Boron-doped iron-gallium alloy magnetostrictive material and preparation method thereof

Abstract

The invention relates to the technical field of iron-gallium-based magnetostrictive materials, in particular to a boron-doped iron-gallium alloy magnetostrictive material and a preparation method thereof. The boron-doped iron-gallium alloy magnetostrictive material is obtained by taking a Fe83Ga17 alloy as a matrix, doping B into the matrix and carrying out directional solidification treatment so as to enable crystal grains to grow along a [100] direction, thereby obtaining the boron-doped iron-gallium alloy magnetostrictive material, the chemical expression of the boron-doped iron gallium alloy magnetostrictive material is Fe < 83 > Ga < 17 > B < x >, wherein 1 < = x < = 4. The Fe83Ga17 alloy is used as a matrix, and the growth of crystal grains in the [100] direction is adjusted by controlling the amount of additionally doped B, so that the magnetostriction property and the mechanical property of the magnetostriction material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of iron-gallium-based magnetostrictive materials, and in particular to a boron-doped iron-gallium alloy magnetostrictive material and a preparation method thereof. Background Art

[0002] Magnetostriction is a physical phenomenon in which a ferromagnetic or ferrimagnetic material changes shape and size when magnetized in a magnetic field. Giant magnetostrictive materials, due to their large magnetostriction coefficient, fast mechanical response, and high energy density, are widely used in fields such as medicine, aerospace, and machinery.

[0003] Tb-Dy-Fe alloys, as a type of giant magnetostrictive material, have attracted much attention due to their ability to generate large strains under the influence of a magnetic field. However, the brittleness of Tb-Dy-Fe alloys limits their use in some applications, especially those requiring high mechanical toughness.

[0004] In recent years, Fe-Ga alloys have become a hot topic of research as an alternative to Tb-Dy-Fe alloys. Binary Fe-Ga alloys exhibit high magnetostriction values ​​at low saturation fields. Compared to Tb-Dy-Fe alloys, Fe-Ga alloys are less brittle, have higher strength, higher magnetic permeability, higher Curie temperatures, and better machinability. These properties make Fe-Ga alloys a promising candidate to replace Tb-Dy-Fe as a new generation of giant magnetostrictive materials.

[0005] However, the maximum magnetostriction value of Fe-Ga alloy is only 1 / 5 of that of Tb-Dy-Fe material. Therefore, in practical applications, how to improve the mechanical properties and magnetostrictive properties of Fe-Ga magnetostrictive materials has become the most critical issue in current research. Summary of the Invention

[0006] In order to solve the problem that the maximum magnetostriction value of Fe-Ga alloy is relatively low, the present invention provides a boron-doped iron-gallium alloy magnetostrictive material and a preparation method thereof.

[0007] The present invention uses Fe 83 Ga 17 The alloy is used as the matrix, and by controlling the amount of additional B doping, the grain growth along the

[100] direction is adjusted, thereby improving the magnetostrictive and mechanical properties of the magnetostrictive material.

[0008] To achieve the above objectives, the technical solutions of the present invention are as follows.

[0009] The first aspect of the present invention provides a boron-doped iron-gallium alloy magnetostrictive material, wherein the boron-doped iron-gallium alloy magnetostrictive material is Fe 83 Ga 17The alloy is used as a matrix, B is doped into the matrix, and a directional solidification process is performed to make the grains grow along the

[100] direction to obtain a boron-doped iron-gallium alloy magnetostrictive material; the chemical expression of the boron-doped iron-gallium alloy magnetostrictive material is: Fe 83 Ga 17 B x ; where 1 ≤ x ≤ 4.

[0010] Preferably, x =3.

[0011] A second aspect of the present invention provides a method for preparing a boron-doped iron-gallium alloy magnetostrictive material, comprising the following steps: Fe 83 Ga 17 The alloy is used as a matrix, and B is doped into the matrix to prepare a boron-doped iron-gallium alloy; The boron-doped iron-gallium alloy is subjected to directional solidification treatment so that the grains grow along the

[100] direction, thereby obtaining a boron-doped iron-gallium alloy magnetostrictive material.

[0012] Preferably, the method for directional solidification of the boron-doped iron-gallium alloy is as follows: Under the protection of an inert atmosphere, a boron-doped iron-gallium alloy is heated to a molten state. Then, at a stretching rate of 110 mm / h to 120 mm / h, the molten boron-doped iron-gallium alloy is stretched and directionally solidified from a heating zone to a cooling zone so that the grains grow along the

[100] direction, thereby obtaining a boron-doped iron-gallium alloy magnetostrictive material.

[0013] Preferably, the temperature for heating to the molten state is 1600°C.

[0014] Preferably, the method for preparing the boron-doped iron-gallium alloy is as follows: According to the chemical formula of boron-doped iron-gallium alloy magnetostrictive material Fe 83 Ga 17 B x The iron, gallium and boron raw materials are weighed respectively in a stoichiometric ratio; under the protection of an inert atmosphere, the iron, gallium and boron raw materials are smelted to obtain a boron-doped iron-gallium alloy.

[0015] The iron, gallium and boron raw materials used in the present invention are respectively iron particles with a purity of ≥99.95%, bulk gallium with a purity of ≥99.99% and boron particles with a purity of ≥99.9%.

[0016] Preferably, the smelting conditions are: The melting pressure is 2×10 4 Pa ~ 3×10 4 Pa; the melting temperature is 1800~2500℃.

[0017] In the present invention, smelting is carried out in an inert gas such as argon to prevent the molten metal from reacting with oxygen, nitrogen, etc. in the air. The smelting pressure is 2×10 4 Pa ~ 3×10 4 Pa; for example, 2.5×10 4 Pa. Appropriate pressure during smelting helps control the melt flow and the escape of metal vapor during the smelting process, and also helps maintain temperature uniformity in the smelting furnace.

