WO2023116234A1 - 一种固液相分离扩散工艺制备高性能钕铁硼磁体的方法 - Google Patents

一种固液相分离扩散工艺制备高性能钕铁硼磁体的方法 Download PDF

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WO2023116234A1
WO2023116234A1 PCT/CN2022/129824 CN2022129824W WO2023116234A1 WO 2023116234 A1 WO2023116234 A1 WO 2023116234A1 CN 2022129824 W CN2022129824 W CN 2022129824W WO 2023116234 A1 WO2023116234 A1 WO 2023116234A1
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diffusion
heat treatment
magnet
alloy
liquid phase
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PCT/CN2022/129824
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French (fr)
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岳明
王占嘉
刘卫强
吴海慧
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北京工业大学
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets

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  • the invention relates to the technical field of rare earth magnetic materials, in particular to a method for preparing a high-performance sintered NdFeB magnet by a solid-liquid phase separation and diffusion process.
  • NdFeB (NdFeB), as the third generation rare earth permanent magnet material, has excellent magnetic properties and is known as the "magnet king".
  • the most common and effective way to improve the magnetic properties of sintered NdFeB is to use the grain boundary diffusion method to replace Nd with heavy rare earth Tb or Dy to form a (Tb/Dy) 2 Fe 14 B shell on the outer layer of the grain.
  • the grain boundary diffusion process can be divided into liquid phase diffusion (diffusion source diffuses from the surface of the magnet along the molten grain boundary phase to the interior of the magnet) and solid phase diffusion (diffusion source diffuses from the grain boundary phase to the interior of the main phase grain).
  • liquid phase diffusion and solid phase diffusion are carried out simultaneously, the diffusion depth of the diffusion source is limited, the grain boundary diffusion magnet structure gradient is large, and along the diffusion direction, anti-core shells are sequentially formed in the magnet structure (the content of diffusion sources inside the grain is higher than that in the epitaxial layer of the grain), core-shell structure, incomplete core-shell structure and pristine structure.
  • the methods to increase the depth of grain boundary diffusion mainly include low-melting point alloy method, low-melting point metal-assisted method, two-step grain boundary diffusion method (such as CN201710497739.1), cyclic cryogenic pretreatment method (such as CN202110533903.6), etc.
  • the low-melting-point alloy method and the low-melting-point metal-assisted method increase the diffusion depth by increasing the fluidity of the diffusion source, but while increasing the diffusion depth, they inevitably increase the rate of diffusion into the grain, resulting in a high concentration gradient and poor squareness. The problem still exists.
  • CN201710497739.1 adopts a two-step grain boundary diffusion process, and uses a low melting point Dy or Tb ternary alloy thin strip as a diffusion source to prepare a high-performance sintered NdFeB magnet, but it has a large concentration gradient for the diffusion source, and the core-shell structure shell Problems such as layer thickness cannot be effectively solved.
  • CN202110533903.6 generates microscopic cracks between the matrix phase and the rare earth-rich phase through cyclic cryogenic treatment.
  • the present invention provides a method for preparing high-performance sintered NdFeB magnets by solid-liquid phase separation and diffusion process.
  • the liquid phase diffusion and solid phase diffusion in the grain boundary diffusion process are separated by the new process of the present invention, the liquid phase diffusion increases the diffusion depth, and the solid phase diffusion controls the shell thickness of the core-shell structure, finally obtaining a large diffusion depth and a core-shell structure Uniform high performance grain boundary diffusion magnets.
  • the first object of the present invention is to provide a preparation method of an NdFeB magnet (see accompanying drawing 1 for its mechanism schematic diagram), comprising the following steps: carrying out a primary liquid phase diffusion heat treatment to the magnet attached to a diffusion source; Phase diffusion heat treatment; finally annealing heat treatment to obtain a diffusion magnet;
  • the magnet is made of the main phase alloy A and the auxiliary alloy B; the nominal composition of the main phase alloy A is R a Fe 100-ab B b , the nominal composition of the auxiliary alloy B is R c M 100-c , where R It is one of Pr 20 Nd 80 and Pr 25 Nd 75 alloys, M is one or more of Al, Cu, Zn, Co, and Ni, a, b, and c are weight percentages ⁇ 100 and satisfy the following Relationship: 26 ⁇ a ⁇ 32, 0.9 ⁇ b ⁇ 1.1, 55 ⁇ c ⁇ 95; the melting point of auxiliary alloy B is lower than 600°C;
  • the diffusion source is a particle containing Dy or Tb
  • the temperature of the primary liquid phase diffusion heat treatment is higher than the melting point of auxiliary alloy B and ⁇ 600°C, and the duration is 30-80h;
  • the temperature of the secondary solid phase diffusion heat treatment is 800-900°C, and the duration is 0.5-3h;
  • the temperature of the annealing heat treatment is 400-500° C., and the duration is 3-5 hours.
  • the diffusion source is a particle containing Dy or Tb with a high melting point, and a lower temperature of 400-600° C. is used for the primary liquid phase diffusion heat treatment.
