Method for improving coercive force and corrosion resistance of high-abundance rare earth strong magnetic alloy

Abstract

The invention provides a method for improving coercive force and corrosion resistance of high-abundance rare earth strong magnetic alloy, in the method, Zr-C composite nanocrystalline powder is added into alloy powder, ZrC is generated at the grain boundary through sintering, and ZrC and Zr which does not participate in reaction form a composite modifier Zrs (ZrC) 100-s. The strong magnetic alloy prepared through the method has the advantage of being clear in grain boundary, compared with an existing common sintered cerium-rich permanent magnet, the microstructure is more optimized, and therefore the strong magnetic alloy prepared through the method has higher coercive force and lower material cost; and meanwhile, chemical stable ZrC is used for blocking grain boundary corrosion, so that the corrosion resistance of the magnet is improved, and the corrosion-resistant alloy is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnetic materials, and specifically relates to a method for improving the coercivity and corrosion resistance of high-abundance rare-earth permanent magnetic alloys. Background Art

[0002] RE-Fe-B (RE = rare-earth elements such as Ce, Nd, Pr, etc.) alloys have permanent magnetic properties and are widely used as permanent magnetic alloys in fields such as new energy, electronic information, transportation, and medical devices. The material properties are closely related to the type and quantity of the rare-earth element RE. Among them, Ce is a high-abundance rare-earth element. After it replaces Nd and Pr, the cost can be significantly reduced, promoting the efficient and balanced utilization of rare-earth resources.

[0003] Cerium is the metal with the highest crustal abundance among the lanthanide rare-earth elements. Preparing a permanent magnetic alloy with Ce / RE≥10% is an important development direction of rare-earth permanent magnetic materials and has a huge market demand in the rapidly developing offshore wind power industry. However, high-abundance rare-earth RE-Fe-B permanent magnetic alloys have two disadvantages due to their high Ce content: one is that the coercivity (Hcj) of the material is relatively low. When Ce / RE = 40%, the Hcj of the magnet is about 7 kOe, which is lower than that of the magnet without Ce; the other is the poor intrinsic corrosion resistance of the alloy. To overcome these disadvantages, there are currently two ideas for improving the Hcj of the magnet: ① Utilize the fact that the magnetocrystalline anisotropy field of Dy(Tb)2Fe 14 B is much larger than that of Nd2Fe 14 B and Ce2Fe 14 B, and incorporate Dy and Tb into the magnet to increase Hcj. The disadvantage of this method is that the material cost is significantly increased; ② Improve Hcj by optimizing the multiphase microstructure of the magnet. Among them, the optimization of the microstructure includes: refining the main phase and improving the morphology and distribution of the grain boundary phase. The common strategy is material alloying, such as doping high-melting-point Nb, Zr, Ti, etc., that is, refining the main phase through grain boundary pinning, or doping low-melting-point Al, Cu, Ga, etc., that is, optimizing the grain boundary structure of the magnet by improving the fluidity of the liquid rare-earth-rich grain boundary phase during powder metallurgy and heat treatment. At the same time, these doping elements can also improve the corrosion resistance of the magnet. One reason is that they can passivate the rare-earth-rich grain boundary phase and reduce the potential difference between it and the main phase; the other reason is that the oxides formed during the corrosion process can play an isolation role. It can be seen that it is of great practical significance to modify the grain boundaries and regulate the organizational structure of high-abundance rare-earth permanent magnetic alloys.

[0004] At present, the transition metal Zr has been proven to be an effective element for refining the main phase. The effect of refining the main phase is related to its incorporation method and / or quantity, depending on the morphology, size, and distribution of its precipitates. If incorporated during the melting process, Zr will be distributed at grain boundaries and corners in the form of Zr-rich phases, Fe2Zr, or ZrB2 after going through the preparation steps of "melt reaction, rapid solidification by spinning, powder making, compacting, sintering, and heat treatment". These phases will damage the crystal structure of the main phase by consuming Fe and B in (Nd,Ce)2Fe 14 B, reducing the remanence and magnetic energy product. In addition, if there is an excessive amount of Zr, the accompanying α-Fe phase of its precipitates will also cause Hcj to decrease instead of increase. It can be seen that incorporating Zr through the melting process is significantly limited in enhancing the physical and chemical properties of the material. Summary of the Invention

[0005] In view of this, the present invention provides a method for enhancing the coercivity and corrosion resistance of high-abundance rare-earth permanent magnetic alloys. Specifically, it is a method of adding Zr-C composite nanocrystal powder to alloy powder and generating ZrC at grain boundaries through sintering, and ZrC and unreacted Zr form a composite modifier Zr s (ZrC) 100-s , effectively improving the coercivity and corrosion resistance of the material.