[0018] Before filling the inert gas into the melting furnace, evacuate to 2×10 -3 ~ 4×10 -3 Pa, for example, vacuum to 3.0×10 -3 Pa, and then filled with inert gas. Under high vacuum conditions, oxygen, nitrogen and other gaseous impurities in the melting furnace can be effectively removed. These impurities may react with the molten metal and affect the purity and performance of the product.

[0019] The melting temperature is 1800-2500°C. The above melting temperature is sufficient to melt iron, gallium and boron, and is conducive to the re-nucleation and growth of grains; in addition, at high temperatures, certain impurity elements are more easily volatilized, thereby further purifying the magnetostrictive material.

[0020] Preferably, the melting process is performed three to five times. For example, four times. Repeated melting helps promote a uniform distribution of the magnetostrictive material components, reduce microsegregation, and improve the uniformity of the magnetostrictive material. The four melting temperatures can range from 1800°C to 2400°C to promote elemental convection and homogenize the sample, for example, at 1800°C, 2000°C, 2200°C, and 2400°C, respectively.

[0021] In the present invention, the smelting is preferably achieved using arc melting technology, more preferably in a non-consumable vacuum arc melting furnace. Such a non-consumable vacuum arc melting furnace can melt metal under extremely high vacuum conditions, reducing the incorporation of oxidation and other impurities, thereby producing a material of very high purity. Furthermore, it facilitates multiple melting and solidification steps, helping to homogenize the chemical composition of the material and reduce segregation.

[0022] Beneficial effects of the present invention: 1. The present invention is based on binary Fe 83 Ga 17 The magnetostrictive and mechanical properties of the magnetostrictive material are improved by adding additional B elements and adjusting the grains to grow along the

[100] direction through directional stretching.

[0023] 2. The boron-doped iron-gallium alloy magnetostrictive material prepared by the present invention has a maximum magnetostriction value of 193 ppm, which is 1.8 times that of the undoped alloy, and the ultimate tensile strength and ductility are increased by 147% and 235%, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagrams of the six-atomic-layer slab model on the (100) and (110) crystal planes without B doping and after B doping. Figure a is a schematic diagram of the six-atomic-layer slab model on the (100) crystal plane in Comparative Example 1; Figure b is a schematic diagram of the six-atomic-layer slab model on the (110) crystal plane in Comparative Example 1; Figure c is a schematic diagram of the six-atomic-layer slab model on the (100) crystal plane after B doping in Example 1; and Figure d is a schematic diagram of the six-atomic-layer slab model on the (110) crystal plane after B doping in Example 1.

[0025] Figure 2 These are X-ray diffraction patterns of the boron-doped iron-gallium alloy magnetostrictive materials prepared in Examples 1 to 4 and the iron-gallium alloy magnetostrictive material prepared in Comparative Example 1.

[0026] Figure 3 This is a comparison chart of the (200) peak to (110) peak intensity ratios of the boron-doped iron-gallium alloy magnetostrictive materials prepared in Examples 1 to 4 and the iron-gallium alloy magnetostrictive material prepared in Comparative Example 1.

[0027] Figure 4 These are strain test graphs for the boron-doped iron-gallium alloy magnetostrictive materials prepared in Examples 1 to 4, and the iron-gallium alloy magnetostrictive material prepared in Comparative Example 1. (a) is a strain test graph for the iron-gallium alloy magnetostrictive material prepared in Comparative Example 1; (b) is a strain test graph for the boron-doped iron-gallium alloy magnetostrictive material prepared in Example 2; (c) is a strain test graph for the boron-doped iron-gallium alloy magnetostrictive material prepared in Example 3; (d) is a strain test graph for the boron-doped iron-gallium alloy magnetostrictive material prepared in Example 1; and (e) is a strain test graph for the boron-doped iron-gallium alloy magnetostrictive material prepared in Example 4.

[0028] Figure 5 The room temperature mechanical properties of the boron-doped iron-gallium alloy magnetostrictive materials prepared in Examples 1 to 4 and the iron-gallium alloy magnetostrictive material prepared in Comparative Example 1 are shown in Figures 1 to 4. (a) shows the room temperature mechanical properties of the iron-gallium alloy magnetostrictive material prepared in Comparative Example 1; (b) shows the room temperature mechanical properties of the boron-doped iron-gallium alloy magnetostrictive material prepared in Example 2; (c) shows the room temperature mechanical properties of the boron-doped iron-gallium alloy magnetostrictive material prepared in Example 3; (d) shows the room temperature mechanical properties of the boron-doped iron-gallium alloy magnetostrictive material prepared in Example 1; and (e) shows the room temperature mechanical properties of the boron-doped iron-gallium alloy magnetostrictive material prepared in Example 4. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0031] Boron-doped Fe-Ga alloys have significantly improved magnetostrictive properties. For example, the magnetostrictive properties of Fe-Ga alloys can be significantly improved by combining laser powder bed melting with boron doping. The rapid solidification characteristics of laser powder bed melting expand the solid solubility of boron, inducing lattice distortion and dislocation proliferation. At the same time, the high temperature gradient of laser powder bed melting synchronously drives the epitaxial growth of grains along the

[001] orientation, thereby significantly improving the magnetostrictive properties of polycrystalline Fe-Ga-B alloys. However, laser powder bed melting introduces a large number of dislocations during the preparation of polycrystalline Fe-Ga-B alloys, resulting in a reduction in their tensile strength. In addition, the magnetostrictive value of polycrystalline Fe-Ga-B alloys prepared by laser powder bed melting is relatively low, reaching only 104 ppm.

[0032] In order to improve the magnetostrictive performance and mechanical properties of boron-doped iron-gallium alloy magnetostrictive materials, the present invention is based on binary Fe 83 Ga 17 The magnetostrictive and mechanical properties of the magnetostrictive material are improved by adding additional B element to the crystal gap and controlling the grain growth along the

[100] direction through directional solidification treatment.

