Neodymium-iron-boron magnet material and preparation method and application thereof

Abstract

The invention discloses a neodymium-iron-boron magnet material and a preparation method and application thereof. The preparation method of the neodymium-iron-boron magnet material comprises the following steps that S1, a main alloy raw material composition and an auxiliary alloy raw material composition are smelted and cast, and a main alloy sheet and an auxiliary alloy sheet are obtained; s2, the main alloy sheet and the auxiliary alloy sheet are mixed and then subjected to hydrogen decrepitation, and coarse powder is obtained; or the main alloy sheet and the auxiliary alloy sheet are subjected to hydrogen decrepitation to obtain main alloy coarse powder and auxiliary alloy coarse powder, and the main alloy coarse powder and the auxiliary alloy coarse powder are mixed to obtain coarse powder; then, the coarse powder is subjected to jet milling, and fine powder is obtained; s3, pressing the fine powder to obtain a green body; s4, sintering the green body to obtain a neodymium iron boron matrix; and S5, carrying out grain boundary diffusion on the neodymium iron boron substrate. The neodymium-iron-boron magnet material disclosed by the invention has excellent magnetic performance and can have ultrahigh residual magnetism and high coercive force at the same time.

Description

Technical Field

[0001] The invention relates to a neodymium iron boron magnet material and a preparation method and application thereof. Background Art

[0002] Sintered NdFeB permanent magnets are widely used due to their ultra-high energy density, earning them the nickname "King of Magnets." Their high magnetic energy density, excellent temperature resistance, and excellent cost-effectiveness have led to their widespread application in my country's pillar industries and emerging sectors, such as rail transit, military equipment, wind power generation, low-altitude flight, artificial intelligence, aerospace, medical devices, and precision manufacturing. With the trend toward miniaturization, lightweighting, efficiency, and intelligent devices across various fields, the performance requirements of rare earth permanent magnets are increasing. The development of ultra-high-performance magnets has become a key focus of industry development, and the development of dual-high remanence magnets with both ultra-high remanence and high coercivity is becoming an increasingly popular topic. However, few dual-high magnets have been certified by authoritative organizations and publicly reported. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defect of existing magnetic materials that cannot achieve both ultra-high remanence and high coercivity, and to provide a neodymium iron boron magnet material, its preparation method, and application. The neodymium iron boron magnet material described in the present invention has excellent magnetic properties and can achieve both ultra-high remanence and high coercivity.

[0004] In order to achieve the above objectives, the present invention adopts the following technical solutions.

[0005] In a first aspect, the present invention provides a method for preparing a neodymium iron boron magnet material, comprising the following steps:

[0006] S1. Melting and casting the main alloy raw material composition and the auxiliary alloy raw material composition respectively to obtain a main alloy sheet and an auxiliary alloy sheet;

[0007] S2. Mixing the main alloy sheet and the auxiliary alloy sheet and then hydrogen-crushing them to obtain a coarse powder; or hydrogen-crushing the main alloy sheet and the auxiliary alloy sheet separately to obtain a main alloy coarse powder and a auxiliary alloy coarse powder, and mixing the main alloy coarse powder and the auxiliary alloy coarse powder to obtain a coarse powder;

[0008] Then, the coarse powder is subjected to air jet milling to obtain fine powder;

[0009] S3, pressing the fine powder to obtain a green body;

[0010] S4, sintering the green body to obtain a NdFeB matrix;

[0011] S5, performing grain boundary diffusion on the NdFeB matrix to obtain the NdFeB magnet material;

[0012] Wherein, the main alloy raw material composition includes the following components:

[0013] R: 25.0-30.0 mass%, wherein R is a rare earth element, and R includes PrNd and Nd; the contents of PrNd and Nd satisfy the following: 0.03≤PrNd / (PrNd+Nd)≤0.84;

[0014] M: 0-3.0 mass%. Wherein, the content of M is not 0, and M includes Al, Cu, Ga, and X; the contents of Al, Cu, and Ga satisfy the following conditions: 0 mass.%<Al+Cu+Ga≤0.46 mass.%, and Al<Cu≤Ga; X includes one or more of Ti, Zr, Nb, W, and Mo;

[0015] B: 0.87-1.02mass.%;

[0016] and the balance of Fe and unavoidable impurities; mass.% represents the mass percentage of the total mass of the main alloy raw material composition;

[0017] Wherein, the auxiliary alloy raw material composition includes the following components:

[0018] R: 21.0-26.5 mass%., wherein R is a rare earth element, including Nd;

[0019] M: 0-3.0 mass%. Wherein, the content of M is not 0, and M includes Al, Cu, Ga, and X; the contents of Al, Cu, and Ga satisfy: 0 mass.%<Al+Cu+Ga≤0.46 mass.%, and Al<Ga<Cu; X includes one or more of Ti, Zr, Nb, W, and Mo;

[0020] B: 0.9-1.06mass.%;

[0021] and the balance of Fe and unavoidable impurities; mass.% represents the mass percentage of the total mass of the auxiliary alloy raw material composition;

[0022] Furthermore, the mass ratio of the main alloy raw material composition to the auxiliary alloy raw material composition is (75-95): (5-25).

[0023] In the present invention, “PrNd / (PrNd+Nd)” represents the ratio of the PrNd content to the “sum of the PrNd and Nd contents”.

[0024] In the present invention, "Al+Cu+Ga" refers to the sum of the contents of Al, Cu and Ga.

[0025] In the present invention, “Al<Cu≤Ga” represents the magnitude relationship among the Al content, the Cu content, and the Ga content.

[0026] In the present invention, the PrNd may be a conventional PrNd alloy in the art. The mass ratio of the Pr element to the Nd element in the PrNd may be (10-25):(75-90), for example, 10:90, 20:80, or 25:75.

[0027] In some embodiments of the present invention, in the main alloy raw material composition, the R further comprises one or more of Dy, Tb, Pr, Y and Ho.

[0028] In some embodiments of the present invention, in the main alloy raw material composition, M further comprises Co; the content of Co is 0.1-0.9 mass%., preferably 0.6-0.9 mass%., for example, 0.78 mass%. or 0.8 mass%.

[0029] In some embodiments of the present invention, in the main alloy raw material composition, the content of R is 28.0-29.5 mass%., for example, 29.28 mass%, 29.30 mass%. or 29.4 mass%.

[0030] In some embodiments of the present invention, in the main alloy raw material composition, the content of M is 1.0-2.0 mass%., for example, 1.40 mass%, 1.41 mass%. or 1.42 mass%.

[0031] In some embodiments of the present invention, in the main alloy raw material composition, the contents of PrNd and Nd satisfy: 0.05≤PrNd / (PrNd+Nd)≤0.15.

[0032] In some specific embodiments of the present invention, in the main alloy raw material composition, the contents of PrNd and Nd satisfy: PrNd / (PrNd+Nd)=0.08 or 0.09.

[0033] In some embodiments of the present invention, the contents of Al, Cu and Ga in the main alloy raw material composition satisfy the following relationship: 0.35 mass.%≤Al+Cu+Ga≤0.40 mass.%.

[0034] In some specific embodiments of the present invention, the contents of Al, Cu and Ga in the main alloy raw material composition satisfy the following ratio: Al+Cu+Ga=0.37 mass%.

[0035] In some embodiments of the present invention, the content of Al in the main alloy raw material composition is 0-0.05 mass%., for example, 0.01 mass%.

[0036] In some embodiments of the present invention, the master alloy stock composition includes a first master alloy stock composition and a second master alloy stock composition;

[0037] The first main alloy raw material composition and the second main alloy raw material composition each independently comprise the following components:

[0038] R: 25.0-30.0 mass%, wherein R is a rare earth element, and R includes PrNd and Nd; the contents of PrNd and Nd satisfy the following: 0.03≤PrNd / (PrNd+Nd)≤0.84;

[0039] M: 0-3.0 mass%. Wherein, the content of M is not 0, and M includes Al, Cu, Ga, and X; the contents of Al, Cu, and Ga satisfy the following conditions: 0 mass.%<Al+Cu+Ga≤0.46 mass.%, and Al<Cu≤Ga; X includes one or more of Ti, Zr, Nb, W, and Mo;

[0040] B: 0.87-1.02mass.%;

[0041] And the balance of Fe and inevitable impurities;

[0042] Mass.% represents the mass percentage of the total mass of the first main alloy raw material composition or the second main alloy raw material composition.

[0043] In some embodiments of the present invention, the mass ratio of the first main alloy raw material composition to the second main alloy raw material composition is 1:(5-15), for example, 8:83 or 10:79.

[0044] In some embodiments of the present invention, the contents of PrNd and Nd in the first main alloy raw material composition satisfy the following ratio: 0.05≤PrNd / (PrNd+Nd)≤0.20.

[0045] In some preferred embodiments of the present invention, the contents of PrNd and Nd in the first main alloy raw material composition satisfy the following ratio: 0.15≤PrNd / (PrNd+Nd)≤0.20.

[0046] In some preferred embodiments of the present invention, the contents of PrNd and Nd in the first main alloy raw material composition satisfy the following ratio: PrNd / (PrNd+Nd)=0.15.

[0047] In some preferred embodiments of the present invention, the content of R in the first main alloy raw material composition is 25.0-28.5 mass%. For example, 28.3 mass%.

[0048] In some preferred embodiments of the present invention, the Nd content in the first main alloy raw material composition is 23.0-25.0 mass%. For example, 24.0 mass%.

[0049] In some preferred embodiments of the present invention, the content of PrNd in the first main alloy raw material composition is 3.0-5.0 mass%., for example, 4.3 mass%.

