Method for producing alloy of rare earth element and transition metal, and, method for reducing oxide of rare earth element

Abstract

To provide a method for producing an alloy of rare earth element and transition metal capable of obtaining alloys of the rare earth element and transition metal, while performing reduction of oxide of the rare earth elements.SOLUTION: The method for producing an alloy of rare earth elements and transition metals disclosed herein is a method for producing an alloy of rare earth elements and transition metals using an oxide of a rare earth element as a raw material, and includes a step of performing a reduction reaction and an alloy reaction by heating a pellet containing the oxide of the rare earth element and the transition metal in the plasma of a reducing metal to a temperature above the alloy eutectic point by induction heating using a high frequency of 1 MHz to 100 MHz.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing alloys of rare earth elements and transition metals, and a method for reducing oxides of rare earth elements. [Background technology]

[0002] Generally, molten salt electrolysis and metallothermal reduction are known as methods for reducing rare earth element oxides (see Non-Patent Document 1). Because the rare earth chloride salts used in molten salt electrolysis are highly hygroscopic, metallothermal reduction is often used to avoid this hygroscopicity. For example, in metallothermal reduction, Dy2O3 is fluorinated with NH4HF2 at around 450°C, and then dysprosium fluoride is reduced with calcium metal at 1400°C to obtain dysprosium metal.

[0003] The reaction formula is as follows: Fluorination (reaction temperature: 450°C) Dy2O3+4NH4HF2→ 2DyF3+ 2NH4F + 2NH3+ 3H2O Reduction (reaction temperature: 1450°C) 2DyF3 + 3Ca → 2Dy + 3CaF2 [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Hang Liu, et. al., “Research Progress in Preparation and Purification of Rare Earth Metal,” Metals, 10(10), 1376; doi:10.3390 / met10101376 Summary of the Invention [Problem to be solved by the invention]

[0005] Because the molten salt electrolysis method uses a corrosive electrolyte, and the metal thermal reduction method uses fluorine and is a high-temperature reaction at 1450°C, costs must be incurred for safety and environmental measures. Furthermore, when reducing dysprosium oxide to obtain dysprosium metal using the metallothermal reduction method, a high-temperature reaction using fluorine is required, followed by a subsequent reaction using Ca metal, so measures to prevent equipment deterioration are necessary. Three processes are also required: the reduction process (two reaction processes) and the alloying process. This is one of the reasons why the market price of dysprosium metal is high.

[0006] Rare earth elements are rarely used alone, but are used as additives to improve material strength and magnetic properties, and are often added in amounts of 1 to 10 mol% or less.

[0007] The present disclosure has been made in consideration of the above circumstances, and relates to a technology for reducing oxides of rare earth elements using microwave-excited plasma. It provides a method for producing an alloy of rare earth elements and transition metals that can obtain an alloy of rare earth elements and transition metals while reducing oxides of rare earth elements, and a method for reducing oxides of rare earth elements. [Means for solving the problem]

[0008] To solve the above problems, the present disclosure provides the following means.

[0009] A first aspect of the present disclosure is a method for producing an alloy of a rare earth element and a transition metal using an oxide of a rare earth element as a raw material, the method comprising the steps of heating a pellet containing an oxide of a rare earth element and a transition metal in a plasma of a reducing metal to a temperature equal to or higher than the alloy eutectic point temperature by induction heating using a high frequency of 1 MHz to 100 MHz, thereby carrying out a reduction reaction and an alloy reaction.

[0010] A second aspect of the present disclosure is the method for producing an alloy of a rare earth element and a transition metal according to the first aspect, wherein the eutectic temperature is 800° C. or higher.

[0011] A third aspect of the present disclosure relates to the method for producing an alloy of a rare earth element and a transition metal according to the first or second aspect, wherein the reducing agent metal and the pellet are disposed at a distance from each other in a reaction chamber, a microwave of 1 GHz or more is irradiated onto the reducing agent metal using a cavity resonator to form the plasma, and an induction coil is used to perform the induction heating.

[0012] A fourth aspect of the present disclosure is a method for producing an alloy of a rare earth element and a transition metal according to any one of the first to third aspects, wherein the rare earth element is at least one selected from scandium, yttrium, and 17 elements, a total of 15 elements ranging from lanthanum (atomic number 57) to lutetium (atomic number 71), and the transition metal is at least one selected from the group consisting of Fe, Cu, Co, Ni, and Mn.

