Neodymium-iron-boron magnet, and preparation method therefor and use thereof

Abstract

Disclosed in the present invention are a neodymium-iron-boron magnet, and a preparation method therefor and the use thereof. The neodymium-iron-boron magnet comprises an invulnerable-to-demagnetization region, a transition region and a vulnerable-to-demagnetization region, wherein the ratio of the content of Tb in the transition region to the content of Tb in the vulnerable-to-demagnetization region is (0.5-0.96):1; the ratio of the content of Tb in the transition region to the content of Tb in the invulnerable-to-demagnetization region is 1 : (0-0.93); the ratio of the content of Dy in the transition region to the content of Dy in the vulnerable-to-demagnetization region is 1:1; and the ratio of the content of Dy in the transition region to the content of Dy in the invulnerable-to-demagnetization is 1:1. The neodymium-iron-boron magnet has a good anti-demagnetization capability.

Description

Neodymium-iron-boron magnet, preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to a neodymium-iron-boron magnet, a preparation method and application thereof. BACKGROUND

[0002] Since the advent of neodymium-iron-boron permanent magnet, it has been widely used in the fields of automobile, wind power, household appliances, industrial robots, etc. Due to different working conditions in different fields, the performance of the product magnetic steel in the field is also required to be different. In recent years, new energy vehicles have developed rapidly, and the demand for magnetic steel of main drive motor has increased dramatically. Since the normal working temperature of the main drive motor mainly concentrates in the range of 120-180℃, the neodymium-iron-boron needs higher coercivity and thermal stability. In order to improve the temperature resistance of rare earth permanent magnet, a large amount of heavy rare earth Dy and Tb is usually added to increase the anisotropic field of the main phase magnetic crystal. However, the heavy rare earth resources are scarce and expensive, which seriously restricts the application of neodymium-iron-boron magnet in various industries.

[0003] With the increasing demand for high-performance magnets, the grain boundary diffusion technology has gradually been known and accepted by everyone. The conventional grain boundary diffusion technology adopts a physical vapor deposition method to deposit the diffusion source on the surface of the magnet, and then penetrates the diffusion source into the magnet along the grain boundary under high temperature and certain pressure. The biggest advantage of this technology is that it can greatly improve the coercivity using a small amount of heavy rare earth while keeping the remanence almost unchanged.

[0004] In terms of effective utilization rate of heavy rare earth, the traditional grain boundary diffusion product has been greatly improved compared with the non-grain boundary diffusion product. However, in order to further improve the utilization rate of heavy rare earth and reduce unnecessary waste of heavy rare earth, and to make the diffusion area more accurate and evaluate, another purpose of the present application is to identify the easy demagnetization and non-easy demagnetization areas by means of electromagnetic simulation of neodymium-iron-boron under the working condition of the main drive motor. We found that the easy demagnetization area appears near the rotor air gap corner, and the demagnetization is not obvious near the rotor and the middle area of the magnetic steel. Therefore, for the easy demagnetization area, high-performance magnets with the same remanence are bonded with low-performance magnets with the same remanence in the non-easy demagnetization area to prepare the required combined magnet, thereby saving the heavy rare earth in the non-easy demagnetization area.

[0005] In the actual use of neodymium-iron-boron, the performance requirements of each part of the magnet are not the same. For example, in the motor, due to the non-uniform magnetic field generated by the reverse magnetic field after the coil is energized in the motor, there will be easy demagnetization area, non-easy demagnetization area and transition area between the easy demagnetization area and the non-easy demagnetization area. Due to the characteristics of the performance of the above-mentioned areas, the coercivity of each area needs to achieve a matching relationship to ensure that the coercivity of the easy demagnetization area and the transition area is the same, the non-easy demagnetization area does not appear the decay of surface magnet and magnetic flux, and the remanence of the transition area and the non-easy demagnetization area is the highest, so as to realize the best cost performance of high-grade such as 48UH. SUMMARY

[0006] The present application provides a neodymium-iron-boron magnet, a preparation method and application thereof, and the neodymium-iron-boron magnet has excellent demagnetization resistance.

[0007] The present application mainly solves the above technical problems through the following technical solutions.

[0008] The present application provides a neodymium-iron-boron magnet, a preparation method and application thereof, and the neodymium-iron-boron magnet has excellent demagnetization resistance.

