阅读说明：本技术 一种添加钇的稀土永磁材料及其制备方法 (Yttrium-added rare earth permanent magnet material and preparation method thereof ) 是由 罗阳 林笑 吴桂勇 谢佳君 王子龙 闫文龙 王仲凯 于敦波 于 2019-02-19 设计创作，主要内容包括：一种添加钇的稀土永磁材料及其制备方法,该材料的化学式按原子百分比表示为(Y<Sub>x</Sub>RE<Sub>1-x</Sub>)<Sub>a</Sub>Fe<Sub>bal</Sub>M<Sub>b</Sub>N<Sub>c</Sub>,其中,0.05≤x≤0.4,7≤a≤13,0≤b≤3,5≤c≤20,余量为Fe,即bal＝100-a-b-c；RE为稀土元素Sm或者是稀土元素Sm与Zr、Nd和Pr中任意一种元素及以上的组合,M为Co和/或Nb,N为氮元素。所述制备方法利用稀土Y元素来取代钐铁氮材料的Sm元素,通过调控Sm元素与Y元素的比例,可以降低合金液的粘度,增强材料的非晶形成能力,有利于磁性能的提高,改善了矫顽力偏高、剩磁偏低的弊端,制得磁粉的磁性能更适用于电机制造对磁体的性能需求,填补了电机应用磁体性能缺口。(A rare-earth permanent-magnet material added with yttrium and its preparing process, the chemical formula of said material is (Y) in atomic percentage x RE 1‑x ) a Fe bal M b N c Wherein x is more than or equal to 0.05 and less than or equal to 0.4, a is more than or equal to 7 and less than or equal to 13, b is more than or equal to 0 and less than or equal to 3, c is more than or equal to 5 and less than or equal to 20, and the balance of Fe, namely bal is 100-a-b-c; RE is rare earth element Sm or the combination of rare earth element Sm and any one or more of Zr, Nd and Pr, M is Co and/or Nb, and N is nitrogen element. Said systemThe method utilizes rare earth element Y to replace Sm element of samarium-iron-nitrogen material, can reduce the viscosity of alloy liquid, enhance the amorphous forming capability of the material, is beneficial to improving the magnetic performance, overcomes the defects of high coercive force and low residual magnetism by regulating the proportion of the Sm element to the Y element, makes the magnetic performance of the prepared magnetic powder more suitable for the performance requirement of motor manufacture on the magnet, and fills the performance gap of the magnet applied to the motor.)

1. An yttrium-doped rare earth permanent magnetic material, characterized in that the chemical formula of the material is expressed as (Y) in atomic percent_xRE_1-x)_aFe_balM_bN_c；

Wherein x is more than or equal to 0.05 and less than or equal to 0.4, a is more than or equal to 7 and less than or equal to 13, b is more than or equal to 0 and less than or equal to 3, c is more than or equal to 5 and less than or equal to 20, and the balance is Fe, namely bal is 100-a-b-c;

RE is rare earth element Sm or the combination of rare earth element Sm and any one or more of Zr, Nd and Pr, M is Co and/or Nb, and N is nitrogen element.

2. Yttrium-added rare earth permanent magnetic material according to claim 1, characterized in that it contains TbCu₇Phase, Th₂Zn₁₇A phase and a soft magnetic phase α -Fe;

preferably, the material has TbCu₇The content of the phase is 70 vol% or more, preferably 90 vol% or more, and more preferably 95 vol% or more of the total volume content of the three phases;

and/or, the Th₂Zn₁₇The content of the phase is 0-30 vol% of the total volume content of the three phases, excluding 0, preferably 1-10 vol%;

and/or the content of the soft magnetic phase alpha-Fe phase in the rare earth permanent magnetic material is less than 1 vol% of the total volume content of three phases.

3. Yttrium-doped rare earth permanent magnetic material according to claim 1 or 2, characterized in that M is within 3 atomic%; preferably, M is within 1.5 atomic%.

4. A yttrium-added rare earth permanent magnetic material according to any of claims 1 to 3, wherein the atomic percentage of Sm element in RE is 95% or more.

5. Yttrium-added rare earth permanent magnetic material according to any of claims 2-4, characterized in that Y element enters TbCu₇Phase and/or Th₂Zn₁₇The proportion of phases is 100%.

