Sintered re-fe-b permanent magnet and method for producing and use thereof

Abstract

The present invention provides a sintered Re-Fe-B permanent magnet, and a preparation method and use thereof.SOLUTION: The sintered Re-Fe-B permanent magnet of the present invention comprises a Ti-based precipitate phase, wherein the Ti-based precipitate phase comprises Re-Fe-Ti-B rod-like objects, and the length of the Re-Fe-Ti-B rod-like objects is 100-300 nm; In the Ti-based precipitated phase, the atomic content of Re is 1 to 20at%, the atomic content of Fe is 1 to 30at%, the atomic content of Ti is 40 to 90at%, the atomic content of B is 10 to 20at%, and the atomic content ratio of Ti to B is 4:1 to 9:1. In the sintered neodymium-iron-boron permanent magnet of the present invention, through the combination of the formula design and the process optimization, a large-size Re-Fe-Ti-B bar is formed to prevent the formation of a boron-rich phase, and the Re-Fe-Ti-B bar is agglomerated only at the grain boundary, which can prevent the grain size from increasing, inhibit the growth of the main phase grains, weaken the magnetic coupling effect between the main phase grains, and improve the performance of the sintered Re-Fe-B permanent magnet.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention belongs to the technical field of manufacturing rare earth permanent magnet materials, and in particular to a sintered Re-Fe-B permanent magnet, as well as its manufacturing method and use. [Background technology]

[0002] Due to their excellent magnetic properties, rare earth magnets, especially neodymium iron boron (NdFeB) magnets, are widely used in a variety of equipment and devices, such as motors, generators, and computer hard disk drives. Currently, the market applications of high-performance neodymium iron boron magnets are gradually expanding. To improve the coercivity of magnets, heavy rare earth elements such as dysprosium (Dy) and terbium (Tb) must usually be added, but the scarcity and high cost of these elements limit their widespread application.

[0003] In the structure of NdFeB, the boron-rich phase is a non-ferromagnetic phase, which is detrimental to magnetic performance rather than beneficial. In current manufacturing technology, adding some metal elements, such as Ti and Zr, results in the formation of additional precipitates with B due to their very low solubility in the grain boundary phase, reducing the proportion of B-rich phase in the non-magnetic phase and improving coercivity. Patent document CN116978653A attempts to control the morphology and distribution of metal precipitates by varying the cooling rate, thereby improving the magnet's coercivity. However, controlling the cooling rate requires high equipment requirements and is difficult to implement, and the size of the Ti-B precipitate rods is relatively small. Therefore, how to effectively improve the coercivity of rare earth magnets using conventional production processes remains an urgent issue. Summary of the Invention [Problem to be solved by the invention]

[0004] In order to solve the above shortcomings of the prior art, the present invention provides the following technical solutions:

[0005] A sintered Re-Fe-B permanent magnet has a Ti-based precipitate phase, the Ti-based precipitate phase being a Re-Fe-Ti-B rod-shaped object, the length of the Re-Fe-Ti-B rod being 100-300 nm, the Ti-based precipitate phase having an atomic content of Re of 1-20 at%, an atomic content of Fe of 1-30 at%, an atomic content of Ti of 40-90 at%, and an atomic content of B of 10-20 at%, with a ratio of Ti to B of 4:1-9:1. In the present invention, the Ti-based precipitate phase may be expressed as a Re-Fe-Ti-B phase. In the present invention, the Re-Fe-Ti-B rod-shaped object is an object whose length is greater than the maximum width (e.g., diameter) of its cross section, and the shape of the cross section is not particularly limited, and includes, but is not limited to, a circle, an ellipse, a rectangle, and a polygon. Preferably, the length of the rod-shaped object is at least two times, for example, at least four or five times, the maximum width of the cross section. Illustrative examples of the rod-shaped object include a rectangular parallelepiped and a cylindrical body.

[0006] According to an embodiment of the present invention, the grain boundary phase refers to a grain boundary between any two crystal grains and / or a grain boundary between any three or more crystal grains. In the present invention, a grain boundary between any two crystal grains is defined as an intergranular grain boundary. A grain boundary between any three or more crystal grains is defined as a triangular grain boundary as shown in FIG. 5.

