Niobium-containing neodymium-iron-boron magnet easy to recycle and preparation method thereof

Abstract

The invention relates to the technical field of rare earth permanent magnet materials, in particular to a niobium-containing neodymium-iron-boron magnet easy to recycle and a preparation method thereof, and the preparation method comprises the following steps: S1, preparing magnetic powder with the component of (A1-xRx) yFebalNbzMuCovBw; s2, preparing the magnetic powder into a green body; s3, sintering the green body to prepare a sintered magnet; and S4, carrying out aging treatment on the sintered magnet to obtain the niobium-containing neodymium-iron-boron magnet easy to recycle. The prepared niobium-containing neodymium-iron-boron magnet has fewer types of alloying elements, can maintain better initial magnetic performance and is also easy to recycle, the remanufactured magnet has better performance, and the problems that the alloying elements in the existing commercial neodymium-iron-boron magnet have too many types and are difficult to recycle and the cost is high can be solved. And the magnetic performance of the remanufactured magnet is restricted.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth permanent magnetic materials, and in particular to a niobium-containing neodymium iron boron magnet that is easy to recycle and reuse, and a preparation method thereof. Background Art

[0002] NdFeB magnets have the advantages of high energy density and high cost performance, and are currently the most widely used rare earth permanent magnet materials. NdFeB magnets are mainly composed of three elements: Nd, Fe, and B. The main components of the magnet are Nd2Fe 14 B phase and Nd-rich phase, in which Nd2Fe 14 B is the source of the permanent magnetic properties of NdFeB magnets; Nd-rich phase is formed in Nd2Fe 14 B grain boundaries, isolating Nd2Fe 14 B phase grains, thereby increasing the coercive force of the magnet.

[0003] The main technical indicators for measuring permanent magnetic properties include remanence B r , coercive force H c , maximum magnetic energy product (B.H.) max and service temperature. The above magnetic properties are mainly affected by the Nd2Fe 14 Saturation magnetization of the B main phase J S , magnetic anisotropy field H A and Curie temperature T C Due to the influence of intrinsic magnetic properties, Nd2Fe 14 The low anisotropy field and Curie temperature of the B phase can easily lead to low magnetic properties of NdFeB magnets. To improve the comprehensive magnetic properties of NdFeB magnets and consider the production cost, the industry generally uses elements such as Gd, Dy, Tb and Y to replace Nd, or uses mixed rare earths and high-abundance rare earth LaCe as raw materials to produce NdFeB magnets. However, the addition of different rare earth elements also causes different rare earth elements to be mixed into the Nd-rich phase (forming a rare earth-rich phase). The distribution and magnetic properties of grain boundary phases such as the rare earth-rich phase will also affect the magnetic properties of NdFeB magnets. Therefore, various alloying elements such as Cu, Al, Ga, Zr and Ti are further added to NdFeB magnets to control the coercivity of the magnets.

[0004] Therefore, in order to make the magnetic properties of the initial NdFeB magnets meet market requirements, the types of elements in existing commercial NdFeB magnets are usually as high as more than ten types (especially more alloying elements need to be added). However, too many types of elements (especially alloying elements) will affect the recycling of NdFeB magnets: on the one hand, the re-separation and purification of multiple elements is difficult and costly; on the other hand, the remade magnets have the problems of rare earth content loss, mutual influence between alloying elements, and the need to continue to add alloying elements during the remaking process, resulting in the total alloying element content in the final remade magnets being too high, which will restrict the magnetic properties of the remade magnets. Summary of the Invention

[0005] In response to the problems raised in the background technology, the first purpose of the present invention is to propose a method for preparing niobium-containing NdFeB magnets that are easy to recycle and reuse. By adding an appropriate amount of Nb element while reducing the addition of other alloying elements, a NdFeB magnet containing Nb and few alloying elements is prepared. The NdFeB magnet can maintain good initial magnetic properties while being easy to recycle. The remade magnet can maintain a high remanence, and can also maintain a coercive force and temperature stability similar to those of the magnet before remaking, and improve the Curie temperature of the main phase of the magnet. It can solve the problem that there are too many types of alloying elements in existing commercial NdFeB magnets, the recycling quality is poor, it is difficult to recycle and restricts the magnetic properties of the remade magnet.