[0009] The neodymium-iron-boron magnet comprises a non-easy demagnetization area, a transition area and an easy demagnetization area; the easy demagnetization area is an annular area on the upper surface of the neodymium-iron-boron magnet along the Z-axis direction, and the non-easy demagnetization area is a central area on the upper surface of the neodymium-iron-boron magnet along the Z-axis direction; the transition area is an interface area between the easy demagnetization area and the non-easy demagnetization area.

[0010] The content ratio of Tb in the transition area to the easy demagnetization area is (0.5-0.96):1;

[0011] The content ratio of Tb in the transition area to the non-easy demagnetization area is 1:(0-0.93);

[0012] The content ratio of Dy in the transition area to the easy demagnetization area is 1:1;

[0013] The content ratio of Dy in the transition area to the non-easy demagnetization area is 1:1.

[0014] In the present application, the heavy rare earth elements can be derived from the substrate and / or the diffusion process, and preferably from the diffusion process.

[0015] In the present application, the content of heavy rare earth refers to the percentage of the mass of heavy rare earth in a certain area in the total mass of the magnet in the area, for example, the content of Tb in the first easy demagnetization area refers to the percentage of the mass of Tb in the first easy demagnetization area in the total mass of the magnet in the first easy demagnetization area.

[0016] In the present application, the diffusion weight gain of heavy rare earth refers to the percentage of the mass of heavy rare earth introduced by diffusion in a certain area in the total mass of the magnet in the area, for example, the diffusion weight gain of Tb in the first easy demagnetization area refers to the percentage of the mass of Tb introduced by diffusion in the first easy demagnetization area in the total mass of the magnet in the first easy demagnetization area.

[0017] In the present application, the specific position of the upper surface is not limited, and those skilled in the art can generally understand that the upper surface refers to the surface opposite to the plane when the magnet is placed on the plane.

[0018] In the present application, preferably, the content ratio of Tb in the transition zone to the Tb in the easy demagnetization zone is (0.5-0.9):1, for example, 0.79:1 or 0.8:1.

[0019] In the present application, preferably, the diffusion weight gain ratio of Tb in the transition zone to the Tb in the easy demagnetization zone is (0.5-0.9):1, more preferably (0.5-0.8):1, for example, 0.79:1 or 0.8:1.

[0020] In the present application, preferably, the content ratio of Tb in the transition zone to the Tb in the non-easy demagnetization zone is 1:(0-0.2), for example, 1:0.02, 1:0.04 or 1:0.05.

[0021] In the present application, preferably, the diffusion weight gain ratio of Tb in the transition zone to the Tb in the non-easy demagnetization zone is 1:(0-0.2), for example, 1:0.02 or 1:0.04.

[0022] In the present application, preferably, the content ratio of Tb in the easy demagnetization zone to the Tb in the non-easy demagnetization zone is 1:(0-0.9), more preferably 1:(0-0.5), and further more preferably 1:(0-0.2), for example, 1:0.02, 1:0.03 or 1:0.04.

[0023] In the present application, preferably, the diffusion weight gain ratio of Tb in the easy demagnetization zone to the Tb in the non-easy demagnetization zone is 1:(0-0.9), more preferably 1:(0-0.5), and further more preferably 1:(0-0.2), for example, 1:0.02, 1:0.03 or 1:0.04.

[0024] In the present application, preferably, the diffusion weight gain ratio of Dy in the easy demagnetization zone to the Dy in the non-easy demagnetization zone is 1:1.

[0025] In the present application, preferably, the diffusion weight gain of Tb in the easy demagnetization zone is gradiently distributed along the X axis.

[0026] In the present application, preferably, the diffusion weight gain of Tb in the transition zone is gradiently distributed along the X axis.

[0027] In the present application, preferably, the diffusion weight gain of Tb in the non-easy demagnetization zone is gradiently distributed along the X axis.

[0028] In the present application, preferably, the content of Tb in the easy demagnetization region is 0.1wt%-2.5wt%, more preferably 0.25wt%-1wt%, further more preferably 0.25wt%-0.6wt%, for example 0.55wt%, 0.58wt% or 0.6wt%.

[0029] In the present application, preferably, the diffusion weight gain of Tb in the easy demagnetization region is 0.1wt%-2.5wt%, more preferably 0.25wt%-1wt%, further more preferably 0.25wt%-0.6wt%, for example 0.55wt%, 0.58wt% or 0.6wt%.

[0030] In the present application, preferably, the content of Tb in the non-easy demagnetization region is 0-1.6wt%, more preferably 0-0.5wt%, further more preferably 0-0.05wt%, for example 0.01wt%, 0.02wt% or 0.022wt%.

