A rare earth iron-carbon based hot deformed magnet and a method for manufacturing the same

Abstract

The application relates to a rare earth iron-carbon-based hot-deformation magnet and a preparation method thereof, and belongs to the technical field of permanent magnet materials. The magnet is prepared through a rapid quenching-heat pressing-hot deformation-annealing heat treatment process. The rare earth iron-carbon-based hot-deformation magnet prepared by adopting the process is composed of RE2(Fe,M) 14 (C,B) main phase and RE6Fe 13 Ga phase, rare earth-rich phase, contains a small amount of RE2Fe 17 C x , alpha-Fe, rare earth oxides and rare earth carbides. The magnet design optimizes the grain boundary phase by introducing Ga, accurately matches the hot deformation temperature and the main phase solid-state reaction temperature through process control, and successfully realizes high comprehensive magnetic properties without adding heavy rare earth elements.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet materials technology, specifically relating to a rare earth iron-carbon based hot-deformation magnet and its preparation method, and particularly to a magnet with RE2(Fe,M) as its main phase. 14 (C,B) heat-deformable magnet. Background Technology

[0002] Rare earth permanent magnets have wide applications in fields such as motors, medical equipment, and new energy due to their excellent magnetic properties. While traditional neodymium iron boron (Nd-Fe-B) magnets possess high energy products, their coercivity is relatively low, requiring the addition of heavy rare earth elements to improve coercivity and meet the demands of high-temperature applications. This results in high costs for high-performance magnets and a strong dependence on heavy rare earth resources. Therefore, obtaining high-coercivity magnets without adding heavy rare earth elements has become an important development direction in this field.

[0003] RE2Fe 14 The magnetocrystalline anisotropy field of the C-type compound is significantly higher than that of RE2Fe. 14 Compound B. This high magnetocrystalline anisotropy provides a foundation for achieving high coercivity under heavy rare-earth-free conditions, making it a preferred material for developing next-generation high-performance permanent magnet materials without heavy rare-earth elements. However, RE2Fe 14 C-type compounds can only be obtained through solid-state reactions at high temperatures, and the solid-state reactions in smelting and casting ingots can take weeks or even longer. Therefore, the traditional preparation of RE2Fe... 14 The method for obtaining C-type compounds involves preparing thin strips through rapid melt quenching, followed by short-time heat treatment at high temperature. This results in only RE₂Fe being obtained. 14 It is difficult to obtain high-performance anisotropic bulk magnets with a wider range of applications from isotropic powder materials of C-type compounds.

[0004] Patent document (CN100514512C) introduces carbon elements during the preparation of the rapid quenching strip. Only the rapidly quenched strip after heat treatment and crystallization undergoes hot deformation. The purpose of introducing carbon is to refine the grains and optimize the microstructure, rather than to form RE2Fe. 14 C phase. This patent embodiment only provides performance data for the rapidly quenched strip after heat treatment, without disclosing the phase composition or magnetic property parameters of the hot-deformed magnet. Similarly, although patent documents (CN104835641A), (CN102714082A), and (CN108257753A) have prepared hot-deformed magnets by performing a hot-deformation process on carbon-containing rapidly quenched strips, the main phase of their magnets is still RE2Fe. 14 B and C are added only as auxiliary elements and do not form the target phase RE2Fe14C, ultimately forming carbon-modified RE2Fe. 14 B magnet, not strictly speaking RE2Fe.14 C magnet. Summary of the Invention

[0005] To address the existing problems of rare earth iron-carbon based alloy hot-deformation magnets, this invention proposes a rare earth iron-carbon based hot-deformation magnet and its preparation method. The preparation process of this invention can be applied in engineering.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a rare-earth iron-carbon based hot-deformation magnet with the chemical formula RE. x Fe 100-y-x-z-w M y C z B w RE primarily consists of one or more of La, Ce, Pr, and Nd. M represents Ga and trace amounts of alloying elements such as Al, Si, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Si, Zr, Nb, and Ag, with Ga being essential and its y-component value not less than 0.15. The mole fractions x, y, z, and w satisfy the following inequalities: 10 ≤ x ≤ 18; 0.3 ≤ y ≤ 5; 2 ≤ z ≤ 5.5; 2 ≤ w ≤ 4. C is first smelted with metals such as Fe to form a pre-alloy, and then enters the alloy during the smelting process, participating in the formation of RE2(Fe,M). 14 (C,B) principal phase.