[0013] A fifth aspect of the present disclosure relates to the method for producing an alloy of a rare earth element and a transition metal according to the fourth aspect, wherein the rare earth element is either Dy or Tb, and the transition metal is either Fe or Cu.

[0014] A sixth aspect of the present disclosure is the method for producing an alloy of a rare earth element and a transition metal according to any one of the first to fifth aspects, wherein the reducing metal is at least one selected from Mg and Ca.

[0015] A seventh aspect of the present disclosure is a method for producing an alloy of a rare earth element and a transition metal according to any one of the first to sixth aspects, wherein the step is carried out at a temperature of 900°C to 1000°C.

[0016] An eighth aspect of the present disclosure is a method for producing an alloy of a rare earth element and a transition metal according to any one of the first to seventh aspects, wherein the steps are carried out for 60 minutes or more.

[0017] A ninth aspect of the present disclosure is a method for reducing oxides of rare earth elements, which includes a step of heating a pellet containing an oxide of a rare earth element and a transition metal in a plasma of a reducing metal to 800°C or higher by induction heating using a high frequency of 1 MHz to 100 MHz, thereby carrying out a reduction reaction and an alloy reaction.

[0018] A tenth aspect of the present disclosure relates to the method for reducing oxides of rare earth elements of the ninth aspect, wherein the reducing metal and the pellet are disposed apart from each other in a reaction chamber, a microwave of 1 GHz or more is irradiated onto the reducing metal using a cavity resonator to form the plasma, and an induction coil is used to perform the induction heating.

[0019] An eleventh aspect of the present disclosure is the method for reducing oxides of rare earth elements according to the ninth or tenth aspect, wherein the plasma is a plasma of a reducing metal alone or a mixed plasma of a reducing metal and an inert gas. [Effects of the Invention]

[0020] According to the method for producing an alloy of a rare earth element and a transition metal disclosed herein, it is possible to provide a method for producing an alloy of a rare earth element and a transition metal, which can obtain an alloy of a rare earth element and a transition metal while reducing an oxide of a rare earth element. [Brief explanation of the drawings]

[0021] [Figure 1A] FIG. 1 is a schematic diagram showing an example of a reaction apparatus that can be used when carrying out the method for producing an alloy of a rare earth element and a transition metal according to the present disclosure. [Figure 1B] FIG. 1 is a schematic diagram showing another example of a reaction apparatus that can be used when carrying out the method for producing an alloy of a rare earth element and a transition metal according to the present disclosure. [Figure 2A] 1 shows an XRD pattern obtained by X-ray diffraction for the sample of Example 1 before the reaction. [Figure 2B] 1 shows an XRD pattern obtained by X-ray diffraction for the sample of Example 1 after the reaction. [Figure 3A]1 shows the results of SEM observation of the sample of Example 1. [Figure 3B] 1 is an elemental mapping image of oxygen (O) obtained by EDX observation of the sample of Example 1. [Figure 3C] 1 is an elemental mapping image of iron (Fe) obtained by EDX observation of the sample of Example 1. [Figure 3D] 1 is an element mapping image of dysprosium (Dy) obtained by EDX observation of the sample of Example 1. [Figure 4] The magnetic properties of the prepared samples were measured. [Figure 5A] 1 shows an XRD pattern obtained by X-ray diffraction for the sample of Example 2 before the reaction. [Figure 5B] 1 shows an XRD pattern obtained by X-ray diffraction for the sample of Example 2 after the reaction. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present disclosure will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for convenience in order to make the features easier to understand, and the dimensional ratios of each component may differ from the actual ones. The dimensions and the like exemplified in the following description are merely examples, and the present disclosure is not limited thereto. Appropriate changes can be made within the scope of the effects of the present disclosure. Hereinafter, even if not specifically explained, the configuration described in one embodiment may be applied to other embodiments.

[0023] (Method for producing alloys of rare earth elements and transition metals) The method for producing an alloy of a rare earth element and a transition metal disclosed herein is a method for producing an alloy of a rare earth element and a transition metal using an oxide of a rare earth element as a raw material, and includes a step of heating a pellet containing an oxide of a rare earth element and a transition metal in a plasma of a reducing metal to a temperature equal to or higher than the alloy eutectic point temperature by induction heating using a high frequency of 1 MHz to 100 MHz, thereby causing a reduction reaction and an alloy reaction.

