Neodymium iron boron magnet and manufacturing method thereof

Abstract

To provide neodymium iron boron magnets I and II, which have excellent residual magnetic flux density, coercive force, and squareness ratio, are highly flexible in terms of adjusting composition and performance, and effectively enhance the effect of grain boundary diffusion, thereby increasing the utilization rate of heavy rare earths, and also provide a method of manufacturing the same.SOLUTION: A neodymium iron boron magnet I includes main phase crystal grains, triangular grain boundary regions, and two-grain grain boundary regions, all of which contain MB2 particles, where M is one or more selected from Nb, Zr, and Ti, and the ratio of the number of MB2 particles in each region to the number of MB2 particles in the neodymium iron boron magnet I is less than 90% in the triangular grain boundary regions, greater than 10% in the two-grain grain boundary regions and main phase crystal grains, and greater than 5% in the two-grain grain boundary regions, and the M content is 0.1 wt.% to 1.5 wt.%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a neodymium-iron-boron magnet and a method for producing the same. [Background technology]

[0002] NdFeB permanent magnet material is currently one of the most excellent permanent magnet materials and is widely used in the main drive motors of new energy vehicles, industrial motors, and various household appliances. With the development of smaller and lighter motors, higher requirements are being placed on the magnetic performance of NdFeB permanent magnet material. Therefore, it is of great importance to constantly explore new methods and technologies for manufacturing high-performance NdFeB permanent magnet material and improve its magnetic performance and temperature characteristics.

[0003] Grain boundary diffusion of heavy rare earths can effectively increase the coercivity of magnets and is currently the main method for producing the high operating temperature magnets required for permanent magnet motors. The heavy rare earth diffusion process involves multiple diffusion mechanisms, and heavy rare earths tend to accumulate in large quantities on the surface of the magnet, forming an excessively thick shell layer on the surface of the main phase crystal grains near the magnet surface, resulting in a serious waste of valuable heavy rare earth diffusion resources. At the same time, this significantly reduces the remanence of the magnet, resulting in insufficient improvement in coercivity and adversely affecting the overall magnetic performance of the magnet. Summary of the Invention [Problem to be solved by the invention]

[0004] To solve the above-mentioned problems in grain boundary diffusion technology, the present invention provides NdFeB magnets and methods for manufacturing the same. Both NdFeB magnet I and NdFeB magnet II have excellent remanence, coercivity, and squareness, and offer great flexibility in adjusting their composition and performance. NdFeB magnet I can also effectively enhance the effect of grain boundary diffusion, thereby increasing the utilization rate of heavy rare earth elements. [Means for solving the problem]

[0005] The present invention discloses a neodymium iron boron magnet I, which includes main phase crystal grains, triangular grain boundary regions, and two-grain grain boundary regions, and each of the main phase crystal grains, the triangular grain boundary regions, and the two-grain grain boundary regions contains MB2 grains, and M is one or more selected from Nb, Zr, and Ti; the ratio of the number of MB2 particles in the triangular grain boundary region to the number of MB2 particles in the neodymium iron boron magnet I is less than 90%, the ratio of the number of MB2 particles in the two-grain grain boundary region and the main phase crystal grains to the number of MB2 particles in the neodymium iron boron magnet I is greater than 10%, and the ratio of the number of MB2 particles in the two-grain grain boundary region to the number of MB2 particles in the neodymium iron boron magnet I is greater than 5%; The content of M in the neodymium iron boron magnet I is 0.1 wt% to 1.5 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet I.

[0006] In the present invention, the terms "main phase grain," "triangular grain boundary region," and "two-grain grain boundary region" are all defined as commonly used in the art. A two-grain grain boundary region is a region formed between two adjacent main phase grains, and a triangular grain boundary region is a region formed between three or more main phase grains.

[0007] Through extensive research, the inventors have discovered that by adjusting the number of MB2 particles in the triangular grain boundary regions and the number of MB2 particles in the two-grain grain boundary regions, the remanence, coercivity, and squareness of a NdFeB magnet can be significantly improved. At the same time, the NdFeB magnet I of the present invention can also enhance the effect of grain boundary diffusion. This is because the MB2 particles in the grain boundary regions expand the grain boundary diffusion channels and increase the diffusion rate of heavy rare earth elements. At the same time, the MB2 particles at the edges of the main phase crystal grains can reduce the thickness of the heavy rare earth shell layer formed on the surface of the main phase crystal grains, thereby increasing the utilization rate of heavy rare earth elements.

[0008] In the present invention, the ratio of the number of MB2 grains in the triangular grain boundary region to the number of MB2 grains in the neodymium iron boron magnet I is preferably 50% to 80%, for example 68%, 74%, or 78%.

[0009] In the present invention, the ratio of the number of MB2 grains in the two-grain grain boundary region and the main phase crystal grains to the number of MB2 grains in the neodymium iron boron magnet I is preferably 20% to 50%, for example 22%, 26%, or 32%.

[0010] In some specific embodiments of the present invention, the neodymium iron boron magnet I comprises the following components: RL: 24 wt% to 33 wt%, RL is a light rare earth element, and The RL contains Nd, 0.7 wt% to 1.2 wt% B, and 0.1 wt% to 1 wt% M; The balance is Fe.

[0011] Here, the neodymium iron boron magnet I preferably contains T, where T is one or more selected from Cu, Al, and Ga.

