RTB magnet and method for manufacturing the same

Abstract

The present invention discloses an RTB magnet and a method for making the same. [Solution] The RTB magnet contains the following components, R: ≧30.0 wt.%, R is a rare earth element, Nb: 0.1-0.3 wt.%, B: 0.955-1.2 wt.%, Fe: 58-69 wt.%, where wt.% is the percentage of the mass of each component in the total mass of each component, and the RTB magnet further contains Co and Ti, and in the RTB magnet, the ratio of the mass content of the Co to the total mass content of "the Nb and the Ti" is 4-10. The present invention further optimizes the blending relationship between the components in the RTB magnet, making it possible to manufacture a magnet material with high levels of magnetic properties such as residual magnetic flux density, coercive force and squareness ratio.

Description

Technical Field

[0001] The present invention relates to an R-T-B magnet and a method for manufacturing the same.

Background Art

[0002] Neodymium-iron-boron permanent magnet materials, as important rare earth functional materials, have excellent comprehensive magnetic properties and are widely applied in many fields such as the electronics industry and electric vehicles. However, it is difficult to obtain products with more excellent characteristics from the current neodymium-iron-boron magnet materials, and they cannot meet the social needs. by For example, Chinese Patent Document CN106158204A discloses a neodymium-iron-boron magnet material composed of components with a weight percentage of 15-30% PrNd, 3-6% Gd, 0.05-0.15% Ga, 0.5-1.2% B, 0.6-1.2% Co, 0.3-0.8% Al, 0.05-0.3% Cu, 0.05-0.3% Mo, 0.05-0.3% Ti, and the balance being Fe. In this patent document, by adding the above components, a fine grain structure is obtained. The low-melting-point metal first dissolves at the grain boundaries, improving the solubility of the high-melting-point metal in the liquid phase and uniformly distributing the high-melting-point metal in the intergranular region. However, the remanent magnetic flux density and coercive force of the neodymium-iron-boron magnet with these components are still at a low level.

[0003]

[0004] Currently, it is a technical problem to be solved to find the components of a neodymium-iron-boron magnet that can maintain high levels of magnetic properties such as remanent magnetic flux density, coercive force, and squareness ratio to meet the applications in current high-demand fields.

Summary of the Invention

Problems to be Solved by the Invention

[0005] This invention provides an RTB magnet and a method for manufacturing the same in order to solve the shortcomings of the prior art, in which the synergistic effect of the components of the RTB magnet is poor, and the resulting magnetic material cannot simultaneously achieve high levels of residual magnetic flux density, coercivity, and angular ratio. By using a specific blend of each component in the RTB magnet according to this invention, it is possible to manufacture a magnetic material in which magnetic properties such as residual magnetic flux density, coercivity, and angular ratio all reach high levels. [Means for solving the problem]

[0006] The present invention primarily solves the above technical problems through the following technical inventions.

[0007] The RTB magnet provided by the present invention comprises the following components: R: ≥ 30.0 wt.%, where R is a rare earth element. Nb: 0.1~0.3 wt.% B: 0.955~1.2 wt.%, Fe: 58-69 wt.%, where wt.% is the percentage of the total mass of each component. The above RTB magnet further contains Co and Ti, and in the RTB magnet, the ratio of the mass content of Co to the total mass content of "the above Nb and the above Ti" is 4-10.

[0008] In the present invention, it can be seen that, according to the above-mentioned RTB magnet, the total mass of each of the above-mentioned components includes the mass content of Co and Ti.

[0009] In the present invention, the content of R is preferably 30 to 32 wt.%, for example, 30.5 wt.%, 30.6 wt.%, or 30.7 wt.%.

[0010] In the present invention, R can generally further include Nd.

[0011] Here, the Nd content may be the usual in the art, and the Nd is preferably 22 to 32 wt.%, for example 28.2 wt.%, 28.4 wt.%, 29.2 wt.%, 29.3 wt.%, 29.4 wt.%, 29.5 wt.%, 29.8 wt.%, 29.9 wt.%, or 30.3 wt.%, where wt.% is the percentage of the total mass of each component.

[0012] In the present invention, the type of R generally further includes Pr and / or RH, where RH is a heavy rare earth element.