6. Yttrium-added rare earth permanent magnetic material according to any of claims 1-5, characterized in that the rare earth permanent magnetic material has an average thickness of 20-40 μm, is composed of nanocrystalline and amorphous material with an average grain size of 20-100nm, preferably with a standard deviation of 2-5.

7. The yttrium-added rare earth permanent magnetic material according to any one of claims 1 to 6, wherein XRD peaks of the rare earth permanent magnetic material are shifted by 1% to 5% to the right as a whole.

8. The yttrium-added rare earth permanent magnet material according to any one of claims 1 to 7, wherein the material is obtained by introducing yttrium element into a samarium-iron-nitrogen magnet by adopting a nanocrystalline bonded permanent magnet material preparation process.

9. A method of making a yttrium-doped rare earth permanent magnetic material according to any of claims 1 to 8, comprising the steps of:

(1) smelting an alloy containing Sm, Y and Fe as main components and added with Co and/or Nb elements into an ingot;

(2) casting the cast ingot to a rotating roller after high-temperature melting, and rotating, rapidly quenching and cooling to obtain a rapidly quenched thin strip;

(3) carrying out crystallization treatment on the quick-quenched thin strip obtained in the step (2), then quenching, and then crushing into alloy powder;

(4) and (4) nitriding the alloy powder obtained in the step (3) in a tube furnace to obtain the yttrium-added rare earth permanent magnet material.

10. The method according to claim 9, wherein the melting in step (1) is vacuum induction melting;

preferably, the temperature for high-temperature melting in the step (2) is 200-400 ℃ above the melting point of the raw material for preparing the quick-quenched thin strip;

preferably, the holding time for high-temperature melting is 60-180 s;

preferably, the casting in the step (2) is carried out by a high-vacuum single-roller spinning method; further preferably, the speed of the rotary quenching roller is 20-40 m/s; further preferably, the cooling rate of the rotary quenching cooling is 1 x 10⁵-5*10⁶℃/s。

11. The method as claimed in claim 9 or 10, wherein the temperature of the crystallization treatment in the step (3) is 650-800 ℃, and the time of the crystallization treatment is 40-70 min;

preferably, the crystallization treatment is performed under a flowing Ar atmosphere;

preferably, the quenching adopts water-cooling quenching;

preferably, the quenching process is carried out under a flowing Ar atmosphere;

preferably, the quenching time is 50-70 min;

preferably, the average particle size of the alloy powder is 70 to 110 μm.

Technical Field

The invention relates to the field of rare earth permanent magnet materials, in particular to a rare earth permanent magnet material added with yttrium and a preparation method thereof.

Background

Since the discovery of the neodymium-iron-boron rare earth permanent magnet material, the excellent comprehensive magnetic performance of the neodymium-iron-boron rare earth permanent magnet material is widely applied to a plurality of fields such as electronic products, medical appliances, automobile industry, energy transportation and the like, and as the yield and consumption of the neodymium-iron-boron are increased year by year, the consumption speed of metal neodymium serving as a raw material and metal dysprosium serving as a common additive is increased more and more, so that the cost of the material is increased year by year; on the other hand, with the further popularization and application of the permanent magnet motor in the fields of electric vehicles and intelligent household appliances, the demand of the motor market for the permanent magnet motor is increasing, and therefore, the magnetic material for replacing NdFeB is sought to be proposed.

At present, the addition of the third elements of Ti, Nb, Al and Si is mainly used for replacing the Fe position so as to stabilize the TbCu₇Metastable phases of the type which reduce the wheel speed, but the addition of a certain amount of the above elements reduces the saturation magnetization of the alloy; and rare earth Y element with smaller atomic radius replaces rare earth position to play a role in stabilizing metastable phase, and the magnetic polarization strength is basically unchanged.

Disclosure of Invention

Objects of the invention

The invention aims to provide a yttrium-doped alloyRare earth permanent magnetic material and preparation method thereof, and Y doping can stabilize metastable phase TbCu₇The structure can obtain excellent magnetic performance under the condition of keeping saturation magnetization not to be reduced.

(II) technical scheme

In order to achieve the purpose, the invention adopts the following technical scheme.

