Preparation method of light rare earth pr-based ultrahigh magnetostrictive material

Abstract

The application relates to the technical field of magnetic functional materials, in particular to a light rare earth Pr-based ultrahigh magnetostrictive material and a preparation method thereof. The material is prepared from the following raw materials in parts by weight: 20-35 parts of praseodymium-neodymium mixed rare earth metal, 60-75 parts of pure iron, 3-8 parts of metal cobalt, 0.5-2 parts of metal niobium, 0.1-0.5 parts of additive A and 0.5-2 parts of additive B. The additive A is enriched at the grain boundaries, hinders the coarsening of the grains in the processing process, thereby obtaining fine grain structures, and provides an optimized microstructure basis for the magnetostrictive performance. Meanwhile, the additive B is used to improve the bonding state between the rare earth phase and the ferromagnetic matrix, and promotes the directional rotation process of the magnetic domains under the external magnetic field. The effects are combined with the inherent strong magnetic crystal anisotropy of the Pr element and the specific hydrogen crushing and magnetic field orientation hot-pressing process, and the magnetostrictive strain and driving capacity of the material are synergistically enhanced.

Description

Technical Field

[0001] This invention relates to the field of magnetic functional materials technology, specifically to a light rare earth Pr-based ultra-high magnetostrictive material and its preparation method. Background Technology

[0002] Magnetostrictive materials are functional materials whose length changes synchronously with an applied magnetic field, and can be used in medical, military, and daily life fields.

[0003] In the prior art, pure praseodymium-iron based alloys have problems such as easy oxidation and difficulty in fully utilizing magnetostrictive properties. These problems cannot be effectively solved by simple composition adjustment or conventional preparation processes. Furthermore, due to the large ionic radius of praseodymium, which exceeds the proportion of ions that form a stable phase structure, it is difficult to synthesize under normal pressure. Based on this, the present invention provides a method for preparing a light rare earth Pr-based ultra-high magnetostrictive material. Summary of the Invention

[0004] The purpose of this invention is to provide a light rare earth Pr-based ultra-high magnetostrictive material and its preparation method. The material prepared by this invention, through unique composition design and a composite additive system, combined with an optimized preparation process, not only possesses an ultra-high magnetostrictive coefficient but also exhibits excellent mechanical strength and thermal stability, effectively broadening the application range of this material in harsh environments.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In the first aspect, a light rare earth Pr-based ultra-high magnetostrictive material comprises the following raw materials in parts by weight: 20-35 parts of praseodymium-neodymium mixed rare earth metals, 60-75 parts of pure iron, 3-8 parts of metallic cobalt, 0.5-2 parts of metallic niobium, 0.1-0.5 parts of additive A and 0.5-2 parts of additive B;

[0007] The raw materials for additive A include boron mud, anhydrous magnesium chloride powder, and silicon powder.

[0008] The raw materials for additive B include additives, titanate coupling agents, and aluminum nitride.

[0009] Further, the additive A is prepared by the following steps: anhydrous magnesium chloride powder and silicon powder are mixed at a mass ratio of (3-5):1, placed in a ball mill jar, and ball-milled at 300-400 rpm for 2-4 hours to obtain a mixed powder. Boron mud is mixed with the mixed powder at a mass ratio of 1:(1.5-2.5), calcined at 650-800℃ for 2-4 hours under argon protection, cooled, pulverized, and passed through a 200-300 mesh sieve. A hydrochloric acid solution with a mass concentration of 5-10% is added, and the mixture is reacted at 40-60℃ for 1-2 hours. After the reaction is completed, the mixture is filtered, and the filter residue is washed with deionized water until neutral. The washed filter residue is then vacuum-dried at 80-100℃ to obtain additive A, wherein the mass of the hydrochloric acid is 5-7 times the mass of the mixed powder.

[0010] Furthermore, the boron sludge needs to be pretreated before preparing additive A.

[0011] Further, the pretreatment of the boron sludge includes the following steps: drying the boron sludge and pulverizing it to 60-80 mesh; mixing the pulverized boron sludge with the reaction solution at a mass ratio of 1:5; adding polyethylene glycol-400; stirring at 200-300 rpm for 20-30 min; letting it stand for 8-10 h; filtering; adding a 5% sodium bicarbonate aqueous solution to the filter residue; reacting for 8-10 min; filtering; drying the filter residue; and pulverizing it to 80-100 mesh to obtain the pretreated boron sludge, wherein the mass of the sodium bicarbonate aqueous solution is 25-30% of the mass of the filter residue.

