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Modeling of Nd-Oxide Grain Boundary Phases in Nd-Fe-B Sintered Magnets

Hrkac, G. and Butler, K. and Woodcock, T. G. and Saharan, L. and Schrefl, T. and Gutfleisch, O. (2014):
Modeling of Nd-Oxide Grain Boundary Phases in Nd-Fe-B Sintered Magnets.
In: JOM, Springer US, pp. 1138-1143, 66, (7), ISSN 1047-4838,
[Online-Edition: http://dx.doi.org/10.1007/s11837-014-0980-5],
[Article]

Abstract

We use atomistic and micromagnetic simulations combined with atomic-scale, aberration-corrected transmission electron microscopy to study the anisotropy profile of the interface between a Nd2O3-hP5 and a Nd2Fe14B phase. It is shown that a hybrid Morse-Buckingham potential approach can be used to study mixed-metallic and oxide-rich systems and to calculate surface-energy-induced large strains and potentially large relaxation effects on the adjacent grains. These are used to derive a magnetoelastic anisotropy energy from a first-order perturbation of the magnetoelastic Hamiltonian and are used to evaluate its effect on coercivity. It is shown that the change in coercivity originates from these distortions in the Nd2Fe14B crystal lattice close to the grain boundary, and the coercivity can be evaluated using such a multiscale modeling approach.

Item Type: Article
Erschienen: 2014
Creators: Hrkac, G. and Butler, K. and Woodcock, T. G. and Saharan, L. and Schrefl, T. and Gutfleisch, O.
Title: Modeling of Nd-Oxide Grain Boundary Phases in Nd-Fe-B Sintered Magnets
Language: English
Abstract:

We use atomistic and micromagnetic simulations combined with atomic-scale, aberration-corrected transmission electron microscopy to study the anisotropy profile of the interface between a Nd2O3-hP5 and a Nd2Fe14B phase. It is shown that a hybrid Morse-Buckingham potential approach can be used to study mixed-metallic and oxide-rich systems and to calculate surface-energy-induced large strains and potentially large relaxation effects on the adjacent grains. These are used to derive a magnetoelastic anisotropy energy from a first-order perturbation of the magnetoelastic Hamiltonian and are used to evaluate its effect on coercivity. It is shown that the change in coercivity originates from these distortions in the Nd2Fe14B crystal lattice close to the grain boundary, and the coercivity can be evaluated using such a multiscale modeling approach.

Journal or Publication Title: JOM
Volume: 66
Number: 7
Publisher: Springer US
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Functional Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 17 Nov 2014 09:35
Official URL: http://dx.doi.org/10.1007/s11837-014-0980-5
Identification Number: doi:10.1007/s11837-014-0980-5
Funders: The authors gratefully acknowledge financial support from the Toyota Motor Corporation and the fruitful discussions with Dr. Kato, Dr. Tetsuja, and Dr. Yano and the EPSRC for financial support under Grants EP/G032440/1 and EP/G032300/1., The authors gratefully acknowledge financial support from the WWTF Project MA09-029, and the Royal Society.
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