Neodymium iron boron magnet and method for manufacturing the same

Abstract

The present invention provides a neodymium iron boron magnet and a manufacturing method thereof. The manufacturing method includes the steps of mixing alloy A and alloy B, milling to obtain a mixed powder, pressing the mixed powder to obtain a pressed product, and sintering and tempering the pressed product in sequence to obtain a neodymium iron boron magnet in step S3. The present invention uses alloy A and alloy B with specific compositions and contents as raw materials, and processes them through multiple steps of milling, molding, sintering and tempering to manufacture a neodymium iron boron magnet. Without adding Dy and Tb, the neodymium iron boron magnet of the present invention has a greater improvement in coercivity, and good stability of remanence and magnetic performance. In addition, the manufacturing method has a simple operation process and is more advantageous for mass production.

Description

[Technical Field]

[0001] This invention relates to the field of neodymium iron boron, and more specifically to neodymium iron boron magnets and methods for manufacturing the same. [Background technology]

[0002] Among the technical indicators for magnetic materials, the magnetic energy product is the most important. The magnetic energy product represents the magnitude of the energy of the external magnetic field generated by a unit volume of magnet. A high magnetic energy product means that a motor can produce greater power with a smaller magnet.

[0003] Sintered neodymium-iron-boron magnets are currently the most powerful permanent magnetic material in the world in terms of overall magnetic performance. With superior properties and price-performance ratio that surpasses conventional permanent magnet materials, they are widely applied in fields such as energy, transportation, machinery, medicine, computers, and home appliances, playing an important role in the national economy.

[0004] Neodymium iron boron is an important rare-earth permanent magnetic material, possessing properties such as high magnetic energy product, high coercivity, light weight, and low cost. It has the best price-performance ratio to date and is known as the "king of magnets." The emergence of neodymium iron boron has led to the development of magnetic devices in the direction of higher efficiency, miniaturization, and weight reduction.

[0005] Currently, there are two main methods for increasing the coercivity of sintered NdFeB magnets in industrial production. The first is to add heavy rare earth elements such as Dy / Tb to the master alloy by directly smelting them, and then manufacture the magnet using a conventional process. However, by directly adding Dy / Tb to the main phase Nd2Fe 14 After substituting Nd in B, the new phase (Nd,Dy)2Fe was generated. 14 B and (Nd,Dy)2Fe 14 The anisotropy of phase B is greater than that of the main phase, and therefore, the coercivity of the sintered magnet can be significantly improved.

[0006] The second is the grain boundary diffusion process, and magnet samples produced using the grain boundary diffusion process are limited by the thickness of the magnet. For example, neither "High-performance sintered neodymium iron boron magnet and method for producing the same" (Patent Publication No. 201810154877.4) nor "Sintered neodymium iron boron magnet and method for producing the same" (Patent Publication No. 201210419107.0) relates to a method for producing high-performance neodymium iron boron magnets without heavy rare earth elements.

[0007] The Dy and Tb content is crucial in determining the cost of high-performance sintered neodymium iron boron materials. However, with the recent rise in the price of heavy rare earth elements, research is focusing on how to improve the coercivity of neodymium iron boron magnets by adjusting the amount of Dy and Tb added (or even omitting them).

[0008] Effects of post-sinter annealing on microstructure and magnetic properties of Nd-Fe-B sintered magnets with Nd-Ga intergranular addition [J]. Chinese Physical Society, 2021. This academic paper discloses that the coercivity of the formed sintered magnets can be improved to some extent by adjusting the content of each component in the alloy (especially the content of Nd and Ga) and the temperature of the hydrogen dissolution treatment. However, this paper also mentions Re2T 14 The B main phase is preferentially and primarily formed, Re6Fe 13 The Ga phase is formed secondarily, and Re6Fe 13 The conditions for forming the Ga phase are strict, making it unsuitable for mass production.

