WO2023280259A1 - 一种耐腐蚀、高性能钕铁硼烧结磁体及其制备方法和用途 - Google Patents

一种耐腐蚀、高性能钕铁硼烧结磁体及其制备方法和用途 Download PDF

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WO2023280259A1
WO2023280259A1 PCT/CN2022/104307 CN2022104307W WO2023280259A1 WO 2023280259 A1 WO2023280259 A1 WO 2023280259A1 CN 2022104307 W CN2022104307 W CN 2022104307W WO 2023280259 A1 WO2023280259 A1 WO 2023280259A1
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ndfeb
sintered
magnet
cooling
sintering
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PCT/CN2022/104307
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English (en)
French (fr)
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李志强
姜云瑛
刘磊
安仲鑫
董昱昊
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烟台正海磁性材料股份有限公司
江华正海五矿新材料有限公司
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Priority to EP22837004.5A priority Critical patent/EP4354472A4/en
Priority to KR1020247000712A priority patent/KR20240017949A/ko
Priority to US18/577,502 priority patent/US20240331898A1/en
Priority to JP2024500588A priority patent/JP2024529310A/ja
Publication of WO2023280259A1 publication Critical patent/WO2023280259A1/zh

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    • H—ELECTRICITY
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    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/02—Permanent magnets [PM]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/16—Both compacting and sintering in successive or repeated steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
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    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
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    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0576—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together pressed, e.g. hot working
    • H—ELECTRICITY
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    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
    • H—ELECTRICITY
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    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
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    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0266—Moulding; Pressing
    • H—ELECTRICITY
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    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0273—Imparting anisotropy
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    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
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    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0293—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
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    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • B22F2003/248—Thermal after-treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
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    • C22C2202/00—Physical properties
    • C22C2202/02—Magnetic

Definitions

  • the invention relates to a corrosion-resistant and high-performance NdFeB sintered magnet, a preparation method and application thereof, and belongs to the field of rare earth permanent magnet materials.
  • NdFeB sintered permanent magnets have been widely used in wind power, automobiles, home appliances, motors, consumer electronics equipment and medical equipment and other fields.
  • NdFeB sintered magnets are mainly composed of R 2 Fe 14 B main phase, R-rich phase and B-rich phase.
  • the main phase of R 2 Fe 14 B is a ferromagnetic material with high saturation magnetization and anisotropic magnetic field, and it is the basis of the magnetic properties of NdFeB sintered magnets.
  • the existing NdFeB sintered magnets tend to form a B-rich phase (Nd 1.1 Fe 4 B 4 compound) at the grain boundaries, resulting in a decrease in the remanence Br and coercive force Hcj of the NdFeB sintered magnets.
  • patent document CN105074837B discloses a sintered neodymium iron boron magnet, which contains 0.86 mass % to 0.90 mass % of B, but the Ga content is 0.4 mass % to 0.6 mass %.
  • Patent document CN105960690B discloses a sintered NdFeB magnet, which requires a Ga content of 0.3-0.8%, a B content of 0.93-1.0%, and a Ti content of 0.15-0.28%; the process of preparing alloy powder includes preparing Ti hydride powder The process of mixing alloy powder and Ti hydride powder to produce powder.
  • Patent document CN106716571B discloses a manufacturing method of NdFeB sintered magnets, requiring Cu and Ga contents to be ⁇ 0.2%, containing Nb and/or Zr and content ⁇ 0.1%, and B content to be 0.85-0.93%; the heat treatment process includes The magnet raw material is heated to a temperature above 730°C and below 1020°C, cooled to 300°C, and then heated to a temperature above 440°C and below 550°C for low-temperature treatment.
  • the present invention provides a sintered NdFeB magnet, which is prepared from a sintered NdFeB magnet composition through powder milling, molding and sintering under an inert atmosphere.
  • the sintered NdFeB magnet comprises:
  • Ga with a content of not less than 0.1 wt% and not more than 0.3 wt%;
  • O content is more than 400ppm and less than 1000ppm
  • the balance is Fe and unavoidable impurities.
  • the R is selected from neodymium (Nd), or neodymium (Nd) and at least one of the following rare earth elements: lanthanum (La), cerium (Ce), praseodymium (Pr), promethium (Pm), samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu), Scandium (Sc) and yttrium (Y) and other rare earth elements.
  • Nd neodymium
  • Nd neodymium
  • rare earth elements lanthanum (La), cerium (Ce), praseodymium (Pr), promethium (Pm), samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb),
  • B, Ga, and O in the sintered NdFeB magnet have the following relationship: 0.25 ⁇ (0.98-[B])+0.1 ⁇ (0.5-[Ga]) ⁇ [O],
  • [B], [Ga], [O] represent the mass percentages of B, Ga, and O in the NdFeB sintered magnet, respectively.
  • the content of the unavoidable impurities is not less than 0 wt % and not more than 2.0 wt %, preferably not less than 0.1 wt % and not more than 0.8 wt %.
  • the sintered NdFeB magnet composition contains less than 200 ppm of O.
  • the NdFeB sintered magnet composition also contains required stoichiometric elements such as R, B, Ga, Co, Fe and the like.
  • the sintered NdFeB magnet includes an R 2 Fe 14 B main phase, an R-rich phase and a B-rich phase.
  • the sintered NdFeB magnet comprises a face centered cubic (fcc) structure as shown in FIG. 1 .
  • fcc face centered cubic
  • the ⁇ -Fe phase is easy to precipitate during the cooling process of the alloy liquid during smelting, and the existence of the ⁇ -Fe phase will lead to a significant decrease in the remanence and coercive force of the NdFeB sintered magnet; with the increase of the R content
  • the Br of the magnet will gradually decrease, and the Hcj will gradually increase.
