Preparation method of aluminum-nickel-cobalt permanent magnet material and corresponding material

Abstract

The invention relates to the technical field of permanent magnet materials, in particular to a preparation method of an aluminum-nickel-cobalt permanent magnet material and a corresponding material. The preparation method of the aluminum-nickel-cobalt permanent magnet material provided by the invention comprises the following steps: mixing raw materials of the aluminum-nickel-cobalt permanent magnet material, then carrying out vacuum arc melting, then shearing a smelted cast ingot into small blocks, then carrying out vacuum rapid quenching melt-spinning, and then crushing and sieving strips after melt-spinning to obtain the aluminum-nickel-cobalt permanent magnet material. And finally, putting the sieved powder into a graphite grinding tool, and carrying out spark plasma sintering, heat treatment and quenching to obtain the aluminum-nickel-cobalt permanent magnet material. Wherein parameters of spark plasma sintering are as follows: P is equal to 300, I is equal to 300 and D is equal to 1. According to the method, the powder is put into the graphite mold in the sintering stage, the parameters of spark plasma sintering are controlled to be P = 300, I = 300 and D = 1, the voltage during spark plasma sintering is changed into pulse voltage, and rapid densification of the powder is achieved.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet materials technology, specifically to a method for preparing an AlNiCo permanent magnet material and the corresponding material. Background Technology

[0002] AlNiCo permanent magnets, discovered in 1932, have undergone nearly 100 years of development. They possess high time stability, temperature stability, and easy magnetization, with a maximum operating temperature of 550℃. Therefore, AlNiCo magnets are mainly used in electrical energy metering instruments, sensors, permanent magnet motors, and loudspeakers. However, currently, the maximum energy product can only reach about one-third of the theoretical value, primarily due to low coercivity, reaching a maximum of around 2 kOe. Commonly used AlNiCo magnets include AlNiCo5, AlNiCo8, and AlNiCo9, with AlNiCo5 exhibiting high remanence, AlNiCo8 high coercivity, and AlNiCo9 high maximum energy product.

[0003] Sintered AlNiCo magnets are widely used in magnetic products requiring high dimensional accuracy, shape complexity, and appearance quality due to their advantages such as small dimensional tolerances, few surface defects, and ease of fabrication of irregularly shaped components. However, traditional sintered AlNiCo magnets suffer from insufficient hard magnetic properties, especially for typical sintered AlNiCo Class 8 products, where the maximum magnetic energy product can only reach approximately 36 kJ / m². 2 The density of sintered AlNiCo is positively correlated with its remanent magnetization.

[0004] Researchers have conducted extensive work on developing AlNiCo / Rare Earth permanent magnet composite materials. For example, a "Samarium Cobalt / AlNiCo Composite Magnet and its Preparation Method" (patent number CN115547662A) involves mixing cobalt alloy powder of a specific composition with AlNiCo powder, followed by orientation shaping and cold isostatic pressing to obtain a Samarium Cobalt / AlNiCo composite magnet green body. This green body is then subjected to vacuum sintering, solution treatment, and aging treatment to obtain the Samarium Cobalt / AlNiCo composite magnet. However, the magnetic properties of the Samarium Cobalt / AlNiCo composite magnet at a high temperature of 500℃ are significantly lower than those at an operating temperature of 20℃. This is because AlNiCo requires high-temperature solution treatment for densification, but rare earth Sm is prone to volatilization and oxidation during sintering and solution processing. The Sm impurity gas reaction leads to a high internal C and O content, resulting in component segregation and severely affecting the magnetic properties.

[0005] Spark plasma sintering (SPS) is often used to prepare composite materials, but no technical solutions for preparing AlNiCo / rare earth permanent magnet composites via SPS have been reported to date. Because different materials have different optimal sintering temperatures—too high a sintering temperature leads to grain growth, while too low a sintering temperature prevents densification—research on the preparation of AlNiCo / rare earth permanent magnet composites via SPS is limited.

[0006] Therefore, we are exploring the discharge plasma electrospark sintering process to improve the density of AlNiCo under low-temperature sintering conditions and to avoid coarsening of the second-phase grains in the composite material, in order to obtain a high-density AlNiCo composite material. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for preparing AlNiCo permanent magnet materials and the corresponding materials. By placing powder into a graphite mold during the sintering stage and controlling the parameters of the spark plasma sintering to P=300, I=300 and D=1, the voltage during spark plasma sintering is transformed into a pulse voltage, thereby achieving rapid densification of the powder. This method has advantages such as rapid heating, short sintering time, controllable microstructure, energy saving, and environmental protection.

