RHxM1yBz alloy, manufacturing method of RHxM1yBz alloy, and manufacturing method of neodymium-iron-boron sintered magnet

Abstract

The present invention discloses a high-performance neodymium-iron-boron sintered magnet and a method for producing the same. 1 m Fe n B p M 2 w The base material is R H x M 1 y B z The alloy is used as a diffusion source and is manufactured by diffusion heat treatment. H x M 1 y B z By using an alloy as a diffusion source and diffusing it using a detachable material reaction barrel, rare earth permanent magnets with high cost performance can be efficiently manufactured, thereby solving the problems of fusion and adhesion between the diffusion source and base material in the diffusion process, improving the Hcj of the NdFeB-based sintered magnet, and solving the problem of improving the efficiency of the diffusion process. Furthermore, the diffusion source of the present invention can be reused, reducing the manufacturing costs of NdFeB-based sintered magnets, and can be applied to magnets with relatively large sizes, ensuring mass production of cost-effective sintered NdFeB-based products, especially those with a thickness of 8 to 30 mm in the orientation direction.

Description

[Technical Field]

[0001] This application claims priority from a prior application bearing patent application number 202110819841.5 and entitled "High-performance neodymium-iron-boron sintered magnet and manufacturing method thereof," filed with the State Intellectual Property Office of the People's Republic of China on July 20, 2021. The prior application is incorporated herein by reference in its entirety.

[0002] The present invention relates to the field of rare earth permanent magnetic materials, and more particularly to high-performance neodymium-iron-boron sintered magnets and methods for producing the same. [Background technology]

[0003] NdFeB magnets are currently considered to be permanent magnets with relatively excellent performance, although their performance varies. The most outstanding performance is achieved by high-performance sintered NdFeB magnets, which are obtained by using processes such as melt spinning, hydro-crushing, jet milling, pressing, and sintering, as well as oxygen-free processes, to produce NdFeB-based sintered permanent magnet materials with a sum of Hcj (intrinsic coercivity, KOe) and (BH)max (maximum magnetic energy product, MGOe) greater than 60. In recent years, developing a NdFeB magnet manufacturing process that significantly improves Hcj while minimizing the decrease in Br and increasing costs has become an important goal for NdFeB magnet manufacturers. Initially, optimization of the composition, such as by substituting expensive heavy rare earths for light rare earths, and grain refinement were used to increase the magnetic energy product and coercivity of NdFeB magnets. At the same time, progress was made on grain boundary strengthening processes such as dual alloying and dual main phase processes. However, these processes all require high addition rates of heavy rare earths, resulting in a significant decrease in Br. Furthermore, the development of these processes has been hindered by the limited reserves and relatively high cost of the commonly used heavy rare earths, Dy and Tb. In recent years, a new process for improving the Hcj performance of NdFeB magnets has been developing relatively rapidly in the industry: sintered NdFeB grain boundary diffusion rare earths and rare earth alloys. This cost-effective process plays an important role in conserving rare earth permanent magnet resources, promoting product upgrades and redesigns, energy conservation, emission reduction, and sustainable development.

[0004] For example, patent application CN101707107A discloses a method for manufacturing a rare earth permanent magnet material with high remanence and high coercivity, which includes the process steps of preparing a master alloy, grinding, molding, and sintering to produce a sintered magnet, aging, machining, and surface treatment. After the process step of sintering to produce a sintered magnet R1-TB-M1, the sintered magnet is embedded in a pre-mixed powder consisting of a heavy rare earth HR2M2 alloy powder and one or more powders of R3 oxide, R4 fluoride, and R5 fluoride. HR2 is at least one of Dy, Ho, and Tb, and M 2 R is at least one of Al, Cu, Co, Ni, Mn, Ga, In, Sn, Pb, Bi, Zn, and Ag, and R3, R4, and R5 are one or more rare earth elements, including Y and Sc. In the above method, a certain gap must be maintained between the magnets during the diffusion process; otherwise, there is a risk of adhesion at the contact surfaces of the magnets, which will affect their appearance. Therefore, workers must space the magnets apart, which reduces work efficiency and affects the charging rate, thereby reducing production efficiency.

