behaviour of GBs and show a decrease of the coercive field with an increasing thickness of the grain boundary layer.
The magnetization reversal and expansion of reversed magnetic domains primarily start as Bloch domain wall at grain boundaries parallel to the c-axis and secondly as Néel domain wall perpendicular to the c-axis into the adjacent hard magnetic grains.
The increasing misalignment of grains leads to the loss of the anisotropic compositional behaviour and therefore to an averaged value of the grain boundary composition.
In this case the simulations show an increase of the coercive field compared to the anisotropic magnet.
The calculated coercive field values of the investigated magnet samples are in the order of μ0HcJ=1.8 T–2.1 T for a mean grain boundary thickness of 4 nm, which agrees perfectly with the experimental data.
American Psychological Association (APA)
Zickler, Gregor A.& Fidler, Josef& Bernardi, Johannes& Schrefl, Thomas& Asali, Ahmad. 2017. A Combined TEMSTEM and Micromagnetic Study of the Anisotropic Nature of Grain Boundaries and Coercivity in Nd-Fe-B Magnets. Advances in Materials Science and Engineering،Vol. 2017, no. 2017, pp.1-12.
https://search.emarefa.net/detail/BIM-1124471
Modern Language Association (MLA)
Zickler, Gregor A.…[et al.]. A Combined TEMSTEM and Micromagnetic Study of the Anisotropic Nature of Grain Boundaries and Coercivity in Nd-Fe-B Magnets. Advances in Materials Science and Engineering No. 2017 (2017), pp.1-12.
https://search.emarefa.net/detail/BIM-1124471
American Medical Association (AMA)
Zickler, Gregor A.& Fidler, Josef& Bernardi, Johannes& Schrefl, Thomas& Asali, Ahmad. A Combined TEMSTEM and Micromagnetic Study of the Anisotropic Nature of Grain Boundaries and Coercivity in Nd-Fe-B Magnets. Advances in Materials Science and Engineering. 2017. Vol. 2017, no. 2017, pp.1-12.
https://search.emarefa.net/detail/BIM-1124471
Data Type
Journal Articles
Language
English
Notes
Includes bibliographical references
Record ID
BIM-1124471