  • the temperature is only higher than the melting point of the grain boundary phase, so that the diffusion source is only The solid phase diffusion into the grain is negligible.
  • the diffusion source can be diffused to the deeper area inside the magnet, while preventing the diffusion source from entering the grain;
  • the diffusion source that has entered the grain boundary phase diffuses into the grains to form a core-shell structure; finally, through annealing treatment, the grain structure can be optimized and grain defects can be reduced.
  • This method can separate the liquid phase diffusion and solid phase diffusion in the grain boundary diffusion process, the diffusion depth and the shell thickness of the core-shell structure can be controlled, avoiding the formation of the anti-core-shell structure, and can obtain a larger depth and a more uniform structure
  • the core-shell structure improves the uniformity of the diffusion magnet structure and significantly improves the squareness of the diffusion magnet.
  • the mass proportion of the above-mentioned main phase alloy A is 85%-99%, and the rest is auxiliary alloy B.
  • the particle diameter of the diffusion source is 50nm-3 ⁇ m, and the magnet weight ratio of the attachment diffusion source is 0.1%-0.5%.
  • the temperature of the above-mentioned primary liquid phase diffusion heat treatment is 400-600°C.
  • the above-mentioned attachment method adopts any one of spray coating, drop coating, and electrodeposition.
  • the preparation method comprises the following steps:
  • the main phase alloy A and the auxiliary alloy B are used to prepare the magnet;
  • the nominal composition of the main phase alloy A is R a Fe 100-ab B b
  • the nominal composition of the auxiliary alloy B is R c M 100-c
  • R It is one of Pr 20 Nd 80 and Pr 25 Nd 75 alloys
  • M is one or more of Al, Cu, Zn, Co, and Ni
  • a, b, and c are weight percentages ⁇ 100 and satisfy the following Relationship: 26 ⁇ a ⁇ 32, 0.9 ⁇ b ⁇ 1.1, 55 ⁇ c ⁇ 95; the melting point of auxiliary alloy B is lower than 600°C;
  • the diffusion source is a particle containing Dy or Tb, the particle size of the diffusion source is 50nm to 3 ⁇ m, and the weight gain ratio of the magnet attached to the diffusion source is 0.1%-0.5% ;
  • the attachment method adopts any one of spray coating, drop coating and electrodeposition;
  • the magnet attached to the diffusion source is subjected to a first-level liquid phase diffusion heat treatment, the temperature of the first-level liquid phase diffusion heat treatment is 400-600°C, and the duration is 30-80h; then the second-level solid phase diffusion heat treatment is performed, and the The temperature of the secondary solid-phase diffusion heat treatment is 800-900° C., and the duration is 0.5-3 hours; finally, annealing heat treatment is performed at 400-500° C. to obtain a diffusion magnet, and the duration is 3-5 hours.
  • the second object of the present invention is to provide a neodymium iron boron magnet prepared according to the above preparation method.
  • the present invention has beneficial effects in that:
  • the present invention adopts the solid-liquid phase separation and diffusion process to carry out the grain boundary diffusion of the designed magnet, realizing the separation of solid phase diffusion and liquid phase diffusion, liquid phase diffusion can increase the diffusion depth, and solid phase diffusion controls the shell layer of the core-shell structure Thickness, which can adjust the diffusion depth and shell thickness;
  • the present invention adopts the solid-liquid phase separation and diffusion process to avoid the formation of the anti-core-shell structure in the diffusion magnet, increase the depth of the core-shell structure, improve the uniformity and squareness of the magnet structure, and comprehensively improve the magnetic properties of the diffusion magnet ;
  • the present invention adopts the solid-liquid phase separation and diffusion process to improve the effective utilization rate of Dy and Tb, and save heavy rare earth resources.
  • Figure 1 is a schematic diagram of the solid-liquid phase coordinated diffusion process and the solid-liquid phase separation diffusion process.
  • main phase alloy A is (Pr 20 Nd 80 ) 29 Fe 70 B (wt.%)
  • auxiliary alloy B is (Pr 20 Nd 80 ) 70 Cu 30 (wt.%)
  • preparation A, B Two kinds of components quick-setting thin strips, hydrogen crushing and dehydrogenation to obtain coarse crushing magnetic powder, and then jet milling to obtain a fine powder of 3 ⁇ m.
  • the two components of A and B are mixed according to the mass ratio of 95:5. After the mass ratio is 95:5, they are fully mixed and oriented and formed in an inert gas protective atmosphere to obtain a green body.
  • the green body is vacuum-packaged for cooling After isostatic pressing, put it into a vacuum sintering furnace for sintering, keep it at a sintering temperature of 1050°C for 2 hours, then pass through argon air cooling, then perform a primary heat treatment at 900°C for 4 hours, and then perform a secondary heat treatment at 450°C. The time is 4h, and magnet C is obtained.