[0005] The patent application with publication number CN106298219A discloses a method for manufacturing an RTB rare earth permanent magnet, which includes the following steps: a) using R as a diffusion source; L u R H v Fe 100-u-v-w-z B w M z Manufacture rare earth alloys and L represents at least one element selected from the group consisting of Pr and Nd, and R H represents at least one element selected from Dy, Tb, and Ho; M represents at least one element selected from Co, Nb, Cu, Al, Ga, Zr, and Ti; the rare earth alloy comprises an R-Fe-B tetragonal main phase structure; u, v, w, and z are weight percents of each substance, and u, v, w, and z satisfy the relationships 0≦u≦10, 35≦v≦70, 0.5≦w≦5, and 0≦z≦5; and b) R L u RH v Fe 100-u-v-w-z B w M z A rare earth alloy is crushed to form an alloy powder; c) the alloy powder is placed in a diffusion device together with an RTB magnet and thermally diffused at a temperature of 750-950°C for a time period of 4-72 hours; and d) an aging treatment is performed. The diffusion source alloy used in this invention is an R-Fe-B alloy. However, if an R-Fe-B alloy is used as the diffusion source and the B content in the diffusion source is too high, its melting point is relatively high, resulting in a slower diffusion rate. This means that less active ingredient penetrates into the substrate in a given time period. Once the diffusion temperature is increased, the main phase crystal grains are destroyed, weakening the diffusion effect. This results in poor diffusion efficiency and less than ideal performance.

[0006] Patent application CN107731437A discloses a method for reducing irreversible loss in NdFeB-based sintered sheet magnets by mixing a light rare earth metal Nd, Pr, or PrNd alloy rapidly solidified sheet with a rejected NdFeB-based sintered sheet magnet in a certain ratio, then heat-treating the mixture in a diffusion furnace under certain rotational speed and temperature conditions. Finally, the diffused magnet is annealed at 460°C to 520°C for 3 to 5 hours. This invention uses the light rare earth metal Nd, Pr, or PrNd alloy rapidly solidified sheet as a diffusion source to diffuse Nd or Pr into the surface layer region of the block NdFeB-based sintered sheet magnet, which further repairs the damaged microstructure in the surface region of the NdFeB-based sintered sheet magnet, thereby increasing the coercive force of the NdFeB-based sintered sheet magnet. However, the diffusion source used in this process is a light rare earth, and because the diffusion effect of light rare earth is limited, it is relatively effective only for sheet products, and the improvement in Hcj performance is limited (only an increase of 1 to 3 KOe), and its effect on improving Hcj performance for slightly thicker products is unclear.

[0007] The patent application with publication number CN105321702A discloses a method for increasing the coercive force of NdFeB sintered magnets, which uses a grain boundary diffusion alloy material that does not contain heavy rare earth elements to increase the coercive force of NdFeB sintered magnets through the grain boundary diffusion method, and the components of the diffusion alloy are Re 100-x-y Al x M y where Re is one or more of Ce, Pr, and Nd, M is one or more of Mg and Cu, and 2≦x≦33, 0≦y≦5. The specific steps of this process are to vacuum-smelt a diffusion alloy, powder the diffusion alloy or rapidly quench it into a thin strip, coat the surface of a sintered NdFeB magnet with the diffusion alloy, and then diffuse it in a vacuum furnace at 600-1000°C for 1-10 hours and temper it at 500°C for 1-5 hours. In addition to the drawbacks of Patent Document CN107731437A, this method has the following drawbacks: the diffusion source is coated on the magnet surface and diffused; therefore, the diffusion source powder or fragments are likely to adhere to the magnet surface; and the gravity of the magnet itself causes varying degrees of depression on the lower surface, which affects the size and / or appearance of the product.

[0008] The patent application with publication number CN103003899A discloses a processing apparatus including a diffusion processing section, a separation section, and a heat treatment section, in which the diffusion processing section is for dissolving a Re-Fe-B based sintered magnet and a metal R containing a heavy rare earth element. H The diffusion source of the metal or alloy is rotated while being heated. The separation section receives the sintered magnet and R H From the diffusion source, R H The heat treatment section selectively separates the diffusion source, and the heat treatment section separates the R from the Re-Fe-B sintered magnet in which the heavy rare earth elements are diffused. HThis heat treatment is performed with the diffusion source removed. Cold spots are likely to occur at the connection points between different cavities in this equipment, making it difficult to ensure a uniform temperature zone within the furnace. Meanwhile, the diffusion zone and heat treatment zone require a relatively long cycle time, while the separation zone requires a relatively short cycle time. This means that this continuous treatment furnace cannot further improve efficiency. For example, when there is material in the diffusion zone, the separation zone and heat treatment zone are in a standby state without material, so there is no clear advantage over equipment with separate diffusion zones, separation zones, and heat treatment zones.

