A samarium-cobalt magnet and a method for manufacturing the same

Abstract

This invention discloses a samarium-cobalt magnet and its preparation method. The samarium-cobalt magnet uses low-melting-point alloy powder, samarium oxide powder, and samarium-cobalt magnetic powder as raw materials; the composition of the samarium-cobalt magnetic powder is Sm(Co) 1‑a‑b‑ c Fe a Cu b Zr c ) z The composition of the low-melting-point alloy is RE. 1‑x M x RE is one or more of Pr, Nd, and Sm, and M is one or more of Cu, Al, and Ga. The preparation method includes: melting samarium-cobalt alloy raw materials and low-melting-point alloy raw materials, followed by coarse crushing, medium crushing, and air jet milling to obtain samarium-cobalt magnetic powder and low-melting-point alloy powder; mixing samarium oxide powder, low-melting-point alloy powder, and samarium-cobalt magnetic powder to obtain magnetic powder; sequentially performing magnetic field forming, cold isostatic pressing, and low-temperature sintering to obtain a sintered billet; and sequentially subjecting the sintered billet to solution treatment and aging heat treatment. The samarium-cobalt magnet of this invention exhibits significantly improved bending strength and fracture toughness, possessing both high magnetic properties and good mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of rare earth magnetic materials technology, and particularly relates to a samarium cobalt magnet and its preparation method. Background Technology

[0002] 2:17-type samarium cobalt (SmCo) permanent magnet material is currently the best performing permanent magnet material in terms of magnetic properties at high temperatures of 250℃ and above. Its core advantage lies in its excellent corrosion resistance and oxidation resistance. With this characteristic, this material occupies an important position that is difficult to replace with other permanent magnet materials in fields with stringent requirements for high temperature resistance, magnetic properties, and environmental adaptability, such as aerospace engines, magnetic bearings, microwave communication equipment, and high-power industrial motors.

[0003] However, the 2:17 type samarium cobalt permanent magnet material has significant performance shortcomings. Its intrinsic mechanical properties are poor, specifically, the material is prone to intragranular cleavage fracture, and its processing performance is limited, making it difficult to process into complex structures or irregularly shaped components. This defect not only severely restricts the expansion of this material in applications requiring complex-shaped magnets (such as integrated magnetic components in precision instruments), but also causes the magnets to be prone to cracking and breakage during service due to insufficient mechanical properties, significantly shortening their service life and becoming a key bottleneck hindering the further promotion and application of this material.

[0004] From a microstructural perspective, the root cause of the aforementioned mechanical performance defects lies in the specific microstructural characteristics of the 2:17 type samarium-cobalt sintered magnet: its micron-sized grains are oriented along the crystal axis, and a multiphase coexisting and coherent nanocellular structure is formed inside the grains. This nanocellular structure is specifically composed of three types of phases: one is a rhombohedral structure Sm2Co rich in Fe / Co elements. 17 The magnet consists of three phases: a cellular phase, which is the main magnetic phase; a hexagonal SmCo5 cell wall phase rich in Sm / Cu elements, which plays a role in regulating magnetic properties and interfacial bonding; and a rhombohedral SmCo3 lamellar phase rich in Zr elements, which runs through the entire nanocellular structure and is used to optimize the high-temperature stability of the magnet. However, none of these three phases possess sufficient slip systems and cannot alleviate the internal stress generated when the material is subjected to force through plastic deformation, ultimately resulting in weak overall mechanical properties of the magnet and making it prone to fracture failure.

[0005] In summary, the contradiction between the "high magnetic properties and poor mechanical properties" of existing 2:17 samarium cobalt permanent magnet materials has become a core technical challenge restricting their further application in high-end fields. Therefore, developing a 2:17 samarium cobalt permanent magnet material that can simultaneously achieve excellent high-temperature magnetic properties and good mechanical properties is a key technical direction that urgently needs to be overcome in this field. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of existing samarium cobalt magnets with high iron content, such as poor bending strength and fracture toughness, and to provide a samarium cobalt magnet with significantly improved bending strength and fracture toughness and its preparation method.

[0007] To address the aforementioned technical problems, this invention provides a samarium-cobalt magnet.

