Method for improving compression performance of MnCoSi-based giant magnetostrictive material

Abstract

The present invention discloses a method for improving the compression performance of a MnCoSi-based giant magnetostrictive material, belonging to the technical field of giant magnetostrictive materials. The Sn element is added to the MnCoSi-based giant magnetostrictive material to improve the compression performance of the material. In terms of atomic percentage, the chemical expression of the material after the Sn element is added is MnCoSiSn x , x =0.1~0.2. The steps are: mixing ingredients according to atomic percentage, repeatedly smelting to obtain an ingot, vacuum packaging in a quartz tube, and heat treating to obtain the material. The present invention directly adds the low-melting-point element Sn to the MnCoSi-based alloy during the alloy smelting process. The Sn element can be evenly distributed in the cracks of the alloy, causing adhesion, thereby obtaining a relatively dense MnCoSi / Sn alloy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of magnetostrictive materials, and relates to a method for improving the mechanical properties of a MnCoSi-based giant magnetostrictive composite material. BACKGROUND

[0002] Magnetostriction effect refers to the change in size of a material under the action of a magnetic field. Giant magnetostrictive materials can convert electromagnetic energy into mechanical energy, and are an important class of functional materials. Due to their excellent mechanical response characteristics and high energy density, they have been widely used in sonar systems, ultrasonic devices and brakes. Currently used giant magnetostrictive materials mainly include Terfenol-D and Fe-Ga alloys. However, Terfenol-D alloy contains heavy rare earth Tb and Dy and has poor mechanical properties, and the saturation magnetostriction value of Fe-Ga is low, which hinders their further practical application.

[0003] As a large class of magnetic functional materials, the giant magnetostrictive effect of magnetic phase change alloys is derived from the dramatic change in unit cell parameters before and after the phase change induced by a magnetic field, which provides a candidate for exploring new types of giant magnetostrictive materials. Currently reported magnetic phase change alloys mainly include NiMn-based Heusler alloys, hexagonal MM’X alloys, La(Fe,Si) 13 However, these alloys have problems such as large thermal / magnetic hysteresis loss, non-recoverable magnetostrictive effect and high driving magnetic field.

[0004] In recent years, MnCoSi magnetoelastic phase change alloys have gradually attracted attention due to their unique three-phase magnetic properties and low cost. The magnetic atom Mn of the orthorhombic MnCoSi alloy has a critical nearest-neighbor Mn-Mn spacing, so the alloy exhibits a helical magnetic structure near room temperature. This non-collinear magnetic structure will lose stability and transform into a collinear ferromagnetic structure under an external magnetic field, and the alloy has a special metamagnetic phase transition accompanied by a sudden change in magnetization. Due to the strong magnetoelastic coupling effect, the lattice constant and volume of the MnCoSi alloy will change significantly during the metamagnetic phase transition, which macroscopically exhibits a giant magnetostrictive effect with a room temperature theoretical saturation value of 5000ppm. In addition, the alloy has a flexible and controllable three-phase temperature, making the giant magnetostrictive effect of the alloy completely reversible and hysteresis-free. However, the MnCoSi alloy undergoes a martensitic phase transition from a hexagonal structure to an orthorhombic structure at 1165K, and during this structural phase transition, the Co-Si covalent bond with high directionality and rigidity will partially break, resulting in cracks on the surface of the alloy ingot at the macroscopic scale. Therefore, the mechanical properties of the material are poor and it is easily broken, which cannot be machined. Therefore, under the condition of ensuring the giant magnetostrictive effect, improving the mechanical properties of the MnCoSi alloy is the primary prerequisite for the practical application of the material. SUMMARY

[0005] The present application aims at the defect of poor compression performance of MnCoSi-based giant magnetostrictive material, and provides a method for improving the compression performance of MnCoSi-based giant magnetostrictive material, which adopts the method of adding low-melting-point metal Sn through smelting bonding to obtain dense MnCoSi-based giant magnetostrictive composite material with high compression strength.

[0006] The technical scheme of the present application is as follows: a method for improving the compression performance of MnCoSi-based giant magnetostrictive material, Sn element is added to the MnCoSi-based giant magnetostrictive material to improve the compression performance of the giant magnetostrictive material, and the chemical expression of the giant magnetostrictive material after adding Sn element is MnCoSiSn in terms of atomic percentage. x , x=0.1~0.2.

[0007] Preferably, when x is 0.20, the giant magnetostrictive material obtains higher compression performance.