  • main phase alloy A is (Pr 20 Nd 80 ) 29 Fe 70 B (wt.%)
  • auxiliary alloy B is (Pr 20 Nd 80 ) 70 Cu 30 (wt.%)
  • preparation A, B Two kinds of components quick-setting thin strips, hydrogen crushing and dehydrogenation to obtain coarse crushing magnetic powder, and then jet milling to obtain a fine powder of 3 ⁇ m.
  • the two components of A and B are mixed according to the mass ratio of 95:5. After the mass ratio is 95:5, they are fully mixed and oriented and formed in an inert gas protective atmosphere to obtain a green body.
  • the green body is vacuum-packaged for cooling After isostatic pressing, put it into a vacuum sintering furnace for sintering, keep it at a sintering temperature of 1050°C for 2 hours, then pass through argon air cooling, then perform a primary heat treatment at 900°C for 4 hours, and then perform a secondary heat treatment at 450°C. The time is 4h, and magnet C is obtained.
  • the magnet C Cut the magnet C into thicknesses of 4mm and 8mm along the orientation direction, configure ethanol and TbH 3 nanoparticles according to the ratio of 2ml: 1g with TbH 3 nanoparticle ethanol suspension as the diffusion source, and spray the diffusion source on the magnets with two thicknesses Surface and blow dry, the weight gain ratio is 0.50%, put it in a vacuum diffusion furnace, evacuate to below 3 ⁇ 10 -3 Pa, conduct diffusion heat treatment at 880°C for 3h, and then perform annealing heat treatment at 500°C for time For 3h, diffusion magnets C 1 (4 mm) and C 2 (8 mm) were obtained.
  • main phase alloy A is (Pr 20 Nd 80 ) 29 Fe 70 B (wt.%)
  • auxiliary alloy B is (Pr 20 Nd 80 ) 70 Cu 30 (wt.%)
  • preparation A, B Two kinds of components quick-setting thin strips, hydrogen crushing and dehydrogenation to obtain coarse crushing magnetic powder, and then jet milling to obtain a fine powder of 3 ⁇ m.
  • the two components of A and B are mixed according to the mass ratio of 95:5. After the mass ratio is 95:5, they are fully mixed and oriented and formed in an inert gas protective atmosphere to obtain a green body.
  • the green body is vacuum-packaged for cooling After isostatic pressing, put it into a vacuum sintering furnace for sintering, keep it at a sintering temperature of 1050°C for 2 hours, then pass through argon air cooling, then perform a primary heat treatment at 900°C for 4 hours, and then perform a secondary heat treatment at 450°C. The time is 4h, and magnet C is obtained.
  • main phase alloy A is (Pr 20 Nd 80 ) 29 Fe 70 B (wt.%)
  • auxiliary alloy B is (Pr 20 Nd 80 ) 70 Cu 30 (wt.%)
  • preparation A, B Two kinds of components quick-setting thin strips, hydrogen crushing and dehydrogenation to obtain coarse crushing magnetic powder, and then jet milling to obtain a fine powder of 3 ⁇ m.
  • the two components of A and B are mixed according to the mass ratio of 95:5. After the mass ratio is 95:5, they are fully mixed and oriented and formed in an inert gas protective atmosphere to obtain a green body.
  • the green body is vacuum-packaged for cooling After isostatic pressing, put it into a vacuum sintering furnace for sintering, keep it at a sintering temperature of 1050°C for 2 hours, then pass through argon air cooling, then perform a primary heat treatment at 900°C for 4 hours, and then perform a secondary heat treatment at 450°C. The time is 4h, and magnet C is obtained.
  • main phase alloy A is (Pr 20 Nd 80 ) 29 Fe 70 B (wt.%)
  • auxiliary alloy B is (Pr 20 Nd 80 ) 70 Cu 30 (wt.%)
  • preparation A, B Two kinds of components quick-setting thin strips, hydrogen crushing and dehydrogenation to obtain coarse crushing magnetic powder, and then jet milling to obtain a fine powder of 3 ⁇ m.
  • the two components of A and B are mixed according to the mass ratio of 95:5. After the mass ratio is 95:5, they are fully mixed and oriented and formed in an inert gas protective atmosphere to obtain a green body.
  • the green body is vacuum-packaged for cooling After isostatic pressing, put it into a vacuum sintering furnace for sintering, keep it at a sintering temperature of 1050°C for 2 hours, then pass through argon air cooling, then perform a primary heat treatment at 900°C for 4 hours, and then perform a secondary heat treatment at 450°C. The time is 4h, and magnet C is obtained.
  • main phase alloy A is (Pr 20 Nd 80 ) 29 Fe 70 B (wt.%)
  • auxiliary alloy B is (Pr 20 Nd 80 ) 70 Cu 30 (wt.%)
  • preparation A, B Two kinds of components quick-setting thin strips, hydrogen crushing and dehydrogenation to obtain coarse crushing magnetic powder, and then jet milling to obtain a fine powder of 3 ⁇ m.
