Alloy powder and preparation method thereof, and application of alloy powder

Abstract

The present application provides an alloy powder, the composition of the alloy powder expressed in atomic percentage is: (Re 1‑a Sm a ) x M y N 100‑x‑y , wherein Re is selected from at least one of La, Ce, Pr, Nd and Y, M is selected from at least one of Cu, Co, Fe and Zr, N is selected from at least one of Al, Ag, Bi, Ga and Sn, the value of x is 50 to 75, the value of y is 15 to 35, and the value of a is 0.1 to 1.0. The present application also provides a method for preparing the alloy powder, a method for preparing a permanent magnet using the alloy powder, a permanent magnet and a device using the permanent magnet. The present application uses the alloy powder formed by the above-mentioned high-activity rare earth elements and metal elements to effectively reduce the melting point of the alloy powder. Using the alloy powder as a binder can achieve hot pressing and sintering preparation of permanent magnets with higher density and higher performance.

Description

Technical Field

[0001] The present application relates to the field of permanent magnetic materials, and in particular to an alloy powder, a method for preparing the alloy powder, a method for preparing a permanent magnet using the alloy powder, the permanent magnet, and a device using the permanent magnet. Background Art

[0002] As an important functional material, permanent magnet materials play a vital role in all aspects of social life. 14 B) compounds have become the most widely used rare earth magnetic materials due to their excellent magnetic properties. However, the low Curie temperature has severely limited the application of NdFeB in high temperature fields such as new energy vehicle drive motors. 17 N3) compounds have attracted much attention from researchers due to their excellent intrinsic magnetic properties. 17 N3 compounds have the same 14 B has a comparable saturation magnetization (1.54T), a higher magnetocrystalline anisotropy field (14T) and better corrosion resistance. More importantly, Sm2Fe 17 The Curie temperature of N3 compound is 470℃, which is much higher than that of Nd2Fe 14 B's 312℃ can meet the operating temperature requirements of permanent magnet motors in high temperature areas.

[0003] However, due to the Sm2Fe 17 N3 compounds decompose into SmN, α-Fe, and N2 at around 600°C. Conventional sintered magnet production processes typically require sintering temperatures exceeding 1000°C, making it impossible to produce SmFeN sintered magnets using high-temperature sintering processes similar to those used to produce NdFeB permanent magnets. This severely impacts the magnet production process and its application areas. Currently, SmFeN permanent magnets primarily exist in the form of bonded magnets, which exhibit relatively low magnetic properties. Summary of the Invention

[0004] In view of this, in order to solve at least one of the above defects, an embodiment of the present application provides a high-activity rare earth-based low-melting-point alloy powder.

[0005] In addition, the embodiments of the present application also provide one or more methods for preparing alloy powders, a method for preparing permanent magnets using the alloy powders, the permanent magnets, and a device using the permanent magnets.

[0006] In a first aspect, an embodiment of the present application provides an alloy powder, wherein the composition of the alloy powder expressed in atomic percentage is: (Re 1-a Sm a ) x M y N 100-x-y, wherein Re is selected from at least one of La, Ce, Pr, Nd and Y, M is selected from at least one of Cu, Co, Fe and Zr, N is selected from at least one of Al, Ag, Bi, Ga and Sn, the value range of x is 50 to 75, the value range of y is 15 to 35, and the value range of a is 0.1 to 1.0.

[0007] By using the alloy powder formed by the above-mentioned high-activity rare earth elements and metal elements, the melting point of the alloy powder can be effectively lowered. By using the alloy powder as a binder, hot pressing and sintering preparation of permanent magnets with higher density and higher performance can be achieved. In addition, since the alloy powder is a samarium-containing compound, it is particularly suitable for the preparation of samarium iron nitrogen magnets, which is beneficial to improve the interfacial wettability of the low-melting point alloy powder after melting on the samarium iron nitrogen magnetic particles, thereby improving the compatibility of the alloy powder and the samarium iron nitrogen magnetic particles.

[0008] In combination with the first aspect, in some possible embodiments, the melting point of the alloy powder is less than or equal to 490°C.

[0009] The melting point of the alloy powder is less than or equal to 490°C, which is much lower than the decomposition temperature of magnetic particles such as samarium iron nitrogen (around 600°C). The alloy powder is used as a binder in the preparation process of permanent magnets, which helps to reduce the temperature of hot pressing and sintering, thereby reducing the risk of decomposition of magnetic particles such as samarium iron nitrogen.

[0010] In combination with the first aspect, in some possible embodiments, the average particle size of the alloy powder is less than or equal to 20 μm.

[0011] The alloy powder has a small average particle size and can be evenly dispersed in the magnetic particles and fully contact the surface of the magnetic particles, which is beneficial to improving the density and magnetic properties of the permanent magnet.

[0012] In combination with the first aspect, in some possible embodiments, the oxygen content of the alloy powder is less than or equal to 1 wt.%.

[0013] If the oxygen content of the alloy powder is too high, an oxide shell will form on the surface of the alloy powder. This oxide shell is dense, hard and has a high melting point. The presence of this oxide layer not only blocks the contact between the alloy powder inside the oxide shell and the samarium iron nitrogen magnetic particles, but also reduces the compatibility between the alloy powder and the samarium iron nitrogen magnetic particles, making it difficult for the alloy powder and the magnetic particles to be evenly dispersed, thereby affecting the density and magnetic properties of the permanent magnet finally formed. Moreover, due to the high melting point of the oxide layer, the melting point of the alloy powder is also increased, which increases the hot pressing sintering temperature of the samarium iron nitrogen magnet and increases the risk of decomposition of the samarium iron nitrogen magnetic particles. Therefore, it is necessary to control the oxygen content of the alloy powder to be as low as possible. However, considering the cost and actual operability, the oxygen content of the alloy powder in this embodiment is controlled to be less than or equal to 1wt.%.

[0014] A second aspect of the present application provides a method for preparing alloy powder, the preparation method comprising the following steps:

[0015] The raw materials of the alloy powder are melted and cooled to obtain a master alloy ingot;

[0016] Rapidly quenching the master alloy ingot to obtain alloy flakes; and

[0017] Crushing the alloy flakes to obtain the alloy powder,

[0018] The alloy powder has the following composition expressed in atomic percentage: 1-a Sm a ) x M y N 100-x-y , wherein Re is selected from at least one of La, Ce, Pr, Nd and Y, M is selected from at least one of Cu, Co, Fe and Zr, N is selected from at least one of Al, Ag, Bi, Ga and Sn, the value range of x is 50 to 75; the value range of y is 15 to 35, and the value range of a is 0.1 to 1.0.

