Cerium magnet with grain boundary phase containing different fe content and having magnetic reinforcement effect and preparation method thereof

Abstract

The application discloses a cerium magnet with a magnetic reinforcement effect and a preparation method thereof, and belongs to the technical field of magnetic materials. The nominal composition of the cerium magnet is (CexRE1-x)aFebalBbMc, wherein 0 < x ≤ 0.2 or 0.5 ≤ x ≤ 0.8 according to mass percentage. The cerium magnet is composed of a main phase and a grain boundary phase. The grain boundary phase comprises a Fe-poor phase and a Fe-rich phase. The composition of the Fe-poor phase is (CeyRE1-y)a1Fed1Mbal, the volume fraction of the Fe-poor phase in the grain boundary phase is A, the composition of the Fe-rich phase is (CezRE1-z)a2Fed2Bb2Mbal, the volume fraction of the Fe-rich phase in the grain boundary phase is B, and A and B satisfy the following condition: 30% ≤ |A-B| ≤ 90%. Compared with a traditional single alloy process, the cerium magnet prepared by the method has better comprehensive magnetic properties, higher Ce content and more stable batch production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnetic materials, in particular to a cerium magnet with a magnetic strengthening effect and a crystal boundary phase containing different Fe contents and a preparation method thereof. BACKGROUND

[0002] With the popularization of automation and artificial intelligence technology, the rapid development of new energy vehicle and wind power industry and other magnetic material application fields, the market demand for rare earth permanent magnet materials is high. Restricted by the high price of raw material metals Pr and Nd, relevant enterprises and technical personnel begin to look for alternative elements of Pr and Nd. Ce is the most abundant in rare earth elements, and the price is less than one tenth of Pr and Nd, and has gradually attracted people's attention in recent years.

[0003] But with the increase of the proportion of Ce replacing Pr and Nd, the coercivity Hcj of the magnet will gradually decrease. In actual production, when the Ce in the magnet accounts for 0-20% or 50-80% of the total rare earth content, this downward trend is particularly obvious. This is mainly related to the composition of the crystal boundary phase in the cerium magnet in this composition interval and the distribution of Ce elements.

[0004] When Ce accounts for 0-20% of the total rare earth content, the crystal boundary phase is mainly composed of Fe-poor phase, and the Fe-poor phase plays a magnetic isolation role between the main phase grains, which helps to improve the coercivity Hcj of the magnet. But at this time, Ce is mainly distributed in the main phase grain to form Ce2Fe14B phase, which has low intrinsic magnetic properties and is the main factor causing the decrease of the coercivity Hcj of the magnet.

[0005] When Ce accounts for 50-80% of the total rare earth content, the crystal boundary phase is mainly composed of Fe-rich phase, and the Fe-rich phase is located at the intersection of the triangular crystal boundary, which cannot effectively play a magnetic isolation role. Ce, except for part of the distribution in the main phase grain, is mainly enriched in the crystal boundary to form a stable Fe-rich phase. At this time, the deterioration of the microstructure of the magnet is the main reason for the significant decrease in performance.

[0006] In these two composition intervals, how to ensure the introduction of Ce elements and reduce the decrease of the coercivity Hcj of the magnet is a big difficulty. SUMMARY

