CN114664507A - High-performance rare earth permanent magnetic material with composite hard magnetic shell structure and preparation method thereof - Google Patents

High-performance rare earth permanent magnetic material with composite hard magnetic shell structure and preparation method thereof Download PDF

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CN114664507A
CN114664507A CN202210392117.3A CN202210392117A CN114664507A CN 114664507 A CN114664507 A CN 114664507A CN 202210392117 A CN202210392117 A CN 202210392117A CN 114664507 A CN114664507 A CN 114664507A
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rare earth
heavy rare
equal
magnet
main phase
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金佳莹
张志恒
周良
林正自
秦发祥
严密
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Zhejiang University ZJU
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    • 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
    • H01F1/0576—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 pressed, e.g. hot working
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    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
    • 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
    • H01F41/0253—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 for manufacturing permanent magnets
    • 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
    • H01F41/0253—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 for manufacturing permanent magnets
    • H01F41/0293—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 for manufacturing permanent magnets diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets

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Abstract

The invention discloses a high-performance rare earth permanent magnetic material with a composite hard magnetic shell structure and a preparation method thereof, based on a multi-main-phase alloy technology and a grain boundary diffusion technology, a multi-main-phase sintered magnet is prepared firstly, and main-phase grains form a heavy rare earth-rich hard magnetic shell; then, the heavy rare earth alloy film is deposited on the surface of the multi-main-phase magnet through magnetron sputtering, and a new hard magnetic shell layer with higher heavy rare earth content is formed on the surface of the main-phase crystal grain through crystal boundary diffusion and low-temperature tempering heat treatment. The main phase crystal grain has multiple layers of heavy rare earth-rich hard magnetic shells, so that a diamagnetic domain nucleation field is effectively improved, and the coercivity is greatly improved; the magnetic dilution effect of the heavy rare earth elements is effectively reduced, and high remanence is kept; has continuous rare earth-rich grain boundary phase, effectively isolates the short-range magnetic exchange effect of adjacent grains, and further improves the coercivity. The invention provides a method for efficiently utilizing heavy rare earth elements, prepares a rare earth permanent magnet material with high coercive force and high magnetic energy product, and meets the urgent application requirements of emerging industries such as high-temperature rare earth permanent magnet motors and the like.

Description

High-performance rare earth permanent magnetic material with composite hard magnetic shell structure and preparation method thereof
Technical Field
The invention relates to the field of rare earth permanent magnet, in particular to a high-performance rare earth permanent magnet material with a composite hard magnetic shell structure and a preparation method thereof.
Background
The third generation rare earth permanent magnet neodymium iron boron has incomparable high magnetic energy product compared with other permanent magnet materials, is particularly beneficial to realizing the miniaturization, light weight and thinning of instruments and instruments, is widely applied to the fields of energy, traffic, information, medical treatment, national defense and the like, and develops into an indispensable strategic functional material in various fields of modern society, military and people. Especially sintered Nd-Fe-B material, after more than 30 years of development, the performance of the magnet is continuously improved, and the maximum magnetic energy product (BH)maxAnd remanence BrThe experimental values are all close to the theoretical values. However, the coercivity H of the sintered NdFeB materialcjThe content of the sintered neodymium iron boron material is still low, and is only 1/5-1/3 of a theoretical value, so that the application of the sintered neodymium iron boron material in the high-temperature field is limited to a great extent.
The addition of heavy rare earth element Dy/Tb partially replaces Nd, and is the most conventional method for improving the coercive force of the sintered Nd-Fe-B magnet at present. However, the heavy rare earth atoms such as Dy/Tb and the like are antiferromagnetically coupled with Fe atoms, so that the maximum magnetic energy product and remanence of the magnet are seriously reduced by adding Dy/Tb excessively in the rare earth permanent magnet. At present, it is generally believed that the coercive force of the sintered Nd-Fe-B magnet is determined by the mechanism of anti-magnetization domain nucleation, and the theoretical limit value is the intrinsic magnetocrystalline anisotropy field H of the main phase of the ferromagnetism of 2:14:1AThe actual value is closely related to the composition/defects of the main phase grain epitaxial layer and the distribution of the Nd-rich phase among the main phase grains. In practical magnets, the main phase grain epitaxial layer composition is generally deviated from the positive stoichiometric ratio due to structural defects, so that the main phase grain epitaxial layer composition has a low magnetocrystalline anisotropy field HAIt is easy to become the nucleation site of the anti-magnetization domain.
