A diffusion source, a method for manufacturing a diffusion source, and a method for improving coercivity of a magnet

Abstract

The application belongs to the technical field of rare earth permanent magnet materials, and particularly relates to a diffusion source, a preparation method of the diffusion source and a method for improving coercivity of a magnet. The diffusion source comprises lanthanum elements, heavy rare earth elements and non-rare earth elements; wherein the heavy rare earth elements are one or a combination of two or more of dysprosium elements, holmium elements, terbium elements and gadolinium elements; and the non-rare earth elements are one or a combination of two or more of aluminum elements, copper elements, cobalt elements and gallium elements. The diffusion source introduces La elements with stronger oxidizability, can promote Ce elements to enter a main phase, and reduce the influence of CeFe2 phase on diffusion of the heavy rare earth elements; meanwhile, due to the stronger oxidizability of the La elements than the heavy rare earth elements, the heavy rare earth oxides gathered in a grain boundary phase are reduced, the utilization rate of the heavy rare earth elements in the diffusion process is improved, the diffusion of the magnet is more uniform, the coercivity of the magnet is significantly improved, and the temperature coefficient of the magnet is improved.

Description

Technical Field

[0001] This invention belongs to the field of rare earth permanent magnet materials technology, specifically relating to a diffusion source, a method for preparing the diffusion source, and a method for improving the coercivity of a magnet. Background Technology

[0002] Sintered NdFeB magnets are widely used in many fields such as electronics, automobiles, computers, and medical devices due to their excellent remanence, energy product, and cost-effectiveness. With the gradual promotion of their application, the consumption of praseodymium and neodymium, the main raw materials in sintered NdFeB magnets, is increasing, while lanthanum and cerium, which are byproducts, are being accumulated in large quantities.

[0003] Although cerium-containing magnets have been produced in recent years, they still suffer from low coercivity. On the other hand, as the cerium content in the magnet increases, the CeFe2 phase content inside the magnet also increases accordingly. Simultaneously, due to the high reactivity of cerium, there is a higher concentration of rare earth oxides in the grain boundary phase. During grain boundary diffusion, the introduction of heavy rare earth elements Dy, Tb, and Ho reacts with the CeFe2 phase in the grain boundary phase to form the (HRE,Ce)Fe2 phase. Furthermore, oxygen in the grain boundary phase also consumes some of the heavy rare earth elements, leading to a sharp decrease in the utilization rate of these elements.

[0004] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention provides a diffusion source comprising lanthanum, heavy rare earth elements, and non-rare earth elements; wherein:

[0006] The heavy rare earth elements are one or more of dysprosium (Dy), holmium (Ho), terbium (Tb), and gadolinium (Gd);

[0007] The non-rare earth elements are one or more of aluminum (Al), copper (Cu), cobalt (Co), and gallium (Ga).

[0008] Preferably, by weight percentage: 0.2% ≤ lanthanum ≤ 20%, 60% ≤ heavy rare earth elements ≤ 90%, and 0.1% ≤ non-rare earth elements ≤ 20%.

[0009] Based on the same technical concept, the present invention provides a method for preparing a diffusion source, which involves melting and mixing lanthanum, heavy rare earth elements and non-rare earth elements to form an alloy.

[0010] Based on the same technical concept, the present invention further provides a method for improving the coercivity of a magnet, the method comprising the following steps:

[0011] (I) Preparation and pretreatment of cerium-containing substrates:

[0012] (I-1) Cerium-containing neodymium iron boron rapid solidification thin sheets were prepared by rapid solidification process;

[0013] (I-2) The cerium-containing NdFeB rapid solidification sheet is sequentially subjected to hydrogen crushing and air jet milling to obtain cerium-containing NdFeB powder;

[0014] (I-3) The cerium-containing NdFeB powder is first oriented and pressed by a magnetic field, and then sintered and heat-treated under vacuum to obtain a cerium-containing NdFeB blank;

[0015] (I-4) The cerium-containing NdFeB blank is cut, degreased, and pickled in sequence to obtain pretreated cerium-containing NdFeB sheets;

[0016] (II) Coating of the diffusion source:

[0017] (II-1) The diffusion source is ground into powder and then mixed with an organic solvent to obtain a diffusion agent;

[0018] (II-2) The dispersant is coated onto the surface of the pretreated cerium-containing NdFeB sheet, and then subjected to diffusion heat treatment and tempering heat treatment.

