Y-based neodymium-iron-boron magnet, and preparation method and application thereof

Abstract

The application discloses a yttrium-based neodymium-iron-boron magnet and a preparation method and application thereof. The yttrium-based neodymium-iron-boron magnet comprises the following steps: providing first main phase alloy powder and second main phase alloy powder, the content of yttrium in the first main phase alloy powder is greater than the content of yttrium in the second main phase alloy powder, mixing the two kinds of powder, and then sequentially performing orientation compression, sintering and tempering heat treatment to obtain the yttrium-based neodymium-iron-boron magnet. According to the application, different yttrium-containing main phase components and alloy powder particle sizes are designed to prepare the yttrium-based sintered neodymium-iron-boron magnet which has the comprehensive performance of high coercivity and high remanence, and the method is easy to control and suitable for batch production.

Description

Technical Field

[0001] This invention belongs to the field of rare earth permanent magnet materials technology, and particularly relates to a high-performance yttrium-based neodymium iron boron magnet, its preparation method and application. Background Technology

[0002] Neodymium iron boron (NdFeB) magnets, due to their high energy density and excellent demagnetization resistance, have become indispensable key components in wind power generation, new energy vehicles, and rail transportation. In recent years, with the technological upgrades in these fields, the demand for NdFeB magnets has increased significantly, leading to the large-scale consumption of expensive and scarce rare earth elements such as Pr, Nd, Dy, and Tb, while the high-abundance rare earth element Y has accumulated excessively. Developing yttrium-based NdFeB magnets rich in high-abundance Y can not only reduce the manufacturing cost of NdFeB magnets but also promote the balanced utilization of rare earth resources. Therefore, developing high-performance yttrium-based NdFeB magnets is of great significance.

[0003] The main reason why yttrium-based NdFeB magnets have poorer magnetic properties compared to NdFeB magnets without high-abundance elements is Y2Fe. 14 The saturation magnetization of B (M s =1.41 T, H A =26 kOe) and the magnetocrystalline anisotropy field is lower than that of Nd2Fe 14 B(M) s =1.60T, H A =73 kOe), therefore, the magnetic properties of NdFeB magnets decrease significantly when the substitution amount of Y increases. Studies have shown that Y has unique metallurgical behavior compared to other rare earth elements. In the main phase grains, Y atoms accumulate at the grain core, while the Y concentration in the grain shell is lower than that in the core. This "core-shell" structure, similar to that in diffused magnets, can enhance the local anisotropy field of the grain surface, which is beneficial to the coercivity of the magnet. The lower the Y concentration in the "core-shell" structure, the higher the local anisotropy field, and the more beneficial it is to the coercivity of the magnet. Currently, by adding low-melting-point alloys containing rare earth elements such as Pr and Dy to yttrium-based magnets using a dual-alloy method, the Y element in the main phase grain surface is replaced by the added rare earth elements due to the concentration gradient, which enhances the local anisotropy field of the grain shell. At the same time, the added rare earth elements widen the grain boundaries and enhance the magnetic isolation between the main phase grains, both of which jointly improve the coercivity of the magnet. However, this method significantly reduces the proportion of main phase grains in the magnet, causing magnetic dilution and deteriorating the remanence of the magnet. Therefore, improving the coercivity of yttrium-based magnets without damaging remanence presents a challenge. Summary of the Invention

[0004] The main objective of this invention is to provide a high-performance yttrium-based neodymium iron boron magnet, its preparation method, and its application, thereby overcoming the shortcomings of the prior art.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0006] The first aspect of this invention provides a method for preparing a yttrium-based neodymium iron boron magnet, comprising:

[0007] A first main phase alloy powder and a second main phase alloy powder are provided, wherein the chemical formula of the first main phase alloy powder is Re. x1 Y m1 B y1 M z1 Fe 100-x1-y1-z1 The chemical formula of the second main phase alloy powder is Re. x2 Y m2 B y2 M z2 Fe 100-x2-y2-z2 Wherein, Re includes at least one of Tb, Dy, Gd, Pr, Nd, La, Ce and Ho, M includes at least one of Cu, Zr, Co, Ga, Si, Sn, Ge, Ti, Zn and Al, 5≤x1≤34, 0.8<y1≤2.0, 0≤z1≤3, 0<m1≤20, 15≤x2≤35, 0.5<y2≤0.99, 0≤z2≤3, 0≤m2≤15, and m1>m2;

[0008] The first main phase alloy powder and the second main phase alloy powder are mixed, and then oriented pressing, sintering and tempering heat treatment are performed in sequence to obtain yttrium-based neodymium iron boron magnets.

