Grain boundary diffusion source, grain boundary diffusion method of neodymium-iron-boron magnet and grain boundary diffusion neodymium-iron-boron magnet

Abstract

The invention provides a grain boundary diffusion source, a grain boundary diffusion method of a neodymium-iron-boron magnet and the grain boundary diffusion neodymium-iron-boron magnet. The grain boundary diffusion source comprises a HREExScyM100-x-y alloy, HREE represents a heavy rare earth element, M represents one or more of aluminum, copper, cobalt, gallium and zinc, and xlt is more than or equal to 60; y is greater than or equal to 5 and less than or equal to 30, and x + result is greater than or equal to 90; 100). According to the grain boundary diffusion source, all element ammonium in the grain boundary diffusion source are matched according to the specific atomic percent and act together, and the sintered neodymium-iron-boron grain boundary diffusion magnet high in coercive force and good in comprehensive magnetic performance can be prepared.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic materials, and in particular to a grain boundary diffusion source, a grain boundary diffusion method of a NdFeB magnet, and a grain boundary diffused NdFeB magnet. Background Art

[0002] With the development and progress of society, industrial Internet, new energy, high-speed rail transit, 5G communications and intelligent manufacturing have become key areas in which countries are competing to make breakthroughs; among them, NdFeB permanent magnet materials are widely used in the above fields due to their excellent magnetic properties. The above fields all require NdFeB magnets to be able to work stably under high temperature conditions, and the high temperature stability of the magnet is closely related to the coercive force. Therefore, improving the coercive force is the key to improving the comprehensive performance of sintered NdFeB magnets.

[0003] Increasing the coercive force of a magnet can effectively resist the inherent demagnetization field of the magnet at higher temperatures, thereby improving the thermal stability of the magnet. At present, the main method to increase the coercive force of a magnet is to increase the anisotropy field of the magnetocrystalline, and adding heavy rare earth elements is an effective method to increase the magnetocrystalline anisotropy field of sintered NdFeB magnets. The traditional method usually adds heavy rare earth elements during the smelting step or the powder making step, but there are disadvantages such as smelting burnout, waste of raw materials, and affecting the magnetization state of the magnet.

[0004] Grain boundary diffusion technology is an effective method to improve the coercivity of sintered NdFeB. However, with the widespread application and rapid development of magnet materials, higher requirements are also placed on the performance of sintered NdFeB magnets. Traditional grain boundary diffusion technology still needs to be further improved to obtain NdFeB magnets with better performance. Summary of the invention

[0005] Based on this, one or more embodiments of the present application provide a grain boundary diffusion source, a grain boundary diffusion method of a NdFeB magnet, and a grain boundary diffused NdFeB magnet; the use of the grain boundary diffusion source can effectively improve the coercive force of the grain boundary diffused NdFeB magnet.

[0006] According to a first aspect of an embodiment of the present application, a grain boundary diffusion source is provided, wherein the grain boundary diffusion source comprises HREE x Sc y M 100-x-y The alloy comprises: HREE represents a heavy rare earth element, M represents one or more of aluminum, copper, cobalt, gallium and zinc, and satisfies 60≤x≤95, 5≤y≤30, and 90≤x+y<100.

[0007] In some embodiments, the atomic percentage of the HREE element in the HREE-Sc-M alloy is 85%-90%, the atomic percentage of the Sc element is 5%-10%, and the atomic percentage of the M element is 1%-10%.

[0008] In some embodiments, the heavy rare earth element includes one or more of dysprosium and terbium.

[0009] According to a second aspect of an embodiment of the present application, a method for grain boundary diffusion of a neodymium iron boron magnet is provided, comprising the following steps:

[0010] The grain boundary diffusion source is attached to the surface of the original NdFeB magnet and subjected to diffusion treatment and tempering treatment.

[0011] In some of the embodiments, the grain boundary diffusion source is used as a target material, and the grain boundary diffusion source is attached to the surface of the NdFeB original magnet by magnetron sputtering.

