Method for preparing samarium-cobalt permanent magnet material based on pre-aging treatment

Abstract

The invention provides a method for preparing a samarium-cobalt permanent magnet material based on pre-aging treatment, and relates to the technical field of samarium-cobalt permanent magnet materials. The invention discloses a method for preparing a samarium cobalt permanent magnet material based on pre-aging treatment. The method comprises the steps of precursor preparation, solution treatment, pre-aging treatment, rapid cooling, main aging treatment and the like. Through pre-aging treatment, segregation of solute atoms is promoted at low temperature, high-concentration point defects are formed, uniform and high-density nucleation sites are provided for main aging Sm (Co, Cu) 5 cell wall phase precipitation, precipitation kinetics is accelerated, a nano cellular structure is refined, fine regulation and control of a microstructure are achieved, and the mechanical properties of the Sm (Co, Cu) 5 are improved. The intrinsic coercive force of the magnet is remarkably improved, the residual magnetism and the maximum magnetic energy product of the magnet are synergistically improved, and the prepared samarium-cobalt permanent magnet material is higher in cell wall density, more uniform in distribution and more excellent in comprehensive magnetic performance.

Description

Technical Field

[0001] This invention relates to the field of samarium cobalt permanent magnet materials technology, and in particular to a method for preparing samarium cobalt permanent magnet materials based on pre-aging treatment. Background Technology

[0002] In rare earth-cobalt intermetallic compounds, Sm2Co 17 Its Curie temperature and saturation magnetization are both higher than those of RCo5. It has a higher Curie temperature, excellent temperature stability and corrosion resistance, and is the most magnetic permanent magnet material at high temperatures.

[0003] Sm2Co 17 The high performance of this type of permanent magnet stems from its unique nanocellular structure, which is composed of Sm2(Co,Fe). 17 The magnet consists of a cellular phase, a Sm(Co,Cu)5 cell wall phase, and a Zr-rich lamellar phase. The formation of this ideal structure relies on precisely controlled aging heat treatment performed after solution treatment, while the material is in a supersaturated solid solution state. The aging process is essentially a phase separation and precipitation process of solute atoms (Fe, Cu, Zr) through diffusion; its kinetics and final microstructure directly determine the overall performance of the magnet.

[0004] Traditional standard heat treatment involves solution treatment followed by high-temperature, long-duration primary aging, then slow cooling and holding at that temperature, and finally air cooling to room temperature. This process is time-consuming, energy-intensive, and its microstructure control relies primarily on the temperature and time of the primary aging stage, offering limited control over the microstructure. This traditional aging process, which directly applies high-temperature, long-duration primary aging to the solution-treated magnet, offers limited control over the microstructure, especially for Fe-rich alloys. It struggles to maintain high remanence while achieving high coercivity and squareness, resulting in the inability to fully realize the theoretical energy product. For magnets with fluctuating composition (especially Fe and Cu content) or those seeking higher performance (such as a synergistic effect of high coercivity and high energy product), the traditional process has a narrow adjustment window, making it difficult to achieve fine-tuning of the microstructure and potentially leading to unstable magnetic properties or failure to fully realize the material's potential.

[0005] Therefore, it is necessary to develop a new heat treatment process that can achieve a synergistic improvement in high coercivity and high squareness while maintaining high remanence, and to finely control the microstructure in order to fully realize the magnetic energy product potential of samarium cobalt permanent magnet materials and improve the stability and adaptability of the process. Summary of the Invention

[0006] In view of this, the present invention provides a method for preparing samarium cobalt permanent magnet materials based on pre-aging treatment. The present invention systematically regulates the defect state before precipitation by performing a "pre-aging + rapid quenching" process before the main aging treatment, thereby refining the final nanocellular structure, achieving synergistic improvement of the magnetic properties of the material, and improving process efficiency and stability. This solves the problem that traditional processes have limited control over microstructure and are difficult to achieve high-performance synergistic optimization.