In order to improve the utilization efficiency of the heavy rare earth Dy/Tb and avoid the anti-ferromagnetic coupling between Dy/Tb atoms and Fe atoms, the formation of a heavy rare earth-rich magnetic hard shell layer on the main phase crystal grain epitaxial layer is an effective approach. The coercive force of the sintered rare earth magnet is not only related to the intrinsic magnetocrystalline anisotropy field, but also closely related to the distribution of the rare earth-rich grain boundary phase. The method optimizes the wettability between the main phase and the rare earth-rich grain boundary phase, forms continuous grain boundary phase in the magnet, isolates the short-range magnetic exchange coupling effect between adjacent main phase grains, and is also an important way for improving the coercive force of the magnet.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a high-performance rare earth permanent magnet material with a composite magnetic hard shell layer structure and a preparation method thereof.
The invention aims at providing a preparation method of a high-performance rare earth permanent magnet material with a composite hard magnetic shell structure, which comprises the steps of firstly preparing a multi-main-phase magnet with a heavy rare earth-rich hard magnetic shell by utilizing a main-phase alloy I without heavy rare earth and one or more main-phase alloys II added with heavy rare earth; then, the heavy rare earth alloy film is deposited on the surface of the multi-main-phase magnet through magnetron sputtering, and a new hard magnetic shell layer with higher heavy rare earth content is formed on the surface of the main-phase crystal grain through crystal boundary diffusion and low-temperature tempering heat treatment.
Wherein, the main phase alloy I without heavy rare earth comprises RE by mass percentx1QbalMy1Bz1RE is one or more of other lanthanide rare earth elements except heavy rare earth elements Dy and Tb, Q is one or more of Fe, Co and Ni, M is one or more of Al, Cr, Cu, Ga, Mn, Mo, N, Nb, P, Pb, Si, Ta, Ti, V and Zr, B is boron, and x1, y1 and z1 satisfy the following relations: x1 is more than or equal to 27 and less than or equal to 36, y1 is more than or equal to 0 and less than or equal to 3, and z1 is more than or equal to 0.8 and less than or equal to 1.2;
wherein, the main phase alloy II added with heavy rare earth comprises the following components (RE) in percentage by masswHRE1-w)x2QbalMy2Bz2RE is other thanOne or more of heavy rare earth elements Dy and Tb and other lanthanide rare earth elements, HRE is one or two of heavy rare earth elements Dy and Tb, Q is one or more of Fe, Co and Ni, M is one or more of Al, Cr, Cu, Ga, Mn, Mo, N, Nb, P, Pb, Si, Ta, Ti, V and Zr, B is boron, and x2, y2, z2 and w satisfy the following relations: w is more than or equal to 0.2 and less than or equal to 0.8, x2 is more than or equal to 26 and less than or equal to 35, y2 is more than or equal to 0 and less than or equal to 3, and z2 is more than or equal to 0.85 and less than or equal to 1.15;
wherein the heavy rare earth alloy film comprises the following components in percentage by mass HREaREbQbalNcHRE is one or two of heavy rare earth elements Dy and Tb, RE is one or more of other lanthanide rare earth elements except for the heavy rare earth elements Dy and Tb, Q is one or more of Fe, Co and Ni, N is one or more of Al, Cu, Ga, Zn, Mn and Mg, and a, b and c satisfy the following relations: a is more than or equal to 20 and less than or equal to 70, b is more than or equal to 2 and less than or equal to 15, and c is more than or equal to 0 and less than or equal to 10.