[0008] The samarium cobalt magnet is obtained by low-temperature sintering, solution treatment and aging heat treatment of raw materials including low-melting-point alloy powder, samarium oxide powder and samarium cobalt magnetic powder;

[0009] The samarium-cobalt magnetic powder is obtained by pulverizing a samarium-cobalt alloy, the stoichiometric formula of which is: Sm(Co) 1-a-b-c Fe a Cu b Zr c ) z The atomic percentages of each elemental component must meet the following range requirements:

[0010] The atomic percentage coefficient of Fe, a: 0.1 ≤ a ≤ 0.4;

[0011] The atomic percentage coefficient b of Cu is: 0.04 ≤ b ≤ 0.1;

[0012] The atomic percentage coefficient c of Zr is: 0.02 ≤ c ≤ 0.04;

[0013] The total atomic ratio coefficient z of samarium (Sm) to other metallic elements (Co, Fe, Cu, Zr) is: 7 ≤ z ≤ 8;

[0014] The low-melting-point alloy powder is obtained by pulverizing a low-melting-point alloy, and the stoichiometric formula of the low-melting-point alloy is RE. 1-x M x , where RE is one or more of Pr, Nd, and Sm, M is one or more of Cu, Al, and Ga, and 0≤x≤1.

[0015] In the aforementioned samarium-cobalt magnet, the samarium-cobalt magnetic powder has a particle size of 3–5 μm; the low-melting-point alloy powder has a particle size of 1–5 μm; and the samarium oxide powder has a particle size of 0.04–2 μm.

[0016] Furthermore, in the aforementioned samarium-cobalt magnet, the grain boundaries of the samarium-cobalt magnet are enriched with a low-melting-point phase, RE. 1-y M y (Co n Fe 1-n ) z, where RE is one or more of Pr, Nd, and Sm, M is one or more of Cu, Al, and Ga, and 0 < y < 1, 0 < Z < 0.5, 0 < n < 1.

[0017] Furthermore, in the aforementioned samarium-cobalt magnet, the average grain size of the low-melting-point phase enriched at the grain boundaries is 15–45 μm, and the size of the cellular structure within the magnet grains is 80–130 nm.

[0018] In the aforementioned samarium cobalt magnet, the content of low-melting-point alloy powder is 0.1 to 5 wt% of the mass of samarium cobalt magnetic powder; and the content of samarium oxide powder is 0.1 to 10 wt% of the mass of samarium cobalt magnetic powder.

[0019] Based on a general technical concept, the present invention also provides a method for preparing the samarium-cobalt magnet, the method comprising the following steps:

[0020] S1. Mix Sm, Co, Fe, Cu and Zr, and smelt to obtain a samarium cobalt alloy ingot; subject the samarium cobalt alloy ingot to coarse crushing, medium crushing and air jet milling in sequence to obtain samarium cobalt magnetic powder; mix one or more of Pr, Nd, Sm and one or more of Cu, Al, Ga, and smelt to obtain a low melting point alloy ingot; subject the low melting point alloy ingot to coarse crushing, medium crushing and air jet milling in sequence to obtain low melting point alloy powder;

[0021] S2. Mix samarium oxide powder, the low-melting-point alloy powder and the samarium-cobalt magnetic powder to obtain magnetic powder;

[0022] S3. The magnetic powder is subjected to magnetic field forming, cold isostatic pressing and low temperature sintering in sequence to obtain a sintered blank.

[0023] S4. The sintered blank is subjected to solution treatment and aging heat treatment in sequence to obtain samarium cobalt magnet.

[0024] In the above preparation method, the low-temperature sintering temperature in step S3 is 1190-1205℃, and the holding time is 1-4 h.

[0025] In the above preparation method, the solution temperature in step S4 is 1130–1190°C, and the solution time is 2–24 h.

[0026] In the above preparation method, the aging heat treatment temperature in step S4 is 780–870°C, and the holding time is 10–24 h.

[0027] The above-described preparation method further includes step S4, which further comprises: cooling the samarium-cobalt magnet to 400-500°C at a rate of 0.4-1°C / min and holding it at that temperature for 1-15 hours, and finally air-cooling or water-cooling it to room temperature.

