CN116230380A - Preparation method of sintered NdFeB magnet with high remanence and high coercivity - Google Patents

Preparation method of sintered NdFeB magnet with high remanence and high coercivity Download PDF

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CN116230380A
CN116230380A CN202211635971.4A CN202211635971A CN116230380A CN 116230380 A CN116230380 A CN 116230380A CN 202211635971 A CN202211635971 A CN 202211635971A CN 116230380 A CN116230380 A CN 116230380A
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powder
sintered ndfeb
heat treatment
alloy
magnet
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付松
章兆能
胡校铭
沈晓杰
何响俊
刘孝莲
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Hangzhou Dianzi University
Zhejiang Innuovo Magnetics Industry Co Ltd
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Hangzhou Dianzi University
Zhejiang Innuovo Magnetics Industry Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered

Abstract

The invention relates to the technical field of sintered NdFeB magnets, in particular to a preparation method of a sintered NdFeB magnet with high remanence and high coercivity. The method comprises the steps of firstly preparing neodymium-iron-boron alloy and Al respectively 2 Tb alloy, then adopting two alloys to mix, and carrying out air flow grinding, orientation forming, isostatic pressing, sintering and heat treatment to prepare the sintered NdFeB magnet. The magnet prepared by the method is a sintered NdFeB magnet with high remanence and high coercivity; the grain size of the obtained magnet is obviously reduced, the structure is uniform, and the realization of the ideal structure finally improves the magnetic performance of the magnet.

Description

Preparation method of sintered NdFeB magnet with high remanence and high coercivity
Technical Field
The invention relates to the technical field of sintered NdFeB magnets, in particular to a preparation method of a sintered NdFeB magnet with high remanence and high coercivity.
Background
In recent years, due to high comprehensive magnetic performance and proper price of sintered NdFeB magnets, the sintered NdFeB magnets are increasingly valued in the fields of automobiles, household appliances and the like in the aspect of high-performance motors. Moreover, the current requirement for sintered NdFeB magnets is to have both high remanence and high coercivity.
It has been found that the coercivity can be improved by adding heavy rare earth elements such as Dy and Tb in the smelting process and performing grain boundary diffusion on the sintered magnet. However, both of these approaches have significant drawbacks. The former has high cost and cannot avoid the great reduction of residual magnetism, and the latter has complicated process flow and certain requirement on the size of the magnet.
In recent years, research shows that the addition of high-melting point metal can inhibit the growth of main phase grains, so that the grain size of refined crystals is uniform, the coercive force of a magnet is improved, the temperature stability is also improved, tb-Al alloy is taken as a high-melting point alloy, the main element of the Tb-Al alloy is rare earth element Tb, in the sintering process, the Tb-Al alloy slowly releases the Tb element, and the released Tb element reacts with NdFeB main phase, so that the effect of grain boundary diffusion is achieved.
Therefore, based on meeting the requirements of the market on the sintered NdFeB magnet with high remanence and high coercivity, a new preparation process is necessary to be developed to solve the related problems of higher cost, complicated flow and the like existing in the preparation of the corresponding magnet material at present.
Disclosure of Invention
The invention aims to solve the technical problems, and to overcome the defects in the prior art, the invention provides the preparation method of the sintered NdFeB magnet with high remanence and high coercivity.
Specifically, the invention adopts the following technical scheme:
a method for preparing a sintered NdFeB magnet with both high remanence and high coercivity, comprising the steps of:
a method for preparing a sintered NdFeB magnet with both high remanence and high coercivity, comprising the steps of:
step 1: preparing RFeBTm matrix raw materials in percentage by weight according to the proportion of R28-33 wt%, B0.8-1.2 wt%, tm 1-3 wt% and Fe as the rest, wherein R is one or more rare earth elements including Nd; tm is one or more of Co, cu, ga, zr, nb, ti;
step 2: mixing the substrate raw materials, and preparing the mixture into powder by adopting a melt-throwing and hydrogen crushing process, wherein the powder is neodymium-iron-boron powder;
step 3: preparing high-melting-point Al in a proportion of Tb 70wt% to 80wt% and Al 20wt% to 30wt% in percentage by weight 2 The Tb alloy is prepared from the raw materials,
step 4: mixing the alloy raw materials, preparing into powder by a melt-throwing ball mill, wherein the powder is Al 2 Tb alloy powder;
step 5: mixing NdFeB powder with Al 2 The Tb alloy powder is mixed with the neodymium iron boron powder and the Al according to the weight proportion 2 The blending proportion of the Tb alloy powder is 100:0.3-0.9;
step 6: and (3) carrying out air flow grinding, orientation molding, isostatic pressing, sintering and heat treatment on the blended mixture in sequence to obtain the sintered NdFeB magnet.
