CN-122000158-A - ThMn (methyl methacrylate)12Rare earth permanent magnet and preparation method thereof

Abstract

The invention discloses a ThMn 12 type rare earth permanent magnet and a preparation method thereof. The preparation method comprises the steps of uniformly mixing raw materials containing Sm, fe, ti, V, al and Cu, smelting to obtain an alloy ingot, sequentially carrying out homogenization annealing heat treatment, hydrogen breaking and air flow grinding on the alloy ingot to obtain alloy powder, carrying out orientation molding and presintering on the alloy powder to obtain a permanent magnet blank, carrying out hot pressing on the permanent magnet blank under inert atmosphere to obtain a compact magnet, and carrying out high-temperature tempering on the compact magnet to obtain the ThMn 12 type rare earth permanent magnet. According to the preparation method, the prepared ThMn 12 type rare earth permanent magnet has high density, stable 1:12 phase structure and excellent magnetic performance through a presintering-hot pressing-tempering synergistic process.

Inventors

• MA ZIHAO
• CHEN RENJIE
• Xing Guangzong
• TANG XU
• YIN WENZONG
• DAI GE

Assignees

• 中国科学院宁波材料技术与工程研究所

Dates

Publication Date

20260508

Application Date

20260407

Claims (10)

1. 1. The preparation method of the ThMn 12 rare earth permanent magnet is characterized by comprising the following steps of: Uniformly mixing raw materials containing Sm, fe, ti, V, al and Cu, smelting to obtain an alloy ingot, and sequentially carrying out homogenization annealing heat treatment, hydrogen breaking and air flow grinding on the alloy ingot to obtain alloy powder; Carrying out orientation molding and presintering on the alloy powder to obtain a permanent magnet blank; Carrying out hot pressing treatment on the permanent magnet blank in an inert atmosphere to obtain a compact magnet; and (3) carrying out high-temperature tempering on the compact magnet to obtain the ThMn 12 type rare earth permanent magnet.
2. 2. The preparation method of claim 1, wherein the raw materials comprise, by atomic percentage, sm 7-13 at%, ti 8 at%, V8 at%, al 2 at%, cu 0.5 at% and Fe as the rest; and/or the preparation method specifically comprises the steps of carrying out homogenizing annealing heat treatment on the alloy cast ingot for 10-30 hours at 900-1300 ℃ in inert atmosphere; And/or the temperature of the hydrogen fracture is normal temperature, and the hydrogen pressure is 0.1-0.2 MPa; and/or the flow speed of the air flow speed of the nozzle in the jet mill is 300-500 m/s, the pressure of the crushing chamber is 0.4-0.8 MPa, and the speed of the classification wheel is 80-120 m/s; and/or the average grain size of the alloy powder is 2.5-4 mu m.
3. 3. The method according to claim 2, wherein the temperature of the homogenizing annealing heat treatment is 1000-1200 ℃ and the time is 15-25 hours; and/or the inert atmosphere comprises argon.
4. 4. The preparation method of the permanent magnet blank according to claim 1, which is characterized by comprising the steps of carrying out magnetic field orientation molding on the alloy powder to obtain a low-density blank with orientation, carrying out cold isostatic pressing, and presintering at 1000-1200 ℃ for 1-5 hours to obtain the permanent magnet blank.
5. 5. The method of claim 4, wherein the magnetic field is 2-4T for 20-40 s; And/or the density of the low-density blank is 3.5-4.5 g/cm 3 ; And/or the pressure of the cold isostatic pressing is 150-200 MPa, and the time is 30-90 s.
6. 6. The method of claim 1, wherein the hot pressing is performed at a temperature of 1000-1200 ℃, a pressing pressure of 50-150 kN, and a pressing time of 2-4 min.
7. 7. The method according to claim 1, wherein the high-temperature tempering is performed on the compact magnet at 1000-1200 ℃ for 1-5 hours to obtain the ThMn 12 type rare earth permanent magnet with high coercivity and high maximum magnetic energy product.
8. 8. The method according to claim 7, further comprising placing a metal Sm coarse powder having a thickness of 0.01-1 mm while the high temperature tempering is performed in a sealed environment, and isolating the dense magnet with a molybdenum foil.
9. 9. The ThMn 12 type rare earth permanent magnet produced by the production method according to any one of claims 1 to 8, wherein the component of the ThMn 12 type rare earth permanent magnet is Sm x Fe bal Ti 8 V 8 Al 2 Cu 0.5 , wherein 7% < x <13%, ti 8%, V8%, al 2%, cu 0.5% and the balance being Fe in atomic percent.
10. 10. The ThMn 12 type rare earth permanent magnet according to claim 9, wherein the coercive force of the ThMn 12 type rare earth permanent magnet is 7kOe or more and the maximum magnetic energy product is 5MGOe or more.