[0009] A second aspect of the present invention provides a yttrium-based neodymium iron boron magnet prepared by the above preparation method.

[0010] A third aspect of the present invention provides the application of the yttrium-based neodymium iron boron magnet in fields such as wind power generation, new energy vehicles, or rail transportation.

[0011] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0012] This invention enables the preparation of yttrium-based sintered NdFeB magnets with both high coercivity and high remanence by designing different combinations of yttrium-containing main phase components and alloy powder particle sizes. The process is easy to control and suitable for mass production. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram illustrating the preparation mechanism and microstructure of a high-performance yttrium-based neodymium iron boron magnet in a typical embodiment of the present invention. Detailed Implementation

[0015] In view of the shortcomings of the prior art, the inventors of this invention have proposed the technical solution of the present invention through long-term research and extensive practice. The main solution is to provide two main phase alloy powders with different yttrium contents, mix the two powders, and then perform orientation pressing, sintering and tempering heat treatment in sequence to obtain high-performance yttrium-based neodymium iron boron magnets.

[0016] The following will further explain the technical solution, its implementation process, and its principles. However, it should be understood that within the scope of this invention, the above-mentioned technical features of this invention and the technical features specifically described below (in embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here.

[0017] As one aspect of the technical solution of this invention, the method for preparing a yttrium-based neodymium iron boron magnet includes:

[0018] A first main phase alloy powder is provided, the chemical formula of which is Re. x1 Y m1 B y1 M z1 Fe 100-x1-y1-z1 Wherein, Re includes at least one of Tb, Dy, Gd, Pr, Nd, La, Ce and Ho, M includes at least one of Cu, Zr, Co, Ga, Si, Sn, Ge, Ti, Zn and Al, 5≤x1≤34, 0.8<y1≤2.0, 0≤z1≤3, 0<m1≤20;

[0019] A second main phase alloy powder is provided, the chemical formula of which is Re. x2 Y m2 B y2 M z2 Fe 100-x2-y2-z2Wherein, Re includes at least one of Tb, Dy, Gd, Pr, Nd, La, Ce and Ho, M includes at least one of Cu, Zr, Co, Ga, Si, Sn, Ge, Ti, Zn and Al, 15≤x2≤35, 0.5<y2≤0.99, 0≤z2≤3, 0≤m2≤15, and the content of yttrium atoms m1 in the first main phase alloy powder is greater than the content of yttrium atoms m2 in the second main phase alloy powder;

[0020] The first main phase alloy powder and the second main phase alloy powder are mixed, and then oriented pressing, sintering and tempering heat treatment are performed in sequence to obtain yttrium-based neodymium iron boron magnets.

[0021] In some implementation schemes, in Re x1 Y m1 B y1 M z1 Fe 100-x1-y1-z1 In the formula, x1 is preferably 23~27, more preferably 24~26; y1 is preferably 0.85~1.6, more preferably 0.9~1.4; z1 is preferably 1.5~2.5, more preferably 1.5~2; m1 is preferably 5~15, more preferably 7~10.

[0022] In some implementation schemes, in Re x2 Y m2 B y2 M z2 Fe 100-x2-y2-z2 In the formula, x2 is preferably 26~29, more preferably 26~28; y2 is preferably 0.9~0.98, more preferably 0.92~0.96; z2 is preferably 1.5~2.5, more preferably 1.5~2; m2 is preferably 0~10, more preferably 0~3.

[0023] In some implementations, the mass ratio of the first main phase alloy powder to the second main phase alloy powder is 1:(3~10).

[0024] In some embodiments, the particle size of the second main phase alloy powder is larger than that of the first main phase alloy powder. This allows the smaller-sized first main phase alloy powder to distribute more easily around the larger-sized second main phase alloy powder. Furthermore, since the yttrium content in the first main phase alloy powder is higher than that in the second main phase alloy powder, this distribution is more conducive to the diffusion of yttrium from the first main phase alloy powder into the grains of the second main phase alloy powder. In addition, the coercivity of a magnet is related to grain size; the finer the grains, the higher the coercivity of the magnet. The presence of fine grains in a magnet is beneficial to its coercivity.