In a first aspect of the invention, there is provided a rare earth permanent magnetic material with yttrium added, the material having a chemical formula expressed in atomic percent as (Y)_xRE_1-x)_aFe_balM_bN_c；

Wherein x is more than or equal to 0.05 and less than or equal to 0.4, a is more than or equal to 7 and less than or equal to 13, b is more than or equal to 0 and less than or equal to 3, c is more than or equal to 5 and less than or equal to 20, and the balance is Fe, namely bal is 100-a-b-c;

RE is rare earth element Sm or the combination of rare earth element Sm and any one or more of Zr, Nd and Pr, M is Co and/or Nb, and N is nitrogen element.

Further, the material contains TbCu₇Phase, Th₂Zn₁₇A phase and a soft magnetic phase α -Fe;

preferably, the material has TbCu₇The content of the phase is 70 vol% or more, preferably 90 vol% or more, and more preferably 95 vol% or more of the total volume content of the three phases;

and/or, the Th₂Zn₁₇The content of the phase is 0-30 vol% of the total volume content of the three phases, excluding 0, preferably 1-10 vol%;

and/or the content of the soft magnetic phase alpha-Fe phase in the rare earth permanent magnetic material is less than 1 vol% of the total volume content of three phases.

Further, the atomic percentage of M is within 3%; preferably, M is within 1.5 atomic%.

Furthermore, the atomic percent of Sm in RE is more than 95%.

Further, the Y element enters TbCu₇Phase and/or Th₂Zn₁₇The proportion of phases is 100%.

Furthermore, the average thickness of the rare earth permanent magnet material is 20-40 μm, the rare earth permanent magnet material is composed of nanocrystalline and amorphous materials with the average grain size of 20-100nm, and the preferred standard deviation of the grain size is 2-5.

Furthermore, the XRD peak of the rare earth permanent magnet material is shifted to the right by 1-5 percent.

Furthermore, the material is obtained by introducing yttrium element into a samarium-iron-nitrogen magnet by adopting a nanocrystalline bonded permanent magnet material preparation process.

In another aspect, the present invention provides a method for preparing a rare earth permanent magnetic material added with yttrium, including the following steps:

(1) smelting an alloy containing Sm, Y and Fe as main components and added with Co and/or Nb elements into an ingot;

(2) casting the cast ingot to a rotating roller after high-temperature melting, and rotating, rapidly quenching and cooling to obtain a rapidly quenched thin strip;

(3) carrying out crystallization treatment on the quick-quenched thin strip obtained in the step (2), then quenching, and then crushing into alloy powder;

(4) and (4) nitriding the alloy powder obtained in the step (3) in a tube furnace to obtain the yttrium-added rare earth permanent magnet material.

Further, the smelting in the step (1) is vacuum induction smelting;

preferably, the temperature for high-temperature melting in the step (2) is 200-400 ℃ above the melting point of the raw material for preparing the quick-quenched thin strip;

preferably, the holding time for high-temperature melting is 60-180 s;

preferably, the casting in the step (2) is carried out by a high-vacuum single-roller spinning method; further preferably, the speed of the rotary quenching roller is 20-40 m/s; further preferably, the cooling rate of the rotary quenching cooling is 1 x 10⁵-5*10⁶℃/s。

Further, the temperature of the crystallization treatment in the step (3) is 650-;

preferably, the crystallization treatment is performed under a flowing Ar atmosphere;

preferably, the quenching adopts water-cooling quenching;

preferably, the quenching process is carried out under a flowing Ar atmosphere;

preferably, the quenching time is 50-70 min;

preferably, the average particle size of the alloy powder is 70 to 110 μm.

(III) advantageous effects

The technical scheme of the invention has the following beneficial technical effects:

1. according to the yttrium-added rare earth permanent magnetic material and the preparation method thereof, the average grain size of the prepared magnetic powder is 20-100nm, the standard deviation is 2-5, the grain size distribution is more concentrated relative to binary SmFe, the influence of nonuniform grain size distribution on the deterioration of magnetic performance is effectively avoided, and the improvement of the magnetic performance is facilitated.

2. Rare earth Y element is used for replacing Sm element of samarium iron nitrogen material, and the ratio of Sm element to Y element is regulated, so that the viscosity of alloy liquid can be reduced, the amorphous forming capability of the material can be enhanced, and the production cost can be reduced.