[0008] For example, the general chemical formula of the hot-deformation magnet based on rare-earth iron-carbon alloy is:

[0009] Pr9Nd7Fe 73.62 Co2Al 0.8 Cu 0.15 Ga 0.25 Zr 0.18 B2C5, La2Pr6Nd2Fe 82.55 Ga 0.2 Cr 0.1 Ti 0.1 Nb 0.05 B4C3, Ce3Pr7Nd4F e78 Si 0.3 Ga 0.3 Ti 0.2 Cu 0.2 B3C4, LaCe3Pr9Nd5Fe 74.35 Ga 0.35 Mn 0.15 Ti 0.1 Nb 0.05 B2C5, La2Ce5Pr5Nd3F e77.3 Ga 0.15 Ni0.2 Nb 0.05 Cu 0.3 B4C3, LaCe3Pr6Nd4F e78 Ga 0.35 V 0.2 Si 0.3 Ti 0.1 Nb 0.05 B4C3.

[0010] The rare-earth iron-carbon based hot-deformation magnet prepared by the process of this invention is mainly composed of RE2(Fe,M). 14 (C,B) principal phase and RE6Fe 13 Composed of Ga phase and rare earth-rich phase, with a small amount of RE2Fe. 17 C x α-Fe, rare earth oxides and rare earth carbides; the main phase RE2(Fe,M) 14 (C,B) mass fraction ≥85wt.%, RE6Fe 13 The Ga phase accounts for 3-5 wt.% of the total mass, and RE2Fe 17 C x The contents of other phases, such as α-Fe, rare earth oxides, and rare earth carbides, are ≤3 wt.%. These phases are generated during smelting and rapid quenching, rather than being added externally, and their contents can be adjusted through heat treatment processes to improve the magnet's performance. RE2(Fe,M) 14 (C,B) principal phase is along <001> The preferred orientation of the lath-shaped nanocrystal structure has an average grain size of about 200 nm, and the carbon content in the main phase should account for more than 90% of the total carbon content.

[0011] The present invention also provides a process for preparing the above-mentioned hot-deformation magnet based on rare-earth iron-carbon alloy, comprising the following steps:

[0012] 1) According to the general formula RE x Fe 100-y-x-z-w M y C z B w Weigh the raw materials, of which rare earth should be added at 1-3 w.t.% loss on ignition based on the theoretical amount, and C element should be added in the form of Fe-C alloy;

[0013] 2) The raw materials are melted into alloy ingots, and then a rapidly quenched strip of amorphous and nanocrystalline mixture is prepared by rapid melt quenching, followed by mechanical crushing to obtain magnetic powder.

[0014] 3) The magnetic powder prepared in 2) is loaded into a mold, cold-pressed and then hot-pressed to make the magnetic powder dense and obtain a blank;

[0015] 4) The blank obtained in 3) is subjected to hot deformation to obtain a primary hot-deformed magnet;

[0016] 5) The primary hot-deformed magnet described in 4) is heat-treated and rapidly cooled to obtain the final hot-deformed magnet.

[0017] Step 2) of this invention does not limit the smelting method, as long as a uniformly composed ingot can be obtained. For example, the smelting is induction melting.

[0018] In step 2) of this invention, the method of crushing the rapid quenching belt is not limited. The crushed magnetic powder can be passed through a 50-150 mesh sieve, preferably 80 mesh. For example, the crushing is grinding crushing.

