Flaky FeMnSiAl-based low-frequency wave-absorbing agent with high ordered phase content and preparation method of flaky FeMnSiAl-based low-frequency wave-absorbing agent

Abstract

The invention discloses a FeMnSiAl substrate-shaped low-frequency wave-absorbing agent with high ordered phase content, which comprises a DO3 ordered phase based on bcc-Fe unit cells, the content of the DO3 phase is 30-50 at.%, and the DO3 ordered phase is a modulation structure formed by arranging two atoms of DO3-FeSiAl and DO3-(Fe, Mn) SiAl. The preparation method comprises the following steps: firstly, doping Mn into bcc-Fe unit cells to form a replacement type solid solution; the preparation method comprises the following steps of: firstly, carrying out heat treatment on the raw materials, then carrying out plastic deformation to introduce shape anisotropy and defects so as to provide energy for atom recombination, and finally, carrying out heat treatment to promote formation of high-temperature ordered phases such as a DO3-FeSiAl superlattice structure and a DO3-(Fe, Mn) SiAl superlattice structure. The problem that the low-frequency wave-absorbing performance of the wave-absorbing material is limited can be effectively solved, the wave-absorbing material has excellent impedance matching and electromagnetic loss, and the microwave absorbing capacity of the wave-absorbing material in the L-S wave band can be improved.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic wave absorbing materials technology, specifically relating to a FeMnSiAl-based sheet-like low-frequency absorbing agent with high ordered phase content and its preparation method. Background Technology

[0002] Faced with the increasing demand for electromagnetic pollution and stealth materials, ideal microwave absorbing materials should possess characteristics such as thinness, light weight, wide bandwidth, and strong absorption. L-band and S-band electromagnetic waves are characterized by long wavelengths and strong penetrating power, making them difficult for materials to effectively absorb. Traditional microwave absorbing materials (such as ferrites and iron carbonyl) require considerable thickness to achieve strong absorption in these bands. FeSiAl alloys, as soft magnetic alloy powders possessing both electrical and magnetic loss mechanisms, have attracted considerable attention due to their high initial permeability and excellent magnetic properties such as saturation magnetization. After high-temperature annealing, they can form a DO3 superlattice structure based on a body-centered cubic unit cell, with Fe, Si, and Al atoms distributed in an L21 symmetric manner, thus exhibiting good isotropy. Currently, the composition of FeSiAl alloys studied by researchers is mostly close to that of Sendust alloys, i.e., 9.6 wt.% Si, 5.4 wt.% Al, and the remainder Fe. This composition is based on the design concept of maximizing the DO3 phase content. It takes into account factors such as long-range disorder in crystal growth and grain refinement. The optimal ratio is achieved by introducing excess Fe and appropriate amounts of Si and Al elements, thus exhibiting extremely low magnetocrystalline anisotropy and magnetostriction coefficient.

[0003] Although FeSiAl alloys theoretically possess excellent electromagnetic properties, they still face some challenges in practical applications. For example, the high complex permittivity of FeSiAl alloys is detrimental to impedance matching. Currently, methods to improve particle impedance matching typically include coating and surface modification. Both coating and surface modification aim to reduce the dielectric constant by decreasing the flow of conductive current between particles. Surface modification and coating are extremely beneficial for improving impedance matching; however, they only focus on the movement of induced current between particles, neglecting the generation of induced current within the particles, which can adversely affect magnetic properties.

[0004] If a low-conductivity element can be found to dope FeSiAl alloys, it can reduce the induced current inside the particles and promote the formation of high-temperature ordered phases in the alloy. This can greatly eliminate the adverse effects of the dopant element on the magnetic permeability, significantly improve the electromagnetic properties of the material, and obtain excellent low-frequency absorbing materials. This is of great significance for expanding the application of electromagnetic wave absorbing materials. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention aims to provide a Mn-doped FeSiAl soft magnetic alloy and its preparation method, which reduces the dielectric constant of the alloy while increasing its magnetic permeability, thereby enhancing its microwave absorption capability in the LS band and effectively solving the problem of limited low-frequency microwave absorption performance of microwave absorbing materials.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A FeMnSiAl-based sheet-like low-frequency microwave absorber with high ordered phase content is prepared by the following steps: (1) Mn doping was performed on FeSiAl alloy to prepare spherical FeMnSiAl alloy micro powder; (2) Perform sheet-like deformation treatment on spherical FeMnSiAl alloy micro powder; (3) The obtained sheet-like FeMnSiAl alloy micro powder was heat-treated to obtain FeMnSiAl-based sheet-like low-frequency absorbing agent with high DO3 ordered phase content.

[0007] According to the above scheme, in step (1), the doping amount of Mn element is 1~10 wt.%.

[0008] According to the above scheme, the original FeSiAl alloy contains 70~90 wt.% Fe, 1~15 wt.% Si, and 1~10 wt.% Al.

[0009] Furthermore, the original FeSiAl alloy also contains element X, which may be one or more of elements such as Cr, Zr, Co, V, Ni, Mo, Ti, Sn, Nb, and Y; the X content is 0~10 wt.%.

[0010] According to the above scheme, in step (1), Mn element can be doped into FeSiAl alloy by melting-atomization method or mechanical alloying method.

[0011] Furthermore, the smelting-atomization process includes the following steps: Fe, Mn, Si, and Al elements are smelted into block ingots under vacuum, placed into crucibles, heated to above 1200℃ under argon atmosphere, and atomized with a gas flow of 2~10 MPa pressure difference to prepare spherical FeMnSiAl alloy micro powder.

[0012] Furthermore, the mechanical alloying process includes the following steps: using FeSiAl powder and Mn powder as the main raw materials, ball milling is carried out for more than 40 hours using high-energy ball milling or planetary ball milling (ball milling rate is 200~500 r / min), separating the grinding balls from the materials and drying them to obtain spherical FeMnSiAl alloy micro powder.

[0013] Furthermore, the FeSiMnAl alloy micro powder is obtained by vacuum melting and spray spheroidization using Fe, Mn, Si and Al as the main raw materials.

[0014] According to the above scheme, in step (1), the spherical FeMnSiAl alloy micro powder prepared has a spherical particle morphology and a powder particle size of less than 100 μm; the phase is a (Fe,Si,Al,Mn,X) solid solution based on bcc-Fe unit cell, containing a small amount of B2 or DO3 phase; the alloy grain size is between 10 and 200 nm.

[0015] According to the above scheme, in step (2), the sheet-like deformation means include stirring ball milling, planetary ball milling or high-energy ball milling.

[0016] Furthermore, the ball milling process used in the sheet-like deformation treatment step is 90~150 r / min and lasts for 12~20 h.

[0017] Furthermore, the sheet-like deformation treatment process employs wet ball milling.

[0018] Furthermore, the ball milling media used in the wet ball milling can be one or more of the following: anhydrous ethanol, cyclohexane, ethylene glycol, propylene glycol, stearic acid, oleic acid, sodium hexametaphosphate, etc.

[0019] According to the above scheme, in step (2), the product particles after deformation are mainly in the form of plates; the size is 5~200 μm and the thickness is 0.3~5 μm; the phase is mainly a (Fe,Si,Al,Mn,X) solid solution based on bcc-Fe unit cells, and the content of B2 or DO3 ordered phases is significantly reduced after deformation; the average grain size of the alloy is 5~30 nm.

[0020] According to the above scheme, in step (3), the heat treatment step uses a holding temperature of 300~800℃; a heating rate of 5~20℃ / min; a holding time of more than 10 min; and the heat treatment atmosphere can be a vacuum environment, a protective atmosphere (such as Ar, N2, etc.) or an atmospheric environment.

[0021] Furthermore, in the heat treatment process, due to the influence of Mn doping, the content of the DO3 phase in the product first increases and then decreases with the increase of the heat treatment holding temperature, preferably 500~600℃; the content of the DO3 phase in the product first increases and then decreases with the increase of the heating rate, preferably 5~15℃ / min; under the condition that the holding time is greater than 10 min, the content of the DO3 phase in the product has no significant relationship with the holding time, and the preferred holding time is 30~150 min.

[0022] The FeMnSiAl sheet-like low-frequency absorber obtained according to the above scheme contains a DO3 ordered phase based on bcc-Fe unit cells, and one or more of the A2 disordered phase and B2 sub-ordered phase based on bcc-Fe unit cells; wherein, the DO3 phase content is 30~50 at.%, and it is a modulation structure with two atomic arrangements, DO3-FeSiAl and DO3-(Fe,Mn)SiAl.

[0023] Furthermore, the saturation magnetization of the FeMnSiAl sheet-like low-frequency absorbing agent is 90~160 emu / g, and the coercivity is less than 20 Oe.