[0009] Furthermore, sintered magnets formed by the above method show little improvement in coercivity, and have poor stability in residual magnetism and magnetic performance.

[0010] Based on this, there is a need to provide neodymium iron boron magnets that have a simpler manufacturing process, are advantageous for mass production, have greater coercivity, and also have good residual magnetic performance and magnetic energy stability. [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] The primary objective of the present invention is to provide a neodymium iron boron magnet and a method for manufacturing the same, in order to solve the problems that, in the prior art, improving the coercivity of a neodymium iron boron magnet by reducing or omitting Dy and Tb is disadvantageous for mass production, the improvement in coercivity of the formed sintered magnet is small, and the stability of residual magnetism and magnetic performance is poor. [Means for solving the problem]

[0012] To achieve the above objective, according to one aspect of the present invention, a method for manufacturing a neodymium iron boron magnet is provided. The manufacturing method comprises: step S1, mixing alloy A and alloy B and then performing a powdering process to obtain a mixed powder; step S2, press-molding the mixed powder to obtain a pressed product; and step S3, sequentially performing sintering and tempering processes on the pressed product to obtain a neodymium iron boron magnet. The raw material components of alloy A, by weight percentage, consist of 28-35 wt% Re, 64-71.2 wt% T, and 0.8-1.0 wt% B, where Re is La, Ce, Pr, or Nd One or more of the following, T is one or more of Fe, Co, Al, Si, Cu, Nb, Zr, and Ga, and in weight percentage, the raw material components of alloy B include 40-60 wt% Re, 39.2-59.5 wt% T, and 0.5-0.8 wt% B, where Re is one or more of La, Ce, Pr, or Nd, T includes Fe and Ga, and T further includes one or more of Co, Cu, Nb, or Zr.

[0013] Furthermore, the amount of alloy B used is 1-10% of the weight of alloy A.

[0014] Furthermore, the raw material components of alloy B include 40-60 wt% Re, 0-2 wt% Co, 3-10 wt% Cu, 3-10 wt% Ga, 0-0.5 wt% Nb and / or Zr, 0.5-0.8 wt% B, and the remainder Fe.

[0015] Furthermore, the raw material components of alloy A include 30-32 wt% Nd, 1.0-2.0 wt% Co, 0.05-0.1 wt% Cu, 0.3-0.8 wt% Al, 0.1-0.15 wt% Ga, 0.12-0.15 wt% Zr, 0.9-0.92 wt% B, and the remainder Fe. The raw material components of alloy B include 40-50 wt% Nd, 1.0-1.5 wt% Co, 5-8 wt% Cu, 0.1-0.4 wt% Al, 5-8 wt% Ga, 0.2-0.3 wt% Nb, 0.65-0.75 wt% B, and the remainder Fe.

[0016] Preferably, the raw material components of alloy A include 32 wt% Nd, 1.5 wt% Co, 0.1 wt% Cu, 0.8 wt% Al, 0.1 wt% Ga, 0.15 wt% Zr, 0.9 wt% B, and the remainder Fe, and the raw material components of alloy B include 50 wt% Nd, 1.0 wt% Co, 6 wt% Cu, 0.4 wt% Al, 6 wt% Ga, 0.3 wt% Nb, 0.75 wt% B, and the remainder Fe. Alternatively, the raw material components of alloy A include 31.5 wt% Nd, 1.5 wt% Co, 0.1 wt% Cu, 0.6 wt% Al, 0.1 wt% Ga, 0.15 wt% Zr, 0.9 wt% B, and the remainder Fe, and the raw material components of alloy B include 45 wt% Nd, 1.0 wt% Co, 5 wt% Cu, 0.1 wt% Al, 5 wt% Ga, 0.3 wt% Nb, 0.7 wt% B, and the remainder Fe.

[0017] Furthermore, the average particle size of the mixed powder is 2.8–3.0 μm.