3. According to the invention, by utilizing the characteristic that Y element does not contain 4f electrons and has small contribution to an anisotropic field, the magnetic performance of the SmFeN material is effectively regulated and controlled by regulating and controlling the doping amount of the Y element, the defects of high coercive force and low residual magnetism are overcome, the magnetic performance of the prepared magnetic powder is more suitable for the performance requirement of motor manufacture on a magnet, and the performance gap of the motor applied magnet is filled.

Drawings

FIG. 1 shows an alloy composition (Sm)_0.7Y_0.3)_8.5Fe₇₉N_12.5(at%) TEM images and statistical plots of grain size for permanent magnet material;

FIG. 2 shows the wheel speed (Sm) at 30m/s_0.7Y_0.3)_8.5Fe₇₉N_12.5And Sm_8.5Fe₇₉N_12.5XRD contrast pattern of (a).

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

In a first aspect of the invention, there is provided a rare earth permanent magnetic material with yttrium additions, the chemical formula of which is expressed in atomic percent as (Y)_xRE_1-x)_aFe_balM_bN_cWherein x is more than or equal to 0.05 and less than or equal to 0.4, a is more than or equal to 7 and less than or equal to 13, b is more than or equal to 0 and less than or equal to 3, c is more than or equal to 5 and less than or equal to 20, and the balance of Fe, namely bal is 100-a-b-c; RE is rare earth element Sm or the combination of rare earth element Sm and any one or more of Zr, Nd and Pr, M is Co and/or Nb, and N is nitrogen element.

The rare earth permanent magnetic material provided by the invention effectively improves TbCu under the condition of keeping saturation magnetization intensity not to be reduced₇Structural stability of metastable phase SmFe, TbCu obtained at 20-40m/s wheel speed₇The volume percentage of the phase is three phases (TbCu)₇Phase, Th₂Zn₁₇α -Fe phase) and more than 70 vol%, preferably more than 95 vol%, of the total volume content, the content of rare earth element Sm in RE has great influence on the structure of the strip of the rapidly quenched SmFe alloy, the Sm content is low, the soft magnetic phase is easy to form, the Sm content is high, the Sm content is easy to form Sm-rich phase, and the main phase TbCu is not favorable₇The structure of the rapid quenching alloy accounts for more than 95 vol%, and Zr, Nd and Pr can replace Sm elements, so the RE accounts for 70% or more of the total atomic proportion of the rare earth, and the atomic percentage content of Sm in the RE accounts for more than 95%.

Preferably, the material contains TbCu₇Phase, Th₂Zn₁₇Phase and soft magnetic phase α -Fe phase.

Preferably, the TbCu in the material₇The content of the phase is 70 vol% or more, preferably 90 vol% or more, and more preferably 95 vol% or more of the total volume content of the three phases;

preferably, the Th is₂Zn₁₇The content of the phase is 0-30 vol% of the total volume content of the three phases, excluding 0, preferably 1-10 vol%;

preferably, the content of the soft magnetic phase alpha-Fe phase in the rare earth permanent magnet material is less than 1 vol% of the total volume content of three phases.

Preferably, the atomic percentage of M is within 3%; preferably, M is within 1.5 atomic%.

Preferably, the atomic percentage of the element Sm in the RE accounts for more than 95% of the total content of the RE.

Preferably, the Y element enters TbCu₇Phase and/or Th₂Zn₁₇The proportion of phases is 100%. Because the system only contains TbCu₇Phase, Th₂Zn₁₇Three phases of α -Fe, and no other phase containing Y element, so that Y element can only enter TbCu by 100%₇Phase and/or Th₂Zn₁₇And (4) phase(s).

Preferably, the average thickness of the permanent magnetic powder of the rare earth permanent magnetic material is 20-40 μm, the rare earth permanent magnetic material is composed of nanocrystalline and amorphous materials with the average grain size of 20-100nm, and the standard deviation of the grain size is preferably 2-5. The standard deviation is used to measure how far the data value deviates from the arithmetic mean.

