Composite rare earth permanent magnet material with heterogeneous structure and preparation method thereof

Abstract

This invention belongs to the field of permanent magnet material technology, and relates to a composite rare-earth permanent magnet material with a heterogeneous structure and its preparation method. The preparation method includes: hot-pressing first and second magnetic powders with different rare-earth contents in an alternating layered manner to prepare a preform; thermoplastic deformation of the preform, compressing it in the X-axis direction and expanding it in the Y-axis direction to form a thermoplastic deformed preform composed of alternating first and second magnetic parts, wherein the orientation of the first magnetic part is transverse, and the second magnetic part has an isotropic, non-directional texture; the first magnetic part is magnetized transversely, and the second magnetic part is magnetized longitudinally, thereby obtaining a composite rare-earth permanent magnet material with a heterogeneous structure. This invention, through the heterogeneous structure design of rare-earth-rich anisotropic magnetic parts and rare-earth-poor isotropic magnetic parts, combined with directional magnetization, enables the permanent magnet material to possess both a high surface magnetic peak value and excellent sinusoidal surface magnetic flux density distribution characteristics.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet materials technology, and relates to a composite rare earth permanent magnet material with a heterogeneous structure and its preparation method. Background Technology

[0002] Rare earth permanent magnet materials are a fundamental functional magnetic material that is extremely important in national production and daily life. With the rapid development of advanced and high-end rare earth permanent magnet motors, increasingly higher requirements are being placed on rare earth permanent magnet materials and their functional components. Applications in fields such as small or micro disc motors and linear motors require magnetic materials to provide high surface magnetism while also offering excellent sinusoidal properties. This is necessary to improve the power density or torque density of the motor, reduce harmonic losses, lower the torque fluctuation rate, and improve torque output stability.

[0003] In disc-type permanent magnet motors, permanent magnet components can be fabricated by bonding magnets and then magnetized to provide good sinusoidal characteristics, but the surface magnetism is very low, making it difficult to meet the requirements of disc-type permanent magnet motors. If mature sintered magnets are used, square waves or saddle waves are usually obtained after magnetization, which affects the accuracy of the motor. In linear motors, permanent magnet components are usually obtained by alternating N and S arrangements of permanent magnets, but this method usually causes the magnetic field to dissipate into space, making it difficult to obtain high air gap magnetic flux density, and the waveform is non-sinusoidal, which has a certain impact on the output fluctuation rate of the motor. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, the present invention aims to provide a composite rare-earth permanent magnet material with a heterogeneous structure and its preparation method, thereby providing excellent surface magnetism and excellent sinusoidal properties.

[0005] The present invention employs the following technical solutions to achieve its objective: One aspect of the present invention provides a method for preparing a composite rare-earth permanent magnet material with a heterogeneous structure, comprising the following steps: S1. The first magnetic powder forming the first magnetic part and the second magnetic powder forming the second magnetic part are loaded into a hot press mold in an alternating layered manner and hot-pressed to prepare a preform; S2. The preform is placed in the cavity of a thermoplastic deformation mold for thermoplastic deformation, so that the preform is compressed in the X-axis direction and expanded in the Y-axis direction to form a thermoplastic deformation preform composed of alternating first magnetic part and second magnetic part. The crystallographic texture orientation of the first magnetic part is transverse, and the second magnetic part is an isotropic non-directional texture. S3. The first magnetic part adopts a transverse magnetization method, and the magnetization directions of adjacent first magnetic parts are opposite; the second magnetic part adopts a longitudinal magnetization method, and the magnetization directions of adjacent second magnetic parts are opposite, thereby obtaining a composite rare earth permanent magnet material with a heterogeneous structure.

[0006] To facilitate the explanation of the structural relationships of the present invention, as follows: Figure 2 As shown in the attached figure, a three-dimensional coordinate system is established, wherein: the direction in which the size increases after thermoplastic deformation is the Y-axis direction, the direction in which the size decreases after thermoplastic deformation is the X-axis direction, and the direction perpendicular to the X-axis and Y-axis directions is the Z-axis direction. The Z-axis direction is also perpendicular to the ground. It should be noted that the above coordinate system is only used to describe the relative positional relationship between the various structures and does not constitute a limitation on the scope of protection of this invention.

