Preparation method of permanent magnet alloy with high-entropy effect and stable ThMn12 structure

Abstract

According to the preparation method of the permanent magnet alloy with the high-entropy effect and the stable ThMn12 structure, the permanent magnet alloy with the high-entropy effect and the stable ThMn12 structure is prepared through the steps of proportioning of Sm, RE1, RE2 and RE3 elementary substances, electric arc melting, melt rapid quenching and heat treatment. According to the invention, multi-component rare earth elements are co-doped in the ThMn12 type SmFe12-based permanent magnet material to obtain the SmFe12-based permanent magnet alloy with relatively high thermal stability, and magnetic moment reduction and secondary phase generation caused by doping of traditional stable elements titanium and vanadium are overcome, so that degradation of magnetic performance of the permanent magnet alloy is avoided, and a new idea is provided for development of the ThMn12 type SmFe12-based permanent magnet material. The stability of the 1: 12 phase can be improved through the high-entropy effect of the multi-component rare earth element, and the prepared ThMn12 type nanocrystalline permanent magnet alloy has high intrinsic magnetic performance, low cost and simple and convenient process.

Description

Technical Field

[0001] This invention relates to a high-entropy effect stabilized ThMn 12 The method for preparing permanent magnet alloys with this structure belongs specifically to the field of rare earth permanent magnet materials technology. Background Technology

[0002] With the rapid development of the technology industry, rare earth permanent magnet materials are increasingly widely used in national defense and military equipment, aerospace and other fields. Global demand for rare earth elements continues to grow, especially for heavy rare earth elements such as terbium (Tb) and dysprosium (Dy) contained in neodymium iron boron magnets, where supply falls short of demand. Although high-abundance rare earth elements cerium (Ce) and lanthanum (La) have been gradually introduced into the neodymium iron boron system in recent years, developing new rare earth-poor, iron-rich permanent magnet materials remains of significant strategic importance from the perspectives of resource conservation, cost reduction, and promoting the green development of the rare earth industry.

[0003] ThMn 12 Type SmFe 12 The base material has attracted attention due to its low rare-earth content, excellent intrinsic magnetic properties, and good temperature stability. It is generally believed that bulk SmFe is difficult to prepare without adding traditional stabilizing elements such as titanium and vanadium. 12 Permanent magnet. This invention partially replaces SmFe with various rare earth elements. 12 In permanent magnet materials, Sm significantly improves the structural stability of the 1:12 phase by utilizing the high entropy effect of multi-component rare earth elements, thus obtaining structurally stable ThMn without the need to add traditional stabilizing elements. 12 Nanocrystalline permanent magnet alloys, characterized by low cost and ease of preparation, are ThMn 12 The development of SmFe-based permanent magnet materials provides a new approach. Summary of the Invention

[0004] This invention addresses the difficulty in preparing bulk ThMn without doping with traditional stabilizing elements such as titanium and vanadium. 12 Type SmFe 12 To address the problem of ThMn-based permanent magnet materials, a high-entropy effect stabilization method is proposed. 12 Method for preparing permanent magnet alloys with specific structures.

[0005] This invention provides a high-entropy effect to stabilize ThMn. 12 The method for preparing permanent magnet alloy structures includes the following steps: Step 1: Ingredients According to the general chemical formula of the ingot alloy (Sm 1-3x RE1 x RE2 x RE3 x )Fe 12The proportions were determined by selecting Sm, RE1, RE2, and RE3 as elemental raw materials for the formulation; Step 2: Arc melting The ingredients are melted and shaped into alloy ingots using a high-vacuum electric arc melting furnace, and then cut into small pieces and polished to remove the surface oxide scale. Smelting parameters: Furnace vacuum degree below 3×10 -3 At Pa, 1.0 atm of argon gas is introduced, the current is adjusted to 120A, and the melting is carried out 4 times, each melting lasts 15 seconds, with a total melting time of 60-75 seconds. Step 3: Rapid quenching of the melt After the alloy ingot is cooled to room temperature, it is placed in a quartz tube. Under a 0.5 atm argon protective atmosphere, a melt quenching process is used. The alloy ingot in the quartz tube is heated by high frequency induction heating until it melts. Then, it is blown off onto a high-speed rotating water-cooled copper roller with the help of argon gas to obtain an alloy strip. Process parameters: melt temperature 1300-1400℃, linear speed of water-cooled copper roller 40m / s, quartz tube diameter 0.65mm, distance from quartz tube opening to water-cooled copper roller 10mm, alloy strip thickness controlled at 12-15μm. Step 4: Heat treatment The alloy strip was placed inside a quartz tube, and the inside of the quartz tube was subjected to argon gas filling and purging five times, followed by evacuation to a vacuum of 3×10⁻⁶. -3 Pa, finally, the open end of the quartz tube was burned closed with an acetylene flame; after the muffle furnace was heated to 800℃, the sealed quartz tube was placed in, held at that temperature for 5-10 minutes, and then quenched and cooled to room temperature to obtain ThMn with high entropy effect. 12 The structure is a permanent magnet alloy; wherein the quenching cooling rate is ≥150℃ / s, and water is used as the quenching cooling medium.

