High-performance R-T-B permanent magnet material and preparation method thereof

Abstract

The invention relates to the technical field of magnetic materials, in particular to a high-performance R-T-B permanent magnet material and a preparation method thereof.The high-performance R-T-B permanent magnet material is composed of a main phase alloy D, a grain boundary phase G and a grain boundary phase F. The magnet component is expressed as D100-u-vGuFv by weight percent, u < = 5wt%, 0lt; v < = 2 wt%; powder needed by the magnet is added according to functions, the adding mode is simple and convenient, the existing production process does not need to be changed, the rare earth consumption of the magnet is reduced, the performance of the magnet is improved, the content of rare earth at the grain boundary corner is reduced, and grain boundary channels are increased; the consumption of the diffusion source at the grain boundary is reduced, and the diffusion source can penetrate into the magnet along a grain boundary channel, so that the coercive force of the magnet can be better improved by using fewer diffusion sources.

Description

Technical Field

[0001] This invention relates to the technical field of magnetic materials, and in particular to a high-performance RTB permanent magnet material and its preparation method. Background Technology

[0002] With R2T 14 RTB (R represents rare earth elements including Y, and T represents transition metals including Fe) permanent magnet materials with B-type compounds as the main phase have high remanence, high coercivity, and high energy product, and have been widely used in modern industry and electronic technology, such as electronic computers, automated control systems, electric motors and generators, nuclear magnetic resonance imaging, audio devices, material sorting devices, communication equipment and many other fields. Main phase Nd2Fe 14 The magnetic flux density Br of B is very high, approximately 1.61 T (16.1 kGs), and the theoretical maximum magnetic energy product BHmax can reach 512 kJ / m. 3 Nd2Fe 14 B has a very high anisotropic field H A Its coercivity Hcj has a theoretical limit as high as 70 kOe. Currently, the remanence Br of RTB magnets can reach 1.55 T, and the maximum energy product BHmax is 474 kJ / m. 3 The values ​​reached 96% and 92% of the theoretical values, respectively, while the coercivity Hcj of the magnet was only one-tenth to one-third of the theoretical value, resulting in poor temperature stability of the magnet and greatly limiting the application fields of RTB magnets. The preparation of dual-high magnets with high remanence and high coercivity mainly focuses on improving H A And improve the boundary phase structure, such as by using grain boundary diffusion methods to add micron or nano-sized powders of heavy rare earth elements or compounds, using grain refinement methods, two-liquid phase alloying methods, and methods such as doping with rare earth hydrides, as well as methods to effectively control the microstructure of materials, to improve the coercivity of magnets. Adding larger amounts of Dy and Tb heavy rare earth elements, although H A While the coercivity is significantly improved, the antiferromagnetic coupling between heavy rare earth elements and iron reduces the magnetic moment of iron atoms, leading to a decrease in Bs and Br. This is detrimental to the preparation of high remanence and high coercivity magnets. Furthermore, Dy and Tb are very expensive, significantly increasing product costs and hindering the comprehensive and efficient utilization of Dy and Tb heavy rare earth elements, which are scarce resources. Therefore, reducing or even eliminating Dy and Tb in high coercivity and high remanence materials holds promise for breakthroughs in grain boundary phase and structure control. The introduction of any non-magnetic phase (element), while increasing coercivity, will more or less reduce the remanence of the magnet. Therefore, it is necessary to improve the composition design and process control of magnetic phases and grain boundary phases to prepare high remanence and high coercivity RTB permanent magnet materials. Currently, the magnetic main phase of the magnet is not the stoichiometric Nd₂Fe. 14 Boron (B) typically contains an excess of boron (B) and rare earth element (R), as well as cobalt (Co) and some non-magnetic elements such as Al, Ga, Cu, Nb, Sn, Zn, Zr, and Ti, to improve the coercivity of the magnet. However, the addition of non-magnetic elements and phases reduces the remanence of the magnet. Another method is to add auxiliary alloy powder via grain boundary addition. This involves preparing metal powder or alloy powder with one or more elements such as Al, Ga, Co, Cu, Nb, Zr, Ti, and rare earth elements (R), and adding it to a substrate containing Nd₂Fe₂. 14 In powders dominated by the boron phase, the aim is to improve the grain boundary structure and enhance the coercivity of the magnet. This method of grain boundary addition can, to some extent, compensate for grain boundary defects in magnets prepared with single, dual, or multiple main phases, and improve magnet stability to some extent, but the effect is still not ideal. This is because the segregation of grain boundary phase elements into the main phase reduces the remanence of the magnet. Furthermore, the segregation of rare earth elements such as R, Fe, and B in the main phase also leads to unstable magnet performance. Typically, an excessive amount of R and B is added to the main phase, which results in a less significant improvement in remanence. Therefore, the addition of traditional grain boundary alloys can only improve coercivity to a certain extent and has a negative effect on improving remanence. This makes it difficult to prepare magnets with high remanence and high coercivity. Although grain boundary diffusion technology has been developed, it has certain limitations on the thickness of the magnet and differs significantly from the basic principles and technical methods of this technique. Patent CN201910422006.0 discloses a magnet containing a main phase alloy D, a non-magnetic grain boundary phase alloy G, and a rare-earth-rich R and B-rich auxiliary alloy phase F, as well as its preparation method. The grain boundary phase G repairs and optimizes grain boundary defects, while the auxiliary alloy phase F pins the main phase D and provides necessary trace amounts of B and rare-earth R elements to both the main phase D and the grain boundary phase G, thereby producing a magnet with high remanence, high coercivity, and high temperature stability. However, this magnet still contains a rare-earth-rich R and B-rich auxiliary alloy, which limits the preparation of magnets with even higher remanence and coercivity. Therefore, there is an urgent need for a high-performance RTB permanent magnet material and its preparation method to improve the above problems. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a high-performance RTB permanent magnet material and its preparation method that uses powder added according to function to power magnets. This method is simple and convenient, does not require changes to the existing production process, reduces the amount of rare earth elements used in the magnets, improves the performance of the magnets, reduces the content of rare earth elements at grain boundary corners and increases grain boundary channels, reduces the consumption of diffusion sources at grain boundaries and allows diffusion sources to penetrate deep into the magnets along the grain boundary channels. Thus, it can improve the coercivity of the magnets with fewer diffusion sources.

