NEODYMIUM-IRON-BORON MAGNET MATERIAL, RAW MATERIAL COMPOSITION, PREPARATION METHOD THEREFOR AND USE THEREOF

Abstract

Disclosed are a neodymium-iron-boron magnet material, a raw material composition and a preparation method therefor and a use thereof. The raw material composition of the neodymium-iron-boron magnet material comprises the following components by mass percentage: 29.5-32% of R′, wherein R′ is a rare earth element and includes Pr and Nd; and Pr≥17.15%; Cu≥0.35%; 0.9-1.2% of B; 64-69.2% of Fe. The percentages refer to the mass percentages relative to the total mass of the raw material composition of the neodymium-iron-boron magnet material. Without the addition of a heavy rare earth element, the neodymium-iron-boron magnet material can still have a high remanence and coercive force.

Claims

1. A raw material composition of neodymium-iron-boron magnet material, wherein, the raw material composition of neodymium-iron-boron magnet material comprises the following components by mass percentage: 29.5-32% of R′, R′ is a rare earth element and includes Pr and Nd; wherein, Pr≥17.15%; Cu≥0.35%; 0.9-1.2% of B; 64-69.2% of Fe, the percentage refers to the mass percentage relative to the total mass of the raw material composition of neodymium-iron-boron magnet material.

2-10. (canceled)

11. The raw material composition according to claim 1, wherein, the content of Pr is 17.15-26%; or, the content of Pr is 18.15%, 19.15%, 20.15%, 20.85%, 21.15%, 22.15%, 23.15%, 24.15%, 25.15% or 26%.

12. The raw material composition according to claim 1, wherein, R′ further comprises RH, RH is heavy rare earth element, the kind of RH comprises one or more of Dy, Tb and Ho; the mass ratio of RH and R′ is preferably less than 0.253, the content of RH is 1-2.5%.

13. The raw material composition according to claim 1, wherein, the content of Cu is 0.35-1.3%.

14. The raw material composition according to claim 1, wherein, the raw material composition of neodymium-iron-boron magnet material further comprises Al; the content of Al is 3% or less; or, the raw material composition of neodymium-iron-boron magnet material further comprises Ga; the content of Ga is 1% or less; or, the raw material composition of neodymium-iron-boron magnet material further comprises Zr; the content of Zr is 0.3% or less; or, the raw material composition of neodymium-iron-boron magnet material further comprises Co; the content of Co is 0.2-1.5%; or, the raw material composition of neodymium-iron-boron magnet material further comprises one or more of Zn, Ag, In, Sn, V, Cr, Mo, Ta, Hf and W.

15. The raw material composition according to claim 1, wherein, the raw material composition comprises the following components by mass percentage: 29.5-32% of R′, R′ is a rare earth element and comprises Pr and Nd; wherein, Pr≥17.15%; Cu≥0.35%; Al≤0.5%; 0.25-0.3% of Zr; 0.9-1.2% of B; 64-69.2% of Fe.

16. The raw material composition according to claim 1, wherein, the raw material composition comprises the following components by mass percentage: 29.5-32% of R′, R′ is a rare earth element and comprises Pr and Nd; wherein, Pr≥17.15%; Cu≥0.35%; Al≤0.5%; Ga≤0.42%; 0.25-0.3% of Zr; 0.9-1.2% of B; 64-69.2% of Fe.

17. A preparation method for neodymium-iron-boron magnet material, wherein, the neodymium-iron-boron magnet material is prepared by using the raw material composition according to claim 1.

18. A preparation method for neodymium-iron-boron magnet material, wherein, the preparation method comprises the following steps: the molten liquid of the raw material composition according to claim 1 is subjected to melting and casting, hydrogen decrepitation, forming, sintering and ageing treatment.

19. A neodymium-iron-boron magnet material, wherein, the neodymium-iron-boron magnet material is prepared by the preparation method according to claim 17.

20. An application of the neodymium-iron-boron magnet material according to claim 19 as an electronic component in a motor.