[0033] In the present invention, in the magnetostrictive material, the energy of the crystal plane (100) is lower than that of the crystal plane (110).

[0034] The experimental results show that Fe without B doping 83 Ga 17 The alloy has a magnetostriction value of 105.9 ppm and an ultimate tensile strength of 363 MPa. In contrast, the boron-doped iron-gallium alloy magnetostrictive material obtained by doping with the element B in the present invention has a magnetostriction value of 122.5 to 193.0 ppm and an ultimate tensile strength of 532 MPa. This demonstrates that the method of the present invention improves both the magnetostrictive and mechanical properties of magnetostrictive materials.

[0035] Through comparative analysis, it can be seen that with the increase of B content, the intensity ratio of (200) peak to (110) peak increases accordingly; on the one hand, the volume proportion of 90° flipped magnetic domains increases, and the magnetostrictive performance increases; on the other hand, the lattice constant increases, and the magnetostrictive constant also increases. Therefore, the magnetostrictive performance of the magnetostrictive material of the present invention shows an increasing trend. However, when x>4, the B element cannot be further dissolved into the FeGa alloy and the additional B element will form more second phases at the grain boundaries, namely Fe2B phase, which leads to a decrease in the intensity ratio of (200) peak to (110) peak and a decrease in the magnetostrictive constant, thereby causing the magnetostrictive performance of the magnetostrictive material to decrease.

[0036] along with x The ultimate tensile strength and ductility are significantly improved. x As the Fe2B phase gradually increases at the grain boundaries, it acts as a hard and brittle secondary phase, which increases the tensile strength of the magnetostrictive material, but at the same time reduces the grain boundary ductility. Therefore, the ultimate tensile strength gradually increases. On the other hand, as the Fe2B phase gradually increases at the grain boundaries, the ultimate tensile strength gradually increases. x The increase in , leads to grain refinement, which may be accompanied by an increase in dislocation density, thereby enhancing the toughness of the alloy. Due to the competition between these two effects, the ductility first increases and then decreases. x = 3 and reaches its maximum value.

[0037] The invention effectively predicts the influence of B element doping on the growth direction of the Fe-Gallium alloy crystal, thereby accurately controlling the crystal growth direction and further improving the magnetostrictive performance of the Fe-Gallium alloy magnetostrictive material.

[0038] The chemical composition of the boron-doped iron-gallium alloy magnetostrictive material was calculated using density functional theory. The specific method is as follows: S1, constructing a block model. Specifically, the method of constructing the block model is as follows:

[0039] S1.1. Determine that the crystal structure of the iron-gallium alloy is a body-centered cubic structure, denoted as BCC structure.

[0040] S1.2, construct supercells based on the determined crystal structure. Among them, the VASP program is mainly used to construct Fe 45 The A2 structure of Ga9 alloy, due to Fe 45 The A2 structure of Ga9 alloy is a random disordered structure. The SQS method is used to construct a 3×3×3 BCC supercell, which is close to the Fe 83 Ga 17 .

[0041] S1.3, perform full relaxation optimization on the supercell to obtain a bulk model. In the VASP program, set the wave function cutoff energy to 400eV to 600eV, for example, 500eV; use the projected augmented wave method, spin-polarized generalized gradient approximation, and Perdew-Burke-Ernzerhof exchange-correlation function to perform full relaxation optimization on the supercell, use a 3×3×3 Monkhorst-Pack k-point grid for Brillouin zone integration, and fully relax the atomic positions and lattice constants in the supercell until the energy and force differences are less than 10 -5 eV and 0.01eV / Å. Projector Augmented Wave method, the full name in English is Projector Augmented Wave method, referred to as PAW method; Generalized Gradient Approximation, the full name in English is Generalized Gradient Approximation, referred to as GGA; Perdew-Burke-Ernzerhof, the Chinese name is Perdew-Burke-Ernzerhof, referred to as PBE. The PAW method is used to improve the efficiency and accuracy of first-principles calculations. GGA is used to more accurately describe the exchange and correlation effects of electrons. PBE is an optimized GGA function that is widely used in electronic structure calculations of materials and molecules. Monkhorst-Pack is the Monkhorst-Pack sampling method.

[0042] S2: Construct a flat plate model based on the block model. Specifically, the method for constructing the flat plate model is as follows:

[0043] Based on the block model, a flat plate model containing six atomic layers is created, which are perpendicular to the (100) crystal plane and the (110) crystal plane respectively. The flat plate model simulates a periodic structure in a plane horizontal and perpendicular to the paper surface, that is, it is infinite in this plane; the flat plate model contains different surface combinations, excluding the flat plate of pure iron surface. Among them, the surface can be different crystal planes, that is, crystal plane (100) or crystal plane (110). Since Fe 83 Ga 17 The A2 crystal structure is used, which represents a chemically disordered body-centered cubic structure; Fe and Ga atoms occupy positions randomly, so there will be a variety of surface combinations of atomic positions.

[0044] S3, based on the flat plate model, B atoms are doped in the surface gap positions and the surface energy is obtained.

[0045] Before doping with B atoms, periodic boundary conditions were set in the x- and y-axis directions, and a vacuum space of at least 20 Å was set in the z-axis direction to prevent interaction between the slab and the periodic structure. Once the slab model was constructed, the periodic boundary conditions in the x- and y-axis directions could be determined.

[0046] Only one B atom was doped on each surface of the Fe-Ga plate, and the effect of B was observed.

[0047] The two middle atomic layers are fixed, and only the atoms in the surface layer are allowed to relax.

[0048] The surface energy is obtained by the following formula: ; Among them, E slab is the total energy of the flat plate model; E bulk is the total energy of the block model; S is the surface area of ​​the plate model. Since there are many surface combinations, is the average surface energy of all plate models.

