A permanent magnet alloy powder and a method of making the same, a permanent magnet made thereby and a method

Abstract

The application relates to the technical field of rare earth permanent magnet materials, in particular to a permanent magnet alloy powder and a preparation method thereof, a prepared permanent magnet and a method. a (La 1‑m Ce m ) b ‑Fe bal ‑M c ‑T n ‑B d , RE is at least one of Pr, Nd, Sm, Y, Gd, Tb, Dy, Ho and Yb; M is at least one of Zr, Nb, Mo, Hf, Mn, Ta and W; T is at least one of Cr, V, Si and Ti; wherein 0 The permanent magnet alloy powder prepared by replacing part of the noble rare earth elements with lanthanum and cerium can greatly reduce the cost, the oxidation resistance is improved by a small amount of refractory metal M and oxidation-resistant reinforcing metal T, the combustibility is reduced, and the problems of poor temperature resistance and oxidation resistance of pure praseodymium-neodymium-lanthanum-cerium / cerium-based iron-boron materials are avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rare earth permanent magnet materials, in particular to a kind of permanent magnet alloy powder and its preparation method, prepared permanent magnet and method.

[0002] In particular, a kind of high-abundance rare earth containing high proportion of quick-quenching rare earth permanent magnetic powder, and the magnet and related production technology prepared from the magnetic powder, suitable for information technology, automobile and other technical fields. BACKGROUND

[0003] Using high-abundance low-cost lanthanum cerium, cerium and other rare earth metals to replace a large amount of neodymium, praseodymium neodymium metal in the magnetic powder can reduce the cost of raw materials of the magnet, and can better meet the demand of the magnet market. At the same time, it can also promote the balanced utilization of rare earth resources and alleviate the overconsumption of praseodymium and neodymium rare earth resources.

[0004] However, using a large amount of lanthanum cerium or cerium and other high-abundance low-cost rare earth metals to replace in the quick-quenching magnetic powder has two main problems of poor oxidation resistance and poor temperature resistance, not only the performance of the rare earth magnet is reduced, but also the large-scale production and application of such rare earth magnet is affected.

[0005] Firstly, poor oxidation resistance. Lanthanum and cerium metals are very active and can be easily oxidized in air. The rapid oxidation of lanthanum cerium / cerium in praseodymium neodymium-lanthanum cerium / cerium-based permanent magnet material can greatly reduce the magnetic performance of the material. At the same time, in order to obtain higher coercivity to meet the use, the total rare earth content of praseodymium neodymium-lanthanum cerium / cerium-based permanent magnet material is often much higher than the normal part. The excess lanthanum cerium / cerium metal phase will be enriched in the grain boundary. Although it can improve the intrinsic coercivity, it is more likely to cause the material to be oxidized along the grain boundary, which deteriorates the material performance. At the same time, the exothermic oxidation of a large amount of rare earth elements promotes the rapid oxidation of the material, greatly increases the risk of material oxidation and combustion, and easily causes serious safety accidents.

[0006] Secondly, poor temperature resistance. In theory, pure Ce2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe 14 The Curie temperature of B phase is about 424 K, La2Fe

[0007] The prior art mainly adopts the following methods for studying the oxidation resistance of magnetic powder: antioxidant additive method, surface coating method, chemical conversion film method, etc. By coating a layer of antioxidant layer on the surface of the magnetic powder, the contact between the magnetic powder and the air is isolated, thereby improving the oxidation resistance of the magnetic powder. However, these antioxidant modification methods need to introduce a large amount of non-magnetic phase, which reduces the proportion of the magnetic phase, and in addition, the non-magnetic phase also interacts with the magnetic powder, causing the antioxidant film layer to fail and the performance of the magnetic powder to decrease, which cannot well solve the problems of poor oxidation resistance and poor temperature resistance when lanthanum and cerium are doped and replaced in rare earth magnetic powder. SUMMARY

[0008] The present application aims to overcome the problems of the prior art, such as the rising price of rare earth materials, the poor oxidation resistance and poor temperature resistance of lanthanum and cerium doped magnetic powder, and the poor magnetic performance and poor antioxidant effect of conventional antioxidant technology, and provides a permanent magnet alloy powder, a preparation method thereof, a prepared permanent magnet and a method.

[0009] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0010] The first aspect of the present application is to provide a permanent magnet alloy powder.

[0011] A permanent magnet alloy powder, the composition of the permanent magnet alloy is as follows:

[0012] RE a (La 1-m Ce m ) b -Fe bal -M c -T n -B d ,

[0013] RE is at least two of Pr, Nd, Sm, Y, Gd, Tb, Dy, Ho and Yb;

[0014] M is at least one of Zr, Nb, Mo, Hf, Mn, Ta and W;

[0015] T is at least one of Cr, V, Si and Ti;

[0016] wherein 0

[0017] wherein "bal" represents "balance of atoms", which is the abbreviation of Balance, indicating that the number of iron Fe atoms in the permanent magnet alloy molecule is calculated according to charge balance or chemical balance.

[0018] The present application is in accordance with RE2Fe14 B design permanent magnet alloy composition, permanent magnet alloy powder using lanthanum cerium instead of part of the rare earth elements, greatly reduce the cost of rare earth permanent magnet alloy powder, for pure praseodymium neodymium-lanthanum cerium / cerium base iron boron material temperature resistance and poor oxidation resistance problem, by a small amount of refractory metal M and anti-oxidation enhancement metal T (such as Cr, V, Ti, Si and other elements) as permanent magnet alloy powder with elements. In the alloying process, refractory metal M and anti-oxidation enhancement metal T, evenly distributed in the permanent magnet material. On the one hand, the doping metal elements play a role in refining the grain, optimizing the grain boundary structure, inhibiting the grain growth of rare earth permanent magnet alloy, high melting point non-magnetic phase will hinder the expansion of magnetic domain wall or magnetic domain turning, so it will also hinder the magnetic domain reversal caused by thermal disturbance at high temperature after magnetization, reduce the speed of magnetic performance loss. On the other hand, the doping metal enhances the magnetic domain pinning effect, and the high melting point non-magnetic phase also "pins" and hinders the growth of the grain, and the uniform and fine nanocrystalline grain is a prerequisite for obtaining high-performance magnetic properties. Therefore, the addition of high melting point elements further optimizes the magnetic properties of the material and improves the magnetic properties.