[0006] The second object of the present invention is to provide a niobium-containing NdFeB magnet that is easy to recycle and reuse, which is prepared by the above-mentioned method for preparing a niobium-containing NdFeB magnet that is easy to recycle and reuse. It can maintain good initial magnetic properties while being easy to recycle, and the magnet has good performance after being remade.

[0007] To achieve the above object, the present invention proposes a method for preparing a niobium-containing neodymium iron boron magnet that is easy to recycle and reuse, comprising the following steps: Step S1. Preparing a composition (A 1-x R x ) y Fe bal Nb z M u Co v B wThe magnetic powder, wherein A is one or two elements of rare earth elements Nd and Pr, R is one or more elements of rare earth elements Gd, Ce, Y, Ho, Dy and Tb, M is any one of elements Cu, Al and Ga, x, y, z, u, v, w and bal are mass percentages, 0≤x≤0.5, 28≤y≤33, 0<z≤2, 0≤u≤2, 0≤v≤2, 0.8≤w≤1.2, and bal is the balance; Step S2. Prepare the magnetic powder into a green compact; Step S3. Sinter the green compact to prepare a sintered magnet; Step S4. Perform aging treatment on the sintered magnet to obtain a niobium-containing Nd-Fe-B magnet that is easy to recycle and reuse.

[0008] Optionally, in the step S1, the magnetic powder is prepared by a melting and rapid solidification - hydrogen decrepitation - jet milling process.

[0009] Optionally, in the step S1, the magnetic powder is prepared by a hydrogenation - disproportionation - dehydrogenation - recombination process.

[0010] Optionally, in the step S1, the magnetic powder is prepared by a rapid quenching method.

[0011] Optionally, in the step S1, the magnetic powder is prepared by mixing alloys or magnetic powders with various different compositions.

[0012] Optionally, in the step S2, the magnetic powder is prepared into a green compact by a one-time forming method or a two-time forming method.

[0013] Optionally, in the step S3, the sintering temperature is 1000°C to 1100°C, and the sintering holding time is 1h to 8h.

[0014] Optionally, in the step S3, the temperature for aging treatment is 400 to 950°C, and the holding time for aging treatment is 1h to 8h.

[0015] Optionally, in the step S, the steps for aging treatment include: Step S41. Primary aging treatment: The temperature of the primary aging treatment is 800°C to 至950°C, and the time is 1h to 8h; Step S42. Secondary aging treatment: The temperature of the secondary aging treatment is 400°C to 650°C, and the time is 1h to 8h.

[0016] The present invention also provides a niobium-containing Nd-Fe-B magnet that is easy to recycle and reuse, which is prepared by using the preparation method of the niobium-containing Nd-Fe-B magnet that is easy to recycle and reuse as described in any one of the above. Compared with the prior art, the embodiments of the present invention have the following beneficial effects: Starting from controlling the types of alloying elements, by adding an appropriate amount of Nb element and reducing the addition of other alloying elements, the Curie temperature of the main phase can be increased, the temperature stability of the magnet can be improved, and the remanence of the magnet can also be increased. In addition, the Nb element will form the NbFeB phase with Fe and B elements. On the one hand, it hinders grain growth. On the other hand, as the B content decreases, the proportion of the rare-earth-rich phase in the magnet increases, which can improve the coercivity of the magnet. The prepared niobium-containing NdFeB magnet has fewer types of alloying elements (not exceeding 3 types), can maintain good initial magnetic properties and is easy to recycle and reuse. Detailed implementation manners

[0017] The present invention provides a method for preparing a niobium-containing NdFeB magnet that is easy to recycle and reuse, comprising the following steps: Step S1. Prepare magnetic powder with a composition of (A 1-x R x ) y Fe bal Nb z M u Co v B w , where A is one or two elements of the rare-earth elements Nd and Pr, R is one or more elements of the rare-earth elements Gd, Ce, Y, Ho, Dy and Tb, M is any one element of the elements Cu, Al and Ga, x, y, z, u, v, w and bal are mass percentages, 0 ≤ x ≤ 0.5, 28 ≤ y ≤ 33, 0 < z ≤ 2, 0 ≤ u ≤ 2, 0 ≤ v ≤ 2, 0.8 ≤ w ≤ 1.2, and bal is the balance; Step S2. Prepare a green compact from the magnetic powder; Step S3. Sinter the green compact to prepare a sintered magnet; Step S4. Perform aging treatment on the sintered magnet to obtain a niobium-containing NdFeB magnet that is easy to recycle and reuse.

