Grain boundary phase-containing samarium iron-based rare earth permanent magnet material, its manufacturing method, and applications

Abstract

The present invention provides a method for producing a samarium-iron-based rare earth permanent magnet material containing grain boundary phase, and by controlling the alloy components and the process parameters in the rapid solidification method, the problem of the inability to form a non-magnetic grain boundary phase due to the lack of liquid phase in the samarium-iron-based rare earth permanent magnet material can be solved, and the purity of the main phase can be improved. This method includes: using pure metal samarium, iron, cobalt, titanium and other key elements as raw materials, and preparing the raw materials by converting the ratio of the atomic number of the pure metal into the mass ratio; using a vacuum high-frequency induction melting furnace to melt the alloy under the condition of high purity argon gas to obtain a master alloy ingot of nominal composition, and melting the alloy twice to keep the sample uniform; grinding the surface impurities of the alloy ingot, crushing it into small pieces, and putting it into a vacuum rapid solidification device, and controlling the rapid solidification speed to 5m / s to 50m / s to obtain a uniform and stable rapid ribbon-shaped samarium-iron-based rare earth permanent magnet containing grain boundary phase. The quenched ribbon-like thin film produced in the present invention has excellent performance at low cost and can be widely applied in the fields of electronic information, energy conversion, etc.

Description

[Technical Field]

[0001] This application claims priority from Application No. 202211464706.4, filed with the State Intellectual Property Office of China on November 22, 2022, entitled "Grain boundary phase-containing samarium iron-based rare earth permanent magnet material, its manufacturing method, and application," the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the technical field of rare earth permanent magnet materials, and in particular to a grain boundary phase-containing samarium iron-based rare earth permanent magnet material, its manufacturing method, and applications. [Background technology]

[0003] Samarium-iron-based rare earth permanent magnet materials were discovered in the 1980s and have been in development for 40 years. With rising rare earth prices in the international market and the rapid development of China's new energy automobile industry, demand for rare earth permanent magnet materials is expanding, necessitating the development of permanent magnets with low rare earth content and high magnetic energy product. Samarium-iron-based permanent magnet materials have the lowest rare earth element content, are inexpensive, and have a high anisotropy magnetic field, high saturation magnetization strength, and a higher theoretical magnetic energy product. Their Curie temperature can reach above 500°C, making them suitable for use in high-temperature magnetic materials.

[0004] Currently, there are three main methods for producing samarium-iron-based rare earth permanent magnet materials: sintering, redox, and rapid solidification. The sintering method typically involves melting pure metal elements into an alloy ingot, then grinding the ingot into micron-sized powder. The micron-sized powder is then oriented and pressed into a magnet block, which is then sintered. However, this method requires slow cooling, resulting in large grain sizes and low coercivity. The redox method involves reducing various raw oxide powders in a ball mill using high-energy ball milling to produce alloy powder, but this method is not suitable for large-scale production. Rapid solidification, on the other hand, typically involves rapid cooling to produce samarium-iron-based rare earth permanent magnet materials with nano-sized grains. This method is simple to operate and convenient for industrial production.

[0005] However, because samarium-iron-based rare earth permanent magnet materials do not have a liquid phase in their phase region, it is difficult to form a continuous, uniform non-magnetic grain boundary phase, and there is a large difference between the actual coercivity and the theoretical coercivity. Researchers working on rare earth permanent magnet materials have hoped to create rapidly quenched ribbons of samarium-iron-based rare earth permanent magnets in which the main phase is surrounded by a non-magnetic grain boundary phase, and this has also been a hot topic in the field of magnetic materials research in recent years. Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above circumstances, the present invention aims to provide a grain boundary phase-containing samarium-iron-based rare earth permanent magnet material, a manufacturing method thereof, and applications thereof. The grain boundary phase-containing samarium-iron-based rare earth permanent magnet material provided by the present invention has a grain boundary phase and exhibits better performance. [Means for solving the problem]

[0007] The present invention provides a grain boundary phase-containing samarium iron-based rare earth permanent magnet material, the chemical formula of which is: Sm a Fe b Co c Tid M e Formula I and In formula I, 0.5≦a≦1.5, 7.5≦b≦9.0, 2.0≦c≦3.0, 0.5≦d≦1.5, and 0.1≦e≦2.0; M is one or more selected from the group consisting of B, C, Al and Si.