[0019] The alloy powder prepared by the smelting-melt rapid quenching-alloy sheet crushing process has a low melting point, high activity and a small average particle size; melt rapid quenching can make the melt of the master alloy ingot melted re-solidify at an extremely high degree of supercooling, which is conducive to the formation of ultrafine grains, and the alloy strips formed by melt rapid quenching are conducive to the subsequent alloy sheet being crushed to form a powdered alloy with a smaller average particle size, so as to improve the dispersibility of the alloy powder in the magnetic particles. Therefore, the alloy powder prepared by the preparation method of the present application can be used as a spare alloy binder for permanent magnet production, which can effectively reduce the temperature of hot pressing and sintering in the permanent magnet preparation process, reduce the risk of high-temperature decomposition of magnetic particles, and thus help to improve the density and magnetic properties of the permanent magnet. In addition, the preparation method of the alloy powder is simple, and the equipment and instruments are vacuum arc furnaces or vacuum induction furnaces commonly used in the field of rare earth-based alloy preparation, which are easy to achieve mass production.

[0020] In conjunction with the second aspect, in some possible embodiments, before the step of smelting the raw materials of the alloy powder, the preparation method further includes the steps of:

[0021] The raw materials of the alloy powder are batched,

[0022] The error between the weighed mass and the theoretical mass of each component in the raw materials during batching is 0.5% to 10%.

[0023] During the batching process, the error between the weighed mass and the theoretical mass of the alloy powder raw materials is strictly controlled to ensure the accuracy of the ratio between the various components of the alloy powder, thereby ensuring that the prepared alloy powder can reach the ideal low melting point.

[0024] In combination with the second aspect, in some possible embodiments, the melting is vacuum arc melting, and the melting current is 100A to 400A.

[0025] Vacuum arc melting can effectively reduce the oxygen content in alloy powders. During vacuum arc melting, the current level affects the furnace's output power, which in turn affects the melting of the alloy powder raw materials. If the current is too low, the raw materials will not melt fully. If the current is too high, the molten raw materials will volatilize under the influence of the high current, resulting in raw material loss, reducing the accuracy of the alloy powder's component ratios, and thus leading to uncertainty in the melting point of the final alloy powder. Therefore, by controlling the vacuum arc melting current within the range of 100A to 400A, the components of the alloy powder raw materials can be fully melted while reducing the risk of raw material volatilization after melting, thereby improving the accuracy of the raw material ratios and obtaining an ideal low-melting-point alloy powder.

[0026] In conjunction with the second aspect, in some possible embodiments, the step of melting the alloy powder raw material and obtaining the master alloy ingot after cooling specifically includes the following steps:

[0027] evacuating the smelting equipment containing the raw materials;

[0028] Filling the vacuumed melting equipment with inert gas;

[0029] Melting the raw materials to obtain hot ingots; and

[0030] The hot cast ingot is cooled to obtain the master alloy cast ingot.

[0031] In combination with the second aspect, in some possible embodiments, the vacuum degree of the smelting equipment is less than or equal to 0.1 Pa; and the pressure of the inert gas is in the range of -0.08 MPa to -0.02 MPa.

[0032] Performing the smelting process under vacuum can further reduce the loss of active components (such as active rare earth elements) in the raw materials due to oxidation, which helps improve the accuracy of the ratio between the raw material components of the alloy powder and also helps increase the activity of the alloy powder. By introducing an inert gas into the smelting equipment and maintaining a certain negative pressure, the oxygen content in the smelting equipment can be reduced, which in turn helps reduce the oxygen content of the alloy powder.

[0033] In combination with the second aspect, in some possible embodiments, the thickness of the alloy sheet is 0.1 mm to 1 mm.

[0034] By controlling the thickness of the alloy sheet, it is beneficial to obtain alloy powder with a smaller average particle size.

[0035] In combination with the second aspect, in some possible embodiments, during the rapid quenching of the melt, the rotational speed of the roller is 25 to 65 m / s.

[0036] During the rapid quenching process of the melt, the oxygen content of the alloy powder can be effectively reduced through inert gas protection; in addition, by controlling the rotation speed of the copper roller, it is beneficial to control the grain size formed by the melt cooling, thereby obtaining ultrafine grains.

[0037] In combination with the second aspect, in some possible embodiments, the rapid quenching of the melt is performed under the protection of an inert gas, the inert gas is argon or helium, and the purity of the inert gas is greater than or equal to 99.99%.

[0038] The use of high-purity inert gas for protection during the rapid quenching of the melt is beneficial to reducing the oxygen content in the alloy powder.

[0039] In combination with the second aspect, in some possible embodiments, the crushing method includes at least one of ball milling, hydrogen explosion and air flow milling.

[0040] A third aspect of the present invention provides a permanent magnet, comprising magnetic particles, a matrix, and an intermediate phase between the magnetic particles and the matrix, wherein the matrix has the following composition expressed in atomic percentage: (Re 1-a Sm a ) x M y N 100-x-y , wherein Re is selected from at least one of La, Ce, Pr, Nd and Y, M is selected from at least one of Cu, Co, Fe and Zr, N is selected from at least one of Al, Ag, Bi, Ga and Sn, the value range of x is 50 to 75, the value range of y is 15 to 35, and the value range of a is 0.1 to 1.0; the intermediate phase contains at least part of the elements of the magnetic particles and at least part of the elements of the matrix.

[0041] By adopting the matrix of the above components, the density and magnetic properties of the permanent magnet are effectively improved.

[0042] In combination with the third aspect, in some possible embodiments, the magnetic particles contain Sm, Fe and N.

[0043] Since the matrix contains samarium, the matrix is ​​similarly compatible with the samarium iron nitrogen magnetic particles, which is beneficial to improving the interface compatibility between the matrix and the surface of the magnetic particles, so that the matrix is ​​evenly coated on the surface of the samarium iron nitrogen magnetic particles, which is beneficial to improving the density and magnetic properties of the permanent magnet.

[0044] In combination with the third aspect, in some possible embodiments, the density of the permanent magnet is greater than or equal to 6.6 g / cm 3 , remanence (Br) greater than or equal to 8.5kGs, intrinsic coercive force (Hcj) greater than or equal to 14.5kOe, and maximum magnetic energy product (HBmax) greater than or equal to 15.5MGOe.

[0045] A fourth aspect of the present invention provides a method for preparing a permanent magnet, the method comprising the following steps:

[0046] An alloy powder is mixed with magnetic particles, oriented in a magnetic field, and formed to obtain an intermediate billet, wherein the alloy powder is the alloy powder described in the first aspect of the embodiment of the present application or the alloy powder prepared by the method for preparing the alloy powder described in the second aspect of the embodiment of the present application; and

[0047] The intermediate blank is hot pressed and sintered, so that the alloy powder is melted and solidified into a matrix located around the magnetic particles, and an intermediate phase is formed between the magnetic particles and the matrix to obtain a permanent magnet, wherein the intermediate phase contains at least part of the elements of the magnetic particles and at least part of the elements of the matrix.