[0050] In some embodiments of the present invention, the content of B in the first main alloy raw material composition is 0.89-1.02 mass%. For example, 0.98 mass%.

[0051] In some embodiments of the present invention, in the first main alloy raw material composition, the R further comprises one or more of Dy, Tb, Pr, Y and Ho.

[0052] In some embodiments of the present invention, the content of M in the first main alloy raw material composition is 1.0-2.0 mass%., for example, 1.25 mass%.

[0053] In some preferred embodiments of the present invention, in the first main alloy raw material composition, the M further comprises Co, and the content of the Co is 0.1-0.6 mass%.

[0054] In some embodiments of the present invention, the contents of Al, Cu and Ga in the first main alloy raw material composition satisfy the following conditions: 0.35 mass.%≤Al+Cu+Ga≤0.40 mass.%, for example, 0.39 mass.%.

[0055] In some embodiments of the present invention, the content of Al in the first main alloy raw material composition is 0.01-0.03 mass%. For example, 0.03 mass%.

[0056] In some embodiments of the present invention, the content of Cu in the first main alloy raw material composition is 0.1-0.2 mass%. For example, 0.16 mass%.

[0057] In some embodiments of the present invention, the Ga content in the first main alloy raw material composition is 0.1-0.3 mass%. For example, 0.2 mass%.

[0058] In some embodiments of the present invention, the content of X in the first main alloy raw material composition is 0.1-0.3 mass%. For example, 0.26 mass%.

[0059] In some embodiments of the present invention, in the first main alloy raw material composition, X includes Ti and / or Zr.

[0060] In some embodiments of the present invention, in the first main alloy raw material composition, X comprises Ti; wherein the content of Ti is preferably 0.05-0.1 mass%., for example, 0.09 mass%.

[0061] In some embodiments of the present invention, in the first main alloy raw material composition, X includes Zr; wherein the content of Zr is preferably 0.15-0.2 mass%., for example, 0.17 mass%.

[0062] In some embodiments of the present invention, in the first main alloy raw material composition, X includes Ti and Zr; wherein the content of Ti is 0.05-0.1 mass %; and the content of Zr is 0.15-0.2 mass %.

[0063] In some specific embodiments of the present invention, in the first main alloy raw material composition, X includes Ti and Zr; wherein the content of Ti is 0.09 mass.%; and the content of Zr is 0.17 mass.%.

[0064] In some embodiments of the present invention, the first main alloy raw material composition includes the following components:

[0065] PrNd: 3.0-5.0 mass.%;

[0066] Nd: 23.0-25.0 mass.%;

[0067] Al: 0.01-0.03 mass.%;

[0068] Cu: 0.1-0.2 mass.%;

[0069] Ga: 0.1-0.3 mass.%;

[0070] Co: 0.1-0.6 mass.%;

[0071] Ti: 0.05-0.1 mass.%;

[0072] Zr: 0.15-0.2 mass.%;

[0073] B: 0.89-1.02 mass.%;

[0074] Fe: 67.0-75.0 mass.%;

[0075] The mass.% is the percentage of the total weight of the first main alloy raw material composition.

[0076] In some specific embodiments of the present invention, the first main alloy raw material composition includes the following components:

[0077] PrNd: 4.3 mass.%;

[0078] Nd: 24.0 mass.%;

[0079] Al: 0.03 mass.%;

[0080] Cu: 0.16 mass.%;

[0081] Ga: 0.2 mass.%;

[0082] Co: 0.6 mass.%;

[0083] Ti: 0.09 mass.%;

[0084] Zr: 0.17 mass.%;

[0085] B:0.98 mass.%;

[0086] Fe: 69.47 mass.%;

[0087] The mass.% is the percentage of the total weight of the first main alloy raw material composition.

[0088] In some embodiments of the present invention, the contents of PrNd and Nd in the second main alloy raw material composition satisfy the following relationship: 0.05≤PrNd / (PrNd+Nd)≤0.20.

[0089] In some embodiments of the present invention, the contents of PrNd and Nd in the second main alloy raw material composition satisfy the following relationship: 0.05≤PrNd / (PrNd+Nd)≤0.10.

[0090] In some specific embodiments of the present invention, the contents of PrNd and Nd in the second main alloy raw material composition satisfy the following ratio: PrNd / (PrNd+Nd)=0.08.

[0091] In some embodiments of the present invention, the content of R in the second main alloy raw material composition is 27.0-30.0 mass%. For example, 29.4 mass%.

[0092] In some embodiments of the present invention, the Nd content in the second main alloy raw material composition is 26.0-27.0 mass%. For example, 27.0 mass%.

[0093] In some embodiments of the present invention, the content of PrNd in the second main alloy raw material composition is 1.0-2.5 mass%. For example, 2.4 mass%.

[0094] In some embodiments of the present invention, the content of B in the second main alloy raw material composition is 0.87-1.0 mass%. For example, 0.98 mass%.

[0095] In some embodiments of the present invention, in the second main alloy raw material composition, the R further comprises one or more of Dy, Tb, Pr, Y and Ho.

[0096] In some embodiments of the present invention, the content of M in the second main alloy raw material composition is 1.0-2.0 mass%., for example, 1.42 mass%.

[0097] In some embodiments of the present invention, in the second main alloy raw material composition, the M further comprises Co, and the content of the Co is 0.1-0.9 mass%. Preferably, the content of the Co is 0.7-0.9 mass%. For example, 0.8 mass%.

[0098] In some embodiments of the present invention, the contents of Al, Cu and Ga in the second main alloy raw material composition satisfy the following conditions: 0.35 mass.%≤Al+Cu+Ga≤0.40 mass.%, for example, 0.37 mass.%.

[0099] In some embodiments of the present invention, the content of Al in the second main alloy raw material composition is 0-0.05 mass%. Preferably, it is 0.01-0.03 mass%. For example, 0.01 mass%.

[0100] In some embodiments of the present invention, the content of Cu in the second main alloy raw material composition is 0.1-0.2 mass%. For example, 0.16 mass%.

[0101] In some embodiments of the present invention, the Ga content in the second main alloy raw material composition is 0.1-0.3 mass%. For example, 0.2 mass%.

[0102] In some embodiments of the present invention, the content of X in the second main alloy raw material composition is 0.1-0.3 mass%. For example, 0.25 mass%.

[0103] In some embodiments of the present invention, in the second main alloy raw material composition, X includes Ti and / or Zr.

[0104] In some embodiments of the present invention, in the second main alloy raw material composition, X comprises Ti; wherein the content of Ti is preferably 0.05-0.1 mass%., for example, 0.06 mass%.

[0105] In some embodiments of the present invention, in the second main alloy raw material composition, X includes Zr; wherein the content of Zr is preferably 0.15-0.2 mass%., for example, 0.19 mass%.

[0106] In some embodiments of the present invention, in the second main alloy raw material composition, X includes Ti and Zr; wherein the content of Ti is 0.05-0.1 mass %; and the content of Zr is 0.15-0.2 mass %.

[0107] In some specific embodiments of the present invention, in the second main alloy raw material composition, X includes Ti and Zr; wherein the content of Ti is 0.06 mass.%; and the content of Zr is 0.19 mass.%.

[0108] In some embodiments of the present invention, the second main alloy raw material composition includes the following components:

[0109] PrNd: 1.0-2.5 mass.%;

[0110] Nd: 26.0-27.0 mass.%;

[0111] Al: 0.01-0.03 mass.%;

[0112] Cu: 0.1-0.2 mass.%;

[0113] Ga: 0.1-0.3 mass.%;

[0114] Co: 0.7-0.9 mass.%;

[0115] Ti: 0.05-0.1 mass.%;

[0116] Zr: 0.15-0.2 mass.%;

[0117] B: 0.87-1.0 mass.%;

[0118] Fe: 65.0-73.0 mass.%;

[0119] The mass.% is the percentage of the total weight of the second main alloy raw material composition.

[0120] In some specific embodiments of the present invention, the second main alloy raw material composition includes the following components:

[0121] PrNd: 2.4 mass.%;

[0122] Nd: 27.0 mass.%;

[0123] Al: 0.01 mass.%;

[0124] Cu: 0.16 mass.%;

[0125] Ga: 0.2 mass.%;

[0126] Co: 0.8 mass.%;

[0127] Ti: 0.06 mass.%;

[0128] Zr: 0.19 mass.%;

[0129] B:0.98 mass.%;

[0130] Fe: 68.2 mass.%;

[0131] The mass.% is the percentage of the total weight of the second main alloy raw material composition.

[0132] In some embodiments of the present invention, in the auxiliary alloy raw material composition, M further comprises Co; the content of Co is 0.1-0.5 mass%., for example, 0.2 mass%, 0.26 mass%, or 0.4 mass%.

[0133] In some embodiments of the present invention, in the auxiliary alloy raw material composition, the content of R is 23.5-26.3 mass%., for example, 24.1 mass%, 24.72 mass%, or 26.2 mass%.

[0134] In some embodiments of the present invention, in the auxiliary alloy raw material composition, the content of M is 0.80-1.20 mass%., for example, 0.85 mass%, 0.89 mass%. or 1.00 mass%.

[0135] In some embodiments of the present invention, the contents of Al, Cu, and Ga in the auxiliary alloy raw material composition satisfy the following relationship: 0.30 mass.%≤Al+Cu+Ga≤0.40 mass.%.

[0136] In some specific embodiments of the present invention, the contents of Al, Cu and Ga in the auxiliary alloy raw material composition satisfy the following ratio: Al+Cu+Ga=0.33 mass%, 0.36 mass% or 0.37 mass%.

