A samarium-cobalt magnet with high iron content and a method for preparing the same

Abstract

The application belongs to the technical field of magnetic materials, and particularly relates to a high-iron-content samarium-cobalt magnet and a preparation method thereof. The preparation method comprises the following steps: firstly, high-iron-content samarium-cobalt main-phase magnetic powder and copper-rich auxiliary alloy powder are mixed according to a certain proportion by adopting a double-alloy process, and an appropriate amount of copper powder is added into the mixed magnetic powder, and then magnetic field forming, cold isostatic pressing and sintering are sequentially performed; then, a two-stage solid solution process is adopted to obtain a solid solution precursor with large-size grains; finally, a three-stage aging process is adopted, so that the cell structure is complete and uniform, and the copper element is concentratedly distributed at the cell wall. The prepared samarium-cobalt magnet has high coercivity and high squareness, is simple and easy to operate, and is convenient for batch production.

Description

Technical Field

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

[0002] 2:17 samarium cobalt (SmCo) magnets are currently the best permanent magnet materials in terms of magnetic properties above 250℃, exhibiting excellent corrosion resistance and oxidation resistance. They play an irreplaceable role in high-precision technology fields such as aerospace engines, magnetic bearings, and microwave communications. The rapid development of emerging technology fields such as new energy vehicles and rail transportation has placed higher demands on the temperature resistance and maximum energy product of permanent magnet materials. Based on the high Curie temperature advantage of 2:17 SmCo permanent magnet materials, appropriately increasing the iron content in the magnet is an effective way to develop high-temperature resistant magnets with high energy product. Studies have shown that increasing the iron substitution for cobalt in 2:17 SmCo magnets can directly improve the remanence of the magnet, thereby obtaining a higher theoretical energy product. However, when the iron content exceeds 20% (mass fraction), the squareness and coercivity of the magnet deteriorate sharply, restricting the development of the maximum energy product. This is mainly attributed to the increase in structural defects in high-iron-content magnets. Therefore, how to overcome the technical barriers of high energy product 2:17 type SmCo magnets is a key issue that needs to be studied. Summary of the Invention

[0003] The purpose of this invention is to provide a high-iron-content samarium-cobalt magnet and its preparation method, aiming to solve the problems of easy formation of defect structures at grain boundaries and incomplete cellular structures within the grains of high-iron-content samarium-cobalt magnets, and to prepare a high-iron-content samarium-cobalt magnet with high coercivity, high squareness and high magnetic energy product.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a high-iron-content samarium-cobalt magnet, comprising: a high-iron-content samarium-cobalt alloy, a copper-rich auxiliary alloy, and copper powder, wherein the mass ratio of the high-iron-content samarium-cobalt alloy to the copper-rich auxiliary alloy is 5:1 to 20:1; and the copper powder accounts for 1 to 5 wt.% of the sum of the mass of the high-iron-content samarium-cobalt alloy and the copper-rich auxiliary alloy.

[0005] Furthermore, the chemical formula of the high-iron content samarium-cobalt alloy is Sm(Co) 1-a-b-c Fe a Cu b Zr c ) z Where 0.16≤a≤0.4, 0.04≤b≤0.1, 0.018≤c≤0.033, 7≤z≤8; the copper-rich auxiliary alloy composition is RE(Co 1-u Cu u )5, where RE is one or more of Pr, Nd, and Sm, and 0.4≤u≤1.

[0006] Furthermore, the final state of the high-iron content samarium cobalt magnet has a complete and uniform cellular structure within the crystal, with a cell size of 100–150 nm; the copper-rich 1:5H phase is generated in the grain boundaries in the form of cell walls.

[0007] Furthermore, the coercivity of the high-iron content samarium cobalt magnet is not less than 25 kOe, the squareness is not less than 0.75, and the maximum magnetic energy product is not less than 33 MGOe.

[0008] Another object of the present invention is to provide a method for preparing the above-mentioned high-iron-content samarium-cobalt magnet, the preparation method specifically including the following steps:

[0009] S1) According to the design ratio, high iron content samarium cobalt alloy raw materials and copper-rich auxiliary alloy raw materials are smelted separately to obtain high iron content samarium cobalt alloy ingots and copper-rich auxiliary alloy ingots;

[0010] S2) The high-iron-content samarium-cobalt alloy ingot and the copper-rich auxiliary alloy ingot obtained in S1) are subjected to coarse crushing, medium crushing and air jet milling respectively to obtain high-iron-content samarium-cobalt magnetic powder and copper-rich auxiliary alloy powder.

