Rare-earth magnet and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-2016141083-A1
Application number	US-201414896215-A
Country	US
Kind code	A1
Filing date	Jun 5, 2014
Priority date	Jun 5, 2013
Publication date	May 19, 2016
Grant date	—

Abstract

To provide a rare earth magnet ensuring excellent magnetic anisotropy while reducing the amount of Nd, etc., and a manufacturing method thereof.
A rare earth magnet comprising a crystal grain having an overall composition of (R2 (1-x) R1 x ) y Fe 100-y-w-z-v Co w B z TM v (wherein R2 is at least one of Nd, Pr, Dy and Tb, R1 is an alloy of at least one or two or more of Ce, La, Gd, Y and Sc, TM is at least one of Ga, Al, Cu, Au, Ag, Zn, In and Mn, 0<x<1, y=12 to 20, z=5.6 to 6.5, w=0 to 8, and v=0 to 2), wherein the average grain size of the crystal grain is 1,000 nm or less, the crystal grain consists of a core and an outer shell, the core has a composition of R1 that is richer than R2, and the outer shell has a composition of R2 that is richer than R1.

First claim

1 . A rare earth magnet comprising a crystal grain having an overall composition of (R2 (1-x) R1 x ) y Fe 100-y-w-z-v Co w B z TM v (wherein R2 is at least one of Nd and Pr, R1 is an alloy of at least one or two or more of Ce, La, Gd, Y and Sc, TM is at least one of Ga, Al, Cu, Au, Ag, Zn, In and Mn, 0<x<1, y=12 to 20, z=5.6 to 6.5, w=0 to 8, and v=0 to 2), wherein the average grain size of the crystal grain is 1,000 nm or less, the crystal grain consists of a core and an outer shell, the core has a composition of R1 that is richer than R2, and the outer shell has a composition of R2 that is richer than R1.

2 . A rare earth magnet comprising a crystal grain having an overall composition of (Nd (1-x) Ce x ) y Fe 100-y-w-z-v Co w B z TM v (wherein TM is at least one of Ga, Al, Cu, Au, Ag, Zn, In and Mn, 0<x<1, y=12 to 20, z=5.6 to 6.5, w=0 to 8, and v=0 to 2), wherein the average grain size of the crystal grain is 1,000 nm or less and the crystal grain consists of a core and an outer shell and has a composition of x in the core that is larger than x in the outer shell.

3 . The rare earth magnet according to claim 1 , wherein the average grain size of the crystal grain is 500 nm or less.

4 . A method for manufacturing a rare earth magnet, comprising:
a first step of performing hot pressing by using a magnetic powder containing a crystal grain having a composition of (R2 (1-x) R1 x ) y Fe 100-y-w-z-v Co w B z TM v (wherein R2 is at least one of Nd and Pr, R1 is an alloy of at least one or two or more of Ce, La, Gd, Y and Sc, TM is at least one of Ga, Al, Cu, Au, Ag, Zn, In and Mn, y=12 to 20, z=5.6 to 6.5, w=0 to 8, and v=0 to 2) to produce a rare earth magnet precursor, and a second step of diffusing and impregnating a modifying metal composed of an R2 element or an R2-TM alloy into the rare earth magnet precursor to manufacture a rare earth magnet comprising a crystal grain having an average grain size of 1,000 nm or less and consisting of a core and an outer shell, the core having a composition of R1 that is richer than R2, and the outer shell having a composition of R2 that is richer than R1.

5 . The method for manufacturing a rare earth magnet according to claim 4 , wherein in the first step, hot press working is performed to produce a compact and the compact is subjected to hot plastic working to produce a rare earth magnet precursor.

6 . The method for manufacturing a rare earth magnet according to claim 4 , wherein the average grain size of the crystal grain is 500 nm or less.

7 . A method for manufacturing a rare earth magnet, comprising:
a step of heating an Re-M alloy (wherein Re is at least one of Nd and Sm and M is an element capable of reducing the melting point of the rare earth element by being alloyed) at a temperature not lower than the melting point thereof to melt the alloy, and a step of bringing the molten Re-M alloy into contact with a magnetic particle containing a transition metal element to diffuse Re in the Re-M alloy into the magnetic particle.

8 - 10 . (canceled)

11 . The method according to claim 7 , wherein the melting point of the Re-M alloy is 800° C. or less.

12 . The method according to claim 7 , wherein the M is at least one of Cu, Fe, Al and Ga.

13 . The method according to claim 7 , wherein the transition metal is at least one of Fe, Co and Ni.

Assignees

• Toyota Motor Co Ltd

Inventors

• Ito Masaaki
• Yano Masao
• Kishimoto Hidefumi
• Sakuma Noritsugu
• Shoji Tetsuya
• Manabe Akira

Classifications

• H01F41/0293

  diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets · CPC title

• H01F1/0576

  pressed, e.g. hot working · CPC title

• C22C2202/02

  Magnetic · CPC title

• B22F2009/048

  by pulverising a quenched ribbon · CPC title

• B22F2998/10

  Processes characterised by the sequence of their steps · CPC title