[0018] Furthermore, during the sintering process, the processing temperature is 1000-1100°C, and the processing time is 5-10 hours.

[0019] Furthermore, the annealing process includes a one-stage annealing process and a two-stage annealing process that are performed sequentially. Preferably, in the one-stage annealing process, the processing temperature is 880-920 °C, and the processing time is 2-4 h. Preferably, in the two-stage annealing process, the processing temperature is 450-550 °C, and the processing time is 4-6 h.

[0020] Furthermore, before the milling process, the manufacturing method further includes the steps of mixing alloy A and alloy B and sequentially performing a hydrogen atomization process and a dehydrogenation process. Preferably, in the dehydrogenation process, the processing temperature is 450-500 °C, and the processing time is 5-10 h. Preferably, the hydrogen content in the mixed powder is 600-1200 ppm, and the oxygen content is 1000-1500 ppm.

[0021] Furthermore, in the press forming process, the mixed powder is press formed in an orientation magnetic field with a magnetic field strength of 1.4 T or more.

[0022] To achieve the above object, according to one aspect of the present invention, a neodymium iron boron magnet is provided. The neodymium iron boron magnet is manufactured by the above manufacturing method of the neodymium iron boron magnet.

Effect of the Invention

[0023] The present invention uses alloy A and alloy B with specific components and contents as raw materials, and manufactures a neodymium iron boron magnet after processing through multiple steps of powder making, forming, sintering, and annealing. Re6Fe in the magnet 13 Ga is Re2T 14 By doping more uniformly and stably between the grain boundary surfaces of the B main phase, a blocking layer is formed. Therefore, without adding Dy and Tb, the neodymium iron boron magnet of the present invention has a greater improvement in coercivity, and the stability of residual magnetism and magnetic performance is also good. In addition, the manufacturing method has a simple operation process and is more advantageous for mass production.

Brief Description of the Drawings

[0024] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are for illustrative purposes only and do not constitute an inappropriate limitation to the present invention. [Figure 1] A flowchart of the method for manufacturing the neodymium iron boron magnet of the present invention is shown. [Modes for carrying out the invention]

[0025] It should be noted that the embodiments and features of the embodiments described herein can be combined with each other, insofar as they do not contradict each other. The present invention will be described in detail below in conjunction with the embodiments.

[0026] As explained in the background technology section, in conventional technology, improving the coercivity of neodymium iron boron magnets by reducing or omitting Dy and Tb presents problems such as being disadvantageous for mass production, having a small improvement in coercivity of the resulting sintered magnets, and having poor stability of residual magnetism and magnetic performance.

[0027] To solve this problem, the present invention provides a method for manufacturing a neodymium iron boron magnet, as shown in Figure 1, the manufacturing method includes: step S1, which involves mixing alloy A and alloy B and then performing a powdering process to obtain a mixed powder; step S2, which involves press molding the mixed powder to obtain a pressed product; and step S3, which involves sequentially performing a sintering process and a tempering process on the pressed product to obtain a neodymium iron boron magnet.

[0028] In weight percentage, the raw material components of alloy A include 28-35 wt% of Re, 64-71.2 wt% of T, and 0.8-1.0 wt% of B. Re is one or more of La, Ce, Pr, or Nd, and T is one or more of Fe, Co, Al, Si, Cu, Nb, Zr, and Ga. In weight percentage, the raw material components of alloy B include 40-60 wt% of Re, 39.2-59.5 wt% of T, and 0.5-0.8 wt% of B. Re is one or more of La, Ce, Pr, or Nd, T includes Fe and Ga, and T further includes one or more of Co, Cu, Nb, or Zr.