[0028] Compared with the prior art, the advantages of the present invention are as follows:

[0029] (1) This invention provides a samarium cobalt magnet, in which a certain proportion of samarium oxide powder and low-melting-point alloy powder are mixed into samarium cobalt magnetic powder. The addition of a certain proportion of low-melting-point alloy powder can improve the grain boundary environment of the samarium cobalt magnet, enabling the magnet to achieve densification under low-temperature sintering conditions. The co-doping of samarium oxide powder and low-melting-point alloy powder can bring significant effects, namely, modifying the boundary environment of the magnet, reducing the full densification temperature of the magnet, reducing the average particle size of the magnet, and ultimately optimizing the magnetic properties of the samarium cobalt magnet to a certain extent, and significantly improving the bending strength and fracture toughness of the magnet.

[0030] (2) The present invention provides a method for preparing samarium cobalt magnets, which is simple and easy to operate and convenient for mass production. The prepared samarium cobalt magnets have both high magnetic properties and good mechanical properties. Attached Figure Description

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0032] Figure 1 This is a flowchart illustrating a high-mechanical-performance samarium-cobalt magnet and its preparation method according to the present invention. Detailed Implementation

[0033] The present invention will be further described below with reference to specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0034] The materials, reagents, and instruments used in the following examples are all commercially available. Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art.

[0035] A samarium-cobalt magnet of the present invention is obtained by using 0.1-5 wt% low melting point alloy powder, 0.1-10 wt% samarium oxide powder and the balance samarium-cobalt magnetic powder as raw materials, and performing low-temperature sintering, solution treatment and aging heat treatment.

[0036] The samarium cobalt magnet is obtained by low-temperature sintering, solution treatment and aging heat treatment of raw materials including low-melting-point alloy powder, samarium oxide powder and samarium cobalt magnetic powder;

[0037] The samarium-cobalt magnetic powder is obtained by pulverizing a samarium-cobalt alloy, the stoichiometric formula of which is: Sm(Co) 1-a-b-c Fe a Cu b Zr c ) zThe atomic percentages of each elemental component must meet the following range requirements:

[0038] The atomic percentage coefficient of Fe, a: 0.1 ≤ a ≤ 0.4;

[0039] The atomic percentage coefficient b of Cu is: 0.04 ≤ b ≤ 0.1;

[0040] The atomic percentage coefficient c of Zr is: 0.02 ≤ c ≤ 0.04;

[0041] The total atomic ratio coefficient z of samarium (Sm) to other metallic elements (Co, Fe, Cu, Zr) is: 7≤z≤8;

[0042] The low-melting-point alloy powder is obtained by pulverizing a low-melting-point alloy, and the stoichiometric formula of the low-melting-point alloy is RE. 1-x M x , where RE is one or more of Pr, Nd, and Sm, M is one or more of Cu, Al, and Ga, and 0≤x≤1.

[0043] This invention involves mixing a certain proportion of samarium oxide powder and low-melting-point alloy powder into samarium-cobalt magnetic powder. The addition of the low-melting-point alloy powder improves the grain boundary environment of the samarium-cobalt magnet, enabling densification of the magnet under low-temperature sintering conditions. The co-doping of samarium oxide powder and low-melting-point alloy powder yields significant effects: it modifies the boundary environment of the magnet, lowers the full densification temperature of the magnet, reduces the average particle size of the magnet, and ultimately optimizes the magnetic properties of the samarium-cobalt magnet to a certain extent, significantly improving the bending strength and fracture toughness of the magnet.

[0044] Furthermore, the particle size of samarium cobalt magnetic powder is 3-5 μm, which can reduce magnetic moment reversal loss; if the particle size is <3 μm: it is prone to agglomeration, has a large sintering shrinkage rate, and is easy to crack during processing; if the particle size is >5 μm: it has a multi-domain structure, low orientation degree, decreased remanence and magnetic energy product, low sintering density, and is prone to compositional segregation.

[0045] Furthermore, the particle size of the low-melting-point alloy powder is 1–5 μm; the particle size of the samarium oxide powder is 0.04–2 μm. Appropriate particle size helps it to be evenly distributed in the alloy and play a better role. If the particle size is too large or too small, it may affect its dispersion effect and function in the magnet.