  • the R content is greater than or equal to 33wt%, the thickness of the grain boundary phase increases, the number of defects and impurities increases, and the performance of the magnet decreases significantly.
  • the main function of B is to form the Nd 2 T 14 B main phase.
  • the change of B content has no significant effect on the remanence and coercive force of NdFeB sintered magnets, but when the B content is high (for example ⁇ 0.94wt%) , the B-rich phase is easy to form at the grain boundary of the magnet.
  • the B-rich phase is non-ferromagnetic, and its existence will greatly reduce the magnetic properties of the magnet.
  • an appropriate amount of oxygen content is beneficial to the structure and performance of the NdFeB sintered magnet; if the oxygen content is too high (for example ⁇ 1000ppm), the net rare earth metal content of the magnet may be reduced to a certain level Critical value, the Nd-rich phase disappears, the magnet cannot be densified during sintering, and even destroys its Nd 2 T 14 B main phase to appear ⁇ -Fe phase. Therefore, too high oxygen content will reduce the Hcj of the magnet.
  • the inventors further found that adding Co can effectively increase the Curie temperature of NdFeB sintered magnets, improve the temperature coefficient of the magnets, and have a great positive effect on the application of NdFeB sintered magnets under high temperature conditions; but Co element is a strategic Resources will tend to become expensive in the future, and excessive addition of Co elements (eg ⁇ 3.0wt%) will also reduce the toughness of NdFeB sintered magnets and increase their brittleness, which is not conducive to the processing of magnet products.
  • the present invention also provides a preparation method of the above-mentioned NdFeB sintered magnet.
  • the preparation method comprises: preparing the above-mentioned NdFeB sintered magnet composition through powder making, molding and sintering.
  • the preparation method specifically includes the following steps:
  • the above-mentioned sintered NdFeB magnet composition has the above-mentioned definition.
  • the NdFeB sintered magnet composition can be a NdFeB quick-setting sheet commonly used by those skilled in the art.
  • the quick-setting sheet is prepared by the following quick-setting process: in a vacuum or an inert gas atmosphere, The above-mentioned NdFeB sintered magnet composition is melted to obtain a uniform and stable alloy liquid, and the alloy liquid is poured onto a quenching roll to form the above-mentioned quick-setting sheet.
  • the pouring temperature is 1300°C to 1600°C, more preferably 1400°C to 1500°C.
  • the speed of the chill roll is preferably 20-60 r/min, more preferably 30-50 r/min.
  • a cooling fluid such as cooling water, passes through the quenching roller.
  • the average particle size SMD of the fine powder produced in the pulverizing process is 1-10 ⁇ m, preferably 1-9 ⁇ m, 2-5 ⁇ m, 6-8 ⁇ m, and 2.8 ⁇ m for example. ⁇ m.
  • the average particle size of the micropowder is measured by a dry dispersion laser diffraction method.
  • step (2) the pulverizing process further includes adding oxygen.
  • the oxygen addition operation steps are as follows: in the pulverization process, a mixed gas containing oxygen is introduced.
  • the volume fraction of oxygen in the mixed gas is 0.1-30%, preferably 4-16%.
  • the mixed gas is nitrogen or inert gas and compressed air, wherein the volume fraction of compressed air in the mixed gas is preferably 20-80%.
  • the inert gas is selected from any one of helium, neon and argon.
  • the pulverizing process includes hydrogen explosion and grinding.
  • the above-mentioned NdFeB sintered magnet composition (preferably a quick-setting sheet) is exploded to obtain a coarse powder, and the average particle size of the coarse powder is 50-150 ⁇ m, preferably 100 ⁇ m.
  • the vacuum degree of the hydrogen explosion is 10 -2 Pa.
  • high-purity hydrogen (99.999%) is used, and the hydrogen pressure reaches about 105 Pa.
  • dehydrogenation treatment is required before grinding after hydrogen explosion.
  • the oxygenation operation can be carried out at any stage after hydrogen explosion, grinding or grinding.
  • the oxygen addition operation occurs in the hydrogen explosion stage.
  • the oxygen-containing mixed gas is introduced to add oxygen, and the coarse powder is recovered.
  • the oxygen addition operation occurs in the grinding stage, and the above-mentioned oxygen-containing mixed gas is fed in for grinding.
  • the grinding also includes medium grinding and airflow micro-grinding.
  • a ball mill is used for medium grinding, for example, a 30-mesh sieve for medium grinding.
  • the flow rate of the airflow is 1 MHz or more and 2 MHz or less.
  • the oxygen addition operation occurs in the post-grinding stage, and the above-mentioned oxygen-containing mixed gas is filled in the fine powder storage tank.
  • step (3) in an inert gas atmosphere, the fine powder is subjected to orientation press molding in a 2T orientation field, preferably a magnetic field of 15KOe.
  • a lubricant is added to the micropowder before pressing, and the amount of lubricant added accounts for 0-1wt% of the total weight of the micropowder, preferably 0.2wt%.
  • the present invention does not specifically limit the lubricant, and lubricants commonly used in this technical field can be selected.
  • the sintering process includes the following steps: high-temperature sintering, cooling, a first aging process, cooling, a second aging process, and cooling.
  • the high temperature sintering includes a high temperature sintering temperature of 1000° C. to 1100° C. and a high temperature sintering time of 4 to 10 hours.
  • the high temperature sintering temperature is 1020-1080°C, exemplarily 1050°C.
  • the high-temperature sintering temperature is 4-10 hours, exemplarily 4, 5, 6, 7, 8, 9, 10 hours.
  • the first aging process includes: a treatment temperature of 600-750°C, preferably 630-700°C, 650-670°C; a treatment time of 4h-10h, for example 4, 5, 6, 7, 8, 9, 10 hours.