Because the thickness of the rapid quenching alloy is related to the preparation method, TbCu₇The structure requires a large cooling speed, but the excessive cooling speed is not beneficial to the formation of thin strips, so the thickness of the prepared samarium-iron alloy is proper; the grain size of the magnetic powder directly influences the magnetic performance, the magnetic powder with fine and uniform grains has higher coercive force and high thermal stability, and the grain size is kept between 20 and 100nm generally, so that the magnetic powder can obtain better magnetic performance. In order to achieve a higher coercive force level of the magnetic powder and to improve thermal stability, the grain size of the magnetic powder is preferably in the range of 10 to 60nm, and the grain size is preferably 2 to 5 standard deviations.

Preferably, the XRD peak (X-ray diffraction peak) of the permanent magnetic powder of the rare earth permanent magnetic material is shifted 1% to 5% rightward as a whole.

Preferably, the material is obtained by introducing yttrium element into a samarium-iron-nitrogen magnet by adopting a nanocrystalline bonded permanent magnet material preparation process.

The average grain size of the magnetic powder prepared by the invention is 20-100nm, the standard deviation is 2-5, the grain size distribution is more concentrated compared with binary SmFe, the influence of uneven grain size distribution on the deterioration of magnetic performance is effectively avoided, and the improvement of the magnetic performance is facilitated.

According to the invention, the components of the material are optimized by adding the rare earth element Y, the viscosity of the material is reduced, and the problems of high viscosity and poor amorphous forming capability of the binary SmFe alloy are solved. Meanwhile, Sm atom position is replaced by Y element with smaller atomic radius, and TbCu is stabilized by reducing average atomic radius of rare earth element₇Structure whereby TbCu can be obtained even at low wheel speed₇The phase is greater than 70 vol% of the alloy.

According to the invention, rare earth Sm is replaced by rare earth Y, so that the phenomenon of reduction of saturation magnetization caused by replacement of Fe atom position by adding traditional transition group metal is overcome, meanwhile, the anti-ferromagnetic coupling effect between Y and Fe further increases the saturation magnetization, so that the remanence is further increased, and the magnetic performance is greatly improved.

Preferably, the content of Y is 0 to 20 at%, excluding 0, and there is a good improvement in the residual magnetism of the magnet.

According to the invention, the squareness of a demagnetization curve is improved by adding the Y element, so that the performance of the magnet is more suitable for the requirement of motor manufacture on raw materials. The problem that the coercivity is higher and the remanence is low, namely the squareness is poor exists after the binary SmFe is subjected to nitridation, so that the final magnetic energy product is influenced. The rare earth Y element does not contain 4f electrons, so that the contribution to the alloy anisotropic field is small, the problem of poor squareness caused by higher coercive force and lower remanence of binary SmFe after nitridation can be solved through the addition of the rare earth Y element, and the overall magnetic performance of the magnet is more suitable for the requirement of motor production on the performance of the magnet.

Another aspect of the present invention provides a method for preparing the yttrium-doped rare earth permanent magnetic material, comprising the following steps:

(1) smelting an alloy which contains Sm, Y and Fe as main components and is added with Co and/or Nb elements into an ingot, casting the ingot onto a rotating roller after high-temperature melting, and rotating, rapidly quenching and cooling to obtain a rapidly quenched thin strip;

(2) casting the cast ingot to a rotating roller after high-temperature melting, and rotating, rapidly quenching and cooling to obtain a rapidly quenched thin strip;

(3) carrying out crystallization treatment on the quick-quenched thin strip obtained in the step (2), then quenching, and then crushing into alloy powder;

(4) and (4) nitriding the alloy powder obtained in the step (3) in a tube furnace to obtain the yttrium-added rare earth permanent magnet material.

The rare earth needed by the prepared raw material adopts single rare earth metal.

Preferably, the melting in the step (1) is vacuum induction melting.

Preferably, the high-temperature melting temperature is 200 ℃ or more and 400 ℃ or more, for example, 205 ℃, 225 ℃, 240 ℃, 260 ℃, 280 ℃, 300 ℃, 330 ℃, 350 ℃, 370 ℃, 390 ℃ or more, which are the melting points of the raw materials for preparing the rapid-quenched ribbon.

Preferably, the holding time for the high-temperature melting is 60 to 180s, for example, 70s, 90s, 110s, 120s, 140s, 150s, 170s, and the like.

Preferably, the casting is carried out by a high-vacuum single-roller rotary quenching method.

Preferably, the rotary quenching roll speed is 20 to 40m/s, for example 22m/s, 25m/s, 27m/s, 29m/s, 30m/s, 32m/s, 35m/s, 38m/s, etc.