[0019] Preferably, in step (I-1), the average thickness of the cerium-containing NdFeB rapid solidification sheet is 0.25–0.45 mm;

[0020] And / or, in step (I-2), the average particle size of the cerium-containing NdFeB powder is 3.5–4.5 μm;

[0021] And / or, in step (I-3), the magnitude of the magnetic field is 1.8 to 2.5 T;

[0022] Or, in step (I-3), the sintering temperature is 1000-1090℃ and the sintering time is 0.5-9h;

[0023] And / or, in step (I-3), the heat treatment is divided into a primary heat treatment and a secondary heat treatment; the temperature of the primary heat treatment is 750-950℃ and the time is 1-5h; the temperature of the secondary heat treatment is 400-700℃ and the time is 1-5h.

[0024] And / or, in step (I-4), the solvent used for degreasing is one or a combination of two or more of anhydrous ethanol, gasoline, and acetone;

[0025] And / or, in step (I-4), the pickling is performed using a 3-5 mol / L nitric acid solution;

[0026] And / or, in step (I-4), the thickness of the pretreated cerium-containing NdFeB sheet is 0.1 to 10 mm;

[0027] And / or, in step (I-4), the composition of the pretreated cerium-neodymium-iron-boron sheet by weight percentage is: 5% ≤ cerium ≤ 20%, 10% ≤ praseodymium and neodymium ≤ 27%, 0.8% ≤ boron ≤ 1.1%, aluminum, copper, cobalt, gallium, zirconium, titanium, nickel, vanadium and chromium ≤ 5%, with the balance being iron.

[0028] Preferably, in step (II-1), the diffusion source is ground to a particle size of 1.5–8.2 μm;

[0029] And / or, in step (II-1), the organic solvent is a mixture of anhydrous ethanol and an adhesive; the mixing is carried out by stirring at 500-1000 r / min for 3-15 min;

[0030] And / or, in step (II-2), the weight gain after coating with the dispersant is 0.3% to 1%;

[0031] And / or, in step (II-2), the vacuum degree of the diffusion heat treatment is 1×10⁻⁶. -3 ~1×10 -2 Pa, the diffusion heat treatment temperature is 700~950℃, and the time is 5~40h;

[0032] And / or, in step (II-2), the tempering heat treatment is performed at a temperature of 400–650°C for a time of 1–6 hours.

[0033] The beneficial effects of this invention are:

[0034] The diffusion source described in this invention introduces the more oxidizing element La, which can promote the entry of Ce into the main phase and reduce the influence of CeFe2 on the diffusion of heavy rare earth elements. At the same time, since La has a stronger oxidizing power than heavy rare earth elements, the amount of heavy rare earth oxides agglomerated in the grain boundary phase is reduced, which can improve the utilization rate of heavy rare earth elements during the diffusion process, make the magnet diffusion more uniform, and significantly improve the coercivity of the magnet and improve the temperature coefficient of the magnet. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a scanning electron microscope backscattering image of the cross-section of the magnet after diffusion in Example 1.

[0037] Figure 2This is a scanning electron microscope backscattering image of the cross-section of the magnet after diffusion in Example 2.

