Neodymium-iron-boron magnet material, method for producing same, and electronic device including same

Abstract

The application discloses a neodymium-iron-boron magnet material and a preparation method thereof, and an electronic device containing the same. The neodymium-iron-boron magnet material comprises R: 29.0-32.0 wt%, R is a rare earth element, and R comprises R1 and R2; R1 comprises Nd, and the content of Nd is greater than or equal to 27.5 wt%; R1 further comprises Dy and / or Tb; R1 can be optionally provided with Pr; R2 comprises Dy and / or Tb, and the content of R2 is 0.1-0.8 wt%; Cu: 0.16-0.40 wt%; Ga: 0.07-0.24 wt%; Al: less than or equal to 0.10 wt%; B: 0.96-1.10 wt%; Co: 3.0-5.5 wt%; M: 0.10-0.25 wt%, M is selected from at least one of Ti, Zr and Nb; Fe: 63.0-70.0 wt%; and the neodymium-iron-boron magnet material further comprises a new phase R w Fe 100‑w‑x‑y‑z Co x Cu y Ga z , w is 53.0-65.0; x is 2.00-3.50; y is 0.25-0.60; and z is 0.1-0.5. The application further optimizes the formula of the neodymium-iron-boron magnet material and a diffusion heat treatment process, so that the coercive force of the prepared neodymium-iron-boron magnet material is significantly improved, and meanwhile, the remanence and the remanence temperature coefficient are maintained.

Description

Technical Field

[0001] This invention relates to a neodymium iron boron magnet material, its preparation method, and electronic devices containing the same. Background Technology

[0002] Neodymium iron boron (NdFeB) permanent magnets are widely used in modern industries such as wind power generation, new energy vehicles, variable frequency air conditioners, and motors due to their excellent magnetic properties. With the trend towards miniaturization and high energy efficiency in motors, magnets are required to have high energy density, i.e., high remanence. Simultaneously, under harsh and variable temperature conditions, sintered NdFeB magnets are required to have good thermal stability, such as a low remanence temperature coefficient and high coercivity.

[0003] Currently, methods to improve the coercivity of NdFeB permanent magnets mainly include grain refinement processes, heavy rare earth grain boundary diffusion, and the design of magnetically insulating phases at grain boundaries. Additionally, replacing iron in the main phase with the transition element cobalt can alter the intrinsic properties of the main phase and reduce the temperature coefficient of remanence of the magnet. For example, the magnet with the composition Fe-10Co-8B-15Nd(at%) in patent US5645651A achieves a better temperature coefficient of remanence (-0.09% / ℃), but the addition of cobalt generates a soft magnetic phase at the grain boundaries, causing a decrease in the material's coercivity. Its magnetic properties are 12.0 kGs + 5.2 kOe, which still cannot meet the magnetic performance requirements of current motor products.

[0004] Therefore, it is an urgent technical problem to solve to develop neodymium iron boron magnet materials with high coercivity (Hcj), remanence (Br), and better remanence thermal stability by using cobalt addition combined with grain boundary diffusion technology. Summary of the Invention

[0005] This invention addresses the deficiency of low coercivity in existing NdFeB magnet materials when high cobalt content is added, by providing a NdFeB magnet material, its preparation method, and an electronic device containing the same. This invention further optimizes the formulation and diffusion heat treatment process of the NdFeB magnet material, resulting in a significantly improved coercivity while maintaining optimal remanence and temperature coefficient of remanence.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution:

[0007] This invention provides a neodymium iron boron magnet material, which comprises the following components in terms of mass content:

[0008] R: 29.0–32.0 wt%, wherein R is a rare earth element, and R includes R1 and R2; wherein R1 includes Nd, wherein the Nd content is ≥27.5 wt%; wherein R1 also includes Dy and / or Tb; wherein Pr is an optional element of R1; wherein R2 includes Dy and / or Tb, and the content of R2 is 0.1–0.8 wt%;

[0009] Cu: 0.16–0.40 wt%;

[0010] Ga: 0.07–0.24 wt%;

[0011] Al: ≤0.10wt%;

[0012] B: 0.96–1.10 wt%;

[0013] Co: 3.0–5.5 wt%;

[0014] M: 0.10–0.25 wt%, M is selected from at least one of Ti, Zr and Nb;

[0015] Fe: 63.0–70.0 wt%;

[0016] wt% is the percentage of the mass of each component to the total mass of the neodymium iron boron magnet material;

[0017] The two-grain boundaries of the neodymium iron boron magnet material also include a new phase, the chemical composition of which is: R w Fe 100-w-x-y-z Co x Cu y Ga z Where w is 53.0–65.0; x is 2.00–3.50; y is 0.25–0.60; and z is 0.1–0.5.

[0018] In this invention, R1 is preferably "Nd and Dy" or "Nd and Tb".

[0019] In this invention, the content of R is preferably 29.5 to 31.5 wt%, for example 29.6 wt%, 29.8 wt%, 29.9 wt%, 30.0 wt%, 30.2 wt%, 30.5 wt%, 30.8 wt%, 31.1 wt%, or 31.5 wt%, and more preferably 29.8 to 30.8 wt%.

[0020] In this invention, when R1 includes Nd, the content of Nd is preferably 28.2 to 30.0 wt%, for example 28.3 wt%, 28.7 wt%, 29.0 wt%, 29.1 wt%, 29.5 wt%, 29.9 wt%, or 30.0 wt%, more preferably 28.5 to 29.5 wt%.

[0021] In this invention, when R1 includes Dy or Tb, the content of Dy or Tb is preferably ≤1.5wt%, but not 0, for example 0.4wt%, 0.6wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.3wt%, or 1.5wt%, more preferably 0.3 to 1.2wt%.

[0022] In this invention, when R1 includes Pr, the content of Pr is preferably 0.0 to 2.00 wt%, for example 0.5 wt%, 1.0 wt%, 1.5 wt%, or 2.0 wt%, more preferably 0.0 to 1.0 wt%.

[0023] In this invention, the content of R2 is preferably 0.2 to 0.7 wt%, for example 0.2 wt%, 0.4 wt%, 0.42 wt%, 0.43 wt%, 0.48 wt%, or 0.7 wt%, and more preferably 0.2 to 0.5 wt%.

[0024] In this invention, the content of Co is preferably 3.20-5.20 wt%, for example 3.30 wt%, 3.60 wt%, 3.62 wt%, 3.90 wt%, 4.16 wt%, 4.18 wt%, 4.20 wt%, 4.21 wt%, 4.25 wt%, 4.50 wt%, 4.80 wt%, 4.85 wt%, or 5.10 wt%, and more preferably 3.60-4.80 wt%.

[0025] In this invention, the Cu content is preferably 0.18 to 0.35 wt%, for example 0.18 wt%, 0.20 wt%, 0.25 wt%, 0.26 wt%, 0.29 wt%, 0.30 wt%, 0.31 wt%, or 0.35 wt%, and more preferably 0.25 to 0.35 wt%.

[0026] In this invention, the Cu is preferably added during smelting and / or during grain boundary diffusion.

[0027] When Cu is added during grain boundary diffusion, the Cu content is preferably 0.03 to 0.10 wt%, for example, 0.05 wt%.

[0028] In this invention, the content of Ga is preferably 0.10 to 0.22 wt%, for example 0.10 wt%, 0.13 wt%, 0.16 wt%, 0.17 wt%, 0.18 wt%, 0.19 wt%, 0.20 wt%, or 0.22 wt%, and more preferably 0.15 to 0.20 wt%.