[0049] S4, predict the crystal growth direction based on the surface energy and determine the composition of the magnetostrictive material.

[0050] According to the difference in surface energy between (100) crystal plane and (110) crystal plane, , determines the crystal growth direction. Specifically, when A positive value means that during the crystal growth process, the (110) crystal plane has lower energy and is more stable than the (100) crystal plane; or when A negative value means that during the crystal growth process, the (100) crystal plane has lower energy and is more stable than the (110) crystal plane. At this time, the crystal growth direction is parallel to the easy magnetization axis, and its magnetostrictive performance is better.

[0051] The present invention uses density functional theory calculations combined with experimental results to confirm that by regulating B doping, the easy growth direction can be changed to be consistent with the easy magnetization axis direction, thereby significantly improving the magnetostrictive performance. In addition, the energy of the crystal plane (100) is lower than that of the crystal plane (110).

[0052] In the present invention, the specific method of directional solidification treatment is as follows: the boron-doped iron-gallium alloy sample is roughly polished, cleaned, and crushed with pliers, and then placed in an alumina ceramic tube with a diameter of 8 mm. One end of the sample holder is used to block the open end of the alumina ceramic tube, and the other end is connected to the traction device through the lower thread. The sample chamber door is sealed and vacuumed to 3.0×10 -3 Pa, turn off the vacuum device, and fill the chamber with argon to 5×10 4 Pa. The position of the sample holder is lowered by 12mm by the pulling device, and then the heating program is set according to 4 stages to the final target temperature of 1600℃. After keeping the temperature for 5 minutes, the stretching program is performed. The 4 heating stages are as follows: First heating stage: set the starting temperature to 25℃ and the heating rate to 13.75℃ / min -1, heating to 300℃ in 20min and keeping warm for 5min; second heating stage: set the starting temperature to 300℃, heating rate to 25℃ / min, heating to 800℃ in 20min and keeping warm for 5min; third heating stage: set the starting temperature to 800℃, heating rate to 20℃ / min, heating to 1200℃ in 20min and keeping warm for 5min; fourth heating stage: set the starting temperature to 1200℃, heating rate to 20℃ / min, heating to 1600℃ in 20min.

[0053] The stretching program was set to a stretching rate of 110 mm / h to 120 mm / h and a stretching time of 30 minutes. Stretching began, with the pulling device pulling the ceramic tube downward into the Ga-In alloy solution at a speed of 110 mm / h to 120 mm / h. The stretching program was terminated when the alumina ceramic tube was completely immersed in the Ga-In alloy solution and the sample was completely solidified. The heating power was turned off, and after the temperature in the sample chamber cooled to room temperature, the sample chamber was opened, the alumina ceramic tube was removed, and the tube was gently broken into pieces. The rod was then removed to obtain a directionally solidified boron-doped iron-gallium alloy magnetostrictive material.

[0054] The wire cutting method was used to cut a cylinder with a radius of 4mm and a height of 10mm from the middle 1cm of the directionally solidified rod. Then, two discs with a radius of 4mm and a thickness of 1.5mm were cut from both sides of the cylinder for microstructural characterization. The remaining cylinder with a radius of 4mm and a height of 7mm was cut longitudinally for strain testing. The microstructural characterization was performed using a Bruker D8 ADVANCE X-ray diffractometer. The strain test was performed using a standard resistance strain gauge. The tensile test sample must follow the above steps to obtain a complete rod under the same conditions, from which a 42mm × 4mm dog-bone specimen was cut using wire cutting. The test was performed using a KQLGW-500 testing machine at room temperature with a loading strain rate of 2×10 -3 s -1 The above test temperatures are all room temperature 300K. To reduce measurement errors, the samples were polished smooth before testing.

[0055] The technical solution of the present invention is further described below through specific embodiments.

[0056] In the following examples, the methods described are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0057] In the following embodiments, the purity of iron is not less than 99.95%, the purity of gallium is not less than 99.99%, and the purity of boron is not less than 99.9%. Example 1 A method for preparing a boron-doped iron-gallium alloy magnetostrictive material comprises the following steps: Step 1: Determine the effect of B doping on Fe 83 Ga 17 Influence of minimum formation energy of alloy.

[0058] Determine Fe 83 Ga 17 The crystal structure of the alloy is a body-centered cubic structure, also known as BCC structure. The SQS method is used to construct a 3×3×3 BCC supercell, making its composition close to that of Fe 83 Ga 17 The wave function cutoff energy was set to 400 eV in the VASP program. The supercell was fully relaxed using the projected augmented wave method, the spin-polarized generalized gradient approximation, and the Perdew-Burke-Ernzerhof exchange-correlation function. A 3×3×3 Monkhorst-Pack k-point grid was used for Brillouin zone integration. The atomic positions and lattice constants in the supercell were fully relaxed until the energy and force differences were less than 10, respectively. -5 eV and 0.01eV / Å, and the bulk model is obtained.

[0059] Based on the bulk model, a slab model consisting of six atomic layers was created, perpendicular to the (100) and (110) crystal planes. The slab model contained different surface configurations, with Fe and Ga atoms randomly occupying positions. Once the slab model was constructed, periodic boundary conditions were set in the x- and y-axis directions, and a vacuum space of 20 Å was set in the z-axis direction. The two middle atomic layers were then fixed, and only the atoms in the surface layers were allowed to relax. Only one B atom was doped on each surface of the Fe-Ga slab.

[0060] Figure 1 Figure c shows the schematic diagram of the six-atom-layer slab model after the (100) crystal plane is doped with B; Figure 1 Figure d shows a schematic diagram of the six-atom-layer slab model after the (110) crystal plane is doped with B. Table 1 shows the total energy of the six planes of FeGaB doped with B, among which the surface areas of the (100) crystal plane and the (110) crystal plane are 75.07 Å, respectively. 2 and 105.79 Å 2 .