[0007] The first aspect of this invention is to provide a method for preparing samarium-cobalt permanent magnet materials based on pre-aging treatment, comprising the following steps: S1. Precursor preparation: The 2:17 type Sm-Co-Fe-Cu-Zr alloy is melted in a vacuum induction melting furnace. The ingot is crushed, milled by air jet, oriented by magnetic field, pressed into shape, and then sintered in a protective atmosphere to obtain a sintered billet. S2. Solution treatment: After the sintered green body is kept at a certain temperature, it is rapidly cooled to room temperature to obtain a supersaturated solid solution. S3. Pre-aging treatment: The solution-treated sample is kept at a temperature range of 500-800℃ for 3 min-300 min; S4. Rapid cooling: After the pre-aging treatment is completed, the sample is immediately rapidly cooled to room temperature; S5. Main aging treatment: The sample from S4 is kept at a constant temperature for one time, then cooled and kept at a constant temperature for a second time, and then air-cooled to room temperature.

[0008] Preferably, the alloy composition of step S1, by weight percentage, is as follows: Sm 23-27%, Fe 10-20%, Cu 5-8%, Zr 1-3%, with the balance being Co; the average particle size of the powder after air jet milling is 2-6 μm; the magnetic field orientation is performed in a magnetic field of 1.0-2.0 T; the pressing pressure is 150-250 MPa; the protective atmosphere is argon, hydrogen, nitrogen, an argon-hydrogen mixture, or vacuum, with a vacuum degree ≤10. -2 Pa; the sintering temperature is 1200℃-1220℃, and the sintering time is 1-4 h.

[0009] Preferably, in step S2, the solution temperature is 1160℃-1200℃, the solution time is 1-3 h, and the cooling method is water cooling, air cooling, or ice-water mixture quenching.

[0010] Preferably, in step S3, the pre-aging treatment is carried out in a vacuum-sealed glass tube or filled with a protective atmosphere (vacuum degree ≤ 10). -3 (Pa) is carried out.

[0011] Preferably, in step S4, the cooling is performed by quenching with an ice-water mixture, oil cooling, or air cooling.

[0012] Preferably, in step S5, the temperature of the first heat preservation is 810℃-890℃, and the heat preservation time is 10-40h; the cooling rate is 0.2-1.0℃ / min; the temperature of the second heat preservation is 360℃-400℃, and the heat preservation time is 2-20h.

[0013] A second aspect of the present invention is to provide a samarium-cobalt permanent magnet material prepared according to the above method, said samarium-cobalt permanent magnet material having a nanocellular structure composed of Sm2(Co,Fe). 17 It consists of a cellular phase, a Sm(Co,Cu)5 cell wall phase, and a Zr-rich lamellar phase.

[0014] The pre-aging treatment of this invention induces the initial segregation of solute atoms (Fe, Cu, Zr) in the solid solution by holding the solution at a relatively low temperature. Simultaneously, the migration of solute atoms towards equilibrium induces an excess of point defects and suppresses diffusion-controlled dislocation decomposition in the early stages. These high concentrations of point defects provide numerous preferential nucleation sites for subsequent phase transitions.

[0015] After the pre-aging treatment, the sample was immediately cooled to room temperature using rapid cooling methods such as ice-water quenching. The key role of this step is to effectively "freeze" and preserve the non-equilibrium defect state formed during the pre-aging stage, preventing the annihilation of defects or the redistribution of solute atoms during slow cooling. Supersaturated solid solutions containing dislocations exhibit higher nucleation rates and faster precipitation kinetics during isothermal aging than dislocation-free alloys. High nucleation rates are extremely important for achieving high coercivity by pinning magnetic domain walls.

[0016] In the subsequent main aging stage, due to the presence of high-density point defects pre-formed during the pre-aging treatment, the precipitation kinetics and defect decomposition kinetics of the Sm(Co,Cu)5 cell wall phase are faster than those of the sample without pre-aging, resulting in a significantly increased and more uniform distribution of nucleation sites. This leads to a finer and more uniform nanocellular structure with a higher cell wall density, effectively pinning magnetic domain walls at the microscale. This achieves a synergistic improvement in high coercivity, high remanence, and high squareness, significantly enhancing the overall magnetic properties of the magnet.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are as follows: This invention promotes the segregation of solute atoms and the formation of high-concentration point defects through pre-aging treatment at a relatively low temperature, providing uniform and high-density nucleation sites for the precipitation of Sm(Co,Cu)5 cell wall phase in the subsequent main aging stage, thereby effectively refining the nanocellular structure and achieving precise control over the microstructure.

