AlNiCo permanent magnet alloy, its preparation method and application

Abstract

This invention relates to an AlNiCo permanent magnet alloy, its preparation method, and its applications. The AlNiCo permanent magnet alloy comprises the following elements by mass fraction: 30%-35% Co, 10%-15% Ni, 5%-8% Al, 4%-7% Ti, 2%-4% Cu, 0-2% Nb, less than 4% rare earth elements, and the balance Fe. The AlNiCo permanent magnet alloy has a nanoscale dual-phase structure, comprising a FeCo-rich phase and an AlNi-rich phase, which are periodically arranged alternately along the magnetic field direction. Some of the rare earth elements are segregated in the FeCo-rich phase, while others form nanoscale first rare earth compounds in the nanoscale dual-phase structure. The AlNiCo permanent magnet alloy exhibits both high coercivity and temperature stability.

Description

Technical Field

[0001] This invention relates to the technical field of permanent magnet materials, and in particular to an AlNiCo permanent magnet alloy, its preparation method, and its application. Background Technology

[0002] AlNiCo permanent magnet alloys, due to their high remanence and good temperature stability, have long been used in temperature-sensitive fields such as relays, accelerometers, micromotors, and loudspeakers. They are also the most widely used permanent magnet material in high-precision instruments used in defense, where their magnetic properties and stability largely determine the measurement accuracy. However, traditional AlNiCo permanent magnet alloys still suffer from limitations in simultaneously improving coercivity and temperature stability, making it difficult to meet the development requirements of high-precision, high-energy-consumption permanent magnet motors and other magnetic devices. Summary of the Invention

[0003] Based on this, it is necessary to provide an AlNiCo permanent magnet alloy, its preparation method, and its application to address the above problems. The AlNiCo permanent magnet alloy has a nanoscale dual-phase structure with FeCo-rich and AlNi-rich phases arranged periodically and alternately. Some rare earth elements are segregated in the FeCo-rich phase, and some rare earth elements form nanoscale first rare earth compounds in the nanoscale dual-phase structure, so that the AlNiCo permanent magnet alloy has both high coercivity and temperature stability.

[0004] An AlNiCo permanent magnet alloy comprises the following constituent elements by mass fraction: 30%-35% Co, 10%-15% Ni, 5%-8% Al, 4%-7% Ti, 2%-4% Cu, 0-2% Nb, less than 4% rare earth elements, and the balance Fe.

[0005] The AlNiCo permanent magnet alloy has a nanoscale dual-phase structure, which includes a FeCo-rich phase and an AlNi-rich phase. The FeCo-rich phase and the AlNi-rich phase are arranged periodically and alternately along the magnetic field direction. Some of the rare earth elements are distributed in the FeCo-rich phase, and some of the rare earth elements form nanoscale first rare earth compounds in the nanoscale dual-phase structure.

[0006] In one embodiment, the AlNiCo permanent magnet alloy comprises the following constituent elements by mass fraction: 30%-35% Co, 10%-15% Ni, 5%-8% Al, 4%-7% Ti, 2%-4% Cu, 0-2% Nb, less than or equal to 3.5% rare earth elements, and the balance Fe.

[0007] In one embodiment, the size of the first rare earth compound is 80nm-120nm.

[0008] In one embodiment, the first rare earth compound mainly comprises Co and rare earth elements.

[0009] In one embodiment, the remaining portion of the rare earth elements forms a micron-sized second rare earth compound in the grain boundaries of the AlNiCo permanent magnet alloy.

[0010] In one embodiment, the second rare earth compound mainly comprises Fe, Co and rare earth elements.

[0011] In one embodiment, the FeCo-rich phase is a long rod-shaped structure, the radial direction of which is parallel to the direction of the magnetic field, and the diameter of the long rod-shaped structure is 20nm-40nm, and the length is ≥260nm.

[0012] A method for preparing the AlNiCo permanent magnet alloy as described above includes the following steps:

[0013] Raw materials containing Fe, Co, Ni, Al, Ti, Cu, Nb and rare earth elements are smelted and cast into ingots;

[0014] The ingot was subjected to solution treatment and a magnetic cold air treatment in sequence to obtain a solution sample;

[0015] The solid solution sample was subjected to magnetic field isothermal treatment and secondary magnetic field cold air treatment in sequence to obtain a blank; and

[0016] The blank is subjected to a three-stage tempering process to obtain an aluminum-nickel-cobalt permanent magnet alloy.