[0025] In some preferred embodiments, the particle size of the first main phase alloy powder is 2µm to 4µm.

[0026] In some preferred embodiments, the particle size of the second main phase alloy powder is 3µm to 5µm.

[0027] In some embodiments, the main phase grains of both the first and second main phase alloy powders have a core-shell structure, and the percentage of yttrium atoms in the core is higher than that in the shell.

[0028] The schematic diagram of the mechanism and microstructure of the present invention for preparing high-performance yttrium-based neodymium iron boron magnets are shown below. Figure 1 As shown, the magnet contains two main phase grains: the main phase grains of the first main phase alloy powder (i.e., "main phase I grains" in the figure) and the main phase grains of the second main phase alloy powder (i.e., "main phase II grains" in the figure). Yttrium (Y) has the metallurgical property of accumulating towards the grain core. In both main phase grains, the Y element concentration at the core is higher than that in the grain shell, forming a unique "core-shell" structure. The size of the main phase I grains is smaller than that of the main phase II grains, and the main phase I grains are uniformly distributed around the main phase II grains. Furthermore, the Y element content of the main phase I grains is higher than that of the main phase II grains. Due to the concentration gradient, the Y element in the main phase I grains tends to migrate towards the main phase II grains. Ultimately, the Y element concentration on the surface of the main phase I grains decreases, while still retaining the original fine grain state and "core-shell" structure. The local anisotropic field on the surface of the main phase grains with a "core-shell" structure is higher than that at the core, which can effectively suppress the flipping and movement of antimagnetic domains during demagnetization. This not only improves the coercivity of the magnet, but also does not cause the loss of remanence while improving the coercivity of the magnet, thus producing a high-performance yttrium-based neodymium iron boron magnet.

[0029] In some embodiments, the preparation method specifically includes:

[0030] First main phase alloy castings (high yttrium content) and second main phase alloy castings (low yttrium content) were prepared by melting and smelting according to the element ratios of the first main phase alloy powder and the second main phase alloy powder, respectively.

[0031] The first main phase alloy casting and the second main phase alloy casting were subjected to hydrogen crushing to obtain intermediates, which were then subjected to air jet milling to obtain the first main phase alloy powder and the second main phase alloy powder.

[0032] In some more preferred embodiments, the hydrogen pressure used in the hydrogen crushing process is 0.1 MPa to 0.4 MPa, the hydrogen absorption time is 2 h to 5 h, the dehydrogenation temperature is 320 °C to 500 °C, and the dehydrogenation time is 4 h to 10 h.

[0033] In some preferred embodiments, the hydrogen content in the intermediate powder obtained after hydrogen crushing is less than 1500 ppm.

[0034] In some more preferred embodiments, the average particle size of the intermediate powder obtained after hydrogen decomposition is 100µm to 250µm.

[0035] In some implementations, the magnetic field strength used in the orientation molding is 1.5T to 2.0T.

[0036] In some embodiments, the sintering is carried out in a vacuum environment at a temperature of 900°C to 1150°C for a time of 1 hour to 6 hours.

[0037] In some embodiments, the tempering heat treatment includes a first tempering heat treatment, a second tempering heat treatment, and a third tempering heat treatment performed sequentially, or includes a first tempering heat treatment and a third tempering heat treatment performed sequentially; wherein the temperature of the first tempering heat treatment is 850℃~950℃, the temperature of the second tempering heat treatment is 650℃~800℃, the temperature of the third tempering heat treatment is 450℃~600℃, and the time of the first tempering heat treatment, the second tempering heat treatment, and the third tempering heat treatment is 1h~4h.

[0038] As another aspect of the technical solution of the present invention, it also relates to yttrium-based neodymium iron boron magnets prepared by the above-described preparation method.

[0039] As another aspect of the technical solution of the present invention, it also relates to the application of the yttrium-based neodymium iron boron magnet in fields such as wind power generation, new energy vehicles, rail transit, humanoid robots, or low-altitude economy.