  • the two components of A and B are mixed according to the mass ratio of 95:5. After the mass ratio is 95:5, they are fully mixed and oriented and formed in an inert gas protective atmosphere to obtain a green body.
  • the green body is vacuum-packaged for cooling After isostatic pressing, put it into a vacuum sintering furnace for sintering, keep it at a sintering temperature of 1050°C for 2 hours, then pass through argon air cooling, then perform a primary heat treatment at 900°C for 4 hours, and then perform a secondary heat treatment at 450°C. The time is 4h, and magnet C is obtained.
  • Table 1 shows the comparison results of the remanence, coercive force, maximum energy product and squareness of the magnets in the above comparative examples and examples.
  • the invention provides a method for preparing a high-performance NdFeB magnet by a solid-liquid phase separation and diffusion process.
  • the magnet attached with the diffusion source is subjected to the first-level liquid phase diffusion heat treatment, the temperature is higher than the melting point of the auxiliary alloy B and ⁇ 600°C, and the duration is 30-80h; then the second-level solid phase diffusion heat treatment is performed, the temperature is 800-900°C, and the duration is 0.5- 3h; finally annealing heat treatment at a temperature of 400-500°C for 3-5h;
  • the magnet is made from the main phase alloy A being R a Fe 100-ab B b and the auxiliary alloy B being R c M 100-c , wherein R is Pr 20 Nd 80 or Pr 25 Nd 75 alloy, M is one or more of Al, Cu, Zn, Co, Ni, a, b, c are weight percentages ⁇ 100 and satisfy: 26 ⁇ a ⁇ 32, 0.9 ⁇ b ⁇ 1.1, 55 ⁇ c ⁇ 95; the melting point of

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Abstract

本发明提供涉及一种固液相分离扩散工艺制备高性能钕铁硼磁体的方法。将附着扩散源的磁体进行一级液相扩散热处理，温度高于辅合金B的熔点且≤600℃，时长30-80h；而后进行二级固相扩散热处理，温度800-900℃，时长0.5-3h；最后进行退火热处理，温度400-500℃，时长3-5h；磁体由主相合金A为R aFe 100-a-bB b和辅合金B为R cM 100-c制得，其中R为Pr 20Nd 80或Pr 25Nd 75合金，M为Al、Cu、Zn、Co、Ni中的一种或几种，a、b、c为重量百分含量×100且满足：26≤a≤32，0.9≤b≤1.1，55≤c≤95；辅合金B的熔点低于600℃。

Description

一种固液相分离扩散工艺制备高性能钕铁硼磁体的方法
交叉引用