[0013] Here, the Pr content is preferably 0.3 wt.% or less, for example, 0.2 wt.%, where wt.% is the percentage of the total mass of each component.

[0014] Here, the RH content is preferably 3 wt.% or less, for example 0.2 wt.%, 0.6 wt.%, 0.8 wt.%, 1.1 wt.%, 1.2 wt.%, 1.4 wt.%, 2.3 wt.%, or 2.5 wt.%, where wt.% is the percentage of the total mass of each component.

[0015] Here, the type of RH mentioned above preferably includes Tb or Dy.

[0016] If the above RH contains Tb, the Tb content is preferably 0.2 to 1.1 wt.%, for example 0.2 wt.%, 0.5 wt.%, 0.6 wt.%, 0.8 wt.%, or 1.1 wt.%, where wt.% is the percentage of the total mass of each component.

[0017] If the above RH contains Dy, the Dy content is preferably 0.5 to 2.5 wt.%, for example 0.6 wt.%, 1.2 wt.%, 1.8 wt.%, or 2.5 wt.%, where wt.% is the percentage of the total mass of each component.

[0018] Here, the ratio of the atomic percentage content of the RH to the atomic percentage content of the R may be 0.1 or less, for example, 0.02, 0.04, 0.06, or 0.08, and the above atomic percentage content means the atomic percentage in the total content of each component.

[0019] In the present invention, the content of the Nb is preferably 0.15 to 0.25 wt.%, for example, 0.16 wt.%, 0.18 wt.%, 0.2 wt.%, 0.22 wt.%, 0.23 wt.%, or 0.24 wt.%.

[0020] In the present invention, in the R-T-B magnet, the ratio of the mass content of the Co to the total mass content of "the Nb and the Ti" is preferably 4.6 to 8.4, for example, 4.6, 5.3, 5.5, 6.5, 6.6, 6.7, 6.8, 7.9, or 8.4, and more preferably 4 to 7.

[0021] In the present invention, the content of the Co is preferably 1.5 to 3.5 wt.%, for example, 2 wt.%, 2.5 wt.%, 2.6 wt.%, 2.8 wt.%, or 3 wt.%.

[0022] In the present invention, the content of the Ti is preferably 0.15 to 0.35 wt.%, for example, 0.15 wt.%, 0.18 wt.%, 0.23 wt.%, 0.25 wt.%, or 0.35 wt.%.

[0023] In the present invention, the content of the B is preferably 0.955 to 1.1 wt.%, for example, 0.99 wt.%.

[0024] In the present invention, the ratio of the atomic percentage content of the B to the atomic percentage content of the R in the R-T-B magnet may be 0.38 or more, for example, 0.41, 0.42, 0.43, or 0.44, and the above atomic percentage content means the atomic percentage in the total content of each component.

[0025] In the present invention, the content of Fe is preferably 65 to 66 wt.%, for example, 64.67 wt.%, 64.71 wt.%, 64.88 wt.%, 64.89 wt.%, 64.98 wt.%, 65.07 wt.%, 65.13 wt.%, 65.14 wt.%, 65.33 wt.%, 65.38 wt.% or 65.64 wt.%.

[0026] In the present invention, the above R-T-B magnet may further contain Cu.

[0027] Here, the content of Cu may be 0.1 to 0.4 wt.%, for example, 0.1 wt.%, 0.15 wt.%, 0.25 wt.%, 0.3 wt.%, 0.36 wt.% or 0.39 wt.%, and wt.% is the percentage occupied by the total mass of each component.

[0028] In the present invention, generally, it is known to those skilled in the art that during the manufacturing process, one or more inevitable impurities such as C, O, and Mn are further introduced into the R-T-B magnet.

[0029] The inventors have discovered that in the magnet component formulation with a specific blending relationship between the above elements and their contents, after being manufactured as an R-T-B magnet, the magnetic properties such as coercive force, residual magnetic flux density, and rectangularity ratio of the obtained magnet material are all at a high level. Further analysis reveals that in the R-T-B magnet with such components, a Co-Ti-Nb phase is formed in the triangular region between crystal grains compared to a magnet material without such components. The presence of the Co-Ti-Nb phase significantly inhibits crystal grain growth.