[0009] Therefore, how to solve the problems of adhesion and fusion between the diffusion source and the substrate in the diffusion process of NdFeB-based sintered magnets? The problems of insufficient improvement in Hcj, difficulty in improving diffusion efficiency, and the inability to reuse the diffusion source make NdFeB-based products relatively expensive and inapplicable to relatively large magnets. These are technical issues that need to be resolved as soon as possible. Summary of the Invention

[0010] In order to improve the above technical problems, the present invention H x M 1 y B z The alloy is provided as above. H is one or two elements selected from Dy and Tb, and M 1 represents one, two or three elements selected from Ti, Zr and Al, B represents boron, x, y and z represent the weight percentage of the element, and x, y and z satisfy the relationship 75%≦x≦90%, 0.1%≦z≦0.5%, and y=1-xz.

[0011] According to an embodiment of the present invention, the above R H x M 1 y B z In the alloy, 80%≦x≦85%, 0.15%≦z≦0.3%, and y=1−xz, illustratively x=80%, 81%, 82%, 83%, 84%, 85%, and z=0.1%, 0.15%, 0.2%, 0.25%, 0.3%.

[0012] According to an exemplary embodiment of the present invention, the R H x M 1 y B z In alloys, M 1 are preferably any two of Ti, Zr and Al elements, and the mass ratio of the two elements is 1:1 to 2:1, for example, 1:1, 1.5:1, 1:2, or 2:1.

[0013] According to an exemplary embodiment of the present invention, the R H x M 1 y B z In alloys, R H is Dy and M 1 are two of Ti and Al, and x=85%, z=0.4%, and y=14.6%. For example, the above R H x M 1 y B z The alloy is Dy 85% Ti 9.73% Al 4.87% B 0.4% is.

[0014] According to an exemplary embodiment of the present invention, the R H x M 1 y B z In alloys, R H is Tb and M 1 are two of Ti and Zr, and x=80%, z=0.3%, and y=19.7%. For example, the above R H x M 1 y B z The alloy is Tb 80% Ti 11.82% Zr 7.88% B 0.3% is.

[0015] According to an embodiment of the present invention, the above R H x M 1y B z The alloy may be in the form of a sheet, for example, having an average thickness of ≦10 mm, preferably ≦5 mm, illustratively 1 mm, 1.8 mm, 2 mm, 3 mm, 4 mm, 5 mm.

[0016] The present invention is H element, M 1 The raw materials containing the elements R and B are smelted and rapidly solidified to obtain the above-mentioned H x M 1 y B z The above R includes producing an alloy. H x M 1 y B z A method for producing the alloy is also provided.

[0017] According to an embodiment of the present invention, the above R H element, M 1 The elements A and B have the meanings given above.

[0018] According to an embodiment of the present invention, the above R H element, M 1 The amount of R and B elements used is H :M 1 :B are weighed in according to a weight ratio of x:y:z, where x, y and z have the above-mentioned meanings.

[0019] According to an embodiment of the present invention, the smelting is carried out in an inert gas atmosphere, for example, the inert gas atmosphere may be provided by argon gas and / or helium gas, and is preferably provided by argon gas.

[0020] According to an embodiment of the present invention, the smelting temperature is 1350°C to 1550°C, e.g., 1350°C, 1450°C, 1480°C, or 1500°C, and the smelting temperature retention time is 0 to 30 minutes, e.g., 5 minutes, 10 minutes, 20 minutes, or 30 minutes.

[0021] According to an embodiment of the present invention, the smelting is performed from when the raw materials are melted to form an alloy liquid until the alloy liquid is completely melted.

[0022] According to an embodiment of the present invention, the manufacturing method further includes cooling the smelted alloy liquid to a casting temperature after the alloy liquid is completely melted.

[0023] Preferably, the cooling rate is 3 to 9°C / min, for example, 3°C / min, 4°C / min, 6°C / min, 8°C / min, or 9°C / min.

[0024] Preferably, the casting temperature is 1330 to 1530°C, for example, 1340°C, 1400°C, 1430°C, or 1450°C.

[0025] According to an embodiment of the present invention, the manufacturing method includes: casting an alloy liquid cooled to a casting temperature by a spinning method; H x M 1 y B z This involves obtaining a rapidly bonding gold sheet.

[0026] According to an embodiment of the present invention, the above R H x M 1 y B z The average thickness of the rapidly bonded gold sheet is ≦10 mm, preferably ≦5 mm, illustratively 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm.

[0027] According to an exemplary embodiment of the present invention, the above-mentioned manufacturing method comprises: H element, M 1 The raw materials containing element B are smelted to form an alloy liquid, and after the alloy liquid is completely melted, it is cooled to the casting temperature and cast using the spinning method to form a R of average thickness ≦ 10 mm. H x M 1 y B z This involves obtaining a rapidly bonding gold sheet.

