Ti element doped high-performance high-temperature samarium cobalt permanent magnet material and preparation method thereof

Abstract

The invention relates to a Ti element doped high-performance high-temperature samarium cobalt permanent magnet material and a preparation method thereof, and belongs to the field of rare earth permanent magnet materials. Elements of Sm, Co, Fe, Cu, Zr and Ti with the purity higher than 99.9% are uniformly mixed and smelted into an original cast ingot, a powder metallurgy preparation technology is adopted, the cast ingot is ground into alloy powder, and the samarium-cobalt permanent magnet material is prepared through orientation compression, isostatic pressing, high-temperature sintering, solid solution and isothermal aging heat treatment processes. According to the invention, by doping the Ti element, the grain size is increased, the grain boundary impurity phase precipitation is inhibited, and the thickness and the content of the flaky phase are properly reduced, so that the number of reverse magnetization nucleation sites is reduced, and the magnetic properties such as the coercive force and the maximum magnetic energy product of the magnet are effectively improved.

Description

Technical Field

[0001] The present invention relates to a Ti-doped high-performance, high-temperature samarium-cobalt permanent magnet material and a preparation method thereof, and more particularly to a method for improving the coercive force and maximum magnetic energy product of the samarium-cobalt permanent magnet material by adding the transition metal element Ti to the samarium-cobalt magnet. The invention belongs to the field of rare earth permanent magnet materials. Background Art

[0002] 2:17 SmCo permanent magnets have high Curie temperature, strong magnetocrystalline anisotropy and excellent temperature stability. They have important application prospects in modern transportation and defense industry. The excellent magnetic properties of 2:17 SmCo permanent magnets are attributed to their unique nanocellular structure, namely 2:17R intracellular phase, 1:5H cell wall phase and Zr-rich lamellar phase. The main components of SmCo permanent magnets are expressed as follows: In the quinary alloy, Fe is enriched in the 2:17R intracellular phase, providing high remanence; Cu is enriched in the 1:5H cell wall phase, and the large Cu concentration gradient is beneficial to improving the pinning strength of the magnetic domain wall, thereby increasing the coercive force.

[0003] Previous studies have shown that Zr plays an important and complex role in SmCo permanent magnet materials. The addition of Zr increases the alloy's solid solubility, facilitating the formation of a single-phase 1:7H solid solution, which is a necessary prerequisite for achieving a complete nanocellular structure and, consequently, high performance through subsequent aging. Furthermore, Zr is primarily concentrated in the lamellar phase, promoting its formation. The lamellar phase provides a diffusion channel for Cu to diffuse into the cell wall phase, facilitating the formation of a large Cu concentration gradient and, consequently, high coercivity. However, recent studies have shown that during demagnetization, remagnetization nuclei preferentially form in the lamellar phase and gradually expand into the intracellular phase. Furthermore, increasing the thickness of the lamellar phase facilitates the remagnetization nucleation process. Furthermore, an increase in the density of the lamellar phase increases the number of remagnetization nucleation sites and facilitates the expansion of reverse magnetic domains, all of which contribute to a decrease in the magnet's coercivity.

[0004] How to give full play to the beneficial effects of Zr on alloy solid solution and the formation of lamellar phase to promote Cu diffusion on the basis of existing quinary alloys, while reducing the adverse effects of Zr-rich lamellar opposite magnetization nucleation on coercivity, is the key to further optimize and improve the comprehensive magnetic properties of magnets, especially coercivity. Summary of the Invention

[0005] The present invention addresses the following technical issues: Addressing the shortcomings of existing technologies, the present invention proposes a Ti-doped high-performance, high-temperature SmCo permanent magnet material and its preparation method. Specifically, by doping with the transition metal element Ti and optimizing the heat treatment process, while increasing the alloy's solid solubility to form a single-phase solid solution, the present invention reduces Zr doping, thereby reducing the thickness and content of the lamellar phase. This reduces the number of nucleation sites for magnetization reversal, resulting in a SmCo permanent magnet material with high coercivity and a high maximum energy product.

[0006] To achieve the above objectives, the present invention provides a Ti-doped high-performance high-temperature samarium-cobalt permanent magnet material. , where u=0.10-0.21, v=0.06-0.10, 0 <x<0.03,0<y<0.03,z=7.0-8.4。

[0007] Preferably, u=0.15-0.20.