[0008] Preferably, the grain boundary phase-containing samarium-iron-based rare earth permanent magnet material contains a samarium-iron-based main phase, a grain boundary phase, and an α-Fe phase, a non-magnetic element is segregated and distributed in the grain boundary phase, The grain boundary phase envelops the surface of the samarium-iron-based main phase.

[0009] Preferably, the volume content of the samarium-iron-based main phase in the grain boundary phase-containing samarium-iron-based rare earth permanent magnet material is 70% to 99%, the volume content of the grain boundary phase in the grain boundary phase-containing samarium-iron-based rare earth permanent magnet material is 1% to 30%, The volume content of the α-Fe phase in the grain boundary phase-containing samarium iron-based rare earth permanent magnet material is 1% to 20%.

[0010] Preferably, the crystal grain size of the samarium-iron-based main phase is 20 nm to 500 nm, The grain size of the grain boundary phase is 1 nm to 50 nm.

[0011] The present invention provides a method for producing a grain boundary phase-containing samarium-iron-based rare earth permanent magnet material as described in the above technical solution, preparing alloy raw materials, melting them, and casting them to obtain a master alloy; and rapidly solidifying and melt-spinning the master alloy to obtain a samarium-iron-based rare earth permanent magnet material containing a grain boundary phase.

[0012] Preferably, the output of the smelting is 14 kw to 19 kw.

[0013] Preferably, the casting output is 5 kW to 9 kW.

[0014] Preferably, the nozzle diameter of the quartz tube during the rapid solidification and melt spinning is 1 mm to 4 mm, and the distance from the nozzle of the quartz tube to the copper roll is 1 mm to 4 mm.

[0015] Preferably, the melt temperature during the rapid solidification and melt spinning is 1000°C to 1700°C, the pressure difference between the gas storage tank and the chamber is 0.02MPa to 0.06MPa, and the rapid solidification speed is 5m / s to 50m / s.

[0016] The present invention provides a magnetic device including the grain boundary phase-containing samarium iron-based rare earth permanent magnet material described in the above technical solution.

[0017] Through the research of the present invention, it has been discovered that controlling the alloy composition and the rapid solidification process has a significant effect on the grain size and micromorphology of the quenched ribbon sample. For example, the alloy composition, the rapid solidification rate, the pressure difference between the gas storage tank and the chamber, and the melt temperature all have a significant effect on the uniformity and performance of the sample. Therefore, controlling these parameters is the key to obtaining a quenched ribbon of a nanocrystalline samarium iron-based rare earth permanent magnet with a uniform grain boundary phase, which is also a challenge that must be solved by those skilled in the art. Furthermore, the alloy composition content and the rapid solidification rate are the most important parameters in the quenching process, which are also key to affecting the purity and phase composition of the main phase. Through the research of the present invention, it has been discovered that the alloy with the chemical formula Sm a Fe b Co c Ti d M e (wherein, 0.5≦a≦1.5, 7.5≦b≦9.0, 2.0≦c≦3.0, 0.5≦d≦1.5, 0.1≦e≦1.0) M is an important additive element, and it was discovered that by controlling the roll speed to 5 m / s to 40 m / s or less, a stable quenched ribbon-shaped samarium-iron rare earth permanent magnet can be obtained. [Brief explanation of the drawings]

[0018] [Figure 1]1 is a transmission electron microscope photograph of a quenched ribbon of a samarium-iron-based rare earth permanent magnet produced in Comparative Example 1 of the present invention. [Figure 2] FIG. 2 is an element detection diagram of a quenched ribbon of a samarium-iron-based rare earth permanent magnet produced in Comparative Example 1 of the present invention. [Figure 3] 1 is a transmission electron microscope photograph of a quenched ribbon of a grain boundary phase-containing samarium iron-based rare earth permanent magnet produced in Example 1 of the present invention. [Figure 4] FIG. 2 is an element detection diagram of the quenched ribbon of the grain boundary phase-containing samarium iron-based rare earth permanent magnet produced in Example 1 of the present invention. [Figure 5] FIG. 1 is an XRD diffraction pattern of a quenched ribbon of a samarium-iron-based rare earth permanent magnet produced in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention provides a grain boundary phase-containing samarium iron-based rare earth permanent magnet material, the chemical formula of which is: Sm a Fe b Co c Ti d M e Formula I and In formula I, 0.5≦a≦1.5, 7.5≦b≦9.0, 2.0≦c≦3.0, 0.5≦d≦1.5, and 0.1≦e≦2.0; M is one or more selected from the group consisting of B, C, Al and Si.