[0038] Figure 3 This is a scanning electron microscope backscattering image of the cross-section of the magnet after diffusion in Example 3. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0040] Example 1

[0041] This embodiment provides a method for improving the coercivity of a magnet, the method being:

[0042] (I) Preparation and pretreatment of cerium-containing substrates:

[0043] (I-1) A cerium-containing neodymium iron boron rapidly solidified sheet with an average thickness of 0.35 mm was prepared using a rapid solidification process;

[0044] (I-2) The cerium-containing NdFeB rapid solidification flakes are sequentially subjected to hydrogen crushing and air jet milling to obtain cerium-containing NdFeB powder with an average particle size of 3.8 μm;

[0045] (I-3) The cerium-containing NdFeB powder is first oriented and pressed under a 2.0T magnetic field, and then sintered and heat-treated in a vacuum sintering furnace to obtain a cerium-containing NdFeB blank; wherein the sintering temperature is 1050℃ and the holding time is 3.5h, the first heat treatment temperature is 900℃ and the holding time is 2h, and the second heat treatment temperature is 600℃ and the holding time is 4h.

[0046] (I-4) The cerium-containing NdFeB blank is first cut, then cleaned and degreased with anhydrous ethanol, and finally acid-washed with 5 mol / L nitric acid solution to obtain a pretreated cerium-containing NdFeB sheet with an average thickness of 2.4 mm (by weight percentage, Ce 9%, Pr and Nd sum 22.5%, B 0.94%, Cu 0.02%, Al 0.03%, Co 0.5%, Zr 0.3%, the remainder being Fe);

[0047] (II) Coating of the diffusion source:

[0048] (II-1) The diffusion source La 10 Dy 85Cu5 was sequentially subjected to hydrogen crushing and air jet milling to obtain alloy powder. The alloy powder was then mixed with anhydrous ethanol and polyvinyl butyral, and stirred at 500 r / min for 15 min to obtain a dispersant.

[0049] (II-2) The dispersant is coated onto the surface of the pretreated cerium-containing NdFeB sheet and dried at 80°C for 10 minutes to obtain a sheet coated with the dispersant, with a weight gain of 0.6%.

[0050] (II-3) The thin sheet coated with the dispersant is sintered in a vacuum furnace (vacuum degree 1×10⁻⁶). -3 The heat treatment and tempering are carried out at 900℃ and 600℃ for 5 hours.

[0051] Example 2

[0052] This embodiment provides a method for improving the coercivity of a magnet, the method being:

[0053] (I) Preparation and pretreatment of cerium-containing substrates:

[0054] (I-1) A cerium-containing neodymium iron boron rapidly solidified sheet with an average thickness of 0.35 mm was prepared using a rapid solidification process;

[0055] (I-2) The cerium-containing NdFeB rapid solidification flakes are sequentially subjected to hydrogen crushing and air jet milling to obtain cerium-containing NdFeB powder with an average particle size of 3.8 μm;

[0056] (I-3) The cerium-containing NdFeB powder is first oriented and pressed under a 2.0T magnetic field, and then sintered and heat-treated in a vacuum sintering furnace to obtain a cerium-containing NdFeB blank; wherein the sintering temperature is 1040℃ and the holding time is 3.5h, the first heat treatment temperature is 900℃ and the holding time is 2h, and the second heat treatment temperature is 600℃ and the holding time is 4h.

[0057] (I-4) The cerium-containing NdFeB blank is first cut, then cleaned with gasoline to remove oil, and finally acid-washed with 5 mol / L nitric acid solution to obtain a pretreated cerium-containing NdFeB sheet with an average thickness of 2.4 mm (by weight percentage, Ce 12%, Pr and Nd sum 19.5%, B 0.94%, Cu 0.02%, Al 0.03%, Co 0.5%, Zr 0.3%, and the remainder is Fe);

[0058] (II) Coating of the diffusion source:

[0059] (II-1) The diffusion source La 10 Dy 85Cu5 was sequentially subjected to hydrogen crushing and air jet milling to obtain alloy powder. The alloy powder was then mixed with anhydrous ethanol and polyvinyl butyral, and stirred at 500 r / min for 15 min to obtain a dispersant.

