Neodymium-iron-boron magnet and preparation method thereof

Abstract

The invention discloses a neodymium iron boron magnet and a preparation method thereof, and relates to the technical field of rare earth magnetic materials. The chemical formula of the neodymium iron boron magnet is [(NdPr) (1-x-y-z) LaxCeyYz] a (Fe (1-u-v-w) CouNivMw) bBc, wherein M is one or a mixture of more of aluminum, copper, gallium, titanium, gadolinium, chromium, manganese and silver, and the mass percent of each element in the neodymium-iron-boron magnet is as follows: x is more than or equal to 0 and less than or equal to 0.25; 0 < = y < = 0.25; 0 < = z < = 0.17; 0 < = u < = 0.135; 0 < = v < = 0.04; 0 < = w < = 0.03; 23 wt.% < = a < = 34.5 wt.%; 59 wt.% < = b < = 69.0 wt.%; 0.2 wt.% < = c < = 2.3 wt.%. According to the embodiment, the balance of normal-temperature and high-temperature magnetic performance and price can be realized, so that the cost performance of the magnet is improved.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth magnetic materials, and in particular to a neodymium iron boron magnet and a preparation method thereof. Background Art

[0002] Due to its excellent comprehensive magnetic properties, NdFeB magnets are widely used in aerospace, wind turbines, automobiles, and household appliances, playing an irreplaceable role.

[0003] The production of NdFeB permanent magnets requires a large amount of rare earth elements such as neodymium and praseodymium (Nd, Pr), which are in small reserves, expensive, and unstable in supply. Therefore, using light rare earth elements such as lanthanum, cerium, and yttrium (La, Ce, Y) with abundant reserves and low prices to replace part of NdPr in NdFeB magnets can reduce the use and dependence on NdPr, effectively reduce the cost of NdFeB magnets, and make balanced use of rare earth resources. However, due to their low intrinsic magnetic properties, light rare earth elements such as La / Ce / Y will significantly reduce the magnetic properties of doped NdFeB magnets, especially under high temperature conditions (150℃~200℃) where NdFeB magnets drive motors. In order to improve the temperature stability of NdFeB magnets, some transition elements with higher Curie temperatures, such as Co and Ni, are generally selected for doping. Appropriate amount of Co and Ni doping can effectively improve the temperature stability of NdFeB magnet, meet the performance requirements of high temperature, but can bring the increase of cost at the same time. In addition, by the grain boundary diffusion process of the heavy rare earth alloy containing Dy and Tb, the alloy is uniformly diffused to the grain boundary of NdFeB magnet at high temperature, improves the microstructure of NdFeB magnet, and can also effectively improve its coercive force and temperature stability. However, the grain boundary diffusion process is complicated, and uses expensive and rare heavy rare earth elements, which improves cost. In addition, the NdFeB magnet obtained by diffusion also loses a part of remanence.

[0004] Therefore, under the premise of controlling the cost of NdFeB magnets, improving the comprehensive performance of NdFeB magnets, especially the remanence and coercive force at high temperatures, has become an urgent problem to be solved.

[0005] It can be seen that the existing technology mainly has the following technical problems:

[0006] 1. The over-utilization of rare earth resources such as Nd, Pr, Dy, and Tb required for the manufacture of NdFeB magnets has increased the cost of NdFeB magnets; light rare earth elements such as La, Ce, and Y are abundant and cheap, but their utilization rate is low;

[0007] 2. La, Ce, and Y doped NdFeB magnets can reduce the cost of NdFeB magnets, but the thermal stability of NdFeB magnets is poor, causing the magnetic properties to deteriorate seriously at high temperatures, and cannot meet the actual application requirements in high temperature environments (>150°C);

[0008] 3. Co and Ni elements have high Curie temperatures. Although Co and Ni elements replace part of Fe in NdFeB magnets, they can significantly increase the Curie temperature of the magnets and improve the thermal stability of NdFeB magnets, but they reduce the saturation magnetization of the magnets and increase the cost of the magnets. Summary of the invention

[0009] In view of this, an embodiment of the present invention provides a NdFeB magnet and a method for preparing the same to solve the technical problems of poor thermal stability, deterioration of high temperature magnetic properties and high cost of NdFeB magnets.