[0017] In one embodiment, the melting temperature is 1600℃-1700℃;

[0018] And / or, the solution treatment temperature is 1200℃-1300℃, and the time is 5min-20min;

[0019] And / or, the magnetic field conditions for the first magnetic field cooling air treatment are 3000e-40000e, the cooling rate is 7℃ / s-8℃ / s, and the temperature is reduced to 730℃-770℃ after the first magnetic field cooling air treatment.

[0020] And / or, the magnetic field isothermal heat treatment is performed at 790℃-820℃ for 10min-25min, with a magnetic field condition of 3000e-40000e;

[0021] And / or, the magnetic field conditions for the secondary magnetic field cold air treatment are 3000e-40000e, the cooling rate is 7℃ / s-8℃ / s, and the temperature is reduced to room temperature after secondary magnetic field cold air treatment;

[0022] And / or, in the three-stage tempering process, the first stage tempering process is held at 620℃-720℃ for 2h-6h, the second stage tempering process is held at 570℃-610℃ for 5h-10h, and the third stage tempering process is held at 450℃-550℃ for 12h-20h.

[0023] Application of an AlNiCo permanent magnet alloy as described above in magnetic devices.

[0024] In the AlNiCo permanent magnet alloy described in this invention, on the one hand, the precipitation of the first rare earth compound component alters the anisotropic field, causing rare earth elements to segregate and distribute in the FeCo-rich phase. This changes the degree of lattice distortion and lattice parameters of the FeCo-rich phase, refining its diameter, thereby improving the coercivity of the AlNiCo permanent magnet alloy and thus enhancing its magnetic properties. On the other hand, the periodic two-phase structure of the FeCo-rich and AlNi-rich phases in the AlNiCo permanent magnet alloy helps reduce the influence of temperature on its magnetic properties, thereby improving its temperature stability. Therefore, the AlNiCo permanent magnet alloy of this invention possesses both high coercivity and temperature stability, enabling it to improve the precision and reliability of magnetic devices when used in magnetic applications, thus meeting the development needs of high-precision, high-energy permanent magnet motors and other magnetic devices.

[0025] Furthermore, the method for preparing AlNiCo permanent magnet alloy provided by this invention can yield AlNiCo permanent magnet alloy that simultaneously possesses high coercivity and temperature stability. Attached Figure Description

[0026] Figure 1 The X-ray diffraction pattern of the AlNiCo permanent magnet alloy prepared in Example 1 of this invention;

[0027] Figure 2 This is a scanning electron microscope image of the AlNiCo permanent magnet alloy prepared in Example 1 of the present invention;

[0028] Figure 3 Transmission electron microscope (TEM) images of the AlNiCo permanent magnet alloy prepared in Example 1 of this invention under different magnification conditions;

[0029] Figure 4 The X-ray diffraction pattern of the AlNiCo permanent magnet alloy prepared in Comparative Example 1 of this invention is shown.

[0030] Figure 5 This is a transmission electron microscope image of the AlNiCo permanent magnet alloy prepared in Comparative Example 1 of the present invention.

[0031] Figure 6 This is a scanning electron microscope image of the AlNiCo permanent magnet alloy prepared in Comparative Example 2 of the present invention. Detailed Implementation

[0032] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments or examples only and is not intended to be limiting of the invention.

[0034] Through long-term and in-depth research, the applicant discovered that the refinement of the magnetic phase in AlNiCo permanent magnet alloys affects their coercivity, while differences in the magnetic phase structure affect their temperature stability. Therefore, adjusting the refinement or structure of the magnetic phase can effectively improve the coercivity and temperature stability of AlNiCo permanent magnet alloys.

[0035] Based on this, the present invention proposes an AlNiCo permanent magnet alloy comprising the following constituent elements by mass fraction: 30%-35% Co, 10%-15% Ni, 5%-8% Al, 4%-7% Ti, 2%-4% Cu, 0-2% Nb, less than 4% rare earth elements, and the balance Fe.

[0036] The AlNiCo permanent magnet alloy has a nanoscale dual-phase structure, which includes a FeCo-rich phase and an AlNi-rich phase. The FeCo-rich phase and the AlNi-rich phase are arranged periodically and alternately along the magnetic field direction. Some of the rare earth elements are distributed in the FeCo-rich phase, and some of the rare earth elements form nanoscale first rare earth compounds in the nanoscale dual-phase structure.

