High-performance cerium-rich magnet based on Laves phase regulation and preparation method thereof

Abstract

The invention relates to the technical field of rare earth permanent magnet materials, in particular to a high-performance cerium-rich magnet based on Laves phase regulation and a preparation method of the high-performance cerium-rich magnet. A preparation method of a high-performance cerium-rich magnet based on Laves phase regulation and control comprises the following steps that S1, main alloy magnetic powder is prepared, specifically, the main alloy magnetic powder with the component being (R < 1-x > Cex) < y > FebalCozTuBw is prepared, and R is one or more of rare earth elements Nd, Pr, Dy, Tb, Y, La and Gd; according to the preparation method of the high-performance cerium-rich magnet based on Laves phase regulation and control, the main alloy magnetic powder and the auxiliary alloy powder are subjected to component design, the cerium-rich magnet is subjected to grain boundary reconstruction, the magnetism and the distribution pattern of the Laves phase in the cerium-rich magnet are regulated and controlled, the magnetic coupling effect among main phase grains is weakened, the coercive force of the magnet is improved, and meanwhile the temperature stability of the magnet is improved; the technical problem that the coercive force and the temperature stability of a cerium-rich magnet are reduced due to the fact that the cerium content is increased is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rare earth permanent magnet materials, and particularly relates to a high-performance cerium-rich magnet based on Laves phase regulation and a preparation method thereof. BACKGROUND

[0002] At present, the application of high-abundance rare earth element cerium in neodymium-iron-boron magnets has attracted wide attention, and the high-performance research of cerium-rich magnets has become one of the important directions of the development of rare earth permanent magnet materials. However, in the cerium-rich magnet, a large number of Laves grain boundary phases dominated by cerium and iron elements and having an atomic ratio of 1:2 are easily formed. The melting point of the Laves phase is generally high, and the Laves phase is mostly distributed in the three-pronged grain boundaries, and has a small magnetic isolation effect on the main phase grains. In addition, Pr, Nd, Dy, Tb, Y and other elements are easy to enter the Laves phase, and the Curie temperature of the Laves phase is increased to above room temperature, so that the Laves phase presents ferromagnetism at room temperature. The coercive force of the ferromagnetic Laves phase is very low, which is a good soft magnetic phase. The soft magnetic phase is a good demagnetization nucleation point, which can deteriorate the coercive force of the magnet, and at the same time, the thin soft magnetic phase can cause the coupling between the main phase grains, further causing the demagnetization expansion between the main phase grains, and thus the cerium-rich magnet has the problems of decreased coercive force and temperature stability due to the increase of cerium content. SUMMARY

[0003] In view of the problems in the background art, the present application aims to provide a preparation method of a high-performance cerium-rich magnet based on Laves phase regulation. The main alloy magnetic powder and the auxiliary alloy powder are designed in composition, the grain boundary of the cerium-rich magnet is reconstructed, the magnetism and distribution form of the Laves phase in the cerium-rich magnet are regulated, the magnetic coupling effect between the main phase grains is weakened, the coercive force of the magnet is improved, and the temperature stability of the magnet is improved, thereby solving the technical problems of decreased coercive force and temperature stability of the cerium-rich magnet due to the increase of cerium content.

[0004] Another object of the present application is to provide a high-performance cerium-rich magnet based on Laves phase regulation prepared by the preparation method of the high-performance cerium-rich magnet based on Laves phase regulation, which has high coercive force and good temperature stability.

[0005] The above technical objects of the present application are achieved by the following technical solutions.

[0006] A preparation method of a high-performance cerium-rich magnet based on Laves phase regulation, comprising the following steps:

[0007] Step S1, preparation of a main alloy magnetic powder: a main alloy magnetic powder having a composition of (R 1-x Ce x ) y Fe bal Coz T u B w , wherein R is one or more elements selected from the group consisting of rare earth elements Nd, Pr, Dy, Tb, Y, La and Gd, T is one or more elements selected from the group consisting of Cr, Mn, Mo, Nb, Si, Ta, Ti, V, Zr, Ni, Al, Cu and Ga, x, y, bal, z, u and w are mass percentages, 0.2≤x≤0.8, 28≤y≤33, 0.5≤z≤4, 0≤u≤4, 0.8≤w≤1.1, and bal is the balance;

[0008] Step S2, preparation of the auxiliary alloy powder: preparing an auxiliary alloy powder with a composition of Q a M 1-a , wherein Q is one or more elements selected from the group consisting of rare earth elements Nd, Pr, Ce, Tb, Dy, Tm and Lu, M is one or more elements selected from the group consisting of Fe, Mn, Ni, Al, Cu, Ga, Co, O, H and F, and a is a mass percentage, 0≤a≤1;

[0009] Step S3, uniformly mixing the main alloy magnetic powder prepared in step S1 and the auxiliary alloy powder prepared in step S2 to obtain a mixed magnetic powder, wherein the auxiliary alloy powder accounts for 0.05-1.5% of the total weight of the mixed magnetic powder;

[0010] Step S4, sequentially performing orientation molding, sintering and heat treatment on the mixed magnetic powder to obtain a high-performance cerium-rich magnet based on Laves phase regulation.