[0011] S3) The high-iron content samarium cobalt magnetic powder and copper-rich auxiliary alloy powder obtained in S2) are mixed in a certain proportion, and copper powder is added to the mixed magnetic powder. Then, the mixture is mixed, magnetic field forming, cold isostatic pressing and sintering are carried out in sequence to obtain a sintered dense magnet.

[0012] S4) The sintered magnet obtained in S3) is subjected to two-stage solid solution treatment to obtain a single-phase solid solution precursor with a grain size greater than 65μm;

[0013] S5) The solid solution precursor obtained in S4) is subjected to a three-stage aging treatment to obtain a high-iron content samarium-cobalt magnet with a complete and uniform cellular structure and a concentrated distribution of copper elements at the cell wall.

[0014] Furthermore, the high-iron content samarium cobalt magnetic powder obtained in S2) has a particle size of 3-5 μm, of which powder with a size of 3.5-4.2 μm accounts for more than 90%; the copper-rich auxiliary alloy powder has a particle size of 2-4 μm, of which powder with a size of 2-3 μm accounts for more than 90%.

[0015] Furthermore, the copper powder in step S3) has a particle size of 0.5–3 μm, and the density of the magnet after sintering is 8.3–8.45 g / cm³. 3 .

[0016] Furthermore, the two-stage solution treatment process in S4) specifically involves: first holding the sintered billet at a temperature of 1180–1205°C for 1–4 hours, then holding it at a temperature of 1150–1190°C for 4–48 hours, and then air-cooling or water-cooling it to room temperature.

[0017] Furthermore, the three-stage aging process in S5) is as follows: first, the temperature is kept at 600-780℃ for 1-5 hours, then at 780-870℃ for 10-24 hours, then cooled to 400-500℃ at a rate of 0.4-1℃ / min and kept at that temperature for 1-15 hours, and finally cooled to room temperature by air or water.

[0018] The high-iron content samarium cobalt magnet prepared by the above-mentioned method can be used in high-power permanent magnet motors or rail transportation.

[0019] The beneficial effects of this invention are as follows: Due to the adoption of the above technical solution, the preparation method of this invention employs a dual-alloy process. First, high-iron-content samarium-cobalt main phase magnetic powder is mixed with copper-rich auxiliary alloy powder, then copper powder is added. Subsequently, mixing, magnetic field forming, cold isostatic pressing, and sintering are performed sequentially to obtain a sintered, dense magnet. Then, a two-stage solid solution process is used to obtain a solid solution precursor with large-sized grains. Finally, a three-stage aging process is used, resulting in a complete and uniform cellular structure within the final magnet, with a cell size of 100–150 nm. The addition of appropriate amounts of copper-rich auxiliary alloy and copper powder avoids the appearance of copper-poor regions at grain boundaries and promotes the formation of the copper-rich 1:5H phase in the form of cell walls within the grain boundaries. The prepared samarium-cobalt magnet possesses both high coercivity and high squareness, is simple and easy to operate, and is suitable for mass production. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating a method for preparing a high-iron-content samarium-cobalt magnet according to the present invention. Detailed Implementation

[0021] The present invention will be further illustrated below with reference to embodiments and comparative embodiments. It should be understood that the following specific embodiments are only used to illustrate the features and advantages of the present invention, and are not intended to limit the scope of the present invention.

[0022] like Figure 1 As shown, this invention discloses a method for preparing a high-iron-content samarium-cobalt magnet. The method specifically includes the following steps:

[0023] S1) Smelt high-iron-content samarium-cobalt alloy raw materials and copper-rich auxiliary alloy raw materials respectively to obtain high-iron-content samarium-cobalt alloy ingots and copper-rich auxiliary alloy ingots;

[0024] S2) The high-iron-content samarium-cobalt alloy ingot and the copper-rich auxiliary alloy ingot obtained in S1) are subjected to coarse crushing, medium crushing and air jet milling respectively;

[0025] S3) The high-iron content samarium cobalt magnetic powder and copper-rich auxiliary alloy powder obtained in S2) are mixed in a ratio of 5:1 to 20:1, and 1 to 5 wt.% copper powder is added to the mixed magnetic powder. Then, the mixture is mixed, magnetic field forming, cold isostatic pressing and sintering are carried out in sequence to obtain a sintered dense magnet.