[0012] Here, the content of the T is preferably 0 to 2.1 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet I. If the content of the T element is within the above range, it is advantageous for the formation of MB2 particles, because Cu, Al, or Ga form a 6:13:1 phase at the grain boundary. For example, when the element is Ga, the 6:13:1 phase is Nd6Fe 13 This is because it is a Ga phase. In addition, the 6:13:1 phase consumes a part of the B element, and when the content of the T element is within the above range, the formation of MB2 particles can be ensured.

[0013] Here, the Cu content is preferably 0 to 0.7 wt%, for example 0.2 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet I.

[0014] Here, the Al content is preferably 0 to 0.7 wt%, for example 0.08 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet I.

[0015] Here, the Ga content is preferably 0 to 0.7 wt%, for example 0.19 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet I.

[0016] Here, the neodymium iron boron magnet I preferably further contains Co.

[0017] Here, the Co content is preferably 0 to 2 wt %, for example 1 wt %, and the content refers to the mass percentage of the element in the neodymium iron boron magnet I.

[0018] Here, it is preferable that the neodymium iron boron magnet I further contains Dy and / or Tb.

[0019] Here, the Dy content is preferably 0 to 1.5 wt%, more preferably 0.1 wt% to 0.15 wt%, for example 0.12 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet I.

[0020] Here, the Tb content is preferably 0 to 1.5 wt%, more preferably 0.1 wt% to 0.15 wt%, for example 0.12 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet I.

[0021] wherein the RL preferably comprises one or more of La, Ce, Pr, Sm, Gd, Ho, and Y.

[0022] Here, the RL content is preferably 29 wt% to 32 wt%, for example 30.14 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet I.

[0023] Here, the B content is preferably 0.8 wt% to 1.1 wt%, for example 0.96 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet I.

[0024] Here, the content of M is preferably 0.1 wt% to 1 wt%, for example 0.4 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet I.

[0025] Here, the Zr content is preferably 0 to 1 wt %, for example 0.4 wt %, and the content refers to the mass percentage of the element in the neodymium iron boron magnet I.

[0026] Here, the Nb content is preferably 0 to 1 wt%, for example 0.4 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet I.

[0027] Here, the Ti content is preferably 0 to 1 wt %, for example 0.4 wt %, and the content means the mass percentage of the element in the neodymium iron boron magnet I.

[0028] In the present invention, the shape of the MB2 particles is, for example, one or more of a sphere, a needle, a rod, and a sheet, and is preferably a rod and / or a sheet.

[0029] In the present invention, the particle size of the MB2 particles is preferably less than 500 nm, more preferably less than 200 nm. When the MB2 particles are spherical, the particle size refers to the diameter of the spherical MB2 particles. When the MB2 particles are sheet-like, needle-like, or rod-like, the particle size refers to the minimum distance between two points passing through the center of the MB2 particles.

[0030] The number of MB2 particles in the present invention is calculated, for example, using the following method: Statistical analysis is performed on the number of MB2 particles in multiple BSE images of a neodymium-iron-boron magnet to obtain the distribution ratio of MB2 particles. The number of MB2 particles is calculated as follows: Statistical analysis is performed on 10 or more BSE images of different regions magnified 10,000 times to obtain the distribution ratio of MB2 particles.

[0031] The present invention further provides a method for producing a neodymium-iron-boron magnet I, which includes the following steps: the raw material is melted and refined, cast, hydro-crushed, jet-milled, pressed, sintered, and aged, and the hydro-crushed process includes the steps of hydrogen absorption, dehydrogenation, and cooling, in that order.

[0032] The content of M in the raw material is 0.1 wt% to 1.5 wt%, and the content means the mass percentage of the element in the raw material, and M is one or more selected from Nb, Zr, and Ti.

[0033] In some specific embodiments of the present invention, the raw material comprises the following components: RL: 24 wt% to 33 wt%, RL is a light rare earth element, and The RL contains Nd, 0.7 wt% to 1.2 wt% B, and 0.1 wt% to 1 wt% M; The balance is Fe.

[0034] Here, the raw material preferably contains T, where T is one or more selected from Cu, Al, and Ga.

[0035] Here, the content of T is preferably 0 to 2.1 wt%, and the content means the mass percentage of the element in the raw material. If the content of T element is within the above range, it is advantageous for the formation of MB2 particles, because Cu, Al, or Ga forms a 6:13:1 phase at the grain boundary. For example, when the element is Ga, the 6:13:1 phase is Nd6Fe 13 This is because it is a Ga phase. In addition, the 6:13:1 phase consumes a part of the B element, and when the content of the T element is within the above range, the formation of MB2 particles can be ensured.

[0036] Here, the Cu content is preferably 0 to 0.7 wt%, for example 0.2 wt%, and the content means the mass percentage of the element in the raw material.

[0037] Here, the Al content is preferably 0 to 0.7 wt%, for example 0.08 wt%, and the content means the mass percentage of the element in the raw material.

[0038] Here, the Ga content is preferably 0 to 0.7 wt%, for example 0.19 wt%, and the content means the mass percentage of the element in the raw material.

[0039] Here, the raw material preferably further contains Co.

[0040] Here, the Co content is preferably 0 to 2 wt %, for example 1 wt %, and the content means the mass percentage of the element in the raw material.