Preferably: the method specifically comprises the following steps:
1) the main phase alloy I without heavy rare earth and the main phase alloy II added with heavy rare earth are respectively proportioned, and the vacuum degree is less than or equal to 10-2Respectively smelting different main phase alloys in a vacuum medium-frequency induction furnace of Pa, obtaining a main phase alloy throwing sheet with the thickness of 0.2-0.6 mm by adopting a rapid hardening sheet casting technology, and respectively preparing main phase alloy I powder and main phase alloy II powder with the average particle size of 2-4 mu m by hydrogen breaking and air flow milling processes;
2) under the protection of nitrogen or argon, uniformly mixing main phase alloy I and main phase alloy II powders with different components according to a proportion to obtain mixed main phase powders with different heavy rare earth addition amounts;
3) carrying out orientation compression on the obtained mixed main phase powder under a 1.5-2.0T magnetic field to obtain a green body;
4) carrying out cold isostatic pressing at 150-250 MPa after vacuum packaging the obtained green body, and then sintering in a high-vacuum positive-pressure sintering furnace to obtain a sintered magnet;
5) carrying out surface pretreatment on the obtained sintered magnet to ensure that the surface roughness Ra of the magnet is less than or equal to 0.1 mu m and the surface has no oil stain;
6) feeding the target materialActivating, and vacuumizing to 1 × 10-3～1×10-4Pa, then introducing high-purity argon to adjust the vacuum degree to 1.5 multiplied by 10-21.0Pa, adjusting target power to be 60-140W, bias voltage to be 70-130V and working time to be 5-15 min; then starting a direct current power supply, bombarding the surface of the target material for 5-15 min, and removing an oxide layer on the surface of the target material;
7) performing magnetron sputtering on the surface of the magnet treated in the step 5), depositing a heavy rare earth alloy film, introducing high-purity argon, controlling the flow rate to be 15-60 sccm, the sputtering power to be 60-220W, the sputtering time to be 0.5-6 h, and controlling the thickness of the deposited heavy rare earth alloy film to be 1-30 mu m;
8) and carrying out grain boundary diffusion treatment and low-temperature tempering heat treatment on the deposited magnet in a high-vacuum annealing furnace to obtain the high-performance rare earth permanent magnet material with the composite hard magnetic shell structure.
Preferably, the grain boundary diffusion treatment schedule in the step 8) is as follows: performing grain boundary diffusion at 650-1000 ℃ for 0.5-12 h, wherein the low-temperature tempering heat treatment system is as follows: heat treatment is carried out for 2-5 hours at the temperature of 420-650 ℃.
The second purpose of the invention is to provide a high-performance rare earth permanent magnetic material with a composite hard magnetic shell structure, which is prepared by the preparation method.
Preferably: the final magnet main phase crystal grain epitaxial layer is provided with a plurality of heavy rare earth-rich hard magnetic shell layers, and the heavy rare earth-rich hard magnetic shell layers comprise two or more than two main phase crystal grain cores with low content of heavy rare earth n1 and main phase crystal grain cores with high content of heavy rare earth n2, a main phase crystal grain hard magnetic shell layer with high content of heavy rare earth n3, and a main phase crystal grain hard magnetic shell layer with higher content of heavy rare earth n4 on the outermost layer. Wherein n1 is more than n3 and more than n2, n1 is more than n3 and more than n4, the coercive force of the magnet is improved, and the remanence of the magnet is kept.
Preferably: finally, the magnet has a continuous rare earth-rich grain boundary phase, the short-range magnetic exchange effect between adjacent grains is effectively isolated, and the coercive force of the magnet is improved.
Compared with the prior art, the invention has the following beneficial effects:
1) the invention innovatively designs the components of the multi-main-phase alloy and the grain boundary diffusion alloy in a synergistic manner, and the main-phase grain epitaxial layer of the magnet is provided with a plurality of layers of heavy rare earth-rich hard magnetic shells, so that the anti-magnetization domain nucleation field in the magnet can be effectively improved, the anti-magnetization domain nucleation can be inhibited, and the coercive force of the magnet can be further improved.
2) The diffusion source designed in the grain boundary diffusion technology is heavy rare earth alloy HREaREbQbalNcThe proportion of heavy rare earth and other rare earth is optimally designed, the proportion of 3d transition metal Fe/Co/Ni and other alloy elements is optimally designed, the physicochemical property and the diffusion efficiency of a diffusion source are regulated and controlled, the components and the distribution of a new hard magnetic shell layer are controlled, the thickness of a deposited heavy rare earth alloy film is controlled to be 1-30 mu m, the use efficiency of the heavy rare earth element is effectively improved, excessive nonmagnetic elements are not additionally introduced to cause a magnetic dilution effect, a continuous grain boundary phase is formed after grain boundary diffusion and heat treatment, the short-range magnetic exchange effect of adjacent main phase grains is isolated, and the coercive force of a magnet can be greatly improved while the remanence of the magnet is kept.
3) Compared with the existing magnet with a single hard magnetic shell, the rare earth permanent magnet material with the composite hard magnetic shell structure provided by the invention has the advantages that the heavy rare earth is more reasonably distributed, the contribution to improving the coercive force of the magnet is larger, and the residual magnetism of the magnet can be kept.