[0046] Furthermore, the grain boundaries of samarium-cobalt magnets are enriched with a low-melting-point phase called RE. 1-y M y (Co n Fe 1-n ) zIn this context, RE is one or more of Pr, Nd, and Sm, and M is one or more of Cu, Al, and Ga, with 0 < y < 1, 0 < Z < 0.5, and 0 < n < 1. This improves the density and grain boundary toughening of samarium cobalt magnets, resulting in an average grain size of 15–45 μm. The cellular structure within the magnet crystals is complete and uniform, with a cell size of 80–130 nm.

[0047] The present invention also provides a method for preparing the above-mentioned samarium cobalt magnet, comprising the following steps:

[0048] S1. Smelting samarium-cobalt alloy raw materials to obtain samarium-cobalt alloy ingots; smelting low-melting-point alloy raw materials to obtain low-melting-point alloy ingots;

[0049] S2. The samarium cobalt alloy ingot and the low melting point alloy ingot are subjected to coarse crushing, medium crushing and air jet milling respectively to obtain samarium cobalt magnetic powder and low melting point alloy powder.

[0050] S3, low melting point alloy powder, samarium oxide powder and samarium cobalt magnetic powder are thoroughly mixed for 1 to 10 hours to obtain mixed magnetic powder;

[0051] S4. The obtained mixed magnetic powder is subjected to magnetic field forming, cold isostatic pressing and low temperature sintering in sequence to obtain a sintered and dense billet.

[0052] S5. The obtained sintered blank is subjected to solution treatment and aging heat treatment in sequence to obtain samarium cobalt magnet.

[0053] The preparation method of this invention can improve the grain boundary environment of samarium-cobalt magnets, enabling the magnets to achieve densification under low-temperature sintering conditions. The co-doping of samarium oxide powder and low-melting-point alloy powder can not only improve the density and grain boundary toughening of samarium-cobalt magnets, but also inhibit the growth of magnet grains.

[0054] Furthermore, the low-temperature sintering temperature is 1190–1205℃, and the sintering time is 1–4 h; subsequently, it is air-cooled or water-cooled to room temperature, and the density of the magnet after sintering is 8.2–8.45 g / cm³. 3 The sintering temperature of this invention is 5-10°C lower than the conventional temperature. Lowering the sintering temperature helps to refine the grain size of the magnet, thereby improving the mechanical properties of the magnet.

[0055] Example 1

[0056] A method for preparing a samarium-cobalt magnet according to the present invention, the preparation process is described in [link to document]. Figure 1 Specifically, it includes the following steps:

[0057] (1) Preparation of samarium cobalt alloy Sm(Co) bal Fe 0.22 Cu 0.06 Zr 0.02) 7.7 Samarium-cobalt alloy ingots were obtained by mixing 24.81 wt% Sm, 52.41 wt% Co, 15.61 wt% Fe, 4.84 wt% Cu and 2.32 wt% Zr and smelting them.

[0058] Preparation of low melting point alloy Pr 0.6 Al 0.1 Cu 0.3 79.53 wt% Pr, 2.54 wt% Al and 17.93 wt% Cu were mixed and smelted to obtain a low-melting-point alloy ingot.

[0059] (2) The samarium cobalt alloy ingot was subjected to coarse crushing, medium crushing and air jet milling in sequence to obtain samarium cobalt magnetic powder with a particle size of 3.7 μm. The low melting point alloy ingot was subjected to coarse crushing, medium crushing and air jet milling in sequence to obtain low melting point alloy powder with a particle size of 2.5 μm.

[0060] (3) Mix 1.5 wt% low melting point alloy powder, 2 wt% samarium oxide powder (particle size of 300 nm) and the balance samarium cobalt magnetic powder thoroughly for 5 h to obtain magnetic powder.

[0061] (4) The magnetic powder was subjected to magnetic field forming and cold isostatic pressing in sequence, and then sintered at 1200℃ for 1 h. It was then cooled to room temperature by air or water to obtain a sintered blank. The density of the sintered magnet was 8.2–8.45 g / cm³. 3 .

[0062] (5) The sintered blank is subjected to solution treatment and aging heat treatment in sequence to obtain the final magnet. The solution temperature is 1130~1190℃ and the solution time is 12h (2~24h are acceptable); the isothermal aging temperature is 780~870℃ and the holding time is 12h (10~24h are acceptable). Then, it is cooled to 400~500℃ at a rate of 0.4~1℃ / min and held for 8h (1~15h are acceptable). Finally, it is cooled to room temperature by air or water.