[0029] In this invention, the content of M is preferably 0.17 to 0.23 wt%, for example 0.18 wt%, 0.19 wt%, 0.20 wt%, 0.21 wt%, or 0.22 wt%.

[0030] In this invention, the content of B is preferably 0.97 to 1.05 wt%, for example 0.98 wt%, 0.99 wt%, 1.00 wt%, 1.01 wt%, 1.02 wt%, or 1.04 wt%, and more preferably 0.98 to 1.02 wt%.

[0031] In this invention, the content of Al is preferably ≤0.08wt%, but not 0, and more preferably 0.03-0.07wt%, for example 0.04wt%, 0.05wt%, 0.06wt%, or 0.07wt%.

[0032] In this invention, the Fe content is preferably 63.0–69.5 wt%, for example 63.00 wt%, 63.10 wt%, 63.68 wt%, 63.78 wt%, 63.91 wt%, 63.92 wt%, 64.12 wt%, 64.20 wt%, 64.75 wt%, 67.5%, 68.0%, 68.5%, 69.0%, or 69.5%, and more preferably 63.0–65.0 wt%.

[0033] In this invention, preferably, the neodymium iron boron magnet material comprises Nd2Fe l4 B grains and their shells, adjacent to the Nd2Fe l4 The B grains contain two grain boundaries and grain boundary triangular regions; among them, the heavy rare earth elements in R1 are distributed in Nd2Fe. l4 B grains and R2 are mainly distributed in the shell, the two-grain boundary, and the grain boundary triangle.

[0034] In this invention, "the heavy rare earth elements in R1 are mainly distributed in Nd2Fe". l4 "B grains" can be understood as the heavy rare earth elements in R1, caused by conventional melting and sintering processes in this field, being mainly distributed (generally referring to above 95 wt%) in Nd2Fe. l4 B grains, with a small amount distributed at grain boundaries. "R2 is mainly distributed in the shell" can be understood as R2 caused by conventional grain boundary diffusion processes in the art being mainly distributed (generally referring to 95 wt% or more) in Nd2Fe.l4 The shell and grain boundaries (two-grain grain boundaries and grain boundary triangular regions) of B grains, a small portion of which also diffuses into Nd2Fe. l4 In B grains, for example in Nd2Fe l4 The outer edge of the B grain.

[0035] In this invention, the grain boundary triangle generally refers to the area where three or more grain boundaries intersect, containing boron-rich phases, rare earth-rich phases, rare earth oxides, rare earth carbides, and voids. The area ratio of the grain boundary triangle is calculated as the ratio of its area to the total area of ​​the grains and grain boundaries. Subtracting the area ratio of the grain boundary triangle from the area ratio of the grain boundaries gives the area ratio of the two-grain grain boundary.

[0036] Rare earth oxides and rare earth carbides are mainly produced by introducing C and O elements during the preparation process. Due to the high rare earth content at grain boundaries, C and O are typically distributed more extensively within these boundaries in the magnet material, thus existing as rare earth carbides and rare earth oxides, respectively. It should be noted that the C and O elements are introduced in a conventional manner, generally as impurities or by the atmosphere. Specifically, for example, additives are introduced during air jet milling or pressing; these additives are removed during sintering through heating, but a small amount of C and O elements inevitably remains. Similarly, a small amount of O elements is inevitably introduced during the preparation process due to the atmosphere. In this invention, the final NdFeB magnet material product, after testing, has C and O contents of only 1000 and 1200 ppm, respectively, which fall within the conventionally acceptable impurity range in the art.

[0037] In this invention, the neodymium iron boron magnet material may also include one or more of the impurities C, N and O.

[0038] Wherein, when the neodymium iron boron magnet material includes C, the content of C can be less than 1500 μg / g, for example 300 to 1500 μg / g, or even 400 to 1000 μg / g, where μg / g is the mass ratio of the mass of C to the mass of the neodymium iron boron magnet material.

[0039] Wherein, when the neodymium iron boron magnet material includes N, the content of N can be less than 1000 μg / g, for example 100 to 1000 μg / g, or even 200 to 600 μg / g, where μg / g is the mass ratio of the mass of N to the mass of the neodymium iron boron magnet material.

[0040] When the neodymium iron boron magnet material includes O, the content of O can be less than 1500 μg / g, for example 300-1500 μg / g, or even 400-1200 μg / g, where μg / g is the mass ratio of the mass of N to the mass of the neodymium iron boron magnet material.

[0041] In this invention, the chemical composition is R w Fe 100-w-x-y-z Co x Cu y Ga z The area of ​​the new phase in the two-grain boundary is preferably 2.0% to 3.2%, for example 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, or 3.2%, more preferably 2.2% to 3.0%. The inventors discovered that the R... w Fe 100-w-x-y-z Co x Cu y Ga z The formation of the phase in the grain boundary effectively reduces the proportion of the NdCo2 soft magnetic phase in the grain boundary, enhances the demagnetizing coupling ability of the grain boundary phase, lowers the dissolution temperature of the grain boundary phase, improves the distribution of the grain boundary phase, and enables the material to obtain better coercivity. At the same time, it also allows more cobalt elements to be distributed in the main phase, improves the intrinsic magnetic properties of the main phase, and reduces the temperature coefficient of remanence.

[0042] In this invention, the remanence temperature coefficient at 20-120℃ is preferably -0.070 to -0.010% / ℃, for example -0.110% / ℃, -0.108% / ℃, -0.103% / ℃, -0.075% / ℃, -0.080% / ℃, -0.085% / ℃, -0.090% / ℃, -0.093% / ℃, -0.095% / ℃, -0.010% / ℃, or more preferably -0.075 to -0.095% / ℃.

[0043] The formula for calculating the remanence temperature coefficient is: (Br at high temperature - Br at room temperature) / (Br at room temperature (high temperature - room temperature)) × 100%.

[0044] In a preferred embodiment of the present invention, the NdFeB magnet material comprises the following components by mass: 8.2 wt% Nd, 1.3 wt% Dy, 0.43 wt% Tb, 4.21 wt% Co, 0.31 wt% Cu, 0.18 wt% Ga, 0.20 wt% Ti, 0.99 wt% B, 0.06 wt% Al, and 64.12 wt% Fe. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the percentage of the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd2Fe. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 55.15 Fe 41.28 Co 2.74 Cu 0.47 Ga 0.36R is one or more of Nd, Dy and Tb, and the area ratio of the new phase in the two-grain boundary is 2.36%.

[0045] In a preferred embodiment of the present invention, the NdFeB magnet material comprises the following components by mass: Nd2 9.0 wt%, Dy 1.0 wt%, Tb 0.42 wt%, Co 4.18 wt%, Cu 0.29 wt%, Ga 0.19 wt%, Ti 0.18 wt%, B 0.99 wt%, Al 0.07 wt%, and Fe 63.68 wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd2Fe. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 56.33 Fe 40.16 Co 2.68 Cu 0.45 Ga 0.38 R is one or more of Nd, Dy and Tb, and the area ratio of the new phase in the two-grain boundary is 2.58%.

[0046] In a preferred embodiment of the present invention, the NdFeB magnet material comprises the following components by mass: Nd 29.9wt%, Dy 0.6wt%, Tb 0.43wt%, Co 4.25wt%, Cu 0.30wt%, Ga 0.18wt%, Ti 0.19wt%, B 1.00wt%, Al 0.05wt%, and Fe 63.1wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd2Fe. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 57.11 Fe 39.27 Co 2.82 Cu 0.45 Ga 0.35 R is one or more of Nd, Dy and Tb, and the area ratio of the new phase in the two-grain boundary is 2.72%.