[0029] The present invention manufactures a neodymium iron boron magnet using alloy A and alloy B with the above specific components and contents as raw materials, after processing through multiple steps of powder making, shaping, sintering, and annealing. Re6Fe in the magnet 13 Ga to Re2T 14 By doping more uniformly and stably between the grain boundary surfaces of the Re6FeGa to Re2T B main phase, a blocking layer is formed. Therefore, without adding Dy and Tb, the neodymium iron boron magnet of the present invention has a greater improvement in coercivity and good stability of residual magnetism and magnetic performance. Also, the manufacturing method has a simple operation process and is advantageous for mass production.

[0030] Note that the above alloy A and alloy B are manufactured by ordinary smelting from their raw materials, and the specific smelting process is known in this field. For example, it is a resin transfer molding process (RTM) or a smelting process in a vacuum rapid solidification furnace.

[0031] Re6Fe 13 To further improve the doping uniformity and stability of the Re6FeGa phase, the usage amount of alloy B is preferably 1-10% of the weight of alloy A. Within this range, the neodymium iron boron magnet has a greater improvement in coercivity and better stability of magnetic performance. Also, the manufacturing method has a simple operation process and is advantageous for mass production.

[0032] To further improve the coercivity of the magnet, preferably, the raw material components of alloy B include 40-60 wt% Re, 0-2 wt% Co, 3-10 wt% Cu, 3-10 wt% Ga, 0-0.5 wt% Nb and / or Zr, 0.5-0.8 wt% B, and the remainder Fe.

[0033] In one preferred embodiment, the content of each component in alloy A is 30-32 wt% Nd, 1.0-2.0 wt% Co, 0.05-0.1 wt% Cu, 0.3-0.8 wt% Al, 0.1-0.15 wt% Ga, 0.12-0.15 wt% Zr, 0.9-0.92 wt% B, and the remainder Fe, and the content of each component in alloy B is 40-50 wt% Nd, 1.0-1.5 wt% Co, 5-8 wt% Cu, 0.1-0.4 wt% Al, 5-8 wt% Ga, 0.2-0.3 wt% Nb, 0.65-0.75 wt% B, and the remainder Fe. Based on this, the coercivity of the magnet is significantly improved, and the stability of its residual magnetism and magnetic performance is also better.

[0034] To further improve the coercivity, remanent magnetism, and stability of the magnetic performance of the magnet, more preferably, the content of each component in alloy A is 32 wt% Nd, 1.5 wt% Co, 0.1 wt% Cu, 0.8 wt% Al, 0.1 wt% Ga, 0.15 wt% Zr, 0.9 wt% B, and the remainder Fe, and the content of each component in alloy B is 50 wt% Nd, 1.0 wt% Co, 6 wt% Cu, 0.4 wt% Al, 6 wt% Ga, 0.3 wt% Nb, 0. The composition is 75 wt% B and the remainder Fe, or the content of each component in alloy A is 31.5 wt% Nd, 1.5 wt% Co, 0.1 wt% Cu, 0.6 wt% Al, 0.1 wt% Ga, 0.15 wt% Zr, 0.9 wt% B, and the remainder Fe, and the content of each component in alloy B is 45 wt% Nd, 1.0 wt% Co, 5 wt% Cu, 0.1 wt% Al, 5 wt% Ga, 0.3 wt% Nb, 0.7 wt% B, and the remainder Fe.

[0035] Preferably, the average particle size of the mixed powder is 2.8 to 3.0 μm, and in a normal distribution, 50% of the powder particles are less than 3.5 μm. In this way, the uniformity of the mixture of alloy A and alloy B is better, the subsequent molding efficiency can be further improved, and therefore the stability of the magnetic performance of the magnet is improved.

[0036] To further improve the stability of the magnetic performance of neodymium iron boron magnets, the sintering process is performed at a temperature of 1000-1100°C for 5-10 hours.

[0037] Re6Fe 13 To further achieve both doping stability and uniformity of the Ga phase, the tempering process preferably includes a one-stage tempering process and a two-stage tempering process performed sequentially. Preferably, in the one-stage tempering process, the processing temperature is 880 to 920°C and the processing time is 2 to 4 hours. Preferably, in the two-stage tempering process, the processing temperature is 450 to 550°C and the processing time is 4 to 6 hours.

