Sintered neodymium-cerium-iron-boron magnet with high comprehensive magnetic performance and preparation method of sintered neodymium-cerium-iron-boron magnet

Abstract

The invention discloses a sintered neodymium-cerium-iron-boron magnet with high comprehensive magnetic performance, which is prepared by uniformly mixing and pressing alloy powder with a chemical formula of (Nd1-xCex) aM100-a-b-cFebBc and one or more kinds of X-B alloy powder and carrying out sintering and tempering treatment, a is more than or equal to 28 and less than or equal to 33, b is more than or equal to 58 and less than or equal to 69, c is more than or equal to 0.8 and less than or equal to 1.1, x is more than 0 and less than or equal to 20, and b is more than or equal to 1 and less than or equal to 3. M is one or more of Zn, Ga, Co, Cu, Nb, Si, Mn and Al, and X is one or more of Ti, Hf, Zr, Cr and Mo. The preparation method comprises the steps of raw material proportioning, rapid hardening melt-spinning, hydrogen crushing, airflow grinding powder preparation, mixed powder compression, sintering and tempering heat treatment. The X-B compound is introduced, a multi-stage induction system is constructed in the magnet, directional migration and enrichment of Ce elements in a grain boundary area are effectively regulated and controlled, an excellent magnetic microstructure with a Ce-rich grain boundary phase and a main phase mainly comprising Nd2Fe14B is formed, a grain boundary engineering strategy without additional heavy rare earth element compensation is provided, and the preparation method has the advantages of being simple in process, low in cost and easy to popularize. And efficient utilization of high-abundance rare earth resources and comprehensive improvement of performance are achieved, and good technical advancement and industrial application prospects are achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rare earth permanent magnet materials, and particularly relates to a sintered neodymium-cerium-iron-boron magnet with high comprehensive magnetic properties and a preparation method thereof. BACKGROUND

[0002] Neodymium-iron-boron-based magnets are widely used in new energy motors, wind power equipment, aerospace and other high-tech fields due to their excellent magnetic properties, and the market demand continues to grow. At the same time, after years of rapid development, the production and application have consumed a large amount of praseodymium and neodymium rare earth resources, leading to an increasingly prominent contradiction between supply and demand of resources. Therefore, the abundant rare earth element Ce in the earth's crust has become an ideal alternative element to achieve resource balance and reduce costs. In recent years, in order to reduce costs and reduce dependence on heavy rare earth resources, researchers have attempted to replace Nd with high-abundance rare earth element Ce.

[0003] However, due to the low intrinsic performance of Ce2Fe 14 B is lower than that of Nd2Fe 14 B, and Ce has a strong tendency to dissolve, it is easy to enter the main phase lattice, which will produce a significant magnetic dilution effect, cause the magnetic anisotropy field to decrease, and lead to a decrease in magnetic properties, which restricts its actual application. Therefore, how to fully utilize the advantages of Ce resources while suppressing its adverse effects on magnetic properties has become a key problem in the current research of neodymium-iron-boron-based magnets. Therefore, an effective strategy is to guide the preferential enrichment of Ce elements in the grain boundary region, thereby forming a microstructure of "Ce-rich grain boundary phase + Nd-rich main phase". However, there is still a lack of systematic and effective methods for inducing directional enrichment of Ce elements, especially a multi-level regulation strategy for Ce has not been reported. SUMMARY

[0004] The purpose of the present application is to provide a sintered neodymium-cerium-iron-boron magnet with high comprehensive magnetic properties, and a preparation method. The present application introduces a nano or sub-micron X-B high melting point alloy to form a multi-level induced structure, which is not easy to react and stably exists at the grain boundary, and realizes the directional aggregation of Ce elements around it, thereby effectively inhibiting the entry of Ce into the main phase lattice and improving the overall magnetic properties and thermal stability of the magnet.

