Precise forming method for aluminum-nickel-cobalt magnet

Abstract

The invention relates to the technical field of magnet forming, in particular to an aluminum-nickel-cobalt magnet precision forming method which comprises the following steps: S1, raw material preparation: weighing and crushing metal raw materials to obtain primarily crushed aluminum-nickel-cobalt alloy ingots; according to the method, smelting is conducted in the high-vacuum environment lower than 0.1 Pa, planetary ball milling and strict screening are combined, the uniform alloy powder with the particle size ranging from 1 micrometer to 50 micrometers is prepared, the basis of high fluidity and high filling density is provided for follow-up pressing forming, and internal defects caused by uneven powder are effectively avoided. The two-stage numerical control precision pressing process combining pre-pressing and final pressing is adopted, air in powder gaps is eliminated in the pre-pressing stage of 50-100 MPa, pressed blank cracking is prevented, and it is ensured that a magnet green body obtains extremely high size precision and density consistency in the final pressing stage of 200-300 MPa.

Description

Technical Field

[0001] This invention relates to the field of magnet forming technology, and in particular to a precision forming method for AlNiCo magnets. Background Technology

[0002] The field of magnet forming technology is a collection of engineering technologies that involve processing mixtures of magnetic raw materials, such as ferrite, Alnico, SmCo, NdFeB, and various magnetic powders with polymer binders, into permanent magnets or soft magnets with predetermined shapes, sizes, magnetic properties, and structural integrity through specific physical or chemical processes.

[0003] Existing magnet forming technologies suffer from unavoidable volume shrinkage and microstructure segregation during the cooling and solidification of molten metal. This directly leads to large dimensional tolerances, limited shapes, and frequent internal defects such as porosity and looseness, resulting in low yields. In traditional powder pressing processes, simple unidirectional or single-stage pressurization is insufficient to effectively eliminate gas between powder particles, easily forming microcracks and areas of uneven density within the pressed compact. This density gradient is directly transmitted to subsequent sintering stages, causing inconsistent shrinkage rates in different parts of the magnet, resulting in large fluctuations in the final product's dimensions. Consequently, the magnetic properties exhibit significant positional dependence, failing to meet the requirements of high-end applications for magnetic field uniformity. Therefore, improvements are needed. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and to propose a precision forming method for AlNiCo magnets.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for precision forming of AlNiCo magnets, comprising the following steps: S1, Raw material preparation: Weigh the metal raw material and crush it to obtain pre-crushed aluminum-nickel-cobalt alloy ingots; S2, Powder processing: The pre-crushed aluminum-nickel-cobalt alloy ingots are loaded into a grinding jar and ground to obtain aluminum-nickel-cobalt alloy powder with controlled particle size. S3, Lubricant mixing: Weigh the aluminum-nickel-cobalt alloy powder with controlled particle size, add lubricant according to the weighing result, and obtain a uniformly mixed alloy powder containing lubricant. S4, Precision pressing: The uniformly mixed alloy powder containing lubricant is loaded into the alloy mold cavity and pressed to obtain a precision-formed AlNiCo magnet green blank. S5, heat treatment: the precision-formed aluminum-nickel-cobalt magnet blank is subjected to aging treatment to obtain the finished aluminum-nickel-cobalt magnet.

[0006] Preferably, step S1 specifically includes: Weigh the metal raw materials, with the following weight ratio: aluminum 10-15%, nickel 18-20%, cobalt 24-26%, copper 3-6%, titanium 1-3%, and iron 44-30%. Put the weighed metal raw materials into a mixer and mix for 40-60 minutes at a speed of 15-25 RPM to obtain a uniform metal mixture. Transfer the uniform metal mixture to a crucible, seal the furnace body, and evacuate the furnace until the pressure inside the furnace is below 0.1 Pa. Then raise the furnace temperature to 1600-1750℃ at a rate of 10-15℃ / min and hold for 1-2 hours. Turn off the heating and pour the alloy melt into a preheated metal mold. Cool to room temperature under argon protection. Crush the cooled alloy ingot to obtain pre-crushed aluminum-nickel-cobalt alloy ingot blocks.

