Cerium-rich R-T-B series sintered magnet and preparation method thereof

Abstract

The invention discloses a cerium-rich R-T-B series sintered magnet and a preparation method thereof.The preparation method comprises the following steps that S1, mixed powder is prepared, the mixed powder is obtained by evenly mixing first R-T-B series alloy powder rich in cerium and poor in rare earth and second R-T-B series alloy powder poor in cerium and rich in rare earth, the sphericity degree of the first R-T-B series alloy powder is not lower than 0.75; and S2, preparing the mixed powder into the R-T-B series sintered magnet. According to the preparation method, a low-Ce-content grain shell layer is constructed in the cerium-rich R-T-B series sintered magnet, so that the intrinsic coercive force of the cerium-rich R-T-B series sintered magnet is improved. By means of the preparation method, the high-performance R-T-B series sintered magnet rich in the Ce element can be prepared, and application of Ce resources in the R-T-B series sintered magnet is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth permanent magnet materials, and specifically relates to a method for preparing a cerium-rich RTB system sintered magnet, and a high-performance cerium-rich RTB system sintered magnet prepared by the preparation method. Background Art

[0002] RTB-based sintered magnets are the highest-performing magnet materials known among permanent magnets. Among them, R represents at least one of the rare earth elements; T represents at least one of the transition metal elements; and B represents the boron element. In the so-called RTB magnets, R is mainly Nd and T is mainly Fe, which is also called NdFeB magnets. RTB-based sintered magnets have been widely used in various generators for automobiles, home appliances, etc. With the rapid development and wide application of RTB-based sintered magnets, a large amount of rare earth resources such as Nd have been consumed. Due to the low abundance and high cost of rare earth elements such as Nd, Pr, Dy, and Tb, in order to achieve comprehensive and balanced utilization of rare earth resources and high cost-effectiveness, the high-abundance and low-cost rare earth element Ce is used to partially replace other rare earth elements such as Nd, and RTB-based sintered magnets rich in Ce elements are developed to promote the application of Ce resources, which has high practical value.

[0003] At present, the methods for preparing cerium-rich RTB sintered magnets mainly include single alloy method and double / multi-alloy method. However, no matter whether it is single alloy method or double / multi-alloy method, the coercive force of the cerium-rich RTB sintered magnets prepared is not high. This is mainly due to (1) single alloy method: using a single alloy process, the Ce element is evenly distributed in the main phase grains, and the Ce content in the core and surface of each main phase grain is equivalent. The coercive force mechanism of RTB sintered magnets is a nucleation mechanism. Due to the low anisotropy field of Ce-Fe-B and the structural defects on the surface of the main phase grains, the reverse magnetization domains are easy to nucleate on the surface of the main phase grains. Therefore, the coercive force of the prepared cerium-rich RTB sintered magnets is low. (2) Dual / multiple alloy method: Using the dual / multiple alloy process (Ce-rich alloy + Ce-poor alloy), during the sintering and densification process, the sharp corners of the Ce-rich alloy powder melt, and the sharp corners of the Ce-poor powder also melt, forming a liquid with a medium Ce content, which then adheres and precipitates on the surface of the Ce-rich powder and the Ce-poor powder. Finally, a grain surface layer with a certain Ce content is formed on the surface of the Ce-rich grains and the Ce-poor grains. The coercivity of this surface layer is relatively low, resulting in a lower coercivity of the entire magnet.

[0004] In order to improve the coercivity of cerium-rich RTB sintered magnets, the grain boundary diffusion technology of heavy rare earth elements has also been applied to cerium-rich RTB sintered magnets. As mentioned above, the main phase grain surface of cerium-rich RTB sintered magnets prepared by either single alloy method or double / multi-alloy method has a high Ce content. 14 The formation energy of B is low, and heavy rare earth elements such as Dy and Tb are difficult to replace Ce2Fe 14 The Ce in B results in poor grain boundary diffusion effect of the Ce-rich RTB system sintered magnet and limited improvement in coercive force, making it difficult to obtain high-performance Ce-rich RTB system sintered magnet. Summary of the invention

[0005] In view of this, the primary purpose of the present invention is to provide a method for preparing a cerium-rich RTB system sintered magnet, which constructs a grain shell with a low Ce content inside the cerium-rich RTB system sintered magnet, thereby improving the intrinsic coercive force of the cerium-rich RTB system sintered magnet.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention first provides a method for preparing a cerium-rich RTB-based sintered magnet, comprising the following steps:

[0008] S1. preparing a mixed powder, wherein the mixed powder is obtained by uniformly mixing a first RTB alloy powder rich in cerium and poor in rare earth and a second RTB alloy powder poor in cerium and rich in rare earth, wherein the sphericity of the first RTB alloy powder is not less than 0.75;

[0009] S2. Prepare the mixed powder into RTB based sintered magnet.

[0010] In a further embodiment, the composition of the first RTB alloy powder is R x T y B z M a , wherein 29wt.%≤x≤30wt.%, 0.89wt.%≤z≤0.92wt.%, 0wt.%≤a≤0.5wt.%, y=100-xza;

[0011] R is a rare earth element and must contain Ce and La, wherein Ce accounts for more than 20% of the total mass of R and La accounts for 5% to 10% of the total mass of R; T is a transition metal element and must contain Fe, wherein Fe accounts for more than 92% of the total mass of T; B is a boron element; M is an auxiliary metal element, consisting of one or a mixture of more than two of Cu, Al, Ga, Zn, Zr, Nb, and Ti.

[0012] In a further embodiment, the rare earth element R further contains one or more of Pr, Nd, Dy, Tb, Gd, Ho, and Y, wherein Dy and / or Tb account for less than 5% of the total mass of R;

[0013] And / or, the transition metal element T further contains Co, and Co accounts for less than 8% of the total mass of T.

[0014] In a further embodiment, the composition of the second RTB alloy powder is R' b T' c B' d M' f , wherein 32wt.%≤b≤34wt.%, 0.88wt.%≤d≤0.91wt.%, 0.5wt.%≤f≤1.0wt.%, c=100-bdf;

[0015] R' is a rare earth element and must contain Nd, and Nd accounts for more than 50% of the total mass of R; T' is a transition metal element and must contain Fe, wherein Fe accounts for 92% or more of the total mass of T; B' is boron; M' is an auxiliary metal element, consisting of one or a mixture of more than two of Cu, Al, Ga, Zn, Zr, Nb, and Ti.

