CN114974777A - Neodymium-iron-boron magnet and preparation method thereof - Google Patents

Abstract

The invention provides a compound of formula R _x T _{100‑x‑y1‑y2‑ z} M _y1 A _y2 B _z The neodymium iron boron magnet is shown, wherein R is selected from one or more of Pr, Nd and RH; m is selected from one or more of Zr, Nb, Hf, Si, Sn, Ge, Ag, Au, Bi and Mn; a is Cu, Ga, Al and Ti; wherein the addition amount of the elements in A satisfies the formula 1 (Cu + Ti)/Ga 2. The invention also provides a preparation method of the neodymium iron boron magnet. The invention optimally designs the specific addition amount by the formula limitation of the addition proportion of each element in A, specially designs the other components, improves the remanence, the coercive force and the magnetic energy product of the magnet alloy, has higher performance, reduces the production cost, has simple process and wide applicability, and is suitable for large-scale industrial production.

Description

Neodymium-iron-boron magnet and preparation method thereof

Technical Field

The invention relates to the technical field of magnet preparation, and relates to a neodymium iron boron magnet and a preparation method thereof.

Background

Sintered neodymium iron boron is a permanent magnet with the highest energy density found by human beings so far, and large-scale commercial production is realized at present. Since the discovery, sintered nd-fe-b sintered magnets have been widely used in many fields such as computer hard disks, hybrid vehicles, medical treatment, and wind power generation, and their application range and yield are increasing year by year, especially in the field of new energy vehicles. Since many applications of sintered nd-fe-b magnets are in high temperature environments, it is required to have not only high remanence but also high coercivity. The coercive force is a main parameter of the permanent magnet material, and the higher the coercive force is, the stronger the demagnetization resistance of the permanent magnet material is. When the sintered magnet is applied, the higher the coercive force of the neodymium iron boron sintered magnet is, the better the coercive force is, the better temperature stability can be ensured, and the sintered magnet can work under the condition of higher temperature.

In the prior art, Dy and Tb are generally used for replacing Nd to improve the coercive force of the neodymium iron boron sintered magnet; however, the heavy rare earth Dy and Tb is short in reserves, expensive and capable of reducing remanence. And, Dy and Tb are vulnerable to the impact of the rare earth policy, thereby bringing a risk of price instability or large fluctuation.

Therefore, how to further improve the comprehensive performance of the magnet, so that the coercive force, remanence and magnetic energy product of the magnet can be improved, and meanwhile, heavy rare earth elements are not adopted or are not adopted a little, which becomes one of the problems to be solved by many researchers in the industry.

Disclosure of Invention

The invention aims to provide a neodymium iron boron magnet, which can improve the remanence, the coercive force and the magnetic energy product of the neodymium iron boron magnet.

In view of the above, the present application provides a neodymium iron boron magnet as shown in formula (i),

R _x T _{100-x-y1-y2-z} M _y1 A _y2 B _z (Ⅰ)；

wherein R is selected from one or more of Pr, Nd and RH;

t comprises Fe;

m is selected from one or more of Zr, Nb, Hf, Si, Sn, Ge, Ag, Au, Bi, Al and Mn;

a is selected from Cu, Ga and Ti; and the mass percentage of the elements in A satisfies that (Cu + Ti)/Ga is more than or equal to 1 and less than or equal to 2;

x, y1, y2 and z are mass percent of corresponding elements, x is more than or equal to 28.0 wt% and less than or equal to 33.0 wt%, y1 is more than or equal to 0 wt% and less than or equal to 3.0 wt%, y2 is more than or equal to 0.75 wt% and less than or equal to 1.7 wt%, and z is more than or equal to 0.86 wt% and less than or equal to 0.98 wt%.

Preferably, the content of R is 28.5 wt% to 32.5 wt%; the RH comprises Dy and/or Tb;

and/or, the content of Pr is 0 wt% -14.5 wt%;

and/or, the content of Nd is 14.0 wt% -32.5 wt%;

and/or, when the RH comprises Tb, the content of Tb is 0 wt% -4.5 wt% and is not 0;

and/or, when the RH includes Dy, the content of Dy is 0 wt% to 4.5 wt%, and is not 0.

Preferably, T also comprises Co, and the content of Co is 0-1.0 wt% and is not 0.

Preferably, the content of A is 0.8-1.5 wt%.

Preferably, the mass percent of the Cu is 0.2-0.5 wt%; and/or the Ga accounts for 0.35 to 0.45 weight percent; and/or the mass percentage of Ti is 0.2 wt% -0.35 wt%.

Preferably, the mass percentage of the elements in the A is more than or equal to 1.2 and less than or equal to (Cu + Ti)/Ga is less than or equal to 1.8.