[0012] In some of the embodiments, the thickness of the diffusion source on the surface of the NdFeB magnet after magnetron sputtering is ≤100 μm.

[0013] In some of the embodiments, the NdFeB raw magnet includes at least one of a sintered NdFeB magnet and a tempered NdFeB magnet.

[0014] In some embodiments, the grain boundary diffusion method satisfies at least one of the following characteristics:

[0015] (1) The temperature of the diffusion treatment is 800°C to 1000°C, and the time is 1h to 50h;

[0016] (2) The tempering temperature is 400℃~700℃ and the time is 1h~12h.

[0017] In some of the embodiments, before the grain boundary diffusion source is attached to the surface of the NdFeB original magnet, the NdFeB original magnet is pre-treated to remove oxides on the surface.

[0018] According to a third aspect of an embodiment of the present application, a grain boundary diffused NdFeB magnet is provided, which is prepared by using the grain boundary diffusion method of the NdFeB magnet described above.

[0019] Compared with the traditional technology, this application has the following beneficial effects:

[0020] The grain boundary diffusion source of the present application contains heavy rare earth elements, which can significantly improve the comprehensive magnetic properties of the magnet during the grain boundary diffusion process; the scandium element in the grain boundary diffusion source can refine the magnet grains and enhance the mechanical properties and corrosion resistance, while promoting the diffusion effect of dysprosium and terbium elements; auxiliary elements such as aluminum can improve the wettability of the diffusion source on the magnet surface, so that the diffusion source can be evenly distributed on the magnet surface, thereby improving the coercive force of the magnet. The specific atomic percentages of the ammonium elements in the above-mentioned grain boundary diffusion sources are matched and work together to prepare a sintered NdFeB grain boundary diffusion magnet with high coercive force and good comprehensive magnetic properties. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present application. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the present application, etc. can be purchased from the market or can be prepared by existing methods.

[0023] In the present application, "plurality", "multiple", "multiple times", "multiples", etc., unless otherwise specified, refer to a number greater than 2 or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0024] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0025] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0026] In the present application, when it comes to numerical intervals (i.e., numerical ranges), unless otherwise specified, the optional numerical distribution is considered continuous within the above numerical interval, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical range, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints. In this article, it is equivalent to directly listing each integer, such as t is an integer selected from 1-10, indicating that t is any integer selected from the integer group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all sub-ranges included therein.

[0027] The temperature parameters in this application, unless otherwise specified, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0028] When magnetron sputtering is used to co-sputter heavy rare earth elements and auxiliary elements in traditional technology, the sputtering time may be prolonged due to the mutual influence between the elements. Therefore, it is crucial to make the elements in the diffusion source target material cooperate with each other and improve the sputtering efficiency.

[0029] Some embodiments of the present application provide a grain boundary diffusion source, the grain boundary diffusion source includes HREE x Sc y M 100-x-y Alloy, wherein HREE represents a heavy rare earth element, M represents one or more of aluminum (Al), copper (Cu), cobalt (Co), gallium (Ga) and zinc (Zn), and satisfies 60≤x≤95, 5≤y≤30, and 90≤x+y<100.

[0030] The grain boundary diffusion source of the present application contains heavy rare earth elements, which can significantly improve the comprehensive magnetic properties of the magnet during the grain boundary diffusion process; the scandium (Sc) element in the grain boundary diffusion source can refine the magnet grains and enhance the mechanical properties and corrosion resistance; auxiliary elements such as aluminum can improve the wettability of the diffusion source on the magnet surface, so that the diffusion source can be evenly distributed on the magnet surface, thereby improving the coercive force of the magnet. The specific atomic percentages of the ammonium elements in the above-mentioned grain boundary diffusion source are matched and work together to prepare a sintered NdFeB grain boundary diffusion magnet with high coercive force and good comprehensive magnetic properties.

[0031] As an example, the value of x can be 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, or any value within the range formed by any two of the above point values.

[0032] In some optional embodiments, the atomic percentage of the HREE element is 85% to 90%.

