Patent Application
20240153681
The invention relates to a neodymium-iron-boron magnet material, a preparation method and use thereof.
Permanent magnet materials have been developed as key materials for supporting electronic devices. R-T-B based permanent magnet materials have the highest magnetic properties and are used in many fields such as voice coil motors for hard drives, motors for electric vehicles and motors for industry equipment.
How to further improve the comprehensive performance of R-T-B based permanent magnet materials is currently a research direction in this field. For example, Chinese patent document CN110993233A discloses a R-T-B based permanent magnet material, wherein by increasing the content of X (Al\Cu\Ga) and adjusting the content of rare earths to change the ratio of Fe and B, a 6:13:1 phase can be formed with only the conventional content of B, a magnet material with excellent magnetic properties is achieved.
Furthermore, for example, Chinese patent document CN111180159A also discloses a neodymium-iron-boron permanent magnet material, and the specific examples in this patent disclose a magnet material having the following components and structure of: 29 wt % of Nd, 0.1 wt % of Tb, 0.4 wt % of Dy, 0.4 wt % of Cu, 0.5 wt % of Al, 0.9 wt % of Co, 1 wt % of B, 0.25 wt % of Nb, and 67.45 wt % of Fe; and a specific mass proportion of a Tb0.4Dy2.5—Al0.59—Nd89.6—Cu1.4—Co5.1 phase is generated in the intergranular region rare-earth rich phase.
The above formulas are based on the improvement of high Cu and high Al magnet materials, which is mainly because the addition of Cu can effectively improve the coercivity of neodymium-iron-boron magnet materials. However, the enrichment of too much Cu (such as 0.35 wt % or more) at the grain boundary will lead to the formation of microcracks in the magnet after sintering, thus reducing the compactness and strength of the magnet. In the prior art, the addition of Al is generally used (such as Chinese patent document CN110993234A) to solve the above-mentioned defects. However, the properties such as coercivity and remanence of the magnet materials with the above formulas still cannot reach the theoretical values of the permanent magnet materials.
How to further optimize the formula of magnet materials to obtain a neodymium-iron-boron magnet material with higher comprehensive performance of coercivity and remanence is a technical problem that needs to be solved urgently.
In order to overcome the defect relating low magnetic properties of the neodymium-iron-boron magnet materials containing Al and Cu in the prior art, the invention provides a neodymium-iron-boron magnet material, a preparation method and use thereof. In the present invention, by optimizing the formula of the neodymium-iron-boron magnet material, the coercivity of the neodymium-iron-boron magnet material prepared is improved while maintaining higher levels of remanence and squareness.
The invention solves the above-mentioned technical problem mainly through the following technical solutions.
The invention provides a neodymium-iron-boron magnet material, comprising the following components of:
In the invention, the content of R is preferably 29-32.5 wt %, such as 29.3 wt %, 29.6 wt %, 29.7 wt %, 30.6 wt %, 30.7 wt %, 31.3 wt %, 31.5 wt %, 31.9 wt %, 32 wt %, 32.1 wt % or 32.3 wt %, wherein wt % is the mass percentage of R in the total mass of the neodymium-iron-boron magnet material.
In the invention, the content of Nd is preferably 27-31 wt %, such as 27.5 wt %, 28.3 wt %, 28.9 wt %, 29.1 wt %, 29.3 wt %, 29.5 wt %, 29.7 wt %, 29.8 wt %, 30.2 wt %, 30.5 wt % or 30.7 wt. %, wherein wt % is the mass percentage of Nd in the total mass of the neodymium-iron-boron magnet material.
In the present invention, the neodymium-iron-boron magnet material can further comprise RH, wherein the RH is a heavy rare earth element.
Wherein, the RH has the conventional content in this field, and is preferably 0.5-2.5 wt %, such as 0.6 wt %, 0.9 wt %, 1 wt %, 1.2 wt %, 1.4 wt %, 1.5 wt %, 1.7 wt %, 2 wt %, 2.3 wt %, wherein wt % is the mass percentage of RH in the total mass of the neodymium-iron-boron magnet material.
Wherein, the RH is preferably Dy and/or Tb.
When the RH comprises Dy, the content of Dy is preferably 0.2-2.5 wt %, such as 0.2 wt %, 0.9 wt %, 1.4 wt %, 1.5 wt %, 1.7 wt % or 2.3 wt %, wherein wt % is the mass percentage of Dy in the total mass of the neodymium-iron-boron magnet material.
