A samarium-based rare earth permanent magnet bulk material and a preparation method and application thereof

Abstract

This invention discloses a samarium-based rare-earth permanent magnet bulk material, its preparation method, and its application. (The last part, "ThMn," appears to be an incomplete sentence or fragment and is left untranslated.) 12 A uniform metallic T coating is formed on the surface of the magnetic powder. The composite magnetic powder is then oriented, pressed into blocks, and heat-treated to create a double-layered non-magnetic shell around the grains. This shell hinders domain movement, effectively improving the material's coercivity. Furthermore, compared to doping or melting, the coating process requires less T and allows for more precise control, preventing excessive T from entering the crystal lattice and negatively impacting the material's intrinsic magnetic properties, thus significantly improving the coercivity of ThMn. 12 Density and overall performance of rare earth permanent magnets.

Description

Technical Field

[0001] This invention belongs to the field of rare earth permanent magnet material preparation technology, specifically relating to a samarium-based rare earth permanent magnet bulk material, its preparation method, and its application. Background Technology

[0002] Rare earth elements typically exist in symbiotic forms in mineral deposits. Currently, with the widespread application of neodymium in high-performance permanent magnet materials, samarium resources, which coexist with neodymium, are largely left idle due to low utilization rates. Therefore, developing high-performance rare earth permanent magnet materials based on samarium not only helps improve the comprehensive utilization efficiency of rare earth resources but also has significant strategic importance.

[0003] And ThMn 12 Samarium-based rare-earth permanent magnet materials not only possess excellent intrinsic properties, but also attract widespread attention due to their advantages such as low rare-earth content and low cost. However, ThMn... 12 The difficulty in preparing samarium-based rare-earth permanent magnets stems from a profound contradiction between their inherent physicochemical properties and existing material preparation technologies. The core challenges can be summarized into three interconnected levels: First, thermodynamic metastability necessitates the introduction of stabilizing elements to dilute magnetic properties, resulting in a fundamental trade-off between phase stability and high saturation magnetization. Second, the lack of an efficient densification mechanism makes it difficult to achieve both high density and grain refinement (especially single-domain formation). Finally, the complex microstructure makes it difficult to establish an effective magnetohardening mechanism, resulting in the material's macroscopic coercivity being far inferior to its intrinsic potential. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a samarium-based rare-earth permanent magnet bulk material, its preparation method, and its applications. This invention utilizes SmFe... 12 A metallic coating forms on the surface of the magnetic powder. During heat treatment, excess Sm elements in the magnetic powder and T elements in the surface layer interdiffusion form two non-magnetic phases, one of which is the low-melting-point non-magnetic phase Sm. 100-t T t (at%) for the formation of high-density ThMn 12 Rare earth permanent magnets are of paramount importance. When magnetic domains inside the magnetic powder move to the surface of the magnetic powder, they are hindered by the double-layer non-magnetic phase shell structure, which increases the resistance to the movement of magnetic domains. This is macroscopically manifested as an increase in the coercivity of the magnetic material.

[0005] One of the technical solutions of this invention is to provide a samarium-based rare-earth permanent magnet bulk material, composed of grains with a core-shell structure, wherein (Sm x A y Zr z ) a (Fe 1-b D b ) d M gThe grain forms the core, which is successively filled with Sm-Fe-T nonmagnetic phase and Sm from the inside out. 100- t T t (at%) of nonmagnetic phase coating, where 0≤t≤90(at%); The samarium-based rare earth permanent magnet bulk material is (Sm x A y Zr z ) a (Fe 1-b D b ) d M g T m Where A is one or more of Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; D is one of Co and Ni; M is one or more of Ti, V, Mo, Al, Si, Nb, B, C, Mn, and W; and T is one or more of Ag, Cu, Zn, and Sn. Where x+y+z=1, 0≤y≤1, 0≤z≤0.5; a=(100-m) / 13 (at%); 0≤b≤1; (100-m)*9 / 13 (at%)≤d≤(100-m)*11.5 / 13 (at%); (100-m) / 26 (at%)≤g≤(100-m)*3 / 13 (at%); (d+g)*13 / (100-m)=12; 0≤m≤10 (at%).

[0006] The grains have a diameter of 0.55 μm, and the grains contain Sm-Fe-T nonmagnetic phases and Sm... 100-t T t The thickness of the non-magnetic phase (at%) is no greater than 50 nm, and the total thickness of the shell is no greater than 100 nm.

[0007] The density of the samarium-based rare-earth permanent magnet bulk material is 6.8-7.9 g / cm³. 3 Intrinsic coercivity ≥10kOe, maximum energy product ≥15MGOe.