21. A neodymium-iron-boron magnet material, wherein, the neodymium-iron-boron magnet material comprises the following components by mass percentage: 29.4-32.6% of R′, R′ comprises Pr and Nd; wherein, Pr≥17.14%; Cu≥0.34%; 0.9-1.2% of B; 64-69.2% of Fe; the percentage refers to the mass percentage relative to the total mass of the neodymium-iron-boron magnet material.

22. The neodymium-iron-boron magnet material according to claim 21, wherein, the content of Pr is 18.15-26.1%; or, the ratio of the mass of Nd to the total mass of R′ is less than 0.5.

23. The neodymium-iron-boron magnet material according to claim 21, wherein, R′ further comprises RH, RH is a heavy rare earth element, the kind of RH comprises one or more of Dy, Tb and Ho; the mass ratio of RH and R′ is preferably less than 0.253; wherein, the content of RH is 1-2.5%.

24. The neodymium-iron-boron magnet material according to claim 21, wherein, the content of Cu is 0.34-1.3%.

25. The neodymium-iron-boron magnet material according to claim 21, wherein, the neodymium-iron-boron magnet material further comprises Al; the content of Al is 0.5% or less; or, the neodymium-iron-boron magnet material further comprises Zr; the content of Zr is 0.05-0.31 wt. % by weight; or, the neodymium-iron-boron magnet material further comprises Ga; the content of Ga is 0.51% or less; or, the neodymium-iron-boron magnet material further comprises Co; the content of Co is 0.2-1.5%; or, the neodymium-iron-boron magnet material further comprises 0; the content of O is 0.13% or less; or, the neodymium-iron-boron magnet material may further comprise one or more of Zn, Ag, In, Sn, V, Cr, Mo, Ta, Hf and W.

26. An application of the neodymium-iron-boron magnet material according to claim 21 as an electronic component in a motor.

27. A neodymium-iron-boron magnet material, wherein, in the intergranular triangle region of the neodymium-iron-boron magnet material, the ratio of the total mass of Pr and Cu to the total mass of each element in the intergranular triangle region is Q1; at the grain boundary of the neodymium-iron-boron magnet material, the ratio of the total mass of Pr and Cu to the total mass of each element at the grain boundary is Q2; wherein, Q1<Q2, and Q2≥0.1.

28. The neodymium-iron-boron magnet material according to claim 27, wherein, the neodymium-iron-boron magnet material comprises the following components by mass percentage: 29.4-32.6% of R′, R′ comprises Pr and Nd; wherein, Pr≥17.14%; Cu≥0.34%; 0.9-1.2% of B; 64-69.2% of Fe; the percentage refers to the mass percentage relative to the total mass of the neodymium-iron-boron magnet material.

29. An application of the neodymium-iron-boron magnet material according to claim 27 as an electronic component in a motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0117] FIG. 1 is the distribution diagram of Pr, Nd, Cu, Ti, Co and O elements formed by the FE-EPMA face scan of the neodymium-iron-boron magnet material prepared in Example 10.

[0118] FIG. 2 is the distribution diagram of elements at the grain boundary of the neodymium-iron-boron magnet material in Example 10, and symbol 1 in FIG. 2 is the point taken in quantitative analysis at the grain boundary.

[0119] FIG. 3 is the distribution diagram of elements in the intergranular triangle of the neodymium-iron-boron magnet material in Example 10, and symbol 1 in FIG. 3 is the point taken in quantitative analysis at the grain boundary.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0120] The following examples further illustrate the present disclosure, but the present disclosure is not limited thereto. Experiment methods in which specific conditions are not indicated in the following embodiments are selected according to conventional methods and conditions, or according to the product specification. In the table below, wt. % refers to the mass percentage of the component in the raw material composition of the R-T-B permanent magnet material, and “/” indicates that the element has not been added. “Br” is the residual magnetic flux density and “Hcj” is the intrinsic coercivity.