When the RH comprises Tb, the content of Tb is preferably 0.5-2.5 wt %, such as 0.6 wt %, 0.8 wt %, 1.2 wt % or 2 wt %, wherein wt % is the mass percentage of Tb in the total mass of the neodymium-iron-boron magnet material.
In the invention, the value of Nd/Pr is preferably 60-400, such as 98, 135, 275, 283, 289, 291, 295, 297, 298, 302, 305 or 307. Those skilled in the field know that the Nd/Pr refers to the ratio of the content of Nd to the content of Pr.
In the invention, the content of Pr is preferably 0.1-0.3 wt %, such as 0.2 wt %, wherein wt % is the mass percentage of Pr in the total mass of the neodymium-iron-boron magnet material.
In the invention, the content of Al is preferably 0.45-1.15 wt %, such as 0.46 wt %, 0.61 wt %, 0.65 wt %, or 0.7 wt %, wherein wt % is the mass percentage of Al in the total mass of the neodymium-iron-boron magnet material.
In the invention, the content of Cu is preferably 0.35-0.45 wt %, such as 0.36 wt %, 0.37 wt %, 0.38 wt %, 0.39 wt %, 0.4 wt % or 0.42 wt %, wherein wt % is the mass percentage of Cu in the total mass of the neodymium-iron-boron magnet material.
In the invention, the content of Co is preferably 0.9-2.5 wt %, such as 1 wt %, 1.1 wt %, 1.2 wt %, 1.3 wt %, 1.4 wt %, or 1.5 wt %, wherein wt % is the mass percentage of Co in the total mass of the neodymium-iron-boron magnet material.
In the invention, the content of Nb is preferably 0.25-0.55 wt %, such as 0.26 wt %, 0.3 wt % or 0.35 wt %, wherein wt % is the mass percentage of Nb in the total mass of the neodymium-iron-boron magnet material.
In the invention, the content of B is preferably 0.98-1.05 wt %, such as 0.99 wt %, 1 wt %, 1.01 wt %, 1.02 wt % or 1.04 wt %, wherein wt % is the mass percentage of B in the total mass of the neodymium-iron-boron magnet material.
In the invention, the content of Fe is preferably 63-68 wt %, such as 63.71 wt %, 63.84 wt %, 64.17 wt %, 64.75 wt %, 64.82 wt %, 64.83 wt %, 65.25 wt. %, 65.61 wt %, 65.78 wt %, 66.23 wt %, 66.84 wt %, 67.04 wt %, 67.24 wt %, 67.34 wt % or 67.35 wt %, wherein wt % is the mass percentage of Fe in the total mass of the neodymium-iron-boron magnet material.
In the invention, the neodymium-iron-boron magnet material preferably comprises a NdxPryCoz phase, wherein based on the total moles of the Nd, the Pr and the Co in the NdxPryCoz phase being 100%, x is 50-57%, y is 3-7%, and z is 39-46%; the NdxPryCoz phase is located in a grain boundary phase, wherein the ratio of the area of the NdxPryCoz phase to the total area of the grain boundary phase is preferably 3-7%, and more preferably 4.5-5.5%, such as 4.9%, 5%, 5.1%, 5.2%, or 5.3%. The area of the NdxPryCoz phase or the total area of the grain boundary phase respectively refers to the area thereof occupied in the vertical orientation plane of the detected neodymium-iron-boron magnet material.
Wherein, the x is, for example, 51%, 52%, 53%, 54%, 55% or 56%.
Wherein, the y is, for example, 4%, 5%, or 6%.
Wherein, the z is, for example, 40%, 41%, 42%, 43%, 44% or 45%.
Wherein, the x (y or z) refers to the percentage of the moles of the Nd (the Pr or the Co) in the NdxPryCoz phase to the total moles of all the elements in the NdxPryCoz phase.
In the invention, the grain boundary phase can be a commonly understood meaning in this field, which generally refers to the region formed by the two-particle grain boundary phase and the intergranular triangular region. The two-particle grain boundary phase is generally a grain boundary phase between two main phase particles.