[0004] This invention discloses a high-performance RTB permanent magnet material, composed of a main phase alloy D, a grain boundary phase G, and a grain boundary phase F. The magnet composition, expressed as D100-u-vGuFv by weight percentage, wherein 0 <u≤5 wt %,0<v≤2 wt%。

[0005] Preferably, the composition of the main phase alloy D is RxT100-xy-zMyBz, where R represents Nd or one or more rare earth elements including Y, T represents one or more of Co and Fe, M represents one or more of Al, Ag, Au, Bi, Cu, Ga, Nb, Mo, Sn, Ti, Zn, and Zr, B represents boron, and 27≤x≤31 wt%, 0 <y≤3wt %,0.85≤z≤1.0wt%; The composition of the grain boundary phase G is expressed as RaQ100-a, where R represents Nd or one or more rare earth elements including Y, Q represents one or more of Al, Ag, Au, Bi, Fe, Co, Cu, Ga, Sn, Ti, Zn, Zr, and Nb, and 0 ≤ a ≤ 100 wt%. The grain boundary phase F is composed of at least one oxide or fluoride formed from Al, Ca, Fe, Mg, Mo, Si, Ti, Zn, Zr, and rare earth element R.

[0006] The present invention provides a method for preparing a high-performance RTB permanent magnet material, comprising the following steps: S1. Prepare the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain alloy sheet D. S2. The D alloy sheet is subjected to hydrogen pulverization and air jet milling to obtain D powder with an average particle size of 2-3.5 μm; S3. The powder prepared in S2 is subjected to magnetic field orientation molding and sintering heat treatment to obtain RTB permanent magnet material.

[0007] Preferably, in step S1, when preparing the main phase alloy D using rapid solidification melting, the rapid solidification melting involves placing the main phase alloy raw materials into a crucible in a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1350–1550°C, and the alloy liquid is poured onto a water-cooled copper roller with a linear velocity of 1.0–3.0 m / s to prepare main phase alloy rapid solidification sheets with an average thickness of 0.15–0.45 mm.

[0008] Preferably, step S2 or S3 further includes the step of adding grain boundary phase G and F powder.

[0009] Preferably, before hydrogen breakdown, at least one of the grain boundary phases G and F is added to the alloy sheet of D; After hydrogenation and before air jet milling, at least one of the grain boundary phases G and F is added to the hydrogenation powder of D.

[0010] Preferably, before molding, at least one of the grain boundary phases G and F is added to the air-jet milled powder of D.

[0011] Preferably, the average particle size of the grain boundary phase G powder is 1–5 μm; The grain boundary phase F consists of two powders with different particle sizes: one is a coarse powder with an average particle size d1 ranging from 1.5 to 5 μm, and the other is a fine powder with an average particle size d2 ranging from 0.02 to 0.5 μm. The ratio of their average particle sizes satisfies the relationship: d1 / d2 ≥ 10. The two particle size ranges of F powder can be the same F powder or different F powders. The weight of coarse particle powder m1 and the weight of fine particle powder m2 added satisfy the relationship: 0.1≤m2 / m1≤10.

[0012] Preferably, the detailed operation method of S3 is as follows: Magnetic powder is oriented using a magnetic field to form a blank with a magnetic field strength of 1.5T or higher and a forming density of 3.8–4.5 g / cm³. 3 The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. It is then degassed at 500℃~700℃ and 830~930℃ for 0.5~3h respectively. Then, it is vacuum sintered at 1020~1100℃ for 2~5h. Finally, it is aged heat treated at 800~930℃ and 450~650℃ for 2~9h respectively to obtain the RTB permanent magnet material.

[0013] Preferably, after S3, the step further includes a grain boundary diffusion treatment of the RTB permanent magnet material; The grain boundary diffusion treatment includes: arranging a diffusion source on the surface of the magnet substrate obtained after processing, heating under vacuum conditions, performing grain boundary diffusion treatment at 800-950℃, holding for 3-48 hours, and performing aging treatment after diffusion at a temperature of 450-650℃. The diffusion source includes heavy rare earth elements, and the arrangement method of the diffusion source is selected from spraying, dipping, sputtering or screen printing.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: the powder required for the magnet is added according to its function, which is simple and convenient to add without changing the existing production process, reducing the amount of rare earth used in the magnet, improving the performance of the magnet, reducing the content of rare earth at the grain boundary corners and increasing the grain boundary channels, reducing the consumption of diffusion source at the grain boundary and allowing it to penetrate deep into the magnet along the grain boundary channels, thereby improving the coercivity of the magnet with less diffusion source. Detailed Implementation

[0015] To facilitate understanding of the present invention, a more comprehensive description will be given below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0016] This invention discloses a high-performance RTB permanent magnet material, composed of a main phase alloy D, a grain boundary phase G, and a grain boundary phase F. The magnet composition, expressed as D100-u-vGuFv by weight percentage, wherein 0 <u≤5 wt %,0<v≤2 wt%。

[0017] The composition of the main phase alloy D is RxT100-xy-zMyBz, where R represents Nd or one or more rare earth elements including Y, T represents one or more of Co and Fe, M represents one or more of Al, Ag, Au, Bi, Cu, Ga, Nb, Mo, Sn, Ti, Zn, and Zr, B represents boron, and 27 ≤ x ≤ 31 wt%, 0 <y≤3wt %,0.85≤z≤1.0wt%; The composition of the grain boundary phase G is expressed as RaQ100-a, where R represents Nd or one or more rare earth elements including Y, Q represents one or more of Al, Ag, Au, Bi, Fe, Co, Cu, Ga, Sn, Ti, Zn, Zr, and Nb, and 0 ≤ a ≤ 100 wt%. The grain boundary phase F is composed of at least one oxide or fluoride formed from Al, Ca, Fe, Mg, Mo, Si, Ti, Zn, Zr, and rare earth element R.

[0018] The present invention provides a method for preparing a high-performance RTB permanent magnet material, comprising the following steps: S1. Prepare the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain alloy sheet D. S2. The D alloy sheet is subjected to hydrogen pulverization and air jet milling to obtain D powder with an average particle size of 2-3.5 μm; S3. The powder prepared in S2 is subjected to magnetic field orientation molding and sintering heat treatment to obtain RTB permanent magnet material.

[0019] In step S1, when preparing the main phase alloy D using rapid solidification melting, the rapid solidification melting involves placing the main phase alloy raw materials into a rapid solidification furnace crucible and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1350–1550°C, and the alloy liquid is poured onto a water-cooled copper roller with a linear velocity of 1.0–3.0 m / s to prepare main phase alloy rapid solidification sheets with an average thickness of 0.15–0.45 mm.