[0041] Here, it is preferable that the raw material further contains Dy and / or Tb.

[0042] Here, the Dy content is preferably 0 to 1.5 wt%, more preferably 0.1 wt% to 0.15 wt%, for example 0.12 wt%, and the content means the mass percentage of the element in the raw material.

[0043] Here, the content of Tb is preferably 0 to 1.5 wt%, more preferably 0.1 wt% to 0.15 wt%, for example 0.12 wt%, and the content means the mass percentage of the element in the raw material.

[0044] wherein the RL preferably comprises one or more of La, Ce, Pr, Sm, Gd, Ho, and Y.

[0045] Here, the content of the RL is preferably 29 wt% to 32 wt%, for example 30.14 wt%, and the content means the mass percentage of the element in the raw material.

[0046] Here, the content of B is preferably 0.8 wt% to 1.1 wt%, for example 0.96 wt%, and the content means the mass percentage of the element in the raw material.

[0047] Here, the content of M is preferably 0.1 wt% to 1 wt%, for example 0.4 wt%, and the content means the mass percentage of the element in the raw material.

[0048] Here, the Zr content is preferably 0 to 1 wt%, for example 0.4 wt%, and the content means the mass percentage of the element in the raw material.

[0049] Here, the content of Nb is preferably 0 to 1 wt%, for example 0.4 wt%, and the content means the mass percentage of the element in the raw material.

[0050] Here, the content of Ti is preferably 0 to 1 wt%, for example 0.4 wt%, and the content means the mass percentage of the element in the raw material.

[0051] In the present invention, the temperature of the melting and smelting is preferably 1500 to 1560°C, and more preferably 1500 to 1540°C.

[0052] In the present invention, the degree of vacuum in the melting and smelting is, for example, 5 × 10 -2 It is Pa.

[0053] In the present invention, the melting and smelting equipment is, for example, a high-frequency vacuum induction melting furnace.

[0054] In the present invention, the casting temperature is preferably 1350 to 1560°C, and more preferably 1420 to 1460°C.

[0055] In the present invention, the casting method is, for example, a strip casting method.

[0056] In the present invention, the thickness of the alloy flakes obtained after the casting is preferably 0.2 to 0.4 mm, for example, 0.35 mm.

[0057] In the present invention, the pressure for the hydrogen absorption is, for example, 0.085 MPa.

[0058] In the present invention, the dehydrogenation temperature is preferably 450 to 550°C.

[0059] In the present invention, the dehydrogenation comprises the following steps: dehydrogenation is carried out under conditions of evacuation and increasing temperature.

[0060] In the present invention, the particle size of the powder obtained after the jet mill treatment is preferably 1 to 8 μm.

[0061] In the present invention, the jet mill treatment is preferably carried out in an atmosphere having an oxidizing gas content of 20 to 50 ppm.

[0062] Here, the oxidizing gas refers to oxygen and / or water vapor.

[0063] In the present invention, the pressure of the jet mill treatment is preferably 0.4 to 1 MPa, for example, 0.68 MPa.

[0064] In the present invention, the magnetic field strength for the press molding is preferably 0.7 to 2.5T, for example 1.8T.

[0065] In the present invention, the press molding is preferably carried out in an inert atmosphere, for example, in a nitrogen atmosphere.

[0066] In the present invention, the temperature of the sintering treatment is preferably 900 to 1200°C, for example, 1085°C.

[0067] In the present invention, the time for the sintering treatment is preferably 3 to 24 hours, for example, 6 hours.

[0068] In the present invention, the aging treatment preferably includes a first stage aging treatment and a second stage aging treatment in this order.

[0069] Here, the temperature of the first stage aging treatment is preferably 600 to 980°C, for example, 900°C.

[0070] Here, the temperature of the second stage aging treatment is preferably 400 to 600°C, for example, 520°C.

[0071] The present invention further provides a neodymium iron boron magnet I produced by the above-mentioned method for producing a neodymium iron boron magnet I.

[0072] The present invention further provides a neodymium iron boron magnet II, which comprises main phase crystal grains, triangular grain boundary regions, and two-grain grain boundary regions, the surfaces of the main phase crystal grains comprise heavy rare earth shell layers, the main phase crystal grains, the triangular grain boundary regions, and the two-grain grain boundary regions all contain MB2 particles, M is one or more selected from Nb, Zr, and Ti, and the content of M in the neodymium iron boron magnet II is 0.1 wt% to 1.5 wt%; NCell ≥ 5% and N Cell is the sum of the number of MB2 grains in the main phase grains and the heavy rare earth shell layer, where C shell / C core ≧1.05, and C shell is the concentration of heavy rare earth in the heavy rare earth shell layer, and C core is the concentration of the heavy rare earth element at the center of the main phase crystal grains.

[0073] In the present invention, N Cell The statistical method involves randomly selecting at least 10 photographs with an amplification factor of 5000 or more within a depth of 0 to 50 μm from the diffusion surface of a neodymium-iron-boron magnet II, and counting the number of MB2 particles in 100 or more main phase crystal grains and their heavy rare earth shell layers.

[0074] In the present invention, a position far from the grain boundary inside the main phase crystal grain, which is the center of the main phase crystal grain. Cell ≧10%, more preferably N Cell is 14%, 15%, 20% or 30%.