The inventors found that the NdxPryCoz phase with a specific content is formed in the neodymium-iron-boron magnet material through the coordination between the above specific elements. The existence of this phase reduces the dissolution temperature of the grain boundary phase, which can significantly increase the fluidity of the grain boundary phase and improve the distribution of the grain boundary phase, thereby greatly improving the coercivity of the neodymium-iron-boron material by enhancing the demagnetic coupling ability of the grain boundary phase.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 29.7 wt % of Nd, 0.1 wt % of Pr, 1.7 wt % of Dy, 0.61 wt % of Al, 0.4 wt % of Cu, 1 wt % of Co, 0.25 wt % of Nb, 0.99 wt % of B and 65.25 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet materials comprise a Nd55Pr4Co41 phase in the grain boundary phase; and the ratio of the area of the Nd55Pr4Co41 phase to the total area of the grain boundary phase is 5.1%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 29.8 wt % of Nd, 0.1 wt % of Pr, 1.4 wt % of Dy, 0.46 wt % of Al, 0.38 wt % of Cu, 1 wt % of Co, 0.25 wt % of Nb, 1 wt % of B and 65.61 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet materials comprise a Nd56Pr4Co40 phase in the grain boundary phase; and the ratio of the area of the Nd56Pr4Co40 phase to the total area of the grain boundary phase is 5.2%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 30.2 wt % of Nd, 0.1 wt % of Pr, 1.7 wt % of Dy, 0.61 wt % of Al, 0.38 wt % of Cu, 0.9 wt % of Co, 0.3 wt % of Nb, 0.99 wt % of B and 64.82 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet materials comprise a Nd55Pr5Co40 phase in the grain boundary phase; and the ratio of the area of the Nd55Pr5Co40 phase to the total area of the grain boundary phase is 5%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 29.3 wt % of Nd, 0.3 wt % of Pr, 2.3 wt % of Dy, 0.61 wt % of Al, 0.39 wt % of Cu, 1 wt % of Co, 0.26 wt % of Nb, 1.01 wt % of B and 64.83 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd53Pr6Co41 phase in the grain boundary phase; and the ratio of the area of the Nd53Pr6Co41 phase to the total area of the grain boundary phase is 5.2%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 30.7 wt % of Nd, 0.1 wt % of Pr, 1.5 wt % of Dy, 1.15 wt % of Al, 0.37 wt % of Cu, 1.1 wt % of Co, 0.25 wt % of Nb, 0.99 wt % of B and 63.84 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd53Pr4Co43 phase in the grain boundary phase; and the ratio of the area of the Nd53Pr4Co43 phase to the total area of the grain boundary phase is 5.1%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 28.9 wt % of Nd, 0.1 wt % of Pr, 0.6 wt % of Tb, 0.46 wt % of Al, 0.36 wt % of Cu, 1 wt % of Co, 0.26 wt % of Nb, 0.98 wt % of B and 67.34 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd56Pr4Co40 phase in the grain boundary phase; and the ratio of the area of the Nd56Pr4Co40 phase to the total area of the grain boundary phase is 4.9%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 28.3 wt % of Nd, 0.1 wt % of Pr, 1.2 wt % of Tb, 0.45 wt % of Al, 0.35 wt % of Cu, 1 wt % of Co, 0.26 wt % of Nb, 0.99 wt % of B and 67.35 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd56Pr4Co40 phase in the grain boundary phase; and the ratio of the area of the Nd56Pr4Co40 phase to the total area of the grain boundary phase is 5.2%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 27 wt % of Nd, 0.2 wt % of Pr, 2.5 wt % of Tb, 0.45 wt % of Al, 0.36 wt % of Cu, 1 wt % of Co, 0.26 wt % of Nb, 0.99 wt % of B and 67.24 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd54Pr5Co41 phase in the grain boundary phase; and the ratio of the area of the Nd54Pr5Co41 phase to the total area of the grain boundary phase is 5.3%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 27.5 wt % of Nd, 0.1 wt % of Pr, 2 wt % of Tb, 0.45 wt % of Al, 0.36 wt % of Cu, 1.3 wt % of Co, 0.26 wt % of Nb, 0.99 wt % of B and 67.04 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd55Pr4Co41 phase in the grain boundary phase; and the ratio of the area of the Nd55Pr4Co41 phase to the total area of the grain boundary phase is 4.9%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 28.3 wt % of Nd, 0.1 wt % of Pr, 0.9 wt % of Dy, 0.7 wt % of Al, 0.42 wt % of Cu, 1.5 wt % of Co, 0.25 wt % of Nb, 0.99 wt % of B and 66.84 