[0007] In view of the shortcomings of the prior art, the present application provides a cerium magnet with a magnetic strengthening effect and a crystal boundary phase containing different Fe contents and a preparation method thereof, and the comprehensive magnetic performance of the cerium magnet is better.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a cerium magnet with a magnetic strengthening effect containing grain boundary phases of different Fe contents, characterized in that: the nominal composition of the cerium magnet, by mass percentage, is (CexRE1-x)aFebalBbMc, wherein 0<x≤0.2 or 0.5≤x≤0.8, 29.5≤a≤33, 0.86≤b≤1.02, 0≤c≤5, bal is the balance, RE is one or more of Pr, Nd, Gd, Td, Dy, Ho, Y, and M is one or more of Co, Al, Cu, Ga, Nb, Ti, Zr, Mo, V, W. The cerium magnet is composed of a main phase and a grain boundary phase. The grain boundary phase includes a Fe-poor phase and a Fe-rich phase. The Fe-poor phase has the composition (CeyRE1-y)a1Fed1Mbal, 0≤y≤0.3, 70≤a1≤100, 0≤d1≤20, and the volume fraction of the Fe-poor phase in the grain boundary phase is A. The Fe-rich phase has the composition (CezRE1-z)a2Fed2Bb2Mbal, 0≤z≤0.5, 10≤a2≤60, 40≤d2≤90, 0≤b2≤10, and the volume fraction of the Fe-rich phase in the grain boundary phase is B. A and B satisfy the following condition: 30%≤|AB|≤90%.

[0009] Preferably, the chemical formula of the Fe-rich phase includes, but is not limited to, CeFe2, CeFe2B2, Ce2Fe17, (CeRE)Fe2, and (CeRE)6Fe13M1.

[0010] The present invention also provides another technical solution: a method for preparing cerium magnets containing grain boundary phases with different Fe contents that have magnetic strengthening effect.

[0011] When the nominal composition of a cerium magnet satisfies 0 < x ≤ 0.2, its preparation method is as follows:

[0012] 1) At least one Ce-free rapidly solidified sheet containing a Fe-poor grain boundary phase and at least one Ce-rich rapidly solidified sheet containing a Fe-rich grain boundary phase are prepared by rapid solidification process. Then, the Ce-free rapidly solidified sheet and the Ce-rich rapidly solidified sheet are mixed in a certain proportion according to the nominal composition of the final cerium magnet.

[0013] 2) Use hydrogen-breaking technology to break the above-mentioned mixed quick-setting tablets into hydrogen-breaking powder;

[0014] 3) Use air jet milling technology to process hydrogen-induced pulverization into fine powder with a particle size of 2-6μm;

[0015] 4) After mixing the fine powder evenly, it is oriented and pressed into shape to obtain a pressed blank;

[0016] 5) After the compact is subjected to sintering heat treatment, a cerium magnet with Fe-poor and Fe-rich phases at the grain boundary is finally obtained.

[0017] Preferably, the nominal composition of the Fe-poor grain boundary phase-free Ce-free rapid-setting sheet is REaFebalBbMc by mass percentage, and the nominal composition of the Fe-rich grain boundary phase-rich Ce-rich rapid-setting sheet is (CeuRE1-u)aFebalBbMc by mass percentage, where 0.52≤u≤0.82.

[0018] When the nominal composition of cerium magnets satisfies 0.5 ≤ x ≤ 0.8, its preparation method is as follows:

[0019] 1) At least one Ce-rich quick-solidified sheet containing a Fe-rich grain boundary phase and at least one Ce-containing alloy sheet containing a Fe-poor grain boundary phase are prepared by quick-solidification process. Then, the Ce-rich quick-solidified sheet and the Ce-containing alloy sheet are mixed in a certain proportion according to the final nominal composition of the cerium magnet.

[0020] 2) Use hydrogen-breaking technology to break the above-mentioned mixed quick-setting tablets into hydrogen-breaking powder;

[0021] 3) Use air jet milling technology to process hydrogen-induced pulverization into fine powder with a particle size of 2-6μm;

[0022] 4) After mixing the fine powder evenly, it is oriented and pressed into shape to obtain a pressed blank;

[0023] 5) After the compact is subjected to sintering heat treatment, a cerium magnet with Fe-poor and Fe-rich phases at the grain boundary is finally obtained.

[0024] Preferably, the nominal composition of the Fe-rich Ce-rich rapid solidification sheet containing the Fe-rich grain boundary phase is (CevRE1-v)aFebalBbMc, 0.45≤v≤0.75 by mass percentage, and the nominal composition of the Fe-poor Ce-containing alloy sheet containing the Fe-poor grain boundary phase is (CewRE1-w)a3Fed3Bb3Mbal, 0.1≤w≤0.8, 40≤a3≤100, 0≤d3≤60, 0≤b3≤0.96 by mass percentage.

