# US 2018/0025818 A1 · Sintered r-tm-b magnet

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- Number: US 2018/0025818 A1
- Document ID: US20180025818A1
- Status: Published application
- Kind: A1
- Application number: 15/549,777
- Filed: 2016-03-22
- Published: 2018-01-25
- Earliest claimed: 2015-03-27
- Assignees: Hitachi Metals, Ltd.
- Applicants: Hitachi Metals, Ltd.
- Inventors: Daisuke YAMAMICHI; Masanao KAMACHI; Rintaro ISHII; Takahiro KATOU
- Web page: https://patentgrep.com/patent/US20180025818A1

## CPC

- B22F 3/00: Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor {; Presses and furnaces}
- C22C 33/02: by powder metallurgy
- C22C 38/00: Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00)
- C22C 38/005: {containing rare earths, i.e. Sc, Y, Lanthanides}
- C22C 38/06: containing aluminium
- C22C 38/10: containing cobalt
- C22C 38/16: containing copper
- H01F 1/057: and IIIa elements, e.g. Nd2Fe14B
- H01F 1/0577: {sintered}
- H01F 1/08: pressed, sintered, or bound together
- H01F 7/02: Permanent magnets {[PM]}
- B22F 9/04: starting from solid material, e.g. by crushing, grinding or milling ({C22C1/1084 takes precedence}; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C)
- B22F 2009/044: {by jet milling}
- 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)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

A sintered R-TM-B magnet comprising 24.5-34.5% by mass of R, which is at least one selected from rare earth elements including Y, 0.85-1.15% by mass of B, less than 0.1% by mass of Co, 0.07-0.5% by mass of Ga, and 0-0.4% by mass of Cu, the balance being Fe and inevitable impurities; the amounts (% by mass) of Ga and Cu being in a region of a pentagon defined by a point A (0.5, 0.0), a point B (0.5, 0.4), a point C (0.07, 0.4), a point D (0.07, 0.1) and a point E (0.2, 0.0), on an X-Y plane in which the X-axis represents the amount of Ga, and the Y-axis represents the amount of Cu.

## Claims

### Claim 1

A sintered R-TM-B magnet comprising 24.5-34.5% by mass of R, wherein R is at least one selected from rare earth elements including Y, 0.85-1.15% by mass of B, less than 0.1% by mass of Co, 0.07-0.5% by mass of Ga, and 0-0.4% by mass of Cu, the balance being Fe and inevitable impurities; the amounts (% by mass) of Ga and Cu being in a region of a pentagon defined by a point A (0.5, 0.0), a point B (0.5, 0.4), a point C (0.07, 0.4), a point D (0.07, 0.1) and a point E (0.2, 0.0), on an X-Y plane in which an X-axis represents the amount of Ga, and a Y-axis represents the amount of Cu.

### Claim 2 (depends on 1)

The sintered R-TM-B magnet according to claim 1, further comprising 3% or less by mass of M, wherein M is at least one selected from Zr, Nb, Hf, Ta, W, Mo, Al, Si, V, Cr, Ti, Ag, Mn, Ge, Sn, Bi, Pb and Zn.

### Claim 3 (depends on 1)

The sintered R-TM-B magnet according to claim 1, wherein the amounts (% by mass) of Ga and Cu are in a region of a pentagon defined by a point A (0.5, 0.0), a point B (0.5, 0.4), point C′ (0.1, 0.4), point D′ (0.1, 0.1) and a point E (0.2, 0.0), on an X-Y plane in which the X-axis represents the amount of Ga, and the Y-axis represents the amount of Cu.

### Claim 4 (depends on 1)

The sintered R-TM-B magnet according to claim 1, wherein said sintered R-TM-B magnet is a radially anisotropic, cylindrical magnet or a polar-anisotropic, cylindrical magnet.

### Claim 5 (depends on 1)

The sintered R-TM-B magnet according to claim 1, wherein its weight loss by corrosion by a pressure cooker test at 120° C., 100% RH and 2 atom for 96 hours is less than 2 mg/cm2.