阅读说明：本技术 一种制备兼具高矫顽力和高磁各向异性纳米晶Co基稀土永磁的方法 (Method for preparing nanocrystalline Co-based rare earth permanent magnet with high coercive force and high magnetic anisotropy ) 是由 李玉卿 滕媛 岳明 刘卫强 徐晓厂 路清梅 张东涛 张红国 吴琼 于 2021-07-23 设计创作，主要内容包括：一种制备兼具高矫顽力和高磁各向异性纳米晶Co基稀土永磁的方法,属于功能材料技术领域。所述制备方法包括以下步骤：制备Co基稀土磁粉；对Co基稀土磁粉进行热压,获得热变形前驱体；对热变形前驱体进行热变形,获得强织构高各向异性纳米晶Co基永磁体。本发明中热变形前驱体的微观结构由RCo-(5)主相和细小且弥散分布的纳米晶富稀土相组成,细小且弥散分布的纳米晶富稀土相是磁体能低温变形和获得强c轴织构的关键。本发明所制备的各向异性纳米晶Co基稀土永磁形成了强的c轴织构,同时具有高矫顽力和良好的热稳定性,在高温永磁领域具有较大的应用空间。(A method for preparing nanocrystalline Co-based rare earth permanent magnet with high coercivity and high magnetic anisotropy belongs to the technical field of functional materials. The preparation method comprises the following steps: preparing Co-based rare earth magnetic powder; hot-pressing the Co-based rare earth magnetic powder to obtain a thermal deformation precursor; and thermally deforming the thermally deformed precursor to obtain the nanocrystalline Co-based permanent magnet with strong texture and high anisotropy. The microstructure of the thermally deformable precursor in the present invention is formed by RCo 5 The main phase and the fine and dispersed nanocrystalline rare earth-rich phase are key points for the magnet to deform at low temperature and obtain strong c-axis texture. The anisotropic nanocrystalline Co-based rare earth permanent magnet prepared by the invention forms a strong c-axis texture, has high coercivity and good thermal stability, and has a large application space in the field of high-temperature permanent magnets.)

1. A method for preparing nanocrystalline Co-based rare earth permanent magnet with high coercivity and high magnetic anisotropy is characterized by comprising the following steps:

(1) milling: the preparation method comprises the following steps of (1) proportioning raw materials according to a stoichiometric ratio, smelting by a vacuum intermediate frequency furnace to prepare a Co-based rare earth alloy ingot, and preparing Co-based rare earth magnetic powder by melt rapid quenching and/or high-energy ball milling;

(2) hot pressing: hot-pressing the Co-based rare earth magnetic powder at the temperature of 500-700 ℃ and the pressure of 100-1000MPa to obtain a nanocrystalline thermal deformation precursor;

(3) thermal deformation: thermally deforming the precursor at 600-800 ℃, the deformation amount of 70-90% and the pressure of 50-500MPa to prepare the anisotropic nanocrystalline Co-based rare earth permanent magnet.

2. According to claim 1The method for preparing the nanocrystalline Co-based rare earth permanent magnet with high coercive force and high magnetic anisotropy is characterized by comprising the following steps: the alloy in the step (1) is RCo_XTM_yX + Y is more than 4.34 and less than 4.76, Y is more than or equal to 0 and less than or equal to 0.3, wherein R is one or more of elements such as Sm, Pr, La, Ce, Y and the like, and TM is one or more of elements such as Ni, Fe, Mn, Cr, Al, Sn, Ga, Ti, Zn, Zr, Mo, Ag, Cu and the like.

3. The method for preparing the nanocrystalline Co-based rare earth permanent magnet with high coercivity and high magnetic anisotropy according to claim 1, which is characterized in that: the alloy according to step (1) is according to RCo_XTM_yThe materials are mixed according to the atomic ratio, and no rare earth is additionally added for burning loss; wherein x + y is less than 4.76 to ensure RCo₅A main phase and a diffusely distributed rare earth-rich phase.

4. The method for preparing the nanocrystalline Co-based rare earth permanent magnet with high coercivity and high magnetic anisotropy according to claim 1, which is characterized in that: the microstructure of the nanocrystalline thermal deformation precursor in the step (2) is formed by nanocrystalline RCo₅The main phase and a fine and dispersedly distributed rare earth-rich phase, and the size of the rare earth-rich phase is 3-10 nm.