[0006] RE1, RE2, and RE3 are any three of La, Ce, Nd, Gd, Sc, and Y.

[0007] The range of x is: 0.2≤x≤0.25.

[0008] Beneficial effects of this invention: This invention is based on the high entropy effect, and utilizes multi-component rare earth elements in ThMn 12 Type SmFe 12 Co-doping in permanent magnet materials yields bulk SmFe with high thermal stability without introducing traditional stabilizing elements for substitution. 12 This invention relates to a permanent magnet alloy. The method effectively overcomes the reduction in magnetic moment and the formation of secondary phases caused by the doping of traditional stabilizing elements such as titanium and vanadium, thereby avoiding the deterioration of the magnetic properties of the permanent magnet alloy and providing a suitable alternative for ThMn alloys. 12 Type SmFe 12This invention provides a new approach to the development of permanent magnet materials. It utilizes the high-entropy effect of multi-component rare earth elements to improve the stability of the 1:12 phase, resulting in ThMn... 12 Nanocrystalline permanent magnet alloys have high intrinsic magnetic properties, low cost, and simple processing. Attached Figure Description

[0009] Figure 1 : Embodiment 1 of the present invention (Sm 0.25 Nd 0.25 Gd 0.25 Y 0.25 )Fe 12 Backscattered scanning electron microscope image of the interior of the alloy ingot; Figure 2 Example 2 of the present invention (Sm) 0.25 Ce 0.25 Gd 0.25 Y 0.25 )Fe 12 Backscattered scanning electron microscope image of the interior of the alloy ingot; Figure 3 This invention (Sm) 0.25 Nd 0.25 Gd 0.25 Y 0.25 )Fe 12 and (Sm 0.25 Ce 0.25 Gd 0.25 Y 0.25 )Fe 12 XRD patterns of annealed alloy ribbons; Figure 4 This invention (Sm) 0.25 Nd 0.25 Gd 0.25 Y 0.25 )Fe 12 and (Sm 0.25 Ce 0.25 Gd 0.25 Y 0.25 )Fe 12 Hysteresis loop diagram of annealed alloy strip. Detailed Implementation

[0010] Example 1 Elemental Sm, Nd, Gd, and Y with a purity of 99.9% were selected as raw materials. Based on (Sm... 0.25 Nd 0.25 Gd 0.25 Y 0.25 )Fe 12 The nominal components were weighed out as follows: Sm 0.56g, Nd 0.54g, Gd 0.59g, Y 0.33g and Fe 9.99g.

[0011] Each elemental substance is placed in a copper crucible within a high-vacuum electric arc melting furnace, while a zirconium ingot is placed separately to absorb impurity gases within the furnace. When the vacuum level inside the high-vacuum electric arc melting furnace is below 3 × 10⁻⁶... -3 At a pressure of Pa, 1.0 atm of argon gas is introduced into the furnace. The current is adjusted to 120A, and the tungsten needle control lever is cranked to rapidly melt and shape the elemental raw material. Considering the loss of Sm element, the raw material is melted repeatedly only 4 times to ensure the uniformity of the alloy ingot composition, with each melting time lasting 15 seconds.

[0012] After the alloy ingot is cooled to room temperature, the surface oxide scale is removed by grinding, and it is cut into 3.5 g pieces. The resulting alloy pieces are placed in a quartz tube and heated to complete melting using a high-frequency induction heating coil under a 0.5 atm argon protective atmosphere. Rapid solidification is then performed using a water-cooled copper roller with a linear velocity of 40 m / s, a quartz tube diameter of 0.65 mm, and a distance of 10 mm between the quartz tube opening and the water-cooled copper roller. Once the alloy is completely melted, the molten alloy is blown onto the surface of the high-speed rotating water-cooled copper roller through a pre-introduced 0.15 MPa argon gas to obtain an alloy strip.