[0018] The present invention starts with controlling the types of alloying elements. By adding an appropriate amount of Nb element while reducing the addition of other alloying elements, a NdFeB magnet containing Nb and a small number of alloying elements is prepared. The appropriate addition of Nb element can not only increase the Curie temperature of the main phase and improve the temperature stability of the magnet, but also increase the remanence of the magnet. In addition, Nb element will form NbFeB phase with Fe and B elements, which on the one hand hinders grain growth, and on the other hand reduces the B content and increases the proportion of rare earth-rich phase in the magnet, which can ensure the coercive force of the magnet. Moreover, the composition of the magnetic powder of the present invention can be selected without adding R (one or more rare earth elements Gd, Ce, Y, Ho, Dy and Tb), M (one element Cu, Al and Ga) or Co element, so that the overall elements in the prepared NdFeB magnet containing niobium are The number of elements is relatively small (especially the number of alloying elements is no more than 3), which can maintain good initial magnetic properties while being easy to recycle and remake into magnets: on the one hand, the number of elements contained in the magnet as a whole is relatively small (especially the number of alloying elements is relatively small), which makes it easy to re-separate, purify and recycle; on the other hand, since the number of elements contained in the magnet waste is relatively small, the entropy is low and the quality is high, the magnetic properties of the magnet are easy to control during the process of remaking the magnet (cleaning the surface of the magnet waste or remelting and rapid solidification, then hydrogen cracking, air flow grinding, molding, sintering and aging); experiments have shown that by adding Nb elements while reducing other alloying elements, the magnet obtained can maintain good initial magnetic properties, and the remade magnet can maintain a high remanence and maintain a coercive force and temperature stability similar to that of the magnet before remaking, while also improving the Curie temperature of the main phase of the magnet. Therefore, the present invention can solve the problem that the number of elements in the existing commercial NdFeB magnets is too large to be recycled and the magnetic properties of the remade magnets are restricted.

[0019] To further illustrate, in step S1, the magnetic powder is prepared by a melting rapid solidification-hydrogen crushing-air flow milling process.

[0020] To further illustrate, in step S1, the magnetic powder is prepared by a hydrogenation-disproportionation-dehydrogenation-recombination process.

[0021] To further illustrate, in step S1, the magnetic powder is prepared by a rapid quenching method.

[0022] It is understandable that the magnetic powder prepared by the smelting rapid solidification-hydrogen crushing-air flow grinding process, the magnetic powder prepared by the hydrogenation-disproportionation-dehydrogenation-recombination process (HDDR process), or the rapid quenching magnetic powder prepared by the rapid quenching method can all be used to prepare the niobium-containing NdFeB magnet that is easy to recycle and reuse as described in the present invention, and can be selected according to actual production needs.

[0023] Further, in step S1, the magnetic powder is prepared by mixing a plurality of alloys of different compositions or a plurality of magnetic powders of different compositions. It is understood that the magnetic powder can be prepared by mixing a plurality of alloys of different compositions; the magnetic powder can also be prepared by mixing a plurality of magnetic powders of different compositions, and the final composition of the magnetic powder is maintained as follows: (A 1-x R x ) y Fe bal Nb z M u Co v B w That's it.

[0024] To further illustrate, in step S2, the magnetic powder is formed into a green compact by a primary molding method or a secondary molding method. More specifically, the magnetic powder can be formed into a green compact by magnetic field orientation molding (in this case, the primary molding method) or by magnetic field orientation molding and cold isostatic pressing (in this case, the secondary molding method). Specifically, the primary molding method or the secondary molding method can be selected based on the composition of the magnetic powder.

[0025] Furthermore, in step S3, the sintering temperature is 1000° C. to 1100° C., and the sintering holding time is 1 hour to 8 hours. Specifically, the appropriate sintering temperature and corresponding holding time can be selected according to the composition of the magnetic powder.

[0026] Furthermore, in step S3, the aging treatment temperature is 400-950°C, and the holding time is 1-8 hours. Specifically, the aging treatment temperature and holding time can be selected appropriately according to the composition of the magnetic powder.