4) The heavy rare earth alloy film is deposited by utilizing a magnetron sputtering technology, has strong bonding force with a matrix, is uniform and compact, and promotes the crystal boundary diffusion process; the magnetron sputtering technology can accurately control the thickness of the film, and the magnetron sputtering technology is used as a diffusion source, so that the number of the diffusion sources can be accurately controlled, and waste caused by enrichment of excessive heavy rare earth elements on the surface of a magnet is avoided.
Detailed Description
The present invention is further illustrated by the following examples, but is not limited to the following examples:
example 1:
1) the main phase alloy I component without heavy rare earth is (Pr) calculated by mass percentage0.2Nd0.8)32.0FebalCo0.5Nb0.2Ga0.3Al0.3Cu0.2B1.05Adding ofThe heavy rare earth has a main phase alloy II component of [ (Pr)0.2Nd0.8)0.25Dy0.75]32.0FebalCo0.5Nb0.2Ga0.3Al0.3Cu0.2B1.05At vacuum degree of less than or equal to 10-2Respectively smelting a main phase alloy I and a main phase alloy II in a Pa vacuum intermediate frequency induction furnace, obtaining a main phase alloy throwing sheet with the thickness of-0.35 mm by adopting a rapid hardening sheet casting technology, and preparing main phase alloy I and main phase alloy II powder with the average particle size of-3.3 mu m by hydrogen breaking and air flow milling processes;
2) under the protection of nitrogen, main phase alloy I and main phase alloy II powders with different components are uniformly mixed according to the mass ratio of 23:1 to obtain the component (Pr)0.2Nd0.8)31.0Dy1.0FebalCo0.5Nb0.2Ga0.3Al0.3Cu0.2B1.05The mixed main phase powder of (1);
3) carrying out orientation compression on the obtained mixed main phase powder under a-1.8T magnetic field to obtain a green body;
4) carrying out cold isostatic pressing at 200MPa after vacuum packaging the obtained green body, and then sintering in a high-vacuum positive-pressure sintering furnace at the sintering temperature of 1065 ℃ for 3h to obtain a sintered magnet;
5) carrying out surface pretreatment on the obtained sintered magnet to ensure that the surface roughness Ra of the magnet is less than or equal to 0.1 mu m and the surface has no oil stain;
6) the target material comprises Dy in percentage by mass60Pr10Fe30Activating the target material, and vacuumizing to 2 × 10-4Pa, then introducing high-purity argon to adjust the vacuum degree to 4 x 10-2Pa, regulating the target power to 110W, the bias voltage to 110V and the working time to 5 min; then starting a direct current power supply, bombarding the surface of the target material for 5min, and removing the oxide layer on the surface of the target material;
7) performing magnetron sputtering on the surface of the magnet treated in the step 5), depositing a heavy rare earth alloy film, introducing high-purity argon, controlling the flow rate to be 30sccm, the sputtering power to be 100W, the sputtering time to be 1h, and controlling the thickness of the deposited rare earth alloy film to be 4 mu m;
8) and (3) carrying out 900 ℃ grain boundary diffusion treatment on the deposited magnet in a high vacuum annealing furnace for 6h, and carrying out 500 ℃ low-temperature tempering heat treatment for 4h to obtain the high-performance rare earth permanent magnet material with the composite hard magnetic shell structure.