[0008] The second technical solution of this invention is to provide a method for preparing samarium-based rare earth permanent magnet bulk materials, using (Sm x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M gMagnetic powder particles are used as raw materials, and a layer of metal T is coated on the surface. The metal T is one of Ag, Cu, Zn, and Sn. Then, the particles are oriented and pressed using a magnetic field. Next, cold isostatic pressing is performed to form a cold-formed magnet. The cold-formed magnet is then placed in a hot-pressing mold for hot pressing. Finally, the hot-pressed magnet is encapsulated and then placed in a heat treatment furnace for heat treatment to obtain samarium-based rare-earth permanent magnet bulk material. Here, e represents the rare-earth element compensation amount, 0 ≤ e ≤ 1. By precisely controlling the time, temperature, and surface metal T content during the heat treatment (annealing) process, the SmFe content is rationally adjusted. 12 The phase structure changes at the interface of the / T composite magnet before and after heat treatment are studied to maximize the coercivity enhancement.

[0009] The encapsulation process involves placing the composite magnet inside a quartz test tube with a volume not exceeding five times the volume of the compacted magnet. The quartz test tube is then filled with argon gas for protection or the vacuum level is ensured to be no higher than 1 × 10⁻⁶. -5 Pa. A dynamic sealing technique using a quartz test tube vacuum sealing machine is employed. A flame seal is used to encapsulate the opening of the quartz test tube, protecting the magnet from oxidation and other environmental factors, while also preventing the volatilization of samarium during heat treatment. This method plays a significant role in improving the coercivity of magnets.

[0010] Furthermore, under inert gas protection, methods such as vapor deposition, liquid deposition, electroplating, sputtering, evaporation plating, ion plating, spraying, electroless plating, immersion plating, thermal spraying, and laser cladding are used to coat (Sm) x(1+e) A y(1+e) Zr z ) a (Fe 1- b D b ) d M g Magnetic powder particles coated with metal T.

[0011] Furthermore, (Sm x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M g The preparation method of magnetic powder particles is one of the following: spray pyrolysis-reduction diffusion method, alloy melting and strip casting method, alloy melting hydrogen embrittlement method, co-precipitation-reduction diffusion method, and high-energy alloying.

[0012] Generally, to prevent oxidation of ingredients, the key is to pre-treat easily oxidized metal raw materials and remove and properly store their surface oxide film before smelting.

[0013] The hot-pressing conditions for the magnet are as follows: hot-pressing temperature 300-600℃, hot-pressing pressure greater than 0.5 GPa, hot-pressing time 0.5-10 min, holding time 0.5-10 min, and magnet density ≥ 6.4 g / cm³. 3 .

[0014] Further, the heat treatment temperature is 600-750℃, and the annealing time is 0.5-3 hours. Preferably, the heat treatment temperature is 600℃, and the annealing time is 1 hour. During the heat treatment process, T (Ag / Cu / Zn / Sn or one or more) and (Sm) x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M g The volatilization of Sm and T on the particle surface leads to interdiffusion, resulting in the magnetic powder particles being bound by a continuous nonmagnetic Sm-Fe-T phase and Sm. 100-t T t The (at%) phase is completely encapsulated, and the two phases sequentially surround each other to form a "core-shell-shell" structure, effectively isolating the magnetic core. This structure not only enhances the coercivity of the magnet but also provides a high-performance (Sm) magnet. x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M g T t This laid a solid foundation for the industrialization and application of magnets.

[0015] Furthermore, (Sm x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M g The percentage of metal atoms coated on the surface of magnetic powder particles is 0-10 at.

[0016] The third technical solution of the present invention is to provide the application of the above-mentioned samarium-based rare earth permanent magnet bulk material.

[0017] The beneficial effects of this invention are as follows: (1) By constructing a non-magnetic double-shell structure, the movement of magnetic domain walls can be effectively suppressed; at the same time, Sm 100-t T t (at%) is a low-melting-point alloy that can promote densification between magnetic powders at lower sintering temperatures, thereby improving the mechanical strength of the magnet.

[0018] (2) The present invention directly coats (Sm) metal T (Ag / Cu / Zn / Sn or one or more) onto (Sm) x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M g The magnetic powder surface is then subjected to orientation pressing, hot pressing, and heat treatment to achieve T (one or more of Ag / Cu / Zn / Sn) and (Sm) x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M g The sufficient reaction and diffusion of iron oxides and α-Fe on the surface of the permanent magnet block can ensure that the T (Ag / Cu / Zn / Sn or one or more) elements are evenly distributed from the surface to the interior during the heat treatment process, and the preparation process has no limitation on the thickness of the permanent magnet block. Attached Figure Description

[0019] Figure 1 The heat treatment (annealing) before and after the present invention (Sm) x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M g Microscopic phase structure evolution diagram of / T composite magnet.

[0020] Figure 2 The images are X-ray diffraction and desktop scanning electron microscope images from Example 1. Detailed Implementation

[0021] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all terms used below are weight fractions and atomic percentages.

[0022] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0023] The embodiments of the present invention will be further described below with reference to several examples.

[0024] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0025] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0026] Example 1 Step (1) Preparation of composite magnetic powder: Under a protective atmosphere (such as nitrogen), Sm is deposited by vapor phase deposition or liquid phase deposition. 11.1 Fe 77.8 V 11.1 A Cu coating is applied to the surface of (at%) magnetic powder (particle size: ≤5μm) to obtain composite magnetic powder containing 0.5at% Cu.

[0027] Step (2) Low-temperature hot pressing to prepare composite magnets: The magnetic powder coated with Cu from step (1) was oriented and pressed into a blank under a 3T magnetic field. The blank was then subjected to cold isostatic pressing at 300 MPa to obtain a cold-formed magnet. Next, these cold-formed magnets were placed in a hot-pressing mold and rapidly hot-pressed to obtain a composite magnet. The entire pressing process was carried out in a glove box filled with inert gas to prevent oxidation of the magnetic powder. Hot-pressing experimental parameters: hot-pressing temperature 350℃, hot-pressing pressure 3GPa, heating time 3min, holding time 2min.

[0028] The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.43 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 9.45 kgs, Hcj = 5.61 KOe, (BH)max = 20.58 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, measured by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 0.5 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'Pert Pro) and a benchtop scanning electron microscope (Phenom ProX), such as... Figure 2 As shown.

[0029] Step (3) Composite magnet encapsulation: The composite magnet prepared by hot pressing in step (2) is placed inside a quartz tube, the volume of which does not exceed 5 times the volume of the compacted magnet. The tube is then filled with argon gas or a vacuum level not exceeding 1×10⁻⁶. 5 Under Pa conditions, a quartz test tube vacuum sealing machine is used with dynamic sealing technology to seal the opening of the quartz test tube with a flame.

[0030] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment at 600℃ for 1 hour, and then cooled and removed from the furnace. The density of the composite magnet was tested to be 6.67 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 9.17 KGs, Hcj = 15.67 KOe, (BH)max = 18.65 MGOe.

[0031] Where Sm 11.1 Fe 77.8 V 11.1 (at%) grain size is ThMn 12 The Sm-Fe-Cu phase is a non-magnetic subphase, while the Sm-Fe-Cu phase is a non-magnetic subphase. 100-t Cu t The phase is a low-melting-point non-magnetic alloy phase.

[0032] The diffusion thickness of the outermost Sm-Fe-Cu phase in the composite magnet is 10 nm. The outer Sm... 100-t Cu t The phase is encapsulated by Sm-Fe-Cu phase. 11.1 Fe 77.8 V 11.1 (at%), and the Sm-Fe-Cu phase is continuously distributed, with the outer Sm layer... 100-t Cu t The encapsulation thickness is 50nm.

[0033] During heat treatment, Cu reacts with Sm 11.1 Fe 77.8 V 11.1 (at%) Particle surface volatilization: Sm and Cu interdiffusion; during the diffusion-structure evolution process, Sm... 11.1 Fe 77.8 V 11.1 (at%) Particle surfaces successively formed a continuous non-magnetic Sm-Fe-Cu subphase as the second outermost layer and an outermost Sm... 100-t Cu t Phase, with Sm-Fe-Cu phase and Sm 100-t Cu t As the phase gradually forms and grows, the original Cu coating thins and eventually disappears.

[0034] Sm-Fe-Cu subphase and Sm 100-t Cu t The phase itself does not exhibit ferromagnetism and does not directly contribute to the overall magnetic properties, but the "core-shell structure" formed by its surrounding magnetic powder effectively prevents adjacent Sm from being affected. 11.1 Fe 77.8 V 11.1 (at%) Exchange coupling between magnetic particles during the magnetization process. Furthermore, the generated Sm... 100-t T t The phase also smooths the surface of the magnetic powder, further eliminating potential reverse magnetic domain nucleation sites. This significantly improves Sm while having a relatively small impact on remanence and magnetic energy product. 11.1 Fe 77.8 V 11.1 The coercivity of the (at%) / Cu composite magnet. In the final obtained material, Sm... 11.1 Fe 77.8 V 11.1 The core consists of (at%) grains, whose surface is successively coated with a non-magnetic Sm-Fe-Cu subphase (secondary outer layer) and a low-melting-point Sm as the outermost layer. 100-t Cu t The non-magnetic alloy phases together constitute Sm with a core-shell grain structure. 11.1 Fe 77.8 V 11.1 (at%)Cu 0.5 Metal block permanent magnet.

[0035] like Figure 1 As shown, the possible chemical reactions inside the composite magnet during the heat treatment process are as shown in (1) and (2): Cu+ Sm 11.1 Fe 77.8 V 11.1 (at%)→Sm 11.1 Fe 77.8 V 11.1 (at%)+Sm-Fe-Cu (1) Cu + Sm → Sm 100-t Cu t (2) In the above reactions, reactions (1) and (2) generate Sm-Fe-Cu nonmagnetic subphases and Sm 100-t Cu t The non-magnetic phase increases coercivity. Specifically, during heat treatment, Sm... 11.1 Fe 77.8 V 11.1 (at%) Cu coating on magnetic powder surface and Sm 11.1 Fe 77.8 V11.1 (at%) of volatile Sm diffuses into each other, forming Sm 11.1 Fe 77.8 V 11.1 (at%) grains form the core, which is then successively surrounded by Sm-Fe-Cu nonmagnetic phase and Sm from the inside out. 100-t T t (at%) The non-magnetic phase is completely encapsulated, forming a "core-shell-shell multilayer structure" of Sm. 11.1 Fe 77.8 V 11.1 (at%)Cu 0.5 Metallic bulk permanent magnet, wherein Sm 100-t Cu t The nonmagnetic subphase diffusion thickness is no greater than 50 nm, and the Sm-Fe-Cu nonmagnetic phase diffuses along Sm 11.1 Fe 77.8 V 11.1 (at%) grains are continuously distributed on the surface, with a coating thickness greater than 1 nm and less than 50 nm. Sm after heat treatment 11.1 Fe 77.8 V 11.1 The density of the permanent magnet (at%) is 6.57.1 ​​g / cm³. 3 Intrinsic coercivity ≥10 kOe, maximum energy product ≥13 MGOe. Sm 11.1 Fe 77.8 V 11.1 (at%) Cu coating on magnetic powder surface and Sm 11.1 Fe 77.8 V 11.1 (at%) reaction diffusion, forming a nonmagnetic Sm-Fe-Cu subphase with Sm 100-t Cu t The non-magnetic phase, the Cu coating gradually disappears; the coercivity of the permanent magnet increases by more than 1.5 times before and after heat treatment.

[0036] Example 2 Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1.

[0037] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 30 mm and a density of 6.54 g / cm³. 3The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.97 kg / s, Hcj = 5.23 KOe, (BH)max = 19.87 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, as determined by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 0.5 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'Pert Pro) and a benchtop scanning electron microscope (Phenom ProX).

[0038] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0039] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment at a temperature of 650°C for 1 hour. The sample was then cooled and removed from the furnace.

[0040] The diffusion thickness of the outermost Sm-Fe-Cu phase in the composite magnet is 14 nm. The outer Sm... 100-t Cu t The phase encapsulation thickness is 35nm.

[0041] The density of the composite magnet was tested to be 6.73 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 9.13 KGs, Hcj = 13.45 KOe, (BH)max = 17.86 MGOe.

[0042] Example 3: Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1.

[0043] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 20 mm and a density of 6.81 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 10.27 kgs, Hcj = 4.92 KOe, (BH)max = 19.54 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, as measured by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 0.5 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'Pert Pro) and a benchtop scanning electron microscope (Phenom ProX).

[0044] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0045] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment at a temperature of 700°C for 1 hour. The sample was then cooled and removed from the furnace.

[0046] The diffusion thickness of the outermost Sm-Fe-Cu phase in the composite magnet is 21 nm. The outer Sm... 100-t Cu t The phase encapsulation thickness is 41 nm.

[0047] The density of the composite magnet was tested to be 7.05 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.23 ​​KGs, Hcj = 15.21 KOe, (BH)max = 16.53 MGOe.

[0048] Example 4: Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1, except that the atomic content of Cu was adjusted, as shown in Table 2.

[0049] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.78 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 9.56 kgs, Hcj = 4.69 KOe, (BH)max = 18.89 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, measured by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 2 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'PertPro) and a benchtop scanning electron microscope (Phenom ProX).

[0050] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0051] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment at a temperature of 600°C for 1 hour. The sample was then cooled and removed from the furnace.

[0052] The diffusion thickness of the outermost Sm-Fe-Cu phase in the composite magnet is 25 nm. The outer Sm... 100-t Cu t The phase encapsulation thickness is 36nm.

[0053] The density of the composite magnet was tested to be 6.92 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 9.21 KGs, Hcj = 15.88 KOe, (BH)max = 17.96 MGOe.

[0054] Example 5: Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1, except that the atomic content of Cu was adjusted, as shown in Table 2.

[0055] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.45 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.85 kg / s, Hcj = 6.51 KOe, (BH)max = 17.83 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, measured by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 4 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'PertPro) and a benchtop scanning electron microscope (Phenom ProX).

