Rare earth high-entropy alloy, annular magnet and preparation method of rare earth high-entropy alloy

Abstract

The invention belongs to the field of rare earth magnetic materials, and particularly relates to a rare earth high-entropy alloy, an annular magnet and a preparation method of the rare earth high-entropy alloy. The invention discloses a rare earth high-entropy alloy, the component of which is (HEA-Re) 2Fe14B, HEA-Re is more than four of rare earth elements La, Ce, Pr, Nd, Y, Gd, Ho, Dy and Tb, and the content proportions of the rare earth elements are the same; meanwhile, the invention discloses a preparation method for preparing the annular magnet by adopting the rare earth high-entropy alloy through the steps of smelting, solution rapid quenching, annealing heat treatment, magnetic powder preparation, magnet pre-forming, hot pressing, thermal deformation and the like, and the prepared annular magnet. According to the annular magnet prepared through the components and the method, the magnetic performance and the mechanical performance are obviously improved, the content of high-price rare earth elements is reduced, and the cost is effectively saved.

Description

Technical Field

[0001] The invention belongs to the field of rare earth magnetic materials, and in particular relates to a rare earth high entropy alloy, a ring magnet and a preparation method thereof. Background Art

[0002] In the application of permanent magnet motors, magnetic rings have the advantages of compact structure, simple assembly, stable output waveform, etc., which can significantly reduce the weight and energy consumption of motors and improve the operation stability. For this reason, the permanent magnet components in high-performance permanent magnet motors are gradually changing from traditional magnetic tile splicing rings to integral radiation rings. At present, the main preparation methods of radiation magnetic rings, especially NdFeB radiation magnetic rings, are sintering and hot pressing. Sintered radiation magnetic rings are prepared by radiation orientation during the permanent magnet powder forming process and then sintering to obtain magnetic rings with radiation orientation. Hot pressing is to induce the spontaneous orientation of its internal grains into radiation magnetic rings by hot extrusion (hot deformation) of hot pressed magnets in a temperature field. Compared with sintered magnetic rings, hot deformed magnetic rings have short preparation process, high reliability and high magnetic properties, especially in the preparation of height-to-diameter ratio, thin wall and small size magnetic rings. In recent years, high entropy alloys (HEA) have received high attention in the field of materials science and engineering. Unlike traditional alloys containing one and usually two basic elements, high entropy alloys contain multiple key elements in equimolar concentrations, and the number of possible high entropy alloy compositions is much more expanded than that of traditional alloys. Most importantly, these high entropy alloys can be constructed and processed using procedures similar to traditional materials. The combination of compositions and processing pathways in the field of high entropy alloys may lead to a wide range of new microstructures and properties, such as better mechanical properties, corrosion resistance, wear resistance, strength, hardness, etc.

[0003] However, the mechanical properties and corrosion resistance of traditional rare earth permanent magnet materials, such as NdFeB, are poor, which limits their scope of use. How to obtain permanent magnet materials with excellent performance in all aspects is a goal that technicians in this field have always pursued. Summary of the invention

[0004] Based on the above background, the present invention provides a new technology for preparing high-performance NdFeB ring magnets by using rare earth high entropy alloys to replace rare earth elements, so as to achieve the purpose of improving mechanical properties, magnetic properties and saving costs.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a rare earth high entropy alloy, the composition of which is (HEA-Re)2Fe 14 B, HEA-Re is four or more of the elements La, Ce, Pr, Nd, Y, Gd, Ho, Dy, and Tb, and the content ratio of each rare earth element is the same.

[0007] In a preferred embodiment, the composition of the rare earth high entropy alloy is (HEA-Re)2Fe 14 B, HEA-Re is the elements La, Ce, Pr, Nd, La, Pr, Nd, Dy or La, Ce, Pr, Nd, Y, Gd, Ho, and the content ratio of each rare earth element is the same.

[0008] A second aspect of the present invention provides a method for preparing a rare earth high entropy alloy ring magnet, comprising the following steps:

[0009] (1) Smelting: placing various metal raw materials in a crucible in a smelting furnace and smelting them under a protective gas atmosphere to obtain an alloy ingot;

[0010] (2) rapid quenching of the solution: removing the oxide on the surface of the metal ingot, placing it in a quartz tube, and fixing the quartz tube in an induction coil; spinning the strip under a protective gas atmosphere to obtain a composite thin strip;

[0011] (3) Annealing heat treatment: placing the composite thin strip in a quartz tube, filling the tube with protective gas, placing the quartz tube in a heat treatment furnace for heating, and cooling after completion;

[0012] (4) preparing magnetic powder: the composite thin strip is ball-milled in a protective gas atmosphere to obtain composite magnetic powder;

[0013] (5) Magnet preforming: placing the composite magnetic powder in a preforming mold and cold pressing to preform the magnet;

[0014] (6) Hot pressing: placing the preformed magnet in a hot pressing mold, placing the hot pressing mold in an induction furnace, evacuating the mold, heating, and keeping the heat; applying pressure and keeping the pressure; after the heating is completed, the pressure is unloaded, and the mold is cooled to room temperature to obtain an isotropic precursor;

[0015] (7) Thermal deformation: placing the isotropic precursor in a thermal deformation mold, evacuating, heating, keeping warm, and pressurizing to extrude the magnetic ring in the reverse direction at a uniform speed. After completion, stop heating, unload part of the pressure, wait for the temperature to cool to room temperature, unload the pressure to 0, and demold to obtain a radiation-oriented permanent magnetic ring.

