(19)
(11) EP 0 338 597 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
13.11.1991 Bulletin 1991/46

(43) Date of publication A2:
25.10.1989 Bulletin 1989/43

(21) Application number: 89111005.8

(22) Date of filing: 27.02.1985
(51) International Patent Classification (IPC)4: H01F 1/053
(84) Designated Contracting States:
BE CH DE FR GB IT LI NL SE

(30) Priority: 28.02.1984 JP 36923/84
28.02.1984 JP 36924/84
28.02.1984 JP 36925/84
28.02.1984 JP 36926/84

(62) Application number of the earlier application in accordance with Art. 76 EPC:
85102200.4 / 0153744

(71) Applicant: SUMITOMO SPECIAL METALS CO., LTD.
Osaka (JP)

(72) Inventors:
  • Yamamoto, Hitoshi
    Mashima-gun Osaka-fu (JP)
  • Sagawa, Masato
    Nagaokakyo-shi Kyoto-fu (JP)
  • Fujimura, Setsuo
    1-ban Ukyo-ku Kyoto (JP)
  • Matsuura, Yutaka
    Ibaraki-shi Osaka-fu (JP)

(74) Representative: Diehl, Hermann O. Th., Dr. et al
Diehl, Glaeser, Hiltl & Partner Patentanwälte Postfach 19 03 65
80603 München
80603 München (DE)


(56) References cited: : 
   
       


    (54) Permanent magnets


    (57) Permanent magnet materials, produced according to the following steps:
    forming an alloy powder having a mean particle size of 0.3-80 µm and composed of, in atomic percentage, 8-30 % R (provided that R is at least one of rare earth elements including Y), 2-­28 % B, and the balance Fe and inevitable impurities,
    sintering the formed body at a temperature of 900-1200°C,
    subjecting the sintered body to a primary heat treatment at a temperature of 750-1000°C,
    then cooling the resultant body to a temperature of no higher than 680°C at a cooling rate of 3-2000°C/min, and
    further subjecting the thus cooled body to a secondary heat treatment at a temperature of 480-700°C.
    Magnets having an energy product (BH)max of at least 20 MGOe and a coercitive force (iHc) of at least 10 kOe or magnets having an energy product (BH)max of 40 MGOe or more can be obtained by specific compositions.







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