R-T-B BASED SINTERED MAGNET

Title:

R-T-B BASED SINTERED MAGNET

Document Type and Number:

WIPO Patent Application WO/2006/098204

Kind Code:

A1

Abstract:

An R-T-B based sintered magnet having a high residual magnetic flux density and a high coercive force in combination is provided. An R-T-B based sintered magnet, which includes a main phase crystal grain (1) having a core-shell structure comprising an inner shell part (2) and an outer shell part (3) surrounding the inner shell part (2). The concentration of a heavy rare earth element in the inner shell part (2) is lower by 10 % or more than the concentration of a heavy rare earth element around the perimeter of the outer shell part (3), and the main phase crystal grain (1) having a core-shell structure comprising the inner shell part (2) and the outer shell part (3) has a (L/r)_ave in the range of 0.03 to 0.40, wherein L: a minimum distance from the perimeter of the main phase crystal grain (1) to the inner shell part (2), r: a diameter of the circle equivalent to the main phase crystal grain (1), and (L/r)_ave: an average value of L/r of the main phase crystal grain (1) having a core-shell structure being present in the above sintered article.

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Inventors:

KATO EIJI (JP)
ISHIZAKA CHIKARA (JP)

Application Number:

PCT/JP2006/304509

Publication Date:

September 21, 2006

Filing Date:

March 08, 2006

Export Citation:

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Assignee:

TDK CORP (JP)
KATO EIJI (JP)
ISHIZAKA CHIKARA (JP)

International Classes:

H01F1/08; H01F1/053

Domestic Patent References:

WO2002061769A1

2002-08-08

Foreign References:

JPH0696928A	1994-04-08
JPS62206802A	1987-09-11
JP2004304038A	2004-10-28
JPH0521218A	1993-01-29
JPH0510806B2	1993-02-10
JPH07122413A	1995-05-12
JP2000188213A	2000-07-04

Other References: