CN115083713A - Sintered 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 sintered neodymium-iron-boron magnet shown; wherein x is more than or equal to 28.5 wt% and less than or equal to 32.0 wt%, y1 is more than or equal to 0.2 wt% and less than or equal to 0.8 wt%, y2 is more than or equal to 0.60 wt% and less than or equal to 1.5 wt%, and z is more than or equal to 0.88 wt% and less than or equal to 0.94 wt%; r is selected from one or more of rare earth elements and must contain Nd; m is one or more selected from Ti, Zr and Nb, and A is Cu, Ga and Al. The application also provides a preparation method of the sintered neodymium-iron-boron magnet. The invention adds M element and A element, optimally designs specific adding amount, specially designs other components, improves remanence, coercive force and magnetic energy product of the magnet alloy, has higher performance, reduces production cost, has simple process and wide applicability, and is suitable for large-scale industrial production.

Description

Sintered neodymium-iron-boron magnet and preparation method thereof

Technical Field

The invention relates to the technical field of magnetic materials, in particular to a sintered 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.

Many applications of sintered nd-fe-b magnets are in high temperature environments, and thus require 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, so that the neodymium iron boron sintered magnet can be ensured to have better temperature stability and can work under the condition of higher temperature.

In the prior art, the method for improving the coercive force of the neodymium iron boron sintered magnet is to use Dy and Tb to partially replace Nd so as to improve the coercive force. However, heavy rare earths Dy and Tb reduce remanence; and the risk of unstable or large fluctuation of price due to the susceptibility of Dy and Tb to the impact of the rare earth policy.

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 adopted less, which becomes a key point and a hot point for research of technicians in the field.

Disclosure of Invention

The invention aims to provide a sintered neodymium-iron-boron magnet which has better remanence, magnetic energy and coercive force.

In view of the above, the present application provides a sintered nd-fe-b magnet represented by formula (I);

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

wherein x, y1, y2 and z are respectively the mass percent of the corresponding elements, x is more than or equal to 28.5 wt% and less than or equal to 32.0 wt%, y1 is more than or equal to 0.2 wt% and less than or equal to 0.8 wt%, y2 is more than or equal to 0.60 wt% and less than or equal to 1.5 wt%, and z is more than or equal to 0.88 wt% and less than or equal to 0.94 wt%;

r is selected from one or more of rare earth elements and must contain Nd;

a is selected from Cu, Ga and Al, and the content of Cu is 0.30-0.55 wt%, the content of Ga is 0.25-0.45 wt%, and the content of Al is 0.02-0.5 wt%;

m is selected from one or more of Ti, Zr and Nb, and A/M is more than 1.5 and less than 6;

t is selected from Fe and Co, the content of Co is 0-1.0 wt%, and the balance is Fe.

Preferably, when M is selected from Ti only, the content of Ti is 0.2 wt% to 0.35 wt%; and 3< A/M < 6;

when M is only selected from Zr, the content of Zr is 0.35wt percent to 0.75 percent; and 1.5< A/M < 3;

when M is only selected from Nb, the content of Nb is 0.35 wt% -0.75 wt%; and 1.5< A/M < 3;

when M is selected from two or three of Ti, Zr and Nb, M 'is Ti + 2+ Zr + Nb, M' is 0.4 wt% -0.8 wt%, and Ti + Zr + Nb is more than 0.2 wt%; and 1.5< A/M' < 3.

Preferably, the rare earth elements are selected from one or more of Pr, Dy, Tb, Gd, La and Ce, the content of Pr is 0-14.5 wt%, the content of Nd is 10-32 wt%, the content of Dy + Tb is 0-4.5 wt%, the content of Gd is 0-4.5 wt%, and the content of La + Ce is 0-15 wt%.

Preferably, the content of Pr is 7 wt% -9 wt%, the content of Nd is 20 wt% -25.5 wt%, and the content of Dy is 0-3 wt%.

Preferably, the Cu content is 0.35 wt% to 0.5 wt%, the Ga content is 0.30 wt% to 0.45 wt%, and the Al content is 0.02 wt% to 0.3 wt%.