[0061] Table 1 Total energy of the six planes of FeGaB alloy It can be clearly seen from the results in Table 1 that the energies of the (100) and (110) crystal planes are: = -46.32meV / Ǻ 2 and = -67.86 meV / Ǻ 2 ; then the energy difference is: = −21.54 meV / Ǻ 2 .

[0062] This indicates that the energy relationship between the (100) and (110) planes has reversed, which means that during crystal growth, the (100) and (110) planes have lower energy and are more stable. Ultimately, the crystal growth direction is parallel to the easy magnetization axis.

[0063] Step 2: Prepare the boron-doped iron-gallium alloy magnetostrictive material by directional solidification.

[0064] Step 2.1, weighing and melting: press Fe 83 Ga 17 The stoichiometric ratio of B3 is 99.95% pure iron, 99.99% pure gallium and 99.9% pure boron. The weighed iron, gallium and boron are placed in a copper crucible in a non-consumable vacuum arc melting furnace. The furnace door is closed and the vacuum is drawn to 3.0×10 -3 Pa, and then filled with high-purity argon gas to 2×10 4 Pa, repeatedly smelted four times at 1800℃~2400℃, to obtain Fe 83 Ga 17 B3 alloy.

[0065] Step 2.2, Directional Solidification of Rods: 83 Ga 17 The B3 alloy sample was crushed by pliers and placed in a ceramic tube with a diameter of 8 mm. The door was sealed and the vacuum was pumped to 3.0 × 10 -3 Pa, close the vacuum device, fill the cabin with a proper amount of high-purity argon, set the heating program, and when the temperature rises to 1600℃, keep it warm for five minutes and then start stretching at a rate of 110mm / h~120mm / h. After stretching, wait until the temperature in the cabin drops to room temperature, open the cabin door and take out the rod to make Fe 83 Ga 17 B3 directionally solidified boron-doped iron-gallium alloy magnetostrictive material.

[0066] For the convenience of description, Fe 83 Ga 17 B3 directionally solidified boron-doped iron-gallium alloy magnetostrictive material, referred to as directionally solidified rod.

[0067] A cylinder with a radius of 4 mm and a height of 10 mm was cut out of the middle 1 cm of the directionally solidified rod using the wire cutting method. Two discs with a radius of 4 mm and a thickness of 1.5 mm were then cut from both sides of the cylinder for microstructural characterization. The remaining cylinder with a radius of 4 mm and a height of 7 mm was cut longitudinally for strain testing. The microstructural characterization was performed using a Bruker D8 ADVANCE X-ray diffractometer, and the strain test was performed using a standard resistance strain gauge. The tensile test sample must follow the above steps to obtain a complete rod under the same conditions, from which a 42 mm × 4 mm dog bone specimen was cut using wire cutting. The test was performed using a KQLGW-500 testing machine at room temperature with a loading strain rate of 2×10 -3 s -1 The above test temperatures are all room temperature 300K. To reduce measurement errors, the samples were polished smooth before testing.

[0068] After testing, the Fe 83 Ga 17 The magnetostriction value of B3 directionally solidified boron-doped iron-gallium alloy magnetostrictive material is 193.0ppm, the (200) peak to (110) peak intensity ratio is 688.81%, the ultimate tensile strength is 531.6MPa, and the corresponding strain is 1.117%.

[0069] Example 2 A method for preparing a boron-doped iron-gallium alloy magnetostrictive material comprises the following steps: Step 1: Determine the effect of B doping on Fe 83 Ga 17 Influence of minimum formation energy of alloy.

[0070] In the same way as in Example 1, a bulk model and a flat plate model containing six atomic layers were constructed. By doping only one B atom on each surface of the Fe-Ga plate, the effect of B on the surface energy was observed. The feasibility of crystal growth was determined based on the energy relationship between the (100) crystal plane and the (110) crystal plane. The composition of the magnetostrictive material was set to Fe 83 Ga 17 B1.

[0071] Step 2: Prepare the boron-doped iron-gallium alloy magnetostrictive material by directional solidification.

[0072] Step 2.1, weighing and melting: press Fe 83 Ga 17 The stoichiometric ratio of B1 is 99.95% pure iron, 99.99% pure gallium and 99.9% pure boron. The weighed iron, gallium and boron are placed in a copper crucible in a non-consumable vacuum arc melting furnace. The furnace door is closed and the vacuum is pumped to 3.0×10 -3 Pa, and then filled with high-purity argon gas to 2×104 Pa, repeatedly smelted four times at 1800℃~2400℃, to obtain Fe 83 Ga 17 B1 alloy.

[0073] Step 2.2, Directional Solidification of Rods: 83 Ga 17 After the B1 alloy sample was crushed, it was placed in a ceramic tube with a diameter of 8 mm, the door was sealed, and the vacuum was evacuated to 3.0 × 10 -3 Pa, close the vacuum device, fill the cabin with a proper amount of high-purity argon, set the heating program, and when the temperature rises to 1600℃, keep it warm for five minutes and then start stretching at a rate of 110mm / h~120mm / h. After stretching, wait until the temperature in the cabin drops to room temperature, open the cabin door and take out the rod to make Fe 83 Ga 17 B1 directionally solidified boron-doped iron-gallium alloy magnetostrictive material.

[0074] For the convenience of description, Fe 83 Ga 17 B1 directionally solidified boron-doped iron-gallium alloy magnetostrictive material, referred to as directionally solidified rod.