[0060] (II-2) The dispersant is coated onto the surface of the pretreated cerium-containing NdFeB sheet and dried at 80°C for 10 minutes to obtain a sheet coated with the dispersant, with a weight gain of 0.6%.

[0061] (II-3) The thin sheet coated with the dispersant is sintered in a vacuum furnace (vacuum degree 1×10⁻⁶). -3 The heat treatment and tempering are carried out at 900℃ and 600℃ for 5 hours.

[0062] Example 3

[0063] This embodiment provides a method for improving the coercivity of a magnet, the method being:

[0064] (I) Preparation and pretreatment of cerium-containing substrates:

[0065] (I-1) A cerium-containing neodymium iron boron rapidly solidified sheet with an average thickness of 0.35 mm was prepared using a rapid solidification process;

[0066] (I-2) The cerium-containing NdFeB rapid solidification flakes are sequentially subjected to hydrogen crushing and air jet milling to obtain cerium-containing NdFeB powder with an average particle size of 3.8 μm;

[0067] (I-3) The cerium-containing NdFeB powder is first oriented and pressed under a 2.0T magnetic field, and then sintered and heat-treated in a vacuum sintering furnace to obtain a cerium-containing NdFeB blank; wherein the sintering temperature is 1030℃ and the holding time is 3.5h, the first heat treatment temperature is 900℃ and the holding time is 2h, and the second heat treatment temperature is 600℃ and the holding time is 4h;

[0068] (I-4) The cerium-containing NdFeB blank is first cut, then cleaned with acetone to remove oil, and finally acid-washed with 5 mol / L nitric acid solution to obtain a pretreated cerium-containing NdFeB sheet with an average thickness of 2.4 mm (by weight percentage, Ce 14%, Pr and Nd sum 17.5%, B 0.94%, Cu 0.02%, Al 0.03%, Co 0.5%, Zr 0.3%, and the remainder is Fe);

[0069] (II) Coating of the diffusion source:

[0070] (II-1) The diffusion source La 10 Dy 85Cu5 was sequentially subjected to hydrogen crushing and air jet milling to obtain alloy powder. The alloy powder was then mixed with anhydrous ethanol and polyvinyl butyral, and stirred at 500 r / min for 15 min to obtain a dispersant.

[0071] (II-2) The dispersant is coated onto the surface of the pretreated cerium-containing NdFeB sheet and dried at 80°C for 10 minutes to obtain a sheet coated with the dispersant, with a weight gain of 0.6%.

[0072] (II-3) The thin sheet coated with the dispersant is sintered in a vacuum furnace (vacuum degree 1×10⁻⁶). -3 The heat treatment and tempering are carried out at 900℃ and 600℃ for 5 hours.

[0073] Comparative Examples 1 to 6

[0074] Replace the diffusion source in Example 1 with DyH x Thus, we obtained Comparative Example 1.

[0075] Replace the diffusion source in Example 1 with Dy 95 Cu5, yielding Comparative Example 2.

[0076] Replace the diffusion source in Example 2 with DyH x Comparative Example 3 was obtained.

[0077] Replace the diffusion source in Example 2 with Dy 95 Cu5, resulting in Comparative Example 4.

[0078] Replace the diffusion source in Example 3 with DyH x Comparative Example 5 was obtained.

[0079] Replace the diffusion source in Example 3 with Dy 95 Cu5, yielding Comparative Example 6.

[0080] The performance tests of the diffusion magnets obtained in Examples 1-3 and Comparative Examples 1-6 are shown in Table 1.

