CN116453792A - NdFeB substrate - Google Patents

Abstract

The present disclosure relates to neodymium iron boron substrates, which are in a sintered state, wherein the substrate has a grain boundary area fraction difference of less than or equal to 1% between a direction parallel to the direction of easy magnetization and a direction perpendicular to the direction of easy magnetization. In an embodiment of the present disclosure, the neodymium iron boron substrate of the present disclosure is obtained by sintering a powder composition obtained by mixing a raw material neodymium iron boron alloy powder with an alloy powder composed of R and M, wherein the mass ratio of R to M is x (100-x), R is one or more of Nd and Pr, M is a combination of one or more of Cu, al, ga, zn, x is the mass fraction of R and 0.ltoreq.x.ltoreq.90. In embodiments of the present disclosure, the substrates of the present disclosure can be used to further fabricate rare earth permanent magnet materials with excellent properties.

Description

NdFeB substrate

Technical Field

The present disclosure belongs to the field of rare earth permanent magnet materials. In an embodiment of the present disclosure, a neodymium iron boron substrate is provided.

Background Art

In order to improve the coercivity of magnets, it has become a common method in the industry to partially replace Nd in Nd ₂ Fe ₁₄ B with heavy rare earth (HRE = Dy/Tb) to form (Nd, HRE) ₂ Fe ₁₄ B with high magnetocrystalline anisotropy to improve coercivity. Although the addition of heavy rare earth elements can greatly improve the coercivity of magnets, the atomic magnetic moments of Dy/Tb and Fe atoms are arranged in antiparallel, resulting in a sharp decrease in the remanence and magnetic energy product of the magnet. The heavy rare earth grain boundary diffusion method can effectively improve the thermal stability of magnets and is currently the main method for preparing high operating temperature magnets required for permanent magnet motors. The advantage of grain boundary diffusion technology is that the added rare earth elements are mainly distributed at the grain boundaries. Therefore, the heavy rare earth content can be significantly reduced while improving the coercivity and maintaining the remanence, thereby reducing the dependence of high-stability NdFeB magnets on heavy rare earths.

The diffusion depth of heavy rare earth inside the magnet is limited, the magnet thickness is less than 6mm, and the gradient distribution of heavy rare earth causes the coercive force in different regions inside the magnet to also show a gradient distribution law, resulting in inconsistent demagnetization behavior in different regions of the magnet, which worsens the squareness of the magnet demagnetization curve.

In addition, the diffusion depth of heavy rare earth in the magnet is also anisotropic, that is, the diffusion depth obtained by grain boundary diffusion parallel to the easy magnetization direction is greater than the diffusion depth obtained by grain boundary diffusion perpendicular to the easy magnetization direction. In order to ensure the diffusion depth and coercive force improvement, the diffusion depth of heavy rare earth along the orientation direction is less than 6mm, and the diffusion depth along the non-orientation direction is even smaller.

Summary of the invention

In the present disclosure, the knee coercive force _Hk is the reverse magnetic field strength required when the magnetization intensity of the permanent magnetic material drops to 90% of the remanence during the demagnetization process.

In the present disclosure, the intrinsic coercive force H _cj is the reverse magnetic field intensity required to be added to reduce the residual magnetization intensity to zero.

In the present disclosure, the squareness H _k /H _cj is defined as the ratio of the knee coercivity to the intrinsic coercivity.

In the present disclosure, squareness reflects the anti-demagnetization ability of a magnet and affects the working stability of the magnet. The closer the squareness of a magnet is to 1, the less likely the magnet is to lose magnetism and the more stable it is in the working environment.

In this disclosure, "preferred" means one of the alternative embodiments, which is not necessarily preferred over other alternative embodiments.

The present disclosure relates to a NdFeB substrate, which is in a sintered state, wherein the difference in crystal interface area fraction between the substrate parallel to the easy magnetization direction and perpendicular to the easy magnetization direction is ≤1%. In an embodiment of the present disclosure, the NdFeB substrate of the present disclosure is obtained by sintering a powder composition obtained by mixing a raw material NdFeB alloy powder with an alloy powder composed of R and M, wherein the mass ratio of R to M is x:(100-x), R is one or more of Nd and Pr, M is one or a combination of more than two of Cu, Al, Ga, and Zn, and x is the mass fraction of R and 0≤x≤90. In an embodiment of the present disclosure, the substrate of the present disclosure can be used to further manufacture rare earth permanent magnet materials with excellent performance.

The present disclosure provides a NdFeB substrate, which is in a sintered state, wherein the difference between the crystal interface area fractions of the substrate parallel to the easy magnetization direction and perpendicular to the easy magnetization direction is less than 2%.

In some embodiments of the present disclosure, the substrate comprises a bulk agglomerated rare earth-rich phase.

In some embodiments of the present disclosure, the average particle size of the rare earth-rich phase particles is less than 2.4 microns, preferably less than 2.3 microns, preferably less than 2.2 microns, preferably less than 2.1 microns, preferably less than 2.0 microns, preferably less than 1.9 microns.

In some embodiments of the present disclosure, the proportion of rare earth-rich phase particles having a particle size greater than 3 microns is less than 20%, preferably less than 19%, preferably less than 18%, preferably less than 17%, preferably less than 16%, preferably less than 15%, preferably less than 14%, preferably less than 13%, preferably less than 12%, preferably less than 11%, and preferably less than 10%.