[0007] Preferably, the first magnetic powder and the second magnetic powder are each independently selected from any one of neodymium iron boron permanent magnet materials, permanent magnet ferrite materials, samarium cobalt permanent magnet materials, samarium iron nitrogen permanent magnet materials, and manganese bismuth permanent magnet materials.

[0008] Preferably, the first magnetic powder is a rare-earth-rich permanent magnet material with a rare-earth element content of 27-35 wt%, and the second magnetic powder is a rare-earth-poor permanent magnet material with a rare-earth element content of <26.8 wt%. The different rare-earth contents of the first and second magnetic powders result in different textures during the subsequent hot extrusion process.

[0009] Further optimization yields the first magnetic powder with the chemical formula: RE x1 Fe 100-x1-y1-z1 M y1 B z1 Where 27wt%≤x1≤35wt%, 0≤y1≤10wt%, 0.6wt%≤z1≤1.1wt%, RE is one or more of the rare earth elements Pr, Nd, Dy, and Tb, M is one or more of Al, Co, Cu, Ga, and Zr, and B is boron.

[0010] Preferably, the chemical formula of the second magnetic powder is: RE x2 Fe 100-x2-y2-z2 M y2 B z2 Where x2 < 26.8 wt%, 0 ≤ y2 ≤ 10 wt%, 0.6 wt% ≤ z2 ≤ 1.1 wt%, RE is one or more of the rare earth elements Pr, Nd, Dy, and Tb, M is one or more of Al, Co, Cu, Ga, and Zr, and B is boron.

[0011] The first and second magnetic powders were prepared by conventional rapid solidification belt spinning, hydrogen crushing and air jet milling processes.

[0012] The ratio of the first magnetic powder to the second magnetic powder varies depending on the actual application and is not subject to special optimization or restriction.

[0013] Preferably, the structure of the thermoplastic deformation mold cavity is as follows: the thermoplastic deformation mold cavity includes an upper cavity and a lower cavity that are interconnected; The upper cavity has the same X-axis length as the preform, the upper cavity has a larger Y-axis width than the preform, and the upper cavity has a larger Z-axis height than the preform, so that the upper mold can enter the upper cavity. The lower cavity is smaller in the X-axis direction than the upper cavity in the X-axis direction. The lower cavity is the same size as the upper cavity in the Y-axis direction. The lower cavity is larger in the Z-axis direction than the upper cavity in the Z-axis direction.

[0014] In summary, the cavity of a thermoplastic deformation mold is larger at the top and smaller at the bottom in the X-axis direction, and consistent in the top and bottom in the Y-axis direction.

[0015] Further preferably, the dimension of the upper cavity in the Y-axis direction is 1.5 to 5 times the Y-axis width of the preform. The dimension of the upper cavity in the X-axis direction is 2 to 6 times the dimension of the lower cavity in the X-axis direction.

[0016] Further preferred, the lower cavity is centrally located below the upper cavity in the X-axis direction.

[0017] Preferably, the shape of the preform is a right parallelepiped, i.e., a cuboid or a cube.

[0018] Preferably, the lower cavity of the thermoplastic deformation mold cavity is also a right parallelepiped shape.

[0019] Preferably, the preform is placed in the upper cavity of the thermoplastic deformation mold cavity, and in the Y-axis direction, the preform is centrally arranged in the upper cavity, and the center line of the preform in the Y-axis direction coincides with the center line of the upper cavity in the Y-axis direction.

[0020] The preform is placed in the upper cavity of the thermoplastic deformation mold. During the plastic deformation process of pressure and heat, the preform is squeezed into the lower cavity. The size design of the thermoplastic deformation mold cavity allows the preform to be compressed in the X-axis direction and expanded in the Y-axis direction after being squeezed into the lower cavity. This thermoplastic deformation gives the first magnetic part a crystallographic texture, with the texture orientation in the transverse direction, i.e., the X-axis direction.

[0021] Preferably, the hot pressing pressure in step S1 is 50~500MPa, the temperature is 300~750℃, and the holding time is 0.5~10min. The hot pressing mold is removed immediately after pressing is completed.

[0022] Preferably, when the first magnetic powder and / or the second magnetic powder are samarium iron nitrogen permanent magnet materials, the hot pressing temperature is 300~500℃, the pressure is 300~500MPa, and the hot pressing mold is removed immediately after pressing is completed.

