Preparation method of easy-axis texture magnetic material

Abstract

The invention discloses a preparation method of an easy-axis texture magnetic material, which comprises the following steps: vacuumizing a vacuum suction casting device, and pouring inert gas backwards; completely melting the alloy material to obtain a melt; vacuum suction casting is started, meanwhile, a static magnetic field is applied, a metal casting mold is arranged to be longitudinally parallel to the direction of the static magnetic field, the melt is sucked into a vacuum suction casting device cooled by a cooling medium, and the melt is rapidly solidified under the action of the static magnetic field to obtain a grain growth easy axis parallel to the direction of the magnetic field. According to the method, an easy-axis texture is achieved aiming at orientation control over a magnetic functional material matrix structure, crystal grains of a liquid-solid interface interact through release of crystallization latent heat pulses in the material solidification process, and interaction-free sequential solidification of the crystal grains is achieved by improving cooling conditions, exporting crystallization latent heat in time and eliminating fluctuation of the crystallization latent heat; the static magnetic field is applied to adjust the grain orientation so as to realize the easy axial orientation of the grown grains, the operation is simple, the efficiency is high, and the easy axial orientation effect of magnetic materials in various shapes can be effectively obtained.

Description

Technical Field

[0001] The invention belongs to the field of material processing, and in particular relates to a method for preparing an easy-axis textured magnetic material. Background Art

[0002] In the prior art, the matrix structure of most magnetic materials has the best magnetic properties along the easy magnetization axis direction. The orientation of the easy magnetization axis of the preparation of magnetic materials has always been one of the research goals of materials science. However, in the actual preparation process of magnetic materials, there is no universal method to achieve this goal.

[0003] In recent years, some studies have reported that solidification in a magnetic field can achieve the orientation of the easy magnetic axis of the matrix structure, but there is still a lack of substantial progress. What is easily overlooked is that the solidification process is a process of continuous pulse phase change. These continuous pulse phase changes are accompanied by the release of pulsed crystallization latent heat. This state causes the grains at the liquid-solid interface during the solidification process to be in an interactive fluctuating state, resulting in the static magnetic field being unable to effectively induce grain orientation. However, previous studies have overemphasized the adjustment of the magnetic field and neglected the control of the extraction of latent heat of crystallization. If the latent heat of crystallization can be extracted in time to ensure the supercooling required for grain growth, the grains at the liquid-solid interface can independently complete the phase change without interacting with each other, thereby providing a realistic solidification environment for the magnetic field to induce the grains to freely adjust their orientation.

[0004] Patent document CN113355734A discloses a method for preparing easy-axis texture in a magnetic field-induced isothermal solidification process, comprising: placing a crystalline material in a vacuum furnace filled with argon, then heating the crystalline material to the solidus, then heating from the solidus to the phase transition temperature of the matrix phase, applying a static magnetic field after heat preservation, cooling to the solidus, then cutting off the heat source and the static magnetic field, and cooling with the furnace. In the general solidification process of large-sized crystalline materials under the action of a magnetic field, the formation of the easy-axis texture of the crystal is very sensitive to temperature. When the crystalline material solidifies from a temperature higher than the phase transition temperature formed by the matrix phase, the orientation effect of the magnetic field on the crystal almost disappears. At this time, the orientation effect of the crystal is similar to that without the action of a static magnetic field. When the crystalline material is controlled in an isothermal range not higher than the phase transition temperature formed by the matrix phase, the magnetic field has the best orientation effect on the growing crystal. The patent document emphasizes that the temperature of the material is not higher than the phase transition temperature of the matrix phase to avoid crystallization thermal disturbance. The temperature control is very difficult, and the solidification is slow. It is only suitable for large-sized materials, but the efficiency is low. Patent document CN118765424A discloses a nano-functionalized magnetic material raw material, which contains: from 50wt% to 99.5wt% of magnetic micron particles with an average micron particle effective diameter from 1 micron to 500 microns; from 0.4wt% to 40wt% of one or more rare earth elements; and from 0.1wt% to 10wt% of metal-containing inoculant nanoparticles, wherein at least 1wt% of the inoculant nanoparticles are chemically and / or physically arranged on the surface of the magnetic micron particles, and the nano-functionalized magnetic material raw material is processed using high-throughput laser-based additive manufacturing to optimize the architecture of NdFeB or other magnets, thereby producing a specific site-specific anti-demagnetization microstructure. A fast, single-step laser-based method is proposed to customize the easy axis alignment, grain size and microstructure of permanent magnets at corners and edges to resist demagnetization. In this case, a magnetic field is applied to orient the easy axis of the grains during solidification, microsecond-long melting and solidification of a small volume occur continuously, and the laser beam is focused on different edges and corners while changing the applied magnetic field to customize the easy axis orientation. This patent document does not pay attention to the influence of the fluctuation of the latent heat of crystallization during the solidification process of the material on the orientation. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a method for preparing an easy-axis textured magnetic material, which is a material processing method for controlling the orientation of the matrix tissue of a magnetic functional material to achieve easy-axis texture. During the solidification of the material, the release of the crystallization latent heat pulse causes the grains at the liquid-solid interface to interact with each other. By improving the cooling conditions and timely extracting the crystallization latent heat, the fluctuation of the crystallization latent heat can be eliminated, and sequential solidification of the grains without interaction can be achieved. At this time, applying a static magnetic field can adjust the grain orientation to achieve the easy-axis orientation of the growing grains. After solidification, the matrix tissue is arranged along the easy axis in the direction of the magnetic field.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention provides a method for preparing an easy-axis textured magnetic material, comprising the following steps:

[0008] (1) Evacuate the vacuum casting device and backfill with inert gas;

[0009] (2) completely melting the alloy material to obtain a melt;

[0010] (3) starting vacuum suction casting and applying a static magnetic field at the same time, setting the longitudinal direction of the metal casting mold parallel to the direction of the static magnetic field, sucking the melt obtained in step (2) into a vacuum suction casting device cooled by a cooling medium for solidification, and obtaining a grain growth axis parallel to the direction of the magnetic field through rapid solidification under the action of the static magnetic field.

[0011] Preferably, in step (2), the alloy material is a crystalline magnetic material.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] The present invention proposes a method for preparing an easy-axis textured magnetic material. Under the action of a static magnetic field, the easy axis of grain growth is obtained by rapid solidification in a direction parallel to the magnetic field direction, that is, the easy-axis oriented growth of the magnetic material matrix structure is achieved. The method is simple to operate and has high efficiency, and can effectively obtain the easy-axis orientation effect of magnetic materials of various shapes. DETAILED DESCRIPTION

[0014] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0015] Example 1

[0016] This embodiment provides a method for preparing an easy-axis textured magnetic material, which is performed using a vacuum suction casting device with an external longitudinal static magnetic field, and the steps are as follows:

[0017] A. Evacuate the vacuum casting device with an inner diameter of 10 mm to 10 -2 Order of magnitude, and then backfill with high-purity argon gas.

[0018] B. Place the Fe-Ga alloy in a crucible and melt it completely to obtain a melt.

[0019] C. Start vacuum suction casting and apply a static magnetic field with a magnetic induction intensity of 10T at the same time. Set the longitudinal direction of the metal casting mold parallel to the direction of the static magnetic field. Suck the obtained melt into a vacuum suction casting device cooled by a cooling medium for solidification. Under the action of the static magnetic field, the grain growth axis is parallel to the magnetic field direction through rapid solidification.

[0020] Comparative Example 1

[0021] This embodiment provides a method for preparing an easy-axis textured magnetic material, which is performed using a vacuum suction casting device with an external longitudinal static magnetic field, and the steps are as follows:

[0022] A. Place the Fe-Ga alloy in a crucible and melt it completely to obtain a melt.

[0023] B. Evacuate the vacuum casting device with an inner diameter of 10 mm to 10 -2 Order of magnitude, and then backfill with high-purity argon gas.

[0024] C. Start vacuum suction casting, and suck the obtained melt into a vacuum suction casting device cooled by a cooling medium for solidification.

[0025] The results are compared as follows: In Example 1, the Fe-Ga alloy is obtained along the magnetic field direction. <100> The sample in Comparative Example 1 has no easy axis orientation along the longitudinal direction. <100> orientation.

[0026] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an easy-axis textured magnetic material, characterized in that: The following steps are involved: (1) Evacuate the vacuum casting device and backfill with inert gas; (2) completely melting the alloy material to obtain a melt; (3) starting vacuum suction casting and applying a static magnetic field at the same time, setting the longitudinal direction of the metal casting mold parallel to the direction of the static magnetic field, sucking the melt obtained in step (2) into a vacuum suction casting device cooled by a cooling medium for solidification, and obtaining a grain growth axis parallel to the direction of the magnetic field through rapid solidification under the action of the static magnetic field.

2. The method for preparing the easy-axis textured magnetic material according to claim 1, characterized in that: In step (2), the alloy material is a crystalline magnetic material.