[0040] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. It should be noted that the following embodiments are intended to facilitate understanding of this invention and are not intended to limit it in any way. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the manufacturer.

[0041] Example 1

[0042] Rapidly solidified alloy castings of main phase I and main phase II were prepared by melting according to the element ratios. The vacuum degree during the preparation of both types of rapidly solidified alloy castings was 3×10⁻⁶. -2 Pa, rotation speed 2.0 m / s, casting temperature 1350℃, chemical formula of the main phase I rapid solidification alloy casting Nd mass percentage 15 Y 15 B 0.96 Al0.1 Cu 0.2 Ga 0.1 Zr 0.1 Fe 68.54 The chemical formula of the rapidly solidified alloy casting of main phase II, by mass percentage, is Nd. 27 Y3B 0.96 Al 0.1 Cu 0.2 Ga 0.1 Zr 0.1 Fe 68.54 Rapidly solidified alloy castings of main phase I and main phase II were subjected to hydrogen absorption at room temperature and a hydrogen pressure of 0.2 MPa for 3 hours, and then vacuum dehydrogenated at 450 °C for 9 hours to obtain hydrogen-crushed intermediate powders (hydrogen content less than 1500 ppm, average particle size approximately 200 µm). The hydrogen-crushed intermediate powders were then further crushed using an air jet mill to obtain main phase I alloy powder with a particle size of 2.3 µm and main phase II alloy powder with a particle size of 3.5 µm. The air jet mill pressure for main phase I alloy powder was 0.52 MPa, and the sorting wheel speed was 4800 rpm; the air jet mill pressure for main phase II alloy powder was 0.52 MPa, and the sorting wheel speed was 4000 rpm.

[0043] The main phase I alloy powder and main phase II alloy powder prepared above were mixed in a mass ratio of 1:4. The resulting mixed powder was then oriented and pressed under a 1.8T magnetic field to obtain a magnet. Subsequently, under atmospheric isolation conditions, the magnet was sintered in a vacuum sintering furnace at a temperature of 1090℃ for 4 hours. Finally, it was heat-treated sequentially at 900℃ and 500℃ for 2 hours each to obtain a yttrium-based neodymium iron boron magnet (Nd). 24.6 Y 5.4 B 0.96 Al 0.1 Cu 0.2 Ga 0.1 Zr 0.1 Fe 68.54 .

[0044] Comparative Example 1

[0045] The difference between this comparative example and Example 1 is that: according to Nd 24.6 Y 5.4 B 0.96 Al 0.1 Cu 0.2 Ga 0.1 Zr 0.1 Fe 68.54 Iron-neodymium-boron permanent magnets are prepared by directly smelting the elements according to their proportions.

[0046] The remanence, coercivity, and magnetic energy product of the magnets prepared in Example 1 and Comparative Example 1 were measured using a BH instrument (model NIM-6500C) provided by the National Institute of Metrology, China. The results are shown in Table 1.

[0047] Table 1. Performance of magnets prepared in Example 1 and Comparative Example 1

[0048]

[0049] Example 2

[0050] Rapidly solidified alloy castings of main phase I and main phase II were prepared by melting according to the element ratios. The vacuum degree during the preparation of both types of rapidly solidified alloy castings was 3×10⁻⁶. -2 Pa, rotation speed 2.0 m / s, casting temperature 1380℃, chemical formula mass percentage of main phase I rapid solidification alloy casting Pr 10 Nd 9.5 Y 10 B 0.98 Al 0.1 Cu 0.2 Ga 0.2 Ti 0.2 Co1Fe 67.82 The chemical formula (mass percentage) of the rapid-solidifying alloy casting of main phase II is Pr4Nd. 22 Gd3B 0.98 Al 0.1 Cu 0.2 Ga 0.2 Ti 0.2 Co1Fe 68.32 Rapidly solidified alloy castings of main phase I and main phase II were subjected to hydrogen absorption at room temperature and a hydrogen pressure of 0.2 MPa for 3 hours, and then vacuum dehydrogenated at 450 °C for 10 hours to obtain hydrogen-crushed intermediate powders (hydrogen content less than 1500 ppm, average particle size approximately 200 µm). The hydrogen-crushed intermediate powders were then further crushed using an air jet mill to obtain main phase I alloy powder with a particle size of 2.1 µm and main phase II alloy powder with a particle size of 3 µm. The air jet mill pressure for main phase I alloy powder was 0.52 MPa, and the sorting wheel speed was 5000 rpm; the air jet mill pressure for main phase II alloy powder was 0.52 MPa, and the sorting wheel speed was 4300 rpm.