[0007] According to an embodiment of the present invention, the Ti-based precipitate phase is distributed only in the grain boundary phase.

[0008] According to an embodiment of the present invention, the length of the Re—Fe—Ti—B rods is, for example, 150 nm, 200 nm, or 250 nm.

[0009] According to an embodiment of the present invention, the ratio of the atomic content of Ti to B in the Ti-based precipitate phase is 4:1 to 9:1, for example, 5:1, 6:1, 7:1, or 8:1.

[0010] According to an embodiment of the present invention, the composition of the Re-Fe-B permanent magnet is Re a Fe 1-a-b-c-d M1 b Ti c Bd and here, Re is at least one or more selected from Sm, La, Ce, Y, Nd, Pr, Ho, Gd, Dy, Tb, 28 wt% ≤ a ≤ 35 wt%, M1 is at least one or more selected from Co, Ga, Cu, Al, Nb, Zr, 0.5 wt% ≤ b ≤ 5 wt%, the content of Ti is 0.05 wt% < c ≤ 0.5 wt%, preferably, the content of Ti is 0.1 wt% < c < 0.2 wt%, the content of B is 0.8 wt% ≤ d ≤ 1.2 wt%, preferably, the content of B is 0.92 wt% < d < 1.05 wt%, the balance is Fe and inevitable impurity elements.

[0011] According to an embodiment of the present invention, among the components of the Re-Fe-B permanent magnet, a, b, c, and d correspond to mass percentages.

[0012] According to an embodiment of the present invention, among the components of the Re-Fe-B permanent magnet, when the atomic contents of Re, Ti, and B are [Re], [Ti], and [B], respectively, they have the relational expression: [Re] - 2[B] + 4[Ti] ≥ 1.91 at%, preferably 2 at%, 2.5 at%, 3 at%, 3.5 at%, 4 at%, 5 at%, 6 at%, 7 at%, 8 at%, 9 at%, 10 at%.

[0013] The present invention also provides a method for manufacturing the sintered Re-Fe-B permanent magnet, and the manufacturing method includes: step (1) of manufacturing a neodymium iron boron strip cast ribbon and performing a grain boundary diffusion treatment on the neodymium iron boron strip cast ribbon; step (2) of pulverizing the neodymium iron boron strip cast ribbon to obtain magnetic powder with an average particle size of 2 to 5 μm, and then pressing the magnetic powder into a green compact; step (3) of sintering the green compact in step (2) in a vacuum environment to obtain the sintered Re-Fe-B permanent magnet.

[0014] According to an embodiment of the present invention, in step (1), the raw material for producing the NdFeB strip cast ribbon includes Re, M1, Ti, B, the remaining Fe and unavoidable impurity elements, the mass content of Re is 28 to 35 wt%, and Re is at least one or more selected from Sm, La, Ce, Y, Nd, Pr, Ho, Gd, Dy, and Tb; the mass content of M1 is 0.5 wt%≦M≦5 wt%, and M1 is at least one or more selected from Co, Ga, Cu, Al, Nb, and Zr; The mass content of Ti is 0.1 wt% <Ti≦0.5wt%であり、 The mass content of B is 0.8 wt%≦B≦1.2 wt%.

[0015] The inventors have found that if Re exceeds 35 wt%, the magnetic energy product of the magnet will be significantly reduced and the cost will be significantly increased due to the excessively high Re content, and if Re is less than 28 wt%, the magnetic energy product of the magnet will be significantly reduced and the cost will be significantly increased. 14 There is not enough Re to form B-phase crystal grains, which significantly reduces performance. The role of Co in M1 is to favor the Curie temperature of the magnet and improve the temperature coefficient of magnetic performance. The role of Ga / Cu / Al is to improve the coercivity of the magnet, and the role of Nb / Zr is to replace part of the iron, effectively improving the coercivity and squareness of the magnet. If M is less than 0.5 wt%, the coercivity and temperature stability of the magnet will be significantly reduced, and if M is more than 5 wt%, the magnetic energy product of the magnet will be significantly reduced.

[0016] According to an embodiment of the present invention, in order to generate a Re-Fe-Ti-B phase in the grain boundary phase, the atomic contents of Re, Ti, and B need to be further controlled, and their corresponding atomic contents have the above-mentioned meanings, for example, satisfying [Re]-2[B]+4[Ti]≧1.91% (at%).