In some embodiments of the present disclosure, the NdFeB substrate comprises grain boundaries, the width of the grain boundaries is less than 0.5 micrometers, preferably less than 0.3 micrometers, preferably less than 0.1 micrometers, and the length of the grain boundaries is 0.5 to 6 micrometers.

In some embodiments of the present disclosure, after diffusing the heavy rare earth for 8 mm along the easy magnetization direction perpendicular to the substrate, the squareness of the resulting magnet is greater than or equal to 0.85, preferably ≥0.82, preferably ≥0.83, preferably ≥0.84, preferably ≥0.85, preferably ≥0.86, preferably ≥0.87, preferably ≥0.88, preferably ≥0.89, preferably ≥0.9, preferably ≥0.91, preferably ≥0.92.

In some embodiments of the present disclosure, heavy rare earth is diffused along a direction perpendicular to the easy magnetization direction of the substrate, and the diffusion depth is greater than or equal to 6 mm, preferably greater than or equal to 7 mm, preferably greater than or equal to 8 mm, preferably greater than or equal to 9 mm, preferably greater than or equal to 10 mm.

In some embodiments of the present disclosure, the heavy rare earth is diffused along the easy magnetization direction parallel to the substrate, and the diffusion depth is greater than or equal to 6 mm, preferably greater than or equal to 7 mm, preferably greater than or equal to 8 mm, preferably greater than or equal to 9 mm, preferably greater than or equal to 10 mm.

In some embodiments of the present disclosure, the heavy rare earth is one or both of Dy and Tb.

In some embodiments of the present disclosure, the substrate is obtained by sintering a powder composition obtained by mixing a raw material neodymium iron boron alloy powder with an alloy powder consisting of R and M, wherein the mass ratio of R to M is x:(100-x), R is one or more of Nd and Pr, M is one or a combination of more than two of Cu, Al, Ga, and Zn, x is the mass fraction of R and 0≤x≤90, preferably 80≤x≤90, preferably 86≤x≤88, and preferably x=87%.

The present disclosure provides a method for preparing a NdFeB magnet, the method comprising diffusing a heavy rare earth in a direction parallel to and/or perpendicular to an easy magnetization direction of a substrate.

In other embodiments of the present disclosure, the heavy rare earth may also be one or more selected from the group consisting of gadolinium (Gd), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), yttrium (Y) and scandium (Sc), or a combination of one or more thereof and one or both of Dy and Tb.

In some embodiments of the present disclosure, the diffusion depth is greater than or equal to 6 mm, preferably greater than or equal to 7 mm, preferably greater than or equal to 8 mm, preferably greater than or equal to 9 mm, preferably greater than or equal to 10 mm.

In some embodiments of the present disclosure, the substrate is a sintered NdFeB substrate having a crystal interface area fraction difference of less than 2% parallel to the easy magnetization direction and perpendicular to the easy magnetization direction, preferably a crystal interface area fraction difference of ≤1%, preferably a crystal interface area fraction difference of ≤0.5%, preferably a crystal interface area fraction difference of ≤0.2%.

In some embodiments of the present disclosure, the process also includes sintering a powder composition obtained by mixing a raw material NdFeB alloy powder with an alloy powder consisting of R and M to obtain the substrate, wherein the mass ratio of R to M is x:(100-x), R is one or more of Nd and Pr, M is one or a combination of more than two of Cu, Al, Ga, and Zn, x is the mass fraction of R and 0≤x≤90, preferably 80≤x≤90, preferably 86≤x≤88, and preferably x=87%.

In some embodiments of the present disclosure, the process further includes fully grinding and mixing the raw material NdFeB alloy powder and the alloy powder to obtain a ground powder composition.

In some embodiments of the present disclosure, the milled powder composition is further oriented and formed.

In some embodiments of the present disclosure, sintering is performed directly after the powder composition is oriented into a shape.

In some embodiments of the present disclosure, a static pressure process is not included, and the static pressure process includes but is not limited to oil cooling.

In some embodiments of the present disclosure, after the powder composition is oriented and formed, sintering is directly performed without going through a static pressing process.

In some embodiments of the present disclosure, the grinding method includes but is not limited to grinding using a jet mill.

In some embodiments of the present disclosure, the grinding method includes but is not limited to grinding using a jet mill.

In some embodiments of the present disclosure, the alloy body is subjected to hydrogen cracking to obtain the alloy powder.

In some embodiments of the present disclosure, the alloy body is in the form of a regular or irregular ingot, block, strip, granule or powder.

In some embodiments of the present disclosure, the process includes hydrogen-cracking a raw material NdFeB alloy to obtain a raw material NdFeB alloy powder.

In some embodiments of the present disclosure, the raw material NdFeB alloy is in the form of regular or irregular ingots, blocks, strips, particles or powders.

In some embodiments of the present disclosure, the raw material NdFeB alloy is obtained by sintering.

In some embodiments of the present disclosure, the raw material NdFeB alloy powder is a main phase material.

In some embodiments of the present disclosure, the mass percentage of the main phase material is higher than 90% of the material, preferably higher than 95%, preferably higher than 98%, and preferably the mass percentage of the main phase material is 97.5%-99.5%.

