A terbium target material and preparation method thereof, rare earth permanent magnet, and new energy vehicle

Abstract

The present application relates to the technical field of target material preparation, and provides a terbium target material and a preparation method thereof, as well as a rare earth permanent magnet and a new energy vehicle. The preparation method comprises: mechanically crushing the terbium residual target to obtain a terbium block; subjecting the terbium block to hydrogen crushing treatment, and then subjecting it to inert gas flow pulverization to obtain terbium powder; ball milling and mixing terbium powder, solid borane, solvent and organic additive to obtain a slurry; granulating the slurry to obtain granulated powder; isostatically pressing the granulated powder to obtain a blank; sintering the blank to obtain a terbium target material. The preparation method of the terbium target material provided in the present application uses the terbium residual target as a raw material, realizes green circulation, and low-cost manufacturing of the whole process; solid borane generates boron and hydrogen during the sintering process to form a reducing atmosphere to prevent oxidation of terbium metal powder; by pressing and molding the granulated powder, the powder is closely arranged under high pressure, which helps to promote diffusion and bonding between powder particles during the sintering process, thereby forming a more uniform and dense target material.

Description

Technical Field

[0001] The present application belongs to the technical field of target material preparation, and in particular relates to a terbium target material and a preparation method thereof, a rare earth permanent magnet, and a new energy vehicle. Background Art

[0002] Neodymium iron boron (NdFeB) rare earth permanent magnets have excellent properties such as high remanence, high coercive force and high magnetic energy product, and are widely used in motors of new energy vehicles and wind power generation equipment. With the continuous increase in motor speed and power, higher requirements are placed on the magnetic properties of NdFeB rare earth permanent magnets. The methods commonly used to improve the magnetic properties of NdFeB rare earth permanent magnets mainly include: using terbium target as raw material, sputtering coating using magnetron sputtering equipment, depositing a terbium metal layer on the surface of the NdFeB rare earth permanent magnet, and then performing grain boundary diffusion heat treatment to diffuse terbium into the interior of the NdFeB rare earth permanent magnet, thereby improving the magnetic properties of the NdFeB rare earth permanent magnet.

[0003] At present, the utilization rate of sputtering targets is generally low, especially the utilization rate of planar targets is even lower. The remaining target residues are usually treated as waste at a very low price. In the case of expensive raw materials of pure terbium powder / ingot, the manufacturing cost is undoubtedly too high. Therefore, how to recycle terbium target residues and re-manufacture terbium targets is of great significance.

[0004] In addition, the common method for preparing terbium targets is mainly based on melting and casting. However, the terbium melt cools quickly. During the melting and casting process, improper control of the casting rate and casting temperature is prone to occur, resulting in defects such as excessively large grains, uneven crystal phase, shrinkage cavities and looseness in the terbium target. Oxygen is also easily accumulated near grain boundaries and shrinkage cavities, which increases the oxygen content of the terbium target, thereby affecting the quality of the terbium target coating and, in turn, the grain boundary diffusion effect. Summary of the invention

[0005] The purpose of this application is to provide a terbium target material and a preparation method thereof, a rare earth permanent magnet, and a new energy vehicle, aiming to solve the problems of shrinkage cavities, looseness, and uneven crystal phases in existing terbium targets, as well as the problem of high production costs.

[0006] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0007] In a first aspect, the present application provides a method for preparing a terbium target, comprising the following steps:

[0008] Mechanically crushing the terbium residual target to obtain terbium blocks;

[0009] The terbium block is subjected to hydrogen crushing treatment, and then pulverized by inert gas flow to obtain terbium powder;

[0010] The terbium powder, solid borane, solvent and organic additive are mixed by ball milling to obtain a slurry;

[0011] granulating the slurry to obtain granulated powder;

[0012] isostatically pressing the granulated powder to obtain a green body;

[0013] The green body is subjected to degreasing and sintering treatments, and then machined to obtain a terbium target material.

[0014] In a second aspect, the present application provides a terbium target material, which is prepared by the preparation method of the terbium target material provided by the present application; wherein the oxygen content of the terbium target material is lower than 1000 ppm and the relative density is higher than 98.5%.

[0015] In a third aspect, the present application provides a rare earth permanent magnet, comprising a NdFeB magnet and a terbium metal layer deposited on the surface of the NdFeB magnet, wherein the terbium metal layer is obtained by sputtering and coating the terbium target provided by the present application.