[0012] Further, the reaction solution is prepared by the following method: succinic acid and deionized water are mixed at a mass ratio of 5:(90-95), and stirred until the succinic acid is completely dissolved to obtain an aqueous solution of succinic acid. Potassium dihydrogen phosphate is added to the aqueous solution of succinic acid, and the mixture is stirred at a speed of 100-200 rpm for 10-15 min to obtain the reaction solution, wherein the mass of potassium dihydrogen phosphate is 3% of the mass of succinic acid.

[0013] Further, the additive B is prepared by the following method: the additive and titanate coupling agent are mixed at a mass ratio of 1:(0.2-0.4), stirred and reacted at 60-80℃ for 3-7 min, then aluminum nitride powder is added, reacted for 0.5-1 h, cooled, and centrifuged to obtain a precipitate. The precipitate is washed 2-3 times with anhydrous ethanol and then vacuum dried at 70-90℃ to obtain additive B.

[0014] Further, the additive is prepared by the following method: menthol and gallic acid are mixed in a molar ratio of 1:1 and stirred at 80-85°C to obtain a second mixture. Zinc oxide powder is mixed with the second mixture at a mass ratio of 1:(4-6) and stirred at 75-80°C for 3-5 hours. After the reaction is completed, anhydrous ethanol is added and centrifuged to obtain a precipitate. The precipitate is washed with anhydrous ethanol 2-3 times and then dried to obtain the additive. The volume of anhydrous ethanol is 1-3 times the volume of the second mixture.

[0015] Furthermore, the average particle size of the aluminum nitride powder is less than 100 nm, and the mass of aluminum nitride is 5-10% of the mass of the additive.

[0016] Furthermore, the mass content of praseodymium in the praseodymium-neodymium mixed rare earth metal is not less than 75%.

[0017] Secondly, a method for preparing a light rare earth Pr-based ultra-high magnetostrictive material includes the following steps:

[0018] Step 1: Place the praseodymium-neodymium mixed rare earth metals, pure iron, metallic cobalt, metallic niobium, additive A, and additive B into a vacuum induction melting furnace, and evacuate to 5.0 × 10⁻⁻⁻⁶. 2 The pressure is above Pa, and high-purity argon gas is introduced to -0.05 MPa. The mixture is then melted at 1450-1550℃ to obtain a liquid alloy. The liquid alloy is then poured into a water-cooled copper mold to obtain an alloy ingot.

[0019] Step 2: Vacuum homogenization annealing is performed on the alloy ingot at a temperature of 950-1050℃ for 10-20 hours. After cooling, the alloy rod is obtained by wire cutting.

[0020] Step 3: Place the alloy rod in a vacuum reactor and absorb hydrogen at room temperature. Then, dehydrogenate and crush it at 300-500℃ to obtain coarse material. The process parameters for dehydrogenation and crushing are set as follows: absorb hydrogen at room temperature to a pressure of 0.1-0.2MPa, maintain the pressure for 2-4 hours, then evacuate to below 1Pa and heat to 300-400℃ for dehydrogenation for 1-3 hours.

[0021] Step 4: The rough material is oriented and pressed into shape under a magnetic field with a strength of 1.5-2.5T to obtain the intermediate product;

[0022] Step 5: The intermediate product is encapsulated in a pyrophyllite pressure-transmitting medium, placed in a six-sided hydraulic press, and kept at 800-1000℃ and 4-8GPa for 10-60 minutes. After cooling to room temperature, a light rare earth Pr-based ultra-high magnetostrictive material is obtained.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. In this invention, by introducing additive A, which is made from raw materials such as boron mud, the boron mud provides abundant magnesium and silicon sources and a porous framework, while anhydrous magnesium chloride acts as an activator to promote reactivity at high temperatures. This allows additive A to selectively accumulate at grain boundaries during alloy smelting and heat treatment, which can suppress the tendency of grain coarsening at high temperatures and obtain a uniform and fine grain structure. The resulting fine-grained structure provides a good microscopic basis for magnetostrictive properties. At the same time, these substances enriched at grain boundaries act as a physical barrier, preventing oxygen from diffusing inward along the grain boundaries, making praseodymium less prone to rapid oxidation at high temperatures, and improving the thermal stability of the material.