In some embodiments of the present disclosure, the diffusion is a grain boundary diffusion process using a heavy rare earth diffusion source.

In some embodiments of the present disclosure, the grain boundary diffusion treatment is performed by a magnetron sputtering method.

In some embodiments of the present disclosure, the grain boundary diffusion treatment is performed by coating, printing or bonding methods.

In some embodiments of the present disclosure, the squareness of the magnet is greater than 0.8, preferably ≥0.82, preferably ≥0.83, preferably ≥0.84, preferably ≥0.85, preferably ≥0.86, preferably ≥0.87, preferably ≥0.88, preferably ≥0.89, preferably ≥0.9, preferably ≥0.91, preferably ≥0.92.

In some embodiments of the present disclosure, the hydrogen cracking temperature is 250-400°C, preferably 260-350°C, preferably 280-320°C, preferably 300°C.

In some embodiments of the present disclosure, the hydrogen pressure is 0.05-0.15 MPa, preferably 0.07-0.13 MPa, preferably 0.09-0.11 MPa, preferably 0.1 MPa.

In some embodiments of the present disclosure, the hydrogen rupture time is 5-15 h, preferably 7-13 h, preferably 9-11 h, preferably 10 h, preferably 7 h, preferably 5 h.

In some embodiments of the present disclosure, the average particle size of the rare earth alloy hydrogen-cracked powder and the raw material NdFeB alloy powder after grinding is 2-5 μm, preferably 3-5 μm, preferably 3.5-4.5 μm, preferably 4 μm.

In some embodiments of the present disclosure, the mass ratio of the alloy powder to the raw material NdFeB alloy powder is 0.5:100 to 2:100, preferably 1:100 to 1.8:100, preferably 1.4:100 to 1.6:100, preferably 1.5.

In some embodiments of the present disclosure, the sintering temperature is 1000-1100°C, preferably 1030-1090°C, preferably 1040-1080°C, preferably 1045-1070°C, preferably 1065°C, preferably 1060°C, preferably 1050°C.

In some embodiments of the present disclosure, the sintering time is 3-10 hours.

In some embodiments of the present disclosure, the grain boundary diffusion treatment includes a first heat treatment and a second heat treatment, the first heat treatment is performed before the second heat treatment, and the treatment temperature of the first heat treatment is higher than the treatment temperature of the second heat treatment.

In some embodiments of the present disclosure, the first heat treatment is performed at 800-950°C, preferably 850-950°C, preferably 900-940°C, preferably 920-930°C, preferably 925°C.

In some embodiments of the present disclosure, the time of the first heat treatment is 3-40 h, preferably 10-40 h, preferably 14 h-40 h, preferably 14 h, preferably 40 h.

In some embodiments of the present disclosure, the second heat treatment is performed at 450-550°C, preferably 480-530°C, preferably 500-520°C, preferably 510°C.

In some embodiments of the present disclosure, the time of the second heat treatment is 3-10 h, preferably 3-6 h, preferably 3-5 h, preferably 3 h, preferably 5 h.

In some embodiments of the present disclosure, the diffusion amount of heavy rare earth is 0.2%-2%, preferably 0.3%-1.5%, preferably 0.4%-1.2%, preferably 0.5%-1%, preferably 0.5%, 0.75% or 1%.

The present disclosure provides a neodymium iron boron magnet prepared according to the method of the present disclosure.

The present disclosure provides a NdFeB magnet comprising a heavy rare earth diffused along an easy magnetization direction parallel to and/or perpendicular to a substrate.

In some embodiments of the present disclosure, the raw material NdFeB alloy powder is a NdFeB hydrogen-cracked powder obtained by hydrogen-cracked raw material NdFeB alloy.

In some embodiments of the present disclosure, the raw material NdFeB alloy contains Nd, Fe and B, and the raw material NdFeB alloy also contains or does not contain one or more of Pr, Tb, Co, Ca, Cu, Al, and Zr, wherein the mass fraction of Nd is 10%-30%, the mass fraction of Fe is less than or equal to 72%, and the mass fraction of B is less than or equal to 1%.

In some embodiments of the present disclosure, the composition of the raw material NdFeB alloy is Pr _6.95 Nd _22.14 Tb _0.12 Fe _68.95 Co _0.5 Ga _0.13 Cu _0.09 Al _0.06 Zr _0.11 B _0.95 , expressed as mass fraction as a subscript.

The present disclosure provides a powder composition, which comprises a first powder component and a second powder component, wherein the first powder component is an alloy powder composed of R and M, wherein the mass ratio of R to M is x:(100-x), R is one or more of Nd and Pr, M is one or a combination of two or more of Cu, Al, Ga, and Zn, x is the mass fraction of R and 0≤x≤90; and the second powder component is a raw material NdFeB alloy powder.

In some embodiments of the present disclosure, the first powder component is an alloy hydrogen-fragmented powder obtained by hydrogen-fragmenting an alloy body.

In some embodiments of the present disclosure, the second powder component is a NdFeB hydrogen-cracked powder obtained by hydrogen-cracked a raw NdFeB alloy.

In some embodiments of the present disclosure, the powder composition is obtained by hydrogen cracking an alloy body that can obtain the first powder component and a raw material NdFeB alloy that can obtain the second powder component.