[0048] The aforementioned alloy powder is used as a binder and mixed with magnetic particles to prepare permanent magnets. Since the aforementioned alloy powder has a low melting point, it is beneficial to reduce the temperature of hot pressing and sintering, reducing the risk of decomposition of magnetic particles during hot pressing and sintering. The low hot pressing and sintering temperature is beneficial to ensure the high activity of the alloy powder during the hot pressing process, so that the alloy powder can fully absorb the oxygen in the oxide layer on the outer surface of the magnetic particles and repair the surface defects of the magnetic particles, which is beneficial to improve the magnetic properties and density of the permanent magnet. In addition, the aforementioned alloy powder contains samarium and is particularly suitable for preparing samarium iron nitrogen magnets. The alloy powder and samarium iron nitrogen magnetic particles are similar and compatible, which is beneficial to improve the wettability of the molten alloy melt on the surface of the samarium iron nitrogen magnetic particles and improve the interface compatibility between the alloy powder and the samarium iron nitrogen magnetic particles, so that the alloy melt is evenly distributed on the surface of the samarium iron nitrogen magnetic particles.

[0049] In conjunction with the fourth aspect, in some possible embodiments, the temperature of the hot pressing sintering does not exceed 500°C.

[0050] The hot pressing sintering temperature does not exceed 500°C. Low temperature sintering can reduce the risk of decomposition of magnetic particles and thus improve the magnetic properties of permanent magnets.

[0051] The fifth aspect of the embodiments of the present application provides a device, which includes a accommodating component and a permanent magnet accommodated in the accommodating component. The permanent magnet is the permanent magnet described in the third aspect of the embodiments of the present application or a permanent magnet prepared by the permanent magnet preparation method described in the fourth aspect of the embodiments of the present application.

[0052] In combination with the fifth aspect, in some possible embodiments, the device is a motor, and the accommodating component is a rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a flow chart for preparing alloy powder in one embodiment of the present application.

[0054] Figure 2 This is a flow chart of the preparation of a permanent magnet in one embodiment of the present application.

[0055] Figure 3 This is a diagram of the preparation process of a permanent magnet in one embodiment of the present application.

[0056] Figure 4 It is a schematic structural diagram of a portion of the permanent magnet structure in one embodiment of the present application.

[0057] Figure 5 It is a structural diagram of a device in one embodiment of the present application.

[0058] Figure 6 Figures (a) and (b) are respectively the (Ce 0.8 Sm 0.2 ) 72 Cu 28 Photographs of the master alloy ingot and alloy strip, (c) is (Ce 0.8 Sm 0.2 ) 72 Cu 28 Scanning electron microscope image of alloy powder.

[0059] Description of main component symbols

[0060] Permanent magnet 100

[0061] Alloy powder 10

[0062] Magnetic particles 20

[0063] Intermediate blank 30

[0064] Base 40

[0065] Interphase 50

[0066] Device 200

[0067] Accommodating component 210 DETAILED DESCRIPTION

[0068] The following describes the embodiments of the present application in conjunction with the accompanying drawings. Unless otherwise specified, the data range values ​​recorded in this application should include the end values.

[0069] Since Sm2Fe 17 N3 decomposes into SmN, α-Fe, and N2 at around 600°C, while the eutectic temperature of the Sm-Fe alloy is approximately 720°C, which is higher than the decomposition temperature of SmFeN. Therefore, the high-temperature sintering process (sintering temperature > 1000°C) similar to that used to prepare sintered NdFeB is not suitable for the production of SmFeN sintered magnets. SmFeN magnets can only be prepared using a method similar to low-temperature solid-phase sintering. However, when SmFeN magnetic particles are sintered at low-temperature solid-phase sintering, the sintering temperature must be below 600°C. At this temperature, the SmFeN magnetic particles cannot form a low-melting-point grain boundary phase, making the preparation of SmFeN sintered magnets extremely difficult.

[0070] In order to solve the above problems, the applicant has found that the use of suitable low-melting-point metals or alloys as adhesives to assist in the molding of samarium iron nitrogen magnetic particles, and combined with a low-temperature solid-phase sintering process, is an important means for preparing high-density and high-performance samarium iron nitrogen magnets. To this end, the embodiment of the present application provides an alloy powder with a low melting point and high activity, which can be used as an alloy adhesive in the molding process of samarium iron nitrogen magnets to assist in the molding of samarium iron nitrogen magnetic particles to prepare samarium iron nitrogen magnets with high density and high magnetic properties. It is understandable that the alloy powder improved in the embodiment of the present application can also be used as a low-melting-point alloy adhesive for other permanent magnets. In the following embodiments, the preparation of samarium iron nitrogen magnets using alloy powders is used as an example for illustration.

[0071] The present invention provides an alloy powder, the composition of which is expressed in atomic percentages as follows: (Re 1-a Sm a ) x M y N 100-x-y , wherein Re is selected from at least one of the rare earth elements lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd) and yttrium (Y), M is selected from at least one of the metal elements copper (Cu), cobalt (Co), iron (Fe) and zirconium (Zr), and N is selected from at least one of the metal elements aluminum (Al), silver (Ag), bismuth (Bi), gallium (Ga) and tin (Sn), wherein a×x is the atomic percentage of the Sm element, x×(1-a) is the atomic percentage of the Re element, y is the atomic percentage of the M element, (100-xy) is the atomic percentage of the N element, the value range of x is 50 to 75, the value range of y is 15 to 35, and the value range of a is 0.1 to 1.0.

[0072] In some embodiments, the melting point of the alloy powder is less than or equal to 490° C., further less than or equal to 450° C., further less than or equal to 410° C., and further less than or equal to 400° C. By using the alloy powder formed by the above highly active rare earth elements and metal elements and strictly controlling the atomic percentages of the alloy powder, the melting point of the alloy powder can be made less than or equal to 490° C.

[0073] In some embodiments, the alloy powder has an average particle size of less than or equal to 20 μm, further less than or equal to 15 μm, and further less than or equal to 10 μm. The small average particle size of the alloy powder allows for uniform dispersion within the samarium iron nitride magnetic particles and sufficient contact with the surfaces of the magnetic particles. Furthermore, the small particle size of the alloy powder allows for sufficient filling of the pores between the magnetic particles, thereby improving the density and magnetic properties of the samarium iron nitride magnet.

[0074] In some embodiments, the oxygen content of the alloy powder is less than or equal to 1wt.%. If the oxygen content of the alloy powder is too high, an oxide shell will form on the surface of the alloy powder, and this oxide shell is dense, hard and has a high melting point. The presence of this oxide layer not only blocks the contact between the alloy powder inside the oxide shell and the samarium iron nitrogen magnetic particles, but also reduces the compatibility of the alloy powder and the samarium iron nitrogen magnetic particles, making it difficult for the alloy powder and the magnetic particles to be evenly dispersed, thereby affecting the density and magnetic properties of the final formed samarium iron nitrogen magnet; moreover, due to the high melting point of the oxide layer, it also increases the melting point of the alloy powder, increases the hot pressing sintering temperature of the samarium iron nitrogen magnet, and increases the risk of decomposition of the samarium iron nitrogen magnetic particles. Therefore, it is necessary to control the oxygen content of the alloy powder as low as possible, but considering the cost and actual operability, this embodiment controls the oxygen content of the alloy powder to be less than or equal to 1wt.%, further the oxygen content is less than or equal to 0.5wt.%, and further the oxygen content is less than or equal to 0.2wt.%.