Preferably, the cooling rate of the rotary rapid quenching cooling is 1 x 10⁵-5*10⁶At 2X 10 deg.C/s, for example⁵、4*10⁵、6*10⁵、8*10⁵The higher the supercooling degree is, the higher the growth rate of the alloy solidification is.

The different speed of the rotary quenching roller and the different cooling rate of the alloy liquid lead the organization structure, thermodynamics and dynamics in the system to change differently. Low wheel speed, 2:17 type SmFe phase and TbCu₇Form SmFe₉The two phases can appear simultaneously, the lower the wheel speed, the higher the proportion of the 2:17 type SmFe phase, the α -Fe phase is separated out, the higher the wheel speed, the gradual evolution of the obtained rapid quenching belt to the amorphous state along with the increase of the rotating speed of the roller, the obvious change of the atomic space arrangement condition of the amorphous belt, and the H caused by the change of the atomic space arrangement condition_cAnd B_sAll exhibit a downward trend. The experiment performed rapid cooling of the alloy melt (cooling rate 1 x 10) by optimizing the wheel speed⁵-5*10⁶At/s) or suppressing heterogeneous nucleation during cooling to make the alloyThe solidification with high growth rate (more than or equal to 1-100cm/s) occurs under large supercooling degree, thus preparing amorphous, quasicrystal and nano alloy materials, and the amorphous or nano crystal metastable state rapid quenching thin strip can be obtained through rapid solidification.

In one embodiment, the high-temperature melting is to melt the raw materials of the quick-quenched thin strips at 200-400 ℃ above the melting point of the raw materials, the speed of the rotary quenching roller is 20-40m/s, and in the step of rotary quick-quenching and cooling, the cooling rate is 1-10⁵-5*10⁶℃/s。

Preferably, the temperature of the crystallization treatment in step (3) is 650-.

The rapid quenching thin strip belongs to a disordered material, has a large amount of amorphous structures and has a large amount of defects such as dislocation, vacancy and the like, so that the rapid quenching sample needs to be subjected to effective crystallization treatment in order to improve the magnetic performance of the material. The present invention requires that the alloy be nucleated from a disordered amorphous state in large amounts in a short time in order to obtain a nanocrystalline material of uniform size. The thermodynamic experiment shows that the crystallization time is 40-70min, and the crystallization temperature is 650-800 deg.c, which is favorable to mass nucleation.

Preferably, the quenching is water cooling quenching, and the alloy after crystallization treatment is immersed in cold water.

Preferably, the quenching process is performed in a flowing Ar gas atmosphere.

Preferably, the quenching time is 40-70min, such as 40min, 45min, 50min, 55min, 60min, 65min, 70min, etc.

Quenching and cooling are key steps of the crystallization process, and directly influence the structure and the performance of a crystallized sample. The cooling speed is higher than the critical cooling speed during cooling so as to ensure that the alloy obtains a stable tissue structure; the quenching time is long enough to ensure that the alloy sample is fully water-cooled so as to avoid the re-growth of crystal grains and possible oxidation on the surface; when quenching is carried out under the flowing Ar atmosphere, the possibility that the sample is oxidized at high temperature can be prevented, partial heat can be taken away through Ar gas flow, and the cooling efficiency is improved.

Preferably, the average particle size of the alloy powder is 70 to 110. mu.m, for example, 70 μm, 75 μm, 80 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, or the like. The rapid quenching belt can be crushed into alloy powder with the average grain size of 70-110 mu m by a coarse crushing and grinding method.

Before the nitriding process, the granularity of the nitrided alloy powder is of great importance, and the granularity directly influences the absorption condition of the alloy powder to nitrogen in the nitriding process. The grain size of the alloy powder is too coarse, and nitrogen atoms are difficult to enter a crystal structure; the alloy powder is too fine and becomes very easy to oxidize due to large specific surface area, and an oxide film is generated, so that the diffusion is hindered to be smoothly carried out, the nitriding effect is greatly reduced, and the fine powder particles cannot meet the requirement of the market on the particle size of the magnetic powder.

Preferably, the temperature of the nitridation process in step (4) is 400-; the nitriding time is 15-25h, such as 15h, 16h, 18h, 20h, 22h, 24h, 25h and the like.