  • the second aging process includes: a treatment temperature of 500°C-650°C, preferably 530-600°C, 560-580°C; a treatment time of 4h-10h, exemplarily 4, 5, 6, 7, 8 , 9, 10h.
  • the cooling in the sintering process refers to cooling to below 80°C.
  • the cooling is selected from any one of vacuum cooling, argon-filled slow cooling, fan cooling and the like.
  • the above-mentioned cooling can be performed at any cooling rate, and slow cooling (for example, ⁇ 10°C/min) or rapid cooling (for example, ⁇ 40°C/min) can be selected.
  • the sintering process is performed under an inert atmosphere.
  • the present invention also provides a sintered NdFeB magnet prepared by the above method, and the sintered NdFeB magnet has the meaning and content as described above.
  • the sintered NdFeB magnet includes a face centered cubic (fcc) structure as shown in FIG. 1 .
  • the present invention also provides the application of the above-mentioned NdFeB sintered magnets in the fields of wind power, automobiles, household appliances, motors, consumer electronic equipment, medical equipment and the like.
  • the NdFeB sintered magnet of the present invention does not contain a boron-rich phase, the grain boundaries are relatively thick and the abnormal growth of grains can be suppressed. Therefore, on the premise of saving the amount of heavy rare earth metals or alloys, by adding oxygen, it can The NdFeB sintered magnet that suppresses the reduction of the coercive force and increases the coercive force is obtained, and at the same time, the corrosion resistance of the magnet can be improved.
  • the second-stage aging process is adopted in the sintering process of the present invention, which can further orderly distribute the oxidized Nd in the grain boundary without reducing the coercive force of the magnet, and at the same time improve the corrosion resistance of the magnet.
  • Fig. 1 is a schematic diagram of the face-centered cubic (fcc) structure in the sintered NdFeB magnet of the present invention.
  • the particle size of the ground fine powder is not less than 1 ⁇ m and not more than 10 ⁇ m, more preferably not less than 2 ⁇ m and not more than 5 ⁇ m.
  • the particle sizes of the micropowders in the examples of the present invention are all measured by dry dispersion laser diffraction method.
  • NdFeB sintered magnets The magnetic properties, oxygen content and weight loss performance test methods of NdFeB sintered magnets are as follows:
  • Magnetic properties making For the sample column, the magnetic properties of each sample column were measured by NIM62000B-H tracer, including remanence Br, intrinsic coercive force Hcj and Hk/Hcj. Among them, H k /H cj expresses the squareness of the intrinsic demagnetization curve of the magnet. Usually, the magnetic field corresponding to 0.9 or 0.8 Br on the demagnetization curve is called the bending point magnetic field Hk, also known as the knee point coercive force. Larger means that the squareness of the intrinsic demagnetization curve of the magnet is better.
  • Oxygen content sample preparation: smash the sample into particles of about 1-2 mm by mechanical knocking, and measure the oxygen content of each column with an oxygen nitrogen meter; if the sample is the above-mentioned sintered magnet sample column, remove the surface layer of the sample , take a sample of the internal magnet.
  • PCT weight loss performance Through the high-pressure accelerated life test equipment (PCT test chamber), the experimental conditions: 121 ° C, 100% RH, 2.0 Bar, 96h, the average loss value of each column is measured with a weighing balance.
  • ⁇ indicates that oxygen is added at this stage, and ⁇ indicates that oxygen is not added at this stage.
  • NdFeB sintered magnet composition adopt vacuum induction melting furnace, according to above-mentioned [Table 1] raw material is equipped with and obtain NdFeB sintered magnet composition and put it into the crucible, and under vacuum or inert gas (typically in argon) (air) atmosphere to be heated to 1480°C to melt into molten steel, pour the molten steel onto the quenching roll, rapidly cool down, nucleate and crystallize on the roll surface, and gradually grow up to form a sintered NdFeB magnet composition. Alloy quick-setting tablets.
  • the speed of the quenching roll is more than 20r/min and less than 60r/min, and the more optimal speed range is more than 30r/min and less than 50r/min, and cooling water is passed through the quenching roll.
  • hoist HD powder into the recovery box first, replace the recovery box with 5000 ⁇ 200L/h nitrogen (or argon, helium and other inert gases) for 30 minutes, cool for 6 hours, and then pull it into the cooling device. Vacuumize to -0.01MPa, fill with a mixture of nitrogen and compressed air at 100 ⁇ 5kPa, the volume ratio of the two is 3:2, cool for 1 hour, then fill with nitrogen to 1 atmospheric pressure, and then turn on the fan to cool down to a temperature lower than After 50°C, it is recovered in the recovery box to complete the oxygenation operation. Then, it is ground in turn by medium mill and jet mill, and finally made into a fine powder with an average particle size SMD of 2.8 ⁇ m.
  • nitrogen or argon, helium and other inert gases
  • Compression molding add 0.2wt% lubricant to the final micropowder made in step (2), after 2 hours of mixing by a mixer, pour it into the film cavity of the press, and apply it under an external magnetic field of 2.5T (For example, a magnetic field of 15 Koe), in an inert gas atmosphere, orientation press molding.
  • 2.5T Magnetic field of 15 Koe
  • Embodiment 2-6 and comparative example F are identical to Embodiment 2-6 and comparative example F.
  • ⁇ indicates that oxygen is added at this stage, and ⁇ indicates that oxygen is not added at this stage.
  • NdFeB sintered magnet composition alloy according to [Table 4] raw material composition ratio, refer to the preparation process of Example 1 to prepare NdFeB sintered magnets of Examples 2-6 and Comparative Example F.