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd54Pr4Co42 phase in the grain boundary phase; and the ratio of the area of the Nd54Pr4Co42 phase to the total area of the grain boundary phase is 5.2%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 30.5 wt % of Nd, 0.1 wt % of Pr, 1.5 wt % of Dy, 0.65 wt % of Al, 0.45 wt % of Cu, 1.4 wt % of Co, 0.25 wt % of Nb, 0.98 wt % of B and 64.17 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd55Pr4Co41 phase in the grain boundary phase; and the ratio of the area of the Nd55Pr4Co41 phase to the total area of the grain boundary phase is 5.1%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 29.7 wt % of Nd, 0.1 wt % of Pr, 1.7 wt % of Dy, 0.61 wt % of Al, 0.4 wt % of Cu, 2.5 wt % of Co, 0.26 wt % of Nb, 1.02 wt % of B and 63.71 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd54Pr5Co41 phase in the grain boundary phase; and the ratio of the area of the Nd54Pr5Co41 phase to the total area of the grain boundary phase is 5.1%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 29.7 wt % of Nd, 0.1 wt % of Pr, 1.7 wt % of Dy, 0.61 wt % of Al, 0.4 wt % of Cu, 1.5 wt % of Co, 0.25 wt % of Nb, 0.99 wt % of B and 64.75 wt % of Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd51Pr4Co45 phase in the grain boundary phase; and the ratio of the area of the Nd51Pr4Co45 phase to the total area of the grain boundary phase is 5.2%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 29.1 wt % of Nd, 0.1 wt % of Pr, 1.5 wt % of Tb, 0.46 wt % of Al, 0.37 wt % of Cu, 0.9 wt % of Co, 0.35 wt % of Nb, 0.99 wt % of B and 66.23 wt % Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd 52 Pr5Co43 phase in the grain boundary phase; and the ratio of the area of the Nd52Pr5Co43 phase to the total area of the grain boundary phase is 5.2%.
In a preferable example of the invention, the neodymium-iron-boron magnet material comprises the following components of: 29.5 wt % of Nd, 0.1 wt % of Pr, 0.2 wt % of Dy, 0.8 wt % of Tb, 0.46 wt % of Al, 0.37 wt % of Cu, 1.2 wt % of Co, 0.55 wt % of Nb, 1.04 wt % of B and 65.78 wt % Fe, wherein wt % is a mass percentage of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises a Nd52Pr4Co44 phase in the grain boundary phase; and the ratio of the area of the Nd52Pr4Co44 phase to the total area of the grain boundary phase is 5.3%.
The invention further provides a preparation method of a neodymium-iron-boron magnet material, comprising the steps of: preparing a raw mixture comprising the respective components for the neodymium-iron-boron magnet material, and subjecting the raw mixture to smelting, casting, pulverization, shaping, sintering and aging treatments in turn.
The aging treatment includes a three-stage aging treatment, wherein, the temperature for a primary aging treatment is 850-950° C.; the temperature for a secondary aging treatment is 600-650° C.; and the temperature for a tertiary aging treatment is 450-550° C.
In the present invention, the temperature for the primary aging treatment is preferably 790-910° C., such as 900° C.
In the present invention, the time for the primary aging treatment can be for example 2-4 hours, such as 3 hours.
In the present invention, the temperature for the secondary aging treatment is preferably 610-640° C., such as 620° C. or 630° C.
In the present invention, the time for the secondary aging treatment can be for example 1-4 hours, such as 2 hours.
In the present invention, the temperature for the tertiary aging treatment is preferably 470-490° C., such as 480° C.
In the present invention, the time for the tertiary aging treatment can be for example 1-4 hours, such as 3 hours.
In the present invention, the preparation method can further comprise a grain boundary diffusion treatment after the tertiary aging treatment.
Wherein, the temperature for the grain boundary diffusion treatment is preferably 850-1000° C., such as 900° C., 910° C. or 920° C.
Wherein, the time for the grain boundary diffusion treatment is preferably 10-30 hours, such as 20 hours.
Wherein, the diffusion source for grain boundary diffusion treatment is a Dy metal powder or an alloy comprising Dy.
Wherein, the diffusion source for grain boundary diffusion treatment is preferably a Dy metal powder and/or an alloy comprising Dy.
The mass percentage of the diffusion source in the total mass of the neodymium-iron-boron magnet material is preferably 0.3-0.5 wt %, such as 0.4 wt %.