[0024] FIG. 1A is a schematic diagram showing an example of a reaction apparatus that can be used to carry out the method for producing an alloy of a rare earth element and a transition metal according to the present disclosure. 1A includes a reaction chamber 10 that can be evacuated to a vacuum and in which a reducing agent metal R, which is a plasma source, and a pellet P containing an oxide of a rare earth element and a transition metal can be disposed at a distance, a cavity resonator (microwave resonator) 20 for generating microwaves to be irradiated to the reducing agent metal R to form plasma, and an induction coil 30 for inductively heating the pellet P. Reference numeral 12 denotes a radiation thermometer.

[0025] A known vacuum vessel can be used as the reaction chamber 10. For example, a quartz tube can be used in a laboratory, and a stainless steel vacuum vessel can be used for industrial use. The reaction chamber 10 is evacuated to about 0.7 Pa by a rotary pump 11, for example.

[0026] The cavity resonator 20 is connected to a known microwave power supply 21. The microwave power supply 21 may be configured, for example, with an oscillator, an isolator, a power meter, a stub tuner (microwave matching device), etc. The oscillator is connected to the cavity resonator 20 via the power meter, the stub tuner, etc. The microwaves oscillated from the oscillator preferably have a frequency of 1 GHz or higher. The microwave power from the oscillator is, for example, 2.45 GHz and about 100 W.

[0027] The electromagnetic field of microwaves generated from microwave power supply 21 is amplified by cavity resonator 20, and the amplified microwaves are irradiated onto the reducing agent metal, which is then heated by induction heating, generating plasma. For example, when the microwave power is 2.45 GHz and about 100 W and the reducing agent metal R is magnesium (Mg) metal, the magnesium metal reaches 660°C or higher in about 10 to 20 minutes after power is applied, generating magnesium plasma.

[0028] The plasma may be a plasma of only a reducing metal, or a mixed plasma of a reducing metal and an inert gas such as He or Ar.

[0029] The induction coil 30 is connected to a known radio frequency (RF) power supply 31. The radio frequency power supply 31 is preferably connected to the induction coil 30 via a matching box in order to efficiently transmit a radio frequency signal.

[0030] The high frequency power supply 31 is a power supply capable of using a high frequency signal of 1 MHz to 100 MHz. Pellets P containing oxides of rare earth elements and transition metals cannot be heated by induction heating at a frequency of a few kHz because the oxides are mixed together, and induction heating at 1 MHz or higher is required to sufficiently raise the temperature of the pellets P in a reasonable amount of time. On the other hand, ions of reducing metals (for example, Mg and Ca) do not move in an electric or magnetic field exceeding 100 MHz in a vacuum, and as a result, the reduction reaction does not proceed sufficiently.

[0031] 1B is a schematic diagram showing another example of a reactor that can be used when carrying out the method for producing an alloy of a rare earth element and a transition metal according to the present disclosure. The reactor shown in FIG. 1B is configured to allow transition metal plasma to be introduced from multiple locations (two locations in the example of FIG. 1B). In FIG. 1B, components with the same reference numerals as those in FIG. 1A are the same components, and their description will be omitted. 1B includes two cavity resonators (microwave resonators) (20A, 20B) for generating microwaves to be irradiated to form plasma on the reducing agent metal R, and reducing agent metals R1 and R2, which are plasma sources, can be placed in the cavity resonators 20A and 20B, respectively. The cavity resonators 20A and 20B are connected to a known microwave power supply 21.

[0032] 1B includes two cavity resonators, but may include three or more cavity resonators. In this case, a reducing agent metal serving as a plasma source can be disposed in each of the three or more cavity resonators.

[0033] 1B, two pellets (designated P1 and P2) containing an oxide of a rare earth element and a transition metal can be placed close to each of the cavity resonators 20A and 20B in the reaction chamber 10. In this case, by making the environments of the pellets P1 and P2 similar (such as the distance from the cavity resonators), it is possible to obtain similar alloys of rare earth elements and transition metals. When the reactor has three or more resonant cavities, the reaction can proceed simultaneously for three or more pellets accordingly.

[0034] A specific example of the method for producing an alloy of a rare earth element and a transition metal according to the present disclosure will be described step by step.

