Neodymium-iron-boron magnet and preparation method thereof

Abstract

The invention provides a neodymium iron boron magnet and a preparation method thereof. The preparation method comprises the steps that first main phase alloy powder, second main phase alloy powder and third main phase alloy powder are mixed and then subjected to orientation forming, sintering and tempering in sequence, and the neodymium-iron-boron magnet is obtained. The magnet material with excellent magnetic performance is obtained on the premise of low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of neodymium iron boron, and in particular to a neodymium iron boron magnet and a preparation method thereof. Background Art

[0002] Nd2Fe 14 Sintered NdFeB permanent magnet material with B as the main component has high remanence, coercive force and maximum magnetic energy product, and is widely used in many high-end fields. However, due to the expensive raw material prices, cost control is the key. It is difficult to obtain magnetic materials that simultaneously take into account high remanence, coercive force and maximum magnetic energy product at a low cost in the prior art, so it is necessary to provide a new sintered NdFeB permanent magnet material. Summary of the invention

[0003] The main purpose of the present invention is to provide a NdFeB magnet and a preparation method thereof, so as to solve the problem in the prior art that it is difficult to obtain a magnetic material with high remanence, coercive force and maximum magnetic energy product at a relatively low cost.

[0004] In order to achieve the above object, according to one aspect of the present invention, a method for preparing a NdFeB magnet is provided, wherein the composition of the NdFeB magnet is as follows by weight percentage: (Re1 A1 Re2 A2 )B Q M1 m Fe 100-A1-A2-Q-m , Re1 is one or more of Pr, Nd, Dy, Tb, Ho, Gd, 9≤A1<34; Re2 is one or more of Ce, La, Y, 0<A2≤25; and 28≤A1+A2≤34; M1 is one or more of Co, Al, Cu, Ga, Nb, Zr, Ti; the preparation method comprises: mixing a first main phase alloy powder, a second main phase alloy powder and a third main phase alloy powder, and then sequentially performing orientation molding, sintering and tempering to obtain a NdFeB magnet; wherein the composition of the first main phase alloy powder is calculated by weight percentage: (PrNd) a B b M c Fe 100-a-b-c , 10≤a≤80, 0<b≤5, 0<c≤5; the composition of the second main phase alloy powder is calculated by weight percentage: Re d B e A f Fe 100-d-e-f , 28≤d≤34, 0<e≤5, 0<f≤6; the composition of the third main phase alloy powder is calculated by weight percentage: [(PrNd) a1 Q a2 ]B g D h Fe 100-a1-a2-g-h, 10≤a1+a2≤80, 0<g≤5, 0<h≤5; M, A and D are each independently one or more of Co, Al, Cu, Ga, Nb, Zr, Ti; Re is one or more of Pr, Nd, Dy, Tb, Gd, Ho; Q is one or more of Ce, La, Y.

[0005] Furthermore, the third main phase alloy powder comprises: [(PrNd) a3 Ce a4 ]B b1 D1 c1 Fe 100-a3-a4-b1-c1 and [(PrNd) a5 La a6 ]B b2 D2 c2 Fe 100-a5-a6-b2-c2 ; 10≤a3+a4≤80, 0<b1≤5, 0<c1≤5; 10≤a5+a6≤80, 0<b2≤5, 0<c2≤5; D1 and D2 are each independently one or more of Co, Cu, Ga, Zr, and Ti.

[0006] Further, according to the first main phase alloy powder (PrNd) a B b M c Fe 100-a-b-c 30~40wt%, second main phase alloy powder Re d B e A f Fe 100-d-e-f 1~10wt%, third main phase alloy powder [(PrNd) a3 Ce a4 ]B b1 D1 c1 Fe 100-a3-a4-b1-c1 45~55wt% and the third main phase alloy powder [(PrNd) a5 La a6 ]B b2 D2 c2 Fe 100-a5-a6-b2-c2 The mixture is mixed at a ratio of 5 to 15 wt%.