[0008] Preferably, MnCoSi-based master alloy ingot is prepared by vacuum arc smelting method, and MnCoSi-based giant magnetostrictive material is obtained through vacuum heat treatment, and the specific process is as follows:

[0009] 1) ingredients are prepared according to the atomic ratio of the chemical expression of the target material;

[0010] 2) the raw materials obtained in step 1) are placed in a vacuum arc smelting furnace, and after repeated smelting for 3 times, a relatively dense MnCoSi-based master alloy ingot is obtained;

[0011] 3) the master alloy ingot is sealed in a quartz tube for heat treatment, and the heat treatment steps are as follows: 2 hours to 850℃, then 60 hours of heat preservation at 850℃, and then 72 hours of slow cooling to room temperature, finally obtaining a uniform and dense ingot.

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

[0013] 1) In the present application, low-melting-point element Sn is added to MnCoSi-based alloy during alloy smelting, and Sn element can be uniformly distributed in the cracks of the alloy for bonding, so that a relatively dense MnCoSi / Sn alloy is obtained. In the process of arc smelting, because the formation energy of MnCoSi alloy is low and the melting point is higher than that of Sn, the solid phase formed first in the alloy liquid is MnCoSi phase, and the subsequently cooled Sn phase will fill the cracks, so that the magnetostrictive composite material obtained by the present application has better mechanical properties compared with MnCoSi-based alloy. The present application has a promoting effect on the practical application of MnCoSi-based material.

[0014] 2) The preparation method of the application is simple, only the raw materials of Sn and MnCoSi are directly mixed and smelted to obtain the final ingot, and the cost of the alloy is low, which is suitable for industrial production. The method can also be used for other MM'X alloy systems in the same family. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 X-ray diffraction (XRD) comparison chart of MnCoSi raw powder and magnetostrictive material obtained in Example 1 of the application.

[0016] Figure 2 MnCoSiSn obtained in Example 1 of the application 0.20 Microstructure morphology of the magnetostrictive material.

[0017] Figure 3 MnCoSiSn obtained in Example 1 0.20 Magnetization intensity curve of the magnetostrictive material with respect to the magnetic field.

[0018] Figure 4 Stress-strain curve chart of the giant magnetostrictive material prepared in Comparative Example 1 and Examples 1-3.

[0019] Figure 5 Giant magnetostriction comparison chart of the giant magnetostrictive material prepared in Comparative Example 1 and Examples 1-3. DETAILED DESCRIPTION

[0020] The MnCoSi / Sn-based giant magnetostrictive composite material with high compressive strength and low phase transition critical field is obtained by the low melting point metal bonding method.

[0021] It should be noted that the Sn component in the MnCoSi / Sn giant magnetostrictive material in the application is not specifically limited, and the Sn content of 0.20 is preferred in consideration of the compression performance and magnetostrictive effect. As long as the element Sn is added, bonding will be formed at the crack, thereby improving the compression performance; too high Sn content will affect the saturation magnetostrictive effect, so the Sn content is preferably 0.20.

[0022] The application will be further described in detail below in conjunction with examples, but the embodiments of the application are not limited thereto.

[0023] Comparative Example 1

[0024] MnCoSiSn 0.25 Preparation process of the magnetostrictive material:

[0025] 1) The Mn, Co, Si and Sn elements are proportioned according to the atomic percentage of 1:1:1:0.25;

[0026] 2) The above ingredients are placed in a vacuum arc melting furnace, and after three times of repeated melting under a vacuum degree of 3 x 10 -3 Pa, a relatively dense ingot is obtained;

[0027] 3) The temperature is raised to 850°C in 2 hours, and then the temperature is kept at 850°C for 60 hours, and then slowly cooled to room temperature in 72 hours, to obtain MnCoSiSn 0.25 magnetostrictive material.

[0028] Example 1

[0029] MnCoSiSn 0.20 magnetostrictive material preparation process:

[0030] 1) The ingredients of Mn, Co, Si and Sn are proportioned according to the atomic percentage of 1:1:1:0.20;

[0031] 2) The above ingredients are placed in a vacuum arc melting furnace, and after three times of repeated melting under a vacuum degree of 3 x 10 -3 Pa, a relatively dense ingot is obtained;

[0032] 3) The temperature is raised to 850°C in 2 hours, and then the temperature is kept at 850°C for 60 hours, and then slowly cooled to room temperature in 72 hours, to obtain MnCoSiSn 0.20 magnetostrictive material.

[0033] Example 2

[0034] MnCoSiSn 0.10 magnetostrictive material preparation process:

[0035] 1) The ingredients of Mn, Co, Si and Sn are proportioned according to the atomic percentage of 1:1:1:0.10;

[0036] 2) The above ingredients are placed in a vacuum arc melting furnace, and after three times of repeated melting under a vacuum degree of 3 x 10 -3 Pa, a relatively dense ingot is obtained;

[0037] 3) The temperature is raised to 850°C in 2 hours, and then the temperature is kept at 850°C for 60 hours, and then slowly cooled to room temperature in 72 hours, to obtain MnCoSiSn 0.10 magnetostrictive material.