[0027] Specifically, the aging treatment in step S4 includes: step S41: primary aging treatment, which is performed at a temperature of 800°C to 950°C for 1 to 8 hours; and step S42: secondary aging treatment, which is performed at a temperature of 400°C to 650°C for 1 to 8 hours. Specifically, the appropriate aging treatment temperature and holding time can be selected based on the composition of the magnetic powder.

[0028] The present invention also provides a niobium-containing NdFeB magnet that is easily recyclable and reused, which is prepared using the method for preparing a niobium-containing NdFeB magnet that is easily recyclable and reused as described in the above item.

[0029] The niobium-containing NdFeB magnets produced by the present invention maintain excellent initial magnetic properties while being easily recyclable. The remanufactured magnets maintain high remanence, coercivity, and temperature stability similar to those of the unmanufactured magnets, while also improving the Curie temperature of the magnet's main phase. Therefore, the present invention addresses the problem of existing commercial NdFeB magnets containing an excessive number of elements (especially alloying elements), making them difficult to recycle and limiting the magnetic properties of the remanufactured magnets.

[0030] For ease of understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0031] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. All reagents or instruments used without specifying the manufacturer are commercially available conventional products.

[0032] (1) Example 1, Comparative Example 1.1 and Comparative Example 1.2: (1) Example 1: A method for preparing a niobium-containing neodymium iron boron magnet that is easily recyclable and reusable comprises the following steps: Step S1. Magnetic powder is prepared by a melting rapid solidification-hydrogen crushing-air flow milling process. The composition of the magnetic powder is: [(Pr,Nd)] 30.8 Fe bal Nb 0.5 Co 0.8 B 0.96 ; Step S2. preparing the magnetic powder into a green compact by a one-step molding process (orientation molding in a magnetic field); Step S3: sintering the green compact to prepare a sintered magnet at a sintering temperature of 1060°C and a sintering holding time of 3 hours; Step S4. Performing aging treatment on the sintered magnet to obtain a niobium-containing NdFeB magnet that is easy to recycle and reuse; the steps of performing aging treatment include: Step S41. Primary aging treatment: the temperature of the primary aging treatment is 890°C and the time is 4 hours; Step S42. Secondary aging treatment: the temperature of the secondary aging treatment is 540°C and the time is 4.5 hours.

[0033] (2) Comparative Example 1.1: The difference between Comparative Example 1.1 and Example 1 is that the composition of the magnetic powder is different, and the other preparation methods are the same as those of Example 1.

[0034] The composition of the magnetic powder of Comparative Example 1.1 is: [(Pr, Nd)] 30.8 Fe bal Zr 0.15 B 0.96 Cu 0.1 Ga 0.1 Al 0.2 Co 0.8 .

[0035] (3) Comparative Example 1.2: The difference between Comparative Example 1.2 and Example 1 lies in the different composition of the magnetic powder, the different sintering temperature in step S3, and the different secondary aging temperature in step S4. The other preparation methods are the same as those in Example 1.

[0036] The composition of the magnetic powder of Comparative Example 1.2 is: [(Pr, Nd)] 30.8 Fe bal Co 0.8 B 0.96 ; The sintering temperature in step S3 is 1000°C, and the secondary aging temperature in step S4 is 460°C.

[0037] (4) Magnetic performance test and result analysis: The magnetic properties of the magnets of Example 1, Comparative Example 1.1 and Comparative Example 1.2 were tested by a pulse magnetic field meter (PFM). The test results are shown in Table 1 below, where B r Remanence, H cj represents the coercive force, (B.H.) max represents the maximum magnetic energy product, β (20-80℃) Indicates the coercive force temperature stability coefficient (the smaller the absolute value of the coercive force temperature stability coefficient, the better the temperature stability of the magnet).

[0038] Table 1 Test results of Example 1, Comparative Example 1.1 and Comparative Example 1.2 .

[0039] Compared with the magnets of Comparative Example 1.2, Example 1 added two alloying elements, Nb and Co, while Comparative Example 1.2 only added Co. The remanence, coercivity, maximum magnetic energy product, Curie temperature of the main phase, and temperature stability of the magnets were all poor. The addition of Nb to the magnets of Example 1 not only hindered abnormal grain growth but also increased the proportion of the rare earth-rich phase in the magnets, thereby improving the coercivity of the magnets. It also maintained the high remanence of the magnets and improved the Curie temperature of the main phase and the temperature stability of the magnets.