[0019] Step 2) The rapid quenching process involves melting raw materials according to a general chemical formula, such as through arc melting or induction melting, to obtain a starting ingot. The starting ingot should be melted at least three times to ensure uniform composition. The ingot is then broken and placed into a quartz tube with an open bottom, the tube opening 3-5 mm away from the copper roller. A vacuum is then applied to the rapid quenching furnace cavity to achieve a vacuum level of 2 × 10⁻⁶. -4 ~9×10 -4 Pa; then, high-purity argon gas is introduced into the cavity to achieve a pressure difference of 60-90 kPa between the inside and outside of the cavity; the heating power supply is turned on with a current of 950 A to melt the ingot in a protective atmosphere, and the molten alloy is sprayed onto a rotating copper roller to obtain a rapid quenching strip; the roller speed is 40-45 m / s. Finally, a rapid quenching strip with uniform thickness of 150-350 μm is obtained, mainly containing a uniformly composed amorphous phase and nanocrystalline particles distributed within the amorphous phase;

[0020] Furthermore, the hot pressing process in step 3) should be carried out within 3 × 10 -3 ~8×10 -3 The process is carried out under a vacuum of Pa, with a pressure of 450-550 MPa applied at 550-650°C and held for 2-10 minutes, preferably 3-6 minutes, to obtain a preliminarily dense hot-pressed blank.

[0021] Furthermore, the hot deformation process in step 4) should be within 3×10 -3 ~8×10 -3 The process is carried out under a vacuum of 100 MPa, and the heat deformation temperature should be near the solid-state reaction temperature of the main phase, which is 90% to 105% of the phase transformation temperature, preferably 770 to 830°C. The deformation pressure is 50 to 250 MPa, preferably 100 to 250 MPa, and the deformation amount is 70 to 95%, preferably 70 to 85%.

[0022] Furthermore, in step 5), the heat treatment process involves annealing at 700–900°C for 0.5–5 minutes under a high-purity argon atmosphere. The preferred heat treatment temperature is 800°C, and the preferred heat treatment time is 2 minutes.

[0023] Furthermore, the present invention does not limit the method of rapid cooling, as long as the rapid cooling effect can be achieved. For example, the preferred rapid cooling process of the present invention is ice-water rapid quenching.

[0024] Furthermore, steps 1), 2), 3), 4), and 5) are all performed under vacuum or a protective atmosphere.

[0025] The principle of this invention is as follows:

[0026] This invention provides a rare-earth iron-carbon (RE-Fe-C) based hot-deformation magnet and its preparation method. The core principle is as follows: First, a rapid quenching band with an amorphous matrix and containing nanocrystals is directly obtained through a high-speed rapid quenching process. This structure significantly improves the efficiency of subsequent solid-state reactions and ensures compositional uniformity. Then, by introducing elements such as Ga to optimize the alloy composition and by coordinating the solid-state reaction and hot deformation processes under low-temperature and high-pressure conditions, a bulk magnet with high anisotropy and excellent performance is successfully prepared. Finally, low-temperature heat treatment is used to optimize the phase composition and microstructure, further enhancing the magnetic properties. Compared with existing technologies, the significant advantages of this invention are: 1) Eliminating the need for rapid quenching band crystallization pretreatment, shortening the process flow; 2) Optimizing the magnet microstructure to form uniformly sized lath-shaped nanocrystals; 3) By precisely matching the hot deformation temperature and the solid-state reaction temperature, the solid-state reaction and hot deformation processes are coordinated, reducing the preparation steps; 4) The introduction of Ga forms an antiferromagnetic RE6Fe. 13 Ga phase effectively weakens the ferromagnetic coupling between the main phase and the grain boundary, significantly improving coercivity without the need for heavy rare earth elements; 5) No heavy rare earth elements need to be added to the magnet, reducing costs and saving heavy rare earth resources. Attached Figure Description

[0027] The accompanying drawings are provided to help illustrate various aspects of the invention. The described embodiments and corresponding drawings are merely illustrative examples, intended to help understand the core concepts of the invention, and not to limit the specific implementation methods or scope of protection of the invention. The drawings are as follows:

[0028] Figure 1 The TEM test results are for the amorphous fast-quenched strip obtained in step 1) of Example 1.