本申请要求2021年12月21日提交的专利名称为“一种固液相分离扩散工艺制备高性能钕铁硼磁体的方法”的第202111574432X号中国专利申请的优先权，其全部公开内容通过引用整体并入本文。
技术领域
本发明涉及稀土磁性材料技术领域，具体涉及一种固液相分离扩散工艺制备高性能烧结钕铁硼磁体的方法。
背景技术
钕铁硼(NdFeB)作为第三代稀土永磁材料，具有优异的磁性能，具有“磁王”之称。近年来，混合动力汽车与风力发电等产业的迅速发展，对烧结NdFeB磁体的性能提出了越来越高的要求。采用晶界扩散方法，以重稀土Tb或Dy取代Nd在晶粒外层形成(Tb/Dy) 2Fe 14B壳层是提高烧结NdFeB磁性能最常见、最有效的方法。晶界扩散过程可以分为液相扩散(扩散源从磁体表面沿熔融的晶界相向磁体内部扩散)和固相扩散(扩散源由晶界相向主相晶粒内部扩散)。在传统热处理工艺(固液相协同扩散)中，液相扩散和固相扩散是同时进行的，扩散源扩散深度有限，晶界扩散磁体结构梯度大，沿扩散方向，磁体中依次形成了反核壳结构(晶粒内部的扩散源含量高于晶粒外延层)、核壳结构、不完整核壳结构和原始结构。不同的结构具有不同的磁畴反转场，显著的结构梯度，导致磁体方形度出现降低，且磁体厚度越大，扩散磁体方形度下降越明显。另外，Dy或Tb扩散进入晶粒内部形成反核壳结构还会导致剩磁的显著下降。
目前，提高晶界扩散深度的方法主要有低熔点合金法、低熔点金属辅助法、两步晶界扩散法(如CN201710497739.1)、循环深冷预处理法(如CN202110533903.6)等。低熔点合金法和低熔点金属辅助法是通过提高扩散源的流动性增加扩散深度，但其在增加扩散深度的同时，不免也增加 了向晶粒内部扩散的速率，浓度梯度高，方形度差的问题依然存在。CN201710497739.1采用两步晶界扩散工艺，以低熔点的Dy或Tb的三元合金薄带为扩散源，制备高性能烧结钕铁硼磁体，但是其对于扩散源浓度梯度大，核壳结构壳层厚等问题，并不能有效地解决。而CN202110533903.6通过循环深冷处理，在基体相和富稀土相之间产生微观裂纹，这些微观裂纹可以作为晶界扩散的有效通道，提高了重稀土元素晶界扩散的深度，但是这些裂纹会降低磁体的力学性能，同时，裂纹会造成磁体内部缺陷，缺陷位置很可能会成为退磁过程中反向畴的形核点，导致磁体矫顽力下降。
发明内容
为了解决上述技术问题，本发明提供了一种固液相分离扩散工艺制备高性能烧结钕铁硼磁体的方法。通过本发明的新工艺将晶界扩散过程中的液相扩散和固相扩散进行分离，液相扩散增加扩散深度，固相扩散控制核壳结构壳层厚度，最终得到扩散深度大、核壳结构均一的高性能晶界扩散磁体。
本发明的第一目的是提供一种钕铁硼磁体的制备方法(其机理示意图见附图1)，包括以下步骤：将附着扩散源的磁体进行一级液相扩散热处理；而后进行二级固相扩散热处理；最后进行退火热处理得到扩散磁体；
所述磁体由主相合金A和辅合金B制得；所述主相合金A的名义成分为R aFe 100-a-bB b，辅合金B的名义成分为R cM 100-c，其中R为Pr 20Nd 80、Pr 25Nd 75合金中的一种，M为Al、Cu、Zn、Co、Ni中的一种或几种，a、b、c为重量百分含量×100且满足以下关系：26≤a≤32，0.9≤b≤1.1，55≤c≤95；辅合金B的熔点低于600℃；
所述扩散源为含Dy或Tb的颗粒；
所述一级液相扩散热处理的温度高于辅合金B的熔点且≤600℃，时长为30-80h；
所述二级固相扩散热处理的温度为800-900℃，时长为0.5-3h；
所述退火热处理的温度为400-500℃，时长为3-5h。
本发明采用扩散源为高熔点含Dy或Tb的颗粒，采用更低的温度400-600℃进行一级液相扩散热处理，该温度仅高于晶界相熔点，使得扩散源仅沿熔融的晶界相进行扩散，向晶粒中的固相扩散可忽略不计，通过一级液相扩散热处理，可将扩散源扩散至磁体内部较深的区域，同时避免扩散源进入晶粒；在二级固相扩散热处理过程中，已经进入晶界相中的扩散源向晶粒中扩散，形成核壳结构；最后通过退火处理，可以优化晶粒结构，减少晶粒缺陷。通过本方法可将晶界扩散过程中的液相扩散和固相扩散进行分离，扩散深度和核壳结构壳层厚度可控，避免了反核壳结构的形成，可获得深度更大、结构更均一的核壳结构，改善了扩散磁体结构的均匀性，显著提高了扩散磁体的方形度。
作为优选，上述主相合金A所占的质量比例为85％～99％，其余为辅合金B。
作为优选，上述扩散源的粒径为50nm～3μm，附着扩散源的磁体增重比为0.1％-0.5％。
作为优选，上述一级液相扩散热处理的温度为400-600℃。
作为优选，上述附着方法采用喷涂、滴涂、电沉积中的任意一种。
作为本发明的最优选实施方案，制备方法包括以下步骤：
(1)采用主相合金A和辅合金B制备磁体；所述主相合金A的名义成分为R aFe 100-a-bB b，辅合金B的名义成分为R cM 100-c，其中R为Pr 20Nd 80、Pr 25Nd 75合金中的一种，M为Al、Cu、Zn、Co、Ni中的一种或几种，a、b、c为重量百分含量×100且满足以下关系：26≤a≤32，0.9≤b≤1.1，55≤c≤95；辅合金B的熔点低于600℃；