[0006] The technical solution of the present invention is as follows: A method for enhancing the coercivity and corrosion resistance of high-abundance rare-earth permanent magnetic alloys, which adds Zr-C composite nanocrystal powder to the alloy powder after melting to in-situ generate a composite modifier Zr s (ZrC) 100-s , where s represents the mass ratio of Zr in Zr s (ZrC) 100-s composite modifier, and 40.0 wt.% ≤ s ≤ 60.0 wt.%; The mass ratio of the composite modifier Zr s (ZrC) 100-s in the alloy powder is v, and 0.1 wt.% ≤ v ≤ 1.5 wt.%.

[0007] Preferably, the composition of the high-abundance rare-earth permanent magnetic alloy is [Ce x (Pr,Nd,Dy) y Fe 100-x-y-z-u (Ga,Al,Cu,Co) z B u 100-v [Zr s (ZrC) 100-s v ; where x, y, z, and u respectively represent the contents of Ce, (Pr,Nd,Dy), (Ga,Al,Cu,Co), and B elements in Ce​​x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u Mass ratio in the alloy powder; The value ranges of x, y, z, and u in the material composition system are as follows: 11.5 wt.% ≤ x ≤ 13.5 wt.%, 17.0 wt.% ≤ y ≤ 20.0 wt.%, 1.5 wt.% ≤ z ≤ 4.5 wt.%, 0.9 wt.% ≤ u ≤ 1.0 wt.%.

[0008] Preferably, the preparation method of the Zr-C composite nanocrystalline powder is as follows: S1. Weigh zirconium (Zr) powder and carbon (C) powder with a purity of 99.9% according to the ratio. The mass ratio of zirconium powder to carbon powder is 13.3 - 19.0:1. Prepare ethanol and zirconium stearate according to the total amount of zirconium powder and carbon powder. The weight - volume ratio (g / ml) of the total amount of zirconium powder and carbon powder to ethanol is 100:1.5 - 4.5; the mass ratio of the total amount of zirconium powder and carbon powder to zirconium stearate is 100:0.5 - 5.0. Mix ethanol and zirconium stearate to obtain a ball - milling process control agent. S2. Add WC cemented carbide balls, Zr powder, C powder, and the ball - milling process control agent into a vacuum ball - milling tank, then seal the cover, evacuate, and fill with high - purity argon, and carry out ball - milling. The ball - milling time is 80 - 160 hours, and the ball - milling speed is 250 - 450 revolutions per minute to prepare a highly active Zr - C composite nanocrystalline powder.

[0009] Preferably, in step S1, the average particle size of the zirconium powder is 10 μm; the average particle size of the carbon powder is 20 nm.

[0010] Preferably, in step S2, the mass ratio of WC cemented carbide balls to the total amount of zirconium powder and carbon powder is 5 - 25:1.