[0023] Preferably, during the thermoplastic deformation process in step S2, the pressing speed is 0.1~2 mm / s, the pressure is 20~200 MPa, the temperature is 750~1000℃, and the holding time is 0.5~10 min. The thermoplastic deformation mold is removed immediately after the thermoplastic deformation is completed.

[0024] To ensure pressing efficiency, both hot pressing and thermoplastic deformation processes are carried out under inert gas protection conditions with a pressure of 101.2~102 kPa. The inert gas is nitrogen or argon, preferably argon.

[0025] Magnetization is performed based on the texture orientation of the first and second magnetic parts within the thermoplastic deformed blank. The crystallographic texture orientation of the first magnetic part is transverse; using transverse magnetization yields high magnetic properties, resulting in a higher peak magnetic flux density on the surface of the permanent magnet material and superior sinusoidal magnetic field waveform. The second magnetic part is composed of rare-earth-poor magnetic powder and remains isotropic after thermoplastic deformation, exhibiting relatively low magnetic properties. Using longitudinal magnetization, it serves as a transition region in the magnetic circuit after magnetization.

[0026] In the orientation and magnetization directions, the X-axis direction is the transverse direction, and the Z-axis direction is the longitudinal direction.

[0027] The second aspect of the present invention provides a composite rare-earth permanent magnet material with a heterogeneous structure, which is prepared by the above method.

[0028] Preferably, the composite rare earth permanent magnet material is composed of a first magnetic part and a second magnetic part arranged in alternating layers; The first magnetic part has a crystallographic texture, and the texture orientation is transverse. The second magnetic part is an isotropic structure; The first magnetic part is magnetized in the transverse direction, and the magnetization directions of two adjacent first magnetic parts are opposite. The second magnetic part is magnetized in the longitudinal direction, and the magnetization directions of two adjacent second magnetic parts are opposite.

[0029] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention utilizes hot extrusion and thermoplastic deformation technologies to develop a heterogeneous permanent magnet material. The first magnetic part is a permanent magnet material with good anisotropic texture, exhibiting better magnetic properties than isotropic materials. After magnetization, it provides a strong surface magnetism within the heterogeneous permanent magnet material. The second magnetic part is a permanent magnet material with weaker texture orientation capability, but after thermoplastic deformation, it still exhibits an isotropic texture on its surface. After magnetization, it provides a magnetic circuit transition region within the heterogeneous permanent magnet material. Overall, it forms a Halbach-structured magnetic functional material, which not only achieves high surface magnetism but also good sinusoidal surface magnetism distribution, effectively solving the technical problems of low surface magnetism or poor sinusoidal magnetic field waveform in traditional magnets.

[0030] 2. The magnetic circuit in the permanent magnet functional material of this invention has a Halbach structure. Compared with traditional Halbach structure permanent magnet functional components prepared by splicing, the permanent magnet functional material provided by this invention is a monolithic material. It eliminates the need for splicing multiple materials to obtain a permanent magnet with high surface magnetism, reducing magnetic field dissipation, increasing air gap magnetic flux density, and avoiding splicing errors. The magnetic circuit stability and magnetic field uniformity are significantly superior to traditional spliced ​​Halbach permanent magnet components. Furthermore, because it is a monolithic magnet, assembly is simple during motor manufacturing, and the extremely high surface magnetism greatly reduces the assembly difficulty and time, thus improving motor manufacturing efficiency.

[0031] 3. The high-performance first magnetic part provides the peak surface magnetic field after magnetization, so the entire magnetic functional material has a higher peak surface magnetic field, which can achieve higher thrust for linear motors; since the surface magnetic field distribution waveform has a better sinusoidal characteristic, the prepared motor has a smaller fluctuation rate and the motor performance is better.

[0032] 4. The complex orientation magnetic material prepared by this invention is prepared using near-net-shape technology, which does not require machining, avoids excessive cutting, and saves raw materials and costs. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the preform structure prepared in Example 1.

[0034] Figure 2 This is a schematic diagram of the structure of the thermoplastic deformation mold cavity in Example 1.

