Aluminum-nickel-cobalt permanent magnet, preparation method thereof and precision component

Abstract

The invention relates to an aluminum-nickel-cobalt permanent magnet, a preparation method thereof and a precision part. The preparation method of the aluminum-nickel-cobalt permanent magnet comprises the following steps that raw materials are provided according to the stoichiometric ratio of the aluminum-nickel-cobalt permanent magnet, the raw materials are sequentially subjected to smelting treatment and directional solidification casting, and a casting is prepared; the casting is sequentially subjected to homogenization heat treatment, magnetic field heat treatment and tempering aging treatment, and the aluminum-nickel-cobalt permanent magnet is prepared; wherein the homogenization heat treatment is performed at the temperature of 1200-1350 DEG C in a heat preservation manner; in the step of magnetic field heat treatment, the direction of a magnetic field and the crystal orientation of the casting are in the same direction, and the crystal orientation of the casting is crystal brim in an X-ray diffraction pattern of the casting; 100 gt; and orienting. According to the method, the aluminum-nickel-cobalt permanent magnet which is relatively regular in structure, high in component uniformity and high in performance stability is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of alloys, and in particular to an AlNiCo permanent magnet, a preparation method thereof, and precision components. Background Art

[0002] Alnico permanent magnets have advantages such as high Curie temperature and operating temperature, excellent temperature stability, good mechanical properties and corrosion resistance. They are widely used in various industrial fields and are particularly suitable for the preparation of high-end precision components such as parts for aerospace and precision instruments.

[0003] Alnico permanent magnets are primarily alloys composed of aluminum, nickel, cobalt, iron, and other trace metal elements. They are typically produced through induction melting, where the raw alloy is melted into molten steel, then poured into sand molds to create alloy ingots, which are then processed. However, due to the limitations of traditional casting methods, severe component segregation is unavoidable in the final product, leading to irregular crystal structures in the castings. This ultimately results in reduced magnet performance, poor consistency, and instability, creating a critical technical challenge that urgently needs to be addressed in the magnetic materials industry.

[0004] Therefore, the existing technology still needs to be improved. Summary of the Invention

[0005] Based on this, the present invention provides an aluminum nickel cobalt permanent magnet with a relatively regular structure, high component uniformity, and high performance stability, as well as a preparation method and precision components thereof.

[0006] One aspect of the present invention provides a method for preparing an AlNiCo permanent magnet, comprising the following steps:

[0007] Providing raw materials according to the stoichiometric ratio of AlNiCo permanent magnets, and sequentially performing smelting treatment and directional solidification casting on the raw materials to prepare castings;

[0008] The casting is sequentially subjected to homogenization heat treatment, magnetic field heat treatment and tempering aging treatment to prepare an AlNiCo permanent magnet;

[0009] Wherein, the homogenization heat treatment is carried out at a temperature of 1200°C to 1350°C; in the step of magnetic field heat treatment, the direction of the magnetic field is in the same direction as the crystal orientation of the casting, and the crystal orientation of the casting is the direction of the crystal along the X-ray diffraction pattern of the casting. <100> orientation.

[0010] The preparation method provided by the present invention, through the sequential smelting treatment, directional solidification casting, specific homogenization heat treatment, specific magnetic field heat treatment and tempering aging treatment, can obtain a crystal with good structure and crystal along the <100> On the other hand, by adding a specific homogenization heat treatment step, the degree of component segregation is significantly reduced, the internal stress generated during the casting process is reduced, and the internal structural defects of the casting are improved to a certain extent. The coordinated influence of various process conditions can obtain AlNiCo permanent magnets with a more regular structure and high component uniformity, thereby improving the performance stability of AlNiCo permanent magnets.

[0011] In some embodiments, the homogenization heat treatment time is 0.5h~7h; and / or

[0012] The directional solidification casting step is performed using a mold, the temperature of the mold is 1450°C to 1700°C, the mold is provided with a riser, the pouring thickness of the riser is 10mm to 25mm, and the mold is placed on a water-cooled plate with a water temperature of 20°C to 40°C.