[0011] Preferably, the method for enhancing the coercivity and corrosion resistance of the high - abundance rare - earth high - coercivity alloy is as follows: Step 1. Prepare Ce x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u High - coercivity alloy powder; First, melt the metal Ce, Fe, and Pr - Nd, Dy - Fe, B - Fe alloy raw materials, then prepare a high - coercivity alloy rapid - solidification thin strip through the rapid - solidification and strip - casting process, and carry out hydrogen explosion to obtain coarsely crushed powder, and then carry out air - jet milling to prepare Ce with a particle size of 1.5 - 3.5 μm x(Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u Alloy powder; Step 2: In an oxygen-free environment, load the Zr-C composite nanocrystal powder and the Ce prepared in Step 1 x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u strong magnetic alloy powder into a vacuum tank, fill it with high-purity argon, and then perform powder mixing on a ball mill for 3 - 5 hours to obtain a uniformly mixed material of alloy powder and Zr-C nanocrystal powder; Step 3: Orient the mixed material prepared in Step 2 in a magnetic field of 1.5 - 2.5 T and form it under a pressure of 100 - 200 MPa to obtain a compact; After that, perform isostatic pressing on the compact at 200 - 400 MPa using a hydraulic press to prepare a green compact with a uniform stress distribution; Step 4: Put the green compact prepared in Step 3 into a vacuum sintering furnace with a vacuum degree of 10 -3 order of magnitude for sintering. The sintering temperature is 1020 - 1050 °C and the sintering time is 2.5 - 4.5 hours; During the sintering process, C and Zr react in-situ at the alloy grain boundaries to form ZrC. At the same time, the unreacted Zr and ZrC together constitute the magnet composite modifier Zr s (ZrC) 100-s ; After that, introduce argon for rapid cooling at a cooling rate of 6.5 °C / min and cool it to room temperature to obtain a high-density sintered strong magnetic alloy; Based on the binding tendency of Zr and C, by regulating the sintering thermal field, spherical ZrC compounds and needle-like zirconium-rich phases are in-situ synthesized at the alloy grain boundaries, and their distribution is regulated by subsequent heat treatment, a method for synergistically modifying the microstructure of high-abundance rare earth strong magnetic alloys by Zr and in-situ generated ZrC and enhancing the coercivity and corrosion resistance is proposed; Step 5: Perform two-stage tempering heat treatment on the prepared sintered strong magnetic alloy; First, load the sintered strong magnetic alloy into a vacuum heat treatment furnace for primary tempering. The tempering temperature range is 900 - 950 °C, the tempering time is 2.5 - 3.5 hours. After the heating is completed, introduce argon into the furnace and cool the magnet to room temperature at a cooling rate of 5 °C / min; After that, secondary tempering is carried out, and the tempering temperature range is 500 - 700 °C. The tempering time and cooling are the same as those of the primary tempering to prepare a high-abundance rare-earth permanent magnetic alloy, which has the characteristics of high coercivity and high corrosion resistance.

[0012] In the present invention, Zr-C composite nanocrystalline powder is prepared by a long-time mechanical alloying technique. After mixing the Zr-C composite nanocrystalline powder with alloy powder, a Ce-rich Nd-Fe-B permanent magnet with a Zr / ZrC synergistic grain boundary modification content of 0.1 - 1.5 wt% is prepared by powder metallurgy - heat treatment technology. The main features of the present invention are as follows: granular ZrC is in-situ generated and distributed in the intergranular region of the magnet together with acicular Zr. The two act synergistically on the permanent magnetic alloy, improving the coercivity and corrosion resistance of the material.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The method of the present invention is directed at a high-abundance rare-earth permanent magnetic alloy. Zr-C composite nanocrystalline powder is incorporated into the alloy powder, and the Zr-C composite nanocrystalline powder and the permanent magnetic alloy powder are sintered at a high temperature, so that ZrC is generated at the grain boundary. ZrC and the unreacted Zr together constitute the modifier Zr s (ZrC) 100-s ; among them, ZrC is a strengthening phase with high melting point, high hardness and high chemical stability. After being incorporated into the grain boundary, it can inhibit grain growth and optimize the magnetic domain structure, improving the corrosion resistance; at the same time, under the co-doping of Zr and ZrC, the two can give full play to the synergistic effect, further improving the coercivity and corrosion resistance of the material.

[0014] 2. The permanent magnetic alloy prepared by the present invention has the advantage of clear grain boundaries. Compared with the commonly used sintered Ce-rich permanent magnets in the prior art, the microstructure is more optimized. Therefore, the permanent magnetic alloy prepared by the method of the present invention has higher coercivity and lower material cost; at the same time, the corrosion resistance of the magnet is improved by using chemically stable ZrC to block grain boundary corrosion, and a corrosion-resistant alloy is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 It is the distribution pattern of Zr and in-situ ZrC in the permanent magnetic alloy of Example 1 in the magnet.

[0017] Figure 2 It is the demagnetization curve of the permanent magnetic alloy obtained in Example 1.

[0018] Figure 3 The polarization curve of the high-strength magnetic alloy obtained in Example 1 in the NaCl solution.

[0019] Figure 4 The comparison of the demagnetization curves of the high-strength magnetic alloy obtained in Comparative Example 1 and the high-strength magnetic alloy obtained in Example 1.