[0047] In a preferred embodiment of the present invention, the NdFeB magnet material comprises the following components by mass: Nd 29.0 wt%, Dy 1.0 wt%, Tb 0.43 wt%, Co 3.62 wt%, Cu 0.30 wt%, Ga 0.20 wt%, Ti 0.21 wt%, B 0.99 wt%, Al 0.05 wt%, and Fe 64.2 wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the percentage of the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd2Fe. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 56.13 Fe 40.88 Co 2.18 Cu 0.45 Ga 0.36 R is one or more of Nd, Dy and Tb, and the area ratio of the new phase in the two-grain boundary is 2.25%.

[0048] In a preferred embodiment of the present invention, the NdFeB magnet material comprises the following components by mass: Nd2 9.0 wt%, Dy 1.0 wt%, Tb 0.43 wt%, Co 4.85 wt%, Cu 0.31 wt%, Ga 0.17 wt%, Ti 0.20 wt%, B 0.99 wt%, Al 0.05 wt%, and Fe 63.00 wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the percentage of the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd2Fe. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 56.18 Fe 39.91 Co 3.12 Cu 0.46 Ga 0.33 R is one or more of Nd, Dy and Tb, and the area ratio of the new phase in the two-grain boundary is 2.89%.

[0049] In a preferred embodiment of the present invention, the NdFeB magnet material comprises the following components by mass: Nd2 9.0 wt%, Dy 0.48 wt%, Tb 0.80 wt%, Co 4.18 wt%, Cu 0.20 wt%, Ga 0.18 wt%, Ti 0.19 wt%, B 1.01 wt%, Al 0.04 wt%, and Fe 63.92 wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the percentage of the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd2Fe. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 55.84 Fe 40.88 Co 2.65 Cu 0.32 Ga 0.31 R is one or more of Nd, Dy and Tb, and the area ratio of the new phase in the two-grain boundary is 2.38%.

[0050] In a preferred embodiment of the present invention, the NdFeB magnet material comprises the following components by mass: Nd2 9.0 wt%, Dy 1.00 wt%, Tb 0.43 wt%, Co 4.16 wt%, Cu 0.18 wt%, Ga 0.20 wt%, Ti 0.21 wt%, B 0.99 wt%, Al 0.05 wt%, and Fe 63.78 wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the percentage of the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd2Fe. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 56.49 Fe 40.27 Co 2.59 Cu 0.32 Ga 0.33 R is one or more of Nd, Dy and Tb, and the area ratio of the new phase in the two-grain boundary is 2.42%.

[0051] In a preferred embodiment of the present invention, the NdFeB magnet material comprises the following components by mass: Nd2 9.0 wt%, Dy 1.00 wt%, Tb 0.42 wt%, Co 4.16 wt%, Cu 0.31 wt%, Ga 0.10 wt%, Ti 0.21 wt%, B 0.99 wt%, Al 0.06 wt%, and Fe 63.75 wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the percentage of the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd2Fe. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 56.37 Fe 40.23 Co 2.71 Cu 0.52 Ga 0.17 R is one or more of Nd, Dy and Tb, and the area ratio of the new phase in the two-grain boundary is 2.34%.

[0052] In a preferred embodiment of the present invention, the NdFeB magnet material comprises the following components by mass: Nd2 9.0 wt%, Dy 1.00 wt%, Tb 0.20 wt%, Co 4.18 wt%, Cu 0.26 wt%, Ga 0.20 wt%, Ti 0.20 wt%, B 0.99 wt%, Al 0.06 wt%, and Fe 63.91 wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the percentage of the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd2Fe. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 55.47 Fe 41.16 Co 2.77 Cu 0.25 Ga 0.35 R is one or more of Nd, Dy and Tb, and the area ratio of the new phase in the two-grain boundary is 2.45%.

[0053] The present invention also provides a method for preparing neodymium iron boron magnet material, which involves melting, pulverizing, molding and sintering the elements other than R2 in the raw material composition to obtain a sintered body, and then diffusing the mixture of the sintered body and R2 through grain boundaries.

[0054] The grain boundary diffusion treatment employs a three-stage heating and cooling process: the first stage is heated to 400-500°C, the second stage is heated to 930-990°C, and the third stage is heated to 30-60°C lower than the second stage.

[0055] The raw material composition comprises, by weight percentage, the following components:

[0056] R: 29.0–32.0 wt%, wherein R is a rare earth element, and R includes R1 and R2; wherein R1 includes Nd, wherein the Nd content is ≥27.5 wt%; wherein R1 also includes Dy and / or Tb; wherein Pr is an optional element of R1; wherein R2 includes Dy and / or Tb, and the content of R2 is 0.1–0.8 wt%;

[0057] Cu: 0.16–0.40 wt%;

[0058] Ga: 0.07–0.24 wt%;

[0059] Al: ≤0.10wt%;

[0060] B: 0.96–1.10 wt%;

[0061] Co: 3.0–5.5 wt%;

[0062] M: 0.10–0.25 wt%, M is selected from at least one of Ti, Zr and Nb;

[0063] Fe: 63.0–70.0 wt%;

[0064] wt% is the percentage of the mass of each component to the total mass of the raw material composition;

[0065] R1 element is added during the smelting step, and R2 element is added during the grain boundary diffusion step.

[0066] In this invention, the smelting operation and conditions can be conventional smelting processes in the art. Generally, the elements other than R2 in the raw material composition of the NdFeB magnet material are smelted and cast using ingot casting and rapid solidification processes to obtain alloy sheets.

[0067] Those skilled in the art will know that rare earth elements are usually lost during the smelting and sintering processes. In order to ensure the quality of the final product, 0 to 0.3 wt% of rare earth elements (usually Nd) are generally added to the raw material composition during the smelting process. wt% is the mass percentage of the added rare earth element relative to the total content of the raw material composition. In addition, the content of this added rare earth element is not included in the scope of the raw material composition.

[0068] In this invention, the melting temperature can be 1400-1600°C, preferably 1450-1550°C, for example 1520°C.

[0069] In this invention, the melting environment can be a vacuum of 0.05 Pa.

[0070] In this invention, the smelting equipment is generally a medium-frequency vacuum smelting furnace, such as a medium-frequency vacuum induction rapid solidification belt spinning furnace.

[0071] In this invention, the powdering operation and conditions can be conventional powdering processes in the art, generally including hydrogen crushing and / or air jet milling.

[0072] The hydrogen-based powdering process generally includes hydrogen absorption, dehydrogenation, and cooling.

[0073] The temperature for hydrogen absorption is generally 20–200°C, for example, 25°C. The pressure for hydrogen absorption is generally 50–600 kPa, preferably 60–300 kPa, for example, 90 kPa.

[0074] The dehydrogenation temperature is generally 400–650°C, and preferably 500–550°C.

[0075] The pressure of the air jet mill is generally 0.1 to 2 MPa, preferably 0.5 to 0.7 MPa, for example 0.6 MPa.

[0076] The airflow in the air-jet mill can be an inert atmosphere, such as nitrogen.

[0077] The time for air jet milling can be 2 to 4 hours, for example, 3 hours.

[0078] In this invention, the molding operation and conditions can be conventional molding processes in the art, such as magnetic field molding. The magnetic field strength in the magnetic field molding method is generally above 1.5T.