The application also provides a preparation method of the neodymium iron boron magnet, which comprises the following steps:

A) according to the raw material ratio, subjecting the neodymium iron boron raw material to a rapid hardening sheet process to obtain a neodymium iron boron rapid hardening sheet;

B) sequentially carrying out hydrogen crushing and airflow milling on the neodymium iron boron quick-setting sheets to obtain neodymium iron boron powder;

C) and sequentially carrying out orientation forming and sintering on the neodymium iron boron powder to obtain the neodymium iron boron magnet.

Preferably, the temperature of the rapid hardening flake process is 1450-1490 ℃; the thickness of the neodymium iron boron quick-setting sheet is 0.10-0.60 mm;

in the hydrogen crushing process, the hydrogen absorption time is 1-3 h, and the hydrogen absorption temperature is 20-300 ℃; the dehydrogenation time is 3-7 h, and the dehydrogenation temperature is 550-600 ℃;

after the hydrogen is crushed, a water cooling step is also included; the water cooling time is 1-3 h.

Preferably, the jet mill is added with lubricant for milling;

the lubricant is 0.02 wt% -0.1 wt% of powder obtained by hydrogen crushing;

the particle size of the neodymium iron boron powder is 2-10 mu m;

the orientation forming comprises orientation pressing and isostatic pressing which are sequentially carried out;

the orientation forming specifically comprises the following steps: under the condition of no oxygen or low oxygen, the neodymium iron boron powder is subjected to orientation molding; the magnetic field intensity of the orientation forming is 1.2-3T;

the sintering temperature is 1000-1200 ℃; the sintering time is 5-15 h;

the sintering vacuum degree is less than or equal to 0.02 Pa;

the sintering process also comprises an aging treatment step;

the aging treatment comprises a first aging treatment and a second aging treatment which are sequentially carried out;

the temperature of the first time aging treatment is 800-980 ℃, and the time of the first time aging treatment is 2-15 hours;

the temperature of the second aging treatment is 420-580 ℃, and the time of the second aging treatment is 1-8 hours.

The invention provides a compound of formula R _x T _{100-x-y1-y2-z} M _y1 A _y2 B _z The neodymium iron boron magnet is limited by a formula of adding proportion among elements in A, specific adding amount is designed, and other components are specially and reasonably designed, so that a titanium-rich phase enriched in a magnetic phase crystal boundary becomes a pinning field center of 'pinning' domain wall movement when the magnet is demagnetized, and the movement of a magnetic domain and a wall is hindered, thereby improving the intrinsic coercive force of the magnet alloy; meanwhile, the titanium-rich phase generates a pinning effect relative to the movement of the crystal boundary of the magnetic phase crystal grains, so that the growth of the magnetic phase can be effectively prevented, the crystal grains are refined, and the remanence, the coercive force and the magnetic energy product of the magnet alloy are further improved; is effectiveThe method solves the inherent defects that the alloy has low melting point, plays a role in wetting crystal boundary, has the function of weakening magnetic exchange coupling, can enter the structure of the main phase of the neodymium iron boron through the diffusion effect in sintering, improves the sintering temperature resistance, does not generate abnormal growth of crystal grains, can only improve the coercive force to a certain extent, but cannot improve the remanence and the magnetic energy product.

The neodymium iron boron magnet and the preparation method thereof provided by the invention can be used for preparing a neodymium iron boron magnetic material with better performance, can improve the remanence, the coercive force and the magnetic energy product of the magnet alloy under the condition of using or not using heavy rare earth elements, reduces the production cost, has simple process and wide applicability, and is suitable for large-scale industrial production. Experimental results show that compared with the neodymium iron boron magnet of the same type, the coercive force improvement value of the neodymium iron boron magnet provided by the invention is larger than 1.3 kOe.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

Aiming at the problems of high magnet heavy rare earth consumption and high production cost in the prior art, the method optimizes the performance of the neodymium iron boron magnet by selecting a composite alloy element adding mode; meanwhile, aiming at the defects that the coercivity can be improved to a certain degree by the compositely added titanium copper or titanium gallium alloy elements, the magnetic performance is not remarkably improved, and the remanence and the magnetic energy product are basically unchanged or reduced, the application limits the addition of the composite elements to meet a specific formula, and finally improves the remanence, the coercivity and the magnetic energy product of the neodymium iron boron magnet.

In the present application, the sources of all raw materials are not particularly limited, and may be those purchased in the market or prepared according to conventional methods well known to those skilled in the art.

All the raw materials of the invention are not particularly limited in purity, and the invention preferably adopts the conventional purity used in the field of industrial pure or neodymium iron boron magnet.

Specifically, the invention provides a sintered neodymium-iron-boron magnet, which has a general formula as follows: r _x T _{100-x-y1-y2-z} M _y1 A _y2 B _z ；

Wherein R is selected from one or more of Pr, Nd and RH;

t comprises Fe;

m is selected from one or more of Zr, Nb, Hf, Si, Sn, Ge, Ag, Au, Al, Bi and Mn;

a is selected from Cu, Ga and Ti; and the mass percentage of A is more than or equal to 1 and less than or equal to (Cu + Ti)/Ga is less than or equal to 2;

x, y1, y2 and z are mass percent of corresponding elements, x is more than or equal to 28.0 wt% and less than or equal to 33.0 wt%, y1 is more than or equal to 0 wt% and less than or equal to 3.0 wt%, y2 is more than or equal to 0.75 wt% and less than or equal to 1.7 wt%, and z is more than or equal to 0.86 wt% and less than or equal to 0.98 wt%.