[0017] If a magnet contains too much B, a non-magnetic B-rich phase will form, significantly reducing the performance of the magnet. At the same time, both Re and Ti consume B, resulting in the formation of Re2Fe 14 From B's point of view, 2% Re is the required Re2Fe 14 1% B is required to form B-major phase grains (at%), and Ti also consumes some of the B. To ensure that the Re-Fe-Ti-B phase can be formed without forming additional B-rich phases, the atomic contents of Re, Ti, and B must satisfy the above relationship.

[0018] Illustratively, the composition is 29.5 wt% Nd, 0.2 wt% Ga, 0.2 wt% Al, 0.15 wt% Cu, 1.0 wt% Co, 0.25 wt% Ti, 1.0 wt% B, and the remainder is Fe and impurity elements.

[0019] According to an embodiment of the present invention, in step (1), the NdFeB strip cast ribbon is produced by a method known in the art, such as a strip cast melt spinning technique. Illustratively, the NdFeB strip cast ribbon is produced by heating and melting the raw materials to 1300 to 1600°C by electromagnetic induction, casting the molten alloy onto a chill roll (preferably a polished chill roll), and cooling to obtain NdFeB strip cast ribbons, which are alloy flakes.

[0020] According to an embodiment of the present invention, the grain boundary expansion treatment step comprises heating the neodymium iron boron strip cast ribbon cooled to 20 to 80°C to a high temperature of 700 to 1000°C under vacuum conditions, treating for 1 to 3 hours, and then cooling to room temperature. Preferably, during the grain boundary expansion treatment, the neodymium iron boron strip cast ribbon needs to be placed in a high-temperature resistant metallic container so as not to be contaminated.

[0021] The inventors also found that during the grain boundary expansion treatment, if the heating temperature is less than 700°C, the rare earth-rich phase in the grain boundary phase cannot be completely melted, resulting in an inhomogeneous distribution of the rare earth-rich phase; if the heating temperature exceeds 1000°C, the edges of the main phase crystal grains melt and columnar crystals grow abnormally; if the treatment time is less than one hour, it is not possible to provide enough heat to uniformly disperse the rare earth-rich phase; and if the treatment time exceeds three hours, costs increase and energy is wasted.

[0022] The inventors have discovered the following. During the cooling process of the molten alloy, the Re-Fe-Ti-B precipitates have a higher melting point, so the Re-Fe-Ti-B phase precipitates first during the cooling process, but this phase tends to be randomly distributed within the cast alloy strip ribbon. By subjecting the cast alloy strip ribbon to a grain boundary expansion treatment, the rare-earth-rich phase in the grain boundary phase can be melted and flowed, resulting in a more uniform distribution of the rare-earth-rich phase surrounding the main phase crystal grains (preferably columnar crystals). This is advantageous for the rare-earth-rich phase to more uniformly surround the main phase crystal grains during the milling process. As a result, during the sintering process, the Re-Fe-Ti-B phase distributes along the molten rare-earth-rich phase to the grain boundary phase, and aggregates, particularly at intergranular and triangular grain boundaries, providing the conditions necessary for the Re-Fe-Ti-B phase to further grow during the subsequent sintering process.

[0023] According to an embodiment of the present invention, in step (2), the pulverization step specifically includes subjecting the NdFeB strip cast ribbon to hydrogen pulverization to obtain a coarsely pulverized powder, and then pulverizing the coarsely pulverized powder in a high-energy ball milling process or a jet mill using a jet milling process to obtain a magnetic powder. Preferably, a lubricant may be added during pulverization. Any lubricant known in the art may be used as the lubricant, and the present invention does not particularly limit the lubricant. Furthermore, the amount of the lubricant added is 0.1 to 1 wt %, for example, 0.1 to 0.5 wt %, of the magnetic powder.

[0024] For example, in step (2), the pulverization step is as follows: the neodymium-iron-boron strip cast ribbon is subjected to hydrogen pulverization to obtain a coarsely pulverized powder, which is then polished and pulverized in a jet mill to obtain a magnetic powder of a target particle size. Optionally, after obtaining the magnetic powder of the target particle size, 0.1 to 0.5 wt % of a lubricant may be added and mixed, for example, for 0.1 to 5 hours to uniformly mix the magnetic powder.