Preferably, the content of Co is 0-0.8 wt%, and the content of B is 0.90-0.94 wt%.

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

A) mixing the raw materials of the neodymium iron boron sintered magnet according to the proportion, and then carrying out quick-setting sheet treatment to obtain a neodymium iron boron quick-setting 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 sintered neodymium iron boron magnet.

Preferably, the processing temperature of the quick-setting sheet is 1400-1500 ℃, and the thickness of the neodymium iron boron quick-setting sheet is 0.10-0.60 mm;

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

in the process of the jet milling, a lubricant is added for milling, the lubricant is 0.02-0.1% of the mass of mixed fine powder obtained by hydrogen crushing, and the average particle size of the powder after the jet milling is 2-6 microns.

Preferably, the orientation forming comprises orientation pressing and isostatic pressing which are sequentially carried out; the magnetic field intensity of the orientation forming is 1.2-3T.

Preferably, the sintering temperature is 1000-1200 ℃, the time is 5-15 h, and the vacuum degree is less than or equal to 0.02 Pa;

the sintering process also comprises aging treatment, wherein the aging treatment comprises first aging treatment and second aging treatment;

the temperature of the first time aging treatment is 800-980 ℃, and the time of the first time aging treatment is 1-10 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 sintered neodymium-iron-boron magnet, which is characterized in that a high-melting-point element M is added in a plurality of alloy elements, the addition amount of the high-melting-point element M is increased, the other components are reasonably designed and matched with the addition of a low-melting-point element A, the A/M is in a certain proportion range, and the M element and the A element are matched to form an alloy phase; the addition of the high-melting-point element M can refine grains and improve the coercive force, and the composite addition of the low-melting-point element A can enable the M element to form an alloy phase and be enriched in a grain boundary to improve the structure of the grain boundary and improve the coercive force.

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 higher performance, can be used for improving the remanence, the coercive force and the magnetic energy product of the magnet alloy under the condition of not increasing heavy rare earth elements, reduces the production cost, and 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 1.3kOe under the condition that the remanence is not reduced.

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 problem that the cost and the performance of a sintered neodymium-iron-boron magnet cannot be balanced in the prior art, the application provides the sintered neodymium-iron-boron magnet, the matching degree of elements is realized by adding alloy elements and limiting the proportional relation of the elements, and finally the obtained sintered neodymium-iron-boron magnet has better remanence, magnetic energy and coercive force. Specifically, the embodiment of the invention discloses a sintered neodymium iron boron magnet shown in a formula (I);

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

wherein x, y1, y2 and z are respectively the mass percent of the corresponding elements, x is more than or equal to 28.5 wt% and less than or equal to 32.0 wt%, y1 is more than or equal to 0.2 wt% and less than or equal to 0.8 wt%, y2 is more than or equal to 0.60 wt% and less than or equal to 1.5 wt%, and z is more than or equal to 0.88 wt% and less than or equal to 0.94 wt%;

r is selected from one or more of rare earth elements and must contain Nd;

a is selected from Cu, Ga and Al, and the content of Cu is 0.30-0.55 wt%, the content of Ga is 0.25-0.45 wt%, and the content of Al is 0.02-0.5 wt%;

m is selected from one or more of Ti, Zr and Nb, and A/M is more than 1.5 and less than 6;

t is selected from Fe and Co, the content of Co is 0-1.0 wt%, and the balance is Fe.

The present invention is not particularly limited to the specific definition of the formula I shown, and such expressions well known to those skilled in the art are understood herein as mass percentages of the corresponding elements.

