A high lanthanum cerium neodymium iron boron sintered permanent magnet and a preparation method thereof

Abstract

This invention belongs to the field of permanent magnet materials technology, specifically relating to a high-lanthanum-cerium NdFeB sintered permanent magnet and its preparation method. The raw materials for preparing this high-lanthanum-cerium NdFeB sintered permanent magnet include alloy one and alloy two. The chemical formula of alloy one is [(PrNd)]. 1‑x (RL) x ] a (TM) b (HM) c B d Fe 100‑a‑b‑c‑d Given the following conditions: 0.3 ≤ x < 1, 29.5 ≤ a ≤ 32.5, 0 < b ≤ 5, 0 < c ≤ 0.8, 0.85 ≤ d ≤ 1.1, the chemical formula of the alloy component II is (PrNd). a1 Ga b1 Fe 100‑a1‑b1 70≤a1≤90, 0<b1≤20. By combining alloy one and alloy two, and combining them with appropriate sintering and aging processes, high lanthanum-cerium NdFeB sintered permanent magnets are obtained, achieving surface magnetic hardening of high lanthanum-cerium main phase grains.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet materials technology, specifically relating to a high lanthanum cerium neodymium iron boron sintered permanent magnet and its preparation method. Background Technology

[0002] Neodymium iron boron magnets are tetragonal crystals formed from rare-earth neodymium, iron, and boron. With a magnetic energy product greater than that of samarium cobalt magnets, they are currently the material with the largest magnetic energy product. Due to their excellent comprehensive magnetic properties, they are known as the "King of Magnets". They are indispensable components in traditional industries such as air conditioning compressors, permanent magnet traction machines, and magnetic chucks. At the same time, they are also widely used in emerging industries that are closely related to carbon neutrality and carbon emission reduction, such as new energy drive motors and wind power generation.

[0003] With changes in market supply and demand and the international situation, the price of rare earth raw materials continues to rise, making downstream customers more sensitive to the cost of magnets. Therefore, achieving efficient utilization of rare earth elements is particularly important. As the most abundant and cheapest rare earth element in the Earth's crust, the effective use of lanthanum and cerium is especially necessary. Traditional lanthanum and cerium substitutes for praseodymium and neodymium in rare earth permanent magnet materials suffer from low intrinsic magnetic properties and poor microstructure, failing to adequately meet market demands. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems by providing a high-lanthanum-cerium NdFeB sintered permanent magnet with superior magnetic properties, thereby broadening the application of high-abundance rare-earth lanthanum and cerium in NdFeB magnets.

[0005] The technical solution of this invention provides a high-lanthanum cerium neodymium iron boron sintered permanent magnet, the raw materials for which include alloy one and alloy two, the chemical formula of alloy one being [(PrNd]]. 1-x (RL) x ] a (TM) b (HM) c B d Fe 100-a-b-c-d , 0.3≤x<1, 29.5≤a≤32.5, 0<b≤5, 0<c≤0.8, 0.85≤d≤1.1, where RL is one or two of La and Ce, TM is one or more of Al, Cu, Ga, Co, and Mn, and HM is one or more of Nb, Zr, Hf, Ti, and V.

[0006] Furthermore, the chemical formula of alloy component two is (PrNd). a1 Ga b1 Fe 100-a1-b1 , 70≤a1≤90, 0<b1≤20.

[0007] Alloy 1 maximizes the proportion of high-abundance rare-earth lanthanum and cerium, and then, through compounding with Alloy 2, achieves surface magnetohardening of high-content lanthanum and cerium main phase grains. In the high-lanthanum and cerium NdFeB sintered permanent magnet, the epitaxial layer (PrNd) / RE ratio of the main phase grains inside is ≥0.6. In addition, RE6 (Fe,TM) is formed at the grain boundaries of the magnet. 14 The compound allows for the simultaneous control of rare earth composition in the grain shell and grain boundary phase composition, resulting in higher magnetic properties.

[0008] Furthermore, the mass percentages of Alloy 1 and Alloy 2 are 95.0–99.9% and 0.1–5.0%, respectively.

[0009] Another object of the present invention is to provide a method for preparing the above-mentioned high lanthanum cerium neodymium iron boron sintered permanent magnet, comprising the following steps:

[0010] (1) After rapid solidification and melting, a thin sheet of alloy is obtained by casting.