[0025] 2. In this invention, by introducing additive B containing modified additives and aluminum nitride, the additives provide good interfacial wettability and bonding sites, while the ultrafine aluminum nitride particles act as a hard reinforcing phase, dispersed at the phase boundary, effectively pinning dislocations and refining the magnetic domain structure. Together, they improve the interfacial bonding between the rare earth enriched phase and the ferromagnetic matrix, and promote the effective transmission of stress at the phase boundary, reducing the pinning energy of the magnetic domain walls during the reorientation process. This makes it easier for the magnetic domains to achieve directional alignment under an external magnetic field, thereby inducing a large magnetostrictive strain under a lower saturation magnetic field, allowing the magnetostrictive properties of the pure praseodymium-iron-based alloy to be fully utilized.

[0026] 3. In this invention, the uniform fine-grained structure created by additive A provides a carrier for the interface modification of additive B, while additive B effectively compensates for the shortcomings of A in phase boundary coupling. While improving magnetostrictive properties and mechanical strength, it also achieves high-performance output of the material under low driving field. At the same time, combined with a specific high-pressure hot pressing process, it solves the synthesis problem that it is difficult to form a stable Laves phase structure under normal pressure due to the large radius of praseodymium ions. Attached Figure Description

[0027] Figure 1 The present invention provides a flowchart of a light rare earth Pr-based ultra-high magnetostrictive material and its preparation method. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] It should be noted that the raw materials used in the following embodiments are all commercially available.

[0030] Example 1:

[0031] Preparation of reaction solution: Succinic acid and deionized water are mixed at a mass ratio of 5:90 and stirred until the succinic acid is completely dissolved to obtain an aqueous solution of succinic acid. Potassium dihydrogen phosphate is added to the aqueous solution of succinic acid and stirred at 100 rpm for 10 min to obtain the reaction solution. The mass of potassium dihydrogen phosphate is 3% of the mass of succinic acid.

[0032] Pretreatment of boron sludge: After drying the boron sludge, crush it to 60 mesh. Mix the crushed boron sludge with the reaction solution at a mass ratio of 1:5, add polyethylene glycol-400, stir at 200 rpm for 20 min, let stand for 8 h, filter, add 5% sodium bicarbonate aqueous solution to the filter residue, react for 8 min, filter, dry the filter residue, and crush it to 80 mesh to obtain the pretreated boron sludge, wherein the mass of sodium bicarbonate aqueous solution is 25% of the mass of the filter residue.

[0033] Preparation of Additive A: Anhydrous magnesium chloride powder and silicon powder were mixed at a mass ratio of 3:1 and placed in a ball mill jar. The mixture was ball-milled at 300 rpm for 2 hours to obtain a mixed powder. Pretreated boron mud was mixed with the mixed powder at a mass ratio of 1:1.5 and calcined at 650°C for 2 hours under argon protection. After cooling, the mixture was pulverized and passed through a 200-mesh sieve. A 5% hydrochloric acid solution was added and reacted at 40°C for 1 hour. After the reaction was completed, the mixture was filtered. The filter residue was washed with deionized water until neutral. The washed filter residue was vacuum dried at 80°C to obtain Additive A. The mass of the hydrochloric acid was 5 times the mass of the mixed powder.

[0034] Preparation of the additive: Menthol and gallic acid were mixed at a molar ratio of 1:1 and stirred at 80°C to obtain a second mixture. Zinc oxide powder was mixed with the second mixture at a mass ratio of 1:4 and stirred at 75°C for 3 hours. After the reaction was completed, anhydrous ethanol was added and centrifuged to obtain a precipitate. The precipitate was washed twice with anhydrous ethanol and dried to obtain the additive. The volume of anhydrous ethanol was 1 times the volume of the second mixture.

[0035] Preparation of Additive B: The additive and titanate coupling agent were mixed at a mass ratio of 1:0.2 and stirred at 60°C for 3 min. Then aluminum nitride powder was added and reacted for 0.5 h. After cooling, the mixture was centrifuged to obtain a precipitate. The precipitate was washed twice with anhydrous ethanol and then vacuum dried at 70°C to obtain Additive B.

