Method for efficiently screening diffusant required by high-resistivity neodymium iron boron base material

Abstract

According to the method for efficiently screening the diffusant required by the high-resistivity neodymium-iron-boron base material, the diffusant with different components is coated on the neodymium-iron-boron rapid-hardening sheet, the diffusion rapid-hardening sheet is obtained after short-time diffusion heat treatment, the diffusant with the resistivity obviously improved is selected based on the influence of the diffusant on the resistivity of the rapid-hardening sheet, and the high-resistivity neodymium-iron-boron base material is obtained. And performing diffusion heat treatment on the neodymium-iron-boron base material with the same components by using the high-resistivity neodymium-iron-boron diffusion material to finally finish the preparation of the high-resistivity neodymium- According to the method, the diffusant with the resistivity obviously improved is efficiently screened out by diffusing the neodymium iron boron rapid hardening sheet, so that the research and development period of the diffusant is greatly shortened, and the research and development cost in the early stage is reduced. Besides, the resistivity of the neodymium-iron-boron magnet prepared by adopting the diffusant screened by the method is remarkably improved, the eddy-current loss of the neodymium-iron-boron magnet in the using process can be effectively reduced, and the temperature rise speed of the magnet under the dynamic working condition is reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of rare earth permanent magnet material preparation, and in particular to a method for efficiently screening diffusion agents required by high-resistivity neodymium-iron-boron substrates. BACKGROUND

[0002] The demand for neodymium-iron-boron permanent magnet materials is rapidly increasing in the fields of new energy vehicles, wind power generation, medical equipment, permanent magnet motors and the like, which puts forward higher requirements on the temperature stability of the neodymium-iron-boron permanent magnet materials. The resistivity of the neodymium-iron-boron magnet is relatively low, which leads to a relatively fast temperature rise of the magnet in the actual working process. Increasing the resistivity of the Nd-Fe-B magnet can effectively reduce the eddy current loss and reduce the working temperature rise of the magnet. Adding a high-resistivity auxiliary alloy through a double-alloy method can effectively increase the resistivity of the magnet, but reduces the volume fraction of the neodymium-iron-boron hard magnetic phase, which leads to a significant deterioration of the magnetic performance. Through the grain boundary diffusion treatment of the neodymium-iron-boron magnet by using a suitable diffusion medium, the coercivity of the magnet can be effectively enhanced, and the resistivity of the magnet can be improved, which is beneficial to improving the high-temperature working stability of the neodymium-iron-boron magnet.

[0003] There are many grades of neodymium-iron-boron, and the compositions of the magnets produced by different enterprises are complex and different. The composition of the diffusion source has a significant influence on the diffusion effect, and the composition of the diffusion source has a certain matching with the diffusion substrate. How to efficiently design the diffusion source matched with the diffusion magnet is one of the difficulties currently faced. The diffusion source is screened through the grain boundary diffusion test results of the sintered neodymium-iron-boron magnet, which has the defects of long diffusion process cycle and high trial and error cost. How to efficiently screen the diffusion agent suitable for different neodymium-iron-boron substrates has become one of the bottlenecks restricting the high-performance neodymium-iron-boron magnet. The phase composition and microstructure of the diffusion agent neodymium-iron-boron rapid solidification sheet are often inherited to the final sintered magnet, and are closely related to the magnetic performance and microstructure of the final magnet. The thickness of the rapid solidification sheet is small, and is in the micron level, and the rapid penetration of the diffusion source in the rapid solidification sheet can be realized in a short time. SUMMARY

[0004] The application aims at: the phase composition and microstructure of the neodymium-iron-boron rapid solidification sheet are often inherited to the final sintered magnet, and are closely related to the magnetic performance and microstructure of the final magnet; through the microstructure inheritance characteristics between the rapid solidification sheet and the sintered magnet and the rapid penetration advantage brought by the micron-level thickness, a large number of candidate diffusion agent formulations can be quickly and low-cost screened and evaluated in the early stage of research and development, reliable basis can be provided for subsequent directional and accurate verification tests on the preparation of high-magnetic-performance and high-resistivity neodymium-iron-boron diffusion magnets, and finally the efficient and low-consumption diffusion agent development goal can be achieved.