[0056] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0057] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment at a temperature of 600°C for 1 hour. The sample was then cooled and removed from the furnace.

[0058] The diffusion thickness of the outermost Sm-Fe-Cu phase in the composite magnet is 31 nm. The outer Sm... 100-t Cu t The phase encapsulation thickness is 45nm.

[0059] The density of the composite magnet was tested to be 6.62 g / cm³. 3The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.07 KGs, Hcj = 12.89 KOe, (BH)max = 15.73 MGOe.

[0060] Example 6: Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1, except that the atomic content of Cu was adjusted, as shown in Table 2.

[0061] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.57 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 9.18 kg / s, Hcj = 5.87 KOe, (BH)max = 19.18 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, as measured by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 6 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'PertPro) and a benchtop scanning electron microscope (Phenom ProX).

[0062] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0063] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment at a temperature of 600°C for 1 hour. The sample was then cooled and removed from the furnace.

[0064] The diffusion thickness of the outermost Sm-Fe-Cu phase in the composite magnet is 45 nm. The outer Sm... 100-t Cu t The phase encapsulation thickness is 46nm.

[0065] The density of the composite magnet was tested to be 6.71 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.54 KGs, Hcj = 15.13 KOe, (BH)max = 17.24 MGOe.

[0066] Example 7: Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1, except that the atomic content of Cu was adjusted, as shown in Table 2.

[0067] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.64 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.57 kgs, Hcj = 6.15 KOe, (BH)max = 18.05 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, measured by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 8 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'PertPro) and a benchtop scanning electron microscope (Phenom ProX).

[0068] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0069] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment at a temperature of 600°C for 1 hour. The sample was then cooled and removed from the furnace.

[0070] The diffusion thickness of the outermost Sm-Fe-Cu phase in the composite magnet is 50 nm. The outer Sm... 100-t Cu t The phase encapsulation thickness is 49nm.

[0071] The density of the composite magnet was tested to be 6.84 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 7.98 KGs, Hcj = 12.98 KOe, (BH)max = 15.76 MGOe.

[0072] Comparative Example 1: Heat treatment temperature different from Example 1 Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1.

[0073] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.32 g / cm³. 3The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 9.18 kgs, Hcj = 5.18 KOe, (BH)max = 19.45 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, as determined by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 0.5 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'Pert Pro) and a benchtop scanning electron microscope (Phenom ProX).

[0074] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0075] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment at a temperature of 500°C for 1 hour. The sample was then cooled and removed from the furnace.

[0076] The density of the composite magnet was tested to be 6.61 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.11 KGs, Hcj = 4.57 KOe, (BH)max = 17.67 MGOe.

[0077] Comparative Example 2: Heat treatment temperature different from Example 1 Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1.

[0078] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.59 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.86 kg / s, Hcj = 5.97 KOe, (BH)max = 18.56 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, as determined by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 0.5 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'Pert Pro) and a benchtop scanning electron microscope (Phenom ProX).

[0079] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0080] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment at 550℃ for 1 hour, and then cooled and removed from the furnace. The density of the composite magnet was tested to be 6.87 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 7.99 KGs, Hcj = 5.28 KOe, (BH)max = 17.19 MGOe.

[0081] Comparative Example 3: Heat treatment temperature different from Example 1 Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1.

[0082] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.47 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.51 kg / s, Hcj = 4.51 KOe, (BH)max = 16.59 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, as determined by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 0.5 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'Pert Pro) and a benchtop scanning electron microscope (Phenom ProX).

[0083] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0084] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment at 750℃ for 1 hour, and then cooled and removed from the furnace. The density of the composite magnet was tested to be 6.85 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 7.92 KGs, Hcj = 13.24 KOe, (BH)max = 15.97 MGOe.

[0085] Comparative Example 4: Step (1) Preparation of composite magnetic powder: The glass bottle was pre-filled with 3mm agate beads, and commercial 1000-mesh Cu powder was mixed with Sm powder with a particle size ≤5μm from Example 1. 11.1 Fe77.8 V 11.1 (at%) magnetic powder was mixed with agate beads in a glass bottle, and then the powder was separated from the agate beads using a sieve. The ratio of agate beads to powder was 1:10. The entire mechanical mixing process was carried out in a glove box with an oxygen content of less than 10 ppm. Finally, a composite magnetic powder containing 0.5 at% Cu was prepared.

[0086] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.52 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 9.57 kgs, Hcj = 5.89 KOe, (BH)max = 20.89 MGOe. For the mechanically mixed magnetic powder, the copper (Cu) content, as determined by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 0.5 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'PertPro) and a benchtop scanning electron microscope (Phenom ProX).