[0020] In the present invention, the a is preferably 0.8 to 1.2, and more preferably 1; the b is preferably 8 to 8.5, and more preferably 8.2 to 8.3; the c is preferably 2.3 to 2.7, and more preferably 2.5; the d is preferably 0.8 to 1.2, and more preferably 1%; and the e is preferably 0.5 to 1.5, and more preferably 0.8 to 1.2, and most preferably 1%.

[0021] In the present invention, the grain boundary phase-containing samarium iron-based rare earth permanent magnet material preferably includes a samarium iron (cobalt) substrate main phase, a grain boundary phase, and an α-Fe phase.

[0022] In the present invention, preferably, the non-magnetic element is segregated and distributed mainly in the grain boundary phase, and the grain boundary phase uniformly envelops the surface of the samarium-iron-based main phase.

[0023] In the present invention, the volume content of the samarium-iron-based main phase in the grain boundary phase-containing samarium-iron-based rare earth permanent magnet material is preferably 70% to 99%, more preferably 75% to 95%, more preferably 80% to 90%, and most preferably 85%. The volume content of the grain boundary phase in the grain boundary phase-containing samarium-iron-based rare earth permanent magnet material is preferably 1% to 30%, more preferably 5% to 25%, more preferably 10% to 20%, and most preferably 15%. The volume content of the α-Fe phase (soft magnetic phase) in the grain boundary phase-containing samarium-iron-based rare earth permanent magnet material is preferably 1% to 20%, more preferably 5% to 15%, more preferably 8% to 12%, and most preferably 10%.

[0024] In the present invention, the crystal grain size of the samarium-iron-based main phase is preferably 20 nm to 200 nm, more preferably 50 nm to 150 nm, more preferably 80 nm to 120 nm, and most preferably 100 nm, and the crystal grain size of the grain boundary phase is preferably 2 nm to 100 nm, more preferably 10 nm to 80 nm, more preferably 20 nm to 60 nm, more preferably 30 nm to 50 nm, and most preferably 40 nm.

[0025] The present invention provides a method for producing a grain boundary phase-containing samarium-iron-based rare earth permanent magnet material as described in the above technical solution, After blending the raw material alloys, they are melted and cast to obtain a master alloy; and rapidly solidifying and melt-spinning the master alloy to obtain a samarium-iron-based rare earth permanent magnet material containing a grain boundary phase.

[0026] In the present invention, there are no particular limitations on the alloy raw materials, and any raw materials for producing permanent magnet materials that are well known to those skilled in the art can be used. In the present invention, it is sufficient to provide a Sm source, an Fe source, a Co source, a Ti source, and an M source.

[0027] In the present invention, there is no particular limitation on the method for compounding the raw materials, and they may be compounded according to the chemical formula of Formula I using methods well known to those skilled in the art. When compounding the raw materials, it is preferable to replenish the burnt-out amount, and the burnt-out element is Sm, that is, when compounding the Sm element, it is added in an amount of 1 wt% to 30 wt%, more preferably 5% to 25%, more preferably 10% to 20%, and most preferably 15%.

[0028] In the present invention, the melting is preferably carried out using a vacuum high-frequency induction furnace, and the degree of vacuum during the melting process is (3 to 7) × 10 -2 Pa is preferably (4 to 6) × 10 -2 Pa is more preferable, and 5×10 -2 It is most preferable that the melting power is 14 kW to 19 kW, more preferably 15 kW to 18 kW, and most preferably 16 kW to 17 kW. The casting power is preferably 5 kW to 9 kW, more preferably 6 kW to 8 kW, and most preferably 7 kW. It is preferable that the number of melting operations is 1 to 3, and it is more preferable that the alloy is repeatedly melted twice.