[0005] The application provides a method for efficiently screening diffusion agents required by high-resistivity neodymium-iron-boron substrates. The method comprises the following steps: S1. Using alloy rapid quenching and fling plate technology, prepare neodymium iron boron rapid quenching plate; S2. Hydrogen break, air flow mill, orientation forming and sintering of the neodymium iron boron rapid quenching plate to prepare neodymium iron boron base material; S3. Prepare diffusion agent with different components; S4. Select the diffusion agent to perform short time vacuum heat diffusion treatment on the neodymium iron boron rapid quenching plate to prepare neodymium iron boron diffusion rapid quenching plate; S5. Test the resistivity of the neodymium iron boron diffusion rapid quenching plate, and select the diffusion agent used for high resistivity neodymium iron boron rapid quenching plate; S6. Use the selected diffusion agent to perform vacuum heat diffusion treatment on the neodymium iron boron base material with the same component as the neodymium iron boron rapid quenching plate to obtain high resistivity neodymium iron boron diffusion magnet; The diffusion agent is R a M x alloy powder.

[0006] The diffusion agent R a M x alloy powder, a and x are atomic percentages of respective elements, a is greater than or equal to 70, and x is less than or equal to 30; R is a rare earth element, selected from one or more of Pr, Ce, La, Nd, Dy, Tb, Y, Ho, Gd, Sm, and Er; and M is a non-rare earth element, selected from one or more of Al, Cu, Ga, Co, Ni, Ti, Si, and Mg.

[0007] When the diffusion agent is added, the amount of the diffusion agent added accounts for 0% to 8% of the mass of the neodymium iron boron rapid quenching plate; and the amount of the diffusion agent added accounts for 0% to 8% of the mass of the neodymium iron boron magnet base material.

[0008] The amount of the diffusion agent added accounts for the same percentage of the mass of the neodymium iron boron rapid quenching plate and the mass of the neodymium iron boron magnet base material.

[0009] The vacuum heat diffusion treatment is performed at a vacuum degree of not less than 1×10 -3 Pa.

[0010] The diffusion temperature for the vacuum heat diffusion treatment of the neodymium iron boron diffusion rapid quenching plate is 890℃ to 940℃, the diffusion time is 0.3h to 1h, the tempering temperature is 480℃ to 520℃, and the tempering time is 2h to 4h; and the diffusion temperature for the vacuum heat diffusion treatment of the neodymium iron boron diffusion magnet is 890℃ to 940℃, the diffusion time is 4h to 12h, the tempering temperature is 480℃ to 520℃, and the tempering time is 2h to 4h.

[0011] The preparation method of the diffusion agent is: under the protection of pure argon, R a M xThe alloy ingot is cast, and strips and balls are prepared by melt rapid quenching and ball milling to obtain the particle size of the diffusion agent being less than or equal to 75 microns.

[0012] Advantages of the present application: The high-efficiency screening of the diffusion agent is realized, the diffusion treatment is performed on the neodymium-iron-boron rapid solidification sheet at the front end of production, the invalid or poor-performance diffusion agent is quickly eliminated at the front end of research and development, the diffusion agent with obvious performance improvement is screened out, the valuable research and development resources and time are concentrated on a few most potential schemes, and the diffusion agent is finally applied to the neodymium-iron-boron base material, the research and development process of the diffusion agent is greatly accelerated, and the early research and development cost is greatly reduced.

