High cobalt rare earth permanent magnet material and method for preparing the same

Abstract

The application relates to a high-cobalt rare earth permanent magnet material and a preparation method thereof, and belongs to the technical field of rare earth permanent magnet materials. The high-cobalt rare earth permanent magnet material comprises the following components in percentage by mass: RE a Co b M c TM e Fe 100‑a‑b‑c‑d B d , 28<=a<=35, 15<=b<=30, 0.5<=c<=1.2, 0.95<=d<=1.2, 0.2<=e<=3; RE is one or a combination of Pr, Nd, La, Ce, Y, Gd, Tb, Dy and Ho; M is one or a combination of Cu and Al; TM is one or a combination of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo and Mn; the microstructure comprises a main phase and a grain boundary phase, the Co-rich phase in the grain boundary phase accounts for less than or equal to 5% of the total volume fraction of the grain boundary phase; and the Co:M mass percentage in the Co-rich phase is 5:1-100:1. The microstructure of the magnet can be optimized, and the coercivity of the magnet is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rare earth permanent magnet materials, and particularly relates to a high-cobalt rare earth permanent magnet material and a preparation method thereof. BACKGROUND

[0002] Sintered rare earth permanent magnet materials have the advantages of high magnetic performance, easy processing and high cost performance, and are widely used in the fields of wind power generation and the like. With the vigorous development of new energy automobile, intelligent robot and precision instrument industries in recent years, higher requirements are put forward for sintered rare earth permanent magnet materials: the sintered rare earth permanent magnet materials have higher magnetic performance and also have higher temperature stability. At present, the typical values of the temperature coefficient of residual magnetism and the temperature coefficient of coercivity of ordinary neodymium-iron-boron magnets are-0.11% / ℃ and-0.75% / ℃, which limits the application of the sintered rare earth permanent magnet materials in the fields of high-speed motors and precision instruments.

[0003] Related researches show that the use of Co to replace Fe can significantly improve the Curie temperature of the magnet, thereby improving the temperature stability of the magnet. However, for high-Co magnets (Co content is greater than or equal to 15 wt%), there are a large number of cobalt-rich aggregation zones with large sizes in the grain boundary phase of the magnet, and these aggregation zones contain various phases that deteriorate the coercivity, such as RECo2, RECo5, RE2Co 17 , etc. The existence of these phases reduces the demagnetization coupling effect of the grain boundary on one hand, and blocks the flow channel of the rare earth-rich phase on the other hand, resulting in a lack of thin-layer grain boundaries. CN111640549A discloses a sintered rare earth permanent magnet material with high temperature stability and a preparation method thereof. The magnet prepared by the method has a cobalt-poor zone with a Co content lower than that in the main phase grain and a cobalt-rich zone with a Co content higher than that in the main phase grain in the grain boundary, and a large number of phases such as RECo2, RECo5, RE2Co 17 , etc. exist in the cobalt-rich zone, which will cause the coercivity of the magnet to decrease. In order to improve the coercivity of the high-Co magnet, the existing method adds heavy rare earth Dy / Tb and the like to the magnet, which will cause the cost of the magnet to increase significantly, and also cause the maximum magnetic energy product of the magnet to decrease, thereby restricting the application and promotion of the high-Co magnet. SUMMARY

[0004] In view of the above analysis, the embodiments of the present application aim to provide a high-cobalt rare earth permanent magnet material and a preparation method thereof, so as to solve the problem that the existence of a large-area cobalt-rich zone in a rare earth permanent magnet material with high Co content causes the coercivity of the magnet to decrease.

[0005] The main purpose of the present application is achieved by the following technical solutions:

[0006] The present application provides a high-cobalt rare earth permanent magnet material, and the composition of the high-cobalt rare earth permanent magnet material is as follows in terms of mass percentage: RE a Co b Mc TM e Fe 100-a-b-c-d B d , wherein 28≤a≤35, 15≤b≤30, 0.5≤c≤1.2, 0.95≤d≤1.2, 0.2≤e≤3; RE is one or a combination of several of Pr, Nd, La, Ce, Y, Gd, Tb, Dy, Ho elements; M is one or a combination of two of Cu, Al, and TM is one or a combination of several of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo, Mn;

[0007] The microstructure of the high-cobalt rare earth permanent magnet material comprises a main phase and a grain boundary phase, the main phase is a main phase of RE:(Fe, Co):B=2:14:1 structure, and the grain boundary phase is composed of an RE-rich phase and a small amount of Co-rich phase;

[0008] In the grain boundary phase, the Co-rich phase accounts for ≤5% of the total volume fraction of the grain boundary phase; the mass percentage of Co:M in the composition of the Co-rich phase is 5:1-100:1;

[0009] The Co-rich phase internally contains, but is not limited to, one or more of RE2(Fe, Co) phase, RE(Fe, Co) phase, RE(Fe, Co)2 phase, RE(Fe, Co)3 phase, RE(Fe, Co)4B phase, RE(Fe, Co)5 phase, RE2(Fe, Co) 17 phase and Co-containing amorphous phase.

[0010] Further, the mass percentage of M in the RE-rich phase is ≥2c.

[0011] The application also provides a preparation method of a high-cobalt rare earth permanent magnet material, which is used for preparing the high-cobalt rare earth permanent magnet material, and adopts a grain boundary doping method to add M elements to the high-cobalt rare earth permanent magnet material, and comprises the following steps:

[0012] Step 1: preparing an added magnet, wherein the magnet is in one of a rapid quenching and tape casting sheet, a magnet hydrogen broken powder and a magnet airflow mill powder;

[0013] Step 2: preparing an M-containing alloy, wherein the M-containing alloy is in one of a powder after breaking a cast ingot prepared by melting, a rapid quenching and tape casting sheet, an M-containing alloy hydrogen broken powder or an M-containing alloy airflow mill powder;

[0014] Step 3: mixing the added magnet and the M-containing alloy according to a certain proportion, performing hydrogen breaking or airflow milling, and then performing orientation forming under a magnetic field with a magnetic field strength of 1.6 T or more to obtain a magnet blank, and performing cold isostatic pressing on the blank to prepare a magnet green body with a density of 3-5 g / cm 3 ;

[0015] Step 4: sintering the magnet green body, the sintering temperature is 1000-1200℃, and the holding time is 2-8h;

[0016] Step 5: primary tempering at 800-950℃, the holding time is 2-8h; secondary tempering at 400-650℃, the holding time is 3-10h, to obtain the finished magnet product.

[0017] Further, in step 1, the prepared magnet is added, including the following steps:

[0018] Raw material preparation: according to the permanent magnet material mass percentage chemical formula RE a Co b M c TM e Fe 100-a-b-c-d B d Configure the raw material, wherein 28≤a≤35, 15≤b≤30, 0.5≤c≤1.2, 0.95≤d≤1.2, 0.2≤e≤3; RE is one or a combination of several of Pr, Nd, La, Ce, Y, Gd, Tb, Dy, Ho elements; M is one or a combination of Cu and Al; TM is one or a combination of several of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo, Mn;

[0019] Preparation of rapid quenching ribbon: put the raw material into the crucible of the induction melting rapid quenching ribbon furnace, and prepare the high cobalt rare earth permanent magnet material ribbon by induction melting rapid quenching, the average thickness of the rapid quenching ribbon is 100-400μm, and the magnet form is the rapid quenching ribbon.