[0010] To achieve the above object, according to one aspect of an embodiment of the present invention, a neodymium iron boron magnet is provided, and the chemical formula of the neodymium iron boron magnet is:

[0011] [(NdPr) 1-x-y-z La x Ce y Y z ] a (Fe 1-u-v-w Co u Ni v M w ) b B c

[0012] Wherein, M is a mixture of one or more of aluminum, copper, gallium, titanium, gadolinium, chromium, manganese, and silver, and the mass percentage of each element in the NdFeB magnet is as follows:

[0013] 0≤x≤0.25; 0≤y≤0.25; 0≤z≤0.17; 0≤u≤0.135; 0≤v≤0.04; 0≤w≤0.03; 23wt.%≤a≤34.5wt.%; 59wt.%≤b≤69.0wt.%; 0.2wt.%≤c≤2.3wt.%.

[0014] Optionally, the mass percentage of each element in the NdFeB magnet is as follows:

[0015] 0≤x≤0.065; 0≤y≤0.23; 0≤z≤0.032; 0≤u≤0.105; 0≤v≤0.015; 0≤w≤0.03; 27.5wt.%≤a≤30wt.%; 63wt.%≤b≤67wt.%; 0.9wt.%≤c≤1wt.%.

[0016] Optionally, the mass percentage of each element in the NdFeB magnet is as follows:

[0017] Neodymium: 23wt.%~30.8wt.%;

[0018] Lanthanum: 0wt.%~7.5wt.%;

[0019] Cerium: 0wt.%~7.5wt.%;

[0020] Yttrium: 0wt.%~5wt.%;

[0021] Cobalt: 0wt.%~9wt.%;

[0022] Nickel: 0wt.%~2.6wt.%;

[0023] Boron: 0.6wt.%~1.0wt.%;

[0024] Aluminum: 1.0wt.%~1.5wt.%;

[0025] Copper: 0.1wt.%~0.3wt.%;

[0026] Gallium: 0.1wt.%~0.3wt.%;

[0027] Titanium: 0.1-0.3wt.%;

[0028] The rest is pure iron.

[0029] Optionally, the percentage of lanthanum is: 0wt.% to 3wt.%.

[0030] Optionally, the percentage of cerium is: 0wt.% to 7wt.%.

[0031] Optionally, the percentage of yttrium is: 0wt.% to 1wt.%.

[0032] Optionally, the percentage of cobalt is: 0 wt.% to 7.2 wt.%.

[0033] Optionally, the percentage of nickel is: 0wt.% to 1.5wt.%.

[0034] Optionally, the percentage of didymium and praseodymium is 23.3 wt.% to 30 wt.%.

[0035] In addition, according to another aspect of the embodiment of the present invention, a method for preparing a neodymium iron boron magnet is provided, comprising:

[0036] Weighing each raw material according to mass percentage and mixing them evenly to obtain a mixture;

[0037] Vacuum melting the mixture to obtain NdFeB casting sheets;

[0038] crushing the NdFeB casting sheet into NdFeB alloy powder;

[0039] Orienting the NdFeB alloy powder in a magnetic field, and pressing and molding to obtain a NdFeB blank;

[0040] The NdFeB blank is subjected to high temperature sintering and tempering treatment to obtain a NdFeB magnet.

[0041] One embodiment of the above invention has the following advantages or beneficial effects: the NdFeB magnet provided by the embodiment of the present invention partially replaces the NdPr element with the high-abundance light rare earth elements La, Ce, and Y, and partially replaces the Fe element with Co and Ni, and by adjusting the ratio of the above doping components, the comprehensive performance of the NdFeB magnet is improved under the premise of controlling the cost, thereby achieving a higher cost performance. In particular, the doped NdFeB magnet has excellent temperature stability and high-temperature magnetic properties, so that it can well meet the application of high temperature environment (>150°C).

[0042] The further effects of the above-mentioned non-conventional optional manner will be described below in conjunction with the specific implementation manner. DETAILED DESCRIPTION

[0043] The following is a description of exemplary embodiments of the present invention, including various details of the embodiments of the present invention to aid understanding, which should be considered as merely exemplary. Therefore, it should be appreciated by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. Likewise, for clarity and simplicity, descriptions of well-known functions and structures are omitted in the following description.

[0044] In order to solve the technical problems existing in the prior art, the embodiment of the present invention provides a NdFeB magnet doped with 2 to 5 elements, wherein the NdPr element is partially replaced by the high-abundance light rare earth elements La, Ce, and Y, and the Fe element is partially replaced by Co and Ni, and the comprehensive performance of the NdFeB magnet is improved under the premise of controlling the cost by adjusting the ratio of the above-mentioned doping components, thereby achieving a higher cost performance. In particular, the doped NdFeB magnet has excellent temperature stability and high-temperature magnetic properties, so that it can well meet the application of high temperature environment (>150°C).