[0016] In a further embodiment, the rare earth element R' further contains one or more of Ce, Pr, Dy, Tb, Gd, Ho, and Y, wherein Ce accounts for less than 10% of the total mass of R', and Dy and / or Tb accounts for less than 5% of the total mass of R;

[0017] And / or, the transition metal element T' further contains Co, and Co accounts for less than 8% of the total mass of T'.

[0018] In a further embodiment, the average particle sizes of the first RTB alloy powder and the second RTB alloy powder are both 2.0-2.8 μm, and the difference in their average particle sizes is less than 0.2 μm.

[0019] In a further embodiment, the first RTB alloy powder is obtained by spheroidization, wherein the spheroidization is carried out by mechanical grinding or high-temperature melting.

[0020] In a further embodiment, the mechanical grinding method includes stirring, rolling, collision or friction to grind away the sharp edges and corners on the surface of the powder particles to achieve sphericalization of the powder.

[0021] In a further embodiment, after the mechanical grinding step, a powder screening step is also included.

[0022] In a further embodiment, the high temperature melting is to melt the sharp edges and corners on the surface of the powder by heating, thereby achieving sphericalization of the powder.

[0023] In a further embodiment, the heating temperature is 1000-1050°C.

[0024] In a further embodiment, the heating method is resistance heating, induction heating, radio frequency induction plasma heating or laser heating.

[0025] In a further embodiment, after the high-temperature melting step, a crushing and powdering step is also included.

[0026] In a further embodiment, in the mixed powder, the mass ratio of the first RTB alloy powder to the second RTB alloy powder is (5-7):(3-5).

[0027] In a further embodiment, the step S2 includes the steps of oriented pressing, sintering and heat treating the mixed powder.

[0028] In a further embodiment, the oriented pressing molding is to mold the mixed powder in an oriented magnetic field with a strength of 1.2T to 1.5T in a protective atmosphere isolated from water and oxygen;

[0029] And / or, the sintering temperature is 1030°C to 1080°C, and the sintering time is 3 to 5 hours;

[0030] And / or, the heat treatment includes primary heat treatment and secondary heat treatment, the primary heat treatment temperature is 880°C to 920°C, the heat treatment time is 2 to 5 hours, and the secondary heat treatment temperature is 480°C to 560°C, and the heat treatment time is 2 to 5 hours.

[0031] In a further embodiment, the preparation method further comprises: step S3, diffusing heavy rare earth elements into the RTB-based sintered magnet using a grain boundary diffusion technique.

[0032] In a further embodiment, the diffusion of the heavy rare earth element in step S3 comprises the following steps:

[0033] Pre-treating the RTB-based sintered magnet;

[0034] After the heavy rare earth diffusion source is attached to the surface of the pre-treated RTB system sintered magnet, a high temperature heat treatment is performed to complete the diffusion.

[0035] In a further embodiment, the heavy rare earth diffusion source is a substance containing heavy rare earth elements, and the mass proportion of the heavy rare earth elements in the heavy rare earth diffusion source is greater than 50%.

[0036] In a further embodiment, the high temperature heat treatment temperature is 800-920° C., and the heat treatment time is 5-15 hours.

[0037] The present invention further provides a cerium-rich RTB-based sintered magnet, which is prepared by the preparation method described above; in the cerium-rich RTB-based sintered magnet, the mass of Ce accounts for more than 9.2% of the mass of rare earth.

[0038] Beneficial effects of the present invention:

[0039] The present invention mixes a Ce-rich alloy powder with high sphericity and a Ce-poor rare earth-rich alloy powder. (1) Since the Ce-rich alloy powder has a high sphericity, the rotational resistance of the powder particles during the orientation molding process is reduced, and the remanence and maximum magnetic energy product of the magnet are increased. (2) The Ce-rich alloy powder with high sphericity can reduce the corner dissolution of the Ce-rich alloy powder during the high-temperature liquid phase sintering process, reduce the concentration of the Ce element in the liquid phase, and further reduce the Ce content in the surface layer of the main phase grains of the magnet after sintering, forming a "shell" with a low Ce content. This "shell" with a low Ce content can increase the intrinsic coercive force of the initial magnet. Thereby promoting the application of Ce in RTB-based sintered magnets. DETAILED DESCRIPTION

[0040] The embodiments of the present invention are described in detail below in conjunction with examples. The examples described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0042] The first aspect of the present invention provides a method for preparing a cerium-rich RTB system sintered magnet, which comprises mixing cerium-rich rare earth-poor RTB system alloy powder with high sphericity and cerium-poor rare earth-rich RTB system alloy powder to prepare an RTB system sintered magnet, and then performing heavy rare earth element diffusion treatment through grain boundary diffusion to obtain a high-performance cerium-rich RTB system sintered magnet with significantly improved coercive force.

[0043] The main steps of the method for preparing the cerium-rich RTB sintered magnet of the present invention are as follows:

[0044] S1. Prepare a mixed powder, wherein the mixed powder is obtained by uniformly mixing a first RTB alloy powder rich in cerium and poor in rare earth and a second RTB alloy powder poor in cerium and rich in rare earth, wherein the sphericity of the first RTB alloy powder is not less than 0.75.

[0045] In the present invention, the term "rich in rare earth" means that the mass of Ce accounts for more than 20% of the total mass of rare earth elements. The term "poor in cerium and rich in rare earth" means that the mass of Ce accounts for less than 10% of the total mass of rare earth elements (including no Ce).

[0046] Further, in some specific embodiments of the present invention, the composition of the first RTB alloy powder rich in cerium and poor in rare earth is R x T y B z M a , wherein 29wt.%≤x≤30wt.%, 0.89wt.%≤z≤0.92wt.%, 0wt.%≤a≤0.5wt.%, y=100-xza;

[0047] R is a rare earth element and must contain Ce and La, wherein Ce accounts for more than 20% of the total mass of R and La accounts for 5% to 10% of the total mass of R; T is a transition metal element and must contain Fe, wherein Fe accounts for more than 92% of the total mass of T; B is a boron element; M is an auxiliary metal element, consisting of one or a mixture of more than two of Cu, Al, Ga, Zn, Zr, Nb, and Ti.