In some embodiments of the present disclosure, the composition is obtained by uniformly mixing the first powder component and the second powder component.

In some embodiments of the present disclosure, the mass ratio of the first powder component to the second powder component in the powder composition is 0.5:100 to 2:100, preferably 1:100 to 1.8:100, preferably 1.4:100 to 1.6:100, preferably 1.5.

In some embodiments of the present disclosure, the uniform mixing comprises jet milling the mixture.

In some embodiments of the present disclosure, the average particle size of the first powder component is 3 μm-5 μm, preferably 3.5-4.5 μm, preferably 4 μm.

In some embodiments of the present disclosure, the average particle size of the second powder component is 3 μm-5 μm, preferably 3.5-4.5 μm, preferably 4 μm.

In some embodiments of the present disclosure, the particle size discreteness of the powder composition is no greater than 2, preferably no greater than 1.5, preferably no greater than 1.4, preferably no greater than 1.3, preferably no greater than 1.2, preferably no greater than 1.1, preferably no greater than 1.0, preferably no greater than 0.9, preferably no greater than 0.8, preferably no greater than 0.7, preferably no greater than 0.6, preferably no greater than 0.5, preferably no greater than 0.4, preferably no greater than 0.3, preferably no greater than 0.2, preferably no greater than 0.1.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 (a) Backscattering structure diagram of the substrate perpendicular to the easy magnetization direction before diffusion in Example 1; (b) Backscattering structure diagram of the substrate parallel to the easy magnetization direction before diffusion in Example 1; (c) Backscattering structure diagram of the substrate perpendicular to the easy magnetization direction before diffusion in Example 42; (d) Backscattering structure diagram of the substrate parallel to the easy magnetization direction before diffusion in Example 42.

Figure 2 (a) is an electron probe image of the Tb element in the cross section of the magnet after heavy rare earth diffusion in Example 1, and (b) is an electron probe image of the Tb element in the cross section of the magnet after heavy rare earth diffusion in Example 42.

Example

The present disclosure is further described in detail below in conjunction with the embodiments of the accompanying drawings, but the present disclosure is not limited to these embodiments. The following embodiments are for illustrative purposes only and should not be used to limit the scope of the present disclosure and the claims.

Examples 1-6

The elements Nd and Al are mixed according to the Nd:Al mass ratio in Table 1, and the prepared raw materials are placed in an arc melting furnace and smelted in an argon atmosphere to obtain a rare earth alloy ingot; the rare earth alloy ingot is hydrogen-broken for 7 hours at a temperature of 300°C and a hydrogen pressure of 0.10 MPa; the rare earth alloy hydrogen-broken powder is mixed with a rare earth alloy having a composition of Pr _6.95 Nd _22.14 Tb _0.12 Fe _68.95 Co _0.5 Ga _0.13 Cu _0.09 Al _0.06 Zr _0.11 B The NdFeB hydrogen-crushed powder of _0.95 is mixed evenly in a mass ratio of 1.5:100 and then jet milled. The average particle size of the rare earth alloy hydrogen-crushed powder and the sintered NdFeB hydrogen-crushed powder after jet milling is 4μm; the sintered NdFeB magnetic powder and the rare earth alloy powder after jet milling are oriented and formed, and the pressed green sheet is sintered at 1065℃ for 6h to obtain the NdFeB substrate; the heavy rare earth diffusion source is treated by grain boundary diffusion parallel to the easy magnetization direction of the NdFeB substrate by magnetron sputtering method, the thickness of the heavy rare earth Tb diffusion direction is 6mm, and the diffusion amount of heavy rare earth Tb is 1%. The high-performance NdFeB magnet with excellent squareness is obtained by heat treatment at 925℃ for 14h and at 510℃ for 3h.

Nd:Al mass ratio B _r (kGs) H _cj (kOe) H _k /H _cj Example 1 87:13 14.24 26.20 0.92 Example 2 80:20 14.30 26.35 0.92 Example 3 60:40 14.34 26.50 0.93 Example 4 30:70 14.20 26.10 0.93 Example 5 10:90 14.19 25.94 0.92 Example 6 1:99 14.15 25.82 0.92

Table 1

Examples 7-12

The elements Nd and Al are mixed according to the Nd:Al mass ratio in Table 2, and the prepared raw materials are placed in an arc melting furnace and smelted in an argon atmosphere to obtain a rare earth alloy ingot; the rare earth alloy ingot is hydrogen-broken for 7 hours at a temperature of 300°C and a hydrogen pressure of 0.10 MPa; the rare earth alloy hydrogen-broken powder is mixed with a rare earth alloy having a composition of Pr _6.95 Nd _22.14 Tb _0.12 Fe _68.95 Co _0.5 Ga _0.13 Cu _0.09 Al _0.06 Zr _0.11 B _0.95 NdFeB hydrogen-crushed powder was mixed evenly at a mass ratio of 1.5:100 and then jet milled. The average particle size of the rare earth alloy hydrogen-crushed powder and sintered NdFeB hydrogen-crushed powder after jet milling was 4μm. The sintered NdFeB magnetic powder and rare earth alloy powder after jet milling were oriented and formed into a green compact and sintered at 1065℃ for 6h to obtain a NdFeB substrate. The heavy rare earth diffusion source was treated by magnetron sputtering along the grain boundary perpendicular to the easy magnetization direction of the NdFeB substrate. The thickness of the heavy rare earth Tb diffusion direction was 8mm and the diffusion amount of the heavy rare earth Tb was 1%. The high-performance NdFeB magnet with excellent squareness was obtained by heat treatment at 925℃ for 40h and at 510℃ for 3h.