[0007] Preferably, step S2 specifically comprises: The pre-crushed aluminum-nickel-cobalt alloy ingots are loaded into a grinding jar, and grinding balls are added at a ball-to-material weight ratio of 15:1. The grinding jar is sealed, and the planetary ball mill is set to an orbital speed of 150-250 RPM and a rotational speed of 300-400 RPM. The grinding is carried out continuously for 24-48 hours. After grinding, the resulting powder is transferred to a vibrating screen to collect powder with a particle size between 1-50 micrometers, thus obtaining aluminum-nickel-cobalt alloy powder with controlled particle size.

[0008] Preferably, step S3 specifically comprises: The particle size-controlled AlNiCo alloy powder is weighed, and zinc stearate with a weight ratio of 1%-3% is calculated and weighed as a lubricant based on the total weight. The weighed zinc stearate and the particle size-controlled AlNiCo alloy powder are added together into a three-dimensional motion mixer to mix and obtain a uniformly mixed alloy powder containing lubricant.

[0009] Preferably, step S4 specifically comprises: The uniformly mixed alloy powder containing lubricant is loaded into the alloy mold cavity and subjected to two-stage pressing. The first stage is pre-pressing, in which the pressure is increased to 50-100MPa at a pressurization rate of 10-20MPa / s and held for 3-5 seconds to expel air between the powder particles and allow the powder to initially take shape. The second stage is final pressing, in which the pressure is rapidly increased to 200-300MPa at a pressurization rate of 20-30MPa / s and held for 5-15 seconds to obtain a precision-formed AlNiCo magnet green blank.

[0010] Preferably, step S5 specifically includes: The precision-formed AlNiCo magnet green blank is placed on a sintering fixture and fed into a vacuum atmosphere furnace with an integrated electromagnetic field. After the furnace is evacuated, argon gas is introduced as a protective atmosphere. The temperature is raised to 1200-1300℃ at a rate of 5-10℃ / min and held for 1-3 hours to densify the magnet green blank and form a uniform solid solution. The magnet is cooled from the solid solution temperature at a rate of 1-5℃ / s. A magnetic field of 200-400kA / m is applied before and after passing the Curie temperature until it is cooled to below 600℃. The magnet is then subjected to a first aging treatment at 600-650℃ for 4-8 hours, and then cooled to 550-600℃ for a second aging treatment for 8-16 hours to precipitate the magnetic phase, thus obtaining the finished AlNiCo magnet.

[0011] Preferably, the grinding jar is filled with argon gas to a pressure of 0.1-0.2 MPa.

[0012] Preferably, the three-dimensional motion mixer mixes at a speed of 20-50 RPM for 30-60 minutes to obtain a uniformly mixed alloy powder containing lubricant.

[0013] Compared with the prior art, the advantages and positive effects of the present invention are as follows: This invention utilizes a high vacuum environment (below 0.1 Pa) for melting, combined with planetary ball milling and rigorous sieving to prepare uniform alloy powder with a particle size distribution of 1-50 micrometers. This provides a foundation for high fluidity and high filling density in subsequent pressing, effectively avoiding internal defects caused by powder inhomogeneity. The two-stage CNC precision pressing process, combining pre-pressing and final pressing, not only eliminates air from the powder gaps during the 50-100 MPa pre-pressing stage, preventing cracking of the pressed blank, but also ensures extremely high dimensional accuracy and density consistency of the magnet green blank during the 200-300 MPa final pressing stage. Finally, a multi-stage heat treatment was performed in a vacuum atmosphere furnace with an integrated magnetic field. Through solution sintering at 1200-1300℃, orientation annealing with a strong magnetic field near the Curie point, and two-stage aging at 600-650℃ and 550-600℃, the microstructure of the magnet was controlled, and highly anisotropic magnetic domains were induced to form. This improved the remanence, coercivity, and energy product of the AlNiCo magnet while ensuring dimensional accuracy, and ensured a high degree of consistency in performance between batches of products. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the steps of the present invention. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0016] Example 1, please refer to Figure 1 This invention provides a technical solution: a method for precision forming of AlNiCo magnets, comprising the following steps: S1, Raw material preparation: Weigh the metal raw material and crush it to obtain pre-crushed aluminum-nickel-cobalt alloy ingots; S2, Powder processing: The pre-crushed aluminum-nickel-cobalt alloy ingots are loaded into a grinding jar and ground to obtain aluminum-nickel-cobalt alloy powder with controlled particle size. S3, Lubricant mixing: Weigh the aluminum-nickel-cobalt alloy powder with controlled particle size, add lubricant according to the weighing result, and obtain a uniformly mixed alloy powder containing lubricant. S4, precision pressing: uniformly mixed alloy powder containing lubricant is loaded into the alloy mold cavity and pressed to obtain a precision-formed AlNiCo magnet blank. S5, heat treatment, involves aging the precision-formed AlNiCo magnet blank to obtain the finished AlNiCo magnet.