5. The method for preparing nanocrystalline Co-based rare earth permanent magnet with both high coercivity and high magnetic anisotropy according to claim 3 or 4, characterized in that: the existence of fine and dispersedly distributed rare earth-rich phases is the key that the magnet can deform at a lower deformation temperature and obtain a strong c-axis texture.

6. The method for preparing the nanocrystalline Co-based rare earth permanent magnet with high coercivity and high magnetic anisotropy according to claim 1, which is characterized in that: the nanocrystalline Co-based rare earth permanent magnet microstructure with the strong texture and the high anisotropy, which is described in the step (3), is provided with a rare earth-rich phase which is dispersed and distributed in the crystal grains and on the crystal boundary, and the size of the crystal grains is 10-50 nm.

Technical Field

The invention relates to a method for preparing a nanocrystalline Co-based rare earth permanent magnet with high coercivity and high magnetic anisotropy, belonging to the technical field of functional magnetic materials.

Background

The rare earth permanent magnetic material is widely applied to the aspects of aerospace, energy, traffic, machinery, information, household appliances, consumer electronics and the like, particularly the rapid development of global energy-saving and environment-friendly industry in recent years promotes the application of the rare earth permanent magnetic material in the emerging fields of hybrid electric vehicles, energy-saving household appliances, robots, wind power generation and the like, and the application market space is huge. The Co-based rare earth permanent magnet is more suitable for severe environments, particularly the high-temperature application field, due to the fact that the Co-based rare earth permanent magnet has super large magnetocrystalline anisotropy, high Curie temperature and good corrosion resistance. The anisotropic nanocrystalline Co-based rare earth permanent magnet has good thermal stability and high magnetic performance. In recent years, the hot press-hot deformation technique is an effective way to prepare a magnetic anisotropic nanocrystalline magnet. Anisotropic nanocrystalline Nd-Fe-B magnets have been successfully prepared by this method at deformation temperatures of 700 ℃ -. Even when the heat distortion temperature is further increased to 900 ℃, the deformation amount is increased to 90% to obtain high magnetic anisotropy, but the coercive force of the final magnet is very low (less than 6kOe) due to coarsening of crystal grains caused by high deformation temperature, and the application of Co-based rare earth permanent magnet is limited. Therefore, achieving both high degree of texture and maintaining good microstructure in Co-based rare earth permanent magnets is an urgent need in the field of permanent magnet development.

Disclosure of Invention

The invention aims to overcome the problems and provide a method for preparing a nanocrystalline Co-based rare earth permanent magnet with high coercivity and high magnetic anisotropy.

The specific technical route of the invention is as follows: weighing rare earth and Co metal according to an atomic ratio, preparing a Co-based rare earth alloy ingot by a vacuum intermediate frequency furnace, and performing quick quenching and/or high-energy ball milling on an alloy ingot melt to prepare Co-based rare earth magnetic powder; hot-pressing the Co-based rare earth magnetic powder to obtain a thermal deformation precursor; and thermally deforming the thermally deformed precursor to obtain the nanocrystalline Co-based permanent magnet with strong texture and high anisotropy.

The method for preparing the nanocrystalline Co-based rare earth permanent magnet with high coercivity and high magnetic anisotropy comprises the following steps:

(1) milling: the preparation method comprises the following steps of (1) proportioning raw materials according to a stoichiometric ratio, smelting by a vacuum intermediate frequency furnace to prepare a Co-based rare earth alloy ingot, and preparing Co-based rare earth magnetic powder by melt rapid quenching and/or high-energy ball milling;

(2) hot pressing: hot-pressing the Co-based rare earth magnetic powder at the temperature of 500-700 ℃ and the pressure of 100-1000MPa to obtain a nanocrystalline thermal deformation precursor;

(3) thermal deformation: thermally deforming the precursor at 600-800 ℃, the deformation amount of 70-90% and the pressure of 50-500MPa to prepare the anisotropic nanocrystalline Co-based rare earth permanent magnet.

The alloy of the invention is RCo_XTM_y(x + Y is more than 4.34 and less than 4.76, and Y is more than or equal to 0 and less than or equal to 0.3), wherein R is one or more of elements such as Sm, Pr, La, Ce, Y and the like, and TM is one or more of elements such as Ni, Fe, Mn, Cr, Al, Sn, Ga, Ti, Zn, Zr, Mo, Ag, Cu and the like.

