Fabrication methods for R-Fe-B permanent magnets

Details Fabrication methods for R-Fe-B permanent magnets Fabrication methods for R-Fe-B permanent magnets

1995-09-06

1997-09-09

Jordan, Charles T.

Powder metallurgy processes

Powder metallurgy processes with heating or sintering

Metal and nonmetal in final product

419 23, 419 42, 148103, B22F 100

Patent

active

056666357

ABSTRACT:
This invention, using finely ground powders obtained by either a ingot grinding method, a Ca reduction diffusion method or a strip casting method, proposes a fabrication method for high-performance R--Fe--B permanent magnets with excellent press packing characteristics, a high degree of orientation of the magnetization direction of each crystallite and a total sum of A, (BH)max (MGOe) and B, iHc (kOe), A+B greater than 59.5. Here, cast alloys or ground alloys are coarse ground by mechanical grinding or by a H.sub.2 absorption and decomposition method, and then fine ground by either mechanical grinding or by a jet mill grinding process to yield R--Fe--B fine powders with an average particle size of 1.0 .mu.m.about.10 .mu.m. These powders are then packed into a mold at a packing density of 1.4.about.3.5 g/cm.sup.3, a pulsed magnetic field with a field intensity greater than 10 kOe is applied so as to repeatedly invert the magnetization direction, and finally cold isostatic pressing is performed in a static magnetic field.

REFERENCES:
patent: 5527504 (1996-06-01), Kishimoto et al.
patent: 5575830 (1996-11-01), Yamashita et al.

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