[0017] In this embodiment, step S1 specifically includes: Weigh the metal raw materials, with the following weight ratio: aluminum 10%, nickel 18%, cobalt 24%, copper 3%, titanium 1%, and iron 44%. Put the weighed metal raw materials into a mixer and mix for 60 minutes at a speed of 25 RPM to obtain a uniform metal mixture. Transfer the uniform metal mixture to a crucible, seal the furnace body, and evacuate until the pressure inside the furnace is below 0.1 Pa. Then raise the furnace temperature to 1750℃ at a rate of 15℃ / min and hold for 2 hours. Turn off the heating and pour the alloy melt into a preheated metal mold. Cool to room temperature under argon protection. Crush the cooled alloy ingot to obtain pre-crushed aluminum-nickel-cobalt alloy ingot blocks.

[0018] In this embodiment, step S2 specifically includes: The pre-crushed aluminum-nickel-cobalt alloy ingots were loaded into a grinding jar, and grinding balls were added at a ball-to-material weight ratio of 15:1. The grinding jar was sealed, and the planetary ball mill was set to an orbital speed of 250 RPM and a rotational speed of 300 RPM. The grinding was carried out continuously for 48 hours. After the grinding was completed, the resulting powder was transferred to a vibrating screen to collect powder with a particle size between 1 and 50 micrometers, thus obtaining aluminum-nickel-cobalt alloy powder with controlled particle size.

[0019] In this embodiment, step S3 specifically includes: Weigh the aluminum-nickel-cobalt alloy powder with controlled particle size, and calculate and weigh 3% zinc stearate as a lubricant based on the total weight. Add the weighed zinc stearate and the aluminum-nickel-cobalt alloy powder with controlled particle size together into a three-dimensional motion mixer to mix and obtain a uniformly mixed alloy powder containing lubricant.

[0020] In this embodiment, step S4 specifically includes: The uniformly mixed alloy powder containing lubricant is loaded into the alloy mold cavity and subjected to two-stage pressing. The first stage is pre-pressing, in which the pressure is increased to 50 MPa at a pressurization rate of 20 MPa / s and held for 5 seconds to expel air between the powder particles and allow the powder to be initially shaped. The second stage is final pressing, in which the pressure is rapidly increased to 200 MPa at a pressurization rate of 30 MPa / s and held for 15 seconds to obtain a precision-shaped AlNiCo magnet green blank.

[0021] In this embodiment, step S5 specifically includes: Precision-formed AlNiCo magnet green blanks are placed on sintering fixtures and fed into a vacuum atmosphere furnace with an integrated electromagnetic field. After the furnace is evacuated, argon gas is introduced as a protective atmosphere. The temperature is raised to 1200°C at a rate of 10°C / min and held for 3 hours to densify the magnet green blanks and form a uniform solid solution. The magnets are cooled from the solid solution temperature at a rate of 5°C / s. A magnetic field of 400 kA / m is applied before and after passing the Curie temperature until the temperature drops below 600°C. The magnets are then subjected to a first aging treatment at 650°C for 8 hours, followed by a second aging treatment at 550°C for 16 hours to precipitate the magnetic phase, thus obtaining the finished AlNiCo magnets.