[0020] The step of adding grain boundary phase G and F powder is also included in S2 or S3.

[0021] Before hydrogen breakdown, at least one of the grain boundary phases G and F powders is added to the alloy sheet of D. After hydrogenation and before air jet milling, at least one of the grain boundary phases G and F is added to the hydrogenation powder of D.

[0022] Before molding, at least one of the grain boundary phases G and F is added to the air-jet milled powder of D.

[0023] The average particle size of the grain boundary phase G powder is 1–5 μm. The grain boundary phase F consists of two powders with different particle sizes: one is a coarse powder with an average particle size d1 ranging from 1.5 to 5 μm, and the other is a fine powder with an average particle size d2 ranging from 0.02 to 0.5 μm. The ratio of their average particle sizes satisfies the relationship: d1 / d2 ≥ 10. The two particle size ranges of F powder can be the same F powder or different F powders. The weight of coarse particle powder m1 and the weight of fine particle powder m2 added satisfy the relationship: 0.1≤m2 / m1≤10.

[0024] The detailed operation method of S3 is as follows: Magnetic powder is oriented using a magnetic field to form a blank with a magnetic field strength of 1.5T or higher and a forming density of 3.8–4.5 g / cm³. The blank is then placed in a high-vacuum sintering furnace, where a vacuum of less than 0.5 Pa is applied before heating. The blank is degassed at 500–700℃ and 830–930℃ for 0.5–3 hours, respectively. It is then vacuum sintered at 1020–1100℃ for 2–5 hours, followed by aging heat treatment at 800–930℃ and 450–650℃ for 2–9 hours, respectively, to finally obtain the RTB permanent magnet material.

[0025] Following S3, the process further includes a step of grain boundary diffusion treatment on the RTB permanent magnet material. The grain boundary diffusion treatment includes: arranging a diffusion source on the surface of the magnet substrate obtained after processing, heating under vacuum conditions, performing grain boundary diffusion treatment at 800-950℃, holding for 3-48 hours, and performing aging treatment after diffusion at a temperature of 450-650℃. The diffusion source includes heavy rare earth elements, which are not specifically limited in this invention. For example, they may be metallic dysprosium, metallic terbium, oxides of dysprosium and / or terbium, fluorides of dysprosium and / or hydrides of dysprosium and / or terbium, or alloys of dysprosium and / or terbium containing other elements (Pr, Nd, Al, Cu, Ga, Fe, Co, Ti, Zr, Nb, etc.). The diffusion source can be arranged by spraying, dip coating, sputtering, or screen printing.

[0026] Example 1: A high-performance RTB permanent magnet material is composed of a main phase alloy D, a grain boundary phase G, and a grain boundary phase F. The magnet composition is expressed as D by weight percentage. 100-u-v G u F v D represents the main phase alloy D, G represents the grain boundary phase alloy G, and F represents the grain boundary phase F, with u = 0.5 wt% and v = 0.5 wt%. The main phase alloy D has a composition of (PrNd). 28.5 Fe 余 Co 0.8 Cu 0.1 Ga 0.1 Zr 0.1 B 0.92 The grain boundary phase G is PrNd, and the auxiliary alloy phase F is Al2O3.

[0027] A method for preparing high-performance RTB permanent magnet materials includes the following steps: S1. Prepare the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain alloy sheet D. S2. The D alloy sheet is subjected to hydrogen pulverization and air jet milling to obtain D powder with an average particle size of 2.9 μm; S3. The powder prepared in S2 is subjected to magnetic field orientation molding and sintering heat treatment to obtain the RTB permanent magnet material; In S1, rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1450℃, and the alloy liquid is poured onto a water-cooled copper roller with a linear speed of 2.0 m / s to prepare rapid solidification sheets of the main phase alloy D with an average thickness of 0.25 mm. In S2, before hydrogen pulverization, 0.5% PrNd (grain boundary phase G) and 0.5% Al2O3 (grain boundary phase F) powders are added to an alloy sheet containing 99.0% D by mass. Then, they are hydrogen pulverized and air-jet milled together. The particle size of the grain boundary phase G powder is the same as that of the D powder, both being ground to an average particle size of 2.9 μm. The added grain boundary phase F powder consists of two types of Al2O3 powder with different average particle sizes: one is a coarse powder with an average particle size d1 of 1.5 μm, and the other is a fine powder with an average particle size d2 of 0.02 μm. The average particle size ratio between the two is d1 / d2 = 75. The masses m1 and m2 of the coarse and fine powders satisfy the relationship: m1 / m2 = 0.1. The S3 method involves: magnetic powder being oriented using a magnetic field to form a blank, with a magnetic field strength of 1.6T and a forming density of 4.2 g / cm³. 3 The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. It is then degassed by holding at 500℃ and 900℃ for 2 hours and 2 hours respectively. Then, it is vacuum sintered at 1020-1100℃ for 5 hours, and then aged at 900℃ and 500℃ for 3 hours and 2 hours respectively to finally obtain the RTB permanent magnet material.

[0028] As a comparative example 1-1, only the component (PrNd) was considered. 29.5 Fe 余 Co 0.8 Cu 0.1 Ga 0.1 Zr 0.1 B 0.92The main phase alloy D was prepared into a magnet by hydrogen crushing, air jet milling, pressing, and sintering. This method only uses the main phase alloy D and does not add grain boundary phases G and F. The PrNd content in the main phase alloy D is 29.5%, which is 1% more than the PrNd content in the main phase alloy D in Example 1. This is exactly equivalent to the total amount of grain boundary phases G and F added in Example 1. Apart from this, the preparation method of Comparative Example 1-1 is the same as that of Example 1. Specifically, the preparation method is as follows: S1, prepare the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain D alloy sheet; S2, pulverize the D alloy sheet by hydrogen crushing and air jet milling to obtain D powder with an average particle size of 2.9 μm; S3, plough the powder prepared in S2 by magnetic field orientation pressing and sintering heat treatment to obtain the RTB permanent magnet material. In S1, rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1450℃, and the alloy liquid is poured onto a water-cooled copper roller with a linear speed of 2.0 m / s to prepare rapid solidification sheets of the main phase alloy D with an average thickness of 0.25 mm. The S3 method involves: magnetic powder being oriented using a magnetic field to form a blank, with a magnetic field strength of 1.6T and a forming density of 4.2 g / cm³. 3 The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. It is then degassed by holding at 500℃ and 900℃ for 2 hours and 2 hours respectively. Then, it is vacuum sintered at 1020-1100℃ for 5 hours, and then aged at 900℃ and 500℃ for 3 hours and 2 hours respectively to finally obtain the RTB permanent magnet material.