[0033] As an example, the value of y can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or any value within the range formed by any two of the above point values.

[0034] In some optional embodiments, the atomic percentage of the Sc element is 5% to 10%.

[0035] Scandium can refine magnet grains and enhance mechanical properties and corrosion resistance, thereby improving the overall performance of the magnet.

[0036] In some optional embodiments, the atomic percentage of the M element is 1% to 10%.

[0037] As examples, the atomic percentage of the M element can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any value within the range formed by any two of the above point values.

[0038] In this application, atomic percentage refers to the ratio of the number of atoms of a certain element to the total number of atoms in the alloy.

[0039] Auxiliary elements can improve the diffusion performance of heavy rare earth elements on the surface of magnets, increase the diffusion depth of heavy rare earth elements, thereby improving coercivity and obtaining high-performance NdFeB magnets. At the same time, auxiliary elements can be enriched at the grain boundaries of magnets, and the grain boundary phase formed can improve the microstructure of the magnet; and can improve the stability of magnet performance in high temperature and other environments.

[0040] In some optional embodiments, the atomic percentage of the HREE element in the HREE-Sc-M alloy is 85%-90%, the atomic percentage of the Sc element is 5%-10%, and the atomic percentage of the M element is 5%-10%.

[0041] Controlling the atomic mass percentages of HREE elements and Sc elements within the above range can further improve the coercive force of the sintered NdFeB grain boundary diffusion magnet.

[0042] In some embodiments, the heavy rare earth element includes one or more of dysprosium (Dy) and terbium (Tb).

[0043] Compared with other rare earth elements, dysprosium and terbium can significantly enhance the anisotropy field of the magnet, thereby enhancing the coercive force of the magnet, which is a feature not possessed by other elements; scandium can promote the diffusion of dysprosium and terbium inside the magnet, thereby improving the effect of enhancing the coercive force.

[0044] Other embodiments of the present application provide a grain boundary diffusion method for a NdFeB magnet, including S10.

[0045] S10: attaching the above-mentioned grain boundary diffusion source to the surface of the original NdFeB magnet, and performing diffusion treatment and tempering treatment.

[0046] In some of the embodiments, in S10, the grain boundary diffusion source is used as a target material, and the grain boundary diffusion source is attached to the surface of the NdFeB original magnet by magnetron sputtering.

[0047] Traditional grain boundary diffusion technologies include coating, bonding, evaporation, magnetron sputtering, etc., through which heavy rare earth elements or their compounds can be attached to the surface of the magnet, and then through heat treatment, diffusion and penetration, tempering treatment, etc., the magnet composition can be controlled, the microstructure organization can be optimized, and the coercive force of the magnet can be improved.

[0048] Compared with other methods, magnetron sputtering can use less heavy rare earth alloy materials and produce magnets with higher coercivity. Magnetron sputtering can make heavy rare earth elements diffuse along the grain boundaries of sintered NdFeB, and a small part of them diffuse from the grain boundaries to the main phase, avoiding excessive heavy rare earth elements in the main phase causing remanence and a decrease in the maximum magnetic energy product.

[0049] At the same time, the film formed on the surface of the original NdFeB magnet by magnetron sputtering has good bonding with the substrate, the film formation rate is stable and controllable, the film thickness is controlled, the activity is high and it is easy to diffuse. Furthermore, the post-processing steps of the film formed by magnetron sputtering are relatively simpler. Magnetron sputtering is conducive to the uniform adhesion of the grain boundary diffusion source to the surface of the magnet, thereby improving the uniformity of the magnet performance.

[0050] It is understandable that when magnetron sputtering is used for coating, the grain boundary diffusion source is used as a target material for sputtering; the grain boundary diffusion source can be made into a target material by a casting method or a powder metallurgy method.

[0051] In some embodiments, the vacuum degree of magnetron sputtering is within 1 Pa, the temperature of magnetron sputtering is 100° C. to 150° C., the current of magnetron sputtering is 0.5A to 30A, and the rate of magnetron sputtering is 1 μm / min to 80 μm / min.