[0030] In the present invention, the RTB magnet preferably further comprises Co-Ti-Nb, wherein the Co-Ti-Nb phase is located in the intergrain triangular region, and the ratio of the area of ​​the Co-Ti-Nb phase in the intergrain triangular region to the total area of ​​the intergrain triangular region is 1.1 to 2.5%. Here, the above-mentioned intergrain triangular region may have the meaning commonly understood in the art, and generally refers to the grain boundary phase formed between three or more main phase particles. The area of ​​the Co-Ti-Nb phase and the total area of ​​the intergrain triangular region generally refer to the area they occupy, respectively, in the cross-section of the RTB magnet detected during FE-EPMA detection.

[0031] In the above Co-Ti-Nb phase, the ratio of the atomic percentage contents of Co, Ti, and Nb is close to 8:1:1. The above Co-Ti-Nb phase is preferably the Co8Ti1Nb1 phase.

[0032] Here, the ratio of the area of ​​the Co-Ti-Nb phase in the intergrain triangular region to the total area of ​​the intergrain triangular region is, for example, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%.

[0033] In one preferred embodiment of the present invention, the RTB magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.07 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 2%.

[0034] In one preferred embodiment of the present invention, the RTB magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.23 wt.% Ti, 0.24 wt.% Nb, 0.99 wt.% B, and 64.98 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.8%.

[0035] In one preferred embodiment of the present invention, the RTB magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.35 wt.% Ti, 0.22 wt.% Nb, 0.99 wt.% B, and 64.88 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.7%.

[0036] In one preferred embodiment of the present invention, the RTB magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.15 wt.% Ti, 0.16 wt.% Nb, 0.99 wt.% B, and 65.14 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.5%.

[0037] In one preferred embodiment of the present invention, the RTB magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 3 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 64.67 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 2%.

[0038] In one preferred embodiment of the present invention, the RTB magnet contains 29.8 wt.% Nd, 0.8 wt.% Tb, 0.3 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.13 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.9%.

[0039] In one preferred embodiment of the present invention, the RTB magnet contains 29.9 wt.% Nd, 0.6 wt.% Tb, 0.25 wt.% Cu, 2.5 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.38 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 2%.

[0040] In one preferred embodiment of the present invention, the RTB magnet contains 30.3 wt.% Nd, 0.2 wt.% Tb, 0.39 wt.% Cu, 2.8 wt.% Co, 0.23 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 64.89 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.8%.

[0041] In one preferred embodiment of the present invention, the RTB magnet contains 28.2 wt.% Nd, 2.5 wt.% Dy, 0.15 wt.% Cu, 3 wt.% Co, 0.25 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 64.71 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.8%.

[0042] In one preferred embodiment of the present invention, the RTB magnet contains 28.4 wt.% Nd, 0.5 wt.% Tb, 1.8 wt.% Dy, 0.1 wt.% Cu, 2.5 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.33 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.8%.

[0043] In one preferred embodiment of the present invention, the RTB magnet contains 29.4 wt.% Nd, 1.2 wt.% Dy, 0.39 wt.% Cu, 2 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.64 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.7%.

[0044] In one preferred embodiment of the present invention, the RTB magnet contains 29.2 wt.% Nd, 0.8 wt.% Tb, 0.6 wt.% Dy, 0.36 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.07 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.6%.

[0045] In one preferred embodiment of the present invention, the RTB magnet contains 29.3 wt.% Nd, 0.2 wt.% Pr, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.07 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.7%.

[0046] In one preferred embodiment of the present invention, the RTB magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.07 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.2%.

[0047] In one preferred embodiment of the present invention, the RTB magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.07 wt.% Fe, where wt.% is the percentage of the total mass of each component, and the intergranular triangular region of the RTB magnet contains a Co8Ti1Nb1 phase, with the ratio of the area of ​​the Co8Ti1Nb1 phase to the total area of ​​the intergranular triangular region being 1.1%.

[0048] The present invention provides a method for manufacturing an RTB magnet, which includes sequentially performing an air blast cooling treatment and an aging treatment after sintering a raw material mixture of each component of the RTB magnet described above.

