CN115274286B - Rare earth permanent magnet and preparation method thereof - Google Patents
Rare earth permanent magnet and preparation method thereof Download PDFInfo
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- CN115274286B CN115274286B CN202211181833.3A CN202211181833A CN115274286B CN 115274286 B CN115274286 B CN 115274286B CN 202211181833 A CN202211181833 A CN 202211181833A CN 115274286 B CN115274286 B CN 115274286B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- 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
- H01F41/0266—Moulding; Pressing
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- 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
- H01F1/0577—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
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Abstract
The invention provides a rare earth permanent magnet and a preparation method thereof. The preparation method comprises the following steps of: smelting in a vacuum induction furnace, absorbing hydrogen, crushing, micro-crushing, orientation forming, sintering and multistage aging. The invention increases R in a crystal boundary phase by adopting a multi-stage aging treatment mode 6 ‑T 13 The proportion of the M phase, suppressing fluctuation of Hcj of the rare earth permanent magnet due to reduction of the boron content, thereby obtaining a rare earth permanent magnet material having a stable high Hcj.
Description
Technical Field
The invention relates to the technical field of permanent magnets, in particular to a rare earth permanent magnet and a preparation method thereof.
Background
Sintered Nd-Fe-B is used as the third generation rare earth permanent magnetic material, and is widely applied to various social industries due to the excellent 'three high'. WhileMany industries are applied at high temperature, so that the temperature resistance of the rare earth permanent magnet has higher requirements, namely the Hcj of the sintered neodymium iron boron is required to be as high as possible. The general means for improving the Hcj of the sintered Nd-Fe-B is to add heavy rare earth elements Dy and Tb to replace Nd 2 Fe 14 Nd in B increases Hcj. Since Dy and Tb have lower magnetic polarization strength than Nd, br of the magnet is reduced after Dy and Tb are added, and at the same time Dy and Tb are non-renewable expensive rare earth metals, and addition of Dy and Tb also increases the production cost, it is required to increase Br and Hcj of the sintered magnet without adding or adding a small amount of heavy rare earth.
In the prior art, the Hcj of sintered neodymium iron boron is improved by using a mode of 'high Ga and low B' under the condition of not adding or adding a small amount of heavy rare earth. However, in the actual preparation process, this method is due to the R generated during tempering 6 -T 13 The total amount of the M phase and the distribution thereof are unstable, so that the distribution of Hcj of the same batch of products in mass production is wide, and the requirement of mass production cannot be met.
Disclosure of Invention
The invention increases R in a crystal boundary phase by adopting a multi-stage aging treatment mode 6 -T 13 The proportion of the M phase, suppressing fluctuation of Hcj of the rare earth permanent magnet due to reduction of the boron content, thereby obtaining a rare earth permanent magnet material having a stable high Hcj.
In order to solve the above problems, the present invention provides a method for preparing a rare earth permanent magnet, the method comprising:
s100: preparing raw materials, and smelting the raw materials to obtain a first intermediate;
s200: crushing the first intermediate to obtain a second intermediate;
s300: carrying out orientation molding treatment on the second intermediate to obtain a third intermediate;
s400: sintering the third intermediate to obtain a fourth intermediate;
s500: carrying out aging treatment on the fourth intermediate to obtain a rare earth permanent magnet;
wherein, S500 specifically includes:
s510: carrying out primary aging treatment on the fourth intermediate, controlling the aging temperature to be 850-950 ℃ and the aging time to be 2-3 h;
s520: carrying out secondary aging treatment on the fourth intermediate, controlling the aging temperature to be 450-550 ℃ and the aging time to be 3-8 h;
s530: carrying out three times of aging treatment on the fourth intermediate, controlling the aging temperature to be 850-950 ℃ and the aging time to be 2-3 h;
s540: carrying out four times of aging treatment on the fourth intermediate, controlling the aging temperature to be 600-700 ℃ and the aging time to be 3-8 h, and obtaining the rare earth permanent magnet;
in 100 parts by mass of a rare earth permanent magnet, comprising: 29-32 parts of rare earth, 0.88-0.92 part of boron, 0.25-0.45 part of gallium and 66.63-69.87 parts of iron.