In the present invention, the process for the smelting treatment can be conventional in the field.
Wherein, the vacuum degree for the smelting is, for example, 5×10−2 Pa.
The temperature for the smelting is 1550° C. or less, such as 1530° C.
In the present invention, the process for the casting treatment may be conventional in the field.
Wherein, the casting process is, for example, a strip casting process.
Wherein, the temperature for the casting may be 1390-1460° C., for example, 1400° C.
Wherein, the alloy sheet obtained after the casting can have a thickness of 0.25-0.40 mm, such as 0.29 mm.
In the present invention, the process for the pulverization can be conventional in the field.
The pulverization generally comprises hydrogen decrepitation and jet mill pulverization in turn.
Wherein, the process of the hydrogen decrepitation generally comprises hydrogen absorption, dehydrogenation, and a cooling treatment in turn.
The hydrogen absorption can be carried out under a condition of a hydrogen pressure of 0.085 MPa.
The dehydrogenation can be carried out under the condition of raising the temperature while evacuating. The temperature for the dehydrogenation can be for example 480-520° C., such as 500° C.
The jet mill pulverization can be carried out in a gas atmosphere with an oxidizing gas content of 100 ppm or less, and the oxidizing gas content refers to the content of oxygen or moisture.
After the jet mill pulverization, a lubricant such as zinc stearate is generally added. The added amount of the lubricant may be 0.05-0.15%, for example 0.12%, of the mass of the powder obtained after the jet mill pulverization.
In the present invention, the shaping is a magnetic field shaping.
Wherein, the magnetic field shaping is carried out at magnetic field strength of for example, 1.8-2.5T.
In the present invention, the process for the sintering may adopt a conventional process in the art.
Wherein, the temperature for the sintering may be 1000-1100° C., for example, 1080° C. Wherein, the time for the sintering treatment may be 4-8 hours, for example, 6 hours.
The invention further provides a neodymium-iron-boron magnet material prepared by the preparation method as mentioned above.
The invention further provides use of the neodymium-iron-boron magnet material as an electronic component.
On the basis of conforming to common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain the preferred examples of the present invention.
The reagents and raw materials used in the present invention are all commercially available.
The positive effects of the present invention are as follows:
In the present invention, through the coordination of the elements such as Al, Cu, Co, Nb and B or the like with specific contents, the coercivity of the neodymium-iron-boron magnet material prepared is improved significantly while maintaining higher levels of remanence and squareness.
The present invention is further illustrated below by means of examples, but the present invention is not limited to the scope of the examples. The experimental methods not indicating specific conditions in the following examples were carried out according to the conventional methods and conditions, or were selected according to the product instructions.
The preparation process of the neodymium-iron-boron magnet material is as follows:
(1) Smelting:
The raw material mixture according to the composition of the neodymium-iron-boron magnet material recorded in Table 1 was smelted in a high-frequency vacuum induction melting furnace with a vacuum degree of 5×10−2 Pa at a smelting temperature of 1530° C.
(2) Casting:
An alloy cast sheet having a thickness of 0.29 mm was obtained by the strip casting process, wherein the casting temperature was 1400° C.
(3) Pulverization Process: hydrogen decrepitation and jet mill pulverization were carried out in turn.
The process of the hydrogen decrepitation comprised hydrogen absorption, dehydrogenation, and a cooling treatment in turn. The hydrogen absorption was carried out under the condition of hydrogen pressure of 0.085 MPa. The dehydrogenation was carried out under the condition of raising the temperature while evacuating, and the dehydrogenation temperature was 500° C.
The jet mill pulverization was performed in an atmosphere having an oxidizing gas content of 100 ppm or less. The particle size obtained by pulverization was 4.21 μm, wherein, the oxidizing gas referred to oxygen or moisture content. The pressure in the grinding chamber of the jet mill was 0.68 MPa. After pulverization, a lubricant, such as zinc stearate, was added, wherein the addition of the lubricant was 0.12% of the powder weight after mixing.
(4) Magnetic Field Shaping:
It was carried out at a magnetic field strength of 1.8-2.5T under the protection of a nitrogen atmosphere.
(5) Sintering:
The mixture was sequentially sintered and cooled under a vacuum condition of 5×10−3 Pa. The sintering treatment was performed at 1080° C. for 6 hours. Before the cooling treatment, Ar gas can be introduced to make the pressure reach 0.05 MPa.