[0049] In the present invention, the sintering process can be a conventional one in the art.

[0050] Here, the temperature of the sintering process is preferably 1000 to 1100°C, for example, 1080°C.

[0051] Here, the sintering is preferably carried out under vacuum conditions, for example, 5 × 10 -3 The procedure is performed under vacuum conditions of Pa.

[0052] Here, the duration of the sintering process can be the usual duration in this field, and may be 4 to 8 hours, for example, 6 hours.

[0053] In the present invention, the temperature of the air blast cooling treatment is preferably 550 to 950°C, for example, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, or 950°C.

[0054] In the present invention, as will be apparent to those skilled in the art, the temperature of the air blast cooling treatment generally refers to the temperature at which, after the sintering treatment has been naturally cooled to the temperature of the air blast cooling treatment, an air blower is turned on to rapidly cool it to room temperature. The duration of the air blast cooling treatment in the present invention is not particularly limited and may be appropriately adjusted according to different air blast cooling treatment temperatures.

[0055] In the present invention, the above-mentioned aging process can employ a conventional aging process in the art, and generally includes a first-stage aging process and a second-stage aging process.

[0056] Here, the temperature of the first-stage aging treatment may be 860 to 920°C, for example, 880°C or 900°C.

[0057] Here, the time for the first stage of the statute of limitations process may be 2.5 to 4 hours, for example, 3 hours.

[0058] Here, the temperature of the second aging treatment may be 460 to 530°C, for example, 500°C, 510°C, or 520°C.

[0059] Here, the time for the second stage of the statute of limitations process may be 2.5 to 4 hours, for example, 3 hours.

[0060] In the present invention, if the RTB magnet contains heavy rare earth elements, conventional grain boundary diffusion can also be performed after the aging treatment.

[0061] Here, the grain boundary diffusion may be a standard process in this field, and is generally performed for heavy rare earth elements.

[0062] The temperature of the grain boundary diffusion may be 800 to 900°C, for example, 850°C. The duration of the grain boundary diffusion may be 5 to 10 hours, for example, 8 hours.

[0063] Here, the method of adding heavy rare earth elements to the RTB magnet can be based on the usual practices in this field. Generally, a method is adopted in which 0-80% of the heavy rare earth elements are added during the melting and smelting process, and the remainder is added during the melting and smelting process, for example, 25%, 30%, 40%, 50%, or 67%. The heavy rare earth element added during the melting and smelting process is, for example, Tb.

[0064] For example, if the heavy rare earth element in the RTB magnet is Tb and Tb is greater than 0.5 wt.%, 25-67% of Tb is added during melting and smelting, and the remainder is added during grain boundary diffusion. For example, if the heavy rare earth elements in the RTB magnet are Tb and Dy, the above Tb is added during melting and smelting, and the above Dy is added during grain boundary diffusion. For example, if the heavy rare earth element in the RTB magnet is Tb and Tb is 0.5 wt.% or less, or if the heavy rare earth element in the RTB magnet is Dy, the heavy rare earth element in the RTB magnet is added during grain boundary diffusion.

[0065] The temperature of the grain boundary diffusion may be 800 to 900°C, for example, 850°C. The duration of the grain boundary diffusion may be 5 to 10 hours, for example, 8 hours.

[0066] In the present invention, prior to the sintering process, the raw material mixture of each component of the RTB magnet is generally subjected to melting and smelting, casting, hydrogen fracturing, fine grinding, and magnetic field molding in sequence.

[0067] Here, the aforementioned melting and smelting process can employ a conventional melting and smelting process in this field.

[0068] The vacuum level for the aforementioned melting and smelting process is, for example, 5 × 10⁻⁶ -2 It is Pa.

[0069] The melting and smelting temperature is, for example, 1550°C or lower.

[0070] The above-mentioned melting and smelting process is generally carried out in a high-frequency vacuum induction melting furnace.

[0071] Here, the casting process can be one that is common in this field.

[0072] The aforementioned casting process can employ, for example, a strip casting method.

[0073] The casting temperature may be 1390 to 1460°C, preferably 1410 to 1440°C, for example 1430°C.

[0074] The thickness of the alloy slab obtained after casting may be 0.25 to 0.40 mm, for example, 0.29 mm.