Compared with the prior art, the technical scheme has the following technical effects: increasing R in grain boundary phase by multistage ageing treatment 6 -T 13 The proportion of the M phase, suppressing fluctuation of Hcj of the rare earth permanent magnet due to reduction of the boron content, thereby obtaining a rare earth permanent magnet material having a stable high Hcj. In the preparation method, the rare earth permanent magnet material is obtained by sequentially carrying out smelting, crushing treatment, orientation forming treatment, sintering treatment and aging treatment on raw materials, wherein the aging treatment comprises at least four stages of different aging treatments, and the design is that when the Hcj of the rare earth permanent magnet material is improved in a 'high Ga low B' mode, the content of boron in the rare earth permanent magnet material is reduced, so that R generated in the aging process is reduced 6 -T 13 The total amount and the distribution of the M phase are unstable, so that the Hcj distribution in the rare earth permanent magnet materials of the same batch is uneven, and the R can be promoted by tempering eutectic reaction by adopting multi-stage aging treatment 6 -T 13 The M grain boundary phase is generated more widely and stably, so that the distribution consistency of the Hcj of the magnets generated in the same batch is better.
In an example of the present invention, S100 specifically includes:
s110: preparing raw materials, putting the raw materials into a vacuum induction furnace forSmelting, controlling the vacuum degree of the vacuum induction furnace to be 10 -2 Pa-10 -3 Pa, smelting temperature is 1300-1500 ℃;
s120: casting at 1400-1500 deg.c to obtain the first intermediate.
Compared with the prior art, the technical scheme has the following technical effects: melting the raw materials by a vacuum induction furnace, then casting to obtain a first intermediate, wherein the first intermediate is an alloy sheet, and the preparation of the first intermediate is prepared for the subsequent preparation steps.
In an example of the present invention, S200 specifically includes:
s210: hydrogen absorption crushing is carried out on the first intermediate to obtain a coarse crushing material;
s220: and carrying out micro-crushing treatment on the coarse crushed material to obtain a second intermediate.
Compared with the prior art, the technical scheme has the following technical effects: the first intermediate is subjected to coarse crushing treatment through hydrogen absorption crushing, then a second intermediate in a fine powder shape is obtained through micro crushing treatment, and the second intermediate is prepared for subsequent sintering and other steps.
In one embodiment of the invention, the hydrogen absorption pressure is controlled to be 0.3MPa-0.4MPa, and the dehydrogenation temperature is controlled to be 560 ℃ to 600 ℃ in the hydrogen absorption crushing; and/or
The pressure of the airflow grinding chamber is controlled to be 0.5MPa-0.7MPa and the granularity is controlled to be 3.2um-4.2um in the micro-grinding treatment.
Compared with the prior art, the technical scheme has the following technical effects: the first intermediate which is the hydrogen absorption pressure and the dehydrogenation temperature of the hydrogen absorption crushing are controlled to be efficiently crushed, and the particle size of the obtained powder is controlled to be 3.2-4.2 um by controlling the pressure of the micro-crushing treatment jet mill, so that a magnet with uniform components can be obtained during subsequent sintering.
In one embodiment of the invention, the particle size distribution of the second intermediate satisfies: d50 < D90/D10 < D50+2.
Compared with the prior art, the technical scheme has the following technical effects: d50 represents the particle size corresponding to 50% of the cumulative particle size distribution of a sampleMeaning that the particle size is greater than 50% of its particles and less than 50% of its particles, and D50 is the median particle size. D10 represents the particle size corresponding to a cumulative particle size distribution percentage of 10% for a sample, and it means that the particles having a particle size smaller (or larger) than that of the sample account for 10%. D90 represents the particle size corresponding to 90% of the cumulative particle size distribution of a sample, and represents particles having a particle size less than (or greater than) 90% of the cumulative particle size distribution. The particle size distribution of the second intermediate is controlled in the formula, so that the particle size distribution of the second intermediate can be controlled to be consistent as much as possible, and R can be generated more stably in a wider range in the rare earth permanent magnet obtained by subsequent preparation 6 -T 13 -an M phase.
In one embodiment of the invention, the sintering temperature of the sintering treatment in S400 is controlled to be 1000-1100 ℃, and the sintering time is controlled to be 7.5-8.5 h.
Compared with the prior art, the technical scheme has the following technical effects: and sintering the third intermediate at the temperature of 1000-1100 ℃ for 7.5-8.5 h to obtain a sintered magnet, namely a fourth intermediate.