  • the difference is that the sintering temperature is set to 1045°C, the first aging temperature is 720°C, and the second aging temperature is 640°C, and the oxygenation operation in Examples 2-6 occurs at different stages of the milling process, as follows:
  • Example 2 When recovering the HD coarse powder, first hoist the HD coarse powder into the recovery box, use 5000 ⁇ 200L/h flow of nitrogen (or inert gas such as argon, helium) to replace the recovery box for 30 minutes, and cool for 6 hours Pull it into the cooling device, evacuate it to -0.01MPa, fill it with a mixture of nitrogen and compressed air 100 ⁇ 5kPa, the ratio of the two is 1:1, cool it for 1 hour, then fill it with nitrogen to 1 atmosphere, and then turn on the fan After cooling to a temperature lower than 50°C, it is recovered in the recovery box to complete the oxygenation operation.
  • nitrogen or inert gas such as argon, helium
  • Embodiment 3 In the intermediate grinding stage, a 30-mesh screen is used to grind in a nitrogen-oxygen mixture atmosphere containing 10 ⁇ 1% oxygen in the intermediate grinding chamber to complete the oxygenation operation.
  • Embodiment 4 In the jet mill stage, grinding is carried out in the nitrogen-oxygen mixture atmosphere containing 12 ⁇ 1% oxygen in the jet mill chamber to complete the oxygen addition operation.
  • Embodiment 5 In the jet mill stage, adjust the jet mill pipeline, change one of the grinding nitrogen tubes into a nitrogen-oxygen mixed gas tube with 1 ⁇ 0.1% oxygen, and perform grinding to complete the oxygen addition operation.
  • Embodiment 6 In the powder mixing stage after the jet mill, gas replacement is carried out in the jet mill powder storage tank, and a nitrogen-oxygen mixture gas with a volume ratio of 13 ⁇ 1% oxygen is charged to complete the oxygen addition operation.
  • Comparative Example F No oxygen addition operation occurs in the milling process, and HD coarse powder recovery and grinding (including medium grinding, jet milling, mixing, etc.) are all carried out under nitrogen atmosphere.
  • the oxygen content of the sintered magnet of the embodiment of the present invention is controlled above 400ppm and below 1000ppm, the magnetic properties of Br, Hcj, and Hk/Hcj are at the same level, the weight loss of PCT is less than 2.0%, and the corrosion resistance is excellent;
  • the comparative example F of the process no oxygen addition operation was performed in the milling process, the oxygen content was only 328ppm, the PCT weight loss was as high as 6.51%, and the corrosion resistance of the magnet was poor.