[0031] In the present application, preferably, the diffusion weight gain of Tb in the non-easy demagnetization region is 0-1.6wt%, more preferably 0-0.5wt%, further more preferably 0-0.05wt%, for example 0.01wt%, 0.02wt% or 0.022wt%.

[0032] In the present application, preferably, the content of Tb in the transition region is 0.1wt%-2.4wt%, more preferably 0.125wt%-1wt%, for example 0.24wt%, 0.36wt%, 0.38wt%, 0.44wt%, 0.46wt% or 0.48wt%.

[0033] In the present application, preferably, the diffusion weight gain of Tb in the transition region is 0.1wt%-2.4wt%, more preferably 0.125wt%-1wt%, for example 0.24wt%, 0.36wt%, 0.38wt%, 0.44wt%, 0.46wt% or 0.48wt%.

[0034] In the present application, preferably, the content of Dy in the easy demagnetization region is 0.1wt%-4wt%, for example 2.2wt%.

[0035] In the present application, preferably, the diffusion weight gain of Dy in the easy demagnetization region is 0-0.8wt%, more preferably 0.2wt%-0.6wt%.

[0036] In the present application, preferably, the content of Dy in the non-easy demagnetization region is 0.1wt%-4wt%, for example 2.2wt%.

[0037] In the present application, preferably, the diffusion weight gain of Dy in the non-remanence easy region is 0-0.8wt%, more preferably 0.2wt%-0.6wt%.

[0038] In the present application, preferably, the content of Dy in the transition region is 0.1wt%-4wt%, for example 0.45wt% or 2.2wt%.

[0039] In the present application, preferably, the diffusion weight gain of Dy in the transition region is 0-0.8wt%, for example 0.6wt%.

[0040] In the present application, the coercivity of the non-remanence easy region and the non-remanence easy region is preferably 1:(0.7-0.96), more preferably 1:(0.8-0.97), for example 1:0.875, 1:0.946 or 1:0.907.

[0041] In some embodiments, the shape of the non-remanence easy region is rectangular in any plane perpendicular to the orientation direction.

[0042] In some embodiments, the neodymium-iron-boron magnet is a cuboid.

[0043] In some embodiments, the shape of the non-remanence easy region is rectangular in any plane perpendicular to the orientation direction.

[0044] In the present application, the ratio of the length to the thickness of the neodymium-iron-boron magnet is preferably (3-25):1, more preferably (3.64-24.27):1, further more preferably (8.74-24.27):1, for example 12.85:1; the length refers to the extension distance of one side of the upper surface along the positive direction of the X axis; the thickness refers to the extension distance of the cuboid from the upper surface along the positive direction of the Z axis.

[0045] In the present application, preferably, the thickness of the neodymium-iron-boron magnet is ≥5mm.

[0046] In the present application, preferably, the width of the non-remanence easy region is 0-6mm and not 0, more preferably 3-5mm; the width refers to the length covered by the non-remanence easy region along the direction perpendicular to the periphery at the origin.

[0047] In the present application, the volume percentage of the non-remanence easy region to the volume of the neodymium-iron-boron magnet is preferably 20%-80%, more preferably 29%-70%, for example 54.6% or 42.48%.

[0048] In the present application, the volume percentage of the transition region to the volume of the neodymium-iron-boron magnet is preferably 5%-15%, more preferably 10%-15%, further more preferably 10.6%-13.65%.

[0049] In the present application, the volume percentage of the non-reversible magnetization area in the volume of the Nd-Fe-B magnet is preferably 20%-80%, more preferably 24.18%-70.66%, and further more preferably 34.27%-57.5%.

[0050] In the present application, the Nd-Fe-B magnet can be represented by the chemical formula R1-R2-T-B-M, wherein R1 includes one or more of Pr, Nd, Ce, Er, Tm, Y, Lu, Gd and Ho; R2 is Dy and / or Tb; T includes one or more of Zn, Si, V, Cr, Mn, Ni, Ge, Ti, Nb, Mo, Pd, Ag, Cd, Sb, Hf, Ta, W, O, C, N, S, F and P; and M elements include one or more of Cu, Al, Co, Ga, Zr and Ti.

[0051] In some embodiments, the M elements are all from the Nd-Fe-B base material.

[0052] In other embodiments, the M elements include diffusively introduced M elements, wherein the diffusively introduced M elements preferably account for 0%-0.4% of the mass percentage of the Nd-Fe-B magnet.