[0075] Here, the hydrogen fracturing process may generally involve hydrogen absorption, dehydrogenation, and cooling in that order.

[0076] The hydrogen absorption may be carried out under conditions of a hydrogen pressure of 0.085 MPa.

[0077] The dehydrogenation may be carried out under conditions of heating while under vacuum. The dehydrogenation temperature may be 480-520°C, for example, 500°C.

[0078] Here, the fine grinding step may employ a conventional process in this field, such as jet mill grinding.

[0079] The gas atmosphere during the fine grinding process may have an oxidizing gas content of 1000 ppm or less, and the oxidizing gas content refers to the content of oxygen or moisture.

[0080] The pressure during the fine grinding process is, for example, 0.68 MPa.

[0081] After the aforementioned fine grinding, a lubricant, such as zinc stearate, is generally added.

[0082] The amount of lubricant added may be 0.05 to 0.15% of the powder mass obtained after fine grinding, for example, 0.12%.

[0083] Here, the magnetic field shaping process may employ a conventional process in this field.

[0084] The aforementioned magnetic field shaping may be performed with a magnetic field strength of 1.8 T or higher and under nitrogen atmosphere protection. For example, it may be performed with a magnetic field strength of 1.8 to 2.5 T.

[0085] The present invention further provides an RTB magnet manufactured by the above-described manufacturing method.

[0086] By arbitrarily combining the above preferred conditions while adhering to the well-known common sense of this field, various preferred embodiments of the present invention can be obtained.

[0087] The reagents and raw materials used in this invention are all commercially available. [Effects of the Invention]

[0088] The positive progressive effects of the present invention are as follows: By providing elements such as Co, Ti, and Nb, as well as B, in specific compound relationships, the present invention further optimizes the composition of RTB magnets, resulting in a significant improvement in the coercivity of the resulting RTB magnets, while simultaneously achieving high levels of magnetic properties such as residual magnetic flux density, high stability performance, and square-to-size ratio. [Brief explanation of the drawing]

[0089] [Figure 1] This is an SEM image of the RTB magnet in Example 1. Arrow A in Figure 1 indicates the Co-Ti-Nb phase obtained by single-point quantitative analysis in the intergranular triangular region. [Modes for carrying out the invention]

[0090] The present invention will be further described below with reference to examples, but the present invention is not limited to the scope of the above examples. In the following examples, experimental methods for which specific conditions are not specified will be selected according to conventional methods and conditions, or according to product specifications. Example 1

[0091] Raw materials were prepared according to the components of the RTB magnet of Example 1 shown in Table 1 below. The raw material mixture (0.4 wt.% of Tb added during melting and smelting in the components of Table 1) was subjected to melting and smelting, casting, hydrogen fracturing, fine grinding, magnetic field shaping, sintering, air blast cooling, aging, and grain boundary diffusion in sequence to obtain the magnet.

[0092] The manufacturing process for the RTB magnet is as follows:

[0093] (1) Melting and smelting: 5 x 10 -2 The material is melted and smelted in a high-frequency vacuum induction melting furnace with a vacuum level of Pa, and the melting and smelting temperature is 1550°C or lower.

[0094] (2) Casting: A strip casting method was adopted to obtain an alloy slab with a thickness of 0.29 mm, and the casting temperature was 1430°C.

[0095] (3) Hydrogen fracturing: Hydrogen absorption, dehydrogenation, and cooling treatments were performed. Hydrogen absorption was carried out under a hydrogen pressure of 0.085 MPa. Dehydrogenation was carried out under conditions of heating while under vacuum, and the dehydrogenation temperature was 500°C.

[0096] (4) Fine grinding process: Jet mill grinding is performed in an atmosphere with an oxidizing gas content of 100 ppm or less, where oxidizing gas refers to oxygen or moisture content. The pressure in the grinding chamber of the jet mill grinding is 0.68 MPa. After grinding, zinc stearate, a lubricant, is added, and the amount added is 0.12% of the weight of the powder after mixing.

[0097] (6) Magnetic field shaping: This was performed under a magnetic field strength of 1.8 to 2.5 T and under nitrogen atmosphere protection.