The present invention is not particularly limited to the specific definitions of the general formulae, and may be expressed in such a manner as is well known to those skilled in the art.

In the general formula of formula (i) of the present invention, R is selected from one or more of Pr, Nd and PH, preferably including Pr and/or Nd, more preferably Pr and Nd, and for further optimizing the performance of the magnet and improving the applicability, preferably further including Dy and/or Tb, more preferably Dy or Tb. The content of R is 28.0-33.0 wt%, and specifically, the content of R is 28.5-32.5 wt%; more specifically, the content of R is 28.6 wt%, 28.8 wt%, 29.0 wt%, 29.2 wt%, 29.5 wt%, 29.8 wt%, 30.0 wt%, 30.3 wt%, 30.4 wt%, 30.6 wt%, 30.7 wt%, 30.9 wt%, 31.0 wt%, 31.3 wt%, 31.6 wt%, 31.9 wt%, 32.0 wt%, 32.1 wt%, 32.5 wt%, 32.7 wt%, 32.9 wt%, or 33.0 wt%.

In R, the content of Pr is 0 to 14.5 weight percent; and/or, the content of Nd is 14.0 wt% -32.5 wt%; and/or, when the RH contains Tb, the content of Tb is 0 wt% -4.5 wt%; and/or, when the RH contains Dy, the Dy content is 0 wt% -4.5 wt%. Specifically, the content of Pr is 2 to 12.5 wt%, more specifically, the content of Pr is 2.2 wt%, 2.5 wt%, 3.3 wt%, 3.6 wt%, 3.8 wt%, 4.1 wt%, 4.5 wt%, 4.8 wt%, 5.0 wt%, 5.1 wt%, 5.2 wt%, 5.6 wt%, 5.7 wt%, 5.9 wt%, 6.0 wt%, 6.1 wt%, 6.2 wt%, 6.4 wt%, 6.6 wt%, 6.7 wt%, 6.9 wt%, 7.1 wt%, 7.2 wt%, 7.3 wt%, 7.5 wt%, 7.7 wt%, 7.8 wt%, 8.0 wt%, 8.1 wt%, 8.3 wt%, 8.6 wt%, 8.8 wt%, 9.1 wt%, 9.3 wt%, 9.6 wt%, 9.7 wt%, 9.9.9 wt%, 10.1 wt%, 10.5 wt%, 10.6 wt%, 10.8 wt%, 11.12 wt%, 11.2 wt%, 11 wt%, 5 wt%, 5.2 wt%, 5 wt%, 6 wt%, 6.7.7 wt%, 6 wt%, 6.8.8.8.8.8.8.8 wt%, 7.8.8.8.8.1 wt%, 9.1 wt%, 11 wt%, 11.1 wt%, 11.12.12.12 wt%, or 11.12 wt%. The content of Nd is 16.5 to 30.0 wt%, more specifically 16.8 wt%, 17.0 wt%, 17.2 wt%, 17.4 wt%, 17.6 wt%, 17.8 wt%, 18.1 wt%, 18.2 wt%, 18.5 wt%, 18.7 wt%, 19.1 wt%, 19.2 wt%, 19.6 wt%, 19.8 wt%, 20.2 wt%, 20.3 wt%, 20.6 wt%, 20.8 wt%, 20.7 wt%, 21.1 wt%, 21.3 wt%, 21.6 wt%, 21.9 wt%, 22.0 wt%, 22.2 wt%, 22.3 wt%, 22.5 wt%, 22.7 wt%, 22.8 wt%, 23.0 wt%, 23.3 wt%, 23.6 wt%, 24.0 wt%, 24.1 wt%, 24.2 wt%, 24.6 wt%, 24.9 wt%, 25.2 wt%, 25.5 wt%, 25.9 wt%, 26.9 wt%, 27.26.2 wt%, 27.9 wt%, 27.8 wt%, 27.9 wt%, 27.8 wt%, 27.9 wt%, 29.8 wt%, 27.1 wt%, 27.2 wt%, 27.9 wt%, 27.8 wt%, 27.1 wt%, 27.2 wt%, 27.8 wt%, 27.9 wt%, 27.8 wt%, or 29.8 wt%.