[0020] Further, the high cobalt rare earth permanent magnet material ribbon is subjected to hydrogen crushing and powdering, and the hydrogen crushing and powdering process is as follows: the vacuum degree in the hydrogen crushing furnace is 0Pa-1×10 -5 Pa, the hydrogen pressure is 0.10MPa-3.00MPa, the dehydrogenation holding temperature is 400-800℃, the dehydrogenation holding time is 2-10h, and the high cobalt rare earth permanent magnet material hydrogen crushing powder with an average particle size of 90-100μm is obtained.

[0021] Further, the high cobalt rare earth permanent magnet material hydrogen crushing powder is subjected to airflow milling and powdering, and the airflow milling and powdering process is as follows: the rotational speed of the airflow mill grading wheel is 2000-5000r / min, and the grinding pressure is 0.20-1.50Mpa, to obtain the high cobalt rare earth permanent magnet material airflow milled fine powder with a particle size of 2-5μm.

[0022] Further, before the airflow milling and powdering process, the high cobalt rare earth permanent magnet material hydrogen crushing powder is added with a permanent magnet material antioxidant, and the mass ratio of the antioxidant to the hydrogen crushing powder is 0.1:1000-2:1000.

[0023] Further, in step 2, the preparation of the M-containing alloy includes the following steps:

[0024] Raw material preparation: according to the mass percentage chemical formula of the M-containing alloy RE x M y TM 100-x-y Configure raw materials, wherein 30≤x≤90, 10≤y≤40; RE is one or a combination of several of Pr, Nd, La, Ce, Y, Gd, Tb, Dy, Ho elements; M is one or a combination of Cu and Al; TM is one or a combination of several of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo, Mn;

[0025] The raw materials are prepared by smelting to obtain the M-containing alloy, and the M-containing alloy is processed to obtain one of the following: a powder obtained by crushing an arc smelting ingot, a rapid solidification tape, an M-containing alloy hydrogen broken powder, or an M-containing alloy airflow powder.

[0026] Further, in step 3, the mixing mass ratio of the added magnet and the M-containing alloy is 1:334-1:20.

[0027] The application also provides a preparation method of a high-cobalt rare earth permanent magnet material, which is used for preparing the high-cobalt rare earth permanent magnet material, and adopts a grain boundary diffusion method to add M elements to the high-cobalt rare earth permanent magnet material, and includes the following steps:

[0028] Step 1: preparing a high-cobalt rare earth permanent magnet material magnet substrate according to a process of batching-preparing a rapid solidification tape-hydrogen breaking-airflow grinding-orientation forming-cold isostatic pressing-sintering-tempering;

[0029] Step 2: preparing an M-containing alloy diffusion source;

[0030] Step 3: attaching the M-containing alloy diffusion source to the surface of the high-cobalt rare earth permanent magnet material magnet substrate, and preparing a magnet through high-temperature diffusion and tempering.

[0031] Compared with the prior art, the application can at least achieve one of the following beneficial effects:

[0032] 1. The application improves the content of Cu / Al elements in the magnet through a grain boundary regulation method, reduces the problem of magnetic reduction caused by the replacement of Fe in the RE2Fe 14 B main phase, and improves the wettability between the interfaces of the main phase-grain boundary phase, improves the flowability of the rare earth-rich grain boundary phase, reduces the volume ratio and size of the Co-rich phase in the grain boundary phase, and reduces RECo2, RECo3, RECo5, RE2Co 17The existence of the phase improves the demagnetization coupling ability of the grain boundary phase, reduces the direct contact between the main phases, thereby improving the coercivity of the magnet, and solves the problem of the existence of the large Co-rich harmful phase in the grain boundary phase of the high cobalt rare earth permanent magnet material.

[0033] 2、The present application optimizes the microstructure of the permanent magnet material, on the one hand, the size of the Co-rich phase in the triangular grain boundary is reduced, the hindering effect of the Co-rich rare earth flow is greatly reduced, more thin layer grain boundary phases are formed between the main phase grains, and the demagnetization coupling ability of the grain boundary is improved; on the other hand, part of the Co-rich ferromagnetic phase is converted into a non-magnetic phase, and the magnetic coupling between the Co-rich phase and the main phase grains is reduced, further improving the magnetic decoupling ability of the grain boundary; the combined action of the two aspects greatly improves the coercivity of the high Co magnet, thereby further improving the demagnetization resistance of the magnet and improving the maximum use temperature of the magnet.

[0034] 3、The high Co magnet provided by the present application solves the problem that Co deteriorates the microstructure of the magnet while obtaining high Curie temperature and high temperature stability. The present method can improve the coercivity of the magnet without adding a large amount of expensive and rare heavy rare element Dy or Tb, greatly reducing the production cost of the high Co content rare earth permanent magnet material, and having important significance for the application and promotion of the high Co content rare earth permanent magnet material.

[0035] The above technical solutions in the present application can also be combined with each other to realize more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification or be understood by implementing the present application. The purposes and other advantages of the present application can be realized and obtained from the contents specifically indicated in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0036] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and serve to explain the principles of the present application.

[0037] Figure 1a SEM of the magnet in Example 1 of the present application;

[0038] Figure 1b SEM of the magnet in Example 2 of the present application;

[0039] Figure 1c SEM of the magnet in the comparative example of the present application;

[0040] Figure 2a Structure diagram of the magnet in the comparative example of the present application;

[0041] Figure 2b Structure diagram of the magnet in Examples 1-3 of the present application. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this application. The drawings illustrate embodiments of the application and serve to explain the principles of the application, but are not intended to limit the scope thereof.

[0043] The present application provides a high cobalt rare earth permanent magnet material, the composition of the permanent magnet material is as follows in percentage by mass: RE a Co b M c TM e Fe 100-a-b-c-d B d , 28≤a≤35, 15≤b≤30, 0.5≤c≤1.2, 0.95≤d≤1.2, 0.2≤e≤3; RE is one or a combination of several of Pr, Nd, La, Ce, Y, Gd, Tb, Dy, Ho elements; M is one or a combination of Cu, Al; TM is one or a combination of several of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo, Mn;

[0044] The microstructure of the high cobalt rare earth permanent magnet material includes a main phase and a grain boundary phase, the main phase is a main phase of RE:(Fe,Co):B=2:14:1 structure, and the grain boundary phase is composed of RE-rich phase and a small amount of Co-rich phase; wherein the Co-rich phase contains but is not limited to one or more of RE2(Fe,Co) phase, RE(Fe,Co) phase, RE(Fe,Co)2 phase, RE(Fe,Co)3 phase, RE(Fe,Co)4B phase, RE(Fe,Co)5 phase, RE2(Fe,Co) 17 phase and Co-containing amorphous phase;

[0045] In the grain boundary phase, the Co-rich phase accounts for ≤5% of the total volume fraction of the grain boundary phase; the mass percentage of Co:M in the composition of the Co-rich phase is 5:1~100:1;

[0046] In the RE-rich phase, the mass percentage of M is ≥2c.

[0047] The Curie temperature of the high cobalt rare earth permanent magnet material is 360~720℃; the density of the high cobalt rare earth permanent magnet material is 7.6~8.0g / cm 3 . The temperature coefficient of residual magnetism of the high cobalt rare earth permanent magnet material is 20~100℃, -0.070% / ℃~+0.015% / ℃; the temperature coefficient of intrinsic coercive force is 20~100℃, -0.58% / ℃~-0.25% / ℃.