[0075] In some specific implementations of the present invention, C shell / C core is 1.5 to 1.6, for example, 1.52, 1.53, 1.54, or 1.58.

[0076] In some specific embodiments of the present invention, the neodymium iron boron magnet II comprises the following components: RL: 24 wt% to 33 wt%, RL is a light rare earth element, and The RL contains Nd, 0.7 wt% to 1.2 wt% B, 0.1 wt% to 1 wt% M, and 0.1 wt% to 5 wt% RH, where RH is a heavy rare earth element; The balance is Fe.

[0077] Here, the RH is, for example, Dy and / or Tb.

[0078] Here, the content of Dy is preferably 0.1 wt% to 3 wt%.

[0079] Here, the content of Tb is preferably 0.1 wt% to 3 wt%.

[0080] In some specific embodiments of the present invention, the neodymium iron boron magnet II comprises the following components: RL: 24 wt% to 33 wt%, RL is a light rare earth element, and The RL contains Nd, 0.7 wt% to 1.2 wt% B, and 0.1 wt% to 1 wt% M; The balance is Fe.

[0081] Here, the neodymium iron boron magnet II preferably contains T, where T is one or more selected from Cu, Al, and Ga.

[0082] The T content is preferably 0 to 2.1 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet II. The T content within the above range is advantageous for the formation of MB2 particles, because Cu, Al, or Ga form a 6:13:1 phase at the grain boundaries. For example, when the element is Ga, the 6:13:1 phase is Nd6Fe 13 This is because it is a Ga phase. In addition, the 6:13:1 phase consumes a part of the B element, and when the content of the T element is within the above range, the formation of MB2 particles can be ensured.

[0083] Here, the Cu content is preferably 0 to 0.7 wt%, for example 0.2 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet II.

[0084] Here, the Al content is preferably 0 to 0.7 wt%, for example 0.08 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet II.

[0085] Here, the Ga content is preferably 0 to 0.7 wt%, for example 0.19 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet II.

[0086] Here, the neodymium iron boron magnet II preferably further contains Co.

[0087] Here, the Co content is preferably 0 to 2 wt%, for example 1 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet II.

[0088] Here, the neodymium iron boron magnet II preferably further contains Dy and / or Tb.

[0089] Here, the Dy content is preferably 0 to 1.5 wt%, more preferably 0.1 wt% to 0.15 wt%, for example 0.12 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet II.

[0090] Here, the Tb content is preferably 0 to 1.5 wt%, more preferably 0.1 wt% to 0.15 wt%, for example 0.12 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet II.

[0091] wherein the RL preferably comprises one or more of La, Ce, Pr, Sm, Gd, Ho, and Y.

[0092] Here, the content of RL is preferably 29 wt% to 32 wt%, for example 30.14 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet II.

[0093] Here, the B content is preferably 0.8 wt% to 1.1 wt%, for example 0.96 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet II.

[0094] In the present invention, the content of M is preferably 0.1 wt% to 1 wt%, for example 0.4 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet II.

[0095] In the present invention, the Zr content is preferably 0 to 1 wt%, for example 0.4 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet II.

[0096] In the present invention, the Nb content is preferably 0 to 1 wt%, for example 0.4 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet II.

[0097] In the present invention, the Ti content is preferably 0 to 1 wt%, for example 0.4 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet II.

[0098] In the present invention, the thickness of the heavy rare earth shell layer is preferably less than 1 μm.

[0099] The present invention further provides a method for producing neodymium iron boron magnet II, which is obtained by subjecting the neodymium iron boron magnet I described above to a grain boundary diffusion treatment.

[0100] In the present invention, the temperature of the grain boundary diffusion treatment is preferably 800 to 1100°C, more preferably 800 to 1000°C, for example 900°C.

[0101] In the present invention, the time for the grain boundary diffusion treatment is preferably 6 to 36 hours, more preferably 12 to 36 hours, for example, 10 hours.

[0102] In the present invention, after the grain boundary diffusion treatment, a step of heat retention treatment is preferably further included.

[0103] Here, the temperature of the heat-retaining treatment is preferably 400 to 700°C, more preferably 400 to 600°C, for example, 460°C.

[0104] Here, the time for the heat-retaining treatment is preferably 1 to 6 hours, more preferably 2 to 4 hours.

[0105] In the present invention, the diffusion source for the grain boundary diffusion treatment is preferably a diffusion source containing Dy and / or Tb.

[0106] Here, the weight increase of the diffusion source is preferably 0.1 to 1%, for example 0.6%, where weight increase refers to the ratio of the weight increase of the NdFeB magnet before and after the grain boundary diffusion treatment, i.e., weight increase = 1 - weight of the NdFeB magnet before the grain boundary diffusion treatment / weight of the NdFeB magnet after the grain boundary diffusion treatment.

[0107] As those skilled in the art generally know, in order to adapt the neodymium iron boron magnet I to the grain boundary diffusion treatment, the neodymium iron boron magnet I can generally be machined before the grain boundary diffusion treatment.

[0108] The present invention further provides a neodymium iron boron magnet II produced by the above-described method for producing a neodymium iron boron magnet II.

[0109] The present invention relates to the application of the neodymium iron boron magnet II to permanent magnets.