In the general formula of formula I of the invention, M is selected from one or more of Zr, Nb, Hf, Si, Sn, Ge, Ag, Au, Al, Bi and Mn, more preferably two or more of Zr, Nb, Hf, Si, Sn, Ge, Ag, Au, Al, Bi and Mn, and most preferably Zr, Al and Nb. The content of M is 0-3.0 wt%, specifically, the content of M is 0-2.5 wt%, more specifically, the content of Zr is 0-1.0 wt%, and the content of Nb is 0-1.5 wt%; more specifically, the Zr content is 0.1 wt%, 0.18 wt%, 0.2 wt%, 0.26 wt%, 0.3 wt%, 0.32 wt%, 0.35 wt%, 0.42 wt%, 0.46 wt%, 0.49 wt%, 0.52 wt%, 0.55 wt%, 0.58 wt%, 0.62 wt%, 0.66 wt%, 0.70 wt%, 0.78 wt%, 0.82 wt%, 0.86 wt%, 0.89 wt%, 0.92 wt%, or 0.95 wt%. The Nb content is 0.12 wt%, 0.15 wt%, 0.20 wt%, 0.22 wt%, 0.25 wt%, 0.32 wt%, 0.35 wt%, 0.46 wt%, 0.50 wt%, 0.53 wt%, 0.58 wt%, 0.62 wt%, 0.66 wt%, 0.73 wt%, 0.79 wt%, 0.82 wt%, 0.96 wt%, 0.99 wt%, 1.32 wt%, 1.41 wt%, or 1.43 wt%. The mass percent of the Al is 0.02 wt% -0.4 wt%; more specifically, the content of Al is 0.03 wt%, 0.08 wt%, 0.10 wt%, 0.11 wt%, 0.13 wt%, 0.16 wt%, 0.17 wt%, 0.19 wt%, 0.20 wt%, 0.21 wt%, 0.23 wt%, 0.26 wt%, 0.27 wt%, 0.29 wt%, 0.30 wt%, 0.31 wt%, 0.33 wt%, 0.35 wt%, 0.36 wt%, 0.37 wt%, 0.39 wt%, 0.40 wt%, 0.42 wt%, 0.44 wt%, or 0.45 wt%.

The A is selected from Cu, Ga, Al and Ti; and the mass percentage of the elements in A satisfies that (Cu + Ti)/Ga is more than or equal to 1 and less than or equal to 2; specifically, the content of A is 0.8-1.5 wt%; more specifically, the mass percent of Cu is 0.2 wt% to 0.5 wt%; and/or the Ga accounts for 0.35 to 0.45 weight percent; and/or the mass percent of Ti is 0.2 wt% -0.35 wt%; more specifically, the Cu content is 0.22 wt%, 0.23 wt%, 0.25 wt%, 0.27 wt%, 0.29 wt%, 0.32 wt%, 0.35 wt%, 0.38 wt%, 0.40 wt%, 0.41 wt%, 0.42 wt%, 0.45 wt%, 0.48 wt%, or 0.5 wt%; the Ga content is 0.35 wt%, 0.37 wt%, 0.38 wt%, 0.39 wt%, 0.40 wt%, 0.41 wt%, 0.42 wt%, 0.43 wt%, 0.44 wt% or 0.45 wt%; the Ti content is 0.22 wt%, 0.24 wt%, 0.25 wt%, 0.27 wt%, 0.28 wt%, 0.30 wt%, 0.32 wt%, 0.33 wt%, 0.34 wt%, or 0.35 wt%. And the mass percentage of the elements in the A is more than or equal to 1.2 (Cu + Ti)/Ga is less than or equal to 1.8; more specifically, the mass fraction of the element in a satisfies 1.22, 1.26, 1.27, 1.29, 1.30, 1.31, 1.33, 1.35, 1.38, 1.41, 1.43, 1.45, 1.48, 1.50, 1.51, 1.52, 1.54, 1.55, 1.58, 1.60, 1.61, 1.62, 1.63, 1.64, 1.66, 1.68, 1.71, 1.72, 1.75, 1.78, or 1.79.

According to the sintered neodymium-iron-boron magnet, through the composite addition of titanium, especially by the design of specific single elements and integral addition, the microstructure of crystal grains is optimized under the action of titanium-rich phase 'nailing gadolinium', so that the coercive force is improved, and the remanence and the magnetic energy product are improved. The added titanium element is too little, and the pinning effect is not obvious; and the titanium element is added in too much amount, the volume of the enriched non-magnetic phase at the grain boundary is increased, the thickness is increased, an isolation effect is generated between magnetic phases, the exchange coupling is weakened to reduce the remanence of the alloy, the hardness is reduced, and the processing performance is reduced.

The invention further provides a preparation method of the neodymium iron boron magnet, which comprises the following steps:

A) according to the raw material ratio, subjecting the neodymium iron boron raw material to a rapid hardening sheet process to obtain a neodymium iron boron rapid hardening sheet;

B) sequentially carrying out hydrogen crushing and airflow milling on the neodymium iron boron quick-setting sheets to obtain neodymium iron boron powder;

C) and sequentially carrying out orientation forming and sintering on the neodymium iron boron powder to obtain the neodymium iron boron magnet.

In the above steps of the present invention, the selection principle and the preferred range of the used neodymium iron boron raw material correspond to the selection principle and the preferred range of the neodymium iron boron raw material, if no special reference is made, and no further description is given here.