[0020] Figure 5 The comparison of the polarization curves of the high-strength magnetic alloy obtained in Comparative Example 1 and the high-strength magnetic alloy obtained in Example 1.

[0021] Figure 6 The comparison of the demagnetization curves of the high-strength magnetic alloy obtained in Comparative Example 2 and the high-strength magnetic alloy obtained in Example 1.

[0022] Figure 7 The comparison of the polarization curves of the high-strength magnetic alloy obtained in Comparative Example 2 and the high-strength magnetic alloy obtained in Example 1. Detailed implementation manners

[0023] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] In the present invention, Ce x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u In the preparation process of the alloy powder, the specific contents of the melting process, the rapid solidification and strip casting process, the hydrogen explosion and crushing process, and the air jet milling process can be found in "Ultra-Strong Permanent Magnets - Rare Earth System Permanent Magnet Materials" edited by Zhou Shouzeng and Dong Qingfei, Beijing: Metallurgical Industry Press, Second Edition in February 2004, pp. 158 - 159, pp. 498 - 504, pp. 326 - 332, pp. 508 - 511, pp. 170 - 172.

[0025] Example 1 A method for improving the coercivity and corrosion resistance of a high-abundance rare earth high-strength magnetic alloy. The high-strength magnetic alloy is [Ce x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u 100-v [Zr s (ZrC) 100-s ​​v , where x, y, z, and u respectively represent the mass ratios of Ce, (Pr, Nd, Dy), (Ga, Al, Cu, Co), and B elements in the Ce x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u alloy powder; In the material composition system, x = 12.0 wt.%, y = 19.0 wt.%, z = 2.0 wt.%, u = 0.9 wt.%; s represents the mass ratio of Zr in Zr s (ZrC) 100-s composite modifier, s = 50.0 wt.%; composite modifier Zr s (ZrC) 100-s in the alloy powder is v, v = 0.5 wt.%; The preparation process is as follows: Step 1, prepare Ce 12 (Pr, Nd, Dy) 19 Fe 66.1 (Ga, Al, Cu, Co)2B 0.9 high-magnetic alloy powder; First, melt the metal raw materials of Ce, Fe, Pr 25 Nd 75 , Dy 80 Fe 20 , B 19.5 Fe 80.5 alloy raw materials, then prepare high-magnetic alloy rapid-solidification thin strips by the rapid-solidification spinning process, and perform hydrogen explosion to obtain coarsely crushed powder, and then perform air jet milling to prepare alloy powder with a particle size of 1.5 - 3.5 μm; Step 2, the preparation method of Zr-C composite nanocrystalline powder is as follows: S1, weigh zirconium (Zr) powder and carbon (C) powder with a purity of 99.9%, and the mass ratio of zirconium powder to carbon powder is 15.0:1; Prepare ethanol according to the ratio of the total amount of zirconium powder and carbon powder to ethanol by weight volume (g / ml) of 100:3, prepare stearic acid according to the total amount of zirconium powder and carbon powder, and the mass ratio of stearic acid to the total amount of Zr powder and C powder is 3.0:100. Mix ethanol and stearic acid to obtain a ball milling process control agent; Among them, the average particle size of Zr powder is 10 μm; the average particle size of C powder is 20 nm; S2. Add WC hard alloy balls, Zr powder, C powder and a ball milling process control agent into a vacuum ball milling tank. The mass ratio of WC hard alloy balls to the total amount of zirconium powder and carbon powder is 10:1. Then cover the tank, evacuate it, fill it with high-purity argon, and carry out ball milling for 120 hours at a ball milling speed of 350 revolutions per minute to prepare highly active Zr-C composite nanocrystalline powder; Step 3. In an oxygen-free environment, put the Zr-C composite nanocrystalline powder and the Ce x (Pr,Nd,Dy) y Fe 100-x-y-z-u (Ga,Al,Cu,Co) z B u strong magnetic alloy powder into a vacuum tank, fill it with high-purity argon, and then carry out powder mixing on a ball mill for 4 hours to obtain a uniform mixture of alloy powder and Zr-C nanocrystalline powder; Step 4. Orient the prepared mixture in a magnetic field of 2.0 T and form it into a compact under a pressure of 150 MPa; After that, use a hydraulic press to perform isostatic pressing on the compact at 300 MPa to prepare a green compact with uniform stress distribution; Step 5. Put the prepared green compact into a vacuum sintering furnace with a vacuum degree of 10 -3 order of magnitude for sintering. The sintering temperature is 1035 °C and the sintering time is 3.5 hours. During this period, C in the incorporated Zr-C composite nanocrystalline powder reacts with Zr to form ZrC, and the surplus Zr forms acicular Zr-rich phases; After that, introduce argon for rapid cooling at a cooling rate of 6.5 °C / min and cool it to room temperature to obtain a highly dense sintered strong magnetic alloy; Step 6. Perform two-stage tempering heat treatment on the prepared sintered strong magnetic alloy; First, put the sintered strong magnetic alloy into a vacuum heat treatment furnace for primary tempering. The tempering temperature range is 925 °C and the tempering time is 3 hours. After the heating is completed, introduce argon into the furnace and cool the magnet to room temperature at a cooling rate of 5 °C / min; After that, perform secondary tempering. The tempering temperature range is 600 °C, and the tempering time and cooling are the same as those in the primary tempering to prepare a high-abundance rare earth strong magnetic alloy. Among them, the distribution patterns of Zr and in-situ ZrC in the magnet are shown in Figure 1 , the demagnetization curve of this strong magnetic alloy is shown in Figure 2 , and the polarization curve of the strong magnetic alloy in NaCl solution is shown in Figure 3 ; This high-abundance rare earth strong magnetic alloy has the characteristics of high coercivity and high corrosion resistance. The acicular Zr refines the grains, and the in-situ ZrC hinders the formation of corrosion reaction channels.