Nd:Al mass ratio B _r (kGs) H _cj (kOe) H _k /H _cj Example 7 87:13 14.32 25.85 0.92 Example 8 80:20 14.38 25.97 0.93 Example 9 60:40 14.31 25.73 0.93 Example 10 30:70 14.23 25.62 0.92 Embodiment 11 10:90 14.19 25.50 0.92 Example 12 1:99 14.14 25.42 0.92

Table 2

Examples 13-16

The elements Nd and Al are mixed in a ratio of 87:13 Nd ₈₇ Al ₁₃ , and the prepared raw materials are placed in an arc melting furnace and smelted in an argon atmosphere to obtain a rare earth alloy ingot; the rare earth alloy ingot is hydrogen-broken for 7 hours at a temperature of 300°C and a hydrogen pressure of 0.10 MPa; the rare earth alloy hydrogen-broken powder is mixed with a rare earth alloy having a composition of Pr _6.95 Nd _22.14 Tb _0.12 Fe _68.95 Co _0.5 Ga _0.13 Cu _0.09 Al _0.06 Zr _0.11 B _0.95 NdFeB hydrogen-crushed powder was mixed uniformly at a mass ratio of 1.5:100 and then jet milled. The average particle size of the rare earth alloy hydrogen-crushed powder and sintered NdFeB hydrogen-crushed powder after jet milling was 4μm. The sintered NdFeB magnetic powder and rare earth alloy powder after jet milling were oriented and formed into a green compact and sintered at 1065℃ for 6h to obtain a NdFeB substrate. The heavy rare earth diffusion source was treated by grain boundary diffusion perpendicular to the easy magnetization direction of the NdFeB substrate by magnetron sputtering. The thickness of the heavy rare earth Tb diffusion direction is shown in Table 3, and the diffusion amount of heavy rare earth Tb is 1%. After heat treatment at 925℃ for 40h and at 510℃ for 3h, a high-performance NdFeB magnet with excellent squareness was obtained.

thickness B _r (kGs) H _cj (kOe) H _k /H _cj Example 13 4mm 14.45 26.67 0.93 Embodiment 14 6mm 14.41 26.45 0.94 Example 7 8mm 14.32 25.85 0.92 Embodiment 15 10mm 14.19 24.84 0.92 Example 16 11mm 14.12 24.49 0.92

Table 3

Examples 17-21

The elements Nd and Al are mixed in a ratio of 87:13 Nd ₈₇ Al ₁₃ , and the prepared raw materials are placed in an arc melting furnace and smelted in an argon atmosphere to obtain a rare earth alloy ingot; the rare earth alloy ingot is hydrogen-broken for 7 hours at a temperature of 300°C and a hydrogen pressure of 0.10 MPa; the rare earth alloy hydrogen-broken powder is mixed with a rare earth alloy having a composition of Pr _6.95 Nd _22.14 Tb _0.12 Fe _68.95 Co _0.5 Ga _0.13 Cu _0.09 Al _0.06 Zr _0.11 B _0.95 NdFeB hydrogen-crushed powder was mixed uniformly at a mass ratio of 1.5:100 and then jet milled. The average particle size of the rare earth alloy hydrogen-crushed powder and sintered NdFeB hydrogen-crushed powder after jet milling was 4μm. The sintered NdFeB magnetic powder and rare earth alloy powder after jet milling were oriented and formed into a green compact and sintered at 1065℃ for 6h to obtain a NdFeB substrate. The heavy rare earth diffusion source was treated by grain boundary diffusion parallel to the easy magnetization direction of the NdFeB substrate by magnetron sputtering. The thickness of the heavy rare earth Tb diffusion direction is shown in Table 4, and the diffusion amount of heavy rare earth Tb is 1%. After heat treatment at 925℃ for 40h and at 510℃ for 3h, a high-performance NdFeB magnet with excellent squareness was obtained.

thickness B _r (kGs) H _cj (kOe) H _k /H _cj Embodiment 17 4mm 14.42 26.75 0.94 Embodiment 18 6mm 14.24 26.20 0.92 Embodiment 19 8mm 14.18 25.85 0.92 Embodiment 20 10mm 14.25 25.64 0.92 Embodiment 21 11mm 14.12 24.56 0.92

Table 4

Examples 22-26

The elements Pr and Cu are placed in an arc melting furnace according to the Pr:Cu mass ratio in Table 5, and the prepared raw materials are melted in an argon atmosphere to obtain a rare earth alloy ingot; the rare earth alloy ingot is hydrogen-broken for 5 hours at a temperature of 350°C and a hydrogen pressure of 0.15MPa; the rare earth alloy hydrogen-broken powder and the NdFeB hydrogen-broken powder are mixed evenly at a mass ratio of 1:100 and then air-milled, and the average particle size of the rare earth alloy hydrogen-broken powder and the sintered NdFeB hydrogen-broken powder after air-milling is 3μm; the sintered NdFeB magnetic powder and the rare earth alloy powder after air-milling are oriented and formed, and the pressed blank is sintered at 1060°C for 5 hours to obtain a NdFeB substrate; the heavy rare earth diffusion source is treated by a coating method along the grain boundary diffusion parallel to the easy magnetization direction of the NdFeB substrate, the thickness of the heavy rare earth Dy diffusion direction is 10mm, and the diffusion amount of the heavy rare earth Dy is 0.75%. By heat treating at 925°C for 14h and at 510°C for 3h, a high performance NdFeB magnet with excellent squareness was obtained.