[0024] Furthermore, the peak value of the imaginary part of the complex permeability of the FeMnSiAl sheet-like low-frequency absorbing agent at 1 GHz can be increased from the traditional ~2.3 to 2.8, and the magnetic loss can be increased by more than 20%; the real part of the complex permittivity in the 0.1~10 GHz frequency band can be reduced from ~20.1 to 16.5.

[0025] By combining the FeMnSiAl sheet-like low-frequency absorbing agent described in this invention with a polymer matrix, high-performance absorbing materials for the LS band can be prepared.

[0026] According to the above scheme, the polymer matrix can be selected from one or more of paraffin, epoxy resin, polyurethane, rubber, etc.

[0027] Furthermore, the mass ratio of the FeMnSiAl alloy micro powder to the polymer matrix is ​​1.5~3.0:1.

[0028] Furthermore, FeMnSiAl alloy micro powder was mixed with paraffin at a mass ratio of 1.5 to 2.5:1 to prepare coaxial samples. In the 0.1 to 10 GHz frequency band, the real part of the relative complex permittivity was less than 30, and the peak value of the imaginary part of the relative complex permeability was higher than 2.0.

[0029] Furthermore, FeMnSiAl alloy micro powder and epoxy resin were mixed at a mass ratio of 2.4 to 3.0:1 to prepare coaxial samples. In the 0.1 to 10 GHz frequency band, the real part of the relative complex permittivity was less than 50, and the peak value of the imaginary part of the relative complex permeability was higher than 7.5.

[0030] The principle employed in this invention is as follows: This invention incorporates Mn into FeSiAl alloy systems to promote the formation of the DO3-(Fe,Mn)SiAl phase, replacing the function of excessive bcc-Fe in traditional Sendust alloys that disrupts long-range order and pins grains. First, Mn is incorporated into the bcc-Fe unit cell to form a substitutional solid solution. Then, plastic deformation introduces shape anisotropy to improve the initial magnetic permeability of the alloy powder and generates defects such as vacancies, dislocations, and stacking faults. A suitable amount of defects provides energy for atomic recombination, which is beneficial for Mn atoms to occupy more nucleation sites and reduce phase transformation energy. Finally, heat treatment induces a high-temperature ordered phase transformation in the alloy. Due to the lower system energy, Mn atoms selectively occupy Fe vacancies, forming high-temperature ordered phases such as DO3-FeSiAl and DO3-(Fe,Mn)SiAl superlattice structures.

[0031] This invention, by controlling the alloy composition, degree of plastic deformation, and heat treatment conditions, can maintain the good isotropy of the DO3-(Fe,Mn)SiAl superlattice structure while disrupting the long-range order of the original DO3 phase and pinning and refining the grains during annealing. Compared with traditional Sendust alloy absorbers, this invention utilizes Mn doping to replace excess Fe atoms in the original alloy composition and leverages defects induced by plastic deformation to induce atomic recombination. The increased number of ordered phase nucleation sites leads to a significant increase in the DO3 phase content, promoting an improvement in initial permeability and dynamic complex permeability, thereby enhancing its microwave absorption capability in the LS band.

[0032] Compared with the prior art, the beneficial effects of the present invention include: 1) This invention uses low-conductivity Mn element to dope and modify FeSiAl alloys, which reduces the induced current inside the particles and promotes the formation of two high-temperature ordered phases, DO3-FeSiAl and DO3-(Fe,Mn)SiAl. It significantly increases the content of ordered phases in FeMnSiAl sheet-like low-frequency absorbers, which can effectively improve the peak value of the imaginary part of the permeability in the low-frequency band and reduce the complex permittivity.

[0033] 2) When the FeMnSiAl sheet-like low-frequency absorbing agent of the present invention is combined with a polymer matrix, a reflection loss of <-6 dB can be achieved in the range of 1.6~3.9 GHz, and it can exert excellent absorption performance in the LS band.

[0034] 3) The composition design of Mn doping is conducive to the flexible control of the electromagnetic properties of FeSiAl alloys in the microwave band; while suppressing eddy currents, the complex permeability of the LS band is improved by increasing the content of DO3 ordered phase, which has excellent impedance matching and electromagnetic loss, and is of great significance for the effective absorption of low-frequency microwaves. Attached Figure Description

[0035] Figure 1 Fe in Example 1 81.8 Mn 3.2 Si 9.6 Al 5.4 Scanning electron micrograph of the raw powder; Figure 2 Fe in Example 1 81.8 Mn 3.2 Si 9.6 Al 5.4 Inductively coupled plasma emission spectrum fitting results of the raw powder; Figure 3 Fe in Examples 1-4 and Comparative Example 1 85-x Mn x Si 9.6 Al 5.4 (x = 0, 1.6, 3.2, 4.8, 6.4wt.%) Cu target (K) of raw powder α X-ray diffraction pattern (-1.54060 Å); Figure 4 The Fe obtained after milling for 16 hours in Example 1 81.8 Mn 3.2 Si 9.6 Al 5.4 Scanning electron micrographs of alloy micropowder; Figure 5 The Fe obtained in Example 1 before grinding and after grinding for 8, 12, and 16 hours respectively. 81.8 Mn 3.2 Si 9.6 Al 5.4 Cu target (K) of alloy micro powder α X-ray diffraction pattern (-1.54060 Å); Figure 6 The sheet-like Fe obtained in Examples 1-4 and Comparative Example 1 85-x Mn x Si 9.6 Al 5.4 (x = 0, 1.6, 3.2, 4.8, 6.4 wt.%) Co target (K) of alloy micropowder α X-ray diffraction pattern of -1.78897 Å; Figure 7 The sheet-like Fe obtained in Examples 1-4 and Comparative Example 1 85-x Mn x Si 9.6 Al 5.4 (x = 0, 1.6, 3.2, 4.8, 6.4 wt.%) alloy micronized powder on a Co target (K αPeak intensity ratios of DO3 (111), DO3 / B2 (200), and bcc-Fe (110) crystal planes in X-ray diffraction patterns of -1.78897 Å. Figure 8 The sheet-like Fe obtained in Example 1 81.8 Mn 3.2 Si 9.6 Al 5.4 The Mössbauer spectra of the alloy micropowders and the fitting analysis results are shown in Table 1. Figure 9 The sheet-like Fe obtained in Examples 1-4 and Comparative Example 1 85-x Mn x Si 9.6 Al 5.4 (x = 0, 1.6, 3.2, 4.8, 6.4 wt.%) MH hysteresis loop of alloy micro powder; Figure 10 Electromagnetic parameters of the coaxial samples obtained in Examples 1-4 and Comparative Example 1 in the range of 0.1-10 GHz; Figure 11 The electromagnetic parameters of the coaxial sample obtained in Example 1 are in the range of 0.1~10 GHz; Figure 12 Fe in Example 1 81.8 Mn 3.2 Si 9.6 Al 5.4 Simulated reflection loss of absorbent / polymer composite coating; Figure 13 Fe in Example 2 83.4 Mn 1.6 Si 9.6 Al 5.4 Scanning electron micrograph of the raw powder; Figure 14 Fe obtained in Example 2 83.4 Mn 1.6 Si 9.6 Al 5.4 Scanning electron micrographs of alloy micropowder; Figure 15 Fe in Example 3 80.2 Mn 4.8 Si 9.6 Al 5.4 Scanning electron micrograph of the raw powder; Figure 16 Fe obtained in Example 3 80.2 Mn 4.8 Si 9.6 Al 5.4 Scanning electron micrographs of alloy micropowder; Figure 17Fe in Example 4 78.6 Mn 6.4 Si 9.6 Al 5.4 Scanning electron micrograph of the raw powder; Figure 18 Fe obtained in Example 4 78.6 Mn 6.4 Si 9.6 Al 5.4 Scanning electron micrographs of alloy micropowder; Figure 19 Fe in Example 5 85 Si 9.6 Al 3.8 Mn 1.6 Scanning electron micrograph of the raw powder; Figure 20 Fe in Example 5 85 Si 9.6 Al 3.8 Mn 1.6 Inductively coupled plasma emission spectrum fitting results of the raw powder; Figure 21 Fe obtained in Example 5 85 Si 9.6 Al 3.8 Mn 1.6 Cu target (K) of alloy micro powder α X-ray diffraction pattern (-1.54060 Å); Figure 22 Fe obtained in Example 5 85 Si 9.6 Al 3.8 Mn 1.6 Scanning electron micrographs of alloy micropowder; Figure 23 Flaky Fe obtained under different heat treatment temperature conditions in Example 5 85 Si 9.6 Al 3.8 Mn 1.6 Co target (K) of alloy micro powder α X-ray diffraction pattern of -1.78897 Å; Figure 24 Flaky Fe obtained under different heat treatment temperature conditions in Example 5 85 Si 9.6 Al 3.8 Mn 1.6 MH hysteresis loop of alloy micro powder; Figure 25 Flaky Fe obtained under different heat treatment temperature conditions in Example 5 85 Si 9.6 Al 3.8 Mn1.6 Electromagnetic parameters of coaxial samples made of alloy micropowder in the range of 0.1–10 GHz; Figure 26 For Fe in Comparative Example 1 85 Si 9.6 Al 5.4 Scanning electron micrograph of the raw powder; Figure 27 For Fe in Comparative Example 1 85 Si 9.6 Al 5.4 Inductively coupled plasma emission spectrum fitting results of the raw powder; Figure 28 Fe obtained under different milling conditions in Comparative Example 1 85 Si 9.6 Al 5.4 Cu target (K) of alloy micro powder α - 1.54060 Å) X-ray diffraction pattern; Figure 29 Fe obtained for Comparative Example 1 85 Si 9.6 Al 5.4 Scanning electron micrographs of alloy micropowder; Figure 30 The flaky Fe obtained in Comparative Example 1 85 Si 9.6 Al 5.4 Mössbauer spectra of alloy micropowders and fitting analysis results; Figure 31 Fe obtained for Comparative Example 2 81.8 Mn 3.2 Si 9.6 Al 5.4 Scanning electron micrographs of alloy micropowder; Figure 32 The flaky Fe obtained in Comparative Example 2 81.8 Mn 3.2 Si 9.6 Al 5.4 Cu target (K) of alloy micro powder α - 1.54060 Å) X-ray diffraction pattern; Figure 33 The flaky Fe obtained in Comparative Example 2 81.8 Mn 3.2 Si 9.6 Al 5.4 Co target (K) of alloy micro powder before heat treatment at 600℃ α X-ray diffraction pattern of -1.78897 Å; Figure 34 The electromagnetic parameters of the coaxial sample obtained in Comparative Example 2 are shown in the range of 0.1 to 10 GHz. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0037] Example 1 A FeMnSiAl-based sheet-like low-frequency microwave absorber with high ordered phase content is prepared by the following steps: (1) Fe, Mn, Si, and Al in bulk or sheet form at a mass ratio of 81.8:3.2:9.6:5.4 were placed in the sample pit of a vacuum arc melting furnace. The vacuum level of the system was evacuated to below 5 × 10⁻⁶ using a mechanical pump and a molecular pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to bring the gas pressure to -0.05 MPa. An arc is ignited using a current of 100~250 A and the mixture is melted in magnetic stirring mode. The mixture is then flipped over and the process is repeated 3~5 times, followed by cooling. The FeMnSiAl alloy ingots obtained from the smelting were then loaded into a quartz nozzle and placed in a gas atomization alloy powder making device. The vacuum degree of the system was evacuated to below 3 × 10⁻⁶ using a mechanical pump and a diffusion pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to achieve a pressure of 7.0~10 MPa. The ingot is heated to 1450~1600℃ by electromagnetic induction with copper wire, and the alloy solution is held at this temperature for more than 2 minutes. The alloy solution is then sprayed out with a pressure difference of 0.02~0.05 MPa to form spherical FeMnSiAl powder. The powder is then ultrasonically sieved through a 250-mesh sieve for more than 5 minutes. The material passing through the 250-mesh sieve is collected to obtain the original spherical FeMnSiAl powder. (2) Take the obtained spherical FeMnSiAl raw powder, weigh 10 g and put it into a grinding jar. Add 800 g of ZrO2 balls with a diameter of 6 mm (>95%) at a ball-to-material mass ratio of 80:1, and add 70 g of anhydrous ethanol (analytical grade) as a process control agent. Set the grinding mill to unidirectional rotation mode, set the grinding time to 16 h, and the rotation speed frequency to 10 Hz (120 r / min). After grinding, separate the ZrO2 grinding balls and the ethanol / powder mixture with a 60-mesh sieve, then use a magnet to adsorb the ethanol / powder mixture and pour off the supernatant. Put the remaining powder into an oven, set the drying temperature to 60℃, and the drying time to not less than 3 h. Obtain flaky FeMnSiAl alloy micro powder. (3) The obtained flake-shaped FeMnSiAl alloy micro powder was poured into a ceramic boat and heat-treated in a tube furnace: a mechanical pump was used to evacuate the air pressure to a level below 1×10⁻⁶. -1 Pa and pressurize for 30 min to ensure good airtightness; under vacuum, set the heating rate to rise from room temperature to 600℃ at 10℃ / min and hold for 2 h, then allow to cool naturally to room temperature.