[0048] In some specific embodiments of the present invention, the rare earth element R further contains one or more of Pr, Nd, Dy, Tb, Gd, Ho, and Y. Preferably, among the rare earth elements R, Ce accounts for 20% to 60% of the total mass of R, La accounts for 5% to 10% of the total mass of R, and Dy and / or Tb account for less than 5% of the total mass of R.

[0049] In some specific embodiments of the present invention, the transition metal element T further contains Co, and Co accounts for less than 8% of the total mass of T.

[0050] Preferably, among the auxiliary elements M, Zr and / or Nb and / or Ti account for R x T y B z M a Less than 0.1% of the total mass of the alloy.

[0051] In the present invention, the first RTB alloy powder is transformed into a spherical powder so that it has a high sphericity, that is, a sphericity of not less than 0.75.

[0052] The spheroidization modification described herein refers to removing the sharp edges and corners on the surface of the alloy powder in a certain way, thereby obtaining a powder with high sphericity. The specific modification method can be mechanical grinding or high-temperature melting.

[0053] In some implementation cases of the present invention, the transformation method is mechanical grinding, specifically, by using stirring, rolling, collision, friction and other methods, the sharp edges and corners on the surface of the powder particles are ground off to achieve the sphericalization of the powder. The stirring refers to a high-speed rotating metal blade, which stirs and cuts off the sharp corners on the surface of the powder (similar to a wall breaking machine), and the preferred rotation speed is above 1000 rpm; the rolling refers to placing the powder between two relatively moving and rough hard surfaces, and applying a force to bring the two surfaces closer to each other while the two surfaces move relative to each other, thereby forming a rolling of the powder particles (similar to a stone mill or mortar); the collision refers to accelerating the powder to a certain speed, and then vertically or nearly vertically hitting the fixed and hard surface of an object, using the impact force to make the sharp corners fall off; the friction also accelerates the powder, but it hits the fixed, hard and rough surface of an object at a certain angle (generally less than 45°), sweeps over the surface at a certain angle, forms friction, and grinds off the sharp edges and corners.

[0054] It should be noted that, in order to remove the ultrafine powder generated by grinding during the mechanical grinding process, the mechanical grinding step also includes a powder screening step.

[0055] In some other embodiments of the present invention, the transformation method is high-temperature melting, and the high-temperature melting is to melt the sharp edges on the surface of the powder by heating, thereby achieving sphericalization of the powder; using melting-flow-precipitation, the sharp edges on the surface of the powder are melted by heating, and flow under the action of surface tension, and re-precipitate in the depressions on the surface of the powder.

[0056] In some specific embodiments of the present invention, the heating temperature is 1000-1050° C.; the heating method can be performed in a manner known in the art, such as resistance heating, induction heating, radio frequency induction plasma heating or laser heating.

[0057] It should be noted that in order to prevent the adhesion between powder particles during the high-temperature melting and spheroidization process, a crushing and powdering step is also included after the high-temperature melting step.

[0058] Further, in some specific embodiments of the present invention, the composition of the second RTB alloy powder poor in cerium and rich in rare earth is R' b T' c B' d M' f , wherein 32wt.%≤b≤34wt.%, 0.88wt.%≤d≤0.91wt.%, 0.5wt.%≤f≤1.0wt.%, c=100-bdf;

[0059] R' is a rare earth element and must contain Nd, and Nd accounts for more than 50% of the total mass of R; T' is a transition metal element and must contain Fe, wherein Fe accounts for 92% or more of the total mass of T; B' is boron; M' is an auxiliary metal element, consisting of one or a mixture of more than two of Cu, Al, Ga, Zn, Zr, Nb, and Ti.

[0060] In some specific embodiments of the present invention, the rare earth element R' further contains one or more of Ce, Pr, Dy, Tb, Gd, Ho, and Y, wherein Ce accounts for less than 10% of the total mass of R', and Dy and / or Tb account for less than 5% of the total mass of R.

[0061] In some specific embodiments of the present invention, the transition metal element T' further contains Co, and Co accounts for less than 8% of the total mass of T'.

[0062] Preferably, among the auxiliary elements M', Zr and / or Nb and / or Ti account for R' b T' c B' d M' f Less than 0.3% of the total mass of the alloy.

[0063] In the present invention, the average particle size of the first RTB alloy powder and the second RTB alloy powder are both 2.0-2.8 μm, and preferably, in order to improve the uniformity of mixing the two alloy powders, in the present invention, the difference in their average particle sizes is less than 0.2 μm.

[0064] In the present invention, in the mixed powder, the mass ratio of the first RTB series alloy powder and the second RTB series alloy powder can be mixed according to performance requirements. Preferably, in order to ensure that the final magnet has a high Ce content to improve the utilization of Ce, while taking into account the advantage of ensuring the magnetic properties of the magnet, in some specific embodiments of the present invention, the mass ratio of the first RTB series alloy powder and the second RTB series alloy powder is (5-7): (3-5), for example, it can be any one of 7:3, 6.5:3.5, 6:4, 5.5:4.5, 5:5, etc.

[0065] It should be noted that the preparation of the first RTB series alloy powder and the second RTB series alloy powder in this article can be carried out by methods known in the art. It only requires corresponding ingredient preparation and post-processing according to the composition of the alloy powder. The specific process conditions and parameters can be adjusted and confirmed based on methods known in the art, and will not be repeated in this article.

[0066] S2. Prepare the mixed powder into RTB based sintered magnet.

[0067] The process of preparing the mixed powder into RTB sintered magnet is a well-known process in the art, and specifically includes the steps of oriented pressing, sintering and heat treating the mixed powder. The specific process conditions in each step can be based on methods known in the art.

[0068] In some specific embodiments of the present invention, the oriented pressing molding is to mold the mixed powder in an oriented magnetic field with an intensity of 1.2T to 1.5T in a protective atmosphere that is isolated from water and oxygen, wherein the protective atmosphere described in this article refers to an inert or inactive gas commonly used in the art, such as nitrogen, rare gases (helium, argon, etc.); the conditions for isolating water and oxygen are preferably that the oxygen content is less than 100ppm and the water content is less than 10ppm.

[0069] In some specific embodiments of the present invention, the sintering temperature is 1030° C. to 1080° C., and the sintering time is 3 to 5 hours.