[0007] Furthermore, the third main phase alloy powder also includes: [(PrNd) a7 Y a8 ]B b3 D3 c3 Fe 100-a7-a8-b3-c3 ; 10≤a7+a8≤80, 0<b3≤5, 0<c3≤5; D3 is one or more of Co, Cu, Ga, Zr, and Ti.

[0008] Further, according to the first main phase alloy powder (PrNd) a B b M c Fe 100-a-b-c 25~35wt%, second main phase alloy powder Re d B e A f Fe 100-d-e-f 1-10wt% of the third main phase alloy powder [(PrNd) a3 Ce a4 ]B b1 D1 c1 Fe 100-a3-a4-b1- c1 45~55wt%, third main phase alloy powder [(PrNd) a5 La a6 ]B b2 D2 c2 Fe 100-a5-a6-b2-c2 5~15wt% and the third main phase alloy powder [(PrNd) a7 Y a8 ]B b3 D3 c3 Fe 100-a7-a8-b3-c3 The mixture is mixed at a ratio of 1 to 10 wt%.

[0009] Furthermore, the particle sizes of the first main phase alloy powder, the second main phase alloy powder and the third main phase alloy powder are independently 2 to 4 mm.

[0010] Furthermore, the magnetic field strength during the orientation molding process is ≥1.8T.

[0011] Furthermore, the sintering treatment temperature is 1050-1100° C. and the treatment time is 5-10 hours.

[0012] Furthermore, the tempering includes primary tempering and secondary tempering performed sequentially; the treatment temperature of the primary tempering is 800-940°C and the time is 6-9h; the treatment temperature of the secondary tempering is 400-600°C and the time is 4-7h.

[0013] According to another aspect of the present invention, there is provided a NdFeB magnet prepared by the above-mentioned method for preparing a NdFeB magnet.

[0014] The present invention prepares rare earth NdFeB magnets by adding low-cost rare earth Ce / La / Y, which greatly reduces costs and increases profits without reducing magnetic properties, and has better prospects for industrial application. Among them, the first main phase provides the main phase of the formula, that is, provides remanence, the second main phase provides the grain boundary phase, that is, the intrinsic coercive force, and the third main phase provides the remaining main phase. At a relatively low cost, the high-abundance rare earth Ce / La / Y with a suitable ratio can make the magnet simultaneously take into account excellent remanence, coercive force and maximum magnetic energy product. In particular, the method of preparing by mixing a plurality of different high-abundance rare earth main phases with a high remanence main phase and a high coercive force main phase can effectively reduce the cost of preparing rare earth NdFeB. Compared with the NdFeB prepared by directly adding Ce / La / Y single alloy smelting in the traditional way, the performance of this method is higher. DETAILED DESCRIPTION

[0015] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0016] As described in the background of the present application, the prior art has the problem that it is difficult to obtain magnetic materials that are excellent in remanence, coercive force and maximum magnetic energy product at a relatively low cost.

[0017] In order to solve this problem, the present application provides a method for preparing a NdFeB magnet, wherein the composition of the NdFeB magnet is as follows by weight percentage: (Re1 A1 Re2 A2 )B Q M1 m Fe 100-A1-A2-Q-m , Re1 is one or more of Pr, Nd, Dy, Tb, Ho, Gd, 9≤A1<34; Re2 is one or more of Ce, La, Y, 0<A2≤25; and 28≤A1+A2≤34; M1 is one or more of Co, Al, Cu, Ga, Nb, Zr, Ti; the preparation method comprises: mixing a first main phase alloy powder, a second main phase alloy powder and a third main phase alloy powder, and then sequentially performing orientation molding, sintering and tempering to obtain a NdFeB magnet; wherein the composition of the first main phase alloy powder is calculated by weight percentage: (PrNd) a B b M c Fe 100-a-b-c , 10≤a≤80, 0<b≤5, 0<c≤5; the composition of the second main phase alloy powder is calculated by weight percentage: Re d B e A f Fe 100-d-e-f , 28≤d≤34, 0<e≤5, 0<f≤6; the composition of the third main phase alloy powder is calculated by weight percentage: [(PrNd)a1 Q a2 ]B g D h Fe 100-a1-a2-g-h , 10≤a1+a2≤80, 0<g≤5, 0<h≤5; M, A and D are each independently one or more of Co, Al, Cu, Ga, Nb, Zr, Ti; Re is one or more of Pr, Nd, Dy, Tb, Gd, Ho; Q is one or more of Ce, La, Y.