[0016] In the preparation method, the protective gas may be a rare gas, such as argon.

[0017] In the preparation method, the metal raw material can be a single metal and / or an alloy that can satisfy (HEA-Re)2Fe 14 B, and the content of each rare earth element is the same.

[0018] In the step (1), the smelting may be performed 3-8 times, preferably 6 times.

[0019] In the step (2), the metal ingot with surface oxide removed is cut into small pieces and then placed in a quartz tube.

[0020] In the step (2), the rotation speed of the copper roller during the belt spinning is 10-50 m / s, preferably 15-30 m / s.

[0021] In the step (3), the heating temperature may be 500-800°C, preferably 600-700°C.

[0022] In the step (3), the cooling method after completion is water cooling.

[0023] In the step (4), the voltage of the ball milling is 10-100V, preferably 50-80V.

[0024] In the step (4), the ball milling time is 0.5-10 h, preferably 0.5-3 h.

[0025] In the step (5), all contact positions of the mold with the composite magnetic powder are evenly coated with a release agent; the release agent is preferably a boron nitride release agent.

[0026] In step (6), the induction furnace is evacuated to a vacuum of less than 0.1 Pa, preferably 1×10 -2 Below Pa.

[0027] In the step (6), the induction furnace is evacuated and then heated to 500-700° C., preferably 500-600° C.; after heating, the temperature is kept at this temperature for 2-10 minutes, preferably 2-5 minutes.

[0028] In the step (6), the pressure is increased to 100-250 MPa, preferably 150-200 MPa, after heating; and the pressure is maintained for 2-10 minutes, preferably 2-5 minutes.

[0029] In the step (6), all contact positions of the hot pressing mold with the composite magnetic powder are evenly coated with a release agent; the release agent is preferably a boron nitride release agent.

[0030] In the step (7), the heat deformation mold is evacuated to 1×10 -2 Below Pa.

[0031] In the step (7), the heat deformation mold is evacuated and then heated to 700-900° C., preferably 800-900° C.; after heating, the heat is kept warm for 2-10 minutes, preferably 5-10 minutes.

[0032] In the step (7), the pressure is increased to 200-300 MPa, preferably 200-250 MPa, after heating.

[0033] In the step (7), after stopping heating, the pressure is unloaded in stages, preferably in two stages. In the first stage, when the heating is stopped, the pressure is unloaded to 15 MPa; in the second stage, when the temperature drops to room temperature, the pressure is unloaded to 0.

[0034] In the step (7), all contact positions of the thermal deformation mold with the composite magnetic powder are evenly coated with a release agent; the release agent is preferably a boron nitride release agent.

[0035] The preparation method comprises the following steps:

[0036] (1) Melting: Place the ingredients in a crucible in a vacuum melting furnace and evacuate the furnace to 5×10 -3 Pa, introduce argon gas, repeat the purge three times, and finally introduce argon gas, and repeat the smelting for 6 times or more to obtain an alloy ingot;

[0037] (2) Solution quenching: The surface oxide scale of the alloy ingot is polished clean, cut into small pieces and loaded into a quartz tube, which is fixed in an induction coil. The quenching furnace is vacuumed to 5×10 -4 Pa, argon was introduced, the purge was repeated three times, and finally argon was introduced, and the belt was spun. The speed of the copper roller was 15-30m / s to prepare (HEA-RE)2Fe 14 B. Rare earth high entropy alloy and rare earth permanent magnet composite ribbon;

[0038] (3) Annealing heat treatment: Place the composite ribbon in a quartz tube and pass argon into the tube to seal it. Then place the quartz tube containing the ribbon in a heat treatment furnace, heat to 600-700°C, keep warm for 0-30 minutes, and cool with water after the heat preservation.

[0039] (4) Preparation of magnetic powder: The rare earth high entropy alloy and rare earth permanent magnet composite thin strip are subjected to high energy ball milling under Ar gas, the high energy ball milling voltage is 50-80V, and the ball milling time is 0.5h-3h to prepare rare earth high entropy alloy and rare earth permanent magnet composite magnetic powder;

[0040] (5) Magnet preforming: The composite magnetic powder is placed in a preforming mold, and the contact positions of the mold with the magnetic powder are uniformly coated with a boron nitride release agent, and cold pressing is performed for preforming and initial densification;

[0041] (6) Hot pressing: The preformed magnet is placed in a hot pressing mold. The contact positions of the mold with the magnet are evenly coated with a boron nitride release agent. The mold is placed in an induction hot pressing furnace and vacuumed to 1×10 -2 Pa, first heat the temperature range to 500-600℃, keep warm for 2-5min, then apply pressure to 150-200MPa to fully densify the magnet, keep pressure for 2-5min, immediately stop heating, unload pressure, cool to room temperature with the furnace, demold to obtain an isotropic precursor;

[0042] (7) Thermal deformation: The isotropic precursor is placed in a thermal deformation mold. The contact positions of the thermal deformation mold with the magnet are uniformly coated with a boron nitride release agent and vacuumed to 1×10 -2 Pa, first heat the temperature range to 800-900℃, keep warm for 5-10min, then apply pressure to 200-250MPa, so that the magnetic ring is back-extruded at a uniform rate, stop heating immediately after preparation, first unload the pressure to 15MPa to maintain the shape of the magnetic ring, cool to room temperature with the furnace, and completely unload the pressure to 0 after reaching room temperature, and demold to obtain a radiation-oriented permanent magnetic ring.