[0075] By using alloy powders formed from the above-mentioned highly active rare earth elements and metal elements and strictly controlling the atomic percentages of each element in the alloy powder, the melting point of the alloy powder can be made less than or equal to 490°C. Since the melting point of the alloy powder is much lower than the decomposition temperature of the samarium iron nitride magnetic particles (approximately 600°C), the alloy powder can be used as a binder for the hot pressing and sintering of samarium iron nitride magnets, which helps to lower the hot pressing and sintering temperature and reduce the risk of decomposition of the samarium iron nitride magnetic particles. Therefore, it is possible to prepare samarium iron nitride sintered magnets with higher density and higher magnetic properties. In addition, the alloy powder is a samarium-containing compound. According to the principle of like dissolves like, it is beneficial to improve the interfacial wettability of the low-melting-point alloy powder after melting on the samarium iron nitride magnetic particles, thereby improving the compatibility of the alloy powder and the samarium iron nitride magnetic particles.

[0076] See also Figure 1Based on the same technical concept, the present invention also provides a method for preparing the aforementioned alloy powder, the method comprising the following steps:

[0077] Step S10: smelting the alloy powder raw materials and obtaining a master alloy ingot after cooling.

[0078] Step S20: subjecting the master alloy ingot to melt rapid quenching to obtain alloy sheets.

[0079] Step S30: crushing the alloy flakes to obtain the alloy powder.

[0080] Before step S10, the preparation method further comprises the steps of:

[0081] The raw materials for the alloy powder are batched. During batching, the error between the weighed mass and the theoretical mass of each component is between 0.5% and 10%, further between 0.5% and 5%, and further between 0.5% and 3%. During the batching process, controlling the error between the weighed mass and the theoretical mass of each component is critical to obtaining a low-melting-point alloy powder. By strictly controlling the error between the weighed mass and the theoretical mass of each raw material for the alloy powder, the accuracy of the ratio between the various components of the alloy powder is ensured, thereby ensuring that the prepared alloy powder can achieve the desired low melting point.

[0082] In step S10 , the melting is vacuum arc melting or vacuum induction melting, and the raw materials of the alloy powder can be weighed and then added into a vacuum arc melting furnace or a vacuum induction melting furnace for melting.

[0083] The specific melting process includes multiple steps such as vacuuming, filling, melting and cooling.

[0084] Step S11, vacuuming: the vacuum degree of the smelting equipment is evacuated to below 0.1 Pa, and further to below 0.01 Pa.

[0085] Step S12, filling: after the vacuum degree reaches the requirement, inert protective gas is filled into the smelting equipment to keep the air pressure of the smelting equipment within the range of -0.08 MPa to -0.02 MPa.

[0086] Step S13, melting and cooling: using a vacuum arc melting furnace, melting is performed at a current of 100A to 400A. During melting, the ingot is turned over multiple times, 4 to 10 times, and after cooling, a master alloy ingot with uniform composition is obtained.

[0087] As mentioned above, since the oxygen content of the alloy powder has an important influence on the quality of the alloy powder, it is crucial to determine whether the oxygen content can synthesize an ideal low-melting-point alloy powder during the synthesis of the alloy powder. Each step in the preparation of the alloy powder requires strict control of the oxygen content. Therefore, by performing the smelting in a vacuum state and under the protection of an inert gas through steps S11 and S12, the oxygen content in the furnace equipment can be effectively reduced, thereby reducing the loss of active components (such as active rare earth elements) in the raw materials after oxidation, which is beneficial to improving the accuracy of the ratio between the raw material components of the alloy powder, reducing the oxygen content of the alloy powder, and thus preparing an alloy powder with an ideal low melting point, while also being beneficial to improving the activity of the alloy powder.

[0088] In step S13, vacuum arc melting is used to effectively reduce the oxygen content in the alloy powder. During vacuum arc melting, the current level affects the furnace's output power, which in turn affects the melting of the alloy powder raw materials. If the current is too low, the raw materials will not melt sufficiently. If the current is too high, the molten raw materials will volatilize under the influence of the high current, resulting in raw material loss, reducing the accuracy of the composition ratio of the alloy powder components, and thus leading to uncertainty in the melting point of the final alloy powder. Therefore, by controlling the vacuum arc melting current within the range of 100A to 400A, the components of the alloy powder raw materials can be fully melted, while reducing the risk of raw material volatilization after melting, thereby improving the accuracy of the composition ratio between the raw materials and obtaining an ideal low-melting-point alloy powder.

[0089] In step S13, the ingot is turned over multiple times to facilitate sufficient mixing of the raw materials, so as to obtain a master alloy ingot with uniform composition.

[0090] In step S20, the master alloy ingot undergoes melt quenching. Specifically, the master alloy ingot is melted under vacuum and injected under pressure onto a high-speed rotating, water-cooled copper roller. The alloy melt solidifies at a very high undercooling rate, producing an alloy ribbon. Due to the extremely high cooling rate during melt quenching, a non-equilibrium microstructure with an ultrafine structure can be obtained, and the grain size can reach the nanometer level.

[0091] In some embodiments, the melt quenching is performed under an inert gas shield, wherein the inert gas is argon or helium, and the purity of the inert gas is greater than or equal to 99.99%, and further greater than or equal to 99.999%. During the melt quenching process, the copper roller rotates at a speed of 25 to 65 m / s. During the melt quenching process, the high-purity inert gas shield effectively reduces the oxygen content of the alloy powder. In addition, controlling the speed of the copper roller facilitates controlling the grain size formed during melt cooling, thereby obtaining ultrafine grains.

[0092] In some embodiments, the alloy flakes are actually very thin ribbons (also called alloy ribbons). The thickness of the alloy ribbons is 0.1 mm to 1 mm. By controlling the thickness of the alloy ribbons, it is advantageous to obtain alloy powders with a smaller average particle size.

[0093] In step S30 , the alloy strip may be crushed by at least one of ball milling, hydrogen explosion and air flow milling to obtain alloy powder with an average particle size less than or equal to 20 μm.

[0094] In some embodiments, the crushing method includes ball milling, and the ball milling time is 0.1h to 10h.