[0075] A cylinder with a radius of 4 mm and a height of 10 mm was cut out of the center 1 cm of the directionally solidified rod using wire cutting. Two discs with a radius of 4 mm and a thickness of 1.5 mm were then cut from both sides of the cylinder for microstructural characterization. The remaining cylinder with a radius of 4 mm and a height of 7 mm was cut longitudinally for strain testing. Microstructural characterization was performed using a Bruker D8 ADVANCE X-ray diffractometer, and strain testing was performed using a standard resistance strain gauge. Tensile test samples were prepared according to the above steps to obtain a complete rod under the same conditions. A 42 mm × 4 mm dog-bone specimen was cut out of the rod using wire cutting. The specimens were tested at room temperature using a KQLGW-500 testing machine with a loading strain rate of 2 × 10 -3 s -1 The above test temperatures are all room temperature 300K. To reduce measurement errors, the samples were polished smooth before testing.

[0076] After testing, the Fe prepared in Example 2 83 Ga 17 The magnetostriction value of B1 directionally solidified boron-doped iron-gallium alloy magnetostrictive material is 122.5ppm, the (200) peak to (110) peak intensity ratio is 55.74%, the ultimate tensile strength is 272.3MPa, and the corresponding strain is 0.609%.

[0077] Example 3 A method for preparing a boron-doped iron-gallium alloy magnetostrictive material comprises the following steps: Step 1: Determine the effect of B doping on Fe 83 Ga 17 Influence of minimum formation energy of alloy.

[0078] In the same way as in Example 1, a bulk model and a flat plate model containing six atomic layers were constructed. By doping only one B atom on each surface of the Fe-Ga plate, the effect of B on the surface energy was observed. The feasibility of crystal growth was determined based on the energy relationship between the (100) crystal plane and the (110) crystal plane. The composition of the magnetostrictive material was set to Fe 83 Ga 17 B2.

[0079] Step 2: Prepare the boron-doped iron-gallium alloy magnetostrictive material by directional solidification.

[0080] Step 2.1, weighing and melting: press Fe 83 Ga 17 The stoichiometric ratio of B2 is 99.95% pure iron, 99.99% pure gallium and 99.9% pure boron. The weighed iron, gallium and boron are placed in a copper crucible in a non-consumable vacuum arc melting furnace. The furnace door is closed and the vacuum is drawn to 3.0×10 -3 Pa, and then filled with high-purity argon gas to 2×10 4 Pa, repeatedly smelted four times at 1800℃~2400℃, to obtain Fe 83 Ga 17 B2 alloy.

[0081] Step 2.2, Directional Solidification of Rods: 83 Ga 17 After the B2 alloy sample was crushed, it was placed in a ceramic tube with a diameter of 8 mm, the door was sealed, and the vacuum was evacuated to 3.0 × 10 -3 Pa, close the vacuum device, fill the cabin with a proper amount of high-purity argon, set the heating program, and when the temperature rises to 1600℃, keep it warm for five minutes and then start stretching at a rate of 110mm / h~120mm / h. After stretching, wait until the temperature in the cabin drops to room temperature, open the cabin door and take out the rod to make Fe 83 Ga 17 B2 directionally solidified boron-doped iron-gallium alloy magnetostrictive material.

[0082] For the convenience of description, Fe 83 Ga 17 B2 directionally solidified boron-doped iron-gallium alloy magnetostrictive material, referred to as directionally solidified rod.

[0083] A cylinder with a radius of 4 mm and a height of 10 mm was cut out of the middle 1 cm of the directionally solidified rod using the wire cutting method. Two discs with a radius of 4 mm and a thickness of 1.5 mm were then cut from both sides of the cylinder for microstructural characterization. The remaining cylinder with a radius of 4 mm and a height of 7 mm was cut longitudinally for strain testing. The microstructural characterization was performed using a Bruker D8 ADVANCE X-ray diffractometer, and the strain test was performed using a standard resistance strain gauge. The tensile test sample must follow the above steps to obtain a complete rod under the same conditions, from which a 42 mm × 4 mm dog bone specimen was cut using wire cutting. The test was performed using a KQLGW-500 testing machine at room temperature with a loading strain rate of 2×10 -3 s -1 The above test temperatures are all room temperature 300K. To reduce measurement errors, the samples were polished smooth before testing.

[0084] After testing, the Fe prepared in Example 3 83 Ga 17 The magnetostriction value of B2 directionally solidified boron-doped iron-gallium alloy magnetostrictive material is 151.8ppm, the (200) peak to (110) peak intensity ratio is 82.07%, the ultimate tensile strength is 436.4MPa, and the corresponding strain is 1.013%.

[0085] Example 4 A method for preparing a boron-doped iron-gallium alloy magnetostrictive material comprises the following steps: Step 1: Determine the effect of B doping on Fe 83 Ga 17 Influence of minimum formation energy of alloy.

[0086] In the same way as in Example 1, a bulk model and a flat plate model containing six atomic layers were constructed. By doping only one B atom on each surface of the Fe-Ga plate, the effect of B on the surface energy was observed. The feasibility of crystal growth was determined based on the energy relationship between the (100) crystal plane and the (110) crystal plane. The composition of the magnetostrictive material was set to Fe 83 Ga 17 B4.

[0087] Step 2: Prepare the boron-doped iron-gallium alloy magnetostrictive material by directional solidification.

[0088] Step 2.1, weighing and melting: press Fe 83 Ga 17 The stoichiometric ratio of B4 is 99.95% pure iron, 99.99% pure gallium and 99.9% pure boron. The weighed iron, gallium and boron are placed in a copper crucible in a non-consumable vacuum arc melting furnace. The furnace door is closed and the vacuum is pumped to 3.0×10 -3 Pa, and then filled with high-purity argon gas to 2×104 Pa, repeatedly smelted four times at 1800℃~2400℃, to obtain Fe 83 Ga 17 B4 alloy.