[0043] The third aspect of the present invention provides a ring magnet prepared by the above preparation method, the composition of which is (HEA-Re)2Fe 14 B, HEA-Re is four or more of the rare earth elements La, Ce, Pr, Nd, Y, Gd, and Ho, and the content ratio of each rare earth element is the same.

[0044] In a preferred embodiment, the composition of the annular magnet is (HEA-Re)2Fe 14 B, HEA-Re is rare earth elements La, Ce, Pr, Nd, La, Pr, Nd, Dy or La, Ce, Pr, Nd, Y, Gd, Ho, and the content ratio of each rare earth element is the same.

[0045] In a preferred embodiment, the raw material of the annular magnet can be a single metal and / or alloy that can satisfy (HEA-Re)2Fe 14 B, and the content of each rare earth element is the same.

[0046] The reagents and raw materials used in the present invention are commercially available.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The present invention provides a new technology for preparing NdFeB magnetic rings by using rare earth high entropy alloys to replace rare earth elements. This technology solves the problem of poor mechanical properties of NdFeB magnetic rings in the prior art. The magnetic and mechanical properties of the NdFeB magnetic rings prepared by this method are significantly improved, and the cost is effectively saved by reducing the content of high-priced rare earth elements. DETAILED DESCRIPTION

[0049] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0050] Example 1

[0051] (1) Ingredients: Prepare the raw materials with (HEA-Re)2Fe14 B is used for batching, and the rare earth high entropy alloy content is appropriately increased considering the rare earth burnout. Among them, HEA-Re is the elements La, Pr, Nd, and Dy, and the molar ratio of each element is roughly the same. Its raw materials are: 63.96 grams of La block, 64.87 grams of Pr block, 66.41 grams of Nd block, 74.82 grams of Dy block, 719.98 grams of Fe particles, and 9.96 grams of B powder.

[0052] (2) Melting: Place the ingredients in a crucible in a vacuum melting furnace and evacuate the furnace to 5×10 -3 Pa, introduce argon, repeat the purge three times, and finally introduce argon. Repeat the smelting for 6 times or more to obtain a 1kg elliptical alloy ingot.

[0053] (3) Solution quenching: The surface oxide scale of the alloy ingot is polished clean, cut into small pieces and loaded into a quartz tube, the quartz tube is fixed in an induction coil, and the quenching furnace is vacuumed to 5×10 -4 Pa, argon was introduced, and the purge was repeated three times. Finally, argon was introduced and the belt was spun. The speed of the copper roller was 15-30m / s to prepare (HEA-Re)2Fe 14 B rare earth high entropy alloy and rare earth permanent magnet composite thin strip, thickness 0.2-0.6mm.

[0054] (4) Annealing heat treatment: Place the composite thin strip in a quartz tube and pass argon gas into the tube to seal it. Then put the quartz tube containing the thin strip into a heat treatment furnace, heat it to 600-700°C, keep it warm for 0-30 minutes, and cool it down with water after the insulation is completed.

[0055] (5) Preparation of magnetic powder: The rare earth high entropy alloy and rare earth permanent magnet composite thin strip are subjected to high energy ball milling under Ar gas, the high energy ball milling voltage is 50-80V, and the ball milling time is 0.5-3h to produce rare earth high entropy alloy and rare earth permanent magnet composite magnetic powder.

[0056] (6) Magnet preforming: The composite magnetic powder is placed in a preforming mold, and the contact positions of the mold with the magnetic powder are evenly coated with a boron nitride release agent, and cold pressing preforming is performed for initial densification.

[0057] (7) Hot pressing: The preformed magnet is placed in a hot pressing mold. The contact positions of the mold with the magnet are uniformly coated with a boron nitride release agent. The mold is placed in an induction hot pressing furnace and vacuumed to 1×10 -2 Pa, first heat the temperature range to 500-600℃, keep warm for 2-5min, then apply pressure to 150-200MPa to fully densify the magnet, keep pressure for 2-5min, immediately stop heating, unload pressure, cool to room temperature with the furnace, and demold to obtain an isotropic precursor.

[0058] (8) Thermal deformation: The isotropic precursor is placed in a thermal deformation mold. The contact positions of the thermal deformation mold with the magnet are uniformly coated with a boron nitride release agent and vacuumed to 1×10 -2 Pa, first heat the temperature range to 800-900℃, keep warm for 5-10min, then apply pressure to 200-250MPa, so that the magnetic ring is back-extruded at a uniform rate, stop heating immediately after preparation, first unload the pressure to 15MPa to maintain the shape of the magnetic ring, cool to room temperature with the furnace, and completely unload the pressure to 0 after reaching room temperature, and demold to obtain a radiation-oriented permanent magnetic ring.

[0059] Example 2

[0060] (1) Ingredients: Prepare the raw materials with (HEA-Re)2Fe 14 B is used for batching, and the rare earth high entropy alloy content is appropriately increased considering the rare earth burnout. Among them, HEA-Re is the elements La, Ce, Pr, and Nd, and the molar ratio of each element is roughly the same. Its raw materials are: 64.62 grams of La block, 65.18 grams of Ce block, 65.55 grams of Pr block, 67.13 grams of Nd block, 727.48 grams of Fe particles, and 10.06 grams of B powder.

[0061] (2) Melting: Place the ingredients in a crucible in a vacuum melting furnace and evacuate the furnace to 5×10 -3 Pa, introduce argon, repeat the purge three times, and finally introduce argon. Repeat the smelting for 6 times or more to obtain an elliptical 1kg alloy ingot.

