Preparation method of high-mechanical-property samarium-cobalt permanent magnet

Abstract

The application belongs to the technical field of permanent magnet materials, and relates to a preparation method of a high-mechanical-property samarium-cobalt permanent magnet, which comprises the following steps: sequentially subjecting raw materials to smelting, powdering, orientation forming, cold isostatic pressing, sintering, solid solution, aging, and heat treatment to obtain a samarium-cobalt permanent magnet; the heat treatment is performed under the protection of an inert atmosphere, the number of heat treatments is 1-10, an external magnetic field and an external stress are applied to one or more heat treatments; the magnetic field strength of the external magnetic field is 1-50 kOe, and the size of the external stress is 5-500 MPa. After the aging process is completed, the heat treatment of the external magnetic field and the external stress is performed again, compared with a traditional process, the mechanical property of the samarium-cobalt magnet is greatly improved while the magnetic property is improved, and the magnetic-force property of the samarium-cobalt magnet is synergistically improved.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet materials technology and relates to a method for preparing a samarium cobalt permanent magnet with high mechanical properties. Background Technology

[0002] Samarium cobalt permanent magnets, with their unique high-temperature stability, excellent corrosion resistance, and low remanence temperature coefficient, are indispensable key materials for the development of high technology, national defense weaponry, modern communications, transportation, and intelligent manufacturing. However, due to its inherent characteristics such as a low slip system and anisotropy, samarium cobalt lacks ductility and is difficult to process into complex shapes. During product processing, turnover, inspection, and magnetization, corner defects are easily caused, especially during use under impact, vibration, centrifugal force, and other external forces, making failure more likely. Currently, the bending strength of samarium cobalt magnets is only 80–140 MPa, and the fracture toughness is only 1.5–2.5 MPa. 1 / 2 Due to its brittleness, production losses can reach as high as 20-30%, which significantly increases processing costs and severely restricts its application range and deep processing, hindering my country's strategic goal of developing towards a high-end industrial chain as a major rare earth producer.

[0003] To improve the mechanical properties of samarium-cobalt permanent magnets, researchers have conducted extensive studies. Adding high-melting-point oxides during the powder preparation stage to form a heterogeneous powder mixture effectively improved the mechanical properties of the magnets, but significantly degraded their magnetic properties. Surface coating with a protective layer can improve mechanical properties and uniformity, but the improvement is limited, and the magnetic properties are somewhat reduced.

[0004] Therefore, how to improve the mechanical properties of magnets while maintaining or enhancing their overall performance is the current research focus of samarium-cobalt permanent magnet materials. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, the present invention aims to provide a method for preparing a high-performance samarium cobalt permanent magnet, which yields a samarium cobalt permanent magnet with excellent mechanical properties, thus overcoming the shortcomings of the prior art.

[0006] One objective of this invention is achieved through the following technical solution:

[0007] A method for preparing a high-performance samarium cobalt permanent magnet includes the following steps:

[0008] The raw materials are sequentially smelted, powdered, oriented, cold isostatically pressed, sintered, solution-treated, aged, and heat-treated to obtain samarium cobalt permanent magnets.

[0009] The heat treatment is carried out under an inert atmosphere and is performed 1 to 10 times. An external magnetic field and external stress are applied in one or more heat treatments. Here, "multiple times" is less than or equal to the number of heat treatments. For example, when the number of heat treatments is 3, "multiple times" here means 2 or 3 times.

[0010] The number of heat treatments is 1 to 10. When the number of heat treatments is ≥2, the temperature is lowered to 10 to 50°C for each heat treatment, and then raised again for subsequent heat treatments. The heating rate is 0.8 to 1.2°C / min. The holding temperature and holding time for each heat treatment can be the same or different.

[0011] Preferably, the holding temperature for each heat treatment is 350℃≤T<Curie temperature, and more preferably 400℃≤T≤850℃.

[0012] Preferably, the holding time for each heat treatment is 3 to 90 minutes, and more preferably 5 to 60 minutes.

[0013] Preferably, each heat treatment stage is one or two stages, and the external magnetic field and external stress are applied to one stage or the entire first and second stages.

[0014] When the heat treatment stage is single-stage, the holding temperature for the first-stage heat treatment is 350℃≤T<Curie temperature, more preferably 400℃≤T≤850℃. The holding time for the first-stage heat treatment is 3~90min, more preferably 5~60min.