[0048] The present application also provides a preparation method of a high cobalt rare earth permanent magnet material, which adds M element to the high cobalt rare earth permanent magnet material by a grain boundary doping method, comprising the following steps:

[0049] Step 1: preparing the added magnet, the magnet form being one of the following: a rapid solidification ribbon, a hydrogen decrepitated powder of the magnet, and a jet mill powder of the magnet;

[0050] Step 2: preparing the M-containing alloy, the M-containing alloy form being one of the following: a powder after breaking an arc-melted ingot, a rapid solidification ribbon, a hydrogen decrepitated powder of the M-containing alloy, or a jet mill powder of the M-containing alloy;

[0051] Step 3: mixing the added magnet and the M-containing alloy according to a certain ratio, hydrogen decrepitation or jet milling, and then orientation forming under a magnetic field with a strength of 1.6 T or above to obtain a magnet rough blank, and cold isostatic pressing the rough blank to prepare a magnet green body with a density of 3-5 g / cm 3 ;

[0052] Step 4: sintering the magnet green body, the sintering temperature being 1000-1200℃, and the holding time being 2-8 h.

[0053] Step 5: first tempering at 800-950℃, the holding time being 2-8 h; second tempering at 400-650℃, the second tempering holding time being 3-10 h, to obtain a magnet finished product.

[0054] Specifically, in Step 1, the added magnet is prepared, the magnet form being one of the following: a rapid solidification ribbon, a hydrogen decrepitated powder of the magnet, and a jet mill powder of the magnet, including the following steps:

[0055] Raw material preparation: configuring raw materials according to the permanent magnet material mass percentage chemical formula RE a Co b M c TM e Fe 100-a-b-c-d B d , wherein 28≤a≤35, 15≤b≤30, 0.5≤c≤1.2, 0.95≤d≤1.2, and 0.2≤e≤3; RE is one or a combination of several of Pr, Nd, La, Ce, Y, Gd, Tb, Dy, and Ho elements; M is one or a combination of Cu and Al; and TM is one or a combination of several of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo, and Mn.

[0056] Preparing the rapid solidification ribbon: placing the raw materials into an induction melting rapid solidification ribbon furnace crucible to prepare a Co-containing rare earth permanent magnet ribbon by induction melting rapid solidification, the average thickness of the rapid solidification ribbon being 100-400 μm, and the magnet form being a rapid solidification ribbon.

[0057] The magnet rapid solidification ribbon can be hydrogen broken to obtain hydrogen broken powder. The hydrogen breaking process is as follows: the magnet rapid solidification ribbon is hydrogen broken to obtain hydrogen broken powder with an average particle size of 90-100 μm; the vacuum degree in the hydrogen breaking furnace is 0 Pa-1×10 -5 Pa, the hydrogen pressure during hydrogen absorption in the hydrogen breaking process is 0.10-3.00 MPa, the dehydrogenation holding temperature is 400-800 ℃, and the dehydrogenation holding time is 2-10 h.

[0058] The magnet hydrogen broken powder can be further jet milled to obtain magnet jet milled powder. The jet milling process is as follows: first, a special antioxidant for permanent magnet materials is added to the hydrogen broken powder (the antioxidant can also not be added), the mass ratio of the antioxidant to the hydrogen broken powder is 0.1:1000-2:1000, and the mixture is uniformly mixed for 0.1-6 h; then, the mixed hydrogen broken powder is jet milled, the rotating speed of the classification wheel is 2000-5000 r / min, the grinding pressure is 0.20-1.50 MPa, and magnet jet milled fine powder with a particle size of 2-5 μm is obtained; after the jet milling, a special lubricant for permanent magnet materials is added to the magnet jet milled fine powder (the lubricant can also not be added), the ratio of the lubricant to the magnet jet milled fine powder is 0.1:1000-2:1000, and the mixture is uniformly mixed for 0.1-6 h.

[0059] Specifically, in step 2, the M-containing alloy is prepared, and the M-containing alloy is in the form of one of the following: a powder broken from a cast ingot prepared by melting, a rapid solidification ribbon, hydrogen broken powder of the M-containing alloy, or jet milled powder of the M-containing alloy. The preparation process includes the following steps:

[0060] Raw material preparation: according to the chemical formula RE x M y TM 100-x-y The raw materials are configured, wherein 30≤x≤90 and 10≤y≤40; RE is one or a combination of several of Pr, Nd, La, Ce, Y, Gd, Tb, Dy, and Ho; M is one or a combination of Cu and Al; and TM is one or a combination of several of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo, and Mn;

[0061] The powder broken from the cast ingot prepared by melting is prepared. Preferably, the powder broken from the cast ingot prepared by melting is prepared by arc melting. Pure metal materials are placed in a copper pan crucible in an arc melting furnace according to the designed percentage of the ingredients, and the valve is closed and tightened. First, the arc melting furnace mechanical pump is opened to pre-evacuate, and then the diffusion pump is started to preheat for 20-80 min; the furnace cavity is evacuated to 1×10 -1When the pressure is below 0.1 MPa, inert gas is introduced for washing; and before the smelting starts, a proper amount of inert gas is introduced, and the smelting is repeated for several times to ensure the uniformity of the alloy composition, so as to obtain the M-containing alloy ingot; the M-containing alloy ingot is crushed into a powder with a particle size of 1-200 μm in a protective atmosphere, and the M-containing alloy is in the form of the powder after crushing of the arc smelting ingot.

[0062] The M-containing alloy is prepared by smelting, the alloy ingot is put into a crucible, and after being melted, the alloy is sprayed under the action of pressure to a rapid solidification roller rotating at a certain linear speed, so as to obtain the M-containing alloy rapid solidification ribbon, the average thickness of the rapid solidification ribbon is 10-400 μm, and the M-containing alloy is in the form of the rapid solidification ribbon.

[0063] The M-containing alloy rapid solidification ribbon can be hydrogen broken to obtain the M-containing alloy hydrogen broken powder, and the hydrogen breaking process is as follows: the M-containing alloy rapid solidification ribbon is hydrogen broken to obtain the hydrogen broken powder with an average particle size of 1-150 μm; the vacuum degree in the hydrogen breaking furnace is 0 Pa-1×10 -5 Pa, the hydrogen pressure during hydrogen absorption in the hydrogen breaking process is 0.10 MPa-3.00 MPa, the dehydrogenation holding temperature is 400-800 ℃, and the dehydrogenation holding time is 2-10 h. The M-containing alloy is in the form of the hydrogen broken powder.

[0064] The M-containing alloy hydrogen broken powder can be further jet milled to obtain the M-containing alloy jet milled powder, and the jet milling process is as follows: the M-containing alloy hydrogen broken powder is jet milled to obtain the jet milled fine powder with a particle size of 0.1-10 μm, the rotating speed of the jet milling classifier wheel is 2000-5000 r / min, and the milling pressure is 0.20-1.50 MPa. The M-containing alloy is in the form of the jet milled fine powder.