[0028] The present invention relates to the above-mentioned R in the production of sintered neodymium iron boron materials, preferably in the production of high-performance sintered neodymium iron boron materials. H x M 1 y B z The application of the alloy is further provided. Among them, the high-performance sintered neodymium iron boron material refers to a neodymium iron boron-based sintered permanent magnet material having a sum of Hcj (intrinsic coercivity, KOe) and (BH)max (maximum magnetic energy product, MGOe) greater than 60. Preferably, the R H x M 1 y B z The alloy is used as a diffusion source in the production of sintered neodymium iron boron materials.

[0029] The present invention is 1 m Fe n B p M 2 w is used as the base material, and R H x M 1 y B z The present invention also provides a neodymium-iron-boron sintered magnet produced by a diffusion heat treatment using an alloy as a diffusion source.

[0030] According to an embodiment of the present invention, the above R H x M 1 y B z Alloy has the meaning given above.

[0031] According to an embodiment of the present invention, the above R 1 m Fe n B p M 2 w In the substrate, the above R 1 represents one, two or more elements selected from the group consisting of Pr, Nd, Dy, Tb, Ho, Gd, Ce, La and Y elements, Fe represents iron element, B represents boron element, M 2is one, two or more elements selected from the group consisting of Ti, Zr, Co, V, Nb, Ni, Cu, Zr, Al and Ga elements.

[0032] Preferably, the above R 1 is selected from Nd and Dy, and the above M 2 is selected from Ti, Cu, Ga and Co.

[0033] According to an embodiment of the present invention, the above R 1 m Fe n B p M 2 w In the substrate, m is R 1 represents the weight percentage content of m, and 35%≧m≧27%, illustratively m=29%, 29.5%, 30%, 31%, 32%.

[0034] According to an embodiment of the present invention, the above R 1 m Fe n B p M 2 w In the substrate, n represents the weight percentage content of Fe, where 70%≧n≧60%, illustratively n=62%, 64%, 66.5%, 67.5%, 68.5%.

[0035] According to an embodiment of the present invention, the above R 1 m Fe n B p M 2 w In the substrate, p represents the weight percentage content of B, and the content of the B element is 0.8%≦p≦1.5%, for example, p=0.8%, 1.0%, 1.1%.

[0036] According to an embodiment of the present invention, R 1 m Fe n B p M 2 wThe manufacturing method of the substrate material includes manufacturing a magnet by smelting, milling, pressing, sintering and aging, and may further include machining and surface treatment steps.

[0037] According to an embodiment of the present invention, the thickness of the substrate in the orientation direction does not exceed 30 mm, for example, 1 to 30 mm, and can be divided into 1 to 8 mm, 8 to 15 mm, 15 to 20 mm, and 20 to 30 mm.

[0038] According to an embodiment of the present invention, the neodymium-iron-boron sintered magnet has an Hcj (intrinsic coercivity) of 20 kOe or more, preferably 21 to 29 kOe, e.g., 23.61 kOe, 24.45 kOe, 25.63 kOe, 26.40 kOe, 27.50 kOe, or 28.89 kOe.

[0039] According to an embodiment of the present invention, the Br of the neodymium-iron-boron sintered magnet is 13.8 to 14.6 kGs, e.g., 13.85 kGs, 13.94 kGs, 14.1 kGs, 14.2 kGs, 14.3 kGs, or 14.55 kGs.

[0040] According to an embodiment of the present invention, the density of the neodymium-iron-boron sintered magnet is 7.50 to 7.60 g / cm 3 , illustratively 7.50 g / cm 3 , 7.56 g / cm 3 , 7.60 g / cm 3 , preferably 7.56 g / cm 3 is.

[0041] The present invention further provides a method for producing the above-mentioned neodymium-iron-boron sintered magnet, the method comprising the steps of: Diffusion source R H x M 1 y B z Alloy and substrate materials R 1 m Fe n B p M 2 wand subjecting the mixture to a diffusion heat treatment to obtain the neodymium-iron-boron sintered magnet.

[0042] According to an embodiment of the present invention, the diffusion source R H x M 1 y B z Alloy and substrate R 1 m Fe n B p M 2 w The mass ratio is (1 to 5):1, illustratively 1:1, 1.5:1, 2:1, 2.3:1, 3:1, or 5:1.