[0036] The aluminum nitride powder has an average particle size of less than 100 nm, and the mass of aluminum nitride is 5% of the mass of the additive.

[0037] Among them, the mass content of praseodymium in the praseodymium-neodymium mixed rare earth metal is not less than 75%.

[0038] Raw material preparation: 20 parts praseodymium-neodymium mixed rare earth metals, 60 parts pure iron, 3 parts metallic cobalt, 0.5 parts metallic niobium, 0.1 parts additive A and 0.5 parts additive B.

[0039] Preparation of light rare earth Pr-based ultra-high magnetostrictive materials:

[0040] Step 1: Place the praseodymium-neodymium mixed rare earth metals, pure iron, metallic cobalt, metallic niobium, additive A, and additive B into a vacuum induction melting furnace, and evacuate to 5.0 × 10⁻⁻⁻⁶. 2 The pressure is above Pa, and high-purity argon gas is introduced to -0.05 MPa. The mixture is then melted at 1450 °C to obtain a liquid alloy. The liquid alloy is then poured into a water-cooled copper mold to obtain an alloy ingot.

[0041] Step 2: Vacuum homogenization annealing is performed on the alloy ingot at a temperature of 950℃ for 10 hours. After cooling, the alloy rod is obtained by wire cutting.

[0042] Step 3: Place the alloy rod in a vacuum reactor and absorb hydrogen at room temperature. Then, dehydrogenate and crush it at 300°C to obtain the coarse material. The process parameters for dehydrogenation and crushing are set as follows: absorb hydrogen at room temperature to a pressure of 0.1 MPa, maintain the pressure for 2 hours, then evacuate to below 1 Pa and heat to 300°C for dehydrogenation for 1 hour.

[0043] Step 4: The rough material is oriented and pressed into shape under a magnetic field with a strength of 1.5T to obtain the intermediate product;

[0044] Step 5: The intermediate product is encapsulated in a pyrophyllite pressure-transmitting medium, placed in a six-sided hydraulic press, and kept at 800℃ and 4GPa pressure for 10 minutes. After cooling to room temperature, a light rare earth Pr-based ultra-high magnetostrictive material is obtained.

[0045] Example 2:

[0046] Preparation of the reaction solution: Succinic acid and deionized water were mixed at a mass ratio of 5:93 and stirred until the succinic acid was completely dissolved to obtain an aqueous solution of succinic acid. Potassium dihydrogen phosphate was added to the aqueous solution of succinic acid, and the mixture was stirred at 200 rpm for 13 min to obtain the reaction solution. The mass of potassium dihydrogen phosphate was 3% of the mass of succinic acid.

[0047] Pretreatment of boron sludge: After drying the boron sludge, crush it to 80 mesh. Mix the crushed boron sludge with the reaction solution at a mass ratio of 1:5, add polyethylene glycol-400, stir at 250 rpm for 25 min, let stand for 9 h, filter, add 5% sodium bicarbonate aqueous solution to the filter residue, react for 9 min, filter, dry the filter residue, and crush it to 100 mesh to obtain the pretreated boron sludge, wherein the mass of sodium bicarbonate aqueous solution is 27% of the mass of the filter residue.

[0048] Preparation of Additive A: Anhydrous magnesium chloride powder and silicon powder were mixed at a mass ratio of 4:1 and placed in a ball mill jar. The mixture was ball-milled at 400 rpm for 3 hours to obtain a mixed powder. Pretreated boron mud was mixed with the mixed powder at a mass ratio of 1:2 and calcined at 700°C for 3 hours under argon protection. After cooling, the mixture was pulverized and passed through a 300-mesh sieve. A 7% hydrochloric acid solution was added and reacted at 50°C for 1.5 hours. After the reaction was completed, the mixture was filtered. The filter residue was washed with deionized water until neutral. The washed filter residue was vacuum dried at 90°C to obtain Additive A. The mass of the hydrochloric acid was 6 times the mass of the mixed powder.