[0137] In some embodiments of the present invention, the content of Al in the auxiliary alloy raw material composition is 0.05-0.10 mass%., for example, 0.05 mass%, 0.06 mass%, or 0.07 mass%.

[0138] In some embodiments of the present invention, the auxiliary alloy raw material composition includes a first auxiliary alloy raw material composition and a second auxiliary alloy raw material composition;

[0139] Wherein, the first auxiliary alloy raw material composition includes the following components:

[0140] R: 21.0-24.5 mass%., wherein R is a rare earth element, including Nd;

[0141] M: 0-3.0 mass%. Wherein, the content of M is not 0, and M includes Al, Cu, Ga, and X; the contents of Al, Cu, and Ga satisfy: 0 mass.%<Al+Cu+Ga≤0.46 mass.%, and Al<Ga<Cu; X includes one or more of Ti, Zr, Nb, W, and Mo;

[0142] B: 0.93-1.06mass.%;

[0143] and the balance of Fe and unavoidable impurities; mass.% represents the mass percentage of the total mass of the first auxiliary alloy raw material composition;

[0144] Wherein, the second auxiliary alloy raw material composition includes the following components:

[0145] R: 23.0-26.5 mass%., wherein R is a rare earth element, including Nd;

[0146] M: 0-3.0 mass%. Wherein, the content of M is not 0, and M includes Al, Cu, Ga, and X; the contents of Al, Cu, and Ga satisfy: 0 mass.%<Al+Cu+Ga≤0.46 mass.%, and Al<Ga<Cu; X includes one or more of Ti, Zr, Nb, W, and Mo;

[0147] B: 0.91-1.04mass.%;

[0148] and the balance of Fe and unavoidable impurities; mass.% represents the mass percentage of the total mass of the second auxiliary alloy raw material composition.

[0149] In some embodiments of the present invention, the mass ratio of the first auxiliary alloy raw material composition to the second auxiliary alloy raw material composition is (1-5):1, for example, 12:5.

[0150] In some preferred embodiments of the present invention, the Nd content in the first auxiliary alloy raw material composition is 21.0-24.5 mass%. For example, 24.1 mass%.

[0151] In some embodiments of the present invention, in the first auxiliary alloy raw material composition, the R further comprises one or more of Dy, Tb, Pr, Y and Ho.

[0152] In some embodiments of the present invention, the content of M in the first auxiliary alloy raw material composition is 0.5-1.0 mass%., for example, 0.85 mass%.

[0153] In some preferred embodiments of the present invention, in the first auxiliary alloy raw material composition, M further comprises Co, and the content of Co is 0.1-0.3 mass%., for example, 0.2 mass%.

[0154] In some embodiments of the present invention, the contents of Al, Cu and Ga in the first auxiliary alloy raw material composition satisfy the following conditions: 0.35 mass.%≤Al+Cu+Ga≤0.40 mass.%, for example, 0.37 mass.%.

[0155] In some embodiments of the present invention, the content of Al in the first auxiliary alloy raw material composition is 0.01-0.10 mass%. For example, 0.07 mass%.

[0156] In some embodiments of the present invention, the content of Cu in the first auxiliary alloy raw material composition is 0.1-0.3 mass%. For example, 0.2 mass%.

[0157] In some embodiments of the present invention, the Ga content in the first auxiliary alloy raw material composition is 0.05-0.15 mass%. For example, 0.1 mass%.

[0158] In some embodiments of the present invention, the content of X in the first auxiliary alloy raw material composition is 0.1-0.3 mass%. For example, 0.28 mass%.

[0159] In some embodiments of the present invention, in the first auxiliary alloy raw material composition, X includes Ti and / or Zr.

[0160] In some embodiments of the present invention, in the first auxiliary alloy raw material composition, X comprises Ti; wherein the content of Ti is preferably 0.1-0.2 mass%., for example, 0.15 mass%.

[0161] In some embodiments of the present invention, in the first auxiliary alloy raw material composition, X includes Zr; wherein the content of Zr is preferably 0.1-0.2 mass%., for example, 0.13 mass%.

[0162] In some embodiments of the present invention, in the first auxiliary alloy raw material composition, X includes Ti and Zr; wherein the content of Ti is 0.1-0.2 mass %; and the content of Zr is 0.1-0.2 mass %.

[0163] In some specific embodiments of the present invention, in the first auxiliary alloy raw material composition, X includes Ti and Zr; wherein the content of Ti is 0.15 mass.%; and the content of Zr is 0.13 mass.%.

[0164] In some embodiments of the present invention, the first auxiliary alloy raw material composition includes the following components:

[0165] Nd: 21.0-24.5 mass.%;

[0166] Al: 0.01-0.10 mass.%;

[0167] Cu: 0.1-0.3 mass.%;

[0168] Ga: 0.05-0.15 mass.%;

[0169] Co: 0.1-0.3 mass.%;

[0170] Ti: 0.1-0.2 mass.%;

[0171] Zr: 0.1-0.2 mass.%;

[0172] B: 0.93-1.06 mass.%;

[0173] Fe: 72.0-75.0 mass.%;

[0174] The mass.% is the percentage of the total weight of the first auxiliary alloy raw material composition.

[0175] In some specific embodiments of the present invention, the first auxiliary alloy raw material composition includes the following components:

[0176] Nd: 24.1 mass.%;

[0177] Al: 0.07 mass.%;

[0178] Cu: 0.2 mass.%;

[0179] Ga: 0.1 mass.%;

[0180] Co: 0.2 mass.%;

[0181] Ti: 0.15 mass.%;

[0182] Zr: 0.13 mass.%;

[0183] B:0.99 mass.%;

[0184] Fe: 74.06 mass.%;

[0185] The mass.% is the percentage of the total weight of the first auxiliary alloy raw material composition.

[0186] In some preferred embodiments of the present invention, the Nd content in the second auxiliary alloy raw material composition is 23.0-26.5 mass%. For example, 26.2 mass%.

[0187] In some embodiments of the present invention, in the second auxiliary alloy raw material composition, the R further comprises one or more of Dy, Tb, Pr, Y and Ho.

[0188] In some embodiments of the present invention, the content of M in the second auxiliary alloy raw material composition is 0.5-1.0 mass%., for example, 1.0 mass%.

[0189] In some preferred embodiments of the present invention, in the second auxiliary alloy raw material composition, M further comprises Co, and the content of Co is 0.35-0.5 mass%., for example, 0.4 mass%.

[0190] In some embodiments of the present invention, the contents of Al, Cu and Ga in the second auxiliary alloy raw material composition satisfy the following conditions: 0.30 mass.%≤Al+Cu+Ga≤0.35 mass.%, for example, 0.33 mass.%.

[0191] In some embodiments of the present invention, the content of Al in the second auxiliary alloy raw material composition is 0.01-0.10 mass%. For example, 0.05 mass%.

[0192] In some embodiments of the present invention, the content of Cu in the second auxiliary alloy raw material composition is 0.1-0.3 mass%. For example, 0.18 mass%.

[0193] In some embodiments of the present invention, the Ga content in the second auxiliary alloy raw material composition is 0.05-0.15 mass%. For example, 0.1 mass%.

[0194] In some embodiments of the present invention, the content of X in the second auxiliary alloy raw material composition is 0.1-0.3 mass%. For example, 0.27 mass%.

[0195] In some embodiments of the present invention, in the second auxiliary alloy raw material composition, X includes Ti and / or Zr.

[0196] In some embodiments of the present invention, in the second auxiliary alloy raw material composition, X comprises Ti; wherein the content of Ti is preferably 0.1-0.2 mass%., for example, 0.12 mass%.

[0197] In some embodiments of the present invention, in the second auxiliary alloy raw material composition, X includes Zr; wherein the content of Zr is preferably 0.1-0.2 mass%., for example, 0.15 mass%.

[0198] In some embodiments of the present invention, in the second auxiliary alloy raw material composition, X includes Ti and Zr; wherein the content of Ti is 0.1-0.2 mass %; and the content of Zr is 0.1-0.2 mass %.

[0199] In some specific embodiments of the present invention, in the second auxiliary alloy raw material composition, X includes Ti and Zr; wherein the content of Ti is 0.12 mass.%; and the content of Zr is 0.15 mass.%.

[0200] In some embodiments of the present invention, the second auxiliary alloy raw material composition includes the following components:

[0201] Nd: 23.0-26.5 mass.%;

[0202] Al: 0.01-0.10 mass.%;

[0203] Cu: 0.1-0.3 mass.%;

[0204] Ga: 0.05-0.15 mass.%;

[0205] Co: 0.35-0.5 mass.%;

[0206] Ti: 0.1-0.2 mass.%;

[0207] Zr: 0.1-0.2 mass.%;

[0208] B: 0.91-1.04 mass.%;

[0209] Fe: 68.0-72.0 mass.%;

[0210] The mass.% is the percentage of the total weight of the second auxiliary alloy raw material composition.

[0211] In some specific embodiments of the present invention, the second auxiliary alloy raw material composition includes the following components:

[0212] Nd: 26.2 mass.%;

[0213] Al: 0.05 mass.%;

[0214] Cu: 0.18 mass.%;

[0215] Ga: 0.1 mass.%;

[0216] Co: 0.4 mass.%;

[0217] Ti: 0.12 mass.%;

[0218] Zr: 0.15 mass.%;

[0219] B:0.99 mass.%;

[0220] Fe: 71.81 mass.%;

[0221] The mass.% is the percentage of the total weight of the second auxiliary alloy raw material composition.