[0065] It should be noted that in step 3, the magnet is added to one of the forms of the rapidly quenched ribbon, hydrogen broken powder, and gas flow milled powder, and the powder broken from the molten ingot of the M-containing alloy, the rapidly quenched ribbon, the hydrogen broken powder, and the gas flow milled powder is mixed; for example, the magnet-added rapidly quenched ribbon is mixed with the powder broken from the molten ingot of the M-containing alloy; the magnet-added rapidly quenched ribbon is mixed with the rapidly quenched ribbon of the M-containing alloy; the magnet-added rapidly quenched ribbon is mixed with the hydrogen broken powder of the M-containing alloy; the magnet-added rapidly quenched ribbon is mixed with the gas flow milled powder of the M-containing alloy; the magnet-added hydrogen broken powder is mixed with the powder broken from the molten ingot of the M-containing alloy; the magnet-added hydrogen broken powder is mixed with the rapidly quenched ribbon of the M-containing alloy; the magnet-added hydrogen broken powder is mixed with the hydrogen broken powder of the M-containing alloy; the magnet-added hydrogen broken powder is mixed with the gas flow milled powder of the M-containing alloy; the magnet-added gas flow milled powder is mixed with the powder broken from the molten ingot of the M-containing alloy; the magnet-added gas flow milled powder is mixed with the rapidly quenched ribbon of the M-containing alloy; the magnet-added gas flow milled powder is mixed with the hydrogen broken powder of the M-containing alloy; the magnet-added gas flow milled powder is mixed with the gas flow milled powder of the M-containing alloy; when the M-containing alloy and the magnet are mixed in various forms, the mass ratio of the mixture is 1:334 to 1:20.

[0066] When the M-containing alloy and the magnet are mixed in various forms, if one of the M-containing alloy or the magnet is in the form of a rapidly quenched ribbon, the mixture is subsequently subjected to hydrogen breaking + gas flow milling: the vacuum degree in the hydrogen breaking furnace is 0 Pa to 1 x 10 -5 Pa. The hydrogen pressure during hydrogen absorption during hydrogen breaking is between 0.10 MPa and 3.00 MPa, the dehydrogenation holding temperature is 400-800°C, and the dehydrogenation holding time is 2-10 h. The hydrogen broken powder is added with a special antioxidant for permanent magnet materials (which can also not be added), the mass ratio of the antioxidant to the hydrogen broken powder is 0.1:1000 to 2:1000, and the powder is uniformly mixed for 0.1 h to 6 h; the gas flow milling classification wheel rotates at 2000-5000 r / min, the grinding pressure is 0.20-1.50 MPa, and the alloy fine powder with a particle size of 2-5 μm is obtained; after gas flow milling, a special lubricant for permanent magnet materials is added to the magnet gas flow milled fine powder (which can also not be added), the ratio of the lubricant to the magnet gas flow milled fine powder is 0.1:1000 to 2:1000, and the powder is uniformly mixed for 0.1 h to 6 h.

[0067] When the M-containing alloy and the magnet are mixed in various forms, if the magnet is in the form of hydrogen broken powder or gas flow milled powder, and the M-containing alloy is in the form of powder broken from a molten ingot, the mixture is subsequently subjected to hydrogen breaking + gas flow milling: the vacuum degree in the hydrogen breaking furnace is 0 Pa to 1 x 10 -5The hydrogen pressure during hydrogen decrepitation is between 0.10 MPa and 3.00 MPa, the dehydrogenation holding temperature is 400-800 DEG C, and the dehydrogenation holding time is 2-10 h. The hydrogen decrepitation powder is added with a special antioxidant for permanent magnet materials (the antioxidant can also not be added), the mass ratio of the antioxidant to the hydrogen decrepitation powder is 0.1:1000-2:1000, and the powder is uniformly mixed for 0.1-6 h; the airflow mill grading wheel rotates at 2000-5000 r / min, the grinding pressure is 0.20-1.50 MPa, and the alloy fine powder with a particle size of 2-5 um is obtained; after the airflow mill, the special lubricant for permanent magnet materials is added to the magnet airflow mill fine powder (the lubricant can also not be added), the ratio of the lubricant to the magnet airflow mill fine powder is 0.1:1000-2:1000, and the powder is uniformly mixed for 0.1-6 h.

[0068] When the M-containing alloy and the added magnet are mixed in various forms, if the form of the added magnet is hydrogen decrepitation powder and the form of the M-containing alloy is hydrogen decrepitation powder or airflow mill powder, or the form of the added magnet is airflow mill powder and the form of the M-containing alloy is hydrogen decrepitation powder, then the mixed powder is subsequently subjected to airflow milling, the airflow mill grading wheel rotates at 2000-5000 r / min, the grinding pressure is 0.20-1.50 MPa, and the alloy fine powder with a particle size of 2-5 um is obtained; after the airflow mill, the special lubricant for permanent magnet materials is added to the magnet airflow mill fine powder (the lubricant can also not be added), the ratio of the lubricant to the magnet airflow mill fine powder is 0.1:1000-2:1000, and the powder is uniformly mixed for 0.1-6 h.

[0069] When the M-containing alloy and the added magnet are mixed in various forms, if both are airflow mill powder, they can be directly mixed according to the ratio without hydrogen decrepitation and / or airflow milling, and then oriented forming is performed under a magnetic field with a magnetic field strength of 1.6 T or more to obtain a magnet blank, the magnet blank is subjected to cold isostatic pressing to prepare a magnet green body with a density of 3-5 g / cm 3 The magnet green body is subjected to sintering treatment, the sintering temperature is 1000-1200 DEG C, and the holding time is 2-8 h. First-stage tempering is performed at 800-950 DEG C, and the holding time is 2-8 h; the second-stage tempering temperature is 400-650 DEG C, the second-stage tempering holding time is 3-10 h, and the magnet finished product is obtained.

[0070] The M element can also be added to the high-cobalt rare earth permanent magnet material by a grain boundary diffusion method, including the following steps:

[0071] Step 1: a high-cobalt rare earth permanent magnet material magnet base body is prepared according to the process of batching-preparing a rapid solidification tape-hydrogen decrepitation-airflow milling-orientation forming-cold isostatic pressing-sintering-tempering;

[0072] Step 2: a diffusion source of an M-containing alloy is prepared;

[0073] Step 3: Attach the M alloy diffusion source to the surface of the high cobalt rare earth permanent magnet material magnet base, and prepare the magnet by high temperature diffusion and tempering.

[0074] Specifically, in step 1, the high cobalt rare earth permanent magnet material magnet base is prepared according to the process of batching-preparing rapid solidification ribbon-hydrogen crushing-airflow milling-orientation forming-sintering-tempering, including the following steps:

[0075] (1) Raw material preparation: according to the chemical formula RE a Co b M c TM e Fe 100-a-b-c-d B d , wherein 28≤a≤35, 15≤b≤30, 0.5≤c≤1.2, 0.95≤d≤1.2, 0.2≤e≤3; RE is one or a combination of several of Pr, Nd, La, Ce, Y, Gd, Tb, Dy, Ho elements; M is one or a combination of Cu and Al; TM is one or a combination of several of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo, Mn.

[0076] (2) Preparation of rapid solidification ribbon: Put the raw materials into the induction melting rapid solidification ribbon furnace crucible, and prepare high Co rare earth permanent magnet material ribbon by induction melting rapid solidification. The average thickness of the rapid solidification ribbon is about 250 μm.

[0077] (3) Hydrogen crushing: hydrogen crushing is performed on the rapid solidification ribbon to obtain hydrogen broken powder with an average particle size of about 100 μm; the vacuum degree in the hydrogen crushing furnace is 0 Pa-1×10 -6 Pa, the hydrogen pressure during hydrogen absorption is between 0.10 MPa and 3.00 MPa, the dehydrogenation holding temperature is 400-800 ℃, and the dehydrogenation holding time is 2-10 h.