[0040] Compared with the magnet of Comparative Example 1.1, the coercive force of the magnet can be improved to a certain extent because five alloying elements, namely Zr, Cu, Al, Ga and Co, are added to Comparative Example 1.1. However, the improvement is not large compared with the coercive force of the magnet of Example 1. At the same time, the addition of non-magnetic alloying elements (Cu, Al and Ga) will also cause the remanence of the magnet to drop significantly, and the maximum magnetic energy product (energy density) will also be significantly reduced.

[0041] (II) Example 2 and Comparative Example 2: (1) Example 2: A method for preparing a niobium-containing neodymium iron boron magnet that is easily recyclable and reusable comprises the following steps: Step S1. Two magnetic powders with different compositions are prepared by the HDDR process (hydrogenation-disproportionation-dehydrogenation-recombination process). The compositions of the two magnetic powders are: [(Pr, Nd) 0.5 Ce 0.5 ] 32 Fe bal Nb 0.2 B 1.0 Ga 0.5 and (Pr,Nd) 32 Fe bal Nb 0.2 B 1.0 Ga 0.5 The two magnetic powders with different compositions are mixed in a ratio of 4:1 to obtain the final magnetic powder. The composition of the final magnetic powder is [(Pr, Nd) 0.6 Ce 0.4 ] 32 Fe bal Nb 0.2 B 1.0 Ga 0.5 ; Step S2. preparing the final magnetic powder into a green compact through a secondary molding process (orientation molding in a magnetic field and cold isostatic pressing); Step S3: sintering the green compact to prepare a sintered magnet at a sintering temperature of 1020° C. and a sintering holding time of 2.5 h; Step S4. Performing aging treatment on the sintered magnet to obtain a niobium-containing NdFeB magnet that is easy to recycle and reuse; the aging treatment steps include: Step S41. Primary aging treatment: the temperature of the primary aging treatment is 890°C and the time is 2.5 hours; Step S42. Secondary aging treatment: the temperature of the secondary aging treatment is 650°C and the time is 2 hours.

[0042] The prepared magnet was remade: the surface of the final magnet was ground to a metallic luster, and the magnetic powder was obtained again by hydrogen crushing and air flow grinding, and then 1% PrNdH was added. aThe powder (where a indicates that it contains a small amount of H element) is remade into a magnet through the same secondary molding process, sintering and aging treatment process.

[0043] (2) Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that the composition of the magnetic powder used is different, and the other preparation methods are the same as those of Example 2.

[0044] Comparative Example 2: Two magnetic powders with different compositions were prepared by HDDR process. The compositions of the two magnetic powders were: [(Pr, Nd) 0.5 Ce 0.5 ] 32 Fe bal Zr 0.1 B 1.0 Co 0.8 Cu 0.1 Al 0.2 Ga 0.5 and (Pr,Nd) 32 Fe bal Zr 0.1 B 1.0 Co 0.8 Cu 0.1 Al 0.2 Ga 0.5 , the final composition of the magnetic powder is: [(Pr,Nd) 0.6 Ce 0.4 ] 32 Fe bal Zr 0.1 B 1.0 Co 0.8 Cu 0.1 Al 0.2 Ga 0.5 .

[0045] (3) Magnetic performance test and result analysis: The magnetic properties of the magnets of Example 2 and Comparative Example 2 before and after remaking were tested using a impulse magnetic field meter (PFM). The test results are shown in Table 2 below.

[0046] Table 2 Test results of Example 2 and Comparative Example 2 .

[0047] Example 2 can maintain the high remanence characteristics of the magnet by adding Nb elements and reducing the types of other alloying elements (only Nb and Ga elements are added). Compared with the magnet before reconstruction in Comparative Example 2, the coercive force remains similar, and the remanence, maximum magnetic energy product, Curie temperature of the main phase and temperature stability are significantly improved.

[0048] In addition, the magnet of Example 2 contains only 7 types of elements (of which only 2 types are alloying elements, namely Nb and Ga elements), which is easier to recycle and reuse, and the coercive force of the magnet after remaking decreases less (decreases by 0.4kOe), while still maintaining a high remanence and good temperature stability, and can further improve the Curie temperature of the main phase; while the magnet of Comparative Example 2 contains as many as 10 types of elements (of which 5 types are alloying elements, namely Zr, Co, Cu, Al, and Ga elements), which is more difficult to remake into a magnet, and the coercive force of the magnet after remaking decreases more (decreases by 1.5kOe), and the magnetic properties of the magnet after remaking of Example 2 are better than those of the magnet after remaking of Comparative Example 2.