[0018] The present invention prepares rare earth NdFeB magnets by adding low-cost rare earth Ce / La / Y, which greatly reduces costs and increases profits without reducing magnetic properties, and has better prospects for industrial application. Among them, the first main phase provides the main phase of the formula, that is, provides remanence, the second main phase provides the grain boundary phase, that is, the intrinsic coercive force, and the third main phase provides the remaining main phase. At a relatively low cost, the high-abundance rare earth Ce / La / Y with a suitable ratio can make the magnet simultaneously take into account excellent remanence, coercive force and maximum magnetic energy product. In particular, the method of preparing by mixing a plurality of different high-abundance rare earth main phases with a high remanence main phase and a high coercive force main phase can effectively reduce the cost of preparing rare earth NdFeB. Compared with the NdFeB prepared by directly adding Ce / La / Y single alloy smelting in the traditional way, the performance of this method is higher.

[0019] In a preferred embodiment, each main phase is respectively prepared by batching-smelting-quick setting to obtain a quick setting sheet, and by distributing the quick setting sheets in proportion, (Re1 A1 Re2 A2 )B Q M1 m Fe 100-A1-A2-Q-m , Re1 is one or more of Pr, Nd, Dy, Tb, Ho, Gd, 9≤A1<34; Re2 is one or more of Ce, La, Y, 0<A2≤25; and 28≤A1+A2≤34; M1 is one or more of Co, Al, Cu, Ga, Nb, Zr, Ti. Specifically, the first main phase alloy powder, the second main phase alloy powder and the third main phase alloy powder are prepared by the following steps: Step S1, respectively preparing the raw materials of the first main phase alloy, the second main phase alloy and the third main phase alloy according to the stoichiometry and preparing the first main phase alloy quick-setting sheet, the second main phase alloy quick-setting sheet and the third main phase alloy quick-setting sheet; Step S2, sequentially performing hydrogen cracking treatment and powder making treatment on the first main phase alloy quick-setting sheet, the second main phase alloy quick-setting sheet and the third main phase alloy quick-setting sheet to obtain the first main phase alloy powder, the second main phase alloy powder and the third main phase alloy powder. In a preferred embodiment, the particle sizes of the first main phase alloy powder, the second main phase alloy powder and the third main phase alloy powder are independently 2 to 4 mm.

[0020] In order to further improve the remanence, coercive force and maximum magnetic energy product of the product, in a preferred embodiment, the third main phase alloy powder comprises: [(PrNd) a3 Ce a4 ]B b1 D1 c1 Fe 100-a3-a4-b1-c1 and [(PrNd) a5 La a6 ]B b2 D2 c2 Fe 100-a5-a6-b2-c2 ; Wherein, 10≤a3+a4≤80, 0<b1≤5, 0<c1≤5; 10≤a5+a6≤80, 0<b2≤5, 0<c2≤5; D1 and D2 are each independently one or more of Co, Cu, Ga, Zr, and Ti. Further preferably, according to the first main phase alloy powder (PrNd) a B b M c Fe 100-a-b-c 30~40wt%, second main phase alloy powder Re d B e A f Fe 100-d-e-f 1~10wt%, third main phase alloy powder [(PrNd) a3 Ce a4 ]B b1 D1 c1 Fe 100-a3-a4-b1-c1 45~55wt% and the third main phase alloy powder [(PrNd) a5 La a6 ]B b2 D2 c2 Fe 100-a5-a6-b2-c2 The mixture is mixed at a ratio of 5 to 15 wt%.

