d-HDDR processing of Nd-Fe-B based alloys to obtain highly anisotropic nanocrystalline powders
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Materials Science Forum
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The HDDR (hydrogenation-disproportionation-desorption-recombination) process is an
established powder metallurgy route to obtain Nd–Fe–B nanocrystalline powders for bonded
magnets manufacturing. Therefore, both conventional (c-HDDR) and dynamic HDDR (d-HDDR)
processes has been investigated to obtain Nd-Fe-B-based powders with different characteristics.
Magnetic properties were measured by means of a hysteresisgraph and the powder obtained by d-
HDDR showed strong anisotropy, allowing a Br of 1.1 T in the bonded magnet, whereas c-HDDR
powder was isotropic with a Br of 0.6 T. Microstructural changes were characterized by X-ray
diffraction (DRX) and scanning electron microscopy (SEM). X-ray patters of anisotropic powders
made by d-HDDR showed high intensity reflection peaks indexed as (004), (105) and (006) planes
in the aligning direction, due the texture inducement in c-axis of the main phase (Nd2Fe14B).
However, SEM micrographs of c-HDDR powder showed a more homogeneous microstructure, with
grain size of ~300 nm, when compared to d-HDDR powder that ranged from 300 nm to 500 nm.
This difference is assumed to be the cause of lower intrinsic coercivity found in the c-HDDR
powder.
Como referenciar
ENGERROFF, JULIANO A.B.; KELLER, FREDERICO O.; LOPES, LEONARDO U.; MASCHERONI, ARTHUR A.; TAKIISHI, HIDETOSHI; WENDHAUSEN, PAULO A.P. d-HDDR processing of Nd-Fe-B based alloys to obtain highly anisotropic nanocrystalline powders. Materials Science Forum, v. 899, p. 563-566, 2017. DOI: 10.4028/www.scientific.net/MSF.899.563. Disponível em: http://repositorio.ipen.br/handle/123456789/29078. Acesso em: 30 Dec 2025.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.