# US 2021/0241949 A1 · Cast alloy flakes for r-t-b rare earth sintered magnet

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- Number: US 2021/0241949 A1
- Document ID: US20210241949A1
- Status: Published application
- Kind: A1
- Application number: 17/052,418
- Filed: 2019-05-07
- Published: 2021-08-05
- Earliest claimed: 2018-05-17
- Assignees: TDK Corporation
- Applicants: TDK Corporation
- Inventors: Akifumi MURAOKA
- Web page: https://patentgrep.com/patent/US20210241949A1

## CPC

- H01F 1/0577: {sintered}
- B23K 35/362: Selection of compositions of fluxes (B23K35/365, B23K35/368 take precedence)
- C22C 37/00: Cast-iron alloys
- C22C 38/00: Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00)
- H01F 41/02: for manufacturing cores, coils, or magnets (H01F41/14 takes precedence; for dynamo-electric machines H02K15/00)
- Y02T 10/64: Electric machine technologies in electromobility
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Cast alloy flakes for a R-T-B based rare earth sintered magnet include R (a cast alloy flakes rare earth element), T (a mixture of Fe or Fe and a transition metal (except for Fe and Cu)), M (one or more metals selected from Al, Ga and Cu), and B, wherein R is in the range of 28 to 33% by mass, B is in the range of 0.8 to 1.1% by mass, and M is in the range of 0.1 to 2.7% by mass, and the balance T and impurities. The cast alloy flakes have an area ratio of an R-rich phase in the range of 0.03% to 5% on the roll surface of the cast alloy flakes, or have a content of a coarse R-rich phase having a short axis length of 20 μm or more in the R-rich phase of 20 pieces or less.

## Claims

### Claim at position 1

1-2. (canceled)

### Claim 3

Cast alloy flakes for an R-T-B based rare earth sintered magnet, comprising:
R which is a rare earth element;
T which is Fe or a mixture of Fe and a transition metal (except for Fe and Cu);
M which is one or more metals selected from the group consisting of Al, Ga, and Cu; and
B,
wherein the cast alloy flakes comprises R in a range of 28% by mass to 33% by mass;
the cast alloy flakes comprises B in a range of 0.8% by mass to 1.1% by mass;
the cast alloy flakes comprises M in a range of 0.1% by mass to 2.7% by mass;
a remainder consists of T and inevitable impurities;
one surface of the cast alloy flakes is a roll surface; and
an area ratio of a R-rich phase on the roll surface is in a range of 0.03% to 5%.

### Claim 4 (depends on 3)

The cast alloy flakes for an R-T-B based rare earth sintered magnet according to claim 3,
wherein the cast alloy flakes comprises Cu in a range of 0% by mass to 1.0% by mass;
the cast alloy flakes comprises Al in a range of from 0% by mass to 0.7% by mass; and
the cast alloy flakes comprises Ga in a range of 0% by mass to 1.0% by mass.

### Claim 5 (depends on 3)

The cast alloy flakes for an R-T-B based rare earth sintered magnet according to claim 3,
wherein the inevitable impurities comprises oxygen; and
the cast alloy flakes comprises oxygen of 0.10 mass % or less.

### Claim 6

Cast alloy flakes for an R-T-B based rare earth sintered magnet, comprising:
R which is a rare earth element;
T which is Fe or a mixture of Fe and a transition metal (except for Fe and Cu);
M which is one or more metals selected from the group consisting of Al, Ga, and Cu; and
B,
wherein the cast alloy flakes comprises R in a range of 28% by mass to 33% by mass;
the cast alloy flakes comprises B in a range of 0.8% by mass to 1.1% by mass;
the cast alloy flakes comprises M in a range of 0.1% by mass to 2.7% by mass;
a remainder consists of T and inevitable impurities;
one surface of the cast alloy flakes is a roll surface; and
when an R-rich phase having a short axis length of 20 μm or more is defined as a coarse R-rich phase, among the R-rich phases on the roll surface, a content of the coarse R-rich phase in the R-rich phase is 20% by number or less.

### Claim 7 (depends on 6)

The cast alloy flakes for an R-T-B based rare earth sintered magnet according to claim 6,
wherein the cast alloy flakes comprises Cu in a range of 0% by mass to 1.0% by mass;
the cast alloy flakes comprises Al in a range of from 0% by mass to 0.7% by mass; and
the cast alloy flakes comprises Ga in a range of 0% by mass to 1.0% by mass.

### Claim 8 (depends on 6)

The cast alloy flakes for an R-T-B based rare earth sintered magnet according to claim 6,
wherein the inevitable impurities comprises oxygen; and
the cast alloy flakes comprises oxygen of 0.10 mass % or less.