EPMA element surface distribution results show that a composite hard magnetic shell structure exists in a main phase crystal grain epitaxial layer of the magnet, namely a Dy-rich hard magnetic shell introduced by a multi-main phase technology and a Dy-rich hard magnetic shell introduced by a grain boundary diffusion technology at the outermost layer; the test result of the AMT-4 permanent magnet characteristic measuring instrument shows that the magnetic property of the magnet is Br＝13.7kG，Hcj＝28.1kOe，(BH)max＝47.1MGOe。
Comparative example 1:
the difference from the example 1 is that the magnet is not subjected to magnetron sputtering, and the EPMA element surface distribution result shows that only a single layer of Dy-rich hard magnetic shell structure exists in the main phase crystal grain epitaxial layer of the magnet; the test result of the AMT-4 permanent magnet characteristic measuring instrument shows that the magnetic property of the magnet is Br＝13.7kG，Hcj＝20.5kOe，(BH)max＝45.9MGOe。
Example 2:
1) the main phase alloy I component without heavy rare earth is (Pr) calculated by mass percentage0.1Nd0.85Ho0.05)32.0FebalCo0.3Zr0.2Ga0.3Al0.35Cu0.15B1.02The main phase alloy II added with heavy rare earth has the composition of [ (Pr)0.1Nd0.85Ho0.05)0.25Dy0.75]32.0FebalCo0.3Zr0.2Ga0.3Al0.35Cu0.15B1.02At vacuum degree of less than or equal to 10- 2Respectively smelting a main phase alloy I and a main phase alloy II in a vacuum intermediate frequency induction furnace of Pa, obtaining a main phase alloy throwing sheet with the thickness of-0.35 mm by adopting a rapid hardening sheet casting technology, and preparing main phase alloy I and main phase alloy II powder with the average particle size of-3.3 mu m by hydrogen breaking and air flow milling processes;
2) under the protection of argon, the main phase alloy I and the main phase alloy II with different compositions are pulverized according to the massUniformly mixing at a ratio of 11:1 to obtain a component (Pr)0.2Nd0.75Ho0.05)31.0Dy2.0FebalCo0.3Zr0.2Ga0.3Al0.35Cu0.15B1.02Mixed main phase powder of (1);
3) carrying out orientation compression on the obtained mixed main phase powder under a-1.8T magnetic field to obtain a green body;
4) carrying out cold isostatic pressing at-180 MPa after vacuum packaging the obtained green body, and then sintering in a high-vacuum positive-pressure sintering furnace at the sintering temperature of 1070 ℃ for 3h to obtain a sintered magnet;
5) performing surface pretreatment on the magnet obtained in the step 4) to ensure that the surface roughness Ra of the magnet is less than or equal to 0.1 mu m and the surface has no oil stain;
6) the target material comprises Tb in percentage by mass70Pr5Fe15Al10Activating the target material, and vacuumizing to 1 × 10-4Pa, then introducing high-purity argon to adjust the vacuum degree to 1.5 multiplied by 10-2Pa, adjusting the target power to 120W, the bias voltage to 120V and the working time to 8 min; then starting a direct current power supply, bombarding the surface of the target for 15min, and removing an oxide layer on the surface of the target;
7) carrying out magnetron sputtering on the surface of the magnet treated in the step 5), depositing a heavy rare earth alloy film, introducing high-purity argon, controlling the pressure to be 25sccm, the sputtering power to be 110W, the sputtering time to be 3.5h, and controlling the thickness of the deposited rare earth alloy film to be 15 mu m;
8) and (3) carrying out 890 ℃ grain boundary diffusion treatment on the deposited magnet in a high vacuum annealing furnace for 9h, and carrying out 480 ℃ low-temperature tempering heat treatment for 3h to obtain the high-performance rare earth permanent magnet material with the composite hard magnetic shell structure.
EPMA element surface distribution results show that a composite hard magnetic shell structure exists in a main phase grain epitaxial layer of the magnet, namely a Dy-rich hard magnetic shell introduced by a multi-main phase technology and a Tb-rich hard magnetic shell introduced by a grain boundary diffusion technology at the outermost layer; the test result of the AMT-4 permanent magnet characteristic measuring instrument shows that the magnetic property of the magnet is Br＝13.4kG，Hcj＝35.5kOe，(BH)max＝44.6MGOe。
Comparative example 2:
the difference from the example 2 is that the magnet is not subjected to magnetron sputtering, and the EPMA element surface distribution result shows that only a single layer of Dy-rich hard magnetic shell structure exists in the main phase crystal grain epitaxial layer of the magnet; the test result of the AMT-4 permanent magnet characteristic measuring instrument shows that the magnetic property of the magnet is Br＝13.5kG，Hcj＝23.8kOe，(BH)max＝43.9MGOe。
Example 3:
1) the components are respectively proportioned according to the designed main phase components, and the main phase alloy I without heavy rare earth is Nd in percentage by mass30.0FebalCo0.3Nb0.2Ta0.05Ti0.1Al0.25Cu0.2Ga0.1B1.0The main phase alloy II added with heavy rare earth comprises (Nd)0.5Dy0.5)30.0FebalCo0.3Nb0.2Ta0.05Ti0.1Al0.25Cu0.2Ga0.1B1.0At vacuum degree of less than or equal to 10-2Respectively smelting a main phase alloy I and a main phase alloy II in a vacuum intermediate frequency induction furnace of Pa, obtaining a main phase alloy throwing sheet with the thickness of 0.28mm by adopting a rapid hardening sheet casting technology, and preparing main phase alloy I and main phase alloy II powder with the average particle size of 3.0 mu m through hydrogen breaking and jet milling processes;