[0035] Figure 3 A schematic diagram (a) and an internal magnetic field pattern (b) of the heterostructure composite permanent magnet material prepared in Example 1.

[0036] Figure 4 The simulated surface magnetic field of the heterostructure composite permanent magnet material prepared in Example 1.

[0037] Figure 5 The simulated surface magnetic field of the heterostructure composite permanent magnet material prepared in Example 2.

[0038] Figure 6 A schematic diagram (a) of the preform structure prepared for Comparative Example 1 and a schematic diagram (b) of the thermoplastic deformed preform structure.

[0039] Figure 7 A schematic diagram (a) and an internal magnetic field pattern (b) of the heterostructure composite permanent magnet material prepared for Comparative Example 1.

[0040] Figure 8 The surface magnetic field of the heterostructure composite permanent magnet material prepared for Comparative Example 1 is simulated. Detailed Implementation

[0041] In the description of this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, and includes both a and b. "Multiple" includes two or more types, and can be two, three, four, five, or more.

[0042] The technical solution of the present invention will be further described and illustrated below with reference to specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of helping to understand the present invention and are not intended to limit the specific scope of the present invention. Furthermore, the accompanying drawings used herein are merely for better illustrating the content disclosed in the present invention and do not limit the scope of protection. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used in the art, and the methods used in the embodiments are all conventional methods in the art.

[0043] In the following examples and comparative examples, the subscript values ​​in the chemical formulas of magnetic powders are the weight fractions (wt) of each element.

[0044] Example 1

[0045] The permanent magnet material in this embodiment is prepared by the following method: S1, The component with rare earth element rich in Nd 22.3 Pr 7.3 Ga 0.47 Fe 余量 Co 3.5 B 0.95 (wt%) of the first magnetic powder and the rare earth-depleted composition of Nd 25 Fe 余量 Co3Ga 0.6 B 0.95The second layer of magnetic powder (wt%) is alternately placed into a hot press mold, then placed in a hot press device, heated to 650℃, and the pressure is gradually increased to 200MPa to prepare a densified preform. The holding time is 2 minutes. The preform is rectangular in shape, with dimensions of 20×10×40mm in the X, Y, and Z directions, and a total of 8 layers. Figure 1 As shown.

[0046] S2. Place the precast blank into the... Figure 2 In the thermoplastic deformation mold cavity shown, the upper cavity has dimensions of 20×20×45mm in the XYZ direction, and the lower cavity has dimensions of 6×20×75mm in the XYZ direction. The lower cavity is centrally located below the upper cavity in the X-axis direction. In the X-direction, the preform is in contact with the inner wall of the cavity (the two surfaces in contact with the inner wall are perpendicular to the X-axis). In the Y-direction, the preform is centrally located in the upper cavity, and the centerline of the preform in the Y-axis direction coincides with the centerline of the upper cavity in the Y-axis direction. The thermoplastic deformation mold is placed in a hot press, heated to 840℃ and held for 1 minute. The press is controlled to press at a speed of 0.3mm / s, causing the preform to shrink in the X-direction and expand in the Y-direction in the hot extrusion deformation zone, thus undergoing plastic deformation until the preform is completely squeezed into the lower part of the cavity and formed, producing a product as shown. Figure 3 The diagram shows a permanent magnet material with a heterogeneous structure. The first magnetic powder is an anisotropic material that forms the first magnetic part during thermoplastic deformation, exhibiting good texture-forming ability with a transverse crystallographic texture orientation. The second magnetic powder is a rare-earth-poor isotropic material, and the second magnetic part formed during thermoplastic deformation is also isotropic, but its magnetic properties are relatively low. The thickness of the first magnetic part is 5 mm, and the thickness of the second magnetic part is 3 mm.

[0047] S3. Customize corresponding magnetizing coils according to the orientation texture of the heterogeneous composite permanent magnet material, and magnetize the material. The first magnetic part adopts a transverse magnetization method, with the magnetization direction arranged along the transverse direction of the material (X-axis direction). The magnetization directions of two adjacent first magnetic parts are opposite. The second magnetic part adopts a longitudinal magnetization method, with the magnetization direction arranged along the longitudinal direction of the material (Z-axis direction). The magnetization directions of two adjacent second magnetic parts are opposite, thereby obtaining a magnetic functional material with heterogeneous structure and special magnetic circuit. Figure 3 The direction of the middle arrow indicates the direction of the internal magnetic field of the material after magnetization. Figure 4 This is a simulated magnetic field.