[0098] (7) Sintering process: 5 × 10 -3 Under vacuum conditions of Pa, sintering was performed at 1080°C for 6 hours, and before cooling, Ar gas was introduced to bring the atmospheric pressure to 0.05 MPa.

[0099] (8) Air blast cooling treatment: After the sintering process was completed, the sintering was allowed to cool naturally to 650°C, and then the air blower was turned on to rapidly cool the sintering to room temperature.

[0100] (9) Aging treatment: The temperature for the first aging stage is 900°C and the duration is 3 hours, and the temperature for the second aging stage is 510°C and the duration is 3 hours.

[0101] (10) Grain boundary diffusion: The remaining heavy rare earth elements (0.7 wt.% Tb) were melted and then attached to the material surface, and grain boundary diffusion was performed at 850°C for 8 hours.

[0102] 2. The raw materials and air blast cooling temperatures for the RTB magnets in Examples 2-15 and Comparative Examples 1-4 are as shown in Table 1 below, and the other manufacturing processes are the same as in Example 1. Here, in Examples 2-7, 13-15 and Comparative Examples 1-4, 0.4 wt% of Tb is added during the melting and smelting process, and the remaining Tb enters the RTB magnet by grain boundary diffusion. In Examples 8, 9 and 11, the heavy rare earth elements are added during grain boundary diffusion and enter the RTB magnet. In Examples 10 and 12, Tb is added during the melting and smelting process, and Dy enters the RTB magnet by grain boundary diffusion. Effect Example 1

[0103] 1. Component Measurement: The RTB magnets in Examples 1-15 and Comparative Examples 1-4 were measured using an inductively coupled plasma atomic emission spectrometer (ICP-OES). The test results are shown in Table 1 below.

[0104] [Table 1] Note: / indicates that the element in question has not been added. Ga and Zr were not detected in the RTB magnets of each of the above examples and comparative examples. The final RTB magnet product inevitably contains C, O, and Mn during manufacturing, and the percentage content stated in each example and comparative example does not include these impurities. 2. Magnetic properties test

[0105] The RBT magnets in Examples 1-15 and Comparative Examples 1-4 were tested using a PFM pulse-type BH demagnetization curve test apparatus under room temperature conditions of 20°C to obtain data on residual magnetic flux density (Br), intrinsic coercivity (Hcj), maximum energy product (BHmax), and squareness ratio (Hk / Hcj). The test results are shown in Table 2 below.

[0106] [Table 2]

[0107] Detection by FE-EPMA: The vertical orientation surfaces of the RTB magnets in Examples 1-15 and Comparative Examples 1-4 were polished, and detection was performed using a field emission electron probe microanalyzer (FE-EPMA, JEOL Ltd., 8530F). First, the distribution of Co, Ti, and Nb elements within the RTB magnet was determined by FE-EPMA surface scanning, and then the content of each element in the Co-Ti-Nb phase was determined by FE-EPMA single-point quantitative analysis. The test conditions were an acceleration voltage of 15 kV and a probe beam current of 50 nA. The detection revealed that the ratio of atomic percentage content of Co, Ti, and Nb elements in the Co-Ti-Nb phase in Examples 1-15 was close to 8:1:8. The test results are shown in Table 3 below.

[0108] As shown in Figure 1, Figure 1 is a microstructure diagram of the SEM image of the RTB magnet in Example 1 as detected by FE-EPMA. The position indicated by arrow A in Figure 1 is the Co-Ti-Nb phase of single-point quantitative analysis in the intergranular triangular region. From detection and calculation, it is obtained that the Co8Ti1Nb1 phase is formed in the intergranular triangular region of the RTB magnet of the present invention, and that the ratio of the area of ​​the said phase in the intergranular triangular region to the total area of ​​the intergranular triangular region (hereinafter referred to as the ratio occupied by the area of ​​the Co8Ti1Nb1 phase) is 2%. Here, the area of ​​the Co8Ti1Nb1 phase and the area of ​​the intergranular triangular region refer to the area occupied in the detected cross-section (the vertical orientation plane mentioned above), respectively. The test results for Examples 2 to 15 and Comparative Examples 1 to 4 are shown in Table 3 below.