[0222] In some preferred embodiments of the present invention, the main alloy raw material composition includes a first main alloy raw material composition and a second main alloy raw material composition, wherein:

[0223] The first main alloy raw material composition includes the following components:

[0224] PrNd: 3.0-5.0 mass.%;

[0225] Nd: 23.0-25.0 mass.%;

[0226] Al: 0.01-0.03 mass.%;

[0227] Cu: 0.1-0.2 mass.%;

[0228] Ga: 0.1-0.3 mass.%;

[0229] Co: 0.1-0.6 mass.%;

[0230] Ti: 0.05-0.1 mass.%;

[0231] Zr: 0.15-0.2 mass.%;

[0232] B: 0.89-1.02 mass.%;

[0233] Fe: 67.0-75.0 mass.%;

[0234] The mass.% is the percentage of the total weight of the first main alloy raw material composition;

[0235] The second main alloy raw material composition includes the following components:

[0236] PrNd: 1.0-2.5 mass.%;

[0237] Nd: 26.0-27.0 mass.%;

[0238] Al: 0.01-0.03 mass.%;

[0239] Cu: 0.1-0.2 mass.%;

[0240] Ga: 0.1-0.3 mass.%;

[0241] Co: 0.7-0.9 mass.%;

[0242] Ti: 0.05-0.1 mass.%;

[0243] Zr: 0.15-0.2 mass.%;

[0244] B: 0.87-1.0 mass.%;

[0245] Fe: 65.0-73.0 mass.%;

[0246] The mass.% is the percentage of the total weight of the second main alloy raw material composition;

[0247] Furthermore, the mass ratio of the first main alloy raw material composition, the second main alloy composition and the auxiliary alloy raw material composition is (8-10): (79-83): (9-11).

[0248] In some specific embodiments of the present invention, the main alloy raw material composition includes a first main alloy raw material composition and a second main alloy raw material composition, wherein:

[0249] The first main alloy raw material composition includes the following components:

[0250] PrNd: 4.3 mass.%;

[0251] Nd: 24.0 mass.%;

[0252] Al: 0.03 mass.%;

[0253] Cu: 0.16 mass.%;

[0254] Ga: 0.2 mass.%;

[0255] Co: 0.6 mass.%;

[0256] Ti: 0.09 mass.%;

[0257] Zr: 0.17 mass.%;

[0258] B:0.98 mass.%;

[0259] Fe: 69.47 mass.%;

[0260] The mass.% is the percentage of the total weight of the first main alloy raw material composition;

[0261] The second main alloy raw material composition includes the following components:

[0262] PrNd: 2.4 mass.%;

[0263] Nd: 27.0 mass.%;

[0264] Al: 0.01 mass.%;

[0265] Cu: 0.16 mass.%;

[0266] Ga: 0.2 mass.%;

[0267] Co: 0.8 mass.%;

[0268] Ti: 0.06 mass.%;

[0269] Zr: 0.19 mass.%;

[0270] B:0.98 mass.%;

[0271] Fe: 68.2 mass.%;

[0272] The mass.% is the percentage of the total weight of the second main alloy raw material composition;

[0273] The auxiliary alloy raw material composition includes the following components:

[0274] Nd: 24.1 mass.%;

[0275] Al: 0.07 mass.%;

[0276] Cu: 0.2 mass.%;

[0277] Ga: 0.1 mass.%;

[0278] Co: 0.2 mass.%;

[0279] Ti: 0.15 mass.%;

[0280] Zr: 0.13 mass.%;

[0281] B:0.99 mass.%;

[0282] Fe: 74.06 mass.%;

[0283] The mass.% is the percentage of the total weight of the auxiliary alloy raw material composition;

[0284] Furthermore, the mass ratio of the first main alloy raw material composition, the second main alloy composition, and the auxiliary alloy raw material composition is 8:83:9.

[0285] In some specific embodiments of the present invention, the main alloy raw material composition includes a first main alloy raw material composition and a second main alloy raw material composition, wherein:

[0286] The first main alloy raw material composition includes the following components:

[0287] PrNd: 4.3 mass.%;

[0288] Nd: 24.0 mass.%;

[0289] Al: 0.03 mass.%;

[0290] Cu: 0.16 mass.%;

[0291] Ga: 0.2 mass.%;

[0292] Co: 0.6 mass.%;

[0293] Ti: 0.09 mass.%;

[0294] Zr: 0.17 mass.%;

[0295] B:0.98 mass.%;

[0296] Fe: 69.47 mass.%;

[0297] The mass.% is the percentage of the total weight of the first main alloy raw material composition;

[0298] The second main alloy raw material composition includes the following components:

[0299] PrNd: 2.4 mass.%;

[0300] Nd: 27.0 mass.%;

[0301] Al: 0.01 mass.%;

[0302] Cu: 0.16 mass.%;

[0303] Ga: 0.2 mass.%;

[0304] Co: 0.8 mass.%;

[0305] Ti: 0.06 mass.%;

[0306] Zr: 0.19 mass.%;

[0307] B:0.98 mass.%;

[0308] Fe: 68.2 mass.%;

[0309] The mass.% is the percentage of the total weight of the second main alloy raw material composition;

[0310] The auxiliary alloy raw material composition includes the following components:

[0311] Nd: 26.2 mass.%;

[0312] Al: 0.05 mass.%;

[0313] Cu: 0.18 mass.%;

[0314] Ga: 0.1 mass.%;

[0315] Co: 0.4 mass.%;

[0316] Ti: 0.12 mass.%;

[0317] Zr: 0.15 mass.%;

[0318] B:0.99 mass.%;

[0319] Fe: 71.81 mass.%;

[0320] The mass.% is the percentage of the total weight of the auxiliary alloy raw material composition;

[0321] Furthermore, the mass ratio of the first main alloy raw material composition, the second main alloy composition, and the auxiliary alloy raw material composition is 10:79:11.

[0322] In some preferred embodiments of the present invention, the auxiliary alloy raw material composition includes a first auxiliary alloy raw material composition and a second auxiliary alloy raw material composition, wherein:

[0323] The first auxiliary alloy raw material composition includes the following components:

[0324] The mass.% is the percentage of the total weight of the first auxiliary alloy raw material composition;

[0325] The second auxiliary alloy raw material composition includes the following components:

[0326] The mass.% is the percentage of the total weight of the second auxiliary alloy raw material composition;

[0327] Furthermore, the mass ratio of the first auxiliary alloy raw material composition, the second auxiliary alloy raw material composition and the main alloy raw material composition is (1-10):(9-20):(70-90), for example, 5:12:83.

[0328] In the present invention, in step S1, the smelting and the casting can be performed in a conventional manner in the art, and can be performed in a continuous furnace.

[0329] In the present invention, in step S1, the smelting and the casting can be performed in a conventional manner in the art, and can be performed in a continuous furnace.

[0330] In some embodiments of the present invention, in step S1, the smelting temperature is 1400-1500°C, for example, 1445°C, 1451°C, 1459°C or 1466°C.

[0331] In some embodiments of the present invention, in step S1, the casting process parameters include: copper roller speed 20-30r / min, supercooling 160-180°C, casting flow 140-145cm 3 / s.

[0332] In some specific embodiments of the present invention, in step S1, the casting process parameters include: copper roller speed 28r / min, supercooling 170°C, casting flow 140.3cm 3 / s.

[0333] In some specific embodiments of the present invention, in step S1, after the casting is completed, the temperature is cooled to 40-60°C, for example, 45°C.

[0334] In some embodiments of the present invention, in step S1, the thickness of the main alloy sheet is 0.20-0.30 mm, for example, 0.26 mm, 0.27 mm or 0.28 mm.

[0335] In some embodiments of the present invention, in step S1, the columnar crystal width of the main alloy sheet is 1.0-4.0 μm, preferably 2.0-3.0 μm, such as 2.7 μm, 2.8 μm or 2.9 μm.

[0336] In some embodiments of the present invention, in step S1, the thickness of the auxiliary alloy sheet is 0.20-0.30 mm, for example, 0.25 mm, 0.26 mm or 0.27 mm.

[0337] In some embodiments of the present invention, in step S1, the columnar crystal width of the auxiliary alloy flakes is 1.0-4.0 μm, preferably 2.0-3.0 μm, such as 2.5 μm or 2.6 μm.

[0338] In some embodiments of the present invention, step S1 further includes: performing a gas atomization treatment on the master alloy sheet using PrNd. The gas atomization treatment can fill and repair the rare earth elements at the grain boundaries of the master alloy sheet to a certain extent, thereby achieving both a main phase with an ultra-high main phase volume fraction and a relatively continuous grain boundary phase structure in the first alloy sheet. This can significantly reduce the risk of powder oxidation during subsequent pulverization and prevent subsequent densification failures during sintering.

[0339] Preferably, the atomization treatment comprises: performing physical vapor deposition on the main alloy sheet using PrNd; the temperature of the physical vapor deposition is 600-800° C., and the time of the physical vapor deposition is 4-20 hours.

[0340] Preferably, after the gas atomization treatment, the PrNd weight gain of the main alloy sheet is 0.5%-1.0%, for example 0.75%. The PrNd weight gain refers to the percentage of the mass increase of PrNd in the main alloy sheet after the gas atomization treatment to the mass of the main alloy sheet before the gas atomization treatment.

[0341] In some embodiments of the present invention, step S1 further includes: performing a gas atomization treatment on the auxiliary alloy sheet using Nd.

[0342] Preferably, the atomization treatment comprises: performing physical vapor deposition on the auxiliary alloy sheet using Nd; the temperature of the physical vapor deposition is 600-800° C., and the time of the physical vapor deposition is 4-20 hours.