[0110] By arbitrarily combining the above-mentioned preferred conditions in accordance with common knowledge in this field, each preferred embodiment of the present invention can be obtained.

[0111] All of the reagents and raw materials used in the present invention are commercially available. [Effects of the Invention]

[0112] The positive and inventive effects of the present invention are as follows:

[0113] The NdFeB magnet I and NdFeB magnet II provided by the present invention both have excellent remanence, coercive force, and squareness ratio. Furthermore, the NdFeB magnet I of the present invention can effectively enhance the effect of grain boundary diffusion and increase the utilization rate of heavy rare earth elements.

[0114] The neodymium iron boron magnets I and II of the present invention offer great flexibility in terms of composition and performance adjustment. [Brief explanation of the drawings]

[0115] [Figure 1] FIG. 1 is a scanning electron microscope backscattered electron (BSE) diagram of the neodymium iron boron magnet I in Example 1. [Figure 2] FIG. 2 is a scanning electron microscope backscattered electron (BSE) diagram of the neodymium iron boron magnet II in Comparative Example 1. [Figure 3] FIG. 3 is a scanning electron microscope backscattered electron (BSE) diagram of the neodymium iron boron magnet II in Example 1. [Figure 4] FIG. 4 is a scanning electron microscope backscattered electron (BSE) diagram of the neodymium iron boron magnet II in Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0116] The present invention will be further described below with reference to examples, but the present invention is not limited to the scope of the above examples. In the following examples, experimental methods for which specific conditions are not specified are selected according to conventional methods and conditions or product specifications.

[0117] Table 1 shows the element contents of the neodymium iron boron magnets I of Examples 1 to 4 and Comparative Examples 1 to 3.

[0118] Table 1 JPEG2025122629000001.jpg234157Note: / indicates that the element is not included.

[0119] The neodymium iron boron magnets I and II of Examples 1 to 4 and Comparative Examples 1 to 3 were produced as follows.

[0120] The raw material is subjected to melting, smelting, casting, hydro-crushing, jet milling, press forming, sintering, and aging, and the hydro-crushing process includes the steps of hydrogen absorption, dehydrogenation, and cooling in that order. The M content in the raw material is 0.1 wt% to 1.5 wt%, and the content means the mass percentage of the element in the raw material, where M is one or more selected from Nb, Zr, and Ti.

[0121] Here, the melting and smelting process is carried out under a vacuum of 5×10 -2 The melting process is carried out in a high-frequency vacuum induction melting furnace with a melting temperature of 1500-1540°C. The casting process employs strip casting to cast the melted and refined material into alloy flakes with a thickness of 0.35 mm at a casting temperature of 1420-1460°C. Hydrogen absorption is carried out under a hydrogen pressure of 0.085 MPa, while dehydrogenation is carried out under a vacuum and elevated temperature condition at a dehydrogenation temperature of 550°C. The jet milling process involves jet milling the material from the hydrogen crushing process in an atmosphere containing 20-50 ppm of oxidizing gas, where the oxidizing gas refers to oxygen and / or water vapor, at a pressure of 0.68 MPa. The press molding process is carried out in a nitrogen atmosphere with a magnetic field strength of 1.8 T. The sintering process involves sintering the press-formed blank at 1085°C for 6 hours. The aging treatment includes a first stage aging treatment and a second stage aging treatment in that order, with the first stage aging treatment being at 900°C and the second stage aging treatment being at 520°C. After the aging treatment, a neodymium iron boron magnet I is obtained.

[0122] After machining, neodymium iron boron magnet I is subjected to a grain boundary diffusion treatment. In the grain boundary diffusion treatment, a diffusion source containing Tb is used, and heat treatment is performed at 900°C for 10 hours, and then at 460°C for 2 hours. The weight of the diffusion source increases by 0.6%, and neodymium iron boron magnet II is obtained after the grain boundary diffusion treatment.

[0123] The resulting neodymium iron boron magnet was examined using a scanning electron microscope. Figure 1 shows a scanning electron microscope backscattered electron (BSE) diagram of the neodymium iron boron magnet I produced in Example 1 of the present invention. Here, the black rod-shaped particles are nanoscale MB2 particles, and the white circles in Figure 1 show MB2 particles within crystal grains, the white triangular areas show MB2 particles in triangular grain boundary regions, and the white rectangular areas show MB2 particles in two-grain grain boundary regions.

[0124] Figure 2 is a scanning electron microscope backscattered electron (BSE) image of the neodymium iron boron magnet II produced in Comparative Example 1 of the present invention. Here, the black rod-shaped particles are nanoscale MB2 particles, and the white circles in Figure 2 show MB2 particles in the triangular grain boundary region and the two-grain grain boundary region, while the white rectangular regions show MB2 particles in the main phase grains and the heavy rare earth shell layer.

[0125] Statistics of the number of MB2 particles in the neodymium-iron-boron magnets of Examples 1-4 and Comparative Examples 1-3: Statistics were run on the number of MB2 particles in multiple backscattered scanning electron microscope (BSE) images to obtain the MB2 particle distribution ratio. The number of MB2 particles was calculated as follows: the number of MB2 particles in different regions of 10 or more BSE images magnified 10,000 times was counted, and the MB2 particle distribution ratio was calculated.