In the present application, said R is selected from one or more of the rare earth elements and must comprise Nd, in particular Nd and one or more of Pr, Dy, Tb, Gd, La and Ce; the content of R is 28.5-32.0 wt%; more specifically, 0-14.5 wt% of Pr, 10-32 wt% of Nd, 0-4.5 wt% of Dy + Tb, 0-4.5 wt% of Gd, and 0-15 wt% of La + Ce; more specifically, the content of Pr is 3-12 wt%, the content of Nd is 15-30 wt%, and the content of Dy is 0-3 wt%; more specifically, the content of Pr is 3.2 wt%, 3.6 wt%, 3.9 wt%, 4.5 wt%, 4.8 wt%, 5.0 wt%, 5.3 wt%, 5.5 wt%, 5.7 wt%, 5.9 wt%, 6.3 wt%, 6.5 wt%, 6.8 wt%, 7.0 wt%, 7.3 wt%, 7.5 wt%, 7.6 wt%, 7.8 wt%, 7.9 wt%, 8.0 wt%, 8.2 wt%, 8.5 wt%, 8.8 wt%, 8.9 wt%, 9.1 wt%, 9.2 wt%, 9.5 wt%, 9.6 wt%, 9.8 wt%, 10.0 wt%, 10.3 wt%, 10.5 wt%, 10.8 wt%, 10.9 wt%, 11.2 wt%, 11.3 wt%, 11.5 wt%, or 11.9 wt%, the content of Nd is 15.2 wt%, 15.8 wt%, 15.9.9 wt%, 16.0 wt%, 16.9 wt%, 16.19 wt%, 16.20 wt%, 16.9 wt%, 16.9.9 wt%, 16.9 wt%, 1 wt%, 16.9.9 wt%, 16.9 wt%, 1.9 wt%, 16.9 wt%, 1.9 wt%, 16.9.9 wt%, 16.9 wt%, 1 wt%, 1.2 wt%, 16.9.9 wt%, 1.9.9 wt%, 1.9 wt%, 16.9 wt%, 1.9 wt%, 1.20 wt%, 1 wt%, 16.20 wt%, 1 wt%, 16.9 wt%, 1 wt%, 16.2 wt%, 1.9 wt%, 1 wt%, 16.2 wt%, 16.9 wt%, 16.20 wt%, 16.9 wt%, 1.9 wt%, 16.9 wt%, 16.9.9 wt%, 16.9 wt%, 1 wt%, 16.9 wt%, 1 wt%, 1.9 wt%, 16.9 wt%, 1.2 wt%, 16.9 wt%, 1 wt%, 9 wt%, 16.2 wt%, 16.9 wt%, 1.9 wt%, 16.9 wt%, 1 wt%, 16.20 wt%, 16.2 wt%, 16.9 wt%, 21.8 wt%, 22 wt%, 22.3 wt%, 22.6 wt%, 22.8 wt%, 23.2 wt%, 23.5 wt%, 23.7 wt%, 23.8 wt%, 24.0 wt%, 24.3 wt%, 24.5 wt%, 24.6 wt%, 24.8 wt%, 25.2 wt%, 25.3 wt%, 25.6 wt%, 25.7 wt%, 25.9 wt%, 26.2 wt%, 26.8 wt%, 27.4 wt%, 27.6 wt%, 27.8 wt%, 28.2 wt%, 28.6 wt%, 29.1 wt%, 29.6 wt%, or 29.9 wt%, and the Dy content is 3.0%.

In the present application, A is selected from Cu, Ga and Al, and the content of Cu is 0.30-0.55 wt%, the content of Ga is 0.25-0.45 wt%, and the content of Al is 0.02-0.5 wt%; specifically, the content of Cu is 0.35 wt% -0.5 wt%, the content of Ga is 0.30 wt% -0.45 wt%, and the content of Al is 0.02 wt% -0.3 wt%; more specifically, the content of Cu is 0.35 wt%, 0.36 wt%, 0.37 wt%, 0.38 wt%, 0.39 wt%, 0.40 wt%, 0.41 wt%, 0.42 wt%, 0.44 wt%, or 0.45 wt%; ga in an amount of 0.26, 0.28, 0.30, 0.31, 0.32, 0.35, 0.36, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, or 0.45 wt%; the Al content is 0.03 wt%, 0.05 wt%, 0.08 wt%, 0.10 wt%, 0.12 wt%, 0.13 wt%, 0.14 wt%, 0.16 wt%, 0.17 wt%, 0.19 wt%, 0.20 wt%, 0.21 wt%, 0.24 wt%, 0.25 wt%, 0.26 wt%, 0.28 wt%, 0.29 wt%, or 0.30 wt%. The element in A can form an M-A alloy phase, optimize a crystal boundary, wet the crystal boundary and greatly improve the coercivity Hcj under the condition that the remanence Br is kept unchanged.