[0029] Figure 2 The XRD test results are for the rare earth iron-carbon based hot deformable magnet obtained in step 4) of Example 1.

[0030] Figure 3 The results are from the powder XRD refinement test of the rare earth iron-carbon based hot deformable magnet obtained in step 4) of Example 1.

[0031] Figure 4 The TEM test results are for the rare earth iron-carbon based hot-deformation magnet obtained in step 4) of Example 1.

[0032] Figure 5 The powder XRD test results are for the nanocrystalline rapid quenching strips obtained in step 1) of Comparative Example 1.

[0033] Figure 6 The results are SEM images of the cross-section of the nanocrystalline rapid quenching strip obtained in step 1) of Comparative Example 1.

[0034] Figure 7 The SEM test results are for the rare earth iron-carbon based hot-deformation magnets obtained in step 4) of Comparative Example 1. Detailed Implementation

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0037] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0038] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0039] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0040] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0041] All raw materials used in the embodiments of this invention were obtained through commercial purchase.

[0042] In embodiments of the present invention, "high-purity argon" refers to argon with a purity of 99.999% or higher.

[0043] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0044] The technical solution of the present invention will be further illustrated by the following embodiments.

[0045] Example 1

[0046] This embodiment provides a fabrication process for a rare-earth iron-carbon based hot-deformation magnet, the steps of which are as follows:

[0047] 1) According to the general chemical formula Pr9Nd7Fe 73.62 Co2Al 0.8 Cu 0.15 Ga 0.25 Zr 0.18 The raw materials with a B2C5 ratio are induction melted to obtain a starting ingot. The ingot is crushed and loaded into a melt rapid quenching device with a copper roller speed of 45 m / s to obtain a rapid quenching strip that is a mixture of amorphous and nanocrystalline materials. The rapid quenching strip is crushed and passed through an 80-mesh sieve to obtain rapid quenching magnetic powder.

[0048] 2) The magnetic powder prepared in step 1) is loaded into a mold, cold-pressed and compacted, and then hot-pressed and sintered in an induction hot press furnace. The hot-pressing temperature is 600℃, and the hot-pressing process lasts for 3×10⁻⁶ days. -3 ~8×10 -3 The process was carried out under a vacuum of 500 MPa, with a heating rate of 60 °C / min and a pressure of 500 MPa. After the blank was densified, it was held at this temperature for 2 minutes to obtain a preliminarily densified hot-pressed blank.

[0049] 3) The hot-pressed blank prepared in 2) is placed into a mold and subjected to hot deformation treatment in an induction hot press furnace to obtain a hot-deformed magnet with a nanocrystalline structure. The hot deformation process is carried out at 3×10⁻⁶ ℃. -3 ~8×10 -3 The process was carried out under a vacuum of 150 MPa, with a heat distortion temperature of 800℃, a heating rate of 60℃ / min, a heat distortion pressure of 150 MPa, a deformation amount of 75%, and a holding time of 3 min.

[0050] 4) The hot-deformed magnet prepared in 3) was annealed in a high-purity argon atmosphere at a temperature of 800℃ for 2 minutes.

[0051] The transmission electron microscope image of the amorphous rapid quenching zone obtained in step 1) is as follows: Figure 1 As shown, the composition of the rapid quenching zone is uniform, and the matrix phase is an amorphous phase containing nanocrystalline particles.