[0087] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0088] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment, and then cooled and removed from the furnace. The heat treatment temperature was 800℃, and the heat treatment time was 1 hour. The density of the composite magnet was tested to be 6.61 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 7.82 kgs, Hcj = 10.57 KOe, (BH)max = 15.78 MGOe. The Sm values ​​before and after heat treatment in Examples 13 and 14 were compared. 11.1 Fe 77.8 V 11.1 The magnetic properties of the (at%) / Cu composite magnet were tested, and the results are shown in Table 1.

[0089] Table 1: Magnetic performance test results of composite magnets prepared by low-temperature hot pressing before and after heat treatment.

[0090]

[0091] Table 1 shows the Sm before and after heat treatment. 11.1 Fe 77.8 V 11.1The magnetic property data of the (at%) / Cu composite magnet show that the untreated magnet has Hcj ~ 5 KOe, (BH)max ~ 20 MGOe, and Br ~ 10 KGs. When the heat treatment temperature is between 500-550℃, the coercivity after heat treatment is lower than before. When the heat treatment temperature reaches 600-800℃, the coercivity of the magnet shows a significant increase. When the heat treatment temperature reaches 550℃, the coercivity still does not increase, and is even slightly lower than before heat treatment, while the decrease in remanence and maximum energy product also increases significantly. If the heat treatment temperature is too low or the time is too short, this will cause Cu to fail to combine with Sm. 11.1 Fe 77.8 V 11.1 (at%) Sm escaping from the magnetic powder surface interdiffusion to form Sm 100-t Cu t Layer, while Cu has difficulty diffusing into Sm 11.1 Fe 77.8 V 11.1 (at%) A Sm-Fe-Cu layer is formed on the surface of the magnetic powder.

[0092] When the heat treatment temperature is too high, Cu will diffuse excessively into the magnetic powder, forming an excessively thick Sm-Fe-Cu phase intermediate diffusion layer and a low-melting-point alloy Sm. 100-t Cu t Phase, excessively thick Sm-Fe-Cu intermediate diffusion layer and outer Sm 100-t Cu t The presence of Sm enriches the surface layer, which reduces the amount of Sm in the core and makes it easier for the α-Fe phase to appear. The generated αFe may still act as a nucleation site for reverse magnetic domains, thereby reducing the coercivity of the magnet. Therefore, excessively high heat treatment temperature will cause the coercivity to decrease relative to the optimal temperature, but it is still significantly higher than that in the untreated state.

[0093] Although thickening the Sm-Fe-Cu intermediate diffusion layer does not reduce the anisotropy at the powder grain boundaries, and it hinders magnetic domain reversal during demagnetization, thus increasing the coercivity of the composite magnet, excessively thick Sm-Fe-Cu intermediate diffusion layer formation during heat treatment increases the proportion of non-magnetic phases, affecting other magnetic properties of the magnet. Furthermore, a thinner Sm-Fe-Cu intermediate diffusion layer... 100-t Cu t This is detrimental to the densification process of the magnet, therefore it is necessary to limit the diffusion thickness of the Sm-Fe-Cu phase to improve the high coercivity of the composite magnet. When the heat treatment temperature is further increased, the Sm... 11.1 Fe 77.8 V 11.1The thermodynamic tendency of (at%) high-temperature decomposition will also increase. A comparison of the magnetic properties of hot-pressed magnets with mechanically mixed magnetic powder before and after heat treatment reveals that, with the same Cu content, hot-pressed magnets coated with Cu magnetic powder exhibit better coercivity after heat treatment. This indicates that improving the uniformity of Cu and magnetic powder dispersion is also one of the conditions for forming a complete "sandwich structure" core-shell structure after heat treatment.

[0094] Comparative Example 5: Cu-free compared to Example 1 Step (1) Preparation of composite magnetic powder: Sm uncoated with Cu was selected from Example 1 11.1 Fe 77.8 V 11.1 (at%) magnetic powder (particle size: ≤5μm).

[0095] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.73 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 9.31 kg / s, Hcj = 6.01 KOe, (BH)max = 21.78 MGOe. For the uncoated Cu magnetic powder, the copper (Cu) content, as measured by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 0 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'PertPro) and a benchtop scanning electron microscope (Phenom ProX).

[0096] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0097] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment, and then cooled and removed from the furnace. The heat treatment temperature was 600℃, and the heat treatment time was 1 hour. The density of the composite magnet was tested to be 6.86 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.23 ​​KGs, Hcj = 5.57 KOe, (BH)max = 15.96 MGOe.

[0098] Comparative Example 6: Cu content increased compared to Example 1 Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1, except that the atomic content of Cu was adjusted, as shown in Table 2.

[0099] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.56 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.87 kg / s, Hcj = 5.61 KOe, (BH)max = 18.67 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, as determined by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 10 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'PertPro) and a benchtop scanning electron microscope (Phenom ProX).