[0008] Preferably, v=0.06-0.10.

[0009] Preferably, w=0.02-0.03.

[0010] Preferably, x=0-0.03.

[0011] Preferably, z=7.5-8.4.

[0012] To achieve the above object, the present invention also provides a method for preparing a Ti-doped high-performance, high-temperature samarium-cobalt permanent magnet material, the specific steps of which are as follows:

[0013] Step 1: Ingredient preparation and alloy smelting

[0014] According to the main alloy chemical formula, Sm, Co, Fe, Cu, Zr and Ti with a purity higher than 99.9% are used as raw materials to prepare the components. Vacuum arc is repeatedly melted 3 to 5 times to obtain an alloy ingot with uniform composition.

[0015] Step 2: Crushing, pulverizing and molding

[0016] After the alloy ingot is coarsely crushed, it is ball milled or jet milled to obtain powder with an average area diameter of 3-5 μm. The powder is placed in a magnetic field press for pressing and orientation, and further pressed in an isostatic press to obtain a compact.

[0017] Step 3: Sintering and solution treatment

[0018] The compact is placed in a vacuum heat treatment furnace and sintered at 1200-1230° C. for 0.5-2 hours in an inert atmosphere; then the temperature is lowered to 1190-1210° C. for solution treatment for 2-10 hours, and then quenched to obtain a solid solution magnet.

[0019] Step 4: Aging Process

[0020] The solid solution magnet is heated to 750-850°C in an inert gas environment, kept warm for 10-30 hours, then cooled to 400-500°C at a cooling rate of 0.3-0.7°C / min, kept warm for 5-20 hours, and then quenched to room temperature to finally obtain a 2:17 type samarium cobalt magnet.

[0021] In the above technical solution, in step 1, the composition takes into account the Sm burnout, and the actual amount of Sm added is 3-5% wt.% more than the stoichiometric amount.

[0022] In the above technical solution, in step 2, the magnetic field strength of the magnetic field press is 1-2T, and the pressure of the isostatic press is 200-300MPa.

[0023] In the above technical solution, in step three, the inert atmosphere is argon or nitrogen.

[0024] In the above technical solution, the average grain size of the permanent magnetic material is 35-45 μm.

[0025] In the above technical solution, the thickness of the lamellar phase in the nanocellular structure of the permanent magnetic material is ≤3 nm.

[0026] The present invention provides a method for preparing a Ti-doped high-performance, high-temperature samarium-cobalt permanent magnet material. Compared with the prior art, the present invention has the following advantages:

[0027] The present invention reduces the doping amount of Zr by doping with the transition element Ti, while improving the solid solubility of the alloy. Under the same heat treatment conditions, a larger grain size is obtained, the content of the grain boundary phase is reduced, and thus the squareness of the magnet is improved.

[0028] The present invention reduces the Zr content by doping with the transition element Ti, thereby obtaining a relatively low flaky phase density and reducing the thickness of the flaky phase, thereby reducing the reverse magnetization nucleation sites and improving the coercive force of the magnet;

[0029] Compared with pure Zr-doped magnets, a larger cell size and a higher maximum magnetic energy product are achieved. Magnets doped with a small amount of Ti increase the magnetic energy product by ~12% compared to the original undoped magnets.

[0030] By adding the transition metal element Ti to the samarium-cobalt quinary alloy and adjusting the magnetic properties of the samarium-cobalt magnet, a magnet that meets the requirements of high performance or high temperature use is prepared. The preparation process is simple, highly repeatable, effective, and has low production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention.

[0032] Figure 1 is the room temperature demagnetization curve of the magnet prepared in Example 1 of the present invention;

[0033] Figure 2 The metallographic structure of the magnet after corrosion prepared in Example 1 of the present invention;

[0034] Figure 3 The transmission electron microscope analysis results of the magnet prepared in Example 1 of the present invention are shown in Figure (a). Magnet, Figure (b) is Magnet, Figure (c) is magnet. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. However, the following embodiments are intended only to explain the present invention, and the scope of protection of the present invention should include the entire contents of the claims. Moreover, through the description of the following embodiments, those skilled in the art can fully implement the entire contents of the claims of the present invention.