[0035] <Pellet preparation process> The pellet preparation step is a step of applying pressure to a mixture containing an oxide of a rare earth element and a transition metal in a pellet molding machine to produce pellets (compressed powder). There is no particular limitation on the shape of the rare earth element oxide and transition metal as raw materials, and both may be in any shape such as powder, granules (including spheres and distorted spheres), rectangular parallelepiped, or thin flakes. However, in consideration of ease of mixing, powder or granular (particulate) form is preferred. Furthermore, when the oxide of the rare earth element and the transition metal are in powder or granular (particulate) form, the size (diameter) can be set to, for example, about 10 μm to 100 μm so that a more uniformly dispersed pellet (compact powder) can be easily obtained. When producing Fe-Dy2O3 pellets, Cu-Dy2O3 pellets, Fe-Tb2O3 pellets, or Cu-Tb2O3 pellets, for example, the Fe particles and Cu particles can be about 70 μm, and the Dy2O3 particles and Tb2O3 particles can be about 40 μm.

[0036] The mixing ratio (molar ratio) of the oxide of the rare earth element to the transition metal is, for example, 1:20 to 1:5. When producing Fe-Dy2O3 pellets, Cu-Dy2O3 pellets, Fe-Tb2O3 pellets, or Cu-Tb2O3 pellets, the molar ratio of Fe:Dy2O3, Cu:Dy2O3, Fe:Tb2O3, or Cu:Tb2O3 can be, for example, 1:10.

[0037] The rare earth elements that make up the oxides of rare earth elements that make up the pellets refer to all 17 elements in total: scandium (Sc) with atomic number 21, yttrium (Y) with atomic number 29, and the 15 elements (lanthanoids) from lanthanum (La) with atomic number 57 to lutetium (Lu) with atomic number 71. The oxides of rare earth elements that make up the pellets contain at least one of these 17 elements. For example, the oxide of dysprosium (Dy), which has atomic number 66, is Dy2O3, and the oxide of terbium (Tb), which has atomic number 65, is Tb2O3.

[0038] The transition metals constituting the pellets include at least one selected from the group consisting of iron (Fe), copper (Cu), cobalt (Co), nickel (Ni), and manganese (Mn). The melting points of Fe are 1538°C, Cu is 1085°C, Co is 1495°C, Ni is 1455°C, and Mn is 1246°C, but according to the alloy manufacturing method of the present invention, alloys of rare earth elements and transition metals can be formed at temperatures lower than their melting points. The disclosed method for producing an alloy of rare earth elements and transition metals significantly reduces the process temperature and reaction time, achieving an energy saving process of more than 70% even by simple calculation.

[0039] <Reducing agent metal and pellet placement process> The reducing agent metal and pellet placement step is a step of placing the reducing agent metal and pellets in the reactor. The reducing agent metal and the pellets are preferably spaced apart within the reactor. This is because induction heating of the reducing agent metal, which is the plasma generation source, is performed using microwaves (MW) of 1 GHz or more, while induction heating of the raw material pellets is performed using radio frequency (RF) waves of 1 MHz to 100 MHz, so each uses a different mechanism. Specifically, the reducing agent metal is induction heated in a cavity resonator (microwave resonator), and the pellet is induction heated in an induction coil. Therefore, it is preferable to place the reducing agent metal at the center of the cavity resonator and the pellet at the center of the induction coil. In the disclosed method for producing an alloy of rare earth elements and transition metals, the plasma is excited by microwaves, and the reduction and alloying reactions are carried out by RF waves using an induction coil.

[0040] The reducing agent metal is preferably magnesium (Mg) or calcium (Ca). The magnesium or calcium is not limited to pure metal magnesium or calcium, but alloys that are compounds containing magnesium or calcium, or other metal magnesium or calcium containing impurities can also be used. The reducing metal can be, for example, in the form of a rod or a plate, and the metal plasma is generated directly from the metal rod or plate.

[0041] <Reaction process> The reaction process involves applying microwave (MW) power to the cavity resonator to generate plasma of the reducing metal, and applying radio frequency (RF) power to the induction coil to heat the pellets, thereby promoting reduction and alloying reactions. By carrying out the reaction step, an intermetallic compound containing an alloy of a rare earth element and a transition metal is obtained. As the reaction step proceeds, the proportion of the alloy phase of the rare earth element and the transition metal increases.

[0042] The induction heating of the reducing agent metal is performed using microwaves (MW) of 1 GHz or more. The MW power input at this time is, for example, 100 W or more, for example, 100 W to 300 W. When the reducing agent metal is magnesium metal, the heating temperature is set to, for example, 660° C. or higher. When the reducing agent metal is calcium metal, the heating temperature is set to, for example, 660° C. or higher. When the reducing agent metal is magnesium metal and induction heating is performed at 2.45 GHz and about 100 W, the magnesium metal reaches a temperature of 660°C or higher in about 10 to 20 minutes.