The alloy according to the invention is according to RCo_XTM_y(x + y is more than 4.34 and less than 4.76, and y is more than or equal to 0 and less than or equal to 0.3) (atomic ratio) without additionally adding rare earth for burning loss; wherein x + y is less than 4.76, which can compensate the loss of rare earth elements during smelting and ensure to obtain RCo₅A main phase and a diffusely distributed rare earth-rich phase.

The microstructure of the nanocrystalline thermal deformation precursor is composed of nanocrystalline RCo₅A main phase and a fine and dispersively distributed rare earth-rich phase, the rare earth-rich phase rule thereofIt is 3-10nm in size, as shown in FIG. 1.

The existence of the fine and dispersedly distributed rare earth-rich phase in the nanocrystalline thermal deformation precursor is the key point that the magnet can deform at a lower deformation temperature and obtain a strong c-axis texture.

The microstructure of the strong-texture high-anisotropy nanocrystalline Co-based rare earth permanent magnet disclosed by the invention has a rare earth-rich phase which is dispersedly distributed in main phase grains and on grain boundaries, and the grain size of the rare earth-rich phase is 10-50nm, as shown in figure 2; finally, the rare earth-rich phase in the strong-texture high-anisotropy nanocrystalline Co-based rare earth permanent magnet material is enlarged relative to the rare earth-rich phase in the nanocrystalline thermal deformation precursor.

The invention has the beneficial effects that:

the rare earth-rich phase which is fine and is dispersed is introduced into the nanocrystalline thermal deformation precursor, so that the nanocrystalline Co-based rare earth permanent magnet is deformed at low temperature, and the nanocrystalline Co-based rare earth permanent magnet can obtain high texture degree and maintain good microstructure; the prepared nanocrystalline Co-based rare earth permanent magnet has strong texture, high remanence ratio and large coercive force, has good thermal stability and has important significance for developing high-performance high-temperature permanent magnets.

Description of the figures and accompanying tables

FIG. 1 is a microstructure topography of a nanocrystalline thermally deformable precursor of example 1, with black boxes representing SmCo₅The main phase, the black circles represent nanocrystalline rare earth-rich phases;

FIG. 2 is a microstructure morphology of a thermally deformable magnet of example 1, in which black boxes represent SmCo₅The main phase, the black circles represent nanocrystalline rare earth-rich phases;

fig. 3 is a demagnetization curve of a thermally deformed magnet according to example 1.

Detailed Description

The invention will be further described with reference to the drawings and the embodiments without limiting the scope of the invention thereto.

Example 1

The method for preparing the nanocrystalline Co-based rare earth permanent magnet with both high coercivity and high magnetic anisotropy, which is described in the embodiment, specifically comprises the following steps:

(1) sm with the purity of 99.9 percent and Co with the purity of 99.9 percent are mixed according to the formula SmCo_4.55Zr_0.2Weighing the atomic ratio, and smelting in a PZGF-40 type intermediate frequency vacuum induction smelting furnace in argon atmosphere to obtain SmCo_4.55Zr_0.2Casting ingots;

(2) carrying out melt rapid quenching on the cast ingot in an argon atmosphere at the speed of 35m/s of a copper roller to prepare a Co-based rare earth rapid quenching belt;

(3) placing the rapid quenching belt into a stainless steel tank, taking a stainless steel ball as a ball milling medium, and carrying out ball milling for 4 hours in an argon atmosphere by a GN-2 type high-energy ball mill to obtain Co-based rare earth magnetic powder;

(4) loading the magnetic powder into a die with the diameter of 10mm, and carrying out hot pressing at 650 ℃ and 500MPa to obtain a nanocrystalline thermal deformation precursor;

(5) and (2) putting the nanocrystalline thermal deformation precursor into a die with the diameter of 22mm, heating to 650 ℃ under a vacuum state (less than 10Pa), gradually applying pressure to 50MPa, and preparing the nanocrystalline Co-based permanent magnet with the deformation of 70% and strong texture and high anisotropy.