The method comprises the steps of firstly, subjecting a neodymium iron boron raw material to a rapid hardening thin sheet process to obtain the neodymium iron boron rapid hardening thin sheet.

The source of the neodymium iron boron raw material is not particularly limited, and the source of the conventional magnet raw material known to those skilled in the art can be selected and adjusted according to factors such as actual production conditions, product requirements and quality control.

The specific steps of the rapid hardening flake process are not particularly limited, and the steps of the rapid hardening flake process in the sintered neodymium iron boron magnet preparation process, which are well known to those skilled in the art, are adopted, and the temperature of the rapid hardening flake process is preferably 1450-1490 ℃, more preferably 1455-1485 ℃, more preferably 1460-1480 ℃, and more preferably 1465-1475 ℃. The thickness of the neodymium iron boron quick-setting sheet is preferably 0.10-0.60 mm, more preferably 0.20-0.50 mm, and more preferably 0.25-0.35 mm.

The neodymium iron boron rapid-hardening thin slices obtained in the steps are sequentially subjected to hydrogen crushing and airflow milling to obtain neodymium iron boron powder.

The specific step of hydrogen crushing in the invention is the step of a hydrogen crushing process in the preparation process of the sintered neodymium iron boron magnet, which is well known to the skilled in the art, and the skilled in the art can select and adjust the hydrogen crushing process according to factors such as actual production conditions, product requirements, quality control and the like, wherein in the hydrogen crushing process, the hydrogen absorption time is preferably 1-3 h, more preferably 1.2-2.8 h, and more preferably 1.5-2.5 h; the hydrogen absorption temperature is preferably 20-300 ℃, more preferably 70-250 ℃, and more preferably 120-200 ℃; the dehydrogenation time is preferably 3-7 h, more preferably 3.5-6.5 h, and more preferably 4-5 h; the dehydrogenation temperature is preferably 550-600 ℃, more preferably 560-590 ℃, and more preferably 570-580 ℃.

After the hydrogen is crushed, the method preferably further comprises a water cooling step. The water cooling time is preferably 1-3 h, more preferably 1.2-2.8 h, and more preferably 1.5-2.5 h.

The invention further improves the milling effect of the jet mill, and the jet mill is more preferably added with a lubricant for jet milling. The lubricant is not particularly limited in the present invention, and the lubricant may be ground with a magnet air stream well known to those skilled in the art. The mass ratio of the lubricant to the powder after hydrogen crushing is preferably 0.02-0.1%, more preferably 0.03-0.09%, and more preferably 0.05-0.08%. The average particle size of the milled mixed fine powder, namely the average particle size of the mixed fine powder, is preferably 2 to 5 μm, more preferably 2.5 to 4.5 μm, and even more preferably 3 to 4 μm.

According to the invention, the neodymium iron boron magnet is obtained by subjecting the neodymium iron boron powder obtained in the above steps to orientation forming and sintering.

The specific steps of the orientation forming are not particularly limited by the present invention, and the specific steps of the magnet orientation forming known to those skilled in the art can be selected and adjusted according to factors such as actual production conditions, product requirements, and quality requirements, and the orientation forming of the present invention preferably comprises the steps of orientation pressing and isostatic pressing, more preferably the magnetic field orientation forming is performed in a sealed glove box without oxygen or oxygen, and ensures that the product is free of oxygen or oxygen during the whole operation and isostatic pressing process.

The magnetic field intensity of the orientation pressing of the invention is preferably1.2-3T, more preferably 1.7-2.5T, and more preferably 2.0-2.2T; the time for orientation pressing is preferably 2-10 s, more preferably 3-9 s, and more preferably 5-7 s. The pressure of the isostatic pressing is preferably 120-240 MPa, more preferably 150-210 MPa, and more preferably 160-200 MPa; the dwell time of the isostatic compaction is preferably 30-120 s, more preferably 50-100 s, and more preferably 70-80 s. In order to further ensure and improve the performance of the final magnet product, the density of the magnet blank after orientation pressing is preferably 3.8-4.3 g/cm ³ More preferably 3.9 to 4.2g/cm ³ More preferably 4.0 to 4.1g/cm ³ . The density of the magnet blank after isostatic pressing is preferably 4.5-5.0 g/cm ³ More preferably 4.6 to 4.9g/cm ³ More preferably 4.7 to 4.8g/cm ³ 。

The magnet body obtained in the last step is sintered, the specific steps of the sintering are not particularly limited, and the specific steps of the magnet sintering well known to those skilled in the art can be adopted, and the sintering is preferably vacuum sintering; the sintering process preferably further comprises an aging treatment step; the aging treatment more preferably includes a first aging treatment and a second aging treatment.