[0011] Optionally, in step S2, the Q in the composition of the auxiliary alloy powder at least includes the Ce element, and the Ce element accounts for more than 50% of the total mass of the auxiliary alloy powder.

[0012] Optionally, in step S3, oxygen is introduced during the process of uniformly mixing the main alloy magnetic powder prepared in step S1 and the auxiliary alloy powder prepared in step S2, so that the oxygen content in the finally prepared high-performance cerium-rich magnet based on Laves phase regulation is 600-1500 ppm.

[0013] Optionally, the main alloy magnetic powder in step S1 is obtained by mixing magnetic powders with different compositions, and the composition of the main alloy magnetic powder obtained by mixing the magnetic powders with different compositions is (R 1-x Ce x ) y Fe bal Co z T u B w .

[0014] Optionally, the auxiliary alloy powder in the step S2 is obtained by mixing a plurality of alloy powders, and the composition of the auxiliary alloy powder obtained by mixing the plurality of alloy powders is Q a M 1-a .

[0015] Optionally, in the step S4, the sintering temperature for sintering is 950-1100 DEG C, and the holding time is 2-6 h.

[0016] Optionally, in the step S4, one-step heat treatment process is adopted when heat treatment is performed.

[0017] The one-step heat treatment is performed under the condition that the heat treatment temperature is 400-900 DEG C, and the holding time is 1-6 h.

[0018] Optionally, in the step S4, two-step heat treatment process is adopted when heat treatment is performed.

[0019] First, one-step heat treatment is performed under the condition that the heat treatment temperature is 600-900 DEG C, and the holding time is 30-120 min.

[0020] Then, two-step heat treatment is performed under the condition that the heat treatment temperature is 400-700 DEG C, and the holding time is 1-6 h.

[0021] A high-performance cerium-rich magnet based on Laves phase regulation, and a preparation method of the high-performance cerium-rich magnet based on Laves phase regulation.

[0022] Compared with the prior art, the embodiments of the application have the following beneficial effects:

[0023] By respectively designing the specific compositions of the main alloy magnetic powder and the auxiliary alloy powder, the grain boundaries of the cerium-rich magnet are reconstructed, and the multi-element synergistic effect of the auxiliary alloy powder and the main alloy magnetic powder is utilized. 14 The composition elements of the auxiliary alloy powder can reduce the magnetism (Curie temperature and saturation magnetization) of the Laves phase, improve the coercive force of the magnet, improve the intrinsic magnetic properties of the RE2Fe DETAILED DESCRIPTION

[0024] A preparation method of a high-performance cerium-rich magnet based on Laves phase regulation, comprising the following steps:

[0025] Step S1, preparation of main alloy magnetic powder: a main alloy magnetic powder with a composition of R 1-x Ce x ) y Fe bal Co z T u B w is prepared, wherein R is one or more elements selected from the group consisting of rare earth elements Nd, Pr, Dy, Tb, Y, La and Gd, T is one or more elements selected from the group consisting of Cr, Mn, Mo, Nb, Si, Ta, Ti, V, Zr, Ni, Al, Cu and Ga, x, y, bal, z, u and w are mass percentages, 0.2≤x≤0.8, 28≤y≤33, 0.5≤z≤4, 0≤u≤4, 0.8≤w≤1.1, and bal is the balance;

[0026] Step S2, preparation of auxiliary alloy powder: an auxiliary alloy powder with a composition of Q a M 1-a is prepared, wherein Q is one or more elements selected from the group consisting of rare earth elements Nd, Pr, Ce, Tb, Dy, Tm and Lu, M is one or more elements selected from the group consisting of Fe, Mn, Ni, Al, Cu, Ga, Co, O, H and F, and a is a mass percentage, 0≤a≤1;

[0027] Step S3, the main alloy magnetic powder prepared in step S1 is uniformly mixed with the auxiliary alloy powder prepared in step S2 to obtain a mixed magnetic powder, and the auxiliary alloy powder accounts for 0.05-1.5% of the total weight of the mixed magnetic powder;

[0028] Step S4, the mixed magnetic powder is sequentially subjected to orientation forming, sintering and heat treatment to obtain a high-performance cerium-rich magnet based on Laves phase regulation.