[0015] When the heat treatment stage is two, the holding temperature of the first stage heat treatment is 350℃≤T<Curie temperature (more preferably 400℃≤T≤850℃), and the holding time is 3~90min (more preferably 5~60min); the holding temperature of the second stage heat treatment is 350℃≤T<Curie temperature (more preferably 400℃≤T≤850℃), and the holding time is 3~90min (more preferably 5~60min).

[0016] Further preferred, when the heat treatment stage is two, the holding temperature of the first stage heat treatment is 700-850℃ and the holding time is 3-90min (more preferably 5-60min); the holding temperature of the second stage heat treatment is 350-600℃ and the holding time is 3-90min (more preferably 5-60min).

[0017] Each heat treatment step includes a heating stage, a holding stage, and a cooling stage. Preferably, the external magnetic field and external stress are applied to any one, any two, or the entirety of each heat treatment step.

[0018] Preferably, the magnetic field strength of the applied magnetic field is 1 to 50 kOe, more preferably 3 to 20 kOe, and even more preferably 5 to 10 kOe.

[0019] Preferably, the external magnetic field is located on both sides of the sample, and the sample is placed at the center of the magnetic field.

[0020] Preferably, the direction of the external magnetic field is one of horizontal, vertical, or arbitrary angle.

[0021] Preferably, the method of applying the external magnetic field is parallel to the easy magnetization axis of the sample.

[0022] Preferably, the applied stress is 5 to 500 MPa, more preferably 30 to 300 MPa, and even more preferably 50 to 200 MPa.

[0023] Stress is applied directly to the magnet using a clamp, press, or other mechanical equipment. The medium for applying the stress is either a magnetically conductive material or a non-magnetically conductive material, preferably a non-magnetically conductive material.

[0024] Preferably, the direction of the applied stress is parallel to the direction of the applied magnetic field.

[0025] Preferably, the inert atmosphere is nitrogen and / or argon. The purity of the nitrogen and / or argon is ≥99.99%.

[0026] Another objective of this invention is achieved through the following technical solution:

[0027] A high-performance samarium cobalt permanent magnet is prepared by the above-described method.

[0028] Preferably, the maximum bending strength of the samarium cobalt permanent magnet is ≥150 MPa. More preferably, the maximum bending strength is ≥220 MPa. Even more preferably, the maximum bending strength is 290–400 MPa.

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

[0030] 1. In this invention, after the aging process is completed, an external magnetic field and external stress heat treatment are applied. Compared with the traditional process, the magnetic properties are improved while the mechanical properties of the samarium cobalt magnet are significantly improved, thus achieving a synergistic improvement in the magnetic and mechanical properties of the samarium cobalt magnet.

[0031] 2. After the aging process is completed, the present invention performs multiple heat treatments with external magnetic fields and external stresses, which significantly improves the coercivity and mechanical properties compared to a single heat treatment.

[0032] 3. The improved bending strength of samarium cobalt permanent magnets facilitates the deep processing of magnets into complex shapes, reduces processing losses, lowers processing costs, and greatly expands their application range. Attached Figure Description

[0033] Figure 1 The process diagram shows the sintering, solution treatment, aging, and heat treatment steps of samarium cobalt permanent magnets.

[0034] Figure 2 This is a graph showing the magnetic properties of the samarium-cobalt magnet in Embodiment 7 of the present invention.

[0035] Figure 3 This is a graph showing the magnetic performance of the samarium cobalt magnet in Comparative Example 1 of the present invention.

[0036] Figure 4 This is a bending stress-strain diagram of the samarium-cobalt magnet in Embodiment 7 of the present invention;

[0037] Figure 5 This is a bending stress-strain diagram of the samarium-cobalt magnet in Comparative Example 1 of the present invention. Detailed Implementation

[0038] In the following description, the steps of smelting, powdering, orientation forming, cold isostatic pressing, sintering, solution treatment, aging, and heat treatment involved in the preparation method of high mechanical properties samarium cobalt permanent magnets will be described in detail. However, these embodiments are exemplary and the disclosure of this invention is not limited thereto.

[0039] Samarium cobalt permanent magnets include 1:5 and 2:17 types, and cannot be used to limit the scope of protection of this invention.