[0022] In this embodiment, the grinding jar is filled with argon gas to a pressure of 0.2 MPa.

[0023] In this embodiment, the three-dimensional motion mixer is used to mix for 30 minutes at a speed of 50 RPM to obtain a uniformly mixed alloy powder containing lubricant.

[0024] Example 2, please refer to Figure 1 This invention provides a technical solution: a method for precision forming of AlNiCo magnets, comprising the following steps: S1, Raw material preparation: Weigh the metal raw material and crush it to obtain pre-crushed aluminum-nickel-cobalt alloy ingots; S2, Powder processing: The pre-crushed aluminum-nickel-cobalt alloy ingots are loaded into a grinding jar and ground to obtain aluminum-nickel-cobalt alloy powder with controlled particle size. S3, Lubricant mixing: Weigh the aluminum-nickel-cobalt alloy powder with controlled particle size, add lubricant according to the weighing result, and obtain a uniformly mixed alloy powder containing lubricant. S4, precision pressing: uniformly mixed alloy powder containing lubricant is loaded into the alloy mold cavity and pressed to obtain a precision-formed AlNiCo magnet blank. S5, heat treatment, involves aging the precision-formed AlNiCo magnet blank to obtain the finished AlNiCo magnet.

[0025] In this embodiment, step S1 specifically includes: Weigh the metal raw materials, with the following weight ratio: aluminum 15%, nickel 20%, cobalt 26%, copper 6%, titanium 3%, and iron 30%. Put the weighed metal raw materials into a mixer and mix for 60 minutes at a speed of 25 RPM to obtain a uniform metal mixture. Transfer the uniform metal mixture to a crucible, seal the furnace body, and evacuate until the pressure inside the furnace is below 0.1 Pa. Then raise the furnace temperature to 1750℃ at a rate of 10℃ / min and hold for 2 hours. Turn off the heating and pour the alloy melt into a preheated metal mold. Cool to room temperature under argon protection. Crush the cooled alloy ingot to obtain pre-crushed aluminum-nickel-cobalt alloy ingot blocks.

[0026] In this embodiment, step S2 specifically includes: The pre-crushed aluminum-nickel-cobalt alloy ingots were loaded into a grinding jar, and grinding balls were added at a ball-to-material weight ratio of 15:1. The grinding jar was sealed, and the planetary ball mill was set to an orbital speed of 250 RPM and a rotational speed of 300 RPM. The grinding was carried out continuously for 48 hours. After the grinding was completed, the resulting powder was transferred to a vibrating screen to collect powder with a particle size between 1 and 50 micrometers, thus obtaining aluminum-nickel-cobalt alloy powder with controlled particle size.

[0027] In this embodiment, step S3 specifically includes: Weigh the aluminum-nickel-cobalt alloy powder with controlled particle size, and calculate and weigh 2% zinc stearate as a lubricant based on the total weight. Add the weighed zinc stearate and the aluminum-nickel-cobalt alloy powder with controlled particle size together into a three-dimensional motion mixer to mix and obtain a uniformly mixed alloy powder containing lubricant.

[0028] In this embodiment, step S4 specifically includes: The uniformly mixed alloy powder containing lubricant is loaded into the alloy mold cavity and subjected to two-stage pressing. The first stage is pre-pressing, in which the pressure is increased to 50 MPa at a pressurization rate of 15 MPa / s and held for 4 seconds to expel air between the powder particles and allow the powder to be initially shaped. The second stage is final pressing, in which the pressure is rapidly increased to 300 MPa at a pressurization rate of 30 MPa / s and held for 15 seconds to obtain a precision-shaped AlNiCo magnet blank.

[0029] In this embodiment, step S5 specifically includes: Precision-formed AlNiCo magnet green blanks are placed on sintering fixtures and fed into a vacuum atmosphere furnace with an integrated electromagnetic field. After the furnace is evacuated, argon gas is introduced as a protective atmosphere. The temperature is raised to 1200°C at a rate of 10°C / min and held for 3 hours to densify the magnet green blanks and form a uniform solid solution. The magnets are cooled from the solid solution temperature at a rate of 5°C / s. A magnetic field of 400 kA / m is applied before and after passing the Curie temperature until the temperature drops below 600°C. The magnets are then subjected to a first aging treatment at 650°C for 8 hours, followed by a second aging treatment at 550°C for 12 hours to precipitate the magnetic phase, thus obtaining the finished AlNiCo magnet.