[0053] In some preferred embodiments of the present application, the grain boundary structure of the Nd-Fe-B magnet includes Re2Fe 14 B main phase grains and Re-rich phase grain boundaries; the Re2Fe 14 B main phase grains include a core layer and a shell layer; and the Re is Dy and / or Tb. The Re2Fe 14 B main phase grains, the meaning of the shell layer is the conventional meaning in the art, i.e. (Nd, Re)2Fe 14 B hard magnetic layer; and the meaning of the Re-rich phase grain boundary is the conventional meaning in the art, i.e. a two-particle grain boundary region with Re>95%.

[0054] Preferably, the Re2Fe14B main phase grains of the reversible magnetization area sequentially include a core layer, a first shell layer and a second shell layer from inside to outside, the first shell layer is a (Nd, Tb)2Fe14B hard magnetic layer, and the second shell layer is a (Nd, Dy)2Fe14B hard magnetic layer.

[0055] In the present application, the non-reversible magnetization area, the transition area and the reversible magnetization area can preferably be obtained through a simulation cloud map under working conditions.

[0056] The present application also provides a preparation method of the above Nd-Fe-B magnet, which includes the following steps: applying a first diffusion source on four non-oriented surfaces of a Nd-Fe-B base material, applying a second diffusion source on at least one oriented surface of the Nd-Fe-B base material, and performing grain boundary diffusion treatment on the Nd-Fe-B base material with the diffusion sources applied.

[0057] the orientation surface is a surface of the Nd-Fe-B substrate perpendicular to the orientation direction, and the non-orientation surface is a surface of the Nd-Fe-B substrate parallel to the orientation direction;

[0058] the first diffusion source contains Tb, and the second diffusion source contains Dy.

[0059] The preparation method of the present application can exert diffusion sources on the orientation surface and the non-orientation surface according to the application working conditions of partial type motors and the distribution of easy demagnetization zones, so that the Nd-Fe-B magnet has excellent anti-demagnetization ability during use.

[0060] In the present application, it is known to those skilled in the art that Dy or Tb in the diffusion source is not completely diffused into the magnet during grain boundary diffusion, and the utilization rate is generally 85%-95%, so that a larger amount of Dy or Tb is generally applied in the actual preparation process.

[0061] In some preferred embodiments of the present application, the second diffusion source is applied to two orientation surfaces of the Nd-Fe-B substrate.

[0062] In some preferred embodiments of the present application, the first diffusion source does not contain Dy.

[0063] In some preferred embodiments of the present application, the second diffusion source does not contain Tb.

[0064] In some specific embodiments of the present application, the first diffusion source is elemental Tb.

[0065] In other embodiments of the present application, the first diffusion source is a Tb-M alloy, and M contains one or more of Cu, Al, Co, Ga, Zr and Ti. Among them, the mass percentage of M in the Tb-M is preferably 0-40%, and is not 0.

[0066] In other embodiments of the present application, the first diffusion source is a hydride of Tb or a fluoride of Tb.

[0067] In some specific embodiments of the present application, the second diffusion source is elemental Dy.

[0068] In other embodiments of the present application, the second diffusion source is a Dy-M alloy, and M contains one or more of Cu, Al, Co, Ga, Zr and Ti. Among them, the mass percentage of M in the Dy-M is preferably 0-40%, and is not 0.

[0069] In other embodiments of the present application, the second diffusion source is a hydride of Dy or a fluoride of Dy.

[0070] In the present application, preferably, the mass percentage of Tb in the first diffusion source is 0.25%-0.75%, more preferably 0.3%-0.75%.

[0071] In the present application, preferably, the mass percentage of Dy in the second diffusion source is 0.25%-0.75%.

[0072] In the present application, the application mode can be performed by conventional methods in the art, for example, coating.

[0073] In the present application, it is generally known to those skilled in the art that different grain boundary diffusion methods will have different coating thicknesses when the same amount of Dy or Tb is diffused into the magnet, therefore, the coating thickness is not limited in the present application, as long as the corresponding diffusion weight gain is achieved.

[0074] Preferably, the coating method is spraying or printing.

[0075] Preferably, the dewaxing temperature of the spraying is 200-400℃.

[0076] Preferably, the dewaxing temperature of the printing is 100-500℃.

[0077] In some embodiments of the present application, when the first diffusion source and the second diffusion source are applied by the coating method, the first diffusion source and the second diffusion source further comprise a solvent and a binder.