(2)将扩散源附着在磁体上下表面；所述扩散源为含Dy或Tb的颗粒，所述扩散源的粒径为50nm～3μm，附着扩散源的磁体增重比为0.1％-0.5％；所述附着方法采用喷涂、滴涂、电沉积中的任意一种；
(3)将附着扩散源的磁体进行一级液相扩散热处理，所述一级液相 扩散热处理的温度为400-600℃，时长为30-80h；而后进行二级固相扩散热处理，所述二级固相扩散热处理的温度为800-900℃，时长为0.5-3h；最后在400-500℃进行退火热处理得到扩散磁体，时长为3-5h。
本发明的第二目的是提供一种根据上述制备方法制得的钕铁硼磁体。
本发明与现有技术相比有益效果在于：
(1)本发明采用固液相分离扩散工艺对设计磁体进行晶界扩散，实现了固相扩散和液相扩散的分离，液相扩散可增加扩散深度，固相扩散控制核壳结构的壳层厚度，可对扩散深度及壳层厚度进行调控；
(2)本发明采用固液相分离扩散工艺避免了扩散磁体中反核壳结构的形成，增加了核壳结构的深度，改善了磁体结构的均匀性和方形度，全面提高了扩散磁体的磁性能；
(3)本发明采用固液相分离扩散工艺提高了Dy、Tb的有效利用率，节省了重稀土资源。
附图说明
图1为固液相协同扩散工艺和固液相分离扩散工艺机理示意图。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将对本发明实施例中的技术方案进行清楚、完整地描述，以下实施例用于说明本发明，但不用来限制本发明的范围。
实施例中未注明具体技术或条件者，均为常规方法或者按照本领域的文献所描述的技术或条件进行，或者按照产品说明书进行。所用试剂和仪器等未注明生产厂商者，均为可通过正规渠道商购买得到的常规产品。
对比例1
根据主相合金A的名义成分为(Pr 20Nd 80) 29Fe 70B(wt.％)，辅合金B的名义成分为(Pr 20Nd 80) 70Cu 30(wt.％)，制备A、B两种成分速凝薄带，进行氢破碎并脱氢后得到粗破碎磁粉，然后进行气流磨制粉，得到3μm的细粉。
在手套箱中将A、B两种成分气流磨细粉按质量比95:5进行混合，充分混合均匀后，在惰性气体保护气氛下，取向成型，得到生坯，将生坯真空封装进行冷等静压后放入真空烧结炉中进行烧结，在烧结温度1050℃保温2小时后通氩气风冷，之后在900℃进行一级热处理，时间为4h，然后在450℃进行二级热处理，时间为4h，得到磁体C。
将制备好的磁体C进行BH测试，结果如下:
原始磁体C：B r＝14.24kG，H cj＝13.63kOe，(BH) max＝49.20MGOe，H k/H cj＝96.1％
对比例2
根据主相合金A的名义成分为(Pr 20Nd 80) 29Fe 70B(wt.％)，辅合金B的名义成分为(Pr 20Nd 80) 70Cu 30(wt.％)，制备A、B两种成分速凝薄带，进行氢破碎并脱氢后得到粗破碎磁粉，然后进行气流磨制粉，得到3μm的细粉。
在手套箱中将A、B两种成分气流磨细粉按质量比95:5进行混合，充分混合均匀后，在惰性气体保护气氛下，取向成型，得到生坯，将生坯真空封装进行冷等静压后放入真空烧结炉中进行烧结，在烧结温度1050℃保温2小时后通氩气风冷，之后在900℃进行一级热处理，时间为4h，然后在450℃进行二级热处理，时间为4h，得到磁体C。
将磁体C沿取向方向分别切割成厚度4mm和8mm，将乙醇和TbH 3纳米颗粒按照2ml：1g的比例配置TbH 3纳米颗粒乙醇悬浊液作为扩散源，将扩散源喷涂在两种厚度磁体上下表面并吹干，增重比为0.50％，置于真空扩散炉中，抽真空至3×10 -3Pa以下，在880℃进行扩散热处理，时间为3h，然后在500℃进行退火热处理，时间为3h，得到扩散磁体C 1(4mm)和C 2(8mm)。
将制备好的C 1、C 2两种厚度的磁体进行BH测试，结果如下:
扩散磁体C 1：B r＝14.08kG，H cj＝20.58kOe，(BH) max＝47.96MGOe，H k/H cj＝92.8％
扩散磁体C 2：B r＝14.13kG，H cj＝19.10kOe，(BH) max＝48.24MGOe，H k/H cj＝83.5％
对比例3
根据主相合金A的名义成分为(Pr 20Nd 80) 29Fe 70B(wt.％)，辅合金B的名义成分为(Pr 20Nd 80) 70Cu 30(wt.％)，制备A、B两种成分速凝薄带，进行氢破碎并脱氢后得到粗破碎磁粉，然后进行气流磨制粉，得到3μm的细粉。
在手套箱中将A、B两种成分气流磨细粉按质量比95:5进行混合，充分混合均匀后，在惰性气体保护气氛下，取向成型，得到生坯，将生坯真空封装进行冷等静压后放入真空烧结炉中进行烧结，在烧结温度1050℃保温2小时后通氩气风冷，之后在900℃进行一级热处理，时间为4h，然后在450℃进行二级热处理，时间为4h，得到磁体C。