[0029] At present, the application of high-abundance rare earth element cerium in neodymium-iron-boron magnets has attracted widespread attention, and the high-performance research of cerium-rich magnets has become one of the important directions of the development of rare earth permanent magnet materials. However, in the cerium-rich magnet, a large amount of Laves grain boundary phase dominated by cerium and iron elements and having an atomic ratio of 1:2 is easily formed. The melting point of the Laves phase is generally high, and the Laves phase is mostly distributed in the triple junction, which has a small magnetic isolation effect on the main phase grains. In addition, Pr, Nd, Dy, Tb, Y and other elements are easy to enter the Laves phase, which increases the Curie temperature of the Laves phase to above room temperature, so that the Laves phase exhibits ferromagnetism at room temperature. The coercive force of this ferromagnetic Laves phase is very low, which is a good soft magnetic phase. The soft magnetic phase is a good demagnetization nucleation point, which will deteriorate the coercive force of the magnet, and at the same time, the thin soft magnetic phase will cause the coupling between the main phase grains, further leading to the expansion of the demagnetization between the main phase grains, and thus the cerium-rich magnet has the problems of decreased coercive force and reduced temperature stability due to the increase of cerium content.

[0030] The applicant found in the research that the magnetism and distribution of the Laves phase are key factors affecting the magnetic properties of the cerium-rich magnet, and the Curie temperature of the Laves phase formed by other rare earth elements and Fe is higher than 500 K except for the Ce element, however, the saturation magnetization of the Laves phase formed by elements such as Tb, Dy, Tm and Lu and Fe is reduced, which can also weaken the magnetism of the Laves phase, and the performance of the magnet can be improved by adding elements such as Tb, Dy, Tm and Lu. Compared with the Fe element, the Curie temperature of the Laves phase formed by rare earth elements and elements such as Mn, Co, Ni, Al and Cu is generally lower. In addition, the combination of H and the Laves phase can also reduce the Curie temperature. The present application further regulates the Curie temperature of the Laves phase by component design, so as to regulate the magnetism at room temperature, further improve the coercivity of the cerium-rich magnet, and obtain a high-performance cerium-rich magnet with high coercivity.

[0031] Specifically, the present application performs grain boundary reconstruction on the cerium-rich magnet by performing specific component design on the main alloy magnetic powder and the auxiliary alloy powder respectively, utilizes the multi-element synergistic effect of the auxiliary alloy powder and the main alloy magnetic powder, and the elements of the auxiliary alloy powder can reduce the magnetism (Curie temperature and saturation magnetization) of the Laves phase on the one hand, improve the coercivity of the magnet, and on the other hand, the composition elements of the auxiliary alloy powder can improve the intrinsic magnetic properties (Curie temperature, etc.) of the RE2Fe 14 B main phase, and further regulate the magnetism and distribution form of the Laves phase in the cerium-rich magnet, weaken the magnetic coupling effect between the main phase grains, improve the coercivity of the magnet, and improve the temperature stability and even the remanence of the magnet, the present application utilizes the multi-element synergistic effect of the auxiliary alloy composition elements and the main alloy in the grain boundary reconstruction process, obtains a high-performance cerium-rich magnet, and solves the technical problems of the reduction of the coercivity and temperature stability of the cerium-rich magnet due to the increase of the cerium content. 14

[0032] Further, the auxiliary alloy powder accounts for 0.05-1.5% of the total weight of the mixed magnetic powder, if the addition amount of the auxiliary alloy powder is too low, the multi-element synergistic effect with the main alloy magnetic powder cannot be achieved, and if the addition amount of the auxiliary alloy powder is too high, the remanence of the magnet will be significantly reduced.

[0033] In an embodiment of the present application, in the step S2, the Q in the composition of the auxiliary alloy powder at least includes the Ce element, and the Ce element accounts for more than 50% of the total mass of the auxiliary alloy powder.

[0034] ​By adding Ce element in the composition of the auxiliary alloy powder, and increasing the proportion of Ce element to more than 50% of the total mass of the auxiliary alloy powder, the Curie temperature of the Laves phase can be reduced to below room temperature, and the Laves phase can be paramagnetic at room temperature. When Q is Ce element, the effect of increasing the proportion of Ce element to more than 50% of the total mass of the auxiliary alloy powder is better. If the addition amount of other elements is too much, the Curie temperature of the Laves phase will increase.

[0035] Preferably, in the step S3, oxygen is introduced during the uniform mixing of the main alloy magnetic powder prepared in the step S1 and the auxiliary alloy powder prepared in the step S2, so that the oxygen content in the finally prepared high-performance cerium-rich magnet based on Laves phase regulation is 600-1500 ppm.