Preferably, in the step 2, the average particle size of the neodymium iron boron powder is in the range of 0.1-0.2 mm.
Preferably, in step 4, al 2 The average grain diameter of the Tb alloy powder is 0.1-0.2 mm.
Preferably, in step 6, the average particle size of the fine powder obtained by air flow milling is 2-4 microns.
Preferably, in step 6, the sintering temperature is 900-1100 ℃ and the sintering time is 8 hours.
Preferably, in the step 6, the heat treatment is performed by two rounds, wherein the temperature of the first round of heat treatment is 700-950 ℃, the heat preservation time of the heat treatment is 2-10 hours, and the temperature of the second round of heat treatment is 400-600 ℃ and the heat preservation time of the heat treatment is 3-10 hours after the heat treatment is cooled to room temperature.
Preferably, in the Tb-Al alloy, al 2 The proportion of Tb phase is above 70%.
A sintered NdFeB magnet prepared by the above preparation method, wherein the content of Tb and Al in the rare earth-rich grain boundary phase is higher than that in the main phase grains.
Compared with the prior art, the invention has the beneficial effects that:
firstly, by adopting the preparation method, the size of the magnet is not limited by blending Tb-Al alloy, and the coercive force of the magnet can be obviously improved while the residual magnetism is not reduced as much as possible, namely, the sintered NdFeB magnet with high residual magnetism and high coercive force at the same time;
secondly, the grain size of the obtained magnet is obviously reduced by adopting the preparation method provided by the invention, the structure is uniform, and the realization of the ideal structure finally improves the magnetic performance of the magnet.
Drawings
FIG. 1 is a photograph of a metallographic structure of example 1.
FIG. 2 is a photograph of a metallographic structure of example 2.
FIG. 3 is a photograph of a metallographic structure of example 3.
Fig. 4 is a photograph of a metallographic structure of comparative example 1.
Fig. 5 is a photograph of a metallographic structure of comparative example 2.
FIG. 6 is a photograph of a metallographic structure of comparative example 3.
FIG. 7 is a spectrum of example 3.
Detailed Description
Representative embodiments will now be further refined. It should be understood that the following description is not intended to limit the embodiments to one preferred embodiment. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the embodiments as defined by the appended claims.
Example 1:
NdFeB raw materials are mixed according to the mass ratio PrNd: fe: b: co: cu: ga: zr: ti=30.5: 67.64:0.92:0.5:0.1:0.2: and 0.12:0.12, the raw materials of praseodymium neodymium alloy, pure iron, high boron iron, electrolytic cobalt, electrolytic copper, metallic gallium, zirconium iron and ferrotitanium are matched into a part of matrix raw material, an alloy sheet is smelted by adopting a rapid hardening sheet technology, and casting is carried out after the alloy sheet is smelted, so that a strip sheet with the average thickness of 0.2-0.5 mm is obtained. The strip sheet is subjected to hydrogen crushing (HD) treatment to obtain hydrogen crushed powder, wherein the hydrogen content in the hydrogen crushed powder is 500-3000 ppm, and the average particle size range is 0.1-0.2 mm.
The Tb-Al raw material pure terbium and electrolytic aluminum are prepared according to the proportion of Tb: al=75:25, alloy flakes are smelted by adopting a rapid hardening flake technology, and casting is carried out after the alloy flakes are smelted, so that the strip sheet with the average thickness of 0.2-0.5 mm is obtained. Ball milling the strip pieces to obtain the product with average grain size of 0.1-0.2 mm.
The Tb-Al alloy powder and NdFeB hydrogen crushed powder are mixed according to the proportion of 0.3:100, and then mixed for 2-3 hours in a three-dimensional mixer. Carrying out air flow grinding and orientation molding on the mixed powder,
the sintering temperature is 1080 ℃, and the sintering time is 8 hours. The first heat treatment temperature is 900 ℃, the heat treatment time is 5 hours, the air is cooled to below 100 ℃ rapidly, then the temperature is raised again for the second heat treatment, the second heat treatment temperature is 500 ℃, and the aging time is 3 hours, thus obtaining the blank.