[0062] (3) Solution quenching: The surface oxide scale of the alloy ingot is polished clean, cut into small pieces and loaded into a quartz tube, the quartz tube is fixed in an induction coil, and the quenching furnace is vacuumed to 5×10 -4 Pa, argon was introduced, and the purge was repeated three times. Finally, argon was introduced and the belt was spun. The speed of the copper roller was 15-30m / s to prepare (HEA-Re)2Fe 14 B rare earth high entropy alloy and rare earth permanent magnet composite thin strip, thickness 0.2-0.6mm.

[0063] (4) Annealing heat treatment: Place the composite thin strip in a quartz tube and pass argon gas into the tube to seal it. Then put the quartz tube containing the thin strip into a heat treatment furnace, heat it to 600-700°C, keep it warm for 0-30 minutes, and cool it down with water after the insulation is completed.

[0064] (5) Preparation of magnetic powder: The rare earth high entropy alloy and rare earth permanent magnet composite thin strip are subjected to high energy ball milling under Ar gas, the high energy ball milling voltage is 50-80V, and the ball milling time is 0.5-3h to produce rare earth high entropy alloy and rare earth permanent magnet composite magnetic powder.

[0065] (6) Magnet preforming: The composite magnetic powder is placed in a preforming mold, and the contact positions of the mold with the magnetic powder are evenly coated with a boron nitride release agent, and cold pressing preforming is performed for initial densification.

[0066] (7) Hot pressing: The preformed magnet is placed in a hot pressing mold. The contact positions of the mold with the magnet are evenly coated with a boron nitride release agent. The mold is placed in an induction hot pressing furnace and vacuumed to 1×10 -2 Pa, first heat the temperature range to 500-600℃, keep warm for 2-5min, then apply pressure to 150-200MPa to fully densify the magnet, keep pressure for 2-5min, immediately stop heating, unload pressure, cool to room temperature with the furnace, and demold to obtain an isotropic precursor.

[0067] (8) Thermal deformation: The isotropic precursor is placed in a thermal deformation mold. The contact positions of the thermal deformation mold with the magnet are uniformly coated with a boron nitride release agent and vacuumed to 1×10 -2 Pa, first heat the temperature range to 800-900℃, keep warm for 5-10min, then apply pressure to 200-250MPa, so that the magnetic ring is back-extruded at a uniform rate, stop heating immediately after preparation, first unload the pressure to 15MPa to maintain the shape of the magnetic ring, cool to room temperature with the furnace, and completely unload the pressure to 0 after reaching room temperature, and demold to obtain a radiation-oriented permanent magnetic ring.

[0068] Example 3

[0069] (1) Ingredients: Prepare the raw materials with (HEA-Re)2Fe 14 B is used for batching, and the rare earth high entropy alloy content is appropriately increased considering the rare earth burnout. Among them, HEA-Re is the elements La, Ce, Pr, Nd, Y, Tb, Gd, and Ho, and the molar ratio of each element is roughly the same. La block 32.27 grams, Ce block 32.54 grams, Pr block 32.73 grams, Nd block 33.51 grams, Y block 20.65 grams, Tb block 36.91 grams, Gd block 36.53 grams, Ho block 38.31 grams, Fe particles 726.48 grams, B powder 10.05 grams.

[0070] (2) Melting: Place the ingredients in a crucible in a vacuum melting furnace and evacuate the furnace to 5×10 -3 Pa, introduce argon, repeat the purge three times, and finally introduce argon. Repeat the smelting for 6 times or more to obtain a 1kg elliptical alloy ingot.

[0071] (3) Solution quenching: The surface oxide scale of the alloy ingot is polished clean, cut into small pieces and loaded into a quartz tube, the quartz tube is fixed in an induction coil, and the quenching furnace is vacuumed to 5×10 -4Pa, argon was introduced, and the purge was repeated three times. Finally, argon was introduced and the belt was spun. The speed of the copper roller was 15-30m / s to prepare (HEA-Re)2Fe 14 B rare earth high entropy alloy and rare earth permanent magnet composite thin strip, thickness 0.2-0.6mm.

[0072] (4) Annealing heat treatment: Place the composite thin strip in a quartz tube and pass argon gas into the tube to seal it. Then put the quartz tube containing the thin strip into a heat treatment furnace, heat it to 600-700°C, keep it warm for 0-30 minutes, and cool it down with water after the insulation is completed.

[0073] (5) Preparation of magnetic powder: The rare earth high entropy alloy and rare earth permanent magnet composite thin strip are subjected to high energy ball milling under Ar gas, the high energy ball milling voltage is 50-80V, and the ball milling time is 0.5-3h to produce rare earth high entropy alloy and rare earth permanent magnet composite magnetic powder.

[0074] (6) Magnet preforming: The composite magnetic powder is placed in a preforming mold, and the contact positions of the mold with the magnetic powder are evenly coated with a boron nitride release agent, and cold pressing preforming is performed for initial densification.

[0075] (7) Hot pressing: The preformed magnet is placed in a hot pressing mold. The contact positions of the mold with the magnet are uniformly coated with a boron nitride release agent. The mold is placed in an induction hot pressing furnace and vacuumed to 1×10 -2 Pa, first heat the temperature range to 500-600℃, keep warm for 2-5min, then apply pressure to 150-200MPa to fully densify the magnet, keep pressure for 2-5min, immediately stop heating, unload pressure, cool to room temperature with the furnace, and demold to obtain an isotropic precursor.