[0051] The main phase I alloy powder and main phase II alloy powder prepared above were mixed in a mass ratio of 1:3. The resulting mixed powder was then oriented and pressed under a 1.8T magnetic field to obtain a magnet. Subsequently, under atmospheric isolation conditions, the magnet was sintered in a vacuum sintering furnace at a temperature of 1090℃ for 4 hours. Finally, it was heat-treated sequentially at 900℃, 700℃, and 500℃ for 2 hours each to obtain a yttrium-based neodymium iron boron magnet, Pr. 5.5 Nd 18.875 Y 2.5 Gd 2.25 B 0.98 Al 0.1 Cu 0.2 Ga 0.2 Ti 0.2 Co1Fe 68.195 .

[0052] Comparative Example 2

[0053] The difference between this comparative example and Example 2 is that: according to Pr 5.5 Nd 18.875 Y 2.5 Gd 2.25 B 0.98 Al 0.1 Cu 0.2 Ga 0.2 Ti 0.2 Co1Fe 68.195 Iron-neodymium-boron permanent magnets are prepared by directly smelting the elements according to their proportions.

[0054] The remanence, coercivity, and magnetic energy product of the magnets prepared in Example 2 and Comparative Example 2 were measured using a BH instrument (model NIM-6500C) provided by the National Institute of Metrology, China. The results are shown in Table 2.

[0055] Table 2. Magnet properties prepared in Example 2 and Comparative Example 2

[0056]

[0057] Example 3

[0058] Rapidly solidified alloy castings of main phase I and main phase II were prepared by melting according to the element ratios. The vacuum degree during the preparation of both types of rapidly solidified alloy castings was 3×10⁻⁶. -2 Pa, rotation speed 2.0 m / s, casting temperature 1380℃, chemical formula of the main phase I rapid solidification alloy casting Nd mass percentage 11 Y 18 B 1.0 Al 0.1 Cu 0.1 Ga0.2 Ti 0.15 Co 0.5 Fe 68.95 The chemical formula of the rapid-solidification alloy casting of main phase II, by mass percentage, is Pr. 28 Dy2B 0.8 Al 0.1 Ga 0.2 Zr 0.1 Co 1.2 Fe 67.6 Rapidly solidified alloy castings of main phase I and main phase II were subjected to hydrogen absorption at room temperature and a hydrogen pressure of 0.2 MPa for 3 hours, and then vacuum dehydrogenated at 450 °C for 10 hours to obtain hydrogen-crushed intermediate powders (hydrogen content less than 1500 ppm, average particle size approximately 200 µm). The hydrogen-crushed intermediate powders were then further crushed using an air jet mill to obtain main phase I alloy powder with a particle size of 2.1 µm and main phase II alloy powder with a particle size of 3.2 µm. The air jet mill pressure for main phase I alloy powder was 0.5 MPa, and the sorting wheel speed was 5500 rpm; the air jet mill pressure for main phase II alloy powder was 0.5 MPa, and the sorting wheel speed was 4000 rpm.

[0059] The main phase I alloy powder and main phase II alloy powder prepared above were mixed in a mass ratio of 1:3. The resulting mixed powder was then oriented and pressed under a 1.8T magnetic field to obtain a magnet. Subsequently, under atmospheric isolation conditions, the magnet was sintered in a vacuum sintering furnace at 1100℃ for 4 hours. Finally, it was heat-treated sequentially at 870℃ and 500℃ for 2 hours each to obtain a yttrium-based neodymium iron boron magnet, Pr. 21 Nd 2.75 Y 4.5 Dy 1.5 B 0.85 Al 0.1 Cu 0.025 Ga 0.2 Ti 0.0375 Zr 0.075 Co 1.025 Fe 67.9375 .

[0060] Comparative Example 3

[0061] The difference between this comparative example and Example 3 is that: according to Pr 21 Nd 2.75 Y 4.5 Dy 1.5 B 0.85 Al 0.1 Cu 0.025 Ga 0.2 Ti0.0375 Zr 0.075 Co 1.025 Fe 67.9375 Iron-neodymium-boron permanent magnets were prepared by direct smelting of the elements in the specified proportions, with other preparation conditions remaining the same.