[0018] This invention achieves a synergistic enhancement of magnetic properties by optimizing the combination of pre-aging temperature and time parameters, enabling the magnet to maintain high remanence while obtaining high coercivity and high squareness, thus fully leveraging the potential of the material's magnetic energy product.

[0019] This invention accelerates the precipitation kinetics of the subsequent main aging stage by inducing high-density point defects through pre-aging treatment, making the microstructure evolution process more controllable and efficient, shortening the total heat treatment cycle, and improving production efficiency.

[0020] This invention effectively preserves the non-equilibrium state through rapid cooling after pre-aging, enhancing the stability and adaptability of the process and solving the problem of performance instability caused by composition fluctuations.

[0021] The samarium cobalt permanent magnet material prepared by this invention has an optimized nanocellular structure, which has a higher cell wall density and a more uniform cell distribution compared with materials prepared by traditional processes, thus achieving superior overall magnetic properties. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] Figure 1 This is a comparison of the second quadrant demagnetization curves of samarium cobalt permanent magnet materials treated with different pre-aging times according to the present invention. The horizontal axis represents the magnetic field strength (unit: kOe), and the vertical axis represents the magnetization (unit: kGs). The figure shows the hysteresis loops of the samples after 0 min (no pre-aging), 5 min, 10 min, 30 min, 60 min, 90 min and 120 min of pre-aging treatment at 650℃. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Unless otherwise specified, all experiments were repeated three times, and the results are expressed as averages.

[0026] Example 1: A method for preparing samarium cobalt permanent magnet materials based on pre-aging treatment, the steps of which are as follows: S1. Precursor Preparation: A 2:17 Sm-Co-Fe-Cu-Zr alloy was prepared according to the following ratio: Sm content 24.3%, Fe content 16.5%, Cu content 6.3%, Zr content 2.4%, and the balance Co. The prepared raw materials were melted under an argon atmosphere to obtain an alloy ingot. The alloy ingot was crushed and milled into powder with a particle size of 3-5 μm using an air jet mill. The powder was oriented under a 2 T magnetic field, and then the oriented powder was pressed into a compact under a pressure of 200 MPa to obtain a compact. The compact was sintered at 1200℃ for 2 h under an argon protective atmosphere to obtain a high-density sintered compact. S2. Solution treatment: The sintered green body is solution treated at 1180℃ for 2 h, and then cooled to room temperature by strong air cooling to obtain a uniform supersaturated solid solution. S3. Pre-aging treatment: The solution-treated sample is sealed in a glass tube using a vacuum sealing machine and placed in a heat treatment furnace, where it is kept at 500℃ for 10 min. S4. Rapid cooling: After the pre-aging treatment is completed, the sample is immediately taken out of the heat treatment furnace and rapidly cooled to room temperature by quenching with an ice-water mixture. S5. Main aging treatment: The sample from S4 was kept at 840℃ for 20 h, then cooled to 380℃ at a rate of 0.5℃ / min and kept at that temperature for 12 h, and finally air-cooled to room temperature to obtain samarium cobalt permanent magnet material.

[0027] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.81 kGs, intrinsic coercivity Hcj = 31.75 kOe, and maximum energy product (BH). max It is 30.1 MGOe.

[0028] Example 2 The difference from Example 1 is that in step S3, the temperature of the pre-aging treatment is 600°C and the holding time is 90 min.

[0029] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.14 kGs, intrinsic coercivity Hcj = 32.42 kOe, and maximum energy product (BH). max It is 28.56 MGOe.

[0030] Example 3 The difference from Example 1 is that in step S3, the temperature of the pre-aging treatment is 650°C and the holding time is 5 min.

[0031] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.21 kGs, intrinsic coercivity Hcj = 32.14 kOe, and maximum energy product (BH). maxIt is 29.61 MGOe.

[0032] Example 4 The difference from Example 1 is that in step S3, the temperature of the pre-aging treatment is 650°C and the holding time is 10 min.