[0038] Figure 1 To prepare spherical Fe by gas atomization 81.8 Mn 3.2 Si 9.6 Al 5.4 Scanning electron micrographs of the original powder show that the powder is basically in the shape of regular spheres; statistically, the particle size ranges from 3 to 54 μm, and the average particle size is about 15.7 μm. Figure 2 To prepare spherical Fe by gas atomization 81.8 Mn 3.2 Si 9.6 Al 5.4 The inductively coupled plasma atomic emission spectrometry (ICP-AES) fitting analysis of the original powder showed that the contents of Fe, Mn, Si, and Al were 81.4285 wt.%, 3.0833 wt.%, 9.3521 wt.%, and 5.2637 wt.%, respectively, which were basically consistent with the designed composition. The alloy contained trace amounts of Co, Ni, Cr, and other elements. Figure 3 To prepare spherical Fe by gas atomization 81.8 Mn 3.2 Si 9.6 Al 5.4 Cu target (K) of the original powder α The X-ray diffraction pattern (-1.54060 Å) shows that the original powder contains a bcc-Fe lattice, and that Si, Al, and Mn elements enter the bcc-Fe lattice in the form of substitutional solid solutions; there are also some B2 and DO3 superlattice structures.

[0039] Figure 4 Fe after 16 h of grinding 81.8 Mn 3.2 Si 9.6 Al 5.4 Scanning electron micrographs of alloy micropowder, showing Fe after stirring. 81.8 Mn 3.2 Si 9.6 Al 5.4 The particles are all in the form of plates or disks, with an average plate diameter of about 19.6 μm and a particle thickness of 0.3~2 μm. Figure 5 Fe after grinding for different durations 81.8 Mn 3.2 Si 9.6 Al5.4 Cu target (K) of alloy micro powder α - 1.54060 Å) X-ray diffraction pattern, showing Fe 81.8 Mn 3.2 Si 9.6 Al 5.4 After grinding, the alloy powder contains only the bcc-(Fe,Mn,Si,Al) phase.

[0040] Figure 6 Flaky Fe after heat treatment 81.8 Mn 3.2 Si 9.6 Al 5.4 Co target (K) of alloy micro powder α - 1.78897 Å) X-ray diffraction pattern, showing Fe 81.8 Mn 3.2 Si 9.6 Al 5.4 The alloy micro powder contains DO3 ordered phase and a small amount of Fe oxides (Fe3O4, Fe2O3); the characteristic peaks of the DO3 phase all shifted significantly to lower angles, indicating that the atomic occupancy of the DO3 ordered phase changed, resulting in an increase in the lattice constant.

[0041] Figure 7 Flaky Fe after heat treatment 81.8 Mn 3.2 Si 9.6 Al 5.4 Alloy micropowder in Co target (K α The peak intensity ratios of the DO3 (111), DO3, and bcc-Fe (110) crystal planes in the X-ray diffraction pattern at -1.78897 Å show that Mn doping increases the relative peak intensity of the DO3 characteristic peak by ~40%, indicating that Fe... 81.8 Mn 3.2 Si 9.6 Al 5.4 The DO3 phase content in the alloy micro powder increased significantly. Figure 8 Flaky Fe after heat treatment 81.8 Mn 3.2 Si 9.6 Al 5.4The Mössbauer spectra of the alloy micropowder, and the fitting analysis results are shown in Table 1. The increased Fe(4) occupancy and decreased Fe(6) occupancy in the Fe atoms of the sample indicate an increase in the DO3 phase content. The decreased Fe(8) occupancy indicates that, in addition to containing DO3-FeSiAl, the body-centered Fe atoms in the superlattice are replaced by doped atoms. Mn atoms tend to occupy the body-centered Fe sites in the DO3-(Fe,Mn)SiAl superlattice structure and promote the DO3 phase transformation, affecting the magnetic order of the alloy. The peak area of ​​the Fe(4) sub-spectrum increased from 44.8% to 49.3%, while the peak area of ​​the Fe(6) sub-spectrum decreased from 7.0% to 5.3%, indicating that the DO3 phase content is nearly 50 at.%, an increase of over 10% compared to the undoped FeSiAl described in Comparative Example 1. The strong preferential substitution tendency of Mn atoms for body-centered Fe atoms indicates the presence of a dual DO3 phase modulation structure in the sample.