[0095] In some embodiments, the crushing method includes jet milling, which is performed under the protection of a protective gas such as nitrogen, argon, or helium, with a gas purity greater than or equal to 99.99%, further greater than or equal to 99.999%, a gas pressure of 0.2 MPa to 1.0 MPa, and a separation wheel speed of 1000 rpm to 8000 rpm. The use of a high-purity inert gas for protection during the jet milling process helps reduce the oxygen content in the alloy powder. In addition, by controlling the gas pressure and separation wheel speed, the crushing efficiency can be improved, while also facilitating the production of alloy powders with a small average particle size and uniform particle size.

[0096] In some embodiments, the alloy powder prepared by the above method and composition has a melting point less than or equal to 490° C. and an oxygen content less than or equal to 1 wt. %.

[0097] The alloy powder prepared by the smelting-melt rapid quenching-alloy sheet crushing process has a low melting point, high activity and a small average particle size; melt rapid quenching can make the melt of the master alloy ingot melted re-solidify at an extremely high degree of supercooling, which is conducive to the formation of ultrafine grains, and the alloy thin strips formed by melt rapid quenching are conducive to the subsequent alloy strips being crushed to form a powdered alloy with a smaller average particle size, so as to improve the dispersibility of the alloy powder in the magnetic particles. Therefore, the alloy powder prepared by the preparation method of the present application can be used as a spare alloy binder for permanent magnet production, which can effectively reduce the temperature of hot pressing and sintering in the permanent magnet preparation process, reduce the risk of high-temperature decomposition of magnetic particles, and thus help to improve the density and magnetic properties of the permanent magnet. In addition, the preparation method of the alloy powder is simple, and the equipment and instruments are vacuum arc furnaces or vacuum induction furnaces commonly used in the field of rare earth-based alloy preparation, which are easy to achieve mass production, and the production cost is low, with extremely high economic value.

[0098] See also Figures 2 to 4 Based on the same technical concept, the present invention also provides a method for preparing a permanent magnet 100, which comprises the following steps:

[0099] In step S40 , the alloy powder 10 and the magnetic particles 20 are mixed, oriented in a magnetic field, and formed to obtain an intermediate blank 30 . The alloy powder 10 is the aforementioned alloy powder.

[0100] In some embodiments, the magnetic particles 20 are samarium iron nitrogen magnetic particles, and the alloy powder 10 and the magnetic particles 20 are mixed by mechanical mixing, sputtering, and deposition. The uniformly mixed powder is then subjected to magnetic field orientation pressing and cold isostatic pressing to form an intermediate billet 30, depending on the shape of the samarium iron nitrogen magnet to be prepared. Because magnetic particles are easily oxidized, the particle size of the magnetic particles is selected to be appropriately larger to reduce the oxygen content of the magnetic particles. Furthermore, during the mixing process of the magnetic particles 20 and the alloy powder 10, the risk of oxidation of the magnetic particles 20 and the alloy powder 10 can be reduced by vacuuming, using inert gas protection, and the like.

[0101] In step S50, the intermediate blank 30 is hot-pressed and sintered to melt and solidify the alloy powder 10 into a matrix 40 located around the magnetic particles 20, and an intermediate phase 50 is formed between the magnetic particles 20 and the matrix 40 to obtain a permanent magnet 100, wherein the intermediate phase 50 contains at least part of the elements of the magnetic particles 20 and at least part of the elements of the matrix 40.

[0102] During the hot pressing and sintering process, an oxide layer is formed on the surface of the samarium iron nitrogen magnetic particles 20. The melt of the alloy powder 10 diffuses and penetrates into the oxide layer and absorbs oxygen in the oxide layer, thereby forming an intermediate phase 50 mainly composed of at least part of the elements of the magnetic particles 20 and at least part of the elements of the matrix 40, wherein the intermediate phase 50 is an intermetallic compound.

[0103] In some embodiments, the hot pressing sintering temperature does not exceed 500° C., which is specifically designed based on the melting point of the alloy powder 10. The hot pressing sintering temperature does not exceed 500° C., which is much lower than the decomposition temperature of the SmFeN magnetic particles 20 (approximately 600° C.), thereby reducing the risk of decomposition of the SmFeN magnetic particles 20 during the hot pressing sintering process.

[0104] In some embodiments, the hot pressing sintering is carried out at a pressure of about 500 MPa for 3 to 10 minutes.

[0105] It is understandable that the aforementioned alloy powder can also be used as a binder for preparing other samarium-containing or non-samarium-containing permanent magnets.

[0106] The permanent magnet 100 is prepared by mixing the aforementioned alloy powder 10 as a binder with the samarium iron nitrogen magnetic particles 20. Since the aforementioned alloy powder 10 contains samarium, which is similarly compatible with the samarium iron nitrogen magnetic particles 20, it is beneficial to improve the interface wettability of the alloy melt after the alloy powder 10 is melted to the samarium iron nitrogen magnetic particles 20, thereby improving the interface compatibility between the alloy melt and the samarium iron nitrogen magnetic particles 20, so that the melt of the alloy powder 10 after melting is evenly distributed on the surface of the samarium iron nitrogen magnetic particles 20, and the small-sized alloy powder 10 can also fully fill the gaps between the samarium iron nitrogen magnetic particles 20 to improve the density of the permanent magnet 100, such as Figure 3 As shown. Moreover, the low melting point of the alloy powder 10 is conducive to lowering the temperature of hot pressing and sintering, thereby reducing the risk of decomposition of the SmFeN magnetic particles 20 during the hot pressing and sintering process. In addition, the low hot pressing and sintering temperature is conducive to ensuring the high activity of the alloy powder 10 during the hot pressing process, so that the melt of the alloy powder 10 is coated on the surface of the SmFeN magnetic particles 20, thereby fully absorbing the oxygen in the oxide layer on the surface of the SmFeN magnetic particles 20 and repairing the surface defects of the SmFeN magnetic particles 20, thereby improving the magnetic properties and magnetic performance of the permanent magnet 100.

[0107] like Figure 4 As shown, refer to Figure 3 The permanent magnet 100 prepared by the above-mentioned alloy powder as an alloy binder and the above-mentioned method for preparing the permanent magnet 100 includes magnetic particles 20, a matrix 40, and an intermediate phase 50 located between the magnetic particles 20 and the matrix 40. The matrix 40 is formed by melting and solidifying the above-mentioned alloy powder 10 and has the same composition as the above-mentioned alloy powder 10. Due to thermal diffusion at the contact interface between the alloy powder 10 and the magnetic particles 20, a chemical reaction occurs between the diffused elements to form the intermediate phase 50 (i.e., an intermetallic compound). It can be understood that the diffused elements can be part of the elements in the magnetic particles 20 and the alloy powder 10, or can be all of the elements. Therefore, the intermediate phase 50 contains at least part of the elements of the magnetic particles 20 and at least part of the elements of the matrix 40.

[0108] When the magnetic particles 20 contain Sm, Fe and N, the permanent magnet 100 has a higher density and magnetic properties. The density of the permanent magnet 100 is greater than or equal to 6.6 g / cm 3 , remanence (Br) greater than or equal to 8.5kGs, intrinsic coercive force (Hcj) greater than or equal to 12kOe, and maximum magnetic energy product (HBmax) greater than or equal to 15MGOe.