[0045] For doping of NdFeB magnets, light rare earth elements such as La, Ce, and Y will reduce the magnetic properties due to their low intrinsic magnetic properties; Co and Ni can significantly increase the Curie temperature, but will cause a serious decrease in saturation magnetization and increase the cost. The present invention creatively proposes that a certain amount of La, Ce, and Y elements replace NdPr while using Co and Ni to replace a part of the Fe element to form a stable (NdPr, La / Ce / Y)2(Fe, Co / Ni) 14 Phase B is used to further prepare the corresponding NdFeB magnet, which has excellent temperature stability and comprehensive performance and can be used at high temperatures.

[0046] Based on the above inventive concept, the embodiment of the present invention provides a sintered NdFeB rare earth magnetic material co-doped with rare earth elements and transition metals, which breaks through the 14 B alone is replaced by a single replacement, and [(NdPr) 1-x-y-z La x Ce y Y z ] a (Fe 1-u-v-w Co u Ni v M w ) b B c Phase. Wherein, M is a mixture of one or more of Al (aluminum), Cu (copper), Ga (gallium), Ti (titanium), Gd (gadolinium), Cr (chromium), Mn (manganese), and Ag (silver); the mass percentage of each element in the NdFeB magnet is as follows: 0≤x≤0.25; 0≤y≤0.25; 0≤z≤0.17; 0≤u≤0.135; 0≤v≤0.04; 0≤w≤0.03; 23wt.%≤a≤34.5wt.%; 59wt.%≤b≤69.0wt.%; 0.2wt.%≤c≤2.3wt.%.

[0047] It should be noted that x has no numerical relationship with y and z; 1-xyz is the proportion of NdPr; u has no numerical relationship with v and w; 1-uvw is the proportion of Fe; a+b+c=100wt.%.

[0048] The NdFeB magnet provided by the embodiment of the present invention does not contain heavy rare earth elements and reduces the usage of NdPr elements, thereby alleviating the oversupply of high-abundance light rare earth resources, allowing rare earth resources to be used in a balanced manner and reducing the production cost of the NdFeB magnet.

[0049] Optionally, the mass percentage of each element in the NdFeB magnet is as follows: 0≤x≤0.065; 0≤y≤0.23; 0≤z≤0.032; 0≤u≤0.105; 0≤v≤0.015; 0≤w≤0.03; 27.5wt.%≤a≤30wt.%; 63wt.%≤b≤67wt.%; 0.9wt.%≤c≤1wt.%. The NdFeB magnet provided in the embodiment of the present invention improves the squareness of the NdFeB matrix through the preferred doping components, reduces the absolute value of the remanence and coercive force temperature coefficient (~150°C) of the NdFeB magnet, is superior to single-doped and double-doped magnets with similar costs, improves the high-temperature magnetic properties of the NdFeB magnet, and can meet the application of motors in high temperature (>150°C) environments while reducing costs.

[0050] Optionally, the mass percentage of each element in the NdFeB magnet is as follows:

[0051] Neodymium: 23wt.%~30.8wt.%;

[0052] Lanthanum: 0wt.%~7.5wt.%;

[0053] Cerium: 0wt.%~7.5wt.%;

[0054] Yttrium: 0wt.%~5wt.%;

[0055] Cobalt: 0wt.%~9wt.%;

[0056] Nickel: 0wt.%~2.6wt.%;

[0057] Boron: 0.6wt.%~1.0wt.%;

[0058] Aluminum: 1.0wt.%~1.5wt.%;

[0059] Copper: 0.1wt.%~0.3wt.%;

[0060] Gallium: 0.1wt.%~0.3wt.%;

[0061] Titanium: 0.1-0.3wt.%;

[0062] The rest is pure iron.

[0063] The NdFeB magnet provided by the embodiment of the present invention reduces the use of scarce and expensive elements such as NdPr in the magnet, and utilizes the light rare earth elements La, Ce, and Y with high abundance and low cost, so as to make rational use of rare earth resources.

[0064] In some embodiments of the present invention, the percentage of lanthanum is: 0wt.% ~ 3wt.%, and the embodiments of the present invention use 0wt.% ~ 3wt.% La element to replace NdPr in part of the NdFeB magnet, reducing the amount of NdPr element used, thereby reducing the cost of the magnet. Optionally, the percentage of lanthanum is: 0.3wt.% ~ 2wt.%. Optionally, the percentage of lanthanum is: 0.5wt.% ~ 2wt.%. Optionally, the percentage of lanthanum is: 0.88wt.% ~ 2wt.%. Optionally, the percentage of lanthanum is: 0.88wt.% ~ 1.76wt.%. Optionally, the percentage of lanthanum is: 0.3wt.% ~ 0.88wt.%. Optionally, the percentage of lanthanum is: 0.1wt.% ~ 0.3wt.%. Optionally, the percentage of lanthanum is: 0.1wt.% ~ 0.2wt.%.