[0037] In the AlNiCo permanent magnet alloy of the present invention, on the one hand, the precipitation of the first rare earth compound component changes the anisotropic field, causing rare earth elements to be segregated and distributed in the FeCo-rich phase, changing the degree of lattice distortion and lattice parameters of the FeCo-rich phase, and refining the diameter of the FeCo-rich phase, thereby improving the coercivity of the AlNiCo permanent magnet alloy and thus enhancing its magnetic properties; on the other hand, the periodic two-phase structure of the FeCo-rich and AlNi-rich phases in the AlNiCo permanent magnet alloy helps to reduce the influence of temperature on the magnetic properties of the AlNiCo permanent magnet alloy, thereby improving the temperature stability of the AlNiCo permanent magnet alloy. Therefore, the AlNiCo permanent magnet alloy of the present invention has both high coercivity and high temperature stability.

[0038] Specifically, the FeCo-rich phase has a long rod-shaped structure, with its radial direction parallel to the magnetic field direction. Under the influence of rare earth elements segregated within the FeCo-rich phase, the diameter of the long rod-shaped structure is 20 nm-40 nm, and its length is ≥260 nm, preferably ≥300 nm. The rare earth elements are preferably those with a boiling point above 1700 °C, and the rare earth compounds formed with Co possess a high magnetocrystalline anisotropy field.

[0039] Since the AlNi-rich phase has a cubic structure, when the cross-section of the FeCo-rich phase parallel to the magnetic field direction is cubic, both the FeCo-rich phase and the AlNi-rich phase have a cubic structure.

[0040] To further improve the coercivity of the AlNiCo permanent magnet alloy, the AlNiCo permanent magnet alloy preferably comprises the following constituent elements by mass fraction: 30%-35% Co, 10%-15% Ni, 5%-8% Al, 4%-7% Ti, 2%-4% Cu, 0-2% Nb, less than or equal to 3.5% rare earth elements, and the balance Fe.

[0041] The rare earth element is preferably less than or equal to 2%, and the AlNiCo permanent magnet alloy is further preferably composed of the following elements by mass fraction: 33%-35% Co, 13%-15% Ni, 6%-8% Al, 4%-7% Ti, 2%-4% Cu, 0-2% Nb, less than or equal to 2% rare earth element and the balance Fe.

[0042] In one embodiment, the rare earth elements in the AlNiCo permanent magnet alloy, in addition to being distributed in the FeCo-rich phase and forming nanoscale first rare earth compounds in the nanoscale dual-phase structure, also have a remaining portion of rare earth elements forming micron-scale second rare earth compounds in the grain boundaries of the AlNiCo permanent magnet alloy.

[0043] By utilizing the first rare earth compound distributed in the nanoscale dual-phase structure and the second rare earth compound distributed in the grain boundaries, the magnetocrystalline anisotropy can be further altered, and the segregation distribution of rare earth elements in the FeCo-rich phase can be coordinated. This refines the size and increases the content of the first and second rare earth compounds, further enhancing the shape anisotropy field and thus improving the coercivity and temperature stability of the AlNiCo permanent magnet alloy.

[0044] Specifically, the first rare earth compound has an irregular shape with a size of 80nm-120nm, and its constituent elements mainly include Co and rare earth elements; the second rare earth compound is unevenly distributed along the grain boundaries, and its constituent elements mainly include Fe, Co and rare earth elements.

[0045] This invention also provides a method for preparing an AlNiCo permanent magnet alloy, the method comprising the following steps:

[0046] S1, which involves melting and casting raw materials containing Fe, Co, Ni, Al, Ti, Cu, Nb and rare earth elements into ingots;

[0047] S2, the ingot is subjected to solution treatment and magnetic cold air treatment in sequence to obtain a solution sample;

[0048] S3, the solution-treated sample is subjected to magnetic field isothermal treatment and secondary magnetic field cold air treatment in sequence to obtain a blank; and

[0049] S4. The blank is subjected to a three-stage tempering process to obtain an aluminum-nickel-cobalt permanent magnet alloy.

[0050] In step S1, in order to accurately prepare the raw materials for the AlNiCo permanent magnet alloy, the raw materials are proportioned according to the following mass fractions of elements: 30%-35% Co, 10%-15% Ni, 5%-8% Al, 4%-7% Ti, 2%-4% Cu, 0-2% Nb, less than 4% rare earth elements, and the balance Fe.

[0051] Preferably, the raw materials are melted in a vacuum induction melting furnace to obtain a uniform alloy solution, which is then cast into a mold to obtain an ingot, wherein the melting temperature is 1600℃-1700℃.