[0052] The XRD test of the rare earth iron-carbon based hot-deformation magnet obtained in step 4) is as follows: Figure 2 As shown, the magnet exhibits strong <001> Texture. Refined powder XRD patterns are shown below. Figure 3 As shown in Table 1, the mass fraction of different phases and the carbon content in the main phase are related. It can be seen that the main phase accounts for approximately 93.68% of the total content, and it also contains rare earth-rich phases and RE6Fe. 13 The contents of Ga phase, 2:17 phase, α-Fe, and rare earth carbide phase (PrC2) are all below 2%. TEM results of rare earth iron-carbon based hot-deformation magnets are as follows: Figure 4 As shown, the grains of the thermally deformable magnet exhibit a lath-like morphology and are uniformly distributed along the direction perpendicular to the pressure. At the same time, some small grains can also be observed in some localized areas, with an average grain size of about 200 nm.

[0053] Table 1 shows the mass fraction of different phases and the carbon content of the main phase in the XRD refinement results of Example 1.

[0054]

[0055] Example 2

[0056] This embodiment provides a preparation process for a rare earth iron-carbon based hot-deformable magnet, which is the same as that in embodiment 1, except that the hot-pressing temperature in 2) is 550℃ and the hot-pressing pressure is 550MPa; and the hot-deformation temperature in 3) is 770℃, the hot-deformation pressure is 250MPa, the deformation amount is 70%, and the holding time is 6min.

[0057] Example 3

[0058] This embodiment provides a fabrication process for a rare-earth iron-carbon based hot-deformable magnet, similar to Embodiment 1, except that in 2) the hot-pressing temperature is 625℃ and the hot-pressing pressure is 475MPa; in 3) the hot-deformation temperature is 830℃, the hot-deformation pressure is 100MPa, the deformation amount is 80%, and the holding time is 5min.

[0059] Example 4

[0060] This embodiment provides a fabrication process for a rare-earth iron-carbon based hot-deformable magnet, similar to Embodiment 1, except that in 2) the hot-pressing temperature is 650℃ and the hot-pressing pressure is 450MPa; and in 3) the hot-deformation temperature is 850℃, the hot-deformation pressure is 50MPa, the deformation amount is 85%, and the holding time is 4min.

[0061] The magnetic properties of the rare-earth iron-carbon based hot-deformable magnets obtained in Examples 1-4 are shown in Table 2. The coercivity (H) of the hot-deformable magnets... cj The remanence reaches a maximum of 18.98 kOe when hot-pressed at 600℃ and 500MPa and hot-deformed at 800℃ and 150MPa, and the remanence (M) is [missing value].r ), saturation magnetization (M) s ), Maximum magnetic energy product ((BH) max The maximum values ​​reached were 139.82 emu / g and 37.89 MGOe when hot-pressed at 625℃ and 475 MPa and hot-deformed at 830℃ and 100 MPa, respectively.

[0062] Table 2 shows the magnetic properties of the heat-deformable magnets in Examples 1-4.

[0063]

[0064] Example 5

[0065] This embodiment provides a preparation process for a rare-earth iron-carbon based hot-deformation magnet, which is the same as in Embodiment 1, except that the general chemical formula in 1) is La2Pr6Nd2Fe. 82.55 Ga 0.2 Cr 0.1 Ti 0.1 Nb 0.05 B4C3.

[0066] Example 6

[0067] This embodiment provides a fabrication process for a rare-earth iron-carbon based hot-deformation magnet, similar to Embodiment 1, except that the general chemical formula in 1) is Ce3Pr7Nd4F. e78 Si 0.3 Ga 0.3 Ti 0.2 Cu 0.2 B3C4.

[0068] Example 7

[0069] This embodiment provides a fabrication process for a rare-earth iron-carbon based hot-deformation magnet, similar to Embodiment 1, except that the general chemical formula in 1) is LaCe3Pr9Nd5Fe. 74.35 Ga 0.35 Mn 0.15 Ti 0.1 Nb 0.05 B2C5.