[0081] Table 1

[0082] Group Remanence (kGs) Coercivity (kOe) Example 1 12.72 17.53 Comparative Example 1 12.66 17.07 Comparative Example 2 12.75 17.33 Example 2 12.35 16.64 Comparative Example 3 12.30 15.78 Comparative Example 4 12.33 16.03 Example 3 11.92 14.24 Comparative Example 5 11.93 13.85 Comparative Example 6 11.91 14.03

[0083] As can be seen from Table 1, the present invention can significantly improve the coercivity of Ce-containing neodymium iron boron magnets by introducing the easily oxidizable rare earth element La into the diffusion source to partially replace the Dy element after diffusion at the grain boundary.

[0084] Furthermore, the scanning electron microscope backscattering image of the magnet cross-section after diffusion in Example 1 is shown below. Figure 1 As shown, by Figure 1 It can be seen that after diffusion at the grain boundary, a Dy-rich shell is formed on the grain surface, which enhances the magnetocrystalline anisotropy field on the grain surface, suppresses the nucleation of antimagnetization domains on the grain surface, and improves the coercivity and thermal stability of the magnet. The introduced La element reduces the enrichment of Dy element in the grain boundary phase, and at the same time diffuses along the grain boundary into the interior of the magnet.

[0085] Example 2: Scanning electron microscopy backscattering image of the magnet cross-section after diffusion (see figure). Figure 2 As shown, by Figure 2 It can be seen that after diffusion at grain boundaries, a Dy-rich shell forms on the grain surface, enhancing the magnetocrystalline anisotropy field on the grain surface, suppressing the nucleation of antimagnetic domains on the grain surface, and improving the coercivity and thermal stability of the magnet. Due to the increased Ce content, the CeFe2 phase content increases, affecting the diffusion effect of Dy inside the magnet. La can promote the entry of Ce into the main phase, reduce the proportion of the CeFe2 phase in the grain boundary phase, and improve the utilization rate of Dy.

[0086] Example 3: Scanning electron microscopy backscattering image of the magnet cross-section after diffusion (see figure). Figure 3 As shown, by Figure 3 It can be seen that after diffusion at the grain boundaries, a Dy-rich shell is formed on the grain surface, which improves the coercivity of the magnet. With a Ce content of 14%, the CeFe2 phase content in the grain boundary phase increases, and the addition of La can significantly improve the diffusion of Dy in the Ce magnet.

[0087] Examples 4 to 6

[0088] Replace the diffusion source in Example 1 with La 10 Tb 85 Cu5, resulting in Example 4.

[0089] Replace the diffusion source in Example 2 with La 10 Tb 85 Cu5, resulting in Example 5.

[0090] Replace the diffusion source in Example 3 with La 10 Tb 85 Cu5, resulting in Example 6.

[0091] Comparative Examples 7 to 12

[0092] The diffusion source in Example 4 was replaced with TbH. x Comparative example 7 was obtained.

[0093] Replace the diffusion source in Example 4 with Tb 85 Cu5, yielding Comparative Example 8.

[0094] The diffusion source in Example 5 was replaced with TbH. xComparative Example 9 was obtained.

[0095] Replace the diffusion source in Example 5 with Tb 85 Cu5 was used to obtain Comparative Example 10.

[0096] The diffusion source in Example 6 was replaced with TbH. x Comparative Example 11 was obtained.

[0097] Replace the diffusion source in Example 6 with Tb 85 Cu5 was used to obtain Comparative Example 12.

[0098] The performance tests of the diffusion magnets obtained in Examples 4-6 and Comparative Examples 7-12 are shown in Table 2.

[0099] Table 2

[0100]

[0101]

[0102] As can be seen from Table 2, the present invention can significantly improve the coercivity of Ce-containing NdFeB magnets by introducing the easily oxidizable rare earth element La into the diffusion source to partially replace the Tb element after diffusion at the grain boundaries.

[0103] Examples 7 to 9

[0104] Replace the diffusion source in Example 1 with La 10 Dy 85 Ga5, resulting in Example 7.

[0105] Replace the diffusion source in Example 2 with La 10 Dy 85 Ga5, resulting in Example 8.