[0042] Table 1. Flaky Fe 81.8 Mn 3.2 Si 9.6 Al 5.4 Mössbauer spectrum fitting results of alloy micro powder (χ²) 2 = 1.51)

[0043] Figure 9 Flaky Fe after heat treatment 81.8 Mn 3.2 Si 9.6 Al 5.4 The MH hysteresis loop of the alloy micro powder shows that Fe 81.8 Mn 3.2 Si 9.6 Al 5.4 The alloy micro powder exhibits good soft magnetic properties; Mn doping can effectively improve the initial magnetic permeability of the alloy.

[0044] The FeMnSiAl flake-shaped low-frequency absorbing agent obtained in this embodiment was mixed with sliced ​​paraffin at a mass ratio of 2:1 to prepare a coaxial sample. Figure 10 Flaky Fe after heat treatment 81.8 Mn 3.2 Si 9.6 Al 5.4 Dynamic electromagnetic parameters of the alloy micropowder, measured using the coaxial method, show that appropriate Mn substitution for Fe doping can effectively reduce the conductivity and complex permittivity of the alloy particles, and its promoting effect on the DO3 phase transition can effectively improve the complex permeability. The heat-treated sheet-like Fe... 81.8 Mn 3.2 Si 9.6 Al 5.4Alloy micro powder and polymer matrix are mixed at a mass ratio of 2.6:1 and sprayed into a coating with a thickness of 0.5~1.5 mm. After the coating is cured, it is engraved into a coaxial sample. Figure 11 Flaky Fe after heat treatment 81.8 Mn 3.2 Si 9.6 Al 5.4 The electromagnetic parameters of the coaxial composite-coated samples in the range of 0.1–10 GHz show that the real part of the relative complex permittivity is less than 40 and the peak value of the imaginary part of the relative complex permeability reaches 8.0. While obtaining a low complex permittivity, extremely high complex permeability is obtained through a highly ordered phase. Figure 12 Flaky Fe after heat treatment 81.8 Mn 3.2 Si 9.6 Al 5.4 Simulated reflection loss of the composite coating shows that a reflection loss of <-6 dB can be achieved in the range of 1.6 to 3.9 GHz with a thickness of 1.5 mm.

[0045] Example 2 A FeMnSiAl-based sheet-like low-frequency microwave absorber with high ordered phase content is prepared by the following steps: (1) Fe, Mn, Si, and Al in bulk or sheet form at a mass ratio of 83.4:1.6:9.6:5.4 were placed in the sample pit of a vacuum arc melting furnace. The vacuum level of the system was evacuated to below 5 × 10⁻⁶ using a mechanical pump and a molecular pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to bring the gas pressure to -0.05 MPa. An arc is ignited using a current of 100~250 A and the mixture is melted in magnetic stirring mode. The mixture is then flipped over and the process is repeated 3~5 times, followed by cooling. The FeMnSiAl alloy ingots obtained from the smelting were then loaded into a quartz nozzle and placed in a gas atomization alloy powder making device. The vacuum degree of the system was evacuated to below 3 × 10⁻⁶ using a mechanical pump and a diffusion pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to achieve a pressure of 7.0~10 MPa. The ingot is heated to 1450~1600℃ by electromagnetic induction with copper wire, and the alloy solution is held at this temperature for more than 2 minutes. The alloy solution is then sprayed out with a pressure difference of 0.02~0.05 MPa to form spherical FeMnSiAl powder. The powder is then ultrasonically sieved through a 250-mesh sieve for more than 5 minutes. The material passing through the 250-mesh sieve is collected to obtain the original spherical FeMnSiAl powder. (2) Take the obtained spherical FeMnSiAl raw powder, weigh 10 g and put it into a grinding jar. Add 800 g of ZrO2 balls with a diameter of 6 mm (>95%) at a ball-to-material mass ratio of 80:1, and add 70 g of anhydrous ethanol (analytical grade) as a process control agent. Set the grinding mill to unidirectional rotation mode, set the grinding time to 16 h, and the rotation speed frequency to 10 Hz (120 r / min). After stirring, separate the ZrO2 grinding balls and the ethanol / powder mixture using a 60-mesh sieve. Then, use a magnet to adsorb the ethanol / powder mixture and pour off the supernatant. Put the remaining powder into an oven and set the drying temperature to 60℃ for a drying time of not less than 3 h. Obtain the flake-shaped FeMnSiAl alloy micro powder. (3) The obtained flake-shaped FeMnSiAl alloy micro powder was poured into a ceramic boat and heat-treated in a tube furnace: a mechanical pump was used to evacuate the air pressure to a level lower than 1×10⁻⁶. -1 Pa and pressurize for 30 min to ensure good airtightness; under vacuum, set the heating rate to rise from room temperature to 600℃ at 10℃ / min and hold for 2 h, then allow to cool naturally to room temperature.

[0046] Figure 13 To prepare spherical Fe by gas atomization 83.4 Mn 1.6 Si 9.6 Al 5.4 Scanning electron micrographs of the original powder show that the powder is basically in the shape of regular spheres; statistically, the particle size ranges from 3 to 45 μm, and the average particle size is about 15.3 μm. Figure 3 To prepare spherical Fe by gas atomization 83.4 Mn 1.6 Si 9.6 Al 5.4 Cu target (K) of the original powder α The X-ray diffraction pattern (-1.54060 Å) shows that the original powder contains a bcc-Fe lattice, and that Si, Al, and Mn elements enter the bcc-Fe lattice in the form of substitutional solid solutions; there is a partial B2 phase, but the DO3 phase content is low.

[0047] Figure 14 Fe after 16 h of grinding 83.4 Mn 1.6 Si 9.6 Al 5.4 Scanning electron micrographs of alloy micropowder, showing Fe after stirring. 83.4 Mn 1.6 Si 9.6 Al 5.4 The particles are all in the form of plates or disks, with an average plate diameter of about 19.7 μm and a particle thickness of 0.3~2 μm.

[0048] Figure 6 Flaky Fe after heat treatment 83.4 Mn 1.6 Si 9.6 Al 5.4 Co target (K) of alloy micro powder α - 1.78897 Å) X-ray diffraction pattern, showing Fe 83.4 Mn 1.6 Si 9.6 Al 5.4 The alloy powder contains an ordered DO3 phase and a small amount of Fe oxide. Figure 7 Flaky Fe after heat treatment 83.4 Mn 1.6 Si 9.6 Al 5.4 Alloy micropowder in Co target (K α The peak intensity ratios of the DO3(111), DO3, and bcc-Fe(110) crystal planes in the X-ray diffraction pattern at -1.78897 Å show that Mn doping increases the relative peak intensity of the DO3 characteristic peak by more than 15%, indicating that Fe... 83.4 Mn 1.6 Si 9.6 Al 5.4 The DO3 phase content in the alloy micro powder increased significantly. Figure 9 Flaky Fe after heat treatment 83.4 Mn 1.6 Si 9.6 Al 5.4 The MH hysteresis loop of the alloy micro powder shows that Fe 83.4 Mn 1.6 Si 9.6 Al 5.4 The alloy micro powder exhibits excellent soft magnetic properties.

[0049] The FeMnSiAl flake-shaped low-frequency absorbing agent obtained in this embodiment was mixed with sliced ​​paraffin at a mass ratio of 2:1 to prepare a coaxial sample. Figure 10 Flaky Fe after heat treatment 83.4 Mn 1.6 Si 9.6 Al 5.4 Dynamic electromagnetic parameters of the alloy micropowder, measured by the coaxial method, show that appropriate Mn substitution for Fe doping can effectively reduce the conductivity and complex permittivity of alloy particles while maintaining high complex permeability by promoting the DO3 phase transition.

[0050] Example 3 A FeMnSiAl-based sheet-like low-frequency microwave absorber with high ordered phase content is prepared by the following steps: (1) Fe, Mn, Si, and Al in bulk or sheet form at a mass ratio of 80.2:4.8:9.6:5.4 were placed in the sample pit of a vacuum arc melting furnace. The vacuum level of the system was evacuated to below 5 × 10⁻⁶ using a mechanical pump and a molecular pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to bring the gas pressure to -0.05 MPa. An arc is ignited using a current of 100~250 A and the mixture is melted in magnetic stirring mode. The mixture is then flipped over and the process is repeated 3~5 times, followed by cooling. The FeMnSiAl alloy ingots obtained from the smelting were then loaded into a quartz nozzle and placed in a gas atomization alloy powder making device. The vacuum degree of the system was evacuated to below 3 × 10⁻⁶ using a mechanical pump and a diffusion pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to achieve a pressure of 7.0~10 MPa. The ingot is heated to 1450~1600℃ by electromagnetic induction with copper wire, and the alloy solution is held at this temperature for more than 2 minutes. The alloy solution is then sprayed out with a pressure difference of 0.02~0.05 MPa to form spherical FeMnSiAl powder. The powder is then ultrasonically sieved through a 250-mesh sieve for more than 5 minutes. The material passing through the 250-mesh sieve is collected to obtain the original spherical FeMnSiAl powder. (2) Take the obtained spherical FeMnSiAl raw powder, weigh 10 g and put it into a grinding jar. Add 800 g of ZrO2 balls with a diameter of 6 mm (>95%) at a ball-to-material mass ratio of 80:1, and add 70 g of anhydrous ethanol (analytical grade) as a process control agent. Set the grinding mill to unidirectional rotation mode, set the grinding time to 16 h, and the rotation speed frequency to 10 Hz (120 r / min). After grinding, separate the ZrO2 grinding balls and the ethanol / powder mixture with a 60-mesh sieve, then use a magnet to adsorb the ethanol / powder mixture and pour off the supernatant. Put the remaining powder into an oven, set the drying temperature to 60℃, and the drying time to not less than 3 h. Obtain flaky FeMnSiAl alloy micro powder. (3) The obtained flake-shaped FeMnSiAl alloy micro powder was poured into a ceramic boat and heat-treated in a tube furnace: a mechanical pump was used to evacuate the air pressure to a level lower than 1×10⁻⁶. -1 Pa and pressurize for 30 min to ensure good airtightness; under vacuum, set the heating rate to rise from room temperature to 600℃ at 10℃ / min and hold for 2 h, then allow to cool naturally to room temperature.

