# US 12,119,150 B2 · Method for producing sintered magnet and sintered magnet

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- Number: US 12,119,150 B2
- Document ID: US12119150B2
- Status: Granted
- Kind: B2
- Application number: 17/288,661
- Filed: 2020-09-24
- Published: 2021-12-23
- Granted: 2024-10-15
- Earliest claimed: 2019-09-26
- Assignees: LG Chem, Ltd.
- Applicants: LG Chem, Ltd.
- Inventors: Nakheon Sung; Ingyu Kim; Soon Jae Kwon; Jinhyeok Choe; Hyounsoo Uh; Tae Hoon Kim
- Web page: https://patentgrep.com/patent/US12119150B2

## CPC

- H01F 1/0577: {sintered}
- B22F 1/148: Agglomerating
- B22F 3/1003: {Use of special medium during sintering, e.g. sintering aid}
- B22F 3/1035: {Liquid phase sintering}
- B22F 3/24: After-treatment of workpieces or articles {(B22F3/1146 takes precedence)}
- C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60}
- C22C 38/005: {containing rare earths, i.e. Sc, Y, Lanthanides}
- C22C 38/06: containing aluminium
- C22C 38/16: containing copper
- H01F 41/0266: {Moulding; Pressing (H01F41/0273 takes precedence; hard magnetic particles H01F1/06, H01F1/11)}
- B22F 9/20: starting from solid metal compounds
- B22F 2003/248: {Thermal after-treatment}
- B22F 2201/11: Argon
- B22F 2301/355: Rare Earth - Fe intermetallic alloys
- B22F 2998/10: Processes characterised by the sequence of their steps
- B22F 2999/00: Aspects linked to processes or compositions used in powder metallurgy
- C22C 2202/02: Magnetic
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

A sintered magnet and a method for producing the same are provided. The method includes producing an R—Fe—B-based magnet powder by a reduction-diffusion method, adding a R—Al—Cu powder as a sintering agent to the R—Fe—B-based magnet powder to form a mixed powder, wherein the R—Al—Cu powder is an alloy of R, Al and Cu, and R is Nd, Pr, Dy, Tb or Ce, and sintering the mixed powder to form a sintered magnet.

## Claims

### Claim 1

A method for producing a sintered magnet, comprising:
producing an R—Fe—B-based magnet powder by a reduction-diffusion method,
adding a R—Al—Cu powder as a sintering agent to the R—Fe—B-based magnet powder to form a mixed powder, wherein the R—Al—Cu powder is an alloy of R, Al and Cu, and R is Nd, Pr, Dy, Tb or Ce,
sintering the mixed powder to form a sintered magnet, and
forming the R—Al—Cu powder as the sintering agent,
wherein the forming the R—Al—Cu powder comprises:
mixing RH2 powder, Al powder, and Cu powder to form a sintered precursor,
agglomerating the sintered precursor,
raising a temperature of the agglomerated sintered precursor to form a metal alloy, and
pulverizing the metal alloy to form the sintering agent.

### Claim 2 (depends on 1)

The method according to claim 1, further comprising wrapping the agglomerated sintered precursor in a metal foil when raising the temperature of the agglomerated sintered precursor.

### Claim 3 (depends on 2)

The method according to claim 2,
wherein the metal foil is Mo or Ta.

### Claim 4 (depends on 2)

The method according to claim 2,
wherein when wrapping the agglomerated sintered precursor in the metal foil and raising the temperature, the temperature is raised in an argon gas atmosphere.

### Claim 5 (depends on 1)

The method according to claim 1,
wherein the forming the sintered precursor further comprises mixing a liquid Ga.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the forming the metal alloy further comprises:
wrapping the agglomerated sintered precursor in a metal foil, raising the temperature up to 900 degrees Celsius to 1050 degrees Celsius, and then performing an additional heat treatment.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the agglomerating the sintered precursor uses any one of hydraulic pressing, tapping, or cold isostatic pressing (CIP).

### Claim 8 (depends on 1)

The method according to claim 1, further comprising:
adding a NdH2 powder to the R—Al—Cu powder as the sintering agent.