[0052] As an example, the vacuum degree of magnetron sputtering can be 0.1Pa, 0.2Pa, 0.3Pa, 0.4Pa, 0.5Pa, 0.6Pa, 0.7Pa, 0.8Pa, 0.9Pa, 1.0Pa, or any value within the range formed by any two of the above point values. Optionally, the vacuum degree of magnetron sputtering is 0.5Pa.

[0053] As an example, the temperature of magnetron sputtering can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, or any value within the range formed by any two of the above point values. Optionally, the temperature of magnetron sputtering is 120°C.

[0054] As an example, the current of magnetron sputtering can be 0.5A, 0.6A, 0.7A, 0.8A, 0.9A, 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A, 9A, 10A, 11A, 12A, 13A, 14A, 15A, 16A, 17A, 18A, 19A, 20A, 21A, 22A, 23A, 24A, 25A, 26A, 27A, 28A, 29A, 30A, or any value within the range formed by any two of the above point values. Optionally, the current of magnetron sputtering is 0.8A.

[0055] As an example, the rate of magnetron sputtering can be 1 μm / min, 2 μm / min, 3 μm / min, 4 μm / min, 5 μm / min, 10 μm / min, 15 μm / min, 20 μm / min, 25 μm / min, 30 μm / min, 35 μm / min, 40 μm / min, 45 μm / min, 50 μm / min, 55 μm / min, 60 μm / min, 65 μm / min, 70 μm / min, 75 μm / min, 80 μm / min, or any value within the range formed by any two of the above point values. Optionally, the rate of magnetron sputtering is 50 μm / min.

[0056] In some embodiments, the thickness of the diffusion source on the surface of the NdFeB magnet after magnetron sputtering is ≤100 μm. Further, the thickness of the diffusion source on the surface of the NdFeB magnet is 1 μm-100 μm.

[0057] As an example, the thickness of the diffusion source on the surface of the NdFeB magnet can be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, or any value within the range formed by any two of the above point values. Optionally, the thickness of the diffusion source on the surface of the NdFeB magnet is 5 μm.

[0058] In some embodiments, the NdFeB raw magnet in S10 includes at least one of a sintered NdFeB magnet and a tempered NdFeB magnet.

[0059] In some embodiments, the diffusion treatment in S20 is performed at a temperature of 800° C. to 1000° C. for a time of 1 h to 50 h.

[0060] As an example, the temperature of the diffusion treatment can be 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, or any value within the range formed by any two of the above point values.

[0061] As an example, the time for the diffusion treatment can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h, 31h, 32h, 33h, 34h, 35h, 36h, 37h, 38h, 39h, 40h, 41h, 42h, 43h, 44h, 45h, 46h, 47h, 48h, 49h, 50h, or any value within the range formed by any two of the above point values.

[0062] In some embodiments, the tempering treatment in S20 is performed at a temperature of 400° C. to 700° C. for a time of 1 h to 12 h.

[0063] As an example, the temperature of the tempering treatment can be 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, or any value within the range formed by any two of the above point values.

[0064] As an example, the annealing time can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, or any value within the range formed by any two of the above point values.

[0065] In some of the embodiments, before coating the grain boundary diffusion source on the surface of the NdFeB magnet, the method further includes the following step: pre-treating the NdFeB magnet to remove oxides on the surface of the NdFeB magnet.

[0066] It is understandable that the pretreatment method includes but is not limited to one or more of cleaning and polishing. The pretreatment method may also be other commonly used methods in the art, and the present application does not specifically limit this.

[0067] The above-mentioned preparation method of the present application is to attach a diffusion source to the surface of the magnet and diffuse the elements in the diffusion source into the interior of the magnet by heat treatment; the heavy rare earth elements will form a hard magnetic shell on the surface of the main phase grains of the magnet, and the hard magnetic shell changes the magnetic properties of the grain surface, so that the grains that are originally easily reversed in magnetization direction by an external reverse magnetic field have enhanced resistance to demagnetization, thereby improving the coercive force of the entire magnet.