[0016] In a fourth aspect, the present application provides a new energy vehicle, including a motor, wherein the motor includes the rare earth permanent magnet provided in the present application.

[0017] Compared with the prior art, this application has the following beneficial effects:

[0018] (1) Using terbium residual target as raw material for terbium target preparation, achieving green recycling and low-cost manufacturing throughout the entire process.

[0019] (2) Hydrogen cracking and inert gas flow pulverization of terbium blocks can prevent terbium metal oxidation, explosion prevention and improve the pulverization efficiency of terbium blocks.

[0020] (3) The added solid borane generates boron and hydrogen during the sintering process, forming a reducing atmosphere, thereby preventing the oxidation of terbium metal powder and reducing the oxygen content of the terbium target. This helps the terbium grain boundaries in the terbium target coating diffuse into the NdFeB magnet, thereby improving the magnetic properties of the NdFeB rare earth permanent magnet. In addition, the generated boron, as a constituent element of the NdFeB magnet, will not introduce impurities and will not affect the performance of the NdFeB magnet.

[0021] (4) By pressing the granulated powder into shape, the powder is arranged closely under high pressure, which can promote the diffusion and bonding between the powder particles during the sintering process to form a more uniform and dense target material, thus overcoming the defects of high-temperature smelting such as excessively large grains, uneven crystal phases, shrinkage cavities and looseness. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a process flow chart of the method for preparing a terbium target provided in an embodiment of the present application. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0025] The first aspect of the present application provides a method for preparing a terbium target material, such as Figure 1 As shown, the following steps are included:

[0026] S01: mechanically crushing the terbium residual target to obtain terbium blocks;

[0027] S02: subjecting the terbium block to hydrogen crushing treatment, and then subjecting it to inert gas flow pulverization to obtain terbium powder;

[0028] S03: ball-milling terbium powder, solid borane, solvent and organic additive to obtain slurry;

[0029] S04: granulating the slurry to obtain granulated powder;

[0030] S05: isostatically pressing the granulated powder to obtain a green body;

[0031] S06: Degreasing and sintering the green body, and then machining to obtain a terbium target.

[0032] The preparation method of the terbium target provided in the embodiment of the present application, on the one hand, uses the terbium residual target as the raw material for preparing the terbium target, realizes green circulation, and low-cost manufacturing of the whole process, and the added solid borane generates boron and hydrogen during the sintering process, creates a reducing environment, and prevents the oxidation of the terbium metal powder, thereby reducing the oxygen content of the terbium target, which helps the terbium grain boundaries in the terbium target coating to diffuse into the NdFeB magnet, and improves the magnetic properties of the NdFeB rare earth permanent magnet; and the generated boron, as a constituent element of the NdFeB magnet, will not introduce impurities and will not affect the performance of the NdFeB magnet. On the other hand, by hydrogen cracking and inert gas flow pulverizing the terbium block, terbium metal oxidation can be prevented, explosion prevention and the pulverization efficiency of the terbium block can be improved; and by pressing the granulated powder into shape, the powder is closely arranged under high pressure, which can promote the diffusion and bonding between powder particles during the sintering process to form a more uniform and dense target material, thus overcoming the defects of excessively large grains, uneven crystal phases, shrinkage cavities and looseness that are prone to occur in high-temperature smelting.

[0033] In the above step S01, the oxygen content of the terbium residual target is lower than 500 ppm, and the metal impurity content is lower than 100 ppm.

[0034] In an embodiment, the mechanical crushing may be performed by using a hammer crusher.

[0035] In the embodiment, the particle size of the terbium block is 40-60 mm. The terbium residual target is first mechanically crushed into terbium blocks within this particle size range, which can prevent the terbium block from being oxidized and facilitate the terbium block to absorb hydrogen and break.

[0036] In the above step S02, in the embodiment, the step of subjecting the terbium block to hydrogen crushing treatment includes: subjecting the terbium block to hydrogen absorption reaction under the condition of hydrogen pressure of 0.1~0.5MPa, and then evacuating and heating to 400~600℃ to carry out heat preservation dehydrogenation reaction for 2~6h.

[0037] Specifically, the terbium block is loaded into a hydrogen crushing furnace, evacuated to 0.01-0.1 Pa, and then hydrogen is introduced to 0.1-0.5 MPa for hydrogen absorption reaction. After the hydrogen absorption reaction is completed, the terbium block is evacuated and heated to 400-600° C. for thermal dehydrogenation for 2-6 hours.

[0038] In the embodiment, the particle size of the terbium powder is 3-10 μm.