[0026] Comparative Example 1 The difference from Example 1 is that Step 2 is not used, and ZrC is added in Step 1; the demagnetization curve of the obtained high-strength magnetic alloy is shown in Figure 4 , and the polarization curve of the high-strength magnetic alloy is shown in Figure 5 ; it can be seen that Example 1 has higher coercivity and lower corrosion current density, confirming the synergistic effect of acicular Zr and in-situ ZrC.

[0027] Comparative Example 2 The difference from Example 1 is that Step 2 is not used, and Zr is added in Step 1; the demagnetization curve of the obtained high-strength magnetic alloy is shown in Figure 6 , and the polarization curve of the high-strength magnetic alloy is shown in Figure 7 . Example 1 has higher coercivity and lower corrosion current density, confirming the synergistic effect of acicular Zr and in-situ ZrC.

[0028] Example 2 A method for improving the coercivity and corrosion resistance of a high-abundance rare-earth high-strength magnetic alloy, the high-strength magnetic alloy being [Ce x (Pr,Nd,Dy) y Fe 100-x-y-z-u (Ga,Al,Cu,Co) z B u 100-v [Zr s (ZrC) 100-s v , where x, y, z, and u respectively represent the mass ratios of Ce, (Pr, Nd, Dy), (Ga, Al, Cu, Co), and B elements in Ce x (Pr,Nd,Dy) y Fe 100-x-y-z-u (Ga,Al,Cu,Co) z B u alloy powder; In the material composition system, x = 13.0 wt.%, y = 20.0 wt.%, z = 3.0 wt.%, u = 1.0 wt.%; s represents the mass ratio of Zr in Zr s (ZrC) 100-s composite modifier, s = 45.0 wt.%; The mass ratio of the composite modifier Zr s (ZrC) 100-s in the alloy powder is v, v = 0.75 wt.%; The preparation process is as follows: Step 1, prepare Ce 13 (Pr,Nd,Dy) 20 Fe 63 ​​(Ga, Al, Cu, Co)3B1 high magnetic alloy powder; First, melt metals Ce, Fe and Pr 25 Nd 75 , Dy 80 Fe 20 , B 19.5 Fe 80.5 alloy raw materials, and then prepare a high magnetic alloy rapid solidification ribbon through a rapid solidification and spinning process, and perform hydrogen explosion to obtain coarsely crushed powder, and then perform jet milling to prepare alloy powder with a particle size of 1.5 - 3.5 μm; Step two, the preparation method of the Zr - C composite nanocrystalline powder is as follows: S1, weigh zirconium (Zr) powder and carbon (C) powder with a purity of 99.9%, and the mass ratio of zirconium powder to carbon powder is 13.3:1; Prepare ethanol according to the ratio of the total amount of zirconium powder and carbon powder to ethanol by weight - volume (g / ml) of 100:1.5, prepare stearic acid according to the total amount of zirconium powder and carbon powder, and the mass ratio of stearic acid to the total amount of Zr powder and C powder is 0.5:100. Mix ethanol and stearic acid to obtain a ball - milling process control agent; Among them, the average particle size of Zr powder is 10 μm; the average particle size of C powder is 20 nm; S2, add WC cemented carbide balls, Zr powder, C powder and the ball - milling process control agent to a vacuum ball - milling tank. The mass ratio of WC cemented carbide balls to the total amount of zirconium powder and carbon powder is 5:1. Then seal the cover, evacuate, and fill with high - purity argon, and perform ball - milling. The ball - milling time is 80 hours and the ball - milling speed is 250 revolutions per minute to prepare a highly active Zr - C composite nanocrystalline powder; Step three, in an oxygen - free environment, put the Zr - C composite nanocrystalline powder together with the Ce prepared in step one x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u high magnetic alloy powder into a vacuum tank, and fill with high - purity argon, and then perform powder mixing on a ball - mill for 3 hours to obtain a uniformly mixed material of alloy powder and Zr - C nanocrystalline powder; Step four, orient the prepared mixed material in a 1.5T magnetic field and form it under a pressure of 100 MPa to obtain a compact; After that, perform isostatic pressing on the