[0109] See also Figure 5Based on the same technical concept, an embodiment of the present application further provides a device 200, which includes a receiving component 210 and the aforementioned permanent magnet 100 received in the receiving component 210. The device 200 can be a drive motor in a new energy vehicle, an electromagnetic coil in a speaker, a hard disk drive, a magnetic drive pump, and the like. For example, when the device 200 is a drive electrode, the receiving component 210 can be a rotor having a magnet mounting groove formed thereon, and the permanent magnet 100 is received in the magnet mounting groove.

[0110] The technical solutions of the embodiments of the present application are further described below through specific examples.

[0111] Example 1

[0112] The alloy compositions expressed in atomic percentages in this example are: (Ce 0.8 Sm 0.2 ) 72 Cu 28 、(Ce 0.8 Sm 0.2 ) 72 Cu 25 Al3、(Ce 0.8 Sm 0.2 ) 72 Cu 22 Al6、(Ce 0.8 Sm 0.2 ) 72 Cu 19 Al9 and (Ce 0.8 Sm 0.2 ) 72 Cu 16 Al 12 First, the raw materials are configured according to the above components, and high-purity Ce, high-purity Sm, high-purity Cu and high-purity Al with a purity of more than 99.99wt% are selected as raw materials. After the raw materials are weighed, they are placed in a melting furnace for melting. The melting process includes multiple steps such as vacuuming, filling with inert protective gas, and alloy melting. The vacuum degree of the equipment is pumped to 10 -3 After the pressure drops below Pa, high-purity Ar at a pressure of -0.08MPa is filled into the smelting equipment, and then the alloy is smelted at a current of 200A. The ingot is turned over and smelted 5 times to ensure uniform composition. After the smelting is completed, the master alloy ingot is taken out after cooling. The prepared master alloy ingot is prepared into an alloy rapid solidification thin strip by melt rapid quenching in a rapid quenching furnace. The roller speed is 45m / s to obtain an alloy strip with a thickness of 0.1mm to 1mm. Subsequently, the alloy strip is further crushed by ball milling. The speed of ball milling is 800rpm and the ball milling time is 0.5h. After ball milling, a (Ce, Sm)-Cu-Al low melting point alloy powder with a particle size of ≤10μm is obtained.

[0113] like Figure 6 As shown in Figures (a) and (b), they are (Ce 0.8 Sm 0.2 ) 72 Cu 28 Photos of master alloy ingots and alloy strips, such as Figure 6 As shown in Figure (c), (Ce 0.8 Sm 0.2 ) 72 Cu 28 SEM photo of alloy powder. Figure 6 As can be seen from Figure (c), the average particle size of the alloy powder is small.

[0114] The above (Ce 0.8 Sm 0.2 ) 72 Cu 28-x Al x The melting points of the (Ce, Sm)-Cu-Al alloy powders (x=0-12) were tested, and the melting points of the obtained alloy powders are shown in Table 1. From the data in Table 1, it can be seen that the melting point of the prepared (Ce, Sm)-Cu-Al alloy powder can reach as low as 382.5°C.

[0115] Table 1

[0116] Alloy powder type Melting point (℃) 1 <![CDATA[(Ce 0.8 Sm 0.2 ) 72 With 28 ]]> 421.3 2 <h2 style=";text-align:left;direction:ltr"><![CDATA[(Ce <h2 style=";text-align:left;direction:ltr"> 0.8 <h2 style=";text-align:left;direction:ltr"> Sm<h2 style=";text-align:left;direction:ltr"> 0.2 <h2 style=";text-align:left;direction:ltr"> )<h2 style=";text-align:left;direction:ltr"> 72 <h2 style=";text-align:left;direction:ltr"> Cu<h2 style=";text-align:left;direction:ltr"> 25 <h2 style=";text-align:left;direction:ltr"> Al3]]><h2 style=";text-align:left;direction:ltr"> 382.5 3 <![CDATA[(Ce 0.8 Sm 0.2 ) 72 With 22 Al6]]> 384.4 4 <![CDATA[(Ce 0.8 Sm 0.2 ) 72 With 19 Al9]]> 386.3 5 <![CDATA[(Ce 0.8 Sm 0.2 ) 72 With 16 the 12 ]]> 385.5

[0117] Example 2

[0118] The alloy compositions expressed in atomic percentages in this example are: (Ce 0.8 Sm 0.2 ) 72 Cu 25 Ga3、(Ce 0.8 Sm 0.2 ) 72 Cu 22 Ga6、(Ce 0.8 Sm 0.2 ) 72 Cu 19 Ga9、(Ce 0.8 Sm 0.2 ) 72 Cu 16 Ga 12 First, the raw materials are prepared according to the above components, and high-purity Ce, high-purity Sm, high-purity Cu and high-purity Ga with a purity of more than 99.99wt% are selected as raw materials. After the preparation is completed, they are placed in the melting furnace for melting. The melting process includes vacuuming, filling with inert protective gas, alloy melting and other steps. The vacuum degree of the equipment is pumped to 10 -3After the pressure drops below Pa, high-purity Ar at a pressure of -0.08MPa is filled into the smelting equipment, and then the alloy is smelted at a current of 180A. The ingot is turned over 6 times for smelting to ensure uniform composition. After the smelting is completed, the master alloy ingot is taken out after cooling. The prepared master alloy ingot is prepared into an alloy rapid solidification thin strip by melt rapid quenching in a rapid quenching furnace. The roller speed is 35m / s to obtain an alloy strip with a thickness of 0.1mm to 1mm. Subsequently, the alloy strip is further crushed by ball milling. The speed of ball milling is 800rpm and the ball milling time is 0.5h. After ball milling, a (Ce, Sm)-Cu-Ga low melting point alloy powder with a particle size of ≤15μm is obtained.

[0119] The (Ce 0.8 Sm 0.2 ) 72 Cu 28-x Ga x The melting points of the (Ce, Sm)-Cu-Ga alloy powders were tested, and the melting points of the obtained alloy powders are shown in Table 1. As shown in Table 2, the melting point of the prepared (Ce, Sm)-Cu-Ga alloy powder can reach as low as 379.6°C.

