# US 11,993,836 B2 · R-FE-B-based sintered magnet with low B content and preparation method therefor

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- Number: US 11,993,836 B2
- Document ID: US11993836B2
- Status: Granted
- Kind: B2
- Application number: 16/964,645
- Filed: 2019-06-17
- Published: 2021-02-25
- Granted: 2024-05-28
- Earliest claimed: 2018-06-19
- Assignees: FUJIAN GOLDEN DRAGON RARE-EARTH Co., Ltd.
- Applicants: FUJIAN GOLDEN DRAGON RARE-EARTH Co., Ltd.
- Inventors: Qin Lan; Yan Zhou; Hiroshi Nagata; Yao Shi
- Web page: https://patentgrep.com/patent/US11993836B2

## CPC

- C22C 38/16: containing copper
- B22F 3/24: After-treatment of workpieces or articles {(B22F3/1146 takes precedence)}
- C22C 33/02: by powder metallurgy
- 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 38/10: containing cobalt
- C22C 38/14: containing titanium or zirconium
- H01F 1/0577: {sintered}
- H01F 41/0266: {Moulding; Pressing (H01F41/0273 takes precedence; hard magnetic particles H01F1/06, H01F1/11)}
- H01F 41/0273: {Imparting anisotropy (methods and devices for magnetising permanent magnets H01F13/003)}
- B22F 2003/248: {Thermal after-treatment}
- B22F 2201/20: Use of vacuum
- B22F 2202/05: Use of magnetic field
- B22F 2301/355: Rare Earth - Fe intermetallic alloys
- C22C 2202/02: Magnetic
- H01F 1/0576: {pressed, e.g. hot working}
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- 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
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

Disclosed are an R—Fe—B-based sintered magnet with a low B content and a preparation method therefor. The sintered magnet comprises the following components: 28.5 wt %-31.5 wt % of R, 0.86 wt %-0.94 wt % of B, 0.2 wt %-1 wt % of Co, 0.2 wt %-0.45 wt % of Cu, 0.3 wt %-0.5 wt % of Ga, 0.02 wt %-0.2 wt % of Ti, and 61 wt %-69.5 wt % of Fe. The sintered magnet has an R6-T13−δM1+δ series phase accounting for 75% or more of the total volume of grain boundaries. The present invention selects optimal content ranges of R, B, Co, Cu, Ga, and Ti, and forms an R6-T13−δM1+δ series phase of a special composition and increases its volume fraction in grain boundary phases, so as to acquire higher Hcj and SQ values.

## Claims

### Claim 1

An R—Fe—B-based sintered magnet with a low B content, containing an R2Fe14B-type main phase, the R being at least one rare earth element comprising Nd, wherein:
the R—Fe—B-based sintered magnet comprises the following components:
28.5 wt %-31.5 wt % of R,
0.86 wt %-0.94 wt % of B,
0.2 wt %-1 wt % of Co,
0.2 wt %-0.45 wt % of Cu,
0.3 wt %-0.5 wt % of Ga,
0.02 wt %-0.2 wt % of Ti, and
61 wt %-69.5 wt % of Fe,
the content of each of Dy, Tb, Gd, or Ho in R is 1 wt % or below, and
the R—Fe—B-based sintered magnet has an R6-T13−δM1+δ series phase accounting for 75% or more of a total volume of grain boundaries, wherein T is at least one selected from Fe or Co, M comprises 80 wt % or more of Ga and 20 wt % or below of Cu, and δ is within a range of from −0.14 to 0.04.

### Claim 2 (depends on 1)

The R—Fe—B-based sintered magnet with the low B content according to claim 1, wherein:
the components comprise 5.0 wt % or below of X and inevitable impurities,
X is selected from at least one of a group of elements consisting of Zn, Al, In, Si, Ti, V, Cr, Mn, Ni, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, and W, and
when X comprises at least one of Nb, Zr, or Cr, a total content of Nb, Zr, and Cr is 0.20 wt % or below.

### Claim 3 (depends on 2)

The R—Fe—B-based sintered magnet with the low B content according to claim 2, wherein a balance is Fe.

### Claim 4 (depends on 2)

The R—Fe—B-based sintered magnet with the low B content according to claim 2, wherein:
the inevitable impurities comprise O, and
an O content of the R—Fe—B-based sintered magnet is 0.5 wt % or below.

### Claim 5 (depends on 1)

The R—Fe—B-based sintered magnet with the low B content according to claim 1, wherein the R—Fe—B-based sintered magnet is an R—Fe—B-based sintered magnet having been subjected to heat treatment.

### Claim 6 (depends on 1)

The R—Fe—B-based sintered magnet with the low B content according to claim 1, wherein:
the R—Fe—B-based sintered magnet is prepared according to a method comprising:
preparing a molten raw material component liquid of the R—Fe—B-based sintered magnet at a cooling rate of 102° C./sec-104° C./sec into a quenched alloy;
crushing the quenched alloy by alloy hydrogen absorption;
micro-pulverizing the crushed quenched alloy into a fine powder;
acquiring a formed body using a magnetic field forming method or by hot-pressing thermal deformation;
sintering the formed body in a vacuum or inert gas at a temperature of 900° C.-1100° C.; and
performing a heat treatment on the sintered formed body to acquire a product.

### Claim 7

A method for preparing an R—Fe—B-based sintered magnet with a low B content, containing an R2Fe14B-type main phase, the R being at least one rare earth element comprising Nd, wherein:
the R—Fe—B-based sintered magnet comprises the following components:
28.5 wt %-31.5 wt % of R,
0.86 wt %-0.94 wt % of B,
0.2 wt %-1 wt % of Co,
0.2 wt %-0.45 wt % of Cu,
0.3 wt %-0.5 wt % of Ga,
0.02 wt %-0.2 wt % of Ti, and
61 wt %-69.5 wt % of Fe,
the content of each of Dy, Tb, Gd, or Ho in R is 1 wt % or below, and
the method comprises:
preparing a molten raw material component liquid of the R—Fe—B-based sintered magnet at a cooling rate of 102° C./sec-104° C./sec into an alloy for the R—Fe—B-based sintered magnet;
crushing the alloy by alloy hydrogen absorption;
micro-pulverizing the crushed alloy into a fine powder;
acquiring a formed body using a magnetic field forming method;
sintering the formed body in a vacuum or inert gas at a temperature of 900° C.-1100° C.; and
performing a heat treatment on the sintered formed body to acquire a product.

### Claim 8 (depends on 2)

The R—Fe—B-based sintered magnet with the low B content according to claim 2, wherein:
the R—Fe—B-based sintered magnet is prepared according to a method comprising:
preparing a molten raw material component liquid of the R—Fe—B-based sintered magnet at a cooling rate of 102° C./sec-104° C./sec into a quenched alloy;
crushing the quenched alloy by alloy hydrogen absorption;
micro-pulverizing the crushed quenched alloy into a fine powder;
acquiring a formed body using a magnetic field forming method or by hot-pressing thermal deformation;
sintering the formed body in a vacuum or inert gas at a temperature of 900° C.-1100° C.; and
performing a heat treatment on the sintered formed body to acquire a product.