[0029] As comparative examples 1-2, the composition was (PrNd). 28.5 Fe 余 Co 0.8 Cu 0.1 Ga 0.1 Zr 0.1 B 0.92The magnet is prepared by mixing the main phase alloy D with PrNd (grain boundary phase G). The preparation method differs from that in Example 1 in that: before hydrogen crushing, 1.0% of PrNd (grain boundary phase G) is added to the alloy sheet containing 99.0% of D by mass. Then, the magnet is prepared by hydrogen crushing, air jet milling, pressing, and sintering. Except for the absence of grain boundary phase F powder, the preparation method is the same as in Example 1. Specifically, the preparation method is as follows: S1, prepare the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain D alloy sheet; S2, perform hydrogen crushing and air jet milling on the D alloy sheet to obtain D powder with an average particle size of 2.9 μm; S3, perform magnetic field orientation pressing and sintering heat treatment on the powder prepared in S2 to obtain the RTB permanent magnet material. In S1, rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1450℃, and the alloy liquid is poured onto a water-cooled copper roller with a linear speed of 2.0 m / s to prepare rapid solidification sheets of the main phase alloy D with an average thickness of 0.25 mm. In S2, before hydrogen pulverization, 1.0% of PrNd (grain boundary phase G) is added to an alloy sheet containing 99.0% of D by mass. The two alloy sheets are then hydrogen pulverized and air-jet milled together. The particle size of the grain boundary phase G powder is the same as that of the D powder, and both are milled to an average particle size of 2.9 μm.

[0030] The S3 method involves: magnetic powder being oriented using a magnetic field to form a blank, with a magnetic field strength of 1.6T and a forming density of 4.2 g / cm³. 3 The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. It is then degassed by holding at 500℃ and 900℃ for 2 hours and 2 hours respectively. Then, it is vacuum sintered at 1020-1100℃ for 5 hours, and then aged at 900℃ and 500℃ for 3 hours and 2 hours respectively to finally obtain the RTB permanent magnet material.

[0031] The magnetic properties of the NdFeB materials prepared by the methods of Example 1, Comparative Example 1-1, and Comparative Example 1-2 were tested, and the results are shown in Table 1. The magnet prepared in Example 1 has a remanence of 15.32 kGs, a coercivity of 12.48 kOe, and a squareness of 97.8%, all of which are better than the magnets prepared in Comparative Example 1-1 and Comparative Example 1-2. Compared with Example 1, adding rare earth elements to the grain boundaries helps to reduce the amount of rare earth elements used in the main phase. The grain boundary phases G and F enriched in the grain boundaries can also better assist liquid phase sintering, thereby improving the remanence and coercivity of the magnet. Compared with Example 1, in Example 1, the grain boundary phase F with different particle sizes and high melting points fills the intergranular and intergranular triangular regions of the main phase D grains, which to some extent replaces the rare earth-rich grain boundary phase. This achieves intergranular isolation of the main phase D, increases the grain boundary thickness, reduces the amount of rare earth elements used, lowers the cost, and improves the remanence and coercivity.

[0032] Example 2: A high-performance RTB permanent magnet material is composed of a main phase alloy D, a grain boundary phase G, and a grain boundary phase F. The magnet composition is expressed as D by weight percentage. 100-u-v G u F v D represents the main phase alloy D, G represents the grain boundary phase alloy G, and F represents the grain boundary phase F, with u = 2wt% and v = 0.5wt%. The main phase alloy D has a composition of (PrNd). 28 Dy 0.5 Fe 余 Co 1.5 Cu 0.1 Ga 0.1 Ti 0.15 B 0.96 The grain boundary phase G is Dy 95 Al5, wherein the grain boundary phase F is Al2O3.

[0033] A method for preparing high-performance RTB permanent magnet materials includes the following steps: S1. Prepare the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain alloy sheet D. S2. The D alloy sheet is subjected to hydrogen pulverization and air jet milling to obtain D powder with an average particle size of 2.8 μm; S3. The powder prepared in S2 is subjected to magnetic field orientation molding and sintering heat treatment to obtain the RTB permanent magnet material.

[0034] In S1, rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1450℃, and the alloy liquid is poured onto a water-cooled copper roller with a linear speed of 1.0 m / s to prepare rapid solidification sheets of the main phase alloy D with an average thickness of 0.35 mm. In S2, grain boundary phases G powder and F powder are added to the D powder after air jet milling, and the three are mixed evenly. Specifically, after air jet milling, D powder will contain 2% Dy powder as a total mass fraction. 95 Al5 (grain boundary phase G) and Al2O3 (grain boundary phase F) powder (0.5% by mass) are added to powder D (97.5% by mass) and mixed thoroughly. The average particle size of grain boundary phase G powder is 2 μm. The added grain boundary phase F powder consists of two Al2O3 powders with different average particle sizes: one is a coarse powder with an average particle size d1 of 2 μm, and the other is a fine powder with an average particle size d2 of 0.05 μm. The average particle size ratio between the two is d1 / d2 = 40. The masses m1 and m2 of the coarse and fine powders satisfy the relationship: m1 / m2 = 10. The S3 method involves: magnetic powder being oriented using a magnetic field to form a blank, with a magnetic field strength of 1.8T and a forming density of 4.2 g / cm³. 3 The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. It is then degassed by holding at 600℃ and 930℃ for 1 h and 3 h respectively. Then it is vacuum sintered at 1020~1100℃ for 3 h, and then aged at 900℃ and 500℃ for 3 h and 3 h respectively, finally obtaining the RTB permanent magnet material.

