Magnetic properties on bulk exchange-spring magnets in Nd-Fe-Co-V-B system formed by Spark Plasma Sintering

Hideaki Ono, Munekatsu Shimada, Akira Fujiki, Hiroshi Yamamoto, Masayuki Sonoda, Masato Tani

Research output: Contribution to journalArticle

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Abstract

Bulk exchange-spring magnets of Nd11Fe72Co8V1.5B7.5 and Nd9Fe76Co8V1B6 alloys were prepared by Spark Plasma Sintering (SPS) using the rapidly quenched ribbon powders. The effects of SPS process conditions on magnetic properties and structures were investigated. SPS is a type of solid compression sintering similar to hot-pressing (HP) and can be performed at lower temperature with a shorter holding time. Bulk magnets reached to approximately full density at a sintering temperature of higher than 650 °C for 5 min. and had magnetically isotropic properties. They indicated the spring back phenomenon peculiar to exchange-spring magnets and consisted of multiphase of the Nd2Fe14B type phase and the α-Fe type phase. Grain growth did not occurred between the powders of the starting ribbons, but the fine crystals were observed inner the powders of the ribbons with an increase in the sintering temperature. Optimum preparation conditions and magnetic properties were as follows: composition, Nd9Fe76Co8V1B6; surface velocity of the roller during melt spinning for starting ribbons, Vs = 20 m/s; SPS condition, at 675 °C for 5 min. under 490 MPa; magnetic and other properties, Bt = 0.99 T, HcJ = 415 kA/m, (BH)max = 107.8 kJ/m3, Hk/HcJ×100 = 23%, spring back ratio = 40% and D = 7.59 Mg/m3.

Original languageEnglish
Pages (from-to)667-673
Number of pages7
JournalFuntai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy
Volume47
Issue number6
Publication statusPublished - 2000 Jun
Externally publishedYes

Fingerprint

Spark plasma sintering
Magnets
Magnetic properties
Powders
Sintering
Melt spinning
Magnetic structure
Hot pressing
Grain growth
Surface structure
Temperature
Compaction
Crystals

ASJC Scopus subject areas

  • Mechanical Engineering
  • Metals and Alloys

Cite this

Magnetic properties on bulk exchange-spring magnets in Nd-Fe-Co-V-B system formed by Spark Plasma Sintering. / Ono, Hideaki; Shimada, Munekatsu; Fujiki, Akira; Yamamoto, Hiroshi; Sonoda, Masayuki; Tani, Masato.

In: Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Vol. 47, No. 6, 06.2000, p. 667-673.

Research output: Contribution to journalArticle

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