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Title:
METHOD FOR PRODUCING RARE-EARTH MAGNET POWDER
Document Type and Number:
WIPO Patent Application WO/2020/017529
Kind Code:
A1
Abstract:
Provided is a method for producing a rare-earth magnet powder having high magnetic characteristics. The present invention is a method for producing a rare-earth magnet powder, the method comprising: a disproportionation step in which a magnet raw material is caused to absorb hydrogen and is subjected to a disproportionation reaction, the magnet raw material being obtained by exposing a casting alloy that contains a rare-earth element (R), boron (B), and a transition element (TM) to a hydrogen atmosphere at a temperature of 350-550°C; and a recombination step in which the hydrogen is removed from the magnet raw material after the disproportionation step, and the magnet raw material is subjected to a recombination reaction. There is no restriction as to the hydrogen partial pressure of the hydrogen atmosphere to which the casting alloy is exposed, but a hydrogen partial pressure of, e.g., 1-250 kPa is preferred. The casting alloy preferably comprises an ingot that is not subjected to a solution treatment in advance before the exposure to the hydrogen atmosphere. Setting the temperature of the hydrogen atmosphere (hydrogen disintegration temperature) within a prescribed range causes cracking to occur mainly in a grain boundary phase and suppresses breakage of a main phase. It is believed that this is reflected even after HDDR and that a magnet powder having high magnetic characteristics has been made obtainable.

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Inventors:
YAMAZAKI MASAO (JP)
SUGIMOTO SATOSHI (JP)
Application Number:
PCT/JP2019/028019
Publication Date:
January 23, 2020
Filing Date:
July 17, 2019
Export Citation:
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Assignee:
AICHI STEEL CORP (JP)
International Classes:
H01F1/057; B22F1/145; B22F9/04; C22C38/00; H01F41/02
Domestic Patent References:
WO2011070827A12011-06-16
Foreign References:
JP2008127648A2008-06-05
JP2003243211A2003-08-29
JP3871219B22007-01-24
JP2008127648A2008-06-05
JP2008305908A2008-12-18
Other References:
See also references of EP 3826036A4
Attorney, Agent or Firm:
MORIOKA Masayuki et al. (JP)
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