[0040] Melting steps: Weigh each raw material according to the molecular formula of samarium cobalt permanent magnets and mix them, with additional compensation for Sm during the mixing process. Place the raw materials into a vacuum melting furnace, and evacuate the vacuum level inside the furnace to <1×10⁻⁶. -1 The solution is filled with inert gas and heated to 1400–1500°C for melting, held at that temperature for 1–30 minutes, and then poured into a water-cooled copper mold. After cooling, an alloy ingot is formed. The above melting steps are merely illustrative and should not be used to limit the scope of protection of this invention.

[0041] Powder preparation step: The alloy ingot obtained from the smelting step is coarsely crushed to below 300 μm. The coarse magnetic powder obtained after coarse crushing is further finely ground by air jet milling to a particle size of 1-6 μm. The above powder preparation steps are merely illustrative and should not be used to limit the scope of protection of this invention.

[0042] Orientation forming and cold isostatic pressing steps: The magnetic powder obtained in the powder preparation step is placed in a magnetic field press with a magnetic field strength of 0.5-5T under an inert atmosphere for orientation forming. The prepared green blank is vacuum-sealed and placed in an isostatic pressing device, where it is held at a pressure of 50-300MPa for 5-60s to obtain a samarium cobalt permanent magnet alloy blank. The above orientation forming and cold isostatic pressing steps are only illustrative and should not be used to limit the scope of protection of this invention.

[0043] Figure 1 This diagram illustrates the sintering, solution treatment, aging, and heat treatment processes for the samarium-cobalt permanent magnet of the present invention. The specific steps are shown below:

[0044] Sintering steps: The samarium-cobalt permanent magnet alloy blank obtained by cold isostatic pressing is first pre-sintered at 1100-1180℃ for 0.5-2 hours, and then sintered at 1170-1250℃ for 1-5 hours under an inert atmosphere. The above sintering steps are only illustrative and should not be used to limit the scope of protection of this invention.

[0045] Solution treatment: The solution temperature is 10-20°C lower than the sintering temperature, and the solution treatment lasts for 2-6 hours. Then, the solution is cooled to room temperature to obtain a samarium-cobalt permanent magnet solid solution. The above solution treatment steps are merely illustrative and should not be used to limit the scope of protection of this invention.

[0046] Aging steps: The samarium cobalt permanent magnet solid solution is heated to 750℃≤T<Curie temperature (more preferably 800℃≤T≤850℃) under an inert atmosphere for isothermal aging treatment for 10~30h, then slowly cooled to 300~500℃ at 0.3~1.0℃ / min and held for 1~5h, and finally slowly cooled to room temperature in the furnace to obtain samarium cobalt samples.

[0047] The above aging steps are merely illustrative and should not be used to limit the scope of protection of this invention. The aging steps may also include multi-stage aging treatment or multiple aging treatments for 1:5 or 2:17 samarium cobalt magnets.

[0048] Heat treatment steps:

[0049] The heat treatment is carried out under an inert atmosphere, and the number of heat treatments is 1 to 10 (it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times). An external magnetic field and external stress are applied in one or more heat treatments. Here, "multiple times" is less than or equal to the number of heat treatments. For example, when the number of heat treatments is 3, "multiple times" here refers to 2 or 3 times. When the number of heat treatments is 10, "multiple times" here can be 2, 3, 4, 5, 6, 7, 8, 9, or 10 times.

[0050] When the heat treatment is performed ≥2 times, the temperature should be lowered to 10–50℃ for each heat treatment before being raised again for subsequent heat treatments. The holding temperature and holding time for each heat treatment can be the same or different.

[0051] Preferably, the holding temperature for each heat treatment is 350℃ ≤ T < Curie temperature, more preferably 400℃ ≤ T ≤ 850℃. Preferably, the holding time for each heat treatment is 3 to 90 minutes, more preferably 5 to 60 minutes.

[0052] Preferably, each heat treatment stage is one or two stages, with the external magnetic field and external stress applied to one stage, or the entire first and second stages. When the heat treatment stage is one stage, the holding temperature for the first stage is 350℃≤T<Curie temperature, more preferably 400℃≤T≤850℃; the holding time for the first stage is 3~90min, more preferably 5~60min. When the heat treatment stage is two stages, the holding temperature for the first stage is 350℃≤T<Curie temperature (more preferably 400℃≤T≤850℃), and the holding time is 3~90min (more preferably 5~60min); the holding temperature for the second stage is 350℃≤T<Curie temperature (more preferably 400℃≤T≤850℃), and the holding time is 3~90min (more preferably 5~60min).