[0070] The purpose of the heat treatment is to improve the magnetic properties of the sintered magnet through heat treatment. The heat treatment temperature, time, etc. can adopt known conditions. In some specific embodiments of the present invention, it includes primary heat treatment and secondary heat treatment. The primary heat treatment temperature is 880℃~920℃, and the heat treatment time is 2~5 hours. The secondary heat treatment temperature is 480℃~560℃, and the heat treatment time is 2~5 hours.

[0071] In the present invention, a Ce-rich alloy powder with high sphericity is mixed with a Ce-poor rare earth-rich alloy powder to form a "shell" with low Ce content in the final magnet. This "shell" with low Ce content improves the intrinsic coercivity of the final magnet.

[0072] As a further optimization of the above technical solution, the preparation method of the RTB system sintered magnet in the present invention further includes step S3, using grain boundary diffusion technology to diffuse heavy rare earth elements in the RTB system sintered magnet. On the basis of the above process, the grain boundary diffusion process is carried out. Since a "shell" with a low Ce content is formed on the surface of the main phase grains of the magnet, it can promote the diffusion of heavy rare earth elements into the surface of the main phase grains to form a "core-shell structure", enhance the grain boundary diffusion effect of heavy rare earth elements, and further significantly improve the intrinsic coercivity of the cerium-rich RTB system sintered magnet.

[0073] The diffusion of the heavy rare earth element in step S3 of the present invention can be carried out by a method known in the art, which mainly includes the following steps:

[0074] Pre-treating the RTB-based sintered magnet;

[0075] After the heavy rare earth diffusion source is attached to the surface of the pre-treated RTB system sintered magnet, a high temperature heat treatment is performed to complete the diffusion.

[0076] In the present invention, pre-treating the RTB based sintered magnet refers to performing mechanical processing and / or surface cleaning on the RTB based sintered magnet as required.

[0077] The mechanical processing described herein refers to the process of mechanically processing a large magnet into a small-sized magnet, such as by cutting, so as to facilitate grain boundary diffusion. In some specific implementation cases of the present invention, the minimum dimension of the processed small-sized magnet is less than 10 mm, preferably, the minimum dimension is less than 5 mm.

[0078] The surface cleaning mentioned herein refers to cleaning the surface of the processed magnet by methods known in the art to remove pollutants such as oil, magnetic mud, rust, etc. attached to the surface, such as degreasing, alkaline washing or acid washing.

[0079] Furthermore, a heavy rare earth diffusion source is attached to the surface of the pretreated RTB system sintered magnet, wherein the attachment method is not particularly limited, as long as it can ensure that the heavy rare earth diffusion source covers the surface of the RTB system sintered magnet. The method used can be coating (such as spraying), printing (such as silk screen printing), physical vapor deposition (such as magnetron sputtering), etc., but is not limited to these.

[0080] Further, the heavy rare earth diffusion source described herein refers to a substance rich in heavy rare earth elements, specifically, a heavy rare earth element that accounts for more than 50% of the diffusion source. The heavy rare earth element described here generally refers to Dy and / or Tb. Examples of specific heavy rare earth diffusion sources include pure metals of Dy and / or Tb, compounds of Dy and / or Tb (such as oxides, hydrides or fluorides), and binary / multinary alloys of Dy and / or Tb with other metals (such as dysprosium / terbium iron alloy, dysprosium / terbium cobalt alloy, dysprosium / terbium aluminum alloy or dysprosium / terbium copper alloy, etc.). It is understood that the "multinary" described above refers to ternary or more.

[0081] In the present invention, the amount of heavy rare earth diffusion source added can be determined according to the needs of those skilled in the art. In some specific embodiments, the heavy rare earth diffusion source covers the surface of the magnet, and the weight gain ratio of the magnet is 0.6wt% to 1wt%.

[0082] Further, the high temperature heat treatment described herein refers to heating the small-sized magnet covered with heavy rare earth diffusion sources to promote the grain boundary diffusion of the heavy rare earth diffusion sources covered on the outer surface into the interior of the magnet. The specific treatment temperature and time can be adjusted based on methods known in the art. In some specific implementation cases of the present invention, the high temperature heat treatment temperature is 800-920°C and the time is 5-15 hours.

[0083] The second aspect of the present invention provides a cerium-rich RTB sintered magnet, which is prepared by the preparation method described in the first aspect of the present invention; in the cerium-rich RTB sintered magnet, the mass of Ce accounts for more than 9.2% of the mass of rare earth, and the cerium-rich RTB sintered magnet has high performance, and the remanence, intrinsic coercivity and maximum magnetic energy product before grain boundary diffusion are improved. The coercivity increase value after grain boundary diffusion is significantly increased, and the coercivity increase is also significantly improved, indicating that the cerium-rich RTB sintered magnet prepared in the present invention can significantly improve the performance of the magnet. The optimal solution is to cooperate with the grain boundary diffusion process, which can significantly improve the grain boundary diffusion effect of heavy rare earth elements and significantly improve the magnetic properties of the cerium-rich RTB sintered magnet.

[0084] The present invention is described below by means of specific examples. It should be noted that the following specific examples are only for illustrative purposes and do not limit the scope of the present invention in any way. In addition, unless otherwise specified, methods without specific conditions or steps are conventional methods, and the reagents and materials used can be obtained from commercial channels.

[0085] Example 1

[0086] This embodiment provides a method for preparing a cerium-rich RTB-based sintered magnet, and the specific steps are as follows:

[0087] (1) Preparation of RTB alloy powder

[0088] Preparation composition is La 1.5 Ce6Pr 1.5 Nd 20 oeLh 68.66 Cu 0.15 Al 0.1 Ga 0.1 Nb 0.02 Ti 0.08 B 0.89 (wt.%), RTB alloy powder F rich in cerium and poor in rare earth with an average particle size of 2.65 μm 10 ; Preparation composition is Pr2Ho6Nd 23 oeLh 66.24 Cu 0.3 Al 0.2 Ga0.1 Nb 0.12 Ti 0.15 B 0.89 (wt.%), an RTB alloy powder P having a low cerium content and high rare earth content and an average particle size of 2.79 μm 10 .