[0343] Preferably, after the gas atomization treatment, the Nd weight gain of the auxiliary alloy sheet is 1.0%-3.0%, for example, 2.48%. The Nd weight gain refers to the percentage of the mass increase of Nd in the auxiliary alloy sheet after the gas atomization treatment to the mass of the auxiliary alloy sheet before the gas atomization treatment.

[0344] In the present invention, in step S2, the hydrogen cracking can be performed using a continuous hydrogen cracking furnace.

[0345] In some embodiments of the present invention, in step S2, the reaction pressure of the hydrogen cracking is 0.08-0.1 MPa, for example, 0.098 MPa.

[0346] In some embodiments of the present invention, in step S2, during the hydrogen cracking process, the temperature of the dehydrogenation treatment is 500-600°C, for example, 570°C.

[0347] In the present invention, in step S2, the air flow milling can be performed using a multi-nozzle opposing fluidized bed air flow mill.

[0348] In some specific embodiments of the present invention, in step S2, the parameter settings of the air jet mill include: the classifying wheel gap maintains the disc cleaning pressure of 70 kPa, the classifying wheel speed is 3490 r / min, the grinding chamber mass is 58 kg, the grinding pressure is 0.57 MPa, and the side spray pressure is 25 kPa.

[0349] In some embodiments of the present invention, in step S2, a powder additive is added to the coarse powder.

[0350] Preferably, the powder additive is added in an amount of 1.7 g per kg of coarse powder.

[0351] In some embodiments of the present invention, in step S2, a powder additive is added to the fine powder.

[0352] Preferably, the powder additive is added in an amount of 0.8 g per kg of coarse powder.

[0353] In some embodiments of the present invention, in step S2, a powder additive is added to the coarse powder before the jet milling, and a powder additive is added to the fine powder obtained by the jet milling.

[0354] In some embodiments of the present invention, the powder additive is added via an online dosing system.

[0355] In some specific embodiments of the present invention, the average particle size SMD of the fine powder obtained by the jet mill is 2.0-2.5 μm, for example, 2.2 μm.

[0356] In the present invention, adding powder additives during the airflow milling process is a conventional operation in the field, which can prevent particle agglomeration, control particle size distribution, improve grinding efficiency, reduce equipment wear, protect the grinding cavity, prevent oxidation or hydrolysis, improve product stability, and improve downstream process adaptability.

[0357] In the present invention, in step S3, the pressing can be performed in a conventional manner in the art.

[0358] In some embodiments of the present invention, in step S3, the pressing is performed using an all-electric floating press and a modular mold.

[0359] In some embodiments of the present invention, in step S3, the pressing comprises orientation pressing.

[0360] Among them, preferably, the process parameters of the orientation pressing include: pressing orientation direction dimension 55mm, pressing blank gram weight 780g, mold forming position minimum orientation field >1.95T, and the oxygen content throughout the pressing process is less than 50ppm.

[0361] In some embodiments of the present invention, in step S3, pre-pressing is further included before the orientation pressing.

[0362] Preferably, the pre-pressing is a two-stage pre-pressing, including:

[0363] The first section: pre-pressed density is 2.2g / cm 3 , suppressing current 20A;

[0364] Second stage: pre-pressed density 3.0 g / cm 3 , suppressing current 100A.

[0365] Preferably, the orientation pressing satisfies: pressing density 4.0 g / cm 3 , suppressing current 210A.

[0366] Preferably, the holding time of the orientation pressing is 1-3s, for example, 2s.

[0367] In some embodiments of the present invention, in step S3, the pressing further comprises isostatic pressing.

[0368] Preferably, the isostatic pressing pressure is 200 MPa.

[0369] In the present invention, in step S4, the sintering can be performed in a conventional manner in the art.

[0370] In some embodiments of the present invention, in step S4, the sintering uses one or more of a high-density graphite box, a molybdenum box, a tungsten box, and a carbon ceramic box; preferably, the sintering uses a combination box of a high-density graphite box and a molybdenum box.

[0371] In some embodiments of the present invention, in step S4, the sintering uses a high-density graphite box and a molybdenum box combination box.

[0372] In some embodiments of the present invention, in step S4, the sintering is performed in a gradient temperature increase manner.

[0373] In some embodiments of the present invention, in step S4, the sintering process includes: keeping warm at 100-300°C, 350-450°C, 550-600°C, 620-680°C, 700-780°C, 810-980°C and 1000-1200°C respectively.

[0374] Preferably, the holding time at 1000-1200°C is 4-15h.

[0375] In some specific embodiments of the present invention, in step S4, the sintering process includes: keeping warm at 250°C, 420°C, 580°C, 640°C, 760°C, 830°C and 1085°C, with the keeping time being 1.5h, 2.5h, 1.5h, 2.5h, 2h, 3h and 9h respectively.

[0376] In some embodiments of the present invention, in step S4, the heating rate during the sintering process is 1-3°C / min, for example, 1.5°C / min.

[0377] In some embodiments of the present invention, in step S4, aging treatment is further performed after sintering, wherein preferably, the aging treatment is a two-stage aging treatment.

[0378] In some embodiments of the present invention, the two-stage aging treatment comprises: keeping at 880-930° C. for 3-10 hours, and then keeping at 450-550° C. for 3-10 hours.

[0379] In some specific embodiments of the present invention, the two-stage aging treatment includes: keeping at 905° C. for 3 hours and then keeping at 505° C. for 5 hours.

[0380] In the present invention, in step S5, the grain boundary diffusion can be performed using conventional methods in the art.

[0381] In some embodiments of the present invention, in step S5, the grain boundary diffusion operation includes: applying a diffusion source to the surface of the NdFeB substrate and performing heat treatment.

[0382] In some embodiments of the present invention, the applying method is screen printing, spraying or magnetron sputtering.

[0383] In some embodiments of the present invention, the grain boundary diffusion is performed using a staged heat treatment process.

[0384] In some embodiments of the present invention, in step S5, the grain boundary diffusion is performed using a staged heat treatment process, including:

[0385] The first stage: the holding temperature is 880-950℃, and the holding time is 5-36h;

[0386] The second stage: the insulation temperature is 450-550℃ and the time is 3-10h.

[0387] In some specific embodiments of the present invention, in step S5, the staged heat treatment process for grain boundary diffusion includes:

[0388] The first stage: keep the temperature at 900℃, 908℃, 916℃ and 905℃ for 4h, 4h, 3h and 5h respectively; after the temperature is kept at 900℃, 908℃, 916℃ and 905℃ respectively; cool the temperature to below 70℃ with argon air;

[0389] The second stage: heat to 505℃ and keep warm for 5h.

[0390] In some embodiments of the present invention, in step S5, the vacuum degree during the grain boundary diffusion process is controlled to be 10 -1 -10 -4 Pa.

[0391] In some embodiments of the present invention, in step S5, the diffusion source of the grain boundary diffusion includes a heavy rare earth element RH, and the RH includes Dy and / or Tb.

[0392] In some embodiments of the present invention, the mass of the heavy rare earth element RH in the diffusion source accounts for 0.1-0.8 mass %, for example, 0.5 mass %, of the NdFeB matrix.

[0393] In some embodiments of the present invention, the diffusion source is one or more of a simple substance, a fluoride, a hydride, and an alloy of RH.

[0394] In some specific embodiments of the present invention, the diffusion source is TbH.

[0395] In some specific embodiments of the present invention, the diffusion source is a (Tb-Co-Fe-Cu-PrNd)H alloy; wherein the mass ratio of Tb, Co, Fe, Cu and PrNd is 76:4:4:8:8.

[0396] In some specific embodiments of the present invention, the diffusion source is (Tb-Fe-Cu-PrNd)H, wherein the mass ratio of Tb, Fe, Cu and PrNd is 75:5:10:10.

[0397] In some specific embodiments of the present invention, the diffusion source is (Tb-Fe-Co-Cu)H, wherein the mass ratio of Tb, Fe, Co and Cu is 82:4:4:10.

[0398] In some specific embodiments of the present invention, the diffusion source is (Tb-Co-Fe-Cu-PrNd)H, wherein the mass ratio of Tb, Co, Fe, Cu and PrNd is 76:4:4:8:8.

[0399] In some specific embodiments of the present invention, the diffusion source is (Tb-Fe-Co-PrNd)H, wherein the mass ratio of Tb, Fe, Co and PrNd is 82:4:4:10.

[0400] In some specific embodiments of the present invention, the diffusion source is (Tb-Cu-PrNd)H, wherein the mass ratio of Tb, Cu and PrNd is 80:10:10.

[0401] In a second aspect, the present invention provides a NdFeB magnet material, which is prepared using the method for preparing the NdFeB magnet material as described above.

[0402] In some embodiments of the present invention, the volume fraction of the main phase grains in the NdFeB magnet material is greater than 96%, for example, 96.8%, 97.1% or 97.8%.

[0403] In some embodiments of the present invention, the carbon content in the NdFeB magnet material is ≤520 ppm, the oxygen content is ≤350 ppm, and the nitrogen content is ≤200 ppm.

[0404] In a third aspect, the present invention further provides a use of the aforementioned NdFeB magnet material as a magnetic device.

[0405] The NdFeB magnet material is used as a magnetic device in many fields such as rail transportation, military equipment, wind power generation, low-altitude flight, artificial intelligence, aerospace, medical equipment, precision manufacturing, etc.