[0076] (8) Thermal deformation: The isotropic precursor is placed in a thermal deformation mold. The contact positions of the thermal deformation mold with the magnet are uniformly coated with a boron nitride release agent and vacuumed to 1×10 -2 Pa, first heat the temperature range to 800-900℃, keep warm for 5-10min, then apply pressure to 200-250MPa, so that the magnetic ring is back-extruded at a uniform rate, stop heating immediately after preparation, first unload the pressure to 15MPa to maintain the shape of the magnetic ring, cool to room temperature with the furnace, and completely unload the pressure to 0 after reaching room temperature, and demold to obtain a radiation-oriented permanent magnetic ring.

[0077] Comparative Example 1

[0078] (1) Ingredients: Prepare the raw materials with (Pr, Nd)2Fe 14 B is used for batching, and the rare earth element content is appropriately increased considering the rare earth burning loss. Pr block 130.74g, Nd block 133.83g, Fe powder 725.41g, B powder 10.03g.

[0079] (2) Melting: Place the ingredients in a crucible in a vacuum melting furnace and evacuate the furnace to 5×10 -3、 Pa, introduce argon, repeat the purge three times, and finally introduce argon. Repeat the smelting for 6 times or more to obtain 1 kg of alloy ingot.

[0080] (3) Solution quenching: The surface oxide scale of the alloy ingot is polished clean, cut into small pieces and loaded into a quartz tube, the quartz tube is fixed in an induction coil, and the quenching furnace is vacuumed to 5×10 -4 Pa, argon was introduced, and the purge was repeated three times. Finally, argon was introduced and the belt was spun. The speed of the copper roller was 15-30m / s to prepare (HEA-Re)2Fe 14 B rare earth high entropy alloy and rare earth permanent magnet composite thin strip, thickness 0.2-0.6mm.

[0081] (4) Annealing heat treatment: Place the composite thin strip in a quartz tube and pass argon gas into the tube to seal it. Then put the quartz tube containing the thin strip into a heat treatment furnace, heat it to 600-700°C, keep it warm for 0-30 minutes, and cool it down with water after the insulation is completed.

[0082] (5) Preparation of magnetic powder: The rare earth high entropy alloy and rare earth permanent magnet composite thin strip are subjected to high energy ball milling under Ar gas, the high energy ball milling voltage is 50-80V, and the ball milling time is 0.5h-3h to produce rare earth high entropy alloy and rare earth permanent magnet composite magnetic powder.

[0083] (6) Magnet preforming: The composite magnetic powder is placed in a preforming mold, and the contact positions of the mold with the magnetic powder are evenly coated with a boron nitride release agent, and cold pressing preforming is performed for initial densification.

[0084] (7) Hot pressing: The preformed magnet is placed in a hot pressing mold. The contact positions of the mold with the magnet are evenly coated with a boron nitride release agent. The mold is placed in an induction hot pressing furnace and vacuumed to 1×10 -2 Pa, first heat the temperature range to 500-600℃, keep warm for 2-5min, then apply pressure to 150-200MPa to fully densify the magnet, keep pressure for 2-5min, immediately stop heating, unload pressure, cool to room temperature with the furnace, and demold to obtain an isotropic precursor.

[0085] (8) Thermal deformation: The isotropic precursor is placed in a thermal deformation mold. The contact positions of the thermal deformation mold with the magnet are uniformly coated with a boron nitride release agent and vacuumed to 1×10 -2Pa, first heat the temperature range to 800-900℃, keep warm for 5-10min, then apply pressure to 200-250MPa, so that the magnetic ring is back-extruded at a uniform rate, stop heating immediately after preparation, first unload the pressure to 15MPa to maintain the shape of the magnetic ring, cool to room temperature with the furnace, and completely unload the pressure to 0 after reaching room temperature, and demold to obtain a radiation-oriented permanent magnetic ring.

[0086] Comparative Example 2

[0087] (1) Ingredients: Prepare the raw materials with Nd2Fe 14 B is used for ingredient preparation. Considering the rare earth burnout, the rare earth element content is appropriately increased, including 266.83 grams of Nd block, 723.17 grams of Fe powder and 9.99 grams of B powder.

[0088] (2) Melting: Place the ingredients in a crucible in a vacuum melting furnace and evacuate the furnace to 5×10 -3 Pa, introduce argon, repeat the purge three times, and finally introduce argon. Repeat the smelting for 6 times or more to obtain 1 kg of alloy ingot.

[0089] (3) Solution quenching: The surface oxide scale of the alloy ingot is polished clean, cut into small pieces and loaded into a quartz tube, the quartz tube is fixed in an induction coil, and the quenching furnace is vacuumed to 5×10 -4 Pa, argon was introduced, and the purge was repeated three times. Finally, argon was introduced and the belt was spun. The speed of the copper roller was 15-30m / s to prepare (HEA-Re)2Fe 14 B rare earth high entropy alloy and rare earth permanent magnet composite thin strip, thickness 0.2-0.6mm.

[0090] (4) Annealing heat treatment: Place the composite thin strip in a quartz tube and pass argon gas into the tube to seal it. Then put the quartz tube containing the thin strip into a heat treatment furnace, heat it to 600-700°C, keep it warm for 0-30 minutes, and cool it down with water after the insulation is completed.

[0091] (5) Preparation of magnetic powder: The rare earth high entropy alloy and rare earth permanent magnet composite thin strip are subjected to high energy ball milling under Ar gas, the high energy ball milling voltage is 50-80V, and the ball milling time is 0.5h-3h to produce rare earth high entropy alloy and rare earth permanent magnet composite magnetic powder.