[0026] S4) The sintered magnet obtained in S3) is subjected to two-stage solid solution treatment to obtain a single-phase solid solution precursor with a grain size greater than 65μm;

[0027] S5) The solid solution precursor obtained in S4) is subjected to a three-stage aging treatment to obtain a complete and uniform cellular structure inside the grains, and copper elements are concentrated in the cell walls.

[0028] Furthermore, the high-iron content samarium-cobalt alloy in S1) has the chemical formula Sm(Co) 1-a-b-c Fe a Cu b Zr c ) z Where 0.16≤a≤0.4, 0.04≤b≤0.1, 0.018≤c≤0.033, 7≤z≤8; the copper-rich auxiliary alloy composition is RE(Co 1- u Cu u )5, where RE is one or more of Pr, Nd, and Sm, and 0.4≤u≤1.

[0029] Furthermore, the high-iron content samarium cobalt magnetic powder obtained in S2) has a particle size of 3-5 μm, of which powder with a size of 3.5-4.2 μm accounts for more than 90%; the copper-rich auxiliary alloy powder has a particle size of 2-4 μm, of which powder with a size of 2-3 μm accounts for more than 90%.

[0030] Furthermore, the copper powder in S3 has a particle size of 0.5–3 μm, and the density of the magnet after sintering is 8.3–8.45 g / cm³. 3 Furthermore, copper is enriched in the grain boundaries of the sintered magnet.

[0031] Furthermore, in S4), the two-stage solution treatment process adds a short high-temperature holding step before the conventional solution treatment process. Specifically, the sintered billet is held at 1180-1205℃ for 1-4 hours and at 1150-1190℃ for 4-48 hours, respectively, and then air-cooled or water-cooled to room temperature.

[0032] Furthermore, in S4), as the two-stage solid solution process proceeds, the grain size of the magnet gradually increases and the elements within the grain and at the grain boundaries gradually become homogenized. This not only significantly reduces the proportion of grain boundary defects in conventional magnets, but also suppresses the occurrence of copper-poor phenomena at grain boundaries.

[0033] Furthermore, the three-stage aging process in S5) adds a low-temperature heat preservation step before the conventional two-stage aging process. Specifically, the solid solution magnet is first kept at 600-780℃ for 1-5 hours, then kept at 780-870℃ for 10-24 hours, cooled to 400-500℃ at a rate of 0.4-1℃ / min, and kept at this temperature for 1-15 hours. Finally, it is air-cooled or water-cooled to room temperature.

[0034] Furthermore, the cellular structure within the final magnet obtained in S5) is complete and uniform, with a cell size of 100-150 nm. The addition of an appropriate amount of copper-rich auxiliary alloy and copper powder not only avoids the appearance of copper-poor regions at the grain boundaries, but also promotes the formation of the copper-rich 1:5H phase in the form of cell walls in the grain boundaries, ultimately resulting in a samarium-cobalt magnet with high iron content.

[0035] Example 1

[0036] The first step is to separately smelt Sm(Co) with a nominal composition of 100%. 0.635 Fe 0.28 Cu 0.065 Zr 0.02 ) 7.75 and Sm(Co 0.5 Cu 0.5 The process involves two steps: First, high-iron-content samarium-cobalt alloy and copper-rich auxiliary alloy are used. Second, the obtained high-iron-content samarium-cobalt alloy ingot and copper-rich auxiliary alloy ingot are subjected to coarse crushing, medium crushing, and air jet milling, respectively. The high-iron-content samarium-cobalt magnetic powder has a particle size of 3–5 μm, with over 90% of the powder having a size of 3.5–4.2 μm. The copper-rich auxiliary alloy powder has a particle size of 2–4 μm, with over 90% of the powder having a size of 2–3 μm. Third, the obtained high-iron-content samarium-cobalt magnetic powder and copper-rich auxiliary alloy powder are mixed in a 10:1 ratio, and 2 wt.% copper powder is added to the mixed magnetic powder. The mixture is then subjected to mixing, magnetic field forming, cold isostatic pressing, and sintering to obtain a dense sintered magnet. The copper powder has a particle size of 1 μm, and the density of the sintered magnet is 8.35 g / cm³. 3The fourth step involves subjecting the obtained sintered billet to a two-stage solution treatment: holding it at 1195℃ for 2 hours and at 1180℃ for 10 hours, respectively, followed by air cooling or water cooling to room temperature to obtain a single-phase solid solution precursor with a grain size greater than 65 μm. As the two-stage solution treatment progresses, the grain size of the magnet gradually increases, and the elements within the grains and at the grain boundaries gradually become homogenized. This not only significantly reduces the proportion of grain boundary defects in conventional magnets but also suppresses the occurrence of copper-poor phenomena at grain boundaries. The fifth step involves a three-stage aging treatment: the obtained solid solution magnet is held at 750℃ for 4 hours and at 810℃ for 24 hours, respectively, then cooled to 400℃ at a rate of 0.5℃ / min and held at this temperature for 10 hours, finally air-cooled or water-cooled to room temperature. After aging, the magnet exhibits a complete and uniform intragranular structure, with copper elements concentrated at the cell walls, and a cell size of approximately 120 nm. More importantly, the addition of appropriate amounts of copper-rich auxiliary alloys and copper powder not only prevented the appearance of copper-poor regions at the grain boundaries, but also promoted the formation of copper-rich 1:5H phases in the form of cell walls at the grain boundaries, ultimately resulting in samarium-cobalt magnets with high iron content.