[0052] To make AlNiCo permanent magnet alloys suitable for different magnetic devices, ingots can be rough-machined to obtain ingots with the target dimensions.

[0053] In step S2, in order to fully dissolve the excess phase in the ingot to obtain a supersaturated solid solution, thereby improving the plasticity and toughness of the AlNiCo permanent magnet alloy, it is preferable to preheat the ingot at a temperature of 780℃-800℃ for 20min-30min, and then perform a solution treatment at a temperature of 1200℃-1300℃ for 5min-20min.

[0054] In one embodiment, after the ingot undergoes solution treatment, it needs to be rapidly cooled to 730°C-770°C in a magnetic field of 3000e-40000e at a cooling rate of 7°C / s-8°C / s.

[0055] In step S3, in order to induce amplitude-modulated decomposition of the AlNiCo permanent magnet alloy microstructure and elongate the FeCo-rich phase along the magnetic field direction to obtain better magnetic properties, it is preferable to hold the solid solution sample in a magnetic field of 3000e-40000e at a temperature of 790℃-820℃ for 10min-25min.

[0056] In one embodiment, after the solid solution sample is subjected to magnetic field isothermal treatment, it needs to be air-cooled to room temperature in a magnetic field of 3000e-40000e at a cooling rate of 7℃ / s-8℃ / s.

[0057] In step S4, in order to eliminate the internal stress of the blank, thereby improving the stability of the microstructure of the AlNiCo permanent magnet alloy and reducing its brittleness, it is preferable to perform a three-stage tempering treatment on the blank.

[0058] Specifically, in the three-stage tempering process, the first stage tempering process is to hold at 620℃-720℃ for 2h-6h, the second stage tempering process is to hold at 570℃-610℃ for 5h-10h, and the third stage tempering process is to hold at 450℃-550℃ for 12h-20h.

[0059] By strictly controlling the magnetic field heat treatment process during the preparation of AlNiCo permanent magnet alloy, the content and type of rare earth elements are regulated, thereby controlling the size and elemental distribution of FeCo-rich phase, first rare earth compound, and second rare earth compound, thus improving the coercivity and temperature stability of AlNiCo permanent magnet alloy.

[0060] This invention also provides an application of AlNiCo permanent magnet alloy in magnetic devices.

[0061] Using AlNiCo permanent magnet alloys in magnetic devices can improve the accuracy and reliability of these devices, thus meeting the development needs of high-precision, high-energy permanent magnet motors and other magnetic devices.

[0062] The following specific embodiments will further illustrate the AlNiCo permanent magnet alloy, its preparation method, and its applications.

[0063] Example 1

[0064] The raw materials are precisely weighed according to the following proportions: 32% Fe, 34.5% Co, 15% Ni, 7% Al, 6% Ti, 4% Cu, 1% Nb, and 0.5% rare earth elements. The raw materials are melted into a uniform alloy liquid in a vacuum induction melting furnace at 1600℃. The liquid is then poured into a mold to obtain an ingot. After the ingot has completely cooled, it is removed from the mold and roughed using wire cutting.

[0065] The cut ingots were preheated in a heat treatment furnace at 800°C for 30 minutes, and then placed in a high-temperature furnace at 1250°C for solution treatment. After holding at 1250°C for 7 minutes, they were rapidly cooled to 750°C in a magnetic field of 30000e at a cooling rate of 7°C / s to obtain a solution sample.

[0066] The solid solution sample was held at 815°C for 20 minutes in a magnetic field isothermal furnace at 40000e, and then removed from the magnetic field isothermal furnace and rapidly cooled to room temperature at a cooling rate of 7°C / s in a magnetic field of 30000e to obtain the blank.

[0067] The blank was subjected to a three-stage tempering process: the first stage was tempering at 650℃ for 3 hours, the second stage was tempering at 600℃ for 8 hours, and the third stage was tempering at 550℃ for 16 hours. After cooling to room temperature in the furnace, it was removed to obtain an aluminum-nickel-cobalt permanent magnet alloy.

[0068] The prepared AlNiCo permanent magnet alloy was analyzed using X-ray diffraction (XRD), and the results are as follows: Figure 1 As shown, the AlNiCo permanent magnet alloy includes a FeCo-rich phase and an AlNi-rich phase, both of which have a cubic structure.

[0069] The microstructure of the prepared AlNiCo permanent magnet alloy was analyzed using scanning electron microscopy (SEM), and the results are as follows: Figure 2 As shown.