[0019] Then, when the surface of the permanent magnet alloy powder material encounters oxygen, these elements are preferentially oxidized, forming a dense and uniform oxide film on the surface of the material, which hinders the diffusion of oxygen molecules into the material, improving the oxidation resistance of the material, and greatly reducing the risk of performance failure during use. Through these modifications, lanthanum cerium / cerium iron boron permanent magnet material has commercial application prospect. At the same time, the doping elements will form high melting point non-magnetic phase at the grain boundary of the main phase.

[0020] Therefore, the rare earth permanent magnet alloy powder of the present application combines the grain boundary diffusion characteristics of the oxidation of the permanent magnet alloy powder, and the addition of refractory metal M and anti-oxidation enhancement metal T improves the oxidation resistance of the material, effectively controls the oxidation of the material at high temperature, makes the material have smaller magnetic performance loss at high temperature, ensures that the material can be used at high temperature, and meets the requirements of high temperature use environment.

[0021] In summary, the present application realizes the preparation of rare earth permanent magnet alloy with cheap rare earth elements, obtains high oxidation resistance, and at the same time has good magnetic performance. It can obtain a rare earth permanent magnet alloy product with good magnetic performance at a low cost, and the product can maintain the magnetic performance in a relatively harsh high temperature working condition, meeting the application requirements of information technology and other industrial fields.

[0022] Further, wherein, .

[0023] Further, 0.1≤a≤2.0, preferably 0.1≤a≤0.9, preferably 0.2≤a≤0.9.

[0024] Further, 11.6≤b≤13.1.

[0025] Further, 0.7≤c≤1.5, preferably, 1≤c≤1.5, preferably, 0.7≤c≤1.1.

[0026] Further, 6.5≤d≤8.1. Preferably, 6.5≤d≤7.

[0027] Further, 0.65≤m≤1.

[0028] Further, 0.25≤n≤3.0, preferably, 0.64≤n≤2.7.

[0029] Further, RE is a rare earth metal consisting of Pr and Nd.

[0030] Further, when T is Cr, 0.25≤n≤2.5.

[0031] Further, when T is Si, 0.60≤n≤2.7. Preferably, 0.9≤n≤3.0.

[0032] Further, when T is V or Ti, 0.60≤n≤1.3.

[0033] Further, T is at least one of Si and Ti. T can be a combination of one or more metals or / and non-metals.

[0034] Further, M is at least one of Zr and Nb. M can be a combination of one or more metals.

[0035] Further, the content of B is higher than RE2Fe 14 The required number of B atoms is 10-40%; wherein, 1-40% of B atoms in the wrapped RE2Fe 14 M is formed in the grain boundary of the B main phase y B and T z B non-magnetic phase.

[0036] In addition, the doping of refractory metal M and oxidation-resistant reinforcing metal T also generates borides with boron B. If a large amount of doping metal elements are added, a large amount of B atoms will be consumed, causing the content of RE2Fe 14 The content of the B main phase is greatly reduced, causing a substantial reduction in performance. Therefore, the rare earth permanent magnet alloy powder of the present application also optimizes the element ratio of the rare earth permanent magnet alloy powder, and designs a composition with more than the content of B, which ensures the improvement of oxidation resistance while ensuring the content of RE2Fe 14 The content of the B main phase is not greatly reduced, and the performance is not greatly weakened.

[0037] Further, the grain size of the permanent magnet alloy powder is not greater than 100 nm.

[0038] Further, the permanent magnetic alloy powder has a grain size of 10-100 nm.

[0039] Further, the permanent magnetic alloy powder has a grain size of 10-100 nm.

[0040] Further, the RE2Fe 14 The phase in the grain boundary of the B main phase includes a rare earth-rich phase, a B-rich phase, an M-B phase, and a T-B phase. The rare earth-rich phase refers to a phase in which the concentration of rare earth elements (such as Nd, Pr, La, Ce, etc.) in the material is significantly higher than that in other regions. The B-rich phase is a phase in which the content of boron (B) in the material is relatively high, and exists in the form of a boride. The M-B phase is a compound phase formed by a metal (M) and boron (B). The T-B phase is a compound phase formed by a metal (T) and boron (B).

[0041] Further, the surface element T and oxygen of the permanent magnetic alloy powder form an oxygen-resistant protective film. The oxide film makes the magnetic powder have high oxidation resistance, and the surface of the permanent magnetic alloy has a doping element T and oxygen to form an oxygen-resistant protective film, so that the oxygen in the air is difficult to contact the internal permanent magnetic alloy, thereby improving the oxidation resistance of the material.

[0042] Further, the permanent magnetic alloy powder has a grain size of 10-100 nm.

[0043] Further, the permanent magnetic alloy powder has a grain size of 10-100 nm. 2

[0044] Further, the permanent magnetic alloy powder has a grain size of 10-100 nm. 2

[0045] Further, the permanent magnetic alloy powder has a grain size of 10-100 nm.

[0046] ​​Further, the primary cooling surface has airbag-shaped holes arranged in the same direction. The airbag-shaped holes form a primary cooling surface for rapid cooling of the alloy liquid, and enhance the magnetization performance of the prepared permanent magnet alloy powder, because the holes increase the primary cooling area of the alloy strip, increase its cooling rate, and the corresponding magnetic powder performance is more excellent.

[0047] The second aspect of the present application is to provide a preparation method of the above-mentioned permanent magnet alloy powder.