[0037] Example 2

[0038] The same high-iron-content samarium-cobalt alloy with the same composition and preparation process as in Example 1 was used, the only difference being that the copper-rich auxiliary alloying component was selected as Sm(Co). 0.4 Cu 0.6 5.

[0039] Example 3

[0040] The same high-iron-content samarium-cobalt alloy with the same composition and preparation process as in Example 1 was used, the only difference being that the copper-rich auxiliary alloying component was selected as Sm(Co). 0.3 Cu 0.7 5.

[0041] Example 4

[0042] The same high-iron-content samarium-cobalt alloy with the same composition and preparation process as in Example 1 was used, the only difference being that the copper-rich auxiliary alloying component was selected as Pr. 0.2 Sm 0.8 (Co 0.5 Cu 0.5 5.

[0043] Comparative Example 1

[0044] The first step is to smelt Sm(Co) with a nominal composition of Sm(Co). 0.635 Fe 0.28 Cu 0.065 Zr 0.02 ) 7.75The process involves three steps: First, a high-iron-content samarium-cobalt alloy is formed. Second, the obtained high-iron-content samarium-cobalt alloy ingot is subjected to coarse crushing, medium crushing, and air jet milling. The samarium-cobalt magnetic powder has a particle size of 3–5 μm, with over 90% of the powder having a size of 3.5–4.2 μm. Third, the obtained high-iron-content samarium-cobalt magnetic powder is subjected to mixing, magnetic field forming, cold isostatic pressing, and sintering to obtain a dense sintered magnet. The density of the sintered magnet is 8.35 g / cm³. 3 The fourth step involves subjecting the obtained sintered billet to two-stage solution treatment: holding it at 1195℃ for 2 hours and at 1180℃ for 10 hours, respectively, followed by air cooling or water cooling to room temperature to obtain a single-phase solid solution precursor with a grain size greater than 65 μm. The fifth step involves a three-stage aging treatment: the obtained solid solution magnet is held at 750℃ for 4 hours and at 810℃ for 20 hours, respectively, then cooled to 400℃ at a rate of 0.5℃ / min and held at this temperature for 10 hours, finally air-cooled or water-cooled to room temperature. After aging, the magnet exhibits a complete and uniform intragranular structure, with copper elements concentrated at the cell walls, and a cell size of 120 nm. However, the grain boundaries of the magnet lack cellular structure and show localized copper depletion.