[0013] In the step of further regulating directional solidification casting, the casting process conditions used in casting are used to promote the crystal to <100> Directional growth.

[0014] In some embodiments, the magnetic field heat treatment step includes the following conditions:

[0015] First, solution treat at 1220℃~1280℃ for 10min~60min, then cool to 800℃~950℃ at a rate of 1℃ / s~30℃ / s, then cover with insulation cotton and cool to below 500℃ in a magnetic field greater than 0.3T or keep warm at 780℃~860℃ for 5min~40min, and finally air cool to room temperature in a magnetic field.

[0016] By regulating the conditions of magnetic field heat treatment, the structural uniformity of AlNiCo permanent magnets can be further improved.

[0017] In some embodiments, the tempering and aging treatment step includes the following conditions:

[0018] First, keep it at 620℃~660℃ for 3h~10h, then cool it down to 560℃~600℃ and keep it for 10h~15h, then cool it down to 530℃~570℃ and keep it for 12h-20h, and finally cool it down to below 150℃ with the furnace.

[0019] The tempering and aging treatment adopts a specific three-stage tempering treatment, which can further improve the composition uniformity of the AlNiCo permanent magnet.

[0020] In some embodiments, the smelting process is performed in an induction melting furnace, and the obtained molten steel temperature is 1600° C. to 1800° C.

[0021] In some embodiments, after the homogenization heat treatment step and before the magnetic field heat treatment step, the method further includes performing pre-processing on the casting that has undergone the homogenization heat treatment, wherein the pre-processing includes cutting and grinding.

[0022] Pre-processing steps can improve the consistency of product appearance quality.

[0023] In some embodiments, the composition of the alnico permanent magnet includes, by mass percentage, 5%-10% Al, 8%-15% Ni, 20%-45% Co, 2%-5% Cu, less than 10% Ti, less than 1.5% Nb, less than 0.3% S, less than 0.3% C, less than 0.5% Si, and the balance Fe.

[0024] Another aspect of the present invention provides an AlNiCo permanent magnet, wherein in the X-ray diffraction pattern of the AlNiCo permanent magnet, the crystals along <100> orientation; and in any two parts of the alnico permanent magnet, the difference in the percentage of the Al element does not exceed 0.5%, the difference in the percentage of the Ni element does not exceed 1%, the difference in the percentage of the Co element does not exceed 2%, and the difference in the percentage of the Fe element does not exceed 2%;

[0025] Alternatively, the AlNiCo permanent magnet is prepared by the AlNiCo permanent magnet preparation method as described above.

[0026] In some embodiments, the composition of the alnico permanent magnet further includes Ti and Cu elements, and in any two parts of the alnico permanent magnet, the difference in the percentage of the Ti element does not exceed 0.5%, and the difference in the percentage of the Cu element does not exceed 0.3%.

[0027] According to another aspect of the present invention, a precision component is provided, comprising the above-mentioned AlNiCo permanent magnet.

[0028] The AlNiCo permanent magnet has a regular structure and high composition uniformity, thereby improving the stability of its performance. It can be used to prepare precision components and effectively improve the stability of the precision components. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is an X-ray diffraction (XRD) pattern of the AlNiCo permanent magnet prepared in Example 1;

[0030] Figure 2 This is the X-ray diffraction (XRD) pattern of the AlNiCo permanent magnet prepared in Comparative Example 1. DETAILED DESCRIPTION

[0031] To facilitate understanding of the present invention, the present invention will be described in more detail below. Preferred embodiments of the present invention are provided in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0033] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0034] The terms "and / or", "or / and", and "and / or" used herein include any one of two or more related listed items, and also include any and all combinations of the related listed items, wherein the any and all combinations include any combination of two related listed items, any more related listed items, or all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in this application, the technical solution undoubtedly includes technical solutions connected by "logical AND" and technical solutions connected by "logical OR".