[0079] In this invention, the sintering operation and conditions can be conventional sintering processes in the art, such as vacuum sintering and / or inert atmosphere sintering.

[0080] Both the vacuum sintering process and the inert atmosphere sintering process are conventional operations in the field. When using the inert atmosphere sintering process, the initial stage of sintering can be carried out at a vacuum level below 5 × 10⁻⁶. -1 The process is carried out under the condition of Pa. The inert atmosphere can be a conventional atmosphere containing an inert gas, such as helium or argon.

[0081] In this invention, the sintering temperature can be 1000-1200℃, preferably 1050-1100℃, for example 1080℃.

[0082] In this invention, the sintering time can be 0.5 to 10 hours, preferably 3 to 6 hours.

[0083] As those skilled in the art will know, the coating operation of R2 is generally included before the grain boundary diffusion described herein.

[0084] R2 is typically coated in the form of a low-melting-point alloy or oxide, such as an alloy powder or oxide of Dy or Tb.

[0085] In this invention, the grain boundary diffusion treatment employs a three-stage heating and cooling process. Preferably, the first stage involves heating to 400–500°C and holding at that temperature for 1–6 hours; the second stage involves heating to 930–990°C and holding at that temperature for 10–30 hours; and the third stage involves cooling to 840–930°C and holding at that temperature for 3–10 hours. The heating rate for each stage is 3–15°C / min, and the cooling rate is 5–30°C / min.

[0086] This invention employs a three-stage heating and cooling diffusion heat treatment method. The first holding stage aims to remove residual moisture and organic matter from the diffusion source, substrate surface, and interior. The second holding stage aims to effectively concentrate heavy rare earth elements in the diffusion source within a narrow area near the grain boundaries, thereby increasing Hcj while reducing remanence loss. When the heat treatment temperature is below 930℃, the high cobalt content easily forms a soft magnetic NdCo2 phase at the grain boundaries, failing to provide magnetic decoupling and leading to a decrease in material coercivity. However, when the temperature is above 990℃, the heavy rare earth elements, after entering the grain boundary phase, continue to diffuse into the main Nd2Fe phase. 14 B, thereby destroying the crystal structure, leading to a decrease in the remanence and coercivity of the magnet. Therefore, this invention controls the secondary heat treatment temperature within the range of 930-990℃ to obtain a high-performance sintered NdFeB magnet; the temperature of the third cooling stage is set slightly lower than that of the second stage by 30-60℃, in order to produce a slight temperature drop, allowing the diffusion source to flow more fully and thus improving the diffusion effect.

[0087] In the first stage of the three-stage heating and cooling heat treatment, the temperature is raised to 400-500℃, for example, 430℃, 450℃, 460℃ or 490℃, preferably 420-480℃.

[0088] The first stage of the three-stage heating and cooling heat treatment involves holding the temperature for 1 to 6 hours, for example, 2 hours, 3 hours or 4 hours, preferably 2 to 5 hours.

[0089] In the second stage of the three-stage heating and cooling heat treatment, the temperature is raised to 930-990℃, for example, 940℃, 955℃, 960℃ or 980℃, preferably 940-980℃.

[0090] The second stage of the three-stage heating and cooling heat treatment involves holding the temperature for 10 to 30 hours, for example, 12 hours, 16 hours, 20 hours, 24 hours or 28 hours, preferably 15 to 25 hours.

[0091] In the third stage of the three-stage heating and cooling heat treatment, the temperature is lowered to 840-930℃, for example, 850℃, 880℃, 900℃ or 910℃, preferably 860-920℃.

[0092] The third stage of the three-stage heating and cooling heat treatment involves holding the temperature for 3 to 10 hours, for example, 5 hours, 6 hours, 7 hours or 9 hours, preferably 4 to 9 hours.

[0093] The heating rate of each stage of the three-stage heating and cooling heat treatment is 3 to 15 °C / min, for example, 6 °C / min, 8 °C / min, or 10 °C / min.

[0094] The cooling rate of each stage of the three-stage heating and cooling heat treatment is 5 to 30°C / min, for example, 6°C / min, 10°C / min, 12°C / min or 15°C / min.

[0095] In this invention, after the grain boundary diffusion, a low-temperature tempering treatment can be performed in accordance with conventional practices in the art.

[0096] The temperature of the low-temperature tempering treatment is generally 460-560℃, for example, 500℃.

[0097] The low-temperature tempering time can generally be 1 to 5 hours, for example, 3 hours.

[0098] In this invention, R1 is preferably "Nd and Dy" or "Nd and Tb".

[0099] In this invention, the content of R is preferably 29.5 to 31.5 wt%, for example 29.6 wt%, 29.8 wt%, 29.9 wt%, 30.0 wt%, 30.2 wt%, 30.5 wt%, 30.8 wt%, 31.1 wt%, or 31.5 wt%, and more preferably 29.8 to 30.8 wt%.

[0100] In this invention, when R1 includes Nd, the content of Nd is preferably 28.2 to 30.0 wt%, for example 28.3 wt%, 28.7 wt%, 29.0 wt%, 29.1 wt%, 29.5 wt%, 29.9 wt%, or 30.0 wt%, more preferably 28.5 to 29.5 wt%.

[0101] In this invention, when R1 includes Dy or Tb, the content of Dy or Tb is preferably ≤1.5wt%, but not 0, for example 0.4wt%, 0.6wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.3wt%, or 1.5wt%, more preferably 0.3 to 1.2wt%.

[0102] In this invention, when R1 includes Pr, the content of Pr is preferably 0.0 to 2.00 wt%, for example 0.5 wt%, 1.0 wt%, 1.5 wt%, or 2.0 wt%, more preferably 0.0 to 1.0 wt%.

[0103] In this invention, the content of R2 is preferably 0.2 to 0.7 wt%, for example 0.2 wt%, 0.4 wt%, 0.42 wt%, 0.43 wt%, 0.48 wt%, or 0.7 wt%, and more preferably 0.2 to 0.5 wt%.

[0104] In this invention, the content of Co is preferably 3.20-5.20 wt%, for example 3.30 wt%, 3.60 wt%, 3.62 wt%, 3.90 wt%, 4.16 wt%, 4.18 wt%, 4.20 wt%, 4.21 wt%, 4.25 wt%, 4.50 wt%, 4.80 wt%, 4.85 wt%, or 5.10 wt%, and more preferably 3.60-4.80 wt%.

[0105] In this invention, the Cu content is preferably 0.18 to 0.35 wt%, for example 0.18 wt%, 0.20 wt%, 0.25 wt%, 0.26 wt%, 0.29 wt%, 0.30 wt%, 0.31 wt%, or 0.35 wt%, and more preferably 0.25 to 0.35 wt%.

[0106] In this invention, the Cu is preferably added during smelting and / or during grain boundary diffusion.

[0107] When Cu is added during grain boundary diffusion, the Cu content is preferably 0.03 to 0.10 wt%, for example, 0.05 wt%.

[0108] In this invention, the content of Ga is preferably 0.10 to 0.22 wt%, for example 0.10 wt%, 0.13 wt%, 0.16 wt%, 0.17 wt%, 0.18 wt%, 0.19 wt%, 0.20 wt%, or 0.22 wt%, and more preferably 0.15 to 0.20 wt%.

[0109] In this invention, the content of M is preferably 0.17 to 0.23 wt%, for example 0.18 wt%, 0.19 wt%, 0.20 wt%, 0.21 wt%, or 0.22 wt%.