Nitridation process makes TbCu₇Form SmFe₉The phase magnet performance is substantially improved. Nitriding temperature and time are two important parameters that affect the effectiveness of nitriding. Increasing the nitriding temperature accelerates the diffusion of nitrogen atoms in the crystal and improves the nitriding effect. But the nitriding temperature is too high, the main phase is decomposed, and the magnetic property is reduced; if the nitriding temperature is too low, the diffusion kinetics will be insufficient, and regions not nitrided will be present inside the alloy, and the magnetic properties will also be affected. In the nitriding process, as the nitriding time is prolonged, the nitrogen concentration tends to be saturated, so that an appropriate nitriding time should be selected to improve the nitriding efficiency.

Preferably, the method specifically comprises the following steps:

(1) preparing materials: in atomic percent of (Y)_xRE_1-x)_aFe_balM_bN_cWeighing metal element ingredients according to a chemical formula, wherein x is more than or equal to 0.05 and less than or equal to 0.4, a is more than or equal to 7 and less than or equal to 13, b is more than or equal to 0 and less than or equal to 3, and the balance is Fe, namely bal is 100-a-b-c, and RE is rare earth element Sm or rare earth element REElement Sm and any one element or combination of more than one element of Zr, Nd and Pr, wherein M is Co and/or Nb;

(2) rapidly quenching to prepare a belt: and (3) carrying out vacuum melting on the prepared raw materials to form an ingot, and casting the smelted master alloy to a rotating roller for rotating, fast quenching and cooling by adopting a high-vacuum single-roller rotary quenching method to obtain the fast-quenched ribbon.

Melting the raw materials for preparing the rapid quenching thin strip in the range of 200-400 ℃ above the melting point of the raw materials, wherein the speed of the rotary quenching roller is between 20 and 40m/s, and in the step of rotary rapid quenching and cooling, the cooling speed is 10⁵-10⁶And the alloy is solidified at a high growth rate (more than or equal to 1-100cm/s) under a large supercooling degree.

The different speed of the rotary quenching roller and the different cooling rate of the alloy liquid lead the organization structure, thermodynamics and dynamics in the system to change differently. Low wheel speed, 2:17 type SmFe phase and TbCu₇Form SmFe₉Two phases can simultaneously appear, the lower the wheel speed, the higher the proportion of the 2:17 type SmFe phase, the α -Fe phase is separated out, the higher the wheel speed, the gradual evolution of the obtained rapid quenching belt to the amorphous state along with the increase of the rotating speed of the roller, the obvious change of the atomic space arrangement condition of the amorphous belt material, and the H caused_cAnd B_sAll exhibit a downward trend. The experiment is carried out by optimizing the wheel speed and rapidly cooling the alloy melt (cooling speed 10)⁵-10⁶Or heterogeneous nucleation in the cooling process is suppressed, so that the alloy is solidified at a high growth rate (more than or equal to 1-100cm/s) under a large supercooling degree, thereby preparing amorphous, quasicrystal and nano alloy materials, and obtaining the amorphous or nano crystal metastable state rapid quenching thin strip through rapid solidification.

(3) Crystallization treatment: the temperature of the crystallization treatment is 650-800 ℃, the time of the crystallization treatment is 40-70min, and the crystallization treatment process is carried out under the flowing Ar atmosphere.

Crystallization is one of the key steps affecting the magnetic performance of the rapid quenching alloy, and the rapid quenching SmFe alloy contains TbCu₇Form SmFe₉A phase, a few soft magnetic phases α -Fe and amorphous, and a large amount of amorphous structure exists in the structure, and a large amount ofAnd defects such as dislocation, vacancy and the like, so that effective crystallization treatment on a rapid quenching sample is required to improve the magnetic property of the material. The crystallization treatment changes the amorphous structure into a crystal structure on one hand and improves the uniformity of the microstructure on the other hand. Too high a crystallization temperature leads to a large amount of TbCu₇Structure direction Th₂Zn₁₇The structure is changed, and simultaneously α -Fe phase is generated to greatly reduce the magnetic property, so that the invention adjusts Th in the alloy by optimizing the crystallization process on the basis of regulating the magnetic property by doping Y content₂Zn₁₇The content of the structural phase and the α -Fe soft magnetic phase ensures that the content of the α -Fe soft magnetic phase is less than 1vol percent, and TbCu₇The structural phase is the main phase, the content is more than 70 vol%, and Th is₂Zn₁₇Is less than 30 vol%, and therefore the temperature of the heat treatment is preferably 650 ℃ to 800 ℃.