[0065] In some embodiments of the present invention, the percentage of cerium is: 0wt.%~7wt.%. The embodiment of the present invention uses 0wt.%~7wt.% of Ce element to replace NdPr in part of the NdFeB magnet, reducing the usage of NdPr element, thereby reducing the cost of the magnet. Optionally, the percentage of cerium is: 0.2wt.%~7wt.%. Optionally, the percentage of cerium is: 0.66wt.%~6.62wt.%. Optionally, the percentage of cerium is: 0.66wt.%~4.64wt.%. Optionally, the percentage of cerium is: 1.33wt.%~4.64wt.%. Optionally, the percentage of cerium is: 1.33wt.%~3.97wt.%. Optionally, the percentage of cerium is: 1.33wt.%~3.31wt.%. Optionally, the percentage of cerium is: 0.2wt.%~0.8wt.%. Optionally, the percentage of cerium is 0.1 wt.% to 0.3 wt.%. Optionally, the percentage of cerium is 0.1 wt.% to 0.5 wt.%.

[0066] In some embodiments of the present invention, the percentage of yttrium is: 0wt.% ~ 1wt.%, and the embodiment of the present invention uses 0wt.% ~ 1wt.% of Y element to replace NdPr in part of the NdFeB magnet, reducing the amount of NdPr element used, thereby reducing the cost of the magnet. Optionally, the percentage of yttrium is: 0.27wt.% ~ 1wt.%. Optionally, the percentage of yttrium is: 0.54wt.% ~ 1wt.%. Optionally, the percentage of yttrium is: 0.27wt.% ~ 0.54wt.%. Optionally, the percentage of yttrium is: 0.1wt.% ~ 0.5wt.%. Optionally, the percentage of yttrium is: 0.1wt.% ~ 0.3wt.%. Optionally, the percentage of yttrium is: 0.1wt.% ~ 0.6wt.%.

[0067] In some embodiments of the present invention, the percentage of cobalt is: 0wt.% ~ 7.2wt.%. The embodiment of the present invention uses 0wt.% ~ 7.2wt.% Co element to replace part of Fe in the NdFeB magnet, which not only improves the thermal stability of the NdFeB magnet, but also meets the practical application of the NdFeB magnet in a high temperature (> 150°C) environment. Optionally, the percentage of cobalt is: 0.26wt.% ~ 7.2wt.%. Optionally, the percentage of cobalt is: 0.6wt.% ~ 7.2wt.%. Optionally, the percentage of cobalt is: 0.6wt.% ~ 6wt.%. Optionally, the percentage of cobalt is: 1.03wt.% ~ 5.5wt.%. Optionally, the percentage of cobalt is: 0.26wt.% ~ 1.03wt.%. Optionally, the percentage of cobalt is: 0.1wt.% ~ 0.2wt.%. Optionally, the percentage of cobalt is: 0.1wt.% ~ 0.5wt.%. Optionally, the percentage of cobalt is: 0.1wt.% to 0.8wt.%.

[0068] In some embodiments of the present invention, the percentage of nickel is: 0wt.% ~ 1.5wt.%. The embodiment of the present invention uses 0wt.% ~ 1.5wt.% Ni element to replace part of Fe in the NdFeB magnet, which not only improves the thermal stability of the NdFeB magnet, but also meets the practical application of the NdFeB magnet in a high temperature (> 150°C) environment. Optionally, the percentage of nickel is: 0.1wt.% ~ 1.2wt.%. Optionally, the percentage of nickel is: 0.15wt.% ~ 1.15wt.%. Optionally, the percentage of nickel is: 0.25wt.% ~ 1.1wt.%. Optionally, the percentage of nickel is: 0.37wt.% ~ 1.03wt.%. Optionally, the percentage of nickel is: 0.1wt.% ~ 0.3wt.%. Optionally, the percentage of nickel is: 0.1wt.% ~ 0.5wt.%. Optionally, the percentage of nickel is: 0.1wt.% ~ 0.6wt.%. Doping a small amount of Ni helps to improve the high temperature (150°C) comprehensive performance of the magnet.

[0069] Optionally, the percentage of neodymium and praseodymium is 23.3 wt.% to 30 wt.%. The embodiment of the present invention reduces the use of scarce and expensive elements such as NdPr in the magnet, and utilizes the light rare earth elements La and Ce with high abundance and low cost, so as to make rational use of rare earth resources.