[0005] The sintered neodymium-cerium-iron-boron magnet with high comprehensive magnetic properties of the present application is characterized in that: the high comprehensive performance magnet is prepared by respectively using (Nd 1-x Ce x ) a M 100-a-b-c Fe b B cA sintered neodymium-cerium-iron-boron single main phase alloy magnet is prepared by uniformly mixing single main phase alloy powder with one or more X-B alloy powders, pressing and sintering and tempering, wherein 28≤a≤33, 58≤b≤69, 0.8≤c≤1.1, 0<x≤20, M is one or more of Zn, Ga, Co, Cu, Nb, Si, Mn and Al, and X is one or more of Ti, Hf, Zr, Cr and Mo.

[0006] In the present application, the X-B alloy powder has the characteristics of non-magnetic, high melting point and high stability, which ensures that it does not react during heat treatment and forms a stable precipitated phase at the grain boundary, realizes the "site adsorption" and "diffusion directional guidance" effect of the Ce element, and makes the Ce element preferentially enriched in the grain boundary area to form a microstructure of "Ce-rich grain boundary phase + Nd-rich main phase".

[0007] Preferably, the mass ratio of the single main phase alloy powder to the X-B alloy powder is 1:0.001-0.008.

[0008] Preferably, the atomic ratio of the elements of the X-B alloy is XB2.

[0009] Preferably, the X-B alloy elements use two different elements to take advantage of their synergistic effect.

[0010] The present application also provides a preparation method of the aforementioned sintered neodymium-cerium-iron-boron magnet with high comprehensive magnetic properties, comprising the following steps: (1) Raw material proportioning: preparing (Nd 1-x Ce x ) a M 100-a-b-c Fe b B c alloy raw materials according to the composition design; (2) Rapid solidification ribbon drawing: preparing alloy rapid solidification ribbons from the raw materials proportioned according to the composition design by melting and rapid solidification ribbon drawing; (3) Hydrogen breaking: preparing alloy hydrogen broken powder after hydrogen absorption and dehydrogenation stages; (4) Jet mill powdering: grinding the prepared alloy hydrogen broken powder to micron-sized alloy powder by accelerating mutual collision; (5) Powder mixing and molding: controlling the particle size of the high melting point X-B alloy powder to be 30-300 nm, adding 0.001-0.008% by mass, then uniformly mixing the prepared jet mill alloy powder and high melting point X-B alloy powder in an inert gas environment for 20-30 min and orienting and pressing into shape, then performing cold isostatic pressing treatment by wrapping with a multi-layer sealing bag, and applying a pressure of 100-200 MPa for 0.01-10 min; (6) heat treatment: sintering and tempering treatment are carried out on the compacted block to prepare a sintered magnet.

[0011] Preferably, the purity of the raw material in step (1) is required to reach 99.5% or above.

[0012] Preferably, the method for preparing the alloy rapid solidification piece in step (2) is as follows: the rapid solidification furnace is kept in vacuum condition, argon is introduced after the material is heated, the temperature of the crucible is refined to 1200-1600 DEG C by medium frequency current, the molten alloy liquid is poured into a tundish, and then is guided to a copper roller to be cooled in a collection tray to prepare the rapid solidification piece, the rotating speed of the copper roller is designed to be 1.1-1.5 m / s, the thickness of the rapid solidification piece is 0.2-0.4 mm, and the temperature of the cooling water of the copper roller is 18-26 DEG C.

[0013] Preferably, the two stages of hydrogen absorption and hydrogen desorption in step (3) are as follows: the hydrogen breaking furnace needs to be kept in oxygen-free environment, hydrogen absorption is carried out at room temperature for 1-2 h under a hydrogen pressure of 0.6-0.9 MPa, and hydrogen desorption is carried out for 2-4 h after heating to 450-500 DEG C.

[0014] Preferably, in the airflow milling process in step (4), the equipment is strictly required to keep the oxygen content of 10-15 ppm, and the rotating speed of the sorting wheel is set to be 4200-4600 r / min.