[0043] According to an embodiment of the present invention, the diffusion heat treatment is performed by a stepwise temperature increase / decrease, preferably a three-step temperature increase / decrease.

[0044] According to an embodiment of the present invention, in the first stage of the three-stage temperature increase / decrease method, the temperature is increased to 300 to 650°C, e.g., 400°C, 480°C, 550°C, and 650°C, and the first stage is maintained at the temperature for 1 to 8 hours, e.g., 2 hours, 4 hours, 6 hours, and 8 hours.

[0045] In the second stage, the temperature is increased to 750 to 980°C, for example, 800°C, 850°C, 930°C, or 980°C, and the second stage is maintained at that temperature for 7 to 50 hours, for example, 10 hours, 20 hours, 30 hours, 40 hours, or 50 hours.

[0046] In the third stage, the temperature is lowered to 700 to 930°C, for example, 750°C, 800°C, 880°C, or 930°C, and the temperature is maintained for 3 to 20 hours, for example, 5 hours, 10 hours, 15 hours, or 20 hours.

[0047] For example, the temperature increase rate in each stage is 3 to 15°C / min, e.g., 6°C / min, 10°C / min, and the temperature decrease rate is 5 to 30°C / min, e.g., 6°C / min, 10°C / min, 20°C / min.

[0048] According to an embodiment of the present invention, the diffusion heat treatment further includes an aging treatment, preferably at a temperature of 400 to 680°C, e.g., 400°C, 500°C, 520°C, 600°C, or 680°C, and for a holding time of 2 to 10 hours, e.g., 2 hours, 4 hours, 6 hours, 8 hours, or 10 hours.

[0049] According to an embodiment of the present invention, the diffusion heat treatment is carried out in a removable diffusion device. The removable material reaction barrels can be easily replaced, allowing one barrel of material to be processed and then the next barrel to be processed, facilitating the continuous production of Nd-Fe-B sintered magnets. [Effects of the Invention]

[0050] (1) The present invention is H x M 1 y B z This method uses an alloy as a diffusion source and a detachable reaction barrel for diffusion. It efficiently produces cost-effective rare earth permanent magnets, solves the problems of adhesion and fusion between the diffusion source and the substrate during the diffusion process, improves the Hcj of NdFeB-based sintered magnets, and solves the problem of improving the efficiency of the diffusion process. Furthermore, the diffusion source of the present invention can be reused, reducing the manufacturing costs of high-performance NdFeB-based sintered magnets and being applicable to relatively large magnets, ensuring mass production of cost-effective sintered NdFeB-based products, particularly those with an orientation thickness of 8 to 30 mm.

[0051] (2) In the present invention, the diffusion source R H x M 1 y B z R in alloys H When one or a combination of Dy and Tb is diffused and the content of B element is controlled to 0.1%≦z≦0.5%, R H x M 1 y B zBy appropriately increasing the melting point of the alloy, Dy and Tb can be efficiently diffused into the magnet during the diffusion process, and the sublimation and waste of Dy and Tb due to excessively high temperatures can be avoided. 1 is one or more elements selected from the group consisting of Ti, Zr, and Al. By rationally optimizing the compounding ratio of the above components, the diffusion effect of the heavy rare earths can be ensured, while at the same time, the temperature stability of the diffusion source can be effectively improved, thereby significantly increasing the Hcj and magnetic energy product of the NdFeB based sintered magnet and enabling the production of a high-performance NdFeB based sintered material magnet.

[0052] (3) The built-in material reaction barrel of the diffusion device of the present invention is detachably installed and can be used interchangeably, which facilitates continuous material supply or removal and greatly improves production efficiency. At the same time, the diffusion source and the substrate are constantly in contact and in relative motion during the diffusion process, which prevents adhesion between the substrates and between the diffusion source and the substrate, and allows for effective diffusion, thereby improving the performance of the neodymium-iron-boron sintered material magnet.