[0013] The alloy strip was placed inside a quartz tube, and the inside of the quartz tube was subjected to argon gas filling and purging five times, followed by evacuation to a vacuum of 3×10⁻⁶. -3 Pa, finally, the open end of the quartz tube was sealed by burning with an acetylene flame; after the muffle furnace was heated to 800℃, the sealed quartz tube was placed in, held at that temperature for 5 minutes, and then quenched using water as the quenching medium, and rapidly cooled to room temperature at a cooling rate of 150℃ / s to obtain ThMn with high entropy effect. 12 Permanent magnet alloy with a structure.

[0014] exist Figure 1 In the alloy, the α-Fe phase exhibits a small area fraction and a discontinuous fishbone-like structure, while the large matrix phase is a structurally stable 1:12 phase. This is a result of the high-entropy effect caused by the mixing of the four rare earth elements Sm, Nd, Gd, and Y in the alloy, which stabilizes the ThMn12 structure. Furthermore, the fishbone-like α-Fe phase is beneficial for the subsequent rapid melt quenching treatment of the alloy ingot, helping to further suppress the precipitation of the α-Fe phase and achieve compositional homogenization. Figure 3 Sm 0.25 Nd 0.25 Gd 0.25 Y 0.25 )Fe 12The diffraction peaks near 30°, 36°, 42°, and 48° in the XRD pattern all match the standard PDF card for the 1:12 phase, indicating the presence of a stable 1:12 phase in the annealed, rapidly quenched thin strip. This demonstrates that co-doping with rare earth elements Sm, Nd, Gd, and Y can indeed stabilize the ThMn phase in permanent magnet alloys. 12 Structure. Furthermore, the diffraction peaks near 45° correspond to the standard PDF card of the soft magnetic α-Fe phase, which is consistent with the backscattered electron microscopy (SEM) image of the alloy ingot. In nanocrystalline rare-earth permanent magnet alloys, an α-Fe soft magnetic phase with appropriate volume fraction and size is beneficial for enhancing the magnetic exchange coupling between the soft and hard magnetic phases in the permanent magnet alloy, and may also yield a certain remanence enhancement effect.

[0015] Example 2 Elemental Sm, Ce, Gd, Y, and Fe with a purity of 99.9% were selected as raw materials, according to (S m0.25 Nd 0.25 Gd 0.25 Y 0.25 )Fe 12 The nominal components were weighed out as follows: Sm 0.56g, Ce 0.52g, Gd 0.59g, Y 0.33g and Fe 10.0g.

[0016] Each elemental substance is placed in a copper crucible within a high-vacuum electric arc melting furnace, while a zirconium ingot is placed separately to absorb impurity gases within the furnace. When the vacuum level inside the high-vacuum electric arc melting furnace is below 3 × 10⁻⁶... -3 At a pressure of Pa, 1.0 atm of argon gas is introduced into the furnace. The current is adjusted to 120A, and the tungsten needle control lever is cranked to rapidly melt and shape the elemental raw material. Considering the loss of Sm element, the raw material is melted repeatedly only 4 times to ensure the uniformity of the alloy ingot composition, with each melting time lasting 15 seconds.

[0017] After the alloy ingot is cooled to room temperature, the surface oxide scale is removed by grinding, and it is cut into 3.5 g pieces. The resulting alloy pieces are placed in a quartz tube and heated to complete melting using a high-frequency induction heating coil under a 0.5 atm argon protective atmosphere. Rapid solidification is then performed using a water-cooled copper roller with a linear velocity of 40 m / s, a quartz tube diameter of 0.65 mm, and a distance of 10 mm between the quartz tube opening and the water-cooled copper roller. Once the alloy is completely melted, the molten alloy is blown onto the surface of the high-speed rotating water-cooled copper roller through a pre-introduced 0.15 MPa argon gas to obtain an alloy strip.

