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Mechanism of the texture development in hydrogen-disproportionation–desorption-recombination (HDDR) processed Nd–Fe–B powders

Sepehri-Amin, H. and Ohkubo, T. and Hono, K. and Güth, K. and Gutfleisch, O. (2015):
Mechanism of the texture development in hydrogen-disproportionation–desorption-recombination (HDDR) processed Nd–Fe–B powders.
In: Acta Materialia, Elsevier Science Publishing, pp. 42-52, 85, ISSN 13596454,
[Online-Edition: http://dx.doi.org/10.1016/j.actamat.2014.11.003],
[Article]

Abstract

Microstructure evolution in Nd12.8Fe80.1B6.6Ga0.3Nb0.2 alloy powders at different hydrogen pressures during the hydrogen-disproportionation process View the MathML sourcePH2HD has been studied in order to understand the underlying mechanism of the texture development during the dynamic hydrogen-disproportionation–desorption-recombination (d-HDDR) process. Transmission electron microscopy showed that Fe2B grains “memorize” the crystallographic orientation of the initial Nd2Fe14B phase and transfer it to the recombined Nd2Fe14B grains in the highly textured sample. 3-D tomography of backscattered electron SEM images showed that recombined Nd2Fe14B grains nucleate at the interfaces of Fe2B/NdH2 phases, which grow through the interfaces of NdH2/α-Fe phases during the DR process. Boron segregation was found at the NdH2/α-Fe interfaces, which serve as a boron source for the growth of the recombined Nd2Fe14B grains. The mechanism of the texture development is discussed based on the microstructure observations and the corresponding evolution of magnetic properties.

Item Type: Article
Erschienen: 2015
Creators: Sepehri-Amin, H. and Ohkubo, T. and Hono, K. and Güth, K. and Gutfleisch, O.
Title: Mechanism of the texture development in hydrogen-disproportionation–desorption-recombination (HDDR) processed Nd–Fe–B powders
Language: English
Abstract:

Microstructure evolution in Nd12.8Fe80.1B6.6Ga0.3Nb0.2 alloy powders at different hydrogen pressures during the hydrogen-disproportionation process View the MathML sourcePH2HD has been studied in order to understand the underlying mechanism of the texture development during the dynamic hydrogen-disproportionation–desorption-recombination (d-HDDR) process. Transmission electron microscopy showed that Fe2B grains “memorize” the crystallographic orientation of the initial Nd2Fe14B phase and transfer it to the recombined Nd2Fe14B grains in the highly textured sample. 3-D tomography of backscattered electron SEM images showed that recombined Nd2Fe14B grains nucleate at the interfaces of Fe2B/NdH2 phases, which grow through the interfaces of NdH2/α-Fe phases during the DR process. Boron segregation was found at the NdH2/α-Fe interfaces, which serve as a boron source for the growth of the recombined Nd2Fe14B grains. The mechanism of the texture development is discussed based on the microstructure observations and the corresponding evolution of magnetic properties.

Journal or Publication Title: Acta Materialia
Volume: 85
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: Nd–Fe–B permanent magnets, d-HDDR process, Microstructure, Texture
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: 10 Feb 2015 09:08
Official URL: http://dx.doi.org/10.1016/j.actamat.2014.11.003
Identification Number: doi:10.1016/j.actamat.2014.11.003
Funders: This work was in part supported by Japan Science Technology Agency, CREST.
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