[0053] (4) The present invention uses a three-stage temperature-up / down diffusion heat treatment method, in which the first temperature-up stage is intended to remove residual moisture and organic matter from the diffusion source, the substrate surface, and the interior. At temperatures below 300°C, a longer temperature-up time is required, consuming more energy. At temperatures above 650°C, the grain boundaries on the magnet surface become molten, causing individual regions to diffuse preferentially. This results in uneven diffusion during the re-heating process, leading to large fluctuations in performance. The second temperature-up stage is intended to ensure that the diffusion source and the substrate are sufficiently reactive. The goal of this method is to effectively concentrate the heavy rare earth elements in a narrow area near the grain boundaries in the diffusion source, thereby improving the Hcj of the magnet and reducing remanence loss. Temperatures below 750°C slow the diffusion rate of the heavy rare earth elements, which is unfavorable for improving the Hcj performance of the magnet and also results in a relatively low utilization rate of the heavy rare earth elements. Meanwhile, temperatures above 980°C continue to diffuse the heavy rare earth elements into the main phase (NdFeB) even after entering the grain boundary phase, destroying the crystal structure and reducing both the Br and Hcj of the magnet. Therefore, the present invention produces high-performance neodymium-iron-boron-based sintered magnets by controlling the temperature of the two heat treatment stages within the range of 750-980°C. The temperature of the third cooling stage is set slightly lower by 20-50°C than that of the second stage, with the aim of providing a gradual temperature decrease to ensure sufficient flow of the diffusion source and enhance the diffusion effect. DETAILED DESCRIPTION OF THE INVENTION

[0054] The technical solutions of the present invention will be described in more detail below with reference to specific examples. It should be understood that the following examples are merely for illustrative purposes and should not be construed as limiting the scope of the claims of the present invention. Any technology realized based on the above content of the present invention is included within the scope of the claims of the present invention.

[0055] Unless otherwise specified, all raw materials and reagents used in the following examples are commercially available or can be prepared by known methods. Example 1 (1) R by smelting method 1 mFe n B p M 2 w The substrate was manufactured by smelting the raw materials in an argon gas atmosphere. The alloy composition was 29.5% Nd, 0.5% Dy, 1.0% B, 0.2% Ti, 0.2% Cu, 0.1% Ga, 1% Co, and the remainder Fe. The raw materials were prepared in the appropriate proportions and placed in a smelting furnace. After the alloy was melted, it was heated to 1480°C and held at that temperature for 5 minutes. It was then cooled to 1400°C and cast into a sheet with an average thickness of 0.28 mm. (2) Milling: Hydrogen crushing + jet milling to finally obtain powder with an average particle size of 3.0 μm; (3) Pressing: Pressing the powder into a green compact under a magnetic field and isostatically pressing it to a density of approximately 4.6 g / cm 3 forming a green compact of (4) Sintering and molding: First, the material is heated at 350°C for 3 hours, then heated to 850°C and kept at that temperature for 1 hour to degas it, then sintered at 1060°C for 120 minutes, and finally aged at 520°C for 300 minutes to form a sintered neodymium-iron-boron substrate. (5) The substrate obtained in step (4) is processed to obtain products of sizes of 40-20-5 mm (i.e., 5 mm thick), respectively, and further subjected to surface chemical pretreatment by degreasing, cleaning, and pickling to eliminate oxide film on the substrate surface and prevent it from hindering the diffusion of the diffusion source; (6) Diffusion source R H x M 1 y B z Alloy - Each raw material was smelted in an argon gas atmosphere. The alloy consisted of 85% Tb, 0.4% B, and the balance Ti + Al (mass ratio 2:1). After the alloy was completely melted, it was heated to 1500 ° C and kept at that temperature for 10 minutes, then cooled to 1430 ° C and cast. A rapid-setting thick sheet with an average thickness of 1.8 mm was obtained by a spinning process. (7) Diffusion treatment: R with surface pretreatment in step (5) 1 m Fe n B p M 2w The substrate and the R obtained in step (6) H x M 1 y B z The diffusion source alloy was uniformly dispersed in a built-in reaction barrel (mass ratio of substrate to diffusion source alloy was 1:2.3), placed in a diffusion furnace, and then drawn out to below 100 Pa to begin heating. The temperature was maintained at 400°C for 4 hours in the first diffusion stage, 930°C for 20 hours in the second stage, and 880°C for 10 hours in the third stage. The heating rate in each stage was 6°C / min, the cooling rate was 10°C / min, and the aging was carried out at 520°C for 4 hours, resulting in a neodymium-iron-boron sintered magnet. Comparative Example 1 Comparative Example 1 is R H x M 1 y B z This example differs from Example 1 in that the content composition of each element in the diffusion source is 85% Tb, no B, and the remainder is Ti+Al (mass ratio 2:1). Comparative Example 2 Comparative Example 2 is R H x M 1 y B z This example differs from Example 1 in that the composition of the elements in the diffusion source is 85% Tb, 1% B, and the remainder Ti+Al (mass ratio 2:1).