[0043] The induction heating of the pellets is performed at a high frequency of 1 MHz to 100 MHz. The RF power input at this time is, for example, about 200 W. For example, it is 100 W to 300 W. The induction heating temperature of the pellets is set to be equal to or higher than the eutectic temperature of the alloy to be produced. For example, it is set to 800°C or higher. Alternatively, it is set to 800°C to 1000°C, or 900°C to 1000°C. Therefore, the reaction temperature can be determined by referring to the phase diagram of the target product. When the pellet is a compact of dysprosium oxide and iron powder (Fe-Dy2O3), the heating temperature is set to, for example, about 890°C. When the pellet is a compact of dysprosium oxide and copper powder (Cu-Dy2O3), the heating temperature is set to, for example, about 955°C. When the pellet is a compact of terbium oxide and iron powder (Fe-Tb2O3), the heating temperature is set to, for example, about 1100°C. When the pellet is a compact of terbium oxide and copper powder (Cu-Tb2O3), the heating temperature is set to, for example, about 900°C. If the pellet is a compact of dysprosium oxide and iron powder (Fe-Dy2O3) and induction heating is performed at 13.56 GHz and approximately 200 W, the pellet will reach approximately 800°C in about 10 to 20 minutes.

[0044] The reaction step is carried out for, for example, 10 minutes or more, and may be carried out for 60 minutes or more. The longer the reaction time, the greater the proportion of the alloy phase of rare earth elements and transition metals. The reaction time may be, for example, about 10 hours.

[0045] <Cooling process> After the MW power and RF power are turned off and the reaction process is completed, the material is left as is or cooled by air cooling, and then exposed to the atmosphere to remove the pellet (an intermetallic compound containing an alloy of rare earth elements and transition metals).

[0046] (Method for reducing oxides of rare earth elements) The method for reducing rare earth element oxides disclosed herein includes a step of heating a pellet containing a rare earth element oxide and a transition metal in a plasma of a reducing metal to 800°C or higher by induction heating using a high frequency of 1 MHz to 100 MHz, thereby causing a reduction reaction and an alloy reaction.

[0047] In the method for reducing oxides of rare earth elements according to the present disclosure, the above-described pellet preparation step, reducing agent metal and pellet arrangement step, reaction step, and cooling step can be applied. [Example]

[0048] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to the examples shown below.

[0049] Example 1 Example 1 is an example in which an FeDy alloy was produced from dysprosium oxide (Dy2O3) and iron (Fe) using a reaction apparatus having the configuration shown in FIG. 1A.

[0050] The preparation of the specimen (sample) of Example 1 and the measurement results of the obtained sample will be described below. (1) Preparation of pellets Iron particles of approximately 70 μm (iron powder, 200 mesh, manufactured by Taiho Trading Co., Ltd.) and dysprosium oxide particles of approximately 40 μm (dysprosium oxide powder, 400 mesh, manufactured by Fujifilm Wako Pure Chemical Corporation) were mixed in a mortar at a molar ratio of 1:10. 1 g of the mixed powder was taken out and left in a pellet molding machine at room temperature under a pressure of 30 MPa for approximately 1 hour to form a pellet. (2) Arrangement of reducing agent metal and pellets A magnesium metal with a diameter of 8 mm and a length of 50 mm was placed in a microwave resonator inside the quartz tube, and the pellet prepared in (1) was placed in the center of the induction coil. The inside of the quartz tube was then evacuated to approximately 0.7 Pa using a rotary pump. (3) Reduction and alloy formation (reaction process) A microwave of 2.45 GHz and 100 W of power was applied to the microwave resonator, and a high frequency of 13.56 MHz and 200 W of power was applied to the induction coil. In about 10 to 20 minutes, the magnesium metal in the microwave resonator reached over 660°C, generating magnesium plasma, and the pellet reached approximately 900°C. Once the pellet reached 900°C, the reaction continued for one hour. (4) Cooling After the reaction, the MW power and RF power were turned off, and after cooling, the system was opened to the atmosphere and the pellet was taken out. (5) Characteristic measurement The pellets were crushed and subjected to X-ray diffraction (XRD) and magnetic property measurements. SEM / EDX observations revealed the presence of an FeDy alloy phase.