[0068] Other embodiments of the present application provide a grain boundary diffused NdFeB magnet, which is prepared by the grain boundary diffusion method of the NdFeB magnet described above.

[0069] The grain boundary diffused NdFeB magnet of the present application has the advantages of high coercivity and good comprehensive performance, and is suitable for application in high temperature scenarios, especially in the new energy industry, high-speed rail transit industry, 5G communication industry, and intelligent manufacturing industry.

[0070] The present application will be further described below in conjunction with specific examples and comparative examples, but they should not be construed as limiting the scope of protection of the present application. The raw materials involved in the following specific examples, unless otherwise specified, can all be sourced from commercial sources, the instruments used, unless otherwise specified, can all be sourced from commercial sources, and the processes involved, unless otherwise specified, are all conventionally selected by those skilled in the art.

[0071] Example 1

[0072] 1) Provide grain boundary diffusion source alloy target: the grain boundary diffusion source is selected from Dy 90 Sc5Al5, wherein the atomic percentage of Dy element is 90%, the atomic percentage of Sc element is 5%, and the atomic percentage of Al element is 5%.

[0073] 2) Pretreatment: Cut the original NdFeB magnet into F20*20*6 squares, remove the oil on the surface by cleaning, then dry, and remove the surface oxide layer by grinding.

[0074] 3) Place the pretreated magnet blank into the magnetron sputtering equipment, control the sputtering process, so that the diffusion source is stably attached and increased in weight on both the upper and lower surfaces of the magnet, with a thickness of 5 μm on each side, and obtain a magnet with grain boundary diffusion source attached. The vacuum degree of magnetron sputtering is 0.5 Pa, the temperature of magnetron sputtering is 120°C, the current of magnetron sputtering is 0.8 A, and the rate of magnetron sputtering is 50 μm / min.

[0075] Subsequently, the magnet with the grain boundary diffusion source attached thereto is subjected to diffusion treatment at 900° C. for 24 hours; then, it is subjected to tempering treatment at 500° C. for 5 hours; and after cooling, a grain boundary diffusion magnet is obtained.

[0076] Example 2

[0077] 1) Provide grain boundary diffusion source alloy target: the grain boundary diffusion source is selected from Tb 90 Sc5Cu5, wherein the atomic percentage of Tb element is 90%, the atomic percentage of Sc element is 5%, and the atomic percentage of Cu element is 5%.

[0078] 2) Pretreatment: Cut the original NdFeB magnets into F20*20*6 blocks, remove the oil on the surface by cleaning, then dry, and remove the surface oxide layer by grinding.

[0079] 3) Place the pretreated magnet blank into the magnetron sputtering equipment, control the sputtering process, so that the diffusion source is stably attached and increased in weight on both the upper and lower surfaces of the magnet, with a thickness of 5 μm on each side, and obtain a magnet with grain boundary diffusion source attached. The vacuum degree of magnetron sputtering is 0.5 Pa, the temperature of magnetron sputtering is 120°C, the current of magnetron sputtering is 0.8 A, and the rate of magnetron sputtering is 50 μm / min.

[0080] Subsequently, the magnet with the grain boundary diffusion source attached thereto is subjected to diffusion treatment at 900° C. for 24 hours; then, it is subjected to tempering treatment at 500° C. for 5 hours; and after cooling, a grain boundary diffusion magnet is obtained.

[0081] Example 3

[0082] 1) Provide grain boundary diffusion source alloy target: the grain boundary diffusion source is selected from Dy 85 Sc5Al5Cu5, wherein the atomic percentage of Dy element is 85%, the atomic percentage of Sc element is 5%, the atomic percentage of Al element is 5%, and the atomic percentage of Cu element is 5%.

[0083] 2) Pretreatment: Cut the NdFeB raw magnet blank into F20*20*6 squares, remove the oil on the surface by cleaning, then dry, and remove the surface oxide layer by grinding.