[0062] The remanence, coercivity, and magnetic energy product of the magnets prepared in Example 3 and Comparative Example 3 were measured using a BH instrument (model NIM-6500C) provided by the National Institute of Metrology, China. The results are shown in Table 3.

[0063] Table 3. Properties of magnets prepared in Example 3 and Comparative Example 3

[0064]

[0065] Example 4

[0066] Rapidly solidified alloy castings of main phase I and main phase II were prepared by melting according to the element ratios. The vacuum degree during the preparation of both types of rapidly solidified alloy castings was 3×10⁻⁶. -2 Pa, rotation speed 2.0 m / s, casting temperature 1360℃, chemical formula of the main phase I rapid solidification alloy casting Nd mass percentage 16 Y 14 B 0.96 Al 0.1 Cu 0.2 Ga 0.1 Zr 0.1 Fe 68.54 The chemical formula of the rapidly solidified alloy casting of main phase II, by mass percentage, is Nd. 28 Y2B 0.96 Al 0.1 Cu 0.2 Ga 0.1 Zr 0.1 Fe 68.54 Rapidly solidified alloy castings of main phase I and main phase II were subjected to hydrogen absorption at room temperature and a hydrogen pressure of 0.2 MPa for 3 hours, and then vacuum dehydrogenated at 450 °C for 9 hours to obtain intermediate powders after hydrogen breakdown (hydrogen content less than 1500 ppm, average particle size of about 200 µm). Subsequently, the intermediate powders after hydrogen breakdown were further crushed by air jet milling to obtain main phase I alloy powder with a particle size of 2.3 µm and main phase II alloy powder with a particle size of 3.5 µm, respectively.

[0067] The main phase I alloy powder and main phase II alloy powder prepared above were mixed in a mass ratio of 1:10. The resulting mixed powder was then oriented and pressed under a 1.8T magnetic field to obtain a magnet. Subsequently, under atmospheric isolation conditions, the magnet was sintered in a vacuum sintering furnace at a temperature of 1090℃ for 4 hours. Finally, it was heat-treated sequentially at 950℃ and 480℃ for 2 hours each to obtain a yttrium-based neodymium iron boron magnet (Nd). 26.92 Y 3.08 B 0.96 Al 0.1 Cu 0.2 Ga 0.1 Zr 0.1 Fe 68.54 .

[0068] Comparative Example 4

[0069] The difference between this comparative example and Example 4 is that: according to Nd 26.92 Y 3.08 B 0.96 Al 0.1 Cu 0.2 Ga 0.1 Zr 0.1 Fe 68.54 The elements were directly smelted to prepare iron-neodymium-boron permanent magnets, and other preparation conditions were the same.

[0070] The remanence, coercivity, and magnetic energy product of the magnets prepared in Example 4 and Comparative Example 4 were measured using a BH instrument (model NIM-6500C) provided by the National Institute of Metrology, China. The results are shown in Table 4.

[0071] Table 4. Performance of magnets prepared in Example 4 and Comparative Example 4

[0072]

[0073] Example 5

[0074] Rapidly solidified alloy castings of main phase I and main phase II were prepared by melting according to the element ratios. The vacuum degree during the preparation of both types of rapidly solidified alloy castings was 3×10⁻⁶. -2 Pa, rotation speed 2.0 m / s, casting temperature 1340℃, chemical formula mass percentage of main phase I rapid solidification alloy casting Pr 4.8 Nd 14.7 Y 10 B 0.98 Al 0.1 Cu 0.2 Ga 0.2 Ti 0.2 Co1Fe 67.82The chemical formula (mass percentage) of the rapid-solidifying alloy casting of main phase II is Pr6Nd. 21 Gd2B 0.98 Al 0.1 Cu 0.2 Ga 0.2 Ti 0.2 Co1Fe 68.32 Rapidly solidified alloy castings of main phase I and main phase II were subjected to hydrogen absorption at room temperature and a hydrogen pressure of 0.2 MPa for 3 hours, and then vacuum dehydrogenated at 450 °C for 9 hours to obtain intermediate powders after hydrogen breakdown (hydrogen content less than 1500 ppm, average particle size of about 200 µm). Subsequently, the intermediate powders after hydrogen breakdown were further crushed by air jet milling to obtain main phase I alloy powder with a particle size of 2.3 µm and main phase II alloy powder with a particle size of 3.5 µm, respectively.