[0025] In the two preparation methods mentioned above, the sintering heat treatment process steps are as follows: 1) Hold at 950-1100℃ for 3-8h; 2) Hold at 850-950℃ for 0-5h; 3) Hold at 600-780℃ for 0-5h; 4) Hold at 350-550℃ for 0-5h.

[0026] Compared with the prior art, the present invention has the following advantages and effects:

[0027] 1. When the Ce content (x) of the total rare earth elements satisfies 0 < x ≤ 0.2, the grain boundary phase of the magnet consists of a large amount of Fe-poor phase and a portion of Fe-rich phase. Ce is mainly distributed in the Fe-rich phase and is not enriched within the main phase grains. Simultaneously, the Fe-poor phase provides magnetic isolation between the main phase grains. Furthermore, only a small amount of Ce is needed to consume a large amount of Fe to form a stable Fe-rich phase. The excess rare earth elements then enter the Fe-poor phase, increasing the rare earth content and further enhancing the magnetic isolation between the main phase grains. Compared to traditional single-alloy processes, the cerium magnets prepared using this method exhibit superior overall magnetic properties and more stable mass production.

[0028] 2. When Ce accounts for 0.5% of the total rare earth content (x) and satisfies x ≤ 0.8, the grain boundary phase of the magnet consists of a partially Fe-depleted phase and a large amount of Fe-rich phase. The presence of the Fe-depleted phase improves the microstructure of the magnet, ensuring that the magnet's performance will not significantly deteriorate even with the presence of a large amount of Fe-rich phase. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] Example 1.

[0031] This embodiment provides a technical solution: a cerium magnet with a magnetic strengthening effect containing grain boundary phases of different Fe contents and its preparation method, as detailed below:

[0032] 1) First, design the nominal composition of the cerium magnet as follows:

[0033] (Ce0.11Pr0.09Nd0.8)29.9FebalB0.94Co0.3Al0.03Cu0.17Ga0.12Ti0.11Zr0.04) was then refined using a rapid solidification process to produce low-Ce rapid solidification flakes with a nominal composition of (Pr0.08Nd0.92)29.5FebalB0.95Co0.3Cu0.15Ga0.15Ti0.1Zr0.05 and Ce-rich rapid solidification flakes with a nominal composition of (Ce0.53Pr0.12Nd0.35)31.51FebalB0.9Co0.3Al0.15Cu0.25Ti0.15, with a blending ratio of 80:20.

[0034] 2) Use hydrogen-breaking technology to break the above-mentioned mixed quick-setting tablets into hydrogen-breaking powder;

[0035] 3) Use air jet milling technology to process hydrogen-induced pulverization into fine powder with a particle size of 3-3.2μm;

[0036] 4) After mixing the fine powder evenly, it is oriented and pressed into shape to obtain a pressed blank;

[0037] 5) After heat treatment at 1075℃ for 6.5h, 900℃ for 3h, and 480℃ for 5h, cerium magnets were obtained. The magnetic properties of the samples were tested using a permanent magnet material measuring instrument. Electron probe microanalysis was used to analyze the elemental distribution in the grain boundary phase of the magnet to measure the proportion of Fe-poor and Fe-rich phases in the grain boundaries.

[0038] Comparative Example 1.

[0039] Cerium magnets are prepared using conventional single-alloy processes, as detailed below:

[0040] The nominal composition is produced by using a rapid solidification process.