[0070] It can be seen that in NdFeB magnets that do not contain the heavy metal element Dy, a certain amount of La, Ce, Y co-doped with Co and Ni makes the magnet have a synergistic effect, improves the remanence and coercive force (150°C) temperature stability of the NdFeB magnet, and its thermal stability is significantly higher than that of undoped, La or Co single-doped, and Ce and Co co-doped magnets. It can improve the high-temperature magnetic properties of the magnet, meet the practical application of NdFeB magnets in high temperature (>150°C) environments, and reduce the cost of the magnet.

[0071] The present invention also provides a method for preparing a NdFeB magnet, comprising the following steps:

[0072] Weighing each raw material according to mass percentage and mixing them evenly to obtain a mixture;

[0073] Vacuum melting the mixture to obtain NdFeB casting sheets;

[0074] crushing the NdFeB casting sheet into NdFeB alloy powder;

[0075] Orienting the NdFeB alloy powder in a magnetic field, and pressing and molding to obtain a NdFeB blank;

[0076] The NdFeB blank is subjected to high temperature sintering and tempering treatment to obtain a NdFeB magnet.

[0077] In order to help understand the solutions of the present invention, several specific technical solutions are given below for detailed description.

[0078] Example 1

[0079] A NdFeB magnet, the preparation method of which comprises the following steps:

[0080] 29.87wt.% NdPr, 0.66wt.% Ce, 0.27wt.% Y, 0.37wt.% Ni, 66.27wt.% Fe, 0.96wt.% B, 1.20wt.% Al, 0.15wt.% Cu, 0.15wt.% Ga, and 0.10wt.% Ti are weighed in proportion, mixed evenly, and a mixture is prepared;

[0081] The uniformly mixed mixture is vacuum-melted to obtain NdFeB casting sheets;

[0082] The NdFeB casting flakes are coarsely crushed by hydrogen treatment and finely crushed by fluidized bed jet mill into NdFeB alloy powder with an average particle size of about 4μm;

[0083] Orienting the NdFeB alloy powder in a 2T magnetic field, and pressing and molding to obtain a NdFeB blank;

[0084] The NdFeB blank is sintered at a high temperature of 1030-1060°C for 6-8 hours, then subjected to primary tempering at 800-850°C for 2-4 hours, and then subjected to secondary tempering at 450-520°C for 3-5 hours to obtain a NdFeB magnet.

[0085] Embodiment 2-6

[0086] The difference from Example 1 is that Examples 2-6 are double / triple / quadruple / pentad NdFeB magnets doped with La, Ce, Y, Co, and Ni in different mass percentages (wt.%), as shown in Table 1.

[0087] Table 1 Element composition and mass percentage (wt.%) of NdFeB magnets in Examples 1-6

[0088] Elemental composition Nb La Ce Y Co Ni Fe B Example 1 29.87 0.66 0.27 0.37 66.27 0.96 Example 2 29.47 1.33 1.03 65.61 0.96 Example 3 27.22 3.31 0.27 0.26 0.37 66.01 0.96 Example 4 27.71 1.76 1.33 0.37 66.27 0.96 Example 5 25.95 0.88 3.97 0.27 0.26 0.37 66.01 0.96 Example 6 23.64 6.62 0.54 1.03 65.61 0.96

[0089] Comparative Examples 1-9

[0090] The difference from Example 1 is that Comparative Example 1 is a Nd-Fe-undoped NdFeB magnet, and Comparative Examples 2-9 are single-doped and double-doped NdFeB magnets of La, Ce, Y, Co, and Ni, as shown in Table 2.

[0091] Table 2 Element composition and mass percentage (wt.%) of NdFeB magnets in Comparative Examples 1-9

[0092]

[0093] The prices of each element: NdPr: 750RMB / kg, La: 35RMB / kg, Ce: 28RMB / kg, Y: 230RMB / kg, Fe: 8RMB / kg, Co: 400RMB / kg, Ni: 150RMB / kg.

[0094] The material price calculation formula is as follows:

[0095] Material price = NdPr price * NdPr quality + La price * La quality + Ce price * Ce quality + Y price * Y quality + Fe price * Fe quality + Co price * Co quality + Ni price * Ni quality

[0096] Here, only the influence of the elements with varying contents on the material price, comprehensive performance and cost performance (150°C) is considered, and the elements with constant contents such as B, Al, Cu, Ga, Ti, etc. are not considered. Among them, the calculation of relative prices is based on Comparative Example 1 (NdFeB magnets without La, Ce, Y, Co, and Ni doping) as a reference system. The details are shown in Table 3.