[0045] Comparative Example 2

[0046] The first step is to separately smelt Sm(Co) with a nominal composition of 100%. 0.635 Fe 0.28 Cu 0.065 Zr 0.02 ) 7.75 and Sm(Co 0.5 Cu 0.5 The process involves three steps: First, high-iron-content samarium-cobalt alloy and copper-rich auxiliary alloy are used. Second, the obtained high-iron-content samarium-cobalt alloy ingot and copper-rich auxiliary alloy ingot are subjected to coarse crushing, medium crushing, and air jet milling, respectively. The samarium-cobalt magnetic powder has a particle size of 3–5 μm, with over 90% of the powder having a size of 3.5–4.2 μm. The copper-rich auxiliary alloy powder has a particle size of 2–4 μm, with over 90% of the powder having a size of 2–3 μm. Third, the obtained high-iron-content samarium-cobalt magnetic powder and copper-rich auxiliary alloy powder are mixed in a 10:1 ratio, followed by mixing, magnetic field forming, cold isostatic pressing, and sintering to obtain a dense sintered magnet. The density of the sintered magnet is 8.35 g / cm³. 3The fourth step involves a two-stage solution treatment of the obtained sintered billet: holding at 1195℃ for 2 hours and at 1180℃ for 10 hours, respectively, followed by air cooling or water cooling to room temperature, resulting in a single-phase solid solution precursor with a grain size greater than 65 μm. The fifth step involves a three-stage aging treatment: holding the obtained solid solution magnet at 750℃ for 4 hours and at 810℃ for 24 hours, respectively, followed by cooling to 400℃ at a rate of 0.5℃ / min and holding at this temperature for 10 hours, finally air cooling or water cooling to room temperature. After aging, the magnet exhibits a complete and uniform cellular structure, with copper elements concentrated at the cell walls, and a cell size of 120 nm. The addition of an appropriate amount of copper-rich auxiliary alloy locally reduces the occurrence of copper-poor regions at grain boundaries, and to some extent promotes the formation of the copper-rich 1:5H phase in the form of cell walls within the grain boundaries.

[0047] Comparative Example 3

[0048] The first step is to smelt Sm(Co) with a nominal composition of Sm(Co). 0.635 Fe 0.28 Cu 0.065 Zr 0.02 ) 7.75 The process involves three steps: First, a high-iron-content samarium-cobalt alloy is formed. Second, the obtained high-iron-content samarium-cobalt alloy ingot is subjected to coarse crushing, medium crushing, and air jet milling. The samarium-cobalt magnetic powder has a particle size of 3–5 μm, with over 90% of the powder having a size of 3.5–4.2 μm. Third, 2 wt.% copper powder is added to the high-iron-content samarium-cobalt magnetic powder, followed by mixing, magnetic field forming, cold isostatic pressing, and sintering to obtain a dense sintered magnet. The copper powder has a particle size of 1 μm, and the density of the sintered magnet is 8.35 g / cm³. 3 The fourth step involves a two-stage solution treatment of the obtained sintered billet, specifically holding it at 1195℃ for 2 hours and at 1180℃ for 10 hours, followed by air cooling or water cooling to room temperature to obtain a single-phase solid solution precursor with a grain size greater than 65 μm. As the two-stage solution process proceeds, the copper enriched at the grain boundaries is gradually homogenized, effectively avoiding the copper-poor phenomenon at grain boundaries common in magnets. The fifth step involves a three-stage aging treatment, specifically holding the obtained solid solution magnet at 750℃ for 4 hours and at 810℃ for 24 hours, followed by cooling to 400℃ at a rate of 0.5℃ / min and holding at this temperature for 10 hours, finally air cooling or water cooling to room temperature. After aging, the magnet exhibits a complete and uniform cellular structure, with copper elements concentrated at the cell walls, and a cell size of 120 nm. The addition of an appropriate amount of copper powder avoids the appearance of copper-poor regions at the grain boundaries, but no copper-rich 1:5H cell wall phase is formed at the grain boundaries.

[0049] Example 5

[0050] The first step is to separately smelt Sm(Co) with a nominal composition of 100%. 0.615 Fe0.31 Cu 0.055 Zr 0.02 ) 7.75 and Sm(Co 0.5 Cu 0.5 The process involves several steps. First, the high-iron-content samarium-cobalt alloy ingot and the copper-rich auxiliary alloy ingot are subjected to coarse crushing, medium crushing, and air jet milling, respectively. The samarium-cobalt magnetic powder has a particle size of 3–5 μm, with over 90% of the powder having a size of 3.5–4.2 μm. The copper-rich auxiliary alloy powder has a particle size of 2–4 μm, with over 90% of the powder having a size of 2–3 μm. Second, the high-iron-content samarium-cobalt magnetic powder and the copper-rich auxiliary alloy powder are mixed in a 10:1 ratio, and 2 wt.% copper powder is added to the mixed magnetic powder. The mixture is then subjected to mixing, magnetic field forming, cold isostatic pressing, and sintering to obtain a dense sintered magnet. The copper powder has a particle size of 1 μm, and the density of the sintered magnet is 8.35 g / cm³. 3 The fourth step involves subjecting the obtained sintered billet to a two-stage solution treatment: holding it at 1185℃ for 2 hours and at 1155℃ for 10 hours, respectively, followed by air cooling or water cooling to room temperature to obtain a single-phase solid solution precursor with a grain size greater than 65 μm. As the two-stage solution treatment proceeds, the copper enriched at the grain boundaries is gradually homogenized, effectively avoiding the copper-poor phenomenon at grain boundaries common in magnets. The fifth step involves a three-stage aging treatment: the obtained solid solution magnet is held at 750℃ for 4 hours and at 810℃ for 24 hours, respectively, then cooled to 400℃ at a rate of 0.5℃ / min and held at this temperature for 10 hours, finally air-cooled or water-cooled to room temperature. After aging, the magnet exhibits a complete and uniform cellular structure, with copper elements concentrated at the cell walls, and a cell size of 120 nm. The addition of appropriate amounts of copper-rich auxiliary alloys and copper powder not only prevented the appearance of copper-poor regions at the grain boundaries, but also promoted the formation of copper-rich 1:5H phases in the form of cell walls at the grain boundaries, ultimately resulting in samarium-cobalt magnets with high iron content.