[0078] (4) Airflow milling: First, add a special antioxidant for permanent magnet materials to the hydrogen broken powder (it can also not be added), and the mass ratio of antioxidant to hydrogen broken powder is 0.1:1000-2:1000, and mix the powder uniformly for 0.1 h-6 h. Airflow milling is performed on the mixed hydrogen broken powder, the airflow milling classification wheel rotates at 2000-5000 r / min, the grinding pressure is 0.20-1.50 Mpa, and the alloy fine powder with a particle size of 2-5 μm is obtained. After airflow milling, add a special lubricant for rare earth permanent magnet materials to the alloy fine powder (it can also not be added), and the mass ratio of lubricant to alloy fine powder is 0.1:1000-2:1000, and mix the powder uniformly for 0.1 h-6 h.

[0079] (5) Oriented forming + cold isostatic pressing: the airflow powder is oriented forming to obtain a permanent magnet material magnet blank under a magnetic field with a magnetic field strength of 1.6T or above, and cold isostatic pressing can be further selected according to needs to prepare a magnet green body with a density of 3-5g / cm 3 .

[0080] (6) Sintering: the magnet green body is sintered at a sintering temperature of 1000-1200℃ for 2-8h.

[0081] (7) Tempering: first-stage tempering is performed at 800-950℃ for 2-8h; the second-stage tempering temperature is 400-650℃, and the second-stage tempering time is 3-10h to obtain the substrate of the high-cobalt rare earth permanent magnet material magnet.

[0082] Specifically, in step 2, the raw materials are configured according to the chemical formula RE x M y TM 100-x-y , wherein 30≤x≤90 and 10≤y≤40; RE is one or a combination of several of Pr, Nd, La, Ce, Y, Gd, Tb, Dy, and Ho; M is one or a combination of Cu and Al; and TM is one or a combination of several of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo, and Mn.

[0083] The M-containing alloy diffusion source can be prepared into a target material or a sheet or a powder. Specifically, the M-containing alloy diffusion source is prepared into a thin round sheet through the following process: the pure metal material after compounding is placed in a copper pan crucible in an arc melting furnace, and the valve is closed and tightened. Before the experiment starts, first, the arc melting furnace mechanical pump is opened to pre-evacuate, and then the diffusion pump is started to preheat for 40-60min. To ensure that the alloy does not react with oxygen in the furnace cavity during arc melting, when the vacuum in the furnace cavity is extracted to 5×10 -3 MPa or below, argon gas is introduced to perform three times of gas absorption, and an appropriate amount of argon gas is introduced before starting melting, and the alloy is repeatedly melted for 4 times to ensure uniformity of the alloy composition, and a diffusion alloy ingot is prepared. The diffusion source alloy ingot is wire cut to a round sheet with a diameter of Φ10mm and a thickness of 0.3mm as a diffusion source layer.

[0084] Specifically, in step 3, the M-containing alloy diffusion source is attached to the surface of the prepared high-cobalt rare earth permanent magnet substrate by using a method including but not limited to a coating method, a physical vapor deposition method, a screen printing method, etc., and a final magnet with further improved Cu content is prepared by high-temperature diffusion and tempering, wherein the diffusion temperature is 800-950℃, the diffusion time is 2-16h; the tempering temperature is 400-650℃, and the tempering time is 3-10h to obtain the magnet.

[0085] The application utilizes a method of regulating through grain boundaries, improves the content of Cu / Al elements in the magnet by means of grain boundary doping, grain boundary diffusion and other technical means, reduces the magnetic reduction problem caused by the replacement of Fe in the B main phase, improves the wettability between the interface of the main phase-grain boundary phase, improves the fluidity of the rare earth-rich grain boundary phase, reduces the volume ratio and size of the Co-rich phase in the grain boundary phase, reduces the existence of RECo2, RECo3, RECo5, RE2Co 14 B main phase, improves the wettability between the interface of the main phase-grain boundary phase, improves the fluidity of the rare earth-rich grain boundary phase, reduces the volume ratio and size of the Co-rich phase in the grain boundary phase, reduces the existence of RECo2, RECo3, RECo5, RE2Co 17 phase, improves the demagnetization coupling ability of the grain boundary phase, reduces the direct contact between the main phases, thereby improving the coercivity of the magnet, solving the problem of the existence of large Co-rich harmful phase in the grain boundary phase in the high-Co rare earth permanent magnet material. On the one hand, the size of the Co-rich phase in the triangular grain boundary is reduced, the hindering effect of the rare earth-rich flow is greatly reduced, more thin-layer grain boundary phases are formed between the main phase grains, and the demagnetization coupling ability of the grain boundary is improved; on the other hand, part of the ferromagnetic phase of the Co-rich phase is converted into a non-magnetic phase, and the magnetic coupling between the Co-rich phase and the main phase grains is reduced, further improving the magnetic decoupling ability of the grain boundary. The combined action of the two aspects greatly improves the coercivity of the high-Co magnet, thereby further improving the demagnetization resistance of the magnet and improving the maximum use temperature of the magnet.

[0086] Embodiment 1

[0087] A preparation method of a high-Co rare earth permanent magnet material (adopting the method of adding PrCu alloy electric arc melting ingot breaking and powder, the proportion of PrCu alloy to the added magnet is 1:149), comprising the following steps:

[0088] (1) according to the designed composition of the permanent magnet material, the mass percentage chemical formula is: (Pr, Nd) 23.7 Dy8Co 15 Cu 0.6 Fe bal B 0.98 (Al, Ga, Zr) 1.05 ; the raw materials are put into the crucible of the induction melting rapid solidification spinning furnace to prepare the rapid solidification spinning, the thickness of the obtained added magnet rapid solidification spinning is 250 μm;

[0089] (2) preparing Pr 80 Cu 20 alloy: by the method of electric arc melting, preparing Pr 80 Cu 20 alloy, and coarsely crushing the Pr 80 Cu 20 alloy in an inert gas protection atmosphere to obtain Pr 80 Cu 20 containing alloy powder with an average particle size of about 150 μm;

[0090] (3) The crushed Pr 80 Cu 20 The alloy and the added magnet were rapidly solidified and spun together at a mass ratio of 1:149.

[0091] (4) Hydrogen crushing + air jet milling + orientation forming: The mixed alloy was subjected to hydrogen crushing and powdering. The hydrogen pressure during hydrogen crushing was 0.35 MPa, and hydrogen crushed powder with a particle size of about 100 μm was obtained after crushing. A special antioxidant for permanent magnet materials was added to the hydrogen crushed powder. The ratio of antioxidant to hydrogen crushed powder was 1.2:1000, and the powder was mixed evenly for 2 hours. The obtained hydrogen crushed powder was subjected to air jet milling. The grinding gas pressure during air jet milling was 0.5 MPa, and the classifying wheel speed was 3800 r / min, to obtain alloy fine powder with a particle size of 2-5 μm. A special lubricant for permanent magnet materials was added to the alloy fine powder. The ratio of lubricant to alloy fine powder was 1.2:1000, and the powder was mixed evenly for 2 hours. Subsequently, orientation forming was performed under a 2T magnetic field, and cold isostatic pressing was performed under a pressure of 220 MPa to prepare magnet green blanks.