(6) Three-Stage Aging Treatment:
The primary aging treatment was carried out at a temperature of 900° C. for 3 hours; the secondary aging treatment was carried out at a temperature of 630° C. for 2 hours; the tertiary aging treatment was carried out at a temperature of 480° C. for 3 hours.
(7) Grain Boundary Diffusion:
A Dy metal powder was diffused into the magnet material obtained after the three-stage aging treatment through grain boundary diffusion treatment (the mass of the added Dy was 0.4 wt %, wt % is the mass percentage of Dy in the total mass of the neodymium-iron-boron magnet material, and the remaining content being 1.3 wt % for Dy recorded in Table 1 was added during smelting), wherein the temperature for the grain boundary diffusion treatment was 910° C., and the time for the grain boundary diffusion treatment was 20 hours.
In Examples 1-5 and 10-13, and Comparative Examples 1-8, raw materials according to the formula in Table 1 below were prepared, and the temperature for the secondary aging treatment is shown in Table 1, and the rest of the preparation process was the same as that in Example 1. Wherein, the content of Dy added during grain boundary diffusion was 0.4 wt %, and the remaining Dy in Table 1 was added during smelting.
In Examples 6-9, 14 and 15, raw materials according to the formula in Table 1 below were prepared, wherein the preparation process did not comprise grain boundary diffusion treatment after the tertiary aging treatment. The temperature for the secondary aging treatment is shown in Table 1, and the rest of the preparation process was the same as that in Example 1.
Effect Example 1
1. Determination of Components:
The neodymium-iron-boron magnet materials prepared in Examples 1-15 and Comparative Examples 1-8 were measured using a high-frequency inductively coupled plasma optical emission spectrometer (ICP-OES). The test results are shown in Table 1 below.
Note: “/” indicates that the element is neither added nor detected. In the neodymium-iron-boron magnet materials of the above-mentioned examples and comparative examples, the value of Fe content is 100% minus the content of all other elements. Those skilled in this field know that the content of Fe comprises some unavoidable impurities introduced during the preparation process.
2. Testing for Magnetic Performance
At room temperature of 20° C., the neodymium-iron-boron magnet materials prepared in Examples 1-15 and Comparative Examples 1-8 were tested by using a PFM pulsed BH demagnetization curve testing equipment to obtain the data of remanence (Br), intrinsic coercivity (Hcj), maximum energy product (BHmax) and squareness (Hk/Hcj). The testing results are shown in Table 2 below.
3. Testing for Microstructures
FE-EPMA Detection:
The vertically oriented faces of the neodymium-iron-boron magnet materials prepared in Examples 1-15 and Comparative Examples 1-8 were polished, and tested by using a Field Emission Electron Probe Microanalyzer (FE-EPMA) (JEOL, 8530F). Firstly, the distribution of Nd, Pr and Co elements in the grain boundary phases of the neodymium-iron-boron magnet materials was determined by surface scanning using FE-EPMA. Then, the mole percentages of respective elements in the NdxPryCoz phase were determined by single-point quantitative analysis using FE-EPMA. The test conditions included an accelerating voltage of 15 kv and a probe beam current of 50 nA. The testing results are shown in Table 2 below.
Wherein, the percentage of the area of NdxPryCoz phase refers to the ratio of the area of NdxPryCoz phase in the cross-section (that is, the vertically oriented face as mentioned above) of the neodymium-iron-boron magnet material to the total area of the grain boundary phase in the cross-section.
From the above experimental data, it can be seen that in the present invention, through the combination of Co, Al, Cu, Nb, rare earth elements, or the like with specific contents and in combination with the specific three-stage aging treatment in the preparation process, the coercivity of the neodymium-iron-boron magnet material prepared is improved significantly as compare to those in the prior art while maintaining higher levels of remanence and squareness. According to the further results of microscopic detection, this may be due to: in the invention, by optimizing the formula of the neodymium-iron-boron magnet material, a NdxPryCoz phase with a specific content is formed in the grain boundary phase of the neodymium-iron-boron magnet material prepared, which optimizes the grain boundary structure and improves the coercivity.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202110866196.2 | Jul 2021 | CN | national |
This application is a continuation of International Patent Application No. PCT/CN2022/072256, which is a continuation of CN202110866196.2, both of which are incorporated in their entirety herein by reference and made a part hereof.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN22/72256 | Jan 2022 | US |
| Child | 18411258 | US |