Pr:Cu mass ratio B _r (kGs) H _cj (kOe) H _k /H _cj Example 22 90:10 14.30 22.88 0.92 Embodiment 23 70:30 14.38 22.52 0.93 Embodiment 24 50:50 14.35 22.40 0.93 Embodiment 25 30:70 14.38 22.32 0.92 Embodiment 26 10:90 14.40 22.12 0.92

Table 5

Examples 27-31

The elements Nd and Zn are placed in an arc melting furnace according to the Nd:Zn mass ratio in Table 6, and the prepared raw materials are placed in an arc melting furnace and melted in an argon atmosphere to obtain a rare earth alloy ingot; the rare earth alloy ingot is hydrogen-broken for 10 hours under the conditions of a temperature of 250°C and a hydrogen pressure of 0.08MPa; the rare earth alloy hydrogen-broken powder and the NdFeB hydrogen-broken powder are mixed evenly in a mass ratio of 2:100 and then air-milled, and the average particle size of the rare earth alloy hydrogen-broken powder and the sintered NdFeB hydrogen-broken powder after air-milling is 5μm; the sintered NdFeB magnetic powder and the rare earth alloy powder after air-milling are oriented and formed, and the pressed blank is sintered at 1050°C for 10 hours to obtain a NdFeB substrate; the heavy rare earth diffusion source is subjected to grain boundary diffusion treatment perpendicular to the easy magnetization direction of the NdFeB substrate by a magnetron sputtering method, the thickness of the heavy rare earth Dy diffusion direction is 8mm, and the diffusion amount of the heavy rare earth Dy is 0.5%. By heat treating at 925°C for 10 hours and at 510°C for 5 hours, a high performance NdFeB magnet with excellent squareness was obtained.

Nd:Zn mass ratio B _r (kGs) H _cj (kOe) H _k /H _cj Embodiment 27 70:30 14.32 20.05 0.92 Embodiment 28 90:10 14.34 21.12 0.93 Embodiment 29 50:50 14.30 20.82 0.94 Embodiment 30 30:70 14.24 20.64 0.92 Embodiment 31 10:90 14.26 20.50 0.92

Table 6

Examples 32-36

The elements Pr and Cu are placed in an arc melting furnace at a mass ratio of Pr:Cu of 80:20, and the prepared raw materials are melted in an argon atmosphere to obtain a rare earth alloy ingot; the rare earth alloy ingot is hydrogen-broken for 5 hours at a temperature of 350°C and a hydrogen pressure of 0.15MPa; the rare earth alloy hydrogen-broken powder and the NdFeB hydrogen-broken powder are mixed evenly at a mass ratio of 1:100 and then air-milled, and the average particle size of the rare earth alloy hydrogen-broken powder and the sintered NdFeB hydrogen-broken powder after air-milling is 3μm; the sintered NdFeB magnetic powder and the rare earth alloy powder after air-milling are oriented and formed, and the pressed blank is sintered at 1060°C for 5 hours to obtain a NdFeB substrate; the heavy rare earth diffusion source is treated by a coating method along the grain boundary diffusion parallel to the easy magnetization direction of the NdFeB substrate, the thickness of the heavy rare earth Dy diffusion direction is shown in Table 7, and the heavy rare earth Dy diffusion amount is 0.75%. By heat treating at 925°C for 14h and at 510°C for 3h, a high performance NdFeB magnet with excellent squareness was obtained.

thickness B _r (kGs) H _cj (kOe) H _k /H _cj Embodiment 32 4mm 14.18 23.36 0.94 Embodiment 33 6mm 14.24 23.22 0.94 Embodiment 34 8mm 14.20 23.02 0.93 Embodiment 35 10mm 14.28 22.68 0.92 Embodiment 36 12mm 14.24 22.24 0.92

Table 7

Examples 37-41

The elements Nd and Zn are placed in an arc melting furnace according to a Nd:Zn mass ratio of 80:20, and the prepared raw materials are placed in an arc melting furnace and melted in an argon atmosphere to obtain a rare earth alloy ingot; the rare earth alloy ingot is hydrogen-broken for 10 hours at a temperature of 250°C and a hydrogen pressure of 0.08MPa; the rare earth alloy hydrogen-broken powder and the NdFeB hydrogen-broken powder are mixed evenly at a mass ratio of 2:100 and then air-milled, and the average particle size of the rare earth alloy hydrogen-broken powder and the sintered NdFeB hydrogen-broken powder after air-milling is 5μm; the sintered NdFeB magnetic powder and the rare earth alloy powder after air-milling are oriented and formed, and the pressed blank is sintered at 1050°C for 10 hours to obtain a NdFeB substrate; the heavy rare earth diffusion source is subjected to grain boundary diffusion treatment perpendicular to the easy magnetization direction of the NdFeB substrate by a magnetron sputtering method, and the thickness of the heavy rare earth Dy diffusion direction is shown in Table 8, and the diffusion amount of the heavy rare earth Dy is 0.5%. By heat treating at 925°C for 10 hours and at 510°C for 5 hours, a high performance NdFeB magnet with excellent squareness was obtained.