[0048] In this embodiment, the first magnetic part has an excellent crystallographic texture, is oriented laterally, and possesses high magnetic properties. After magnetization, the magnetic field direction is laterally, providing the surface magnetic peak portion. The second magnetic part is an isotropic part with relatively low magnetic properties. After magnetization, the magnetic field direction is longitudinal, serving as the transition region of the magnetic circuit, such as... Figure 3 As shown in (b). The complex-oriented magnetic material prepared in this embodiment is prepared using near-net-shape technology, which does not require a large amount of cutting, thus saving raw materials and costs. Secondly, in this embodiment, the high-performance first magnetic part provides a peak surface magnetic field after magnetization, so the entire magnetic functional material has a higher peak surface magnetic field, which can achieve higher thrust for linear motors. Since the surface magnetic field distribution waveform has a better sinusoidal characteristic, the prepared motor has a smaller fluctuation rate, and the motor performance is better.

[0049] Example 2

[0050] The permanent magnet material in this embodiment is prepared by the following method: S1, The component with rare earth element rich in Nd 24 Pr 6.5 Ga 0.76 Fe 余量 Co 4.2 B 0.85 (wt%) of the first magnetic powder and the rare earth-depleted composition of Nd 24 Fe 余量 Co4Ga 0.7 B 0.85 (wt%) of the second layer of magnetic powder is alternately placed into a hot press mold, then placed in a hot press device, heated to 700℃, and the pressure is gradually increased to 180MPa to prepare a densified preform. The holding time is 2 minutes. The preform is rectangular in shape, with dimensions of 30×15×30mm in the X, Y, and Z directions, and a total of 8 layers. Figure 1 As shown.

[0051] S2. Place the preform into the cavity of a thermoplastic deformation mold. The upper part of the mold cavity has dimensions of 30×30×50mm in the XYZ direction, and the lower part has dimensions of 9×30×60mm in the XYZ direction. In the X direction, the preform is in contact with the inner wall of the cavity. In the Y direction, the preform is centrally positioned in the upper cavity, with the centerline of the preform's Y-axis coinciding with the centerline of the upper cavity's Y-axis. Place the thermoplastic deformation mold in a hot press, heat to 900℃ and hold for 1.5 minutes, and gradually apply pressure at a speed of 0.2mm / s. This causes the preform to shrink in the X direction and expand in the Y direction in the hot extrusion deformation zone, resulting in plastic deformation until the preform is completely squeezed into the lower part of the cavity and formed, producing a product as shown. Figure 3The diagram shows a permanent magnet material with a heterogeneous structure. The first magnetic powder is an anisotropic material that forms the first magnetic part during thermoplastic deformation, exhibiting good texture-forming ability. Its crystallographic texture orientation is transverse, resulting in high magnetic properties. The second magnetic powder is a rare-earth-poor isotropic material, and the second magnetic part formed during thermoplastic deformation is also isotropic, but its magnetic properties are relatively low. The thickness of the first magnetic part is 5 mm, and the thickness of the second magnetic part is 3 mm.

[0052] S3. Customize corresponding magnetizing coils according to the orientation texture of the heterogeneous composite permanent magnet material, and magnetize the material. The first magnetic part adopts a transverse magnetization method, with the magnetization direction arranged along the transverse side of the material. The magnetization directions of two adjacent first magnetic parts are opposite. The second magnetic part adopts a longitudinal magnetization method, with the magnetization direction arranged along the longitudinal side of the material. The magnetization directions of two adjacent second magnetic parts are opposite, thereby obtaining a magnetic functional material with heterogeneous structure and special magnetic circuit. Figure 3 The direction of the middle arrow indicates the direction of the internal magnetic field of the material after magnetization. Figure 5 This is a simulated magnetic field.