[0110] In this invention, the content of B is preferably 0.97 to 1.05 wt%, for example 0.98 wt%, 0.99 wt%, 1.00 wt%, 1.01 wt%, 1.02 wt%, or 1.04 wt%, and more preferably 0.98 to 1.02 wt%.

[0111] In this invention, the content of Al is preferably ≤0.08wt%, but not 0, and more preferably 0.03-0.07wt%, for example 0.04wt%, 0.05wt%, 0.06wt%, or 0.07wt%.

[0112] In this invention, the Fe content is preferably 63.0–69.5 wt%, for example 63.00 wt%, 63.10 wt%, 63.68 wt%, 63.78 wt%, 63.91 wt%, 63.92 wt%, 64.12 wt%, 64.20 wt%, 64.75 wt%, 67.5%, 68.0%, 68.5%, 69.0%, or 69.5%, and more preferably 63.0–65.0 wt%.

[0113] The present invention also provides a neodymium iron boron magnet material, which is prepared by the above-described preparation method.

[0114] The present invention also provides an electronic device comprising the above-described neodymium iron boron magnet material.

[0115] The present invention also provides an application of the neodymium iron boron magnet material as described above in the preparation of magnetic steel.

[0116] In this invention, the magnet is preferably a 52UH or 54UH magnet.

[0117] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0118] The reagents and raw materials used in this invention are all commercially available.

[0119] The positive and progressive effects of this invention are as follows:

[0120] In this invention, by combining specific amounts of various elements, and under the premise of adding a high amount of cobalt and not containing a large amount of heavy rare earth elements, a three-stage heating and cooling diffusion heat treatment process is used to generate a new phase in the two-grain boundary, which enhances the magnetic decoupling effect of the grain boundary, overcomes the defect of reduced coercivity caused by the addition of a high amount of cobalt, and obtains better remanence, coercivity, and corresponding remanence temperature stability.

[0121] The remanence of the neodymium iron boron magnet material prepared by this invention can reach 14.44 to 14.58 kGs, the coercivity can reach 25.35 to 27.60 kOe, and the Br temperature coefficient α at 20 to 120℃ can reach -0.080 to -0.093% / ℃. Attached Figure Description

[0122] Figure 1 This is a microstructure diagram of the EPMA of the NdFeB magnet material prepared in Example 1. The point indicated by arrow 1 in the diagram represents the R-type matrix contained in the grain boundary between two grains. w Fe 100-w-x-y-z Co x Cu y Ga z The new phase is indicated by arrow 2 at the grain boundary triangle region, and arrow 3 at the Nd2Fe phase. l4 B is the main phase. Detailed Implementation

[0123] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0124] Example 1

[0125] Preparation method of neodymium iron boron magnet material:

[0126] (1) Melting and casting process: According to the formula in Table 1, the prepared raw materials except R2 are placed in the crucible of alumina and vacuum melted in a medium frequency vacuum melting furnace at a vacuum of 0.05 Pa and 1520℃. Argon gas is then introduced and the rapid solidification casting method is used to obtain alloy castings (thickness of 0.29 mm). The casting temperature is 1440℃.

[0127] (2) Hydrogen-crushing powder production process: The hydrogen-crushing furnace containing the rapidly cooled alloy is evacuated at room temperature. Then, hydrogen gas with a purity of 99.9% is introduced into the hydrogen-crushing furnace, maintaining a hydrogen pressure of 90 kPa. After sufficient hydrogen absorption, the temperature is increased while evacuating the furnace. After sufficient dehydrogenation, the furnace is cooled and the hydrogen-crushed powder is taken out. The hydrogen absorption temperature is room temperature, and the dehydrogenation temperature is 550℃.

[0128] (3) Airflow milling process: Under nitrogen atmosphere, the powder after hydrogen pulverization is subjected to airflow milling for 3 hours under the condition of 0.6 MPa pressure in the pulverizing chamber to obtain fine powder.

[0129] (4) Molding process: The powder after passing through the airflow membrane is molded in a magnetic field with a strength of 1.5T or higher.

[0130] (5) Sintering process: Each molded body is moved to a sintering furnace for sintering. Sintering is carried out at 1080℃ for 6 hours under a vacuum of less than 0.5 Pa to obtain the sintered body.

[0131] (6) Grain boundary diffusion process: After cleaning the surface of the sintered body, R2 (e.g., alloy powder or oxide of Tb, alloy powder or oxide of Dy) is coated on the surface of the sintered body. Then, a three-stage heating and cooling heat treatment is performed. The sintered body is heated to 450℃ in the first stage and held at that temperature for 3 hours. In the second stage, the temperature is raised to 955℃ and held at that temperature for 20 hours. In the third stage, the temperature is lowered to 900℃ and held at that temperature for 6 hours. The heating rate for each stage is 8℃ / min and the cooling rate is 12℃ / min. After cooling to room temperature, it is then tempered at 500℃ for 3 hours.

[0132] Examples 2-9

[0133] Examples 2-9 were prepared according to the formula in Table 1 below, and the parameters in the preparation method were the same as in Example 1.

[0134] The neodymium iron boron magnet materials prepared in Examples 1-9 all contain Nd2Fe. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B grains contain two grain boundaries and grain boundary triangular regions; among them, the heavy rare earth elements in R1 are distributed in Nd2Fe. l4 B grains and R2 are mainly distributed in the shell, the two-grain boundary, and the grain boundary triangle.

[0135] Comparative Examples 1-4

[0136] Comparative Examples 1 to 4 were prepared according to the formulations in Table 1 below, and the parameters in the preparation methods were the same as those in Example 1.

[0137] Table 1. Components and their contents (wt%)

[0138]

[0139] Note: " / " indicates that the element is not present. wt% is the mass percentage.

[0140] Example 1

[0141] The neodymium iron boron magnet materials in Examples 1-9 and Comparative Examples 1-4 were subjected to the following tests:

[0142] 1. Magnetic Performance Testing: The sintered magnets were tested using a PFM-14 magnetic performance measuring instrument from Hirs, UK. The tested magnetic properties included remanence at 20℃ and 120℃, coercivity at 20℃ and 120℃, and the corresponding temperature coefficient of remanence. The formula for calculating the temperature coefficient of remanence is: (Br... 高温 -Br 常温 ) / (Br 常温 (High temperature - normal temperature) × 100%, the test results are shown in Table 2 below.

[0143] 2. FE-EPMA Testing: The perpendicular orientation surfaces of the NdFeB magnet material are polished and tested using a field emission electron probe microanalyzer (FE-EPMA) (JEOL, 8530F). Figure 1 As shown, the distribution of elements in the grain boundary phase of the NdFeB magnet material was determined by FE-EPMA surface scanning, and then the composition of the new phase was determined by FE-EPMA single-point quantitative analysis. The area ratio of the new phase in the two-grain grain boundary was calculated.

[0144] Table 2

[0145]

[0146] Note: "×" indicates that the two-grained grain boundary phase does not contain chemical composition R. w Fe 100-w-x-y-z Co x Cu y Ga z A new phase.

[0147] As can be seen from the data in the table above, this invention generates a new phase R in the grain boundary between two grains by combining specific amounts of Co, Ga, Cu, rare earth elements, etc. w Fe 100-w-x-y-z Co x Cu y Ga z This improves the fluidity of grain boundaries, resulting in neodymium iron boron magnet materials with better remanence and coercivity. At the same time, it concentrates cobalt in the main phase, significantly reducing the remanence temperature coefficient compared to existing products.