[0089] (2) RTB alloy powder F 10 Spherization

[0090] The cerium-rich and rare earth-poor RTB alloy powder F was prepared by high-speed rolling and mixing. 10 Spherical transformation was performed to grind off the sharp edges and corners on the surface of the powder particles. The powder after rolling and stirring was sieved to remove the ultrafine powder (sharp corners ground off) produced during the rolling and stirring process, and a powder F with a sphericity of 0.76 was obtained. 11 .

[0091] (3) Powder mixing

[0092] Alloy powder F transformed into spherical shape according to the mass ratio of 7:3 11 And alloy powder P 10 Mix evenly to obtain mixed powder K1.

[0093] (4) Preparation of sintered magnets

[0094] In a nitrogen protection environment with an oxygen content of less than 100 ppm and a water content of less than 10 ppm, the mixed powder K1 was molded in a 1.3 T oriented magnetic field, and then sintered at 1040°C for 5 hours, subjected to a primary heat treatment at 890°C for 5 hours, and a secondary heat treatment at 500°C for 2 hours to produce an RTB-based sintered magnet M. 10 .

[0095] (5) Grain boundary diffusion treatment

[0096] RTB sintered magnet M 10 The magnet was processed into a small-sized magnet with a minimum dimension of 3 mm. The surface of the processed small-sized magnet was cleaned to remove the oil, magnetic mud, rust and other pollutants attached to the surface. Dysprosium hydride powder was sprayed on the magnet surface with a weight gain percentage of 0.8wt%, and then heat-treated at 800°C for 20 hours to obtain a diffuse magnet M. 11 .

[0097] Comparative Example 1

[0098] This comparative example discloses a method for preparing a cerium-rich RTB-based sintered magnet, and the specific steps are as follows:

[0099] (1) Preparation of RTB alloy powder

[0100] Preparation composition is La1.05 Ce 4.2 Pr 1.65 Ho 1.8 Nd 20.9 oeLh 67.934 Cu 0.195 Al 0.13 Ga 0.1 Nb 0.05 Ti 0.10 1B 0.89 (wt. %) (same as mixed powder K1) of single RTB based alloy powder K1'.

[0101] (2) Preparation of sintered magnets

[0102] The alloy powder K1' is made into RTB sintered magnet M in the same manner as in Example 1. 10 '.

[0103] (3) Grain boundary diffusion treatment

[0104] The same method as in Example 1 is used to sinter the RTB-based magnet M. 10 'Carry out grain boundary diffusion of heavy rare earth elements to obtain diffusion magnet M 11 '.

[0105] Comparative Example 2

[0106] This comparative example discloses a method for preparing a cerium-rich RTB-based sintered magnet, which adopts the same implementation as Example 1, except that: the cerium-rich rare earth-poor RTB-based alloy powder F is not subjected to the sintering. 10 The other steps and process conditions are the same as those in Example 1.

[0107] The preparation method of the cerium-rich RTB sintered magnet in this comparative example comprises the following specific steps:

[0108] (1) Powder mixing

[0109] The alloy powder F in Example 1 was used 10 And alloy powder P 10 , the alloy powder F was mixed in a mass ratio of 7:3 10 And alloy powder P 10 Mix evenly to obtain mixed powder K1".

[0110] (2) Preparation of sintered magnets

[0111] The mixed powder K1" is made into RTB sintered magnet M in the same manner as in Example 1. 10 ”.

[0112] (3) Grain boundary diffusion treatment

[0113] The same method as in Example 1 is used to sinter the RTB-based magnet M. 10 "Carry out grain boundary diffusion of heavy rare earth elements to obtain diffusion magnet M 11 ”.

[0114] Example 2

[0115] This embodiment provides a method for preparing a cerium-rich RTB-based sintered magnet, and the specific steps are as follows:

[0116] (1) Preparation of RTB alloy powder

[0117] Preparation composition is La2Ce 9.5 PdX 13.4 ikB 0.5 Fe 65.37 Co4Cu 0.05 Al 0.07 Ga 0.05Zn0.08Zr0.04 Nb 0.0 4B 0.9 (wt.%), RTB alloy powder F rich in cerium and poor in rare earth with an average particle size of 2.17 μm 20 ; Preparation composition is Pr1Ho4Gd1Nd 24 ikB 0.5 Fe 62.62 Co4Cu 0.2 Al 0.4 Zn 0.15 Zr 0.14 Nb 0.04 Ti 0.05 B 0.9 (wt.%), cerium-poor rare earth-rich RTB alloy powder P with an average particle size of 2.01 μm 20 .

[0118] (2) RTB alloy powder F 20 Spherization

[0119] Laser heating of cerium-rich rare earth-poor RTB alloy powder 20 The spherical transformation was carried out at a heating temperature of 1040°C to melt the sharp edges and corners on the surface of the powder particles. The powder after spherical transformation was jet milled to prevent the adhesion between the powder particles, and a powder F with a sphericity of 0.77 was obtained. 21 .

[0120] (3) Powder mixing

[0121] Alloy powder F transformed into spherical shape according to the mass ratio of 5:5 21 And alloy powder P 20Mix evenly to obtain mixed powder K2.

[0122] (4) Preparation of sintered magnets

[0123] In a nitrogen protection environment with an oxygen content of less than 100 ppm and a water content of less than 10 ppm, the mixed powder K2 was molded in a 1.5 T oriented magnetic field, and then sintered at 1050°C for 3 hours, subjected to a primary heat treatment at 880°C for 4 hours, and a secondary heat treatment at 480°C for 3 hours to produce an RTB-based sintered magnet M. 20 .

[0124] (5) Grain boundary diffusion treatment

[0125] The large magnet M 20 The magnet was processed into a small-sized magnet with a minimum dimension of 9 mm. The surface of the processed small-sized magnet was cleaned to remove the oil, magnetic mud, rust and other pollutants attached to the surface. A metal terbium coating layer was physically vapor deposited on the magnet surface with a weight gain percentage of 0.6 wt%. The magnet was then heat treated at 840 ° C for 25 hours to obtain a diffusion magnet M. 21 .

[0126] Comparative Example 3

[0127] This comparative example discloses a method for preparing a cerium-rich RTB-based sintered magnet, and the specific steps are as follows:

[0128] (1) Preparation of RTB alloy powder

[0129] Preparation composition is La1Ce 4.75 P2Hg 0.5 Nd 18.7 ikB 0.5 Fe 63.995 Co4Cu 0.125 Al 0.235 Ga 0.025 Zn 0.115 Zr 0.09 Nb 0.04 Ti 0.025 B 0.9 (wt. %) (same as mixed powder K2) of single RTB based alloy powder K2'.