[0021] In order to further improve the remanence, coercive force and maximum magnetic energy product of the product, in a preferred embodiment, the third main phase alloy powder also includes: [(PrNd) a7 Y a8 ]B b3 D3 c3 Fe 100-a7-a8-b3-c3 ; 10≤a7+a8≤80, 0<b3≤5, 0<c3≤5; D3 is one or more of Co, Cu, Ga, Zr, and Ti. Further preferably, according to the first main phase alloy powder (PrNd) a B b M c Fe 100-a-b-c 25~35wt%, second main phase alloy powder Re d B e Af Fe 100-d-e-f 1-10wt% of the third main phase alloy powder [(PrNd) a3 Ce a4 ]B b1 D1 c1 Fe 100-a3-a4-b1-c1 45~55wt%, third main phase alloy powder [(PrNd) a5 La a6 ]B b2 D2 c2 Fe 100-a5-a6-b2-c2 5~15wt% and the third main phase alloy powder [(PrNd) a7 Y a8 ]B b3 D3 c3 Fe 100-a7-a8-b3-c3 The mixture is mixed at a ratio of 1 to 10 wt%.

[0022] In order to further improve the performance uniformity of NdFeB magnets, in a preferred embodiment, the magnetic field intensity during the orientation molding process is ≥1.8 T. The sintering treatment temperature is 1050-1100°C and the treatment time is 5-10 hours. Tempering includes primary tempering and secondary tempering in sequence; the primary tempering treatment temperature is 800-940°C and the time is 6-9 hours; the secondary tempering treatment temperature is 400-600°C and the time is 4-7 hours.

[0023] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0024] Example 1

[0025] Making N38SH

[0026] Formula: Re 31.5%, (PrNd) 20.2%, Ce 5%, La 1%, Y 0.5%, Gd 3.8%, Dy 1%, Cu 0.29%, Ga 0.17%, B 0.96%, Co 0.48%, Ti 0.1%, Zr 0.2%, Ti 0.1%, and the rest is Fe.

[0027] The formula and proportion of each main phase are shown in Table 1 below:

[0028] Table 1

[0029] PcqI G Dy Co Cu Ga B Zr Ti Ce La Y Proportion No.-Main phase 27 4 0.5 0.15 0.1 0.98 0.08 0.1 30％ Second main phase 20 20 3 1.5 0.58 2.5 0.1 5％ The third main phase 17 4 0.5 0.15 0.1 0.98 0.08 0.1 10 50％ The fourth main phase 17 4 0.5 0.15 0.1 0.98 0.08 0.1 10 10％ The fifth main aspect 17 4 0.5 0.15 0.1 0.98 0.08 0.1 10 5％ Total formula 20.2 3.8 1 0.48 0.29 0.17 0.96 0.2 0.1 5 1 0.5 100％

[0030] The flakes of each main phase are melted separately to obtain flakes 1 to 5, and the atomic mass ratio is adjusted to the ratio of the total formula by blending. Flakes 1 to 5 are subjected to hydrogen cracking treatment and powder making treatment in sequence to obtain alloy powders 1 to 5, and the powders are mixed and then oriented, sintered and tempered in sequence to obtain NdFeB magnets.

[0031] Hydrogen decomposition: Hydrogen absorption pressure: 0.096Mpa, dehydrogenation starts after a 5-minute pressure drop of 0.02-0.04Mpa;

[0032] Powder making: No oxygen is added during the process, nitrogen protection is used, and the particle size is 2-4μm;

[0033] Molding: Orientation magnetic field ≥1.8T;

[0034] Sintering: 1080℃ for 7h;

[0035] Tempering: first treat at 900℃ for 8h, then cool to room temperature, and then treat at 460℃ for 5h.

[0036] The performance of NdFeB magnets was measured to be 12.7KGs of remanence and 22Koe of target intrinsic coercive force.