[0038] Preferably, prior to the milling process, the manufacturing method further includes the steps of mixing alloy A and alloy B, followed by a hydrogenation treatment and a dehydrogenation treatment. Preferably, in the dehydrogenation treatment process, the treatment temperature is 450-500°C and the treatment time is 5-10 hours. Preferably, by pre-crushing the mixture of alloy A and alloy B through the hydrogenation treatment of the mixed powder, the subsequent milling efficiency can be further improved. After hydrogenation, the above dehydrogenation treatment operation can be used to control the hydrogen content in the mixed powder to 600-1200 ppm and the oxygen content to 1000-1500 ppm.

[0039] Preferably, during the press forming process, the mixed powder is press-formed in an oriented magnetic field with a magnetic field strength of 1.4T or higher. In this way, the product manufactured by pressing becomes more compact, alloy A and alloy B in the product are uniformly mixed, and therefore, after subsequent sintering and tempering, the intrinsic coercivity of the magnet is greatly improved, the residual magnetism is superior, the maximum magnetic energy product is superior, and the magnetic performance of the magnet is more stable.

[0040] The present invention further provides a neodymium iron boron magnet manufactured by the above-described method for manufacturing a neodymium iron boron magnet.

[0041] Based on the aforementioned reasons, the neodymium-iron-boron magnet of the present invention exhibits significantly improved coercivity without the addition of any dysprosium / terbium, better residual magnetism and magnetic performance stability, and greater advantages for mass production.

[0042] The present application will be described in more detail below, along with specific embodiments, but these embodiments should not be interpreted as limiting the scope of protection provided by this application.

[0043] Performance test: (1) Residual magnetic performance (Br) test: A permanent magnet non-destructive testing instrument NIM-10000 is used. (2) Intrinsic coercivity (Hcj) test: Use the permanent magnet non-destructive testing instrument NIM-10000. (3) Maximum magnetic energy product (BH max Test: A permanent magnet non-destructive testing instrument, NIM-10000, is used.

[0044] Example 1 Alloy A slabs are manufactured according to a formulation with weight content of 31.5 wt% (Nd,Pr), 1.5 wt% Co, 0.1 wt% Cu, 0.6 wt% Al, 0.1 wt% Ga, 0.15 wt% Zr, 0.90 wt% B, and the remainder Fe. Alloy B slabs are manufactured by a smelting process in a vacuum rapid solidification furnace according to a formulation with weight content of 45 wt% (Nd,Pr), 1.0 wt% Co, 5 wt% Cu, 0.1 wt% Al, 5 wt% Ga, 0.3 wt% Nb, 0.70 wt% B, and the remainder Fe. The weight ratio of Nd to Pr in both Alloy A and Alloy B is 2:8.

[0045] After mixing alloy A and alloy B (the amount of alloy B used is 5% of the weight of alloy A), the mixture is subjected to hydrogenation, dehydrogenation, and milling in sequence to obtain a mixed powder. The temperature for the hydrogenation and dehydrogenation treatment is 480°C, the dehydrogenation treatment time is 6 hours, and after dehydrogenation, the hydrogen content in the powder is 980 ppm and the oxygen content is 1100 ppm. The powder after hydrogenation is milled using a jet mill, and the particle size of the mixed powder satisfies a normal distribution, with an average particle size of 2.8 μm, and 50% of the powder particle size in the normal distribution is less than 3.25 μm.

[0046] The mixed powder is press-formed into a 60 × 35 × 40 (mm) block-shaped blank in an oriented magnetic field of 1.4T or higher. The blank is placed in a high-vacuum sintering furnace and sintered at 1070°C for 7 hours. Then, it is tempered in stages: 3 hours at 900°C (first stage), and 5 hours at 510°C (second stage) (second stage) to produce a neodymium iron boron magnet. A standard sample of Φ10 × 10 (mm) was tested, and the test results are shown in Table 1 below.