[0100] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0101] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment, and then cooled and removed from the furnace. The heat treatment temperature was 600℃, and the heat treatment time was 1 hour. The density of the composite magnet was tested to be 6.69 g / cm³. 3 The magnetic properties of the magnets were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 6.93 KGs, Hcj = 14.27 KOe, (BH)max = 13.36 MGOe. The magnetic properties of the composite magnets prepared by low-temperature hot pressing in Examples 2 and 47, and Comparative Examples 5 and 6, were tested before and after heat treatment, and the results are shown in Table 2.

[0102] Table 2: Magnetic property test results of composite magnets prepared by low-temperature hot pressing before and after heat treatment

[0103] Table 2 shows the magnetic properties of hot-pressed magnets coated with magnetic powder of different Cu contents before and after heat treatment. It can be seen that for magnets with different Cu contents at the same heat treatment temperature (600℃), the initial Hcj of the composite magnet before heat treatment was approximately 6 KOe, (BH)max was approximately 21 MGOe, and Br was approximately 9 KGs. After heat treatment, when the Cu content was between 0.5 and 10 at%, the coercivity increased by a maximum net 2.38 times while ensuring a small decrease in remanence and maximum energy product. However, when the Cu content was 10 at.% (Comparative Example 6), although the increase in coercivity was significant, the remanence and maximum energy product decreased substantially. This is because with the increase in Cu content, Sm is formed after heat treatment. 100-t Cu tThe core-shell structure of the phase-coated magnetic powder is more complete. This structure prevents exchange coupling between adjacent magnetic powders, thereby improving the coercivity of the magnet. When the Cu content is excessive, during the heat treatment process, some Cu does not participate in the reaction but diffuses into the interior of the magnetic powder or exists between the magnetic powders. The presence of the non-magnetic Cu phase will greatly reduce the remanence of the magnet, thus causing a decrease in magnetic properties.

[0104] Example 8: Sm 7.7 Ce 1.1 Zr 2.2 (Fe 0.8 Co 0.2 ) 85.2 Ti 3.7 (at%) Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1, except that the type of core magnetic powder was adjusted, and its composition was Sm. 7.7 Ce 1.1 Zr 2.2 (Fe 0.8 Co 0.2 ) 85.2 Ti 3.7 (at%), see Table 3.

[0105] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.86 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 9.98 kg / s, Hcj = 6.86 KOe, (BH)max = 18.51 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, as determined by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 0.5 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'Pert Pro) and a benchtop scanning electron microscope (Phenom ProX).

[0106] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0107] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment, and then cooled and removed from the furnace. The heat treatment temperature was 600℃, and the heat treatment time was 1 hour. The density of the composite magnet was tested to be 7.20 g / cm³. 3The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 8.63 KGs, Hcj = 15.01 KOe, (BH)max = 11.46 MGOe.

[0108] Example 9: Sm 8.8 Zr 2.2 Fe 81.6 Ti 7.4 (at%) Step (1) Preparation of composite magnetic powder: The composite magnetic powder was prepared as described in Example 1, except that the type of core magnetic powder was adjusted, and its composition was Sm. 8.8 Zr 2.2 Fe 81.6 Ti 7.4 (at%), see Table 3.

[0109] Step (2) Low-temperature hot pressing to prepare composite magnets: The low-temperature hot pressing process for preparing the composite magnet is as described in Example 1. The composite magnet was tested and found to have a thickness of 25 mm and a density of 6.57 g / cm³. 3 The magnetic properties of the magnet were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 10.75 kgs, Hcj = 5.73 KOe, (BH)max = 19.52 MGOe. For the copper-coated magnetic powder, the copper (Cu) content, as determined by energy-dispersive X-ray fluorescence spectrometry (XRF, model ZSX PrimusⅡ), was 0.5 at%. Microstructure and morphology were studied using X-ray diffraction (XRD, X'Pert Pro) and a benchtop scanning electron microscope (Phenom ProX).

[0110] Step (3) Composite magnet encapsulation: The specific steps for packaging the composite magnet are as described in Example 1.

[0111] Step (4) Heat treatment (annealing): The quartz tube-encapsulated sample obtained in step (3) was placed in a heat treatment furnace for heat treatment, and then cooled and removed from the furnace. The heat treatment temperature was 600℃, and the heat treatment time was 1 hour. The density of the composite magnet was tested to be 6.97 g / cm³. 3 The magnetic properties of the magnets were measured using an AMT4 permanent magnet parameter measuring instrument: Br = 9.65 KGs, Hcj = 17.16 KOe, (BH)max = 12.96 MGOe. The magnetic properties of the composite magnets prepared by low-temperature hot pressing in Examples 1, 8, and 9 were tested before and after heat treatment, and the results are shown in Table 3.