[0120] Table 2

[0121] Alloy powder type Melting point (℃) 1 <![CDATA[(Ce 0.8 Sm 0.2 ) 72 With 25 Ga3]]> 402.1 2 <![CDATA[(Ce 0.8 Sm 0.2 ) 72 With 22 Ga6]]> 384.7 3 <![CDATA[(Ce 0.8 Sm 0.2 ) 72 With 19 Ga9]]> 381.7 4 <![CDATA[(Ce 0.8 Sm 0.2 ) 72 With 16 Ga 12 ]]> 379.6

[0122] Example 3

[0123] The alloy compositions expressed in atomic percentages in this example are: (Ce 0.7 Sm 0.3 ) 76 Co 24 、(Ce 0.7 Sm 0.3 ) 76 Co 21 Al3、(Ce 0.7 Sm 0.3 ) 76 Co 18 Al6、(Ce 0.7 Sm 0.3 ) 76 Co 15 Al9、(Ce 0.7 Sm 0.3 ) 76 Co 12 Al 12First, the raw materials are prepared according to the above components, and high-purity Ce, high-purity Sm, high-purity Co and high-purity Al with a purity of more than 99.99wt% are selected as raw materials. After the preparation is completed, they are placed in the melting furnace for melting. The melting process includes vacuuming, filling with inert protective gas, alloy melting and other steps. The vacuum degree of the equipment is pumped to 10 -3 After the pressure drops below Pa, high-purity Ar at a pressure of -0.08MPa is filled into the smelting equipment, and then the alloy is smelted at a current of 200A. The ingot is turned over 6 times for smelting to ensure uniform composition. After the smelting is completed, the master alloy ingot is taken out after cooling. The prepared master alloy ingot is prepared into an alloy rapid solidification thin strip by melt rapid quenching in a rapid quenching furnace. The roller speed is 45m / s to obtain an alloy strip with a thickness of 0.1mm to 1mm. The alloy strip is then further crushed by ball milling. The speed of ball milling is 800rpm and the ball milling time is 0.5h. After ball milling, a (Ce, Sm)-Co-Al low melting point alloy powder with a particle size of ≤10μm is obtained.

[0124] The (Ce 0.7 Sm 0.3 ) 76 Co 24-x Al x The melting points of the (Ce, Sm)-Co-Al alloy powders (x = 0 to 12) were tested, and the melting points of the obtained alloy powders are shown in Table 3. From the data in Table 3, it can be seen that the melting point of the prepared (Ce, Sm)-Co-Al alloy powder can reach as low as 410.3°C.

[0125] Table 3

[0126] Alloy powder type Melting point (℃) 1 <![CDATA[(Ce 0.7 Sm 0.3 ) 76 What 24 ]]> 427.6 2 <h2 style=";text-align:left;direction:ltr"><![CDATA[(Ce <h2 style=";text-align:left;direction:ltr"> 0.7 <h2 style=";text-align:left;direction:ltr"> Sm<h2 style=";text-align:left;direction:ltr"> 0.3 <h2 style=";text-align:left;direction:ltr"> )<h2 style=";text-align:left;direction:ltr"> 76 <h2 style=";text-align:left;direction:ltr"> Co<h2 style=";text-align:left;direction:ltr"> 21 <h2 style=";text-align:left;direction:ltr"> Al3]]><h2 style=";text-align:left;direction:ltr"> 411.2 3 <![CDATA[(Ce 0.7 Sm 0.3 ) 76 What 18 Al6]]> 411.0 4 <![CDATA[(Ce 0.7 Sm 0.3 ) 76 What 15 Al9]]> 410.3 5 <![CDATA[(Ce 0.7 Sm 0.3 ) 76 What 12 Al 12 ]]> 417.2

[0127] Example 4

[0128] The alloy components expressed in atomic percentage in this example are (Pr 0.7 Sm 0.3 ) 68 Cu 32 、(Pr 0.7 Sm 0.3 ) 68 Cu 29 Al3、(Pr 0.7 Sm 0.3 ) 68 Cu 26 Al6、(Pr 0.7 Sm 0.3 ) 68 Cu 23 Al9、(Pr 0.7 Sm 0.3 ) 68 Cu20 Al 12 First, the raw materials are prepared according to the above components, and high-purity Pr, high-purity Sm, high-purity Cu and high-purity Al with a purity of more than 99.99wt% are selected as raw materials. After the preparation is completed, they are placed in the melting furnace for melting. The melting process includes vacuuming, filling with inert protective gas, alloy melting and other steps. The vacuum degree of the equipment is pumped to 10 -3 After the pressure drops below Pa, high-purity Ar at a pressure of -0.08MPa is filled into the smelting equipment, and then the alloy is smelted at a current of 220A. The ingot is turned over 5 times for smelting to ensure uniform composition. After the smelting is completed, the master alloy ingot is taken out after cooling. The prepared master alloy ingot is prepared into an alloy rapid solidification thin strip by melt rapid quenching in a rapid quenching furnace. The roller speed is 35m / s to obtain an alloy strip with a thickness of 0.1mm to 1mm. The alloy strip is then further crushed by ball milling. The speed of ball milling is 800rpm and the ball milling time is 0.5h. After ball milling, a (Pr, Sm)-Cu-Al low melting point alloy powder with a particle size of ≤15μm is obtained.

[0129] The (Pr 0.7 Sm 0.3 ) 68 Cu 32-x Al x The melting points of the (Pr, Sm)-Cu-Al alloy powders (x=0-12) were tested, and the melting points of the obtained alloy powders are shown in Table 4. From the data in Table 4, it can be seen that the melting point of the experimentally prepared (Pr, Sm)-Cu-Al alloy can reach as low as 426.9°C.

[0130] Table 4

[0131] Alloy powder type Melting point (℃) 1 <![CDATA[(Pr 0.7 Sm 0.3 ) 68 With 32 ]]> 472.1 2 <h2 style=";text-align:left;direction:ltr"><![CDATA[(Pr <h2 style=";text-align:left;direction:ltr"> 0.7 <h2 style=";text-align:left;direction:ltr"> Sm<h2 style=";text-align:left;direction:ltr"> 0.3 <h2 style=";text-align:left;direction:ltr"> )<h2 style=";text-align:left;direction:ltr"> 68 <h2 style=";text-align:left;direction:ltr"> Cu<h2 style=";text-align:left;direction:ltr"> 29 <h2 style=";text-align:left;direction:ltr"> Al3]]><h2 style=";text-align:left;direction:ltr"> 426.9 3 <![CDATA[(Pr 0.7 Sm 0.3 ) 68 With 26 Al6]]> 427.2 4 <![CDATA[(Pr 0.7 Sm 0.3 ) 68 With 23 Al9]]> 429.6 5 <![CDATA[(Pr 0.7 Sm 0.3 ) 68 With 20 the 12 ]]> 426.9

[0132] Samarium Iron Nitride Magnet Example

[0133] In this embodiment, the obtained low-melting-point alloy powder is mixed with Sm-Fe-N magnetic particles and then a hot pressing sintering process is used to prepare an alloy-bonded high-performance samarium iron nitride sintered magnet. The specific method is as follows: the (Ce, Sm)-Cu-Ga rare earth alloy powder prepared in Example 2 is mixed with Sm-Fe-N magnetic particles, and then the intermediate blank is obtained by magnetic field orientation pressing and cold isostatic pressing. The intermediate blank is then hot pressed and sintered at 450°C and 500MPa for 5 minutes. After demolding, a samarium iron nitride magnet bonded with a rare earth-based low-melting-point alloy is obtained. Since the alloy powder binder used has a relatively low melting point, the samarium iron nitride magnet can be formed at a low temperature of 450°C. The types of alloy powders used in this embodiment and the specific properties of the obtained samarium iron nitride magnets are detailed in Table 5.