[0049] In summary, by adding Nb element and reducing other alloying elements, Example 2 has better initial comprehensive magnetic properties of the magnet, and when it is used as a raw material to remake the magnet, the quality is higher, which is more conducive to recycling and preparing magnets with higher comprehensive magnetic properties.

[0050] (III) Example 3 and Comparative Example 3: (1) Example 3: A method for preparing a niobium-containing neodymium iron boron magnet that is easily recyclable and reusable comprises the following steps: Step S1. Prepare a molten metal having a composition of [(Pr, Nd)] by a rapid quenching process. 0.902 Dy 0.098 ] 30.5 Fe bal Nb 0.5 B 1.0 Ga 0.15 Magnetic powder; Step S2. preparing the final magnetic powder into a green compact through a secondary molding process (orientation molding in a magnetic field and cold isostatic pressing); Step S3: sintering the green compact to prepare a sintered magnet at a sintering temperature of 1070°C and a sintering holding time of 4.5h; Step S4. Performing aging treatment on the sintered magnet to obtain a niobium-containing NdFeB magnet that is easy to recycle and reuse; the steps of performing aging treatment include: Step S41. Primary aging treatment: the temperature of the primary aging treatment is 890°C and the time is 6 hours; Step S42. Secondary aging treatment: the temperature of the secondary aging treatment is 480°C and the time is 4.5 hours.

[0051] The prepared magnet was remade: the surface of the final magnet was ground to a metallic luster, and the magnetic powder was obtained again by hydrogen crushing and air flow grinding, and 1% [(Pr, Nd) 0.902 Dy 0.098 ] 30.5 Fe bal Nb0.5 B 1.0 Ga 0.15 The powder is remade into magnets through the same secondary molding process, sintering and aging treatment.

[0052] (2) Comparative Example 3.1 and Comparative Example 3.2: The difference between Comparative Example 3.1 and Example 3 is that the composition of the magnetic powder is different, and the other preparation methods are the same as Example 3.

[0053] The magnetic powder composition of Comparative Example 3.1 is: [(Pr,Nd) 0.902 Dy 0.098 ] 30.5 Fe bal Nb 0.5 B 1.0 Ga 0.15 Zr 0.1 Co 0.8 Cu 0.1 Al 0.2 .

[0054] The difference between Comparative Example 3.2 and Comparative Example 3.1 is that the composition and amount of the magnet powder added when the prepared magnet is remade are different. The other preparation methods are the same as those of Comparative Example 3.1.

[0055] When the magnet prepared in Comparative Example 3.2 is remade, it is necessary to add 2% of [(Pr,Nd) 0.902 Dy 0.098 ] 30.5 Fe bal Nb 0.5 B 1.0 Ga 0.15 Zr 0.1 Co 0.8 Cu 0.1 Al 0.2 powder.

[0056] (3) Magnetic performance test and result analysis: The magnetic properties of the magnets of Example 3, Comparative Example 3.1, and Comparative Example 3.2 before and after remaking were tested using a pulse field meter (PFM), and the test results are shown in Table 3. The magnetic properties of the magnets of Comparative Example 3.1 and Comparative Example 3.2 before remaking were the same.

[0057] Table 3 Test results of Example 3 and Comparative Example 3 .

[0058] Example 3, by simply adding a certain amount of Nb and Ga, maintains the magnet's high remanence while effectively increasing its coercivity. Compared to the unreformed magnets of Comparative Examples 3.1 and 3.2, Example 3 exhibits superior remanence, coercivity, maximum magnetic energy product, Curie temperature of the main phase, and temperature stability.

[0059] In addition, the final magnet of Example 3 contains only 7 types of elements (of which only 2 types are alloying elements, namely Nb and Ga elements), which is easier to recycle and reuse, and the coercive force of the remade magnet decreases less (decreases by 1.3kOe), while still maintaining a high remanence, Curie temperature and good temperature stability; while the magnet of Comparative Example 3.1 contains as many as 11 types of elements (of which 6 types are alloying elements, namely Nb, Zr, Co, Cu, Al, and Ga elements), and it is more difficult to re-separate and purify multiple elements when remaking the magnet, the coercive force of the remade magnet decreases more (decreases by 3.1kOe), and the magnetic properties of the remade magnet of Example 3 are better than those of the remade magnet of Comparative Example 3.1.