[0029] In the present invention, preferably, the melting and casting method comprises: The prepared alloy material is placed in a vacuum induction melting furnace, and after charging, the furnace lid is closed and the temperature is (3-7) x 10 -2Preferably, the method includes evacuating the material to 100 Pa, baking at a relatively low temperature to remove water vapor and gases adsorbed on the surface of the raw materials, filling with high-purity argon gas after the degree of vacuum has stabilized, gradually increasing the heating power, and after the raw materials have completely melted, reducing the heating power, keeping the temperature for 2 to 5 minutes, and then casting the alloy liquid into a copper mold and cooling it.

[0030] In the present invention, the relatively low temperature is preferably 1400° C. to 1800° C., more preferably 1500° C. to 1700° C., and most preferably 1600° C. After the vacuum is stabilized, the degree of vacuum is less than 2×10 -2 The pressure of the filled argon gas is preferably 0.04 MPa to 0.08 MPa, more preferably 0.05 MPa to 0.07 MPa, and most preferably 0.06 MPa. The purity of the argon gas is preferably 99.999%. The range for gradually increasing the output is preferably 12 kW to 18 kW, more preferably 13 kW to 17 kW, more preferably 14 kW to 16 kW, and most preferably 15 kW. The range for decreasing the heating output is preferably 10 kW to 8 kW, and more preferably 9 kW. The warming time is preferably 3 to 4 minutes.

[0031] In the present invention, it is preferable to polish impurities on the surface of the master alloy and crush the master alloy into small pieces before the rapid solidification and melt spinning. The rapid solidification and melt spinning are preferably performed in a vacuum rapid solidification apparatus, and a rapidly quenched ribbon of rare earth containing grain boundary phases can be discharged from the vacuum rapid solidification apparatus.

[0032] In the present invention, the nozzle diameter of the quartz tube during the rapid solidification and melt spinning is preferably 1 mm to 4 mm, more preferably 2 mm to 3 mm. The distance from the nozzle of the quartz tube to the copper roll is preferably 1 mm to 4 mm, more preferably 2 mm to 3 mm. The melt temperature is preferably 1000°C to 1700°C, more preferably 1100°C to 1600°C, more preferably 1200°C to 1500°C, and most preferably 1300°C to 1400°C. The melt temperature is preferably measured using an infrared thermometer. The pressure difference between the gas storage tank and the chamber is preferably 0.02 MPa to 0.06 MPa, more preferably 0.03 MPa to 0.05 MPa, and most preferably 0.04 MPa. The rapid solidification speed is preferably 10 m / s to 50 m / s, more preferably 20 m / s to 40 m / s, and most preferably 30 m / s.

[0033] The present invention provides a magnetic device including the grain boundary phase-containing samarium iron-based rare earth permanent magnet material described in the above technical solution.

[0034] The rapidly spun ribbon produced by the present invention is low-cost and can be used in the development of bonded magnetic powders and magnetic devices in fields such as information and communications. Compared to conventional techniques, this invention overcomes problems in samarium-iron-based rare earth permanent magnet materials, such as a lack of grain boundary phase and ease of α-Fe precipitation, and provides a new concept for the development of new samarium-iron-based rare earth permanent magnets with high coercivity.

[0035] The microstructure of the samarium-iron-based rare earth permanent magnet material containing a grain boundary phase provided by the present invention includes not only a samarium-iron-based main phase with permanent magnetic properties but also a grain boundary phase, which is not found in conventional samarium-iron-based rare earth permanent magnet materials. The present invention utilizes the samarium-iron-based main phase and grain boundary phase to achieve high magnetic properties, yet does not require complex processes and can be applied to low-cost rare earth permanent magnet materials. [Example]

[0036] Example 1 Raw material mixture: stoichiometric formula (SmFe 8.8 Co2.2 Ti1B 0.25 The raw materials are mixed in the molar ratio of each element.

[0037] Melting: Put the mixed raw materials into a vacuum induction melting furnace, cover the furnace after charging, and mix 5 x 10 -2 The material is then evacuated to a vacuum of 100 Pa, and then baked at a lower temperature to remove water vapor and gases adsorbed on the surface of the material. After the vacuum level stabilizes (<2×10 -2 The furnace was filled with high-purity argon gas (99.999%) at a pressure of 0.06 MPa (Pa), and the heating power was gradually increased to 16.8 kW. After the raw materials were completely melted, the heating power was reduced to 8 kW. After keeping the temperature for 2 to 5 minutes, the molten steel was cast and cooled in a copper mold to obtain a master alloy.