将磁体C沿取向方向分别切割成厚度4mm和8mm，将乙醇和DyH 3纳米颗粒按照2ml：1g的比例配置DyH 3纳米颗粒乙醇悬浊液作为扩散源，将扩散源喷涂在两种厚度磁体上下表面并吹干，增重比为0.50％，置于真空扩散炉中，抽真空至3×10 -3Pa以下，在880℃进行扩散热处理，时间为3h，然后在500℃进行退火热处理，时间为3h，得到扩散磁体C 3(4mm)和C 4(8mm)。
将制备好的C 3、C 4两种厚度的磁体进行BH测试，结果如下:
扩散磁体C 3：B r＝14.10kG，H cj＝17.63kOe，(BH) max＝48.03MGOe，H k/H cj＝91.8％
扩散磁体C 4：B r＝14.16kG，H cj＝16.36kOe，(BH) max＝48.36MGOe，H k/H cj＝82.3％
实施例1
根据主相合金A的名义成分为(Pr 20Nd 80) 29Fe 70B(wt.％)，辅合金B的名义成分为(Pr 20Nd 80) 70Cu 30(wt.％)，制备A、B两种成分速凝薄带，进行氢破碎并脱氢后得到粗破碎磁粉，然后进行气流磨制粉，得到3μm的细 粉。
在手套箱中将A、B两种成分气流磨细粉按质量比95:5进行混合，充分混合均匀后，在惰性气体保护气氛下，取向成型，得到生坯，将生坯真空封装进行冷等静压后放入真空烧结炉中进行烧结，在烧结温度1050℃保温2小时后通氩气风冷，之后在900℃进行一级热处理，时间为4h，然后在450℃进行二级热处理，时间为4h，得到磁体C。
将磁体C沿取向方向分别切割成厚度4mm和8mm，将乙醇和TbH 3纳米颗粒按照2ml：1g的比例配置TbH 3纳米颗粒乙醇悬浊液作为扩散源，将扩散源喷涂在两种厚度磁体上下表面并吹干，增重比为0.25％，置于真空扩散炉中，抽真空至3×10 -3Pa以下，先在580℃进行低温液相扩散热处理，时间为50h，之后在880℃进行高温固相扩散热处理，时间为3h，然后在500℃进行退火热处理，时间为3h，得到扩散磁体C 5(4mm)和C 6(8mm)。
将制备好的C 5、C 6两种厚度的磁体进行BH测试，结果如下:
扩散磁体C 5：B r＝14.26kG，H cj＝20.83kOe，(BH) max＝49.56MGOe，H k/H cj＝96.3％
扩散磁体C 6：B r＝14.30kG，H cj＝20.25kOe，(BH) max＝49.83MGOe，H k/H cj＝93.2％
实施例2
根据主相合金A的名义成分为(Pr 20Nd 80) 29Fe 70B(wt.％)，辅合金B的名义成分为(Pr 20Nd 80) 70Cu 30(wt.％)，制备A、B两种成分速凝薄带，进行氢破碎并脱氢后得到粗破碎磁粉，然后进行气流磨制粉，得到3μm的细粉。
在手套箱中将A、B两种成分气流磨细粉按质量比95:5进行混合，充分混合均匀后，在惰性气体保护气氛下，取向成型，得到生坯，将生坯真空封装进行冷等静压后放入真空烧结炉中进行烧结，在烧结温度1050℃保温2小时后通氩气风冷，之后在900℃进行一级热处理，时间为 4h，然后在450℃进行二级热处理，时间为4h，得到磁体C。
将磁体C沿取向方向分别切割成厚度4mm和8mm，将乙醇和TbH 3纳米颗粒按照2ml：1g的比例配置TbH 3纳米颗粒乙醇悬浊液作为扩散源，将扩散源喷涂在两种厚度磁体上下表面并吹干，增重比为0.50％，置于真空扩散炉中，抽真空至3×10 -3Pa以下，先在580℃进行低温液相扩散热处理，时间为50h，之后在880℃进行高温固相扩散热处理，时间为3h，然后在500℃进行退火热处理，时间为3h，得到扩散磁体C 7(4mm)和C 8(8mm)。
将制备好的C 7、C 8两种厚度的磁体进行BH测试，结果如下:
扩散磁体C 7：B r＝14.23kG，H cj＝22.03kOe，(BH) max＝49.17MGOe，H k/H cj＝96.4％
扩散磁体C 8：B r＝14.25kG，H cj＝21.36kOe，(BH) max＝49.43MGOe，H k/H cj＝92.5％
实施例3
根据主相合金A的名义成分为(Pr 20Nd 80) 29Fe 70B(wt.％)，辅合金B的名义成分为(Pr 20Nd 80) 70Cu 30(wt.％)，制备A、B两种成分速凝薄带，进行氢破碎并脱氢后得到粗破碎磁粉，然后进行气流磨制粉，得到3μm的细粉。
在手套箱中将A、B两种成分气流磨细粉按质量比95:5进行混合，充分混合均匀后，在惰性气体保护气氛下，取向成型，得到生坯，将生坯真空封装进行冷等静压后放入真空烧结炉中进行烧结，在烧结温度1050℃保温2小时后通氩气风冷，之后在900℃进行一级热处理，时间为4h，然后在450℃进行二级热处理，时间为4h，得到磁体C。
将磁体C沿取向方向分别切割成厚度4mm和8mm，将乙醇和DyH 3纳米颗粒按照2ml：1g的比例配置DyH 3纳米颗粒乙醇悬浊液作为扩散源，将扩散源喷涂在两种厚度磁体上下表面并吹干，增重比为0.50％，置于真空扩散炉中，抽真空至3×10 -3Pa以下，先在580℃进行低温液相扩散热 处理，时间为50h，之后在880℃进行高温固相扩散热处理，时间为3h，然后在500℃进行退火热处理，时间为3h，得到扩散磁体C 9(4mm)和C 10(8mm)。