[0109] [Table 3]

[0110] As can be seen from the experimental data above, the formulation method for the RTB magnet designed by the inventors, after being manufactured as a magnetic material, yields a magnetic material with excellent overall magnetic properties, exhibiting high levels of residual magnetic flux density, coercivity, high-temperature stability, magnetic energy product, and angularity, thus satisfying the requirements for application in demanding fields. Further microstructural analysis revealed that after the RTB magnet of the above specific formulation method is manufactured as a magnetic material, a Co8Ti1Nb1 phase with a specific area ratio is formed in the intergrain triangular region of the magnet. The presence of this phase significantly inhibits grain growth and further improves the coercivity and other magnetic properties of the RTB magnet. RTB magnet If the compounding method falls outside the scope of the present invention, it becomes impossible to obtain the Co8Ti1Nb1 phase or a low-content version of the said phase, making it difficult to significantly improve the magnetic properties of the RTB magnet.

Claims

1. It is an R-T-B magnet, The following components are included, with each component accounting for a percentage of the total mass in wt. %: R: ≥ 30.0 wt. %, where R is a rare earth element. Nb: 0.1-0.3wt. %, B: 0.955-1.2wt. %, The main component of the remainder is Fe. The aforementioned R further contains RH, which is a heavy rare earth element containing Tb, and the RH content is 3 wt.% or less, but not 0. The R-T-B magnet further contains Co and Ti, the Ti content being 0.15 to 0.35 wt.%, and in the R-T-B magnet, the ratio of the mass content of Co to the total mass content of "the Nb and the Ti" is 6.5 to 7.

9. The R-T-B magnet further comprises a Co-Ti-Nb phase, the Co-Ti-Nb phase located in the intergranular triangular region, the ratio of the area of ​​the Co-Ti-Nb phase in the intergranular triangular region to the total area of ​​the intergranular triangular region being 1.1 to 2.5%, and the Co-Ti-Nb phase is Co ８ Ti １ Nb １ It is a sign, An R-T-B magnet characterized by the following features.

2. The content of R is 30 to 32 wt.%. The aforementioned R further includes Nd, The Nd content is 22 to 32 wt.%. The aforementioned R may contain Pr, and the Pr content is 0.3 wt.% or less. The Tb content in the RH is 0.2 to 1.1 wt.%. The RH may contain Dy, and if the RH contains Dy, the Dy content is 0.5 to 2.5 wt.%. The ratio of the atomic percentage content of RH to the atomic percentage content of R is 0.1 or less. The R-T-B magnet according to feature 1.

3. The Nb content is 0.15 to 0.25 wt.%. The Co content is 1.5 to 3.5 wt.%. The R-T-B magnet according to feature 1.

4. The content of B is 0.955 to 1.1 wt.%, The ratio of the atomic percentage content of B to the atomic percentage content of R in the R-T-B magnet is 0.38 or higher. The R-T-B magnet further contains Cu, The Cu content is 0.1 to 0.4 wt.%. The R-T-B magnet according to feature 1.

5. The ratio of the area of ​​the Co-Ti-Nb phase in the intergrain triangular region to the total area of ​​the intergrain triangular region is 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%. The R-T-B magnet according to any one of claims 1 to 4.