compact at 200 MPa using a hydraulic press to prepare a green compact with a uniform stress distribution; Step five, put the prepared green compact into a vacuum with a degree of -3Sintering is carried out in a vacuum sintering furnace of an order of magnitude. The sintering temperature is 1020 °C and the sintering time is 2.5 hours. During this period, C in the incorporated Zr-C composite nanocrystalline powder reacts with Zr to form ZrC, and the surplus Zr forms acicular Zr-rich phases; After that, argon is introduced for rapid cooling. The cooling rate is 6.5 °C / min, and it is cooled to room temperature to obtain a high-density sintered high-strength magnetic alloy; Step six, perform secondary tempering heat treatment on the prepared sintered high-strength magnetic alloy; First, load the sintered high-strength magnetic alloy into a vacuum heat treatment furnace for primary tempering. The tempering temperature range is 900 °C, and the tempering time is 2.5 hours. After the heating is completed, introduce argon into the furnace and cool the magnet to room temperature at a cooling rate of 5 °C / min; After that, perform secondary tempering. The tempering temperature range is 500 °C, and the tempering time and cooling are the same as those of the primary tempering to prepare a high-abundance rare earth high-strength magnetic alloy. This high-abundance rare earth high-strength magnetic alloy has the characteristics of high coercivity and high corrosion resistance.

[0029] Example 3 A method for improving the coercivity and corrosion resistance of a high-abundance rare earth high-strength magnetic alloy. This high-strength magnetic alloy is [Ce x (Pr,Nd,Dy) y Fe 100-x-y-z-u (Ga,Al,Cu,Co) z B u 100-v [Zr s (ZrC) 100-s v , where x, y, z, and u respectively represent the mass ratios of Ce, (Pr,Nd,Dy), (Ga,Al,Cu,Co), and B elements in the Ce x (Pr,Nd,Dy) y Fe 100-x-y-z-u (Ga,Al,Cu,Co) z B u alloy powder; In the material composition system, x = 13.5 wt.%, y = 20.0 wt.%, z = 4.5 wt.%, u = 0.95 wt.%; s represents the mass ratio of Zr in the Zr s (ZrC) 100-s composite modifier, s = 60.0 wt.%; The mass ratio of the composite modifier Zr s (ZrC) 100-s in the alloy powder is v, v = 1.0 wt.%; The preparation process is as follows: ​​Step 1: Prepare Ce 13.5 (Pr, Nd, Dy) 20 Fe 61.05 (Ga, Al, Cu, Co) 4.5 B 0.95 high-strength magnetic alloy powder; First, melt the metal Ce, Fe, Pr 25 Nd 75 , Dy 80 Fe 20 , B 19.5 Fe 80.5 alloy raw materials, and then prepare high-strength magnetic alloy rapid solidification ribbon through the rapid solidification and strip casting process, and perform hydrogen explosion to obtain coarsely crushed powder, and then prepare alloy powder with a particle size of 1.5 - 3.5 μm through air jet milling; Step 2: The preparation method of Zr - C composite nanocrystalline powder is as follows: S1: Weigh zircon (Zr) powder and carbon (C) powder with a purity of 99.9%, and the mass ratio of zircon powder to carbon powder is 19.0:1; Prepare ethanol according to the ratio of the total amount of zircon powder and carbon powder to ethanol by weight - volume (g / ml) of 100:4.5, and prepare stearic acid according to the total amount of zircon powder and carbon powder. The mass ratio of stearic acid to the total amount of Zr powder and C powder is 5.0:100. Mix ethanol and stearic acid to obtain the ball milling process control agent; Among them, the average particle size of Zr powder is 10 μm; the average particle size of C powder is 20 nm; S2: Add WC cemented carbide balls, Zr powder, C powder and the ball milling process control agent into a vacuum ball milling tank. The mass ratio of WC cemented carbide balls to the total amount of zircon powder and carbon powder is 15:1. Then seal the cover, evacuate, and fill with high - purity argon, and perform ball milling for 160 hours at a ball milling speed of 450 revolutions per minute to prepare highly active Zr - C composite nanocrystalline powder.