Example 2

The method for preparing the nanocrystalline Co-based rare earth permanent magnet with high coercivity and high anisotropy and the method thereof specifically comprise the following steps:

(1) mixing Sm, Pr and 99.9% Co with purity of 99.9% (Sm)_0.6Pr_0.4)Co_4.63Weighing the atomic ratio, and smelting in a PZGF-40 type intermediate frequency vacuum induction smelting furnace under argon atmosphere to obtain (Sm)_0.6Pr_0.4)Co_4.63Casting ingots;

(2) carrying out melt rapid quenching on the cast ingot in an argon atmosphere at the speed of 35m/s of a copper roller to prepare a Co-based rare earth rapid quenching belt;

(3) placing the rapid quenching belt into a stainless steel tank, taking a stainless steel ball as a ball milling medium, and carrying out ball milling for 4 hours in an argon atmosphere by a GN-2 type high-energy ball mill to obtain Co-based rare earth magnetic powder;

(4) loading the magnetic powder into a die with the diameter of 10mm, and carrying out hot pressing at 650 ℃ and 500MPa to obtain a nanocrystalline thermal deformation precursor;

(5) and (2) putting the nanocrystalline thermal deformation precursor into a mold with the diameter of 35mm, heating to 700 ℃ under a vacuum state (less than 10Pa), gradually applying pressure to 300MPa, and preparing the nanocrystalline Co-based permanent magnet with the deformation of 90% and strong texture and high anisotropy.

Example 3

The method for preparing the nanocrystalline Co-based rare earth permanent magnet with high coercivity and high anisotropy and the method thereof specifically comprise the following steps:

(1) sm with the purity of 99.9 percent and Co with the purity of 99.9 percent are mixed according to the formula SmCo_4.46Weighing the atomic ratio, and smelting in a PZGF-40 type intermediate frequency vacuum induction smelting furnace in argon atmosphere to obtain SmCo_4.46Casting ingots;

(2) carrying out melt rapid quenching on the cast ingot in an argon atmosphere at the speed of 35m/s of a copper roller to prepare a Co-based rare earth rapid quenching belt;

(3) placing the rapid quenching belt into a stainless steel tank, taking a stainless steel ball as a ball milling medium, and carrying out ball milling for 4 hours in an argon atmosphere by a GN-2 type high-energy ball mill to obtain Co-based rare earth magnetic powder;

(4) loading the magnetic powder into a die with the diameter of 10mm, and carrying out hot pressing at 650 ℃ and 500MPa to obtain a nanocrystalline thermal deformation precursor;

(5) and (2) putting the nanocrystalline thermal deformation precursor into a mold with the diameter of 28mm, heating to 600 ℃ under a vacuum state (less than 10Pa), gradually applying pressure to 500MPa, and preparing the nanocrystalline Co-based permanent magnet with the deformation of 80% and strong texture and high anisotropy.

Comparative example

(1) Selection of proportional components of SmCo_4.76As a comparative example (Sm is volatile during smelting, in SmCo₅5 percent of Sm is added as burning loss), and the purity of the Sm with the purity of 99.9 percent and the purity of the Co with the purity of 99.9 percent are SmCo_4.76Weighing atomic ratio, and smelting in a PZGF-40 type intermediate frequency vacuum induction smelting furnace under argon atmosphere to obtain SmCo_4.76Casting ingots;

(2) carrying out melt rapid quenching on the cast ingot in an argon atmosphere at the speed of 35m/s of a copper roller to prepare a Co-based rare earth rapid quenching belt;

(3) placing the rapid quenching belt into a stainless steel tank, taking a stainless steel ball as a ball milling medium, and carrying out ball milling for 4 hours in an argon atmosphere by a GN-2 type high-energy ball mill to obtain Co-based rare earth magnetic powder;

(4) loading the magnetic powder into a die with the diameter of 10mm, and carrying out hot pressing at 650 ℃ and 500MPa to obtain a nanocrystalline thermal deformation precursor;

(5) the nanocrystalline thermal deformation precursor is filled into a mold with the diameter of 28mm, the temperature is raised to 600 ℃ under the vacuum state (less than 10Pa), the pressure is gradually applied to 500MPa, and the obtained magnet has the deformation of only 10 percent and shows weak anisotropy. Compared with example 3, it is demonstrated that introducing a fine and dispersed rare earth-rich phase into a nanocrystalline thermal deformation precursor can promote deformation and obtain a strong c-axis texture at a lower deformation temperature.

And (3) magnetic property testing:

the samples were centered and the magnetic performance data are shown in table 1 below.

TABLE 1