[0053] Further preferred, when the heat treatment stage is two, the holding temperature of the first stage heat treatment is 700-850℃ and the holding time is 3-90min (more preferably 5-60min); the holding temperature of the second stage heat treatment is 350-600℃ and the holding time is 3-90min (more preferably 5-60min).

[0054] Each heat treatment step includes a heating stage, a holding stage, and a cooling stage. The heating rate is 0.8–1.2 °C / min, and the cooling rate can be furnace cooling or 1–50 °C / min. Each heat treatment step can be the same or different. Preferably, the external magnetic field and external stress are applied to any one, any two, or the entirety of each heat treatment step.

[0055] Preferably, the applied magnetic field strength is 1–50 kOe, more preferably 3–20 kOe, and even more preferably 5–10 kOe. Preferably, the applied stress is 5–500 MPa, more preferably 30–300 MPa, and even more preferably 50–200 MPa. Preferably, the inert atmosphere is nitrogen and / or argon. The purity of the nitrogen and / or argon is ≥99.99%.

[0056] Preferably, the external magnetic field is located on both sides of the sample, with the sample placed at the center of the magnetic field. Preferably, the direction of the external magnetic field is horizontal, vertical, or at an arbitrary angle. Preferably, the external magnetic field is parallel to the easy magnetization axis of the sample.

[0057] Stress is applied directly to the magnet using a fixture, press, or other mechanical equipment. The medium for applying the stress is either a magnetically conductive material or a non-magnetically conductive material, preferably a non-magnetically conductive material. Preferably, the direction of the applied stress is parallel to the direction of the applied magnetic field.

[0058] 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.

[0059] Example 1

[0060] The preparation method of the high mechanical performance samarium cobalt permanent magnet material in this embodiment includes the following steps:

[0061] (1) Smelting: According to the molecular formula Sm(Co bal Fe 0.21 Cu 0.062 Zr 0.024 ) 7.36 During the batching process, an additional 4% (mass fraction) compensation amount is applied to Sm; the batched ingredients are then placed in a vacuum melting furnace, and the vacuum level inside the furnace is evacuated to 3×10⁻⁶. -2 Pa is filled with high-purity argon gas, heated to 1450℃ for melting, held at that temperature for 5 minutes, and then the high-temperature alloy solution is poured into a water-cooled copper mold and cooled to form an alloy ingot.

[0062] (2) Powdering: The alloy ingot obtained in step (1) is subjected to coarse crushing and air jet milling. The coarse crushing breaks the alloy ingot to below 300μm. The coarse magnetic powder obtained after coarse crushing is further ground into magnetic powder with a particle size of about 4μm.

[0063] (3) Orientation and cold isostatic pressing: The magnetic powder obtained in step (2) is placed in a magnetic field press with a magnetic field strength of 2T under nitrogen protection. The prepared green blank is vacuum sealed and placed in an isostatic pressing device. It is held under pressure of 180MPa for 30s to obtain a samarium cobalt permanent magnet alloy blank.

[0064] (4) The samarium cobalt permanent magnet alloy blank obtained in step (3) is first pre-sintered at a temperature of 1180℃ for 1 hour, and then sintered at a temperature of 1200℃ for 2 hours under argon protection.

[0065] (5) After sintering, a solution heat treatment is performed at a temperature of 1190℃ for 4 hours. After the solution treatment, the mixture is cooled to obtain a samarium cobalt permanent magnet solid solution.

[0066] (6) The samarium cobalt permanent magnet solid solution obtained in step (5) was isothermally heat-treated at 830°C for 20 hours under argon protection, then slowly cooled to 400°C at 0.7°C / min and held for 3 hours, and finally slowly cooled to room temperature with the furnace to obtain samarium cobalt sample.

[0067] (7) The samarium cobalt sample obtained in step (6) is isothermally heat-treated at 810°C for 10 min under a high-purity argon atmosphere at a rate of 1°C / min. At the same time as heating, an external magnetic field with a strength of 10 kOe is applied (the external magnetic field is located on both sides of the sample, the sample is placed at the center of the magnetic field, and the direction of the external magnetic field is parallel and horizontal to the easy magnetization axis of the sample). The external stress is 100 MPa (the direction of the external stress is parallel to the direction of the magnetic field). Finally, the sample is slowly cooled to room temperature in the furnace, and the magnetic field and stress are removed to obtain the final samarium cobalt product.