[0406] In the present invention, the symbols of each element have conventional meanings in the art, specifically: "Pr" for praseodymium, "Nd" for neodymium, "Dy" for dysprosium, "Tb" for terbium, "Y" for yttrium, "Ho" for holmium, "Al" for aluminum, "Cu" for copper, "Ga" for gallium, "Co" for cobalt, "Ti" for titanium, "Zr" for zirconium, "Nb" for niobium, "W" for tungsten, "Mo" for molybdenum, "Fe" for iron, and "B" for boron.

[0407] In the present invention, unless otherwise specified, an element appearing alone means a simple substance of the element.

[0408] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0409] The reagents and raw materials used in the present invention are commercially available.

[0410] The positive progress effect of the present invention is:

[0411] This invention utilizes a primary-auxiliary alloy process and a specially formulated primary and auxiliary alloy to achieve a further breakthrough in the performance of NdFeB magnet materials. This NdFeB magnet material boasts a high volume fraction of primary phase grains (over 96%), significantly reduced levels of impurity elements such as carbon, oxygen, and nitrogen, and exhibits excellent magnetic properties, combining ultra-high remanence with high coercivity. Specifically, the remanence can reach over 14.9 kGs, the coercivity over 20.5 kOe, and an Hk / Hcj ratio over 96%. DETAILED DESCRIPTION

[0412] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0413] Example 1

[0414] S1. Melting and Casting

[0415] (1) Preparation of the first main alloy sheet: The raw material components of the first main alloy sheet were weighed and mixed according to Table 1, smelted in a continuous furnace at 1451°C, and cast on a copper roller (copper roller speed 28 r / min, undercooling 170°C, casting flow rate 140.3 cm 3 / s), cooled to 45°C and taken out of the furnace to obtain a first main alloy sheet. The specific thickness and columnar crystal width of the first main alloy sheet are shown in Table 2; the first main alloy sheet is placed in a sealed stainless steel barrel, fully deoxygenated with argon gas, and then sealed for standby use.

[0416] The first master alloy sheet was subjected to gas atomization treatment. Physical vapor deposition of a PrNd alloy (Pr:Nd in a ratio of 20:80) was performed at 690°C for 8 hours, resulting in a PrNd weight gain of 0.75%. The PrNd weight gain refers to the percentage of PrNd mass increase in the first master alloy sheet after gas atomization compared to the mass of the first master alloy sheet before gas atomization. Gas atomization can fill and repair the grain boundaries of the first master alloy sheet to a certain extent.

[0417] (2) Preparation of the Second Main Alloy Sheet: The raw materials for the second main alloy sheet were weighed according to Table 1. Except for a melting temperature of 1445°C, the remaining steps and conditions were the same as for the preparation of the first main alloy sheet. The specific thickness and columnar crystal width of the second main alloy sheet are shown in Table 2.

[0418] (3) Preparation of the auxiliary alloy flakes: The raw material components of the auxiliary alloy flakes were weighed according to Table 1. Except for the melting temperature of 1466°C and the gas atomization step, the remaining steps and conditions were the same as those for the preparation of the first main alloy flake. The specific thickness and columnar crystal width of the auxiliary alloy flakes are shown in Table 2.

[0419] Gas atomization treatment of the auxiliary alloy sheet: Nd was physically vapor deposited on the auxiliary alloy sheet at 690°C for 12 hours. The Nd weight of the auxiliary alloy sheet increased by 2.48% (the mass increase of Nd in the auxiliary alloy sheet after gas atomization treatment accounts for the mass percentage of the auxiliary alloy sheet before gas atomization treatment), and the grain boundaries of the auxiliary alloy sheet were filled and repaired to a certain extent.

[0420] S2, flour making

[0421] (1) Hydrogen rupture:

[0422] The obtained first main alloy sheet, second main alloy sheet, and auxiliary alloy sheet were subjected to hydrogen cracking treatment in a continuous hydrogen cracking furnace at a reaction pressure of 0.098 MPa and 570°C for dehydrogenation. After cooling to below 40°C, they were removed from the furnace in a fully sealed manner to obtain first main alloy coarse powder, second main alloy coarse powder, and auxiliary alloy coarse powder, respectively. The first main alloy coarse powder, second main alloy coarse powder, and auxiliary alloy coarse powder were mixed in a mass ratio of 8:83:9 to obtain coarse powder. The coarse powder was loaded into a coarse powder tank that had been fully deoxygenated to below 50 ppm in advance and filled with argon gas to maintain pressure.

[0423] Powder additives were added to the obtained coarse powder. The powder additives consisted of Tianjin agent, Yuesheng agent (purchased from Tianjin Yuesheng New Materials Research Institute, model YSH-01), Dongyang agent (purchased from Dongyang Antai Magnetic Materials Co., Ltd., YKJ-10) and 120# gasoline in a mass ratio of 1:1:1.8. The addition ratio was 1.7 g of powder additive per kg of coarse powder, and the mixed powder was stirred for 120 minutes.

[0424] (2) Jet mill:

[0425] A multi-nozzle, opposed-flow fluidized bed jet mill was used for grinding. First, the bottom material in the mill was completely blown out to prevent any impurities from entering. Argon was then used to fully deoxygenate the mill to below 2 ppm before the coarse powder was loaded. The mill was then started, with key parameters set to maintain a cleaning pressure of 70 kPa for the separation wheel gap, a separation wheel speed of 3490 rpm, a mill chamber mass of 58 kg, a grinding pressure of 0.57 MPa, and a side spray pressure of 25 kPa. A highly spherical fine powder with an average particle size (SMD) of approximately 2.2 μm was produced. The main phase of the fine powder produced by this process exhibited a high degree of rare earth-rich coating.

[0426] During the grinding process, an online dosing system is used to add powder additives (with the same composition as the aforementioned powder additives) to the fine powder receiving tank at a ratio of 0.8 g of powder additive per kg of fine powder, and the powders are mixed and stirred for 120 minutes.

[0427] The fine powder after air jet milling is screened, and the oxygen content during the whole screening process is less than 50ppm.

[0428] S3, Suppression

[0429] A fully electric floating press and a combined mold are used to orient the fine powder. The pressing orientation direction dimension is 55mm, the pressed blank weighs 780g, the minimum orientation field at the mold forming position is >1.95T, and the oxygen content during the entire pressing process is <50ppm.

[0430] The pressing process adopts a two-stage pre-pressing and pre-orientation process design, with the pre-pressing density of 2.2g / cm 3 , pressing current 20A, and pre-pressing density 3.0 g / cm 3, pressing current 100A; then start pressing, pressing density 4.0 g / cm 3 , pressing current 210A, and appropriately extending the holding pressure orientation time (holding pressure orientation time is 2s) to obtain a higher orientation degree.

[0431] The obtained compact was isostatically pressed at a pressure of 200 MPa.

[0432] S4, sintering

[0433] A high-density graphite box and a molybdenum box are used for sintering. Before use, the blank obtained in step S3 is placed in the box and evacuated. The temperature is raised at a rate of approximately 1.5°C / min, and the blanks are kept at 250°C, 420°C, 580°C, 640°C, 760°C, 830°C, and 1085°C for 1.5 hours, 2.5 hours, 1.5 hours, 2.5 hours, 2 hours, 3 hours, and 9 hours, respectively. After sintering, two-stage aging treatments are performed in vacuum (905°C for 3 hours and 505°C for 5 hours) to obtain the NdFeB matrix.

[0434] S5, Grain Boundary Diffusion

[0435] The NdFeB substrate was processed into a 30*12*3.5mm sample and surface activated by degreasing and ultrasonic cleaning. A diffusion film was then attached to the NdFeB substrate using screen printing. The diffusion film had a composition of (Tb-Co-Fe-Cu-PrNd)H (where the mass ratio of Tb, Co, Fe, Cu, and PrNd was 76:4:4:8:8), with Tb accounting for 0.5 mass% of the NdFeB substrate.

[0436] Diffusion is carried out using a staged heat treatment process, specifically:

[0437] The first stage: keep the temperature at 900℃, 908℃, 916℃ and 905℃ for 4h, 4h, 3h and 5h respectively; after the temperature is kept at 900℃, 908℃, 916℃ and 905℃ respectively; cool the temperature to below 70℃ with argon air;

[0438] The second stage: heating to 505°C, keeping the temperature for 5 hours, cooling to below 60°C with nitrogen, and taking out of the furnace to obtain NdFeB magnet material.

[0439] Example 2

[0440] S1. Melting and Casting

[0441] (1) Preparation of main alloy sheet: According to Table 1, the raw material components of the main alloy sheet were weighed and mixed, smelted in a continuous furnace at 1445°C, and cast on a copper roller (copper roller speed 28 r / min, supercooling degree 170°C, casting flow rate 140.3 cm3 / s), cooled to 45℃ and taken out of the furnace to obtain a main alloy sheet. The specific thickness and columnar crystal width of the main alloy sheet are shown in Table 2; the main alloy sheet is placed in a sealed stainless steel barrel, fully deoxygenated with argon gas, and then sealed for standby use.

[0442] (2) Preparation of the first auxiliary alloy sheet: The raw material components of the first auxiliary alloy sheet were weighed according to Table 1, smelted in a continuous furnace at 1466°C, and cast on a copper roller (copper roller speed 28 r / min, supercooling 170°C, casting flow 140.3 cm 3 / s), cooled to 45°C and taken out of the furnace to obtain the first auxiliary alloy sheet. The specific thickness and columnar crystal width of the first auxiliary alloy sheet are shown in Table 2.