[0025] In the present invention, the hydrogen pulverization, high energy ball milling process, and jet milling process can all be carried out using process conditions known in the art, as long as the magnetic powder is obtained.

[0026] According to an embodiment of the present invention, in step (2), the production of the green compact comprises orienting the magnetic powder in a magnetic field and pressing the magnetic powder to obtain a green compact. Preferably, the magnetic field may be a magnetic field known in the art, for example, the magnetic field strength is 2 T. Preferably, after the orientation and pressing, cold isostatic pressing may be optionally performed. Preferably, the cold isostatic pressing may be performed under cold isostatic pressing conditions known in the art, and the present invention is not particularly limited thereto.

[0027] According to an embodiment of the present invention, in step (3), the sintering treatment includes gradually increasing the temperature of the green compact in a vacuum environment up to a sintering temperature of 1000 to 1100°C, maintaining the temperature for 0.5 to 4 hours, cooling, and then performing a pulse aging heat treatment.

[0028] Preferably, the stepwise temperature increase specifically includes increasing the temperature from room temperature to a first temperature (e.g., 220 to 260°C, e.g., 240°C) and maintaining the temperature for 10 to 60 minutes, then increasing the temperature to a second temperature (e.g., 380 to 420°C, e.g., 400°C) and maintaining the temperature for 10 to 60 minutes (e.g., 30 minutes), then increasing the temperature to a third temperature (e.g., 700 to 750°C, e.g., 750°C) and maintaining the temperature for 30 to 120 minutes (e.g., 90 minutes), and then increasing the temperature to a sintering temperature of 1000 to 1100°C and maintaining the temperature for 0.5 to 4 hours (e.g., 3.5 hours). Furthermore, during the stepwise temperature increase, the temperature increase rate is 1 to 10°C / min, e.g., 5°C / min, 6°C / min, or 8°C / min.

[0029] Preferably, the pulse aging heat treatment specifically includes step (a) of increasing the temperature to 700 to 900°C at a heating rate of 5 to 15°C / min, maintaining the temperature for 2 to 6 hours, and then cooling to room temperature; step (b) of repeating the operation of step (a) 1 to 5 times (e.g., 2, 3, or 4 times); and step (c) of aging at 450 to 650°C for 2 to 6 hours.

[0030] The inventors have found the following: 1) During the pulse aging heat treatment, the temperature during the aging heating process is controlled to 700-900°C to melt the rare earth-rich phase. If the number of aging heating processes is too small, sufficient energy cannot be provided for uniform distribution and crystallization of the Re-Fe-Ti-B rods, so the aging heating process is performed at least twice. 2) When the pulse aging heat treatment is used, the Re-Fe-Ti-B rods are distributed along the molten grain boundaries and aggregate in the grain boundary phase (e.g., intergranular grain boundaries, triangular grain boundaries), and Ti and B elements crystallize in the Re-Fe-Ti-B rods, causing the size of the Re-Fe-Ti-B rods to increase. This prevents the grain size from increasing, weakens the magnetic coupling effect between the main phase crystal grains, and improves the performance of the sintered Re-Fe-B permanent magnet.

[0031] The present invention also provides a sintered Re-Fe-B permanent magnet manufactured by the above manufacturing method, and the sintered Re-Fe-B permanent magnet has the above-mentioned meaning.

[0032] The present invention also provides the use of the above-mentioned sintered Re-Fe-B permanent magnet, preferably for use in a motor. [Effects of the Invention]

[0033] The beneficial effects of the present invention are as follows:

[0034] The sintered NdFeB permanent magnet of the present invention is manufactured by combining formulation design and process optimization to form large-sized Re-Fe-Ti-B rods, which prevent the formation of boron-rich phases and cause the Re-Fe-Ti-B rods to aggregate at the grain boundaries, thereby preventing the increase in grain size, suppressing the growth of main phase grains, and weakening the magnetic coupling effect between the main phase grains, thereby improving the performance of the sintered Re-Fe-B permanent magnet. [Brief explanation of the drawings]

[0035] [Figure 1] 1 is a TEM image of Example 1. [Figure 2] 1 is a TEM image of Comparative Example 1. [Figure 3] 1 is a TEM image of Comparative Example 3-3. [Figure 4] FIG. 1 is a schematic diagram of the processing of a sample column. [Figure 5] 1 is a schematic diagram of a sintered Re—Fe—B permanent magnet of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] The following will further describe the technical solutions of the present invention in detail with reference to specific examples. It should be understood that the following examples are only intended to exemplify and explain the present invention, and should not be construed as limiting the protection scope of the present invention. Any technology realized based on the above content of the present invention is included in the protection scope of the present invention.