[0030] Step 3: In an oxygen - free environment, load the Zr - C composite nanocrystalline powder and the Ce x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u high - strength magnetic alloy powder together into a vacuum tank, and fill with high - purity argon, and then perform powder mixing on a ball mill for 5 hours to obtain a uniform mixture of alloy powder and Zr - C nanocrystalline powder; Step 4: Orient the prepared mixture in a 2.5T magnetic field and form it under a pressure of 200 MPa to obtain a compact; After that, use a hydraulic press to perform isostatic pressing on the compact at 400 MPa to prepare a green compact with uniform stress distribution. Step Five: Put the prepared green compact into a vacuum sintering furnace with a vacuum degree of 10 -3 orders of magnitude for sintering. The sintering temperature is 1050°C and the sintering time is 4.5 hours. During this process, C in the incorporated Zr-C composite nanocrystal powder reacts with Zr to form ZrC, and the surplus Zr forms acicular Zr-rich phases; After that, argon is introduced for rapid cooling at a cooling rate of 6.5°C / min until it is cooled to room temperature to obtain a high-density sintered hard magnetic alloy; Step Six: Perform a two-stage tempering heat treatment on the prepared sintered hard magnetic alloy; First, put the sintered hard magnetic alloy into a vacuum heat treatment furnace for primary tempering. The tempering temperature range is 950°C and the tempering time is 3.5 hours. After the heating is completed, introduce argon into the furnace and cool the magnet to room temperature at a cooling rate of 5°C / min; After that, perform secondary tempering. The tempering temperature range is 700°C, and the tempering time and cooling are the same as those in the primary tempering to prepare a high-abundance rare earth hard magnetic alloy, which has the characteristics of high coercivity and high corrosion resistance.

[0031] Although the present invention has been described in detail by referring to the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions should all be within the scope covered by the present invention. / Any person familiar with the technical field of the present invention can easily think of changes or substitutions within the technical scope disclosed by the present invention, and all of them should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for enhancing the coercivity and corrosion resistance of high-abundance rare earth strong magnetic alloys, characterized in that, Add Zr-C composite nanocrystalline powder to the melted alloy powder to in-situ generate a composite modifier Zr s (ZrC) 100-s , s represents the mass ratio of Zr in Zr s (ZrC) 100-s in the composite modifier, 40.0 wt.% ≤ s ≤ 60.0 wt.%; Compound modifier Zr s (ZrC) 100-s The mass ratio in the alloy powder is v, where 0.1 wt.% ≤ v ≤ 1.5 wt.%.

2. The method for improving the coercivity and corrosion resistance of a high-abundance rare earth strong magnetic alloy according to claim 1, characterized in that, The composition of the rare earth-abundant high-strength magnetic alloy is [Ce x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u 100-v [Zr s (ZrC) 100-s v ;​​ Among them, x, y, z, and u represent the mass ratios of Ce, (Pr, Nd, Dy), (Ga, Al, Cu, Co), and B elements in the Ce x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u alloy powder, respectively; The value ranges of x, y, z, and u in the material composition system are as follows: 11.5 wt.% ≤ x ≤ 13.5 wt.%, 17.0 wt.% ≤ y ≤ 20.0 wt.%, 1.5 wt.% ≤ z ≤ 4.5 wt.%, 0.9 wt.% ≤ u ≤ 1.0 wt.%.