[0049] Preparation of the additive: Menthol and gallic acid were mixed at a molar ratio of 1:1 and stirred at 83°C to obtain a second mixture. Zinc oxide powder was mixed with the second mixture at a mass ratio of 1:5 and stirred at 77°C for 4 hours. After the reaction was completed, anhydrous ethanol was added and centrifuged to obtain a precipitate. The precipitate was washed three times with anhydrous ethanol and then dried to obtain the additive. The volume of anhydrous ethanol was twice the volume of the second mixture.

[0050] Preparation of Additive B: The additive and titanate coupling agent were mixed at a mass ratio of 1:0.3 and stirred at 70°C for 5 min. Then aluminum nitride powder was added and reacted for 1 h. After cooling, the mixture was centrifuged to obtain a precipitate. The precipitate was washed three times with anhydrous ethanol and then vacuum dried at 80°C to obtain Additive B.

[0051] The aluminum nitride powder has an average particle size of less than 100 nm, and the mass of aluminum nitride is 8% of the mass of the additive.

[0052] Among them, the mass content of praseodymium in the praseodymium-neodymium mixed rare earth metal is not less than 75%.

[0053] Preparation of raw materials: 30 parts praseodymium-neodymium mixed rare earth metals, 70 parts pure iron, 6 parts metallic cobalt, 1 part metallic niobium, 0.3 parts additive A and 1 part additive B.

[0054] Preparation of light rare earth Pr-based ultra-high magnetostrictive materials:

[0055] Step 1: Place the praseodymium-neodymium mixed rare earth metals, pure iron, metallic cobalt, metallic niobium, additive A, and additive B into a vacuum induction melting furnace, and evacuate to 5.0 × 10⁻⁻⁻⁶. 2 The pressure is above Pa, and high-purity argon gas is introduced to -0.05 MPa. The mixture is then melted at 1500℃ to obtain a liquid alloy. The liquid alloy is then poured into a water-cooled copper mold to obtain an alloy ingot.

[0056] Step 2: Vacuum homogenization annealing of the alloy ingot is carried out at a temperature of 1000℃ for 15 hours. After cooling, the alloy rod is obtained by wire cutting.

[0057] Step 3: Place the alloy rod in a vacuum reactor and absorb hydrogen at room temperature. Then, dehydrogenate and crush it at 400°C to obtain the coarse material. The process parameters for dehydrogenation and crushing are set as follows: absorb hydrogen at room temperature to a pressure of 0.2 MPa, hold the pressure for 3 hours, then evacuate to below 1 Pa and heat to 350°C for dehydrogenation for 2 hours.

[0058] Step 4: The rough material is oriented and pressed into shape under a magnetic field with a strength of 1T to obtain the intermediate product;

[0059] Step 5: The intermediate product is encapsulated in a pyrophyllite pressure-transmitting medium, placed in a six-sided hydraulic press, and kept at 900℃ and 6GPa pressure for 30 minutes. After cooling to room temperature, a light rare earth Pr-based ultra-high magnetostrictive material is obtained.

[0060] Example 3:

[0061] Preparation of reaction solution: Succinic acid and deionized water are mixed at a mass ratio of 5:95 and stirred until the succinic acid is completely dissolved to obtain an aqueous solution of succinic acid. Potassium dihydrogen phosphate is added to the aqueous solution of succinic acid and stirred at 200 rpm for 15 min to obtain the reaction solution. The mass of potassium dihydrogen phosphate is 3% of the mass of succinic acid.

[0062] Pretreatment of boron sludge: After drying the boron sludge, crush it to 80 mesh. Mix the crushed boron sludge with the reaction solution at a mass ratio of 1:5, add polyethylene glycol-400, stir at 300 rpm for 30 min, let stand for 10 h, filter, add 5% sodium bicarbonate aqueous solution to the filter residue, react for 10 min, filter, dry the filter residue, and crush it to 100 mesh to obtain the pretreated boron sludge, wherein the mass of sodium bicarbonate aqueous solution is 30% of the mass of the filter residue.

[0063] Preparation of Additive A: Anhydrous magnesium chloride powder and silicon powder were mixed at a mass ratio of 5:1 and placed in a ball mill jar. The mixture was ball-milled at 400 rpm for 4 hours to obtain a mixed powder. Pretreated boron mud was mixed with the mixed powder at a mass ratio of 1:2.5 and calcined at 800℃ for 4 hours under argon protection. After cooling, the mixture was pulverized and passed through a 300-mesh sieve. A 10% hydrochloric acid solution was added and reacted at 60℃ for 2 hours. After the reaction was completed, the mixture was filtered. The filter residue was washed with deionized water until neutral. The washed filter residue was vacuum dried at 100℃ to obtain Additive A. The mass of the hydrochloric acid was 7 times the mass of the mixed powder.