[0092] (5) Sintering + Tempering: Vacuum sintering treatment was performed on the green magnet blank at a temperature of 1050℃ and a holding time of 5h; tempering heat treatment was performed on the magnet at a first tempering temperature of 880℃ and a holding time of 2h; and a second tempering temperature of 520℃ and a holding time of 3h to obtain the magnet sample.

[0093] (6) Magnetic property measurement and microstructure observation: The obtained magnet samples were cut into cylinders of Φ10mm×10mm by wire cutting; the remanence B of the magnets was measured using the NIM-6500C ultra-high temperature permanent magnet material precision measurement system produced by the National Institute of Metrology of China. r Innate coercivity H cj Maximum energy product (BH)max, squareness H k / H cj Remanence temperature coefficient α Br Intrinsic coercivity temperature coefficient α Hcj The magnetic properties of the samples are shown in Table 1.

[0094] The obtained magnet sample was cut into cylinders with a diameter of 10 mm × 7 mm by wire cutting; the irreversible flux loss Φ of the magnet was measured using an HT-707 fluxmeter with a measuring coil; the irreversible flux loss of the sample is shown in Table 1.

[0095] The surface and end faces of the Φ10mm×10mm cylindrical tube were smoothed with sandpaper and then rotary polished; a JSM-7200F field emission scanning electron microscope equipped with an Oxford X-Max was used. N The energy dispersive spectroscopy (EDS) system was used for preliminary observation of the sample's microstructure; scanning electron microscope (SEM) images of the sample are shown below. Figure 1a As shown.

[0096] Example 2

[0097] A preparation method of a high-cobalt rare earth permanent magnet material (adopting a method of adding PrAlCu alloy to a rapid quenching and drawing strip, and the ratio of the PrAlCu alloy strip to the added magnet is 1:74), comprising the following steps:

[0098] (1) According to the designed composition of the permanent magnet material, the mass percentage chemical formula is: (Pr, Nd) 23.7 Dy8Co 15 Cu 0.6 Fe bal B 0.98 (Al, Ga, Zr) 1.05 ; Put the raw materials into the crucible of the induction melting rapid quenching and drawing furnace to prepare a rapid quenching and drawing strip, and the thickness of the obtained added magnet rapid quenching and drawing strip is 250 μm;

[0099] (2) Prepare a Pr 80 Al 10 Cu 10 alloy strip: by an arc melting method, prepare a Pr 80 Al 10 Cu 10 alloy, put the alloy ingot into the crucible, after melting, spray it to the rapid quenching roller rotating at a certain linear speed under the action of pressure, to prepare a Pr 80 Al 10 Cu 10 alloy rapid quenching and drawing strip, with a thickness of 150 μm;

[0100] (3) Uniformly mix the Pr 80 Al 10 Cu 10 alloy rapid quenching and drawing strip with the added magnet rapid quenching and drawing strip at a mass ratio of 1:74;

[0101] (4) Hydrogen breaking + jet milling + orientation forming: hydrogen break the mixed alloy strip to obtain a powder, the hydrogen pressure during hydrogen breaking is 0.35 MPa, and a hydrogen broken powder with a particle size of about 100 μm is obtained after breaking; add a special antioxidant for permanent magnet materials to the hydrogen broken powder, the mass ratio of the antioxidant to the hydrogen broken powder is 1.2:1000, and uniformly mix the powder for 2 h; jet mill the obtained hydrogen broken powder, the grinding gas pressure during jet milling is 0.5 MPa, and the grading wheel rotating speed is 3800 r / min, to obtain an alloy fine powder with a particle size of 2-5 μm; add a special lubricant for permanent magnet materials to the alloy fine powder, the mass ratio of the lubricant to the alloy fine powder is 1.2:1000, and uniformly mix the powder for 2 h; then, orientation forming is carried out under a magnetic field of 2T, and a green magnet is prepared by cold isostatic pressing under a pressure of 220 MPa.

[0102] (5) Sintering + tempering: the green magnet body is subjected to vacuum sintering treatment, the sintering temperature is 1050℃, and the holding time is 5h; the magnet body is subjected to tempering heat treatment, the first-stage tempering temperature is 880℃, the holding time is 2h; the second-stage tempering temperature is 500℃, and the holding time is 3h, to obtain the magnet body sample.

[0103] (6) Magnetic property measurement and microstructure observation: the obtained magnet body sample is cut into a Φ10mm×10mm cylinder by wire cutting; the remanence B r , intrinsic coercivity H cj , maximum magnetic energy product (BH) max, squareness H k / H cj , remanence temperature coefficient α Br , intrinsic coercivity temperature coefficient α Hcj of the magnet body are measured by using the NIM-6500C ultra-high temperature permanent magnet material precision measurement system produced by China Institute of Metrology; the sample magnetic properties are shown in Table 1.

[0104] The obtained magnet body sample is cut into a Φ10mm×7mm cylinder by wire cutting; the irreversible magnetic flux loss Φ of the magnet body is measured by using the HT-707 fluxmeter with a measuring coil; the sample irreversible magnetic flux loss is shown in Table 1.

[0105] After polishing the surface and end face of the Φ10mm×10mm cylinder by using sandpaper and then rotary polishing, the microstructure of the sample is preliminarily observed by using the JSM-7200F field emission scanning electron microscope equipped with the Oxford X-Max N energy spectrum detection system; the scanning electron microscope photos of the sample are shown in Table 1. Figure 1b

[0106] Example 3

[0107] A preparation method of a high-cobalt rare earth permanent magnet material (adopting a grain boundary diffusion method), comprising the following steps:

[0108] (1) ingredients are prepared according to the designed composition of the permanent magnet material, the mass percentage chemical formula is: (Pr, Nd) 23.7 Dy8Co 15 Cu 0.6 Fe bal B 0.98 (Al, Ga, Zr) 1.05 ; the raw materials are put into the crucible of the induction melting rapid solidification spinning furnace to prepare a rapid solidification spinning, the thickness of the obtained rapid solidification spinning is 250μm;

[0109] ​(2) Hydrogen breaking + Jet Milling + Oriented forming: The rapid solidification ribbon in step 1 is broken by hydrogen to obtain powder, the hydrogen pressure is 0.35 MPa, and the hydrogen broken powder with a particle size of about 100 μm is obtained. Add antioxidant to the hydrogen broken powder, the mass ratio of antioxidant to hydrogen broken powder is 1.2:1000, and mix uniformly for 2 hours. The hydrogen broken powder is jet milled, the grinding gas pressure is 0.5 MPa, the classification wheel speed is 3800 r / min, and the fine powder with a particle size of 2-5 μm is obtained. Add lubricant to the fine powder, the mass ratio of lubricant to fine powder is 1.2:1000, and mix uniformly for 2 hours. Then, the green magnet is prepared by oriented forming under a magnetic field of 2T and cold isostatic pressing under a pressure of 220 MPa.

[0110] (3) Sintering + Tempering: The green magnet is sintered in vacuum, the sintering temperature is 1050℃, and the holding time is 5 hours. The magnet is tempered, the first stage tempering temperature is 880℃, the holding time is 2 hours, the second stage tempering temperature is 480℃, and the holding time is 3 hours, and the magnet sample is obtained.