The sintering temperature is preferably 1000-1200 ℃, more preferably 1025-1175 ℃, more preferably 1040-1150 ℃, and more preferably 1050-1080 ℃; the sintering time is preferably 5-15 h, more preferably 7-13 h, and more preferably 8-10 h. The sintered vacuum bag of the present invention is preferably equal to or less than 0.02Pa, more preferably equal to or less than 0.015Pa, and even more preferably equal to or less than 0.01 Pa. In order to further ensure and improve the performance of the final magnet product, the density of the sintered magnet blank is preferably 7.4-7.7 g/cm ³ More preferably 7.45 to 7.65g/cm ³ More preferably 7.5 to 7.6g/cm ³ 。

The specific steps of the aging treatment are not particularly limited, the specific steps of the magnet aging treatment known to a person skilled in the art can be used, the person skilled in the art can select and adjust the steps according to factors such as actual production conditions, product requirements and quality requirements, and the temperature of the first aging treatment is preferably 800-980 ℃, and more preferably 820-960 ℃; the time of the first aging treatment is preferably 1 to 10 hours, and more preferably 2 to 8 hours. The temperature of the second aging treatment is preferably 420-580 ℃, and more preferably 440-560 ℃; the time of the second aging treatment is preferably 1 to 8 hours, and more preferably 2 to 7 hours.

The overall preparation process of the magnet is not particularly limited, and the sintered neodymium iron boron magnet well known to those skilled in the art can be prepared by a process of preparing raw materials by blending, a rapid hardening sheet process (smelting), pulverizing into powder by hydrogen crushing, powder orientation compression molding, vacuum sintering and the like, namely, a blank is subjected to surface treatment and processing to obtain the finished product neodymium iron boron magnet.

The neodymium iron boron magnet and the preparation method thereof provided by the invention not only can prepare a neodymium iron boron magnetic material, but also can improve the remanence, the coercive force and the magnetic energy product of the magnet alloy under the condition of using or using less heavy rare earth elements, thereby reducing the production cost, and the preparation method is simple in process, wide in applicability and suitable for large-scale industrial production.

Experimental results show that compared with the neodymium iron boron magnet of the same type, the coercive force improvement value of the neodymium iron boron magnet provided by the invention is larger than 1.3 kOe.

For further understanding of the present invention, the neodymium iron boron magnet and the preparation method thereof provided by the present invention are described in detail below with reference to the following examples, and the scope of the present invention is not limited by the following examples.

Table 1 raw material formulation table (wt%) of neodymium iron boron magnet provided in example and comparative example

Example 1

According to the formula of example 1 shown in Table 1 (the addition ratio of each element of the compound A is (Cu + Ti)/Ga is 1.26) and the formula of comparative example 1 (the addition ratio of each element of the compound A is (Cu + Ti)/Ga is 3), the obtained mixture is respectively mixed, the obtained mixture is smelted in a vacuum induction smelting furnace, the obtained melt is cast at 1460 ℃, cooled on a copper roller with the rotating speed of 40 revolutions per minute to obtain a neodymium iron boron alloy cast sheet with the average thickness of 0.30mm, the cast sheet is subjected to hydrogen crushing, the hydrogen absorption time in the hydrogen crushing process is 1 hour, the dehydrogenation time is 5 hours, the dehydrogenation temperature is 600 ℃, the hydrogen crushing process is carried out for 2 hours, the obtained powder is subjected to air flow milling to obtain powder with the particle size of 3.4 microns, the obtained powder is subjected to magnetic field orientation molding treatment under 17320 Gauss magnetic field in a sealed oxygen-free glove box and then subjected to isostatic pressing treatment under 200MPa, obtaining a magnet body; and sintering the magnet blank at 1070 ℃ for 6 hours, then carrying out aging treatment at 910 ℃ for 2 hours, and finally carrying out aging treatment at 525 ℃ for 5 hours to obtain the neodymium-iron-boron magnet.

The neodymium iron boron magnet prepared by the method is compared with a common neodymium iron boron magnet in a parallel test, the comparison result is shown in table 2, and the table 2 is the performance data of the magnet before and after implementation;

table 2 magnet performance data tables before and after implementation

Sample marking	Br(kGs)	Hcj(kOe)	Hk/Hcj
				Example 1	14.22	18.23	0.98
Comparative example 1	14.2	16.82	0.98

As can be seen from Table 1, the mass percentage value of the comparative example (Cu + Ti)/Ga is more than 2, the contents of Cu, Ti and Ga are out of the range of the patent requirement, and the coercive force is different from that of the example 1 by 1.41 kOe.