[0037] Comparative Example 1:

[0038] Directly mix Re31.5%, (PrNd)20.2%, Ce5%, La1%, Y0.5%, Gd3.8%, Dy1%, Cu0.29%, Ga0.17%, B0.96%, Co0.48%, Ti0.1%, Zr0.2%, Ti0.1%, Fe balance, and obtain the flakes through one smelting;

[0039] Hydrogen decomposition: Hydrogen absorption pressure: 0.096Mpa, dehydrogenation begins after a 5-minute pressure drop of 0.02-0.04Mpa;

[0040] Powder making: No oxygen is added during the process, nitrogen protection is used, and the particle size is 2-4μm;

[0041] Molding: Orientation magnetic field ≥1.8T;

[0042] Sintering: 1080℃ for 7h;

[0043] Tempering: first treat at 900℃ for 8h, then cool to room temperature, and then treat at 460℃ for 5h.

[0044] The performance of NdFeB magnets was measured to be 12.3KGs in remanence and 18Koe in intrinsic coercivity.

[0045] Embodiment 2:

[0046] Production of N38M, target remanence 12.8KGs, target intrinsic coercivity 15KOe

[0047] Formula: Re31.5%, (PrNd)21.2%, Ce5%, La1%, Y0.5%, Gd3.8%, Cu0.29%, Ga0.17%, B0.96%, Co0.48%, Ti0.1%, Zr0.2%, Ti0.1%, Fe balance;

[0048] The formula and proportion of each main phase are shown in Table 2 below:

[0049] Table 2

[0050] PcqI G Dy Co Cu Ga B Zr Ti Ce La Y Proportion The first main phase 27 4 0.5 0.15 0.1 0.98 0.08 0.1 30％ Second main phase 40 3 1.5 0.58 2.5 0.1 5％ The third main phase 17 4 0.5 0.15 0.1 0.98 0.08 0.1 10 50％ The fourth main phase 17 4 0.5 0.15 0.1 0.98 008 0.1 10 10％ The fifth main aspect 17 4 0.5 0.15 0.1 0.98 0.08 0.1 10 5％ Total formula 21.2 3.8 0 0.48 0.29 0.17 0.96 0.2 0.1 5 1 0.5 100％

[0051] The flakes of each main phase are melted separately to obtain flakes 1 to 5, and the atomic mass ratio is adjusted to the ratio of the total formula by blending. Flakes 1 to 5 are subjected to hydrogen cracking treatment and powder making treatment in sequence to obtain alloy powders 1 to 5, and the powders are mixed and then oriented, sintered and tempered in sequence to obtain NdFeB magnets.

[0052] Hydrogen decomposition: Hydrogen absorption pressure: 0.096Mpa, dehydrogenation begins after a 5-minute pressure drop of 0.02-0.04Mpa;

[0053] Powder making: No oxygen is added during the process, nitrogen protection is used, and the particle size is 2 to 4 μm;

[0054] Molding: Orientation magnetic field ≥1.8T;

[0055] Sintering: 1080℃ for 7h;

[0056] Tempering: first treat at 900℃ for 8h, then cool to room temperature, and then treat at 460℃ for 5h.

[0057] The measured performance of NdFeB magnets is 12.8KGs of remanence and the target intrinsic coercive force is 15.5Koe;

[0058] Comparative Example 2:

[0059] Directly mix Re31.5%, (PrNd)21.2%, Ce5%, La1%, Y0.5%, Gd3.8%, Cu0.29%, Ga0.17%, B0.96%, Co0.48%, Ti0.1%, Zr0.2%, Ti0.1%, Fe balance, and obtain the flakes through one smelting;

[0060] Hydrogen decomposition: Hydrogen absorption pressure: 0.096Mpa, dehydrogenation begins after a 5-minute pressure drop of 0.02-0.04Mpa;

[0061] Powder making: No oxygen is added during the process, nitrogen protection is used, and the particle size is 2-4μm;

[0062] Molding: Orientation magnetic field ≥1.8T;

[0063] Sintering: 1080℃ for 7h;

[0064] Tempering: first treat at 900℃ for 8h, then cool to room temperature, and then treat at 460℃ for 5h.

[0065] The performance of NdFeB magnets was measured to be 12.4KGs in remanence and 14Koe in intrinsic coercivity.