[0053] Comparative Example 1 The permanent magnet material of Comparative Example 1 was prepared by the following method: S1, The component with rare earth element rich in Nd 22.3 Pr 7.3 Ga 0.47 Fe 余量 Co 3.5 B 0.95 (wt%) of the first magnetic powder and the rare earth-depleted composition of Nd 25 Fe 余量 Co3Ga 0.6 B 0.95 The second layer of magnetic powder (wt%) was alternately placed into a hot-pressing die with an inner diameter of 16 mm, and then placed in a hot-pressing device. The temperature was raised to 650℃, and the pressure was gradually increased to 200 MPa to prepare a densified preform. The holding time was 2 minutes, and the preform was cylindrical in shape. Figure 6 As shown in (a), D is 16.3 mm, H is 60 mm, and the total number of layers is 8.

[0054] S2. Place the preform into a thermoplastic deformation mold cavity with an inner diameter of 30mm. Place the thermoplastic deformation mold into a hot press, heat to 840℃ and hold for 1 minute, and gradually apply pressure at a speed of 0.3mm / s to gradually upset the preform, forming a thermoplastic deformation preform composed of a first magnetic part and a second magnetic part, as shown. Figure 6(b) shows the assembly. The first magnetic powder is an anisotropic material that forms the first magnetic part during thermoplastic deformation, exhibiting good texture-forming ability. Its crystallographic texture orientation is longitudinal, resulting in high magnetic properties. The second magnetic powder is a rare-earth-poor isotropic material, and the second magnetic part formed during thermoplastic deformation is also isotropic, but its magnetic properties are relatively low. The thickness of the first magnetic part is 5 mm, and the thickness of the second magnetic part is 3 mm.

[0055] S3. The thermoplastic deformed preform is machined to obtain the following: Figure 7 (a) shows a cuboid magnet with the same dimensions as the permanent magnet material in Example 1. A corresponding magnetizing coil is customized according to the magnet's orientation texture, and the material is magnetized. The first magnetic part is magnetized longitudinally, with the magnetization direction along the longitudinal direction of the material. The magnetization directions of two adjacent first magnetic parts are opposite. The second magnetic part is magnetized transversely, with the magnetization direction along the transverse direction of the material. The magnetization directions of two adjacent second magnetic parts are opposite, resulting in a magnetic functional material with a heterogeneous structure and a special magnetic circuit. Figure 7 (b) The arrows indicate the direction of the magnetic field inside the material after magnetization. Figure 8 This is a simulated magnetic field.

[0056] Compared to Example 1, Comparative Example 1 requires machining, resulting in significant cutting and waste of raw materials. Furthermore, the second magnetic part of Comparative Example 1, with its low magnetic properties, provides a peak surface magnetic field after magnetization, thus resulting in an even lower peak surface magnetic field for the entire magnetic functional material.

[0057] All aspects, embodiments, and features of this invention should be considered illustrative in all respects and not limiting of the invention; the scope of the invention is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0058] In the preparation method of this invention, the order of the steps is not limited to the listed order. For those skilled in the art, variations in the order of the steps without creative effort are also within the scope of protection of this invention. Furthermore, two or more steps or actions can be performed simultaneously.

[0059] Finally, it should be noted that the specific embodiments described herein are merely illustrative examples of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them; it is neither necessary nor possible to exemplify all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the invention still fall within the scope of protection of the invention, and interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A method for preparing a composite rare-earth permanent magnet material with a heterogeneous structure, characterized in that, Includes the following steps: S1. The first magnetic powder forming the first magnetic part and the second magnetic powder forming the second magnetic part are loaded into a hot press mold in an alternating layered manner and hot-pressed to prepare a preform; S2. The preform is placed in the cavity of a thermoplastic deformation mold for thermoplastic deformation, so that the preform is compressed in the X-axis direction and expanded in the Y-axis direction to form a thermoplastic deformation preform composed of alternating first magnetic part and second magnetic part. The crystallographic texture orientation of the first magnetic part is transverse, and the second magnetic part is an isotropic non-directional texture. S3. The first magnetic part adopts a transverse magnetization method, and the magnetization directions of adjacent first magnetic parts are opposite; the second magnetic part adopts a longitudinal magnetization method, and the magnetization directions of adjacent second magnetic parts are opposite, thereby obtaining a composite rare earth permanent magnet material with a heterogeneous structure. The three-dimensional coordinate system includes: the Y-axis direction in which the size increases after thermoplastic deformation, the X-axis direction in which the size decreases after thermoplastic deformation, and the Z-axis direction in which the size is perpendicular to the X-axis and Y-axis directions. The horizontal direction is the X-axis, and the vertical direction is the Z-axis.