[0013] By adjusting the composition of the diffusion agent, R a M x The alloy diffusion agent successfully induces and forms a high-resistance rare earth oxide phase at the grain boundary of the neodymium-iron-boron rapid solidification sheet and the neodymium-iron-boron magnet, increases the resistance of the grain boundary phase, improves the resistivity of the neodymium-iron-boron magnet, effectively reduces the eddy current loss of the neodymium-iron-boron magnet in use, and reduces the temperature rising speed of the magnet under dynamic working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 Nd 23.32 Pr 6.63 Fe bal B 0.98 Cu 0.1 Al 0.18 Co 0.49 Ga 0.1 Zr 0.17 The micro-morphology diagram of the section of the neodymium-iron-boron rapid solidification sheet and the corresponding Nd, Pr, Al, Cu, Ga, O and Fe element distribution diagrams; Figure 2 Pr 50 Dy 20 Al 20 Cu 10 The micro-morphology diagram of the section of the diffusion rapid solidification sheet and the corresponding Dy, Nd, Pr, Al, Cu, Ga, O and Fe element distribution diagrams; Figure 3 Pr 50 Dy 20 Al 20 Cu 10 The BSE diagrams and the Dy, Nd, Pr, Al, Cu, Ga and Fe element distribution diagrams of the diffusion magnet A at depths of 50 microns, 100 microns and 500 microns; Figure 4 Pr 50 Dy 20 Al 10 Cu10 Ga 10 Conductive atomic force microscopy characterization results at the center of the cross section of the diffusion rapidly solidified piece; (a) topography distribution map, (b) current distribution map, (c) current line scan distribution map corresponding to Line 1.

[0015] Figure 5 Pr 50 Dy 20 Al 10 Cu 10 Ga 10 Conductive atomic force microscopy characterization results at the center of the cross section of the diffusion rapidly solidified piece; (a) topography distribution map, (b) current distribution map, (c) current line scan distribution map corresponding to Line 1. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the protection scope of the present application.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0018] The embodiments of the present application will be described in detail below with specific examples.

[0019] Example 1 An alloy rapid solidification technique is used to prepare a neodymium-iron-boron rapidly solidified piece according to the nominal composition Nd 23.32 Pr 6.63 Fe bal B 0.98 Cu 0.1 Al 0.18 Co 0.49 Ga 0.1 Zr 0.17 (by weight percentage, wherein bal represents the balance) is dosed, heated and melted into an alloy liquid, and then cast on a rotating copper roller to be spun into a neodymium-iron-boron rapidly solidified piece; the neodymium-iron-boron rapidly solidified piece is prepared into a neodymium-iron-boron base material through hydrogen breaking, airflow grinding, orientation forming and sintering technology.

[0020] The method comprises the following steps: (1) under the protection of pure argon, Pr 50Dy 20 Al 20 Cu 10 The alloy was ball-milled at a speed of 300 r / min for 3 h to obtain Pr with an average particle size of less than 75 μm. 50 Dy 20 Al 20 Cu 10 alloy powder; (2) The alloy dispersant Pr prepared above 50 Dy 20 Al 20 Cu 10 The powder is uniformly coated on the upper surface of the neodymium iron boron quick-setting sheet, resulting in a 2% increase in the weight of the coated quick-setting sheet; (3) Place the coated NdFeB rapid solidification sheet into a high vacuum diffusion furnace, and heat it at 1×10⁻⁶ ℃. -3 Under a vacuum of Pa, the neodymium iron boron diffusion rapid solidification sheet was obtained by vacuum heat diffusion treatment at 910℃ for 1 hour, tempering at 500℃ for 3 hours, and cooling to room temperature. (4) The resistivity of the prepared NdFeB diffusion-accelerated sheet was tested and analyzed; (5) The alloy dispersant Pr prepared above 50 Dy 20 Al 20 Cu 10 The powder was uniformly coated on the upper and lower surfaces of the neodymium iron boron magnet substrate in equal amounts, resulting in a 2% increase in the weight of the coated magnet. (6) Place the coated NdFeB magnet substrate into a high vacuum diffusion furnace, and at 1×10 -3 Under a vacuum of Pa, a neodymium iron boron diffused magnet was obtained by vacuum thermal diffusion treatment at 910°C for 6 hours, tempering at 500°C for 3 hours, and cooling to room temperature.