[0051] Figure 15 To prepare spherical Fe by gas atomization 80.2 Mn 4.8 Si 9.6 Al 5.4 Scanning electron micrographs of the original powder show that the powder is basically in the shape of regular spheres; statistically, the particle size ranges from 3 to 48 μm, and the average particle size is about 15.3 μm. Figure 3 To prepare spherical Fe by gas atomization 80.2 Mn 4.8 Si 9.6 Al 5.4 Cu target (K) of the original powder α The X-ray diffraction pattern (-1.54060 Å) shows that the original powder contains a bcc-Fe lattice, and that Si, Al, and Mn elements enter the bcc-Fe lattice in the form of substitutional solid solutions; there are also some B2 or DO3 superlattice structures.

[0052] Figure 16 Fe after 16 h of grinding 80.2 Mn 4.8 Si 9.6 Al 5.4 Scanning electron micrographs of alloy micropowder, showing Fe after stirring. 80.2 Mn 4.8 Si 9.6 Al 5.4 The particles are all in the form of plates or disks, with an average plate diameter of about 19.3 μm and a particle thickness of 0.3~2 μm.

[0053] Figure 6 Flaky Fe after heat treatment 80.2 Mn 4.8 Si 9.6 Al 5.4 Co target (K) of alloy micro powder α - 1.78897 Å) X-ray diffraction pattern, showing Fe 80.2 Mn 4.8 Si 9.6 Al 5.4 The alloy powder contains an ordered DO3 phase and a small amount of Fe oxide. Figure 7 Flaky Fe after heat treatment 80.2 Mn 4.8 Si 9.6 Al 5.4 Alloy micropowder in Co target (K α The peak intensity ratio of the DO3(111), DO3 and bcc-Fe(110) crystal planes in the X-ray diffraction pattern of -1.78897 Å shows that Mn doping makes the relative peak intensity of the DO3 characteristic peak exceed 3.5%. Figure 9 Flaky Fe after heat treatment 80.2 Mn 4.8 Si 9.6 Al 5.4 The MH hysteresis loop of the alloy micro powder shows that Fe 80.2 Mn 4.8 Si 9.6 Al 5.4 The alloy micro powder exhibits excellent soft magnetic properties.

[0054] The FeMnSiAl flake-shaped low-frequency absorbing agent obtained in this embodiment was mixed with sliced ​​paraffin at a mass ratio of 2:1 to prepare a coaxial sample. Figure 10 Flaky Fe after heat treatment 80.2 Mn 4.8 Si 9.6 Al 5.4 Dynamic electromagnetic parameters of the alloy micropowder, measured by the coaxial method, show that appropriate Mn substitution for Fe doping can effectively reduce the conductivity and complex permittivity of the alloy particles while maintaining high complex permeability.

[0055] Example 4 A FeMnSiAl-based sheet-like low-frequency microwave absorber with high ordered phase content is prepared by the following steps: (1) Fe, Mn, Si, and Al in bulk or sheet form at a mass ratio of 78.6:6.4:9.6:5.4 were placed in the sample pit of a vacuum arc melting furnace. The vacuum level of the system was evacuated to below 5 × 10⁻⁶ using a mechanical pump and a molecular pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to bring the gas pressure to -0.05 MPa. An arc is ignited using a current of 100~250 A and the mixture is melted in magnetic stirring mode. The mixture is then flipped over and the process is repeated 3~5 times, followed by cooling. The FeMnSiAl alloy ingots obtained from the smelting were then loaded into a quartz nozzle and placed in a gas atomization alloy powder making device. The vacuum degree of the system was evacuated to below 3 × 10⁻⁶ using a mechanical pump and a diffusion pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to achieve a pressure of 7.0~10 MPa. The ingot is heated to 1450~1600℃ by electromagnetic induction with copper wire, and the alloy solution is held at this temperature for more than 2 minutes. The alloy solution is then sprayed out with a pressure difference of 0.02~0.05 MPa to form spherical FeMnSiAl powder. The powder is then ultrasonically sieved through a 250-mesh sieve for more than 5 minutes. The material passing through the 250-mesh sieve is collected to obtain the original spherical FeMnSiAl powder. (2) Take the obtained spherical FeMnSiAl raw powder, weigh 10 g and put it into a grinding jar. Add 800 g of ZrO2 balls with a diameter of 6 mm (>95%) at a ball-to-material mass ratio of 80:1, and add 70 g of anhydrous ethanol (analytical grade) as a process control agent. Set the grinding mill to unidirectional rotation mode, set the grinding time to 16 h, and the rotation speed frequency to 10 Hz (120 r / min). After grinding, separate the ZrO2 grinding balls and the ethanol / powder mixture with a 60-mesh sieve, then use a magnet to adsorb the ethanol / powder mixture and pour off the supernatant. Put the remaining powder into an oven, set the drying temperature to 60℃, and the drying time to not less than 3 h. Obtain flaky FeMnSiAl alloy micro powder. (3) The obtained flake-shaped FeMnSiAl alloy micro powder was poured into a ceramic boat and heat-treated in a tube furnace: a mechanical pump was used to evacuate the air pressure to a level lower than 1×10⁻⁶. -1 Pa and pressurize for 30 min to ensure good airtightness; under vacuum, set the heating rate to rise from room temperature to 600℃ at 10℃ / min and hold for 2 h, then allow to cool naturally to room temperature.

[0056] Figure 17 To prepare spherical Fe by gas atomization 78.6 Mn 6.4 Si 9.6 Al 5.4 Scanning electron micrographs of the original powder show that the powder is basically in the shape of regular spheres; statistically, the particle size ranges from 3 to 45 μm, and the average particle size is about 15.4 μm. Figure 3 To prepare spherical Fe by gas atomization 78.6 Mn 6.4 Si 9.6 Al 5.4 Cu target (K) of the original powder α The X-ray diffraction pattern (-1.54060 Å) shows that the original powder contains a bcc-Fe lattice, and that Si, Al, and Mn elements enter the bcc-Fe lattice in the form of substitutional solid solutions; there are also some B2 or DO3 superlattice structures.

[0057] Figure 18 Fe after 16 h of grinding 78.6 Mn 6.4 Si 9.6 Al 5.4 Scanning electron micrographs of alloy micropowder, showing Fe after stirring. 78.6 Mn 6.4 Si 9.6 Al 5.4 The particles are all in the form of plates or disks, with an average plate diameter of about 19.4 μm and a particle thickness of 0.3~2 μm.

[0058] Figure 6 Flaky Fe after heat treatment 78.6 Mn 6.4 Si 9.6 Al 5.4 Co target (K) of alloy micro powder α - 1.78897 Å) X-ray diffraction pattern, showing Fe 78.6 Mn 6.4 Si 9.6 Al 5.4 The alloy powder contains an ordered DO3 phase and a small amount of Fe oxide. Figure 7 Flaky Fe after heat treatment 78.6 Mn 6.4Si 9.6 Al 5.4 Alloy micropowder in Co target (K α The peak intensity ratio of the DO3(111), DO3 and bcc-Fe(110) crystal planes in the X-ray diffraction pattern of -1.78897 Å shows that Mn doping increases the relative peak intensity of the DO3 characteristic peak to 4.8%. Figure 9 Flaky Fe after heat treatment 78.6 Mn 6.4 Si 9.6 Al 5.4 The MH hysteresis loop of the alloy micro powder shows that Fe 78.6 Mn 6.4 Si 9.6 Al 5.4 The alloy micro powder exhibits excellent soft magnetic properties.