[0070] The microstructure of the prepared AlNiCo permanent magnet alloy was analyzed using transmission electron microscopy (TEM) at different magnifications. The results are as follows: Figure 3 As shown, where, Figure 3 Image a shows a transmission electron microscope (TEM) image of the AlNiCo permanent magnet alloy at 50Kx magnification, and image b shows a TEM image of the AlNiCo permanent magnet alloy at 25Kx magnification. It can be seen that the AlNiCo permanent magnet alloy has a nanoscale dual-phase structure, with the FeCo-rich phase and the AlNi-rich phase arranged periodically and alternately along the magnetic field direction.

[0071] Example 2

[0072] The raw materials are precisely weighed according to the following proportions: 33% Fe, 34% Co, 13% Ni, 8% Al, 7% Ti, 4% Cu and 1% rare earth elements. The raw materials are melted into a uniform alloy liquid in a vacuum induction melting furnace at 1600℃. The liquid is then poured into a mold to obtain an ingot. After the ingot has completely cooled, it is removed from the mold and roughed using wire cutting.

[0073] The cut ingots were preheated in a heat treatment furnace at 800°C for 30 minutes, and then placed in a high-temperature furnace at 1250°C for solution treatment. After holding at 1250°C for 7 minutes, they were rapidly cooled to 750°C in a magnetic field of 30000e at a cooling rate of 7°C / s to obtain a solution sample.

[0074] The solid solution sample was held at 815°C for 20 minutes in a magnetic field isothermal furnace at 40000e, and then removed from the magnetic field isothermal furnace and rapidly cooled to room temperature at a cooling rate of 7°C / s in a magnetic field of 30000e to obtain the blank.

[0075] The blank was subjected to a three-stage tempering process: the first stage was tempering at 650℃ for 3 hours, the second stage was tempering at 600℃ for 8 hours, and the third stage was tempering at 550℃ for 16 hours. After cooling to room temperature in the furnace, it was removed to obtain an aluminum-nickel-cobalt permanent magnet alloy.

[0076] Example 3

[0077] The raw materials are precisely weighed according to the following proportions: 35% Fe, 34% Co, 14% Ni, 6% Al, 5% Ti, 2.5% Cu, 2% Nb, and 1.5% rare earth elements. The raw materials are melted into a uniform alloy liquid in a vacuum induction melting furnace at 1600℃. The liquid is then poured into a mold to obtain an ingot. After the ingot has completely cooled, it is removed from the mold and roughed using wire cutting.

[0078] The cut ingots were preheated in a heat treatment furnace at 800°C for 30 minutes, and then placed in a high-temperature furnace at 1250°C for solution treatment. After holding at 1250°C for 7 minutes, they were rapidly cooled to 750°C in a magnetic field of 30000e at a cooling rate of 7°C / s to obtain a solution sample.

[0079] The solid solution sample was held at 815°C for 20 minutes in a magnetic field isothermal furnace at 40000e, and then removed from the magnetic field isothermal furnace and rapidly cooled to room temperature at a cooling rate of 7°C / s in a magnetic field of 30000e to obtain the blank.

[0080] The blank was subjected to a three-stage tempering process: the first stage was tempering at 650℃ for 3 hours, the second stage was tempering at 600℃ for 8 hours, and the third stage was tempering at 550℃ for 16 hours. After cooling to room temperature in the furnace, it was removed to obtain an aluminum-nickel-cobalt permanent magnet alloy.

[0081] Example 4

[0082] The raw materials are precisely weighed according to the following proportions: 38% Fe, 33% Co, 13% Ni, 6% Al, 4% Ti, 2% Cu, 2% Nb, and 2% rare earth elements. The raw materials are melted into a uniform alloy liquid in a vacuum induction melting furnace at 1600℃. The liquid is then poured into a mold to obtain an ingot. After the ingot has completely cooled, it is removed from the mold and roughed using wire cutting.

[0083] The cut ingots were preheated in a heat treatment furnace at 800°C for 30 minutes, and then placed in a high-temperature furnace at 1250°C for solution treatment. After holding at 1250°C for 7 minutes, they were rapidly cooled to 750°C in a magnetic field of 30000e at a cooling rate of 7°C / s to obtain a solution sample.

[0084] The solid solution sample was held at 815°C for 20 minutes in a magnetic field isothermal furnace at 40000e, and then removed from the magnetic field isothermal furnace and rapidly cooled to room temperature at a cooling rate of 7°C / s in a magnetic field of 30000e to obtain the blank.