[0021] Example 2: Example 2 uses NdFeB rapid-setting sheets and NdFeB magnet substrates with the same composition as in Example 1. The method includes the following steps: (1) Pr was prepared by arc melting and rapid melt quenching under pure argon protection. 50 Dy 20 Al 10 Cu 10 Ga 10 The alloy was ball-milled at a speed of 300 r / min for 3 h to obtain Pr with an average particle size of less than 75 μm. 50 Dy 20 Al 10 Cu 10 Ga 10alloy powder; (2) The alloy dispersant Pr prepared above 50 Dy 20 Al 10 Cu 10 Ga 10 The powder is uniformly coated on the upper surface of the neodymium iron boron quick-setting sheet, resulting in a 2% increase in the weight of the coated quick-setting sheet; (3) Place the coated NdFeB rapid solidification sheet into a high vacuum diffusion furnace, and heat it at 1×10⁻⁶ ℃. -3 Under a vacuum of Pa, the neodymium iron boron diffusion rapid solidification sheet was obtained by vacuum heat diffusion treatment at 910℃ for 1 hour, tempering at 500℃ for 3 hours, and cooling to room temperature. (4) The resistivity of the prepared NdFeB diffusion-accelerated sheet was tested and analyzed; (5) The alloy dispersant Pr prepared above 50 Dy 20 Al 10 Cu 10 Ga 10 The powder was uniformly coated on the upper and lower surfaces of the neodymium iron boron magnet substrate in equal amounts, resulting in a 2% increase in the weight of the coated magnet. (6) Place the coated NdFeB magnet substrate into a high vacuum diffusion furnace, and at 1×10 -3 Under a vacuum of Pa, a neodymium iron boron diffused magnet was obtained by vacuum thermal diffusion treatment at 910°C for 6 hours, tempering at 500°C for 3 hours, and cooling to room temperature.

[0022] Example 3: Example 3 uses NdFeB rapid-setting sheets and NdFeB magnet substrates with the same composition as in Example 1. The method includes the following steps: (1) Pr was prepared by arc melting and rapid melt quenching under pure argon protection. 45 Dy 35 Al 20 The alloy was ball-milled at a speed of 300 r / min for 3 h to obtain Pr with an average particle size of less than 75 μm. 45 Dy 35 Al 20 alloy powder; (2) The alloy dispersant Pr prepared above 45 Dy 35 Al 20 The powder is uniformly coated on the upper surface of the neodymium iron boron quick-setting sheet, resulting in a 2% increase in the weight of the coated quick-setting sheet; (3) Place the coated NdFeB rapid solidification sheet into a high vacuum diffusion furnace, and heat it at 1×10⁻⁶ ℃. -3Under a vacuum of Pa, the neodymium iron boron diffusion rapid solidification sheet was obtained by vacuum heat diffusion treatment at 910℃ for 1 hour, tempering at 500℃ for 3 hours, and cooling to room temperature. (4) The resistivity of the prepared NdFeB diffusion-accelerated sheet was tested and analyzed; (5) The alloy dispersant Pr prepared above 45 Dy 35 Al 20 The powder was uniformly coated on the upper and lower surfaces of the neodymium iron boron magnet substrate in equal amounts, resulting in a 2% increase in the weight of the coated magnet. (6) Place the coated NdFeB magnet substrate into a high vacuum diffusion furnace, and at 1×10 -3 Under a vacuum of Pa, a neodymium iron boron diffused magnet was obtained by vacuum thermal diffusion treatment at 910°C for 6 hours, tempering at 500°C for 3 hours, and cooling to room temperature.