[0078] Preferably, the solvent is conventional in the art, for example, water, alcohol, ketone or ester.

[0079] In the present application, preferably, the grain boundary diffusion temperature is 750-950℃, for example, 900℃.

[0080] In the present application, preferably, the grain boundary diffusion time is 5-30h, for example, 10h.

[0081] In the present application, preferably, the grain boundary diffusion is followed by aging treatment.

[0082] Preferably, the aging treatment temperature is 300-600℃, for example, 500℃.

[0083] Preferably, the aging treatment time is 1-10h, for example, 3h.

[0084] The present application also provides a neodymium-iron-boron magnet prepared by the preparation method of the neodymium-iron-boron magnet.

[0085] The present application also provides the use of the neodymium-iron-boron magnet in a magnetic steel.

[0086] The above-mentioned preferred conditions can be combined arbitrarily to obtain preferred examples of the present application.

[0087] The reagents and raw materials used in the present application are commercially available.

[0088] The positive progress effect of the present application is that:

[0089] The neodymium-iron-boron magnet described in the present application comprises a transition zone, and by controlling the content of Tb and Dy introduced by diffusion in the transition zone, the easy demagnetization zone and the non-easy demagnetization zone, and the diffusion direction, the problem of the performance of the interface zone presenting a gradient decline and causing the demagnetization resistance effect to weaken due to the cross-zone interdiffusion of Tb or Dy caused by the difference in the Tb concentration gradient of the transition zone can be reduced, the decay of the surface magnetism and magnetic flux of the neodymium-iron-boron magnet can be reduced under the premise of ensuring the remanence of the neodymium-iron-boron magnet, and the demagnetization resistance of the neodymium-iron-boron magnet can be improved. In addition, the easy demagnetization zone, the non-easy demagnetization zone and the transition zone are all rectangular, which can improve the demagnetization resistance of the four long sides of the neodymium-iron-boron magnet. BRIEF DESCRIPTION OF DRAWINGS

[0090] Fig. 1 is a schematic diagram of the structure of the neodymium-iron-boron magnet of Example 1.

[0091] Fig. 2 is a schematic diagram of the microstructure of the easy demagnetization zone of Example 1.

[0092] The reference signs are as follows: 1-non-easy demagnetization zone; 2-transition zone; 3-easy demagnetization zone; 301-core layer; 302-first shell layer; 303-second shell layer. DETAILED DESCRIPTION

[0093] The present application will be further described by way of examples, but the present application is not limited to the examples described. The experimental methods in the following examples are not specified, and are selected according to conventional methods and conditions, or according to the instructions of the goods.

[0094] Examples 1-3

[0095] The neodymium-iron-boron magnet provided in Examples 1-3 is a rectangular parallelepiped, as shown in Fig. 1, and a three-dimensional rectangular coordinate system is established, wherein the orientation direction is the positive direction of the Z axis, the X axis is parallel to one side of the upper surface, and the origin of the three-dimensional rectangular coordinate system is located inside the neodymium-iron-boron magnet;

[0096] The neodymium-iron-boron magnet comprises a non-easy demagnetization zone 1, a transition zone 2 and an easy demagnetization zone 3; the easy demagnetization zone is a ring-shaped region located on the outer edge of the neodymium-iron-boron magnet along the Z axis direction, and the non-easy demagnetization zone is a central region located on the neodymium-iron-boron magnet along the Z axis direction; the transition zone is an interface region located between the easy demagnetization zone and the non-easy demagnetization zone;

[0097] wherein the Re2Fe 14 The structure of the B main phase grain is shown in FIG. 2, which comprises a core layer 301, a first shell layer 302 and a second shell layer 303 from inside to outside, the first shell layer is (Nd, Tb)2Fe 14 B hard magnetic layer, and the second shell layer is (Nd, Dy)2Fe 14 B hard magnetic layer;

[0098] The diffusion weight gain of each region is listed in Table 1, wherein the content of Tb in the substrate is 0, so the content of Tb in Examples 1-3 is equal to the diffusion weight gain thereof; the content of Dy in each region is listed in Table 1; the volume ratio of each region is listed in Table 2.