[0036] By introducing a small amount of oxygen during the uniform mixing of the main alloy magnetic powder and the auxiliary alloy powder in the step S3, the oxygen content in the finally prepared high-performance cerium-rich magnet based on Laves phase regulation is 600-1500 ppm. Because the appropriate oxygen content forms a certain amount of oxide to form voids between the grains, promote the formation of a continuous grain boundary thin layer, and promote the extension of the Laves phase to form a continuous grain boundary thin layer.

[0037] Further, the main alloy magnetic powder in the step S1 is obtained by mixing magnetic powders with different compositions. The composition of the main alloy magnetic powder obtained by mixing magnetic powders with different compositions is (R 1-x Ce x ) y Fe bal Co z T u B w .

[0038] By mixing magnetic powders with different compositions, a main alloy magnetic powder with an average composition of (R 1-x Ce x ) y Fe bal Co z T u B w .

[0039] Further, the auxiliary alloy powder in the step S2 is obtained by mixing a plurality of alloy powders. The composition of the auxiliary alloy powder obtained by mixing a plurality of alloy powders is Q a M 1-a .

[0040] By mixing a plurality of alloy powders, an auxiliary alloy powder with an average composition of Q a M 1-a .

[0041] Preferably, the sintering temperature in the step S4 is 950-1100℃, and the holding time is 2-6h.

[0042] Specifically, different sintering temperatures and holding times can be used according to the composition of the main alloy magnetic powder and the composition of the auxiliary alloy powder and the proportion of the auxiliary alloy powder in the mixed magnetic powder.

[0043] In one embodiment of the present application, in the step S4, one-step heat treatment process is used when heat treatment is performed.

[0044] The one-step heat treatment is performed at a heat treatment temperature of 400-900℃ and a holding time of 1-6h.

[0045] In another embodiment of the present application, in the step S4, two-step heat treatment process is used when heat treatment is performed.

[0046] First, one-step heat treatment is performed at a heat treatment temperature of 600-900℃ and a holding time of 30-120min;

[0047] Then, two-step heat treatment is performed at a heat treatment temperature of 400-700℃ and a holding time of 1-6h.

[0048] When heat treatment is performed, one-step heat treatment process or two-step heat treatment process is selected according to the composition of the magnet.

[0049] A high-performance cerium-rich magnet based on Laves phase regulation is prepared by the preparation method of the high-performance cerium-rich magnet based on Laves phase regulation.

[0050] The high-performance cerium-rich magnet prepared by the preparation method of the high-performance cerium-rich magnet based on Laves phase regulation has high coercivity and good temperature stability.

[0051] In order to facilitate the understanding of the present application, the present application will be described more fully below. The present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0052] Unless otherwise specified in the examples, the techniques or conditions described in the literature in the art or according to the product instructions are used. Unless otherwise specified, the reagents or instruments used are conventional products that can be obtained commercially.

[0053] (I) Example 1 and Comparative Example 1:

[0054] (1) Example 1:

[0055] A preparation method of a high-performance cerium-rich magnet based on Laves phase regulation, comprising the following steps:

[0056] Step S1, preparation of main alloy magnetic powder: magnetic powder with a composition of [(Pr 0.25 Nd 0.75 ) 0.5 Ce 0.5 ] 32 Fe bal Zr 0.15 Cu 0.12 Al 0.2 Co 0.8 B 0.9 Ga 0.15 and (Pr 0.25 Nd 0.75 ) 32 Fe bal Zr 0.15 Cu 0.12 Al 0.2 Co 0.8 B 0.9 Ga 0.15 is prepared by the processes of melting, rapid solidification, hydrogen decrepitation and jet milling, and the main alloy magnetic powder with a final composition of [(Pr 0.25 Nd 0.75 ) 0.6 Ce 0.4 ] 32 Fe bal Zr 0.15 Cu 0.12 Al 0.2 Co 0.8 B 0.9 Ga 0.15 is obtained by mixing the magnetic powders in a mass ratio of 4:1;

[0057] Step S2, preparation of auxiliary alloy powder: auxiliary alloy powder with a composition of Pr 0.2 Ce 0.2 Co 0.6 is prepared;

[0058] Step S3, uniformly mixing the main alloy magnetic powder prepared in step S1 and the auxiliary alloy powder prepared in step S2 to obtain a mixed magnetic powder, wherein the auxiliary alloy powder accounts for 0.2% of the total weight of the mixed magnetic powder;

[0059] Step S4, sequentially performing the following orientation forming, sintering and heat treatment on the mixed magnetic powder:

[0060] Orientation forming: the mixed magnetic powder is pressed into a green body under an orientation magnetic field of 1.8 T, and is subjected to isostatic pressing treatment under a pressure of 200 MPa;

[0061] Sintering: sintering treatment was carried out under the condition of sintering temperature of 1020℃ and holding time of 3h;

[0062] Heat treatment: one-step heat treatment process was adopted, and one-step heat treatment was carried out under the condition of heat treatment temperature of 650℃ and holding time of 3h;

[0063] A high-performance cerium-rich magnet based on Laves phase regulation was obtained.