Claims

1. A neodymium iron boron magnet material, characterized in that, It includes the following components in terms of mass content: R: 29.0~32.0 wt%, where R is a rare earth element, and R includes R1 and R2; R1 includes Nd, wherein the Nd content is ≥27.5 wt%; R1 also includes Dy and / or Tb; Pr is an optional element of R1; R2 includes Dy and / or Tb, and the content of R2 is 0.1~0.8 wt%. Cu: 0.16~0.40wt% Ga: 0.07~0.24wt% Al: ≤0.10wt% B: 0.96~1.10wt% Co: 3.0~5.5wt% M: 0.10~0.25wt%, M is selected from at least one of Ti, Zr and Nb; Fe: 63.0~65.0 wt% wt% is the percentage of the mass of each component to the total mass of the neodymium iron boron magnet material; The neodymium iron boron magnet material includes Nd2Fe l4 B grains and their shells, adjacent to the Nd2Fe l4 The B grains contain two grain boundaries and grain boundary triangular regions; among them, the heavy rare earth elements in R1 are distributed in Nd2Fe. l4 B grains, R2 are mainly distributed in the shell, the two-grain boundary and the grain boundary triangle; The two-grain boundaries of the neodymium iron boron magnet material also include a new phase, the chemical composition of which is: R w Fe 100-w-x-y-z Co x Cu y Ga z Where w is 53.0~65.0; x is 2.00~3.50; y is 0.25~0.60; and z is 0.1~0.

5.

2. The neodymium iron boron magnet material as described in claim 1, characterized in that, R1 is either "Nd and Dy" or "Nd and Tb"; And / or, the content of R is 29.5~31.5 wt%; And / or, when R1 includes Nd, the content of Nd is 28.2~30.0 wt%; And / or, when R1 includes Dy or Tb, the content of Dy or Tb is ≤1.5wt% but not 0; And / or, when R1 includes Pr, the content of Pr is 0.0~2.00 wt%; And / or, the content of R2 is 0.2~0.7wt%; And / or, the content of Co is 3.20~5.20 wt%; And / or, the Cu content is 0.18~0.35wt%; And / or, the Ga content is 0.10~0.22wt%; And / or, the content of M is 0.17~0.23 wt%; And / or, the content of B is 0.97~1.05 wt%; And / or, the content of Al is ≤0.08wt%, but not 0; And / or, the chemical composition is R w Fe 100-w-x-y-z Co x Cu y Ga z The area ratio of the new phase in the two-grain boundary is 2.0~3.2%.

3. The neodymium iron boron magnet material as described in claim 2, characterized in that, The content of R is 29.6 wt%, 29.8 wt%, 29.9 wt%, 30.0 wt%, 30.2 wt%, 30.5 wt%, 30.8 wt%, 31.1 wt%, or 31.5 wt%. And / or, when R1 includes Nd, the content of Nd is 28.3wt%, 28.7wt%, 29.0wt%, 29.1wt%, 29.5wt%, 29.9wt%, or 30.0wt%; And / or, when R1 includes Dy or Tb, the content of Dy or Tb is 0.4wt%, 0.6wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.3wt%, or 1.5wt%; And / or, when R1 includes Pr, the content of Pr is 0.5wt%, 1.0wt%, 1.5wt%, or 2.0wt%; And / or, the content of R2 is 0.2wt%, 0.4wt%, 0.42wt%, 0.43wt%, 0.48wt%, or 0.7wt%; And / or, the content of Co is 3.30 wt%, 3.60 wt%, 3.62 wt%, 3.90 wt%, 4.16 wt%, 4.18 wt%, 4.20 wt%, 4.21 wt%, 4.25 wt%, 4.50 wt%, 4.80 wt%, 4.85 wt%, or 5.10 wt%; And / or, the Cu content is 0.18wt%, 0.20wt%, 0.25wt%, 0.26wt%, 0.29wt%, 0.30wt%, 0.31wt%, or 0.35wt%; And / or, the Ga content is 0.10 wt%, 0.13 wt%, 0.16 wt%, 0.17 wt%, 0.18 wt%, 0.19 wt%, 0.20 wt%, or 0.22 wt%; And / or, the content of M is 0.18wt%, 0.19wt%, 0.20wt%, 0.21wt%, or 0.22wt%; And / or, the content of B is 0.98wt%, 0.99wt%, 1.00wt%, 1.01wt%, 1.02wt%, or 1.04wt%; And / or, the Al content is 0.04 wt%, 0.05 wt%, 0.06 wt%, or 0.07 wt%; And / or, the Fe content is 63.00 wt%, 63.10 wt%, 63.68 wt%, 63.78 wt%, 63.91 wt%, 63.92 wt%, 64.12 wt%, 64.20 wt%, or 64.75 wt%; And / or, the chemical composition is R w Fe 100-w-x-y-z Co x Cu y Ga z The area percentage of the new phase in the two grain boundaries is 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, or 3.2%.

4. The neodymium iron boron magnet material as described in claim 2, characterized in that, The content of R is 29.8~30.8 wt%; And / or, when R1 includes Nd, the content of Nd is 28.5~29.5 wt%; And / or, when R1 includes Dy or Tb, the content of Dy or Tb is 0.3~1.2wt%; And / or, when R1 includes Pr, the content of Pr is 0.0~1.0 wt%; And / or, the content of R2 is 0.2~0.5 wt%; And / or, the content of Co is 3.60~4.80 wt%; And / or, the Cu content is 0.25~0.35 wt%; And / or, the Ga content is 0.15~0.20 wt%; And / or, the content of B is 0.98~1.02 wt%; And / or, the content of Al is 0.03~0.07wt%; And / or, the chemical composition is R w Fe 100-w-x-y-z Co x Cu y Ga z The new phase accounts for 2.2% to 3.0% of the area of ​​the two grain boundaries.