[0035] As a comparative example 2, the composition was (PrNd). 28 Dy 2.4 Fe 余 Co 1.5 Al 0.1 Cu 0.1 Ga 0.1 Ti 0.15 B 0.96Magnets were prepared by mixing the air-jet milled main phase alloy D with Al2O3 (grain boundary phase F) powder. The Dy and Al contents of the main phase alloy D in Comparative Example 2 were 1.9% and 0.1% higher, respectively, than those in the main phase alloy D of Example 2 (these 1.9% and 0.1% contents are exactly equivalent to the Dy and Al contents of the 2% grain boundary phase G added in Comparative Example 2 converted to the magnet content). The difference between Comparative Example 2 and Example 2 was that, after air-jet milling, 0.5% Al2O3 (grain boundary phase F) powder was added to the main phase alloy D of Example 2. The magnet was prepared by air-jet milling powder containing 99.5% D, followed by pressing and sintering. The preparation method was the same as in Example 2, except that no grain boundary phase G powder was added. Specifically, the preparation method of Comparative Example 2 was as follows: S1, preparing the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain D alloy sheets; S2, subjecting the D alloy sheets to hydrogen annealing and air-jet milling to obtain D air-jet milled powder with an average particle size of 2.8 μm; S3, subjecting the powder prepared in S2 to magnetic field orientation pressing and sintering heat treatment to obtain the RTB permanent magnet material. In S1, rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1450℃, and the alloy liquid is poured onto a water-cooled copper roller with a linear velocity of 1.0 m / s to prepare rapid solidification sheets of the main phase alloy D with an average thickness of 0.35 mm. In S2, grain boundary phase F powder is added to the air-jet milled powder D after air-jet milling and the two are mixed evenly. Specifically, after air-jet milling powder D, Al2O3 (grain boundary phase F) powder accounting for 0.5% of the total mass fraction is added to the air-jet milled powder D accounting for 99.5% of the total mass fraction and the two are mixed evenly. The average particle size of the added grain boundary phase F powder is 2 μm. The S3 method involves: magnetic powder being oriented using a magnetic field to form a blank, with a magnetic field strength of 1.8T and a forming density of 4.1 g / cm³. 3 The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. It is then degassed by holding at 600℃ and 930℃ for 1 h and 3 h respectively. Then it is vacuum sintered at 1020~1100℃ for 3 h, and then aged at 900℃ and 500℃ for 3 h and 3 h respectively, finally obtaining the RTB permanent magnet material.

[0036] The magnetic properties of the neodymium iron boron materials prepared by the methods of Example 2 and Comparative Example 2 were tested, and the results are shown in Table 1. It can be seen that when using the same amount of rare earth and adding the grain boundary phase F, the magnet prepared in Example 2 has higher remanence and coercivity.

[0037] Example 3: A high-performance RTB permanent magnet material is composed of a main phase alloy D, a grain boundary phase G, and a grain boundary phase F. The magnet composition is expressed as D by weight percentage. 100-u-v G u F v D represents the main phase alloy D, G represents the grain boundary phase alloy G, and F represents the grain boundary phase F, with u = 5 wt% and v = 2 wt%. The main phase alloy D has a composition of (PrNd). 27 Fe 余 Co1Cu 0.1 Ga 0.1 Zr 0.1 B 0.92 The grain boundary phase G is Dy 90 Al5Zr5, wherein the auxiliary alloy phase F is Al2O3 or CeO2.

[0038] A method for preparing high-performance RTB permanent magnet materials includes the following steps: S1. Prepare the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain alloy sheet D. S2. The D alloy sheet is subjected to hydrogen pulverization and air jet milling to obtain D powder with an average particle size of 3.0 μm; S3. The powder prepared in S2 is subjected to magnetic field orientation molding and sintering heat treatment to obtain the RTB permanent magnet material; In S1, rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1500℃, and the alloy liquid is poured onto a water-cooled copper roller with a linear velocity of 2.5m / s to prepare rapid solidification sheets of the main phase alloy D with an average thickness of 0.22mm. In S2, grain boundary phases G powder and F powder are added to the D powder after air jet milling and the three are mixed evenly. Specifically, after air jet milling, D powder will contain 5% Dy powder by mass. 90 Al5Zr5 (grain boundary phase G) powder, Al2O3 (2% by mass), and CeO2 (grain boundary phase F) powder (93% by mass) are added to powder D and mixed thoroughly. The average particle size of the grain boundary phase G powder is 1 μm. The added grain boundary phase F powder consists of Al2O3 and CeO2 powders. The Al2O3 powder has an average particle size d1 of 5 μm (coarse powder), and the CeO2 powder has an average particle size d2 of 0.5 μm (fine powder). The average particle size ratio between the two is d1 / d2 = 10. The mass m1 of the coarse Al2O3 powder and the mass m2 of the fine CeO2 powder satisfy the relationship: m1 / m2 = 0.5. The S3 method involves: magnetic powder being oriented using a magnetic field to form a blank, with a magnetic field strength of 1.8T and a forming density of 4.2 g / cm³. 3The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. It is then degassed by holding at 600℃ and 830℃ for 0.5 h and 3 h respectively. Then it is vacuum sintered at 1020~1100℃ for 6 h, and then aged at 930℃ and 550℃ for 9 h and 6 h respectively, finally obtaining the RTB permanent magnet material.

[0039] As a comparative example 3, the composition was (PrNd). 27 Fe 余 Co1Cu 0.1 Ga 0.1 Zr 0.1 B 0.92 Airflow milling of main phase alloy D and Dy 90 The magnet was prepared by mixing Al5Zr5 (grain boundary phase G) powder. The difference between this preparation method and that of Example 3 is that after air jet milling, 5% Dy... 90 Al5Zr5 (grain boundary phase G) powder was added to air-jet milled powder of D, which accounted for 95% of the total mass fraction. Then, magnets were prepared by pressing and sintering. The preparation method was the same as in Example 3 except that grain boundary phase F powder was not added. Specifically, the preparation method of Comparative Example 3 was as follows: S1, prepare the main phase alloy D by rapidly solidifying and melting the raw materials required to prepare the main phase alloy D to obtain D alloy sheet; S2, perform hydrogen pulverization and air-jet milling on the D alloy sheet to obtain air-jet milled powder of D with an average particle size of 3.0 μm; S3, perform magnetic field orientation pressing and sintering heat treatment on the powder prepared in S2 to obtain the RTB permanent magnet material. In S1, rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1500℃, and the alloy liquid is poured onto a water-cooled copper roller with a linear velocity of 2.5m / s to prepare rapid solidification sheets of the main phase alloy D with an average thickness of 0.22mm. In S2, this involves adding grain boundary phase G powder to the air-jet milled powder D and mixing them uniformly. Specifically, after air-jet milling, Dy powder, accounting for 5% of the total mass fraction, is added. 90 Al5Zr5 (grain boundary phase G) powder was added to an air-jet milled powder containing 95% D by mass and the two were mixed uniformly. The average particle size of the grain boundary phase G powder was 1 μm. The S3 method involves: magnetic powder being oriented using a magnetic field to form a blank, with a magnetic field strength of 1.8T and a forming density of 4.2 g / cm³. 3The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. It is then degassed by holding at 600℃ and 830℃ for 0.5 h and 3 h respectively. Then it is vacuum sintered at 1020~1100℃ for 6 h, and then aged at 930℃ and 550℃ for 9 h and 6 h respectively, finally obtaining the RTB permanent magnet material.