[0085] The blank was subjected to a three-stage tempering process: the first stage was tempering at 650℃ for 3 hours, the second stage was tempering at 600℃ for 8 hours, and the third stage was tempering at 550℃ for 16 hours. After cooling to room temperature in the furnace, it was removed to obtain an aluminum-nickel-cobalt permanent magnet alloy.

[0086] Example 5

[0087] The raw materials are precisely weighed according to the following proportions: 35% Fe, 35% Co, 13% Ni, 6% Al, 4% Ti, 2% Cu, 2% Nb, and 3% rare earth elements. The raw materials are melted into a uniform alloy liquid in a vacuum induction melting furnace at 1700℃. The liquid is then poured into a mold to obtain an ingot. After the ingot has completely cooled, it is removed from the mold and rough-machined using wire cutting.

[0088] The cut ingots were preheated in a heat treatment furnace at 780°C for 25 minutes, and then placed in a high-temperature furnace at 1200°C for solution treatment. After holding at 15 minutes, they were rapidly cooled to 730°C in a magnetic field of 40000e at a cooling rate of 8°C / s to obtain a solution sample.

[0089] The solid solution sample was held at 820°C for 20 minutes in a magnetic field isothermal furnace at 30000e, and then removed from the magnetic field isothermal furnace and rapidly cooled to room temperature at a cooling rate of 8°C / s in a magnetic field of 40000e to obtain the blank.

[0090] The blank was subjected to a three-stage tempering process: the first stage tempering was performed at 680℃ for 4 hours, the second stage tempering was performed at 590℃ for 9 hours, and the third stage tempering was performed at 500℃ for 18 hours. After cooling to room temperature in the furnace, it was removed to obtain an aluminum-nickel-cobalt permanent magnet alloy.

[0091] Example 6

[0092] The raw materials are precisely weighed according to the following proportions: 31.5% Fe, 34% Co, 14% Ni, 7% Al, 6% Ti, 3% Cu, 1% Nb, and 3.5% rare earth elements. The raw materials are melted into a uniform alloy liquid in a vacuum induction melting furnace at 1700℃. The liquid is then poured into a mold to obtain an ingot. After the ingot has completely cooled, it is removed from the mold and rough-machined using wire cutting.

[0093] The cut ingots were preheated in a heat treatment furnace at 780°C for 25 minutes, and then placed in a high-temperature furnace at 1300°C for solution treatment. After holding at 18 minutes, they were rapidly cooled to 740°C in a magnetic field of 40000e at a cooling rate of 8°C / s to obtain a solution sample.

[0094] The solid solution sample was held at 820°C for 15 minutes in a magnetic field isothermal furnace at 30000e, and then removed from the magnetic field isothermal furnace and rapidly cooled to room temperature in a magnetic field at 40000e at a cooling rate of 8°C / s to obtain the blank.

[0095] The blank was subjected to a three-stage tempering process: the first stage tempering was performed at 660℃ for 5 hours, the second stage tempering was performed at 580℃ for 8 hours, and the third stage tempering was performed at 500℃ for 16 hours. After cooling to room temperature in the furnace, it was removed to obtain an aluminum-nickel-cobalt permanent magnet alloy.

[0096] Comparative Example 1

[0097] The raw materials are precisely weighed according to the following proportions: 32% Fe, 35% Co, 15% Ni, 7% Al, 6% Ti, 4% Cu and 1% Nb. The raw materials are melted into a uniform alloy liquid in a vacuum induction melting furnace at 1600℃. The liquid is then poured into a mold to obtain an ingot. After the ingot has completely cooled, it is removed from the mold and roughed using wire cutting.

[0098] The cut ingots were preheated in a heat treatment furnace at 800°C for 30 minutes, and then placed in a high-temperature furnace at 1250°C for solution treatment. After holding at 1250°C for 7 minutes, they were rapidly cooled to 750°C in a magnetic field of 30000e at a cooling rate of 7°C / s to obtain a solution sample.

[0099] The solid solution sample was held at 815°C for 20 minutes in a magnetic field isothermal furnace at 40000e, and then removed from the magnetic field isothermal furnace and rapidly cooled to room temperature at a cooling rate of 7°C / s in a magnetic field of 30000e to obtain the blank.

[0100] The blank was subjected to a three-stage tempering process: the first stage was tempering at 650℃ for 3 hours, the second stage was tempering at 600℃ for 8 hours, and the third stage was tempering at 550℃ for 16 hours. After cooling to room temperature in the furnace, it was removed to obtain an aluminum-nickel-cobalt permanent magnet alloy.