将制备好的C 9、C 10两种厚度的磁体进行BH测试，结果如下:
扩散磁体C 9：B r＝14.23kG，H cj＝18.82kOe，(BH) max＝48.99MGOe，H k/H cj＝95.8％
扩散磁体C 10：B r＝14.26kG，H cj＝17.75kOe，(BH) max＝49.48MGOe，H k/H cj＝91.6％
以上对比例和实施例中各磁体的剩磁、矫顽力、最大磁能积和方形度的比较结果如表1所示。
表1 对比例和实施例中各磁体的剩磁、矫顽力、最大磁能积和方形度
Figure PCTCN2022129824-appb-000001
虽然，上文中已经用一般性说明及具体实施方案对本发明作了详尽的描述，但在本发明基础上，可以对之作一些修改或改进，这对本领域技术人员而言是显而易见的。因此，在不偏离本发明精神的基础上所做的这些 修改或改进，均属于本发明要求保护的范围。
工业实用性
本发明提供一种固液相分离扩散工艺制备高性能钕铁硼磁体的方法。将附着扩散源的磁体进行一级液相扩散热处理，温度高于辅合金B的熔点且≤600℃，时长30-80h；而后进行二级固相扩散热处理，温度800-900℃，时长0.5-3h；最后进行退火热处理，温度400-500℃，时长3-5h；所述磁体由主相合金A为R aFe 100-a-bB b和辅合金B为R cM 100-c制得，其中R为Pr 20Nd 80或Pr 25Nd 75合金，M为Al、Cu、Zn、Co、Ni中的一种或几种，a、b、c为重量百分含量×100且满足：26≤a≤32，0.9≤b≤1.1，55≤c≤95；辅合金B的熔点低于600℃。本发明的固液相分离扩散工艺制备高性能钕铁硼磁体的方法具有较好的经济价值和应用前景。

Claims (8)

  1. 一种钕铁硼磁体的制备方法，其特征在于，包括以下步骤：将附着扩散源的磁体进行一级液相扩散热处理；而后进行二级固相扩散热处理；最后进行退火热处理得到扩散磁体；
    所述磁体由主相合金A和辅合金B制得；所述主相合金A的名义成分为R aFe 100-a-bB b，辅合金B的名义成分为R cM 100-c，其中R为Pr 20Nd 80、Pr 25Nd 75合金中的一种，M为Al、Cu、Zn、Co、Ni中的一种或几种，a、b、c为重量百分含量×100且满足以下关系：26≤a≤32，0.9≤b≤1.1，55≤c≤95；辅合金B的熔点低于600℃；
    所述扩散源为含Dy或Tb的颗粒；
    所述一级液相扩散热处理的温度高于辅合金B的熔点且≤600℃，时长为30-80h；
    所述二级固相扩散热处理的温度为800-900℃，时长为0.5-3h；
    所述退火热处理的温度为400-500℃，时长为3-5h。
  2. 根据权利要求1所述的制备方法，其特征在于，所述主相合金A所占的质量比例为85％～99％。
  3. 根据权利要求1或2所述的制备方法，其特征在于，所述扩散源的粒径为50nm～3μm。
  4. 根据权利要求1～3中任一项所述的制备方法，其特征在于，所述附着扩散源的磁体增重比为0.1％-0.5％。
  5. 根据权利要求1～4中任一项所述的制备方法，其特征在于，所述一级液相扩散热处理的温度为400-600℃。
  6. 根据权利要求1～5中任一项所述的制备方法，其特征在于，所述附着方法采用喷涂、滴涂、电沉积中的任意一种。
  7. 根据权利要求1～6所述的制备方法，其特征在于，包括以下步骤：
    (1)采用主相合金A和辅合金B制备磁体；所述主相合金A的名义成分为R aFe 100-a-bB b，辅合金B的名义成分为R cM 100-c，其中R为Pr 20Nd 80、 Pr 25Nd 75合金中的一种，M为Al、Cu、Zn、Co、Ni中的一种或几种，a、b、c为重量百分含量×100且满足以下关系：26≤a≤32，0.9≤b≤1.1，55≤c≤95；辅合金B的熔点低于600℃；
    (2)将扩散源附着在磁体上下表面；所述扩散源为含Dy或Tb的颗粒，所述扩散源的粒径为50nm～3μm，附着扩散源的磁体增重比为0.1％-0.5％；所述附着方法采用喷涂、滴涂、电沉积中的任意一种；
    (3)将附着扩散源的磁体进行一级液相扩散热处理，所述一级液相扩散热处理的温度为400-600℃，时长为30-80h；而后进行二级固相扩散热处理，所述二级固相扩散热处理的温度为800-900℃，时长为0.5-3h；最后在400-500℃进行退火热处理得到扩散磁体，时长为3-5h。
  8. 一种钕铁硼磁体，其特征在于，其通过权利要求1～7所述的制备方法制得。
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