6. The R-T-B magnet contains components of 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B and 65.07 wt.% Fe. In the triangular regions between the crystal grains of the R-T-B magnet, Co ８ Ti １ Nb １ phases are included. The ratio of the area of the Co ８ Ti １ Nb １ phase to the total area of the triangular regions between the crystal grains is 2%. Alternatively, the R-T-B magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.23 wt.% Ti, 0.24 wt.% Nb, 0.99 wt.% B, and 64.98 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 1.8%. Alternatively, the R-T-B magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.35 wt.% Ti, 0.22 wt.% Nb, 0.99 wt.% B, and 64.88 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 1.7%. Alternatively, the R-T-B magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.15 wt.% Ti, 0.16 wt.% Nb, 0.99 wt.% B, and 65.14 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 1.5%. Alternatively, the R-T-B magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 3 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 64.67 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 2%. Alternatively, the R-T-B magnet contains components of 29.8 wt.% Nd, 0.8 wt.% Tb, 0.3 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.13 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 1.9%. Alternatively, the R-T-B magnet contains components of 29.9 wt.% Nd, 0.6 wt.% Tb, 0.25 wt.% Cu, 2.5 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.38 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 2%. Alternatively, the R-T-B magnet contains components of 30.3 wt.% Nd, 0.2 wt.% Tb, 0.39 wt.% Cu, 2.8 wt.% Co, 0.23 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 64.89 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 1.8%. Alternatively, the R-T-B magnet contains components of 28.4 wt.% Nd, 0.5 wt.% Tb, 1.8 wt.% Dy, 0.1 wt.% Cu, 2.5 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.33 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 1.8%. Alternatively, the R-T-B magnet contains components of 29.2 wt.% Nd, 0.8 wt.% Tb, 0.6 wt.% Dy, 0.36 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.07 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 1.6%. Alternatively, the R-T-B magnet contains components of 29.3 wt.% Nd, 0.2 wt.% Pr, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.07 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 1.7%. Alternatively, the R-T-B magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.07 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 1.2%. Alternatively, the R-T-B magnet contains 29.5 wt.% Nd, 1.1 wt.% Tb, 0.36 wt.% Cu, 2.6 wt.% Co, 0.18 wt.% Ti, 0.2 wt.% Nb, 0.99 wt.% B, and 65.07 wt.% Fe, and the intergrain triangular region of the R-T-B magnet contains Co ８ Ti １ Nb １ The phase is included, and the Co ８ Ti １ Nb １ The ratio of the phase area to the total area of ​​the intergrain triangular region is 1.1%. The R-T-B magnet according to feature 1.

7. A method for manufacturing an R-T-B magnet, After performing a sintering treatment on the raw material mixture of each component of the R-T-B magnet according to any one of claims 1 to 4 and 6, an air blast cooling treatment and an aging treatment are performed sequentially. A method for manufacturing an R-T-B magnet, characterized by the following:

8. The temperature of the sintering process is 1000 to 1100°C. The duration of the sintering process is 4 to 8 hours. The temperature of the air blast cooling treatment is 550 to 950°C. The aforementioned prescription process includes a first-stage prescription process and a second-stage prescription process. The temperature for the first stage aging treatment is 860 to 920°C. The duration of the first stage of aging processing is 2.5 to 4 hours. The temperature for the second stage aging treatment is 460 to 530°C. The duration of the second stage of statute of limitations processing is 2.5 to 4 hours. If the R-T-B magnet contains heavy rare earth elements, the aging treatment is further followed by grain boundary diffusion, The temperature of grain boundary diffusion is 800 to 900°C. The duration of grain boundary diffusion is 5 to 10 hours. The method of adding heavy rare earth elements to the R-T-B magnet is as follows: 0-80% of the heavy rare earth elements are added during melting and smelting, and the remaining heavy rare earth elements are added during grain boundary diffusion. If the heavy rare earth element in the R-T-B magnet is Tb and Tb is greater than 0.5 wt.%, 25-67% of Tb is added during melting and smelting, and the remainder is added during grain boundary diffusion. If the heavy rare earth elements in the R-T-B magnet are Tb and Dy, Tb is added during melting and smelting, and Dy is added during grain boundary diffusion. If the heavy rare earth element in the R-T-B magnet is Tb and Tb is 0.5 wt.% or less, the heavy rare earth elements in the R-T-B magnet are added during grain boundary diffusion. The method for manufacturing an R-T-B magnet according to feature 7.

9. Prior to the sintering process, the process further includes melting and smelting, casting, hydrogen fracturing, fine grinding and molding, The melting and smelting temperature is 1550°C or lower. The casting temperature is 1410 to 1440°C. The thickness of the alloy slab obtained after the casting is 0.25 to 0.40 mm. The hydrogen fracturing process is carried out in the following order: hydrogen absorption, dehydrogenation, and cooling treatment. The magnetic field strength during the molding process is 1.8 T or higher. The method for manufacturing an R-T-B magnet according to feature 7.

10. A magnet manufactured by the method for manufacturing an R-T-B magnet described in claim 7, An R-T-B magnet characterized by the following features.

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