[0066] Embodiment 3:

[0067] Production of N38M, target remanence 12.85KGs, target intrinsic coercivity 15KOe

[0068] Formula: The total formula is Re31.3%, (PrNd)21.7%, Ce5%, La1%, Gd3.6%, Cu0.29%, Ga2.8%, B0.91%, Co0.48%, Ti0.1%, Zr0.2%, Ti0.1%, Fe balance;

[0069] The formula and proportion of each main phase are shown in Table 3 below:

[0070] Table 3

[0071] PcqI G Dy Co Cu Ga B Zr Ti Ce La Y Proportion The first main phase 27 4 0.5 0.15 3 0.98 0.08 0.1 35％ Second main phase 40 3 2 0.58 2.5 0.1 5％ The third main phase 17 4 0.5 0.15 3 0.98 0.08 0.1 10 50％ The fourth main phase 17 4 0.5 0.15 3 0.98 0.08 0.1 10 10％ Total formula 21.7 3.6 0 0.45 0.29 2.8 0.91 0.2 0.1 5 1 0 100％

[0072] The flakes of each main phase are melted separately to obtain flakes 1 to 5, and the atomic mass ratio is adjusted to the ratio of the total formula by blending. Flakes 1 to 5 are subjected to hydrogen cracking treatment and powder making treatment in sequence to obtain alloy powders 1 to 5, and the powders are mixed and then oriented, sintered and tempered in sequence to obtain NdFeB magnets.

[0073] Hydrogen decomposition: Hydrogen absorption pressure: 0.096Mpa, dehydrogenation starts after a 5-minute pressure drop of 0.02-0.04Mpa;

[0074] Powder making: No oxygen is added during the process, nitrogen protection is used, and the particle size is 2-4μm;

[0075] Molding: Orientation magnetic field ≥1.8T;

[0076] Sintering: 1080℃ for 7h;

[0077] Tempering: first treat at 900℃ for 8h, then cool to room temperature, and then treat at 460℃ for 5h.

[0078] The performance of NdFeB magnets was measured to be 12.85KGs in remanence and 15Koe in intrinsic coercivity.

[0079] Comparative Example 3:

[0080] Directly mix Re31.3%, (PrNd)21.7%, Ce5%, La1%, Gd3.6%, Cu0.29%, Ga2.8%, B0.91%, Co0.48%, Ti0.1%, Zr0.2%, Ti0.1%, Fe balance, and obtain the flakes through one smelting;

[0081] Hydrogen decomposition: Hydrogen absorption pressure: 0.096Mpa, dehydrogenation starts after a 5-minute pressure drop of 0.02-0.04Mpa;

[0082] Powder making: No oxygen is added during the process, nitrogen protection is used, and the particle size is 2-4μm;

[0083] Molding: Orientation magnetic field ≥1.8T;

[0084] Sintering: 1080℃ for 7h;

[0085] Tempering: first treat at 900℃ for 8h, then cool to room temperature, and then treat at 460℃ for 5h.

[0086] The performance of NdFeB magnets was measured to be 12.45KGs in remanence and 14.5Koe in intrinsic coercivity.

[0087] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a neodymium iron boron magnet, wherein the components of the neodymium iron boron magnet are as follows by weight percentage: (Re1 A1 Re2 A2 )B Q M1 m Fe 100-A1-A2-Q-m , Re1 is one or more of Pr, Nd, Dy, Tb, Ho, Gd, 9≤A1<34; Re2 is one or more of Ce, La, Y, 0<A2≤25; and 28≤A1+A2≤34; M1 is one or more of Co, Al, Cu, Ga, Nb, Zr, and Ti; characterized in that, The preparation method comprises: mixing the first main phase alloy powder, the second main phase alloy powder and the third main phase alloy powder, and then sequentially performing orientation molding, sintering and tempering to obtain the NdFeB magnet; Wherein, the composition of the first main phase alloy powder is calculated by weight percentage: (PrNd) a B b M c Fe 100-a-b-c , 10≤a≤80, 0<b≤5, 0<c≤5; The composition of the second main phase alloy powder is as follows by weight percentage: Re d B e A f Fe 100-d-e-f , 28≤d≤34, 0<e≤5, 0<f≤6; The composition of the third main phase alloy powder is calculated by weight percentage: [(PrNd) a1 Q a2 ]B g D h Fe 100-a1-a2-g-h ,10≤a1+a2≤80,0<g≤5,0<h≤5; M, A and D are each independently one or more of Co, Al, Cu, Ga, Nb, Zr and Ti; Re is one or more of Pr, Nd, Dy, Tb, Gd and Ho; Q is one or more of Ce, La, and Y.