2. The preparation method according to claim 1, characterized in that, The first magnetic powder and the second magnetic powder are each independently selected from any one of neodymium iron boron permanent magnet materials, permanent magnet ferrite materials, samarium cobalt permanent magnet materials, samarium iron nitrogen permanent magnet materials, and manganese bismuth permanent magnet materials; The first magnetic powder is a rare earth-rich permanent magnet material with a rare earth element content of 27~35wt%, and the second magnetic powder is a rare earth-poor permanent magnet material with a rare earth element content of <26.8wt%.

3. The preparation method according to claim 1 or 2, characterized in that, The chemical formula of the first magnetic powder is: RE x1 Fe 100-x1-y1-z1 M y1 B z1 Where 27wt%≤x1≤35wt%, 0≤y1≤10wt%, 0.6wt%≤z1≤1.1wt%, RE is one or more of the rare earth elements Pr, Nd, Dy, and Tb, M is one or more of Al, Co, Cu, Ga, and Zr, and B is boron. The chemical formula of the second magnetic powder is: RE x2 Fe 100-x2-y2-z2 M y2 B z2 Where x2 < 26.8 wt%, 0 ≤ y2 ≤ 10 wt%, 0.6 wt% ≤ z2 ≤ 1.1 wt%, RE is one or more of the rare earth elements Pr, Nd, Dy, and Tb, M is one or more of Al, Co, Cu, Ga, and Zr, and B is boron.

4. The preparation method according to claim 1, characterized in that, The thermoplastic deformation mold cavity includes an upper cavity and a lower cavity that are interconnected; Among them, the size of the upper cavity in the X-axis direction is the same as the length of the preform in the X-axis direction, the size of the upper cavity in the Y-axis direction is greater than the width of the preform in the Y-axis direction, and the size of the upper cavity in the Z-axis direction is greater than the height of the preform in the Z-axis direction. The lower cavity is smaller in the X-axis direction than the upper cavity in the X-axis direction. The lower cavity is the same size as the upper cavity in the Y-axis direction. The lower cavity is larger in the Z-axis direction than the upper cavity in the Z-axis direction.

5. The preparation method according to claim 4, characterized in that, The dimension of the upper cavity in the Y-axis direction is 1.5 to 5 times the width dimension of the preform in the Y-axis direction; And / or, the dimension of the upper cavity in the X-axis direction is 2 to 6 times the dimension of the lower cavity in the X-axis direction.

6. The preparation method according to claim 4, characterized in that, The lower cavity is centered below the upper cavity in the X-axis direction.

7. The preparation method according to claim 4, characterized in that, The shape of the precast blank is a right parallelepiped; The lower cavity of the thermoplastic deformation mold cavity is a right parallelepiped shape.

8. The preparation method according to claim 4, characterized in that, The preform is placed in the upper cavity of the thermoplastic deformation mold cavity. In the Y-axis direction, the preform is centrally arranged in the upper cavity, and the center line of the preform in the Y-axis direction coincides with the center line of the upper cavity in the Y-axis direction.

9. The preparation method according to claim 1, characterized in that, In step S1, the hot pressing pressure is 50~500MPa, the temperature is 300~750℃, and the holding time is 0.5~10min; In the thermoplastic deformation process in step S2, the pressing speed is 0.1~2mm / s, the pressure is 20~200MPa, the temperature is 750~1000℃, and the holding time is 0.5~10min; Both hot pressing and thermoplastic deformation processes are carried out under inert gas protection conditions.

10. A composite rare-earth permanent magnet material with a heterogeneous structure, characterized in that, It is prepared by the method described in any one of claims 1 to 9, wherein the composite rare earth permanent magnet material is composed of a first magnetic part and a second magnetic part arranged in an alternating layered manner; The first magnetic part has a crystallographic texture, and the texture orientation is transverse. The second magnetic part is an isotropic structure; The first magnetic part is magnetized in the transverse direction, and the magnetization directions of two adjacent first magnetic parts are opposite. The second magnetic part is magnetized in the longitudinal direction, and the magnetization directions of two adjacent second magnetic parts are opposite.

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