[0011] (2) The metal is smelted and then cast to obtain alloy ingot II;

[0012] (3) Alloy 1 and Alloy 2 were hydrogen-crushed into coarse powder. After dehydrogenation treatment, Alloy 1 coarse powder was mixed evenly with Alloy 2 coarse powder, and an antioxidant was added. The powder was then milled using a two-stage air jet milling process to obtain air jet mill magnetic powder.

[0013] (4) The air-jet mill magnetic powder obtained in step (3) is oriented and shaped, vacuum-sealed and then isostatically pressed.

[0014] (5) The magnet obtained by isostatic pressing is sintered and then aged.

[0015] Retaining a small amount of hydrogen within the permanent magnet can promote coercivity to some extent; however, excessive hydrogen content can lead to product cracking. Through appropriate sintering and aging processes, two microstructures that promote coercivity enhancement are formed at the grain boundaries: uniformly distributed thin grain boundaries and a non-ferromagnetic 6:14 phase, thereby improving the overall magnetic properties within the high-lanthanum-cerium magnet.

[0016] Furthermore, in step (1), the smelting temperature is 1465~1485℃ and the casting temperature is 1405~1425℃.

[0017] Furthermore, in step (1), the thickness of the alloy sheet is 0.30 to 0.80 mm.

[0018] Furthermore, in step (2), the smelting temperature is 1485~1500℃ and the casting temperature is 1445~1455℃.

[0019] Further, in step (3), alloy one and alloy two are hydrogen-crushed into coarse powder with a particle size of 20-50 μm.

[0020] Furthermore, the temperature of the dehydrogenation treatment in step (3) is 500–580 °C.

[0021] Furthermore, in step (3), the hydrogen content of the alloy coarse powder dehydrogenation treatment is ≤1300ppm.

[0022] Furthermore, in step (3), the antioxidant is one or more of glycerol, zinc stearate, silicate, silicone oil, and n-octane.

[0023] Furthermore, in step (3), the amount of antioxidant added is 0.05 to 0.1% of the total mass of alloy one and alloy two.

[0024] Furthermore, in step (3), the first air jet milling process yields powder with an average particle size of 4.0–4.5 μm, and the second air jet milling process yields powder with an average particle size of 2.5–3.2 μm. The two-stage air jet milling process can improve the particle size distribution of the air-jet milled powder. At a similar average particle size (SMD), the higher particle size distribution is beneficial for subsequent molding and orientation, thereby improving the remanence and performance consistency of the product.

[0025] Furthermore, in step (4), the orientation current during orientation molding is 50-300A, and the molding pressure is 0.2-10MPa.

[0026] Furthermore, in step (4), the isostatic pressure during isostatic treatment is 150-200 MPa, and the holding time is 10-60 s.

[0027] Furthermore, in step (5), the vacuum degree during sintering is 0.2 to 0.5 MPa, the sintering temperature is 1010 to 1040 °C, and the sintering time is 4 to 6 h.

[0028] Furthermore, the aging treatment in step (5) adopts a two-stage aging process. The first stage aging treatment temperature is 600-860℃ and the time is 2-4h, while the second stage aging treatment temperature is 360-600℃ and the time is 3-6h. The two-stage aging can optimize the internal microstructure of the magnet, making the distribution of the thin-area grain boundary phase that enhances coercivity more uniform.

[0029] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0030] (1) In this invention, by combining alloy one and alloy two, and combining them with appropriate sintering and aging processes, a high lanthanum cerium neodymium iron boron sintered permanent magnet is obtained, thereby achieving surface magnetic hardening of high lanthanum cerium main phase grains.

[0031] (2) In high lanthanum cerium neodymium iron boron sintered permanent magnets, the ratio of the internal main phase grain epitaxial layer (PrNd) / RE is ≥0.6, and RE6 (Fe, TM) is formed at the grain boundaries of the magnet.14 The compound can simultaneously control the rare earth composition of the grain shell and the composition of the grain boundary phase, thereby obtaining higher magnetic properties.

[0032] (3) After Alloy 1 and Alloy 2 are hydrogenated into coarse powder, they are dehydrogenated to retain a small amount of hydrogen in the permanent magnet, which has a certain promoting effect on coercivity.

[0033] (4) By using secondary airflow milling, the particle size concentration of powder can be improved, which is beneficial to subsequent molding and orientation, thereby improving the remanence and performance consistency of the product.