[0068] Example 2

[0069] The difference between Example 2 and Example 1 is only in step (7). In step (7) of Example 2, the samarium cobalt sample is isothermally heat-treated for 30 min at 810°C under a high-purity argon atmosphere at a rate of 1°C / min. At the same time as heating, an external magnetic field with a strength of 10 kOe and an external stress of 100 MPa are applied. Finally, the sample is slowly cooled to room temperature in the furnace, and the magnetic field and stress are removed to obtain the final samarium cobalt product.

[0070] Example 3

[0071] The difference between Example 3 and Example 1 is only in step (7). In step (7) of Example 3, the samarium cobalt sample is isothermally heat-treated for 60 min at 810°C under a high-purity argon atmosphere at a rate of 1°C / min. At the same time as heating, an external magnetic field with a strength of 10 kOe and an external stress of 100 MPa are applied. Finally, the sample is slowly cooled to room temperature in the furnace, and the magnetic field and stress are removed to obtain the final samarium cobalt product.

[0072] Example 4

[0073] The difference between Example 4 and Example 1 is only in step (7). In step (7) of Example 4, the samarium cobalt sample is heated to 600℃ at 1℃ / min under a high-purity argon atmosphere and isothermally heat-treated for 10min. At the same time as heating, an external magnetic field strength of 10kOe and an external stress of 100MPa are applied. Finally, the sample is slowly cooled to room temperature with the furnace, and the magnetic field and stress are removed to obtain the final samarium cobalt product.

[0074] Example 5

[0075] The difference between Example 5 and Example 1 is only in step (7). In step (7) of Example 5, the samarium cobalt sample is heated to 400°C at a rate of 1°C / min under a high-purity argon atmosphere and isothermally heat-treated for 10 min. At the same time as heating, an external magnetic field with a strength of 10 kOe and an external stress of 100 MPa are applied. Finally, the sample is slowly cooled to room temperature in the furnace, and the magnetic field and stress are removed to obtain the final samarium cobalt product.

[0076] Example 6

[0077] The difference between Example 6 and Example 1 is only in step (7). In step (7) of Example 6, the samarium cobalt sample is heated to 400°C at a rate of 1°C / min under a high-purity argon atmosphere and isothermally heat-treated for 30 min. At the same time as heating, an external magnetic field with a strength of 10 kOe and an external stress of 100 MPa are applied. Finally, the sample is slowly cooled to room temperature in the furnace, and the magnetic field and stress are removed to obtain the final samarium cobalt product.

[0078] Example 7

[0079] The difference between Example 7 and Example 1 is only in step (7). In step (7) of Example 7, the samarium cobalt sample is heated to 810°C at a rate of 1°C / min under a high-purity argon atmosphere and isothermally heat-treated for 30 min. At the same time as heating, an external magnetic field with a strength of 10 kOe and an external stress of 100 MPa are applied. Then, it is slowly cooled to 400°C and isothermally heat-treated for 60 min. Finally, it is slowly cooled to room temperature with the furnace, and the magnetic field and stress are removed to obtain the final samarium cobalt product.

[0080] Example 8

[0081] The difference between Example 8 and Example 1 is only in step (7). In step (7) of Example 8, the samarium cobalt sample is heated to 810°C at a rate of 1°C / min under a high-purity argon atmosphere and isothermally heat-treated for 30 min. At the same time as heating, an external magnetic field with a strength of 10 kOe and an external stress of 100 MPa are applied. After isothermally heat-treated for 30 min, the magnetic field and stress are removed, and then the sample is slowly cooled to 400°C and isothermally heat-treated for 60 min. Finally, the sample is slowly cooled to room temperature with the furnace to obtain the final samarium cobalt product.

[0082] Example 9

[0083] The difference between Example 9 and Example 1 is only in step (7). In step (7) of Example 9, the samarium cobalt sample is heated to 700℃ at a rate of 1.2℃ / min under a high-purity argon atmosphere and isothermally heat-treated for 20min. At the same time as heating, an external magnetic field with a strength of 5kOe and an external stress of 200MPa are applied. After isothermal heat treatment for 20min, the magnetic field and stress are removed, and finally the sample is slowly cooled to room temperature in the furnace to obtain the final samarium cobalt product.

[0084] Example 10

[0085] The difference between Example 10 and Example 1 is only in step (7). In step (7) of Example 10, the samarium cobalt sample is heated to 810°C at a rate of 0.8°C / min under a high-purity argon atmosphere and isothermally heat-treated for 40 min. At the same time as heating, an external magnetic field strength of 15 kOe and an external stress of 150 MPa are applied. Finally, the sample is slowly cooled to room temperature in the furnace, and the magnetic field and stress are removed to obtain the final samarium cobalt product.