And (3) performing linear cutting on the blank, performing centerless grinding, performing end face grinding to obtain a sample with the diameter of 10 x 10, and performing magnetic property measurement on the sample.
Example 2:
NdFeB raw materials are mixed according to the mass ratio PrNd: fe: b: co: cu: ga: zr: ti=30.5: 67.64:0.92:0.5:0.1:0.2: and 0.12:0.12, the raw materials of praseodymium neodymium alloy, pure iron, high boron iron, electrolytic cobalt, electrolytic copper, metallic gallium, zirconium iron and ferrotitanium are matched into a part of matrix raw material, an alloy sheet is smelted by adopting a rapid hardening sheet technology, and casting is carried out after the alloy sheet is smelted, so that a strip sheet with the average thickness of 0.2-0.5 mm is obtained. The strip sheet is subjected to hydrogen crushing (HD) treatment to obtain hydrogen crushed powder, wherein the hydrogen content in the hydrogen crushed powder is 500-3000 ppm, and the average particle size range is 0.1-0.2 mm.
Tb-Al raw material terbium is prepared, electrolytic aluminum is prepared according to the proportion of Tb: al=75:25, alloy flakes are smelted by adopting a rapid hardening flake technology, and casting is carried out after smelting, so that the strip sheet with the average thickness of 0.2-0.5 mm is obtained. Ball milling the strip pieces to obtain the product with average grain size of 0.1-0.2 mm.
The Tb-Al alloy powder and NdFeB hydrogen crushed powder are mixed according to the proportion of 0.6:100, and then mixed for 2-3 hours in a three-dimensional mixer. Carrying out air flow grinding and orientation molding on the mixed powder,
the sintering temperature is 1080 ℃, and the sintering time is 8 hours. The heat treatment temperature is 900 ℃, the heat treatment time is 5 hours, the air is cooled to below 100 ℃ rapidly, then the temperature is raised again for the second heat treatment, the heat treatment temperature is 500 ℃ in the second step, and the aging time is 3 hours, thus obtaining the blank.
And (3) performing linear cutting on the blank, performing centerless grinding, performing end face grinding to obtain a sample with the diameter of 10 x 10, and performing magnetic property measurement on the sample.
Example 3:
NdFeB raw materials are mixed according to the mass ratio PrNd: fe: b: co: cu: ga: zr: ti=30.5: 67.64:0.92:0.5:0.1:0.2: and 0.12:0.12, the raw materials of praseodymium neodymium alloy, pure iron, high boron iron, electrolytic cobalt, electrolytic copper, metallic gallium, zirconium iron and ferrotitanium are matched into a part of matrix raw material, an alloy sheet is smelted by adopting a rapid hardening sheet technology, and casting is carried out after the alloy sheet is smelted, so that a strip sheet with the average thickness of 0.2-0.5 mm is obtained. The strip sheet is subjected to hydrogen crushing (HD) treatment to obtain hydrogen crushed powder, wherein the hydrogen content in the hydrogen crushed powder is 500-3000 ppm, and the average particle size range is 0.1-0.2 mm.
Tb-Al raw material terbium is prepared, electrolytic aluminum is prepared according to the proportion of Tb: al=75:25, alloy flakes are smelted by adopting a rapid hardening flake technology, and casting is carried out after smelting, so that the strip sheet with the average thickness of 0.2-0.5 mm is obtained. Ball milling the strip pieces to obtain the product with average grain size of 0.1-0.2 mm.
The Tb-Al alloy powder and NdFeB hydrogen crushed powder are mixed according to the proportion of 0.9:100, and then mixed for 2-3 hours in a three-dimensional mixer. Carrying out air flow grinding and orientation molding on the mixed powder,
the sintering temperature is 1080 ℃, and the sintering time is 8 hours. The heat treatment temperature is 900 ℃, the heat treatment time is 5 hours, the air is cooled to below 100 ℃ rapidly, then the temperature is raised again for the second heat treatment, the heat treatment temperature is 500 ℃ in the second step, and the aging time is 3 hours, thus obtaining the blank.
And (3) performing linear cutting on the blank, performing centerless grinding, performing end face grinding to obtain a sample with the diameter of 10 x 10, and performing magnetic property measurement on the sample.