[0059] The FeMnSiAl flake-shaped low-frequency absorbing agent obtained in this embodiment was mixed with sliced ​​paraffin at a mass ratio of 2:1 to prepare a coaxial sample. Figure 10 Flaky Fe after heat treatment 78.6 Mn 6.4 Si 9.6 Al 5.4 Dynamic electromagnetic parameters of the alloy micropowder, measured by the coaxial method, show that appropriate Mn substitution for Fe doping can effectively reduce the conductivity and complex permittivity of the alloy particles while maintaining high complex permeability.

[0060] Example 5 A FeMnSiAl-based sheet-like low-frequency microwave absorber with high ordered phase content is prepared by the following steps: (1) Fe, Si, Al, and Mn in bulk or sheet form at a mass ratio of 85:9.6:3.8:1.6 are placed in the sample pit of a vacuum arc melting furnace. The vacuum level of the system is evacuated to below 5×10⁻⁶ using a mechanical pump and a molecular pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to bring the gas pressure to -0.05 MPa. An arc is ignited using a current of 100~250 A and the mixture is melted in magnetic stirring mode. The mixture is then flipped over and the process is repeated 3~5 times, followed by cooling. The FeSiAlMn alloy ingots obtained from the smelting process were then loaded into a quartz nozzle and placed in a gas atomization alloy powder making device. The vacuum degree of the system was then evacuated to below 3 × 10⁻⁶ using a mechanical pump and a diffusion pump. -3After Pa, high-purity argon gas (99.999%) is introduced to achieve a pressure of 7.0~10 MPa. The ingot is heated to 1450~1600℃ by electromagnetic induction with copper wire, and the alloy solution is held at this temperature for more than 2 minutes. The alloy solution is then sprayed out with a pressure difference of 0.02~0.05 MPa to form spherical FeSiAlMn powder. The powder is then ultrasonically sieved through a 250-mesh sieve for more than 5 minutes. The material passing through the 250-mesh sieve is collected to obtain the original spherical FeMnSiAl powder. (2) Take the obtained spherical FeSiAlMn raw powder, weigh 10 g and put it into a grinding jar. Add 800 g of ZrO2 balls with a diameter of 6 mm (>95%) at a ball-to-material mass ratio of 80:1, and add 70 g of anhydrous ethanol (analytical grade) as a process control agent. Set the grinding mill to unidirectional rotation mode, set the grinding time to 20 h, and the rotation speed frequency to 10 Hz (120 r / min). After grinding, separate the ZrO2 grinding balls and the ethanol / powder mixture using a 60-mesh sieve. Then, use a magnet to adsorb the ethanol / powder mixture and pour off the supernatant. Put the remaining powder into an oven, set the drying temperature to 60℃, and the drying time to not less than 3 h. Obtain flaky FeMnSiAl alloy micro powder. (3) The obtained flake-shaped FeSiAlMn alloy micro powder was poured into a ceramic boat and heat-treated in a tube furnace: a mechanical pump was used to evacuate the air pressure to a level lower than 1×10⁻⁶. -1 Pa and pressurize for 30 min to ensure good airtightness; under vacuum, set the heating rate to 10℃ / min to raise the temperature from room temperature to 300℃, 400℃, 500℃, 600℃ and 700℃ respectively and hold for 2 h, then let it cool naturally to room temperature.

[0061] Figure 19 To prepare spherical Fe by gas atomization 85 Si 9.6 Al 3.8 Mn 1.6 Scanning electron micrographs of the original powder show that the powder is basically in the shape of regular spheres; statistically, the particle size ranges from 3 to 57 μm, and the average particle size is about 15.9 μm. Figure 20 To prepare spherical Fe by gas atomization 85 Si 9.6 Al 3.8 Mn 1.6 The inductively coupled plasma atomic emission spectrometry (ICP-AES) fitting analysis of the original powder showed that the contents of Fe, Si, Al, and Mn were 85.2115 wt.%, 9.4807 wt.%, 3.7288 wt.%, and 1.5790 wt.%, respectively, which were basically consistent with the designed composition. The alloy contained trace amounts of impurity elements such as Co, Ni, and Cr. Figure 21 Fe before and after 16 h of grinding 85Si 9.6 Al 3.8 Mn 1.6 Cu target (K) of alloy micro powder α X-ray diffraction pattern at -1.54060 Å shows Fe 85 Si 9.6 Al 3.8 Mn 1.6 The original powder contained a bcc-Fe lattice, with Si, Al, and Mn elements entering the bcc-Fe lattice in the form of substitutional solid solutions, and some B2 and DO3 ordered phases were also present; the plate-like Fe after stirring and grinding... 85 Si 9.6 Al 3.8 Mn 1.6 The alloy micro powder contains only the bcc-(Fe,Si,Al,Mn) phase, and its internal stress is significantly increased and its grain size is refined. Figure 22 The flaky Fe after grinding for 16 hours 85 Si 9.6 Al 3.8 Mn 1.6 Scanning electron micrographs of alloy micropowder, showing Fe 85 Si 9.6 Al 3.8 Mn 1.6 The particles are all in the form of plates or disks, with an average plate diameter of about 18.7 μm and a particle thickness of 0.3~2 μm.

[0062] Figure 23 Flaky Fe before and after heat treatment at different temperatures 85 Si 9.6 Al 3.8 Mn 1.6 Co target (K) of alloy micro powder α X-ray diffraction pattern (-1.78897 Å) shows that Fe... 85 Si 9.6 Al 3.8 Mn 1.6 The alloy micro powder can undergo a transformation from the disordered A2 phase of bcc-(Fe,Si,Al,Mn) to the sub-ordered B2 phase and then to the ordered DO3 phase; and the content of the ordered DO3 phase is relatively high when the heat treatment temperature is 500℃ and 600℃; at the same time, the heat treatment at high temperature is accompanied by a trace oxidation of Fe. Figure 24 Fe before and after heat treatment at 300℃, 400℃, 500℃, 600℃, and 700℃ 85 Si 9.6 Al 3.8 Mn 1.6The MH hysteresis loop of the alloy micropowder shows that the FeSiAlMn alloy micropowder exhibits good soft magnetic properties; Mn doping can effectively improve the initial permeability of the alloy.

[0063] Coaxial samples were prepared by heating and mixing FeMnSiAl flake-shaped low-frequency absorbing agents obtained at different heat treatment temperatures with sliced ​​paraffin at a mass ratio of 2:1. Figure 25 Flaky Fe before and after heat treatment 85 Si 9.6 Al 3.8 Mn 1.6 Dynamic electromagnetic parameters of the alloy micropowder measured by the coaxial method show that appropriate Mn doping can effectively reduce the conductivity and complex permittivity of the alloy particles in the range of 0.1 to 10 GHz, with the real part of the relative complex permittivity being less than 30; and its promoting effect on the DO3 phase transition can effectively improve the complex permeability, with the imaginary part of the relative complex permeability reaching a peak value of nearly 2.5 at ~1 GHz.

[0064] Example 6 A FeMnSiAl-based sheet-like low-frequency microwave absorber with high ordered phase content is prepared by the following steps: (1) Five elemental materials, Fe, Mn, Si, Cr, and Al, in bulk or sheet form, were placed in the sample pit of a vacuum arc melting furnace at a mass ratio of 81.8:3.2:6.4:3.2:5.4. The vacuum level of the system was evacuated to below 5 × 10⁻⁶ using a mechanical pump and a molecular pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to bring the gas pressure to -0.05 MPa. An arc is ignited using a current of 100~250 A and the mixture is melted in magnetic stirring mode. The mixture is then flipped over and the process is repeated 3~5 times, followed by cooling. The FeMnSiAl-Cr alloy ingots obtained from the smelting process were then loaded into a quartz nozzle and placed in a gas atomization alloy powder making device. The vacuum degree of the system was then evacuated to below 3 × 10⁻⁶ using a mechanical pump and a diffusion pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to achieve a pressure of 7.0~10 MPa. The ingot is heated to 1450~1600℃ by electromagnetic induction with copper wire, and the alloy solution is held at this temperature for more than 2 minutes. The alloy solution is then sprayed out with a pressure difference of 0.02~0.05 MPa to form spherical FeMnSiAl-Cr powder. The powder is then ultrasonically sieved through a 250-mesh sieve for more than 5 minutes. The material passing through the 250-mesh sieve is collected to obtain the original spherical FeMnSiAl powder. (2) Take the obtained spherical FeMnSiAl-Cr raw powder, weigh 10 g and put it into a grinding jar. Add 800 g of ZrO2 balls with a diameter of 6 mm (>95%) at a ball-to-material mass ratio of 80:1, and add 70 g of anhydrous ethanol (analytical grade) as a process control agent. Set the grinding mill to unidirectional rotation mode, set the grinding time to 20 h, and the rotation speed frequency to 10 Hz (120 r / min). After grinding, separate the ZrO2 grinding balls and the ethanol / powder mixture using a 60-mesh sieve. Then, use a magnet to adsorb the ethanol / powder mixture and pour off the supernatant. Put the remaining powder into an oven and set the drying temperature to 60℃ for a drying time of not less than 3 h. Obtain the flake-shaped FeMnSiAl alloy micro powder. (3) The obtained flaky FeMnSiAl-Cr alloy powder was poured into a ceramic boat and heat-treated in a tube furnace: a mechanical pump was used to evacuate the air pressure to a level below 1×10⁻⁶. -1 Pa and pressurize for 30 min to ensure good airtightness; under vacuum, set the heating rate to rise from room temperature to 600℃ at 10℃ / min and hold for 2 h, then allow to cool naturally to room temperature.