[0056] The B content of the diffusion material was adjusted in Comparative Examples 1 and 2, and the effect of the B content of the diffusion material on the appearance and magnetic properties of the magnet after diffusion was considered (the appearance inspection method was to inspect 100% of the material appearance after a certain amount of material was removed from the furnace; if there was no adhesion between two or more sheets of the magnet after the material diffusion in the furnace was completed, the adhesion rate in appearance was 0%; if the two or more sheets could not be separated, it was considered to be adhesive sheets, i.e., adhesion rate = (number of adhesive sheets / total number of sheets removed from the furnace) × 100%), and the results are as shown in Table 1 below.

[0057] [Table 1]

[0058] According to the results in Table 1, adding an appropriate amount of B H x M 1 y B z The melting point of the alloy can be increased moderately, which allows H x M 1 y B z This avoids adhesion caused by surface melting of the diffusion source alloy, reduces the rate of adhesion between magnets, improves the appearance of the magnets when they are removed from the furnace, and effectively increases the Hcj of the magnets. However, it has been found that if the B content is too high, it affects the diffusion path and, conversely, affects the extent to which the Hcj of the magnets after diffusion is improved. Example 2 (1) R by smelting method 1 m Fe n B p M 2 w The substrate was manufactured by smelting the raw materials in an argon gas atmosphere. The alloy consisted of 29.5% Nd, 0.5% Dy, 1.0% B, 0.2% Ti, 0.2% Cu, 0.1% Ga, 1% Co, and the balance Fe. After the alloy was melted, it was heated to 1480°C and held at that temperature for 5 minutes. It was then cooled to 1400°C and cast into a spinning sheet with an average thickness of 0.28 mm. (2) Milling: Hydrogen crushing + jet milling to finally obtain powder with an average particle size of 3.0 μm; (3) Pressing: Pressing the powder into a green compact under a magnetic field and isostatically pressing it to a density of approximately 4.6 g / cm 3 forming a green compact of (4) Sintering and molding: First, the material is heated at 350°C for 3 hours, then heated to 850°C and kept at that temperature for 1 hour to degas it, then sintered at 1060°C for 120 minutes, and finally aged at 520°C for 300 minutes to form a sintered neodymium-iron-boron substrate. (5) The substrate obtained in step (4) is processed to obtain products of sizes of 40-20-10 mm (i.e., thickness 10 mm), respectively, and further subjected to surface chemical pretreatment by degreasing, cleaning, and pickling to eliminate oxide film on the substrate surface and prevent it from hindering the diffusion of the diffusion source; (6) Diffusion source R H x M 1 y B z Alloy - Each raw material was smelted in an argon gas atmosphere. The alloy consisted of 80% Tb, 0.3% B, and the balance Ti + Zr (mass ratio 1.5:1). After the alloy was completely melted, it was heated to 1500 °C and kept at that temperature for 10 minutes. It was then cooled to 1430 °C and cast into a rapid-setting thick sheet with an average thickness of 2.0 mm by a spinning process. (7) Diffusion treatment: R with surface pretreatment in step (5) 1 m Fe n B p M 2 w The substrate and the R obtained in step (6) H x M 1 y B z The diffusion source alloy was uniformly dispersed in the built-in reaction barrel (substrate:diffusion material mass ratio 1:2 placed in the diffusion furnace), and then drawn out to below 100 Pa to begin heating. The temperature in the first diffusion stage was maintained at 400°C for 4 hours, the temperature in the second stage was maintained at 930°C for 30 hours, and the temperature in the third stage was maintained at 880°C for 10 hours. The heating rate in each stage was 6°C / min, the cooling rate was 10°C / min, and the aging time was 500°C for 6 hours. Comparative Example 3 Comparative Example 3 is R H x M 1 y B z The only difference from Example 2 is that the content composition of each element in the diffusion source is 70% Tb, 0.3% B, and the remainder Ti+Zr (mass ratio 1.5:1). Comparative Example 4 Comparative Example 4 differs from Example 2 in that the diffusion in step (7) was a two-stage process, i.e., the temperature in the first stage of diffusion was maintained at 400°C for 4 hours, and the temperature in the second stage was maintained at 930°C for 30 hours, with the temperature increase rate in each stage being 6°C / min and the temperature decrease rate being 10°C / min, and the aging treatment was performed at 500°C for 6 hours. Example 3 This example differs from Example 2 in the following respects: (1)R 1 m Fe n B p M 2 w The substrate is processed to obtain a product having a size of 40-20-15 mm (i.e., a thickness of 15 mm), (2) The second stage of diffusion was maintained at 930°C for 40 hours.

[0059] The appearance and magnetic properties of the magnets obtained in Examples 2 and 3 and Comparative Examples 3 and 4 were tested, and the results are shown in Table 2 below.