[0035] In the present invention, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no conflicts or constraints.

[0036] In the present invention, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values within the numerical interval is deemed to be continuous and includes the two numerical endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between the two numerical endpoints. Unless otherwise specified, when a numerical interval refers only to integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. "Numerical interval" allows for broadly including numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0037] The temperature parameters in the present invention, unless otherwise specified, allow for both constant temperature treatment and temperature fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for temperature fluctuations within the precision range of instrument control. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are permitted. In the present invention, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, for example, 20°C ± 5°C.

[0038] The mass or weight of the relevant components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also represent the mass or weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally increased or decreased according to the description of the embodiments of the present invention, it is within the scope disclosed in the description of the embodiments of the present invention. Specifically, the mass or weight mentioned in the description of the embodiments of the present invention may be units commonly known in the chemical industry, such as μg, mg, g, and kg.

[0039] An embodiment of the present invention provides a method for preparing an AlNiCo permanent magnet, comprising the following steps S10 to S20.

[0040] S10: providing raw materials according to the stoichiometric ratio of the AlNiCo permanent magnet, and sequentially performing smelting treatment and directional solidification casting on the raw materials to prepare a casting.

[0041] S20: performing homogenization heat treatment, magnetic field heat treatment and tempering aging treatment on the casting in sequence to prepare an AlNiCo permanent magnet.

[0042] The homogenization heat treatment is carried out at a temperature of 1200°C to 1350°C; in the step of magnetic field heat treatment, the direction of the magnetic field is in the same direction as the crystal orientation of the casting, and the crystal orientation of the casting is the direction along the crystal in the X-ray diffraction pattern of the casting. <100> orientation.

[0043] Research has found that the main factors affecting the uniformity and stability of AlNiCo permanent magnets are their intrinsic properties and organizational structure, and the preparation and casting process is the direct cause of the influence on the intrinsic properties and organizational structure of the product. Therefore, after a large number of experimental explorations, the present invention provides the above-mentioned preparation method, which obtains a good crystal structure and a crystal structure along the crystal by sequentially performing smelting treatment, directional solidification casting, specific homogenization heat treatment, specific magnetic field heat treatment and tempering aging treatment. <100> On the other hand, by adding a specific homogenization heat treatment step, the degree of component segregation is significantly reduced, the internal stress generated during the casting process is reduced, and the internal structural defects of the casting are improved to a certain extent. The coordinated influence of various process conditions can obtain AlNiCo permanent magnets with a more regular structure and high component uniformity, thereby improving the performance stability of AlNiCo permanent magnets.

[0044] “The direction of the magnetic field is in the same direction as the crystal orientation of the casting” can be understood as the two directions are parallel.

[0045] In some embodiments, the homogenization heat treatment time is 0.5 h to 7 h.

[0046] In some embodiments, the smelting step is performed in an induction melting furnace, and the obtained molten steel temperature is 1600° C. to 1800° C.

[0047] In some embodiments, after the smelting process is completed, the molten steel is further subjected to slag removal to remove impurities.

[0048] In some embodiments, the directional solidification casting step is performed using a mold, the mold temperature is 1450°C~1700°C, the mold is provided with a riser, the casting thickness of the riser is 10mm~25mm, and the mold is placed on a water cooling plate, the water temperature is 20°C~40°C.

[0049] In the step of further regulating directional solidification casting, the casting process conditions used in casting are used to promote the crystal to <100> Directional growth.

[0050] In some embodiments, the steps of directional solidification casting are: pouring the molten steel into a mold, wrapping the mold with an insulation material until it cools to below 800°C, and then dismantling the mold and removing the riser.

[0051] Specifically, the casting is a block with a length of 10-150 mm, a width of 10-150 mm, and a height of 10-150 mm, or a cylinder with a diameter of 10-150 mm and a height of 10-200 mm, or a special-shaped piece of similar size.

