TY - GEN
T1 - Enhancement of coercivity of Nd-Fe-B ultrafine powders comparable to single domain size by grain boundary diffusion process
AU - Sugimoto, S.
AU - Nakamura, M.
AU - Matsuura, M.
AU - Une, Y.
AU - Kubo, H.
AU - Sagawa, M.
N1 - Publisher Copyright:
© 2015 IEEE.
PY - 2015/7/14
Y1 - 2015/7/14
N2 - 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.
AB - 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.
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U2 - 10.1109/INTMAG.2015.7156599
DO - 10.1109/INTMAG.2015.7156599
M3 - Conference contribution
AN - SCOPUS:84942475201
T3 - 2015 IEEE International Magnetics Conference, INTERMAG 2015
BT - 2015 IEEE International Magnetics Conference, INTERMAG 2015
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 2015 IEEE International Magnetics Conference, INTERMAG 2015
Y2 - 11 May 2015 through 15 May 2015
ER -