[0037] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0038] Examples 1 to 5 The manufacturing method of a sintered Re-Fe-B permanent magnet includes the following steps: (1) The raw materials were mixed in the ratios shown in Table 1, and the mixed materials were vacuum melted and kept at 1420°C for 15 minutes. Then, the mixture was cast onto the surface of a quenching roll and then cooled in a water-cooled bath to obtain the desired scales. (2) The scales from step (1) were collected, subjected to grain boundary expansion treatment, placed in a high-temperature resistant metal container, and placed in a vacuum sintering furnace. The temperature was increased from room temperature to 900°C, kept at 900°C for 300 minutes, and then cooled to room temperature. (3) The scales from step (2) were collected, subjected to hydrogen pulverization to coarsely pulverize them, and then polished in a jet mill to obtain magnetic powder with a target particle size VMD=3.1 μm. (4) The magnetic powder from step (3) was filled into a vacuum press mold, oriented in a magnetic field strength of 2 T, press-molded, and cold isostatically pressed to obtain a green compact. (5) The compact from step (4) was placed in a vacuum sintering furnace, heated from room temperature to 240°C at a rate of 6°C / min, held at 240°C for 60 minutes, then heated to 400°C at a rate of 4°C / min and held at 400°C for 30 minutes, then heated to 750°C at a rate of 5°C / min and held at 750°C for 90 minutes, then heated to 1040°C at a rate of 8°C / min and sintered for 3.5 hours. The compact was then subjected to the following pulse aging heat treatments: (a) a one-step aging treatment at 800°C for 4 hours and then cooled to room temperature; (b) the one-step aging treatment of step (a) was repeated three times; and (c) a two-step aging treatment at 480°C for 4 hours to obtain an Nd-Fe-B blank, i.e., a sintered Re-Fe-B permanent magnet. Comparative Example 1

[0039] In this comparative example, the method for producing a sintered Re-Fe-B permanent magnet was almost the same as in Example 1, except that the scales of step (1) were directly processed according to steps (3) to (5) without undergoing the grain boundary expansion treatment of step (2). Comparative Example 2

[0040] In this comparative example, the method for producing a sintered Re—Fe—B permanent magnet was almost the same as in Example 1, except that in step (5), pulse aging heat treatment was not performed after sintering was completed. The remaining steps were the same as in Example 1. Comparative Examples 3-1, 3-2, and 3-3

[0041] In Comparative Examples 3-1, 3-2, and 3-3, the method for producing the sintered Re-Fe-B permanent magnet was almost the same as that of Example 1, except that in step (1), the materials were blended in the corresponding raw material blending ratios shown in Table 1. The remaining steps were the same as in Example 1.

[0042] [Table 1] JPEG2026015294000003.jpg35169 In Table 1, the content of each element is expressed as a mass percentage, and [Re], [B], and [Ti] represent the atomic contents of Re, B, and Ti, respectively. Test Example

[0043] (1) Magnetic performance test After uniformly removing the skin from the Nd-Fe-B blanks manufactured in the above examples and comparative examples, a φ10 * Ten sample columns were fabricated and subjected to magnetic performance tests. A schematic diagram of the fabrication of the sample columns is shown in Figure 4. (2) Evaluation of organizational characteristics Samples were taken from the corners and center of each Nd-Fe-B blank produced in the above examples and comparative examples to produce TEM test samples with a diameter of 3 mm and a thickness of 150 nm. Each was observed using a TEM. After magnification, at least one complete main phase crystal grain or grain boundary phase (including a rare earth-rich phase) was present within the observation field, and a component analysis of element distribution points including Ti element was performed within the observation field. The test results are shown in Table 2.