[0041] The rapidly solidified flakes of (Ce0.11Pr0.09Nd0.8)29.9FebalB0.94Co0.3Al0.03Cu0.17Ga0.12Ti0.11Zr0.04 were used. The rapidly solidified flakes were crushed into hydrogen-crushed powder using a hydrogen-crushing process. The hydrogen-crushed powder was then processed into fine powder with a particle size of 3-3.2μm using an air jet mill. The fine powder was stirred and mixed, then oriented and pressed into a compact. The compact was then heat-treated by holding at 1075℃ for 6.5h, 900℃ for 3h, and 480℃ for 5h to obtain a cerium magnet.

[0042] Table 1 lists the magnetic properties of cerium magnets and the proportions of Fe-poor and Fe-rich phases in the grain boundary phase.

[0043] Table 1. Magnetic properties of cerium magnets and the proportion of Fe-poor and Fe-rich phases in grain boundary phases.

[0044] Sample Residual Br (kGs) Coercivity Hcj (kOe) Squareness Hk / Hcj (%) Poor Fe phase in the grain boundary A (%) Rich Fe phase in the grain boundary B (%) |A-B| (%) Example 1 14.35 12.11 98.2 92 8 84 Comparative Example 1 14.21 10.56 97.0 99 1 98

[0045] As shown in Table 1, the cerium magnet prepared in Example 1 of this invention has superior overall magnetic properties compared with conventional processes.

[0046] Example 2.

[0047] In this embodiment, a cerium magnet containing grain boundary phases with different Fe contents and exhibiting magnetic strengthening effect, and its preparation method, are described in detail below:

[0048] 1) First, design the nominal composition of the cerium magnet as follows:

[0049] (Ce0.5Pr0.12Nd0.38)32.14FebalB0.9Al0.1Cu0.2Ga0.1Ti0.1Zr0.4, then a Ce-rich quick-solidification sheet with a nominal composition of (Ce0.46Pr0.13Nd0.4)31.27FebalB0.92Al0.1Cu0.15Ti0.12Zr0.3 and a Ce-containing alloy sheet with a nominal composition of (Ce0.75Pr0.06Nd0.19)40FebalB0.9Al0.5Cu0.5Ga0.5Zr1 were produced using a rapid solidification process, with a blending ratio of 90:10.

[0050] 2) Use hydrogen-breaking technology to break the above-mentioned mixed quick-setting tablets into hydrogen-breaking powder;

[0051] 3) Use air jet milling technology to process hydrogen-induced pulverization into fine powder with a particle size of 3.2-3.5μm;

[0052] 4) After mixing the fine powder evenly, it is oriented and pressed into shape to obtain a pressed blank;

[0053] 5) After heat treatment at 1035℃ for 5 hours, 680℃ for 5 hours, and 480℃ for 5 hours, cerium magnets were obtained. The magnetic properties of the samples were tested using a permanent magnet material measuring instrument. Electron probe microanalysis was used to analyze the elemental distribution in the grain boundary phase of the magnet to measure the proportion of Fe-poor and Fe-rich phases in the grain boundaries.

[0054] Comparative Example 2.

[0055] Cerium magnets are prepared using conventional single-alloy processes, as detailed below:

[0056] The nominal composition is produced by using a rapid solidification process.

[0057] (Ce0.47Pr0.13Nd0.4)32.21FebalB0.9Al0.1Cu0.2Ga0.1Ti0.1Zr0.4) rapid solidification flakes were prepared; the rapid solidification flakes were crushed into hydrogen-crushed powder using a hydrogen-crushing process; the hydrogen-crushed powder was then processed into fine powder with a particle size of 3.2-3.5μm using an air jet mill; the fine powder was stirred and mixed evenly, then oriented and pressed into a compact; the compact was then heat-treated by holding at 1035℃ for 5h, 680℃ for 5h, and 480℃ for 5h to obtain a cerium magnet.

[0058] Table 2 lists the magnetic properties of cerium magnets and the proportions of Fe-poor and Fe-rich phases in the grain boundary phase.

[0059] Table 2. Magnetic properties of cerium magnets and the proportion of Fe-poor and Fe-rich phases in grain boundary phases.