[0047] [Table 1]

[0048] Example 2 The only difference from Example 1 is that the amount of alloy B used is 12% of the weight of alloy A. A standard sample of Ф10×10(mm) was tested, and the test results are shown in Table 2 below.

[0049] [Table 2]

[0050] Example 3 Alloy A slabs are manufactured according to a formulation with weight content of 30 wt% (Nd,Pr), 1.0 wt% Co, 0.05 wt% Cu, 0.3 wt% Al, 0.1 wt% Ga, 0.12 wt% Zr, 0.92 wt% B, and the remainder Fe. Alloy B slabs are manufactured by smelting in a vacuum rapid solidification furnace according to a formulation with weight content of 40 wt% (Nd,Pr), 1.0 wt% Co, 8 wt% Cu, 0.1 wt% Al, 8 wt% Ga, 0.2 wt% Nb, 0.65 wt% B, and the remainder Fe. The weight ratio of Nd to Pr in both Alloy A and Alloy B is 2:8.

[0051] After mixing alloy A and alloy B (the amount of alloy B used is 6% of the weight of alloy A), the mixture is subjected to hydrogenation, dehydrogenation, and milling treatments in sequence to obtain a mixed powder. The temperature for the hydrogenation and dehydrogenation treatment is 470°C, the dehydrogenation treatment time is 6 hours, and after dehydrogenation, the hydrogen content in the powder is 1020 ppm and the oxygen content is 1060 ppm. The powder after hydrogenation is milled using a jet mill, and the particle size of the mixed powder satisfies a normal distribution, with an average particle size of 2.95 μm, and 50% of the powder particle size in the normal distribution is less than 3.42 μm.

[0052] The mixed powder is press-formed into a 70 × 50 × 35 (mm) block-shaped blank in an oriented magnetic field of 1.4T or higher. The blank is placed in a high-vacuum sintering furnace and sintered at 1060°C for 7 hours, followed by sequential tempering at 900°C for 3 hours (first stage) and 510°C for 5 hours (second stage) to produce a neodymium iron boron magnet. A standard sample of Φ10 × 10 (mm) was tested, and the test results are shown in Table 3 below.

[0053] [Table 3]

[0054] Example 4 The only difference from Example 3 is that the amount of alloy B used is 11% of the weight of alloy A. A standard sample of Φ10×10 (mm) was tested, and the test results are shown in Table 4 below.

[0055] [Table 4]

[0056] Example 5 Alloy A slab is produced by smelting in a vacuum rapid solidification furnace according to a formulation containing 32 wt% (Nd,Pr), 1.5 wt% Co, 0.1 wt% Cu, 0.8 wt% Al, 0.1 wt% Ga, 0.15 wt% Zr, 0.90 wt% B, and the remainder Fe by weight. Alloy B slab is produced by smelting in a vacuum rapid solidification furnace according to a formulation containing 50 wt% (Nd,Pr), 1.0 wt% Co, 6 wt% Cu, 0.4 wt% Al, 6 wt% Ga, 0.3 wt% Nb, 0.75 wt% B, and the remainder Fe by weight. The weight ratio of Nd to Pr in both Alloy A and Alloy B is 2:8.

[0057] After mixing alloy A and alloy B (the amount of alloy B used is 8% of the weight of alloy A), a mixed powder is obtained by sequentially performing hydrogenation, dehydrogenation, and milling treatments. The temperature for the hydrogenation and dehydrogenation treatment is 490°C, the dehydrogenation treatment time is 6 hours, and after dehydrogenation, the hydrogen content in the powder is 980 ppm and the oxygen content is 1050 ppm. The powder after hydrogenation is milled using a jet mill, and the particle size of the mixed powder satisfies a normal distribution, with an average particle size of 2.87 μm, and 50% of the powder particle size in the normal distribution is less than 3.28 μm.