[0030] In this embodiment, the grinding jar is filled with argon gas to a pressure of 0.1 MPa.

[0031] In this embodiment, the three-dimensional motion mixer is used to mix for 60 minutes at a speed of 50 RPM to obtain a uniformly mixed alloy powder containing lubricant.

[0032] Experimental methods: 1. Test methods for remanence (Br), intrinsic coercivity (Hcj), and maximum energy product ((BH)max). The determination of remanence, intrinsic coercivity, and maximum energy product was carried out in accordance with GB / T3217-2013. The experimental equipment used was the NIM-2000H permanent magnet material measuring device (or an equivalent BH tester / hysteresis loop apparatus).

[0033] Sample Preparation: Select representative samples from the prepared AlNiCo magnets. The sample size should meet the requirements of the testing equipment, typically in the form of regular cylinders or cubes. Before testing, ensure the sample surface is clean and free of contaminants. If the sample may have been partially magnetized or demagnetized during processing or handling, it must first be placed in the electromagnet of the testing equipment and saturated with a magnetic field much larger than its coercivity (e.g., for AlNiCo5, a magnetization field of 300-500 kA / m is typically required) to ensure all magnetic domains are aligned.

[0034] Testing environment: Experiments are conducted at room temperature (typically 20±5℃) and relative humidity below 65%. The testing equipment must be preheated and stabilized, and calibrated according to the instrument's instruction manual to ensure measurement accuracy.

[0035] Experimental Procedure: Place the sample to be tested in the sample chamber or fixture of the testing equipment, ensuring that the center of the sample is aligned with the center of the measuring coil. Start the testing program; the equipment will automatically apply a positive saturation magnetic field, then gradually decrease the magnetic field to zero, then increase the magnetic field in the opposite direction to negative saturation, and finally decrease the reverse magnetic field to zero and return to positive saturation, thereby obtaining a complete hysteresis loop or at least a demagnetization curve in the second quadrant.

[0036] Data acquisition and calculation: Remanence (Br): The magnetic induction intensity exhibited by the sample when the applied magnetic field drops from saturation to zero is called remanence. The instrument reads this value directly from the hysteresis loop.

[0037] Intrinsic coercivity (Hcj): Under the influence of a reverse magnetic field, the intensity of the reverse magnetic field corresponding to the point where the magnetic polarization (J) of the sample drops to zero is the intrinsic coercivity. The instrument reads this value directly from the JH curve.

[0038] Maximum magnetic energy product ((BH)max): In the second quadrant of the demagnetization curve, the product (absolute value) of the magnetic induction intensity B and the corresponding reverse magnetic field intensity H has a maximum value, which is the maximum magnetic energy product. The instrument software will automatically calculate and display this value. Record all test data. Test at least 3-5 samples per batch and take the average value as the final result.

[0039] 2. Density (ρ) Test Method: The density is determined using Archimedes' displacement method, based on the immersion method principle in standard GB / T1033.1-2008. The experimental equipment mainly includes an electronic analytical balance with an accuracy of 0.0001g, and a density measuring component (including a basket, beaker, and thermometer) or a self-made suspension device.

[0040] Sample preparation: Select 3-5 representative samples from the prepared AlNiCo magnets. Clean the sample surface with anhydrous ethanol to remove oil and impurities, then wipe dry with filter paper or dry in an oven at 60-80℃ for 30 minutes until constant weight, ensuring that the sample is completely dry inside and out.

[0041] Test environment: The experiment was conducted at room temperature (e.g., 20±2℃). The water temperature was recorded during the experiment to determine the density of pure water at that temperature. The impregnation liquid used was typically freshly boiled and cooled distilled water or deionized water to eliminate the influence of dissolved air.