[0070] Example 8

[0071] This embodiment provides a fabrication process for a rare-earth iron-carbon based hot-deformation magnet, which is the same as in Embodiment 1, except that the general chemical formula in 1) is La2Ce5Pr5Nd3F. e77.3 Ga 0.15 Ni 0.2 Nb 0.05 Cu 0.3 B4C3.

[0072] Example 9

[0073] This embodiment provides a fabrication process for a rare-earth iron-carbon based hot-deformation magnet, similar to Embodiment 1, except that the general chemical formula in 1) is LaCe3Pr6Nd4F. e78 Ga 0.35 V 0.2 Si 0.3 Ti 0.1 Nb 0.05 B4C3.

[0074] The powder XRD refinement results and carbon content in the main phase of the rare earth iron-carbon based hot-deformation magnets obtained in Examples 5-9 are shown in Table 3. The magnetic properties of the rare earth iron-carbon based hot-deformation magnets obtained in Examples 5-9 are shown in Table 4.

[0075] According to the refinement results, the main phase content of Examples 5-9 is all above 85%, and the impurity phases such as α-Fe are all below 3%.

[0076] Table 3 shows the mass fraction of different phases and the carbon content of the main phase in the XRD refinement results of Examples 5-9.

[0077]

[0078] Table 4 shows the magnetic properties of the heat-deformable magnets in Examples 5-9.

[0079]

[0080] Comparative Example 1

[0081] This comparative example provides a preparation process for a rare earth iron-carbon based hot-deformable magnet. The difference from Example 1 is that the speed of the rapid quenching copper roller in step 1) is 20 m / s, and the hot deformation temperature in step 3) is 700℃ and the hot deformation pressure is 30 MPa.

[0082] Comparative Example 2

[0083] This comparative example provides a process for preparing a heat-deformable magnet, which differs from Example 1 only in that the chemical formula is Pr9Nd7Fe. 73.62 Co2Al 0.8 Cu 0.15 Ga 0.25 Zr 0.18 B7.

[0084] Comparative Example 3

[0085] This comparative example provides a preparation process for a rare-earth iron-carbon based hot-deformation magnet, which differs from Example 1 only in that the chemical formula is Pr9Nd7Fe. 73.62 Co2Al 0.8 Cu 0.15 Ga0.25 Zr 0.18 BC6.

[0086] Comparative Example 4

[0087] This comparative example provides a preparation process for a rare-earth iron-carbon based hot-deformation magnet, which differs from Example 1 only in that the chemical formula is Pr9Nd7Fe. 73.87 Co2Al 0.8 Cu 0.15 Zr 0.18 B2C5.

[0088] The powder XRD finishing results and magnetic properties of Comparative Examples 1-4 are shown in Tables 5 and 6.

[0089] The key difference between Comparative Example 1 and Example 1 is that a lower rapid quenching speed (20 m / s) was used, a hot deformation process was carried out using crystallized nanocrystalline rapid quenching strips, and the hot deformation temperature was not near the solid-state reaction temperature range of the main phase. Figure 5 The powder XRD test results of the rapidly quenched ribbon prepared at a roller speed of 20 m / s show that the diffraction peaks are sharp, indicating that significant crystallization has occurred during the rapid quenching process at a lower roller speed. Figure 6 The image shows a cross-sectional SEM image of a rapidly quenched thin strip prepared at a rolling speed of 20 m / s, in which nanocrystalline grains can be observed in the fracture area. Figure 7 The SEM test results for Comparative Example 1 show that, compared to Example 1, the grain size is larger and more unevenly distributed, and it contains a large number of equiaxed crystals that are detrimental to magnetic properties. The powder XRD refinement results show that the mass fraction of the main phase has decreased significantly, and RE2Fe... 17 The increased mass fractions of C and PrC2 phases are likely due to the fact that the heat distortion temperature is much lower than the solid-state reaction temperature, resulting in a slower solid-state reaction rate and difficulty in the formation of the main phase. A large amount of C elements participate in the formation of RE2Fe. 17 The C phase and PrC2 phase further deteriorate the magnetic properties.