[0040] The magnetic properties of the NdFeB materials prepared by the methods in Example 3 and Comparative Example 3 were tested, and the results are shown in Table 1. It can be seen that all methods used the method of adding 5% Dy at the grain boundaries. 90 In the case of Al5Zr5 (grain boundary phase G) heavy rare earth powder, Example 3 further replaced the corresponding proportion of main phase alloy D with grain boundary phase F accounting for 2% of the total mass fraction. The remanence of Example 3 decreased (compared to Comparative Example 3), but the decrease was much less than 2% (i.e., the dilution of magnetic properties by the added 2% grain boundary phase F was less than 2%). Moreover, the coercivity of Example 3 was significantly higher than that of the Comparative Example. Therefore, grain boundary phase F can reduce the enrichment of main phase D and rare earth grain boundary phase at the grain boundaries, improve coercivity, and reduce costs. Furthermore, the resulting decrease in remanence of the magnet is also significantly lower than that caused by the addition of grain boundary phase F.

[0041] Example 4: A high-performance RTB permanent magnet material is composed of a main phase alloy D, a grain boundary phase G, and a grain boundary phase F. The magnet composition is expressed as D by weight percentage. 100-u-v G u F v D represents the main phase alloy D, G represents the grain boundary phase alloy G, and F represents the grain boundary phase F, with u = 0.5 wt% and v = 1 wt%. The main phase alloy D has a composition of (PrNd). 29 Dy 1.5 Fe 余 Co1Cu 0.1 Ga 0.1 Zr 0.1 B 0.90 The grain boundary phase G is Pr 90 Cu5Ga5, wherein the auxiliary alloy phase F is DyF3 or ZrO2.

[0042] A method for preparing high-performance RTB permanent magnet materials includes the following steps: S1. Prepare the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain alloy sheet D. S2. The D alloy sheet is subjected to hydrogen pulverization and air jet milling to obtain D powder with an average particle size of 3.0 μm; S3. The powder prepared in S2 is subjected to magnetic field orientation molding and sintering heat treatment to obtain the RTB permanent magnet material; In S1, rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1480℃, and the alloy liquid is poured onto a water-cooled copper roller with a linear velocity of 2.0 m / s to prepare rapid solidification sheets of the main phase alloy D with an average thickness of 0.25 mm. In S2, grain boundary phases G powder and F powder are added to the D powder after air jet milling, and the three are mixed evenly. Specifically, after air jet milling, Pr, which accounts for 0.5% of the total mass fraction, is added to the D powder. 90 Cu5Ga5 (grain boundary phase G) powder, DyF3 (1% by mass) and ZrO2 (grain boundary phase F) powder (98.5% by mass) are added to D powder and mixed evenly. The average particle size of the grain boundary phase G powder is 5 μm. The added grain boundary phase F powder consists of two types of powders: DyF3 and ZrO2. The ZrO2 powder has an average particle size d1 of 2 μm (coarse powder), and the DyF3 powder has an average particle size d2 of 0.5 μm (fine powder). The average particle size ratio between the two is d1 / d2 = 4. The mass m1 of the coarse ZrO2 powder and the mass m2 of the fine DyF3 powder satisfy the relationship: m1 / m2 = 1, that is, the mass fraction of DyF3 is 0.5% and the mass fraction of ZrO2 is 0.5%. The S3 method involves: magnetic powder being oriented using a magnetic field to form a blank, with a magnetic field strength of 1.8T and a forming density of 4.2 g / cm³. 3 The prepared blank was placed in a high vacuum sintering furnace, and the vacuum was evacuated to less than 0.5 Pa before heating was started. The blank was degassed by holding it at 700℃ and 880℃ for 0.5 h and 0.5 h respectively. Then, it was vacuum sintered at 1020~1100℃ for 5 h, and then aged at 900℃ and 500℃ for 6 h and 9 h respectively to finally obtain the RTB permanent magnet material. As a comparative example 4, the composition was (PrNd). 29 Dy 1.5 Fe 余 Co1Cu 0.1 Ga 0.1 Zr 0.1 B 0.90 Airflow milling of main phase alloy D with Pr 90 The magnet was prepared by mixing Cu5Ga5 (grain boundary phase G) powder and DyF3 (grain boundary phase F) powder. The difference between this preparation method and that of Example 4 is that only one type of grain boundary phase F powder with an average particle size was added. After air jet milling, Pr, accounting for 0.5% of the total mass fraction, was added. 90Cu5Ga5 (grain boundary phase G) powder and 0.5% DyF3 by mass are added to an air-jet milled powder containing 99% D by mass. The magnet is then prepared by pressing and sintering. This method is the same as that in Example 4 except that only one type of F powder with an average particle size is added. Specifically, the preparation method of Comparative Example 4 is as follows: S1 Prepare the main phase alloy D by rapidly solidifying and melting the raw materials required to prepare the main phase alloy D to obtain D alloy sheet; S2 Perform hydrogen pulverization and air-jet milling on the D alloy sheet to obtain D air-jet milled powder with an average particle size of 3.0 μm; S3 Perform magnetic field orientation pressing and sintering heat treatment on the powder prepared in S2 to obtain the RTB permanent magnet material. In S1, rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1480℃, and the alloy liquid is poured onto a water-cooled copper roller with a linear velocity of 2.0 m / s to prepare rapid solidification sheets of the main phase alloy D with an average thickness of 0.25 mm. In S2, grain boundary phases G powder and F powder are added to the D powder after air jet milling, and the three are mixed evenly. Specifically, after air jet milling, Pr, which accounts for 0.5% of the total mass fraction, is added to the D powder. 90 Cu5Ga5 (grain boundary phase G) powder and DyF3 powder accounting for 0.5% of the total mass fraction were added to an air-jet mill powder accounting for 99% of the total mass fraction of D and the three were mixed evenly. The average particle size of the grain boundary phase G powder was 5 μm and the average particle size of the DyF3 powder was 0.5 μm. The S3 method involves: magnetic powder being oriented using a magnetic field to form a blank, with a magnetic field strength of 1.8T and a forming density of 4.2 g / cm³. 3 The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. It is then degassed by holding at 700℃ and 880℃ for 0.5 h and 0.5 h respectively. Then it is vacuum sintered at 1020~1100℃ for 5 h, and then aged at 900℃ and 500℃ for 6 h and 9 h respectively to finally obtain the RTB permanent magnet material.