[0443] Gas atomization treatment of the first auxiliary alloy sheet: Nd was physically vapor deposited on the first auxiliary alloy sheet at 690°C for 12 hours, and the Nd weight of the first auxiliary alloy sheet increased by 2.48% (the mass increase of Nd in the first auxiliary alloy sheet after gas atomization treatment accounts for the percentage of the mass of the first auxiliary alloy sheet before gas atomization treatment), and the grain boundaries of the first auxiliary alloy sheet were filled and repaired to a certain extent.

[0444] (3) Preparation of the Second Auxiliary Alloy Flake: Weigh the raw materials for the first auxiliary alloy flake according to Table 1. Except for a melting temperature of 1459°C, the remaining steps and conditions are the same as for the preparation of the first auxiliary alloy flake. The specific thickness and columnar crystal width of the second auxiliary alloy flake are shown in Table 2.

[0445] S2, flour making

[0446] (1) Hydrogen cracking: The main alloy sheet, the first auxiliary alloy sheet, and the second auxiliary alloy sheet were subjected to hydrogen cracking treatment in a continuous hydrogen cracking furnace, respectively, with a reaction pressure of 0.098 MPa and a dehydrogenation treatment at 570°C. After cooling to below 40°C, they were taken out of the furnace in a fully sealed manner to obtain the main alloy coarse powder, the first auxiliary alloy coarse powder, and the second auxiliary alloy coarse powder. The main alloy coarse powder, the first auxiliary alloy coarse powder, and the second auxiliary alloy coarse powder were mixed in a mass ratio of 83:12:5 to obtain a mixed coarse powder; the mixed coarse powder was placed in a coarse powder tank that had been fully deoxygenated to below 50 pm in advance, and filled with argon to maintain pressure.

[0447] (2) Jet mill: Same as Example 1.

[0448] The operations and conditions of steps S3, S4 and S5 are the same as those in Example 1, and a NdFeB magnet material is obtained.

[0449] Example 3

[0450] S1. Melting and Casting

[0451] (1) Preparation of the first main alloy sheet: Weigh the raw material components of the first main alloy sheet according to Table 1. The remaining steps are the same as step S1 (1) of Example 1. The specific thickness and columnar crystal width of the first main alloy sheet are shown in Table 2.

[0452] (2) Preparation of the Second Main Alloy Sheet: The raw materials for the second main alloy sheet were weighed according to Table 1. Except for a melting temperature of 1445°C, the remaining steps and conditions were the same as for the preparation of the first main alloy sheet. The specific thickness and columnar crystal width of the second main alloy sheet are shown in Table 2.

[0453] (3) Preparation of the auxiliary alloy sheet: The raw material components of the auxiliary alloy sheet were weighed according to Table 1. Except for the melting temperature of 1459°C, the remaining steps and conditions were the same as those for the preparation of the first main alloy sheet. The specific thickness and columnar crystal width of the auxiliary alloy sheet are shown in Table 2.

[0454] S2, flour making

[0455] (1) Hydrogen rupture:

[0456] The obtained first main alloy sheet, second main alloy sheet, and auxiliary alloy sheet were subjected to hydrogen cracking treatment in a continuous hydrogen cracking furnace at a reaction pressure of 0.098 MPa and 570°C for dehydrogenation. After cooling to below 40°C, they were removed from the furnace in a fully sealed manner to obtain first main alloy coarse powder, second main alloy coarse powder, and auxiliary alloy coarse powder, respectively. The first main alloy coarse powder, second main alloy coarse powder, and auxiliary alloy coarse powder were mixed in a mass ratio of 10:79:11 to obtain a mixed coarse powder. The mixed coarse powder was placed in a coarse powder tank that had been fully deoxygenated to below 50 ppm in advance and filled with argon to maintain pressure.

[0457] (2) Jet mill: Same as Example 1.

[0458] S3, Suppression

[0459] Proceed in accordance with step S3 of Example 1.

[0460] S4, sintering

[0461] The process is carried out in accordance with step S4 of Example 1.

[0462] S5, Grain Boundary Diffusion

[0463] The NdFeB substrate was processed into a 30 x 12 x 3.5 mm sample and then surface activated by degreasing and ultrasonic cleaning. A diffusion film was then attached to the surface of the NdFeB substrate using screen printing. The diffusion film was composed of TbH, with Tb accounting for 0.5 mass% of the NdFeB substrate.

[0464] Diffusion is carried out using a staged heat treatment process, specifically:

[0465] The first stage: keep the temperature at 900℃, 908℃, 916℃ and 905℃ for 4h, 4h, 3h and 5h respectively; after the temperature is kept at 900℃, 908℃, 916℃ and 905℃ respectively; cool the temperature to below 70℃ with argon air;

[0466] The second stage: heating to 505°C, keeping the temperature for 5 hours, cooling to below 60°C with nitrogen, and taking out of the furnace to obtain NdFeB magnet material.

[0467] Example 4

[0468] The only difference from Example 3 is that in step S5 , the composition of the diffusion film layer is (Tb-Fe-Cu-PrNd)H, wherein the mass ratio of Tb, Fe, Cu and PrNd is 75:5:10:10.

[0469] Example 5

[0470] The only difference from Example 3 is that in step S5 , the composition of the diffusion film layer is (Tb-Fe-Co-Cu)H, wherein the mass ratio of Tb, Fe, Co and Cu is 82:4:4:10.

[0471] Example 6

[0472] The only difference from Example 3 is that in step S5 , the composition of the diffusion film layer is (Tb-Co-Fe-Cu-PrNd)H, wherein the mass ratio of Tb, Co, Fe, Cu and PrNd is 76:4:4:8:8.

[0473] Example 7

[0474] The only difference from Example 3 is that in step S5 , the composition of the diffusion film layer is (Tb—Fe—Co—PrNd)H, wherein the mass ratio of Tb, Fe, Co, and PrNd is 82:4:4:10.

[0475] Example 8

[0476] The only difference from Example 3 is that in step S5 , the composition of the diffusion film layer is (Tb—Cu—PrNd)H, wherein the mass ratio of Tb, Cu, and PrNd is 80:10:10.

[0477] Table 1 Content of each component in the raw material composition of NdFeB matrix (unit: mass%)

[0478]

[0479] Note: 1 The mass proportion of Pr in PrNd is 20%.

[0480] Table 2

[0481]

[0482] The columnar crystal width was tested as follows: After each alloy sheet was mounted, polished, and then microscopic photographs were taken using a scanning electron microscope (SEM). The columnar crystal width was analyzed and calculated using the streak method using ImageJ software. The results are shown in Table 2. As shown in Table 2, the alloy sheet thickness of the NdFeB magnet material prepared in this embodiment of the present invention was less than 0.3 mm, and the columnar crystal width did not exceed 3.0 μm.

[0483] Effect Example 1: Material Composition Determination and Structural Characterization

[0484] (1) Compositions of NdFeB magnet material (after diffusion) and NdFeB matrix (before diffusion)

[0485] The components of the NdFeB matrix (before diffusion) and the NdFeB magnet material (after diffusion) in Examples 1-8 were measured using a high-frequency inductively coupled plasma optical emission spectrometer (ICP-OES) using conventional methods in the art. The measurement results are shown in Tables 3 and 4, respectively.

[0486] Table 3 Content of each component in NdFeB matrix (mass%)

[0487]

[0488] Table 4 Content of each component of NdFeB magnet material (mass%)

[0489]

[0490] (2) Impurity element content test

[0491] The NdFeB magnet materials (after diffusion) obtained in Examples 1-8 were crushed into small particles, and carbon and oxygen and nitrogen were tested and analyzed using a carbon-sulfur analyzer CS-3000 (Steel Research Institute Nanotechnology) and an oxygen-nitrogen-hydrogen analyzer ONH836 (Shanghai Yuzhong Industrial Co., Ltd.). The test data are shown in Table 5 below.

[0492] Table 5

[0493]

[0494] As can be seen from Table 5, the contents of impurity elements carbon, oxygen, and nitrogen in the NdFeB magnet material prepared in the embodiment of the present invention are significantly reduced, with the carbon content being ≤520ppm, the oxygen content being ≤350ppm, and the nitrogen content being ≤200ppm. This is also one of the important factors for the significant improvement in magnetic properties Br and Hcj.

[0495] (3) Main phase grain volume fraction test

[0496] The volume fraction of the primary phase grains in the NdFeB matrix (before diffusion) and NdFeB magnet material (after diffusion) from Examples 1-8 were measured. The samples were ground and prepared, and X-ray spectroscopy was performed to obtain diffraction peak data. Image J was used to compare the primary phase grains, and the volume fraction of the primary phase grains in the samples was determined by analysis and processing. The test results are shown in Table 6.

[0497] Table 6

[0498]

[0499] As can be seen from Table 6, the volume fraction of the main phase grains in the NdFeB magnet material prepared in the embodiment of the present invention is higher. In addition, the volume fraction of the main phase grains in the material before and after diffusion does not change much.

[0500] Effect Example 2

[0501] The NdFeB matrix (before diffusion) and NdFeB magnet material (after diffusion) prepared in Examples 1-8 were processed into standard sample columns of ø10*10 mm, and magnetic properties were tested using NIM62000 at a constant temperature of 20°C. The test data are shown in Tables 7 and 8.

[0502] Table 7 Magnetic properties of NdFeB matrix

[0503]

[0504] Table 8 Magnetic properties of NdFeB magnet materials

[0505]

[0506] In Tables 7 and 8, "Br" represents remanence; Hcj represents intrinsic coercivity; and "Hk / Hcj" represents knee coercivity and intrinsic coercivity. Hk / Hcj is a quantitative indicator of squareness, reflecting the rectangularity of the demagnetization curve. The closer its value is to 100%, the stronger the irreversibility of magnetization reversal under a reverse magnetic field, the more stable the magnetic domains remain before the knee point (Hk), and the better the demagnetization resistance. As shown in Table 8, the NdFeB magnet material produced in the embodiment of the present invention can achieve a remanence of over 14.9 kGs, an intrinsic coercivity of over 20.5 kOe, and an Hk / Hcj ratio of over 96%.