2. The method for preparing a NdFeB magnet according to claim 1, wherein: The third main phase alloy powder comprises: [(PrNd) a3 Ce a4 ]B b1 D1 c1 Fe 100-a3-a4-b1-c1 and [(PrNd) a5 La a6 ]B b2 D2 c2 Fe 100-a5-a6-b2-c2 ; 10≤a3+a4≤80, 0<b1≤5, 0<c1≤5; 10≤a5+a6≤80,0<b2≤5,0<c2≤5; D1 and D2 are each independently one or more of Co, Cu, Ga, Zr, and Ti.

3. The method for preparing a NdFeB magnet according to claim 2, characterized in that: According to the first main phase alloy powder (PrNd) a B b M c Fe 100-a-b-c 30~40wt%, second main phase alloy powder Re d B e A f Fe 100-d-e-f 1~10wt%, third main phase alloy powder [(PrNd) a3 Ce a4 ]B b1 D1 c1 Fe 100-a3-a4-b1-c1 45~55wt% and the third main phase alloy powder [(PrNd) a5 La a6 ]B b2 D2 c2 Fe 100-a5-a6-b2-c2 The mixture is mixed at a ratio of 5 to 15 wt%.

4. The method for preparing a NdFeB magnet according to claim 2, characterized in that: The third main phase alloy powder also includes: [(PrNd) a7 Y a8 ]B b3 D3 c3 Fe 100-a7-a8-b3-c3 ; 10≤a7+a8≤80,0<b3≤5,0<c3≤5; D3 is one or more of Co, Cu, Ga, Zr, and Ti.

5. The method for preparing a NdFeB magnet according to claim 4, characterized in that: According to the first main phase alloy powder (PrNd) a B b M c Fe 100-a-b-c 25~35wt%, second main phase alloy powder Re d B e A f Fe 100-d-e-f 1-10wt% of the third main phase alloy powder [(PrNd) a3 Ce a4 ]B b1 D1 c1 Fe 100-a3-a4-b1-c1 45~55wt%, third main phase alloy powder [(PrNd) a5 La a6 ]B b2 D2 c2 Fe 100-a5-a6-b2-c2 5~15wt% and the third main phase alloy powder [(PrNd) a7 Y a8 ]B b3 D3 c3 Fe 100-a7-a8-b3-c3 The mixture is mixed at a ratio of 1 to 10 wt%.

6. The method for preparing a NdFeB magnet according to claim 1, characterized in that: The particle sizes of the first main phase alloy powder, the second main phase alloy powder and the third main phase alloy powder are independently 2 to 4 mm.

7. The method for preparing a NdFeB magnet according to claim 1, characterized in that: The magnetic field intensity during the orientation molding process is ≥1.8T.

8. The method for preparing a NdFeB magnet according to claim 1, characterized in that: The sintering treatment temperature is 1050-1100° C. and the treatment time is 5-10 hours.

9. The method for preparing a NdFeB magnet according to claim 1, characterized in that: The tempering includes primary tempering and secondary tempering performed sequentially; The primary tempering treatment temperature is 800-940°C and the time is 6-9h; The treatment temperature of the secondary tempering is 400-600° C. and the time is 4-7 hours.

10. A neodymium iron boron magnet, characterized in that: The NdFeB magnet is prepared by the method for preparing the NdFeB magnet according to any one of claims 1 to 9.