[0075] The main phase I alloy powder and main phase II alloy powder prepared above were mixed in a mass ratio of 1:7. The resulting mixed powder was then oriented and pressed under a 1.8T magnetic field to obtain a magnet. Subsequently, under atmospheric isolation conditions, the magnet was sintered in a vacuum sintering furnace at a temperature of 1090℃ for 4 hours. Finally, it was heat-treated sequentially at 850℃ and 450℃ for 4 hours each to obtain a yttrium-based neodymium iron boron magnet, Pr. 5.85 Nd 20.21 Y 1.25 Gd 1.75 B 0.98 Al 0.1 Cu 0.2 Ga 0.2 Ti 0.2 Co1Fe 68.26 .

[0076] Comparative Example 5

[0077] The difference between this comparative example and Example 5 is that: according to Pr 5.85 Nd 20.21 Y 1.25 Gd 1.75 B 0.98 Al 0.1 Cu 0.2 Ga 0. 2Ti 0.2 Co1Fe 68.26 Iron-neodymium-boron permanent magnets were prepared by direct smelting of the elements in the specified proportions, with other preparation conditions remaining the same.

[0078] The remanence, coercivity, and magnetic energy product of the magnets prepared in Example 5 and Comparative Example 5 were measured using a BH instrument (model NIM-6500C) provided by the National Institute of Metrology, China. The results are shown in Table 5.

[0079] Table 5. Performance of magnets prepared in Example 5 and Comparative Example 5

[0080]

[0081] Example 6

[0082] Rapidly solidified alloy castings of main phase I and main phase II were prepared by melting according to the element ratios. The vacuum degree during the preparation of both types of rapidly solidified alloy castings was 3×10⁻⁶. -2 Pa, rotation speed 2.0 m / s, casting temperature 1350℃, chemical formula of the main phase I rapid solidification alloy casting Nd mass percentage 9.5 Y 20 B 0.98 Al 0.1 Cu 0.1 Ga 0.2 Ti 0.15 Co 0.5 Fe 68.47 The chemical formula of the rapid-solidification alloy casting of main phase II, by mass percentage, is Pr. 27 Tb3B 0.85 Al 0.1 Ga 0.2 Zr 0.1 Co 1.2 Fe 67.55 Rapidly solidified alloy castings of main phase I and main phase II were subjected to hydrogen absorption at room temperature and a hydrogen pressure of 0.2 MPa for 3 hours, and then vacuum dehydrogenated at 450 °C for 9 hours to obtain intermediate powders after hydrogen breakdown (hydrogen content less than 1500 ppm, average particle size of about 200 µm). Subsequently, the intermediate powders after hydrogen breakdown were further crushed by air jet milling to obtain main phase I alloy powder with a particle size of 2.2 µm and main phase II alloy powder with a particle size of 3.6 µm, respectively.

[0083] The main phase I alloy powder and main phase II alloy powder prepared above were mixed in a mass ratio of 1:5. The resulting mixed powder was then oriented and pressed under a 2.0T magnetic field to obtain a magnet. Subsequently, under atmospheric isolation conditions, the magnet was sintered in a vacuum sintering furnace at a temperature of 1030℃ for 6 hours. Finally, it was heat-treated sequentially at 950℃ and 600℃ for 1 hour each to obtain a yttrium-based neodymium iron boron magnet, Pr. 22.49 Nd 1.59 Y 3.34 Tb 2.5 B 0.87 Al 0.1 Cu 0.017 Ga 0.2 Ti 0.025 Zr0.083 Co 1.083 Fe 67.702 .

[0084] Comparative Example 6

[0085] This comparative example differs from Example 6 in that: according to Pr 22.49 Nd 1.59 Y 3.34 Tb 2.5 B 0.87 Al 0.1 Cu 0.017 Ga 0.2 Ti 0.025 Zr 0.083 Co 1.083 Fe 67.702 The elements were directly smelted to prepare iron-neodymium-boron permanent magnets, and other preparation conditions were the same.

