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Nd-Fe-B type anisotropic exchange spring magnet and method of producing the same

a technology of anisotropy and exchange springs, which is applied in the field of anisotropy of rare earth permanent magnets and a method of producing magnets, can solve the problems of insufficient properties of obtained exchange spring magnets compared to theoretical properties, and achieve the effect of improving the magnetic properties of anisotropy exchange spring magnets and easy production

Inactive Publication Date: 2008-08-21
NISSAN MOTOR CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006]However, it is further required to improve the magnetic property of an anisotropic exchange spring magnet and to develop a method of easily producing such an improved anisotropic exchange spring magnet.

Problems solved by technology

However, a melt spun method or mechanical alloying (MA) method employed in the above magnet producing methods cannot produce the magnet having the magnetic anisotropy, and therefore the property of the obtained exchange spring magnet is not sufficient as compared to the theoretical property.

Method used

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  • Nd-Fe-B type anisotropic exchange spring magnet and method of producing the same
  • Nd-Fe-B type anisotropic exchange spring magnet and method of producing the same
  • Nd-Fe-B type anisotropic exchange spring magnet and method of producing the same

Examples

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example 1

[0069]A thin strip of the rare earth magnet alloy was produced from an alloy ingot having a composition of Nd9.1Fe75.8CO8B6.1V1 by means of the strip casting method. A condition of the strip casting method was that a cooling speed for cooling the melted alloy to a solidification temperature of around 900° C. was set at 2300° C. / sec. By observing a cross-section of the thin strip alloy by means of a SEM (scanning electron microscope), it was confirmed that the thin strip alloy had a mixed structure of the hard magnetic phases and the soft magnetic phases. Substantially the minimum width of the soft magnetic phase was smaller than or equal to 1 μm, and the minimum distance between the soft magnetic phases was greater than or equal to 0.1 μm. The thin strip alloy had a structure such that a surface of the thin strip facing a roller of the strip casting method was more micro-structured than that of the other surface. FIG. 1 is a SEM photograph showing a center area of a cross section of...

example 2

[0077]A thin strip of the rare earth magnet alloy was produced from an alloy ingot having a composition of Nd10Fe75CO8B6V1 by means of the strip casting method and in the same manner as EXAMPLE 1. It was observed that the thin strip alloy has had a mixed structure of the hard magnetic phases and the soft magnetic phases, as a result of observing a cross-section of the thin strip alloy by means of SEM. Substantially the minimum width of the soft magnetic phases was smaller than or equal to 1 μm, and the minimum distance between the soft magnetic phases was greater than or equal to 0.2 μm. Powder for a VSM sample was produced by pulverizing the thin strip alloy into a size smaller than 25 μm using a set of mortar and pestle. The Js ratio of the VSM sample was 1.8.

example 3

[0078]A thin strip of the rare earth magnet alloy was produced from an alloy ingot having a composition of Nd11Fe74CO8B6V1 by means of the strip casting method and in the same manner as EXAMPLE I. It was observed that the thin strip alloy has had a mixed structure of the hard magnetic phases and the soft magnetic phases, as a result of observing a cross-section of the thin strip alloy by means of SEM. Substantially the minimum width of the soft magnetic phase was smaller than or equal to 1 μm, and the minimum distance between the soft magnetic phases was greater than or equal to 0.5 μm. Powder of a VSM sample was produced by pulverizing the thin strip alloy into a size smaller than 25 μm using a set of mortar and pestle. The Js ratio of the VSM sample was 1.8.

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Abstract

A Nd—Fe—B type anisotropic exchange spring magnet is produced by a method of obtaining powder of a Nd—Fe—B type rare earth magnet alloy which comprises hard magnetic phases and soft magnetic phases wherein a minimum width of the soft magnetic phases is smaller than or equal to 1 μm and a minimum distance between the soft magnetic phases is greater than or equal to 0.1 μm, obtaining a compressed powder body by compressing the powder, and obtaining the Nd—Fe—B type anisotropic exchange spring magnet by sintering the compressed powder body using a discharge plasma sintering unit.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to a rare earth permanent magnet having anisotropy and a method of producing the magnet.[0002]Nd—Fe—B type permanent magnets have been widely used as a magnet for a motor. Such magnets have been produced by means of a melting method disclosed in M. Sagawa et al., Japanese Journal of Applied Physics 26 (1987) 785 or a quenching method disclosed in R. W. Lee, Applied Physics Letter 46 (1985) 790. Further, it is possible to produce magnet powder having anisotropy by means of a HDDR treatment disclosed in T. Takeshita et al., Proc. 10th Int. Workshop on Rare Earth Magnets and Their Applications, Kyoto, (1989) 511.[0003]The magnetic properties of Nb—Fe—B type permanent magnets have approached a theoretical limit, and therefore it is desired to develop next-generation high-performance magnets. One of the next-generation magnets is an exchange spring magnet, which is also called nano-composite magnet, as disclosed in E. F. Knel...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B22F3/12B02C17/00B22F1/00H01F1/057H01F41/02
CPCB82Y25/00Y10T428/12014H01F41/0273H01F1/0579
Inventor SHIMADA, MUNEKATSUONO, HIDEAKIONO, TAKAEKANO, MAKOTOTAYU, TETSUROU
Owner NISSAN MOTOR CO LTD
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