[0033] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.14 kGs, intrinsic coercivity Hcj = 32.81 kOe, and maximum energy product (BH). max It is 29.14 MGOe.

[0034] Example 5 The difference from Example 1 is that in step S3, the pre-aging treatment temperature is 650°C and the holding time is 30 min.

[0035] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.10 kGs, intrinsic coercivity Hcj = 32.22 kOe, and maximum energy product (BH). max It is 29.04 MGOe.

[0036] Example 6 The difference from Example 1 is that in step S3, the temperature of the pre-aging treatment is 650°C and the holding time is 60 min.

[0037] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.02 kGs, intrinsic coercivity Hcj = 31.15 kOe, and maximum energy product (BH). max It is 28.66 MGOe.

[0038] Example 7 The difference from Example 1 is that in step S3, the pre-aging treatment temperature is 650°C and the holding time is 90 min.

[0039] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.14 kGs, intrinsic coercivity Hcj = 31.81 kOe, and maximum energy product (BH). max It is 28.96 MGOe.

[0040] Example 8 The difference from Example 1 is that in step S3, the temperature of the pre-aging treatment is 650°C and the holding time is 120 min.

[0041] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.15 kGs, intrinsic coercivity Hcj = 32.89 kOe, and maximum energy product (BH). maxIt is 28.51 MGOe.

[0042] Example 9 The difference from Example 1 is that in step S3, the temperature of the pre-aging treatment is 700°C and the holding time is 20 min.

[0043] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.13 kGs, intrinsic coercivity Hcj = 31.74 kOe, and maximum energy product (BH). max It is 28.64 MGOe.

[0044] Example 10 The difference from Example 1 is that in step S3, the temperature of the pre-aging treatment is 800°C and the holding time is 10 min.

[0045] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.77 kGs, intrinsic coercivity Hcj = 32.32 kOe, and maximum energy product (BH). max It is 31.92 MGOe.

[0046] Example 11 The difference from Example 1 is that in step S3, the pre-aging treatment temperature is 650 °C and the holding time is 3 min. Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.75 kGs, intrinsic coercivity Hcj = 31.89 kOe, and maximum energy product (BH). max It is 31.78 MGOe.

[0047] Example 12 The difference from Example 1 is that in step S3, the temperature of the pre-aging treatment is 650°C and the holding time is 300 min.

[0048] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.10 kGs, intrinsic coercivity Hcj = 32.43 kOe, and maximum energy product (BH). max It is 29.03 MGOe.

[0049] Example 13 The difference from Example 1 is that the alloy composition in step S1 is adjusted to: Sm 23%, Fe 20%, Cu 5%, Zr 3%, with the balance being Co.

[0050] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.14 kGs, intrinsic coercivity Hcj = 32.97 kOe, and maximum energy product (BH)max = 28.08 MGOe.

[0051] Example 14 The difference from Example 1 is that the alloy composition in step S1 is adjusted to: Sm 27%, Fe 20%, Cu 8%, Zr 1%, with the balance being Co.

[0052] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.87 kGs, intrinsic coercivity Hcj = 32.61 kOe, and maximum energy product (BH)max = 31.78 MGOe.

[0053] Comparative Example 1 The difference from Example 1 is that the pre-aging treatment in step S3 and the rapid cooling in step S4 are omitted, and the main aging treatment is performed directly after the solution treatment.

[0054] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 10.51 kGs, intrinsic coercivity Hcj = 28.28 kOe, and maximum energy product (BH). max It is 25.31 MGOe.

[0055] Comparative Example 2 The difference from Example 1 is that after the pre-aging treatment in step S3, step S4 adopts slow cooling to room temperature in the furnace, with a cooling rate of about 5°C / min.

[0056] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.12 kGs, intrinsic coercivity Hcj = 29.50 kOe, and maximum energy product (BH). max It is 28.4 MGOe.

[0057] Comparative Example 3 The difference from Example 1 is that in step S3, the temperature of the pre-aging treatment is 400°C (lower than the scope of the claims), and the holding time is 30 min.

[0058] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 11.14 kGs, intrinsic coercivity Hcj = 27.80 kOe, and maximum energy product (BH). max It is 28.47 MGOe.