[0042] Experimental steps: First, accurately weigh the mass of the dried sample in air on an electronic balance and record it as m1.

[0043] Then, completely immerse the sample in distilled water at a known temperature (note that the sample should not touch the beaker wall or bottom, and no air bubbles should adhere to the sample surface), and weigh the suspended mass (apparent weight) of the sample in the water, and record it as m2.

[0044] Record the water temperature T at the time of measurement, and look up the density ρ_water of pure water at that temperature.

[0045] Data calculation: The sample volume V is calculated as follows: V = (m1 - m2) / ρ_water. Here, (m1 - m2) represents the equivalent mass of liquid due to the buoyancy force on the sample. Dividing this mass by the liquid density gives the volume of liquid displaced by the sample, which is the sample volume.

[0046] The density ρ of the sample is calculated as follows: ρ = m1 / V. Dividing the mass m1 in the air by the calculated sample volume V yields the sample density. Multiple samples are measured, and the average value is taken as the final density result.

[0047] 3. Dimensional tolerance testing methods The determination of dimensional tolerances aims to evaluate the consistency between the actual dimensions of the finished magnet and its design nominal dimensions. The experimental equipment is selected according to the geometry and precision requirements of the magnet. Commonly used tools include digital vernier calipers (accuracy 0.01 mm), outside micrometers (accuracy 0.001 mm), or higher precision measuring instruments such as 2D image measuring instruments and coordinate measuring machines (CMMs).

[0048] Sample Preparation: Randomly select a sufficient number of samples, such as 10-20 pieces, from the same batch of AlNiCo finished magnets to ensure statistical representativeness. Ensure the sample surface is clean and free of burrs, oil stains, or other factors that may affect the measurement. Review the product design drawings to clarify the nominal values ​​of each key dimension.

[0049] Testing environment: Measurements should be performed in a clean, vibration-free environment with minimal temperature fluctuations (e.g., 20±2℃). Measuring instruments should be calibrated before use and operated correctly according to their operating procedures.

[0050] Experimental steps: For each sample, select the key dimensions marked on the drawing for measurement, such as length, width, thickness, outer diameter, inner diameter, and hole spacing.

[0051] For each critical dimension, measurements should be taken at at least three different locations on the sample to assess dimensional uniformity. For example, when measuring the diameter of a cylinder, measurements should be taken at different axial locations and in different radial directions.

[0052] Record the actual value of each measurement.

[0053] Data processing and tolerance determination: Calculate the average measured value for each critical dimension of each sample.

[0054] The average measured value of each sample is compared with the nominal value of that size, and the deviation is calculated.

[0055] The maximum and minimum deviations of all samples at this critical dimension are statistically analyzed. Dimensional tolerances are typically expressed as the allowable range of variation over the nominal size, for example, ±X mm. This is determined by identifying the maximum upper deviation (the largest positive value minus the nominal value) and the maximum lower deviation (the largest negative value minus the nominal value, or the largest positive value minus the nominal value) for all samples. If the upper and lower deviations are symmetrical, the tolerance is ± (the absolute value of the maximum deviation); if they are asymmetrical, they are expressed as +X / -Y respectively. In the table, we uniformly use ± to represent the symmetrical tolerance range. For ±0.0X mm in this example, it means that the difference between the maximum measured size and the nominal size does not exceed +0.0X mm, and the difference between the minimum measured size and the nominal size is not less than -0.0X mm.

[0056] 4. Surface roughness (Ra) test method Surface roughness (Ra) is measured to evaluate the smoothness of a magnet surface. The experimental equipment typically consists of a contact surface roughness meter or a non-contact optical profilometer. This method uses a contact surface roughness meter as an example, referring to GB / T3505-2009 and GB / T6062-2009.

[0057] Sample preparation: Select 3-5 samples from the prepared AlNiCo magnets. The surface to be tested must be clean, dry, and free from oil, dust, rust, and obvious scratches, burrs, or other defects, as these defects may affect the measurement results or damage the stylus. Select a representative area of ​​the surface to be tested.