In the application, the content of M is 0.2-0.8 wt%, and the M is specifically selected from one or more of Ti, Zr and Nb, and A/M is more than 1.5 and less than 6; more specifically, when M is selected from Ti alone, the content of Ti is 0.2 wt% to 0.35 wt%; and 3< A/M < 6; at this time, M is selected only from Ti, which forms a TiA2 phase with the element in A in the above range to facilitate the increase of Hcj, and the content of Ti and the content of A/M exceeding this range results in a deficiency of TiA2 phase, which may make Ti or A superfluous to adversely affect the increase of Hcj to decrease Br. More specifically, the content of Ti is 0.21 wt%, 0.23 wt%, 0.24 wt%, 0.25 wt%, 0.26 wt%, 0.28 wt%, 0.29 wt%, 0.30 wt%, 0.31 wt%, 0.32 wt%, 0.33 wt%, 0.34 wt%, or 0.35 wt%; A/M is in particular 3.2, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.2, 4.3, 4.4, 4.8, 4.6, 4.7, 4.8, 5.0, 5.3 or 5.8.

When M is only selected from Zr, the content of Zr is 0.35wt percent to 0.75 percent; and 1.5< A/M < 3; in this case, M is selected only from Zr, which forms ZrA2 phases with the element in A, in the above range, it is advantageous for increasing Hcj, while exceeding this range in Zr content and A/M content results in ZrA2 phase deficiency, with either excess Zr or A being detrimental for increasing Hcj to decrease Br. More specifically, the Zr content is 0.35 wt%, 0.37 wt%, 0.39 wt%, 0.41 wt%, 0.42 wt%, 0.44 wt%, 0.45 wt%, 0.48 wt%, 0.52 wt%, 0.55 wt%, 0.57 wt%, 0.59 wt%, 0.61 wt%, 0.63 wt%, 0.65 wt%, 0.66 wt%, 0.68 wt%, 0.70 wt%, 0.72 wt%, or 0.75 wt%. A/M is in particular 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 or 2.9.

When M is only selected from Nb, the content of Nb is 0.35wt percent to 0.75wt percent; and 1.5< A/M < 3; in this case, M is selected from Nb only, which forms NbA2 phase with the element in A, in the above range, it is advantageous to increase Hcj, and the content of Nb and the content of A/M exceeding this range also result in NbA2 phase deficiency, which may make Nb superfluous or A is not advantageous to increase Hcj and decrease Br. More specifically, the content of Nb is 0.38 wt%, 0.40 wt%, 0.42 wt%, 0.43 wt%, 0.44 wt%, 0.45 wt%, 0.46 wt%, 0.48 wt%, 0.51 wt%, 0.53 wt%, 0.55 wt%, 0.58 wt%, 0.61 wt%, 0.63 wt%, 0.66 wt%, 0.67 wt%, 0.68 wt%, 0.70 wt%, 0.71 wt%, 0.72 wt%, or 0.74 wt%. A/M is in particular 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 or 2.9.

When M is selected from two or three of Ti, Zr and Nb, M 'is Ti + 2+ Zr + Nb, and M' is 0.4 wt% -0.8 wt%; and 1.5< A/M' < 3. In this case, M is selected from two or three of Ti, Zr and Nb, which forms M 'A2 phase with the element in A, in the above range, it is advantageous to increase Hcj, and the content of M' and the content of A/M 'exceeding this range result in insufficient M' A2 phase, and excess Nb or A is not advantageous to increase Hcj and decrease Br. More specifically, M' is 0.41 wt%, 0.42 wt%, 0.44 wt%, 0.45 wt%, 0.46 wt%, 0.48 wt%, 0.49 wt%, 0.50 wt%, 0.51 wt%, 0.52 wt%, 0.53 wt%, 0.55 wt%, 0.56 wt%, 0.57 wt%, 0.58 wt%, 0.62 wt%, 0.63 wt%, 0.65 wt%, 0.66 wt%, 0.71 wt%, 0.72 wt%, 0.73 wt%, 0.74 wt%, or 0.75 wt%; A/M' is specifically 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 or 2.9.