[0090] The key difference between Comparative Example 2 and Example 1 is that carbon was not introduced during the smelting process. Although Comparative Example 1 had a higher content of the main phase and contained antiferromagnetic RE6Fe... 13 The Ga phase was used, but the magnetic properties were still significantly different from those in Example 1. This may be due to RE2Fe. 14 The magnetocrystalline anisotropy of B compared to RE2Fe 14 A lower C content is detrimental to obtaining excellent magnetic properties.

[0091] The difference between Comparative Example 3 and Example 1 lies in the ratio of carbon and boron. After altering the carbon-boron ratio beyond the set value, the mass fraction of the main phase sharply decreased to 87.42 wt.%, while the α-Fe phase and RE2Fe phase, which deteriorated the magnetic properties, also showed negative effects. 17 Cx An increase in phase content is detrimental to obtaining good magnetic properties.

[0092] The key difference between Comparative Example 4 and Example 1 is the absence of Ga doping. Powder XRD analysis shows that, due to the lack of Ga, Comparative Example 3 failed to form the antiferromagnetic RE6Fe13Ga phase, thus failing to effectively weaken the ferromagnetic coupling between the main phase and grain boundaries, leading to a deterioration in coercivity.

[0093] Table 5 shows the mass fraction of different phases and the carbon content of the main phase in the XRD refinement results of Comparative Examples 1-4.

[0094]

[0095] Table 6 shows the magnetic properties of the heat-deformed magnets in Comparative Examples 1-4.

[0096]

Claims

1. A rare-earth iron-carbon based hot-deformation magnet, characterized in that, Its general chemical formula is RE x Fe 100-y-x-z-w M y C z B w RE is one or more of La, Ce, Pr, and Nd; M is one or more of Ga and trace alloying elements of Al, Si, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Si, Zr, Nb, and Ag, of which Ga is essential and the number of Ga corresponding to the y-part is not less than 0.15; the mole fractions x, y, z, and w satisfy the inequalities: 10 ≤ x ≤ 18; 0.3 ≤ y ≤ 5; 2 ≤ z ≤ 5.5; 2 ≤ w ≤ 4; C is first smelted with Fe metal to form a pre-alloy, and then enters the alloy during the smelting process to participate in the formation of RE2(Fe,M). 14 (C,B) Main phase; the carbon content in the main phase should account for more than 90% of the total carbon content.

2. A rare-earth iron-carbon based hot-deformation magnet according to claim 1, characterized in that, OnePr9Nd7Fe 73.62 Co2Al 0.8 Cu 0.15 Ga 0.25 Zr 0.18 B2C5, La2Pr6Nd2Fe 82.55 Ga 0.2 Cr 0.1 The 0.1 Nb 0.05 B4C3, Ce3Pr7Nd4F e78 Si 0.3 Ga 0.3 The 0.2 Cu 0.2 B3C4, LaCe3Pr9Nd5Fe 74.35 Ga 0.35 Mn 0.15 The 0.1 Nb 0.05 B2C5, La2Ce5Pr5Nd3F e77.3 Ga 0.15 Ni 0.2 Nb 0.05 Cu 0.3 B4C3, LaCe3Pr6Nd4F e78 Ga 0.35 V 0.2 Si 0.3 The 0.1 Nb 0.05 B4C3 3. A rare-earth iron-carbon based hot-deformation magnet according to claim 1, characterized in that, From RE2(Fe,M) 14 (C,B) principal phase and RE6Fe 13 Composed of Ga phase and rare earth-rich phase, with a small amount of RE2Fe. 17 C x α-Fe, rare earth oxides and rare earth carbides; the main phase RE2(Fe,M) 14 (C,B) mass fraction ≥85 wt.%, RE6Fe 13 The Ga phase accounts for 3-5 wt.% of the total mass, while RE2Fe 17 C x The contents of α-Fe, rare earth oxides, and other phases of rare earth carbides are ≤3 wt.%; RE2(Fe,M) 14 (C,B) principal phase is along <001> Lath-shaped nanocrystalline structures with preferred crystal orientation.