[0036] The present invention relates to a method for preparing a Ti-doped high-performance, high-temperature samarium-cobalt permanent magnetic material, comprising the following preparation steps:

[0037] Step 1: Ingredient preparation and alloy smelting

[0038] Sm, Co, Fe, Cu, Zr and Ti with a purity higher than 99.9% are used as raw materials for the composition, and vacuum arc is repeatedly melted 3 to 5 times to obtain an alloy ingot with uniform composition.

[0039] Step 2: Crushing, pulverizing and molding

[0040] After the alloy ingot is coarsely crushed, it is ball milled or jet milled to obtain a powder with an average area diameter of 3-5 μm. The powder is placed in a magnetic field press to obtain a highly oriented green body, and the pressure is maintained in an isostatic press for 1 hour, and further pressed to obtain a green body.

[0041] Step 3: Sintering and solution treatment

[0042] The compact is placed in a vacuum heat treatment furnace and sintered at 1200-1230° C. for 0.5-2 hours in an inert atmosphere; then the temperature is lowered to 1190-1210° C. for solution treatment for 2-10 hours, and then quenched to obtain a solid solution magnet.

[0043] Step 4: Aging Process

[0044] The solid solution magnet is heated to 750-850°C in an inert gas environment, kept warm for 10-30 hours, then cooled to 400-500°C at a cooling rate of 0.3-0.7°C / min, kept warm for 5-20 hours, and then quenched to room temperature to finally obtain a 2:17 type samarium cobalt magnet.

[0045] In step 1, the composition takes into account the Sm burnout, and the actual amount of Sm element added is 3-5% wt.% more than the stoichiometric amount.

[0046] In step 2, the magnetic field strength of the magnetic field press is 1-2T, and the pressure of the isostatic press is 200-300MPa.

[0047] In step 3, the inert atmosphere is argon or nitrogen.

[0048] The present invention adds the transition metal element Ti to the samarium-cobalt quinary alloy to adjust the microstructure and magnetic properties of the samarium-cobalt magnet. The following are specific embodiments of the present invention:

[0049] Example 1:

[0050] The nominal composition is selected as A small amount of Ti element is added during the alloy smelting process.

[0051] The specific preparation process is as follows:

[0052] Step 1: Ingredient preparation and alloy smelting

[0053] According to the main alloy chemical formula, Sm, Co, Fe, Cu, Zr, and Ti with a purity higher than 99.9% are used as raw materials. Considering the burnout of Sm, 3%-5% more Sm is added. The crucible is placed in a water-cooled copper crucible in a vacuum arc furnace. The Sm element, which is easy to burn out, is placed at the bottom and vacuumed to , and washed three times, and filled with high-purity Ar gas. Each alloy ingot was melted four times on both sides to finally obtain an alloy ingot.

[0054] Step 2: Crushing, milling and molding

[0055] The alloy ingot is coarsely crushed in an Ar atmosphere and filtered through an 80-mesh sieve to obtain coarse powder, which is then ball-milled or jet-milled to obtain a powder with an average area diameter of 3-5 μm. The powder is placed in a magnetic field press for press orientation and further pressed in an isostatic press to obtain a compact.

[0056] Step 3: Sintering and solution treatment

[0057] The compact was placed in a vacuum heat treatment furnace and sintered at 1210°C for 1 hour in a high-purity Ar gas atmosphere; then the temperature was lowered to 1205°C for solution treatment for 4 hours and then quenched to obtain a solid solution magnet.

[0058] Step 4: Aging

[0059] The solid solution magnet was placed in an Ar gas atmosphere, heated to 815°C, kept warm for 24 hours, then cooled to 400°C at a rate of 0.5°C per minute, kept warm for 10 hours, and then quenched to room temperature to obtain the final magnet.

[0060] Comparative Example 1:

[0061] In this comparative example, the nominal components are and The preparation process of the magnet is the same as that of Example 1.

[0062] use Permanent magnet measuring instrument measurement 、 and Magnetic properties of magnets. Magnetic properties data are shown in Table 1.

[0063] For the convenience of explanation, the following 、 and Magnets are referred to as 、 and magnet.