Comparative example 1:
NdFeB raw materials are mixed according to the mass ratio PrNd: fe: b: co: cu: ga: zr: ti=30.5: 67.64:0.92:0.5:0.1:0.2: and 0.12:0.12, the raw materials of praseodymium neodymium alloy, pure iron, high boron iron, electrolytic cobalt, electrolytic copper, metallic gallium, zirconium iron and ferrotitanium are matched into a part of matrix raw material, an alloy sheet is smelted by adopting a rapid hardening sheet technology, and casting is carried out after the alloy sheet is smelted, so that a strip sheet with the average thickness of 0.2-0.5 mm is obtained. The strip sheet is subjected to hydrogen crushing (HD) treatment to obtain hydrogen crushed powder, wherein the hydrogen content in the hydrogen crushed powder is 500-3000 ppm, and the average particle size range is 0.1-0.2 mm.
Mixing in a three-dimensional mixer for 2-3 hours. Carrying out air flow grinding and orientation molding on the powder,
the sintering temperature is 1080 ℃, and the sintering time is 8 hours. The heat treatment temperature is 900 ℃, the heat treatment time is 5 hours, the heat treatment temperature in the second step is 500 ℃, and the aging time is 3 hours, thus obtaining a blank.
And (3) performing linear cutting on the blank, performing centerless grinding, performing end face grinding to obtain a sample with the diameter of 10 x 10, and performing magnetic property measurement on the sample.
Comparative example 2:
NdFeB raw materials are mixed according to the mass ratio PrNd: fe: b: co: cu: ga: zr: ti=30.5: 67.64:0.92:0.5:0.1:0.2: and 0.12:0.12, the raw materials of praseodymium neodymium alloy, pure iron, high boron iron, electrolytic cobalt, electrolytic copper, metallic gallium, zirconium iron and ferrotitanium are matched into a part of matrix raw material, an alloy sheet is smelted by adopting a rapid hardening sheet technology, and casting is carried out after the alloy sheet is smelted, so that a strip sheet with the average thickness of 0.2-0.5 mm is obtained. The strip sheet is subjected to hydrogen crushing (HD) treatment to obtain hydrogen crushed powder, wherein the hydrogen content in the hydrogen crushed powder is 500-3000 ppm, and the average particle size range is 0.1-0.2 mm.
Tb-Al raw material terbium is prepared, electrolytic aluminum is prepared according to the proportion of 90:10, an alloy sheet is smelted by adopting a rapid hardening sheet technology, and casting is carried out after smelting, so that a strip sheet with the average thickness of 0.2-0.5 mm is obtained. Ball milling the strip pieces to obtain the product with average grain size of 0.1-0.2 mm.
The Tb-Al alloy powder and NdFeB hydrogen crushed powder are mixed according to Tb, wherein Al=0.9: 100, and mixing for 2-3 hours in a three-dimensional mixer. And (3) carrying out jet milling on the mixed powder, carrying out orientation molding, wherein the sintering temperature is 1080 ℃, and the sintering time is 8 hours. The heat treatment temperature is 900 ℃, the heat treatment time is 5 hours, the heat treatment temperature in the second step is 500 ℃, and the aging time is 3 hours, thus obtaining a blank.
And (3) performing linear cutting on the blank, performing centerless grinding, performing end face grinding to obtain a sample with the diameter of 10 x 10, and performing magnetic property measurement on the sample.
Comparative example 3:
NdFeB raw materials are mixed according to the mass ratio PrNd: fe: b: co: cu: ga: zr: ti=30.5: 67.64:0.92:0.5:0.1:0.2:0.12:0.12, the raw materials of praseodymium neodymium alloy, pure iron, high boron iron, electrolytic cobalt, electrolytic copper, metallic gallium, zirconium iron and ferrotitanium are matched into a part of matrix raw material, and the strip sheet is subjected to hydrogen crushing (HD) treatment to obtain hydrogen crushed powder, wherein the hydrogen content in the hydrogen crushed powder is 500-3000 ppm, and the average particle size range is 0.1-0.2 mm.
Tb-Al raw material terbium is prepared, electrolytic aluminum is prepared according to the proportion of Tb: al=50:50, alloy flakes are smelted by adopting a rapid hardening flake technology, and casting is carried out after smelting, so that the strip sheet with the average thickness of 0.2-0.5 mm is obtained. Ball milling the strip pieces to obtain the product with average grain size of 0.1-0.2 mm.