[0052] In some embodiments, the uniform heat treatment is performed in a high-temperature furnace. After the treatment, the casting is cooled to below 500° C. in the furnace and then taken out.

[0053] In some embodiments, after the homogenization heat treatment step and before the magnetic field heat treatment step, the step of pre-processing the homogenization heat treated casting is further included, and the pre-processing includes cutting and grinding.

[0054] The purpose of the pre-processing treatment is to select areas with good columnar crystals and facilitate the product to maintain a good orientation during subsequent magnetic field heat treatment, while also improving the consistency of product appearance quality. Cutting and grinding can adopt cutting and grinding processes commonly used in this field without special limitations.

[0055] In some specific examples, the pre-processing steps are as follows: cutting off the bottom portion of the casting close to the cooling plate surface and 3mm to 25mm high, and the top portion (excluding the riser) away from the water-cooling plate surface and 3mm to 30mm high; at the same time, it is necessary to polish according to the required product size specifications, and leave a subsequent processing allowance of 0.2mm to 1.0mm.

[0056] In some embodiments, the step of magnetic field heat treatment includes the following conditions:

[0057] First, solution treat at 1220℃~1280℃ for 10min~60min, then cool to 820℃~950℃ at a rate of 1℃ / s~30℃ / s, then cover with insulation cotton and cool to below 500℃ in a magnetic field greater than 0.3T or keep at 780℃~860℃ for 5min~40min, and finally air cool to room temperature in a magnetic field.

[0058] By regulating the conditions of magnetic field heat treatment, the structural uniformity of AlNiCo permanent magnets can be further improved.

[0059] The thermal insulation cotton can adopt the thermal insulation cotton material commonly used in this field, without any special requirements or restrictions.

[0060] In some embodiments, the tempering and aging treatment step includes the following conditions:

[0061] First, keep it at 620℃~660℃ for 3h~10h, then cool it down to 560℃~600℃ and keep it for 10h~15h, then cool it down to 530℃~570℃ and keep it for 12h-20h, and finally cool it down to below 150℃ with the furnace.

[0062] The tempering and aging treatment adopts a specific three-stage tempering treatment, which can further improve the composition uniformity of the AlNiCo permanent magnet.

[0063] In some of the embodiments, the method further comprises the step of finishing the product after the tempering and aging treatment by grinding and finishing according to the specifications required by the product.

[0064] The finishing process may be a finishing process commonly used in the art without any particular limitation.

[0065] In some embodiments, the composition of the alnico permanent magnet includes, by mass percentage, 5%-10% Al, 8%-15% Ni, 20%-45% Co, 2%-5% Cu, less than 10% Ti, less than 1.5% Nb, less than 0.3% S, less than 0.3% C, less than 0.5% Si, and the balance Fe.

[0066] In some embodiments, the composition of the alnico permanent magnet includes, by mass percentage, 5%-10% Al, 8%-15% Ni, 20%-45% Co, 2%-5% Cu, greater than 0 and less than 10% Ti, greater than 0 and less than 1.5% Nb, 0-0.3% S, 0-0.3% C, 0-0.5% Si, and the balance Fe.

[0067] The mass percentage of Al mentioned above includes 5%, 6%, 7%, 8%, 9%, 10%, and any value between the minimum and maximum values, or a range consisting of any two values.

[0068] The mass percentage of Ni includes 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, and any value between the minimum and maximum values, or a range consisting of any two values.

[0069] The mass percentage of Co mentioned above includes 20%, 25%, 30%, 35%, 40%, 43%, 44%, 45%, and each value between such minimum and maximum values, or a range consisting of any two values.

[0070] The mass percentage of Cu includes 2%, 3%, 4%, 5%, and any value between the minimum and maximum values, or a range consisting of any two values.

[0071] The mass percentage of Ti mentioned above includes 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, and each value between the minimum and maximum values, or a range consisting of any two values.