In one embodiment of the present invention, before S200, the rare earth element content of at least 10 first intermediate bodies is detected, and the rare earth element content of at least 10 first intermediate bodies is controlled to satisfy the following formula: (T) max - T min ）/T max *100%＜2%；
Wherein, T max Denotes the maximum value of the rare earth element content, T, of at least 10 first intermediate bodies min Representing the lowest value of the rare earth element content in at least 10 first intermediates.
Compared with the prior art, the technical effect achieved by adopting the technical scheme is as follows: the content of the rare earth elements in the first intermediate is detected before the crushing treatment, and the distribution consistency of the rare earth elements among the first intermediate subjected to the crushing treatment is controlled to be less than 2 percent, so that the design can prevent the reaction from being uneven due to component segregation during the subsequent aging treatment.
In one embodiment of the present invention, before S200, the gallium content of at least 10 first intermediates is detected, and the gallium content of at least 10 first intermediates is controlledThe content satisfies the following formula: (Ga) max - Ga min ）/ Ga max *100%＜5%；
Wherein Ga max Represents the maximum value of the content of gallium element in at least 10 first intermediates, ga min Representing the lowest value of the content of gallium element in at least 10 first intermediates.
Compared with the prior art, the technical effect achieved by adopting the technical scheme is as follows: the content of the gallium element in the first intermediate is detected before the crushing treatment, and the distribution consistency of the gallium element among the first intermediates subjected to the crushing treatment is controlled to be less than 5 percent, so that the design can prevent the reaction from being uneven due to component segregation during the subsequent aging treatment.
In one example of the present invention, 100 parts by mass of the rare earth permanent magnet further includes: less than or equal to 0.2 mass part of titanium, less than or equal to 0.3 mass part of zirconium, 0.1-0.15 mass part of copper and 1.5-2 mass parts of cobalt.
Compared with the prior art, the technical scheme has the following technical effects: in the rare earth permanent magnet, the addition amounts of rare earth, gallium and boron are limited, and the effect of improving the Hcj of the sintered magnet under the condition of not adding or adding less heavy rare earth is realized by increasing the content of gallium and reducing the content of boron. Other elements are added into the rare earth permanent magnet, so that the performances of high temperature resistance and the like of the rare earth permanent magnet can be improved.
In one embodiment of the present invention, the rare earth is at least one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium; and/or
The rare earth is at least one of gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and yttrium.
Compared with the prior art, the technical effect achieved by adopting the technical scheme is as follows: the rare earth in the rare earth permanent magnet is light rare earth in most cases, and the light rare earth mainly comprises at least one of praseodymium and neodymium. In some cases, the rare earth in the rare earth permanent magnet will also comprise heavy rare earths, the heavy rare earths comprising primarily at least one of dysprosium, yttrium. In some cases, in order to greatly increase Hcj of a sintered magnet, nd is replaced with heavy rare earth elements, dysprosium and terbium 2 Fe 14 In the case of increasing Hcj with neodymium in B, the Hcj of the sintered magnet is increased by using a "high Ga low B" method.
The invention also provides a rare earth permanent magnet which is prepared by adopting the preparation method.
Compared with the prior art, the technical scheme has the following technical effects: the rare earth permanent magnet prepared by the method has R widely and stably distributed in the grain boundary phase 6 -T 13 The M phase, so that the produced rare earth permanent magnet of the same batch has the same and stable high Hcj performance.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments thereof are described in detail below.
The invention provides a preparation method of a rare earth permanent magnet material, which comprises the following steps:
s100: preparing raw materials, and smelting the raw materials to obtain a first intermediate;
s200: crushing the first intermediate to obtain a second intermediate;
s300: carrying out orientation molding treatment on the second intermediate to obtain a third intermediate;
s400: sintering the third intermediate to obtain a fourth intermediate;
s500: and carrying out aging treatment on the fourth intermediate to obtain the rare earth permanent magnet.