[0089] Step 2.2, Directional Solidification of Rods: 83 Ga 17 After the B4 alloy sample was crushed, it was placed in a ceramic tube with a diameter of 8 mm, the door was sealed, and the vacuum was evacuated to 3.0 × 10 -3 Pa, close the vacuum device, fill the cabin with a proper amount of high-purity argon, set the heating program, and when the temperature rises to 1600℃, keep it warm for five minutes and then start stretching at a rate of 110mm / h~120mm / h. After stretching, wait until the temperature in the cabin drops to room temperature, open the cabin door and take out the rod to make Fe 83 Ga 17 B4 directionally solidified boron-doped iron-gallium alloy magnetostrictive material.

[0090] For the convenience of description, Fe 83 Ga 17 B4 directionally solidified boron-doped iron-gallium alloy magnetostrictive material, referred to as directionally solidified rod.

[0091] A cylinder with a radius of 4 mm and a height of 10 mm was cut out of the middle 1 cm of the directionally solidified rod using the wire cutting method. Two discs with a radius of 4 mm and a thickness of 1.5 mm were then cut from both sides of the cylinder for microstructural characterization. The remaining cylinder with a radius of 4 mm and a height of 7 mm was cut longitudinally for strain testing. The microstructural characterization was performed using a Bruker D8 ADVANCE X-ray diffractometer, and the strain test was performed using a standard resistance strain gauge. The tensile test sample must follow the above steps to obtain a complete rod under the same conditions, from which a 42 mm × 4 mm dog bone specimen was cut using wire cutting. The test was performed using a KQLGW-500 testing machine at room temperature with a loading strain rate of 2×10 -3 s -1 The above test temperatures are all room temperature 300K. To reduce measurement errors, the samples were polished smooth before testing.

[0092] After testing, the Fe 83 Ga 17 The magnetostriction value of B4 directionally solidified boron-doped iron-gallium alloy magnetostrictive material is 151.1ppm, the (200) peak to (110) peak intensity ratio is 122.69%, the ultimate tensile strength is 608.8MPa, and the corresponding strain is 0.859%.

[0093] Comparative Example 1 A method for preparing an iron-gallium alloy magnetostrictive material comprises the following steps: Step 1: Determine that the crystal structure of the Fe-Ga alloy is a body-centered cubic structure, also known as a BCC structure, and use the SQS method to construct a 3×3×3 BCC supercell so that its composition is close to that of Fe. 83 Ga 17 The wave function cutoff energy was set to 400 eV in the VASP program. The supercell was fully relaxed using the projected augmented wave method, the spin-polarized generalized gradient approximation, and the Perdew-Burke-Ernzerhof exchange-correlation function. A 3 × 3 × 3 Monkhorst-Pack k-point grid was used for Brillouin zone integration. The atomic positions and lattice constants in the supercell were fully relaxed until the energy and force differences were less than 10, respectively. -5 eV and 0.01eV / Å, and the bulk model is obtained.

[0094] Based on the bulk model, a slab model consisting of six atomic layers was created, perpendicular to the (100) and (110) crystal planes. The slab model contained different surface configurations, with Fe and Ga atoms randomly occupying positions. Once the slab model was constructed, periodic boundary conditions were set in the x and y directions, and a vacuum space of 20 Å was set in the z direction. The two middle atomic layers were then fixed, allowing only the surface atoms to relax.

[0095] Figure 1 Figure a shows a schematic diagram of the (100) crystal plane six-atom layer flat plate model; Figure 1 Figure b shows a schematic diagram of the (110) crystal plane six-atom layer slab model. Table 2 shows the total energy of the six planes of the FeGa alloy; among them, the surface areas of the (100) crystal plane and the (110) crystal plane are 75.07 Å, respectively. 2 and 105.79 Å 2 .

[0096] Table 2 Total energy of the six surfaces of FeGa alloy It can be clearly seen from the results in Table 2 that the energies of the (100) and (110) crystal planes are: =-134.77 meV / Ǻ 2 and = -129.14 meV / Ǻ 2 ; then the energy difference is: = 5.63meV / Ǻ 2 , is a positive value. This indicates that the (110) crystal plane has lower energy and is more stable than the (100) crystal plane.

[0097] Step 2: preparing the iron-gallium alloy magnetostrictive material by directional solidification.

[0098] Step 2.1, weighing and melting: press Fe83 Ga 17 The stoichiometric ratio is 99.95% pure iron and 99.99% pure gallium. The weighed iron and gallium are placed in a copper crucible in a non-consumable vacuum arc melting furnace. The furnace door is closed and the vacuum is drawn to 3.0×10 -3 Pa, and then filled with high-purity argon gas to 2×10 4 Pa, repeatedly smelted four times at 1800℃~2400℃, to obtain Fe 83 Ga 17 alloy.

[0099] Step 2.2, Directional Solidification of Rods: 83 Ga 17 The alloy sample was crushed with pliers and placed in a ceramic tube with a diameter of 8 mm. The door was sealed and the vacuum was pumped to 3.0 × 10 -3 Pa, close the vacuum device, fill the cabin with a proper amount of high-purity argon, set the heating program, and when the temperature rises to 1600℃, keep it warm for five minutes and then start stretching at a rate of 110mm / h~120mm / h. After stretching, wait until the temperature in the cabin drops to room temperature, open the cabin door and take out the rod to make Fe 83 Ga 17 Directionally solidified iron-gallium alloy magnetostrictive material.

[0100] For the convenience of description, Fe 83 Ga 17 Directionally solidified iron-gallium alloy magnetostrictive material, referred to as directionally solidified rod.

[0101] A cylinder with a radius of 4 mm and a height of 10 mm was cut out of the middle 1 cm of the directionally solidified rod using the wire cutting method. Two discs with a radius of 4 mm and a thickness of 1.5 mm were then cut from both sides of the cylinder for microstructural characterization. The remaining cylinder with a radius of 4 mm and a height of 7 mm was cut longitudinally for strain testing. The microstructural characterization was performed using a Bruker D8 ADVANCE X-ray diffractometer, and the strain test was performed using a standard resistance strain gauge. The tensile test sample must follow the above steps to obtain a complete rod under the same conditions, from which a 42 mm × 4 mm dog bone specimen was cut using wire cutting. The test was performed using a KQLGW-500 testing machine at room temperature with a loading strain rate of 2×10 -3 s -1 The above test temperatures are all room temperature 300K. To reduce measurement errors, the samples were polished smooth before testing.

