# US 2019/0172616 A1 · R-t-b based permanent magnet

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- Number: US 2019/0172616 A1
- Document ID: US20190172616A1
- Status: Published application
- Kind: A1
- Application number: 16/202,936
- Filed: 2018-11-28
- Published: 2019-06-06
- Earliest claimed: 2017-12-05
- Assignees: TDK Corporation
- Applicants: TDK Corporation
- Inventors: Hiroshi DOTO; Kiyoyuki MASUZAWA; Makoto NAKANE
- Web page: https://patentgrep.com/patent/US20190172616A1

## CPC

- H01F 1/0577: {sintered}
- H01F 41/0293: {diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets}
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

An R-T-B based permanent magnet in which R is a rare earth element, T is Fe and Co, and B is boron. R at least includes Dy. The R-T-B based permanent magnet includes M, and M is at least one or more elements selected from the group consisting of Cu, Ga, Al, Mn, Zr, Ti, Cr, Ni, Nb, Ag, Hf, Ta, W, Si, Bi, and Sn. M at least includes Cu. A total content of R is 28.0 mass % to 30.2 mass %, a content of Dy is 1.0 mass % to 6.5 mass %, a content of Cu is 0.04 mass % to 0.50 mass %, a content of Co is 0.5 mass % to 3.0 mass %, and a content of B is 0.85 mass % to 0.95 mass %.

## Claims

### Claim 1

An R-T-B based permanent magnet comprising M wherein,
R is a rare earth element, T is Fe and Co, and B is boron,
R at least includes Dy,
M is one or more elements selected from Cu, Ga, Al, Mn, Zr, Ti, Cr, Ni, Nb, Ag, Hf, Ta, W, Si, Bi, and Sn,
M at least includes Cu, and
a total content of R is 28.0 mass % to 30.2 mass %, a content of Dy is 1.0 mass % to 6.5 mass %, a content of Cu is 0.04 mass % to 0.50 mass %, a content of Co is 0.5 mass % to 3.0 mass %, and a content of B is 0.85 mass % to 0.95 mass %.

### Claim 2 (depends on 1)

The R-T-B based permanent magnet according to claim 1, wherein the total content of R is 29.2 mass % to 30.2 mass %.

### Claim 3 (depends on 1)

The R-T-B based permanent magnet according to claim 1, wherein R at least includes Nd.

### Claim 4 (depends on 2)

The R-T-B based permanent magnet according to claim 2, wherein R at least includes Nd.

### Claim 5 (depends on 1)

The R-T-B based permanent magnet according to claim 1, wherein R at least includes Pr, and a content of Pr is more than 0 and 10.0 mass % or less.

### Claim 6 (depends on 2)

The R-T-B based permanent magnet according to claim 2, wherein R at least includes Pr, and a content of Pr is more than 0 and 10.0 mass % or less.

### Claim 7 (depends on 3)

The R-T-B based permanent magnet according to claim 3, wherein R at least includes Pr, and a content of Pr is more than 0 and 10.0 mass % or less.

### Claim 8 (depends on 4)

The R-T-B based permanent magnet according to claim 4, wherein R at least includes Pr, and a content of Pr is more than 0 and 10.0 mass % or less.

### Claim 9 (depends on 1)

The R-T-B based permanent magnet according to claim 1, wherein an atomic ratio of TRE/B is 2.19 to 2.60, where TRE is the total content of R.

### Claim 10 (depends on 2)

The R-T-B based permanent magnet according to claim 2, wherein an atomic ratio of TRE/B is 2.19 to 2.60, where TRE is the total content of R.

### Claim 11 (depends on 3)

The R-T-B based permanent magnet according to claim 3, wherein an atomic ratio TRE/B is 2.19 to 2.60, where TRE is the total content of R.

### Claim 12 (depends on 4)

The R-T-B based permanent magnet according to claim 4, wherein an atomic ratio of TRE/B is 2.19 to 2.60, where TRE is the total content of R.

### Claim 13 (depends on 5)

The R-T-B based permanent magnet according to claim 5, wherein an atomic ratio of TRE/B is 2.19 to 2.60, where TRE is the total content of R.

### Claim 14 (depends on 6)

The R-T-B based permanent magnet according to claim 6, wherein an atomic ratio of TRE/B is 2.19 to 2.60, where TRE is the total content of R.

### Claim 15 (depends on 7)

The R-T-B based permanent magnet according to claim 7, wherein an atomic ratio of TRE/B is 2.19 to 2.60, where TRE is the total content of R.

### Claim 16 (depends on 8)

The R-T-B based permanent magnet according to claim 8, wherein an atomic ratio of TRE/B is 2.19 to 2.60, where TRE is the total content of R.

### Claim 17 (depends on 1)

The R-T-B based permanent magnet according to claim 1, wherein an atomic ratio of Pr/TRE is 0 or more and less than 0.25, where TRE is the total content of R.

### Claim 18 (depends on 2)

The R-T-B based permanent magnet according to claim 2, wherein an atomic ratio of Pr/TRE is 0 or more and less than 0.25, where TRE is the total content of R.

### Claim 19 (depends on 1)

The R-T-B based permanent magnet according to claim 1, wherein an atomic ratio of 14B/(Fe+Co) is larger than 0 and 1.01 or less.

### Claim 20 (depends on 2)

The R-T-B based permanent magnet according to claim 2, wherein an atomic ratio of 14B/(Fe+Co) is larger than 0 and 1.01 or less.