[0086] The remanence, coercivity, and magnetic energy product of the magnets prepared in Example 6 and Comparative Example 6 were measured using a BH instrument (model NIM-6500C) provided by the National Institute of Metrology, China. The results are shown in Table 6.

[0087] Comparative Example 7

[0088] The only difference between this comparative example and Example 6 is that the particle size of the main phase I alloy powder is replaced with 3.6µm, while the particle size of the main phase II alloy powder is 2.2µm. All other preparation conditions are the same.

[0089] Table 6. Performance of magnets prepared in Example 6 and Comparative Examples 6 and 7

[0090]

[0091] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method of producing a yttrium-based neodymium-iron-boron magnet, characterized by, include: A first main phase alloy powder and a second main phase alloy powder are provided, wherein the chemical formula of the first main phase alloy powder is Re. x1 Y m1 B y1 M z1 Fe 100-x1-y1-z1 The chemical formula of the second main phase alloy powder is Re. x2 Y m2 B y2 M z2 Fe 100-x2-y2-z2 Wherein, Re includes at least one of Tb, Dy, Gd, Pr, Nd, La, Ce, and Ho, and M includes at least one of Cu, Zr, Co, Ga, Si, Sn, Ge, Ti, Zn, and Al, 5≤x1≤34, 0.8<y1≤2.0, 0≤z1≤3, 0<m1≤20, 15≤x2≤35, 0.5<y2≤0.99, 0≤z2≤3, 0<m2≤15, and m1>m2; the particle size of the second main phase alloy powder is larger than that of the first main phase alloy powder, and the main phase grains of both the first and second main phase alloy powders have a core-shell structure, and the percentage of yttrium atoms in the core is higher than that in the shell. The first main phase alloy powder and the second main phase alloy powder are mixed, and then oriented pressing, sintering and tempering heat treatment are performed in sequence to obtain yttrium-based neodymium iron boron magnets.

2. The method of claim 1, wherein: The mass ratio of the first main phase alloy powder to the second main phase alloy powder is 1:(3~10).

3. The method of claim 1, wherein: The particle size of the first main phase alloy powder is 2µm to 4µm; and / or the particle size of the second main phase alloy powder is 3µm to 5µm.

4. The method of claim 1, wherein: The magnetic field strength used in the orientation pressing is 1.5T~2.0T.

5. The method of claim 1, wherein: The sintering temperature is 900℃~1150℃, and the sintering time is 1h~6h.

6. The method of claim 1, wherein: The tempering heat treatment includes a first tempering heat treatment, a second tempering heat treatment, and a third tempering heat treatment performed sequentially, or includes a first tempering heat treatment and a third tempering heat treatment performed sequentially; wherein the temperature of the first tempering heat treatment is 850℃~950℃, the temperature of the second tempering heat treatment is 650℃~800℃, the temperature of the third tempering heat treatment is 450℃~600℃, and the time of the first tempering heat treatment, the second tempering heat treatment, and the third tempering heat treatment is 1h~4h.

7. The preparation method according to claim 1, characterized in that, include: First main phase alloy castings and second main phase alloy castings were prepared by melting and smelting according to the element ratios of the first main phase alloy powder and the second main phase alloy powder, respectively. The first main phase alloy casting and the second main phase alloy casting were subjected to hydrogen crushing to obtain intermediates, which were then subjected to air jet milling to obtain the first main phase alloy powder and the second main phase alloy powder.

8. The method of claim 7, wherein: The hydrogen crushing process uses a hydrogen pressure of 0.1 MPa to 0.4 MPa, a hydrogen absorption time of 2 h to 5 h, a dehydrogenation temperature of 320 °C to 500 °C, and a dehydrogenation time of 4 h to 10 h. And / or, the hydrogen content in the intermediate obtained after hydrogen crushing is less than 1500 ppm; And / or, the average particle size of the intermediate obtained after hydrogen crushing is 100µm~250µm.

9. A yttrium-based neodymium iron boron magnet prepared by any one of claims 1 to 8.

10. The application of the yttrium-based neodymium iron boron magnet of claim 9 in wind power generation, new energy vehicles, rail transit, humanoid robots, or low-altitude economy.

Images