[0099] Table 1

[0100] Table 1

[0101] Table 2

[0102] Table 3

[0103] The preparation method of Examples 1-3 is that a first diffusion source is applied on four non-oriented surfaces of the neodymium iron boron substrate, a second diffusion source is applied on two oriented surfaces of the neodymium iron boron substrate, and the neodymium iron boron substrate to which the diffusion source is applied is subjected to grain boundary diffusion treatment; the oriented surface is the surface of the neodymium iron boron substrate perpendicular to the orientation direction, and the non-oriented surface is the surface of the neodymium iron boron substrate parallel to the orientation direction; the first diffusion source contains elemental Tb and does not contain Dy, and the second diffusion source contains elemental Dy and does not contain Tb; the element mass content of the neodymium iron boron substrate used in Examples 1-3 is listed in Table 3.

[0104] The temperature of the grain boundary diffusion is 900°C; the time of the grain boundary diffusion is 10h; the grain boundary diffusion is further followed by aging treatment; wherein the temperature of the aging treatment is 500°C; wherein the time of the aging treatment is 3h; the application mode is, for example, coating; wherein the coating mode is spraying, and the dewaxing temperature of the spraying is 200°C.

[0105] Effect Example 1

[0106] The neodymium iron boron magnets of Examples 1-3 are subjected to the following tests:

[0107] 1. Coercivity test: The samples of Examples 1-3 are prepared with the specification of W2-3±0.1*L19±0.1*T4±0.1mm, two pieces are stacked for measurement, and a coil with the size of W3*L19-20*T2.7mm is used to measure the permanent magnet in the permanent magnet precision measurement system NIM-62000 at room temperature (temperature ≤200℃).

[0108] 2. Demagnetization rate test: An electromagnetic simulation software, model Ansys Workbench, is used to input the speed of 13000rmp, and then adjust the temperature to the corresponding temperature working condition, collect the back electromotive force data of the motor under the same time and observe the change of the magnetic steel cloud map to identify whether the magnetic steel demagnetizes. The calculation formula of demagnetization rate is: demagnetization rate = (high-temperature back electromotive force- room-temperature back electromotive force) / room-temperature back electromotive force.

[0109] 3. The test method and test instrument of line scanning are as follows: the selected area of the magnet surface is microphotographed under the equipment EMMA, the equipment model is JEOL 8530f, the shooting magnification is X3000, and the line scanning of two main phases is performed to represent the distribution of elements such as Dy / Nd.

[0110] The technical effects of Examples 1-3 are listed in Table 4 below:

[0111] Table 4

[0112] As shown in Table 4 above, the coercivity ratio of the easy demagnetization zone and the transition zone of the neodymium-iron-boron magnets prepared in Examples 1-3 is between 1:(0.93-0.98), the coercivity difference between the easy demagnetization zone and the non-easy demagnetization zone is between 0-3.5kOe, and the magnets have excellent demagnetization resistance. The demagnetization rate of the neodymium-iron-boron magnets of Examples 1-3 at 160℃ is only 0.9%-2.5%.

[0113] The above-described examples are only better embodiments of the present application, which are convenient for those skilled in the art to understand and use the present application. Obviously, any skilled person in the art can make slight modifications or changes to the present embodiments without creative labor and apply them to other embodiments. Therefore, the present application is not limited to the above-described embodiments, and any equivalent changes, simple modifications and modifications within the scope of the present application still belong to the scope of the present application.

Claims

1. A neodymium-iron-boron magnet, characterized in that A three-dimensional rectangular coordinate system is established, wherein the orientation direction is the positive direction of the Z-axis, the X-axis is parallel to the upper surface, and the origin of the three-dimensional rectangular coordinate system is located in the Nd-Fe-B magnet; The Nd-Fe-B magnet comprises a non-easy demagnetization region, a transition region, and an easy demagnetization region; the easy demagnetization region is an annular region located on the upper surface of the Nd-Fe-B magnet along the Z-axis direction, the non-easy demagnetization region is a central region located on the upper surface of the Nd-Fe-B magnet along the Z-axis direction, and the transition region is an interface region located between the easy demagnetization region and the non-easy demagnetization region; The content ratio of Tb in the transition region to the easy demagnetization region is (0.5-0.96):1; The content ratio of Tb in the transition region to the non-easy demagnetization region is 1:(0-0.93); The content ratio of Dy in the transition region to the easy demagnetization region is 1:1; The content ratio of Dy in the transition region to the non-easy demagnetization region is 1:

1.