[0092] (6) Magnet preforming: The composite magnetic powder is placed in a preforming mold, and the contact positions of the mold with the magnetic powder are evenly coated with a boron nitride release agent, and cold pressing preforming is performed for initial densification.

[0093] (7) Hot pressing: The preformed magnet is placed in a hot pressing mold. The contact positions of the mold with the magnet are uniformly coated with a boron nitride release agent. The mold is placed in an induction hot pressing furnace and vacuumed to 1×10 -2Pa, first heat the temperature range to 500-600℃, keep warm for 2-5min, then apply pressure to 150-200MPa to fully densify the magnet, keep pressure for 2-5min, immediately stop heating, unload pressure, cool to room temperature with the furnace, and demold to obtain an isotropic precursor.

[0094] (8) Thermal deformation: The isotropic precursor is placed in a thermal deformation mold. The contact positions of the thermal deformation mold with the magnet are uniformly coated with a boron nitride release agent and vacuumed to 1×10 -2 Pa, first heat the temperature range to 800-900℃, keep warm for 5-10min, then apply pressure to 200-250MPa, so that the magnetic ring is back-extruded at a uniform rate, stop heating immediately after preparation, first unload the pressure to 15MPa to maintain the shape of the magnetic ring, cool to room temperature with the furnace, and completely unload the pressure to 0 after reaching room temperature, and demold to obtain a radiation-oriented permanent magnetic ring.

[0095] Comparative Example 3

[0096] (1) Ingredients: Prepare the raw materials with (HEA-Re)2Fe 14 B is used for batching, and the rare earth high entropy alloy content is appropriately increased considering the rare earth burnout. Among them, HEA-Re is the elements La, Pr, Nd, and Dy, and the molar ratio of each element is roughly the same. La block 63.96 grams, Pr block 64.87 grams, Nd block 66.41 grams, Dy block 74.82 grams, Fe particles 719.98 grams, B powder 9.96 grams.

[0097] (2) Melting: Place the ingredients in a crucible in a vacuum melting furnace and evacuate the furnace to 5×10 -3 Pa, introduce argon, repeat the purge three times, and finally introduce argon. Repeat the smelting for 6 times or more to obtain 1 kg of alloy ingot.

[0098] (3) Solution quenching: The surface oxide scale of the alloy ingot is polished clean, cut into small pieces and loaded into a quartz tube, the quartz tube is fixed in an induction coil, and the quenching furnace is vacuumed to 5×10 -4 Pa, argon was introduced, and the purge was repeated three times. Finally, argon was introduced and the belt was spun. The speed of the copper roller was 15-30m / s to prepare (HEA-Re)2Fe 14 B rare earth high entropy alloy and rare earth permanent magnet composite thin strip, thickness 0.2-0.6mm.

[0099] (4) Annealing heat treatment: Place the composite thin strip in a quartz tube and pass argon gas into the tube to seal it. Then put the quartz tube containing the thin strip into a heat treatment furnace, heat it to 600-700°C, keep it warm for 0-30 minutes, and cool it down with water after the insulation is completed.

[0100] (5) Preparation of magnetic powder: The rare earth high entropy alloy and rare earth permanent magnet composite thin strip are subjected to high energy ball milling under Ar gas, the high energy ball milling voltage is 50-80V, and the ball milling time is 0.5-3h to produce rare earth high entropy alloy and rare earth permanent magnet composite magnetic powder.

[0101] (6) Magnet preforming: The composite magnetic powder is placed in a preforming mold, and the contact positions of the mold with the magnetic powder are evenly coated with a boron nitride release agent, and cold pressing preforming is performed for initial densification.

[0102] (7) Hot pressing: The preformed magnet is placed in a hot pressing mold. The contact positions of the mold with the magnet are uniformly coated with a boron nitride release agent. The mold is placed in an induction hot pressing furnace and vacuumed to 1×10 -2 Pa, first heat the temperature range to 300-500℃, keep warm for 2-5min, then apply pressure to 100-150MPa to fully densify the magnet, keep pressure for 2-5min, immediately stop heating, unload pressure, cool to room temperature with the furnace, and demold to obtain an isotropic precursor.

[0103] (8) Thermal deformation: The isotropic precursor is placed in a thermal deformation mold. The contact positions of the thermal deformation mold with the magnet are uniformly coated with a boron nitride release agent and vacuumed to 1×10 -2 Pa, first heat the temperature range to 900-950℃, keep warm for 5-10min, then apply pressure to 150-200MPa, so that the magnetic ring is back-extruded at a uniform rate, stop heating immediately after preparation, first unload the pressure to 15MPa to maintain the shape of the magnetic ring, cool to room temperature with the furnace, and completely unload the pressure to 0 after reaching room temperature, and demold to obtain a radiation-oriented permanent magnetic ring.

[0104] The magnetic properties of the magnetic rings in the embodiment and the comparative example are compared. The magnetic properties are tested by a vibrating sample magnetometer (VSM). A 3mm*3mm*3mm rectangular block test sample of each sample is placed in a 3T magnetic field at room temperature for a hysteresis loop test. The mechanical properties are tested by a universal testing machine for non-standard samples. As shown in Table 1 and Table 2.

[0105] Table 1: Magnetic property test results in the embodiments of the present invention and comparative examples (taking the magnetic properties of the magnetic rings prepared in each example as an example).