Wherein, the raw materials comprise simple substances or alloys of rare earth elements, boron elements, gallium elements, titanium elements, zirconium elements, copper elements, cobalt elements, aluminum elements and iron elements. When the raw materials are smelted, the raw materials are firstly put into a vacuum induction furnace, and the vacuum degree of the vacuum induction furnace is controlled to be 10 -2 Pa-10 -3 Pa, the smelting temperature is 1300-1500 ℃, and the raw materials are smelted to a molten state. Preferably, the smelting temperature is controlled to be 1400-1500 ℃. And then pouring the molten raw materials into a mould at the temperature of 1400-1500 ℃ for casting to obtain a first intermediate, wherein the first intermediate obtained by casting is a rare earth alloy sheet.
After smelting and before hydrogen absorption and crushing, 10 rare earth alloy sheets are randomly taken for ICP test, the rare earth content and the gallium content of the rare earth alloy sheets are detected, and the distribution consistency of the rare earth elements among the 10 rare earth alloy sheets is controlled to be less than 2 percent, and the distribution consistency of the gallium elements is controlled to be less than 5 percent.
The distribution consistency of the rare earth elements is embodied by the content of neodymium elements, and the specific calculation mode is as follows:
（Nd max - Nd min ）/ Nd max *100%＜2%；
wherein, nd max Represents the value of the highest neodymium content among 10 rare earth alloy sheets, nd min The value of the minimum neodymium content in 10 pieces of rare earth alloy is shown. When the neodymium content in 10 rare earth alloy sheets meets the formula, the rare earth alloy sheets (namely the first intermediate) obtained by preparation meet the requirement of subsequent hydrogen absorption and crushing.
The specific calculation method of the distribution consistency of the gallium element is as follows:
（Ga max - Ga min ）/ Ga max *100%＜5%；
wherein Ga max Represents the value of Ga with the highest content in 10 rare earth alloy sheets, ga min Represents the lowest value of the gallium content in 10 pieces of rare earth alloy. When the gallium content in 10 rare earth alloy sheets meets the formula, the prepared rare earth alloy sheet (namely the first intermediate) meets the requirement of subsequent hydrogen absorption and crushing.
The distribution consistency of the rare earth elements in the rare earth alloy sheet subjected to hydrogen absorption crushing is controlled to be less than 2 percent, and the distribution consistency of the gallium elements is controlled to be less than 5 percent, so that the components of the rare earth alloy sheet are consistent, and R cannot be caused by component segregation during subsequent tempering aging reaction 6 -T 13 The M phases are unevenly distributed and the amount of production is small.
Further, S200 specifically includes:
s210: hydrogen absorption crushing is carried out on the first intermediate to obtain a coarse crushed material;
s220: and carrying out micro-crushing treatment on the coarse crushed material to obtain a second intermediate.
Specifically, in the hydrogen absorption and fragmentation in S210, the hydrogen absorption characteristics of the rare earth intermetallic compound are utilized, the rare earth alloy sheet is placed in a hydrogen environment, and hydrogen enters the alloy along the neodymium-rich phase thin layer, so that the alloy is expanded, burst and fragmented, and the thin sheet is changed into coarse powder. Controlling the hydrogen absorption pressure to be 0.3MPa-0.4MPa and the dehydrogenation temperature to be 560-600 ℃ in the hydrogen absorption crushing process, thereby obtaining the crude crushed material.
In S220, the coarse crushing material is further refined, the fine crushing treatment is mainly powder grinding through airflow milling, the pressure of a milling chamber is controlled within the range of 0.5MPa-0.7MPa in the airflow milling process, the prepared second intermediate is in a fine powder shape, and the particle size of the second intermediate is controlled within the range of 3.2um-4.2um. Preferably, the pressure in the polishing chamber is controlled to be in the range of 0.55MPa to 0.65 MPa.
Further, after the powder is milled by the jet mill, the particle size distribution of the obtained second intermediate needs to satisfy the following formula: d50 < D90/D10 < D50+2, so that the particle size distribution is as consistent as possible, which is favorable for the stability and consistency of subsequent reactions.
In the above formula, D50 represents the particle size corresponding to a sample having a cumulative particle size distribution percentage of 50%, D10 represents the particle size corresponding to a sample having a cumulative particle size distribution percentage of 10%, and D90 represents the particle size corresponding to a sample having a cumulative particle size distribution percentage of 90%, wherein the units of D10, D50, and D90 are um.