[0015] Preferably, the sintering in step (6) is that the compacted block is loaded into a graphite box, and then is put into a tube type sintering furnace to be sintered under the condition of 1x10 -3 Pa vacuum.

[0016] The present application forms a multi-stage induced structure by introducing nano-scale or sub-micron X-B alloy, which is not easy to react and stably exists at the grain boundary, and realizes directional aggregation of Ce elements around it, so as to effectively inhibit Ce from entering the main phase lattice, and improve the magnetic performance and thermal stability of the whole magnet. The induction mechanism is derived from the unique crystal potential field of the XB2 phase surface, which has good matching with the radius and electronegativity of Ce atoms, and further combines the electronic coupling effect between the transition metal d orbit and the 4f orbit of Ce. Further, the characteristic differences of different XB2 alloys can be used to form layered induction sites at the grain boundary and the deep layer of the grain boundary respectively, and enhance the aggregation trend of Ce in the grain boundary area, so as to construct a microstructure of "Ce-rich grain boundary phase + Nd-rich main phase".

[0017] Therefore, the present application has the following beneficial effects: (1) The high-abundance rare earth element Ce is used to partially replace Nd, which reduces the manufacturing cost of the magnet, and helps to alleviate the long-term overstock problem of high-abundance rare earth resources, and realizes balanced utilization of rare earth resources.

[0018] (2) XB2 phase preferentially precipitates in the grain boundary region and builds a multi-stage induction structure, guiding the directional enrichment of Ce elements in the grain boundary region, avoiding its interference with the magnetic anisotropy field of the B main phase, and inhibiting the growth of abnormal grains, realizing the improvement of magnetic performance and thermal stability. At the same time, it effectively enhances the distribution control ability of rare earth elements and improves the efficient utilization efficiency of Ce resources, which has significant technical advantages and promotion value in the development of high-performance magnets. 14 B main phase magnetic anisotropy field, and inhibits the growth of abnormal grains, realizes the improvement of magnetic performance and thermal stability. At the same time, it effectively enhances the distribution control ability of rare earth elements and improves the efficient utilization efficiency of Ce resources, which has significant technical advantages and promotion value in the development of high-performance magnets. DETAILED DESCRIPTION

[0019] Further detailed description will be made below in combination with specific embodiments, and the examples given are only for illustrating the present application, not for limiting the scope of the present application.

[0020] Example 1 Preparation of original magnet (1) The ingredients are prepared according to the mass percentage of (Nd 83 Ce 17 ) 29.5 Fe bal Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 0.9 single main phase alloy. Note: subscript "bal" is the abbreviation of "balance", which means remaining, indicating that in addition to other chemical elements, the content of Fe is left.

[0021] (2) The prepared raw materials are placed in the rapid solidification furnace in a certain order, and then vacuumed to 5×10 ‑3 Pa, then the equipment power is increased to 7 kW for drying treatment, then argon is filled, and the equipment power is slowly increased to make the melting temperature reach 1500 ℃ for 3 min of refining, then the alloy liquid is poured into the tundish and guided to the copper roller, and then it is spun to the collection tray for cooling to prepare the rapid solidification sheet, the copper roller speed is designed to be 1.3 m / s, the copper roller cooling water temperature is 22 ℃, and the prepared rapid solidification sheet thickness is 0.26 mm.

[0022] (3) The rapid solidification sheet is placed in a hydrogen breaking furnace for hydrogen breaking treatment, and the hydrogen breaking furnace vacuum degree is maintained at 1×10 ‑ 3 Pa, hydrogen absorption at room temperature for 1 h under 0.8 MPa hydrogen pressure, and dehydrogenation at 500 ℃ for 3 h, and after the hydrogen absorption and dehydrogenation two stages, the hydrogen broken powder is prepared.

[0023] (4) The hydrogen broken powder is poured into the jet mill tank under argon atmosphere, and the alloy powder with a particle size of 2.6 μm is prepared under the conditions of oxygen content of 10 ppm and sorting wheel speed of 4500 r / min through the jet mill equipment.