[0106] Coercivity(kOe) Remanence(kGs) Magnetic energy product (MGOe) Example 1 14.7 14.5 41.9 Example 2 11.9 13.5 36.7 Example 3 13.7 13.4 38.9 Comparative Example 1 9.7 11.4 30.2 Comparative Example 2 10.8 11.2 31.6 Comparative Example 3 12.4 10.5 31.4

[0107] It can be clearly seen from the experimental results in Table 1 that after adjusting the alloy composition, the coercivity is increased by at least 10%, the remanence is increased by at least 15%, and the magnetic energy product is increased by at least 15%; after adjusting the preparation method, the coercivity is equivalent to or slightly improved, the remanence is increased by at least 25%, and the magnetic energy product is increased by at least 15%. Through the alloy composition and / or preparation method of the present application, the magnetic properties of the magnetic ring are significantly improved.

[0108] Table 2: Mechanical property test results in the embodiments of the present invention and comparative examples (taking the tensile strength and compressive strength of the magnetic rings prepared in each example as examples).

[0109]

[0110]

[0111] It can be clearly seen from the experimental results in Table 2 that after adjusting the alloy composition, the tensile strength is increased by at least 15%, and the compressive strength is increased by at least nearly 10%; after adjusting the preparation method, the tensile strength is increased by at least 30%, and the compressive strength is increased by at least 10%. Through the alloy composition and / or preparation method of the present application, the mechanical properties of the magnetic ring are significantly improved.

[0112] In summary, the magnetic properties of the radiation-oriented magnetic ring prepared by the method of the present invention are the best. Compared with Comparative Examples 1 and 2, the coercive force and magnetic energy product of the magnetic ring forming the high entropy alloy rare earth phase are improved, and the mechanical properties are improved. Compared with Comparative Example 3, the magnetic ring formed by the magnetic ring preparation process parameters provided by the present invention has better magnetic properties and mechanical properties.

Claims

1. A rare earth high entropy alloy, characterized in that: Its composition is (HEA-Re)2Fe 14 B, HEA-Re is four or more elements among La, Ce, Pr, Nd, Y, Gd, Ho, Dy, and Tb, and the content ratio of each rare earth element is the same.

2. A method for preparing a rare earth high entropy alloy ring magnet, characterized in that: The following steps are involved: (1) Smelting: placing various metal raw materials in a crucible in a smelting furnace and smelting them under a protective gas atmosphere to obtain an alloy ingot; (2) rapid quenching of the solution: removing the oxide on the surface of the metal ingot, placing it in a quartz tube, and fixing the quartz tube in an induction coil; spinning the strip under a protective gas atmosphere to obtain a composite thin strip; (3) Annealing heat treatment: placing the composite thin strip in a quartz tube, filling the tube with protective gas, placing the quartz tube in a heat treatment furnace for heating, and cooling after completion; (4) preparing magnetic powder: the composite thin strip is ball-milled in a protective gas atmosphere to obtain composite magnetic powder; (5) Magnet preforming: placing the composite magnetic powder in a preforming mold and cold pressing to preform the magnet; (6) Hot pressing: placing the preformed magnet in a hot pressing mold, placing the hot pressing mold in an induction furnace, and evacuating the mold; Heating, insulation; Pressurize and maintain the pressure; after the pressure is completed, stop heating, unload the pressure, cool to room temperature, and obtain an isotropic precursor; (7) Thermal deformation: placing the isotropic precursor in a thermal deformation mold, evacuating, heating, keeping warm, and pressurizing to extrude the magnetic ring in the reverse direction at a uniform speed. After completion, stop heating, unload part of the pressure, wait for the temperature to cool to room temperature, unload the pressure to 0, and demold to obtain a radiation-oriented permanent magnetic ring.

3. The preparation method according to claim 2, characterized in that: The metal raw material may be a single metal and / or an alloy that satisfies (HEA-Re)2Fe 14 B, and the content of each rare earth element is the same.

4. The preparation method according to claim 2, characterized in that: The preparation method satisfies one or more of the following: (a) the protective gas is a rare gas; (b) In step (1), the smelting is performed 3 to 8 times; (c) in step (2), the metal ingot after removing the surface oxide is cut into small pieces and then placed in a quartz tube; (d) In the step (2), the copper roller rotates at a speed of 10-50 m / s when the belt is swung; (e) In step (3), the heating temperature is 500-800° C.; (f) In step (3), the cooling method after completion is water cooling; (g) In step (4), the ball milling voltage is 10-100 V; (h) In step (4), the ball milling time is 1-10 hours; (i) In step (5), all contact positions of the mold with the composite magnetic powder are evenly coated with a release agent; (k) In step (6), the induction furnace is evacuated to a vacuum of 0.1×10 -2 Below Pa; (l) In the step (6), the induction furnace is evacuated and then heated to 500-700° C.; (m) in step (6), the pressure is increased to 100-250 MPa after heating; (n) In the step (6), the contact positions of the hot pressing mold with the composite magnetic powder are uniformly coated with a release agent; (o) In step (7), the heat deformation mold is evacuated to 1×10 -2 Below Pa; (p) In the step (7), the heat deformation mold is evacuated and then heated to 700-900° C.; (q) in step (7), the pressure is increased to 200-300 MPa, preferably 200-250 MPa after heating; (r) in step (7), the pressure is unloaded in stages after the heating is stopped; (s) In the step (7), the contact positions of the thermal deformation mold with the composite magnetic powder are uniformly coated with a release agent.