3. The method for improving the coercivity and corrosion resistance of a high-abundance rare earth strong magnetic alloy according to claim 2, characterized in that, The preparation method of the Zr-C composite nanocrystalline powder is as follows: S1. Weigh zirconium powder and carbon powder with a purity of 99.9% according to the ratio. The mass ratio of zirconium powder to carbon powder is 13.3 - 19.0:1; Prepare ethanol and zirconium stearate according to the total amount of zirconium powder and carbon powder. The weight-to-volume ratio (g / ml) of the total amount of zirconium powder and carbon powder to ethanol is 100:1.5 - 4.5; the mass ratio of the total amount of zirconium powder and carbon powder to zirconium stearate is 100:0.5 - 5.0; Mix ethanol and zirconium stearate to obtain a ball milling process control agent; S2. Add WC cemented carbide balls, Zr powder, C powder, and the ball milling process control agent into a vacuum ball milling tank, then seal the cover, evacuate, and fill with high-purity argon, and carry out ball milling for 80 - 160 hours at a ball milling speed of 250 - 450 revolutions per minute to prepare a highly active Zr-C composite nanocrystalline powder.

4. The method for improving the coercivity and corrosion resistance of a high-abundance rare-earth strong magnetic alloy according to claim 3, characterized in that, In step S1, the average particle size of the zirconium powder is 10 μm; the average particle size of the carbon powder is 20 nm.

5. The method for improving the coercivity and corrosion resistance of a high-abundance rare earth strong magnetic alloy according to claim 3, characterized in that In step S2, the mass ratio of WC cemented carbide balls to the total amount of zirconium powder and carbon powder is 5 - 25:

1.

6. The method for improving the coercivity and corrosion resistance of a high-abundance rare earth strong magnetic alloy according to claim 3, characterized in that The method for improving the coercivity and corrosion resistance of the high-abundance rare earth permanent magnet alloy is as follows: Step 1: Prepare Ce x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u ferromagnetic alloy powder; First, melt the metal raw materials of Ce, Fe and Pr-Nd, Dy-Fe, B-Fe alloys, then prepare a rapidly solidified thin strip of a high magnetic alloy by the rapid solidification and strip casting process, and perform hydrogen explosion to obtain coarsely crushed powder, and then perform jet milling to prepare Ce x (Pr,Nd,Dy) y Fe 100-x-y-z-u (Ga,Al,Cu,Co) z B u alloy powder; Step 2: In an anaerobic environment, load the Zr-C composite nanocrystal powder and the Ce x (Pr, Nd, Dy) y Fe 100-x-y-z-u (Ga, Al, Cu, Co) z B u high-strength magnetic alloy powder into a vacuum tank, fill it with high-purity argon, and then perform powder mixing on a ball mill for 3 - 5 hours to obtain a uniform mixture of alloy powder and Zr-C nanocrystal powder; Step three. Orient the mixture prepared in step two in a magnetic field of 1.5 - 2.5 T, and form it under a pressure of 100 - 200 MPa to obtain a compact; After that, isostatically press the compact with a hydraulic press at 200 - 400 MPa to prepare a green compact with a uniform stress distribution; Step 4: Put the green compact prepared in Step 3 into a vacuum sintering furnace with a vacuum degree of 10 -3 in the order of magnitude for sintering. The sintering temperature is 1020 - 1050 °C, and the sintering time is 2.5 - 4.5 hours; Then, introduce argon for rapid cooling at a cooling rate of 6.5 °C / min until it reaches room temperature to obtain a high-density sintered permanent magnet alloy; Step five. Perform a two-stage tempering heat treatment on the prepared sintered permanent magnet alloy; First, load the sintered permanent magnet alloy into a vacuum heat treatment furnace for primary tempering. The tempering temperature range is 900 - 950 °C, and the tempering time is 2.5 - 3.5 hours. After heating, introduce argon into the furnace and cool the magnet to room temperature at a cooling rate of 5 °C / min; After that, perform secondary tempering. The tempering temperature range is 500 - 700 °C, and the tempering time and cooling are the same as those in the primary tempering to prepare a high-abundance rare earth permanent magnet alloy.

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