[0048] A preparation method of a permanent magnet alloy powder, comprising the following steps:

[0049] Step 1, according to the element ratio in the permanent magnet alloy powder, prepare the raw materials required for alloying compounds, and smelt into a permanent magnet alloy;

[0050] Step 2, quenching the permanent magnet alloy at a temperature above its melting point into an alloy strip with partial microcrystalline size or amorphous;

[0051] Step 3, performing crystal structure regulation treatment on the alloy strip or not;

[0052] Step 4, crushing the alloy strip that has been treated or not to the required size to obtain a permanent magnet alloy powder.

[0053] Further, in step 1, the permanent magnet alloy smelted has a morphology of flake, plate or column with a minimum direction size greater than 0.2mm. The smelted permanent magnet alloy can also be other shapes and structures, as long as the same intermediate alloy can be achieved as the raw material for subsequent rapid quenching preparation of alloy powder.

[0054] By smelting, the material is alloyed to obtain a permanent magnet alloy, which is an intermediate material for rapid quenching preparation of alloy strips, and its morphology can be various, which is convenient for subsequent rapid quenching into alloy thin strips.

[0055] Preferably, the quenching method of the compound at a temperature above its melting point after alloying includes water cooling, air cooling, etc.

[0056] Further, in step 2, the thickness direction size of the alloy strip is 30-60 microns, and the width direction size is 2-5mm.

[0057] Further, in step 2, the grain size in the alloy strip is 0-100nm.

[0058] Further, when quenching, the cooling mass flow rate is 60-120kg / h.

[0059] Further, when quenching, the primary cooling heat conduction medium used is a ring structure made of metal molybdenum, titanium-zirconium-molybdenum alloy or molybdenum-lanthanum alloy.

[0060] Further, when the quenching treatment is performed, the linear speed of the rotating heat conducting medium used for initial cooling is 10-35 m / s.

[0061] Further, when the quenching treatment is performed, the thickness of the main phase RE2Fe 14 The B grain size of the microcrystalline region or amorphous region is less than 20 nm.

[0062] The quenching treatment is performed by rapidly rotating the annular heat conducting medium to spin out the alloy liquid to form an alloy strip, and rapidly complete the cooling. During the cooling process, the strip structure is expected to be a uniform microcrystalline structure to achieve optimal performance. The process parameters of the quenching treatment are controlled to improve the consistency, reduce the grain difference between the initial cooling surface and the free surface, reduce the grain difference between the left and right end surfaces and the center of the strip, and obtain a more ideal uniform microstructure. Appropriate linear speed is adopted for cooling, and the thickness of the thin strip is controlled to make the cooling rate of each part of the strip as uniform as possible, so that the grain size is uniform.

[0063] Since the alloying raw material contains a large number of high-melting-point elements, the alloy liquid is prone to undercooling into an amorphous structure during cooling. The magnetic performance of the amorphous structure strip is low, and even after the later structure adjustment, it is difficult to obtain a uniform crystal structure, and often accompanied by partial abnormal growth of coarse crystals, so that it is difficult for the magnetic powder to achieve optimal performance. Therefore, the linear speed and cooling mass flow rate are adopted to obtain a suitable crystal structure on the initial cooling surface and the free surface of the rapidly quenched strip, and optimal performance is achieved. On the contrary, according to the traditional understanding of accelerating the quenching treatment and accelerating the linear speed of the rotating heat conducting medium, the performance of the permanent magnet alloy cannot be optimized.

[0064] Further, in step 4, the alloy strip subjected to the regulation treatment or not is crushed to a required size, and any one or a combination of a plurality of methods such as rolling and cutting is adopted.

[0065] Further, the alloy strip is subjected to a crystal structure regulation treatment, and high-temperature treatment is adopted, and the treatment temperature is 300-800℃. Preferably, the treatment temperature is 400-800℃.

[0066] Through the high-temperature treatment in the above temperature range, the microcrystals on the initial cooling surface are appropriately grown, or the amorphous structure is converted into a crystal structure; at the same time, the grain size of the free surface is not abnormally grown, the grain size is controlled within a certain range, the grain size difference between the initial cooling surface and the free surface is small, and a uniform structure is obtained, so that higher magnetic performance can be obtained.

[0067] Further, the above preparation method obtains a permanent magnet alloy powder with a grain size of 10-100 nm.

[0068] The third aspect of the present application is to provide a permanent magnet prepared by using the above permanent magnet alloy powder.

[0069] A permanent magnet containing the above-mentioned permanent magnet alloy powder as a raw material.

[0070] A fourth aspect of the present application is to provide a method for producing the above-mentioned permanent magnet.

[0071] A method for producing a permanent magnet, comprising the following steps: using the above-mentioned permanent magnet alloy powder and a polymer binder, and preparing a permanent magnet by compression molding or injection molding or calendering.

[0072] Compared with the prior art, the present application has the following beneficial effects:

[0073] 1. The permanent magnet alloy powder prepared by replacing part of the rare earth elements with lanthanum and cerium can greatly reduce the cost. At the same time, a small amount of refractory metal M and oxidation-resistant reinforcing metal T (such as Cr, V, Ti, Si, etc.) are used as the matching elements of the permanent magnet alloy powder to improve the oxidation resistance of the magnetic powder, reduce the flammability of the magnetic powder, and avoid the problems of poor temperature resistance and oxidation resistance of pure praseodymium-neodymium-lanthanum-cerium / cerium-based iron-boron materials. The problem of easy ignition and rapid spread of the traditional lanthanum-cerium iron boride alloy magnetic powder during production process is solved.