[0038] Example 3

[0039] MnCoSiSn 0.15 magnetostrictive material preparation process:

[0040] 1) The ingredients are prepared according to the atomic percentage of Mn, Co, Si, and Sn in the ratio of 1:1:1:0.15;

[0041] 2) The above ingredients are melted in a vacuum arc melting furnace at a vacuum degree of 3×10 -3 In the case of Pa, after repeated smelting three times, a relatively dense ingot was obtained;

[0042] 3) Heating to 850℃ in 2 hours, then keeping at 850℃ for 60 hours, and then slowly cooling to room temperature for 72 hours to obtain MnCoSiSn 0.15 Magnetostrictive materials.

[0043] MnCoSiSn obtained in Example 1 0.20 The XRD diffraction of magnetostrictive materials at room temperature is as follows Figure 1 As shown. It can be seen that compared with the original powder (MnCoSi), Figure 1 Medium MnCoSiSn 0.20 The magnetostrictive material shows a diffraction peak of Sn, and the original main phase is not destroyed, ensuring its magnetostrictive effect.

[0044] Figure 2 The MnCoSiSn obtained in Example 1 0.20 SEM image of magnetostrictive material, Figure 2 It can be seen that MnCoSiSn 0.20 The cracks are filled with element Sn.

[0045] Figure 3 The MnCoSiSn obtained in Example 1 0.20 The relationship between the magnetization intensity and magnetic field of magnetostrictive material. Figure 3 It can be seen that the saturation magnetization intensity of magnetostrictive materials is close to 100Am 2 kg -1 , the critical field is around 2T.

[0046] Figure 4 The MnCoSiSn prepared in Comparative Example 1 0.25 , MnCoSiSn prepared in Example 1 0.20 , MnCoSiSn prepared in Example 2 0.1 , MnCoSiSn prepared in Example 3 0.15The compressive strength of the magnetostrictive material obtained in Example 1 is close to 900 MPa, the compressive strength of the magnetostrictive material obtained in Example 2 is 100 MPa, the compressive strength of the magnetostrictive material obtained in Example 3 is 180 MPa, and the compressive strength of the magnetostrictive material obtained in Comparative Example 1 is 300 MPa. It can be seen from Examples 1-3 and Comparative Example 1 that the addition of Sn element can improve the compressive performance of the MnCoSi-based giant magnetostrictive material, which is much greater than the compressive strength of the existing MnCoSi material (<2 MPa, according to the literature). In summary, Example 1 is the best choice.

[0047] Figure 5 MnCoSiSn prepared in Comparative Example 1 0.25 MnCoSiSn prepared in Example 1 0.20 MnCoSiSn prepared in Example 2 0.10 MnCoSiSn prepared in Example 3 0.15 The relationship between magnetostriction and magnetic field. It can be seen from Figure 4 that the magnetostrictive material obtained in Example 1 reaches 700 ppm in saturation magnetostriction under a 3T external magnetic field, the magnetostrictive materials obtained in Examples 2 and 3 are both less than 200 ppm in saturation magnetostriction under a 3T external magnetic field, and the magnetostriction value of Comparative Example 1 under a 3T external magnetic field is 700 ppm.

[0048] The above-mentioned Example 1 is a preferred embodiment of the present application, but the embodiments of the present application are not limited by the above-mentioned examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods, which are all included in the protection scope of the present application.

Claims

1. A method for improving the compression performance of MnCoSi-based giant magnetostrictive materials, characterized in that: Sn element is added to the MnCoSi-based giant magnetostrictive material to improve the compression performance of the giant magnetostrictive material. In terms of atomic percentage, the chemical expression of the giant magnetostrictive material after adding Sn element is MnCoSiSn x , x =0.1~0.2, preparing a MnCoSi-based master alloy ingot by vacuum arc melting, and performing vacuum heat treatment to obtain the MnCoSi-based giant magnetostrictive material.

2. The method according to claim 1, wherein x is 0.

20.

3. The method according to claim 1, wherein The specific process is as follows: 1) Prepare ingredients according to the atomic ratio of the chemical expression of the target material; 2) placing the raw materials obtained in step 1) in a vacuum arc melting furnace and repeatedly melting them three times to obtain a MnCoSi-based master alloy ingot; 3) The master alloy ingot is sealed in a quartz tube for heat treatment. The heat treatment steps are as follows: heating to 850°C for 2 hours, then keeping at 850°C for 60 hours, and then slowly cooling to room temperature for 72 hours to finally obtain an ingot with uniform composition and density.

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