Enhancement of coercivity of Nd-Fe-B ultrafine powders comparable to single domain size by grain boundary diffusion process

S. Sugimoto, M. Nakamura, M. Matsuura, Y. Une, H. Kubo, M. Sagawa

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Nd-Fe-B sintered magnets are widely used in many applications. However, for the use in motors for hybrid electric vehicles (HEV), the development of Dy-free or Dy-lean Nd-Fe-B sintered magnets with high coercivity is desirable. Decreasing grain size of the Nd2Fe14B phase is an established method for increasing coercivity of Nd-Fe-B sintered magnets. We decreased the size of jet-milled powder to around 1 mm by helium (He) jet-milling in Dy-free Nd-Fe-B sintered magnets and obtained high coercivity (μ0 HcJ) of 2 T with (BH)max of around 400 kJm-3 [1]. We also succeeded further decrease in the size to 0.3 μm by combining hydrogenation-disproportionation-desorption-recombination (HDDR), hydrogen decrepitation (HD) and He jet-milling [2, 3]. However, the effect of annealing on magnetic properties of the ultrafine powders was not clear. On the other hand, the grain boundary diffusion (GBD) process [4-6] is well known as an effective method for the enhancement of coercivity. However, the effect for the ultrafine powders has not been investigated. Therefore, in this investigation, we investigated the effects of annealing and GBD process on coercivity of the Nd-Fe-B ultrafine jet-milled powders prepared by our developed process which combined HDDR, HD and He jet-milling.

Original languageEnglish
Title of host publication2015 IEEE International Magnetics Conference, INTERMAG 2015
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Electronic)9781479973224
DOIs
Publication statusPublished - 2015 Jul 14
Event2015 IEEE International Magnetics Conference, INTERMAG 2015 - Beijing, China
Duration: 2015 May 112015 May 15

Publication series

Name2015 IEEE International Magnetics Conference, INTERMAG 2015

Other

Other2015 IEEE International Magnetics Conference, INTERMAG 2015
Country/TerritoryChina
CityBeijing
Period15/5/1115/5/15

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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