[0039] In the above step S03, in an embodiment, the solid borane is selected from decaborane. Decaborane generates boron and hydrogen during the sintering process, creating a reducing environment, which can prevent the oxidation of terbium metal powder and reduce the oxygen content of the terbium target. In addition, the generated boron, as a constituent element of the NdFeB magnet, will not introduce impurities and will not affect the performance of the NdFeB magnet.

[0040] In an embodiment, the solvent is selected from terpineol and / or ethanol; these solvents can prevent the terbium powder from being oxidized.

[0041] In an embodiment, the organic additive includes polyalphaolefin, fatty acid methyl ester, polyethyleneimine, and polyvinylpyrrolidone in a mass ratio of (2-4) / (0.1-2) / (0.5-2) / (0.2-1). Fatty acid methyl ester can remove free radicals on the surface of terbium powder, and polyalphaolefin and fatty acid methyl ester can form a protective barrier for terbium powder to isolate terbium powder from contact with oxygen. Therefore, under the cooperation of polyalphaolefin and fatty acid methyl ester, terbium powder can be prevented from oxidation during ball milling mixing and molding, thereby helping to reduce the oxygen content of terbium target. Polyvinylpyrrolidone and polyethyleneimine can not only firmly bond terbium powder and solid borane to form dense granulated powder, which is not easy to break or crack and is conducive to molding, but also polyvinylpyrrolidone decomposes during the sintering process, which helps to remove oxygen and impurities. The amine group contained in polyethyleneimine is reducing, and its decomposition during the sintering process can play a reducing role to prevent terbium oxidation. Therefore, under the synergistic effect of the organic additives in this embodiment, terbium is fully protected, so the oxygen content of the terbium target is lower.

[0042] In an embodiment, the step of ball-milling terbium powder, solid borane, solvent and organic additive comprises: mixing poly-alpha-olefin, fatty acid methyl ester and solvent to obtain a mixed solution; adding terbium powder and solid borane to the mixed solution and ball-milling, and then adding polyethyleneimine and polyvinyl pyrrolidone and mixing evenly to obtain a slurry.

[0043] In the embodiment, the amount of the organic additive added is 0.5-5% of the total weight of the terbium powder and the solid borane.

[0044] In the embodiment, the mass ratio of terbium powder to solid borane is (95-98) / (2-5). The addition amount of the solid borane can generate an appropriate amount of hydrogen to create a reducing environment during the sintering process, prevent the oxidation of the terbium metal powder, reduce the oxygen content of the terbium target, and the boron generated will not be excessive, so as not to have a negative impact on the performance of the NdFeB magnet.

[0045] In the embodiment, the solid content of the slurry is 75-85%.

[0046] In the above step S06, in the embodiment, the degreasing treatment is performed in a vacuum atmosphere, at a temperature of 450-550° C., for a time of 6-12 hours; wherein the vacuum degree may be 0.1-0.01 Pa.

[0047] In the embodiment, the sintering process is performed in a vacuum atmosphere or an inert atmosphere, at a temperature of 1100-1200° C., for a time of 12-36 hours, wherein the inert atmosphere may be argon or nitrogen.

[0048] A second aspect of an embodiment of the present application provides a terbium target material, which is prepared by the preparation method of the terbium target material provided by the embodiment of the present application; wherein the oxygen content of the terbium target material is lower than 1000 ppm and the relative density is higher than 98.5%.

[0049] The terbium target material provided in the embodiment of the present application is prepared by the preparation method provided in the embodiment of the present application, so it has a low oxygen content and a uniform and dense structure, which helps to improve the coating quality of the terbium target material and has a better grain boundary diffusion effect.

[0050] A third aspect of an embodiment of the present application provides a rare earth permanent magnet, comprising a NdFeB magnet and a terbium metal layer deposited on the surface of the NdFeB magnet, wherein the terbium metal layer is obtained by sputtering and coating the terbium target provided by the present application.

[0051] The rare earth permanent magnet provided in the embodiment of the present application has a terbium metal layer on its surface obtained by sputtering and coating the terbium target provided in the embodiment of the present application, so the magnetic properties of the NdFeB magnet can be significantly enhanced after grain boundary diffusion heat treatment.

[0052] A fourth aspect of an embodiment of the present application provides a new energy vehicle, including a motor, which includes the rare earth permanent magnet provided in an embodiment of the present application.