2) under the protection of nitrogen, uniformly mixing the main phase alloy I and the main phase alloy II powder according to the mass ratio of 9:1 to obtain the Nd component28.5Dy1.5FebalCo0.3Nb0.2Ta0.05Ti0.1Al0.25Cu0.2Ga0.1B1.0Mixed main phase powder of (1);
3) carrying out orientation compression on the obtained mixed main phase powder under a-1.6T magnetic field to obtain a green body;
4) carrying out cold isostatic pressing at 190MPa after vacuum packaging the obtained green body, and then sintering in a high-vacuum positive-pressure sintering furnace at 1075 ℃ for 3h to obtain a sintered magnet;
5) performing surface pretreatment on the magnet obtained in the step 4) to ensure that the surface roughness Ra of the magnet is less than or equal to 0.1 mu m and the surface has no oil stain;
6) the target material comprises Dy in percentage by mass30Tb50Pr2Fe10Ga8Activating the target material, firstly vacuumizing to 8 x 10-4Pa, then introducing high-purity argon to adjust the vacuum degree to 8 x 10-2Pa, regulating the target power to be 100W, the bias voltage to be 100V and the working time to be 6 min; then starting a direct current power supply, bombarding the surface of the target material for 6min, and removing an oxide layer on the surface of the target material;
7) performing surface magnetron sputtering on the magnet treated in the step 5), depositing a heavy rare earth alloy film, introducing high-purity argon, controlling the flow rate to be 20sccm, the sputtering power to be 95W, controlling the sputtering time to be 3h, and controlling the thickness of the deposited rare earth alloy film to be 10 mu m;
8) and (3) carrying out 850 ℃ grain boundary diffusion treatment on the deposited magnet in a high vacuum annealing furnace for 9h, and carrying out 480 ℃ low-temperature tempering heat treatment for 4h to obtain the high-performance rare earth permanent magnet material with the composite hard magnetic shell structure.
EPMA element surface distribution results show that a composite hard magnetic shell structure exists in a main phase crystal grain epitaxial layer of the magnet, namely a Dy-rich hard magnetic shell introduced by a multi-main phase technology and a Dy/Tb-rich hard magnetic shell introduced by a grain boundary diffusion technology at the outermost layer; the test result of the AMT-4 permanent magnet characteristic measuring instrument shows that the magnetic property of the magnet is Br＝13.6kG，Hcj＝30.1kOe，(BH)max＝46.0MGOe。
Comparative example 3:
the difference from the example 3 is that the magnet is not subjected to magnetron sputtering, and the EPMA element surface distribution result shows that only a single layer of Dy-rich hard magnetic shell structure exists in the main phase crystal grain epitaxial layer of the magnet; the test result of the AMT-4 permanent magnet characteristic measuring instrument shows that the magnetic property of the magnet is Br＝13.6kG，Hcj＝22.5kOe，(BH)max＝44.7MGOe。
Example 4:
1) the main phase alloy I component without heavy rare earth is (Pr) calculated by mass percentage0.2Nd0.8)31.0FebalCo0.3Zr0.2Ga0.5Al0.1Cu0.2B0.95The main phase alloy II added with heavy rare earth has the composition of [ (Pr)0.2Nd0.8)0.4Tb0.6]31.0FebalCo0.3Zr0.2Ga0.5Al0.1Cu0.2B0.95At vacuum degree of less than or equal to 10-2Respectively smelting a main phase alloy I and a main phase alloy II in a Pa vacuum intermediate frequency induction furnace, obtaining a main phase alloy throwing sheet with the thickness of 0.30mm by adopting a rapid hardening sheet casting technology, and preparing main phase alloy I and main phase alloy II powder with the average particle size of 3.1 mu m through hydrogen breaking and air flow grinding processes;
2) under the protection of argon, uniformly mixing main phase alloy I and main phase alloy II powder with different components according to the mass ratio of 5:1 to obtain the component (Pr)0.2Nd0.8)27.9Tb3.1FebalCo0.3Zr0.2Ga0.5Al0.1Cu0.2B0.95The mixed main phase powder of (1);
3) carrying out orientation compression on the obtained mixed main phase powder under a-2.0T magnetic field to obtain a green body;
4) carrying out cold isostatic pressing at 200MPa after vacuum packaging the obtained green body, and then sintering in a high-vacuum positive-pressure sintering furnace at the sintering temperature of 1070 ℃ for 3.5h to obtain a sintered magnet;
5) performing surface pretreatment on the magnet obtained in the step 4) to ensure that the surface roughness Ra of the magnet is less than or equal to 0.1 mu m and the surface has no oil stain;
6) the target material comprises Dy in percentage by mass10Tb60Ce5Al5Cu5Fe15Activating the target material, firstly vacuumizing to 1 × 10-3Pa, then introducing high-purity argon to adjust the vacuum degree to 2 x 10-2Pa, adjusting the target power to 100W, the bias voltage to 100V and the working time to 8 min; then starting a direct current power supply, bombarding the surface of the target for 10min, and removing an oxide layer on the surface of the target;
7) performing surface magnetron sputtering on the magnet treated in the step 5), depositing a heavy rare earth alloy film, introducing high-purity argon, controlling the flow rate to be 35sccm, the sputtering power to be 120W, and the sputtering time to be 4h, and controlling the thickness of the deposited rare earth alloy film to be 20 mu m;
8) and then carrying out 880 ℃ grain boundary diffusion treatment for 12h in a high vacuum annealing furnace, and carrying out 480 ℃ low-temperature tempering heat treatment for 5h to obtain the high-performance rare earth permanent magnetic material with the composite hard magnetic shell structure.