[0043] Comparison shows that the grain boundary phase Pr added in Example 4 and Comparative Example 4... 90The addition amounts and methods of Cu5Ga5 (grain boundary phase G) powder and DyF3 powder were the same in Example 4 and Comparative Example 4. The difference between the two was that Example 4 added 0.5% more ZrO2 (grain boundary phase F) powder and correspondingly reduced the amount of main phase alloy D by 0.5%. The magnetic properties of the NdFeB materials prepared by the methods of Example 4 and Comparative Example 4 were tested, and the results are shown in Table 1. The remanence of Example 4 was 13.6 kGs and the coercivity was 21.32 kOe, while the remanence of Comparative Example 4 was 13.65 kGs and the coercivity was 20.55 kOe. It can be seen that the magnet of Example 4 has a higher coercivity and only slightly lower remanence.

[0044] Example 5: A high-performance RTB permanent magnet material is composed of a main phase alloy D, a grain boundary phase G, and a grain boundary phase F. The magnet composition is expressed as D by weight percentage. 100-u-v G u F v D represents the main phase alloy D, G represents the grain boundary phase alloy G, and F represents the grain boundary phase F, with u = 1 wt% and v = 0.5 wt%. The main phase alloy D has a composition of (PrNd). 29 Dy1Fe 余 Co1Cu 0.1 Ga 0.2 Zr 0.2 B 0.95 The grain boundary phase G is Pr 90 Al5Co5, wherein the auxiliary alloy phase F is Al2O3.

[0045] A method for preparing high-performance RTB permanent magnet materials includes the following steps: S1. Prepare the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain alloy sheet D. S2. The D alloy sheet is subjected to hydrogen pulverization and air jet milling to obtain D powder with an average particle size of 3.0 μm; S3. The powder prepared in S2 is subjected to magnetic field orientation molding and sintering heat treatment to obtain the RTB permanent magnet material; In S1, rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1450℃, and the alloy liquid is poured onto a water-cooled copper roller with a linear speed of 2.0 m / s to prepare rapid solidification sheets of the main phase alloy D with an average thickness of 0.25 mm. In S2, grain boundary phases G powder and F powder are added to the D powder after air jet milling and the three are mixed evenly. Specifically, after air jet milling, Pr, which accounts for 1% of the total mass fraction, is added to the D powder. 90Al5Co5 (grain boundary phase G) powder and Al2O3 (grain boundary phase F) powder (0.5% of total mass fraction) powder (98.5% of total mass fraction) powder are added to D powder and mixed evenly. The average particle size of the grain boundary phase G powder is 2 μm. The added grain boundary phase F powder consists of two Al2O3 powders with different average particle sizes: one is a coarse powder with an average particle size d1 of 2 μm, and the other is a fine powder with an average particle size d2 of 0.1 μm. The average particle size ratio between the two is d1 / d2 = 20. The masses m1 and m2 of the coarse powder and the fine powder satisfy the relationship: m1 / m2 = 0.2. The S3 method involves: magnetic powder being oriented using a magnetic field to form a blank, with a magnetic field strength of 1.8T and a forming density of 4.2 g / cm³. 3 The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. The blank is degassed by holding it at 500℃ and 900℃ for 3 hours and 3 hours respectively. Then, it is vacuum sintered at 1020~1100℃ for 5 hours to finally obtain the RTB permanent magnet material matrix. Furthermore, the RTB permanent magnet material is subjected to grain boundary diffusion treatment. The RTB permanent magnet material is processed into a magnet with a specification of 20×20×5M (M represents the magnetization direction). Tb accounting for 0.4% of the magnet mass fraction is coated on two 20×20 planes perpendicular to the magnetization direction. Then, the magnet is subjected to thermal diffusion treatment at 900℃ for 20h, followed by aging treatment at 500℃ for 5h. After cooling, the grain boundary diffusion treated RTB permanent magnet material is obtained.

[0046] As a comparative example 5, the composition was (PrNd). 29 Dy1Fe 余 Co1Cu 0.1 Ga 0.2 Zr 0.2 B 0.95 Airflow milling of main phase alloy D with Pr 90 The magnet was prepared by mixing Al5Co5 (grain boundary phase G) powder. The difference between this preparation method and that of Example 5 is that, after air jet milling, 1.5% of Pr (a specific component) was added. 90 Al5Co5 (grain boundary phase G) powder was added to air-jet milled powder containing D at a total mass fraction of 98.5%, and then magnets were prepared by pressing and sintering. The preparation method was the same as in Example 5 except that grain boundary phase F powder was not added. Specifically, the preparation method of Comparative Example 5 was as follows: S1, preparing the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain D alloy sheet; S2, subjecting the D alloy sheet to hydrogen annealing and air-jet milling to obtain D air-jet milled powder with an average particle size of 3.0 μm; S3, subjecting the powder prepared in S2 to magnetic field orientation pressing and sintering heat treatment to obtain the RTB permanent magnet material. In S1, rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1450℃, and the alloy liquid is poured onto a water-cooled copper roller with a linear speed of 2.0 m / s to prepare rapid solidification sheets of the main phase alloy D with an average thickness of 0.25 mm. In S2, this involves adding grain boundary phase G powder to the air-jet milled powder D and mixing them uniformly. Specifically, after air-jet milling, Pr, accounting for 1.5% of the total mass fraction, is added... 90 Al5Co5 (grain boundary phase G) powder was added to an air-jet milled powder containing 98.5% D by mass and the two were mixed evenly, wherein the average particle size of the grain boundary phase G powder was 2 μm. The S3 method involves: magnetic powder being oriented using a magnetic field to form a blank, with a magnetic field strength of 1.8T and a forming density of 4.2 g / cm³. 3 The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. The blank is degassed by holding it at 500℃ and 900℃ for 3 hours and 3 hours respectively. Then, it is vacuum sintered at 1020~1100℃ for 5 hours to finally obtain the RTB permanent magnet material matrix. Furthermore, the RTB permanent magnet material is subjected to grain boundary diffusion treatment. The RTB permanent magnet material is processed into a magnet with a specification of 20×20×5M (M represents the magnetization direction). Tb accounting for 0.4% of the magnet mass fraction is coated on two 20×20 planes perpendicular to the magnetization direction. Then, the magnet is subjected to thermal diffusion treatment at 900℃ for 20h, followed by aging treatment at 500℃ for 5h. After cooling, the grain boundary diffusion treated RTB permanent magnet material is obtained.