[0074] 2. The refractory metal M and the oxidation-resistant reinforcing metal T in the permanent magnet alloy material are uniformly distributed in the permanent magnet material. On the one hand, the doping of metal elements refines the grain size, optimizes the grain boundary structure, and inhibits the grain growth of the rare earth permanent magnet alloy. The non-magnetic phase with high melting point will hinder the expansion of the magnetic domain wall or the turning of the magnetic domain, and will also hinder the magnetic domain reversal caused by thermal disturbance at high temperature after magnetization, thereby reducing the speed of magnetic performance loss. On the other hand, the doping of metal enhances the magnetic domain pinning effect, and the non-magnetic phase with high melting point also "pins" and hinders the growth of the grain, thereby refining the grain size of the main phase in the material. Uniform and small nanocrystalline grains are a prerequisite for obtaining high-performance magnetic properties. Therefore, the addition of high-melting-point elements further optimizes the magnetic properties of the material and improves the magnetic properties.

[0075] 3. The element ratio of the rare earth permanent magnet alloy powder in the permanent magnet alloy material is optimized, and the composition with more than normal B content is designed. While ensuring the improvement of oxidation resistance, the performance of RE2Fe 14 B main phase is not greatly reduced, and the performance is not greatly weakened. The magnet made of the permanent magnet alloy material has low magnetic performance loss during long-term use, and meets the performance requirements. BRIEF DESCRIPTION OF DRAWINGS

[0076] Figure 1 It is a micrograph of the magnetic powder in Example 1 of the present application. DETAILED DESCRIPTION

[0077] The "rapid cooling" of the present invention refers to the rapid solidification of the molten metal at a cooling rate of 10 3 ~10 6 K / s, such as a cooling rate of 10 5 -10 6 K / s. For example, the molten alloy liquid is spun into 20-50 μm alloy thin strips using a high-speed rotating molybdenum roller (linear speed of 20-50 m / s) to achieve the rapid quenching process, and the cooling rate is 10 5 ~10 6 K / s. The molybdenum roller is internally passed with a cooling medium (such as water) to reduce the temperature of the molybdenum roller and improve the cooling efficiency to achieve a higher cooling rate.

[0078] Preferably, in step 2 of the preparation method of the permanent magnet alloy powder, the alloying material is rapidly cooled above its melting point to form alloy strips with partial microcrystalline size or amorphous. The linear speed of the rotating roller is controlled in the range of 10-35 m / s. If the linear speed of the roller is too high, a large amount of amorphous will be formed, and after heat treatment, the performance of the rare earth permanent magnet alloy will not be good, and the maximum performance loss can reach 50%.

[0079] The present invention is a RE a (La 1-m Ce m ) b -Fe bal -M c -T n -B d rare earth alloy magnet, RE is PrNd; wherein Nd is metallic neodymium; Pr is metallic praseodymium, and the ratio of Nd and Pr is not limited. For example, in some embodiments of the present invention, the ratio of Pr and Nd is 75:25. La is metallic lanthanum; Ce is metallic cerium, and a portion of neodymium or praseodymium neodymium is replaced by LaCe. In this way, a lanthanum cerium replaced portion of praseodymium neodymium is formed in the neodymium iron boron magnet, which is lower in cost than the praseodymium neodymium rare earth magnet.

[0080] A preparation method of a permanent magnet alloy, comprising the following steps:

[0081] Step 1, preparing raw materials according to the formula of the permanent magnet alloy, and melting the raw materials into alloy ingots;

[0082] Step 2, melting the alloy ingots into alloy thin strips;

[0083] Step 3, heat treating the alloy strips;

[0084] A certain amount of doping elements (such as Cr / Si / V / Ti, etc.) is added during smelting to form an alloy ingot, and then the alloy ingot is rapidly quenched into alloy magnetic powder. When the modified magnetic powder is oxidized, a dense and continuous oxide passivation film can be formed on the surface, which hinders the continuous diffusion of oxygen to the alloy matrix, so that the magnetic powder is not easy to burn, and exhibits excellent flame-retardant and oxidation-resistant functional properties.

[0085] The application will be further described in conjunction with specific examples. However, it should not be understood that the above-mentioned subject matter of the application is limited to the following examples, and any technology realized based on the content of the application falls within the scope of the application.

[0086] Example 1

[0087] A preparation method of a permanent magnet alloy, comprising the following steps:

[0088] 1. Material configuration

[0089] The material is configured according to the following permanent magnet alloy element composition ratio.

[0090] (Pr 0.75 Nd 0.25 ) 0.2 (La 0.2 Ce 0.8 ) 12.5 Zr 1.06 Si 1.7 B 6.5 Fe bal

[0091] 2. Material alloying

[0092] The prepared permanent magnet alloy raw materials are subjected to high-temperature alloying, and after alloying, the molten liquid is rapidly cooled to form a permanent magnet alloy ingot with a minimum direction size of greater than 0.2 mm in sheet, plate, column or other shape structure. Rapid cooling methods include water cooling, air cooling, etc. In this embodiment, the water cooling method is used to rapidly cool the ingot.

[0093] 3. Alloy strip

[0094] The permanent magnet alloy ingot is remelted to form an alloy strip by rapid cooling, and the thickness direction size is 30-60 microns, and the width size is 2-5 mm. In this embodiment, the target alloy strip thickness is controlled to be 50 microns (actual error within ±10%), and the width is 4 mm (actual error within ±10%). The mass flow rate of the rapid cooling process is 70-120 kg / h, and the target mass flow rate of the rapid cooling process in this embodiment is controlled to be 100 kg / h. In the rapid cooling process, the first cooling heat transfer medium used is a ring-shaped metal material made of metal molybdenum, titanium-zirconium-molybdenum alloy or molybdenum-lanthanum alloy, and the second heat transfer medium is a flowing liquid, which is subjected to secondary heat transfer with the aforementioned ring-shaped metal material.

[0095] The first heat transfer medium used in the rapid cooling of the molten alloy has a linear velocity of 20-40 m / s; the primary phase RE2Fe 14 B crystal grains have a size of less than 20 nm.

[0096] The molten permanent magnet alloy is sprayed onto the surface of the high-speed rotating molybdenum roller, which has a linear velocity of 15 m / s, and the cooled alloy strip has a thickness of 40-50 microns and a width of 3-4 mm.