[0060] Obviously, Example 3 improves the initial magnetic properties of the magnet by adding Nb element, and when it is used as a raw material to remake the magnet, the quality is higher, which is more conducive to the recycling and preparation of higher performance magnets.

[0061] In addition, from the magnetic property results of the remade magnet in Comparative Example 3.2, it can be seen that 2% of magnetic powder needs to be added again when the magnet is remade in order to obtain magnetic properties close to those of the initial magnet, while Example 3 only needs to add 1% of magnetic powder again during remaking, so that the remade magnet can maintain a higher remanence, Curie temperature and temperature stability of the magnet. It can reduce the input of additional magnetic powder and other materials during remaking, and can reduce the cost of recycling magnets while maintaining higher magnet performance.

[0062] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A method for preparing a niobium-containing neodymium iron boron magnet that is easily recyclable, characterized in that: The following steps are involved: Step S1. Prepare magnetic powder with the composition (A 1-x R x ) y Fe bal Nb z M u Co v B w , where A is one or two elements of the rare earth elements Nd and Pr, R is one or more elements of the rare earth elements Gd, Ce, Y, Ho, Dy and Tb, M is any one element of the elements Cu, Al and Ga, x, y, z, u, v, w and bal are mass percentages, 0 ≤ x ≤ 0.5, 28 ≤ y ≤ 33, 0 < z ≤ 2, 0 ≤ u ≤ 2, 0 ≤ v ≤ 2, 0.8 ≤ w ≤ 1.2, and bal is the balance; Step S2. preparing the magnetic powder into a green compact; Step S3. sintering the green compact to prepare a sintered magnet; Step S4: performing aging treatment on the sintered magnet to obtain a niobium-containing NdFeB magnet that is easy to recycle and reuse.

2. The method for preparing a niobium-containing NdFeB magnet that is easily recyclable according to claim 1, characterized in that: In the step S1, the magnetic powder is prepared by a melting rapid solidification-hydrogen crushing-air flow milling process.

3. The method for preparing a niobium-containing NdFeB magnet that is easily recyclable according to claim 1, characterized in that: In the step S1, the magnetic powder is prepared by a hydrogenation-disproportionation-dehydrogenation-recombination process.

4. The method for preparing a niobium-containing NdFeB magnet that is easily recyclable according to claim 1, wherein: In the step S1, the magnetic powder is prepared by a rapid quenching method.

5. The method for preparing a niobium-containing NdFeB magnet that is easily recyclable according to claim 1, characterized in that: In the step S1, the magnetic powder is prepared by mixing alloys of multiple different compositions or magnetic powders of multiple different compositions.

6. The method for preparing a niobium-containing NdFeB magnet that is easily recyclable according to claim 1, characterized in that: In the step S2, the magnetic powder is prepared into a green compact by a primary molding method or a secondary molding method.

7. The method for preparing a niobium-containing NdFeB magnet that is easily recyclable according to claim 1, wherein: In step S3, the sintering temperature is 1000° C. to 1100° C., and the sintering holding time is 1 hour to 8 hours.

8. The method for preparing a niobium-containing NdFeB magnet that is easily recyclable according to claim 1, characterized in that: In step S3, the temperature for aging treatment is 400-950° C., and the holding time for aging treatment is 1 hour-8 hours.

9. The method for preparing a niobium-containing NdFeB magnet that is easily recyclable according to claim 1, characterized in that: In step S4, the step of performing aging treatment includes: Step S41. Primary aging treatment: the temperature of the primary aging treatment is 800°C to 950°C, and the time is 1h to 8h; Step S42. Secondary aging treatment: The temperature of the secondary aging treatment is 400° C. to 650° C., and the time is 1 hour to 8 hours.

10. A niobium-containing neodymium iron boron magnet that is easily recyclable, characterized in that: The magnet is prepared using the method for preparing a niobium-containing neodymium iron boron magnet that is easily recyclable as described in any one of claims 1 to 9.