[0024] (5) The prepared airflow mill powder was weighed according to the size of the mold, 100 g was pressed into a 26x26x27 mm block under the protection of high-purity nitrogen, and then isostatic pressing was carried out, the pressure was applied to 200 MPa, and the pressure holding time was 5 min.

[0025] (6) The block was loaded into a graphite box and placed into a tube sintering furnace, vacuumized to 1x10 -3 Pa, and a (Nd 83 Ce 17 ) 29.5 Fe bal Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 0.9 magnet was prepared through a heat treatment process.

[0026] Example 2 (1) The components of (Nd 83 Ce 17 ) 29.5 Fe bal Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 0.9 single main phase alloy were prepared according to the mass percentage.

[0027] (2) The prepared raw materials were placed in the rapid solidification furnace in a certain order, then vacuumized to 5x10 ‑3 Pa, the power of the equipment was increased to 7 kW for baking treatment, then argon was filled, the power of the equipment was slowly increased to make the melting temperature reach 1500 ℃, and the alloy liquid was poured into the tundish and guided to the copper roller to be spun onto the collection tray to cool and prepare into a rapid solidification sheet, the copper roller speed was designed to be 1.3 m / s, the temperature of the copper roller cooling water was 22 ℃, and the prepared rapid solidification sheet had a thickness of 0.26 mm.

[0028] (3) The rapid solidification sheet was placed into a hydrogen breaking furnace for hydrogen breaking treatment, the vacuum degree of the hydrogen breaking furnace was maintained at 1x10 ‑ 3 Pa, hydrogen was absorbed at room temperature for 1 h under a hydrogen pressure of 0.8 MPa, and dehydrogenation was carried out at 500 ℃ for 3 h, and the hydrogen broken powder was prepared after the two stages of hydrogen absorption and dehydrogenation.

[0029] (4) The hydrogen broken powder was poured into a jet mill tank under an argon environment, and the alloy powder with a particle size of 2.6 μm was prepared through a jet mill device under the conditions of an oxygen content of 10 ppm and a sorting wheel speed of 4500 r / min.

[0030] (5) The prepared airflow mill powder was uniformly mixed with high-melting-point TiB2 alloy with a particle size of 50 nm in an inert gas environment at a ratio of 1:0.004. According to the size of the mold, 100 g was weighed and pressed into a 26x26x27 mm block under high-purity nitrogen protection. Subsequently, isostatic pressing was performed, and a pressure of 200 MPa was applied for 5 min.

[0031] (6) The block was loaded into a graphite box and placed in a tube sintering furnace. The vacuum was extracted to 1x10 -3 Pa, and a (Nd 83 Ce 17 ) 29.4 Fe 68.46 Ti 0.27 Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 1.02 magnet was prepared through a heat treatment process.

[0032] Example 3 (1) The components were prepared in a mass percentage of (Nd 83 Ce 17 ) 29.5 Fe bal Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 0.9 single main phase alloy.

[0033] (2) The prepared raw materials were placed in the rapid solidification furnace in a certain order, and then vacuum was extracted to 5x10 ‑3 Pa. The equipment power was then increased to 7 kW for baking treatment. After that, argon was filled, and the equipment power was slowly increased to a smelting temperature of 1500 ℃ for 3 min of refining. The alloy liquid was poured into a tundish, guided to a copper roller, and spun onto a collection tray to cool and prepare a rapid solidification sheet. The copper roller speed was designed to be 1.3 m / s, and the copper roller cooling water temperature was 22 ℃. The prepared rapid solidification sheet had a thickness of 0.26 mm.

[0034] (3) The rapid solidification sheet was placed in a hydrogen breaking furnace for hydrogen breaking treatment, and the hydrogen breaking furnace vacuum was maintained at 1x10 ‑ 3 Pa. Hydrogen was absorbed at 0.8 MPa hydrogen pressure for 1 h at room temperature, and dehydrogenation was performed at 500 ℃ for 3 h. Hydrogen breaking powder was prepared after the hydrogen absorption and dehydrogenation stages.