[0112] Table 3: Magnetic property test results of composite magnets prepared by low-temperature hot pressing with different magnetic powder cores before and after heat treatment

[0113] Table 3 shows the magnetic properties of hot-pressed magnets coated with different core magnetic powders before and after heat treatment. For magnets with the same Cu content at the same heat treatment temperature (600℃), the initial Hcj of the composite magnet before heat treatment is approximately 5 KOe, (BH)max is approximately 20 MGOe, and Br is approximately 10 KGs. After heat treatment, for magnets with the same Cu content and different core magnetic powder compositions, while the remanence and maximum energy product of some components decrease significantly, the highest net increase in coercivity is nearly 2 times. This indicates that when a Cu layer is deposited on the surface of different core magnetic powders, it will react with the rare earth element Sm volatilized from the magnetic powder surface during heat treatment to form Sm. 100-t Cu t During this process, Cu elements gradually diffuse into the magnetic powder core to form the Sm-Fe-Cu phase. The resulting non-magnetic dual-phase coating prevents the exchange coupling between adjacent magnetic powders, resulting in a significant improvement in the material's coercivity. However, the negative impact on remanence and maximum energy product varies depending on the composition.

[0114] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

Claims

1. A samarium-based rare-earth permanent magnet bulk material, characterized in that, The samarium-based rare-earth permanent magnet bulk material is composed of grains with a core-shell structure, with (Sm x A y Zr z ) a (Fe 1-b D b ) d M g The grain forms the core, which is successively filled with Sm-Fe-T nonmagnetic phase and Sm from the inside out. 100-t T t (at%) of nonmagnetic phase coating, where 0≤t≤90(at%); The samarium-based rare earth permanent magnet bulk material is (Sm x A y Zr z ) a (Fe 1-b D b ) d M g T m Where A is one or more of Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; D is one of Co and Ni; M is one or more of Ti, V, Mo, Al, Si, Nb, B, C, Mn, and W; and T is one or more of Ag, Cu, Zn, and Sn. Where x+y+z=1, 0≤y≤1, 0≤z≤0.5; a=(100-m) / 13 (at%); 0≤b≤1; (100-m)*9 / 13 (at%)≤d≤(100-m)*11.5 / 13 (at%); (100-m) / 26 (at%)≤g≤(100-m)*3 / 13 (at%); (d+g)*13 / (100-t)=12; 0≤m≤10 (at%).

2. The samarium-based rare-earth permanent magnet bulk material according to claim 1, characterized in that, The diameter of the grain is 0.55 μm.

3. The samarium-based rare-earth permanent magnet bulk material according to claim 1, characterized in that, Sm-Fe-T nonmagnetic phase and Sm in grains 100-t T t The thickness of the non-magnetic phase (at%) is no greater than 50 nm, and the total thickness of the shell is no greater than 100 nm.

4. The samarium-based rare-earth permanent magnet bulk material according to claim 1, characterized in that, Its density is 6.8-7.9 g / cm³. 3 Intrinsic coercivity ≥10kOe, maximum energy product ≥15MGOe.

5. A method for preparing the samarium-based rare-earth permanent magnet bulk material as described in claim 1, characterized in that, With (Sm x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M g Magnetic powder particles are used as raw materials, and a layer of metal is coated on the surface. The metal is one of Ag, Cu, Zn, and Sn. Then, the particles are oriented and pressed by magnetic field. Then, cold isostatic pressing is performed to form a cold blank magnet. The cold blank magnet is then placed in a hot pressing mold for hot pressing. Finally, the hot-pressed magnet is packaged and then placed in a heat treatment furnace for heat treatment to obtain samarium-based rare earth permanent magnet bulk material. Where e represents the amount of rare earth element compensation, 0≤e≤1.

6. The method according to claim 5, characterized in that, In (Sm x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M g The method of coating metal with magnetic powder particles is one of the following: vapor deposition, liquid deposition, electroplating, sputtering, evaporation plating, ion plating, spraying, chemical plating, immersion plating, thermal spraying, and laser cladding.

7. The method according to claim 5, characterized in that, (Sm x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M g The preparation method of magnetic powder particles is one of the following: spray pyrolysis-reduction diffusion method, alloy melting and strip casting method, alloy melting hydrogen embrittlement method, co-precipitation-reduction diffusion method, and high-energy alloying.

8. The method according to claim 5, characterized in that, The heat treatment temperature is 600-750℃, and the annealing time is 0.5-3h.

9. The method according to claim 5, characterized in that, (Sm x(1+e) A y(1+e) Zr z ) a (Fe 1-b D b ) d M g The percentage of metal atoms coated on the surface of magnetic powder particles is 0.1-10 at.

10. An application of the samarium-based rare earth permanent magnet bulk material as described in claim 1.

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