2. The neodymium-iron-boron magnet according to claim 1, characterized in that The content ratio of Tb in the transition region to the easy demagnetization region is (0.5-0.9):1, for example, 0.79:1 or 0.8:1; And / or, the diffusion weight gain ratio of Tb in the transition region to the easy demagnetization region is (0.5-0.9):1, preferably (0.5-0.8):1, for example, 0.79:1 or 0.8:1; And / or, the content ratio of Tb in the transition region to the non-easy demagnetization region is 1:(0-0.2), for example, 1:0.02, 1:0.04, or 1:0.05; And / or, the diffusion weight gain ratio of Tb in the transition region to the non-easy demagnetization region is 1:(0-0.2), preferably 1:0.02 or 1:0.04; And / or, the content ratio of Tb in the easy demagnetization region to the non-easy demagnetization region is 1:(0-0.9), preferably 1:(0-0.5), more preferably 1:(0-0.2), for example, 1:0.02, 1:0.03, or 1:0.04; And / or, the diffusion weight gain ratio of Tb in the easy demagnetization region to the non-easy demagnetization region is 1:(0-0.9), preferably 1:(0-0.5), more preferably 1:(0-0.2), for example, 1:0.02, 1:0.03, or 1:0.04; And / or, the diffusion weight gain ratio of Dy in the easy demagnetization region to the non-easy demagnetization region is 1:1; And / or, the diffusion weight gain of Tb in the easy demagnetization region is gradiently distributed along the X-axis; And / or, the diffusion weight gain of Tb in the transition region is gradiently distributed along the X-axis; And / or, the diffusion weight gain of Tb in the non-easy demagnetization region is gradiently distributed along the X-axis.

3. The neodymium-iron-boron magnet of claim 1, wherein, The content of Tb in the easy demagnetization region is 0.1wt%-2.5wt%, preferably 0.25wt%-1wt%, more preferably 0.25wt%-0.6wt%, for example, 0.55wt%, 0.58wt%, or 0.6wt%; And / or, the diffusion weight gain of Tb in the easy demagnetization region is 0.1wt%-2.5wt%, preferably 0.25wt%-1wt%, more preferably 0.25wt%-0.6wt%, for example, 0.55wt%, 0.58wt%, or 0.6wt%; and / or, the content of Tb in the non-remanence easy region is 0-1.6wt%, preferably 0-0.5wt%, more preferably 0-0.05wt%, for example 0.01wt%, 0.02wt% or 0.022wt%; and / or, the diffusion weight gain of Tb in the non-remanence easy region is 0-1.6wt%, preferably 0-0.5wt%, more preferably 0-0.05wt%, for example 0.01wt%, 0.02wt% or 0.022wt%; and / or, the content of Tb in the transition region is 0.1wt%-2.4wt%, preferably 0.125wt%-1wt%, for example 0.24wt%, 0.36wt%, 0.38wt%, 0.44wt%, 0.46wt% or 0.48wt%; and / or, the diffusion weight gain of Tb in the transition region is 0.1wt%-2.4wt%, preferably 0.125wt%-1wt%, for example 0.24wt%, 0.36wt%, 0.38wt%, 0.44wt%, 0.46wt% or 0.48wt%; and / or, the content of Dy in the non-remanence easy region is 0.1wt%-4wt%, for example 2.2wt%; and / or, the diffusion weight gain of Dy in the non-remanence easy region is 0-0.8wt%, preferably 0.2wt%-0.6wt%; and / or, the content of Dy in the non-remanence easy region is 0.1wt%-4wt%, for example 2.2wt%; and / or, the diffusion weight gain of Dy in the non-remanence easy region is 0-0.8wt%, preferably 0.2wt%-0.6wt%; and / or, the content of Dy in the transition region is 0.1wt%-4wt%, for example 0.45wt% or 2.2wt%; 4. The neodymium-iron-boron magnet of claim 1, wherein, and / or, the diffusion weight gain of Dy in the transition region is 0-0.8wt%, for example 0.6wt%. The ratio of coercivity of the remanence easy region and the non-remanence easy region is 1:(0.7-0.96), preferably 1:(0.8-0.97), for example 1: 0.875, 1:0.946 or 1:0.907; and / or, the shape of the remanence easy region is rectangular outer edge annular region in any plane perpendicular to the orientation direction; and / or, the neodymium iron boron magnet is a cuboid; and / or, the shape of the non-remanence easy region is a rectangle in any plane perpendicular to the orientation direction; and / or, the ratio of length to thickness of the neodymium iron boron magnet is (3-25):1, preferably (3.64-24.27):1, more preferably (8.74-24.27):1, for example 12.85:1; the length refers to the extension distance of one side of the upper surface along the positive direction of the X axis; the thickness refers to the extension distance of the cuboid from the upper surface along the positive direction of the Z axis; 5. The neodymium-iron-boron magnet of claim 1, wherein, and / or, the thickness of the neodymium iron boron magnet is ≥5mm. The width of the remanence easy region is 0-6mm and not 0, more preferably 3-5mm; the meaning of the width is the length covered by the remanence easy region along the direction perpendicular to the four sides of the origin; and / or, the volume percentage of the easy demagnetization zone in the volume of the Nd-Fe-B magnet is 20%-80%, preferably 29%-70%, for example 54.6% or 42.48%; and / or, the volume percentage of the transition zone in the volume of the Nd-Fe-B magnet is 5%-15%, preferably 10%-15%, more preferably 10.6%-13.65%; and / or, the volume percentage of the non-easy demagnetization zone in the volume of the Nd-Fe-B magnet is 20%-80%, preferably 24.18%-70.66%, more preferably 34.27%-57.5%.