[0121] The formulations for the raw material compositions of the neodymium-iron-boron magnet material in each Example and Comparative Example are shown in Table 1 below.

TABLE-US-00001 TABLE 1 The formulations for the raw material compositions of the neodymium-iron- boron magnet material in each Example and Comparative Example (wt. %) No. Nd Pr Dy Tb Ho Cu Al Ga Zr Co Zn Mo B Fe 1 12.35 17.15 / / / 0.35 / / / / / / 0.985 69.165 2 12.85 17.15 / / / 0.45 / / / / / / 0.985 68.565 3 12.35 18.15 / / / 0.5 / / / / / / 0.985 68.015 4 12.85 18.15 / / / 0.6 / / / / / / 0.985 67.415 5 12.35 19.15 / / / 0.65 / / / / / / 0.985 66.865 6 12.85 19.15 / / / 0.7 / / / / / / 0.985 66.315 7 11.35 20.15 / / / 0.8 / / / / / / 0.985 66.715 8 11.35 20.15 / / / 0.9 / / / / / / 0.985 66.615 9 10.85 21.15 / / / 1 / / / / / / 0.985 66.015 10 4 26 / / / 1.1 / / 0.1 0.2 / / 0.985 67.615 11 8.85 22.15 / / / 1.2 / / / / / / 0.985 66.815 12 5.85 25.15 0.3 0.7 / 0.5 0.03 / / / / / 0.985 66.485 13 5.85 25.15 / 1 / 0.7 0.1 / / / / / 0.985 66.215 14 5.85 24.15 0.2 1.8 / 0.9 0.2 / / / / / 0.985 65.915 15 5.85 24.15 / 2 / 1.1 0.25 / / / / / 0.985 65.665 16 8.85 22.15 0.2 0.8 / 1.2 / 0.1 / / / / 0.985 65.715 17 8.85 22.15 0   1 / 0.85 / 0.2 / / / / 0.985 65.965 18 7.85 23.15 0.1 0.9 / 0.65 / / 0.1 / / / 0.985 66.265 19 7.85 23.15 0.1 0.9 / 0.95 / / 0.25 / / / 0.985 65.815 20 12.35 18.15 / 1.5 / 1.05 / / / 1 0.985 64.965 21 10.85 19.15 0.1 1.9 / 0.8 0.1 0.1 / / / / 0.985 66.015 22 10.85 19.15 0.1 1.9 / 0.9 0.3 0.2 / / / / 0.985 65.615 23 12.35 18.15 / 1.5 / 0.5 /  0.25 0.22 / / / 0.985 66.045 24 12.35 18.15 / 1.5 / 0.6 / 0.1 0.28 / / / 0.985 66.035 25 9.85 19.15 0.1 1.9 / 1.2 0.2 / 0.25 / / / 0.985 66.365 26 9.85 19.15 0.1 1.9 / 0.8 0.4 / 0.3 / / / 0.985 66.515 27 8.85 22.15 0.1 0.9 / 0.9 0.3 / 0.26 / / / 1 65.54 28 5.85 25.15 0.2 0.8 / 1.2 0.46 / 0.29 / 0.985 65.065 29 5.85 25.15 0.3 0.7 / 1.1 0.48 / 0.3 / 0.985 65.135 30 9.85 19.15 0.1 1.9 / 0.6 0.2  0.15 0.2 / 0.985 66.865 31 8.85 22.15 0.3 0.7 / 0.8 0.3  0.18 0.25 / 0.985 65.485 32 6.85 24.15 / / / 0.8 0.4 0.2 0.27 / 1.1 66.23 33 6.85 24.15 / / / 0.9 0.45 0.2 0.28 / 1.2 65.93 34 9.85 19.15 / 2 / 0.4 0.1 0.1 0.25 0.985 67.165 35 6.85 24.15 / 1 / 0.5 0.25 0.1 0.3 0.985 65.865 36 12.35 17.15 0.7 0.02  0.25 0.25 0.985 68.295 37 12.35 17.15 1 0.8 0.02 0.3 0.25 0.985 67.145 38 8.85 22.15 0.3 0.7 0.9 0.03 0.4 0.28 0.985 65.405 39 8.85 22.15 0.3 0.7 1.1 0.03 0.5 0.3 0.985 65.085 40 8.85 20.15 0.3 0.7 1.0 0.8 0.3 0 0.25 / 0.04 0.08 0.985 66.545 41 8.85 20.15 0.3 0.7 1.0 0.9 0.3 0 0.25 / 0.08 0.04 0.985 66.445 42 6.85 24.15 / / 1.0 0.9 0.4 0 0.25 / 0.05 0.05 0.985 65.365 45 5.85 25.15 / 1 / 0.2 0.1 / / / / / 0.985 66.715 46 5.85 25.15 / 1 / 0.1 0.1 / / / / / 0.985 66.815 47 14.85 15.15 / 0.9 0.2 / / / / / 0.985 67.915 48 21.15 8.85 / 0.9 0.2 / / / / / 0.985 67.915