[0130] (2) Preparation of sintered magnets

[0131] The alloy powder K2' is made into RTB sintered magnet M in the same manner as in Example 2. 20 '.

[0132] (3) Grain boundary diffusion treatment

[0133] The same method as in Example 2 is used to sinter the RTB-based magnet M. 20 'Carry out grain boundary diffusion of heavy rare earth elements to obtain diffusion magnet M 21 '.

[0134] Comparative Example 4

[0135] This comparative example discloses a method for preparing a cerium-rich RTB-based sintered magnet, which adopts the same implementation as Example 2, except that: the cerium-rich rare earth-poor RTB-based alloy powder F is not subjected to the sintering. 20 The other steps and process conditions are the same as those in Example 2.

[0136] The preparation method of the cerium-rich RTB sintered magnet in this comparative example comprises the following specific steps:

[0137] (1) Powder mixing

[0138] The alloy powder F in Example 2 was used 20 And alloy powder P 20 , alloy powder F was mixed in a mass ratio of 5:5 20 And alloy powder P 20 Mix evenly to obtain mixed powder K2".

[0139] (2) Preparation of sintered magnets

[0140] The mixed powder K2" is made into RTB sintered magnet M in the same manner as in Example 2. 20 ”.

[0141] (3) Grain boundary diffusion treatment

[0142] The same method as in Example 2 is used to sinter the RTB-based magnet M. 20 "Carry out grain boundary diffusion of heavy rare earth elements to obtain diffusion magnet M 21 ”.

[0143] Example 3

[0144] This embodiment provides a method for preparing a cerium-rich RTB-based sintered magnet, and the specific steps are as follows:

[0145] (1) Preparation of RTB alloy powder

[0146] Preparation composition is La 2.5 Ce 13.4 Y 1.5 Nd 10.4 ikB 0.2 Fe 67.69 Co2Cu 0.2 Ga 0.1 Zr0.04 Ti 0.06 B 0.91 (wt.%), RTB alloy powder F rich in cerium and poor in rare earth with an average particle size of 2.77 μm 30 ; Preparation composition is Pr4Gd1Y2Ce3Nd 23 oeLh 62.39 Co2Al 0.1 Ga 0.3 Zn 0.1 Zr 0.04 Ti 0.16 B 0.91 (wt.%), cerium-poor rare earth-rich RTB alloy powder P with an average particle size of 2.63 μm 30 .

[0147] (2) RTB alloy powder F 30 Spherization

[0148] Radio frequency induction plasma heating of cerium-rich rare earth-poor RTB alloy powder F 30 Spheroidization was performed, and the heating temperature was 1020℃ to melt the sharp edges on the surface of the powder particles. The powder after spheroidization was jet milled to prevent the powder particles from sticking together, and a powder F with a sphericity of 0.80 was obtained. 31 .

[0149] (3) Powder mixing

[0150] Alloy powder F transformed into spherical shape according to the mass ratio of 6:4 31 And alloy powder P 30 Mix evenly to obtain mixed powder K3.

[0151] (4) Preparation of sintered magnets

[0152] In a nitrogen protection environment with an oxygen content of less than 100 ppm and a water content of less than 10 ppm, the mixed powder K3 was molded in a 1.4 T oriented magnetic field, and then sintered at 1030°C for 4 hours, subjected to a primary heat treatment at 900°C for 3 hours, and a secondary heat treatment at 530°C for 4 hours to produce an RTB-based sintered magnet M. 30 .

[0153] (5) Grain boundary diffusion treatment

[0154] The large magnet M 30 The small-sized magnets were processed into a minimum size of 5 mm, and the surface of the processed small-sized magnets was cleaned to remove the oil, magnetic mud, rust and other pollutants attached to the surface. Dysprosium oxide powder was screen-printed on the surface of the magnets with a weight gain percentage of 1wt%, and then heat-treated at 880°C for 15 hours to obtain a diffuse magnet M. 31 .

[0155] Comparative Example 5

[0156] This comparative example discloses a method for preparing a cerium-rich RTB-based sintered magnet, and the specific steps are as follows:

[0157] (1) Preparation of RTB alloy powder

[0158] Preparation composition is La 1.5 Ce 9.24 Y 1.7 Pr 1.6 G 0.4 Nd 15.44 ikB 0.12 Fe 65.57 Co2Cu 0.12 Al 0.04 Ga 0.18 Zn 0.04 Zr 0.04 Ti 0.1 B 0.91 (wt. %) (same as mixed powder K3) of single RTB based alloy powder K3'.

[0159] (2) Preparation of sintered magnets

[0160] The alloy powder K3' is made into RTB sintered magnet M in the same manner as in Example 3. 30 '.

[0161] (3) Grain boundary diffusion treatment

[0162] The same method as in Example 3 is used to sinter the RTB-based magnet M. 30 'Carry out grain boundary diffusion of heavy rare earth elements to obtain diffusion magnet M 31 '.

[0163] Comparative Example 6

[0164] This comparative example discloses a method for preparing a cerium-rich RTB-based sintered magnet, which adopts the same implementation as Example 3, except that: the cerium-rich rare earth-poor RTB-based alloy powder F is not subjected to the sintering. 30 The other steps and process conditions are the same as those in Example 3.

[0165] The preparation method of the cerium-rich RTB sintered magnet in this comparative example comprises the following specific steps:

[0166] (1) Powder mixing

[0167] The alloy powder F in Example 3 was used 30 And alloy powder P 30, alloy powder F was mixed in a mass ratio of 6:4 30 And alloy powder P 30 Mix evenly to obtain mixed powder K3".

[0168] (2) Preparation of sintered magnets

[0169] The mixed powder K3" is made into RTB sintered magnet M in the same manner as in Example 3. 30 ”.

[0170] (3) Grain boundary diffusion treatment

[0171] The same method as in Example 3 is used to sinter the RTB-based magnet M. 30 "Carry out grain boundary diffusion of heavy rare earth elements to obtain diffusion magnet M 31 ”.