[0023] Example 4: Example 4 uses NdFeB rapid-setting sheets and NdFeB magnet substrates with the same composition as in Example 1. The method includes the following steps: (1) Ce was prepared by arc melting and rapid melt quenching under pure argon protection. 45 Dy 35 Al 20 The alloy was ball-milled at a speed of 300 r / min for 3 h to obtain Ce with an average particle size of less than 75 μm. 45 Dy 35 Al 20 alloy powder; (2) The alloy dispersant Ce prepared above 45 Dy 35 Al 20 The powder is uniformly coated on the upper surface of the neodymium iron boron quick-setting sheet, resulting in a 2% increase in the weight of the coated quick-setting sheet; (3) Place the coated NdFeB rapid solidification sheet into a high vacuum diffusion furnace, and heat it at 1×10⁻⁶ ℃. -3 Under a vacuum of Pa, the neodymium iron boron diffusion rapid solidification sheet was obtained by vacuum heat diffusion treatment at 910℃ for 1 hour, tempering at 500℃ for 3 hours, and cooling to room temperature. (4) The resistivity of the prepared NdFeB diffusion-accelerated sheet was tested and analyzed; (5) The alloy dispersant Ce prepared above 45 Dy 35 Al 20 The powder was uniformly coated on the upper and lower surfaces of the neodymium iron boron magnet substrate in equal amounts, resulting in a 2% increase in the weight of the coated magnet. (6) Place the coated NdFeB magnet substrate into a high vacuum diffusion furnace, and at 1×10 -3 Under a vacuum of Pa, a neodymium iron boron diffused magnet was obtained by vacuum thermal diffusion treatment at 910°C for 6 hours, tempering at 500°C for 3 hours, and cooling to room temperature.

[0024] The performance results of the NdFeB diffusion-accelerated sheet are shown in Table 1.

[0025] Table 1: The performance results of the neodymium iron boron diffused magnets are shown in Table 2.

[0026] Table 2: Analysis of the data in Tables 1 and 2 shows that the influence of the dispersant on the resistivity of the quick-setting sheet is consistent with the trend of its influence on the magnet substrate, thus enabling rapid and efficient screening of the dispersant.

[0027] Example 5: Using alloy rapid solidification flake technology, according to the nominal composition Nd 19.40 Pr 6.46 Ce 1.93 Fe bal B 1.09 Cu 0.15 Co 0.3 Ga 0.2 2Zr 0.18 (In weight percent, where bal represents the balance) The ingredients are batched, heated and melted into an alloy liquid, and then poured onto a rotating copper roller to form NdFeB rapid-solidification sheets; the NdFeB rapid-solidification sheets are then processed through hydrogen blasting, air jet milling, orientation forming, and sintering techniques to prepare NdFeB magnet substrates. The method includes the following steps: (1) Pr was prepared by arc melting and rapid melt quenching under pure argon protection. 35 Dy 35 Al 20 Cu 10 The alloy was ball-milled at a speed of 300 r / min for 3 h to obtain Pr with an average particle size of less than 75 μm. 35 Dy 35 Al 20 Cu 10 alloy powder; (2) The alloy dispersant Pr prepared above 35 Dy 35 Al 20 Cu 10 The powder is uniformly coated on the upper surface of the neodymium iron boron quick-setting sheet, resulting in a 2% increase in the weight of the coated quick-setting sheet; (3) Place the coated NdFeB rapid solidification sheet into a high vacuum diffusion furnace, and heat it at 1×10⁻⁶ ℃. -3 Under a vacuum of Pa, the neodymium iron boron diffusion rapid solidification sheet was obtained by vacuum heat diffusion treatment at 910℃ for 1 hour, tempering at 500℃ for 3 hours, and cooling to room temperature. (4) The resistivity of the prepared NdFeB diffusion-accelerated sheet was tested and analyzed; (5) The alloy dispersant Pr prepared above 35 Dy 35 Al 20 Cu 10 The powder was uniformly coated on the upper and lower surfaces of the neodymium iron boron magnet substrate in equal amounts, resulting in a 2% increase in the weight of the coated magnet. (6) Place the coated NdFeB magnet substrate into a high vacuum diffusion furnace, and at 1×10 -3 Under a vacuum of Pa, a neodymium iron boron diffused magnet was obtained by vacuum thermal diffusion treatment at 910°C for 6 hours, tempering at 500°C for 3 hours, and cooling to room temperature.