[0058] Test Environment and Equipment Setup: The experiment was conducted in a standard room temperature (20±5℃), with suitable humidity and no significant vibration or electromagnetic interference. Based on the instrument manual and the expected roughness of the surface being measured, appropriate stylus radius, sampling length (the evaluation length is typically 5 sampling lengths), filtering method (e.g., Gaussian filtering), and measurement speed were selected. The roughness meter was calibrated using a standard sample block.

[0059] Experimental steps: Place the sample to be tested firmly on the working platform of the roughness tester, ensuring that the surface being tested is approximately perpendicular to the scanning direction of the stylus.

[0060] Adjust the stylus so that it gently contacts the surface being measured, and apply an appropriate measuring force.

[0061] The measurement program is started, and the stylus moves at a constant speed along the preset sampling length on the surface being measured. The sensor converts the tiny displacement of the stylus perpendicular to the surface into an electrical signal, which is amplified and processed to calculate the surface roughness parameters.

[0062] Measurements should be taken at at least three different locations on each sample. If the sample surface has a texture in a specific direction (such as a grinding texture), the roughness should be measured parallel to and perpendicular to the texture direction, or measured in the direction specified in the requirements.

[0063] Data acquisition and calculation: The instrument automatically calculates and displays the profile arithmetic mean deviation Ra value. Ra is defined as the arithmetic mean of the absolute values ​​of profile deviations over a sampling length.

[0064] Record the Ra value at each measurement location. Calculate the average Ra value for each sample, and then calculate the overall average Ra value for all tested samples as the final result. If there are special textures, report the Ra values ​​for different directions separately.

[0065] Experiments were conducted on the finished materials prepared in Examples 1-2, wherein Comparative Example 1 is the magnet prepared in Example 1 of Chinese Invention Patent Publication No. CN115547662A. The experimental results are as follows: Table 1 Performance Test Data As shown in Table 1, Examples 1-2 exhibit superior overall magnetic properties and molding precision compared to Comparative Example 1. This comprehensive improvement stems from the synergistic effect of the various process steps in this invention. Regarding magnetic properties, the core lies in the unique magnetic field heat treatment and dual-stage aging process in step S5. By applying a magnetic field to induce preferred orientation of the magnetic phase and utilizing dual-stage aging to precisely control the microstructure, remanence, intrinsic coercivity, and maximum energy product are synergistically enhanced. This effect is further facilitated by grinding in an inert atmosphere in step S2, effectively preventing powder oxidation and providing a pure raw material foundation for maximizing the efficiency of subsequent heat treatment. Simultaneously, in terms of precision molding, the two-stage pressing process in S4, the optimized particle size distribution in S2, and the uniform lubrication in S3 form a key synergy: optimized powder conditions (S2, S3) ensure uniform transmission of pressing force, while the two-stage pressing (S4) achieves degassing and high densification, working together to produce a green blank with fewer defects and higher density. This directly results in the final magnet having higher density, stricter dimensional tolerances, and lower surface roughness after sintering. Therefore, it is the synergistic effect of these interconnected technical features, from powder preparation to precision pressing and heat treatment, that proves the advantages of this invention in improving the performance and forming precision of AlNiCo magnets.

[0066] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for precision forming of AlNiCo magnets, characterized in that, Includes the following steps: S1, Raw material preparation: Weigh the metal raw material and crush it to obtain pre-crushed aluminum-nickel-cobalt alloy ingots; S2, Powder processing: The pre-crushed aluminum-nickel-cobalt alloy ingots are loaded into a grinding jar and ground to obtain aluminum-nickel-cobalt alloy powder with controlled particle size. S3, Lubricant mixing: Weigh the aluminum-nickel-cobalt alloy powder with controlled particle size, add lubricant according to the weighing result, and obtain a uniformly mixed alloy powder containing lubricant. S4, Precision pressing: The uniformly mixed alloy powder containing lubricant is loaded into the alloy mold cavity and pressed to obtain a precision-formed AlNiCo magnet green blank. S5, heat treatment: the precision-formed aluminum-nickel-cobalt magnet blank is subjected to aging treatment to obtain the finished aluminum-nickel-cobalt magnet.