5. The neodymium iron boron magnet material as described in claim 1, characterized in that, The neodymium iron boron magnet material comprises the following components by mass: Nd 28.2wt%, Dy 1.3wt%, Tb 0.43wt%, Co 4.21wt%, Cu 0.31wt%, Ga 0.18wt%, Ti 0.20wt%, B 0.99wt%, Al 0.06wt%, and Fe 64.12wt%. The neodymium iron boron magnet material does not contain Zr or Nb. wt% represents the percentage of each component's mass to the total mass of the neodymium iron boron magnet material. The neodymium iron boron magnet material contains Nd₂Fe₂. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 55.15 Fe 41.28 Co 2.74 Cu 0.47 Ga 0.36 R is one or more of Nd, Dy, and Tb, and the area ratio of the new phase in the two-grain boundary is 2.36%. Alternatively, the NdFeB magnet material comprises the following components by mass: Nd 29.0wt%, Dy 1.0wt%, Tb 0.42wt%, Co 4.18wt%, Cu 0.29wt%, Ga 0.19wt%, Ti 0.18wt%, B 0.99wt%, Al 0.07wt%, and Fe 63.68wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd₂Fe₂. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 56.33 Fe 40.16 Co 2.68 Cu 0.45 Ga 0.38 R is one or more of Nd, Dy, and Tb, and the area ratio of the new phase in the two-grain boundary is 2.58%. Alternatively, the NdFeB magnet material comprises the following components by mass: Nd 29.9wt%, Dy 0.6wt%, Tb 0.43wt%, Co 4.25wt%, Cu 0.30wt%, Ga 0.18wt%, Ti 0.19wt%, B 1.00wt%, Al 0.05wt%, and Fe 63.1wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd₂Fe₂. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 57.11 Fe 39.27 Co 2.82 Cu 0.45 Ga 0.35 R is one or more of Nd, Dy, and Tb, and the area ratio of the new phase in the two-grain boundary is 2.72%. Alternatively, the NdFeB magnet material comprises the following components by mass: Nd 29.0wt%, Dy 1.0wt%, Tb 0.43wt%, Co 3.62wt%, Cu 0.30wt%, Ga 0.20wt%, Ti 0.21wt%, B 0.99wt%, Al 0.05wt%, and Fe 64.2wt%. The NdFeB magnet material does not contain Zr or Nb, and wt% represents the percentage of the mass of each component to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd₂Fe₂. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 56.13 Fe 40.88 Co 2.18 Cu 0.45 Ga 0.36 R is one or more of Nd, Dy, and Tb, and the area ratio of the new phase in the two-grain boundary is 2.25%. Alternatively, the NdFeB magnet material comprises the following components by mass: Nd 29.0wt%, Dy 1.0wt%, Tb 0.43wt%, Co 4.85wt%, Cu 0.31wt%, Ga 0.17wt%, Ti 0.20wt%, B 0.99wt%, Al 0.05wt%, and Fe 63.00wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd₂Fe₂. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 56.18 Fe 39.91 Co 3.12 Cu 0.46 Ga 0.33 R is one or more of Nd, Dy, and Tb, and the area ratio of the new phase in the two-grain boundary is 2.89%. Alternatively, the NdFeB magnet material comprises the following components by mass: Nd 29.0wt%, Dy 0.48wt%, Tb 0.80wt%, Co 4.18wt%, Cu 0.20wt%, Ga 0.18wt%, Ti 0.19wt%, B 1.01wt%, Al 0.04wt%, and Fe 63.92wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd₂Fe₂. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 55.84 Fe 40.88 Co 2.65 Cu 0.32 Ga 0.31 R is one or more of Nd, Dy, and Tb, and the area ratio of the new phase in the two-grain boundary is 2.38%. Alternatively, the NdFeB magnet material comprises the following components by mass: Nd 29.0wt%, Dy 1.00wt%, Tb 0.43wt%, Co 4.16wt%, Cu 0.18wt%, Ga 0.20wt%, Ti 0.21wt%, B 0.99wt%, Al 0.05wt%, and Fe 63.78wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd₂Fe₂. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 56.49 Fe 40.27 Co 2.59 Cu 0.32 Ga 0.33 R is one or more of Nd, Dy, and Tb, and the area ratio of the new phase in the two-grain boundary is 2.42%. Alternatively, the NdFeB magnet material comprises the following components by mass: Nd 29.0wt%, Dy 1.00wt%, Tb 0.42wt%, Co 4.16wt%, Cu 0.31wt%, Ga 0.10wt%, Ti 0.21wt%, B 0.99wt%, Al 0.06wt%, and Fe 63.75wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd₂Fe₂. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 56.37 Fe 40.23 Co 2.71 Cu 0.52 Ga 0.17 R is one or more of Nd, Dy, and Tb, and the area ratio of the new phase in the two-grain boundary is 2.34%. Alternatively, the NdFeB magnet material comprises the following components by mass: Nd 29.0wt%, Dy 1.00wt%, Tb 0.20wt%, Co 4.18wt%, Cu 0.26wt%, Ga 0.20wt%, Ti 0.20wt%, B 0.99wt%, Al 0.06wt%, and Fe 63.91wt%. The NdFeB magnet material does not contain Zr or Nb. The wt% percentage represents the mass of each component relative to the total mass of the NdFeB magnet material. The NdFeB magnet material contains Nd₂Fe₂. l4 B grains and their shells, adjacent to the Nd2Fe l4 The B-grain contains two grain boundaries and a grain boundary triangular region, wherein the two grain boundaries contain a new phase with the chemical composition R. 55.47 Fe 41.16 Co 2.77 Cu 0.25 Ga 0.35 R is one or more of Nd, Dy and Tb, and the area ratio of the new phase in the two grain boundaries is 2.45%.

6. A method for preparing a neodymium iron boron magnet material, characterized in that, It is obtained by melting, pulverizing, shaping and sintering the elements other than R2 in the raw material composition to obtain a sintered body, and then diffusing the mixture of the sintered body and R2 through the grain boundary. The grain boundary diffusion treatment employs a three-stage heating and cooling process: the first stage is heated to 400-500°C, the second stage is heated to 930-990°C, and the third stage is 30-60°C lower than the second stage. The raw material composition comprises, by weight percentage, the following components: R: 29.0~32.0 wt%, where R is a rare earth element, and R includes R1 and R2; R1 includes Nd, wherein the Nd content is ≥27.5 wt%; R1 also includes Dy and / or Tb; Pr is an optional element of R1; R2 includes Dy and / or Tb, and the content of R2 is 0.1~0.8 wt%. Cu: 0.16~0.40wt% Ga: 0.07~0.24wt% Al: ≤0.10wt% B: 0.96~1.10wt% Co: 3.0~5.5wt% M: 0.10~0.25wt%, M is selected from at least one of Ti, Zr and Nb; Fe: 63.0~65.0 wt% wt% is the percentage of the mass of each component to the total mass of the raw material composition; R1 element is added during the smelting step, and R2 element is added during the grain boundary diffusion step.

7. The method for preparing neodymium iron boron magnet material as described in claim 6, characterized in that, The smelting operation involves smelting and casting the elements other than R2 in the raw material composition of the neodymium iron boron magnet material using an ingot casting process and a rapid solidification sheet process to obtain an alloy sheet; And / or, the melting temperature is 1400~1600℃; And / or, the melting environment is a vacuum of 0.05 Pa; And / or, the powdering includes hydrogen crushing and / or air jet milling; And / or, the molding process employs a magnetic field molding method; And / or, the sintering is performed using a vacuum sintering process and / or an inert atmosphere sintering process; And / or, the sintering temperature is 1000~1200℃; And / or, the sintering time is 0.5~10h; And / or, the coating operation of R2 is further included prior to the grain boundary diffusion; And / or, in the three-stage heating and cooling heat treatment, the first stage heats up to 400~500℃ and holds for 1~6 hours; the second stage heats up to 930~990℃ and holds for 10~30 hours; the third stage cools down to 840~930℃ and holds for 3~10 hours; the heating rate for each stage is 3~15℃ / min and the cooling rate is 5~30℃ / min. And / or, after the grain boundary diffusion, a low-temperature tempering treatment is also performed.

8. The method for preparing neodymium iron boron magnet material as described in claim 7, characterized in that, The melting temperature is 1450~1550℃; And / or, the magnetic field strength of the magnetic field shaping method is above 1.5T; And / or, the sintering temperature is 1050~1100℃; And / or, the sintering time is 3 to 6 hours.

9. The method for preparing the neodymium iron boron magnet material as described in claim 7, characterized in that, The melting temperature is 1520℃; The sintering temperature is 1080℃.

10. The method for preparing the neodymium iron boron magnet material as described in claim 7, characterized in that, The hydrogen-based powdering process includes hydrogen absorption, dehydrogenation, and cooling. And / or, the pressure of the airflow milled powder is 0.1~2MPa; And / or, the airflow in the air-jet mill is an inert atmosphere; And / or, the air jet milling time is 2-4 hours; And / or, when using the inert atmosphere sintering process, the vacuum level is below 5 × 10⁻⁶ at the beginning of the sintering stage. -1 Under the condition of Pa; And / or, prior to the said grain boundary diffusion, the R2 is coated in the form of a low-melting-point alloy or oxide; And / or, the temperature of the low-temperature tempering treatment is 460~560℃; And / or, the low-temperature tempering time is 1~5h.