Example 1

[0122] The neodymium-iron-boron magnet material is prepared as follows:

[0123] (1) Melting and casting process: according to the formulation shown in Table 1, the prepared raw material was put into a crucible made of alumina and vacuum melted in a high frequency vacuum induction melting furnace and in a vacuum of 5×10.sup.−2 Pa at a temperature of 1500° C. or less. After the vacuum melting, Ar gas was introduced into the melting furnace to make the pressure of furnace reach 55,000 Pa, casting was carried out, and the quenched alloy was obtained at a cooling rate of 10.sup.2° C./sec to 10.sup.4° C./sec.

[0124] (2) Hydrogen decrepitation process: the melting furnace in which the quench alloy was placed was evacuated at room temperature, and then hydrogen of 99.9% purity was introduced into the furnace for hydrogen decrepitation to maintain the hydrogen pressure at 0.15 Mpa; after full hydrogen absorption, vacuuming was conducted while heating up to fully dehydrogenate; then cooling was carried out and the powder after hydrogen decrepitation was taken out.

[0125] (3) Micro pulverization process: the powder after hydrogen decrepitation was pulverized by jet mill for 3 hours under a nitrogen atmosphere with an oxidizing gas content of 150 ppm or less and under a pressure of 0.38 MPa in the pulverization chamber to obtain a fine powder. The oxidizing gas referred to oxygen or moisture.

[0126] (4) Zinc stearate was added to the powder from jet mill pulverization, and the addition amount of zinc stearate was 0.12% of the weight of the mixed powder, and then mixed thoroughly with a V-mixer.

[0127] (5) Magnetic field forming process: the above-mentioned zinc stearate added powder was formed into a first cube with a side length of 25 mm by using a right-angle oriented magnetic field forming machine at an oriented magnetic field of 1.6 T and a forming pressure of 0.35 ton/cm.sup.2; and it was demagnetised in a magnetic field of 0.2 T after the first forming. In order to prevent the formed body obtained after the first forming from being exposed to air, it was sealed, and then a secondary forming machine (isostatic forming machine) was used to perform secondary forming at a pressure of 1.3 ton/cm.sup.2.

[0128] (6) Sintering process: each formed body was moved to the sintering furnace for sintering, which was held in vacuum of 5×10.sup.−3 Pa at 300° C. and 600° C. for 1 hour respectively; then, sintered at 1040° C. for 2 hours; then cooled to room temperature after the pressure reached 0.1 Mpa by introducing Ar gas.

[0129] (7) Ageing treatment process: the sintered body was heat treated in high purity Ar gas at 550° C. for 3 hours and then it was cooled to room temperature before being taken out.

[0130] The preparation process of Example 2-42 and Comparative Examples 45-48 was the same as that of Example 1.

[0131] Example 43 and 44 employed Tb grain boundary diffusion method in the preparation process.