[0051] Example 6

[0052] The same high-iron-content samarium-cobalt alloy with the same composition and preparation process as in Example 5 was used, the only difference being that the copper-rich auxiliary alloying component was selected as Sm(Co). 0.4 Cu 0.6 5.

[0053] Example 7

[0054] The same high-iron-content samarium-cobalt alloy with the same composition and preparation process as in Example 5 was used, the only difference being that the copper-rich auxiliary alloying component was selected as Sm(Co). 0.3 Cu 0.7 5.

[0055] Example 8

[0056] The same high-iron-content samarium-cobalt alloy with the same composition and preparation process as in Example 5 was used, the only difference being that the copper-rich auxiliary alloying component was selected as Pr. 0.2 Sm 0.8 (Co 0.5 Cu 0.5 5.

[0057] Comparative Example 4

[0058] The first step is to melt the nominal component Sm(Co) 0.615 Fe 0.31 Cu 0.055 Zr 0.02 ) 7.75 The process involves three steps: First, a high-iron-content samarium-cobalt alloy is formed. Second, the obtained high-iron-content samarium-cobalt alloy ingot is subjected to coarse crushing, medium crushing, and air jet milling. The samarium-cobalt magnetic powder has a particle size of 3–5 μm, with over 90% of the powder having a size of 3.5–4.2 μm. Third, the obtained high-iron-content samarium-cobalt magnetic powder is subjected to mixing, magnetic field forming, cold isostatic pressing, and sintering to obtain a dense sintered magnet. The density of the sintered magnet is 8.35 g / cm³. 3 The fourth step involves subjecting the obtained sintered billet to two-stage solution treatment: holding at 1185℃ for 2 hours and at 1155℃ for 10 hours, respectively, followed by air cooling or water cooling to room temperature to obtain a single-phase solid solution precursor with a grain size greater than 65 μm. The fifth step involves a three-stage aging treatment: the obtained solid solution magnet is held at 750℃ for 4 hours and at 810℃ for 20 hours, respectively, then cooled to 400℃ at a rate of 0.5℃ / min and held at this temperature for 10 hours, finally air-cooled or water-cooled to room temperature. After aging, the magnet exhibits a complete and uniform cellular structure within the grains, with copper elements concentrated at the cell walls and a cell size of 120 nm. However, no cellular structure is present at the grain boundaries, and localized copper depletion is observed.