[0111] (4) Preparation of M-containing alloy diffusion source: The composition of the diffusion source alloy is Pr 80 Cu 20 , and the Pr 80 Cu 20 diffusion source alloy ingot is prepared by arc melting according to the designed mass ratio. The specific experimental operation process is as follows: the pure metal material after batching is placed in the copper pan crucible in the arc melting furnace, and the valve is closed and tightened. Before the experiment starts, first open the mechanical pump of the arc melting furnace to pre-vacuum, and then start the diffusion pump to preheat for 50 minutes. In order to ensure that the alloy does not react with oxygen in the furnace during arc melting, when the vacuum in the furnace is below 5x10 -3 MPa, argon gas is introduced for three times of gettering, and an appropriate amount of argon is introduced before starting the melting, and the alloy is repeatedly melted for 4 times to ensure uniform alloy composition, and the diffusion source alloy ingot is prepared. The diffusion source alloy ingot is wire cut into a round piece with a diameter of Φ10 mm and a thickness of 0.3 mm as the diffusion source layer.

[0112] (5) Paste magnet and diffusion source alloy piece: The magnet is cut into a cylinder with a diameter of Φ10 mm and a thickness of 3.5 mm (oriented direction), and is polished using 400cw metallographic sandpaper to remove surface oxides and dirt, and then is placed in anhydrous ethanol for ultrasonic cleaning and drying. The M-containing alloy piece is placed on the upper and lower surfaces of the magnet by pasting method.

[0113] (6) Diffusion and tempering heat treatment: The magnet with the diffusion source M-containing alloy piece is placed in a vacuum tube furnace, and the vacuum degree is 3x10 -3The grain boundary diffusion heat treatment was carried out under the condition of 900℃ and 6h, and then the tempering treatment was carried out under the condition of 500℃ and 2h.

[0114] (7) Magnetic property measurement: The remanence B r , intrinsic coercivity H cj , maximum magnetic energy product (BH)max, squareness degree H k / H cj , remanence temperature coefficient α Br , intrinsic coercivity temperature coefficient α Hcj of the magnet were measured by using PFM14.CN super high coercivity permanent magnet tester.

[0115] Comparative example

[0116] A preparation method of a high-cobalt rare earth permanent magnet material (without adding any M alloy, the method disclosed in CN111640549A) comprises the following steps:

[0117] (1) The ingredients of the designed permanent magnet material are prepared, and the mass percentage chemical formula is: (Pr, Nd) 23.7 Dy8Co 15 Cu 0.6 Fe bal B 0.98 (Al, Ga, Zr) 1.05 ; The raw materials are placed in the crucible of the induction melting rapid solidification spinning furnace to prepare the rapid solidification spinning belt, and the thickness of the obtained rapid solidification spinning belt is 250μm;

[0118] (2) Hydrogen crushing: The rapid solidification spinning belt is crushed by hydrogen to obtain hydrogen broken powder with an average particle size of about 100μm; A special antioxidant for permanent magnet materials is added to the hydrogen broken powder, and the ratio of the antioxidant to the hydrogen broken powder is 1.2:1000, and the powder is uniformly mixed for 2h;

[0119] (3) Airflow milling: The obtained hydrogen broken powder is milled by airflow to obtain fine powder with a particle size of 2-5μm; A special lubricant for rare earth permanent magnet materials is added to the fine powder, and the ratio of the lubricant to the fine powder is 1.2:1000, and the powder is uniformly mixed for 2h;

[0120] (4) Orientation forming: The fine powder is oriented and formed under a magnetic field with a strength of 2T to obtain a magnet blank, and the magnet green body is prepared by cold isostatic pressing under a pressure of 220MPa;

[0121] (5) Sintering: The magnet green body is sintered at a temperature of 1070℃ for 5h;

[0122] (6) Tempering: The magnets were subjected to two-stage tempering heat treatment, the first stage tempering temperature was 880℃, the holding time was 2h; the second stage tempering temperature was 560℃, the holding time was 3h, and the magnet samples were obtained.

[0123] (7) Magnetic property measurement and microstructure observation: The obtained magnet samples were cut into Φ10mm×10mm cylinders by wire cutting; the remanence B r , intrinsic coercivity H cj , maximum magnetic energy product (BH) max , squareness H k / H cj , remanence temperature coefficient α Br , intrinsic coercivity temperature coefficient α Hcj of the magnets were measured by NIM-6500C ultra-high temperature permanent magnet material precision measurement system produced by China Institute of Metrology; the sample magnetic properties are shown in Table 1.

[0124] The obtained magnet samples were cut into Φ10mm×7mm cylinders by wire cutting; the irreversible magnetic flux loss Φ of the magnets was measured by HT-707 fluxmeter with a measuring coil; the sample irreversible magnetic flux loss is shown in Table 1.

[0125] After polishing the surface and end face of the Φ10mm×10mm cylinder with sandpaper and then rotating and polishing, the microstructure of the sample was observed by JSM-7200F field emission scanning electron microscope equipped with Oxford X-Max N energy spectrum detection system; the scanning electron microscope photos of the sample are shown in Table 1. Figure 1c

[0126] Table 1 Magnetic properties of magnet samples of examples and comparative examples

[0127]

[0128] Table 2 Intrinsic energy spectrum point scanning data of magnet samples of examples and comparative examples

[0129]

[0130] Example 1 introduces Pr 80 Cu 20 alloy powder by grain boundary doping on the basis of the comparative example, example 2 introduces Pr 80 Al 10 Cu 10 alloy strip by grain boundary doping on the basis of the comparative example, and example 3 introduces Pr 80 Cu 20 alloy diffusion source by grain boundary diffusion on the basis of the comparative example.

[0131] ​As shown in the magnet performance in Table 1, the coercivity of the magnet after adding the grain boundary in Example 1 and Example 2 is obviously higher than that of the magnet in the comparative example; as shown in Table 1, the coercivity of the magnet after grain boundary diffusion in Example 3 is obviously higher than that of the magnet in the comparative example.

[0132] As shown in the magnet performance in Table 1, the high-Co magnet provided by the application can obtain high Curie temperature and high temperature stability, and can improve the coercivity of the magnet without adding a large amount of expensive and rare heavy rare elements Dy or Tb, thereby greatly reducing the production cost of the high-Co content rare earth permanent magnet material.

[0133] As shown in the magnet internal energy spectrum point scanning data in Table 2, the comparative example magnet has a Co-rich phase with Co content higher than that of the main phase and a Co-lean phase with Co content lower than that of the main phase; the magnet after adding the grain boundary in Example 1, Example 2 and Example 3 only has a RE-rich phase with Co content lower than that of the main phase; the difference between the RE-rich phase 1 and the RE-rich phase 2 is the amount of Co content, the Co content of the RE-rich phase 1 is relatively high, and the Co content of the RE-rich phase 2 is relatively low, but both are lower than that of the main phase.

[0134] Figure 1a and Figure 1b As shown in the scanning electron microscope images of the magnet in Example 1 and Example 2 of the application, it can be seen from the figure that the high-Co permanent magnet material prepared by the method of the application reduces the size of the Co-rich phase in the triangular grain boundary, greatly reduces the hindering effect of the Co-rich phase on the flow of rare earth, and the RE2Fe 14 B main phase grain boundary phase is formed between the grains, improving the demagnetization coupling ability of the grain boundary; at the same time, part of the Co-rich ferromagnetic phase is converted into a non-magnetic phase, further improving the magnetic decoupling ability of the grain boundary. The combined effect of the two aspects greatly improves the coercivity of the high-Co magnet, thereby further improving the demagnetization resistance of the magnet and improving the maximum use temperature of the magnet.