[0101] Comparative Example 2

[0102] The raw materials were precisely weighed according to the following proportions: 35% Fe, 32% Co, 12% Ni, 7% Al, 5% Ti, 3% Cu, 2% Nb, and 4% rare earth elements.

[0103] The raw materials are melted into a uniform alloy liquid in a vacuum induction melting furnace at 1600℃, and then cast into a mold to obtain an ingot. After the ingot has completely cooled, it is removed from the mold and roughed using wire cutting.

[0104] The cut ingots were preheated in a heat treatment furnace at 800°C for 30 minutes, and then placed in a high-temperature furnace at 1250°C for solution treatment. After holding at 1250°C for 7 minutes, they were rapidly cooled to 750°C in a magnetic field of 30000e at a cooling rate of 7°C / s to obtain a solution sample.

[0105] The solid solution sample was held at 815°C for 20 minutes in a magnetic field isothermal furnace at 40000e, and then removed from the magnetic field isothermal furnace and rapidly cooled to room temperature at a cooling rate of 7°C / s in a magnetic field of 30000e to obtain the blank.

[0106] The blank was subjected to a three-stage tempering process: the first stage was tempering at 650℃ for 3 hours, the second stage was tempering at 600℃ for 8 hours, and the third stage was tempering at 550℃ for 16 hours. After cooling to room temperature in the furnace, it was removed to obtain an aluminum-nickel-cobalt permanent magnet alloy.

[0107] Comparative Example 3

[0108] The raw materials were precisely weighed according to the following proportions: 34% Fe, 32% Co, 12% Ni, 5% Al, 6% Ti, 4% Cu, 2% Nb, and 5% rare earth elements.

[0109] The raw materials are melted into a uniform alloy liquid in a vacuum induction melting furnace at 1600℃, and then cast into a mold to obtain an ingot. After the ingot has completely cooled, it is removed from the mold and roughed using wire cutting.

[0110] The cut ingots were preheated in a heat treatment furnace at 800°C for 30 minutes, and then placed in a high-temperature furnace at 1250°C for solution treatment. After holding at 1250°C for 7 minutes, they were rapidly cooled to 750°C in a magnetic field of 30000e at a cooling rate of 7°C / s to obtain a solution sample.

[0111] The solid solution sample was held at 815°C for 20 minutes in a magnetic field isothermal furnace at 40000e, and then removed from the magnetic field isothermal furnace and rapidly cooled to room temperature at a cooling rate of 7°C / s in a magnetic field of 30000e to obtain the blank.

[0112] The blank was subjected to a three-stage tempering process: the first stage was tempering at 650℃ for 3 hours, the second stage was tempering at 600℃ for 8 hours, and the third stage was tempering at 550℃ for 16 hours. After cooling to room temperature in the furnace, it was removed to obtain an aluminum-nickel-cobalt permanent magnet alloy.

[0113] The mass ratios of raw material elements for preparing AlNiCo permanent magnet alloys in Examples 1-6 and Comparative Examples 1-3 are shown in Table 1.

[0114] Table 1

[0115]

[0116] The elemental distribution of the second rare earth compounds in the grain boundaries of the AlNiCo permanent magnet alloys of Example 1 and Comparative Example 2 was analyzed using energy loss X-ray electron spectroscopy (EDS). The test results are shown in Table 2.

[0117] Table 2

[0118]

[0119] According to Table 2 and Figure 2 It is known that a second rare earth compound precipitates at the grain boundaries of the AlNiCo permanent magnet alloy. Its main components include Fe, Co and rare earth elements, and a large number of micron-sized rare earth-rich particles precipitate inside the grains of the AlNiCo permanent magnet alloy.

[0120] The diameter of the FeCo-rich phase and the size of the first rare earth compound in the AlNiCo permanent magnet alloys of Examples 1-6 and Comparative Examples 1-3 were measured, and the measurement results are shown in Table 3.

[0121] Table 3

[0122]

[0123] The performance of the AlNiCo permanent magnet alloys prepared in Examples 1-6 and Comparative Examples 1-3 was tested, and the test results are shown in Table 4.