[0064] (2) Comparative Example 1:

[0065] Compared with Example 1, the difference between Comparative Example 1 and Example 1 is that no auxiliary alloy powder with the composition of Pr 0.2 Ce 0.2 Co 0.6 was added in Comparative Example 1, and the main alloy magnetic powder was directly subjected to orientation molding, sintering and heat treatment in sequence, and the remaining preparation method was consistent with that of Example 1, thereby preparing a magnet.

[0066] (3) Magnetic property test and result analysis:

[0067] The magnetic properties of the magnets of Example 1 and Comparative Example 1 were tested by NIM-62000TB (permanent magnet material precision measurement system), and the test results are shown in Table 1, wherein B r represents remanence, H cj represents coercivity, (BH) max represents maximum magnetic energy product, and β (20℃-100℃) represents coercivity temperature coefficient (the smaller the absolute value of the coercivity temperature coefficient, the better the temperature stability of the magnet).

[0068] Table 1: Magnetic property test results of Example 1 and Comparative Example 1

[0069] From the test results, it can be seen that, by the multi-element synergistic effect of the main alloy magnetic powder and the auxiliary alloy powder, the Laves phase Curie temperature of Example 1 is reduced to 20℃, while the Laves phase Curie temperature of the magnet prepared in Comparative Example 1 is 42℃. At the same time, due to the improvement effect of Co and Pr elements on the 2:14:1 phase, the coercivity and temperature stability of the magnet of Example 1 are obviously better than those of Comparative Example 1 without adding auxiliary alloy powder.

[0070] (II) Example 2 and Comparative Example 2:

[0071] (1) Example 2:

[0072] A preparation method of a high-performance cerium-rich magnet based on Laves phase regulation, comprising the following steps:

[0073] Step S1, preparation of main alloy magnetic powder: a main alloy magnetic powder with a composition of Pr 0.25 Nd 0.75 ) 0.5 Ce 0.5 ] 31 Fe bal Zr 0.15 Cu 0.12 Al 0.2 Co 1.5 B 0.9 Ga 0.1 is prepared by a process of melting, rapid solidification, hydrogen decrepitation and jet milling;

[0074] Step S2, preparation of auxiliary alloy powder: an auxiliary alloy with a composition of Pr 50 Ce 50 is prepared, and a hydrogenated auxiliary alloy powder is prepared, the auxiliary alloy powder containing residual H elements, forming an alloy powder with a composition of Pr 50 Ce 50 H x , wherein x represents the amount of residual H elements;

[0075] Step S3, uniformly mixing the main alloy magnetic powder prepared in step S1 and the auxiliary alloy powder prepared in step S2 to obtain a mixed magnetic powder, wherein the auxiliary alloy powder accounts for 0.5% of the total weight of the mixed magnetic powder;

[0076] Step S4, sequentially performing orientation forming, sintering and heat treatment on the mixed magnetic powder:

[0077] Orientation forming: the mixed magnetic powder is pressed into a green body under an orientation magnetic field of 1.8 T, and is subjected to isostatic pressing treatment under a pressure of 200 MPa;

[0078] Sintering: sintering treatment is performed under the conditions of a sintering temperature of 1010℃ and a holding time of 3h;

[0079] Heat treatment: one-step heat treatment process is adopted, and one-step heat treatment is performed under the conditions of a heat treatment temperature of 600℃ and a holding time of 3h;

[0080] to obtain a high-performance cerium-rich magnet based on Laves phase regulation.

[0081] (2) Comparative Example 2:

[0082] Comparative Example 2 differs from Example 2 in that no hydrogenated auxiliary alloy powder with a composition of Pr 50 Ce 50 is added in Comparative Example 2, and the main alloy magnetic powder is directly subjected to orientation forming, sintering and heat treatment, and the remaining preparation methods are consistent with those of Example 2, to prepare a magnet.