[0097] In the rapid cooling, the strip structure is expected to be a uniform microcrystalline structure to achieve optimal performance. In order to obtain the ideal uniform microstructure, especially to reduce the grain difference between the primary cooling surface and the free surface, and the grain difference between the left and right end surfaces and the center of the strip, a higher linear velocity is usually used for cooling to thin the thickness of the strip and make the cooling rate of each part of the strip as uniform as possible to ensure uniform grain size.

[0098] 4. Strip breaking

[0099] The above strip is broken, and the breaking methods include rolling and cutting. In this embodiment, the cutting method is used to break the strip.

[0100] 5. Strip structure regulation

[0101] The above broken magnetic powder needs to be treated for structure regulation at a temperature of 400-800°C. In this embodiment, the heat treatment is performed at 550°C for 30 minutes to complete the structure regulation of the permanent magnet alloy powder. Since the linear velocity of the alloy strip formed by the above rapid cooling is selected to match, the magnetic performance of the permanent magnet alloy powder after heat treatment is optimal. Compared with other alloy strips obtained by faster rapid cooling, the magnetic performance of the permanent magnet alloy powder obtained by breaking the alloy strip obtained by rapid cooling at a linear velocity of 10-35 m / s is optimal after treatment.

[0102] The primary cooling surface microcrystalline is appropriately grown, or the amorphous structure is converted into a crystalline structure; at the same time, the heating and cooling rates are controlled to prevent the grain size of the free surface from abnormally growing, and the grain size of the free surface is controlled within a certain range, so that the grain size difference between the primary cooling surface and the free surface is small, and the structure is close to uniform, which can obtain higher magnetic performance.

[0103] 6. Magnetic powder characteristics

[0104] The permanent magnet alloy powder material prepared by the above method, when the surface of the powder contacts oxygen, the doped Cr, V, Ti, Si and the like are preferentially oxidized, a dense and uniform oxide film can be formed on the surface of the material, hindering the diffusion of oxygen molecules to the inside of the material, improving the oxidation resistance of the material, and greatly reducing the risk of performance failure of the material during use.

[0105] At the same time, by adding a large amount of B, the consumption of B due to the large addition of Cr, V, Ti, Si and the like is compensated, and the RE2Fe 14 The proportion of B main phase is not greatly reduced, and the magnetic performance is not greatly weakened. At the same time, 1-40% of B atoms are wrapped in RE2Fe 14 M y B and T z B non-magnetic phase, hindering the reversal of magnetic domains, and improving the coercivity of the material.

[0106] 7. Magnet preparation

[0107] The rare earth permanent magnet alloy powder material prepared by the above method is combined with a high molecular binder, and is prepared by compression molding or injection molding or calendering. The present embodiment is prepared by compression molding process.

[0108] Test the flame retardant performance of the permanent magnet alloy powder (test according to the standard method of GB / T 21618-2008 "Dangerous Goods Combustion Rate Test Method of Flammable Solids"):

[0109] First, screen the permanent magnet alloy powder prepared with different atomic proportions, take the powder sample under the 100 mesh standard screen and on the 280 mesh standard screen, and make a standard bulk sample. The standard bulk sample is a triangle with a length of 250 mm, a cross section of 10 mm in height and 20 mm in width. Place it in air and observe the oxidation and combustion of the standard bulk sample, and test the oxidation and combustion speed.

[0110] The results show that the permanent magnet alloy powder prepared in this embodiment has good flame retardant performance, and the combustion speed is 10.8 mm / min.

[0111] Test the magnetic properties of the permanent magnet alloy powder:

[0112] Test according to GB / T 3217-2013 "Permanent Magnet (Hard Magnet) Material Magnetic Test Method" and GB / T 24270-2009 "Permanent Magnet Material Magnetic Property Temperature Coefficient Measurement Method", make φ10*10 standard sample of permanent magnet powder at room temperature 25℃, high temperature 125℃, and test the remanence B r and coercivity H cJTest and compare the magnetic flux loss of the standard sample after 2h and 100h storage in a high temperature environment of 120°C. The magnetic properties of the permanent magnet alloy powder are tested: permanent magnet alloy powder α(B r ) (-125°C) = -0.25% / °C, β(H cJ ) (-125°C) = -0.28% / °C. Among them, "α(B r ) (-125°C)" is the temperature coefficient of the residual magnetism of the sample (i.e. the percentage change of the residual magnetism of the sample per 1°C rise) during the process of the sample rising from 25°C to 125°C; "β(H cJ ) (-125°C)" is the temperature coefficient of the coercive force of the sample (i.e. the percentage change of the coercive force of the sample per 1°C rise) during the process of the sample rising from 25°C to 125°C.

[0113] The permanent magnet alloy powder is stored in a high temperature environment of 120°C for 2h and 100h for high temperature aging treatment. Then, the room temperature (25°C) magnetic properties of the permanent magnet alloy powder are tested according to GB / T 3217-2013 "Permanent Magnet (Hard Magnet) Material - Magnetic Property Test Method", and the performance loss of the permanent magnet alloy powder due to high temperature is compared. The magnetic property loss of the permanent magnet alloy powder after aging is measured to be 1.55% and 3.41%, respectively.

[0114] Example 2

[0115] The same method as in Example 1 is used to produce and process the permanent magnet alloy powder, and permanent magnet alloy powders with different atomic proportions are obtained. The flame retardant properties of the different permanent magnet alloy powders are tested and compared. Specifically, permanent magnet alloy powders with different element ratios are prepared, and their flame retardant properties are tested. The test method refers to the flame retardant property test method in Example 1.

[0116] By adding doping elements, the alloy magnetic powder exhibits excellent oxidation resistance and flame retardancy, and the problem of flammability of lanthanum-cerium or cerium rapid-quenching magnetic powder is improved. At the same time, due to the excellent oxidation resistance of the magnetic powder, the bonded magnets manufactured exhibit better oxidation resistance, the magnetic loss of the magnets due to oxidation is less, and the stability is better.