[0064] Table 1 Comparison of room temperature magnetic properties of Ti-doped magnets

[0065]

[0066] Comparison of room temperature magnetic properties of the magnets in Example 1 and Comparative Example 1 is shown in Table 1. The remanence of the magnet is high at ~10.32 kGs and the coercivity is high at ~33 kOe, but the squareness SF is very poor at ~83.6, resulting in a low magnetic energy product of ~21.75 MGOe. The squareness of the magnet is significantly improved, and the SF is increased to 89.7, but the remanence ~9.862 kGs and the coercive force ~20.73 kOe are significantly reduced, resulting in an insignificant improvement in the magnetic energy product of the final magnet ~22.75 MGOe. The squareness SF of the magnet is significantly improved to ~96.3, the coercivity of the magnet does not decrease significantly to ~34.21kOe, and the addition of the non-magnetic element Ti causes the remanence of the magnet to decrease by ~10.05kGs. Finally, the magnetic energy product of the magnet is significantly improved to ~24.35 MGOe. The room temperature demagnetization curve of the above magnet is shown in Figure 1 .

[0067] Figure 2 China is 、 and The metallographic structures of the three magnets, The grain size of the magnet is extremely small, only about 10μm. The small grains lead to the presence of more grain boundary precipitation phases in the magnet, which significantly deteriorates the squareness of the magnet. and magnets doped with a small amount of Ti The grain size increases significantly, reaching 32μm and 45μm respectively. The increase in grain size reduces the precipitation phase at the grain boundary, and ultimately the squareness of the magnet is significantly improved. Due to the addition of a large amount of Zr element in the magnet, a large amount of white precipitated phases are precipitated in the matrix. These white precipitated phases are mainly FeCoZr precipitated phases. These soft magnetic FeCoZr precipitated phases will deteriorate the coercive force and squareness of the magnet.

[0068] Figure 3 China is 、 and The transmission bright field images of the three magnets correspond to (a1) / (b1) / (c1), (a2) / (b2) / (c2) and (a3) / (b3) / (c3) in the figure, respectively. The Cu concentration distribution across the cell wall is shown in (a4) / (b4) / (c4). All three magnets have a typical nanocellular structure, mainly composed of three phases: intracellular phase, cell wall phase and lamellar phase. Zr 0.02 The cellular structure is incomplete, and the average cell size is ∼81 nm. and The cell structures of the three magnets are complete, with average cell sizes of ~68nm and ~53nm respectively. The cell wall thickness and lamellar phase density of the three magnets are similar, however The coarser lamellar phases can be seen in the MgO, which will lead to a decrease in the coercive force of the magnet.

[0069] Example 2:

[0070] The nominal composition is selected as A small amount of Ti element is added during the alloy smelting process.

[0071] The specific preparation process is as follows:

[0072] Step 1: Ingredient preparation and alloy smelting

[0073] According to the main alloy chemical formula, Sm, Co, Fe, Cu, Zr, and Ti with a purity higher than 99.9% are used as raw materials. Considering the burnout of Sm, 3%-5% more Sm is added. The crucible is placed in a water-cooled copper crucible in a vacuum arc furnace. The Sm element, which is easy to burn out, is placed at the bottom and vacuumed to , and washed three times, and filled with high-purity Ar gas. Each alloy ingot was melted four times on both sides to finally obtain an alloy ingot.

[0074] Step 2: Crushing, milling and molding

[0075] The alloy ingot is coarsely crushed in an Ar atmosphere and filtered through an 80-mesh sieve to obtain coarse powder, which is then ball-milled or jet-milled to obtain a powder with an average area diameter of 3-5 μm. The powder is placed in a magnetic field press for press orientation and further pressed in an isostatic press to obtain a compact.

[0076] Step 3: Sintering and solution treatment

[0077] The compact was placed in a vacuum heat treatment furnace and sintered at 1210°C for 1 hour in a high-purity Ar gas atmosphere; then the temperature was lowered to 1205°C for solution treatment for 4 hours and then quenched to obtain a solid solution magnet.

[0078] Step 4: Aging

[0079] The solid solution magnet was placed in an Ar gas atmosphere, heated to 815°C, kept warm for 24 hours, then cooled to 400°C at a rate of 0.5°C per minute, kept warm for 10 hours, and then quenched to room temperature to obtain the final magnet.

[0080] Comparative Example 2:

[0081] In this comparative example, the nominal composition is selected as The rest of the preparation process is the same as that of Example 2.

[0082] use Permanent magnet measuring instrument measurement and Magnetic properties of magnets. Magnetic properties data are shown in Table 2.