[0083] (3) Magnetic property test and result analysis:

[0084] The magnetic properties of the magnets of Example 2 and Comparative Example 2 were tested by NIM-62000TB (permanent magnetic material precision measurement system), and the test results are shown in Table 2 below, wherein B r represents remanence, H cj represents coercivity, (BH) max represents maximum magnetic energy product, β (20℃-100℃) represents coercivity temperature coefficient (the smaller the absolute value of the coercivity temperature coefficient, the better the temperature stability of the magnet).

[0085] Table 2 Magnetic property test results of Example 2 and Comparative Example 2

[0086] From the test results, it can be seen that the Laves phase Curie temperature of Example 2 is significantly reduced to 15℃, and the Laves phase Curie temperature of Comparative Example 2 is 25℃. At the same time, due to the effect of Pr element on the 2:14:1 main phase, the coercivity and temperature stability of Example 2 are better than those of Comparative Example 2. Obviously, by adding Pr 50 Ce 50 hydrogenated auxiliary alloy powder, the magnet has higher coercivity and better temperature stability.

[0087] (Three) Example 3 and Comparative Example 3:

[0088] (1) Example 3:

[0089] A preparation method of a high-performance cerium-rich magnet based on Laves phase regulation, comprising the following steps:

[0090] Step S1, preparation of main alloy magnetic powder: a main alloy magnetic powder with a composition of [(Pr 0.25 Nd 0.75 ) 0.7 Ce 0.3 ] 32 Fe bal Zr 0.1 Cu 0.2 Al 0.2 Co 0.5 B 0.9 is prepared by the processes of melting, rapid solidification and sheeting, hydrogen breaking and air flow milling;

[0091] Step S2, preparation of auxiliary alloy powder: an auxiliary alloy powder with a composition of Al 0.5 Co 0.5 is prepared;

[0092] Step S3, uniformly mixing the main alloy magnetic powder prepared in step S1 with the auxiliary alloy powder prepared in step S2 to obtain a mixed magnetic powder, wherein the auxiliary alloy powder accounts for 1.0% of the total weight of the mixed magnetic powder;

[0093] Step S4, sequentially performing the following orientation forming, sintering and heat treatment on the mixed magnetic powder:

[0094] Orientation forming: the mixed magnetic powder is pressed into a green body under an orientation magnetic field of 1.8 T, and is subjected to isostatic pressing treatment under a pressure of 200 MPa;

[0095] Sintering: sintering treatment is performed under the condition that the sintering temperature is 1040℃ and the holding time is 4h;

[0096] Heat treatment: a two-step heat treatment process is adopted, primary heat treatment is performed at a heat treatment temperature of 890℃ for 120 min, and secondary heat treatment is performed at a heat treatment temperature of 650℃ for 3h;

[0097] to obtain a high-performance cerium-rich magnet based on Laves phase regulation.

[0098] (2) Comparative Example 3:

[0099] Compared with Example 3, the difference between Comparative Example 3 and Example 3 is that no auxiliary alloy powder with a component of Al 0.5 Co 0.5 is added in Comparative Example 3, and the main alloy magnetic powder is directly subjected to orientation forming, sintering and heat treatment, and the rest of the preparation method is consistent with that of Example 3, to prepare a magnet.

[0100] (3) Magnetic property test and result analysis:

[0101] The magnetic properties of the magnets of Example 3 and Comparative Example 3 are tested by NIM-62000TB (Permanent Magnetic Material Precision Measurement System), and the test results are shown in Table 3, wherein B r represents remanence, H cj represents coercive force, (BH) max represents maximum magnetic energy product, and β (20℃-100℃) represents the coercive force temperature coefficient (the smaller the absolute value of the coercive force temperature coefficient, the better the temperature stability of the magnet).

[0102] Table 3 Magnetic property test results of Example 3 and Comparative Example 3

[0103] From the test results, compared with Comparative Example 3, Example 3 adds Al 0.5 Co 0.5The introduction of the auxiliary alloy effectively reduces the Curie temperature of the Laves phase from 60℃ to 30℃, significantly weakens the room temperature magnetism of the Laves phase, and significantly improves the coercivity of the magnet. At the same time, due to the improvement of the Co element to the 2:14:1 main phase, the temperature stability of the magnet is improved, and the temperature stability of Example 3 is better.