[0035] (4) Under the argon environment, hydrogen was poured into the jet mill tank, and the alloy powder with a particle size of 2.6 μm was prepared by the jet mill equipment under the conditions of 10 ppm of oxygen content and 4500 r / min of sorting wheel rotating speed.

[0036] (5) The prepared jet mill powder was uniformly mixed with high melting point ZrB2 alloy with a particle size of 50 nm in an inert gas environment according to 1:0.004, and 100 g was weighed according to the size of the mold and pressed into a 26×26×27 mm block under the protection of high-purity nitrogen. Subsequently, isostatic pressing was carried out, and the pressure reached 200 MPa, and the pressure holding time was 5 min.

[0037] (6) The block was loaded into a graphite box and placed in a tube sintering furnace. The vacuum was extracted to 1×10 -3 Pa, and the (Nd 83 Ce 17 ) 29.4 Fe 68.46 Zr 0.32 Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 0.97 magnet was prepared by a heat treatment process.

[0038] Example 4 (1) The components of (Nd 83 Ce 17 ) 29.5 Fe bal Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 0.9 single main phase alloy.

[0039] (2) The prepared raw materials were placed in the rapid solidification furnace in a certain order, and then vacuum was extracted to 5×10 ‑3 Pa, and then the device power was increased to 7 kW for baking treatment. Then, argon was filled, the device power was slowly increased to make the melting temperature reach 1500 ℃, and the alloy liquid was poured into the tundish and guided to the copper roller to be collected on the collection plate to prepare the rapid solidification sheet. The copper roller rotating speed was designed to be 1.3 m / s, and the copper roller cooling water temperature was 22 ℃. The prepared rapid solidification sheet had a thickness of 0.26 mm.

[0040] (3) The rapid solidification sheet was placed in a hydrogen crusher for hydrogen crushing treatment, and the hydrogen crusher vacuum degree was maintained at 1×10 ‑ 3Hydrogen-degraded powder was obtained by absorbing hydrogen at room temperature for 1 h under a hydrogen pressure of 0.8 MPa and dehydrogenating it for 3 h at 500 °C.

[0041] (4) The hydrogen was crushed and poured into the air jet mill jar under an argon atmosphere. The alloy powder with a particle size of 2.6 μm was obtained by using the air jet mill equipment under the conditions of an oxygen content of 10 ppm and a sorting wheel speed of 4500 r / min.

[0042] (5) The obtained air-jet mill powder and the high melting point CrB2 alloy with a particle size of 50 nm are uniformly mixed in an inert gas environment at a ratio of 1:0.004. According to the mold size, 100 g is weighed and pressed into a block of 26×26×27 mm under the protection of high purity nitrogen. Then isostatic pressing is performed, with a pressure of 200 MPa and a holding time of 5 min.

[0043] (6) Load the block into a graphite box, place it in a tube sintering furnace, and evacuate to a vacuum level of 1×10⁻⁶. -3 Pa, obtained through heat treatment process (Nd) 83 Ce 17 ) 29.4 Fe 68.46 Cr 0.28 Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 1.01 magnet.

[0044] Example 5 (1) The formula is prepared by mass percentage as (Nd) 83 Ce 17 ) 29.5 Fe bal Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 0.9 Single-phase alloy.

[0045] (2) Place the prepared raw materials in a certain order in the quick-setting furnace, and then evacuate to 5×10. ‑3 Pa, then increase the equipment power to 7kW for drying, then fill with argon gas, and slowly increase the equipment power to the melting temperature of 1500℃ for 3 minutes. Pour the alloy liquid into the tundish and guide it to the copper roller and throw it into the collection tray to cool and prepare it into a quick-setting sheet. The copper roller speed is designed to be 1.3 m / s, the temperature of the copper roller cooling water is 22℃, and the thickness of the quick-setting sheet is 0.26 mm.