[0072] The mass percentage of Nb mentioned above includes 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, and each value between the minimum and maximum values, or a range consisting of any two values.

[0073] Another embodiment of the present invention provides an AlNiCo permanent magnet, wherein in the X-ray diffraction pattern of the AlNiCo permanent magnet, the crystals are along <100> orientation; and in any two parts of the alnico permanent magnet, the difference in the percentage of the Al element does not exceed 0.5%, the difference in the percentage of the Ni element does not exceed 1%, the difference in the percentage of the Co element does not exceed 2%, and the difference in the percentage of the Fe element does not exceed 2%.

[0074] Or another embodiment of the present invention provides an AlNiCo permanent magnet, which is prepared by the AlNiCo permanent magnet preparation method as described above.

[0075] The AlNiCo permanent magnet provided by the present invention has a relatively regular structure, high component homogeneity, and low segregation degree of main elements, thereby improving the performance consistency and stability of the AlNiCo permanent magnet.

[0076] In some embodiments, the composition of the alnico permanent magnet further includes Ti and Cu, and in any two parts of the alnico permanent magnet, the difference in the percentage of the Ti element does not exceed 0.5%, and the difference in the percentage of the Cu element does not exceed 0.3%.

[0077] Another aspect of the present invention provides a precision component, which includes the above-mentioned AlNiCo permanent magnet.

[0078] The AlNiCo permanent magnet has a regular structure and high composition uniformity, thereby improving the stability of its performance. It can be used to prepare precision components and effectively improve the stability of the precision components.

[0079] The above-mentioned precision components can be various types of precision components in this field, including but not limited to: components for instruments and meters, components for motors, components for electroacoustic devices, components for magnetic machinery, etc.

[0080] The present invention will be described below with reference to specific embodiments, but the present invention is not limited to the following embodiments. It should be understood that the appended claims summarize the scope of the present invention. Under the guidance of the concept of the present invention, those skilled in the art should realize that certain changes made to the various embodiments of the present invention will be covered by the spirit and scope of the claims of the present invention.

[0081] The following are specific examples.

[0082] Example 1

[0083] (1) Prepare the raw materials according to the following mass percentages: 7.5% Al, 13% Ni, 33.5% Co, 2.8% Cu, 6.7% Ti, 1.0% Nb, 0.25% S, 0.1% C, 0.25% Si and the balance Fe. Place the raw materials in an induction melting furnace for smelting and remove the slag to obtain pure molten steel. Then pour the molten steel into a high-temperature mold: the molten steel temperature is about 1650℃, the mold temperature is about 1600℃, and the mold is placed on a water-cooled plate at a water temperature of 25℃. The outer periphery of the mold is wrapped with aluminum silicate insulation cotton. After the pouring is completed, it is cooled to about 500℃ to obtain a cylindrical casting with a diameter of 68mm and a height of 120mm. The thickness of the riser is about 15mm. Then the mold is dismantled and the riser is removed.

[0084] (2) The casting was subjected to uniform heat treatment: the casting was kept in a high-temperature furnace at 1280℃ for 2.5h, and then slowly cooled to about 300℃ and taken out, and finally cooled to room temperature; then the casting was cut off from the bottom (water-cooling plate end) with a height of 10mm and the top (riser end) with a height of 20mm. The casting was then pre-processed by cutting, grinding and other methods according to the required standard samples to obtain pre-processed samples with a diameter and height of 10.5mm; then magnetic field heat treatment was carried out: first, the casting was heated at 1250℃ and the casting was heated at 1250℃. ℃ for 30 min, then cooled to about 900 ℃ at a rate of 10 ℃ / s, then isothermal treated in a 0.35 T magnetic field for 30 min, and finally placed in a magnetic field and air-cooled to room temperature; then tempering and aging treatment was carried out: first, it was kept at 640 ℃ for 8 h, then cooled to 590 ℃ and kept for 12 h, further cooled to 540 ℃ and kept for 13 h, and finally cooled to below 150 ℃ with the furnace and taken out of the furnace, and finally fine processing was carried out to obtain AlNiCo permanent magnets with a diameter and height of 10 mm.

