Method of manufacturing rare earth magnet

Patent metadata

Field	Value
Publication number	US-10347418-B2
Application number	US-201415104369-A
Country	US
Kind code	B2
Filing date	Dec 17, 2014
Priority date	Dec 19, 2013
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A method includes: manufacturing a sintered compact represented by (Rl)x(Rh)yTzBsMt and has a grain boundary phase; manufacturing a rare earth magnet precursor from the sintered compact; and performing a heat treatment on the rare earth magnet precursor at 450° C. to 700° C. to diffuse and to infiltrate a melt of a modified alloy containing a light rare earth element and either a transition metal element, Al, In, Zn, or Ga into the grain boundary phase. Rl represents a light rare earth element. Rh represents Dy or Tb. T represents a transition metal containing at least one of Fe, Ni, and Co. B represents boron. M represents at Ga, Al, or Cu. x, y, z, s, and t represent mass % of Rl, Rh, T, B, and M. Following expressions are established: 27≤x≤44, 0≤y≤10, z=100−x−y−s−t, 0.75≤s≤3.4, 0≤t≤3. An infiltration amount of the modified alloy is 0 mass % to 5 mass %.

First claim

The invention claimed is:

1. A method of manufacturing a rare earth magnet comprising:
manufacturing a sintered compact which has a composition represented by (Rl) x (Rh) y T z B s M t and has a structure including a main phase and a grain boundary phase;
manufacturing a rare earth magnet precursor by performing hot deformation processing on the sintered compact, and manufacturing a rare earth magnet by performing a heat treatment on the rare earth magnet precursor in a temperature range of 450° C. to 700° C. so as to diffuse and to infiltrate a melt of a modified alloy into a surface region of the grain boundary phase of the rare earth magnet precursor, the modified alloy containing a light rare earth element and one of a transition metal element, Al, In, Zn, and Ga, wherein
Rl represents at least one of light rare earth element or Y,
Rh represents Dy or Tb,
T represents a transition metal and T is at least one of Fe, Ni, and Co,
B represents boron,
M represents at least one of Ga, Al, and Cu,
x, y, z, s, and t respectively represent percentages by mass of Rl, Rh, T, B, and M in the sintered compact,
x, y, z, s, and t are expressed by the following expressions: 27
an infiltration amount of the melt of the modified alloy infiltrated into the surface region of the grain boundary phase is more than 0 mass % and less than 5 mass % with respect to the rare earth magnet precursor, and
the surface region is defined as a depth of up to 2a/3 where a represents a distance from a surface to a center of the rare earth magnet.

2. The method according to claim 1 , wherein
a holding time during the heat treatment is 5 minutes to 3 hours.

3. The method according to claim 2 , wherein
the holding time during the heat treatment is 30 minutes to 3 hours.

4. The method according to claim 1 , wherein
the modified alloy has at least one of a melting point and an eutectic point in the temperature range of 450° C. to 700° C., and
the modified alloy is an alloy containing at least one of Nd and Pr and one of Cu, Co, Mn, In, Zn, Al, Ag, Ga, and Fe.

5. The method according to claim 1 , wherein
the infiltration amount of the melt of the modified alloy is at least 1 mass % and at most 2 mass % with respect to the rare earth magnet precursor.

Assignees

• Toyota Motor Co Ltd

Inventors

• Sakuma Noritsugu
• Shoji Tetsuya
• Sakuma Daisuke
• Haga Kazuaki

Classifications

• B22F1/09

  Mixtures of metallic powders · CPC title

• H01F1/0577 Primary

  sintered · CPC title

• C22C38/16

  containing copper · CPC title

• H01F41/0293 Primary

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

• C22C38/06

  containing aluminium · CPC title