[0507] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A method for preparing a neodymium iron boron magnet material, characterized in that: It includes the following steps: S1. Melting and casting the main alloy raw material composition and the auxiliary alloy raw material composition respectively to obtain a main alloy sheet and an auxiliary alloy sheet; S2. Mixing the main alloy sheet and the auxiliary alloy sheet and then hydrogen-crushing them to obtain a coarse powder; or hydrogen-crushing the main alloy sheet and the auxiliary alloy sheet separately to obtain a main alloy coarse powder and a auxiliary alloy coarse powder, and mixing the main alloy coarse powder and the auxiliary alloy coarse powder to obtain a coarse powder; Then, the coarse powder is subjected to air jet milling to obtain fine powder; S3, pressing the fine powder to obtain a green body; S4, sintering the green body to obtain a NdFeB matrix; S5, performing grain boundary diffusion on the NdFeB matrix to obtain the NdFeB magnet material; Wherein, the main alloy raw material composition includes the following components: R: 25.0-30.0 mass%, wherein R is a rare earth element, and R includes PrNd and Nd; the contents of PrNd and Nd satisfy the following: 0.03≤PrNd / (PrNd+Nd)≤0.84; M: 0-3.0 mass%. Wherein, the content of M is not 0, and M includes Al, Cu, Ga, and X; the contents of Al, Cu, and Ga satisfy the following conditions: 0 mass.%<Al+Cu+Ga≤0.46 mass.%, and Al<Cu≤Ga; X includes one or more of Ti, Zr, Nb, W, and Mo; B: 0.87-1.02mass.%; and the balance of Fe and unavoidable impurities; mass.% represents the mass percentage of the total mass of the main alloy raw material composition; Wherein, the auxiliary alloy raw material composition includes the following components: R: 21.0-26.5 mass%., wherein R is a rare earth element, including Nd; M: 0-3.0 mass%. Wherein, the content of M is not 0, and M includes Al, Cu, Ga, and X; the contents of Al, Cu, and Ga satisfy: 0 mass.%<Al+Cu+Ga≤0.46 mass.%, and Al<Ga<Cu; X includes one or more of Ti, Zr, Nb, W, and Mo; B: 0.9-1.06mass.%; and the balance of Fe and unavoidable impurities; mass.% represents the mass percentage of the total mass of the auxiliary alloy raw material composition; Furthermore, the mass ratio of the main alloy raw material composition to the auxiliary alloy raw material composition is (75-95): (5-25).

2. The method for preparing a NdFeB magnet material according to claim 1, wherein: The main alloy raw material composition satisfies one or more of the following conditions (1)-(7): (1) In the main alloy raw material composition, the R further comprises one or more of Dy, Tb, Pr, Y and Ho; (2) In the main alloy raw material composition, M also includes Co; the content of Co is 0.1-0.9 mass.%; (3) In the main alloy raw material composition, the content of R is 28.0-29.5 mass.%; (4) In the main alloy raw material composition, the content of M is 1.0-2.0 mass.%; (5) In the main alloy raw material composition, the contents of PrNd and Nd satisfy the following conditions: 0.05≤PrNd / (PrNd+Nd)≤0.15; (6) In the main alloy raw material composition, the contents of Al, Cu and Ga satisfy the following conditions: 0.35 mass.% ≤ Al+Cu+Ga ≤ 0.40 mass.%; (7) In the main alloy raw material composition, the Al content is 0-0.05 mass%.

3. The method for preparing a NdFeB magnet material according to claim 1, wherein: The auxiliary alloy raw material composition satisfies one or more of the following conditions (1)-(6): (1) In the auxiliary alloy raw material composition, the R further comprises one or more of PrNd, Dy, Tb and Pr; (2) In the auxiliary alloy raw material composition, M also includes Co; the content of Co is 0.1-0.5 mass.%; (3) In the auxiliary alloy raw material composition, the content of R is 23.5-26.3 mass.%; (4) In the auxiliary alloy raw material composition, the content of M is 0.80-1.20 mass.%; (5) In the auxiliary alloy raw material composition, the contents of Al, Cu and Ga satisfy the following conditions: 0.30 mass.% ≤ Al+Cu+Ga ≤ 0.40 mass.%; (6) In the auxiliary alloy raw material composition, the Al content is 0.05-0.10 mass%.

4. The method for preparing a NdFeB magnet material according to claim 1, wherein: The main alloy raw material composition includes a first main alloy raw material composition and a second main alloy raw material composition; The first main alloy raw material composition and the second main alloy raw material composition each independently comprise the following components: R: 25.0-30.0 mass%, wherein R is a rare earth element, and R includes PrNd and Nd; the contents of PrNd and Nd satisfy the following: 0.03≤PrNd / (PrNd+Nd)≤0.84; M: 0-3.0 mass%. Wherein, the content of M is not 0, and M includes Al, Cu, Ga, and X; the contents of Al, Cu, and Ga satisfy the following conditions: 0 mass.%<Al+Cu+Ga≤0.46 mass.%, and Al<Cu≤Ga; X includes one or more of Ti, Zr, Nb, W, and Mo; B: 0.87-1.02mass.%; And the balance of Fe and inevitable impurities; mass.% represents the mass percentage of the total mass of the first main alloy raw material composition or the second main alloy raw material composition; Furthermore, the mass ratio of the first main alloy raw material composition to the second main alloy raw material composition is 1:(5-15).

5. The method for preparing a NdFeB magnet material according to claim 1, wherein: The auxiliary alloy raw material composition includes a first auxiliary alloy raw material composition and a second auxiliary alloy raw material composition; Wherein, the first auxiliary alloy raw material composition includes the following components: R: 21.0-24.5 mass%., wherein R is a rare earth element, including Nd; M: 0-3.0 mass%. Wherein, the content of M is not 0, and M includes Al, Cu, Ga, and X; the contents of Al, Cu, and Ga satisfy: 0 mass.%<Al+Cu+Ga≤0.46 mass.%, and Al<Ga<Cu; X includes one or more of Ti, Zr, Nb, W, and Mo; B: 0.93-1.06mass.%; and the balance of Fe and unavoidable impurities; mass.% represents the mass percentage of the total mass of the first auxiliary alloy raw material composition; Wherein, the second auxiliary alloy raw material composition includes the following components: R: 23.0-26.5 mass%., wherein R is a rare earth element, including Nd; M: 0-3.0 mass%. Wherein, the content of M is not 0, and M includes Al, Cu, Ga, and X; the contents of Al, Cu, and Ga satisfy: 0 mass.%<Al+Cu+Ga≤0.46 mass.%, and Al<Ga<Cu; X includes one or more of Ti, Zr, Nb, W, and Mo; B: 0.91-1.04mass.%; and the balance of Fe and unavoidable impurities; mass.% represents the mass percentage of the total mass of the second auxiliary alloy raw material composition; Furthermore, the mass ratio of the first auxiliary alloy raw material composition to the second auxiliary alloy raw material composition is (1-5):

1.

6. The method for preparing a NdFeB magnet material according to claim 1, wherein: Step S1 further includes: performing a gas atomization treatment on the main alloy sheet using PrNd; wherein the gas atomization treatment includes: performing physical vapor deposition on the main alloy sheet using PrNd; the temperature of the physical vapor deposition is 600-800° C., and the time of the physical vapor deposition is 4-20 hours; wherein, after the gas atomization treatment, the PrNd weight gain of the main alloy sheet is 0.5%-1.0%; And / or, step S1 further includes: performing a gas atomization treatment on the auxiliary alloy sheet using Nd; wherein the gas atomization treatment includes: performing physical vapor deposition on the auxiliary alloy sheet using Nd; the temperature of the physical vapor deposition is 600-800° C., and the time of the physical vapor deposition is 4-20 hours; wherein, after the gas atomization treatment, the Nd weight gain of the auxiliary alloy sheet is 0.5%-1.0%; And / or, in step S3, the pressing includes orientation pressing; And / or, in step S4, the sintering uses a high-density graphite box and a molybdenum box combination box; And / or, in step S4, the sintering further includes a two-stage aging treatment.

7. The method for preparing a NdFeB magnet material according to claim 1, wherein: In step S5, the grain boundary diffusion is performed using a staged heat treatment process, including: The first stage: the holding temperature is 880-950℃, and the holding time is 5-36h; The second stage: the holding temperature is 450-550℃, and the holding time is 3-10h; And / or, the vacuum degree during the grain boundary diffusion process is controlled to be 10 -1 -10 -4 Pa; And / or, in step S5, the diffusion source of the grain boundary diffusion includes a heavy rare earth element RH, and the RH includes Dy and / or Tb.

8. A neodymium iron boron magnet material, characterized in that: The NdFeB magnet is prepared by the method for preparing the NdFeB magnet material according to any one of claims 1 to 7.

9. The NdFeB magnet material according to claim 8, characterized in that: The volume fraction of the main phase grains in the NdFeB magnet material is greater than 96%; And / or, the carbon content in the NdFeB magnet material is ≤520ppm, the oxygen content is ≤350ppm, and the nitrogen content is ≤200ppm.

10. Use of the NdFeB magnet material according to claim 8 or 9 as a magnetic device.

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