[0132] The raw material compositions of No. 12 and 16 in Table 1 were first prepared according to the preparation of the sintered body of Example 1 to obtain a sintered body, followed by grain boundary diffusion, and then ageing treatment was carried out. The ageing treatment process was the same as in Example 1, and the process of grain boundary diffusion was as follows.

[0133] The sintered body was processed into a magnet with a diameter of 20 mm and a sheet thickness of less than 7 mm in the direction of the magnetic field orientation, and after surface cleaning, the magnet was coated with a full spray using a raw material prepared with Tb fluoride, respectively, and the coated magnet was dried and the metal with Tb element attached was sputtered on the magnet surface in a high purity Ar atmosphere at the temperature of 850° C. diffusion heat treatment for 24 hours. Cool to room temperature.

Examples of Effect Implementation

[0134] The magnetic properties and compositions of the neodymium-iron-boron magnet materials produced in each example and comparative example were measured and the crystalline phase structure of the magnets is observed by FE-EPMA.

[0135] (1) Magnetic properties evaluation: The magnet materials were tested for magnetic properties by using the NIM-10000H BH bulk rare earth permanent magnet non-destructive measurement system from the China Metrology Institute. The results of the magnetic properties testing were shown in Table 2 below.

TABLE-US-00002 TABLE 2 80° C. Hcj 150° C. Hcj 180° C. Hcj Absolute Absolute Absolute value of value of value of temperature temperature temperature No. Br(kGs) Hcj(kOe) coefficient coefficient coefficient 1 14.35 17.01 0.689 / / 2 14.16 17.62 0.684 / / 3 13.98 18.03 0.679 / / 4 14.01 18.21 0.674 / / 5 13.84 18.56 0.672 / / 6 13.65 18.88 0.668 / / 7 13.7 19.15 0.663 / / 8 13.62 19.39 0.663 / / 9 13.5 20.11 0.652 / / 10 13.49 20.64 0.648 / / 11 13.7 22 0.621 / / 12 13.30 23.6 0.601 / / 13 13.19 25.24 / 0.515 / 14 13.06 28.02 / 0.485 / 15 13.00 28.98 / 0.479 / 16 13.59 24.48 / 0.523 / 17 13.25 24.68 / 0.520 / 18 13.29 22.73 0.619 / / 19 13.15 24.03 / 0.520 / 20 13.02 25.23 0.515 21 13.27 26.81 / 0.512 / 22 13.07 28.71 / 0.491 / 23 13.34 25.66 / 0.519 / 24 13.29 25.08 / 0.522 / 25 13.39 27.24 0.493 / 26 12.91 27.09 0.503 27 13.29 24.69 / 0.531 / 28 13.01 26.97 / 0.508 / 29 12.66 26.84 0.511 30 13.15 26.87 / 0.504 / 31 13.14 26.05 / 0.510 / 32 13.10 26.68 / 0.509 / 33 13.59 23.93 0.591 / / 34 13.42 24.47 / 0.524 / 35 13.18 23.73 0.593 / / 36 14.33 18.76 0.675 / / 37 13.74 23.39 0.599 / / 38 13.19 26.04 / 0.510 / 39 12.95 27.52 / 0.488 / 40 12.75 24.19 / 0.521 / 41 12.79 24.23 / 0.519 / 42 12.63 23.72 0.594 / / 43 13.02 33.2 / / 0.428 44 13.37 34.8 / / 0 45 13.27 21.75 0.629 / / 46 13.30 21.53 0.632 / / 47 13.8 16.8 0.742 / / 48 14.0 14.9 0.782 / /

[0136] (2) Component determination: each component was determined by using a high frequency inductively coupled plasma emission spectrometer (ICN-OES). The component determination results were shown in Table 3 below.