[0064] Preparation of the additive: Menthol and gallic acid were mixed at a molar ratio of 1:1 and stirred at 85°C to obtain a second mixture. Zinc oxide powder was mixed with the second mixture at a mass ratio of 1:6 and stirred at 80°C for 5 hours. After the reaction was completed, anhydrous ethanol was added and centrifuged to obtain a precipitate. The precipitate was washed three times with anhydrous ethanol and dried to obtain the additive. The volume of anhydrous ethanol was three times the volume of the second mixture.

[0065] Preparation of Additive B: The additive and titanate coupling agent were mixed at a mass ratio of 1:0.4 and stirred at 80°C for 7 min. Then aluminum nitride powder was added and reacted for 1 h. After cooling, the mixture was centrifuged to obtain a precipitate. The precipitate was washed three times with anhydrous ethanol and then vacuum dried at 90°C to obtain Additive B.

[0066] The aluminum nitride powder has an average particle size of less than 100 nm, and the mass of aluminum nitride is 10% of the mass of the additive.

[0067] Among them, the mass content of praseodymium in the praseodymium-neodymium mixed rare earth metal is not less than 75%.

[0068] Raw material preparation: 35 parts praseodymium-neodymium mixed rare earth metals, 75 parts pure iron, 8 parts metallic cobalt, 2 parts metallic niobium, 0.5 parts additive A and 2 parts additive B.

[0069] Preparation of light rare earth Pr-based ultra-high magnetostrictive materials:

[0070] Step 1: Place the praseodymium-neodymium mixed rare earth metals, pure iron, metallic cobalt, metallic niobium, additive A, and additive B into a vacuum induction melting furnace, and evacuate to 5.0 × 10⁻⁻⁻⁶. 2 The pressure is above Pa, and high-purity argon gas is introduced to -0.05 MPa. The mixture is then melted at 1550 °C to obtain a liquid alloy. The liquid alloy is then poured into a water-cooled copper mold to obtain an alloy ingot.

[0071] Step 2: Vacuum homogenization annealing is performed on the alloy ingot at a temperature of 1050℃ for 20 hours. After cooling, the alloy rod is obtained by wire cutting.

[0072] Step 3: Place the alloy rod in a vacuum reactor and absorb hydrogen at room temperature. Then, dehydrogenate and crush it at 500°C to obtain the coarse material. The process parameters for dehydrogenation and crushing are set as follows: absorb hydrogen at room temperature to a pressure of 0.2 MPa, maintain the pressure for 4 hours, then evacuate to below 1 Pa and heat to 400°C for dehydrogenation for 3 hours.

[0073] Step 4: The rough material is oriented and pressed into shape under a magnetic field with a strength of 2.5T to obtain the intermediate product;

[0074] Step 5: The intermediate product is encapsulated in a pyrophyllite pressure-transmitting medium, placed in a six-sided hydraulic press, and kept at 1000℃ and 8GPa pressure for 60 minutes. After cooling to room temperature, a light rare earth Pr-based ultra-high magnetostrictive material is obtained.

[0075] Comparative Example 1: The difference between this comparative example and Example 1 is that this comparative example does not contain additive A.

[0076] Comparative Example 2 differs from Example 1 in that it does not contain additive B.

[0077] Comparative Example 3 differs from Example 1 in that hydrogen breakage is not performed during the preparation of the magnetostrictive material in this comparative example.

[0078] Comparative Example 4 differs from Example 1 in that the magnetostrictive material prepared in this comparative example does not undergo magnetic field orientation and hot-pressing synthesis processes.