[0117] The specific permanent magnet alloy element ratio and the combustion test results are shown in the following table.

[0118] 1. Flame retardant data

[0119] Table 1: Effect of different Cr contents on PrNdCe-based

[0120]

[0121] Table 2: Effect of different Cr contents on PrNdLaCe-based

[0122]

[0123] Table 3: Effect of different Si contents on PrNdLaCe-based

[0124]

[0125] Table 4: Effect of different V contents on PrNdLaCe-based

[0126]

[0127] Table 5: Effect of different Si contents on PrNdLaCe-based

[0128]

[0129] Table 6: Effect of different Cr contents on PrNdLaCe-based

[0130]

[0131] Table 7: Effect of different LaCe ratios on PrNdLaCe-based

[0132]

[0133] Table 8: Effect of different B contents on PrNdLaCe-based

[0134]

[0135] Table 9: Effect of different element contents on PrNdLaCe-based

[0136]

[0137] From the experimental results recorded in the above tables, it can be seen that by doping Cr, Si, V, Zr, etc. into lanthanum cerium praseodymium neodymium rare earth permanent magnet alloy, better flame retardant performance can be obtained. When the doping ratio of Cr, Si, V, Zr reaches a certain amount, the rare earth permanent magnet alloy powder can achieve the characteristics of not spreading or not burning, realizing good flame retardant performance, meeting the production safety requirements of permanent magnet alloy powder, and the performance of the magnetic powder is not easily damaged by air oxidation.

[0138] Example 3

[0139] Permanent magnet alloy powders were prepared by the method of Reference Example 1, and the compositions of the alloy powders are shown in the following table. Based on the raw material ratio of the permanent magnet alloy powder prepared in the foregoing examples, the raw material ratio of the permanent magnet alloy was adjusted to prepare permanent magnet alloys with multiple ratios, and the room temperature and high temperature magnetic performance data of the permanent magnet alloy powders were tested.

[0140] Permanent magnetic powder was made into φ10*10 standard sample as in Example 1, and then tested by GB / T 3217-2013 "Permanent magnet (hard magnetic) material - Magnetic test method", and the permanent magnetic alloy powder was stored at room temperature 25℃ and high temperature 125℃ to test the remanence B r and coercive force H cJ . The magnetic property loss of the permanent magnetic alloy powder after being stored at high temperature 120℃ for 2h was compared. In the table, "α(B r )(-125℃)" is the remanence temperature coefficient of the sample during the process of increasing the temperature of the sample from 25℃ to 125℃ (i.e. the change percentage of the remanence of the sample per 1℃ increase); "β(H cJ )(-125℃)" is the coercive force temperature coefficient of the sample during the process of increasing the temperature of the sample from 25℃ to 125℃ (i.e. the change percentage of the coercive force of the sample per 1℃ increase).

[0141] The test results were compared with the results at room temperature 25℃, and the high temperature magnetic loss and the remanence and coercive force temperature coefficient data proved that the improved magnetic powder of the application, due to its excellent oxidation resistance, effectively controlled the oxidation of the magnetic powder at high temperature, so that the magnetic powder had smaller magnetic property loss at high temperature, and ensured that the magnetic powder could be used at high temperature, and the high temperature use stability was improved.

[0142] Table 10: Influence of magnetic property loss of permanent magnetic alloy powder of different elements

[0143]

[0144] Table 11: Influence of magnetic property loss of permanent magnetic alloy powder of different elements

[0145]

[0146] Table 12: Influence of magnetic property loss of permanent magnetic alloy powder of different B contents

[0147]

[0148] Table 13: Influence of magnetic property loss of permanent magnetic alloy powder of different LaCe ratios

[0149]

[0150] On the basis of Example 2, the element ratio of the permanent magnetic alloy powder of Example 3 was further designed, and the performance of the permanent magnetic alloy powder prepared by the element ratio of each example and the comparative example showed that when the elements in the ratio of the application were added, the ratio of each element was controlled to meet the design requirements, and better anti-magnetic property loss effect could be obtained.

[0151] The permanent magnet alloy powder prepared in the foregoing examples is subjected to grain size testing, and the test results show that with the addition of a large amount of high-melting-point elements, the growth of the main phase grains is inhibited, and 20-50 nm sized, uniform nanocrystalline magnetic powder is obtained. The ultra-fine nanocrystalline structure also ensures that the magnetic powder has relatively high performance.

[0152] Example 4

[0153] The permanent magnet alloy powder is subjected to oxidation weight gain testing, and the oxidation weight gain data prove that the improved magnetic powder of the application has a lower weight gain ratio after oxidation, indicating that the magnetic powder has strong oxidation resistance.

[0154] Specifically, the permanent magnet alloy powder prepared according to the method of Reference Example 3 is further tested for the baking oxidation weight gain of each alloy powder under specific conditions. In particular, the oxidation weight gain data of the alloy composition ratio with the two extreme contents in Table 10 and Table 11 in Example 3 are verified as the basis for further optimization of the content.

[0155] Table 14: Effect of different elements

[0156]

[0157] Table 15: Effect of different elements

[0158]

[0159] Table 16: Effect of different B contents

[0160]

[0161] Table 17: Effect of different LaCe ratios

[0162]

[0163] Comparative Example 1

[0164] The permanent magnet alloy powder is prepared according to the preparation process and raw material ratio of Reference Example 1, and the only difference is that the different roller speeds are adjusted so that the linear speed during rapid cooling of the molten alloy liquid is 8 m / s, 10 m / s, 20 m / s, 30 m / s, 35 m / s, and 40 m / s. The alloy liquid is rapidly cooled to obtain a thin strip, which is then crushed to obtain an alloy powder, and the magnetic performance of the alloy powder after heat treatment is analyzed and tested.

[0165] Table 18: Effect of different linear speeds on the performance of the permanent magnet alloy powder

[0166]

[0167] *Heat treatment: The prepared alloy is heat treated at 550°C for 30 minutes.