TABLE-US-00003 TABLE 3 No. Nd Pr Dy Tb Ho Cu Al Ga Zr Co Zn Mo B Fe 1 12.341 17.154 / / / 0.341 / / / / / / 0.983 69.181 2 12.849 17.154 / / / 0.452 / / / / / / 0.989 68.556 3 12.364 18.154 / / / 0.502 / / / / / / 0.984 67.996 4 12.802 18.155 / / / 0.598 / / / / / / 0.988 67.457 5 12.348 19.15 / / / 0.649 / / / / / / 0.983 66.87 6 12.791 19.155 / / / 0.701 / / / / / / 0.989 66.364 7 11.384 20.155 / / / 0.806 / / / / / / 0.984 66.671 8 11.349 20.155 / / / 0.903 / / / / / / 0.988 66.605 9 10.844 21.157 / / / 1.021 / / / / / / 0.983 65.995 10 4.02 26.01 / / / 1.103 / / 0.1 0.2 / / 0.989 67.578 11 8.851 22.1555 / / / 1.202 / / / / / / 0.984 66.8075 12 5.854 25.156  0.31 0.72 / 0.52 0.02 / / / / / 0.983 66.437 13 5.848 25.156 / 1.02 / 0.71 0.12 / / / / / 0.989 66.157 14 5.849 24.158  0.21 1.81 / 0.91 0.21 / / / / / 0.984 65.869 15 5.847 24.155 / 2.02 / 1.12 0.24 / / / / / 0.988 65.63 16 8.846 22.155 0.2 0.82 / 1.19 / 0.12 / / / / 0.983 65.686 17 8.85 22.15 0   1 / 0.852 / 0.2 / / / / 0.985 65.963 18 7.85 23.15 0.1 0.9 / 0.648 / / 0.1 / / / 0.985 66.267 19 7.85 23.15 0.1 0.9 / 0.948 / / 0.25 / / / 0.985 65.817 20 12.35 18.15 / 1.5 / 1.05 / / / 1   0.985 64.965 21 10.849 19.154 0.1 1.91 / 0.81 0.1  0.1 / / / / 0.983 65.994 22 10.846 19.159 0.1 1.89 / 0.89 0.3  0.2 / / / / 0.989 65.626 23 12.345 18.152 / 1.48 / 0.47 / 0.25 0.22 / / / 0.984 66.099 24 12.35 18.152 / 1.47 / 0.62 / 0.1 0.28 / / / 0.988 66.04 25 9.85 19.15 0.1 1.88 / 1.21 0.2  / 0.25 / / / 0.983 66.377 26 9.85 19.15 0.1 1.9 / 0.795 0.4  / 0.3 / / / 0.985 66.52 27 8.853 22.152 0.1 0.91 / 0.91 0.3  / 0.261 / / / 0.989 65.525 28 5.851 25.153 0.2 0.82 / 1.21 0.46 / 0.291 / / / 0.984 65.031 29 5.85 25.15 0.3 0.7 / 1.08 0.48 / 0.3 / / / 0.985 65.155 30 9.851 19.152 0.1 1.91 / 0.62 0.21 0.152 0.21 / / / 0.985 66.81 31 8.853 22.152 0.3 0.72 / 0.81 0.29 0.18 0.252 / / / 0.985 65.458 32 6.851 24.155 / / / 0.78 0.42 0.202 0.272 / / / 1.102 66.218 33 6.852 24.157 / / / 0.92 0.45 0.24 0.282 / / / 1.19 65.909 34 9.851 19.15 / 2.01 / 0.41  0.102 0.101 0.251 / / / 0.988 67.137 35 6.852 24.151 / 1.02 / 0.502  0.250 0.102 0.301 / / / 0.983 65.839 36 12.351 17.150 / / / 0.702 0.01 0.251 0.251 / / / 0.983 68.302 37 12.348 17.149 / 1.02 / 0.79 0.03 0.302 0.252 / / / 0.989 67.12 38 8.848 22.151 0.3 0.7 / 0.901 0.03 0.401 0.281 / / / 0.988 65.4 39 8.847 22.152 0.3 0.7 / 1.101 0.02 0.501 0.301 / / / 0.983 65.095 40 8.851 20.13 0.3 0.17 0.99 0.81 0.31 0 0.251 / 0.04 0.07 0.983 67.095 41 8.852 20.16 0.3 0.72 0.98 0.91 0.31 0 0.252 / 0.07 0.03 0.989 66.427 42 6.853 24.152 / / 1.02 0.91 0.38 0 0.251 / 0.03 0.06 0.984 65.36 43 5.853 25.152  0.312 1.12 / 0.51 0.03 / / / / / 0.984 66.039 44 8.846 22.155 0.2 1.32 / 1.18 / 0.11 / / / / 0.985 65.204 45 5.853 25.153 / 1.02 / 0.19 0.07 / / / / / 0.988 66.726 46 5.852 25.151 / 1.04 / 0.09 0.09 / / / / / 0.983 66.794 47 14.851 15.153 / / / 0.91 0.22 / / / / / 0.983 67.883 48 21.152 8.852 / / / 0.93 0.21 / / / / / 0.989 67.867