[0034] (5) Through the optimized secondary aging, the internal microstructure of the magnet can be optimized, the distribution of the thin-area grain boundary phase is more uniform, and the coercivity of the magnet is effectively enhanced. Attached Figure Description

[0035] Figure 1 This is a low-magnification SEM image of the high lanthanum cerium neodymium iron boron sintered permanent magnet obtained in Example 1.

[0036] Figure 2 This is a high-magnification SEM image of the high-lanthanum cerium neodymium iron boron sintered permanent magnet obtained in Example 1. Detailed Implementation

[0037] 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.

[0038] Example 1

[0039] The preparation method of the high lanthanum cerium neodymium iron boron sintered permanent magnet in this embodiment includes the following steps:

[0040] (1) with [(Pr 0.2 Nd 0.8 ) 0.75 La 0.1 Ce 0.15 ] 31.0 Al 0.5 Cu 0.15 Nb 0.1 Zr 0.1 Ti 0.1 Co 0.2 Ga 0.15 B 1.0 Fe 66.7The elemental ratios were determined by melting the various metal elements at 1470℃ and casting them onto the runner at 1410℃ to obtain an alloy sheet with a thickness of 0.3mm.

[0041] (2) According to (Pr 0.2 Nd 0.8 ) 80 Ga5Fe 15 The elemental ratios were determined by melting the various metallic elements at 1490℃ and casting them at 1450℃ to obtain alloy ingot II.

[0042] (3) Alloy 1 and Alloy 2 were placed in a hydrogen crushing furnace and hydrogenated into coarse powder. The hydrogenated coarse powder of Alloy 1 was dehydrogenated in the hydrogen crushing furnace at 550°C for 4 hours. After mixing 99 parts of dehydrogenated Alloy 1 and 1 part of Alloy 2, 0.06 parts of n-octane were added. The first air jet milling yielded alloy powder with an average particle size of 4.0 μm, and the second air jet milling yielded alloy powder with an average particle size of 3.0 μm.

[0043] (4) The alloy powder obtained in step (3) was oriented and shaped under an orientation current of 100A and a forming pressure of 3.0Mpa. After vacuum sealing, it was isostatically pressed under a pressure of 160Mpa for 30s.

[0044] (5) The isostatically pressed magnet was sintered at 0.3 MPa vacuum and 1020℃ for 5 hours and then aged. The first stage of aging treatment was at 650℃ for 4 hours and the second stage of aging treatment was at 500℃ for 6 hours.

[0045] Example 2

[0046] The preparation method of the high lanthanum cerium neodymium iron boron sintered permanent magnet in this embodiment includes the following steps:

[0047] (1) According to [(Pr 0.2 Nd 0.8 ) 0.9 La 0.1 ] 30.5 Al 0.8 Cu 0.15 Nb 0.1 Zr 0.1 Ti 0.1 Co 0.2 Ga 0.15 B 1.0 Fe 66.9 The elemental ratios were determined by melting the various metal elements at 1480℃ and casting them onto the runner at 1420℃ to obtain an alloy sheet with a thickness of 0.3mm.

[0048] (2) According to (Pr 0.2 Nd 0.8 ) 80 Ga5Fe 15The elemental ratios were determined by melting the various metallic elements at 1490℃ and casting them at 1450℃ to obtain alloy ingot II.

[0049] (3) Alloy 1 and Alloy 2 were placed in a hydrogen crushing furnace and hydrogenated into coarse powder. The hydrogen-crushed coarse powder of Alloy 1 was dehydrogenated in the hydrogen crushing furnace at 520°C for 4 hours. After mixing 99 parts of dehydrogenated Alloy 1 and 1 part of Alloy 2, 0.06 parts of n-octane were added. The first air jet milling yielded alloy powder with an average particle size of 4.0 μm, and the second air jet milling yielded alloy powder with an average particle size of 3.0 μm.

[0050] (4) The alloy powder obtained in step (3) was oriented and shaped under an orientation current of 100A and a forming pressure of 5.0Mpa. After vacuum sealing, it was isostatically pressed under a pressure of 180Mpa for 20s.

[0051] (5) The isostatically pressed magnet was sintered at 0.2 MPa vacuum and 1040℃ for 4 hours and then aged. The first stage of aging treatment was at 700℃ for 4 hours and the second stage of aging treatment was at 450℃ for 6 hours.