[0053] The new energy vehicle provided in the embodiment of the present application can improve the energy conversion efficiency of the motor, thereby improving the performance and endurance of the vehicle, because the motor includes the rare earth permanent magnet provided in the present application.

[0054] The following describes the invention in conjunction with specific embodiments.

[0055] Example 1

[0056] This embodiment provides a method for preparing a terbium target, comprising the following steps:

[0057] S11: mechanically crushing the terbium residual target (oxygen content less than 500 ppm, metal impurity content less than 100 ppm) to obtain a terbium block with a particle size of 50 mm;

[0058] S12: The terbium block is placed in a hydrogen crushing furnace, and after vacuuming to 0.3Pa, hydrogen is introduced to 0.3MPa, and the valve is closed to carry out a hydrogen absorption reaction. When the hydrogen pressure drops significantly, the valve is opened again and the pressure is maintained at 0.3MPa. When no hydrogen enters the hydrogen crushing furnace, the hydrogen absorption reaction ends. Then, vacuuming is carried out and heating is carried out to 550°C for heat preservation and dehydrogenation for 4h, and then air flow pulverization is carried out under nitrogen protection to obtain terbium powder with a particle size D50 of 5.6μm;

[0059] S13: mixing poly-alpha-olefin, fatty acid methyl ester and ethanol to obtain a mixed solution; adding terbium powder and decaborane to the mixed solution and mixing by ball milling; and then adding polyethyleneimine and polyvinyl pyrrolidone and mixing evenly to obtain a slurry;

[0060] The mass ratio of terbium powder to decaborane is 97 / 3, the amount of organic additive added is 3% of the total weight of terbium powder and decaborane, the mass ratio of organic additive: polyalphaolefin, fatty acid methyl ester, polyethyleneimine and polyvinylpyrrolidone is 3 / 1 / 1.2 / 0.8, and the solid content of the slurry is 80%;

[0061] S14: introducing the slurry into a centrifugal spray granulator (with an inlet temperature of 190° C. and an outlet temperature of 100° C.) for spray granulation to obtain granulated powder;

[0062] S15: isostatically pressing the granulated powder to obtain a green body;

[0063] S16: placing the green body in a vacuum sintering furnace, evacuating to 0.05 Pa, and then heating to 550°C for 9 hours, and then heating to 1200°C for 24 hours, and then machining to obtain a terbium target.

[0064] Example 2

[0065] This embodiment provides a method for preparing a terbium target material, which is different from Embodiment 1 in that:

[0066] In step S13, the mass ratio of terbium powder to decaborane is 95 / 5.

[0067] Example 3

[0068] This embodiment provides a method for preparing a terbium target material, which is different from Embodiment 1 in that:

[0069] In step S13, the mass ratio of terbium powder to decaborane is 98 / 2.

[0070] Example 4

[0071] This comparative example provides a method for preparing a terbium target material, which is different from Example 1 in that:

[0072] In step S13, the mass ratio of terbium powder to decaborane is 93 / 7.

[0073] Example 5

[0074] This comparative example provides a method for preparing a terbium target material, which is different from Example 1 in that:

[0075] In step S13, the mass ratio of terbium powder to decaborane is 99 / 1.

[0076] Example 6

[0077] This embodiment provides a method for preparing a terbium target material, which is different from Embodiment 1 in that:

[0078] In step S13, the mass ratio of poly-alpha-olefin, fatty acid methyl ester, polyethyleneimine and polyvinyl pyrrolidone is 2 / 2 / 0.5 / 1.

[0079] Example 7

[0080] This embodiment provides a method for preparing a terbium target material, which is different from Embodiment 1 in that:

[0081] In step S13, the mass ratio of poly-alpha-olefin, fatty acid methyl ester, polyethyleneimine and polyvinyl pyrrolidone is 4 / 0.1 / 2 / 0.2.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing a terbium target material, which is different from Example 1 in that:

[0084] In step S13, decaborane is not added.

[0085] Comparative Example 2

[0086] This comparative example provides a method for preparing a terbium target material, which is different from Example 1 in that:

[0087] In step S13, no poly-alpha-olefin is added, and the mass ratio of fatty acid methyl ester, polyethyleneimine and polyvinyl pyrrolidone is 4 / 1.2 / 0.8.

[0088] Comparative Example 3

[0089] This comparative example provides a method for preparing a terbium target material, which is different from Example 1 in that:

[0090] In step S13, fatty acid methyl ester is not added, and the mass ratio of poly-alpha-olefin, polyethyleneimine and polyvinyl pyrrolidone is 4 / 1.2 / 0.8.