T is selected from Fe and Co, wherein the content of Co is 0-1.0 wt%, more specifically, the content of Co is 0-0.8 wt%.

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

A) mixing the raw materials of the neodymium iron boron sintered magnet according to the proportion, and then carrying out quick-setting sheet treatment to obtain a neodymium iron boron quick-setting 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 sintered neodymium iron boron magnet.

In the above steps of the present invention, the selection principle and the preferred range of the 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, can be selected and adjusted by the skilled in the art according to factors such as actual production conditions, product requirements and quality control, 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 sheet obtained in the above steps is subjected to hydrogen crushing and airflow milling in sequence to obtain neodymium iron boron powder. The present invention does not particularly limit the specific step of hydrogen crushing, and the step of hydrogen crushing process in the preparation process of the sintered nd-fe-b magnet, which is well known to those skilled in the art, may be sufficient. 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.

In order to further improve the milling effect of the jet mill, the jet mill is more preferably subjected to jet milling with the addition of a lubricant. 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 mixed fine powder 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 powder obtained in the above steps is subjected to orientation molding and sintering in sequence to obtain the neodymium iron boron magnet. 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 is preferably 1.2-3T, more preferably 1.7-2.5T, and more preferably 1.6-2.4T; 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 preferably70-80 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 present invention does not specifically limit the specific steps of the aging treatment, and the specific steps of the aging treatment of the magnet known to those skilled in the art may be used. 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 can be used for preparing a neodymium iron boron magnetic material with higher performance, can be used for improving the remanence, the coercive force and the magnetic energy product of the magnet alloy under the condition of not increasing heavy rare earth elements, reduces the production cost, and 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 1.3kOe under the condition that the remanence is not reduced.

For further understanding of the present invention, the sintered nd-fe-b 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 materials recipe data Table (wt%)

Note: in the table, when M is selected from two or three of Ti, Zr and Nb, A/M represents A/M'.

Example 1

Proportioning according to example 1 shown in Table 1, smelting the obtained raw materials in a vacuum induction smelting furnace, casting the obtained molten liquid at 1460 ℃, and 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 0.30 mm; hydrogen crushing the casting 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 carried out for 2 hours, the obtained powder is subjected to jet milling to obtain powder with the granularity of 3.4 mu m, the prepared powder is subjected to magnetic field orientation forming treatment in a sealed oxygen-free glove box under the condition of 17320 Gauss magnetic field, and then isostatic pressing treatment is carried out under the condition of 200MPa to obtain a magnet blank; 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.

Comparative example 1a and comparative example 1b were prepared in the same procedure.

The neodymium iron boron magnet prepared by the method is compared with the neodymium iron boron magnet prepared by the comparative example 1 in a parallel test, the comparison result is shown in table 2, and the table 2 is a performance data table of the magnets prepared in the examples and the comparative examples;

TABLE 2 tables of magnet property data for examples and comparative examples

Sample marking	Br(kGs)	Hcj(kOe)	Hk/Hcj
				Example 1	14.32	18.5	0.98
Comparative example 1a	14.30	16.9	0.98
				Comparative example 1b	14.36	16.3	0.98

As can be seen from tables 1 and 2: in example 1 and comparative example 1a, Ti is the same but A/M is less than the range, and the coercive force is different by 1.6 kOe; example 1 compares to example 1b with a/M in the range, but with Ti less than the range, the coercivity was 2.20kOe different.

Example 2

Proportioning according to example 2 shown in Table 1, smelting the obtained raw materials in a vacuum induction smelting furnace, casting the obtained molten liquid at 1465 ℃, and 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 0.28 mm; hydrogen crushing 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 carried out for 2 hours, the obtained powder is subjected to jet milling to obtain powder with the granularity of 3.4 microns, the prepared powder is subjected to magnetic field orientation forming treatment in a sealed oxygen-free glove box under a 17500 Gauss magnetic field, and then isostatic pressing treatment is carried out under 200MPa to obtain a magnet blank; 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.