Example 2

According to the formula of example 2 shown in Table 1 (the addition ratio of each element of the compound A is (Cu + Ti)/Ga is 1.43) and the formula of comparative example 2 (the addition ratio of each element of the compound A is (Cu + Ti)/Ga is 0.5), smelting the obtained mixture in a vacuum induction smelting furnace, casting the obtained molten liquid at 1465 ℃, cooling on a copper roller with the rotating speed of 40 revolutions per minute to obtain a neodymium iron boron alloy cast sheet with the average thickness of 0.28mm, carrying out hydrogen crushing on the cast sheet, carrying out hydrogen absorption time of 1 hour and dehydrogenation time of 5 hours in the hydrogen crushing process, cooling at 600 ℃ for 2 hours, carrying out jet milling on the obtained powder to obtain powder with the particle size of 3.4 microns, carrying out magnetic field orientation molding treatment on the obtained powder in a sealed oxygen-free glove box at 17500 Gauss magnetic field, and then carrying out isostatic pressing at 200MPa, obtaining a magnet body; and sintering the magnet blank at 1070 ℃ for 6 hours, then carrying out aging treatment at 910 ℃ for 2 hours, and finally carrying out aging treatment at 525 ℃ for 5 hours to obtain the neodymium-iron-boron magnet.

The neodymium iron boron magnet prepared by the method is compared with a common neodymium iron boron magnet in a parallel test, the comparison result is shown in table 3, and table 3 is the performance data of the magnet before and after implementation;

table 3 table of magnet performance data before and after implementation

Sample marking	Br(kGs)	Hcj(kOe)	Hk/Hcj
				Example 2	14.1	19.1	0.98
Comparative example 2	14.15	17.5	0.98

As shown in Table 3, the mass percentage value of (Cu + Ti)/Ga of the comparative example 2 is less than 1, the contents of Cu, Ti and Ga are out of the range required by the patent, and the coercive force is different from that of the example 2 by 1.60 kOe.

Example 3

According to the formula of example 3 shown in table 1 (the adding ratio of each element of the compound A is (Cu + Ti)/Ga is 1.63) and the formula of comparative example 3 (the adding ratio of each element of the compound A is (Cu + Ti)/Ga is 2.43), the obtained mixture is smelted in a vacuum induction smelting furnace, the obtained melt is cast at 1468 ℃, the cooled melt is cooled on a copper roller with the rotating speed of 40 revolutions per minute to obtain a neodymium iron boron alloy cast sheet with the average thickness of 0.32mm, the cast sheet is subjected to hydrogen crushing, the hydrogen absorption time in the hydrogen crushing process is 1 hour, the dehydrogenation time is 5 hours, the dehydrogenation temperature is 600 ℃, the hydrogen crushing process is carried out for 2 hours, the obtained powder is subjected to air flow milling to obtain powder with the granularity of 3.4 microns, the obtained powder is subjected to magnetic field orientation molding treatment under a 60 Gauss magnetic field in a sealed oxygen-free glove box, and then is subjected to isostatic pressing under 200MPa, obtaining a magnet body; and sintering the magnet blank at 1070 ℃ for 6 hours, then carrying out aging treatment at 910 ℃ for 2 hours, and finally carrying out aging treatment at 525 ℃ for 5 hours to obtain the neodymium-iron-boron magnet.

The neodymium iron boron magnet prepared by the method is compared with a common neodymium iron boron magnet in a parallel test, the comparison result is shown in table 4, and the table 4 is the performance data of the magnet before and after implementation;

table 4 table of magnet performance data before and after implementation

Sample marking	Br(kGs)	Hcj(kOe)	Hk/Hcj
				Example 3	13.65	20.65	0.97
Comparative example 3	13.57	19.23	0.98

As can be seen from Table 4, the mass percentage value of the comparative example (Cu + Ti)/Ga is greater than 2, and the contents of Cu, Ti and Ga are within the range required by the patent, but the coercive force is still different from that of the embodiment by 1.42 kOe.

Example 4

According to the formula of example 4 shown in table 1 (the addition ratio of each element of the compound A is (Cu + Ti)/Ga is 1.67) and the formula of comparative example 4 (the addition ratio of each element of the compound A is (Cu + Ti)/Ga is 0.89), smelting the obtained mixture in a vacuum induction smelting furnace, casting the obtained melt at 1458 ℃, cooling on a copper roller with the rotating speed of 40 revolutions per minute to obtain a neodymium iron boron alloy cast sheet with the average thickness of 0.29mm, carrying out hydrogen crushing on the cast sheet, wherein the hydrogen absorption time in the hydrogen crushing process is 1 hour, the dehydrogenation time is 5 hours, the dehydrogenation temperature is 600 ℃, cooling is 2 hours, carrying out jet milling on the powder to obtain powder with the particle size of 3.4 microns, carrying out magnetic field orientation molding treatment on the prepared powder in a sealed oxygen-free glove box under 17700 high-gauss magnetic field, then carrying out isostatic pressing treatment under 200MPa to obtain a magnet blank, sintering the magnet blank at 1070 ℃ for 6 hours, then carrying out aging treatment for 2 hours at 910 ℃, and finally carrying out aging treatment for 5 hours at 525 ℃ to obtain the neodymium iron boron magnet.

The neodymium iron boron magnet prepared by the method is compared with a common neodymium iron boron magnet in a parallel test, and the comparison result is shown in table 5, wherein the table 5 shows the performance data of the magnet before and after the implementation.