[0124] Table 4

[0125]

[0126]

[0127]

[0128] As shown in Tables 3 and 4, compared with Examples 1-6, the less rare earth elements contained in the AlNiCo permanent magnet alloy, the smaller the diameter of the FeCo-rich phase in the two-phase system, the smaller the size of the first rare earth compound, the significantly increased coercivity, and the improved temperature stability. Therefore, the presence of trace amounts of rare earth elements in the AlNiCo permanent magnet alloy can improve its coercivity and temperature stability. However, the AlNiCo permanent magnet alloy in Comparative Example 1, which does not contain rare earth elements, exhibits inferior temperature stability compared to the AlNiCo permanent magnet alloys in Examples 1-6 that contain rare earth elements.

[0129] Comparative examples 1-6 and 2-3 show that when rare earth elements are present in excess in the AlNiCo permanent magnet alloy, the coercivity and temperature stability of the alloy are lower. Therefore, a rare earth element content of 4% or higher in the AlNiCo permanent magnet alloy will reduce its magnetic properties.

[0130] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0131] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An AlNiCo permanent magnet alloy, characterized in that, The AlNiCo permanent magnet alloy comprises the following elements by mass fraction: 30%-35% Co, 10%-15% Ni, 5%-8% Al, 4%-7% Ti, 2%-4% Cu, 0-2% Nb, less than 4% rare earth elements, and the balance Fe. The AlNiCo permanent magnet alloy has a nanoscale dual-phase structure, which includes a FeCo-rich phase and an AlNi-rich phase. The FeCo-rich phase and the AlNi-rich phase are arranged periodically and alternately along the magnetic field direction. Some of the rare earth elements are distributed in the FeCo-rich phase, and some of the rare earth elements form nanoscale first rare earth compounds in the nanoscale dual-phase structure. The remaining rare earth elements form micrometer-scale second rare earth compounds in the grain boundaries of the AlNiCo permanent magnet alloy. The second rare earth compound mainly includes Fe, Co and rare earth elements.

2. The AlNiCo permanent magnet alloy according to claim 1, characterized in that, The AlNiCo permanent magnet alloy comprises the following elements by mass fraction: 30%-35% Co, 10%-15% Ni, 5%-8% Al, 4%-7% Ti, 2%-4% Cu, 0-2% Nb, less than or equal to 3.5% rare earth elements, and the balance Fe.

3. The AlNiCo permanent magnet alloy according to claim 1 or 2, characterized in that, The size of the first rare earth compound is 80nm-120nm.

4. The AlNiCo permanent magnet alloy according to claim 1 or 2, characterized in that, The first rare earth compound mainly consists of Co and rare earth elements.

5. The AlNiCo permanent magnet alloy according to claim 1 or 2, characterized in that, The FeCo-rich phase has a long rod-shaped structure, the radial direction of which is parallel to the magnetic field direction, and the diameter of the long rod-shaped structure is 20nm-40nm, and the length is ≥260nm.

6. A method for preparing an AlNiCo permanent magnet alloy as described in any one of claims 1-5, characterized in that, The preparation method of the AlNiCo permanent magnet alloy includes the following steps: Raw materials containing Fe, Co, Ni, Al, Ti, Cu, Nb and rare earth elements are smelted and cast into ingots; The ingot was subjected to solution treatment and a magnetic cold air treatment in sequence to obtain a solution sample; The solid solution sample was subjected to magnetic field isothermal heat treatment and secondary magnetic field cold air treatment in sequence to obtain a blank. as well as The blank is subjected to a three-stage tempering process to obtain an aluminum-nickel-cobalt permanent magnet alloy.

7. The method for preparing the AlNiCo permanent magnet alloy according to claim 6, characterized in that, The melting temperature is 1600℃-1700℃; And / or, the solution treatment temperature is 1200℃-1300℃, and the time is 5min-20min; And / or, the magnetic field conditions for the first magnetic field cooling air treatment are 3000e-40000e, the cooling rate is 7℃ / s-8℃ / s, and the temperature is reduced to 730℃-770℃ after the first magnetic field cooling air treatment. And / or, the magnetic field isothermal heat treatment is performed at 790℃-820℃ for 10min-25min, with a magnetic field condition of 3000e-40000e; And / or, the magnetic field conditions for the secondary magnetic field cold air treatment are 3000e-40000e, the cooling rate is 7℃ / s-8℃ / s, and the temperature is reduced to room temperature after secondary magnetic field cold air treatment; And / or, in the three-stage tempering process, the first stage tempering process is held at 620℃-720℃ for 2h-6h, the second stage tempering process is held at 570℃-610℃ for 5h-10h, and the third stage tempering process is held at 450℃-550℃ for 12h-20h.

8. The application of an AlNiCo permanent magnet alloy as described in any one of claims 1-5 in magnetic devices.

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