Comparative example 2 was prepared by the same procedure

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 a performance data table of the magnets prepared in the examples and the comparative examples;

TABLE 3 tables of magnet property data of examples and comparative examples

Sample marking	Br(kGs)	Hcj(kOe)	Hk/Hcj
				Example 2	13.61	20.4	0.98
Comparative example 2	13.70	17.8	0.98

As can be seen from tables 1 and 3: in example 2 and comparative example 2a, where A/M is greater than the range and M is not within the range, the coercivity is different by 2.6 kOe.

Example 3

Proportioning according to example 3 shown in Table 1, smelting the obtained raw materials in a vacuum induction smelting furnace, casting the obtained molten liquid at 1468 ℃, and 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 0.32 mm; hydrogen crushing 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 carried out for 2 hours, the obtained powder is subjected to jet milling to obtain powder with the granularity of 3.4 microns, the prepared powder is subjected to magnetic field orientation forming treatment in a sealed oxygen-free glove box under a 17560 Gauss magnetic field, and then isostatic pressing treatment is carried out under 200MPa to obtain a magnet blank; 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.

Comparative example 3 was prepared by the same procedure.

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 table 4 is a performance data table of the magnets prepared in the examples and the comparative examples;

TABLE 4 tables of magnet property data of examples and comparative examples

Sample marking	Br(kGs)	Hcj(kOe)	Hk/Hcj
				Example 3	13.84	20.0	0.97
Comparative example 3	13.65	19.2	0.98

As can be seen from tables 1 and 4: m is within the range in example 3 and comparative example 3, but A/M is out of range and the coercive force differs by 0.8 kOe.

Example 4

Proportioning according to example 4 shown in Table 1, smelting the obtained raw materials in a vacuum induction smelting furnace, casting the obtained molten liquid at 1458 ℃, and cooling on a copper roller with the rotating speed of 40 r/min to obtain a neodymium iron boron alloy cast sheet with the average thickness of 0.29 mm; hydrogen crushing the casting 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 carried out for 2 hours, the obtained powder is subjected to jet milling to obtain powder with the granularity of 3.4 microns, the prepared powder is subjected to magnetic field orientation forming treatment in a sealed oxygen-free glove box under a 17700 Gauss magnetic field, and then isostatic pressing treatment is carried out under 200MPa to obtain a magnet blank; 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. Comparative example 4 was prepared according to the same procedure.

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 5, and table 5 is a performance data table of the magnets prepared in the examples and the comparative examples;

TABLE 5 tables of magnet property data of examples and comparative examples

Sample marking	Br(kGs)	Hcj(kOe)	Hk/Hcj
				Example 4	13.51	20.9	0.97
Comparative example 4	13.40	20.3	0.97

As can be seen from tables 1 and 5: in example 4 and comparative example 4, M is out of range, A/M is in range, remanence difference is 0.11kGs, and coercive force difference is 0.6 kOe.

Example 5

Batching according to example 5 shown in Table 6, smelting the obtained raw materials in a vacuum induction smelting furnace, casting the obtained melt at 1458 ℃, and cooling on a copper roller with the rotating speed of 40 r/min to obtain a neodymium iron boron alloy cast sheet with the average thickness of 0.29 mm; hydrogen crushing the casting 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 carried out for 2 hours, the obtained powder is subjected to jet milling to obtain powder with the granularity of 3.4 microns, the prepared powder is subjected to magnetic field orientation forming treatment in a sealed oxygen-free glove box under a 17700 Gauss magnetic field, and then isostatic pressing treatment is carried out under 200MPa to obtain a magnet blank; 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.

Comparative example 5 was prepared by the same procedure.

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 6, and table 6 is a performance data table of the magnets prepared in the embodiment and the comparative example;

TABLE 6 data of magnet properties prepared in examples and comparative examples

Sample marking	Br(kGs)	Hcj(kOe)	Hk/Hcj
				Example 5	13.18	21.9	0.97
Comparative example 5	12.87	21.5	0.97

As can be seen from tables 1 and 6: A/M 'is within the range in example 5 and comparative example 5, but M' is not within the range, the difference in remanence is 0.31kGs, and the difference in coercive force is 0.4 kOe.