[0058] The mixed powder is press-formed into a 70 × 50 × 35 (mm) block-shaped blank in an oriented magnetic field of 1.4T or higher. The blank is then placed in a high-vacuum sintering furnace and sintered at 1080°C for 7 hours. Subsequently, it is tempered in two stages: 3 hours at 900°C and 5 hours at 510°C to produce a neodymium iron boron magnet. A standard sample of Φ10 × 10 (mm) was tested, and the test results are shown in Table 5 below.

[0059] [Table 5]

[0060] Example 6 The only difference from Example 5 is that the amount of alloy B used is 13% of the weight of alloy A. A standard sample of Φ10×10 (mm) was tested, and the test results are shown in Table 6 below.

[0061] [Table 6]

[0062] Comparative Example 1 The difference from Example 1 is that the neodymium iron boron magnet is manufactured after the raw materials are jointly produced into an alloy. Specifically, Alloy C is produced by smelting in a vacuum rapid solidification furnace according to a formulation containing 32.14 wt% (Nd,Pr), 1.48 wt% Co, 0.33 wt% Cu, 0.58 wt% Al, 0.24 wt% Ga, 0.16 wt% Zr, 0.89 wt% B, and the remainder Fe by weight. Alloy C is then subjected to hydrogenation, dehydrogenation, and milling to obtain powder. The hydrogenation and dehydrogenation treatment is performed at a temperature of 480°C for 6 hours, and after dehydrogenation, the hydrogen content in the powder is 980 ppm and the oxygen content is 1100 ppm. The powder after hydrogenation is milled using a jet mill, and the particle size of the mixed powder satisfies a normal distribution, with an average particle size of 2.8 μm, and 50% of the powder particle size in the normal distribution is less than 3.25 μm. The weight ratio of Nd to Pr in both alloy A and alloy B is 2:8.

[0063] The powder is press-formed into a 60 × 35 × 40 (mm) block-shaped blank in an oriented magnetic field of 1.4T or higher. The blank is then placed in a high-vacuum sintering furnace and sintered at 1070°C for 7 hours. Subsequently, it is tempered in two stages: 3 hours at 900°C and 5 hours at 510°C to produce a neodymium iron boron magnet. A standard sample of Φ10 × 10 (mm) was tested, and the test results are shown in Table 7 below.

[0064] Comparative Example 2 The difference from Example 3 is that the neodymium iron boron magnet is manufactured after the raw materials are jointly produced into an alloy. Specifically, According to a formulation containing 30.57 wt% (Nd,Pr), 1.0 wt% Co, 0.5 wt% Cu, 0.29 wt% Al, 0.55 wt% Ga, 0.11 wt% Zr, 0.90 wt% B, and the remainder Fe by weight, alloy D slabs are produced by smelting in a vacuum rapid solidification furnace. Alloy D is extracted by hydrogenation and pulverization, and then subjected to dehydrogenation and milling to obtain powder. The temperature for hydrogenation and dehydrogenation treatment is 470°C, the dehydrogenation treatment time is 6 hours, and after dehydrogenation, the hydrogen content in the powder is 1020 ppm and the oxygen content is 1060 ppm.

[0065] The powder after hydrogen pulverization was milled using a jet mill, and the particle size distribution of the mixed powder satisfies a normal distribution, with an average particle size of 2.95 μm, and 50% of the powder particles in the normal distribution were less than 3.42 μm. The weight ratio of Nd to Pr in both alloy A and alloy B is 2:8.

[0066] The powder is press-formed into a 70 × 50 × 35 (mm) block-shaped blank in an oriented magnetic field of 1.4T or higher. The blank is then placed in a high-vacuum sintering furnace and sintered at 1060°C for 7 hours. Subsequently, it is tempered in two stages: 3 hours at 900°C and 5 hours at 510°C to produce a neodymium iron boron magnet. A standard sample of Φ10 × 10 (mm) was tested, and the test results are shown in Table 7 below.