[0137] (3) FE-EPMA inspection: the magnet material of Example 10 was taken to be polished on the vertically oriented surface, and inspected by using the Field Emission Electron Probe Microanalyser (FE-EPMA) (Japan Electronics Company (JEOL), 8530F). The distribution of elements such as Pr, Cu, B, Fe, Co and O in the magnet was first determined by FE-EPMA surface scanning, and then the content of Pr. Cu, O and other elements in the key phase was determined by FE-EPMA single point quantitative analysis, the test conditions were accelerating voltage of 15 kv and probe beam current of 50 nA.

[0138] The magnetic steel prepared by the formulation of the present invention was analyzed by means of the Field Emission Electron Probe Microanalyser (FE-EPMA), mainly for the elements Pr, Nd, Cu, Ti, Co and O, as shown in FIG. 1, and quantitative analysis was carried out for the elements at grain boundaries and in the intergranular triangle. Wherein: the grain boundary referred to the boundary between two grains, and the intergranular triangle referred to the gap formed by three and more grains.

[0139] FIG. 2 shows the distribution of elements at the grain boundaries of the neodymium-iron-boron magnet material in Example 10, Pr, Nd elements were mainly distributed in the main phase, part of the rare earth was also present at the grain boundary, element Cu and element Zr were distributed at the grain boundaries, and the point marked 1 in FIG. 2 was taken for quantitative analysis of the elements at the grain boundaries, the results were shown in Table 4 below.

TABLE-US-00004 TABLE 4 Pr Nd Cu Zr O Fe (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) 65.2 12.5 28.6 0.05 0.79 Residual

[0140] From the above data, it can been seen that Pr and Nd were present at the grain boundary in the form of rare earth rich phases and oxides, which were respectively a-Pr and a-Nd, Pr.sub.2O. Nd.sub.2O.sub.3 and NdO, and Cu occupied a certain content of about 28 wt. % at the grain boundary in addition to the main phase, for example 28.6 wt. % in this embodiment. Zr as a high melting point element was diffusely distributed throughout the region, with the effective distribution of Cu, combined with the combined effect of Pr, improved the wettability of the grain boundary, repaired crystal defects and improved the performance of the magnet.

[0141] FIG. 3 shows the distribution of elements in the intergranular triangle of the neodymium-iron-boron magnet material in Example 10, the point marked 1 in FIG. 3 was taken for quantitative analysis of the elements in the intergranular triangle, the results were shown in Table 5 below.

TABLE-US-00005 TABLE 5 Pr Nd Cu Zr O Fe (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) 42.2 23 31 0.02 1.3 Residual

[0142] In the intergranular triangle, Pr and Nd elements were distributed therein. In the high-Pr formulation, it is clear that Pr and Nd will be also enriched in the intergranular triangle, where the oxygen content was slightly higher than the grain boundary and the oxides formed increased, and the rare earth oxides were also distributed at the grain boundary after the ageing treatment, which was beneficial to isolate the exchange coupling among the main phases, and the magnetic properties of the magnets were ultimately improved.