[0028] Example 6: Example 6 The method uses NdFeB rapid-setting sheets and NdFeB magnet substrates with the same composition as in Example 5. The method includes the following steps: (1) Pr was prepared by arc melting and rapid melt quenching under pure argon protection. 50 Dy 20 Al 10 Ga 20 The alloy was ball-milled at a speed of 300 r / min for 3 h to obtain Pr with an average particle size of less than 75 μm. 50 Dy 20 Al 10 Ga 20 alloy powder; (2) The alloy dispersant Pr prepared above 50 Dy 20 Al 10 Ga 20 The powder is uniformly coated on the upper surface of the neodymium iron boron quick-setting sheet, resulting in a 2% increase in the weight of the coated quick-setting sheet; (3) Place the coated NdFeB rapid solidification sheet into a high vacuum diffusion furnace, and heat it at 1×10⁻⁶ ℃. -3 Under a vacuum of Pa, the neodymium iron boron diffusion rapid solidification sheet was obtained by vacuum heat diffusion treatment at 910℃ for 1 hour, tempering at 500℃ for 3 hours, and cooling to room temperature. (4) The resistivity of the prepared NdFeB diffusion-accelerated sheet was tested and analyzed; (5) The alloy dispersant Pr prepared above 50 Dy 20 Al 10 Ga 20 The powder was uniformly coated on the upper and lower surfaces of the neodymium iron boron magnet substrate in equal amounts, resulting in a 2% increase in the weight of the coated magnet. (6) Place the coated NdFeB magnet substrate into a high vacuum diffusion furnace, and at 1×10 -3 Under a vacuum of Pa, a neodymium iron boron diffused magnet was obtained by vacuum thermal diffusion treatment at 910°C for 6 hours, tempering at 500°C for 3 hours, and cooling to room temperature.

[0029] Example 7: Example 7 The method uses NdFeB rapid-setting sheets and NdFeB magnet substrates with the same composition as in Example 5. The method includes the following steps: (1) Pr was prepared by arc melting and rapid melt quenching under pure argon protection. 35 Dy 35 Cu 10 Ga 20 The alloy was ball-milled at a speed of 300 r / min for 3 h to obtain Pr with an average particle size of less than 75 μm. 35 Dy 35 Cu 10 Ga 20 alloy powder; (2) The alloy dispersant Pr prepared above 35 Dy 35 Cu 10 Ga 20 The powder is uniformly coated on the upper surface of the neodymium iron boron quick-setting sheet, resulting in a 2% increase in the weight of the coated quick-setting sheet; (3) Place the coated NdFeB rapid solidification sheet into a high vacuum diffusion furnace, and heat it at 1×10⁻⁶ ℃. -3 Under a vacuum of Pa, the neodymium iron boron diffusion rapid solidification sheet was obtained by vacuum heat diffusion treatment at 910℃ for 1 hour, tempering at 500℃ for 3 hours, and cooling to room temperature. (4) The resistivity of the prepared NdFeB diffusion-accelerated sheet was tested and analyzed; (5) The alloy dispersant Pr prepared above 35 Dy 35 Cu 10 Ga 20 The powder was uniformly coated on the upper and lower surfaces of the neodymium iron boron magnet substrate in equal amounts, resulting in a 2% increase in the weight of the coated magnet. (6) Place the coated NdFeB magnet substrate into a high vacuum diffusion furnace, and at 1×10-3 Under a vacuum of Pa, a neodymium iron boron diffused magnet was obtained by vacuum thermal diffusion treatment at 910°C for 6 hours, tempering at 500°C for 3 hours, and cooling to room temperature.

[0030] The performance results of the NdFeB diffusion-accelerated sheets are shown in Table 3.

[0031] Table 3: The performance results of the NdFeB diffusion velocity magnet are shown in Table 4.

[0032] Table 4: A comparative analysis of the data in Tables 3 and 4 shows that the resistivity variation pattern of NdFeB rapid solidification sheets is consistent with the resistivity variation trend of NdFeB diffused magnets of the same composition.

[0033] In summary, the data analysis above demonstrates that this application provides a highly efficient method for screening dispersants required for high-resistivity NdFeB substrates, effectively overcoming the inherent drawbacks of traditional diffusion experiments on sintered magnets, such as long development cycles, high costs, and low efficiency. By performing diffusion treatment on NdFeB rapid-solidifying sheets at the R&D stage, rapid prediction and efficient screening of the effects of various dispersants are achieved. This method significantly shortens the development cycle of high-performance dispersants and substantially reduces the time and economic costs of early-stage R&D.