[0168] But the alloy of the present application has more high melting point elements, and when the alloy is cooled, it is very easy to undercool into an amorphous structure, and the magnetic performance of the amorphous structure strip is low. Even after the later structure adjustment, it is also difficult to obtain a crystal structure with uniform size, and often accompanied by partial abnormal growth of coarse grains, so it is difficult for the magnetic powder to achieve optimal performance. Therefore, for the alloy of the present application, it is not suitable to use high rotational linear speed for cooling. If a lower linear speed is used, the strip thickness will be thicker, causing a large difference in grain size between the initial cooling surface and the free surface of the strip thickness direction, which will also reduce the magnetic performance. Therefore, it is necessary to reasonably control the quenching cooling speed to obtain suitable crystal structure on the initial cooling surface and the free surface of the rapidly quenched strip, so as to correct the crystal structure of the strip through later heat treatment, so as to achieve optimal performance.

[0169] Through many experiments of the inventors, it is found that when the linear speed of the rotating roller is controlled in the range of 10-35 m / s, the magnetic performance of the permanent magnet alloy is maximized.

[0170] Comparative Example 2

[0171] The influence of different element ratio schemes of permanent magnet alloy on the performance of permanent magnet alloy powder is compared. The permanent magnet alloy powder is prepared by the method of Reference Example 1, and the preparation process parameters remain unchanged, only the ingredient ratio of the permanent magnet alloy smelting is changed, so that the element ratio in the smelted permanent magnet alloy changes, and the specific control target permanent magnet alloy element ratio is as follows.

[0172] RE a (La 1-m Ce m ) b -Fe bal -M c -T n -B d ,

[0173] The raw material ratio is adjusted so that the subscript of each element in the target permanent magnet alloy is as follows:

[0174] Table 19: Element ratio of multiple permanent magnet alloys prepared in Comparative Example 2

[0175]

[0176] The left two columns of the table are condition explanations, the first column is the element or element combination corresponding to the subscript, and the second column or the corresponding subscript corresponds to the element subscript value in the target permanent magnet alloy corresponding to each value in the table. The last row is the value obtained based on the subscript value calculation corresponding formula.

[0177] Table 20: Performance test results of permanent magnet alloys with different element ratios

[0178]

[0179] From the experimental research results of the above-mentioned Comparative Example 2, it can be seen that when different element ratios are selected, the performance of the permanent magnet alloy is quite different. According to the foregoing single-factor analysis experiment, it can be seen that the addition of M elements or T elements can improve the flame retardant performance of the permanent magnet alloy, so that it is not easy to burn. Then, combined with the empirical formula:

[0180]

[0181] Adjust and optimize the element ratio of the permanent magnet alloy, take the rare earth element RE as the reference point and the boron B of the neodymium-iron-boron permanent magnet, adjust the proportion of the T element, so that the product of the above-mentioned empirical formula is between 0-67.5, ensure that the added application of the doping element maximizes the role of oxidation resistance and flame retardance, while maintaining the best magnetic performance of the rare earth permanent magnet alloy powder.

[0182] In summary, the present application solves the problems of poor temperature resistance and oxidation resistance of pure lanthanum cerium / cerium-based iron-boron materials. By adding a small amount of Cr, V, Ti, Si and other elements during alloying, they are uniformly distributed in the permanent magnet material. When the material surface encounters oxygen, these elements will oxidize preferentially, forming a dense and uniform oxide film on the material surface, which hinders the diffusion of oxygen molecules into the material, improving the oxidation resistance of the material and significantly reducing the risk of performance failure during material use. Through these modifications, the lanthanum cerium / cerium iron-boron permanent magnet material has commercial application prospects.

[0183] By adding a small amount of Cr, V, Ti, Si and other elements, the oxidation resistance of the material is improved, the oxidation of the material at high temperature is effectively controlled, the material has a small loss of magnetic performance at high temperature, and the material can be used at high temperature, and the high temperature use stability is improved. Under the condition of a small increase in cost, the temperature resistance of the pure lanthanum cerium / cerium iron-boron permanent magnet material is significantly improved, the high temperature magnetic performance loss is greatly reduced, which can meet the requirements of higher temperature use environment, and solves the problems of poor high temperature performance of pure lanthanum cerium / cerium iron-boron permanent magnet material and cannot be used at high temperature.

[0184] At the same time, through the addition of a small amount of Cr, V, Ti, Si and other high melting point elements, high melting point non-magnetic phases will be formed at the grain boundary of the main phase of the material. These high melting point non-magnetic phases have two advantages. First, these high melting point non-magnetic phases will hinder the expansion of the magnetic domain wall or the turning of the magnetic domain, so as to hinder the magnetic domain reversal caused by thermal disturbance at high temperature after the material is magnetized, and reduce the speed of magnetic performance loss. Secondly, these high melting point non-magnetic phases also "pin" hinder the growth of the grains, and refine the grain size of the main phase in the material. Uniform and small nanocrystalline grains are a prerequisite for obtaining high-performance magnetic properties. Therefore, the addition of high melting point elements further optimizes the magnetic properties of the material.

[0185] However, a large amount of Cr, V, Ti, Si and other elements will form borides with B, consume a large amount of B atoms, cause RE2Fe 14 The proportion of B main phase is greatly reduced, causing a large reduction in performance. In order to improve the performance, we designed a composition exceeding the normal B content, which ensures the improvement of oxidation resistance and the RE2Fe 14 The proportion of B main phase is not greatly reduced, and the performance is not greatly weakened.

[0186] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A permanent magnet alloy powder, characterized by, The permanent magnetic alloy powder has the following composition: RE a (La 1-m Ce m ) b -Fe bal -M c -T n -B d , RE is at least one of Pr, Nd, Sm, Y, Gd, Tb, Dy, Ho and Yb; M is at least one of Zr, Nb, Mo, Hf, Mn, Ta and W; T is at least one of Cr, V, Si and Ti; wherein 0 bal is the atomic number of Fe calculated according to chemical equilibrium.