[0052] Example 3

[0053] The only difference between this embodiment and Embodiment 1 is that in step (1), the chemical formula of alloy one is [(Pr 0.2 Nd 0.8 ) 0.6 Ce 0.4 ] 30.5 Al 0.4 Cu 0.15 Nb 0.1 Zr 0.1 Ti 0.1 Co 0.15 Ga 0.05 B 1.0 Fe 67.45 In step (2), the chemical formula of alloy 2 is (Pr 0.2 Nd 0.8 ) 85 Ga5Fe 10 .

[0054] Example 4

[0055] The only difference between this embodiment and Embodiment 1 is that the thickness of the alloy sheet in step (1) is 0.5 mm.

[0056] Example 5

[0057] The difference between this embodiment and embodiment 1 is only that in step (3), alloy one and alloy two are respectively placed in a hydrogen crushing furnace and hydrogenated into coarse powder. The hydrogen-crushed coarse powder of alloy one is dehydrogenated in the hydrogen crushing furnace at 550°C for 4 hours. After mixing 96 parts of dehydrogenated alloy one and 4 parts of alloy two, 0.06 parts of n-octane are added. The first air jet milling yields alloy powder with an average particle size of 4.0 μm, and the second air jet milling yields alloy powder with an average particle size of 3.0 μm.

[0058] Example 6

[0059] The difference between this embodiment and embodiment 1 is only that in step (3), alloy one and alloy two are respectively placed in a hydrogen crushing furnace and hydrogenated into coarse powder. The coarse powder of alloy one after hydrogen crushing is dehydrogenated in the hydrogen crushing furnace at 550°C for 4 hours. After mixing 85 parts of dehydrogenated alloy one and 15 parts of alloy two, 0.06 parts of n-octane are added. The first air jet milling yields alloy powder with an average particle size of 4.0 μm, and the second air jet milling yields alloy powder with an average particle size of 3.0 μm.

[0060] Example 7

[0061] The difference between this embodiment and embodiment 1 is only in step (3) where alloy 1 and alloy 2 are placed in a hydrogen crushing furnace and hydrogenated into coarse powder. The hydrogen-crushed coarse powder of alloy 1 is dehydrogenated in the hydrogen crushing furnace at 550°C for 4 hours. After mixing 99 parts of dehydrogenated alloy 1 and 1 part of alloy 2, 0.06 parts of n-octane are added, and alloy powder with an average particle size of 3.0 μm is obtained by one-pass air jet milling.

[0062] Example 8

[0063] The difference between this embodiment and embodiment 1 is only that in step (3), alloy one and alloy two are respectively placed in a hydrogen crushing furnace and hydrogenated into coarse powder. After hydrogen crushing, 99 parts of alloy one coarse powder and 1 part of alloy two coarse powder are mixed and 0.06 parts of n-octane are added. The first air jet milling yields alloy powder with an average particle size of 4.0 μm, and the second air jet milling yields alloy powder with an average particle size of 3.0 μm.

[0064] Example 9

[0065] The difference between this embodiment and embodiment 1 is only that in step (3), alloy one and alloy two are respectively placed in a hydrogen crushing furnace and hydrogenated into coarse powder. The coarse powder of alloy one after hydrogen crushing is dehydrogenated in the hydrogen crushing furnace at 550°C for 4 hours, and the coarse powder of alloy two after hydrogen crushing is dehydrogenated in the hydrogen crushing furnace at 550°C for 4 hours. After mixing 99 parts of dehydrogenated alloy one and 1 part of dehydrogenated alloy two, 0.06 parts of n-octane are added. The first air jet milling yields alloy powder with an average particle size of 4.0 μm, and the second air jet milling yields alloy powder with an average particle size of 3.0 μm.

[0066] Example 10

[0067] The difference between this embodiment and embodiment 1 is only that in step (3), alloy 1 and alloy 2 are respectively placed in a hydrogen crushing furnace and hydrogenated into coarse powder. The coarse powder of alloy 2 after hydrogen crushing is dehydrogenated in the hydrogen crushing furnace at 550°C for 4 hours. After mixing 99 parts of alloy 1 and 1 part of dehydrogenated alloy 2, 0.06 parts of n-octane are added. The first air jet milling yields alloy powder with an average particle size of 4.0 μm, and the second air jet milling yields alloy powder with an average particle size of 3.0 μm.