[0060] Sample Residual Br (kGs) Coercivity Hcj (kOe) Squareness Hk / Hcj (%) Poor Fe phase in the grain boundary A (%) Rich Fe phase in the grain boundary B (%) |A-B| (%) Example 2 12.11 12.53 97.7 14 86 72 Comparative Example 2 11.90 11.26 96.4 2 98 96

[0061] As shown in Table 2, compared with conventional processes, the cerium magnets prepared in Example 2 of this invention have superior overall magnetic properties and higher Ce content.

[0062] Example 3.

[0063] In this embodiment, a cerium magnet with magnetic strengthening effect and containing grain boundary phases of different Fe contents is described. The nominal composition of the cerium magnet, by mass percentage, is (CexRE1-x)aFebalBbMc, where x=0.2, a=33, b=1.02, c=5, bal is the balance, RE represents Dy, Ho, and Y, and M represents Ga, Nb, and Ti. The cerium magnet consists of a main phase and a grain boundary phase, which includes Fe-poor and Fe-rich phases. The Fe-depleted phase composition is (CeyRE1-y)a1Fed1Mbal, y=0.3, a1=75, d1=20, and the volume fraction of the Fe-depleted phase in the grain boundary phase is A. The Fe-rich phase composition is (CezRE1-z)a2Fed2Bb2Mbal, z=0.5, a2=15, d2=70, b2=10, and the volume fraction of the Fe-rich phase in the grain boundary phase is B. A and B satisfy the following condition: |AB|=90%.

[0064] The preparation method is as follows:

[0065] 1) At least one Ce-free rapidly solidified sheet containing a Fe-poor grain boundary phase and at least one Ce-rich rapidly solidified sheet containing a Fe-rich grain boundary phase are prepared by rapid solidification process. Then, the Ce-free rapidly solidified sheet and the Ce-rich rapidly solidified sheet are mixed in a certain proportion according to the nominal composition of the final cerium magnet.

[0066] 2) Use hydrogen-breaking technology to break the above-mentioned mixed quick-setting tablets into hydrogen-breaking powder;

[0067] 3) Use air jet milling technology to process hydrogen-induced pulverization into fine powder with a particle size of 2-6μm;

[0068] 4) After mixing the fine powder evenly, it is oriented and pressed into shape to obtain a pressed blank;

[0069] 5) After the compact is subjected to sintering heat treatment, a cerium magnet with Fe-poor and Fe-rich phases at the grain boundary is finally obtained.

[0070] The nominal composition of the Ce-free rapid-solidifying sheet containing Fe-poor grain boundary phases is REaFebalBbMc by mass percentage, and the nominal composition of the Ce-rich rapid-solidifying sheet containing Fe-rich grain boundary phases is (CeuRE1-u)aFebalBbMc by mass percentage, where u=0.82.

[0071] The sintering heat treatment process steps are as follows:

[0072] 1) Keep warm at 1100℃ for 5 hours;

[0073] 2) Keep warm at 950℃ for 2 hours;

[0074] 3) Keep warm at 700℃ for 1 hour;

[0075] 4) Keep warm at 450℃ for 1 hour.

[0076] Example 4.

[0077] In this embodiment, a cerium magnet with magnetic strengthening effect and containing grain boundary phases of different Fe contents is described. The nominal composition of the cerium magnet, by mass percentage, is (CexRE1-x)aFebalBbMc, where x=0.8, a=31, b=0.92, c=2, bal is the balance, RE represents Nd and Gd, and M represents Co, Al, and Zr. The cerium magnet consists of a main phase and a grain boundary phase, which includes Fe-poor and Fe-rich phases. The Fe phase composition is (CeyRE1-y)a1Fed1Mbal, y=0.25, a1=85, d1=10, and the volume fraction of the Fe-depleted phase in the grain boundary phase is A. The Fe-rich phase composition is (CezRE1-z)a2Fed2Bb2Mbal, z=0.4, a2=30, d2=60, b2=1, and the volume fraction of the Fe-rich phase in the grain boundary phase is B. A and B satisfy the following condition: |AB|=30%.