[0046] (3) Place the quick-setting tablets into a hydrogen crushing furnace for hydrogen crushing treatment, maintaining the vacuum degree of the hydrogen crushing furnace at 1×10⁻⁶. ‑ 3 Hydrogen-degraded powder was obtained by absorbing hydrogen at room temperature for 1 hour under a hydrogen pressure of 0.8 MPa and dehydrogenating it for 3 hours at 500℃.

[0047] (4) The hydrogen was crushed and poured into the air jet mill jar under an argon atmosphere. The alloy powder with a particle size of 2.6 μm was obtained by using the air jet mill equipment under the conditions of an oxygen content of 10 ppm and a sorting wheel speed of 4500 r / min.

[0048] (5) The obtained air-jet mill powder and high-melting-point TiB2 and ZrB2 alloys with a particle size of 50 nm were uniformly mixed in an inert gas environment at a ratio of 1:0.002:0.002. 100 g of the mixture was weighed according to the mold size and pressed into a block of 26×26×27 mm under the protection of high-purity nitrogen. Then isostatic pressing was performed, with a pressure of 200 MPa and a holding time of 5 min.

[0049] (6) Load the block into a graphite box, place it in a tube sintering furnace, and evacuate to a vacuum level of 1×10⁻⁶. -3 Pa, obtained through heat treatment process (Nd) 83 Ce 17 ) 29.4 Fe 68.45 Ti 0.14 Zr 0.16 Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 1.00 magnet.

[0050] Example 6 (1) The formula is prepared by mass percentage as (Nd) 83 Ce 17 ) 29.5 Fe bal Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 0.9 Single-phase alloy.

[0051] (2) Place the prepared raw materials in a certain order in the quick-setting furnace, and then evacuate to 5×10. ‑3Pa, then increase the equipment power to 7kW for drying, then fill with argon gas, and slowly increase the equipment power to the melting temperature of 1500℃ for 3 minutes. Pour the alloy liquid into the tundish and guide it to the copper roller and throw it into the collection tray to cool and prepare it into a quick-setting sheet. The copper roller speed is designed to be 1.3 m / s, the temperature of the copper roller cooling water is 22 ℃, and the thickness of the quick-setting sheet is 0.26 mm.

[0052] (3) Place the quick-setting tablets into a hydrogen crushing furnace for hydrogen crushing treatment, maintaining the vacuum degree of the hydrogen crushing furnace at 1×10⁻⁶. ‑ 3 Hydrogen-degraded powder was obtained by absorbing hydrogen at room temperature for 1 h under a hydrogen pressure of 0.8 MPa and dehydrogenating it for 3 h at 500 °C.

[0053] (4) The hydrogen was crushed and poured into the air jet mill jar under an argon atmosphere. The alloy powder with a particle size of 2.6 μm was obtained by using the air jet mill equipment under the conditions of an oxygen content of 10 ppm and a sorting wheel speed of 4500 r / min.

[0054] (5) The obtained air-jet mill powder and high melting point TiB2 and CrB2 alloys with a particle size of 50 nm were uniformly mixed in an inert gas environment at a ratio of 1:0.002:0.002. According to the mold size, 100 g was weighed and pressed into a block of 26×26×27 mm under the protection of high purity nitrogen. Then isostatic pressing was performed, with a pressure of 200 MPa and a holding time of 5 min.

[0055] (6) Load the block into a graphite box, place it in a tube sintering furnace, and evacuate to a vacuum level of 1×10⁻⁶. -3 Pa, obtained through heat treatment process (Nd) 83 Ce 17 ) 29.4 Fe 68.45 Cr 0.14 Ti 0.14 Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 1.02 magnet.

[0056] Example 7 (1) The formula is prepared by mass percentage as (Nd) 83 Ce 17 ) 29.5 Fe bal Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B0.9 Single-phase alloy.