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 (10)

1. A sintered NdFeB magnet represented by formula (I);

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

wherein x, y1, y2 and z are respectively the mass percent of the corresponding elements, x is more than or equal to 28.5 wt% and less than or equal to 32.0 wt%, y1 is more than or equal to 0.2 wt% and less than or equal to 0.8 wt%, y2 is more than or equal to 0.60 wt% and less than or equal to 1.5 wt%, and z is more than or equal to 0.88 wt% and less than or equal to 0.94 wt%;

r is selected from one or more of rare earth elements and must contain Nd;

a is selected from Cu, Ga and Al, and the content of Cu is 0.30-0.55 wt%, the content of Ga is 0.25-0.45 wt%, and the content of Al is 0.02-0.5 wt%;

m is selected from one or more of Ti, Zr and Nb, and A/M is more than 1.5 and less than 6;

t is selected from Fe and Co, the content of Co is 0-1.0 wt%, and the balance is Fe.

2. The sintered ndfeb magnet according to claim 1, wherein when M is selected from Ti alone, the Ti content is 0.2 wt% to 0.35 wt%; and 3< A/M < 6;

when M is only selected from Zr, the content of Zr is 0.35wt percent to 0.75 percent; and 1.5< A/M < 3;

when M is only selected from Nb, the content of Nb is 0.35wt percent to 0.75wt percent; and 1.5< A/M < 3;

when M is selected from two or three of Ti, Zr and Nb, M 'is Ti + 2+ Zr + Nb, M' is 0.4 wt% -0.8 wt%, and Ti + Zr + Nb is more than 0.2 wt%; and 1.5< A/M' < 3.

3. The sintered ndfeb magnet according to claim 1, wherein the rare earth element is selected from one or more of Pr, Dy, Tb, Gd, La and Ce, the content of Pr is 0 to 14.5 wt%, the content of Nd is 10 to 32 wt%, the content of Dy + Tb is 0 to 4.5 wt%, the content of Gd is 0 to 4.5 wt%, and the content of La + Ce is 0 to 15 wt%.

4. The sintered neodymium-iron-boron magnet according to claim 1 or 3, wherein the Pr content is 7-9 wt%, the Nd content is 20-25.5 wt%, and the Dy content is 0-3 wt%.

5. The sintered ndfeb magnet according to claim 1, wherein the Cu content is 0.35 wt% to 0.5 wt%, the Ga content is 0.30 wt% to 0.45 wt%, and the Al content is 0.02 wt% to 0.3 wt%.

6. The sintered neodymium-iron-boron magnet according to claim 1, wherein the content of Co is 0-0.8 wt%, and the content of B is 0.90-0.94 wt%.

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

A) mixing the raw materials of the neodymium iron boron sintered magnet according to the proportion, and then carrying out quick-setting sheet treatment to obtain a neodymium iron boron quick-setting 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 sintered neodymium iron boron magnet.

8. The preparation method according to claim 7, wherein the temperature for processing the quick-setting sheet is 1400-1500 ℃, and the thickness of the neodymium iron boron quick-setting sheet is 0.10-0.60 mm;

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

in the process of the jet milling, a lubricant is added for milling, the lubricant is 0.02-0.1% of the mass of mixed fine powder obtained by hydrogen crushing, and the average particle size of the powder after the jet milling is 2-6 microns.

9. The production method according to claim 7, wherein the orientation molding includes orientation pressing and isostatic pressing which are performed in this order; the magnetic field intensity of the orientation forming is 1.2-3T.

10. The preparation method according to claim 7, wherein the sintering temperature is 1000-1200 ℃, the time is 5-15 h, and the vacuum degree is less than or equal to 0.02 Pa;

the sintering process also comprises aging treatment, wherein the aging treatment comprises first aging treatment and second aging treatment;

the temperature of the first aging treatment is 800-980 ℃, and the time of the first aging treatment is 1-10 hours;

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