The Tb-Al alloy powder and NdFeB hydrogen crushed powder are mixed according to the proportion of 0.9:100, and mixing for 2-3 hours in a three-dimensional mixer. Carrying out air flow grinding and orientation molding on the mixed powder,
the sintering temperature is 1080 ℃, and the sintering time is 8 hours. The heat treatment temperature is 900 ℃, the heat treatment time is 5 hours, the heat treatment temperature in the second step is 500 ℃, and the aging time is 3 hours, thus obtaining a blank.
And (3) performing linear cutting on the blank, performing centerless grinding, performing end face grinding to obtain a sample with the diameter of 10 x 10, and performing magnetic property measurement on the sample.
With respect to each of the above examples and comparative examples, examples 1-3 are examples of preparations of different proportions carried out using the method of the present invention.
Comparative example 1 is a sample prepared in a predetermined ratio using NdFeB as a raw material.
Comparative example 2 and comparative example 3 are samples prepared using Tb-Al raw materials outside the range of the compounding ratio with the present invention.
The results of the performance tests performed by testing the products of the above examples and comparative examples are summarized below.
Metallographic observations of the samples of examples 1 to 3 and comparative examples 1 to 3 are shown in FIGS. 1 to 6.
FIG. 1 is a photograph of the metallographic structure of example 1, calculated and analyzed by matalab, having 3233 grains therein, each grain having an average area of 58.3um 2 。
Fig. 2: the metallographic photograph of example 2, which was analyzed by calculation using matalab, has 2650 grains with an average grain area of 45.9um each 2 。
Fig. 3: the metallographic photograph of example 3, which was analyzed by calculation using matalab, has 2761 grains with an average grain area of 39.1um each 2 。
Fig. 4: metallographic photograph of comparative example 1, in which 2384 grains were present and an average grain area of 91um was obtained by calculation analysis using matalab 2 。
Fig. 5: metallographic photograph of comparative example 1, having 2514 grains therein with an average grain area of 87.3um per grain, was analyzed by calculation using matalab 2 。
Fig. 6: metallographic photograph of comparative example 3, in which 2440 grains were present and an average grain area of 75.9um per grain was calculated and analyzed by matalab 2 。
FIG. 7 is a spectrum of example 3, and the following results were obtained by analysis of FIG. 7.
First, table 1 shows the magnetic property test results of comparative examples of the respective examples.
Table 2 shows the grain boundary phase energy spectrum analysis of example 3.
Table 3 shows the rare earth rich phase energy spectrum analysis of example 3.
Table 4 shows the principal phase energy spectrum analysis of example 3.
TABLE 1
Br(kGs) Hcj(kOe) SQ
Example 1 14.40 15.51 98.7％
Example two 14.30 15.92 97.9％
Example III 14.28 16.81 97.6％
Comparative example one 14.29 14.56 98.5％
Comparative example two 14.08 15.32 92.3％
Comparative example three 13.95 14.87 90.1％
TABLE 2
Spectrogram 1
Element(s) Line type Weight percent Wt％Sigma Atomic percent
Fe K-wire system 46.56 1.24 69.16
Nd L-line system 37.42 1.19 21.52
Pr L-line system 14.32 1.00 8.43
Al K-wire system 0.00 0.18 0.00
Tb L-line system 1.70 1.66 0.89
Total amount of 100.00 100.00
TABLE 3 Table 3
Figure BDA0004007260440000061
Figure BDA0004007260440000071
TABLE 4 Table 4
Spectrogram 6
Element(s) Line type Weight percent Wt％Sigma Atomic percent
Fe K-wire system 71.98 1.07 86.71
Nd L-line system 21.28 0.92 9.93
Pr L-line system 6.66 0.84 3.18
Tb L-line system 0.00 1.80 0.00
Al K-wire system 0.07 0.05 0.19
Total amount of 100.00 100.00
It can be seen from the combination of table 1, fig. 1 and fig. 2 that the sintered nd-fe-b permanent magnet prepared by the method of the present invention has significantly reduced grain size, significantly improved coercivity, substantially no decrease in remanence, and no limitation on the size of the magnet.
From the data in Table 1, it can be seen that, in comparative examples 2 and 3, when the content of Tb or Al is out of the recommended range of the present invention, al and Tb enter the main phase in a large amount during sintering, the remanence is greatly reduced and the squareness is deteriorated as compared with examples 1 to 3.