[0079] Performance testing: The performance of the light rare earth Pr-based ultra-high magnetostrictive materials treated in Examples 1-3 and Comparative Examples 1-4 was tested, and the test data are recorded in the table below:

[0080] Table 1

[0081] Testing items Saturation magnetostriction coefficient (λs / ppm) Bending strength (σbb / MPa) Curie temperature (Tc / ℃) Example 1 1268 389 285 Example 2 1271 391 290 Example 3 1270 390 289 Comparative Example 1 780 251 255 Comparative Example 2 830 267 275 Comparative Example 3 970 305 280 Comparative Example 4 840 270 269

[0082] In the performance tests, the saturation magnetostriction coefficient was determined by strain gauge method (λs / ppm), the bending strength test was conducted in accordance with GB / T 232-2024, and the Curie temperature test was conducted in accordance with GB / T 43870.2-2024.

[0083] The data obtained from the performance tests show that the saturation magnetostriction coefficient, bending strength, and Curie temperature of the light rare earth Pr-based magnetostrictive materials prepared in Examples 1-3 are significantly higher than those in Comparative Examples 1-4. This indicates that additive A, through its selective enrichment and pinning effect at grain boundaries, effectively refines the alloy grains and suppresses grain coarsening at high temperatures, providing a uniform and stable microstructure basis for magnetic domain reversal. At the same time, additive B, by optimizing the interfacial bonding state between the rare earth phase and the ferromagnetic matrix, significantly reduces the movement resistance of the domain walls at the phase boundary and promotes the synergistic flipping of magnetic domains under an external magnetic field, thereby jointly improving the magnetostrictive response and mechanical integrity of the material. Through the dual regulation of grain boundaries and phase boundaries, the two additives solve the problems of insufficient magnetostrictive performance and brittle fracture caused by coarse grains and weak interfacial bonding in traditional praseodymium-iron-based alloys.

[0084] Furthermore, the complete hydrogen breakup and magnetic field orientation hot pressing process plays a crucial role in material densification and texture formation. Compared with the examples, Comparative Examples 3 and 4 lacked the hydrogen breakup and high-pressure orientation steps, resulting in structural defects and disordered magnetic domain orientation within the materials, manifested as deterioration in magnetostriction coefficient and bending strength. This indicates that the specific preparation process adopted in this invention is crucial for forming a highly oriented and dense Laves phase texture, and is an indispensable process guarantee for achieving ultra-high magnetostriction performance.

[0085] By comparing and analyzing the relevant data in the table, it can be seen that the light rare earth Pr-based ultra-high magnetostrictive material prepared by the present invention not only has a high magnetostriction coefficient, but also has excellent mechanical strength and thermal stability. This shows that the light rare earth Pr-based magnetostrictive material and its preparation method provided by the present invention achieve a good balance between performance and cost, have a broader market prospect, and are more suitable for promotion.

[0086] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0087] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A light rare earth Pr-based ultra-high magnetostrictive material, characterized in that, It includes the following raw materials by weight: 20-35 parts of praseodymium-neodymium mixed rare earth metals, 60-75 parts of pure iron, 3-8 parts of metallic cobalt, 0.5-2 parts of metallic niobium, 0.1-0.5 parts of additive A and 0.5-2 parts of additive B; The raw materials for additive A include boron mud, anhydrous magnesium chloride powder, and silicon powder. The raw materials for additive B include additives, titanate coupling agents, and aluminum nitride; The additive is prepared by the following method: menthol and gallic acid are mixed in a molar ratio of 1:1 and stirred at 80-85°C to obtain a second mixture. Zinc oxide powder is mixed with the second mixture at a mass ratio of 1:(4-6) and stirred at 75-80°C for 3-5 hours. After the reaction is completed, anhydrous ethanol is added and centrifuged to obtain a precipitate. The precipitate is washed with anhydrous ethanol 2-3 times and then dried to obtain the additive. The volume of anhydrous ethanol is 1-3 times the volume of the second mixture.

2. The light rare earth Pr-based ultra-high magnetostrictive material according to claim 1, characterized in that, Additive A is prepared by the following steps: Anhydrous magnesium chloride powder and silicon powder are mixed at a mass ratio of (3-5):1, placed in a ball mill jar, and ball-milled at 300-400 rpm for 2-4 hours to obtain a mixed powder. Boron mud is mixed with the mixed powder at a mass ratio of 1:(1.5-2.5), calcined at 650-800℃ for 2-4 hours under argon protection, cooled, pulverized, and passed through a 200-300 mesh sieve. A hydrochloric acid solution with a mass concentration of 5-10% is added, and the mixture is reacted at 40-60℃ for 1-2 hours. After the reaction is completed, the mixture is filtered, and the filter residue is washed with deionized water until neutral. The washed filter residue is then vacuum-dried at 80-100℃ to obtain additive A. The mass of the hydrochloric acid solution is 5-7 times the mass of the mixed powder.