[0059] Comparative Example 5

[0060] The first step is to separately smelt Sm(Co) with a nominal composition of 100%. 0.615 Fe 0.31 Cu 0.055 Zr 0.02 ) 7.75 and Sm(Co 0.5 Cu 0.5The process involves three steps: First, high-iron-content samarium-cobalt alloy and copper-rich auxiliary alloy are used. Second, the obtained high-iron-content samarium-cobalt alloy ingot and copper-rich auxiliary alloy ingot are subjected to coarse crushing, medium crushing, and air jet milling, respectively. The samarium-cobalt magnetic powder has a particle size of 3–5 μm, with over 90% of the powder having a size of 3.5–4.2 μm. The copper-rich auxiliary alloy powder has a particle size of 2–4 μm, with over 90% of the powder having a size of 2–3 μm. Third, the obtained high-iron-content samarium-cobalt magnetic powder and copper-rich auxiliary alloy powder are mixed in a 10:1 ratio, followed by mixing, magnetic field forming, cold isostatic pressing, and sintering to obtain a dense sintered magnet. The density of the sintered magnet is 8.35 g / cm³. 3 The fourth step involves a two-stage solution treatment of the obtained sintered billet, specifically holding it at 1185℃ for 2 hours and at 1155℃ for 10 hours, followed by air cooling or water cooling to room temperature to obtain a single-phase solid solution precursor with a grain size greater than 65 μm. The fifth step involves a three-stage aging treatment, specifically holding the obtained solid solution magnet at 750℃ for 4 hours and at 810℃ for 24 hours, followed by cooling to 400℃ at a rate of 0.5℃ / min and holding at this temperature for 10 hours, finally air cooling or water cooling to room temperature. After aging, the magnet exhibits a complete and uniform cellular structure, with copper elements concentrated at the cell walls, and a cell size of 120 nm. The addition of an appropriate amount of copper-rich auxiliary alloy locally reduces the occurrence of copper-poor regions at grain boundaries, and to some extent promotes the formation of the copper-rich 1:5H phase in the form of cell walls within the grain boundaries.

[0061] Comparative Example 6

[0062] The first step is to separately smelt Sm(Co) with a nominal composition of 100%. 0.615 Fe 0.31 Cu 0.055 Zr 0.02 ) 7.75 The process involves three steps: First, a high-iron-content samarium-cobalt alloy is formed. Second, the obtained high-iron-content samarium-cobalt alloy ingot is subjected to coarse crushing, medium crushing, and air jet milling. The samarium-cobalt magnetic powder has a particle size of 3–5 μm, with over 90% of the powder having a size of 3.5–4.2 μm. Third, 2 wt.% copper powder is added to the high-iron-content samarium-cobalt magnetic powder, followed by mixing, magnetic field forming, cold isostatic pressing, and sintering to obtain a dense sintered magnet. The copper powder has a particle size of 1 μm, and the density of the sintered magnet is 8.35 g / cm³. 3The fourth step involves subjecting the obtained sintered billet to a two-stage solution treatment: holding it at 1185℃ for 2 hours and at 1155℃ for 10 hours, respectively, followed by air cooling or water cooling to room temperature to obtain a single-phase solid solution precursor with a grain size greater than 65 μm. As the two-stage solution treatment proceeds, the copper enriched at the grain boundaries is gradually homogenized, effectively avoiding the copper-poor phenomenon at grain boundaries common in magnets. The fifth step involves a three-stage aging treatment: the obtained solid solution magnet is held at 750℃ for 4 hours and at 810℃ for 24 hours, respectively, then cooled to 400℃ at a rate of 0.5℃ / min and held at this temperature for 10 hours, finally air-cooled or water-cooled to room temperature. After aging, the magnet exhibits a complete and uniform cellular structure, with copper elements concentrated at the cell walls, and a cell size of 120 nm. The addition of an appropriate amount of copper powder prevented the formation of copper-poor regions at the grain boundaries, but no copper-rich 1:5H cell wall phase was formed at the grain boundaries.

[0063] The magnets prepared according to the above embodiments and comparative examples were subjected to room temperature (20°C) magnetic performance tests using a permanent magnet material measurement system. The performance results are shown in Table 1 below.

[0064] Table 1 Comparison of magnet performance parameters in the embodiments and comparative examples.

[0065]

[0066] Comparing the magnetic performance data of Example 1 and Comparative Example 1, it was found that the coercivity (H) of the magnet in Example 1 was higher. cj Squareness (H) k / H cj ) and the maximum magnetic energy product ((BH) max The magnetic properties of the examples are significantly higher than those of the comparative examples. Furthermore, by comparing the magnetic property data of Examples 2-8 and Comparative Examples 2-8, the magnetic properties of the examples are all superior to those of the comparative examples. This demonstrates that by adding an appropriate amount of copper-rich auxiliary alloy and a small amount of pure copper powder to high-iron-content samarium-cobalt magnetic powder, not only is the copper depletion phenomenon at the grain boundaries of conventional magnets effectively avoided, but a cellular structure can also be constructed at the grain boundaries. It is worth noting that the pure copper powder plays a role in wetting the grain boundaries in the magnet, making the cellular structure at the grain boundaries more uniform and complete. The synergistic effect of the copper-rich auxiliary alloy and pure copper powder significantly improves the coercivity, squareness, and maximum energy product of the high-iron-content samarium-cobalt magnet. This invention provides a high-iron-content samarium-cobalt magnet and its preparation method, which has important guiding significance for the preparation of high-iron-content samarium-cobalt magnets.