[0078] The preparation method is as follows:

[0079] 1) At least one Ce-rich quick-solidified sheet containing a Fe-rich grain boundary phase and at least one Ce-containing alloy sheet containing a Fe-poor grain boundary phase are prepared by quick-solidification process. Then, the Ce-rich quick-solidified sheet and the Ce-containing alloy sheet are mixed in a certain proportion according to the final nominal composition of the cerium magnet.

[0080] 2) Use hydrogen-breaking technology to break the above-mentioned mixed quick-setting tablets into hydrogen-breaking powder;

[0081] 3) Use air jet milling technology to process hydrogen-induced pulverization into fine powder with a particle size of 2-6μm;

[0082] 4) After mixing the fine powder evenly, it is oriented and pressed into shape to obtain a pressed blank;

[0083] 5) After the compact is subjected to sintering heat treatment, a cerium magnet with Fe-poor and Fe-rich phases at the grain boundary is finally obtained.

[0084] The nominal composition of the Ce-rich rapid solidification sheet containing Fe-rich grain boundary phase is (CevRE1-v)aFebalBbMc, v=0.75 by mass percentage, and the nominal composition of the Ce-containing alloy sheet containing Fe-poor grain boundary phase is (CewRE1-w)a3Fed3Bb3Mbal, w=0.8, a3=90, d3=5, b3=0.5 by mass percentage.

[0085] The sintering heat treatment process steps are as follows:

[0086] 1) Keep warm at 1000℃ for 7 hours;

[0087] 2) Keep warm at 920℃ for 3 hours;

[0088] 3) Keep warm at 750℃ for 5 hours;

[0089] 4) Keep warm at 530℃ for 2 hours.

[0090] Although embodiments of the invention have been shown and described, those skilled in the art will recognize that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and concept of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A cerium magnet containing grain boundary phases with different Fe contents and exhibiting magnetic strengthening effect, characterized in that: The nominal composition of the cerium magnet, by mass percentage, is (CexRE1-x)aFebalBbMc, where 0 < x ≤ 0.2 or 0.5 ≤ x ≤ 0.8, 29.5 ≤ a ≤ 33, 0.86 ≤ b ≤ 1.02, 0 ≤ c ≤ 5, bal is the balance, RE is one or more of Pr, Nd, Gd, Td, Dy, Ho, and Y, and M is one or more of Co, Al, Cu, Ga, Nb, Ti, Zr, Mo, V, and W; the cerium magnet consists of a main phase and a grain boundary phase, the grain boundary phase containing F-depleted... The Fe-rich phase consists of an e-phase and a Fe-rich phase. The Fe-poor phase has the composition (CeyRE1-y)a1Fed1Mbal, where 0≤y≤0.3, 70≤a1≤100, and 0≤d1≤20. The volume fraction of the Fe-poor phase in the grain boundary phase is A. The Fe-rich phase has the composition (CezRE1-z)a2Fed2Bb2Mbal, where 0≤z≤0.5, 10≤a2≤60, 40≤d2≤90, and 0≤b2≤10. The volume fraction of the Fe-rich phase in the grain boundary phase is B. A and B satisfy the following condition: 30%≤|AB|≤90%.

2. The cerium magnet with magnetic strengthening effect containing grain boundary phases of different Fe contents according to claim 1, characterized in that: The chemical formulas of the Fe-rich phases include CeFe2, CeFe2B2, Ce2Fe17, (CeRE)Fe2, and (CeRE)6Fe13M1.