2. The permanent magnet alloy powder according to claim 1, characterized by 0.1≤a≤0.9, 11.6≤b≤13.1, 0.7≤c≤1.1, 6.5≤d≤8.1, 0.65≤m≤1, 0.64≤n≤2.

7.

3. The permanent magnet alloy powder according to claim 1, characterized in that RE is a rare earth metal consisting of Pr and / or Nd.

4. The permanent magnet alloy powder according to claim 1, characterized by When T is Cr, 0.25≤n≤2.

5.

5. The permanent magnet alloy powder according to claim 1, characterized by When T is Si, 0.60≤n≤2.

7.

6. The permanent magnet alloy powder according to claim 1, characterized by When T is V or Ti, 0.60≤n≤1.

3.

7. The permanent magnet alloy powder according to claim 1, characterized by T is at least one of Si and Ti.

8. The permanent magnet alloy powder according to claim 1, characterized by M is at least one of Zr and Nb.

9. The permanent magnet alloy powder according to claim 1, characterized by B content is higher than RE2Fe 14 B positive fraction of the required number of atoms 10-40%; wherein 1-40% of the B atoms are in the form of RE2FB4 14 MyB and TzB non-magnetic phases are formed in the grain boundaries of the B main phase.

10. The permanent magnet alloy powder according to claim 1, characterized by The permanent magnetic alloy powder has a grain size of no more than 100 nm.

11. The permanent magnet alloy powder according to claim 10, characterized by The permanent magnetic alloy powder has a grain size of 10-100 nm.

12. The permanent magnet alloy powder according to claim 1, characterized by In the permanent magnetic alloy powder, the main phase grains with a size of 20-50 nm account for more than 80%.

13. The permanent magnet alloy powder according to claim 1, characterized by The package RE2Fe 14 The phases in the grain boundaries of the B main phase include rare earth rich phases, B rich phases, M-B phases and T-B phases.

14. The permanent magnet alloy powder according to claim 1, characterized by The permanent magnetic alloy powder has a standard accumulation sample with a length of 250 mm, a cross section of a triangle with an inner height of 10 mm and a width of 20 mm, and a standard combustion rate of less than 22 mm / min or no complete combustion or no combustion.

15. The permanent magnet alloy powder according to claim 1, characterized by The permanent magnetic alloy powder has an oxidation weight gain of less than 313 mg / (m 2 / g) per unit specific surface area after being baked in an atmospheric environment at 175°C for 24 hours.

16. The permanent magnet alloy powder according to claim 1, characterized by The permanent magnetic alloy powder has an oxidation weight gain of less than 332 mg / (m 2 / g) per unit specific surface area after being baked in an atmospheric environment at 175°C for 48 hours.

17. The permanent magnet alloy powder according to claim 1, characterized by The permanent magnetic alloy powder is prepared by a rapid quenching method, and in the preparation process, the grain size in the microcrystalline zone or amorphous zone of the primary cooling surface along the thickness direction of the alloy strip is less than 20 nm.

18. The permanent magnet alloy powder according to claim 1, characterized by The permanent magnetic alloy powder is prepared by a rapid quenching method, and in the preparation process, the primary cooling surface has balloon-shaped holes arranged in the same direction.

19. A method of producing a permanent magnetic alloy powder, characterized by, The method comprises the following steps: Step 1, preparing raw materials required for alloying compounds according to the element proportion of the permanent magnetic alloy powder in any one of claims 1-8, and smelting into a permanent magnetic alloy; Step 2, rapidly cooling the permanent magnetic alloy at a temperature above the melting point into an alloy strip with partial microcrystalline size or amorphous; Step 3, performing crystal structure regulation treatment on the alloy strip or not; Step 4, crushing the alloy strip with or without regulation treatment to a required size to obtain a permanent magnetic alloy powder.

20. The method of claim 19, wherein the alloy powder is prepared by a method comprising: In step 1, the permanent magnetic alloy smelted has a morphology of a sheet, a plate or a column with a minimum direction size of more than 0.2 mm.

21. The method of claim 19, wherein the alloy powder is prepared by a method comprising: In step 2, the thickness direction size of the alloy strip is 30-60 microns, and the width direction size is 2-5 mm.

22. The method of claim 19, wherein the alloy powder is prepared by a method comprising: In step 2, the grain size in the alloy strip is 0-100 nm.

23. The method for preparing permanent magnet alloy powder according to claim 19, characterized in that: In step 2, when the rapid cooling treatment is performed, the cooling mass flow rate is 60-120 kg / h.

24. The method of claim 19, wherein the permanent magnetic alloy powder is prepared by a method comprising: In step 2, when the rapid cooling treatment is performed, the primary cooling heat conduction medium used is a ring structure made of metal molybdenum, titanium-zirconium-molybdenum alloy or molybdenum-lanthanum alloy. ​ 25. The method of claim 19, wherein the alloy powder is a permanent magnet alloy powder. In step 2, when the rapid cooling treatment is performed, the rotating linear speed of the primary cooling heat conduction medium used is 10-35 m / s.

26. The method of claim 19, wherein the permanent magnetic alloy powder is prepared by a method comprising: In step 3, the alloy strip is subjected to a crystal structure regulating treatment, and the crystal structure is regulated by heat treatment, and the treatment temperature is 300-800℃. ​ 27. The method of claim 19, wherein the alloy powder is a permanent magnet alloy powder. The permanent magnet alloy powder has a grain size of 10-100nm.

28. A permanent magnet, characterized by The permanent magnet alloy powder according to any one of claims 1-18 is used as a raw material.

29. A method of making the permanent magnet of claim 28, wherein, The method comprises the following steps: The permanent magnet alloy powder according to any one of claims 1-18 is used as a raw material together with a polymer binder to prepare a permanent magnet by compression molding, injection molding or calendering.

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