[0086] Comparative Example 1

[0087] The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not have step (7).

[0088] Comparative Example 2

[0089] The only difference between Comparative Example 2 and Example 1 is that in step (7) of Comparative Example 2, the samarium cobalt sample was isothermally heat-treated for 10 min at 810°C under a high-purity argon atmosphere at a rate of 1°C / min. No external magnetic field strength or external stress was applied during the heat treatment process. Finally, the sample was slowly cooled to room temperature with the furnace to obtain the final samarium cobalt product.

[0090] Comparative Example 3

[0091] The only difference between Comparative Example 3 and Example 1 is that in step (7) of Comparative Example 3, the samarium cobalt sample was heated to 810°C at a rate of 1°C / min under a high-purity argon atmosphere and isothermally heat-treated for 10 min. At the same time as heating, an external magnetic field with a strength of 10 kOe was applied. No external stress was applied. Finally, the sample was slowly cooled to room temperature in the furnace, and the magnetic field was removed to obtain the final samarium cobalt product.

[0092] Comparative Example 4

[0093] The only difference between Comparative Example 4 and Example 1 is that in step (7) of Comparative Example 4, the samarium cobalt sample was heated to 810°C at a rate of 1°C / min under a high-purity argon atmosphere and isothermally heat-treated for 10 min. At the same time as heating, an external stress of 100 MPa was applied, but no external magnetic field strength was applied. Finally, the sample was slowly cooled to room temperature with the furnace, and the external force was removed to obtain the final samarium cobalt product.

[0094] The samarium cobalt permanent magnet materials obtained in the above embodiments and comparative examples were characterized for room temperature magnetic and mechanical properties. The samarium cobalt permanent magnet materials were then processed into… Used for magnetic performance testing; processed into standard samples of h×b×l=5×6×20mm, with the height direction parallel to the easy magnetization axis, i.e. h / / c, used for bending strength testing of samarium cobalt permanent magnet materials, the results are shown in Table 1.

[0095] Table 1. Magnetic properties and bending strength of samarium-cobalt permanent magnet materials obtained in the examples and comparative examples.

[0096]

[0097]

[0098] Figure 3 This is a graph showing the magnetic properties of the samarium-cobalt magnet in Comparative Example 1. Figure 5The diagram shows the bending stress-strain of the samarium-cobalt magnet in Comparative Example 1. Compared to the performance of Comparative Example 1 using the conventional process, the coercivity and energy product of the samarium-cobalt magnets in Examples 1-10 are improved, with the maximum value being in Example 1, where the energy product is 29.33 MGOe. The bending strength of the samarium-cobalt magnets is also significantly improved, with an increase of 24.6% to 131.7%, the maximum value being in Example 7. Example 7, with its additional secondary isothermal heat treatment at 400℃ for 60 minutes, further improves both coercivity and mechanical properties. Figure 2 and Figure 4 As shown, the bending strength is as high as 292 MPa. Examples 1-3 are isothermal heat treatments at 810℃ for different times. As the aging time increases, the mechanical properties first increase and then decrease, while the magnetic properties gradually decrease, but all are greater than the comparative example. Example 4 is an isothermal heat treatment at 600℃ for 10 minutes. Compared with the isothermal heat treatment at 810℃ for 10 minutes, the mechanical properties decrease significantly. Examples 5-6 are isothermal heat treatments at 400℃ for different times. As the aging time increases, the mechanical properties increase, but the magnetic properties do not change much. This may be because the coercivity of the samarium cobalt magnet is still very high at 400℃, and the external magnetic field is relatively small, which cannot saturate the magnet and has little impact on the magnetic properties.

[0099] Comparative Example 2 involved only heat treatment without applying an external magnetic field or stress. The experimental results from Comparative Examples 1 and 2 show that heat treatment without an external magnetic field or stress has no significant effect on the magnetic properties and bending strength of the magnet. Comparative Examples 3 and 4 involved only applying an external magnetic field or only applying external stress. The experimental results from Comparative Examples 1, 3, and 4 show that applying only an external magnetic field or only external stress during heat treatment results in a very limited increase in bending strength.