[0008] Therefore, the present invention provides the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing an AlNiCo permanent magnet material in an optional embodiment, comprising the following steps:

[0010] The raw materials of the aluminum-nickel-cobalt permanent magnet material are mixed and then vacuum arc melted. The melted ingot is then cut into small pieces and vacuum fast quenched and spun. The spun strip is then crushed and sieved. Finally, the sieved powder is placed in a graphite mold for discharge plasma sintering, heat treatment and quenching to obtain the aluminum-nickel-cobalt permanent magnet material.

[0011] The parameters for the spark plasma sintering are: P = 300, I = 300 and D = 1.

[0012] Preferably, the discharge plasma sintering pressure is 50-200 MPa; and / or, the discharge plasma sintering time is 5-10 min. The vacuum arc melting temperature is 1400℃, and the time is 20 min; and / or, the vacuum rapid quenching belt spinning speed is 25-28 m / s. The crushing method is selected from one or a combination of grinding crushing or ball milling, the ball milling speed is 400-600 rpm, and the time is 30-60 min; and / or, the average particle size of the sieved powder is below 100 μm. The heat treatment temperature is 1200-1300℃ and the time is 3-10 min; and / or, the quenching method is: holding at 820-840℃ for 12-18 min, then holding at 600-650℃ for 3.5-4.5 h, then holding at 510-550℃ for 7.5-8.5 h, and finally holding at 480-500℃ for 8-10 h.

[0013] Preferably, the vacuum level of the sintering system is controlled to be less than 5 × 10⁻⁶ before and throughout the sintering process. -2 Pa. The temperature of the spark plasma sintering is 600-800℃, and / or, during the spark plasma sintering, the heating rate of the sieved powder from room temperature to the sintering temperature is 30-100℃ / min.

[0014] Preferably, the composition of the AlNiCo permanent magnet material is: Al a Ni b Co c Fe d Cu e Ti f Nb 100-a-b-c-d-e-f Among them, 3≤a≤11, 11≤b≤19, 31≤c≤39, 30≤d≤38, 2≤e≤6, 3≤f≤7, and the rest are Nb and unavoidable impurities.

[0015] Furthermore, the composition of the AlNiCo permanent magnet material is: Al 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 .

[0016] In this invention, the equipment used for spark plasma sintering is model LABOX-1575F.

[0017] Secondly, in an optional embodiment, the present invention provides an AlNiCo permanent magnet material, which is prepared by the above-described preparation method.

[0018] Compared with the prior art, the present invention has one of the following beneficial effects:

[0019] 1. This invention achieves rapid densification of powder by placing powder into a graphite mold during the sintering stage and controlling the parameters of spark plasma sintering to P=300, I=300 and D=1, thereby changing the voltage during spark plasma sintering to a pulse voltage. This method has the advantages of fast heating rate, short sintering time, controllable microstructure, energy saving and environmental protection. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the sintering process of a permanent magnet using spark plasma sintering in Embodiment 1 of the present invention.

[0022] Figure 2 The diagram shows the kinetic curves of the spark plasma sintering process in Embodiment 1 of the present invention, where (a) is the temperature-time curve, (b) is the indenter displacement-time curve, (c) is the voltage-time curve, and (d) is the indenter displacement rate-time curve.

[0023] Figure 3 The diagram shows the kinetic curves of Comparative Example 1 of the present invention during the spark plasma sintering process, where (a) is the temperature-time curve, (b) is the indenter displacement-time curve, (c) is the voltage-time curve, and (d) is the indenter displacement rate-time curve. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0025] The technical solution of the present invention will be described below with reference to embodiments.

[0026] Example 1

[0027] This embodiment provides a component of Al 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2The method for preparing permanent magnet materials includes the following steps:

[0028] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 28m / s. The strip is then shredded, ground in a mortar and pestle, and then ball-milled. The ball milling process is carried out at 500rpm for 40 minutes. The particle size is tested to ensure it is around 10μm. The powder is poured into a graphite mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2 Pa, sintering temperature 700℃, sintering pressure 50MPa, sintering time 6min, P=300, I=300, D=1 (see sintering process) Figure 1-2 The spark plasma sintered magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintered magnet was placed in a muffle furnace and held at 1250℃ for 10 min. Then it was quenched, held at 835℃ for 15 min, held at 600℃ for 4 h, held at 550℃ for 8 h, and held at 500℃ for 9 h.