[0172] Example 4

[0173] This embodiment provides a method for preparing a cerium-rich RTB-based sintered magnet, and the specific steps are as follows:

[0174] (1) Preparation of RTB alloy powder

[0175] Preparation composition is La 2.9 Ce 17.4 G 0.8 oeLh 0.5 Fe 63.49 Co 5.5 Cu 0.15 Al 0.1 Ga 0.05 Zn 0.1 Zr 0.03 Nb 0.0 3Ti 0.03 B 0.92 (wt.%), RTB alloy powder F rich in cerium and poor in rare earth with an average particle size of 2.04 μm 40 ; Preparation composition is Pr1Ho2Gd1Y1Ce2Nd 26 Tb 0.5 Fe 59.83 Co 5.1 Cu 0.1 Zn 0.1 Ga 0.2 Zr 0.13 Nb 0.03 Ti 0.13 B 0.88 (wt.%), cerium-poor rare earth-rich RTB alloy powder P with an average particle size of 2.18 μm 40 .

[0176] (2) RTB alloy powder F 40 Spherization

[0177] The high pressure airflow collision was used to precipitate the cerium-rich rare earth-poor RTB alloy powder F 40 Spherical transformation was performed to grind off the sharp edges and corners on the surface of the powder particles. The powder after high-pressure airflow collision was screened to remove the sharp corners of the powder particles that fell off during the high-pressure airflow collision process, and a powder F with a sphericity of 0.82 was obtained. 41 .

[0178] (3) Powder mixing

[0179] Alloy powder F transformed into spherical shape according to the mass ratio of 7:3 41 And alloy powder P 40 Mix evenly to obtain mixed powder K4.

[0180] (4) Preparation of sintered magnets

[0181] In a nitrogen protection environment with an oxygen content of less than 100ppm and a water content of less than 10ppm, the mixed powder K4 was molded in a 1.2T oriented magnetic field, and then sintered at 1080℃ for 4.5 hours, subjected to a primary heat treatment at 920℃ for 2 hours, and a secondary heat treatment at 560℃ for 5 hours to produce an RTB-based sintered magnet M. 40 .

[0182] (5) Grain boundary diffusion treatment

[0183] The large magnet M 40 The small-sized magnets were processed into a minimum size of 5 mm, and the surface of the processed small-sized magnets was cleaned to remove the oil, magnetic mud, rust and other pollutants attached to the surface, and terbium hydride powder was sprayed on the surface of the magnets with a weight gain percentage of 0.8wt%, and then heat-treated at 920°C for 10 hours to obtain a diffuse magnet M. 41 .

[0184] Comparative Example 7

[0185] This comparative example discloses a method for preparing a cerium-rich RTB-based sintered magnet, and the specific steps are as follows:

[0186] (1) Preparation of RTB alloy powder

[0187] Preparation composition is La 2.03 Ce 12.78 Y 0.3 Pr 0.3 Ho 0.6 G 0.86 Nd 13.4 Tb 0.5 Fe 62.392 Co5.38 Cu 0.135 Al 0.0 7Ga 0.095 Zn 0.1 Zr 0.06 Nb 0.03 Ti 0.06 B 0.908 (wt. %) (same as mixed powder K4) of single RTB-based alloy powder K4'.

[0188] (2) Preparation of sintered magnets

[0189] The alloy powder K4' is made into RTB sintered magnet M in the same manner as in Example 4. 40 '.

[0190] (3) Grain boundary diffusion treatment

[0191] The same method as in Example 4 is used to sinter the RTB-based magnet M. 40 'Carry out grain boundary diffusion of heavy rare earth elements to obtain diffusion magnet M 41 '.

[0192] Comparative Example 8

[0193] This comparative example discloses a method for preparing a cerium-rich RTB-based sintered magnet, which adopts the same implementation as Example 4, except that: the cerium-rich rare earth-poor RTB-based alloy powder F is not subjected to the sintering. 40 The other steps and process conditions are the same as those in Example 4.

[0194] The preparation method of the cerium-rich RTB sintered magnet in this comparative example comprises the following specific steps:

[0195] (1) Powder mixing

[0196] The alloy powder F in Example 4 was used 40 And alloy powder P 40 , the alloy powder F was mixed in a mass ratio of 7:3 40 And alloy powder P 40 Mix evenly to obtain mixed powder K4".

[0197] (2) Preparation of sintered magnets

[0198] The mixed powder K4" is made into RTB sintered magnet M in the same manner as in Example 4. 40 ”.

[0199] (3) Grain boundary diffusion treatment

[0200] The same method as in Example 4 is used to sinter the RTB-based magnet M.40 "Carry out grain boundary diffusion of heavy rare earth elements to obtain diffusion magnet M 41 ”.

[0201] Performance Testing

[0202] According to the "Magnetic Test Methods for Permanent Magnet (Hard Magnetic) Materials" (GB / T 3217-2013), the main magnetic properties (remanence, intrinsic coercivity, and maximum magnetic energy product) of the cerium-rich RTB-based sintered magnets in Examples 1-4 and Comparative Examples 1-8 were tested, and the results are shown in Table 1. In order to reflect the grain boundary diffusion effect of the cerium-rich RTB-based sintered magnets, the magnetic properties of each sample before and after grain boundary diffusion were tested at the same time, and the increase in intrinsic coercivity and increase (percentage) of each sample after grain boundary diffusion were calculated.

[0203] Table 1 Magnetic properties of cerium-rich RTB sintered magnets

[0204]

[0205]

[0206] From the test results in Table 1, we can see that:

[0207] (1) The cerium-rich RTB sintered magnets (Examples 1 to 4) prepared by the process of the present invention are compared with the single alloy process magnets (Comparative Examples 1, 3, 5, and 7) with the same formula: ① The remanence, intrinsic coercivity, and maximum magnetic energy product of the magnets before grain boundary diffusion are improved; ② The coercivity increase value of the magnets after grain boundary diffusion is significantly increased, and the coercivity increase is significantly improved. This shows that the preparation method of the present invention can improve the magnetic properties of cerium-rich magnets, especially after grain boundary diffusion, it can improve the grain boundary diffusion effect of cerium-rich magnets and significantly improve the magnetic properties of cerium-rich magnets.