[0126] Measurement of the thickness of the heavy rare earth shell layer: The measurement method involves statistically measuring the average thickness of the heavy rare earth shell layer of more than 100 main phase crystal grains within a depth of 0 to 50 μm from the diffusion surface in a neodymium-iron-boron magnet II. The measurement device is a scanning electron microscope.

[0127] NCell The statistical method involves randomly selecting at least 10 photographs with an amplification factor of 5000 or more within a depth of 0 to 50 μm from the diffusion surface of a neodymium-iron-boron magnet II, and counting the number of MB2 particles in 100 or more main phase crystal grains and their heavy rare earth shell layers.

[0128] Fig. 3 is a scanning electron microscope backscattered electron microscope (BSE) diagram of the neodymium iron boron magnet II in Example 1. Fig. 4 is a scanning electron microscope backscattered electron microscope (BSE) diagram of the neodymium iron boron magnet II in Comparative Example 1. As can be seen from Figs. 3 and 4, the thickness of the heavy rare earth shell layer in Example 1 is smaller than the thickness of the heavy rare earth shell layer in Comparative Example 1. Effect Example 1

[0129] The remanence (Br) and coercivity (Hcj) of the neodymium-iron-boron magnet produced in Example 1 were tested using a PFM pulsed BH demagnetization curve tester (model number: PFM14, Hirst, UK, on ​​behalf of the Institute of Metrology), and the results are shown in the table below. JPEG2025122629000002.jpg88149

[0130] The NdFeB magnet I of Examples 1 to 4 of the present invention can have a Br of 13.92 kGs or more, and a Hcj of 15.17 kOe or more. The NdFeB magnet II of Examples 1 to 4 can have a Br of 13.8 kGs or more, and a Hcj of 25.18 kOe or more. This shows that both the NdFeB magnet I and NdFeB magnet II of the present invention have excellent remanence and coercivity.

[0131] In Comparative Example 1, compared to Examples 1 to 4, the ratio of the number of MB2 particles in the triangular grain boundary region to the number of MB2 particles in the neodymium iron boron magnet I was too high, and the ratio of the number of MB2 particles in the two-particle grain boundary region and the main phase crystal grains to the number of MB2 particles in the neodymium iron boron magnet I was too low, resulting in a clear deterioration in the performance of the neodymium iron boron magnet I. In Comparative Example 2, compared to Examples 1 to 4, the ratio of the number of MB2 particles in the two-particle grain boundary region to the number of MB2 particles in the neodymium iron boron magnet I was too low, resulting in a significant decrease in Hcj of the neodymium iron boron magnet II. In Comparative Example 3, compared to Examples 1 to 4, the ratio of the number of MB2 particles in the two-particle grain boundary region to the number of MB2 particles in the neodymium iron boron magnet II was too low, resulting in a significant decrease in Hcj of the neodymium iron boron magnet II. Cell is too low, and the Hcj of the neodymium iron boron magnet II is significantly reduced.

[0132] As can be seen from the above, the NdFeB magnet I of the present invention can effectively enhance the effect of grain boundary diffusion and increase the utilization rate of heavy rare earths. Both the NdFeB magnet I and the NdFeB magnet II of the present invention have excellent remanence, coercivity, and squareness, and offer great flexibility in terms of adjusting their composition and performance.

Claims

1. Neodymium iron boron magnet I, The neodymium iron boron magnet I includes main phase crystal grains, triangular grain boundary regions, and two-grain grain boundary regions, and MB is present in all of the main phase crystal grains, the triangular grain boundary regions, and the two-grain grain boundary regions. ２ particles, wherein M is one or more selected from Nb, Zr, and Ti; MB in the triangular grain boundary region ２ The number of particles is MB in the neodymium iron boron magnet I. ２ The ratio of the number of grains to the number of grains is less than 90%, and the MB in the two-grain grain boundary region and the main phase crystal grain ２ The number of particles is MB in the neodymium iron boron magnet I. ２ The ratio of the number of grains to the number of grains is more than 10%, and the MB in the two-grain grain boundary region ２ The number of particles is MB in the neodymium iron boron magnet I. ２ The proportion of particles in the total number exceeds 5%. The content of M in the neodymium iron boron magnet I is 0.1 wt% to 1.5 wt%, and the content refers to the mass percentage of the element in the neodymium iron boron magnet I. Neodymium iron boron magnet I characterized by the above.