[0084] 3) Place the pretreated magnet blank into the magnetron sputtering equipment, control the sputtering process, so that the diffusion source is stably attached and increased in weight on both the upper and lower surfaces of the magnet, with a thickness of 5 μm on each side, and obtain a magnet with grain boundary diffusion source attached. The vacuum degree of magnetron sputtering is 0.5 Pa, the temperature of magnetron sputtering is 120°C, the current of magnetron sputtering is 0.8 A, and the rate of magnetron sputtering is 50 μm / min.

[0085] Subsequently, the magnet with the grain boundary diffusion source attached thereto is subjected to diffusion treatment at 900° C. for 24 hours; then, it is subjected to tempering treatment at 500° C. for 5 hours; and after cooling, a grain boundary diffusion magnet is obtained.

[0086] Example 4

[0087] 1) Provide grain boundary diffusion source alloy target: the grain boundary diffusion source is selected from Tb 85 Sc5Al5Cu5, wherein the atomic percentage of Tb element is 85%, the atomic percentage of Sc element is 5%, the atomic percentage of Al element is 5%, and the atomic percentage of Cu element is 5%.

[0088] 2) Pretreatment: Cut the original magnet blank into F20*20*6 squares, remove the oil on the surface by cleaning, then dry, and remove the surface oxide layer by grinding.

[0089] 3) Place the pretreated magnet blank into the magnetron sputtering equipment, control the sputtering process, so that the diffusion source is stably attached and increased in weight on both the upper and lower surfaces of the magnet, with a thickness of 5 μm on each side, and obtain a magnet with grain boundary diffusion source attached. The vacuum degree of magnetron sputtering is 0.5 Pa, the temperature of magnetron sputtering is 120°C, the current of magnetron sputtering is 0.8 A, and the rate of magnetron sputtering is 50 μm / min.

[0090] Subsequently, the magnet with the grain boundary diffusion source attached thereto is subjected to diffusion treatment at 900° C. for 24 hours; then, it is subjected to tempering treatment at 500° C. for 5 hours; and after cooling, a grain boundary diffusion magnet is obtained.

[0091] Example 5

[0092] It is basically the same as Example 1, except that the grain boundary diffusion source is replaced by Dy 45 Tb 45 Sc5Al5, wherein the atomic percentage of Dy element is 45%, the atomic percentage of Tb element is 45%, the atomic percentage of Sc element is 5%, and the atomic percentage of Al element is 5%.

[0093] Example 6

[0094] It is basically the same as Example 1, except that the grain boundary diffusion source is replaced by Dy 60 Sc 30 Al5, wherein the atomic percentage of Dy element is 60%, the atomic percentage of Sc element is 30%, and the atomic percentage of Al element is 5%.

[0095] Comparative Example 1

[0096] It is basically the same as Example 1, except that the grain boundary diffusion source is replaced by Dy 95 Al5, in which the atomic percentage of Dy element is 95%, the atomic percentage of Al element is 5%, and no Sc element is added.

[0097] Comparative Example 2

[0098] It is basically the same as Example 2, except that the grain boundary diffusion source is replaced by Tb 95 Cu5, wherein the atomic percentage of Tb element is 95%, the atomic percentage of Cu element is 5%, and no Sc element is added.

[0099] Comparative Example 3

[0100] It is basically the same as Example 3, except that the grain boundary diffusion source is replaced by Dy 85 Y5Al5Cu5, wherein the atomic percentage of Dy element is 85%, the atomic percentage of Y element is 5%, the atomic percentage of Al element is 5%, the atomic percentage of Cu element is 5%, and no Sc element is added.

[0101] Comparative Example 4

[0102] It is basically the same as Example 4, except that the grain boundary diffusion source is replaced by Tb 85 Y5Al5Cu5, wherein the atomic percentage of Tb element is 85%, the atomic percentage of Y element is 5%, the atomic percentage of Al element is 5%, the atomic percentage of Cu element is 5%, and no Sc element is added.