[0083] Table 2 Effect of Ti doping on room temperature magnetic properties of high z value magnets

[0084]

[0085] Comparing the room temperature magnetic properties of the magnets in Example 2 and Comparative Example 2, see Table 2, it is found that The remanence of the magnet is high, ~10.09 kGs, which is mainly due to the addition of Ti element to replace Zr, avoiding the precipitation of Zr-rich phase caused by excessive Zr element, which is also beneficial to improving the squareness SF of the magnet while still maintaining the high coercive force of the magnet. Finally, the magnetic energy product of the magnet is also improved to ~24.35 MGOe.

[0086] These results demonstrate that adding the transition metal element Ti to the 2:17 SmCo quinary alloy can optimize the magnet's microstructure and improve its magnetic properties. Ti doping increases grain size and inhibits the precipitation of impurity phases at grain boundaries, while also appropriately reducing the thickness and content of the lamellar phase, thereby reducing the number of sites for magnetization reversal nucleation. This effectively enhances the magnet's coercivity and maximum energy product, among other magnetic properties.

[0087] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A Ti-doped high-performance, high-temperature samarium-cobalt permanent magnet material, characterized in that: The expression of the samarium cobalt permanent magnet is: , where u=0.10-0.21, v=0.06-0.10, 0 <x<0.03,0<y<0.03,z=7.0-8.4。 2. The Ti element doped high performance high temperature samarium cobalt permanent magnet material according to claim 1, characterized in that: The u=0.15-0.20, The v=0.06-0.10, x=0.02-0.03, The y=0-0.03, Said z=7.5-8.

4.

3. The Ti-doped high-performance, high-temperature samarium-cobalt permanent magnet material according to claim 1, characterized in that: The samarium cobalt permanent magnet material has a coercive force of ~34 kOe and a maximum magnetic energy product of ~25 MGOe at room temperature; and a coercive force of ~7 kOe and a maximum magnetic energy product of ~13.6 MGOe at 500°C.

4. A method for preparing a Ti-doped high-performance, high-temperature samarium-cobalt permanent magnet material according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: Ingredient preparation and alloy smelting Sm, Co, Fe, Cu, Zr and Ti with a purity higher than 99.9% are used as raw materials for the preparation of ingredients. Vacuum arc is used for repeated melting 3 to 5 times to obtain an alloy ingot with uniform composition. Step 2: Crushing, pulverizing and molding After the alloy ingot is coarsely crushed, it is ball-milled or jet-milled to obtain a powder with an average area diameter of 3-5 μm. The powder is placed in a magnetic field press to obtain a highly oriented green body, and then kept under pressure in an isostatic press for 1 hour and further pressed to obtain a green body. Step 3: Sintering and solution treatment The compact is placed in a vacuum heat treatment furnace and sintered at 1200-1230°C for 0.5-2 hours under an inert atmosphere; then cooled to 1190-1210°C for solution treatment for 2-10 hours, and then quenched to obtain a solid solution magnet; Step 4: Aging Process The solid solution magnet is heated to 750-850°C in an inert gas environment, kept warm for 10-30 hours, then cooled to 400-500°C at a cooling rate of 0.3-0.7°C / min, kept warm for 5-20 hours, and then quenched to room temperature to finally obtain a 2:17 type samarium cobalt magnet.

5. The method for preparing the Ti element doped high performance and high temperature samarium cobalt permanent magnet material according to claim 4, characterized in that: In step 1, the actual amount of Sm element added is 3-5% wt.% more than the stoichiometric amount.

6. The method for preparing the Ti element doped high performance and high temperature samarium cobalt permanent magnet material according to claim 4, characterized in that: In step 2, the magnetic field strength of the magnetic field press is 1-2T, and the pressure of the isostatic press is 200-300MPa.

7. The method for preparing the Ti element doped high performance and high temperature samarium cobalt permanent magnet material according to claim 4, characterized in that: In step 3, the inert atmosphere is argon or nitrogen.

8. The method for preparing the Ti element doped high performance and high temperature samarium cobalt permanent magnet material according to claim 4, characterized in that: The average grain size of the permanent magnet material is 35-45 μm.

9. The method for preparing the Ti element doped high performance and high temperature samarium cobalt permanent magnet material according to claim 4, characterized in that: The thickness of the lamellar phase in the nanocellular structure of the permanent magnetic material is ≤3 nm.

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