[0135] Figure 2a As shown in the magnet microstructure diagram before introducing the M-containing alloy, the comparative example magnet is prepared, Figure 2b As shown in the magnet microstructure diagram after introducing the M-containing alloy, the magnet of Example 1-3 of the application is prepared. It can be seen that before introducing the M-containing alloy, there is a large area of Co-rich phase deteriorating the coercivity in the magnet, and after introducing the M-containing alloy, the size of the Co-rich phase is greatly reduced, and its existence form is only a few scattered points.

[0136] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited thereto, and any changes or replacements within the technical range disclosed by the application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the application.

Claims

1. A high cobalt rare earth permanent magnet material, characterized in that, The high-cobalt rare earth permanent magnet material comprises the following components in percentage by mass: REaCobMcTMeFe100-a-b-c-dBd, wherein 28≤a≤35, 15≤b≤30, 0.5≤c≤1.2, 0.95≤d≤1.2, and 0.2≤e≤3; RE is one or a combination of several of Pr, Nd, La, Ce, Y, Gd, Tb, Dy, and Ho; M is one or a combination of Cu and Al; and TM is one or a combination of several of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo, and Mn. The microstructure of the high-cobalt rare earth permanent magnet material comprises a main phase and a grain boundary phase, the main phase is a main phase of RE:(Fe, Co):B=2:14:1 structure, and the grain boundary phase is composed of an RE-rich phase and a small amount of Co-rich phase. In the grain boundary phase, the Co-rich phase accounts for ≤5% of the total volume fraction of the grain boundary phase; and the mass percentage of Co:M in the composition of the Co-rich phase is 5:1-100:

1. wherein the Co-rich phase comprises, but is not limited to, one or more of RE2(Fe,Co) phase, RE(Fe,Co) phase, RE(Fe,Co)2 phase, RE(Fe,Co)3 phase, RE(Fe,Co)4B phase, RE(Fe,Co)5 phase, RE2(Fe,Co) 17 one or more of the RE2(Fe,Co) phase and the Co-containing amorphous phase; In the RE-rich phase, the mass percentage of M is ≥2c.

2. A method for producing a high cobalt rare earth permanent magnet material according to claim 1, characterized by, The method for adding M elements to the high-cobalt rare earth permanent magnet material by means of grain boundary doping comprises the following steps: Step 1: preparing an added magnet, the magnet being in one of the following forms: a rapid solidification ribbon, a hydrogen broken powder of the magnet, and a jet mill powder of the magnet; Step 2: preparing an M-containing alloy, the M-containing alloy being in one of the following forms: a powder broken from a cast ingot prepared by melting, a rapid solidification ribbon, a hydrogen broken powder of the M-containing alloy, or a jet mill powder of the M-containing alloy; Step 3: mix the added magnet and M-containing alloy in a certain proportion, perform hydrogen crushing or jet milling, and then perform orientation forming under a magnetic field with a magnetic field strength of 1.6 T or above to obtain a magnet rough blank, and perform cold isostatic pressing on the rough blank to prepare a magnet green body with a density of 3-5 g / cm 3 . Step 4: sintering the green body of the magnet, the sintering temperature being 1000-1200℃, and the holding time being 2-8h; Step 5: first-stage tempering at 800-950℃, the holding time being 2-8h; second-stage tempering at 400-650℃, the holding time being 3-10h, to obtain a finished magnet.

3. The method of producing a high-cobalt rare earth permanent magnet material according to claim 2, characterized by, In step 1, the added magnet is prepared by the following steps: Raw material preparation: according to the permanent magnet material quality percentage chemical formula RE a Co b M c TM e Fe 100-a-b-c-d B d Configure raw materials, wherein 28≤a≤35, 15≤b≤30, 0.5≤c≤1.2, 0.95≤d≤1.2, 0.2≤e≤3; RE is one or a combination of several of Pr, Nd, La, Ce, Y, Gd, Tb, Dy, Ho elements; M is one or a combination of Cu, Al; TM is one or a combination of several of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo, Mn; Preparation of a rapid solidification ribbon: the raw materials are placed in a crucible of an induction melting rapid solidification ribbon furnace, and a high-cobalt rare earth permanent magnet ribbon is prepared by induction melting rapid solidification, the average thickness of the rapid solidification ribbon being 100-400μm, and the magnet being in the form of a rapid solidification ribbon.

4. The method of producing a high-cobalt rare earth permanent magnet material according to claim 3, characterized by, The high-cobalt rare earth permanent magnet material strip is hydrogen decrepitated to prepare powder, and the hydrogen decrepitation powder preparation process is as follows: the vacuum degree in the hydrogen decrepitation furnace is 0 Pa to 1*10 -5 Pa, the hydrogen pressure is 0.10 MPa to 3.00 MPa, the dehydrogenation holding temperature is 400 to 800 DEG C, the dehydrogenation holding time is 2 to 10 h, and the high-cobalt rare earth permanent magnet material hydrogen decrepitation powder with an average particle size of 90 to 100 mu m is obtained.

5. The method of producing a high-cobalt rare earth permanent magnet material according to claim 4, characterized by, The hydrogen broken powder of the high-cobalt rare earth permanent magnet material is jet milled, and the jet milling process is as follows: the rotating speed of the classification wheel of the jet mill is 2000-5000r / min, and the grinding pressure is 0.20-1.50Mpa, to obtain a jet milled fine powder of the high-cobalt rare earth permanent magnet material with a particle size of 2-5μm.

6. The method of producing a high-cobalt rare earth permanent magnet material according to claim 5, characterized by, Before the jet milling process, the hydrogen broken powder of the high-cobalt rare earth permanent magnet material is added with a permanent magnet antioxidant, and the mass ratio of the antioxidant to the hydrogen broken powder is 0.1:1000-2:1000.

7. The method for preparing high-cobalt rare-earth permanent magnet material according to claim 2, characterized in that, In step 2, the M-containing alloy is prepared by the following steps: Raw material preparation: according to the mass percentage chemical formula of M alloy RE x M y TM 100-x-y Configure raw materials, wherein 30≤x≤90, 10≤y≤40; RE is one or a combination of several of Pr, Nd, La, Ce, Y, Gd, Tb, Dy, Ho elements; M is one or a combination of two of Cu, Al; TM is one or a combination of several of Cr, Nb, Zr, Ga, Ti, Zn, V, Mo, Mn; The raw materials are melted to prepare the M-containing alloy, and the M-containing alloy is processed to prepare one of the following: a powder broken from an arc melting cast ingot, a rapid solidification ribbon, a hydrogen broken powder of the M-containing alloy, or a jet mill powder of the M-containing alloy.

8. The method of producing a high-cobalt rare earth permanent magnet material according to claim 2, characterized by, In step 3, the mass ratio of the M-containing alloy to the added magnet is 1:334-1:

20.

9. A method for preparing a high cobalt rare earth permanent magnet material as claimed in claim 1, characterized in that, The method comprises the following steps: Step 1: a high-cobalt rare earth permanent magnet material is prepared according to the process of ingredient preparation-preparation of quick-solidification and belt casting-hydrogen crushing-airflow grinding-orientation forming-cold isostatic pressing-sintering-tempering; Step 2: an M-containing alloy diffusion source is prepared; Step 3: the M-containing alloy diffusion source is attached to the surface of the high-cobalt rare earth permanent magnet material, and the magnet is prepared through high-temperature diffusion and tempering.

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