EPMA element surface distribution results show that a composite hard magnetic shell structure exists in a main phase grain epitaxial layer of the magnet, namely a Tb-rich hard magnetic shell layer introduced by a multi-main phase technology and a Dy/Tb-rich hard magnetic shell layer introduced by a grain boundary diffusion technology at the outermost layer; the test result of the AMT-4 permanent magnet characteristic measuring instrument shows that the magnetic property of the magnet is Br＝13.1kG，Hcj＝38.2kOe，(BH)max＝41.2MGOe。
Comparative example 4:
the difference from the embodiment 4 is that the magnet is not subjected to magnetron sputtering, and the EPMA element surface distribution result shows that only a single-layer Tb-rich hard magnetic shell structure exists in the main phase crystal grain epitaxial layer of the magnet; the test result of the AMT-4 permanent magnet characteristic measuring instrument shows that the magnetic property of the magnet is Br＝13.2kG，Hcj＝27.2kOe，(BH)max＝42.3MGOe。

Claims (6)

1. A preparation method of a high-performance rare earth permanent magnetic material with a composite hard magnetic shell structure is characterized by comprising the following steps: firstly, preparing a multi-main-phase magnet with a heavy rare earth-rich hard magnetic shell layer by using a main-phase alloy I without heavy rare earth and one or more main-phase alloys II added with heavy rare earth; then, the heavy rare earth alloy film is deposited on the surface of the multi-main-phase magnet through magnetron sputtering, and a new hard magnetic shell layer with higher heavy rare earth content is formed on the surface of the main-phase crystal grain through crystal boundary diffusion and low-temperature tempering heat treatment.
Wherein, the main phase alloy I without heavy rare earth comprises RE by mass percentx1QbalMy1Bz1RE is one or more of other lanthanide rare earth elements except heavy rare earth elements Dy and Tb, Q is one or more of Fe, Co and Ni, M is one or more of Al, Cr, Cu, Ga, Mn, Mo, N, Nb, P, Pb, Si, Ta, Ti, V and ZrOne or more, B is boron, and x1, y1 and z1 satisfy the following relations: x1 is more than or equal to 27 and less than or equal to 36, y1 is more than or equal to 0 and less than or equal to 3, and z1 is more than or equal to 0.8 and less than or equal to 1.2;
wherein, the main phase alloy II added with heavy rare earth comprises the following components (RE) in percentage by masswHRE1-w)x2QbalMy2Bz2RE is one or more of other lanthanide rare earth elements except heavy rare earth elements Dy and Tb, HRE is one or two of heavy rare earth elements Dy and Tb, Q is one or more of Fe, Co and Ni elements, M is one or more of Al, Cr, Cu, Ga, Mn, Mo, N, Nb, P, Pb, Si, Ta, Ti, V and Zr elements, B is boron element, and x2, y2, z2 and w satisfy the following relations: w is more than or equal to 0.2 and less than or equal to 0.8, x2 is more than or equal to 26 and less than or equal to 35, y2 is more than or equal to 0 and less than or equal to 3, and z2 is more than or equal to 0.85 and less than or equal to 1.15;
wherein the heavy rare earth alloy film comprises the following components in percentage by mass HREaREbQbalNcHRE is one or two of heavy rare earth elements Dy and Tb, RE is one or more of other lanthanide rare earth elements except for the heavy rare earth elements Dy and Tb, Q is one or more of Fe, Co and Ni, N is one or more of Al, Cu, Ga, Zn, Mn and Mg, and a, b and c satisfy the following relations: a is more than or equal to 20 and less than or equal to 70, b is more than or equal to 2 and less than or equal to 15, and c is more than or equal to 0 and less than or equal to 10.