[0018] The alloy strip was placed inside a quartz tube, and the inside of the quartz tube was subjected to argon gas filling and purging five times, followed by evacuation to a vacuum of 3×10⁻⁶. -3Pa, finally, use an acetylene flame to heat the open end of the quartz tube to close and seal it; wait for the muffle furnace to heat up to 800℃, put in the sealed quartz tube, hold it at the temperature for 5 minutes and then quench it, using water as the quenching medium, and rapidly cool it to room temperature at a cooling rate of 150℃ / s.

[0019] observe Figure 2 It can be seen that the structurally stable 1:12 phase occupies (Sm 0.25 Ce 0.25 Gd 0.25 Y 0.25 )Fe 12 The main body of the alloy ingot shows that the high entropy effect caused by the mixing of four rare earth elements (Sm, Ce, Gd, and Y) in the alloy can stabilize ThMn. 12 Structure. The α-Fe phase in the alloy ingot has a small area fraction and exhibits a discontinuous, fishbone-like structure. Through... Figure 3 It can be seen that (Sm) 0.25 Nd 0.25 Gd 0.25 Y 0.25 )Fe 12 The diffraction peaks near 30°, 42°, and 48° in the XRD pattern all match the standard PDF card for the 1:12 phase, indicating the presence of a stable 1:12 phase in the annealed, rapidly quenched thin strip. This demonstrates that mixing rare earth elements such as Sm, Ce, Gd, and Y can indeed stabilize the ThMn phase in permanent magnet alloys. 12 Structure. Furthermore, the diffraction peaks near 45° correspond to the standard PDF card of the soft magnetic α-Fe phase, which is consistent with the backscattered electron microscopy (SEM) image of the alloy ingot. In nanocrystalline rare-earth permanent magnet alloys, an α-Fe soft magnetic phase with appropriate volume fraction and size is beneficial for enhancing the magnetic exchange coupling between the soft and hard magnetic phases in the permanent magnet alloy, and may also yield a certain remanence enhancement effect.

Claims

1. A high-entropy effect stabilizes ThMn 12 The method for preparing permanent magnet alloys with a structure is characterized by, The preparation method includes the following steps: Step 1: Ingredients According to the general chemical formula of the ingot alloy (Sm 1-3x RE1 x RE2 x RE3 x )Fe 12 The proportions were determined by selecting Sm, RE1, RE2, and RE3 as elemental raw materials for the formulation; Step 2: Arc melting The ingredients are melted into alloy ingots using a high-vacuum electric arc melting furnace, and then cut into small pieces and polished to remove the surface oxide scale. Smelting parameters: Furnace vacuum degree below 3×10 -3 At Pa, 1.0 atm of argon gas is introduced, the current is adjusted to 120A, and the melting is carried out 4 times, each melting lasts 15 seconds, with a total melting time of 60-75 seconds. Step 3: Rapid quenching of the melt After the alloy ingot is cooled to room temperature, it is placed in a quartz tube. Under a 0.5 atm argon protective atmosphere, a melt quenching process is used. The alloy ingot in the quartz tube is heated by high frequency induction heating until it melts. Then, it is blown off onto a high-speed rotating water-cooled copper roller with the help of argon gas to obtain an alloy strip. Process parameters: melt temperature 1300-1400℃, linear speed of water-cooled copper roller 40m / s, quartz tube diameter 0.65mm, distance from quartz tube opening to water-cooled copper roller 10mm, alloy strip thickness controlled at 12-15μm. Step 4: Heat treatment The alloy strip was placed inside a quartz tube, and the inside of the quartz tube was subjected to argon gas filling and purging five times, followed by evacuation to a vacuum of 3×10⁻⁶. -3 Pa, finally, the open end of the quartz tube was burned closed with an acetylene flame; after the muffle furnace was heated to 800℃, the sealed quartz tube was placed in, held at that temperature for 5-10 minutes, and then quenched and cooled to room temperature to obtain ThMn with high entropy effect. 12 The structure is a permanent magnet alloy; wherein the quenching cooling rate is ≥150℃ / s, and water is used as the quenching cooling medium.

2. A high-entropy effect stabilizing ThMn according to claim 1 12 The method for preparing permanent magnet alloys with a structure is characterized by: RE1, RE2, and RE3 are any three of La, Ce, Nd, Gd, Sc, and Y.

3. A high-entropy effect stabilizing ThMn according to claim 1 12 The method for preparing permanent magnet alloys with a structure is characterized by: The range of x is: 0.2≤x≤0.25.

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