2. MB in the triangular grain boundary region ２ The number of particles is MB in the neodymium iron boron magnet I. ２ the proportion of particles by number is between 50% and 80%, for example 68%, 74%, or 78%, and / or MB in the two-grain grain boundary region and the main phase grain ２ The number of particles is MB in the neodymium iron boron magnet I. ２ the proportion of particles by number is between 20% and 50%, for example 22%, 26% or 32%, and / or The content of M is preferably 0.1 wt % to 1 wt %, for example 0.4 wt %, and the content means the mass percentage of the element in the neodymium iron boron magnet I; and / or The Zr content is preferably 0 to 1 wt %, for example 0.4 wt %, where the content means the mass percentage of the element in the NdFeB magnet I; and / or The Nb content is preferably 0 to 1 wt %, for example 0.4 wt %, where the content means the mass percentage of the element in the NdFeB magnet I; and / or The Ti content is preferably 0 to 1 wt %, for example 0.4 wt %, where the Ti content is the mass percentage of the element in the NdFeB magnet I; and / or The MB ２ The particle shape may be, for example, one or more of a sphere, a needle, a rod, and a sheet, preferably a rod and / or a sheet; and / or The MB ２ When the particle shape is spherical or sheet-like, the MB ２ The particle size is preferably less than 500 nm, more preferably less than 200 nm, and / or The neodymium iron boron magnet I contains the following components: RL: 24 wt% to 33 wt%, RL is a light rare earth element, and the RL contains Nd, 0.7 wt% to 1.2 wt% B, 0.1 wt% to 1 wt% M, and the balance is Fe; Here, the neodymium iron boron magnet I preferably contains T, where T is one or more selected from Cu, Al, and Ga; Here, the content of T is preferably 0 to 2.1 wt %, and the content means the mass percentage of the element in the neodymium iron boron magnet I. Here, the Cu content is preferably 0 to 0.7 wt %, for example 0.2 wt %, and the Cu content refers to the mass percentage of the element in the NdFeB magnet I. Here, the Al content is preferably 0 to 0.7 wt %, for example 0.08 wt %, and the Al content refers to the mass percentage of the element in the neodymium iron boron magnet I. Here, the Ga content is preferably 0 to 0.7 wt %, for example 0.19 wt %, and the Ga content refers to the mass percentage of the element in the NdFeB magnet I. Here, the neodymium iron boron magnet I preferably further contains Co, Here, the Co content is preferably 0 to 2 wt %, for example 1 wt %, and the Co content refers to the mass percentage of the element in the NdFeB magnet I. Here, it is preferable that the neodymium iron boron magnet I further contains Dy and / or Tb, Here, the Dy content is preferably 0 to 1.5 wt %, more preferably 0.1 wt % to 0.15 wt %, for example 0.12 wt %, and the content refers to the mass percentage of the element in the neodymium iron boron magnet I. Here, the Tb content is preferably 0 to 1.5 wt %, more preferably 0.1 wt % to 0.15 wt %, for example 0.12 wt %, and the content refers to the mass percentage of the element in the neodymium iron boron magnet I. wherein the RL preferably comprises one or more of La, Ce, Pr, Sm, Gd, Ho, and Y; Here, the content of the RL is preferably 29 wt % to 32 wt %, for example 30.14 wt %, and the content means the mass percentage of the element in the NdFeB magnet I. Here, the content of B is preferably 0.8 wt% to 1.1 wt%, for example 0.96 wt%, and the content means the mass percentage of the element in the neodymium iron boron magnet I.

2. A neodymium iron boron magnet I according to claim 1.

3. 3. A method for producing a neodymium iron boron magnet I according to claim 1 or 2, comprising the steps of: The raw material is obtained after melting, smelting, casting, hydro-crushing, jet milling, press molding, sintering and aging, and the hydro-crushing process includes the steps of hydrogen absorption, dehydrogenation and cooling in order; The content of M in the raw material is 0.1 wt % to 1.5 wt %, the content being the mass percentage of the element in the raw material, and M being one or more selected from Nb, Zr, and Ti; A method for producing a neodymium-iron-boron magnet I.

4. The content of M is 0.1 wt % to 1 wt %, for example 0.4 wt %, and the content means the mass percentage of the element in the raw material; and / or The Zr content is 0-1 wt %, for example 0.4 wt %, where the content is the mass percentage of the element in the raw material; and / or The Nb content is 0-1 wt%, for example 0.4 wt%, where the content is the mass percentage of the element in the raw material; and / or The Ti content is 0-1 wt %, for example 0.4 wt %, where the content is the mass percentage of the element in the raw material; and / or The smelting temperature is 1500 to 1560°C, more preferably 1500 to 1540°C, and / or The vacuum degree of the melting and smelting is, for example, 5×10 －２ Pa, and / or The melting and smelting equipment is a high frequency vacuum induction melting furnace, and / or the casting temperature is between 1350 and 1560°C, preferably between 1420 and 1460°C; and / or the casting method is a strip casting method; and / or the thickness of the alloy flake obtained after the casting is 0.2 to 0.4 mm, for example 0.35 mm; and / or The pressure of the hydrogen absorption is 0.085 MPa, and / or the dehydrogenation temperature is between 450 and 550°C, and / or The dehydrogenation step includes a step of dehydrogenating under conditions of evacuation and elevated temperature, and / or The particle size of the powder obtained after the jet milling is 1 to 8 μm, and / or The jet mill treatment is carried out in an atmosphere having an oxidizing gas content of 20 to 50 ppm, where the oxidizing gas refers to oxygen and / or water vapor, and / or The pressure of the jet milling is 0.4 to 1 MPa, for example 0.68 MPa, and / or The magnetic field strength of the press molding is 0.7 to 2.5 T, for example 1.8 T, and / or The pressing is carried out under an inert atmosphere, for example under a nitrogen atmosphere, and / or the sintering temperature is between 900 and 1200°C, for example 1085°C, and / or The sintering time is between 3 and 24 hours, for example 6 hours, and / or The aging treatment includes a first stage aging treatment and a second stage aging treatment in sequence, wherein the temperature of the first stage aging treatment is preferably 600 to 980°C, for example, 900°C, and the temperature of the second stage aging treatment is preferably 400 to 600°C, for example, 520°C; and / or The raw material comprises the following components: RL: 24 wt% to 33 wt%, RL is a light rare earth element, and the RL contains Nd, 0.7 wt% to 1.2 wt% B, 0.1 wt% to 1 wt% M, and the balance is Fe; Here, the raw material preferably contains T, where T is one or more selected from Cu, Al, and Ga; Here, the content of T is preferably 0 to 2.1 wt %, and the content means the mass percentage of the element in the raw material; Here, the Cu content is preferably 0 to 0.7 wt %, for example 0.2 wt %, and the content means the mass percentage of the element in the raw material; Here, the content of Al is preferably 0 to 0.7 wt %, for example, 0.08 wt %, and the content means the mass percentage of the element in the raw material; Here, the Ga content is preferably 0 to 0.7 wt %, for example 0.19 wt %, and the content means the mass percentage of the element in the raw material; wherein the raw material preferably further contains Co, and the content of Co is preferably 0 to 2 wt%, for example 1 wt%, where the content means the mass percentage of the element in the raw material; Here, it is preferable that the raw material further contains Dy and / or Tb, wherein the Dy content is preferably 0 to 1.5 wt %, more preferably 0.1 wt % to 0.15 wt %, for example 0.12 wt %, the content being expressed as a mass percentage of the element in the raw material; wherein the Tb content is preferably 0 to 1.5 wt %, more preferably 0.1 wt % to 0.15 wt %, for example 0.12 wt %, the content being expressed as a mass percentage of the element in the raw material; wherein the RL preferably comprises one or more of La, Ce, Pr, Sm, Gd, Ho, and Y; Here, the content of the RL is preferably 29 wt % to 32 wt %, for example, 30.14 wt %, and the content means the mass percentage of the element in the raw material; Here, the content of B is preferably 0.8 wt % to 1.1 wt %, for example, 0.96 wt %, and the content means the mass percentage of the element in the raw material.