[0134] Table 5

[0135]

[0136] The SmFeN magnets prepared in this example used the alloy powders prepared in Example 2 as a binder. The four alloy powders prepared in Example 2 have low melting points, which reduces the hot-pressing sintering temperature of the SmFeN magnets to 450°C. Table 5 shows that the addition of the (Ce, Sm)-Cu-Ga alloy powder significantly improves the density and magnetic properties of the prepared SmFeN magnets.

[0137] It should be noted that the above are only specific embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application; the embodiments of the present application and the features of the embodiments can be combined with each other unless there is a conflict. Therefore, the scope of protection of the present application shall be based on the scope of protection of the claims.

Claims

1. An alloy powder, characterized in that: The alloy powder is an alloy binder for preparing samarium iron nitrogen magnets. The composition of the alloy powder expressed in atomic percentage is: (Re 1-a Sm a ) x M y N 100-x-y , wherein Re is selected from at least one of La, Ce, Pr, Nd and Y, M is selected from at least one of Cu, Co, Fe and Zr, N is selected from at least one of Al, Ag, Bi, Ga and Sn, the value range of x is 50~75, the value range of y is 15~35, the value range of a is 0.1~1.0, and the melting point of the alloy powder is less than or equal to 490°C.

2. The alloy powder according to claim 1, wherein The average particle size of the alloy powder is less than or equal to 20 μm.

3. The alloy powder according to claim 1 or 2, characterized in that The oxygen content of the alloy powder is less than or equal to 1 wt.%.

4. A method for preparing alloy powder, characterized in that: The following steps are involved: The raw materials of the alloy powder are melted and cooled to obtain a master alloy ingot; Rapidly quenching the master alloy ingot to obtain alloy flakes; and Crushing the alloy flakes to obtain the alloy powder, The alloy powder is an alloy binder for preparing samarium iron nitrogen magnets, and the composition of the alloy powder expressed in atomic percentage is: (Re 1-a Sm a ) x M y N 100-x-y , wherein Re is selected from at least one of La, Ce, Pr, Nd and Y, M is selected from at least one of Cu, Co, Fe and Zr, N is selected from at least one of Al, Ag, Bi, Ga and Sn, the value range of x is 50~75; the value range of y is 15~35, the value range of a is 0.1~1.0, and the melting point of the alloy powder is less than or equal to 490℃.

5. The method for preparing alloy powder according to claim 4, characterized in that: Before the step of smelting the raw materials of the alloy powder, the preparation method further comprises the steps of: The raw materials of the alloy powder are batched, The error between the measured mass and the theoretical mass of each component in the raw materials during batching is 0.5% to 10%.

6. The method for preparing the alloy powder according to claim 4 or 5, wherein: The smelting is vacuum arc melting, and the current of the smelting is 100 A to 400 A.

7. The method for preparing alloy powder according to claim 4, characterized in that: The step of smelting the alloy powder raw materials and obtaining the master alloy ingot after cooling specifically comprises the following steps: evacuating the smelting equipment containing the raw materials; Filling the vacuumed melting equipment with inert gas; Melting the raw materials to obtain hot ingots; and The hot cast ingot is cooled to obtain the master alloy cast ingot.

8. The method for preparing alloy powder according to claim 7, wherein: The vacuum degree of the smelting equipment is less than or equal to 0.1 Pa; The gas pressure of the inert gas is in the range of -0.08 MPa to -0.02 MPa.

9. The method for preparing alloy powder according to claim 7 or 8, characterized in that: The thickness of the alloy sheet is 0.1 mm to 1 mm.

10. The method for preparing alloy powder according to claim 4, wherein: During the rapid quenching of the melt, the rotational speed of the roller is 25-65 m / s.

11. The method for preparing alloy powder according to claim 4, wherein: The rapid quenching of the melt is carried out under the protection of an inert gas, wherein the inert gas is argon or helium, and the purity of the inert gas is greater than or equal to 99.99%.

12. The method for preparing alloy powder according to claim 4, characterized in that: The crushing method includes at least one of ball milling, hydrogen explosion and air flow milling.

13. A permanent magnet, characterized in that: include: Magnetic particles, wherein the magnetic particles are samarium iron nitrogen magnets; The matrix is ​​located around the magnetic particles, and the composition of the matrix expressed in atomic percentage is: (Re 1- a Sm a ) x M y N 100-x-y , wherein Re is selected from at least one of La, Ce, Pr, Nd and Y, M is selected from at least one of Cu, Co, Fe and Zr, N is selected from at least one of Al, Ag, Bi, Ga and Sn, x is in the range of 50 to 75, y is in the range of 15 to 35, a is in the range of 0.1 to 1.0, and the melting point of the matrix is ​​less than or equal to 490°C; and An intermediate phase is located between the magnetic particles and the matrix, and contains at least part of the elements of the magnetic particles and at least part of the elements of the matrix.

14. The permanent magnet according to claim 13, characterized in that The magnetic particles contain Sm, Fe, and N.

15. The permanent magnet according to claim 14, wherein The density of the permanent magnet is greater than or equal to 6.6 g / cm 3 , remanence (Br) greater than or equal to 8.5kGs, intrinsic coercive force (Hcj) greater than or equal to 12kOe, and maximum magnetic energy product (HBmax) greater than or equal to 15 MGOe.

16. A method for preparing a permanent magnet, characterized in that: The following steps are involved: Mixing alloy powder with magnetic particles, orienting in a magnetic field, and forming the mixture to obtain an intermediate billet, wherein the alloy powder is the alloy powder according to any one of claims 1 to 3 or the alloy powder prepared by the method for preparing the alloy powder according to any one of claims 4 to 12; and The intermediate blank is hot pressed and sintered, so that the alloy powder is melted and solidified into a matrix located around the magnetic particles, and an intermediate phase is formed between the magnetic particles and the matrix to obtain a permanent magnet, wherein the intermediate phase contains at least part of the elements of the magnetic particles and at least part of the elements of the matrix.

17. The method for preparing a permanent magnet according to claim 16, wherein: The temperature of the hot pressing sintering does not exceed 500°C.

18. A device, characterized in that It comprises an accommodating component and a permanent magnet accommodated in the accommodating component, wherein the permanent magnet is the permanent magnet according to any one of claims 13 to 15 or a permanent magnet prepared by the method for preparing a permanent magnet according to claim 16 or 17.

19. The device according to claim 18, characterized in that The device is a motor, and the accommodating component is a rotor.

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