[0106] Replace the diffusion source in Example 3 with La 10 Dy 85 Ga5, resulting in Example 9.

[0107] Comparative Examples 13 to 18

[0108] Replace the diffusion source in Example 7 with Nd 10 Dy 85 Ga5 yielded Comparative Example 13.

[0109] Replace the diffusion source in Example 8 with Nd 10 Dy 85 Ga5 yields Comparative Example 14.

[0110] Replace the diffusion source in Example 9 with Nd 10 Dy85 Ga5 yields comparative example 15.

[0111] Replace the diffusion source in Example 7 with Pr 10 Dy 85 Ga5 yields Comparative Example 16.

[0112] Replace the diffusion source in Example 8 with Pr 10 Dy 85 Ga5 yielded Comparative Example 17.

[0113] Replace the diffusion source in Example 9 with Pr 10 Dy 85 Ga5 yielded a comparative example 18.

[0114] The performance tests of the diffusion magnets obtained in Examples 7-9 and Comparative Examples 13-18 are shown in Table 3.

[0115] Table 3

[0116] Group Remanence (kGs) Coercivity (kOe) Example 7 12.82 18.4 Comparative Example 13 12.72 17.57 Comparative Example 16 12.65 17.95 Example 8 12.35 17.61 Comparative Example 14 12.41 16.88 Comparative Example 17 12.31 17.29 Example 9 11.97 16.87 Comparative Example 15 11.91 15.21 Comparative Example 18 11.91 15.77

[0117] As can be seen from Table 3, by introducing the easily oxidizable rare earth element La into the diffusion source, the present invention can significantly improve the coercivity of Ce-containing neodymium iron boron magnets after diffusion at the grain boundaries, compared with Pr and Nd elements.

[0118] Examples 10 to 12

[0119] Replace the diffusion source in Example 1 with La 10 Tb 85 Ga5 alloy powder was used to obtain Example 10.

[0120] Replace the diffusion source in Example 2 with La 10 Tb 85 The Ga5 alloy powder was used to obtain Example 11.

[0121] Replace the diffusion source in Example 3 with La 10 Tb 85 The Ga5 alloy powder was used to obtain Example 12.

[0122] Comparative Examples 19 to 24

[0123] Replace the diffuser element in Example 10 with Nd 10 Tb 85 Ga5 yielded Comparative Example 19.

[0124] Replace the diffuser element in Example 11 with Nd 10 Tb 85 Ga5 yielded a comparative example of 20.

[0125] Replace the diffuser element in Example 12 with Nd 10 Tb 85 Ga5 yields Comparative Example 21.

[0126] Replace the diffuser element in Example 10 with Pr 10 Tb 85 Ga5 yields Comparative Example 22.

[0127] Replace the diffuser element in Example 11 with Pr 10 Tb 85 Ga5 yields comparative example 23.

[0128] Replace the diffuser element in Example 12 with Pr 10 Tb 85 Ga5 yields comparative example 24.

[0129] The performance tests of the diffusion magnets obtained in Examples 10-12 and Comparative Examples 19-24 are shown in Table 4.

[0130] Table 4

[0131] Group Remanence (kGs) Coercivity (kOe) Example 10 12.87 22.03 Comparative Example 19 12.82 21.14 Comparative Example 22 12.76 21.64 Example 11 12.36 19.75 Comparative Example 20 12.35 18.67 Comparative Example 23 12.25 18.99 Example 12 11.87 17.75 Comparative Example 21 11.88 16.58 Comparative Example 24 11.84 17.04

[0132] As can be seen from Table 4, by introducing the easily oxidizable rare earth element La into the diffusion source, the present invention can significantly improve the coercivity of Ce-containing neodymium iron boron magnets after diffusion at the grain boundaries, compared with Pr and Nd elements.