TABLE 5 magnet Performance data tables before and after implementation

Sample marking	Br(kGs)	Hcj(kOe)	Hk/Hcj
				Example 4	13.34	21.5	0.97
Comparative example 4	13.38	19.8	0.97

As can be seen from Table 5, the mass percentage value of the comparative example (Cu + Ti)/Ga is less than 1, and the contents of Cu, Ti and Ga are within the range required by the patent, but the coercive force is still different by 1.70kOe compared with the embodiment.

In summary, (Cu + Ti)/Ga is required to satisfy the formula range of the application, and the performance is better in the range (the mass percent of Cu is 0.2 wt% -0.5 wt%, the mass percent of Ga is 0.35 wt% -0.45 wt%, and the mass percent of Ti is 0.2 wt% -0.35 wt%).

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. A neodymium iron boron magnet as shown in formula (I),

R _x T _{100-x-y1-y2-z} M _y1 A _y2 B _z (Ⅰ)；

wherein R is selected from one or more of Pr, Nd and RH;

t comprises Fe;

m is selected from one or more of Zr, Nb, Hf, Si, Sn, Ge, Ag, Au, Bi, Al and Mn;

a is selected from Cu, Ga and Ti; and the mass percentage of the elements in A satisfies that (Cu + Ti)/Ga is more than or equal to 1 and less than or equal to 2;

x, y1, y2 and z are mass percent of corresponding elements, x is more than or equal to 28.0 wt% and less than or equal to 33.0 wt%, y1 is more than or equal to 0 wt% and less than or equal to 3.0 wt%, y2 is more than or equal to 0.75 wt% and less than or equal to 1.7 wt%, and z is more than or equal to 0.86 wt% and less than or equal to 0.98 wt%.

2. The ndfeb magnet according to claim 1, wherein the content of R is 28.5 wt% to 32.5 wt%; the RH comprises Dy and/or Tb;

and/or, the content of Pr is 0 wt% -14.5 wt%;

and/or, the content of Nd is 14.0 wt% -32.5 wt%;

and/or, when the RH comprises Tb, the content of Tb is 0 wt% -4.5 wt% and is not 0;

and/or, when the RH includes Dy, the content of Dy is 0 wt% to 4.5 wt%, and is not 0.

3. The ndfeb magnet according to claim 1, wherein T further comprises Co in an amount of 0-1.0 wt% and not 0.

4. The ndfeb magnet according to claim 1, wherein the content of a is 0.8-1.5 wt%.

5. The ndfeb magnet according to claim 1 or 4, characterized in that the mass percentage of Cu is 0.2-0.5 wt%; and/or the Ga accounts for 0.35 to 0.45 weight percent; and/or the mass percentage of Ti is 0.2 wt% -0.35 wt%.

6. The ndfeb magnet according to claim 1, characterized in that the mass percentage of the elements in a satisfies 1.2 ≦ (Cu + Ti)/Ga ≦ 1.8.

7. The method for preparing the neodymium-iron-boron magnet according to any one of claims 1 to 6, characterized by comprising the following steps:

A) according to the raw material ratio, subjecting the neodymium iron boron raw material to a rapid hardening sheet process to obtain a neodymium iron boron rapid hardening sheet;

B) sequentially carrying out hydrogen crushing and airflow milling on the neodymium iron boron quick-setting sheets to obtain neodymium iron boron powder;

C) and sequentially carrying out orientation forming and sintering on the neodymium iron boron powder to obtain the neodymium iron boron magnet.

8. The preparation method according to claim 7, wherein the temperature of the rapid hardening flake process is 1450-1490 ℃; the thickness of the neodymium iron boron quick-setting sheet is 0.10-0.60 mm;

in the hydrogen crushing process, the hydrogen absorption time is 1-3 h, and the hydrogen absorption temperature is 20-300 ℃; the dehydrogenation time is 3-7 h, and the dehydrogenation temperature is 550-600 ℃;

after the hydrogen is crushed, a water cooling step is also included; the water cooling time is 1-3 h.

9. The method of claim 7, wherein the jet mill is milled with the addition of a lubricant;

the lubricant is 0.02 wt% -0.1 wt% of powder obtained by hydrogen crushing;

the particle size of the neodymium iron boron powder is 2-10 mu m;

the orientation forming comprises orientation pressing and isostatic pressing which are sequentially carried out;

the orientation forming specifically comprises the following steps: under the condition of no oxygen or low oxygen, the neodymium iron boron powder is subjected to orientation molding; the magnetic field intensity of the orientation forming is 1.2-3T;

the sintering temperature is 1000-1200 ℃; the sintering time is 5-15 h;

the sintering vacuum degree is less than or equal to 0.02 Pa;

the sintering process also comprises an aging treatment step;

the aging treatment comprises a first aging treatment and a second aging treatment which are sequentially carried out;

the temperature of the first aging treatment is 800-980 ℃, and the time of the first aging treatment is 2-15 hours;

the temperature of the second aging treatment is 420-580 ℃, and the time of the second aging treatment is 1-8 hours.