[0057] (2) Place the prepared raw materials in a certain order in the quick-setting furnace, and then evacuate to 5×10. ‑3 Pa, then increase the equipment power to 7 kW for drying, then fill with argon gas, slowly increase the equipment power to the melting temperature to 1500 ℃ and refine for 3 minutes, pour the alloy liquid into the tundish and guide it to the copper roller and throw it into the collection tray to cool and prepare the quick-setting sheet. The copper roller speed is designed to be 1.3 m / s, the temperature of the copper roller cooling water is 22℃, and the thickness of the quick-setting sheet is 0.26 mm.

[0058] (3) Place the quick-setting tablets into a hydrogen crushing furnace for hydrogen crushing treatment, maintaining the vacuum degree of the hydrogen crushing furnace at 1×10⁻⁶. ‑ 3 Hydrogen-degraded powder was obtained by absorbing hydrogen at room temperature for 1 h under a hydrogen pressure of 0.8 MPa and dehydrogenating it for 3 h at 500 °C.

[0059] (4) The hydrogen was crushed and poured into the air jet mill jar under an argon atmosphere. The alloy powder with a particle size of 2.6 μm was obtained by using the air jet mill equipment under the conditions of an oxygen content of 10 ppm and a sorting wheel speed of 4500 r / min.

[0060] (5) The obtained air-jet mill powder and high-melting-point ZrB2 and CrB2 alloys with a particle size of 50 nm were uniformly mixed in an inert gas environment at a ratio of 1:0.002:0.002. According to the mold size, 100 g was weighed and pressed into a block of 26×26×27 mm under the protection of high-purity nitrogen. Then isostatic pressing was performed, with a pressure of 200 MPa and a holding time of 5 min.

[0061] (6) Load the block into a graphite box, place it in a tube sintering furnace, and evacuate to a vacuum level of 1×10⁻⁶. -3 Pa, obtained through heat treatment process (Nd) 83 Ce 17 ) 29.4 Fe 68.46 Cr 0.14 Zr 0.16 Cu 0.2 Co 0.15 Si 0.1 Ga 0.25 Al 0.15 B 0.99 magnet.

[0062] The magnets prepared in Examples 1-7 were subjected to performance tests, and the results are shown in Table 1.

[0063] Table 1 Magnetic properties of magnets with different high-melting-point alloys added. As can be seen from the examples and their corresponding performance test results, the sintered Nd:C2FeB magnets obtained by the preparation method provided by the present invention have significantly improved coercivity compared with the original magnets, and their comprehensive magnetic properties have reached a better level, thus realizing the preparation of sintered Nd:C2FeB magnets with high comprehensive magnetic properties.

[0064] The comparison of magnetic properties between Examples 1 and Examples 2-4 shows that introducing a high-melting-point transition metal diboride (XB) alloy powder into the original magnet increases the coercivity by nearly 4 kOe, indicating a significant enhancement effect on magnetic properties. Furthermore, the performance comparison between Examples 2-4 and Examples 5-7 shows that the magnet prepared by synergistically adding multiple high-melting-point XB alloy powders can further improve its coercivity on the basis of the above, with an overall increase of nearly 6 kOe, accompanied by a slight increase in remanence, resulting in a significant optimization of overall magnetic properties. This performance improvement is attributed to the preferential precipitation of the XB2 phase formed by the introduced XB compound in the magnet within the grain boundary region, constructing a multi-level induced structure that guides the directional enrichment of Ce elements in the grain boundary region, thereby achieving an optimization effect on the grain boundaries and avoiding its influence on Nd2Fe. 14 The interference of the anisotropic field of the B-phase magnetocrystalline material is mitigated. Simultaneously, the appropriate enrichment of Ce elements in the grain boundaries helps suppress abnormal grain growth, achieving stable control over the microstructure. This synergistically enhances the magnetic properties and thermal stability of the magnet, exhibiting excellent structural control and performance enhancement effects.