[0065] Example 7 A FeMnSiAl-based sheet-like low-frequency microwave absorber with high ordered phase content is prepared by the following steps: (1) Five elemental materials, Fe, Mn, Si, Ti, and Al, in bulk or sheet form, were placed in the sample pit of a vacuum arc melting furnace in a mass ratio of 81.8:3.2:8.4:1.2:5.4. The vacuum level of the system was evacuated to below 5 × 10⁻⁶ using a mechanical pump and a molecular pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to bring the gas pressure to -0.05 MPa. An arc is ignited using a current of 100~250 A and the mixture is melted in magnetic stirring mode. The mixture is then flipped over and the process is repeated 3~5 times, followed by cooling. The FeMnSiAl-Ti alloy ingots obtained from the smelting process were then loaded into a quartz nozzle and placed in a gas atomization alloy powder making device. The vacuum degree of the system was then evacuated to below 3 × 10⁻⁶ using a mechanical pump and a diffusion pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to achieve a pressure of 7.0~10 MPa. The ingot is heated to 1450~1600℃ by electromagnetic induction with copper wire, and the alloy solution is held at this temperature for more than 2 minutes. The alloy solution is then sprayed out with a pressure difference of 0.02~0.05 MPa to form spherical FeMnSiAl-Ti powder. The powder is then ultrasonically sieved through a 250-mesh sieve for more than 5 minutes. The material passing through the 250-mesh sieve is collected to obtain the original spherical FeMnSiAl-Ti powder. (2) Take the obtained spherical FeMnSiAl-Ti raw powder, weigh 10 g and put it into a grinding jar. Add 800 g of ZrO2 balls with a diameter of 6 mm (>95%) at a ball-to-material mass ratio of 80:1, and add 70 g of anhydrous ethanol (analytical grade) as a process control agent. Set the grinding mill to unidirectional rotation mode, set the grinding time to 20 h, and the rotation speed frequency to 10 Hz (120 r / min). After grinding, separate the ZrO2 grinding balls and the ethanol / powder mixture using a 60-mesh sieve. Then, use a magnet to adsorb the ethanol / powder mixture and pour off the supernatant. Put the remaining powder into an oven and set the drying temperature to 60℃ for a drying time of not less than 3 h. Obtain flaky FeMnSiAl-Ti alloy micro powder. (3) The obtained flaky FeMnSiAl-Ti alloy micro powder was poured into a ceramic boat and heat-treated in a tube furnace: a mechanical pump was used to evacuate the air pressure to a level below 1×10⁻⁶. -1 Pa and pressurize for 30 min to ensure good airtightness; under vacuum, set the heating rate to rise from room temperature to 600℃ at 10℃ / min and hold for 2 h, then allow to cool naturally to room temperature.

[0066] Comparative Example 1 A FeSiAl alloy micro powder is prepared using only milling and heat treatment processes; the specific preparation method includes the following steps: (1) Fe, Si, and Al elements in bulk or sheet form were placed in the sample pit of a vacuum arc melting furnace in a Sendust alloy composition ratio (mass ratio 85:9.6:5.4). The vacuum level of the system was evacuated to below 5 × 10⁻⁶ using a mechanical pump and a molecular pump. - 3 After Pa, high-purity argon gas (99.999%) is introduced to bring the gas pressure to -0.05 MPa. An arc is ignited using a current of 100~250 A and the mixture is melted in magnetic stirring mode. The mixture is then flipped over and the process is repeated 3~5 times, followed by cooling. The FeSiAl alloy ingots obtained from the smelting were then loaded into a quartz nozzle and placed in a gas atomization alloy powder making device. The vacuum degree of the system was evacuated to below 3 × 10⁻⁶ using a mechanical pump and a diffusion pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to achieve a pressure of 7.0~10 MPa. The ingot is heated to 1450~1600℃ by electromagnetic induction with copper wire, and the alloy solution is held at this temperature for more than 2 minutes. The alloy solution is then sprayed out with a pressure difference of 0.02~0.05 MPa to form spherical FeSiAlMn powder. The powder is then ultrasonically sieved through a 250-mesh sieve for more than 5 minutes. The material passing through the 250-mesh sieve is collected to obtain the original spherical FeSiAl powder. (2) Take the obtained spherical FeSiAl raw powder, weigh 10 g and put it into a grinding jar. Add 800 g of ZrO2 balls with a diameter of 6 mm (>95%) at a ball-to-material mass ratio of 80:1, and add 70 g of anhydrous ethanol (analytical grade) as a process control agent. Set the grinding mill to unidirectional rotation mode, set the grinding time to 20 h, and the rotation speed frequency to 10 Hz (120 r / min). After grinding, separate the ZrO2 grinding balls and the ethanol / powder mixture with a 60-mesh sieve, then use a magnet to adsorb the ethanol / powder mixture and pour off the supernatant. Put the remaining powder into an oven, set the drying temperature to 60℃, and the drying time to not less than 3 h. Obtain flaky FeSiAl alloy micro powder. (3) The obtained flake-shaped FeSiAl alloy micro powder was poured into a ceramic boat and heat-treated in a tube furnace: a mechanical pump was used to evacuate the air pressure to a level below 1×10⁻⁶. -1 Pa and pressurize for 30 min to ensure good airtightness; under vacuum, set the heating rate to 10℃ / min to raise the temperature from room temperature to 300℃, 400℃, 500℃, 600℃ and 700℃ respectively and hold for 2 h, then let it cool naturally to room temperature.

[0067] Figure 26 To prepare spherical Fe by gas atomization 85 Si 9.6 Al 5.4 Scanning electron micrographs of the original powder show that the powder is basically in the shape of regular spheres; statistically, the particle size ranges from 3 to 58 μm, and the average particle size is about 16.0 μm. Figure 27 To prepare spherical Fe by gas atomization 85 Si 9.6 Al 5.4 The inductively coupled plasma atomic emission spectrometry (ICP-AES) fitting analysis of the original powder showed that the contents of Fe, Si, and Al were 84.3994 wt.%, 9.5776 wt.%, and 5.3573 wt.%, respectively, which were basically consistent with the designed composition. The alloy contained trace amounts of impurity elements such as Mn, Co, Ni, and Cr. Figure 28 Fe before and after 8 h, 12 h, and 16 h of grinding 85 Si 9.6 Al 5.4 Cu target (K) of alloy micro powder α - 1.54060 Å) X-ray diffraction pattern, showing Fe 85 Si 9.6 Al 5.4 The original powder contained a bcc-Fe lattice, with Si and Al elements entering the bcc-Fe lattice in the form of substitutional solid solutions, and some B2 and DO3 ordered phases were also present; Fe 85 Si9.6 Al 5.4 After grinding, the alloy micro powder contains only the bcc-(Fe,Mn,Si,Al) phase, and the internal stress increases significantly and the grain size is refined. Figure 29 Fe after grinding 85 Si 9.6 Al 5.4 Scanning electron micrographs of the alloy micropowders show that the FeSiAl alloy micropowders after 16 h of stirring are all in the form of flakes or discs, with an average flake diameter of about 19.2 μm and a particle thickness of 0.3~2 μm.

[0068] Figure 6 Flaky Fe after heat treatment 85 Si 9.6 Al 5.4 Co target (K) of alloy micro powder α - 1.78897 Å) X-ray diffraction pattern, showing Fe 85 Si 9.6 Al 5.4 The alloy powder contains an ordered DO3 phase and a small amount of Fe oxide. Figure 7 Flaky Fe after heat treatment 85 Si 9.6 Al 5.4 Alloy micropowder in Co target (K α The peak intensity ratios of the DO3 (111), DO3, and bcc-Fe (110) crystal planes in the X-ray diffraction pattern at -1.78897 Å show that the absence of Mn doping reduces the relative peak intensity of the DO3 characteristic peak. Figure 30 Flaky Fe after heat treatment 81.8 Mn 3.2 Si 9.6 Al 5.4 The Mössbauer spectra and fitting analysis results of the alloy micropowder (see Table 2) show that, compared with Example 1, the Fe(4) occupancy in the Fe atoms of the sample decreased and the Fe(6) occupancy increased, indicating that the DO3 phase content was low; the Fe(6) occupancy sub-spectral peak area corresponding to the A2 disorder reached 7.0%, which is 30% higher than that of Example 1, indicating that the A2 disorder phase content increased significantly and the DO3 ordering was relatively insufficient. Figure 9 Flaky Fe after heat treatment 85 Si 9.6 Al 5.4 The MH hysteresis loop of the alloy micro powder shows that Fe 85 Si 9.6 Al 5.4 The alloy micro powder exhibits good soft magnetic properties, but its initial permeability is low.