[0034] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for efficiently screening dispersants required for high resistivity NdFeB substrates, characterized in that, The method includes the following steps: S1. Neodymium iron boron rapid-setting flakes were prepared using alloy rapid-setting flake technology; S2. The neodymium iron boron rapid solidification sheet is hydrogen-broken, air-jet milled, oriented and sintered to prepare a neodymium iron boron substrate; S3. Preparation of dispersants with different compositions; S4. The neodymium iron boron rapid-setting sheet is subjected to a short-time vacuum thermal diffusion treatment using the aforementioned dispersant to prepare a neodymium iron boron diffusion rapid-setting sheet; S5. Test the resistivity of the NdFeB diffusion-accelerated sheet and select the diffusion agent for high resistivity NdFeB diffusion-accelerated sheets; S6. Using a selected diffusing agent, a NdFeB substrate with the same composition as the NdFeB rapid-curing sheet is subjected to vacuum thermal diffusion treatment to obtain a high-resistivity NdFeB diffused magnet; Wherein, the dispersant is R a M x alloy powder.

2. The method for efficiently screening dispersants required for high resistivity NdFeB substrates according to claim 1, characterized in that, The diffusing agent R a M x Alloy powder, where a and x are the atomic percentages of their respective elements, a≥70, x≤30; R is a rare earth element, selected from one or more elements among Pr, Ce, La, Nd, Dy, Tb, Y, Ho, Gd, Sm, and Er; M is a non-rare earth element, selected from one or more elements among Al, Cu, Ga, Co, Ni, Ti, Si, and Mg.

3. The method for efficiently screening dispersants required for high resistivity NdFeB substrates according to claim 1, characterized in that, When the dispersant is added, the amount of the dispersant added accounts for 0% to 8% of the mass of the NdFeB rapid-curing sheet; the amount of the dispersant added accounts for 0% to 8% of the mass of the NdFeB magnet substrate.

4. The method for efficiently screening dispersants required for high resistivity NdFeB substrates according to claim 3, characterized in that, The amount of the dispersant added is kept consistent as a percentage of the mass of the NdFeB rapid-setting sheet and the mass of the NdFeB magnet substrate.

5. The method for efficiently screening dispersants required for high resistivity NdFeB substrates according to claim 1, characterized in that, The vacuum thermal diffusion treatment is at a temperature of not less than 1×10⁻⁶. -3 The procedure was carried out under a vacuum of Pa.

6. The method for efficiently screening dispersants required for high resistivity NdFeB substrates according to claim 1, characterized in that, The diffusion temperature for vacuum thermal diffusion treatment of NdFeB diffusion fast-setting sheets is 890℃~940℃, the diffusion time is 0.3h~1h, the tempering temperature is 480℃~520℃, and the tempering time is 2h~4h; the diffusion temperature for vacuum thermal diffusion treatment of NdFeB diffusion magnets is 890℃~940℃, the diffusion time is 4h~12h, the tempering temperature is 480℃~520℃, and the tempering time is 2h~4h.

7. The method for efficiently screening dispersants required for high resistivity NdFeB substrates according to claim 1, characterized in that, The dispersant is prepared by means of: R under pure argon protection, through melting, rapid melt quenching, and ball milling. a M x The particle size of the alloy powder and dispersant powder is ≤ 75 μm.

8. The method for efficiently screening dispersants required for high resistivity NdFeB substrates according to claim 6, characterized in that, Instead of using high-temperature, long-duration diffusion on NdFeB substrates to screen dispersants, suitable powder dispersants can be screened through short-time diffusion on NdFeB rapid-condensation sheets. This effectively shortens the development cycle of dispersants required to improve the resistivity of NdFeB magnets and achieves efficient screening of dispersants with different compositions for NdFeB magnets.

9. The method for efficiently screening dispersants required for high resistivity NdFeB substrates according to claim 8, characterized in that, The term "long time" refers to a duration of 4 hours or more, and the term "short time" refers to a duration of 1 hour or less.

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