[0085] (3) The AlNiCo permanent magnet sample was tested by XRD. The X-ray diffraction (XRD) pattern is shown as follows: Figure 1 As shown, the diffraction intensity ratio of its (200) crystal plane to (110) crystal plane is 10.75, which has good <100> Directionally oriented structure.

[0086] Three samples were taken from the upper, middle and lower parts of the AlNiCo permanent magnet in the height direction, and were recorded as: upper-1, upper-2, upper-3, middle-1, middle-2, middle-3, lower-1, lower-2 and lower-3 respectively. The contents of the main component elements of the samples were detected, and the magnetic properties were tested at the same time. The specific test results are shown in Tables 1 and 2 respectively.

[0087] Table 1

[0088]

[0089] Table 2

[0090]

[0091] Comprehensive Table 1~2 and Figure 1 It can be seen that the preparation method of the present invention can obtain an AlNiCo permanent magnet with a relatively regular structure and high composition uniformity, thereby improving the performance stability and consistency of the AlNiCo permanent magnet.

[0092] Example 2

[0093] Example 2 The experimental steps of Example 1 were repeated. It was found that the composition uniformity and magnetic property stability of the prepared AlNiCo permanent magnet were basically consistent with those in the example.

[0094] It can be seen that the preparation method of the present invention has a stable process effect and exhibits good mass production capability.

[0095] Example 3

[0096] The process is basically the same as that in Example 1, except that the uniform heat treatment condition in step (2) is: heat treatment in a high-temperature furnace at 1210°C for 7 hours. The other step conditions are the same as those in Example 1.

[0097] The results show that the prepared AlNiCo permanent magnet has good composition uniformity and magnetic property stability, and is basically consistent with the results of Example 1. The specific test results are shown in Tables 3 and 4.

[0098] Table 3

[0099]

[0100] Table 4

[0101]

[0102] Example 4

[0103] The process is basically the same as that of Example 1, except that the uniform heat treatment condition in step (2) is: heat treatment in a high-temperature furnace at 1340°C for 1.2 h. The other step conditions are the same as those of Example 1.

[0104] The results show that the prepared AlNiCo permanent magnet has good composition uniformity and magnetic property stability, and is basically consistent with the results of Example 1. The test results are shown in Tables 5 and 6.

[0105] Table 5

[0106]

[0107] Table 6

[0108]

[0109] Comparative Example 1

[0110] Comparative Example 1 is basically the same as Example 1, except that uniform heat treatment is not performed in experimental step (2) of Comparative Example 1, and the conditions of other steps are the same as those of Example 1.

[0111] The X-ray diffraction (XRD) pattern of the AlNiCo permanent magnet sample prepared in Comparative Example 1 is as follows: Figure 2 As shown, the analysis shows that: although there is <100> The diffraction intensity ratio of the (200) crystal plane to the (110) crystal plane is relatively low, only 0.61, indicating a poor orientation.

[0112] The results of the content detection of the main component elements and the magnetic properties test of the AlNiCo permanent magnet sample prepared in Comparative Example 1 are shown in Tables 7 and 8, respectively.

[0113] Table 7

[0114]

[0115] Table 8

[0116]

[0117] Compare the data in Tables 1 to 6 and 7 to 8, and compare Figure 1~Figure 2 It can be seen that compared with the technical solution of Comparative Example 1, the structure of the aluminum nickel cobalt permanent magnet obtained by the technical solution of the present invention is more regular and the composition uniformity is higher. For example, the difference in the percentage of Al in any two partial samples in Example 1 does not exceed 0.5%, while the difference in the percentage of Al in Comparative Example 1 reaches 1.11%. Furthermore, the performance stability of the aluminum nickel cobalt permanent magnet obtained by the technical solution of the present invention is higher.