6. The neodymium-iron-boron magnet of claim 1, wherein, The grain boundary structure of the neodymium-iron-boron magnet comprises Re2Fe 14 B main phase grains and Re-rich phase grain boundaries; the Re2Fe 14 The B main phase grains comprise a core layer and a shell layer; the Re is Dy and / or Tb; Preferably, the Re2Fe 14 The B main phase crystal grain comprises, from inside to outside, a core layer, a first shell layer and a second shell layer, the first shell layer is (Nd, Tb)2Fe 14 B hard magnetic layer, and the second shell layer is (Nd, Dy)2Fe 14 B hard magnetic layer.

7. A method of producing a neodymium-iron-boron magnet as claimed in any one of claims 1 to 6, characterized in that, It comprises the following steps: applying a first diffusion source on four non-oriented surfaces of the Nd-Fe-B substrate and applying a second diffusion source on at least one oriented surface of the Nd-Fe-B substrate, and performing grain boundary diffusion treatment on the Nd-Fe-B substrate to which the diffusion sources are applied; the oriented surface is the surface of the Nd-Fe-B substrate perpendicular to the orientation direction, and the non-oriented surface is the surface of the Nd-Fe-B substrate parallel to the orientation direction; the first diffusion source contains Tb, and the second diffusion source contains Dy.

8. The method of producing a neodymium-iron-boron magnet according to claim 7, wherein the second diffusion source is applied on two oriented surfaces of the Nd-Fe-B substrate; and / or, the first diffusion source does not contain Dy; and / or, the second diffusion source does not contain Tb; and / or, the first diffusion source is elemental Tb; and / or, the first diffusion source is a Tb-M alloy, M contains one or more of Cu, Al, Co, Ga, Zr and Ti; wherein the mass percentage of M in the Tb-M is preferably 0-40%, and is not 0; and / or, the first diffusion source is a hydride of Tb or a fluoride of Tb; and / or, the second diffusion source is elemental Dy; and / or, the second diffusion source is a Dy-M alloy, M contains one or more of Cu, Al, Co, Ga, Zr and Ti; wherein the mass percentage of M in the Dy-M is preferably 0-40%, and is not 0; and / or, the second diffusion source is a hydride of Dy or a fluoride of Dy; and / or, the mass percentage of Tb in the first diffusion source is 0.25%-0.75%, preferably 0.3%-0.75%; and / or, the mass percentage of Dy in the second diffusion source is 0.25%-0.75%; and / or, the temperature of the grain boundary diffusion is 750-950℃, for example 900℃; and / or, the time of the grain boundary diffusion is 5-30h, for example 10h; and / or, it further comprises aging treatment after the grain boundary diffusion; wherein the temperature of the aging treatment is preferably 300-600℃, for example 500℃; wherein the time of the aging treatment is preferably 1-10h, for example 3h; and / or, the application method is for example coating; wherein, preferably, the coating method is spraying or printing; wherein the dewaxing temperature of the spraying is preferably 200-400℃; wherein the dewaxing temperature of the printing is preferably 100-500℃; Preferably, the first diffusion source and the second diffusion source further comprise a solvent and a binder; wherein the solvent is, for example, water, alcohol, ketone or ester.

9. A neodymium-iron-boron magnet produced by the method of any one of claims 7 to 8.

10. Use of a neodymium-iron-boron magnet according to any one of claims 1 to 6 and 9 in a magnetic steel.

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