[0104] (IV) Example 4 and Comparative Example 4:

[0105] (1) Example 4:

[0106] A preparation method of a high-performance cerium-rich magnet based on Laves phase regulation, comprising the following steps:

[0107] Step S1, preparation of main alloy magnetic powder: the main alloy magnetic powder with the composition of [(Pr, Nd) 0.4 Ce 0.6 ] 30 Fe bal Zr 0.15 B 0.96 Cu 0.12 Ga 0.5 Co 0.5 is prepared by the processes of melting, rapid solidification, hydrogen breaking and air flow grinding;

[0108] Step S2, preparation of auxiliary alloy powder: alloy powders with the compositions of Al 0.5 Ni 0.5 and Pr 0.25 Nd 0.75 are prepared, and the auxiliary alloy powder with the final composition of (Pr 0.25 Nd 0.75 ) 0.8 (Al 0.5 Ni 0.5 ) 0.2 is obtained by mixing the alloy powders in a mass ratio of 1:4;

[0109] Step S3, uniformly mixing the main alloy magnetic powder prepared in step S1 and the auxiliary alloy powder prepared in step S2 to obtain a mixed magnetic powder, wherein the auxiliary alloy powder accounts for 1.5% of the total weight of the mixed magnetic powder;

[0110] Step S4, sequentially performing the following orientation forming, sintering and heat treatment on the mixed magnetic powder:

[0111] Orientation forming: the mixed magnetic powder is pressed into a green body under an orientation magnetic field of 1.8 T, and is subjected to isostatic pressing treatment under a pressure of 200MPa;

[0112] Sintering: sintering treatment is performed under the conditions of a sintering temperature of 1010℃ and a holding time of 2.5h;

[0113] Heat treatment: one-step heat treatment process was adopted, and one-step heat treatment was carried out under the condition that the heat treatment temperature was 540℃ and the holding time was 3h.

[0114] A high-performance cerium-rich magnet based on Laves phase regulation was obtained.

[0115] (2) Comparative Example 4:

[0116] Compared with Example 4, the difference between Comparative Example 4 and Example 4 is that, in Comparative Example 4, the auxiliary alloy powder in Example 4 is not added, and the main alloy magnetic powder is directly subjected to orientation molding, sintering and heat treatment in sequence, and the rest of the preparation method is consistent with that of Example 4, thereby preparing a magnet.

[0117] (3) Magnetic property test and result analysis:

[0118] The magnetic properties of the magnets of Example 4 and Comparative Example 4 were tested by NIM-62000TB (Permanent Magnetic Material Precision Measurement System), and the test results are shown in Table 4, wherein B r represents remanence, H cj represents coercivity, (BH) max represents maximum magnetic energy product, β (20℃-100℃) represents coercivity temperature coefficient (the smaller the absolute value of the coercivity temperature coefficient, the better the temperature stability of the magnet).

[0119] Table 4 Magnetic property test results of Example 4 and Comparative Example 4

[0120] From the test results, it can be seen that the coercivity and temperature stability of the magnet of Example 4 are obviously better than those of the magnet of Comparative Example 4, and even the remanence is also higher than that of Comparative Example 4. The Curie temperature of the Laves phase of Example 4 is only 20℃, while the Curie temperature of the Laves phase of Comparative Example 4 is 30℃. This is because the auxiliary alloy powder improves the magnetism and distribution form of the Laves phase in the cerium-rich magnet, weakens the magnetic coupling effect between the main phase grains, improves the coercivity of the magnet, and at the same time, the Pr and Nd elements improve the intrinsic properties of the main phase, thereby improving the temperature stability and even the remanence of the magnet.

[0121] (Five) Example 5 and Comparative Example 5:

[0122] (1) Example 5:

[0123] Compared with Example 1, the difference between Example 5 and Example 1 is that, in step S3, oxygen is introduced during the process of uniformly mixing the main alloy magnetic powder and the auxiliary alloy powder, so that the oxygen content in the finally prepared high-performance cerium-rich magnet based on Laves phase regulation is 1000ppm, and the rest of the preparation method is consistent with that of Example 1, thereby obtaining a high-performance cerium-rich magnet based on Laves phase regulation.

[0124] (2) Comparative Example 5:

[0125] Comparative Example 5 is different from Example 1 in that in step S3, the auxiliary alloy powder accounts for 2% of the total weight of the mixed magnetic powder, and the remaining preparation method is consistent with that of Example 1, to obtain a magnetic powder.

[0126] (3) Magnetic property test and result analysis:

[0127] The magnetic properties of the magnets of Example 5 and Comparative Example 5 were tested by NIM-62000TB (Permanent Magnetic Material Precision Measurement System), and the test results are shown in Table 5, wherein B r represents remanence, H cj represents coercivity, (BH) max represents maximum magnetic energy product, and β (20℃-100℃) represents the coercivity temperature coefficient (the smaller the absolute value of the coercivity temperature coefficient, the better the temperature stability of the magnet).