[0067] Comparative Example 3 The difference from Example 5 is that the neodymium iron boron magnet is manufactured after the raw materials are jointly produced into an alloy. Specifically, According to a formulation containing 33.33 wt% (Nd,Pr), 1.46 wt% Co, 0.54 wt% Cu, 0.77 wt% Al, 0.54 wt% Ga, 0.14 wt% Zr, 0.02 wt% Nb, 0.89 wt% B, and the remainder Fe by weight, alloy E slabs are produced by smelting in a vacuum rapid solidification furnace. Alloy E is extracted by hydrogenation and pulverization, and then subjected to dehydrogenation and milling to obtain powder. The temperature for hydrogenation and dehydrogenation treatment was 490°C, the dehydrogenation treatment time was 6 hours, and after dehydrogenation, the hydrogen content in the powder was 980 ppm and the oxygen content was 1050 ppm.

[0068] The powder after hydrogen thawing was milled using a jet mill, and the particle size distribution of the mixed powder satisfies a normal distribution, with an average particle size of 2.87 μm, and 50% of the powder particles in the normal distribution were less than 3.28 μm. The weight ratio of Nd to Pr in both alloy A and alloy B is 2:8.

[0069] The powder is press-formed into a 70 × 50 × 35 (mm) block-shaped blank in an oriented magnetic field of 1.4T or higher. The blank is then placed in a high-vacuum sintering furnace and sintered at 1080°C for 7 hours. Subsequently, it is tempered in two stages: 3 hours at 900°C and 5 hours at 510°C to produce a neodymium iron boron magnet. A standard sample of Φ10 × 10 (mm) was tested, and the test results are shown in Table 7 below.

[0070] [Table 7]

[0071] The foregoing are merely preferred embodiments of the present invention and are not intended to limit it. Those skilled in the art can make various modifications and changes to the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for manufacturing a neodymium iron boron magnet, A step to produce an alloy A slab by smelting in a vacuum rapid solidification furnace according to a formulation containing 32 wt% Nd and Pr, 1.5 wt% Co, 0.1 wt% Cu, 0.8 wt% Al, 0.1 wt% Ga, 0.15 wt% Zr, 0.90 wt% B, and the remainder Fe by weight; and a step to produce an alloy B slab by smelting in a vacuum rapid solidification furnace according to a formulation containing 50 wt% Nd and Pr, 1.0 wt% Co, 6 wt% Cu, 0.4 wt% Al, 6 wt% Ga, 0.3 wt% Nb, 0.75 wt% B, and the remainder Fe by weight, wherein the weight ratio of Nd to Pr in both alloy A and alloy B is 2:

8. The process involves mixing alloy A and alloy B, followed by sequential hydrogenation, dehydrogenation, and milling to obtain a mixed powder, wherein the amount of alloy B used is 8% of the weight of alloy A, the temperature of the hydrogenation and dehydrogenation treatment is 490°C, the dehydrogenation treatment time is 6 hours, the hydrogen content in the powder after dehydrogenation is 980 ppm, the oxygen content is 1050 ppm, the powder after hydrogenation is milled using a jet mill, the particle size distribution of the mixed powder satisfies a normal distribution, the average particle size is 2.87 μm, and 50% of the powder particle size in the normal distribution is less than 3.28 μm. A method for producing a neodymium iron boron magnet, comprising the steps of: press-forming a mixed powder into a block-shaped blank measuring 70 × 50 × 35 (mm) in an orientation magnetic field of 1.4 T or higher; placing the blank in a high-vacuum sintering furnace; sintering it at 1080°C for 7 hours; sequentially tempering it in one stage at 900°C for 3 hours; and tempering it in two stages at 510°C for 5 hours.

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