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Abstract

本发明提供一种耐腐蚀、高性能钕铁硼烧结磁体及其制备方法和用途。本发明的钕铁硼烧结磁体由钕铁硼烧结磁体组合物经制粉、成型、烧结制得，所述钕铁硼烧结磁体包含：含量为28.5wt％以上且32.5wt％以下的R；含量为0.88wt％以上且0.94wt％以下的B；含量为0.1wt％以上且0.3wt％以下的Ga；含量为1.0wt％以上且3.0wt％以下的Co；含量为400ppm以上且1000ppm以下的O。本发明通过进行加氧操作，能够获得抑制矫顽力降低、并且提高矫顽力的钕铁硼烧结磁体，同时可以改善磁体的耐腐蚀能力。

Description

一种耐腐蚀、高性能钕铁硼烧结磁体及其制备方法和用途
本申请要求享有2021年7月8日向中国国家知识产权局提交的，专利申请号为202110774881.2，发明名称为“一种耐腐蚀、高性能钕铁硼烧结磁体及其制备方法和用途”的在先申请的优先权权益。所述在先申请的全文通过引用的方式结合于本申请中。
技术领域
本发明涉及一种耐腐蚀、高性能钕铁硼烧结磁体及其制备方法和用途，属于稀土永磁材料领域。
背景技术
稀土永磁材料已然成为现代经济和科技不可或缺的支柱性材料。其中，钕铁硼烧结永磁体目前已被广泛地应用于风电、汽车、家电、电机、消费电子设备以及医疗器械等领域。钕铁硼烧结磁体主要由R 2Fe 14B主相、富R相和富B相组成。R 2Fe 14B主相是具有高饱和磁化和各向异性磁场的铁磁性材料，是构成钕铁硼烧结磁体磁特性的根基。现有技术的钕铁硼烧结磁体往往会在晶粒边界形成富B相(Nd 1.1Fe 4B 4化合物)，导致钕铁硼烧结磁体的剩余磁通密度Br与矫顽力Hcj的降低。
近年来，钕铁硼永磁体生产企业也一直致力于研究低B配方以及其配套技术，以期实现稳定批量生产。其中，专利文献CN105074837B公开了一种钕铁硼烧结磁铁，包含0.86质量％以上且0.90质量％以下的B，但Ga含量为0.4质量％以上且0.6质量％以下。专利文献CN105960690B公开了一种钕铁硼烧结磁体，要求Ga含量为0.3-0.8％，B含量为0.93-1.0％，Ti含量为0.15-0.28％； 准备合金粉末的工序包括准备Ti的氢化物粉末的工序，将合金粉末与Ti的氢化物的粉末混合制粉生产。专利文献CN106716571B公开了一种钕铁硼烧结磁体的制造方法，要求Cu、Ga含量均≥0.2％，含有Nb和/或Zr且含量≤0.1％，B含量为0.85-0.93％；热处理工序，包括将磁体原材加热至730℃以上且1020℃以下，冷却至300℃后，再加热至440℃以上且550℃以下的温度进行低温段处理。
尽管上述技术方案致力于通过减少钕铁硼烧结磁体内的B浓度，降低主相晶粒的比率，增厚晶界相等手段来提高钕铁硼烧结磁体的矫顽力，但仍存在低B体系钕铁硼烧结磁体内的晶界会变厚的现象。并且，较厚的晶界相使得磁体中的Nd和Fe更易被氧化，从而导致磁体的耐腐蚀能力变差。因此，亟需进一步提高钕铁硼烧结磁体的磁性能、耐腐蚀性，并且降低成本等。
发明内容
为改善现有技术存在的问题，本发明提供一种钕铁硼烧结磁体，所述钕铁硼烧结磁体由钕铁硼烧结磁体组合物在惰性气氛下经制粉、成型、烧结制得。
根据本发明的实施方案，所述钕铁硼烧结磁体包含：
含量为28.5wt％以上且32.5wt％以下的R；
含量为0.88wt％以上且0.94wt％以下的B；
含量为0.1wt％以上且0.3wt％以下的Ga；
含量为1.0wt％以上且3.0wt％以下的Co；
含量为400ppm以上且1000ppm以下的O；
余量为Fe以及不可避免的杂质。
优选地，所述R选自钕(Nd)，或者钕(Nd)与下述稀土元素中的至少一种：镧(La)、铈(Ce)、镨(Pr)、钷(Pm)、钐(Sm)、铕(Eu)、钆(Gd)、铽(Tb)、 镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)、镥(Lu)、钪(Sc)和钇(Y)等稀土元素。
根据本发明的实施方案，所述钕铁硼烧结磁体中B、Ga、O具有如下关系：0.25×(0.98-[B])+0.1×(0.5-[Ga])＜[O]，
其中，[B]、[Ga]、[O]分别表示在钕铁硼烧结磁体中B、Ga、O的质量百分含量。
根据本发明的实施方案，所述不可避免的杂质的含量为0wt％以上且2.0wt％以下，优选为0.1wt％以上且0.8wt％以下。
根据本发明的实施方案，所述钕铁硼烧结磁体组合物中含有200ppm以下的O。优选地，所述钕铁硼烧结磁体组合物中还含有所需化学计量的R、B、Ga、Co、Fe等元素。
根据本发明的实施方案，所述钕铁硼烧结磁体包括R 2Fe 14B主相、富R相和富B相。
根据本发明的实施方案，所述钕铁硼烧结磁体包含如图1所示的面心立方(fcc)结构。发明人发现，R含量决定了钕铁硼烧结磁体主相晶粒及晶界相的组织结构，对磁体的性能起到非常重要的作用。当R含量≤29wt％时，熔炼时合金液冷却过程中易析出α-Fe相，α-Fe相的存在会导致钕铁硼烧结磁体剩磁和矫顽力的显著降低；随着R含量的增加，磁体的Br会逐渐降低，Hcj会逐渐提高，当R含量≥33wt％时，晶界相厚度增大，缺陷及杂质数量增多，磁体性能大幅降低。
B的主要作用是形成Nd 2T 14B主相，B含量的变化，对钕铁硼烧结磁体的剩磁及矫顽力无显著影响，但当B含量偏高(例如≥0.94wt％)时，磁体晶界处易形成富B相，富B相是非铁磁性的，它的存在会大幅降低磁体的磁性能。