[0029] Example 2

[0030] This embodiment provides a component of Al 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 The method for preparing permanent magnet materials includes the following steps:

[0031] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 28m / s. The strip is then shredded, ground in a mortar and pestle, and then ball-milled. The ball milling process is carried out at 500rpm for 40 minutes. The particle size is tested to ensure it is around 10μm. The powder is poured into a graphite mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2 The sintering conditions were: Pa, sintering temperature: 800℃, sintering pressure: 50MPa, sintering time: 6min, P = 300, I = 300, D = 1. The spark plasma sintering magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintering magnet was placed in a muffle furnace and held at 1250℃ for 10min, then quenched, held at 835℃ for 15min, held at 600℃ for 4h, held at 550℃ for 8h, and held at 500℃ for 9h.

[0032] Comparative Example 1

[0033] This comparative example provides a component of Al. 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 The method for preparing permanent magnet materials includes the following steps:

[0034] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 25m / s-28m / s. The strip is then shredded and ground in a mortar and pestle, with particle size controlled by a sieve to ensure it is around 10μm. The powder is poured into a graphite mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2 Pa, sintering temperature 700℃, sintering pressure 50MPa, sintering time 6min, P=200, I=200, D=1 (see sintering process) Figure 3 The spark plasma sintered magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintered magnet was placed in a muffle furnace and held at 1250℃ for 10 min. Then it was quenched, held at 835℃ for 15 min, held at 600℃ for 4 h, held at 550℃ for 8 h, and held at 500℃ for 9 h.

[0035] Comparative Example 2

[0036] This comparative example provides a component of Al. 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 The method for preparing permanent magnet materials includes the following steps:

[0037] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 28m / s. The strip is then shredded and ground in a mortar and pestle, with particle size controlled by a sieve to ensure it is around 10μm. The powder is poured into a graphite mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2The sintering conditions were: Pa, sintering temperature: 800℃, sintering pressure: 50MPa, sintering time: 6min, P = 200, I = 200, D = 1. A spark plasma sintering magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintering magnet was placed in a muffle furnace and held at 1250℃ for 10min, then quenched, held at 835℃ for 15min, held at 600℃ for 4h, held at 550℃ for 8h, and held at 500℃ for 9h.

[0038] Comparative Example 3

[0039] This comparative example provides a component of Al. 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 The method for preparing permanent magnet materials includes the following steps:

[0040] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 28m / s. The strip is then shredded, ground in a mortar and pestle, and then ball-milled. The ball milling process is performed at 500rpm for 40 minutes. The particle size is tested to ensure it is around 10μm. The powder is poured into a cemented carbide mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2 The sintering conditions were: Pa, sintering temperature: 800℃, sintering pressure: 50MPa, sintering time: 6min, P = 300, I = 300, D = 1. The spark plasma sintering magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintering magnet was placed in a muffle furnace and held at 1250℃ for 10min, then quenched, held at 835℃ for 15min, held at 600℃ for 4h, held at 550℃ for 8h, and held at 500℃ for 9h.

[0041] Comparative Example 4

[0042] This comparative example provides a component of Al. 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 The method for preparing permanent magnet materials includes the following steps:

[0043] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 28m / s. The strip is then shredded, ground in a mortar and pestle, and then ball-milled. The ball milling process is carried out at 500rpm for 40 minutes. The particle size is tested to ensure it is around 10μm. The powder is poured into a graphite mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2 The sintering conditions were: Pa, sintering temperature: 800℃, sintering pressure: 50MPa, sintering time: 6min, P = 150, I = 150, D = 1. The spark plasma sintering magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintering magnet was placed in a muffle furnace and held at 1250℃ for 10min, then quenched, held at 835℃ for 15min, held at 600℃ for 4h, held at 550℃ for 8h, and held at 500℃ for 9h.

[0044] Comparative Example 5

[0045] This comparative example provides a component of Al. 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 The method for preparing permanent magnet materials includes the following steps:

[0046] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 28m / s. The strip is then shredded, ground in a mortar and pestle, and then ball-milled. The ball milling process is carried out at 500rpm for 40 minutes. The particle size is tested to ensure it is around 10μm. The powder is poured into a graphite mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2 The sintering conditions were: Pa, sintering temperature: 800℃, sintering pressure: 50MPa, sintering time: 6min, P = 180, I = 180, D = 1. The spark plasma sintering magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintering magnet was placed in a muffle furnace and held at 1250℃ for 10min, then quenched, held at 835℃ for 15min, held at 600℃ for 4h, held at 550℃ for 8h, and held at 500℃ for 9h.