[0118] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0119] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing an AlNiCo permanent magnet, characterized in that: The steps include: Providing raw materials according to the stoichiometric ratio of AlNiCo permanent magnets, and sequentially performing smelting treatment and directional solidification casting on the raw materials to prepare castings; The casting is sequentially subjected to homogenization heat treatment, magnetic field heat treatment and tempering aging treatment to prepare an AlNiCo permanent magnet; Wherein, the homogenization heat treatment is carried out at a temperature of 1200°C to 1350°C; in the step of magnetic field heat treatment, the direction of the magnetic field is in the same direction as the crystal orientation of the casting, and the crystal orientation of the casting is the direction of the crystal along the X-ray diffraction pattern of the casting. <100> orientation.

2. The method for preparing an AlNiCo permanent magnet according to claim 1, wherein: The homogenization heat treatment time is 0.5h~7h; and / or The directional solidification casting step is performed using a mold, the temperature of the mold is 1450°C to 1700°C, the mold is provided with a riser, the pouring thickness of the riser is 10mm to 25mm, and the mold is placed on a water-cooled plate with a water temperature of 20°C to 40°C.

3. The method for preparing an AlNiCo permanent magnet according to claim 2, wherein: The step of magnetic field heat treatment includes the following conditions: First, solution treat at 1220℃~1280℃ for 10min~60min, then cool to 800℃~950℃ at a rate of 1℃ / s~30℃ / s, then cover with insulation cotton and cool to below 500℃ in a magnetic field greater than 0.3T or keep warm at 780℃~860℃ for 5min~40min, and finally air cool to room temperature in a magnetic field.

4. The method for preparing an AlNiCo permanent magnet according to any one of claims 1 to 2, wherein: The steps of the tempering and aging treatment include the following conditions: First, keep it at 620℃~660℃ for 3h~10h, then cool it down to 560℃~600℃ and keep it for 10h~15h, then cool it down to 530℃~570℃ and keep it for 12h-20h, and finally cool it down to below 150℃ with the furnace.

5. The method for preparing an AlNiCo permanent magnet according to any one of claims 1 to 2, wherein: The smelting process is carried out in an induction melting furnace, and the temperature of the obtained molten steel is 1600°C to 1800°C.

6. The method for preparing an AlNiCo permanent magnet according to any one of claims 1 to 2, wherein: After the homogenization heat treatment step and before the magnetic field heat treatment step, the method further includes a step of pre-processing the casting that has undergone the homogenization heat treatment, wherein the pre-processing includes cutting and grinding.

7. The method for preparing an AlNiCo permanent magnet according to any one of claims 1 to 2, wherein: Measured in mass percentage, the composition of the alnico permanent magnet includes: 5%-10% Al, 8%-15% Ni, 20%-45% Co, 2%-5% Cu, less than 10% Ti, less than 1.5% Nb, less than 0.3% S, less than 0.3% C, less than 0.5% Si, and the balance Fe.

8. An AlNiCo permanent magnet, characterized in that: In the X-ray diffraction pattern of the AlNiCo permanent magnet, the crystals along <100> orientation; and in any two parts of the alnico permanent magnet, the difference in the percentage of the Al element does not exceed 0.5%, the difference in the percentage of the Ni element does not exceed 1%, the difference in the percentage of the Co element does not exceed 2%, and the difference in the percentage of the Fe element does not exceed 2%; Alternatively, the AlNiCo permanent magnet is prepared by the method for preparing an AlNiCo permanent magnet according to any one of claims 1 to 7.

9. The AlNiCo permanent magnet according to claim 8, wherein The components of the AlNiCo permanent magnet also include Ti and Cu elements, and in any two parts of the AlNiCo permanent magnet, the difference in the percentage of the Ti element does not exceed 0.5%, and the difference in the percentage of the Cu element does not exceed 0.3%.

10. A precision component, characterized in that: The precision component includes the AlNiCo permanent magnet according to any one of claims 8 to 9.

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