[0063] Comparative Example 1

[0064] A method for preparing a samarium-cobalt magnet according to the present invention includes the following steps:

[0065] (1) Preparation of samarium cobalt alloy Sm(Co) bal Fe 0.22 Cu 0.06 Zr 0.02 ) 7.7 Samarium cobalt alloy ingots were obtained by mixing 24.81 wt% Sm, 52.41 wt% Co, 15.61 wt% Fe, 4.84 wt% Cu and 2.32 wt% Zr and smelting them.

[0066] (2) The samarium cobalt alloy ingot was subjected to coarse crushing, medium crushing and air jet milling in sequence to obtain samarium cobalt magnetic powder with a particle size of 3.7 μm.

[0067] (3) The magnetic powder is subjected to magnetic field forming and cold isostatic pressing in sequence, and sintered at a low temperature of 1200℃ for 1 h. Then it is cooled to room temperature by air or water to obtain sintered blank.

[0068] (4) The sintered blank is subjected to solution treatment and aging heat treatment in sequence to obtain the final magnet.

[0069] Example 2

[0070] A method for preparing a samarium-cobalt magnet according to the present invention includes the following steps:

[0071] (1) Preparation of samarium cobalt alloy Sm(Co) bal Fe 0.26 Cu 0.06 Zr 0.02 ) 7.7 Samarium cobalt alloy ingots were obtained by mixing 24.90 wt% Sm, 46.57 wt% Co, 21.36 wt% Fe, 4.86 wt% Cu and 2.33 wt% Zr and smelting them.

[0072] Preparation of low melting point alloy Pr 0.6 Al 0.1 Cu 0.3 79.53 wt% Pr, 2.54 wt% Al and 17.93 wt% Cu were mixed and smelted to obtain a low-melting-point alloy ingot.

[0073] (2) The samarium cobalt alloy ingot was subjected to coarse crushing, medium crushing and air jet milling in sequence to obtain samarium cobalt magnetic powder with a particle size of 3.7 μm. The low melting point alloy ingot was subjected to coarse crushing, medium crushing and air jet milling in sequence to obtain low melting point alloy powder with a particle size of 2.5 μm.

[0074] (3) Mix 1.5wt% low melting point alloy powder, 2wt% samarium oxide powder (particle size 300nm) and the balance samarium cobalt magnetic powder thoroughly for 5 h to obtain magnetic powder.

[0075] (4) The magnetic powder is subjected to magnetic field forming, cold isostatic pressing, and low-temperature sintering in sequence to obtain a dense sintered blank. The low-temperature sintering temperature is 1195℃, and the sintering time is 1 h. This sintering temperature is 5-10℃ lower than the traditional temperature. Subsequently, it is air-cooled or water-cooled to room temperature. After sintering, the density of the magnet is 8.2-8.45 g / cm³. 3 .

[0076] (5) The sintered blank is subjected to solution treatment and aging heat treatment in sequence to obtain the final magnet. The solution temperature is 1130~1190℃ and the solution time is 12h (2~24h are acceptable); the isothermal aging temperature is 780~870℃ and the holding time is 12h (10~24h are acceptable). Then, it is cooled to 400~500℃ at a rate of 0.4~1℃ / min and held for 8h (1~15h are acceptable). Finally, it is cooled to room temperature by air or water.

[0077] Comparative Example 2

[0078] A method for preparing a samarium-cobalt magnet according to the present invention includes the following steps:

[0079] (1) Preparation of samarium cobalt alloy Sm(Co) bal Fe 0.26 Cu 0.06 Zr 0.02 ) 7.7 Samarium cobalt alloy ingots were obtained by mixing 24.90 wt% Sm, 46.57 wt% Co, 21.36 wt% Fe, 4.86 wt% Cu and 2.33 wt% Zr and smelting them.

[0080] (2) The samarium cobalt alloy ingot was subjected to coarse crushing, medium crushing and air jet milling in sequence to obtain samarium cobalt magnetic powder with a particle size of 3.7 μm.

[0081] (3) The magnetic powder is subjected to magnetic field forming and cold isostatic pressing in sequence, and sintered at a low temperature of 1205℃ for 1 h. Then it is cooled to room temperature by air or water to obtain sintered blank.