[0069] Table 2. Flaky Fe 85 Si 9.6 Al5.4 Mössbauer spectrum fitting results of alloy micro powder (χ²) 2 = 1.97)

[0070] Heat-treated sheet Fe 85 Si 9.6 Al 5.4 Alloy micro powder and sliced ​​paraffin were heated and mixed at a mass ratio of 2:1 to form a coaxial sample. Figure 10 Flaky Fe after heat treatment 85 Si 9.6 Al 5.4 Dynamic electromagnetic parameters of the alloy micropowder, measured using the coaxial method, show that under Mn-free conditions, the real part of the complex permittivity at 1 GHz is ~20, which is higher than that of the Mn-doped FeSiAl absorbers after heat treatment at the same temperature in Examples 1, 2, 3, and 4 (see...). Figure 10 The real and imaginary parts of the complex permeability are ~3.1 and ~2.2, respectively, which are lower than those in Examples 1 and 2. Figure 10 ) and, Example 5 ( Figure 25 The FeSiAl absorber was heat-treated at the same temperature with Mn. Compared to a suitable amount of Mn doping, it is difficult to obtain both low complex permittivity and high complex permeability without Mn doping. Therefore, the impedance matching and absorption performance are relatively poor, which is not conducive to low-frequency absorption.

[0071] Comparative Example 2 A FeMnSiAl alloy micro powder is prepared by the following steps: (1) Fe, Mn, Si, and Al in bulk or sheet form were placed in the sample pit of a vacuum arc melting furnace in a mass ratio of 81.8:3.2:9.6:5.4. The vacuum level of the system was evacuated to below 5×10⁻⁶ using a mechanical pump and a molecular pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to bring the gas pressure to -0.05 MPa. An arc is ignited using a current of 100~250 A and the mixture is melted in magnetic stirring mode. The mixture is then flipped over and the process is repeated 3~5 times, followed by cooling. The FeSiAl alloy ingots obtained from the smelting were then loaded into a quartz nozzle and placed in a gas atomization alloy powder making device. The vacuum degree of the system was evacuated to below 3 × 10⁻⁶ using a mechanical pump and a diffusion pump. -3 After Pa, high-purity argon gas (99.999%) is introduced to achieve a pressure of 7.0~10 MPa. The ingot is heated to 1450~1600℃ by electromagnetic induction with copper wire, and the alloy solution is held at this temperature for more than 2 minutes. The alloy solution is then sprayed out with a pressure difference of 0.02~0.05 MPa to form spherical FeSiAlMn powder. The powder is then ultrasonically sieved through a 250-mesh sieve for more than 5 minutes. The material passing through the 250-mesh sieve is collected to obtain the original spherical FeSiAl powder. (2) Take the obtained spherical FeMnSiAl raw powder, weigh 10 g and put it into a grinding jar. Add 800 g of ZrO2 balls with a diameter of 6 mm (>95%) at a ball-to-material mass ratio of 80:1, and add 70 g of anhydrous ethanol (analytical grade) as a process control agent. Set the grinding mill to unidirectional rotation mode, set the grinding time to 20 h, and the rotation speed frequency to 10 Hz (120 r / min). After grinding, separate the ZrO2 grinding balls and the ethanol / powder mixture using a 60-mesh sieve. Then, use a magnet to adsorb the ethanol / powder mixture and pour off the supernatant. Put the remaining powder into an oven and set the drying temperature to 60℃ for a drying time of not less than 3 h. Obtain flaky FeMnSiAl alloy micro powder. (3) The obtained flake-shaped FeMnSiAl alloy micro powder was poured into a ceramic boat and heat-treated in a tube furnace: a mechanical pump was used to evacuate the air pressure to a level below 1×10⁻⁶. -1 Pa and pressurize for 30 min to ensure good airtightness; under vacuum, set the heating rate to rise from room temperature to 600℃ at 10℃ / min and hold for 2 h, then allow to cool naturally to room temperature.

[0072] Figure 31 Fe after 20 h of grinding 81.8 Mn 3.2 Si 9.6 Al 5.4 Scanning electron micrographs of alloy micropowder, showing Fe after stirring. 81.8 Mn 3.2 Si 9.6 Al 5.4 The particles are all in the form of flakes or discs, and their width-to-thickness ratio is further increased compared with the alloy micro powder that has been stirred and milled for 16 h, with an average flake diameter of about 22.5 μm.

[0073] Figure 32 The flaky Fe after milling for 20 hours 81.8 Mn 3.2 Si 9.6 Al 5.4 Cu target (K) of alloy micro powder α - 1.54060 Å) X-ray diffraction pattern, obtained from XRD structure calculations after 20 h of grinding of Fe 81.8 Mn 3.2 Si 9.6 Al 5.4 The internal strain of the alloy micro powder increased to 0.68% from 0.55% after 16 h of milling, indicating that the internal defects of the alloy micro powder further increased. Figure 33 The flaky Fe after milling for 20 hours 81.8 Mn 3.2 Si 9.6 Al5.4 Co target (K) after heat treatment of alloy micro powder at 600℃ α The X-ray diffraction pattern of -1.78897 Å shows that after heat treatment, the relative peak intensity of the DO3 (111) crystal plane relative to the (110) plane is 5.2%, which is significantly lower than that after 16 h of stirring. This indicates that the DO3 ordered phase transition energy increases due to the large number of dislocations and stacking faults caused by prolonged stirring, resulting in a decrease in the DO3 ordered phase content after heat treatment.

[0074] Figure 34 The flaky Fe after milling for 20 hours 81.8 Mn 3.2 Si 9.6 Al 5.4 Electromagnetic parameters of coaxial samples prepared by mixing alloy micropowder with sliced ​​paraffin at a mass ratio of 2:1 before and after heat treatment at 600℃ in the range of 0.1 to 10 GHz show that even with a further increase in the particle size-to-thickness ratio, the excess defects can still overcome the Snoek limit, and the decrease in the content of the DO3 ordered phase leads to a significant decrease in the real and imaginary parts of the complex permeability.

[0075] The above description is merely a specific embodiment of this application; however, the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A FeMnSiAl-based high-order phase content flaky low-frequency wave absorber, characterized in that, The D03 ordered phase based on a bcc-Fe cell contains 30-50 at.% of D03 phase, and the D03 ordered phase is a modulated structure of D03-FeSiAl and D03-(Fe, Mn)SiAl two atomic arrangements. 2.The FeMnSiAl-based sheet-like low-frequency wave absorber according to claim 1, wherein, It also contains one or more of A2 disordered phase and B2 subordered phase based on a bcc-Fe cell.

3. The method of producing a high ordered phase content FeMnSiAl based sheet-like low frequency wave absorber according to any one of claims 1 to 2, characterized in that, The method comprises the following steps: (1) doping FeSiAl alloy with Mn to prepare spherical FeMnSiAl alloy micro powder; (2) performing sheeting deformation treatment on the spherical FeMnSiAl alloy micro powder; (3) performing heat treatment on the obtained sheet FeMnSiAl alloy micro powder to obtain FeMnSiAl-based sheet low-frequency wave absorber with high ordered phase content.

4. The production method according to claim 3, characterized by, In step (1), the doping amount of Mn element is 1-10 wt.%.

5. The preparation method according to claim 3, characterized in that, In the FeSiAl alloy, the content of Fe element is 70-90 wt.%, the content of Si element is 1-15 wt.% and the content of Al element is 1-10 wt.%.

6. The preparation method according to claim 3, characterized in that, The FeSiAl alloy also contains one or more of Cr, Zr, Co, V, Ni, Mo, Ti, Sn, Nb and Y elements.

7. The preparation method according to claim 3, characterized in that, The sheeting deformation means adopts a ball milling process, and the ball milling rate is 90-150 r / min and the time is 12-20 h.

8. The preparation method according to claim 3, characterized in that, The sheet FeMnSiAl alloy micro powder has a sheet size of 5-200 μm and a thickness of 0.3-5 μm.

9. The preparation method according to claim 3, characterized in that, In step (3), the heat treatment step uses a holding temperature of 300-800℃, a heating rate of 5-20℃ / min and a holding time of more than 10 min.

10. A high-performance wave-absorbing material based on the high-order phase content of the FeMnSiAl-based flaky low-frequency wave-absorbing agent of claim 1, characterized in that, The FeMnSiAl sheet low-frequency wave absorber is compounded with a polymer matrix to obtain a high-performance wave-absorbing material for L-S frequency band.

Images