[0067] The foregoing has provided a detailed description of a high-iron-content samarium-cobalt magnet and its preparation method, as provided in the embodiments of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this application; furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0068] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0069] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0070] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0071] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A method for preparing a high-iron-content samarium-cobalt magnet, characterized in that, The preparation method specifically includes the following steps: S1) According to the design ratio, high iron content samarium cobalt alloy raw materials and copper-rich auxiliary alloy raw materials are smelted separately to obtain high iron content samarium cobalt alloy ingots and copper-rich auxiliary alloy ingots; The high-iron-content samarium-cobalt magnet comprises: a high-iron-content samarium-cobalt alloy, a copper-rich auxiliary alloy, and copper powder, wherein the mass ratio of the high-iron-content samarium-cobalt alloy to the copper-rich auxiliary alloy is 5:1 to 20:1; and the copper powder accounts for 1 to 5 wt.% of the sum of the mass of the high-iron-content samarium-cobalt alloy and the copper-rich auxiliary alloy. S2) The high-iron-content samarium-cobalt alloy ingot and the copper-rich auxiliary alloy ingot obtained in S1) are subjected to coarse crushing, medium crushing and air jet milling respectively to obtain high-iron-content samarium-cobalt magnetic powder and copper-rich auxiliary alloy powder. S3) The high-iron content samarium cobalt magnetic powder and copper-rich auxiliary alloy powder obtained in S2) are mixed in a mass ratio of 5:1 to 20:1, and copper powder is added to the mixed magnetic powder. Then, the mixture is mixed, magnetic field forming, cold isostatic pressing and sintering are carried out in sequence to obtain a sintered dense magnet. The added copper powder accounts for 1 to 5 wt.% of the total mass of the high-iron content samarium-cobalt alloy and the copper-rich auxiliary alloy; S4) The sintered and dense magnet obtained in S3) is subjected to two-stage solid solution treatment to obtain a single-phase solid solution precursor with a grain size greater than 65 μm. The two-stage solution treatment process specifically involves: first holding the sintered billet at a temperature of 1180~1205℃ for 1~4 hours, then holding it at a temperature of 1150~1190℃ for 4~48 hours, followed by air cooling or water cooling to room temperature; S5) The single-phase solid solution precursor obtained in S4) is subjected to a three-stage aging treatment to obtain a high-iron content samarium-cobalt magnet with a complete and uniform cellular structure and a concentrated distribution of copper elements at the cell wall; The three-stage aging process is as follows: first, the temperature is kept at 600~780℃ for 1~5 hours, then at 780~870℃ for 10~24 hours, then cooled to 400~500℃ at a rate of 0.4~1℃ / min and kept at that temperature for 1~15 hours, and finally cooled to room temperature by air or water. The high-iron content samarium-cobalt alloy has the chemical formula Sm(Co) 1-a-b-c Fe a Cu b Zr c ) z Where 0.16≤a≤0.4, 0.04≤b≤0.1, 0.018≤c≤0.033, 7≤z≤8; the copper-rich auxiliary alloy composition is RE(Co 1-u Cu u )5, where RE is one or more of Pr, Nd, and Sm, and 0.4≤u≤1; The final state magnet of the high-iron content samarium-cobalt magnet obtained by the method has a complete and uniform cellular structure with a cell size of 100-150 nm; the copper-rich 1:5H phase is generated in the grain boundary in the form of cell wall. The coercivity of the high-iron content samarium cobalt magnet is not less than 25 kOe, the squareness is not less than 0.75, and the maximum magnetic energy product is not less than 33 MGOe.

2. The preparation method according to claim 1, characterized in that, The high-iron content samarium cobalt magnetic powder obtained in S2) has a particle size of 3~5 μm, of which powder with a size of 3.5~4.2 μm accounts for more than 90%; the copper-rich auxiliary alloy powder has a particle size of 2~4 μm, of which powder with a size of 2~3 μm accounts for more than 90%.

3. The preparation method according to claim 1, characterized in that, The copper powder in S3) has a particle size of 0.5~3μm, and the density of the magnet after sintering is 8.3~8.45 g / cm³. 3 .

4. The application of a high-iron content samarium cobalt magnet prepared by the preparation method according to any one of claims 1-3 in the fields of high-power permanent magnet motors or rail transportation.

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