[0047] The comparison shows that Example 5 contains 0.5% less grain boundary phase Pr compared to Comparative Example 5. 90 Al5Co5 was used to prepare the matrix and diffuser of RTB permanent magnet materials, respectively, by replacing 0.5% Al2O3. The magnetic properties of the NdFeB material matrix and diffuser prepared by the methods of Example 5 and Comparative Example 5 were tested, and the results are shown in Table 1. The matrix remanence and coercivity of the magnet in Example 5 were slightly higher than those of the magnet in Comparative Example 5. After diffusion, the increase in coercivity of the magnet in Example 5 was more obvious.

[0048] As can be seen from the data of the examples and comparative examples in Examples 1-5, the magnet of the present invention, which is composed of main phase alloy D, non-magnetic grain boundary phase G and auxiliary alloy phase F, has good comprehensive magnetic properties such as remanence and intrinsic coercivity, and saves rare earth usage. The prepared magnet can be used as a grain boundary diffusion substrate, which can improve the diffusion penetration effect to reduce the amount of diffusion source used and save production costs.

[0049] Table 1 shows a comparison of the magnetic properties of Examples 1-5 and Comparative Examples 1-5. Table 1. Magnetic property tests of sintered NdFeB materials prepared by different methods. ; The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-performance RTB permanent magnet material, characterized in that, Composed of a main phase alloy D, grain boundary phase G, and grain boundary phase F, the magnet composition, expressed as D100-u-vGuFv by weight percentage, where 0 <u≤5 wt %,0<v≤2 wt%。 2. The high-performance RTB permanent magnet material as described in claim 1, characterized in that, The composition of the main phase alloy D is RxT100-xy-zMyBz, where R represents Nd or one or more rare earth elements including Y, T represents one or more of Co and Fe, M represents one or more of Al, Ag, Au, Bi, Cu, Ga, Nb, Mo, Sn, Ti, Zn, and Zr, B represents boron, and 27 ≤ x ≤ 31 wt%, 0 <y≤3wt %,0.85≤z≤1.0wt%; The composition of the grain boundary phase G is expressed as RaQ100-a, where R represents Nd or one or more rare earth elements including Y, Q represents one or more of Al, Ag, Au, Bi, Fe, Co, Cu, Ga, Sn, Ti, Zn, Zr, and Nb, and 0 ≤ a ≤ 100 wt%; The grain boundary phase F is composed of at least one oxide or fluoride formed from Al, Ca, Fe, Mg, Mo, Si, Ti, Zn, Zr, and rare earth element R.

3. A method for preparing a high-performance RTB permanent magnet material, characterized in that, The method for preparing the high-performance RTB permanent magnet material according to claim 2 includes the following steps: S1. Prepare the main phase alloy D by rapidly solidifying and melting the raw materials required for preparing the main phase alloy D to obtain alloy sheet D. S2. The D alloy sheet is subjected to hydrogen pulverization and air jet milling to obtain D powder with an average particle size of 2-3.5 μm; S3. The powder prepared in S2 is subjected to magnetic field orientation molding and sintering heat treatment to obtain RTB permanent magnet material.

4. The method for preparing a high-performance RTB permanent magnet material as described in claim 3, characterized in that, In step S1, when preparing the main phase alloy D using rapid solidification melting, the rapid solidification melting involves placing the main phase alloy raw materials into the crucible of a rapid solidification furnace and performing vacuum induction melting under argon protection. After the raw materials are fully melted, the temperature is maintained at 1350–1550°C, and the alloy liquid is poured onto a water-cooled copper roller with a linear velocity of 1.0–3.0 m / s to prepare main phase alloy rapid solidification sheets with an average thickness of 0.15–0.45 mm.

5. The method for preparing a high-performance RTB permanent magnet material as described in claim 3, characterized in that, The step of adding grain boundary phase G and F powder is also included in S2 or S3.

6. The method for preparing a high-performance RTB permanent magnet material as described in claim 3, characterized in that, Before hydrogen breakdown, at least one of the grain boundary phases G and F powders is added to the alloy sheet of D. After hydrogenation and before air jet milling, at least one of the grain boundary phases G and F is added to the hydrogenation powder of D.

7. The method for preparing a high-performance RTB permanent magnet material as described in claim 3, characterized in that, Before molding, at least one of the grain boundary phases G and F is added to the air-jet milled powder of D.

8. A method for preparing a high-performance RTB permanent magnet material as described in any one of claims 5-7, characterized in that, The average particle size of the grain boundary phase G powder is 1–5 μm. The grain boundary phase F consists of two powders with different particle sizes: one is a coarse powder with an average particle size d1 ranging from 1.5 to 5 μm, and the other is a fine powder with an average particle size d2 ranging from 0.02 to 0.5 μm. The ratio of their average particle sizes satisfies the relationship: d1 / d2 ≥ 10. The two particle size ranges of F powder can be the same F powder or different F powders. The weight of coarse particle powder m1 and the weight of fine particle powder m2 added satisfy the relationship: 0.1≤m2 / m1≤10.

9. The method for preparing a high-performance RTB permanent magnet material as described in claim 3, characterized in that, The detailed operation method of S3 is as follows: Magnetic powder is oriented using a magnetic field to form a blank with a magnetic field strength of 1.5T or higher and a forming density of 3.8–4.5 g / cm³. 3 The prepared blank is placed in a high vacuum sintering furnace, and the vacuum is evacuated to less than 0.5 Pa before heating. It is then degassed at 500℃~700℃ and 830~930℃ for 0.5~3h respectively. Then, it is vacuum sintered at 1020~1100℃ for 2~5h. Finally, it is aged heat treated at 800~930℃ and 450~650℃ for 2~9h respectively to obtain the RTB permanent magnet material.

10. The method for preparing a high-performance RTB permanent magnet material as described in claim 3, characterized in that, Following S3, the process further includes a step of grain boundary diffusion treatment on the RTB permanent magnet material. The grain boundary diffusion treatment includes: arranging a diffusion source on the surface of the magnet substrate obtained after processing, heating under vacuum conditions, performing grain boundary diffusion treatment at 800-950℃, holding for 3-48 hours, and performing aging treatment after diffusion at a temperature of 450-650℃. The diffusion source includes heavy rare earth elements, and the arrangement method of the diffusion source is selected from spraying, dipping, sputtering or screen printing.