[0060] [Table 2]

[0061] According to Table 2, in Comparative Example 3, the Tb content was reduced compared to Example 2, resulting in a decrease in the Hcj of the magnet obtained after diffusion. In Comparative Example 4, the diffusion process was adjusted from a three-stage temperature increase / decrease diffusion method to a two-stage temperature increase / decrease diffusion method, resulting in a decrease in the Hcj of the magnet obtained. According to the results of Example 3, R 1 m Fe n B p M 2 w It was also revealed that when the thickness of the substrate is increased, the Hcj performance of the magnet after diffusion can be improved by adjusting the time of the three-stage temperature increase / decrease diffusion treatment.

[0062] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. A sheet-like form of R that is used as a diffusion source during the processing of diffusion heat treatment in the production of sintered neodymium iron boron material. H x M 1 y B z An alloy, H is one or two elements selected from Dy and Tb, and M 1 represents one, two or three elements selected from Ti, Zr and Al; B represents boron; x, y and z represent mass percentages of the elements, and x, y and z satisfy the relationships 80%≦x≦85%, 0.3%≦z≦0.5%, and y=1−xz. H x M 1 y B z alloy.

2. The R H x M 1 y B z In alloys, M 1 are any two elements selected from the group consisting of Ti, Zr, and Al, and the mass ratio of the two elements is 1:1 to 2:

1. H x M 1 y B z alloy.

3. The RHxM1yBz alloy of claim 1, wherein the RHxM1yBz alloy has an average thickness of ≦10 mm.

4. R according to claim 1 H x M 1 y B z A method for producing an alloy, the method comprising the steps of: H element, M 1 The raw material containing the R element and the B element is smelted and rapidly solidified, H x M 1 y B z producing an alloy, R H element, M 1 The elements A and B have the meanings set forth in claim 1, R H element, M 1 The amount of R and B elements used is H :M 1 :A mass ratio of x:y:z, wherein x, y and z have the meanings set forth in claim 1.

5. The smelting is carried out in an inert gas atmosphere, 5. The method according to claim 4, wherein the smelting temperature is 1350 to 1550°C, and the smelting temperature retention time is 0 to 30 minutes.

6. The smelting process is performed until the raw materials are melted to form an alloy liquid and the alloy liquid is completely melted; The manufacturing method further includes cooling the smelted alloy liquid to a casting temperature after the alloy liquid is completely melted, The cooling rate is 3 to 9°C / min, 5. The method according to claim 4, wherein the casting temperature is 1330 to 1530°C.

7. The manufacturing method includes the steps of: H element, M 1 The raw materials containing element B are smelted to form an alloy liquid, which is then cooled to the casting temperature after being completely melted, and cast using a spinning method to produce R with an average thickness of ≦10 mm. H x M 1 y B z 5. The method of claim 4, further comprising obtaining a rapidly bonded gold sheet.

8. A method for producing a neodymium-iron-boron sintered magnet, the method comprising: The R according to claim 1 is used as a diffusion source. H x M 1 y B z Alloy and substrate materials R 1 m Fe n B p M 2 w and subjecting the mixture to a diffusion heat treatment to obtain the neodymium-iron-boron sintered magnet. In the R 1 m Fe n B p M 2 w substrate, R 1 is selected from Nd and Dy, Fe is an iron element, B is a boron element, and M 2 is selected from Ti, Cu, Ga, and Co; m represents the mass percentage content of R 1 , and 35%≧m≧27%; n represents the mass percentage content of Fe, and 70% ≧ n ≧ 60%; p represents the mass percentage content of B, and the content of the B element is 0.8%≦n≦1.5%; Diffusion source R H x M 1 y B z Alloy and substrate R 1 m Fe n B p M 2 w The mass ratio of the above is (1-5):

1.

9. The diffusion heat treatment is performed using a three-stage temperature increase / decrease method, and the first stage of the three-stage temperature increase / decrease method is to increase the temperature to 300 to 650°C and maintain the temperature for 1 to 8 hours; In the second stage, the temperature is raised to 750-980°C and kept at that temperature for 7-50 hours. In the third stage, the temperature is lowered to 700-930°C, and the temperature is maintained for 3-20 hours. The method according to claim 8, wherein the temperature increase rate in each stage is 3 to 15°C / min and the temperature decrease rate is 5 to 30°C / min.

10. The diffusion heat treatment further includes an aging treatment, The manufacturing method according to claim 8, wherein the temperature of the aging treatment is 400 to 680°C, and the heat-retention time of the aging treatment is 2 to 10 hours.

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