[0047] Comparative Example 6

[0048] This comparative example provides a component of Al.5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 The method for preparing permanent magnet materials includes the following steps:

[0049] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 28m / s. The strip is then shredded, ground in a mortar and pestle, and then ball-milled. The ball milling process is carried out at 500rpm for 40 minutes. The particle size is tested to ensure it is around 10μm. The powder is poured into a graphite mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2 The sintering conditions were: Pa, sintering temperature: 800℃, sintering pressure: 50MPa, sintering time: 6min, P = 220, I = 220, D = 1. The spark plasma sintered magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintered magnet was placed in a muffle furnace and held at 1250℃ for 10min, then quenched, held at 835℃ for 15min, held at 600℃ for 4h, held at 550℃ for 8h, and held at 500℃ for 9h.

[0050] Comparative Example 7

[0051] This comparative example provides a component of Al. 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 The method for preparing permanent magnet materials includes the following steps:

[0052] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 28m / s. The strip is then shredded, ground in a mortar and pestle, and then ball-milled. The ball milling process is carried out at 500rpm for 40 minutes. The particle size is tested to ensure it is around 10μm. The powder is poured into a graphite mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2The sintering conditions were: Pa, sintering temperature: 800℃, sintering pressure: 50MPa, sintering time: 6min, P = 250, I = 250, D = 1. The spark plasma sintering magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintering magnet was placed in a muffle furnace and held at 1250℃ for 10min, then quenched, held at 835℃ for 15min, held at 600℃ for 4h, held at 550℃ for 8h, and held at 500℃ for 9h.

[0053] Comparative Example 8

[0054] This comparative example provides a component of Al. 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 The method for preparing permanent magnet materials includes the following steps:

[0055] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 28m / s. The strip is then shredded, ground in a mortar and pestle, and then ball-milled. The ball milling process is carried out at 500rpm for 40 minutes. The particle size is tested to ensure it is around 10μm. The powder is poured into a graphite mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2 The sintering conditions were: Pa, sintering temperature: 800℃, sintering pressure: 50MPa, sintering time: 6min, P = 280, I = 280, D = 1. A spark plasma sintering magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintering magnet was placed in a muffle furnace and held at 1250℃ for 10min, then quenched, held at 835℃ for 15min, held at 600℃ for 4h, held at 550℃ for 8h, and held at 500℃ for 9h.

[0056] Comparative Example 9

[0057] This comparative example provides a component of Al. 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 The method for preparing permanent magnet materials includes the following steps:

[0058] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 28m / s. The strip is then shredded, ground in a mortar and pestle, and then ball-milled. The ball milling process is carried out at 500rpm for 40 minutes. The particle size is tested to ensure it is around 10μm. The powder is poured into a graphite mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2 The sintering conditions were: Pa, sintering temperature: 800℃, sintering pressure: 50MPa, sintering time: 6min, P = 320, I = 320, D = 1. The spark plasma sintering magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintering magnet was placed in a muffle furnace and held at 1250℃ for 10min, then quenched, held at 835℃ for 15min, held at 600℃ for 4h, held at 550℃ for 8h, and held at 500℃ for 9h.

[0059] Comparative Example 10

[0060] This comparative example provides a component of Al. 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 The method for preparing permanent magnet materials includes the following steps:

[0061] According to the composition of the permanent magnet material, the raw materials are mixed and melted in a high-vacuum electric arc melting furnace. The melted ingot is cut into 15g pieces, and each piece is placed in a quartz tube and spun at a speed of 28m / s. The strip is then shredded, ground in a mortar and pestle, and then ball-milled. The ball milling process is carried out at 500rpm for 40 minutes. The particle size is tested to ensure it is around 10μm. The powder is poured into a graphite mold and rapidly sintered using a spark plasma sintering device to obtain the sintered magnet. The vacuum degree before sintering and throughout the sintering process is less than 5×10⁻⁶. -2 The sintering conditions were: Pa, sintering temperature: 800℃, sintering pressure: 50MPa, sintering time: 6min, P = 350, I = 350, D = 1. The spark plasma sintered magnet was sealed inside a quartz tube filled with argon gas. The quartz tube containing the spark plasma sintered magnet was placed in a muffle furnace and held at 1250℃ for 10min, then quenched, held at 835℃ for 15min, held at 600℃ for 4h, held at 550℃ for 8h, and held at 500℃ for 9h.