thickness B _r (kGs) H _cj (kOe) H _k /H _cj Embodiment 37 4mm 14.28 20.81 0.93 Embodiment 38 6mm 14.24 20.40 0.92 Embodiment 39 8mm 14.32 20.05 0.92 Embodiment 40 10mm 14.30 18.45 0.92 Embodiment 41 11mm 14.28 17.68 0.91

Table 8

Embodiment 42

The sintered NdFeB magnetic powder (components are Pr _6.95 Nd _22.14 Tb _0.12 Fe _68.95 Co _0.5 Ga _0.13 Cu _0.09 Al _0.06 Zr _0.11 B _0.95 ) after jet milling was oriented and formed into a green compact, which was sintered at 1065℃ for 6h to obtain a NdFeB substrate. The heavy rare earth diffusion source was diffused along the grain boundary parallel to the easy magnetization direction of the NdFeB substrate by magnetron sputtering, and the thickness of the heavy rare earth Tb diffusion direction was 6mm, and the diffusion amount of the heavy rare earth Tb was 1%. The NdFeB magnet was obtained by heat treatment at 925℃ for 14h and at 510℃ for 3h.

Embodiment 43

The sintered NdFeB magnetic powder (components are Pr _6.95 Nd _22.14 Tb _0.12 Fe _68.95 Co _0.5 Ga _0.13 Cu _0.09 Al _0.06 Zr _0.11 B _0.95 ) after jet milling was oriented and formed into a green compact, which was sintered at 1065℃ for 6h to obtain a NdFeB substrate. The heavy rare earth diffusion source was diffused along the grain boundary perpendicular to the easy magnetization direction of the NdFeB substrate by magnetron sputtering, and the thickness of the heavy rare earth Tb diffusion direction was 8mm, and the diffusion amount of the heavy rare earth Tb was 1%. The NdFeB magnet was obtained by heat treatment at 925℃ for 40h and at 510℃ for 3h.

Embodiment 44

The sintered NdFeB magnetic powder (components are Pr _6.95 Nd _22.14 Tb _0.12 Fe _68.95 Co _0.5 Ga _0.13 Cu _0.09 Al _0.06 Zr _0.11 B _0.95 ) after jet milling was oriented and formed into a green compact, which was sintered at 1065℃ for 6h to obtain a NdFeB substrate. The heavy rare earth diffusion source was diffused along the grain boundary perpendicular to the easy magnetization direction of the NdFeB substrate by magnetron sputtering, and the thickness of the heavy rare earth Tb diffusion direction was 10mm, and the diffusion amount of the heavy rare earth Tb was 1%. The NdFeB magnet was obtained by heat treatment at 925℃ for 40h and at 510℃ for 3h.

Br(kGs) Hcj(kOe) Hk/Hcj Example 1 14.24 26.20 0.92 Example 7 14.32 25.85 0.92 Embodiment 15 14.19 24.84 0.92 Embodiment 42 14.40 24.14 0.90 Embodiment 43 14.31 24.26 0.84 Embodiment 44 14.39 21.31 0.77

Table 9

Comparison of Figures 1(a)-(d) shows that after the introduction of R _x M _100-x alloy, the difference in the content of grain boundary phase in different directions of the substrate is reduced, which effectively improves the anisotropy of the distribution of grain boundary phase in the substrate, and forms a continuous narrow grain boundary inside the substrate. The results of the electron probe (Figure 2) show that the Tb element has a deeper diffusion depth in the substrate introduced with the R _x M _100-x alloy, the accumulation of heavy rare earth on the surface is significantly reduced, and the concentration gradient inside the magnet is slowed down. Combined with the magnetic performance data, the NdFeB diffusion magnet after the introduction of the R _x M _100-x alloy has a better squareness. For a 10 mm thick substrate, the squareness of the magnet can still reach 0.92 after the heavy rare earth Tb is diffused perpendicular to the easy magnetization direction, which is significantly better than 0.77 in Example 83.

By comparing the magnetic property data of the embodiment and the comparative example, it can be seen that by introducing R _x M _100-x to regulate the distribution morphology of the grain boundary phase of the substrate and the content in different directions, the squareness of the diffused magnet is effectively improved, the accumulation of Tb elements on the surface of the magnet is reduced, and the utilization rate of heavy rare earth is effectively improved.

Examples 45-47

The elements Nd and Al are mixed in a mass ratio of Nd:Al of 87:13, and the prepared raw materials are placed in an arc melting furnace and melted in an argon atmosphere to obtain a rare earth alloy ingot; the rare earth alloy ingot is hydrogen-broken for 7 hours at a temperature of 300°C and a hydrogen pressure of 0.10 MPa; the rare earth alloy hydrogen-broken powder and the NdFeB hydrogen-broken powder having the composition shown in Table 10 are mixed evenly in a mass ratio of 1.5:100 and then air-milled, and the average particle size of the rare earth alloy hydrogen-broken powder and the sintered NdFeB hydrogen-broken powder after air-milling is 4 μm; the sintered NdFeB magnetic powder after air-milling and the rare earth alloy powder are oriented and formed, and the pressed green sheet is sintered at a temperature of 1065°C for 6 hours to obtain a NdFeB substrate; the heavy rare earth diffusion source is subjected to grain boundary diffusion treatment parallel to the easy magnetization direction of the NdFeB substrate by a magnetron sputtering method, the thickness of the heavy rare earth Tb diffusion direction is 6 mm, and the diffusion amount of the heavy rare earth Tb is 1%. By heat treating at 925°C for 14h and at 510°C for 3h, a high performance NdFeB magnet with excellent squareness was obtained.