[0097] Table 3 Prices of NdFeB magnets in Examples 1-6 and Comparative Examples 1-9

[0098]

[0099]

[0100] The NdFeB magnets in Examples 1-6 and Comparative Examples 1-9 were tested at 20°C to 150°C to obtain the corresponding magnetic properties and temperature coefficients, as shown in Table 4.

[0101] Table 4 Magnetic properties and temperature coefficients of Examples 1-6 and Comparative Examples 1-9 at different temperatures

[0102]

[0103]

[0104] Among them, Br represents the remanence, α Br Represents the remanence temperature coefficient, H cj represents the coercive force, β Hcj Represents the coercivity temperature coefficient, H k / H cj Indicates squareness, (BH) max Represents the maximum magnetic energy product.

[0105] It can be seen from Tables 3-4 that, compared with Comparative Example 1 (undoped magnet), the costs of Examples 1-2 and Comparative Example 2 are comparable. Relative to Comparative Example 1 (undoped magnet), the high temperature remanence temperature coefficient (150°C) of Examples 1-2 is better than that of Comparative Example 1 (undoped magnet). Relative to Comparative Example 1, the coercivity of Examples 1-2 at all temperatures is improved (the coercivity is increased), and the high temperature (150°C) coercivity temperature coefficient is also significantly improved (the absolute value is decreased). In particular, relative to Comparative Example 1, the squareness (H k / H cj ) is also significantly higher. Compared with Comparative Example 1 (undoped magnet), the maximum magnetic energy product and comprehensive performance at high temperature (150°C) of Example 1-2 are improved. Relative to Comparative Example 2, the maximum magnetic energy product and comprehensive performance of Example 1-2 at each temperature are improved. In summary, compared with Comparative Example 1, Example 1 (Ce, Y, Ni triple doping) and Example 2 (Ce, Co double doping) significantly improve the high temperature coercive force and maintain a high squareness while basically maintaining the remanence level, thereby significantly improving the maximum magnetic energy product and comprehensive performance at high temperature (150°C). In particular, compared with Comparative Example 1, which has the highest comprehensive performance at high temperature (150°C) among the comparative examples, under the premise of similar cost, the comprehensive performance at high temperature (150°C) of Example 1 is improved from 28.82 to 30.28, and the improvement ratio is up to ~5%.

[0106] It can be seen from Table 3-4 that the cost of Example 3-4 is comparable to that of Comparative Example 3-4. Relative to Comparative Example 3-4, Example 3-4 has obvious advantages in remanence and coercivity at various temperatures. Relative to Comparative Example 3-4, the squareness of Example 3 at various temperatures is significantly improved. Relative to Comparative Example 3-4, the maximum magnetic energy product and comprehensive performance of Example 3-4 at various temperatures are greatly improved. In summary, compared with Comparative Example 3-4, Example 3 (Ce, Y, Co, Ni quad-doping) and Example 4 (La, Ce, Ni triple-doping) show better remanence, especially coercivity, thereby significantly improving the maximum magnetic energy product and comprehensive performance. In particular, compared with Example 3 having higher comprehensive performance at high temperature (150°C), under the premise of similar cost, the comprehensive performance at high temperature (150°C) of Examples 3-4 was improved from 24.15 (Comparative Example 3) to 26.98 (Example 4) and 26.07 (Example 5), respectively, with an improvement of ~12% (Example 3) and ~8% (Example 4).

[0107] It can be seen from Table 3-4 that the cost of Example 5 is comparable to that of Comparative Examples 5-6. Relative to Comparative Examples 5-6, the room temperature (20°C) remanence of Example 5 is significantly improved. Relative to Comparative Examples 5-6, the coercivity of Example 5 at all temperatures is significantly improved. Relative to Comparative Examples 5-6, the squareness of Example 5 at all temperatures is significantly improved. Relative to Comparative Examples 5-6, the maximum magnetic energy product and comprehensive performance of Example 5 at all temperatures are improved, especially at high temperatures (150°C). In summary, compared with Comparative Examples 5-6, Example 5 (La, Ce, Y, Co, Ni five doping) significantly improves the coercivity and squareness while basically maintaining the remanence level, thereby significantly improving the maximum magnetic energy product and comprehensive performance at all temperatures. In particular, compared with Comparative Example 6, which has the highest comprehensive performance at high temperature (150°C) among the comparative examples, under the premise of similar cost, the high temperature (150°C) comprehensive performance of Example 5 is improved from 10.66 to 24.24, and the improvement ratio exceeds 100%.