11. The method for preparing neodymium iron boron magnet material as described in claim 10, characterized in that, The temperature for hydrogen absorption is 20~200℃; And / or, the hydrogen absorption pressure is 50~600kPa; And / or, the dehydrogenation temperature is 400~650℃; And / or, the pressure of the air jet milled powder is 0.5~0.7MPa; And / or, the gas flow in the air-jet mill is nitrogen; And / or, the air jet milling time is 3 hours; And / or, when using the inert atmosphere sintering process, the inert atmosphere is helium or argon; And / or, prior to the said grain boundary diffusion, the low-melting-point alloy or oxide is an alloy powder or oxide of Dy or Tb; And / or, the temperature of the low-temperature tempering treatment is 500°C; And / or, the low-temperature tempering time is 3 hours.

12. The method for preparing neodymium iron boron magnet material as described in claim 10, characterized in that, The temperature at which hydrogen is absorbed is 25°C; And / or, the hydrogen absorption pressure is 60~300kPa; And / or, the dehydrogenation temperature is 500~550℃; And / or, the pressure of the airflow milled powder is 0.6 MPa.

13. The method for preparing neodymium iron boron magnet material as described in claim 10, characterized in that, The hydrogen absorption pressure is 90 kPa.

14. The method for preparing the neodymium iron boron magnet material as described in claim 7, characterized in that, The first stage of the three-stage heating and cooling heat treatment is heated to 430℃, 450℃, 460℃ or 490℃. And / or, the first stage of the three-stage heating and cooling heat treatment has a holding time of 2h, 3h or 4h; And / or, the second stage of the three-stage heating and cooling heat treatment is heated to 940°C, 955°C, 960°C or 980°C; And / or, the second stage holding time of the three-stage heating and cooling heat treatment is 12h, 16h, 20h, 24h or 28h; And / or, the third stage of the three-stage heating and cooling heat treatment is cooled to 850°C, 880°C, 900°C or 910°C; And / or, the third stage of the three-stage heating and cooling heat treatment has a holding time of 5h, 6h, 7h or 9h; And / or, the heating rate of each stage of the three-stage heating and cooling heat treatment is 6℃ / min, 8℃ / min or 10℃ / min; And / or, the cooling rate of each stage of the three-stage heating and cooling heat treatment is 6℃ / min, 10℃ / min, 12℃ / min or 15℃ / min.

15. The method for preparing neodymium iron boron magnet material as described in claim 7, characterized in that, The first stage of the three-stage heating and cooling heat treatment is heated to 420~480℃; And / or, the first stage of the three-stage heating and cooling heat treatment has a holding time of 2 to 5 hours; And / or, the second stage of the three-stage heating and cooling heat treatment is heated to 940~980℃; And / or, the second stage of the three-stage heating and cooling heat treatment has a holding time of 15~25h; And / or, the third stage of the three-stage heating and cooling heat treatment is cooled to 860~920℃; And / or, the third stage of the three-stage heating and cooling heat treatment has a holding time of 4~9 hours.

16. The method for preparing the neodymium iron boron magnet material as described in claim 6, characterized in that, R1 is either "Nd and Dy" or "Nd and Tb"; And / or, the content of R is 29.5~31.5 wt%; And / or, when R1 includes Nd, the content of Nd is 28.2~30.0 wt%; And / or, when R1 includes Dy or Tb, the content of Dy or Tb is ≤1.5wt% but not 0; And / or, when R1 includes Pr, the content of Pr is 0.0~2.00 wt%; And / or, the content of R2 is 0.2~0.7wt%; And / or, the content of Co is 3.20~5.20 wt%; And / or, the Cu content is 0.18~0.35wt%; And / or, the Ga content is 0.10~0.22wt%; And / or, the content of M is 0.17~0.23 wt%; And / or, the content of B is 0.97~1.05 wt%; And / or, the content of Al is ≤0.08wt%, but not 0.

17. The method for preparing the neodymium iron boron magnet material as described in claim 16, characterized in that, The content of R is 29.6 wt%, 29.8 wt%, 29.9 wt%, 30.0 wt%, 30.2 wt%, 30.5 wt%, 30.8 wt%, 31.1 wt%, or 31.5 wt%. And / or, when R1 includes Nd, the content of Nd is 28.3wt%, 28.7wt%, 29.0wt%, 29.1wt%, 29.5wt%, 29.9wt%, or 30.0wt%; And / or, when R1 includes Dy or Tb, the content of Dy or Tb is 0.4wt%, 0.6wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.3wt%, or 1.5wt%; And / or, when R1 includes Pr, the content of Pr is 0.5wt%, 1.0wt%, 1.5wt%, or 2.0wt%; And / or, the content of R2 is 0.2wt%, 0.4wt%, 0.42wt%, 0.43wt%, 0.48wt%, or 0.7wt%; And / or, the content of Co is 3.30 wt%, 3.60 wt%, 3.62 wt%, 3.90 wt%, 4.16 wt%, 4.18 wt%, 4.20 wt%, 4.21 wt%, 4.25 wt%, 4.50 wt%, 4.80 wt%, 4.85 wt%, or 5.10 wt%; And / or, the Cu content is 0.18wt%, 0.20wt%, 0.25wt%, 0.26wt%, 0.29wt%, 0.30wt%, 0.31wt%, or 0.35wt%; And / or, the Ga content is 0.10 wt%, 0.13 wt%, 0.16 wt%, 0.17 wt%, 0.18 wt%, 0.19 wt%, 0.20 wt%, or 0.22 wt%; And / or, the content of M is 0.18wt%, 0.19wt%, 0.20wt%, 0.21wt%, or 0.22wt%; And / or, the content of B is 0.98wt%, 0.99wt%, 1.00wt%, 1.01wt%, 1.02wt%, or 1.04wt%; And / or, the Al content is 0.04 wt%, 0.05 wt%, 0.06 wt%, or 0.07 wt%; And / or, the Fe content is 63.00 wt%, 63.10 wt%, 63.68 wt%, 63.78 wt%, 63.91 wt%, 63.92 wt%, 64.12 wt%, 64.20 wt%, or 64.75 wt%.

18. The method for preparing the neodymium iron boron magnet material as described in claim 16, characterized in that, The content of R is 29.8~30.8 wt%; And / or, when R1 includes Nd, the content of Nd is 28.5~29.5 wt%; And / or, when R1 includes Dy or Tb, the content of Dy or Tb is 0.3~1.2wt%; And / or, when R1 includes Pr, the content of Pr is 0.0~1.0 wt%; And / or, the content of R2 is 0.2~0.5 wt%; And / or, the content of Co is 3.60~4.80 wt%; And / or, the Cu content is 0.25~0.35 wt%; And / or, the Ga content is 0.15~0.20 wt%; And / or, the content of B is 0.98~1.02 wt%; And / or, the content of Al is 0.03~0.07wt%.

19. A neodymium iron boron magnet material, characterized in that, It is prepared by any one of the preparation methods as described in claims 6 to 18.

20. An electronic device, characterized in that, It includes neodymium iron boron magnet materials as described in any one of claims 1 to 5 or 19.

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