[0208] (2) The cerium-rich RTB sintered magnets (Examples 1 to 4) prepared by the process of the present invention are compared with the dual alloy process magnets (Comparative Examples 2, 4, 6, and 8) of the same formula without spherical transformation of the cerium-rich and rare earth-poor alloy powder: ① The remanence, intrinsic coercivity and maximum magnetic energy product before grain boundary diffusion are improved; ② The coercivity increase value after grain boundary diffusion is significantly increased, and the coercivity increase is also significantly improved. This shows that the preparation method of the present invention can improve the magnetic properties of cerium-rich magnets, especially after the grain boundary diffusion step, it can enhance the grain boundary diffusion effect of cerium-rich magnets and significantly improve the magnetic properties of cerium-rich magnets.

[0209] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0210] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a cerium-rich RTB-based sintered magnet, characterized in that: The following steps are involved: S1. preparing a mixed powder, wherein the mixed powder is obtained by uniformly mixing a first RTB alloy powder rich in cerium and poor in rare earth and a second RTB alloy powder poor in cerium and rich in rare earth, wherein the sphericity of the first RTB alloy powder is not less than 0.75; S2. Prepare the mixed powder into RTB based sintered magnet.

2. The preparation method according to claim 1, characterized in that The composition of the first RTB alloy powder is R x T y B z M a , wherein 29wt.%≤x≤30wt.%, 0.89wt.%≤z≤0.92wt.%, 0wt.%≤a≤0.5wt.%, y=100-xza; R is a rare earth element and must contain Ce and La, wherein Ce accounts for more than 20% of the total mass of R and La accounts for 5% to 10% of the total mass of R; T is a transition metal element and must contain Fe, wherein Fe accounts for more than 92% of the total mass of T; B is boron; M is an auxiliary metal element, consisting of one or a mixture of two or more of Cu, Al, Ga, Zn, Zr, Nb, and Ti; And / or, the composition of the second RTB alloy powder is R' b T' c B' d M' f , wherein 32wt.%≤b≤34wt.%, 0.88wt.%≤d≤0.91wt.%, 0.5wt.%≤f≤1.0wt.%, c=100-bdf; R' is a rare earth element and must contain Nd, and Nd accounts for more than 50% of the total mass of R; T' is a transition metal element and must contain Fe, wherein Fe accounts for 92% or more of the total mass of T; B' is boron; M' is an auxiliary metal element, which is composed of one or a mixture of two or more of Cu, Al, Ga, Zn, Zr, Nb, and Ti; Preferably, the rare earth element R further contains one or more of Pr, Nd, Dy, Tb, Gd, Ho, and Y, wherein Dy and / or Tb account for less than 5% of the total mass of R; And / or, the transition metal element T further contains Co, and Co accounts for less than 8% of the total mass of T; Preferably, the rare earth element R' further contains one or more of Ce, Pr, Dy, Tb, Gd, Ho, and Y, wherein Ce accounts for less than 10% of the total mass of R', and Dy and / or Tb accounts for less than 5% of the total mass of R; And / or, the transition metal element T' further contains Co, and Co accounts for less than 8% of the total mass of T'.

3. The method for preparing a cerium-rich RTB based sintered magnet according to claim 1, characterized in that: The average particle sizes of the first RTB alloy powder and the second RTB alloy powder are both 2.0-2.8 μm, and the difference between the average particle sizes of the two is less than 0.2 μm.

4. The method for preparing a cerium-rich RTB based sintered magnet according to claim 1, wherein: The first RTB alloy powder is obtained by spheroidization, wherein the spheroidization is carried out by mechanical grinding or high-temperature melting; Preferably, the mechanical grinding method includes stirring, rolling, collision or friction to grind away the sharp edges and corners on the surface of the powder particles to achieve sphericalization of the powder; Preferably, after the mechanical grinding step, a powder screening step is also included; Preferably, the high temperature melting is to melt the sharp edges and corners on the surface of the powder by heating, thereby achieving sphericalization of the powder; Preferably, the heating temperature is 1000-1050°C; Preferably, the heating method is resistance heating, induction heating, radio frequency induction plasma heating or laser heating; Preferably, after the high-temperature melting step, a crushing and powdering step is also included.

5. The method for preparing a cerium-rich RTB based sintered magnet according to claim 1, wherein: In the mixed powder, the mass ratio of the first RTB alloy powder to the second RTB alloy powder is (5-7):(3-5).

6. The method for preparing a cerium-rich RTB based sintered magnet according to claim 1, characterized in that: The step S2 includes the steps of oriented pressing, sintering and heat treating the mixed powder; Preferably, the oriented pressing molding is to mold the mixed powder in an oriented magnetic field with a strength of 1.2T to 1.5T in a protective atmosphere isolated from water and oxygen; And / or, the sintering temperature is 1030°C to 1080°C, and the sintering time is 3 to 5 hours; And / or, the heat treatment includes primary heat treatment and secondary heat treatment, the primary heat treatment temperature is 880°C to 920°C, the heat treatment time is 2 to 5 hours, and the secondary heat treatment temperature is 480°C to 560°C, and the heat treatment time is 2 to 5 hours.

7. The method for preparing a cerium-rich RTB-based sintered magnet according to any one of claims 1 to 6, characterized in that: The preparation method further comprises: step S3, diffusing heavy rare earth elements into the RTB-based sintered magnet using grain boundary diffusion technology.

8. The method for preparing a cerium-rich RTB based sintered magnet according to claim 7, characterized in that: The diffusion of heavy rare earth elements in step S3 comprises the following steps: Pre-treating the RTB-based sintered magnet; After the heavy rare earth diffusion source is attached to the surface of the pre-treated RTB series sintered magnet, a high temperature heat treatment is performed to complete the diffusion; Preferably, the heavy rare earth diffusion source is a substance containing heavy rare earth elements, and the mass proportion of the heavy rare earth elements in the heavy rare earth diffusion source is greater than 50%.

9. The method for preparing a cerium-rich RTB based sintered magnet according to claim 8, characterized in that: The high temperature heat treatment temperature is 800-920° C., and the heat treatment time is 5-15 hours.

10. A cerium-rich RTB-based sintered magnet, characterized in that: The cerium-rich RTB sintered magnet is prepared by the preparation method according to any one of claims 1 to 9; in the cerium-rich RTB sintered magnet, the mass of Ce accounts for more than 9.2% of the mass of rare earth.

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