[0108] It can be seen from Table 3-4 that the cost of Example 6 is comparable to that of Comparative Examples 7-9. Compared with Comparative Examples 7-9, the remanence and coercivity of Example 6 at room temperature (20°C) at each temperature are significantly improved, and the coercivity is more significantly improved. In particular, the remanence and coercivity temperature coefficients of Example 6 at each temperature are similar to or better than those of Comparative Examples 7-9. Compared with Comparative Examples 7-9, the squareness of Example 6 at each temperature is significantly improved. In summary, compared with Comparative Examples 7-9, Example 6 (Ce, Y, Ni triple doping) significantly improves the maximum magnetic energy product and comprehensive performance at high temperature (150°C) while improving the levels of remanence, coercivity and squareness. In particular, compared with Comparative Example 7, which has a higher comprehensive performance at high temperature (150°C), under the premise of similar cost, the comprehensive performance of Example 6 at high temperature (150°C) is improved from 19.88 (Comparative Example 7) to 23.15, with an improvement of ~16%.

[0109] By comparing the comprehensive performance of Examples 1-6 and Comparative Examples 1-9, it can be seen that the high temperature (150°C) comprehensive performance of Examples 1-6 is significantly higher than that of Comparative Examples 1-9 with similar costs; by comparing the doping components of Examples 1-6 and Comparative Examples 1-9, it can be seen that the significant feature of the doping components of Example 1-3 is the doping of a small amount of Ni (0.37-1.03wt.%), compared with a large amount of Ni (2.6wt.%) in Comparative Examples 2, 4, and 9, and the absence of Ni in other Comparative Examples. In summary, the small amount of Ni doped in Examples 1-6 helps to improve the high temperature (150°C) comprehensive performance of the magnet.

[0110] By comparing the squareness of Examples 1-6 and Comparative Examples 1-9, it can be seen that the squareness of Examples 1, 3, 5, and 6 is significantly higher than that of other Examples and Comparative Examples 1-9 in the range of 20°C to 150°C; by comparing the doping components of Examples 1, 3, 5, and 6 and other Examples and Comparative Examples 1 to 9, it can be seen that the significant feature of the doping components of Examples 1, 3, 5, and 6 is the doping of a small amount of Y (0.27-0.54 wt.%), relative to the large amount of Y (5 wt.%) of Comparative Examples 3 and 4, and the absence of Y in other Comparative Examples. In summary, the small amount of Y doped in Examples 1, 3, 5, and 6 improves the squareness, and further improves the maximum magnetic energy product and comprehensive performance.

[0111] Comparing Example 1 with Comparative Example 1 (undoped magnet), under the premise of similar cost, Example 1 improves the coercive force and its temperature stability at the expense of a small amount of remanence and its temperature stability through the preferred doping of Ce, Y, and Ni, thereby achieving a higher high temperature (150°C) maximum magnetic energy product and comprehensive performance. Compared with Comparative Example 1 (undoped magnet), the high temperature (150°C) comprehensive performance of Example 1 is improved by ~10%. Thereby, the high temperature (150°C) cost performance is improved by ~13%. Therefore, the ternary doping component of Example 1 has excellent performance and is expected to become a low-cost high-temperature applicable NdFeB magnet solution. Among them, Y doping improves squareness, Ni doping improves temperature stability, and the co-doping synergistic effect of the above elements achieves the high comprehensive performance of Example 1.

[0112] Comparing Example 3 with Comparative Example 1 (undoped magnet), under the premise of reducing the cost by ~10%, Example 3 improves the high-temperature coercivity and temperature stability at the expense of part of the remanence and temperature stability through the preferred doping of Ce, Y, Co, and Ni, thereby achieving a high-temperature (150°C) maximum magnetic energy product and comprehensive performance close to that of Comparative Example 1. Compared with Comparative Example 1 (undoped magnet), the high-temperature (150°C) comprehensive performance of Example 3 is only reduced by ~2%. Thereby, the high-temperature (150°C) cost performance is improved by ~10%. Therefore, the quaternary doping component of Example 3 has excellent performance and is expected to become a low-cost high-temperature applicable NdFeB magnet solution. Among them, Ce and Co co-doping is beneficial to achieving high coercivity and temperature stability, Y doping improves squareness, and Ni doping improves temperature stability. The co-doping synergistic effect of the above elements achieves the high comprehensive performance of Example 3.