Further, in S300, the second intermediate is subjected to orientation molding in a magnetic field, and the magnetic field orientation molding is performed by aligning the easy magnetization direction of the powder particles by using the interaction between the magnetic powder (second intermediate) and an external magnetic field so that the easy magnetization direction coincides with the final magnetization direction of the magnet.
Further, in S400, the sintering process is completed in a vacuum sintering furnace, and the sintering treatment is sintering for 7.5h-8.5h at the sintering temperature of 1000-1100 ℃ in a vacuum environment.
After the sintering treatment, a sintered magnet (fourth intermediate) is obtained, and then the sintered magnet is subjected to aging treatment to obtain the rare earth permanent magnet. The ageing treatment being carried out by multistage temperingThe method specifically comprises the steps of primary aging at 850-950 ℃ for 2-3 h, secondary aging at 450-550 ℃ for 3-8 h, tertiary aging at 850-950 ℃ for 2-3 h, quaternary aging at 600-700 ℃ for 3-8 h. R can be promoted by eutectic reaction at the time of multi-stage tempering 6 -T 13 Stability of the M grain boundary phase reactions.
Further, the aging treatment is also performed in a vacuum atmosphere.
Furthermore, the rare earth permanent magnet can also be prepared by adopting a double-alloy method.
Furthermore, the aging time of the secondary aging treatment is 3h-6h, and the aging time of the fourth aging treatment is 3h-6h;
furthermore, the aging time of the secondary aging treatment is 5h-8h, and the aging time of the fourth aging treatment is 5h-8h;
further, the rare earth permanent magnet is specifically an R-T-B rare earth permanent magnet material, wherein R denotes a rare earth element, T denotes a transition metal element and a third main group metal element, and B denotes a boron element. The most important performance of the R-T-B series rare earth permanent magnet material is intrinsic coercive force Hcj, and the higher Hcj is, the better the high temperature resistance of the rare earth permanent magnet is. R is contained in R-T-B series rare earth permanent magnet 2 Fe 14 The main phase B mainly comprises the following components in 100 parts by mass of R-T-B series rare earth permanent magnet: 29-32 parts of rare earth, 0.88-0.92 part of boron, 0.25-0.45 part of gallium, less than or equal to 0.2 part of titanium, less than or equal to 0.3 part of zirconium, 0.1-0.15 part of copper, 1.5-2 parts of cobalt, less than or equal to 0.6 part of aluminum and 63.38-68.27 parts of iron.
Further, the rare earth is at least one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium and europium. Preferably, the rare earth includes at least one of praseodymium and neodymium.
Further, the rare earth is at least one of gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and yttrium. Preferably, the rare earth comprises at least one of dysprosium and yttrium.
The preparation method can be used at the condition of no heavy rare earth or low heavy rare earth contentAnd obtaining the rare earth permanent magnet with high remanence Br and high coercive force Hcj, wherein the fluctuation of the coercive force Hcj of the rare earth permanent magnet prepared in the same batch is less than 4%. The invention limits the addition range of rare earth, gallium and boron elements, limits the dispersion of component distribution in the alloying process, limits the particle size distribution range in the powder making process and ensures that a delt phase (R) generated by eutectic reaction in the tempering process is subjected to multistage heat treatment 6 -T 13 the-M phase) has wider distribution range, is more uniform and is more stable, so that the distribution consistency of the coercive force Hcj of the rare earth permanent magnet generated in the same batch is better.
The method for producing a rare earth permanent magnet according to the present invention will be described in detail with reference to the following examples.
Rare earth permanent magnets were prepared by preparing raw materials with the compositions shown in table 1, wherein the aging treatment steps of examples 1 to 3 and comparative examples 4 and 5 were controlled: the primary aging treatment temperature is 890 ℃, the aging time is 2h, the secondary aging treatment temperature is 510 ℃, the aging time is 4h, the tertiary aging treatment temperature is 900 ℃, the aging time is 2h, the quaternary aging treatment temperature is 630 ℃ and the aging time is 3h, the secondary aging treatment is carried out on the aging treatment steps of comparative examples 1-3 corresponding to examples 1-3, the primary aging treatment temperature is 900 ℃, the aging time is 3.5h, the secondary aging treatment temperature is 490 ℃ and the aging time is 7.5h.