[0103] The types of grain boundary diffusion sources in Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Table 1.

[0104] Table 1

[0105]

[0106] The remanence, coercive force, maximum magnetic energy product and squareness of the original magnet blank, the grain boundary diffused NdFeB magnets prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were tested with reference to the standard GB / T3217 permanent magnet (hard magnetic) material magnetic property test method. The results are shown in Table 2.

[0107] Table 2

[0108]

[0109] It can be seen from the above table that the grain boundary diffusion magnet prepared by using the grain boundary diffusion source of the present application has a significantly improved coercive force and a relatively small decrease in remanence, so that the grain boundary diffusion source magnet has good comprehensive performance.

[0110] It can be seen from Examples 1 to 4 that, compared with the Dy element, the use of the Tb element as the heavy rare earth element can further improve the coercive force of the NdFeB magnet.

[0111] Compared with Example 1, the diffusion source of Comparative Example 1 does not contain Sc element, and the remanence and maximum magnetic energy product of the NdFeB magnet finally obtained are slightly reduced, and the coercive force is significantly lower than that of Example 1.

[0112] Compared with Example 2, the diffusion source of Comparative Example 2 does not contain the Sc element, and the remanence of the NdFeB magnet finally obtained is reduced, and the coercive force is significantly lower than that of Example 2.

[0113] Compared with Example 3 and Example 4, in Comparative Examples 3 and Comparative Examples 4, the Sc element is replaced by the Y element, and the remanence, coercive force and maximum magnetic energy product of the NdFeB magnet finally obtained are significantly reduced.

[0114] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A grain boundary diffusion source, characterized in that: The grain boundary diffusion source includes HREE x Sc y M 100-x-y The alloy comprises: HREE represents a heavy rare earth element, M represents one or more of aluminum, copper, cobalt, gallium and zinc, and satisfies 60≤x≤95, 5≤y≤30, and 90≤x+y<100.

2. The grain boundary diffusion source according to claim 1, characterized in that: In the HREE-Sc-M alloy, the atomic percentage of the HREE element is 85% to 90%, the atomic percentage of the Sc element is 5% to 10%, and the atomic percentage of the M element is 1% to 10%.

3. The grain boundary diffusion source according to claim 1 or 2, characterized in that: The heavy rare earth element includes one or more of dysprosium and terbium.

4. A method for grain boundary diffusion of NdFeB magnets, characterized in that: The steps include: The grain boundary diffusion source described in any one of claims 1 to 3 is attached to the surface of the original NdFeB magnet, and diffusion treatment and tempering treatment are performed.

5. The grain boundary diffusion method of NdFeB magnet according to claim 4, characterized in that: The grain boundary diffusion source is used as a target material and attached to the surface of the NdFeB original magnet by magnetron sputtering.

6. The grain boundary diffusion method of NdFeB magnet according to claim 5, characterized in that: After magnetron sputtering, the thickness of the diffusion source on the surface of the NdFeB magnet is ≤100 μm.

7. The grain boundary diffusion method of NdFeB magnet according to any one of claims 4 to 6, characterized in that: The NdFeB original magnet includes at least one of a sintered NdFeB magnet and a tempered NdFeB magnet.

8. The grain boundary diffusion method of NdFeB magnet according to any one of claims 4 to 6, characterized in that: The grain boundary diffusion method satisfies at least one of the following characteristics: (1) The temperature of the diffusion treatment is 800°C to 1000°C, and the time is 1h to 50h; (2) The tempering temperature is 400℃~700℃ and the time is 1h~12h.

9. The grain boundary diffusion method of NdFeB magnet according to any one of claims 4 to 6, characterized in that: Before the grain boundary diffusion source is attached to the surface of the NdFeB original magnet, the NdFeB original magnet is pretreated to remove oxides on the surface.

10. A grain boundary diffused NdFeB magnet, characterized in that: The NdFeB magnet is prepared by the grain boundary diffusion method of any one of claims 4 to 9.

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