[0091] Comparative Example 4

[0092] This comparative example provides a method for preparing a terbium target material, which is different from Example 1 in that:

[0093] In step S13, polyethyleneimine is not added, and the mass ratio of poly-alpha-olefin, fatty acid methyl ester and polyvinyl pyrrolidone is 3 / 1 / 2.

[0094] Comparative Example 5

[0095] This comparative example provides a method for preparing a terbium target material, which is different from Example 1 in that:

[0096] In step S13, polyvinyl pyrrolidone is not added, and the mass ratio of poly-alpha-olefin, fatty acid methyl ester and polyethyleneimine is 3 / 1 / 2.

[0097] Comparative Example 6

[0098] This comparative example provides a method for preparing a terbium target material, which is different from Example 1 in that:

[0099] In step S13, "polyvinyl alcohol" is used instead of "organic auxiliary agent".

[0100] Comparative Example 7

[0101] This comparative example provides a method for preparing a terbium target, comprising the following steps:

[0102] S1: Place the terbium residual target (oxygen content less than 500ppm, metal impurity content less than 100ppm) in a vacuum melting furnace, heat it to 1450℃ at a frequency of 5000 Hz, melt it and keep it warm for 30 minutes to form a terbium melt;

[0103] S2: Casting the terbium melt into a water-cooled mold, controlling the cooling rate at 50°C / s by controlling the water flow rate, taking out the ingot from the mold after cooling, and then machining to obtain the terbium target.

[0104] Comparative Example 8

[0105] This comparative example provides a method for preparing a terbium target material, which is different from Example 1 in that:

[0106] The terbium powder obtained by crushing the terbium residual target in Example 1 is replaced by a commercially available terbium powder raw material having an oxygen content of less than 500 ppm and a metal impurity content of less than 100 ppm.

[0107] Related performance test analysis:

[0108] 1. The actual density of the terbium targets prepared in Example 1 and Comparative Example 7 was tested by the Archimedes density test method. The theoretical density was used as a reference. Relative density = actual density / theoretical density × 100%;

[0109] The relative densities of the terbium targets obtained in Example 1 and Comparative Example 7 were 99.4% and 95.6%, respectively. It can be seen that the density of the terbium target obtained in the embodiment of the present application is significantly higher than that in Comparative Example 7, indicating that the embodiment of the present application adopts a powder metallurgy atmosphere sintering process, and by pressing the granulated powder into shape, the powder is closely arranged under high pressure, and there are more contact points, which is conducive to promoting the diffusion and bonding between the powder particles during the sintering process, so a more uniform and dense terbium target is formed. However, due to improper control of the casting rate and casting temperature during high-temperature smelting, the terbium target is prone to defects such as excessively large grains, uneven crystal phases, shrinkage cavities, and looseness, so the relative density is relatively low.

[0110] 2. The O content of the silicon targets prepared in Examples 1 to 7 and Comparative Examples 1 to 8 was tested using an oxygen and nitrogen analyzer.

[0111] 3. The terbium targets prepared in Examples 1 to 5 and Comparative Examples 7 and 8 were sputtered and coated by magnetron sputtering equipment to deposit a terbium metal layer on the surface of the NdFeB substrate, and then diffused at 900° C. for 4 hours to obtain a rare earth permanent magnet; according to GBT 3217-2013 “Magnetic Test Methods for Permanent Magnetic Materials”, the magnetic properties of the rare earth permanent magnets corresponding to Examples 1 to 5 and Comparative Examples 6 and 7 were tested;

[0112] The test results are shown in Table 1 below:

[0113] Table 1

[0114]

[0115] It can be seen from Table 1 that the oxygen content of the terbium target materials of Examples 1 to 3 is lower than that of Example 5, and is significantly lower than that of Comparative Example 1, indicating that the solid borane added in the examples of the present application generates hydrogen during the sintering process to create a reducing environment, which can prevent terbium metal oxidation, so the oxygen content of the terbium target materials is significantly lower.

[0116] The oxygen content of the terbium target material of Example 1 is lower than that of Comparative Examples 2 to 5, and is significantly lower than that of Comparative Example 6, indicating that the embodiment of the present application, under the synergistic effect of four organic additives of poly-alpha olefin, fatty acid methyl ester, polyethyleneimine, and polyvinyl pyrrolidone, can remove free radicals (containing oxygen) on the surface of terbium metal during ball milling and molding, and form a protective barrier to isolate oxygen; exclude oxygen during the sintering process, and form a reducing atmosphere to prevent terbium oxidation, so the terbium target material of the present application has a low oxygen content.