4. The method for producing a neodymium-iron-boron magnet I according to claim 3.

5. Produced by the method for producing a neodymium-iron-boron magnet I according to claim 3 or 4. Neodymium iron boron magnet I characterized by the above.

6. Neodymium iron boron magnet II, The neodymium iron boron magnet II includes main phase crystal grains, triangular grain boundary regions, and two-grain grain boundary regions, and the surfaces of the main phase crystal grains include heavy rare earth shell layers, and MB is contained in all of the main phase crystal grains, the triangular grain boundary regions, the two-grain grain boundary regions, and the heavy rare earth shell layers. ２ particles, M being one or more selected from Nb, Zr, and Ti, and the content of M in the neodymium iron boron magnet II is 0.1 wt % to 1.5 wt %; N Ｃｅｌｌ ≧5%, and N Ｃｅｌｌ is the MB in the main phase grains and the heavy rare earth shell layer. ２ is the sum of the number of particles, Here, C ｓｈｅｌｌ / C ｃｏｒｅ ≧1.05, and C ｓｈｅｌｌ is the concentration of heavy rare earth in the heavy rare earth shell layer, and C ｃｏｒｅ is the concentration of heavy rare earth at the center of the main phase crystal grains, Neodymium iron boron magnet II.

7. N Ｃｅｌｌ ≧10%, preferably N Ｃｅｌｌ is 14%, 15%, 20% or 30%, and / or C ｓｈｅｌｌ / C ｃｏｒｅ is between 1.5 and 1.6, for example 1.52, 1.53, 1.54, or 1.58, and / or the thickness of the heavy rare earth shell layer is less than 1 μm, and / or The neodymium iron boron magnet II contains the following components: RL: 24 wt% to 33 wt%, RL is a light rare earth element, and said RL contains Nd, 0.7 wt% to 1.2 wt% B, 0.1 wt% to 1 wt% M and 0.1 wt% to 5 wt% RH, RH is a heavy rare earth element, and the balance is Fe; wherein RH is Dy and / or Tb; Here, the content of Dy is preferably 0.1 wt % to 3 wt %; Here, the content of Tb is preferably 0.1 wt% to 3 wt%.

7. The neodymium iron boron magnet II according to claim 6.

8. A method for producing a neodymium iron boron magnet II according to claim 6 or 7, The magnet is obtained by subjecting the neodymium-iron-boron magnet I according to any one of claims 1, 2 and 5 to a grain boundary diffusion treatment. A method for producing a neodymium iron boron magnet II.

9. The temperature of the grain boundary diffusion treatment is 800 to 1100°C, preferably 800 to 1000°C, for example 900°C, and / or The duration of the grain boundary diffusion treatment is 6 to 36 hours, preferably 12 to 36 hours, for example 10 hours, and / or The method further includes a step of heat-holding treatment after the grain boundary diffusion treatment, wherein the temperature of the heat-holding treatment is preferably 400 to 700°C, more preferably 400 to 600°C, for example 460°C, and the time of the heat-holding treatment is preferably 1 to 6 hours, more preferably 2 to 4 hours; and / or The diffusion source of the grain boundary diffusion treatment is a diffusion source containing Dy and / or Tb, and the weight increase of the diffusion source is 0.1 to 1%, for example, 0.6%.

9. The method for producing a neodymium iron boron magnet II according to claim 8.

10. Produced by the method for producing a neodymium iron boron magnet II according to claim 8 or 9. Neodymium iron boron magnet II.

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