[0065] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the scope of protection of the present invention. Any modifications and refinements made by those skilled in the art without departing from the concept and scope of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A sintered Nd:cerium-iron-boron magnet with high overall magnetic properties, characterized in that: The high-performance magnet is made by using Nd24 ... 1-x Ce x ) a M 100-a-b-c Fe b B c A sintered Nd:C:Fe:B single-phase alloy magnet is prepared by uniformly mixing and pressing a single-phase alloy powder with one or more XB alloy powders, followed by sintering and tempering treatment. The magnet is characterized by 28≤a≤33, 58≤b≤69, 0.8≤c≤1.1, 0<x≤20, M being one or more of Zn, Ga, Co, Cu, Nb, Si, Mn and Al, and X being one or more of Ti, Hf, Zr, Cr and Mo.

2. The neodymium-cerium-iron-boron magnet as described in claim 1, characterized in that: The mass ratio of the single-phase alloy powder to the XB alloy powder is 1:0.001-0.

008.

3. The neodymium-cerium-iron-boron magnet as described in claim 1, characterized in that: The atomic ratio of each element in the XB alloy is XB2.

4. The neodymium-cerium-iron-boron magnet as described in claim 1, characterized in that: In the XB alloy element, X is two different elements.

5. A method for preparing a sintered Nd:C:FeB magnet with high overall magnetic properties as described in any one of claims 1-4, comprising the following steps: (1) Raw material ratio: Preparation of (Nd 1-x Ce x ) a M 100-a-b-c Fe b B c Alloy raw materials; (2) Rapid solidification strip casting: The raw materials with a good proportion of the composition design are made into alloy rapid solidification sheets by melting and rapid solidification strip casting; (3) Hydrogen crushing: The alloy rapid solidification sheet is processed into alloy hydrogen crushing powder after passing through two stages of hydrogen absorption and dehydrogenation. (4) Airflow milling: The obtained alloy hydrogen-broken powder is milled to micron-level alloy powder by accelerated mutual collision; (5) Mixing and pressing: The particle size of high melting point XB alloy powder is controlled at 30-300 nm, and the mass percentage added is 0.001-0.

008. Then, the obtained air jet mill alloy powder and high melting point XB alloy powder are uniformly mixed in an inert gas environment for 20-30 min and oriented and pressed into shape. Then, the powder is wrapped in a multi-layer sealed bag and subjected to cold isostatic pressing treatment. The applied pressure is 100-200 MPa and the pressing time is 0.01-10 min. (6) Heat treatment: The pressed block is sintered and tempered to prepare sintered magnets.

6. The preparation method according to claim 5, characterized in that: The purity of the raw materials in step (1) must reach 99.5% or higher.

7. The preparation method according to claim 5, characterized in that: The preparation method of the alloy quick-setting sheet in step (2) is as follows: the quick-setting furnace is kept under vacuum conditions, argon gas is introduced after heating and drying the material, the crucible is heated to 1200-1600℃ by medium frequency current for refining, the molten alloy liquid is poured into the intermediate ladle, guided to the copper roller and thrown into the collection plate for cooling to prepare quick-setting sheets, the copper roller speed is designed to be 1.1-1.5m / s, the thickness of the quick-setting sheet is 0.2-0.4mm, and the temperature of the copper roller cooling water is 18-26℃.

8. The preparation method according to claim 5, characterized in that: The two stages of hydrogen absorption and dehydrogenation in step (3) are as follows: the hydrogen decompression furnace needs to be kept in an oxygen-free environment, absorb hydrogen at room temperature with a hydrogen pressure of 0.6-0.9MPa for 1-2 hours, and dehydrogenate at 450-500℃ for 2-4 hours.

9. The preparation method according to claim 5, characterized in that: In step (4), during the air jet milling process, the equipment is required to maintain an oxygen content of 10-15 ppm and the sorting wheel speed is set to 4200-4600 r / min.

10. The preparation method according to claim 5, characterized in that: The sintering in step (6) involves placing the pressed block into a graphite box, then into a tube sintering furnace, and sintering at a temperature of 1×10⁻⁶. -3 The experiment was conducted under Pa vacuum conditions.

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