Ga的含量越少，主相颗粒中的Ga的含量越减少，且主相颗粒中的Ga的原子数浓度越少，R 6Fe 13Ga相难以在晶界中产生。其结果是，磁特性，特别是Hcj容易降低。
发明人发现，B的含量在0.94wt％以下的钕铁硼烧结磁体中，控制氧含量在 400ppm以上且1000ppm以下，可改善磁体的耐腐蚀性能。当磁体中Nd含量一定时，适量的氧含量对钕铁硼烧结磁体的组织和性能都是有利的；如果氧含量过高(例如≥1000ppm)，可能使磁体的净稀土金属含量降低到某一个临界值，而使富Nd相消失，导致烧结时磁体不能致密化，甚至破坏其Nd 2T 14B主相而出现α-Fe相，因此，过高的氧含量会使磁体的Hcj降低。
发明人进一步发现，添加Co可有效提高钕铁硼烧结磁体的居里温度，改善磁体的温度系数，对于钕铁硼烧结磁体在高温条件下的应用有极大的积极作用；但是Co元素属于战略资源，未来存在变得昂贵的趋势，并且过多的添加Co元素(例如≥3.0wt％)也会降低钕铁硼烧结磁体的韧性，使其脆性增大，不利于磁体产品的加工。
本发明还提供上述钕铁硼烧结磁体的制备方法，其制备方法包括：将上述钕铁硼烧结磁体组合物经制粉、成型、烧结制得。
根据本发明的钕铁硼烧结磁体的制备方法的实施方案，所述制备方法具体包括如下步骤：
(1)准备上述钕铁硼烧结磁体组合物；
(2)将上述钕铁硼烧结磁体组合物经过制粉工序，制成微粉末；
(3)在外磁场作用下，在惰性气体氛围中，将上述微粉末压型制得成型体；
(4)将上述成型体进行烧结工序，得到所述钕铁硼烧结磁体。
根据本发明的实施方案，上述钕铁硼烧结磁体组合物具有如上文所述定义。优选的，所述钕铁硼烧结磁体组合物可以为本领域技术人员常用的钕铁硼速凝片，例如，所述速凝片采用如下速凝工艺制备得到：在真空或惰性气体气氛中，将上述钕铁硼烧结磁体组合物熔化，得到成分均匀、稳定的合金液，并且将合金液浇注到急冷辊上形成上述速凝片。例如，浇注温度为1300℃～1600℃，更优选为1400℃～1500℃。急冷辊转速优选为 20～60r/min，更优选为30～50r/min。优选地，急冷辊内通有冷却流体，例如冷却水。
根据本发明的实施方案，步骤(2)中，所述制粉工序制成的微粉末平均粒径SMD为1～10μm，优选为1～9μm、2～5μm、6～8μm，示例性为2.8μm。优选地，所述微粉末的平均粒度通过利用干式分散的激光衍射法测得。
根据本发明的实施方案，步骤(2)中，所述制粉工序还包括加氧操作。
优选地，所述加氧操作步骤如下：在制粉工序中通入含氧混合气体。优选地，所述混合气体中氧气的体积分数为0.1～30％，优选为4～16％。
优选地，所述混合气体为氮气或惰性气体与压缩空气，其中，压缩空气占混合气体的体积分数优选为20～80％。优选地，所述惰性气体选自氦气、氖气、氩气中的任一种。
优选地，所述制粉工序包括氢爆和研磨。
优选地，氢爆后，上述钕铁硼烧结磁体组合物(优选为速凝片)爆裂得到粗粉末，该粗粉末的平均粒度为50～150μm，优选为100μm。
优选地，氢爆的真空度为10 -2Pa。优选地，氢爆时，采用高纯氢气(99.999％)，且氢气压达到105Pa左右。优选地，氢爆后研磨前，需进行脱氢处理。
优选地，所述加氧操作可在氢爆、研磨或研磨后的任一阶段进行。
示例性地，所述加氧操作发生在氢爆阶段。
例如，在氢爆粗粉末并脱氢后，通入含氧混合气体进行加氧，并回收粗粉末。
优选地，在加氧结束后，进行充气冷却、回收。示例性地，所述加氧操作发生在研磨阶段，通入上述含氧混合气体进行研磨。进一步的，所述研磨还包括中研磨和气流微研磨。例如，中研磨采用球磨机进行研磨，例如30目筛网进行中研磨。例如，气流微研磨时，气流流速为1MHz以上且2MHz以下。
示例性地，所述加氧操作发生在研磨后阶段，在微粉末存储料罐中充入上述含氧混合气体。
根据本发明的实施方案，步骤(3)中，在惰性气体氛围中，将所述微粉末在2T取向场中取向压制成型，优选为15KOe的磁场。
优选地，步骤(3)中，压型前向所述微粉末中添加润滑剂，润滑剂添加量占微粉末总重量的0～1wt％，优选为0.2wt％。优选地，本发明对润滑剂不做具体限定，可选用本技术领域常用的润滑剂。
根据本发明的实施方案，步骤(4)中，所述烧结工序包含如下步骤：高温烧结，冷却，第一时效工序，冷却，第二时效工序，冷却。
优选地，所述高温烧结包括，高温烧结温度1000℃～1100℃，高温烧结时间为4～10h。优选地，所述高温烧结温度为1020～1080℃，示例性为1050℃。优选地，所述高温烧结温度为4～10h，示例性为4、5、6、7、8、9、10h。
优选地，所述第一时效工序包括：处理温度600～750℃，优选为630～700℃、650～670℃；处理时间为4h～10h，示例性为4、5、6、7、8、9、10h。
优选地，所述第二时效工序包括：处理温度500℃～650℃，优选为530～600℃、560～580℃；处理时间为4h～10h，示例性为4、5、6、7、8、9、10h。
优选地，烧结工序中的冷却是指冷却至80℃以下。优选地，所述冷却选自真空冷却、充氩气缓冷、开风机冷却等任一种。上述冷却可以在任意的冷却速度下进行，可以选用缓冷(例如，≤10℃/min)或是急冷(例如，≥40℃/min)均可。
优选地，所述烧结工序在惰性气氛下进行。
本发明还提供由上述方法制备得到的钕铁硼烧结磁体，所述钕铁硼烧结磁体具有如上文所述的含义和含量。所述钕铁硼烧结磁体包含如图1所示的面心立方(fcc)结构。
本发明还提供上述钕铁硼烧结磁体在风电、汽车、家电、电机、消费电子设备以及医疗器械等领域中的应用。
有益效果