(4) Water cooling quenching: the quenching process is to immerse the alloy after crystallization treatment in cold water, the quenching time is 40-70min, and the quenching process is carried out under the flowing Ar atmosphere.

Cooling is a key step of the crystallization process, and directly influences the structure and performance of the crystallized sample. The cooling speed is higher than the critical cooling speed during cooling so as to ensure that the alloy obtains a stable tissue structure; during quenching, the alloy sample is fully cooled by water to avoid the re-growth of crystal grains and possible oxidation on the surface, and during quenching, the sample is subjected to oxidation under flowing Ar atmosphere, so that the possibility that the sample is oxidized at high temperature can be prevented, partial heat can be taken away through Ar gas flow, and the cooling efficiency is improved.

And crushing the quick-quenched thin strip into alloy powder with the average grain size of 70-110 mu m by a coarse crushing and grinding method.

(5) Nitriding: the temperature of the nitridation process is 400-500 ℃, and the nitridation time is 15-25 h.

Nitridation process makes TbCu₇Form SmFe₉The phase magnet performance is substantially improved. Nitriding temperature and time are two important parameters that affect the effectiveness of nitriding. Increasing the nitriding temperature accelerates the diffusion of nitrogen atoms in the crystal and improves the nitriding effect. However, the nitriding temperature is too high, and the main phase will be decomposed to causeThe magnetic performance is reduced; if the nitriding temperature is too low, the diffusion kinetics will be insufficient, and regions not nitrided will be present inside the alloy, and the magnetic properties will also be affected. In the nitriding process, as the nitriding time is prolonged, the nitrogen concentration tends to be saturated, so that an appropriate nitriding time should be selected to improve the nitriding efficiency.

The invention provides a TbCu added with rare earth Y element₇A SmFeN nanocrystalline bonded magnet is prepared by melting alloy by high-vacuum single-roll rotary quenching process, spraying onto a roller rotating at high speed, and rapidly cooling the alloy melt (cooling speed 10)⁵-10⁶At the temperature of more than or equal to 1-100cm/s) under a large supercooling degree, so as to provide conditions for preparing a metastable phase, obtain a fast quenching thin strip with fine grains or even an amorphous structure, perform crystallization treatment and crushing on the thin strip, and perform nitridation treatment to obtain nitrided powder. Due to Y element to metastable phase TbCu₇The stability of the structure can obtain single TbCu at lower wheel speed₇And (3) a main phase structure. The average grain size of the prepared magnetic powder is 20-100nm, the standard deviation is 2-5, the grain size distribution is more concentrated relative to binary SmFe, the influence of uneven grain size distribution on the deterioration of magnetic performance is effectively avoided, and the improvement of the magnetic performance is facilitated.

According to the invention, rare earth Y element is used for replacing Sm element of samarium-iron-nitrogen material, the ratio of Sm element to Y element is regulated, the viscosity of alloy liquid can be reduced, the amorphous forming capability of the material is enhanced, on the other hand, the average radius of rare earth element is reduced by adding Y, and TbCu is stabilized₇Structure to obtain TbCu even at low wheel speed₇The phase is more than 70 vol% of alloy, so that the production cost is greatly reduced.

According to the invention, by utilizing the characteristic that Y element does not contain 4f electrons and has small contribution to an anisotropic field, the magnetic performance of the SmFeN material is effectively regulated and controlled by regulating and controlling the doping amount of the Y element, the defects of high coercive force and low residual magnetism are overcome, the magnetic performance of the prepared magnetic powder is more suitable for the performance requirement of motor manufacture on a magnet, and the performance gap of the motor applied magnet is filled.

For further illustration of the present invention, the following will describe the preparation method of a rare earth permanent magnetic material with yttrium addition in detail with reference to the following examples, but it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and the detailed implementation and specific operation procedures are given only for further illustration of the features and advantages of the present invention, not for limitation of the claims of the present invention, and the protection scope of the present invention is not limited to the following examples.