4. A rare-earth iron-carbon based hot-deformation magnet according to claim 3, characterized in that, It has a lamellar nanocrystalline structure with an average grain size of 200 nm.

5. A method for preparing a rare-earth iron-carbon based hot-deformation magnet according to any one of claims 1-4, comprising the following steps: 1) According to the general formula RE x Fe 100-y-x-z-w M y C z B w Weigh the raw materials, among which rare earth should be added at 1-3 w.t.% loss on ignition based on the theoretical amount, and C element should be added in the form of Fe-C alloy; 2) The raw materials are melted into alloy ingots, and then the melt is rapidly quenched to prepare a mixture of amorphous and nanocrystalline materials into a rapidly quenched strip, which is then mechanically crushed to obtain magnetic powder. 3) The magnetic powder prepared in 2) is loaded into a mold, cold-pressed and then hot-pressed to make the magnetic powder dense and obtain a blank; 4) The blank obtained in 3) is subjected to hot deformation to obtain a primary hot-deformed magnet; 5) The primary hot-deformed magnet described in 4) is heat-treated and rapidly cooled to obtain the final hot-deformed magnet.

6. The method according to claim 5, characterized in that, Step 2) describes induction melting; Step 2) There are no restrictions on the crushing method of the rapid quenching belt. The crushed magnetic powder can be passed through a 50-150 mesh sieve.

7. The method according to claim 5, characterized in that, Step 2) The rapid quenching process involves melting the raw materials according to the general chemical formula using either electric arc melting or induction melting to obtain a starting ingot. The starting ingot should be melted at least three times to ensure uniform composition. The starting ingot is then broken and placed into a quartz tube with an open bottom, the tube opening 3-5 mm away from the copper roller. A vacuum is then applied to the rapid quenching furnace cavity to achieve a vacuum level of 2 × 10⁻⁶. -4 ~9×10 -4 Pa; then high-purity argon gas is introduced into the cavity to make the pressure difference between the inside and outside of the cavity reach 60-90 kPa; the heating power supply is turned on with a current of 950 A to melt the ingot in a protective atmosphere, and the alloy melt is sprayed onto the rotating copper roller to obtain a rapid quenching strip; the roller speed of the copper roller is 40-45 m / s; finally, a rapid quenching thin strip with uniform thickness is obtained, with a thickness of 150-350 μm, containing a uniformly composed amorphous phase and nanocrystalline particles distributed in the amorphous phase.

8. The method according to claim 5, characterized in that, Step 3) The hot pressing process should be carried out within 3×10 -3 ~8×10 -3 The process is carried out under a vacuum of 450-550 MPa at 550-650℃ and held for 2-10 minutes to obtain a preliminarily dense hot-pressed blank.

9. The method according to claim 8, characterized in that, Keep warm for 3-6 minutes.

10. The method according to claim 5, characterized in that, Step 4) The intermediate heat deformation process should be within 3×10 -3 ~8×10 -3 The process is carried out under a vacuum of 100 MPa. The heat deformation temperature should be near the solid-state reaction temperature of the main phase, which is 90% to 105% of the phase transformation temperature. The deformation pressure is 50 to 250 MPa, and the deformation amount is 70 to 95%.

11. The method according to claim 5, characterized in that, Step 5) involves heat treatment, which is annealing at 700-900℃ for 0.5-5 min in a high-purity argon atmosphere.

12. The method according to claim 11, characterized in that, Heat treatment: Anneal at 800℃ for 2 min.

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