发明人发现，本发明的钕铁硼烧结磁体中，晶界内部分Nd与氧结合生成较稳定的氧化钕，氧化钕能够起到阻碍晶粒异常长大的作用；同时，氧进入富Nd相后，使其双六方最密堆积(dhcp)结构转变为面心立方(fcc)结构，如图1所示；fcc结构富液态Nd相与Nd2T14B主相晶粒的湿润角变小，增加它们之间的浸润性，有助于富Nd相更加均匀的沿晶界分布。由于本发明的钕铁硼烧结磁体不含富硼相，晶界相对较厚且能够抑制晶粒的异常长大，因此在节省重稀土金属或合金用量的前提下，通过进行加氧操作，能够获得抑制矫顽力降低、并且提高矫顽力的钕铁硼烧结磁体，同时可以改善磁体的耐腐蚀能力。
并且，本发明的烧结工序中采用了二段时效工艺，能够进一步使氧化态的Nd在晶界中有序地分布，且不降低磁体的矫顽力，同时能够改善磁体的耐腐蚀性能。
附图说明
图1为本发明钕铁硼烧结磁体中的面心立方(fcc)结构示意图。
具体实施方式
下文将结合具体实施例对本发明的技术方案做更进一步的详细说明。应当理解，下列实施例仅为示例性地说明和解释本发明，而不应被解释为对本发明保护范围的限制。凡基于本发明上述内容所实现的技术均涵盖在本发明旨在保护的范围内。
除非另有说明，以下实施例中使用的原料和试剂均为市售商品，或者可以通过已知方法制备。
在本发明的制粉阶段，研磨后的微粉末的粒度为1μm以上且10μm以下， 更优为2μm以上且5μm以下。本发明实施例中微粉末的粒度均采用干式分散的激光衍射法测得。
钕铁硼烧结磁体的磁性能、氧含量、失重性能测试方法如下：
磁性能：制作
Figure PCTCN2022104307-appb-000001
样柱，通过NIM62000B-H描绘器测定各样柱的磁性能，包括剩磁Br、内禀矫顽力Hcj和Hk/Hcj。其中，H k/H cj表述的是磁体内禀退磁曲线的方形度，通常将退磁曲线上0.9或0.8Br相对应的磁场称为弯曲点磁场Hk，也称为膝点矫顽力，Hk越大，意味着磁体的内禀退磁曲线的方形度越好。
氧含量：制样：通过机械敲击，将样品砸成约1-2mm的颗粒，通过氧氮仪测定各样柱的氧含量；若样品为上述烧结磁体样柱时，去掉样品的表层料皮，取内部磁体制样。
PCT失重性能：通过高压加速寿命测试设备(PCT试验箱)，实验条件：121℃、100％RH、2.0Bar、96h，称量天平测定各样柱的平均损失值。
实施例1和对比例A-E
按照表1的组分配比和表2的工艺条件，制备实施例1和对比例A-E的钕铁硼烧结磁体：
[表1]
Figure PCTCN2022104307-appb-000002
注：○表示此阶段加氧，×表示此阶段不加氧。
[表2]
Figure PCTCN2022104307-appb-000003
Figure PCTCN2022104307-appb-000004
具体制备过程如下：
(1)准备钕铁硼烧结磁体组合物：采用真空感应熔炼炉，按照上述[表1]原料配备得到钕铁硼烧结磁体组合物放入坩埚中，并在真空或惰性气体(典型地在氩气)气氛中加热至1480℃熔化为钢液，将熔融的钢液倾倒至急冷辊上，急速降温，在辊面上形核、结晶，并逐渐长大，形成钕铁硼烧结磁体组合物的合金速凝片。急冷辊转速为20r/min以上且60r/min以下，更优转速范围为30r/min以上且50r/min以下，急冷辊内通有冷却水。
取上述速凝片，测得氧含量为109ppm。
(2)制粉：将步骤(1)所得合金鳞片进行氢爆(HD)破碎处理得到粗粉末；
在HD粉回收时，先将HD粉吊入回收箱中，使用5000±200L/h流量的氮气(或氩气、氦气等惰性气体)置换回收箱30min，冷却6h后拉至冷却装置中，抽真空至-0.01MPa，充入氮气与压缩空气的混合气100±5kPa，二者体积比为3:2，冷却1h后，再充入氮气至1个大气压，然后开风机冷却至温度低于50℃后，在回收箱中回收，完成加氧操作。然后依次经过中磨、气流磨等研磨，最终制成平均粒径SMD为2.8μm的微粉末。
(3)压型：向步骤(2)最终制得的微粉末中添加0.2wt％的润滑剂，经混料机混料2h后，倒入压机的膜腔中，在2.5T的外加磁场(例如15Koe的磁场)作用下，在惰性气体氛围中，取向压制成型。
(4)烧结：将步骤(3)压制的成型体在Ar气氛下的真空烧结炉中，分别按照[表2]的烧结温度，进行烧结，然后开风机急冷至80℃以下，制成烧结钕铁硼烧结磁体。然后按照[表2]的第一时效温度和第二时效温度，进行第一时效工序后，冷却至80℃以下，再进行第二时效工序，冷却至80℃以下，完成烧结工 序，得到烧结磁体。
测试实施例1和对比例A-E所得到的钕铁硼烧结磁体的磁性能、氧含量、失重性能，测试结果汇总于表3。
[表3]
Figure PCTCN2022104307-appb-000005
如测试结果所示，本发明实施例1的产品Br＝1.397T、Hcj＝1440kA/m、Hk/Hcj≥0.95且PCT平均损失值仅为0.28mg/cm 2，取得了优异的磁性能和耐腐蚀性能。
实施例2-6和对比例F
[表4]
Figure PCTCN2022104307-appb-000006
注：○表示此阶段加氧，×表示此阶段不加氧。
依照[表4]原料组分配比制备钕铁硼烧结磁体组合物合金，参照实施例 1的制备过程制备实施例2-6和对比例F的钕铁硼烧结磁体。不同之处在于：设置烧结温度为1045℃，第一时效温度为720℃，第二时效温度为640℃，且实施例2-6的加氧操作发生在制粉工序的不同阶段，具体如下：
实施例2：在HD粗粉末回收时，先将HD粗粉末吊入回收箱中，使用5000±200L/h流量的氮气(或氩气、氦气等惰性气体)置换回收箱30min，冷却6h后拉至冷却装置中，抽真空至-0.01MPa，充入氮气与压缩空气的混合气100±5kPa，二者比例为1:1，冷却1h后，再充入氮气至1个大气压，然后开风机冷却至温度低于50℃后，在回收箱中回收，完成加氧操作。
实施例3：在中磨阶段，采用30目筛网，在中磨腔体含体积比10±1％氧气的氮氧混合气氛围中进行研磨，完成加氧操作。
实施例4：在气流磨阶段，在气流磨腔体含体积比12±1％氧气的氮氧混合气氛围中进行研磨，完成加氧操作。