[0133] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for improving the coercivity of a magnet, characterized in that, The method includes the following steps: (I) Preparation and pretreatment of cerium-containing substrates: (I-1) Cerium-containing neodymium iron boron rapidly solidified flakes were prepared using a rapid solidification process; (I-2) The cerium-containing NdFeB rapid solidification sheet is sequentially subjected to hydrogen crushing and air jet milling to obtain cerium-containing NdFeB powder; (I-3) The cerium-containing NdFeB powder is first oriented and pressed by a magnetic field, and then sintered and heat-treated under vacuum to obtain a cerium-containing NdFeB blank; (I-4) The cerium-containing NdFeB blank is cut, degreased, and pickled in sequence to obtain pretreated cerium-containing NdFeB sheets; (II) Coating of the diffusion source: (II-1) The diffusion source is ground into powder and then mixed with an organic solvent to obtain a diffusion agent; (II-2) The dispersant is coated onto the surface of the pretreated cerium-containing NdFeB sheet, and then subjected to diffusion heat treatment and tempering heat treatment. The diffusion source is composed of lanthanum, heavy rare earth elements, and non-rare earth elements; wherein: The heavy rare earth elements are one or more of dysprosium, holmium, terbium, and gadolinium; The non-rare earth element is one or a combination of two or more of aluminum, copper, cobalt, and gallium. By weight percentage: 0.2% ≤ Lanthanum ≤ 20%, 60% ≤ Heavy rare earth elements ≤ 90%, 0.1% ≤ Non-rare earth elements ≤ 20%.

2. The method for improving the coercivity of a magnet according to claim 1, characterized in that, The diffusion source is prepared by melting and mixing lanthanum, heavy rare earth elements, and non-rare earth elements to form an alloy.

3. The method for improving the coercivity of a magnet according to claim 1, characterized in that, In step (I-1), the average thickness of the cerium-containing neodymium iron boron rapid solidification sheet is 0.25~0.45 mm; And / or, in step (I-2), the average particle size of the cerium-containing NdFeB powder is 3.5~4.5μm; And / or, in step (I-3), the magnitude of the magnetic field is 1.8~2.5T; Or, in step (I-3), the sintering temperature is 1000~1090℃ and the sintering time is 0.5~9h; And / or, in step (I-3), the heat treatment is divided into a primary heat treatment and a secondary heat treatment; the temperature of the primary heat treatment is 750~950℃ and the time is 1~5h; the temperature of the secondary heat treatment is 400~700℃ and the time is 1~5h. And / or, in step (I-4), the solvent used for degreasing is one or a combination of two or more of anhydrous ethanol, gasoline, and acetone; And / or, in step (I-4), the pickling is performed using a 3-5 mol / L nitric acid solution; And / or, in step (I-4), the thickness of the pretreated cerium-containing NdFeB sheet is 0.1~10 mm; And / or, in step (I-4), the composition of the pretreated cerium-neodymium-iron-boron sheet by weight percentage is: 5%≤cerium element≤20%, 10%≤praseodymium and neodymium element sum≤27%, 0.8%≤boron element≤1.1%, aluminum, copper, cobalt, gallium, zirconium, titanium, nickel, vanadium and chromium element sum≤5%, and the balance is iron.

4. The method for improving the coercivity of a magnet according to claim 1, characterized in that, In step (II-1), the diffusion source is ground to a particle size of 1.5~8.2 μm; And / or, in step (II-1), the organic solvent is a mixture of anhydrous ethanol and the adhesive; the mixing is carried out by stirring at 500-1000 r / min for 3-15 min; And / or, in step (II-2), the weight gain after coating with the dispersant is 0.3% to 1%; And / or, in step (II-2), the vacuum degree of the diffusion heat treatment is 1×10⁻⁶. -3 ~1×10 -2 Pa, the diffusion heat treatment temperature is 700~950℃, and the time is 5~40h; And / or, in step (II-2), the tempering heat treatment temperature is 400~650℃ and the time is 1~6h.

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