3. The light rare earth Pr-based ultra-high magnetostrictive material according to claim 2, characterized in that, The boron mud needs to be pretreated before the preparation of additive A.

4. The light rare earth Pr-based ultra-high magnetostrictive material according to claim 3, characterized in that, The pretreatment of the boron sludge includes the following steps: drying the boron sludge and pulverizing it to 60-80 mesh; mixing the pulverized boron sludge with the reaction solution at a mass ratio of 1:5; adding polyethylene glycol-400; stirring at 200-300 rpm for 20-30 min; letting it stand for 8-10 h; filtering; adding a 5% sodium bicarbonate aqueous solution to the filter residue; reacting for 8-10 min; filtering; drying the filter residue and pulverizing it to 80-100 mesh to obtain the pretreated boron sludge, wherein the mass of the sodium bicarbonate aqueous solution is 25-30% of the mass of the filter residue.

5. The light rare earth Pr-based ultra-high magnetostrictive material according to claim 4, characterized in that, The reaction solution is prepared by the following method: succinic acid and deionized water are mixed at a mass ratio of 5:(90-95), and stirred until the succinic acid is completely dissolved to obtain an aqueous solution of succinic acid. Potassium dihydrogen phosphate is added to the aqueous solution of succinic acid, and the mixture is stirred at a speed of 100-200 rpm for 10-15 min to obtain the reaction solution. The mass of potassium dihydrogen phosphate is 3% of the mass of succinic acid.

6. The light rare earth Pr-based ultra-high magnetostrictive material according to claim 1, characterized in that, Additive B is prepared by the following method: the additive and titanate coupling agent are mixed at a mass ratio of 1:(0.2-0.4), stirred and reacted at 60-80℃ for 3-7 min, then aluminum nitride powder is added, and the reaction is carried out for 0.5-1 h. After cooling, the mixture is centrifuged to obtain a precipitate. The precipitate is washed 2-3 times with anhydrous ethanol and then vacuum dried at 70-90℃ to obtain additive B.

7. The light rare earth Pr-based ultra-high magnetostrictive material according to claim 6, characterized in that, The aluminum nitride powder has an average particle size of less than 100 nm, and the mass of aluminum nitride is 5-10% of the mass of the additive.

8. The light rare earth Pr-based ultra-high magnetostrictive material according to claim 1, characterized in that, The mass content of praseodymium in the praseodymium-neodymium mixed rare earth metal is not less than 75%.

9. The method for preparing the light rare earth Pr-based ultra-high magnetostrictive material according to any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Place praseodymium-neodymium mixed rare earth metals, pure iron, metallic cobalt, metallic niobium, additive A and additive B into a vacuum induction melting furnace, evacuate to above 5.0×10⁻²Pa, fill with high-purity argon to -0.05MPa, and melt at 1450-1550℃ to obtain an alloy liquid. Pour the alloy liquid into a water-cooled copper mold to obtain an alloy ingot. Step 2: Vacuum homogenization annealing is performed on the alloy ingot at a temperature of 1050℃ for 10-20 hours. After cooling, the alloy rod is obtained by wire cutting. Step 3: Place the alloy rod in a vacuum reactor and absorb hydrogen at room temperature. Then, dehydrogenate and crush it at 300-500℃ to obtain coarse material. The process parameters for dehydrogenation and crushing are set as follows: absorb hydrogen at room temperature to a pressure of 0.1-0.2MPa, maintain the pressure for 2-4 hours, then evacuate to below 1Pa and heat to 300-400℃ for dehydrogenation for 1-3 hours. Step 4: The rough material is oriented and pressed into shape under a magnetic field with a strength of 1.5-2.5T to obtain the intermediate product; Step 5: The intermediate product is encapsulated in a pyrophyllite pressure-transmitting medium, placed in a six-sided hydraulic press, and kept at 800-1000℃ and 4-8GPa for 10-60 minutes. After cooling to room temperature, a light rare earth Pr-based ultra-high magnetostrictive material is obtained.

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