[0044] [Table 2] Detection results

[0045] Figure 1 is a TEM image of the sample of Example 1. In the sample of Example 1, the Re-Fe-Ti-B phase (Re-Fe-Ti-B rod-like particles) is observed, and this phase is distributed only at the grain boundaries. The component of this phase is (PrNd) 1.9 Fe 4.1 Ti 81.4 B 12.6 and this phase is rod-like with a length of about 255 nm. 2 is a TEM image of the sample of Comparative Example 1. In the sample of Comparative Example 1, a Re—Fe—Ti—B phase is observed, and this phase is distributed within the main phase crystal grains. Comparative Example 3-3

[0046] 3 is a TEM image of the sample of Comparative Example 3-3. In the sample of Comparative Example 3-3, no Re—Fe—Ti—B phase was observed.

[0047] From Tables 1 and 2, the following was found:

[0048] In Examples 1, 2, 3, and 4, the Re-Fe-Ti-B phase was observed in the grain boundary phase. The Re-Fe-Ti-B rods were distributed along the fused grain boundaries and aggregated in the grain boundary phase (e.g., intergranular grain boundaries, triangular grain boundaries). Ti and B elements were crystallized in the Re-Fe-Ti-B rods, and no Re-Fe-Ti-B rod crystals were observed in the main phase grains. The dimensions of the Re-Fe-Ti-B rods were observed to be 255 nm, 193 nm, 234 nm, and 198 nm, respectively. The large-sized Re-Fe-Ti-B phases concentrated in the grain boundary phase better prevented the grain size from increasing, weakened the magnetic coupling effect between the main phase grains, and improved the performance of the sintered Re-Fe-B permanent magnets.

[0049] Comparison of Example 1 with Comparative Examples 3-1, 3-2, and 3-3 revealed that only the B and Ti contents and ratios described in the present invention allowed the formation of Re-Fe-Ti-B rods in the grain boundary phase of a permanent magnet.

[0050] A comparison between Example 1 and Comparative Example 1 revealed that when pulse aging treatment was performed without grain boundary expansion treatment, the Re-Fe-Ti-B phase was present in the grain boundary phase of the permanent magnet, but some of the Re-Fe-Ti-B rod-shaped particles also entered the main phase crystal grains, which destroyed the structure of the main phase crystal grains and significantly reduced the Br value of the permanent magnet.

[0051] A comparison between Example 1 and Comparative Example 2 revealed that when the composition of the Nd-Fe-B blank was the same, and only the grain boundary expansion treatment was performed, Re-Fe-Ti-B rods could be similarly produced in the grain boundary phase of the permanent magnet. However, since the pulse aging treatment was not performed, the dimensions of the Re-Fe-Ti-B rods were significantly reduced, and therefore the magnetic performance of Comparative Example 2 was found to be inferior to that of Example 1.

[0052] From the above, the inventors believe that the grain boundary expansion treatment and pulse aging treatment cause the Re-Fe-Ti-B phase to crystallize and grow by agglomerating at the intergranular grain boundaries and triangular grain boundaries, resulting in the formation of Re-Fe-Ti-B rods, which effectively suppress the growth of the main phase crystal grains and reduce the proportion of the boron-rich phase in the permanent magnet, ultimately benefiting the improvement of the magnetic performance of the permanent magnet.

[0053] The above describes exemplary embodiments of the present invention. However, the scope of protection of the present application is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made by those skilled in the art within the spirit and principle of the present invention should be included within the scope of protection of the present invention.

Claims

1. 1. A sintered Re-Fe-B permanent magnet, comprising: a Ti-based precipitate phase; the Ti-based precipitate phase being Re-Fe-Ti-B rod-shaped particles; the length of the Re-Fe-Ti-B rod-shaped particles being 100 to 300 nm; the Ti-based precipitate phase having an atomic content of Re of 1 to 20 at %, an atomic content of Fe of 1 to 30 at %, an atomic content of Ti of 40 to 90 at %, and an atomic content of B of 10 to 20 at %, with the atomic content ratio of Ti to B being 4:1 to 9:

1.

2. 2. The sintered Re-Fe-B permanent magnet according to claim 1, wherein the Ti-based precipitate phase is distributed only in the grain boundary phase.