TABLE 1
The rare earth permanent magnets of examples 1 to 3 and comparative examples 1 to 5 were subjected to performance tests, 5 samples per group were taken for detection, and the detection results are shown in table 2. The detection result shows that the rare earth permanent magnet subjected to multistage aging treatment has higher and more stable Hcj.
TABLE 2
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected by one skilled in the art without departing from the spirit and scope of the invention, as defined in the appended claims.
Claims (9)
1. A method for preparing a rare earth permanent magnet, characterized by comprising:
s100: preparing raw materials, and smelting the raw materials to obtain a first intermediate;
s200: crushing the first intermediate to obtain a second intermediate;
s300: carrying out orientation molding treatment on the second intermediate to obtain a third intermediate;
s400: sintering the third intermediate to obtain a fourth intermediate;
s500: carrying out aging treatment on the fourth intermediate to obtain the rare earth permanent magnet;
wherein, the S500 specifically includes:
s510: carrying out primary aging treatment on the fourth intermediate, controlling the aging temperature to be 850-950 ℃ and the aging time to be 2-3 h;
s520: carrying out secondary aging treatment on the fourth intermediate, controlling the aging temperature to be 450-550 ℃ and the aging time to be 3-8 h;
s530: carrying out three times of aging treatment on the fourth intermediate, controlling the aging temperature to be 850-950 ℃ and the aging time to be 2-3 h;
s540: carrying out four times of aging treatment on the fourth intermediate, controlling the aging temperature to be 600-700 ℃ and the aging time to be 3-8 h, and obtaining the rare earth permanent magnet;
the rare earth permanent magnet comprises, based on 100 parts by mass: 29-32 parts of rare earth, 0.88-0.92 part of boron, 0.25-0.45 part of gallium and 66.63-69.87 parts of iron.
2. The method according to claim 1, wherein S100 specifically comprises:
s110: preparing the raw materials, putting the raw materials into a vacuum induction furnace for smelting, and controlling the vacuum degree of the vacuum induction furnace to be 10 < -2 > Pa to 10 < -3 > Pa and the smelting temperature to be 1300-1500 ℃;
s120: casting at 1400-1500 ℃ to obtain the first intermediate.
3. The preparation method according to claim 1, wherein the S200 specifically comprises:
s210: carrying out hydrogen absorption crushing on the first intermediate to obtain a coarse crushing material;
s220: and carrying out micro-crushing treatment on the coarse crushing material to obtain the second intermediate.
4. The production method according to claim 3,
controlling the hydrogen absorption pressure to be 0.3MPa-0.4MPa and the dehydrogenation temperature to be 560-600 ℃ in the hydrogen absorption crushing process; and/or
In the micro-crushing treatment, the pressure of the airflow grinding chamber is controlled to be 0.5MPa-0.7MPa, and the granularity is controlled to be 3.2um-4.2um.
5. The preparation method according to claim 1, wherein the sintering treatment in S400 is performed at a sintering temperature of 1000 ℃ to 1100 ℃ for a sintering time of 7.5h to 8.5h.
6. The method according to any one of claims 1 to 5, wherein before the step S200, at least 10 of the first intermediate bodies are subjected to rare earth element content detection, and the rare earth element content of at least 10 of the first intermediate bodies is controlled to satisfy the following formula:
（T max - T min ）/T max *100%＜2%；
wherein, T is max Represents the maximum value of the rare earth element content, T, of at least 10 of the first intermediate bodies min Represents the lowest value of the rare earth element content in at least 10 first intermediates.
7. The preparation method according to claim 6, wherein before performing S200, the gallium content of at least 10 of the first intermediates is detected, and the gallium content of at least 10 of the first intermediates is controlled to satisfy the following formula:
（Ga max - Ga min ）/ Ga max *100%＜5%；
wherein Ga max Represents the maximum value of the content of gallium element in at least 10 of the first intermediates, ga min Represents the lowest value of the gallium content in at least 10 of the first intermediates.
8. The production method according to any one of claims 1 to 5, characterized by further comprising, in 100 parts by mass of the rare earth permanent magnet:
less than or equal to 0.2 mass part of titanium, less than or equal to 0.3 mass part of zirconium, 0.1-0.15 mass part of copper and 1.5-2 mass parts of cobalt.
9. A rare earth permanent magnet characterized by being produced by the production method according to any one of claims 1 to 8.
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