2. The precision forming method for AlNiCo magnets according to claim 1, characterized in that, The specific steps of S1 are as follows: Weigh the metal raw materials, with the following weight ratio: aluminum 10-15%, nickel 18-20%, cobalt 24-26%, copper 3-6%, titanium 1-3%, and iron 44-30%. Put the weighed metal raw materials into a mixer and mix for 40-60 minutes at a speed of 15-25 RPM to obtain a uniform metal mixture. Transfer the uniform metal mixture to a crucible, seal the furnace body, and evacuate the furnace until the pressure inside the furnace is below 0.1 Pa. Then raise the furnace temperature to 1600-1750℃ at a rate of 10-15℃ / min and hold it for 1-2 hours. Turn off the heating and pour the alloy melt into a preheated metal mold. Cool to room temperature under argon protection. Crush the cooled alloy ingot to obtain pre-crushed aluminum-nickel-cobalt alloy ingot blocks.

3. The precision forming method for AlNiCo magnets according to claim 1, characterized in that, The S2 step is specifically as follows: The pre-crushed aluminum-nickel-cobalt alloy ingots are loaded into a grinding jar, and grinding balls are added at a ball-to-material weight ratio of 15:

1. The grinding jar is sealed, and the planetary ball mill is set to an orbital speed of 150-250 RPM and a rotational speed of 300-400 RPM. The grinding is carried out continuously for 24-48 hours. After grinding, the resulting powder is transferred to a vibrating screen to collect powder with a particle size between 1-50 micrometers, thus obtaining aluminum-nickel-cobalt alloy powder with controlled particle size.

4. The precision forming method for AlNiCo magnets according to claim 1, characterized in that, The S3 step is specifically as follows: The particle size-controlled AlNiCo alloy powder is weighed, and zinc stearate with a weight ratio of 1%-3% is calculated and weighed as a lubricant based on the total weight. The weighed zinc stearate and the particle size-controlled AlNiCo alloy powder are added together into a three-dimensional motion mixer to mix and obtain a uniformly mixed alloy powder containing lubricant.

5. The precision forming method for AlNiCo magnets according to claim 1, characterized in that, The S4 step is specifically as follows: The uniformly mixed alloy powder containing lubricant is loaded into the alloy mold cavity and subjected to two-stage pressing. The first stage is pre-pressing, in which the pressure is increased to 50-100MPa at a pressurization rate of 10-20MPa / s and held for 3-5 seconds to expel air between the powder particles and allow the powder to initially take shape. The second stage is final pressing, in which the pressure is rapidly increased to 200-300MPa at a pressurization rate of 20-30MPa / s and held for 5-15 seconds to obtain a precision-formed AlNiCo magnet green blank.

6. The precision forming method for AlNiCo magnets according to claim 1, characterized in that, The S5 step is specifically as follows: The precision-formed AlNiCo magnet green blank is placed on a sintering fixture and fed into a vacuum atmosphere furnace with an integrated electromagnetic field. After the furnace is evacuated, argon gas is introduced as a protective atmosphere. The temperature is raised to 1200-1300℃ at a rate of 5-10℃ / min and held for 1-3 hours to densify the magnet green blank and form a uniform solid solution. The magnet is cooled from the solid solution temperature at a rate of 1-5℃ / s. A magnetic field of 200-400kA / m is applied before and after passing the Curie temperature until it is cooled to below 600℃. The magnet is then subjected to a first aging treatment at 600-650℃ for 4-8 hours, and then cooled to 550-600℃ for a second aging treatment for 8-16 hours to precipitate the magnetic phase, thus obtaining the finished AlNiCo magnet.

7. The precision forming method for AlNiCo magnets according to claim 3, characterized in that, Argon gas is filled into the grinding jar to a pressure of 0.1-0.2 MPa.

8. The precision forming method for AlNiCo magnets according to claim 4, characterized in that, The three-dimensional motion mixer mixes at a speed of 20-50 RPM for 30-60 minutes to obtain a uniformly mixed alloy powder containing lubricant.

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