3. The components of the Re-Fe-B permanent magnet are Re ａ Fe １－ａ－ｂ－ｃ－ｄ M1 ｂ Ti ｃ B ｄ where: Re is at least one or more elements selected from Sm, La, Ce, Y, Nd, Pr, Ho, Gd, Dy, and Tb, and 28 wt%≦a≦35 wt%; M1 is at least one or more selected from Co, Ga, Cu, Al, Nb, and Zr, and 0.5 wt%≦b≦5 wt%; The content of Ti is 0.05 wt%<c≦0.5 wt%, The content of B is 0.8 wt%≦d≦1.2 wt%; 3. The sintered Re-Fe-B permanent magnet according to claim 1, wherein the remainder is Fe and unavoidable impurity elements.

4. The sintered Re—Fe—B permanent magnet according to claim 1, characterized in that, when the atomic contents of Re, Ti, and B among the components of the Re—Fe—B permanent magnet are designated as [Re], [Ti], and [B], respectively, they satisfy the relationship: [Re] - 2[B] + 4[Ti] ≧ 1.91 at %.

5. 2. A method for producing a sintered Re—Fe—B permanent magnet according to claim 1, comprising the steps of: A step (1) of producing a neodymium-iron-boron strip cast ribbon and performing a grain boundary expansion treatment on the neodymium-iron-boron strip cast ribbon; (2) crushing the neodymium-iron-boron strip cast ribbon to obtain magnetic powder having an average particle size of 2 to 5 μm, and then pressing the magnetic powder into a powder compact; and step (3) sintering the powder compact of step (2) in a vacuum environment to obtain the sintered Re—Fe—B permanent magnet.

6. In step (1), the raw material for producing the neodymium iron boron strip cast ribbon contains Re, M1, Ti, B, the remaining Fe and unavoidable impurity elements; the mass content of Re is 28 to 35 wt %, and Re is at least one or more selected from Sm, La, Ce, Y, Nd, Pr, Ho, Gd, Dy, and Tb; The mass content of M1 is 0.5 wt%≦M≦5 wt%, and M1 is at least one or more selected from Co, Ga, Cu, Al, Nb, and Zr; The mass content of Ti is 0.1 wt% < Ti ≦ 0.5 wt%, The mass content of B is 0.8 wt%≦B≦1.2 wt%, 6. The manufacturing method according to claim 5, wherein in step (1), the grain boundary expansion treatment step comprises heating the NdFeB strip cast ribbon cooled to 20 to 80°C to a high temperature of 700 to 1000°C under vacuum conditions, treating for 1 to 3 hours, and then cooling to room temperature.

7. In step (2), the pulverizing step specifically includes subjecting the neodymium-iron-boron strip cast ribbon to hydrogen pulverization to obtain coarsely pulverized powder, and then pulverizing the coarsely pulverized powder in a high-energy ball milling process or a jet milling process to obtain magnetic powder; 6. The method according to claim 5, wherein in step (2), the production of the green compact includes orienting the magnetic powder in a magnetic field and press-molding the magnetic powder to obtain the green compact.

8. 6. The method according to claim 5, wherein in step (3), the sintering treatment comprises gradually increasing the temperature of the powder compact in a vacuum environment to a sintering temperature of 1000 to 1100°C, maintaining the temperature for 0.5 to 4 hours, cooling the compact, and then performing a pulse aging heat treatment.

9. Specifically, the stepwise temperature increase includes increasing the temperature from room temperature to a first temperature retention and maintaining the temperature for 10 to 60 minutes, then increasing the temperature to a second temperature retention and maintaining the temperature for 10 to 60 minutes, then increasing the temperature to a third temperature retention and maintaining the temperature for 30 to 120 minutes, and further increasing the temperature to a sintering temperature of 1000 to 1100°C and maintaining the temperature for 0.5 to 4 hours. The manufacturing method according to claim 8, wherein the pulse aging heat treatment specifically includes: step (a) of increasing the temperature to 700 to 900°C at a heating rate of 5 to 15°C / min, maintaining the temperature for 2 to 6 hours, and then cooling to room temperature; step (b) of repeating the operation of step (a) 1 to 5 times; and step (c) of performing aging treatment at 450 to 650°C for 2 to 6 hours.

10. Use of the sintered Re-Fe-B permanent magnet according to claim 1 in a motor.

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