[0068] Example 11

[0069] The difference between this embodiment and embodiment 1 is that step (5) involves sintering the isostatically pressed magnet at a vacuum of 0.3 MPa and 1020°C for 5 hours, followed by aging treatment at 900°C for 6 hours.

[0070] Comparative Example 1

[0071] The preparation method of this comparative permanent magnet includes the following steps:

[0072] (1) According to [(Pr 0.2 Nd 0.8 ) 0.6 Ce 0.4 ] 30.5 Al 0.4 Cu 0.15 Nb 0.1 Zr 0.1 Ti 0.1 Co 0.15 Ga 0.05 B1Fe 67.45 The elemental ratios were determined by melting the various metal elements at 1470℃ and casting them onto the runner at 1410℃ to obtain an alloy sheet with a thickness of 0.3mm.

[0073] (2) Alloy 1 was placed in a hydrogen crushing furnace and hydrogenated into coarse powder. The coarse powder of alloy 1 after hydrogen crushing was dehydrogenated in the hydrogen crushing furnace at 550°C for 4 hours. 0.06 parts of n-octane were added. Alloy powder with an average particle size of 4.0 μm was obtained by the first air jet milling and alloy powder with an average particle size of 3.0 μm was obtained by the second air jet milling.

[0074] (3) The alloy powder obtained in step (2) was oriented and shaped under an orientation current of 100A and a forming pressure of 3.0Mpa. After vacuum sealing, it was isostatically pressed under a pressure of 160Mpa for 30s.

[0075] (4) The isostatically pressed magnet was sintered at 0.3 MPa vacuum and 1020℃ for 5 hours and then aged. The first stage of aging treatment was at 650℃ for 4 hours and the second stage of aging treatment was at 500℃ for 6 hours.

[0076] The properties of the lanthanum-cerium-containing NdFeB magnets prepared in the embodiments and comparative examples of this invention were tested according to the methods in GB / T-3217-2013 "Magnetic Test Methods for Permanent Magnet (Hard Magnetic) Materials": Br represents remanence; Hcj represents intrinsic coercivity; (BH) max The maximum magnetic energy product is shown in Table 1 below.

[0077] Table 1. Performance data of permanent magnet materials obtained from the examples and comparative examples.

[0078] Br / kGs Hcj / kOe <![CDATA[(BH) max / MGOe]]> Example 1 13.02 14.95 41.28 Example 2 13.36 16.69 43.25 Example 3 12.86 13.96 39.96 Example 4 12.91 14.85 40.45 Example 5 12.83 16.29 40.26 Example 6 12.35 18.88 38.01 Example 7 12.83 13.84 40.25 Example 8 12.41 12.68 36.27 Example 9 13.00 13.05 40.65 Example 10 12.92 12.31 36.25 Example 11 12.91 11.28 38.56 Comparative Example 1 12.90 12.12 37.52

[0079] Figure 1 The image shows a low-magnification SEM image of the high-lanthanum cerium NdFeB sintered permanent magnet obtained in Example 1. The elemental analysis results at the marked grain boundaries are shown in Table 2, indicating that a 6:14 phase is formed within the magnet. [(Pr 0.2 Nd 0.8 ) 0.75 La 0.1 Ce 0.15 ] 31.0 Al 0.5 Cu 0.15 Nb 0.1 Zr 0.1 Ti 0.1 Co 0.2 Ga 0.15 B 1.0 Fe 66.7

[0080] Table 2 Figure 1 Element analysis results at marked points

[0081] Al Fe Ga La Ce Pr Nd Line type K-line system K-line system K-line system L-line system L-line system L-line system L-line system wt% 0.50 42.97 3.90 5.82 6.98 6.60 32.23 Atomic percentage 1.52 63.45 4.61 3.46 4.11 3.86 19.00

[0082] Figure 2 The high-magnification SEM image of the high-lanthanum cerium neodymium iron boron sintered permanent magnet obtained in Example 1 is shown in Table 3. The elemental analysis results of the corresponding points of the grain boundaries at the marked locations are shown in Table 3, indicating that the epitaxial layer (PrNd) / RE of the main phase grain is ≥0.6.