2. The method for preparing a high-performance rare earth permanent magnetic material with a composite hard magnetic shell structure according to claim 1, comprising the following steps:
1) the main phase alloy I without heavy rare earth and the main phase alloy II added with heavy rare earth are respectively proportioned, and the vacuum degree is less than or equal to 10-2Respectively smelting different main phase alloys in a vacuum medium-frequency induction furnace of Pa, obtaining a main phase alloy throwing sheet with the thickness of 0.2-0.6 mm by adopting a rapid hardening sheet casting technology, and respectively preparing main phase alloy I powder and main phase alloy II powder with the average particle size of 2-4 mu m by hydrogen breaking and air flow milling processes;
2) under the protection of nitrogen or argon, uniformly mixing main phase alloy I and main phase alloy II powders with different components according to a proportion to obtain mixed main phase powders with different heavy rare earth addition amounts;
3) carrying out orientation compression on the obtained mixed main phase powder under a 1.5-2.0T magnetic field to obtain a green body;
4) carrying out cold isostatic pressing at 150-250 MPa after vacuum packaging the obtained green body, and then sintering in a high-vacuum positive-pressure sintering furnace to obtain a sintered magnet;
5) carrying out surface pretreatment on the obtained sintered magnet to ensure that the surface roughness Ra of the magnet is less than or equal to 0.1 mu m and the surface has no oil stain;
6) activating the target material, and vacuumizing to 1 × 10-3～1×10-4Pa, then introducing high-purity argon to adjust the vacuum degree to 1.5 multiplied by 10-21.0Pa, adjusting target power to be 60-140W, bias voltage to be 70-130V and working time to be 5-15 min; then starting a direct current power supply, bombarding the surface of the target material for 5-15 min, and removing an oxide layer on the surface of the target material;
7) performing magnetron sputtering on the surface of the magnet treated in the step 5), depositing a heavy rare earth alloy film, introducing high-purity argon, controlling the flow rate to be 15-60 sccm, the sputtering power to be 60-220W, the sputtering time to be 0.5-6 h, and controlling the thickness of the deposited heavy rare earth alloy film to be 1-30 mu m;
8) and carrying out grain boundary diffusion treatment and low-temperature tempering heat treatment on the deposited magnet in a high-vacuum annealing furnace to obtain the high-performance rare earth permanent magnet material with the composite hard magnetic shell structure.
3. The method for preparing a high-performance rare earth permanent magnetic material with a composite hard magnetic shell structure according to claim 2, wherein the grain boundary diffusion treatment system in the step 8) is as follows: performing grain boundary diffusion at 650-1000 ℃ for 0.5-12 h, wherein the low-temperature tempering heat treatment system is as follows: heat treatment is carried out for 2-5 hours at the temperature of 420-650 ℃.
4. A high-performance rare earth permanent magnetic material with a composite hard magnetic shell structure, which is characterized by being prepared by the preparation method of any one of claims 1 to 3.
5. A high performance rare earth permanent magnetic material with a composite hard magnetic shell structure as claimed in claim 4 wherein the final magnet main phase grain epitaxial layer has multiple heavy rare earth rich hard magnetic shells including two or more of a low heavy rare earth content n1 main phase grain core and a high heavy rare earth content n2 main phase grain core, and a high heavy rare earth content n3 main phase grain hard magnetic shell, and an outermost higher heavy rare earth content n4 main phase grain hard magnetic shell. Wherein n1 is more than n3 and more than n2, n1 is more than n3 and more than n4, the coercive force of the magnet is improved, and the remanence of the magnet is kept.
6. The high-performance rare earth permanent magnetic material with the composite hard magnetic shell structure as claimed in claim 4, wherein the final magnet has a continuous rare earth-rich grain boundary phase, thereby effectively isolating the short-range magnetic exchange effect between adjacent grains and improving the coercive force of the magnet.
CN202210392117.3A 2022-04-14 2022-04-14 High-performance rare earth permanent magnetic material with composite hard magnetic shell structure and preparation method thereof Pending CN114664507A (en)

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