Granted Patent B2

US 12,731,709 · App. 17/906,446 · Granted Sep 8, 2026

Inventors: Tadao Nomura (Fukui, JP); Kazuki Otsuka (Echizen, JP); Masayuki Kamata (Tsuruga, JP)

Assignee: SHIN-ETSU CHEMICAL CO., LTD.

H01F1/0593B22F3/12B22F3/24C22C38/10H01F41/0266H01F41/0293C22C2202/02

Abstract

Claims (24)

1 . An anisotropic rare earth sintered magnet represented by the formula (R 1-a Zr a ) x (Fe 1-b Co b ) 100-x-y (M 1 1-c M 2 c ) y

wherein:

R is a combination of Sm and one or more elements selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu;

M 1 is at least one element selected from the group consisting of V, Cr, Mn, Ni, Cu, Zn, Ga, Al, and Si;

M 2 is at least one element selected from the group consisting of Ti, Nb, Mo, Hf, Ta, and W;

x, y, a, b, and c each satisfy 7≤x≤15 at %, 4≤y≤20 at %, 0≤a≤0.2, 0≤b≤0.5, and 0≤c≤0.9; and

the magnet comprises 80% by volume or more of a main phase composed of a compound of a ThMn 12 type crystal, the main phase having an average crystal grain size of 1 μm or more, and containing an R-rich phase and an R(Fe,Co) 2 phase in a grain boundary portion, the R-rich phase containing R in an amount of 40 at % or more, and a Sm/R ratio in an inner portion of the main phase grain being lower than Sm/R ratios of the R-rich phase and the R(Fe,Co) 2 phase.

2 . The anisotropic rare earth sintered magnet according to claim 1 , which comprises the R-rich phase and the R(Fe,Co) 2 phase in an amount of 1% by volume or more in total.

3 . The anisotropic rare earth sintered magnet according to claim 1 , wherein the R(Fe,Co) 2 phase is a phase exhibiting ferromagnetism or ferrimagnetism at room temperature or higher.

4 . The anisotropic rare earth sintered magnet according to claim 1 , wherein a Sm/R ratio in an inner portion of the main phase grain is lower than a Sm/R ratio in an outer shell portion of the main phase grain.

5 . The anisotropic rare earth sintered magnet according to claim 1 , wherein Sm is not contained in the inner portion of the main phase grain.

6 . The anisotropic rare earth sintered magnet according to claim 1 , wherein the magnet exhibits a coercive force of 5 kOe or more at room temperature, and a temperature coefficient β of the coercive force is −0.5%/K or more.

7 . A method for producing the anisotropic rare earth sintered magnet according to claim 1 , the method comprising:

pulverizing an alloy comprising a compound phase of a ThMn 12 type crystal to produce a pulverized alloy;

compacting the pulverized alloy under application of a magnetic field to form a compact; and

sintering the compact at a temperature of 800° C. or higher and 1400° C. or lower to obtain a sintered body as the anisotropic rare earth sintered magnet.

8 . The method for producing an anisotropic rare earth sintered magnet according to claim 7 ,

wherein the pulverizing comprises pulverizing and mixing the alloy comprising a compound phase of a ThMn 12 type crystal with an alloy having a higher R composition ratio and a higher Sm/R ratio to produce the pulverized alloy.

9 . The method for producing an anisotropic rare earth sintered magnet according to claim 7 , further comprising:

contacting a material comprising Sm with the sintered body; and

heating at a temperature of 600° C. or higher and a sintering temperature or lower to diffuse Sm into the sintered body.

10 . The method for producing an anisotropic rare earth sintered magnet according to claim 9 , wherein the material comprising Sm to be brought into contact with the sintered body is at least one selected from Sm metal, Sm-containing alloy, Sm-containing compound, and Sm-containing vapor, and a form thereof is at least one selected from powder, film, strip, foil, and gas.

11 . The method for producing an anisotropic rare earth sintered magnet according to claim 7 , further comprising:

heating the sintered body at a temperature of 300 to 900° C.

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (23)