[0102] After testing, the Fe 83 Ga 17The magnetostriction value of the directionally solidified iron-gallium alloy magnetostrictive material is 105.9ppm, the (200) peak to (110) peak intensity ratio is 51.82%, the ultimate tensile strength is 363.7MPa, and the corresponding strain is 0.474%.

[0103] It can be seen that compared with Comparative Example 1, the Fe 83 Ga 17 The magnetostrictive properties of B3 directionally solidified boron-doped iron-gallium alloy magnetostrictive material increased by 182%, and the ultimate tensile strength and corresponding strain increased by 146% and 235%, respectively.

[0104] Figure 2 The X-ray diffraction patterns of the boron-doped iron-gallium alloy magnetostrictive materials prepared in Examples 1 to 4 and the iron-gallium alloy magnetostrictive material prepared in Comparative Example 1 are shown. Figure 2 It can be seen that after doping with B element, the intensity of the (200) peak changes significantly relative to the intensity of the (110) peak.

[0105] Figure 3 This is a comparison chart of the (200) peak to (110) peak intensity ratios of the boron-doped iron-gallium alloy magnetostrictive materials prepared in Examples 1 to 4 and the iron-gallium alloy magnetostrictive material prepared in Comparative Example 1. Figure 3 It can be seen that the boron-doped iron-gallium alloy magnetostrictive material doped with 3 at.% B in Example 1 significantly enhances the (200) peak orientation, which is consistent with the VASP theoretical prediction.

[0106] Figure 4 The strain test diagrams of the boron-doped iron-gallium alloy magnetostrictive materials prepared in Examples 1 to 4 and the iron-gallium alloy magnetostrictive material prepared in Comparative Example 1 are shown. Figure 4 Yes, it can be seen that after doping with B, the magnetostrictive properties of the magnetostrictive material are greatly improved, especially when x = 3, the magnetostrictive properties are improved the most.

[0107] Figure 5 The room temperature mechanical properties of the boron-doped iron-gallium alloy magnetostrictive materials prepared in Examples 1 to 4 and the iron-gallium alloy magnetostrictive materials prepared in Comparative Example 1 are shown. Figure 5It can be seen that the tensile direction is parallel to the directional solidification direction. With the increase of B doping, the ultimate tensile strength and ductility are significantly improved. On the one hand, as x increases, the Fe2B phase gradually increases at the grain boundaries as a hard and brittle secondary phase, which improves the tensile strength of the material, but at the same time reduces the grain boundary ductility, so the ultimate tensile strength gradually increases. On the other hand, as x increases, it leads to grain refinement, which may be accompanied by an increase in dislocation density, thereby enhancing the toughness of the alloy. Due to the competition between these two effects, the ductility first increases and then decreases, reaching a maximum value at x = 3.

[0108] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A boron-doped iron-gallium alloy magnetostrictive material, characterized in that: The boron-doped iron-gallium alloy magnetostrictive material is based on Fe 83 Ga 17 The alloy is used as a matrix, B is doped into the matrix, and a directional solidification process is performed to make the grains grow along the [100] direction to obtain a boron-doped iron-gallium alloy magnetostrictive material; The chemical formula of the boron-doped iron-gallium alloy magnetostrictive material is: Fe 83 Ga 17 B x ; where 1 ≤ x ≤ 4.

2. The boron-doped iron-gallium alloy magnetostrictive material according to claim 1, characterized in that: x =3。 3. A method for preparing the boron-doped iron-gallium alloy magnetostrictive material according to any one of claims 1 to 2, characterized in that: The following steps are involved: Fe 83 Ga 17 The alloy is used as a matrix, and B is doped into the matrix to prepare a boron-doped iron-gallium alloy; The boron-doped iron-gallium alloy is subjected to directional solidification treatment so that the grains grow along the [100] direction, thereby obtaining a boron-doped iron-gallium alloy magnetostrictive material.

4. The method for preparing the boron-doped iron-gallium alloy magnetostrictive material according to claim 3, characterized in that: The method for directional solidification of boron-doped iron-gallium alloy is as follows: Under the protection of an inert atmosphere, a boron-doped iron-gallium alloy is heated to a molten state. Then, at a stretching rate of 110 mm / h to 120 mm / h, the molten boron-doped iron-gallium alloy is stretched and directionally solidified from a heating zone to a cooling zone so that the grains grow along the [100] direction, thereby obtaining a boron-doped iron-gallium alloy magnetostrictive material.

5. The method for preparing the boron-doped iron-gallium alloy magnetostrictive material according to claim 4, characterized in that: The temperature when heated to the molten state is 1600°C.

6. The method for preparing the boron-doped iron-gallium alloy magnetostrictive material according to claim 3, characterized in that: The method for preparing boron-doped iron-gallium alloy is as follows: According to the chemical formula of boron-doped iron-gallium alloy magnetostrictive material Fe 83 Ga 17 B x The stoichiometric ratio of iron, gallium and boron raw materials were weighed respectively; Under the protection of an inert atmosphere, iron, gallium and boron raw materials are smelted to obtain a boron-doped iron-gallium alloy.

7. The method for preparing the boron-doped iron-gallium alloy magnetostrictive material according to claim 6, characterized in that: The smelting conditions are: The melting pressure is 2×10 4 Pa ~ 3×10 4 Pa; the melting temperature is 1800℃~2500℃.

8. The method for preparing the boron-doped iron-gallium alloy magnetostrictive material according to claim 6, characterized in that: The number of smelting times is 3 to 5 times.

Images