[0083] Table 3 Figure 2 Table of element content data at each marked location

[0084] La / wt% Ce / wt% Pr / wt% Nd / wt% Pr+Nd / RE 1 2.08 5.85 5.07 16.03 0.727 2 3.04 6.04 4.69 16.25 0.697 3 2.92 6.02 4.94 16.02 0.701 4 2.14 5.68 4.35 16.48 0.727

[0085] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the spirit 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 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 high-lanthanum cerium neodymium iron boron sintered permanent magnet, characterized in that, The raw materials for preparation include Alloy 1 and Alloy 2. The chemical formula of Alloy 1 is [(PrNd). 1-x (RL) x ] a (TM) b (HM) c B d Fe 100-a-b-c-d , 0.3≤x<1, 29.5≤a≤32.5, 0<b≤5, 0<c≤0.8, 0.85≤d≤1.1, where RL is one or two of La and Ce, TM is one or more of Al, Cu, Ga, Co, and Mn, and HM is one or more of Nb, Zr, Hf, Ti, and V; The chemical formula of the second alloy component is (PrNd). a1 Ga b1 Fe 100-a1-b1 70≤a1≤90, 0<b1≤20; the mass percentages of Alloy 1 and Alloy 2 are 95.0~99.9% and 0.1~5.0%, respectively; The preparation method of the high lanthanum cerium neodymium iron boron sintered permanent magnet includes the following steps: (1) After rapid solidification and melting, a thin sheet of alloy is obtained by casting. (2) The metal is smelted and then cast to obtain alloy ingot II; (3) Alloy 1 and Alloy 2 were hydrogen-crushed into coarse powder. After dehydrogenation treatment, Alloy 1 coarse powder was mixed evenly with Alloy 2 coarse powder. The hydrogen content of Alloy 1 coarse powder after dehydrogenation treatment was ≤1300ppm. Antioxidant was added, and air-jet milled magnetic powder was obtained by two air-jet milling processes. The first air-jet milling yielded powder with an average particle size of 4.0 to 4.5μm, and the second air-jet milling yielded powder with an average particle size of 2.5 to 3.2μm. (4) The air-jet mill magnetic powder obtained in step (3) is oriented and shaped, vacuum-sealed and then isostatically pressed. (5) The magnet obtained by isostatic pressing is sintered and then aged.

2. A method for preparing a high-lanthanum cerium neodymium iron boron sintered permanent magnet as described in claim 1, characterized in that, Includes the following steps: (1) After rapid solidification and melting, a thin sheet of alloy is obtained by casting. (2) The metal is smelted and then cast to obtain alloy ingot II; (3) Alloy 1 and Alloy 2 were hydrogen-crushed into coarse powder. After dehydrogenation treatment, Alloy 1 coarse powder was mixed evenly with Alloy 2 coarse powder. The hydrogen content of Alloy 1 coarse powder after dehydrogenation treatment was ≤1300ppm. Antioxidant was added, and air-jet milled magnetic powder was obtained by two air-jet milling processes. The first air-jet milling yielded powder with an average particle size of 4.0 to 4.5μm, and the second air-jet milling yielded powder with an average particle size of 2.5 to 3.2μm. (4) The air-jet mill magnetic powder obtained in step (3) is oriented and shaped, vacuum-sealed and then isostatically pressed. (5) The magnet obtained by isostatic pressing is sintered and then aged.

3. The method for preparing high-lanthanum cerium neodymium iron boron sintered permanent magnets according to claim 2, characterized in that, In step (3), alloy one and alloy two are hydrogen-crushed into coarse powder with a particle size of 20-50 μm.

4. The method for preparing high-lanthanum cerium neodymium iron boron sintered permanent magnets according to claim 2, characterized in that, In step (3), the amount of antioxidant added is 0.05 to 0.1% of the total mass of Alloy 1 and Alloy 2.

5. The method for preparing high-lanthanum cerium neodymium iron boron sintered permanent magnets according to claim 2, characterized in that, In step (5), the vacuum degree during sintering is 0.2 to 0.5 MPa, the sintering temperature is 1010 to 1040 °C, and the sintering time is 4 to 6 h.

6. The method for preparing high-lanthanum cerium neodymium iron boron sintered permanent magnets according to claim 2, characterized in that, In step (5), the aging process adopts a two-stage aging process. The first stage of aging process is carried out at a temperature of 600-860℃ for 2-4 hours, and the second stage of aging process is carried out at a temperature of 360-600℃ for 3-6 hours.

Images