[0117] The oxygen content of the terbium target material in Example 1 is significantly lower than that in Comparative Example 7, and is close to that in Comparative Example 8, indicating that the terbium residual target has undergone specific treatment in the embodiments of the present application, and the terbium target has a low oxygen content, which can even be comparable to the terbium target material made of pure terbium metal powder in Comparative Example 8. Comparative Example 7 has a high oxygen content due to its large and uneven grain size, as well as the shrinkage cavities and looseness that are relatively easy to accumulate oxygen.

[0118] The remanence, coercive force and maximum magnetic energy product of the rare earth permanent magnet corresponding to Example 1 are all greater than those of Example 4, indicating that although the solid borane added in the present application can reduce the oxygen content of the terbium target, the excessively high B content in the terbium target coating will affect the grain boundary diffusion of terbium.

[0119] The remanence, coercive force and maximum magnetic energy product of the rare earth permanent magnet corresponding to Example 1 are significantly greater than those of Comparative Example 7, indicating that the terbium target coating in the embodiment of the present application has a low oxygen content and better film quality, which is more conducive to the thermal diffusion of terbium into the grain boundaries of the NdFeB magnet, thereby obtaining better magnetic properties.

[0120] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a terbium target, characterized in that: The following steps are involved: Mechanically crushing the terbium residual target to obtain terbium blocks; The terbium block is subjected to hydrogen crushing treatment, and then pulverized by inert gas flow to obtain terbium powder; The terbium powder, solid borane, solvent and organic additive are ball-milled and mixed to obtain a slurry; the mass ratio of the terbium powder to the solid borane is (95-98) / (2-5); the organic additive comprises polyalphaolefin, fatty acid methyl ester, polyethyleneimine and polyvinyl pyrrolidone in a mass ratio of (2-4) / (0.1-2) / (0.5-2) / (0.2-1); granulating the slurry to obtain granulated powder; isostatically pressing the granulated powder to obtain a green body; The green body is subjected to degreasing and sintering treatments, and then machined to obtain a terbium target material.

2. The preparation method according to claim 1, characterized in that The step of subjecting the terbium block to hydrogen crushing treatment includes: subjecting the terbium block to hydrogen absorption reaction under the condition of hydrogen pressure of 0.1-0.5 MPa, and then evacuating and heating to 400-600° C. to carry out heat preservation dehydrogenation reaction for 2-6 hours.

3. The preparation method according to claim 1, characterized in that: The solid borane is selected from decaborane; And / or, the solvent is selected from terpineol and / or ethanol.

4. The preparation method according to claim 3, characterized in that: The step of ball-milling and mixing the terbium powder, solid borane, solvent and organic additive comprises: Mixing the poly-alpha olefin, the fatty acid methyl ester and the solvent to obtain a mixed solution; The terbium powder and the solid borane are added to the mixed solution and mixed by ball milling, and then the polyethyleneimine and the polyvinyl pyrrolidone are added and mixed evenly to obtain a slurry.

5. The preparation method according to any one of claims 1 to 4, characterized in that The amount of the organic additive added is 0.5-5% of the total weight of the terbium powder and the solid borane; And / or, the solid content of the slurry is 75-85%.

6. The preparation method according to any one of claims 1 to 4, characterized in that: The particle size of the terbium block is 40-60 mm; And / or, the particle size of the terbium powder is 3-10 μm.

7. The preparation method according to any one of claims 1 to 4, characterized in that: The degreasing treatment is performed in a vacuum atmosphere, at a temperature of 450-550°C, for a time of 6-12 hours; And / or, the sintering treatment is carried out in a vacuum atmosphere or an inert atmosphere, at a temperature of 1100-1200° C., for a time of 12-36 hours.

8. A terbium target material, characterized in that: The terbium target is prepared by the method for preparing the terbium target according to any one of claims 1 to 7; wherein the oxygen content of the terbium target is lower than 980 ppm and the relative density is higher than 98.5%.

9. A rare earth permanent magnet, characterized in that: It comprises a NdFeB magnet and a terbium metal layer deposited on the surface of the NdFeB magnet, wherein the terbium metal layer is obtained by sputtering and coating the terbium target material according to claim 8.

10. A new energy vehicle, comprising a motor, characterized in that: The motor comprises the rare earth permanent magnet according to claim 9.

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