[0100] The above analysis shows that the magnetic and mechanical properties of samarium-cobalt magnets are improved through magnetic field, stress, and isothermal heat treatment. This is likely because the applied magnetic field and pressure provide an external driving force, causing lattice distortion within the magnet and accelerating the diffusion of elements within and between cells. Compared to traditional manufacturing processes, the addition of magnetic field, stress, and isothermal heat treatment results in more complete element diffusion within the magnet, leading to more precipitates and enhanced pinning effect of the precipitates on domain walls. Simultaneously, appropriate temperature, magnetic field strength, aging time, and stress levels can refine the grains, increase the number of grain boundaries, and increase the resistance to crack propagation, thus improving the mechanical properties of the magnet. As the heat treatment temperature increases within a certain range, the mechanical properties also improve significantly.

[0101] All aspects, embodiments, and features of this invention should be considered illustrative in all respects and not limiting of the invention; the scope of the invention is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0102] In the preparation method of this invention, the order of the steps is not limited to the listed order. For those skilled in the art, variations in the order of the steps without creative effort are also within the scope of protection of this invention. Furthermore, two or more steps or actions can be performed simultaneously.

[0103] Finally, it should be noted that the specific embodiments described herein are merely illustrative examples 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 specific 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 method for producing a high mechanical property samarium-cobalt permanent magnet, characterized by comprising: The samarium-cobalt permanent magnet comprises a 1:5 type or a 2:17 type, and the preparation method comprises the following steps: ​ The raw materials are sequentially subjected to smelting, powdering, orientation forming, cold isostatic pressing, sintering, solid solution, aging, and heat treatment to obtain the samarium-cobalt permanent magnet. The heat treatment is performed under protection of an inert atmosphere, the heat treatment is performed 1-10 times, and an external magnetic field and an external stress are applied to one or more heat treatments; The holding temperature of each heat treatment is 350 DEG C ≤ T < Curie temperature; The magnetic field strength of the external magnetic field is 1-50 kOe; The external stress has a magnitude of 5-500 MPa.

2. The method of claim 1, wherein the Sm-Co permanent magnet has a high mechanical property. The holding temperature of each heat treatment is 400 DEG C ≤ T ≤ 850 DEG C. And / or, the holding time of each heat treatment is 3-90 min.

3. The method of claim 1, wherein the Sm-Co permanent magnet has a high mechanical property. The heat treatment has one or two stages, and the external magnetic field and the external stress are applied to one or both of the stages; When the heat treatment has one stage, the holding temperature of the one-stage heat treatment is 350 DEG C ≤ T < Curie temperature, and the holding time of the one-stage heat treatment is 3-90 min. When the heat treatment has two stages, the holding temperature of the first-stage heat treatment is 350 DEG C ≤ T < Curie temperature, and the holding time is 3-90 min; the holding temperature of the second-stage heat treatment is 350 DEG C ≤ T < Curie temperature, and the holding time is 3-90 min.

4. The method of claim 3, wherein the Sm-Co permanent magnet has a high mechanical property. When the heat treatment has two stages, the holding temperature of the first-stage heat treatment is 700-850 DEG C, and the holding time is 3-90 min; the holding temperature of the second-stage heat treatment is 350-600 DEG C, and the holding time is 3-90 min.

5. The method of claim 1, wherein the Sm-Co permanent magnet has a high mechanical property. The The magnetic field strength of the external magnetic field is 3-20 kOe. And / or, the external stress has a magnitude of 30-300 MPa.

6. The method of claim 1 or 5, wherein the method further comprises the step of: The magnetic field strength of the external magnetic field is 5-10 kOe, and the external stress has a magnitude of 50-200 MPa. ​ 7. The method of claim 1, wherein the Sm-Co permanent magnet has a high mechanical property. The external magnetic field is located on both sides of the sample, and the sample is placed at the center of the magnetic field. The direction of the external magnetic field is one of horizontal, vertical, and any angle.

8. The method of claim 1, wherein the Sm-Co permanent magnet has high mechanical properties. The method of the external magnetic field is parallel to the easy magnetization axis of the sample, and the direction of the external stress is parallel to the direction of the external magnetic field.

9. A high mechanical performance samarium-cobalt permanent magnet, characterized in that, The samarium-cobalt permanent magnet is prepared by the preparation method of claim 1.

10. The high mechanical property samarium-cobalt permanent magnet of claim 9, wherein, The maximum bending strength of the samarium-cobalt permanent magnet is ≥ 150 MPa.

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