实施例5：在气流磨阶段，调整气流磨管路，将其中一根研磨氮气管改成1±0.1％氧气的氮氧混合气体管，进行研磨，完成加氧操作。
实施例6：在气流磨后的混粉阶段，对气流磨粉末存储料罐中进行气体置换，充入体积比为13±1％氧气的氮氧混合气气体，完成加氧操作。
对比例F：在制粉工序不发生加氧操作，HD粗粉末回收、研磨(包括中磨、气流磨、混料等)均在氮气氛围下进行。
实施例2-6和对比例F中，最终均制成平均粒径SMD为2.8μm的微粉末。
测试实施例2～6、对比例F所得到的钕铁硼烧结磁体的磁性能、氧含量、失重性能，测试结果汇总于表5中。
[表5]
Figure PCTCN2022104307-appb-000007
结果表明，本发明实施例的烧结磁体的氧含量控制在400ppm以上且1000ppm以下，Br、Hcj、Hk/Hcj磁性能水平相当，PCT失重损失＜2.0％，耐腐蚀性能优；而采用传统制粉工序的对比例F，制粉工序中未进行加氧操作，氧含量仅有328ppm，PCT失重损失高达6.51％，磁体耐腐蚀性能差。
以上仅是本发明实施方案的示例性说明，并非旨在对本发明的保护范围作任何形式上的限制。任何熟悉本领域的技术人员，在不脱离本发明精神和教导情况下，都可以对本发明的技术方案作出修改、等同变化及修饰，这样的修改、等同变化及修饰均仍属于本发明保护的范围。

Claims (10)

  1. 一种钕铁硼烧结磁体，其特征在于，所述钕铁硼烧结磁体由钕铁硼烧结磁体组合物在惰性气氛保护下经制粉、成型、烧结制得；
    所述钕铁硼烧结磁体包含：
    含量为28.5wt％以上且32.5wt％以下的R；
    含量为0.88wt％以上且0.94wt％以下的B；
    含量为0.1wt％以上且0.3wt％以下的Ga；
    含量为1.0wt％以上且3.0wt％以下的Co；
    含量为400ppm以上且1000ppm以下的O；
    余量为Fe以及不可避免的杂质。
  2. 根据权利要求1所述的钕铁硼烧结磁体，其特征在于，所述R选自钕(Nd)，或者钕(Nd)与下述稀土元素中的至少一种：镧(La)、铈(Ce)、镨(Pr)、钷(Pm)、钐(Sm)、铕(Eu)、钆(Gd)、铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)、镥(Lu)、钪(Sc)和钇(Y)等稀土元素。
  3. 根据权利要求1或2所述的钕铁硼烧结磁体，其特征在于，所述钕铁硼烧结磁体中B、Ga、O具有如下关系：0.25×(0.98-[B])+0.1×(0.5-[Ga])＜[O]，
    其中，[B]、[Ga]、[O]分别表示在钕铁硼烧结磁体中B、Ga、O的质量百分含量；
    优选地，所述杂质的含量为0wt％以上且2.0wt％以下，优选为0.1wt％以上且0.8wt％以下。
  4. 根据权利要求1-3任一项所述的钕铁硼烧结磁体，其特征在于，所述钕铁硼烧结磁体组合物中含有200ppm以下的O；优选地，所述钕铁硼烧结磁体组合物中还含有所需化学计量的R、B、Ga、Co、Fe等元素。
  5. 根据权利要求1-4任一项所述的钕铁硼烧结磁体，其特征在于，所述钕铁硼烧结磁体包括R 2Fe 14B主相、富R相和富B相；
    优选地，所述钕铁硼烧结磁体包含如图1所示的面心立方(fcc)结构。
  6. 权利要求1-5任一项所述的钕铁硼烧结磁体的制备方法，其特征在于，所述制备方法包括：将所述钕铁硼烧结磁体组合物经制粉、成型、烧结制得；
    优选地，所述钕铁硼烧结磁体的制备方法具体包括如下步骤：
    (1)准备所述钕铁硼烧结磁体组合物；
    (2)将所述钕铁硼烧结磁体组合物经过制粉工序，制成微粉末；
    (3)在外磁场作用下，在惰性气体氛围中，将所述微粉末压型制得成型体；
    (4)将所述成型体进行烧结工序，得到所述钕铁硼烧结磁体。
  7. 根据权利要求6所述的钕铁硼烧结磁体的制备方法，其特征在于，步骤(2)中，所述制粉工序制成的微粉末平均粒径SMD为1～10μm；
    优选地，步骤(2)中，所述制粉工序还包括加氧操作；
    优选地，所述加氧操作步骤如下：在制粉工序中通入含氧混合气体。优选地，所述混合气体中氧气的体积分数为0.1～30％，优选为4～16％；优选地，所述混合气体为氮气或惰性气体与压缩空气，其中压缩空气占混合气体的体积分数优选为20～80％；优选地，所述惰性气体选自氦气、氖气、氩气中的任一种；
    优选地，所述制粉工序包括氢爆和研磨；
    优选地，所述加氧操作可在氢爆、研磨或研磨后的任一阶段进行。
  8. 根据权利要求6或7所述的钕铁硼烧结磁体的制备方法，其特征在于，步骤(3)中，将所述微粉末在2T取向场中取向压制成型，优选为15KOe的磁场；
    优选地，步骤(3)中，压型前向所述微粉末中添加润滑剂，润滑剂添加量占微粉末总重量的0～1wt％；
  9. 根据权利要求6-8任一项所述的钕铁硼烧结磁体的制备方法，其特 征在于，步骤(4)中，所述烧结工序包含如下步骤：高温烧结，冷却，第一时效工序，冷却，第二时效工序，冷却；
    优选地，所述高温烧结包括：高温烧结温度1000℃～1100℃，高温烧结时间为4～10h；
    优选地，所述第一时效工序包括：处理温度600～750℃；处理时间为4h～10h；
    优选地，所述第二时效工序包括：处理温度500℃～650℃；处理时间为4h～10h；
    优选地，烧结工序中的冷却是指冷却至80℃以下。优选地，所述冷却选自真空冷却、充氩气缓冷、开风机冷却等任一种；
    优选地，所述烧结工序在惰性气氛下进行。
  10. 权利要求1-5任一项所述的钕铁硼烧结磁体在风电、汽车、家电、电机、消费电子设备以及医疗器械等领域中的应用。
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