[0038] After polishing off surface impurities, the obtained master alloy is pulverized and packed into a quartz tube. The quartz tube has a nozzle diameter of 1 mm, and the distance from the nozzle to the copper roll is 3 mm. The quartz tube is melted in a vacuum high-frequency induction melting furnace, and the melt temperature measured with an infrared thermometer is 1600°C. The pressure difference between the gas storage tank and the chamber is 0.04 MPa, and the ribbon is discharged at a rapid solidification speed of 25 m / s, to obtain a quenched ribbon-shaped rare earth permanent magnet ribbon containing a uniform and stable grain boundary phase.

[0039] FIG. 3 shows a transmission electron microscope photograph of the microstructure of the samarium-iron-based permanent magnet material containing grain boundary phase produced in Example 1 of the present invention. As can be seen from FIG. 3, the microstructure of the samarium-iron-based permanent magnet material containing grain boundary phase is mainly composed of a samarium-iron-based main phase and a grain boundary phase. The grain boundary phase is distributed along the grain boundaries, with the crystal grain size of the main phase being 100 nm to 200 nm and the size of the grain boundary phase being 3 nm to 30 nm.

[0040] FIG. 4 shows the test results of the element distribution of the grain boundary phase-containing samarium-iron-based rare earth permanent magnet material produced in Example 1, and it can be seen that the Ti element is mainly segregated in the grain boundary phase.

[0041] FIG. 5 is an XRD diffraction pattern of the quenched ribbon of the samarium-iron-based rare earth permanent magnet produced in Example 1 of the present invention. As can be seen from FIG. 5, the ratio of the main phase ThMn12 to the soft magnetic phase α-Fe is 97.58 wt.%:2.42 wt.%.

[0042] Example 2 Stoichiometric formula Sm1Fe 8.8 Co 2.2 Ti1B 0.5 A grain boundary phase-containing samarium-iron-based permanent magnet material was produced in the same manner as in Example 1, except that the raw materials were mixed in the molar ratio of each element shown above.

[0043] Example 3 Stoichiometric formula Sm1Fe 8.8 Co 2.2 A samarium-iron-based permanent magnet material containing a grain boundary phase was produced in the same manner as in Example 1, except that the raw materials were mixed in a molar ratio of each element of Ti1B1.

[0044] Example 4 A samarium-iron-based permanent magnet material containing a grain boundary phase was produced in the same manner as in Example 1, except that the rapid solidification and melt spinning speed was 40 m / s.

[0045] Example 5 Stoichiometric formula Sm1Fe 8.8 Co 2.2 Ti1B 0.5 The raw materials were mixed in the molar ratio of each element shown above, and a grain boundary phase-containing samarium-iron-based permanent magnet material was produced in the same manner as in Example 1, except that the rapid solidification and melt spinning speed was 40 m / s.

[0046] Example 6 Stoichiometric formula Sm1Fe 8.8 Co 2.2 Ti1B 0.75 The raw materials were mixed in the molar ratio of each element shown above, and a grain boundary phase-containing samarium-iron-based permanent magnet material was produced in the same manner as in Example 1, except that the rapid solidification and melt spinning speed was 40 m / s.

[0047] Example 7 Stoichiometric formula Sm1Fe8.8 Co 2.2 A grain boundary phase-containing samarium-iron-based permanent magnet material was produced in the same manner as in Example 1, except that raw materials were mixed in a molar ratio of Ti1B1 and the rapid solidification and melt spinning speed was 40 m / s.

[0048] Comparative Example 1 Raw material mixture: stoichiometric formula (SmFe 8.8 Co 2.2 The raw materials were mixed in the molar ratio of each element of Ti1).

[0049] Melting: Put the mixed raw materials into a vacuum induction melting furnace, cover the furnace after charging, and mix 5 x 10 -2 The material is then evacuated to a vacuum of 10 Pa, and then baked at a relatively low temperature to remove water vapor and gases adsorbed on the surface of the material. After the vacuum level stabilizes (<2×10 -2 The furnace was filled with high-purity argon gas (99.999%) at a pressure of 0.06 MPa (Pa), and the heating power was gradually increased to 15.7 kW. After the raw materials were completely melted, the heating power was reduced to 7.6 kW. After keeping the temperature for 2 to 5 minutes, the molten steel was cast and cooled in a copper mold to obtain a master alloy.