[0113] Comparing Example 5 with Comparative Example 1 (undoped magnet), under the premise of reducing the cost by ~15%, Example 5 sacrifices part of the remanence and coercive force and its temperature stability through the preferred doping of La, Ce, Y, Co, and Ni, but maintains the squareness at various temperatures. Compared with Comparative Example 1 (undoped magnet), the high temperature (150°C) comprehensive performance of Example 5 is reduced from 27.44 to 24.24, a reduction of ~12%. Thereby, the high temperature (150°C) cost performance is improved by ~3%. Therefore, the five-element doping component of Example 5 has excellent performance and is expected to become a low-cost high-temperature applicable NdFeB magnet solution. Among them, Ce and Co co-doping is beneficial to achieving high coercive force and temperature stability, Y doping improves squareness, and Ni doping improves temperature stability. The co-doping synergistic effect of the above elements achieves the high comprehensive performance of Example 5.

[0114] This shows that when La, Ce, Y, Co, and Ni are co-doped, the NdFeB magnet has a synergistic effect, and the comprehensive performance of the various less doped multi-optimized components proposed in the present invention is significantly higher than the corresponding magnets with similar costs (Comparative Examples 2-9), and is close to the undoped magnet (Comparative Example 1). The obtained NdFeB magnet achieves excellent high temperature (150°C) comprehensive performance, so it has a high cost-effectiveness, and can realize the application of NdFeB magnets in high temperature (>150°C) environments.

[0115] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A neodymium iron boron magnet, characterized in that: The chemical formula of the NdFeB magnet is: [(NdPr) 1-x-y-z There x This y Y z ] a (Fe 1-u-v-w Co u Neither v M w ) b B c Wherein, M is a mixture of one or more of aluminum, copper, gallium, titanium, gadolinium, chromium, manganese, and silver, and the mass percentage of each element in the NdFeB magnet is as follows: 0≤x≤0.25; 0≤y≤0.25; 0≤z≤0.17; 0≤u≤0.135; 0≤v≤0.04; 0≤w≤0.03; 23wt.%≤a≤34.5wt.%; 59wt.%≤b≤69.0wt.%; 0.2wt.%≤c≤2.3wt.%.

2. The NdFeB magnet according to claim 1, characterized in that: The mass percentage of each element in the NdFeB magnet is as follows: 0≤x≤0.065; 0≤y≤0.23; 0≤z≤0.032; 0≤u≤0.105; 0≤v≤0.015; 0≤w≤0.03; 27.5wt.%≤a≤30wt.%; 63wt.%≤b≤67wt.%; 0.9wt.%≤c≤1wt.%.

3. The NdFeB magnet according to claim 2, characterized in that: The mass percentage of each element in the NdFeB magnet is as follows: Neodymium: 23wt.%~30.8wt.%; Lanthanum: 0wt.%~7.5wt.%; Cerium: 0wt.%~7.5wt.%; Yttrium: 0wt.%~5wt.%; Cobalt: 0wt.%~9wt.%; Nickel: 0wt.%~2.6wt.%; Boron: 0.6wt.%~1.0wt.%; Aluminum: 1.0wt.%~1.5wt.%; Copper: 0.1wt.%~0.3wt.%; Gallium: 0.1wt.%~0.3wt.%; Titanium: 0.1-0.3wt.%; The rest is pure iron.

4. The NdFeB magnet according to claim 3, characterized in that: The percentage of lanthanum is: 0wt.% to 3wt.%.

5. The NdFeB magnet according to claim 3, characterized in that: The percentage of cerium is: 0wt.% to 7wt.%.

6. The NdFeB magnet according to claim 3, characterized in that: The percentage of yttrium is: 0wt.%~1wt.%.

7. The NdFeB magnet according to claim 3, characterized in that: The percentage of cobalt is: 0wt.% to 7.2wt.%.

8. The NdFeB magnet according to claim 3, characterized in that: The percentage of nickel is: 0wt.% to 1.5wt.%.

9. The NdFeB magnet according to any one of claims 1 to 6, characterized in that: The percentage of didymium and praseodymium is 23.3 wt.% to 30 wt.%.

10. A method for preparing a NdFeB magnet as claimed in any one of claims 1 to 9, characterized in that: include: Weighing each raw material according to mass percentage and mixing them evenly to obtain a mixture; Vacuum melting the mixture to obtain NdFeB casting sheets; crushing the NdFeB casting sheet into NdFeB alloy powder; Orienting the NdFeB alloy powder in a magnetic field, and pressing and molding to obtain a NdFeB blank; The NdFeB blank is subjected to high temperature sintering and tempering treatment to obtain a NdFeB magnet.

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