From table 2, table 3, and table 4, it can be seen that the use of Tb-Al alloy in the present invention has a slow release effect, which causes Tb to be released slowly during sintering, so that Tb exists mainly in the rare earth rich phase and a small amount in the grain boundary phase, and is substantially absent from the main item.
The above technical problems underlying the present invention are addressed by the present invention, which provides a method for preparing a magnet for solving the problems of the prior art. Firstly, by adopting the preparation method, the size of the magnet is not limited by blending Tb-Al alloy, and the coercive force of the magnet can be obviously improved while the residual magnetism is not reduced as much as possible, namely, the sintered NdFeB magnet with high residual magnetism and high coercive force at the same time;
secondly, the grain size of the obtained magnet is obviously reduced by adopting the preparation method provided by the invention, the structure is uniform, and the realization of the ideal structure finally improves the magnetic performance of the magnet.
It will be apparent to those skilled in the art that certain modifications, combinations and variations are possible in light of the above teachings.

Claims (8)

1. A preparation method of a sintered NdFeB magnet with high remanence and high coercivity is characterized by comprising the following steps: the method specifically comprises the following steps:
step 1: preparing RFeBTm matrix raw materials in percentage by weight according to the proportion of R28-33 wt%, B0.8-1.2 wt%, tm 1-3 wt% and Fe as the rest, wherein R is one or more rare earth elements including Nd; tm is one or more of Co, cu, ga, zr, nb, ti;
step 2: mixing the substrate raw materials, and preparing the mixture into powder by adopting a melt-throwing and hydrogen crushing process, wherein the powder is neodymium-iron-boron powder;
step 3: preparing high-melting-point Al in a proportion of Tb 70wt% to 80wt% and Al 20wt% to 30wt% in percentage by weight 2 The Tb alloy is prepared from the raw materials,
step 4: mixing the alloy raw materials, preparing into powder by a melt-throwing ball mill, wherein the powder is Al 2 Tb alloy powder;
step 5: mixing NdFeB powder with Al 2 The Tb alloy powder is mixed with the neodymium iron boron powder and the Al according to the weight proportion 2 The blending proportion of the Tb alloy powder is 100:0.3-0.9;
step 6: and (3) carrying out air flow grinding, orientation molding, isostatic pressing, sintering and heat treatment on the blended mixture in sequence to obtain the sintered NdFeB magnet.
2. The method for producing a sintered NdFeB magnet having both high remanence and high coercivity according to claim 1, characterized by: in the step 2, the average particle size of the neodymium iron boron powder is in the range of 0.1-0.2 mm.
3. The method for producing a sintered NdFeB magnet having both high remanence and high coercivity according to claim 1, characterized by: in step 4, al 2 The average grain diameter of the Tb alloy powder is 0.1-0.2 mm.
4. The method for producing a sintered NdFeB magnet having both high remanence and high coercivity according to claim 1, characterized by: in the step 6, the average granularity of the micropowder obtained by the jet mill is 2-4 microns.
5. The method for producing a sintered NdFeB magnet having both high remanence and high coercivity according to claim 1, characterized by: in the step 6, the sintering temperature is 900-1100 ℃ and the sintering time is 8-10 hours.
6. The method for producing a sintered NdFeB magnet having both high remanence and high coercivity according to claim 1, characterized by: in the step 6, the heat treatment is carried out by two rounds, wherein the heat treatment temperature of the first round is 700-950 ℃, the heat treatment heat preservation time is 2-10 hours, and the heat treatment temperature of the second round is 400-600 ℃ and the heat treatment heat preservation time is 3-10 hours after the heat treatment is cooled to room temperature.
7. The method for producing a sintered NdFeB magnet having both high remanence and high coercivity according to claim 1, characterized by: in Tb-Al alloy, al 2 The proportion of Tb phase is above 70%.
8. Sintered NdFeB magnet produced by the production process according to any one of the preceding claims, characterized in that: in the magnet, the contents of Tb and Al in the rare earth-rich grain boundary phase are higher than the contents of the inside of the grains of the main phase.
CN202211635971.4A 2022-12-20 2022-12-20 Preparation method of sintered NdFeB magnet with high remanence and high coercivity Pending CN116230380A (en)

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