[0050] The obtained master alloy was ground to remove surface impurities, then pulverized and packed into a quartz tube. The quartz tube had a nozzle diameter of 1 mm and a distance from the nozzle of the quartz tube to a copper roll of 3 mm. The master alloy was melted in a vacuum high-frequency induction melting furnace. The melt temperature measured by an infrared thermometer was 1550°C, the pressure difference between the gas storage tank and the chamber was 0.04 MPa, and the ribbon was discharged at a rapid solidification speed of 25 m / s, yielding a uniform and stable rapid-cooled ribbon of a rare earth permanent magnet containing grain boundary phase.

[0051] Fig. 1 is a transmission electron microscope image of a quenched ribbon of a samarium-iron-based rare earth permanent magnet produced in Comparative Example 1 of the present invention. Fig. 2 is an element detection image of a quenched ribbon of a samarium-iron-based rare earth permanent magnet produced in Comparative Example 1 of the present invention. As can be seen from Figs. 1 and 2, no grain boundary phase was observed in the alloy to which the element M was not added.

[0052] The magnetic properties of the products manufactured in the examples and comparative examples of the present invention were measured. The measurement method was to measure the hysteresis loop by applying an external magnetic field under vacuum conditions of a 9 T magnetic field (instrument type: PPMS-EverCool).

[0053] The measurement results are as follows:

[0054] [Table 1]

[0055] In Examples 1 to 7, it was found that the addition of the key element M and the corresponding manufacturing process precipitated a grain boundary phase that uniformly encloses the crystals of the samarium-iron-based main phase in the samarium-iron-based permanent magnet material, and the coercive force of the quenched ribbon manufactured in Example 1 was significantly increased compared to Comparative Example 1.

[0056] It should be pointed out that the above description is only a preferred embodiment of the present invention, and those skilled in the art may make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be regarded as within the protection scope of the present invention.

Claims

1. A grain boundary phase-containing samarium-iron-based rare earth permanent magnet material, The chemical formula is Sm ａ Fe ｂ Co ｃ Ti ｄ B ｅ Formula I and (In formula I, 0.5≦a≦1.5, 7.5≦b≦9.0, 2.0≦c≦3.0, 0.5≦d≦1.5, 0.1≦e≦0.

25. the grain boundary phase-containing samarium-iron-based rare earth permanent magnet material comprises a samarium-iron-based main phase, a grain boundary phase, and an α-Fe phase; a non-magnetic element Ti is segregated and distributed in the grain boundary phase, the grain boundary phase envelops the surface of the samarium-iron-based main phase, the samarium-iron-based main phase has a crystal grain size of 20 nm to 500 nm; The grain boundary phase-containing samarium-iron-based rare earth permanent magnet material has a thickness of 1 nm to 50 nm.

2. A method for producing the grain boundary phase-containing samarium-iron-based rare earth permanent magnet material according to claim 1, comprising the steps of: After blending the raw material alloys, they are melted and cast to obtain a master alloy; and rapidly solidifying and melt-spinning the master alloy to obtain a grain boundary phase-containing samarium-iron-based rare earth permanent magnet material.

3. 3. The method according to claim 2, wherein the output of the melting is 14 kW to 19 kW.

4. 3. The method according to claim 2, wherein the power of the casting is between 5 kW and 9 kW.

5. 3. The method according to claim 2, wherein the nozzle diameter of the quartz tube during the rapid solidification and melt spinning is 1 mm to 4 mm, and the distance from the nozzle of the quartz tube to the copper roll is 1 mm to 4 mm.

6. The method according to claim 2, characterized in that the melt temperature during the rapid solidification and melt spinning is 1000°C to 1700°C, the pressure difference between the gas storage tank and the chamber is 0.02MPa to 0.06MPa, and the rapid solidification speed is 5m / s to 50m / s.

7. A magnetic device comprising the grain boundary phase-containing samarium iron-based rare earth permanent magnet material according to claim 1.

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