Description

ThMn 12 type rare earth permanent magnet and preparation method thereof Technical Field The invention belongs to the technical field of rare earth permanent magnet materials, and particularly relates to a ThMn 12 type rare earth permanent magnet and a preparation method thereof. Background In the field of rare earth permanent magnet materials, the third-generation rare earth permanent magnet represented by neodymium iron boron has extremely high theoretical maximum magnetic energy product, and shows excellent magnetic performance in a room temperature environment, but the coercive force of the third-generation rare earth permanent magnet can be remarkably attenuated under high-temperature service conditions. In order to maintain its high temperature magnetic properties, it is often necessary to add expensive and resource-scarce heavy rare earth elements such as dysprosium (Dy) and terbium (Tb) to the material, which increases the material cost significantly. In addition, after decades of development and optimization, the performance of the neodymium-iron-boron permanent magnet gradually approaches to the theoretical limit of the neodymium-iron-boron permanent magnet, and the technical bottleneck is further broken through. Therefore, the research and development of a novel permanent magnet material with high coercivity and high maximum magnetic energy product and reducing dependence on heavy rare earth has become the pursuit goal of the permanent magnet industry to develop towards high performance, low cost and high stability, and has important significance for meeting the application requirements of fields such as electric automobiles, wind power generation, high-end industrial motors and the like under high-temperature complex working conditions. The ThMn 12 rare earth permanent magnet material has the characteristics of excellent theoretical magnetic property, remarkably lower rare earth content than neodymium iron boron and the like, and attracts wide attention. However, in the preparation process of the block magnet facing the practical application, a plurality of challenges are faced in (1) a large amount of impurity phases such as alpha-Fe and the like are easy to separate out in the alloying and solidification processes, so that the purity of the main phase of the ThMn 12 is reduced, the high theoretical anisotropic field advantage of the main phase of the ThMn 12 is not fully exerted, the actual coercive force is improved, and the fundamental bottleneck is faced, and (2) the block magnet with high density and ideal grain boundary structure is difficult to obtain by adopting the traditional sintering process, so that the actual maximum magnetic energy product is far lower than the theoretical value, and the application of the block magnet as a high-performance permanent magnet material is limited. At present, the prior art CN112103022A and the like generate non-magnetic grain boundary phase through component design induction to strengthen the coercive force of the magnet, the amorphous precursor is obtained through a melt rapid quenching technology to inhibit alpha-Fe phase precipitation, an isotropic bulk magnet is obtained through a hot pressing technology, the magnet anisotropy is induced through a thermal deformation technology, and finally the anisotropic THMn 12 -based rare earth permanent magnet is obtained. However, the technical core is that the structure refinement and the phase control are realized by depending on a rapid quenching process, and the mixed phases such as alpha-Fe still exist in the ingot casting stage, and the whole process belongs to a typical technical route of rapid quenching strip + hot pressing + thermal deformation, but the process has the problems that the process cannot be industrially and stably carried out on a large scale, the requirements on equipment and a die are harsh, the uniformity is poor and the like, and the final magnetic performance level is limited. Disclosure of Invention The invention mainly aims to provide a ThMn 12 type rare earth permanent magnet and a preparation method thereof, so as to overcome the defects of the prior art. In order to achieve the purpose of the invention, the technical scheme adopted by the invention comprises the following steps: The first aspect of the present invention provides a method for preparing a rare earth permanent magnet of the ThMn 12 type, comprising: Uniformly mixing raw materials containing Sm, fe, ti, V, al and Cu, smelting to obtain an alloy ingot, and sequentially carrying out homogenization annealing heat treatment, hydrogen breaking and air flow grinding on the alloy ingot to obtain alloy powder; Carrying out orientation molding and presintering on the alloy powder to obtain a permanent magnet blank; Carrying out hot pressing treatment on the permanent magnet blank in an inert atmosphere to obtain a compact magnet; and (3) carrying out high-temperature tempering on the compact magnet to obtain the ThMn 12