[0059] Comparative Example 4 The difference from Example 1 is that in step S3, the temperature of the pre-aging treatment is 810°C (higher than the scope of the claims), and the holding time is 30 min.

[0060] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 10.71 kGs, intrinsic coercivity Hcj = 27.39 kOe, and maximum energy product (BH). max It is 26.44 MGOe.

[0061] Comparative Example 5 The difference from Example 1 is that in step S3, the heat preservation time for the pre-aging treatment is 1 min and the temperature is 650℃.

[0062] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 10.91 kGs, intrinsic coercivity Hcj = 28.35 kOe, and maximum energy product (BH). max It is 27.87 MGOe.

[0063] Comparative Example 6 The difference from Example 1 is that in step S3, the heat preservation time for the pre-aging treatment is 150 min and the temperature is 650℃.

[0064] Test results show that the magnetic properties of this samarium cobalt permanent magnet material are: remanence Br = 10.59 kGs, intrinsic coercivity Hcj = 27.82 kOe, and maximum energy product (BH). max It is 25.29 MGOe.

[0065] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing samarium-cobalt permanent magnet materials based on pre-aging treatment, characterized in that, Includes the following steps: S1. Precursor preparation: The 2:17 type Sm-Co-Fe-Cu-Zr alloy ingot is crushed, air-flow milled, magnetically oriented, pressed into shape, and then sintered in a protective atmosphere to obtain a sintered billet. S2. Solution treatment: After the sintered green body is kept at a certain temperature, it is rapidly cooled to room temperature to obtain a supersaturated solid solution. S3. Pre-aging treatment: The solution-treated sample is kept at a temperature range of 500-800℃ for 3 min-300 min; S4. Rapid cooling: After the pre-aging treatment is completed, the sample is immediately rapidly cooled to room temperature; S5. Main aging treatment: The sample from S4 is kept at a constant temperature for one time, then cooled and kept at a constant temperature for a second time, and then air-cooled to room temperature.

2. The method for preparing samarium-cobalt permanent magnet materials based on pre-aging treatment according to claim 1, characterized in that, The alloy composition of step S1, by weight percentage, is as follows: Sm 23-27%, Fe 10-20%, Cu 5-8%, Zr 1-3%, with the balance being Co.

3. The method for preparing samarium-cobalt permanent magnet materials based on pre-aging treatment according to claim 1, characterized in that, The average particle size of the powder after air jet milling in step S1 is 2-6 μm.

4. The method for preparing samarium-cobalt permanent magnet materials based on pre-aging treatment according to claim 1, characterized in that, The magnetic field orientation in step S1 is performed in a magnetic field of 1.0-2.0 T.

5. The method for preparing samarium-cobalt permanent magnet materials based on pre-aging treatment according to claim 1, characterized in that, The pressure for pressing in step S1 is 150-250 MPa.

6. The method for preparing samarium-cobalt permanent magnet materials based on pre-aging treatment according to claim 1, characterized in that, In step S1, the protective atmosphere is argon, hydrogen, nitrogen, an argon-hydrogen mixture, or vacuum, with a vacuum degree ≤10. -2 Pa.

7. The method for preparing samarium-cobalt permanent magnet materials based on pre-aging treatment according to claim 1, characterized in that, In step S1, the sintering temperature is 1200℃-1220℃, and the sintering time is 1-4 h.

8. The method for preparing samarium-cobalt permanent magnet materials based on pre-aging treatment according to claim 1, characterized in that, In step S2, the temperature for heat preservation is 1160℃-1200℃, and the heat preservation time is 1-3 hours; the cooling method is water cooling, air cooling, or quenching with a mixture of ice and water.

9. The method for preparing samarium-cobalt permanent magnet materials based on pre-aging treatment according to claim 1, characterized in that, The rapid cooling in step S4 is achieved by quenching with an ice-water mixture, oil cooling, or air cooling.

10. The samarium-cobalt permanent magnet material prepared by the method according to any one of claims 1-9, characterized in that, The samarium-cobalt permanent magnet material has a nanocellular structure, which is composed of Sm2(Co,Fe). 17 It consists of a cellular phase, a Sm(Co,Cu)5 cell wall phase, and a Zr-rich lamellar phase.

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