[0062] Experimental Example

[0063] The density of the permanent magnet materials prepared in Examples 1-2 and Comparative Examples 1-10 was tested using the Archimedes displacement method, and calculated according to the formula:

[0064]

[0065] The test results are shown in Table 1:

[0066] Table 1. Density test results of Examples 1-2 and Comparative Examples 1-10

[0067]

[0068]

[0069] As shown in Table 1, the sintered magnets prepared in Example 2 achieved a high degree of densification of AlNiCo permanent magnets while having the same sintering temperature and time as Comparative Examples 1-10.

[0070] A comparison of Example 1 and Comparative Example 1 revealed that, using two different sintering processes, the first derivative of the indenter displacement in discharge plasma electric spark sintering with voltage and current pulse fluctuations increased and decreased simultaneously with the voltage fluctuations. Upon reaching the specified temperature, the ratio of the displacement increment during the holding phase to the displacement increment during the heating phase was 66.95%, while the ratio of the holding displacement increment to the heating displacement increment for samples with linearly proportional voltage increases was 33.32%. Therefore, the densification effect of pulse voltage fluctuations is better.

[0071] Although the principles of the present invention have been described in detail above with reference to preferred embodiments, those skilled in the art should understand that the above embodiments are merely illustrative explanations of the implementation of the present invention and are not intended to limit the scope of the present invention. The details in the embodiments do not constitute a limitation on the scope of the present invention. Any obvious changes, such as equivalent transformations or simple substitutions, based on the technical solutions of the present invention without departing from the spirit and scope of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing an AlNiCo permanent magnet material, characterized in that, Includes the following steps: The raw materials of the aluminum-nickel-cobalt permanent magnet material are mixed and then vacuum arc melted. The melted ingot is then cut into small pieces and vacuum fast quenched and spun. The spun strip is then crushed and sieved. Finally, the sieved powder is placed in a graphite mold for discharge plasma sintering, heat treatment and quenching to obtain the aluminum-nickel-cobalt permanent magnet material. The parameters for the spark plasma sintering are: P = 300, I = 300 and D = 1.

2. The method for preparing AlNiCo permanent magnet material according to claim 1, characterized in that, The pressure of the discharge plasma sintering is 50-200 MPa; and / or, The discharge plasma sintering time is 5-10 minutes.

3. The method for preparing AlNiCo permanent magnet material according to claim 1, characterized in that, The vacuum arc melting temperature is 1400℃, and the time is 20 min; and / or, The spinning speed of the vacuum rapid quenching strip is 25-28 m / s.

4. The method for preparing AlNiCo permanent magnet material according to claim 1, characterized in that, The crushing method is selected from one or a combination of grinding crushing or ball milling, wherein the ball milling speed is 400-600 rpm and the time is 30-60 min; and / or, The average particle size of the sieved powder is below 100 μm.

5. The method for preparing AlNiCo permanent magnet material according to claim 1, characterized in that, The heat treatment is performed at a temperature of 1200-1300℃ for 3-10 minutes; and / or, The quenching process is as follows: hold at 820-840℃ for 12-18 minutes, then hold at 600-650℃ for 3.5-4.5 hours, then hold at 510-550℃ for 7.5-8.5 hours, and finally hold at 480-500℃ for 8-10 hours.

6. The method for preparing AlNiCo permanent magnet material according to claim 1, characterized in that, Before and throughout the entire sintering process, the vacuum level of the sintering system is controlled to be less than 5 × 10⁻⁶. -2 Pa.

7. The method for preparing AlNiCo permanent magnet material according to claim 1, characterized in that, The temperature of the discharge plasma sintering is 600-800℃; and / or, During the discharge plasma sintering process, the temperature rise rate of the sieved powder from room temperature to the sintering temperature is 30-100℃ / min.

8. The method for preparing AlNiCo permanent magnet material according to claim 1, characterized in that, The composition of the AlNiCo permanent magnet material is: Al a Ni b Co c Fe d Cu e Ti f Nb 100-a-b-c-d-e-f ; Among them, 3≤a≤11, 11≤b≤19, 31≤c≤39, 30≤d≤38, 2≤e≤6, 3≤f≤7, and the rest are Nb and unavoidable impurities.

9. The method for preparing the AlNiCo permanent magnet material according to claim 1, characterized in that, The composition of the AlNiCo permanent magnet material is: Al 5.9 Ni 13.6 Co 36.3 Fe 34.2 Cu 2.8 Ti 6.0 Nb 1.2 .

10. An AlNiCo permanent magnet material, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.

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