3. A method for preparing a cerium magnet with a magnetic strengthening effect containing grain boundary phases of different Fe contents as described in claim 1 or 2, characterized in that: When x in the nominal composition of the cerium magnet satisfies 0 < x ≤ 0.2, the preparation method is as follows: 1) At least one Ce-free rapidly solidified sheet containing a Fe-poor grain boundary phase and at least one Ce-rich rapidly solidified sheet containing a Fe-rich grain boundary phase are prepared by rapid solidification process. Then, the Ce-free rapidly solidified sheet and the Ce-rich rapidly solidified sheet are mixed in a certain proportion according to the nominal composition of the final cerium magnet. 2) Use hydrogen-breaking technology to break the mixed quick-setting tablets into hydrogen-breaking powder; 3) Use air jet milling technology to process hydrogen-induced pulverization into fine powder with a particle size of 2-6μm; 4) After mixing the fine powder evenly, it is oriented and pressed into shape to obtain a pressed blank; 5) After the compact is subjected to sintering heat treatment, a cerium magnet with Fe-poor and Fe-rich phases at the grain boundary is finally obtained; When the nominal composition of the cerium magnet satisfies 0.5 ≤ x ≤ 0.8, the preparation method is as follows: 1) At least one Ce-rich quick-solidified sheet containing a Fe-rich grain boundary phase and at least one Ce-containing alloy sheet containing a Fe-poor grain boundary phase are prepared by quick-solidification process. Then, the Ce-rich quick-solidified sheet and the Ce-containing alloy sheet are mixed in a certain proportion according to the final nominal composition of the cerium magnet. 2) Use hydrogen-breaking technology to break the mixed quick-setting tablets into hydrogen-breaking powder; 3) Use air jet milling technology to process hydrogen-induced pulverization into fine powder with a particle size of 2-6μm; 4) After mixing the fine powder evenly, it is oriented and pressed into shape to obtain a pressed blank; 5) After the compact is subjected to sintering heat treatment, a cerium magnet with Fe-poor and Fe-rich phases at the grain boundary is finally obtained.

4. The method for preparing cerium magnets with magnetic strengthening effect containing grain boundary phases of different Fe contents according to claim 3, characterized in that: When x in the nominal composition of the cerium magnet satisfies 0 < x ≤ 0.2, the nominal composition of the Ce-free rapid solidification sheet containing the Fe-poor grain boundary phase is REaFebalBbMc by mass percentage.

5. The method for preparing cerium magnets with magnetic strengthening effect containing grain boundary phases of different Fe contents according to claim 3, characterized in that: When x in the nominal composition of the cerium magnet satisfies 0 < x ≤ 0.2, the nominal composition of the Ce-rich rapid solidification sheet containing Fe-rich grain boundary phase is (CeuRE1-u)aFebalBbMc, 0.52 ≤ u ≤ 0.82 by mass percentage.

6. The method for preparing cerium magnets with magnetic strengthening effect containing grain boundary phases of different Fe contents according to claim 3, characterized in that: When x in the nominal composition of the cerium magnet satisfies 0.5≤x≤0.8, the nominal composition of the Ce-rich rapid solidification sheet containing Fe-rich grain boundary phase is (CevRE1-v)aFebalBbMc, 0.45≤v≤0.75 by mass percentage.

7. The method for preparing cerium magnets with magnetic strengthening effect containing grain boundary phases of different Fe contents according to claim 3, characterized in that: When x in the nominal composition of the cerium magnet satisfies 0.5≤x≤0.8, the nominal composition of the Ce-containing alloy sheet containing the Fe-depleted grain boundary phase is (CewRE1-w)a3Fed3Bb3Mbal, 0.1≤w≤0.8, 40≤a3≤100, 0≤d3≤60, 0≤b3≤0.96 by mass percentage.

8. The method for preparing cerium magnets with magnetic strengthening effect containing grain boundary phases of different Fe contents according to claim 3, characterized in that: The sintering heat treatment process steps are as follows: 1) Hold at 950-1100℃ for 3-8 hours; 2) Hold at 850-950℃ for 0-5 hours; 3) Hold at 600-780℃ for 0-5 hours; 4) Hold at 350-550℃ for 0-5 hours.