5. The preparation method according to claim 4, characterized in that: The preparation method satisfies one or more of the following: (a1) The protective gas is argon; (b1) In step (1), the smelting is performed 6 times; (d1) In the step (2), the rotation speed of the copper roller during the belt spinning is 15-30 m / s; (e1) In step (3), the heating temperature is 600-700° C.; (g1) In step (4), the ball milling voltage is 50-80V; (h1) In step (4), the ball milling time is 0.5-3h; (i1) In step (5), the release agent is preferably a boron nitride release agent; (k1) In step (6), the induction furnace is evacuated to a vacuum of 1×10 -2 Below Pa; (l1) In the step (6), the induction furnace is evacuated and then heated to 500-600°C; (m1) In step (6), the pressure is increased to 150-200 MPa after heating; (n1) In step (6), the release agent is preferably a boron nitride release agent; (p1) In the step (7), the heat deformation mold is evacuated and then heated to 800-900°C; (q1) In step (7), the pressure is increased to 200-250 MPa after heating; (r1) In step (7), after stopping heating, the pressure is unloaded in two stages. In the first stage, when heating is stopped, the pressure is unloaded to 15 MPa; in the second stage, when the temperature drops to room temperature, the pressure is unloaded to 0; (s1) In the step (7), the release agent is preferably a boron nitride release agent.

6. The preparation method according to claim 5, characterized in that: The preparation method satisfies one or more of the following: (12) In the step (6), the induction furnace is evacuated and then heated and then kept warm for 2-10 minutes, preferably 2-5 minutes; (m2) In step (6), the pressure is maintained for 2-10 minutes after heating and pressurizing, preferably 2-5 minutes; (p2) In the step (7), the heat-deformable mold is evacuated, heated, and then kept warm for 2-10 minutes, preferably 5-10 minutes.

7. The preparation method according to claim 2, characterized in that: The preparation method comprises the following steps: (1) Melting: Place the ingredients in a crucible in a vacuum melting furnace and evacuate the furnace to 5×10 -3 Pa, introduce argon gas, repeat the purge three times, and finally introduce argon gas, and repeat the smelting for 6 times or more to obtain an alloy ingot; (2) Solution quenching: The surface oxide scale of the alloy ingot is polished clean, cut into small pieces and loaded into a quartz tube, which is fixed in an induction coil. The quenching furnace is vacuumed to 5×10 -4 Pa, argon was introduced, the purge was repeated three times, and finally argon was introduced, and the belt was spun. The speed of the copper roller was 15-30m / s to prepare (HEA-RE)2Fe 14 B. Rare earth high entropy alloy and rare earth permanent magnet composite ribbon; (3) Annealing heat treatment: Place the composite ribbon in a quartz tube and pass argon into the tube to seal it. Then place the quartz tube containing the ribbon in a heat treatment furnace, heat to 600-700°C, keep warm for 0-30 minutes, and cool with water after the heat preservation. (4) Preparation of magnetic powder: The rare earth high entropy alloy and rare earth permanent magnet composite thin strip are subjected to high energy ball milling under Ar gas, the high energy ball milling voltage is 50-80V, and the ball milling time is 0.5-3h to prepare rare earth high entropy alloy and rare earth permanent magnet composite magnetic powder; (5) Magnet preforming: The composite magnetic powder is placed in a preforming mold, and the contact positions of the mold with the magnetic powder are uniformly coated with a boron nitride release agent, and cold pressing is performed for preforming and initial densification; (6) Hot pressing: The preformed magnet is placed in a hot pressing mold. The contact positions of the mold with the magnet are uniformly coated with a boron nitride release agent. The mold is placed in an induction hot pressing furnace and vacuumed to 1×10 -2 Pa, first heat the temperature range to 500-600℃, keep warm for 2-5min, then apply pressure to 150-200MPa to fully densify the magnet, keep pressure for 2-5min, immediately stop heating, unload pressure, cool to room temperature with the furnace, demold to obtain an isotropic precursor; (7) Thermal deformation: The isotropic precursor is placed in a thermal deformation mold. The contact positions of the thermal deformation mold with the magnet are uniformly coated with a boron nitride release agent and vacuumed to 1×10 -2 Pa, first heat the temperature range to 800-900℃, keep warm for 5-10min, then apply pressure to 200-250MPa, so that the magnetic ring is back-extruded at a uniform rate, stop heating immediately after preparation, first unload the pressure to 15MPa to maintain the shape of the magnetic ring, cool to room temperature with the furnace, and completely unload the pressure to 0 after reaching room temperature, and demold to obtain a radiation-oriented permanent magnetic ring.

8. A ring magnet prepared by the preparation method according to any one of claims 2 to 7, characterized in that: Its composition is (HEA-Re)2Fe 14 B, HEA-Re is four or more of the rare earth elements La, Ce, Pr, Nd, Y, Gd, Ho, Dy, and Tb, and the content ratio of each rare earth element is the same.

9. The ring magnet according to claim 8, characterized in that The composition of the annular magnet is (HEA-Re)2Fe 14 B, HEA-Re is rare earth elements La, Ce, Pr, Nd, La, Pr, Nd, Dy or La, Ce, Pr, Nd, Y, Gd, Ho, and the content ratio of each rare earth element is the same.

10. The ring magnet according to claim 8, characterized in that The raw material of the annular magnet is a single metal and / or alloy that can satisfy (HEA-Re)2Fe 14 B, and the content of each rare earth element is the same.

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