[0082] (4) The sintered blank is subjected to solution treatment and aging heat treatment in sequence to obtain the final magnet.

[0083] Example 3

[0084] A method for preparing a samarium-cobalt magnet according to the present invention includes the following steps:

[0085] (1): Preparation of samarium-cobalt alloy Sm(Co) bal Fe 0.30 Cu 0.06 Zr 0.02 ) 7.7 Samarium-cobalt alloy ingots were obtained by mixing 24.81 wt% Sm, 52.41 wt% Co, 15.61 wt% Fe, 4.84 wt% Cu and 2.32 wt% Zr and smelting them.

[0086] Preparation of low melting point alloy Pr 0.6 Al 0.1 Cu 0.379.53 wt% Pr, 2.54 wt% Al and 17.93 wt% Cu were mixed and smelted to obtain a low-melting-point alloy ingot.

[0087] (2) The samarium cobalt alloy ingot was subjected to coarse crushing, medium crushing and air jet milling in sequence to obtain samarium cobalt magnetic powder with a particle size of 3.7 μm. The low melting point alloy ingot was subjected to coarse crushing, medium crushing and air jet milling in sequence to obtain low melting point alloy powder with a particle size of 2.5 μm.

[0088] (3) Mix 1.5 wt% low melting point alloy powder, 2 wt% samarium oxide powder (particle size 300 nm) and the balance samarium cobalt magnetic powder thoroughly for 5 h to obtain magnetic powder.

[0089] (4) The magnetic powder is subjected to magnetic field forming, cold isostatic pressing, and low-temperature sintering in sequence to obtain a dense sintered blank. The low-temperature sintering temperature is 1205℃, and the sintering time is 1 h. This sintering temperature is 5-10℃ lower than the traditional temperature. Subsequently, it is air-cooled or water-cooled to room temperature. After sintering, the density of the magnet is 8.2-8.45 g / cm³. 3 .

[0090] (5) The sintered blank is subjected to solution treatment and aging heat treatment in sequence to obtain the final magnet. The solution temperature is 1130~1190℃ and the solution time is 12h (2~24h are acceptable); the isothermal aging temperature is 780~870℃ and the holding time is 12h (10~24h are acceptable). Then, it is cooled to 400~500℃ at a rate of 0.4~1℃ / min and held for 8h (1~15h are acceptable). Finally, it is cooled to room temperature by air or water.

[0091] Comparative Example 3

[0092] A method for preparing a samarium-cobalt magnet according to the present invention includes the following steps:

[0093] (1) Preparation of samarium cobalt alloy Sm(Co) bal Fe 0.30 Cu 0.06 Zr 0.02 ) 7.7 Samarium-cobalt alloy ingots were obtained by mixing 24.81 wt% Sm, 52.41 wt% Co, 15.61 wt% Fe, 4.84 wt% Cu and 2.32 wt% Zr and smelting them.

[0094] (2) The samarium cobalt alloy ingot was subjected to coarse crushing, medium crushing and air jet milling in sequence to obtain samarium cobalt magnetic powder with a particle size of 3.7 μm.

[0095] (3) The magnetic powder is subjected to magnetic field forming and cold isostatic pressing in sequence, and sintered at a low temperature of 1200℃ for 1 h. Then it is cooled to room temperature by air or water to obtain sintered blank.

[0096] (4) The sintered blank is subjected to solution treatment and aging heat treatment in sequence to obtain the final magnet.

[0097] The magnets prepared according to the above embodiments and comparative examples were subjected to room temperature (20°C) magnetic properties tests. The performance results are shown in Table 1 below.