[0128] Table 5 Magnetic property test results of Example 1, Example 5 and Comparative Example 5

[0129] Example 5 increases the oxygen content of the finally prepared magnet by introducing oxygen during the mixing of the main alloy magnetic powder and the auxiliary alloy powder, and a proper oxygen content forms a certain amount of oxides to form voids between the grains, promote the formation of a continuous grain boundary thin layer, promote the extension of the Laves phase to form a continuous grain boundary thin layer, and thus the coercivity of the magnet exceeds that of Example 1, and the coercivity of the magnet relative to Comparative Example 1 is increased more.

[0130] Comparative Example 5 significantly reduces the remanence of the magnet compared with Example 1 due to the excessive proportion of the auxiliary alloy powder.

[0131] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A method for preparing high-performance cerium-rich magnets based on Laves phase regulation, characterized in that: The following steps are involved: Step S1, preparation of main alloy magnetic powder: preparation composition (R 1-x Ce x ) y Fe bal Co z T u B w Main alloy magnetic powder, wherein R is one or more rare earth elements selected from the group consisting of Nd, Pr, Dy, Tb, Y, La, and Gd, T is one or more rare earth elements selected from the group consisting of Cr, Mn, Mo, Nb, Si, Ta, Ti, V, Zr, Ni, Al, Cu, and Ga, x, y, bal, z, u, and w are mass percentages, 0.2≤x≤0.8, 28≤y≤33, 0.5≤z≤4, 0≤u≤4, 0.8≤w≤1.1, and bal is the balance; Step S2, preparation of auxiliary alloy powder: preparation of the composition Q a M 1-a Auxiliary alloy powder, wherein Q is one or more rare earth elements selected from Nd, Pr, Ce, Tb, Dy, Tm and Lu, M is one or more rare earth elements selected from Fe, Mn, Ni, Al, Cu, Ga, Co, O, H and F, a is a mass percentage, 0≤a≤1; Step S3, uniformly mixing the main alloy magnetic powder obtained in step S1 with the auxiliary alloy powder obtained in step S2 to obtain mixed magnetic powder, wherein the auxiliary alloy powder accounts for 0.05 to 1.5% of the total weight of the mixed magnetic powder; Step S4: orienting, sintering, and heat treating the mixed magnetic powder in sequence to obtain a high-performance cerium-rich magnet based on Laves phase regulation.

2. The method for preparing high-performance cerium-rich magnets based on Laves phase regulation according to claim 1, characterized in that: In the step S2, Q in the components of the auxiliary alloy powder includes at least Ce element, and Ce element accounts for more than 50% of the total mass of the auxiliary alloy powder.

3. The method for preparing a high-performance cerium-rich magnet based on Laves phase regulation according to claim 1, characterized in that: In step S3, oxygen is introduced during the uniform mixing of the main alloy magnetic powder obtained in step S1 and the auxiliary alloy powder obtained in step S2, so that the oxygen content in the final high-performance cerium-rich magnet based on Laves phase regulation is 600-1500 ppm.

4. The method for preparing a high-performance cerium-rich magnet based on Laves phase regulation according to claim 1, characterized in that: The main alloy magnetic powder in step S1 is obtained by mixing magnetic powders of different compositions. The composition of the main alloy magnetic powder obtained by mixing magnetic powders of different compositions is (R 1-x Ce x ) y Fe bal Co z T u B w .

5. The method for preparing high-performance cerium-rich magnets based on Laves phase regulation according to claim 1, characterized in that: The auxiliary alloy powder in step S2 is obtained by mixing multiple alloy powders, and the composition of the auxiliary alloy powder obtained by mixing multiple alloy powders is Q a M 1-a .

6. The method for preparing a high-performance cerium-rich magnet based on Laves phase regulation according to claim 1, characterized in that: In the step S4, the sintering temperature is 950-1100° C., and the holding time is 2-6 hours.

7. The method for preparing a high-performance cerium-rich magnet based on Laves phase regulation according to claim 1, characterized in that: In step S4, a one-step heat treatment process is used for heat treatment: The one-step heat treatment is carried out under the conditions of a heat treatment temperature of 400 to 900° C. and a heat preservation time of 1 to 6 hours.

8. The method for preparing high-performance cerium-rich magnets based on Laves phase regulation according to claim 1, characterized in that: In step S4, a two-step heat treatment process is used for heat treatment: First, a heat treatment is performed at a heat treatment temperature of 600-900°C and a holding time of 30-120 minutes; Then, a secondary heat treatment is carried out under the conditions of a heat treatment temperature of 400 to 700° C. and a heat preservation time of 1 to 6 hours.

9. A high-performance cerium-rich magnet based on Laves phase regulation, characterized in that: The high-performance cerium-rich magnet is prepared using the preparation method based on Laves phase regulation as described in any one of claims 1 to 8.

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