Table 10

Examples 48-49

The elements Nd and Al are mixed in a mass ratio of 87:13, and the prepared raw materials are placed in an arc melting furnace, and smelted in an argon atmosphere to obtain a rare earth alloy ingot; the rare earth alloy ingot is hydrogen-broken for 7 hours at a temperature of 300°C and a hydrogen pressure of 0.10 MPa; the rare earth alloy hydrogen-broken powder is mixed with a rare earth alloy having a composition of Pr _6.95 Nd _22.14 Tb _0.12 Fe _68.95 Co _0.5 Ga _0.13 Cu _0.09 Al _0.06 Zr _0.11 B The NdFeB hydrogen-crushed powder of _0.95 was mixed evenly according to the mass ratio in Table 11 and then jet milled. The average particle size of the rare earth alloy hydrogen-crushed powder and the sintered NdFeB hydrogen-crushed powder after jet milling was 4μm. The sintered NdFeB magnetic powder and the rare earth alloy powder after jet milling were oriented and formed, and the pressed green sheet was sintered at 1065℃ for 6h to obtain the NdFeB substrate. The heavy rare earth diffusion source was treated by magnetron sputtering along the grain boundary parallel to the easy magnetization direction of the NdFeB substrate. The thickness of the heavy rare earth Tb diffusion direction was 6mm, and the diffusion amount of the heavy rare earth Tb was 1%. The high-performance NdFeB magnet with excellent squareness was obtained by heat treatment at 925℃ for 14h and at 510℃ for 3h.

Quality Ratio B _r (kGs) H _cj (kOe) H _k /H _cj Example 1 1.5:100 14.24 26.20 0.92 Embodiment 48 0.5:100 14.35 25.64 0.91 Embodiment 49 1:100 14.30 25.96 0.92

Table 11

The average particle size and particle size dispersion of the powder compositions obtained in Examples 1-49 were measured to obtain the measurement results in Table 12. The difference in the crystal interface area fraction parallel to the easy magnetization direction and perpendicular to the easy magnetization direction, the average particle size of the rare earth-rich phase particles, the proportion of the rare earth-rich phase particles with a particle size greater than 3 μm to all the rare earth-rich phase particles, the grain boundary width, and the grain boundary length of the substrates obtained in Examples 1-49 were measured to obtain the measurement results in Tables 13-14.

Table 12

Table 13

Table 14

The above embodiments are only for illustrating the technical concept and features of the present disclosure, and their purpose is to enable those skilled in the art to understand the content of the present disclosure and implement it accordingly, and they cannot be used to limit the protection scope of the present disclosure. Any equivalent changes or modifications made according to the spirit of the present disclosure should be included in the protection scope of the present disclosure.

Claims (10)

1. And the neodymium iron boron substrate is in a sintering state, and the area fraction of the grain boundary of the substrate parallel to the easy magnetization direction and perpendicular to the easy magnetization direction is less than 2%.

2. The neodymium iron boron substrate of claim 1, comprising a bulk agglomerated rare earth-rich phase.

3. The neodymium iron boron substrate of claim 2, wherein said rare earth-rich phase particles have an average particle size of less than 2.4 microns.

4. The neodymium iron boron substrate of claim 2, wherein the proportion of rare earth-rich phase particles having a particle size greater than 3 microns is less than 20% of the total rare earth-rich phase particles.

5. The neodymium iron boron substrate of claim 1, comprising grain boundaries having a width of less than 0.5 microns and a length of from 0.5 to 6 microns.

6. The neodymium iron boron substrate of claim 1, wherein the square degree of the obtained magnet is greater than or equal to 0.85 after heavy rare earth is diffused for 8 millimeters along the direction perpendicular to the easy magnetization direction of the substrate.

7. The neodymium iron boron substrate of claim 1, wherein heavy rare earth is diffused along a direction perpendicular to the easy magnetization direction of the substrate, and the diffusion depth is greater than or equal to 8mm.

8. The neodymium iron boron substrate of claim 1, wherein heavy rare earth is diffused along a direction parallel to the easy magnetization direction of the substrate, and the diffusion depth is greater than or equal to 8mm.

9. The neodymium iron boron substrate of claims 6-8, wherein the heavy rare earth is one or both of Dy and Tb.

10. The neodymium iron boron substrate according to claim 1, which is obtained by sintering a powder composition obtained by mixing a raw material neodymium iron boron alloy powder with an alloy powder composed of R and M, wherein the mass ratio of R to M is x (100-x), R is one or more of Nd and Pr, M is a combination of one or more than two of Cu, al, ga, zn, x is the mass fraction of R and x is 0.ltoreq.90.