[0098] Table 1: Comparison of Test Results in Examples and Comparative Examples

[0099]

[0100] The results in Table 1 show that the average grain size of the magnets in the example is significantly smaller than that in the comparative example, and their coercivity, flexural strength, and fracture toughness are all higher than those in the comparative example. This demonstrates that by adding appropriate amounts of samarium oxide and low-melting-point alloys to samarium-cobalt magnetic powder, the grain boundary environment of the samarium-cobalt magnet can be modified, and grain growth can be suppressed. This method for preparing samarium-cobalt magnets not only improves the magnetic properties of the magnets to a certain extent but also significantly enhances their flexural strength and fracture toughness. This invention provides a high-mechanical-performance samarium-cobalt magnet and its preparation method, which has important guiding significance for the preparation of samarium-cobalt magnets.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A samarium-cobalt magnet, characterized in that, The samarium-cobalt magnet is prepared by low-temperature sintering, solution treatment and aging heat treatment using a mixture of low-melting-point alloy powder, samarium oxide powder and samarium-cobalt magnetic powder as raw materials. The samarium-cobalt magnetic powder is obtained by pulverizing a samarium-cobalt alloy, the stoichiometric formula of which is: Sm(Co1-ab-cFeaCubZrc)z, and the atomic percentages of each element component meet the following requirements: The atomic percentage coefficient of Fe, a: 0.1 ≤ a ≤ 0.4; The atomic percentage coefficient b of Cu is: 0.04 ≤ b ≤ 0.1; The atomic percentage coefficient c of Zr is: 0.02 ≤ c ≤ 0.04; The total atomic ratio coefficient z of samarium (Sm) with other metallic elements (Co, Fe, Cu, Zr) is: 7 ≤ z ≤ 8; The low-melting-point alloy powder is obtained by pulverizing a low-melting-point alloy. The stoichiometric formula of the low-melting-point alloy is RE1-xMx, where RE is one or more of Pr, Nd, and Sm, M is one or more of Cu, Al, and Ga, and 0≤x≤1. The content of the low melting point alloy powder is 0.1 to 5 wt% of the mass of samarium cobalt magnetic powder; the content of the samarium oxide powder is 0.1 to 10 wt% of the mass of samarium cobalt magnetic powder.

2. The samarium-cobalt magnet according to claim 1, characterized in that, The samarium cobalt magnetic powder has a particle size of 3–5 μm; the low melting point alloy powder has a particle size of 1–5 μm; and the samarium oxide powder has a particle size of 0.04–2 μm.

3. The samarium-cobalt magnet according to claim 1, characterized in that, The grain boundary enrichment of samarium cobalt magnets is a low-melting-point phase RE1-yMy(ConFe1-n)z, where RE is one or more of Pr, Nd, and Sm, and M is one or more of Cu, Al, and Ga, and 0 < y < 1, 0 < Z < 0.5, and 0 < n < 1.

4. The samarium-cobalt magnet according to claim 3, characterized in that, The average grain size of the low-melting-point phase enriched at the grain boundaries is 15–45 μm, and the size of the cellular structure within the magnet crystal is 80–130 nm.

5. A method for preparing a samarium-cobalt magnet according to any one of claims 1 to 4, characterized in that, The preparation method includes the following steps: S1. Mix Sm, Co, Fe, Cu and Zr, and smelt to obtain a samarium-cobalt alloy ingot; subject the samarium-cobalt alloy ingot to coarse crushing, medium crushing and air jet milling in sequence to obtain samarium-cobalt magnetic powder; mix Pr, Al and Cu, and smelt to obtain a low-melting-point alloy ingot; subject the low-melting-point alloy ingot to coarse crushing, medium crushing and air jet milling in sequence to obtain low-melting-point alloy powder. S2. Mix samarium oxide powder, the low-melting-point alloy powder and the samarium-cobalt magnetic powder to obtain magnetic powder; S3. The magnetic powder is subjected to magnetic field forming, cold isostatic pressing and low temperature sintering in sequence to obtain a sintered blank. S4. The sintered blank is subjected to solution treatment and aging heat treatment in sequence to obtain samarium cobalt magnet.

6. The preparation method according to claim 5, characterized in that, The low-temperature sintering temperature in S3 is 1190–1205°C, and the holding time is 1–4 h.

7. The preparation method according to claim 5, characterized in that, The solution temperature in S4 is 1130–1190°C, and the solution time is 2–24 h.

8. The preparation method according to claim 5, characterized in that, The aging heat treatment in S4 is performed at a temperature of 780–870°C for 10–24 hours.

9. The preparation method according to claim 5, characterized in that, The S4 step further includes: cooling the samarium cobalt magnet to 400-500°C at a rate of 0.4-1°C / min, holding it at that temperature for 1-15 hours, and finally air-cooling or water-cooling it to room temperature.

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