[0051] 2A and 2B show the XRD patterns obtained by X-ray diffraction for the prepared sample before the reaction and the XRD patterns after the reaction, respectively.

[0052] It can be seen that a peak appears near 2θ=40° in the XRD pattern after the reaction in FIG. 2B, which was not present in the XRD pattern before the reaction in FIG. 2A. The content ratio of each phase was analyzed using the Relative Intensity Ratio Method based on the inorganic material database (AtomWork) constructed by the National Institute for Materials Science, etc., and the results showed that the content ratio of each phase was DyFe2 or Dy6Fe 26 It was found that the alloy phase close to the above was contained at 13 mass%.

[0053] FIG. 3 shows the results of SEM / EDX observation of the prepared sample. FIG. 3A is an SEM image of the sample, FIG. 3B is an elemental mapping image (EDX image) of oxygen (O), FIG. 3C is an elemental mapping image of iron (Fe), and FIG. 3D is an elemental mapping image of dysprosium (Dy).

[0054] In the region enclosed by a square in the SEM image shown in FIG. 3A, the content of each element was 50.9 mass % for iron (Fe), 5.4 mass % for dysprosium (Dy), and 18.0 mass % for oxygen (O).

[0055] FIG. 4 shows the results of measuring the magnetic properties of the prepared samples. In Figure 4, it can be seen that the magnetization decreases once and then increases again. It can be inferred that decomposition of the material occurs at this temperature. From the inflection point of the magnetic properties, the prepared samples were either DyFe2 or Dy6Fe 26 Although the alloy phase is close to that of DyFe2, a Curie temperature of 650K (literature value) close to that of DyFe2 can be observed. Furthermore, this result indicates that reduction by Mg plasma was successful.

[0056] Measurement of the properties of the sample obtained in Example 1 revealed that a DyFe2 phase was obtained.

[0057] Example 2 Example 2 is an example in which a CuDy alloy was produced from dysprosium oxide (Dy2O3) and copper (Cu) using a reaction apparatus having the configuration shown in FIG. 1A.

[0058] The specimen (sample) of Example 2 was prepared under the same conditions as those of Example 1.

[0059] Figures 5A and 5B show the X-ray diffraction patterns of the prepared samples before the reaction. The XRD pattern and the XRD pattern after the reaction are shown.

[0060] In the XRD pattern after the reaction in Figure 5B, a DyCu phase peak appears on the low-angle side, close enough to overlap with the Dy2O3 phase peak around 2θ = 30°. As a result, the Dy2O3 phase peak in the XRD pattern before the reaction in Figure 5A appears to be shifted to the low-angle side. The content of each phase was analyzed using the Relative Intensity Ratio Method, which is based on the inorganic materials database (AtomWork) constructed by the National Institute for Materials Science and other organizations. As a result, it was found that the DyCu phase was contained at 14 mass%. [Explanation of symbols]

[0061] 10 Reaction chamber 20 Cavity resonator (microwave resonator) 30 induction coil 100 Reactor

Claims

1. A method for producing an alloy of a rare earth element and a transition metal using an oxide of a rare earth element as a raw material, comprising: A method for producing an alloy of a rare earth element and a transition metal, comprising the step of heating a pellet containing an oxide of a rare earth element and a transition metal in a plasma of a reducing metal by induction heating using a high frequency of 1 MHz to 100 MHz to a temperature equal to or higher than the eutectic point temperature of the alloy, thereby causing a reduction reaction and an alloy reaction.

2. 2. The method for producing an alloy of a rare earth element and a transition metal according to claim 1, wherein the eutectic temperature is 800°C or higher.

3. 2. The method for producing an alloy of a rare earth element and a transition metal according to claim 1, wherein the reducing agent metal and the pellet are arranged at a distance from each other in a reaction chamber, the reducing agent metal is irradiated with microwaves of 1 GHz or more using a cavity resonator to form the plasma, and the induction heating is performed using an induction coil.

4. 2. The method for producing an alloy of rare earth element and transition metal according to claim 1, wherein the rare earth element is at least one selected from the group consisting of scandium, yttrium, and 17 elements, which is a total of 15 elements from lanthanum having atomic number 57 to lutetium having atomic number 71, and the transition metal is at least one selected from the group consisting of Fe, Cu, Co, Ni, and Mn.

5. 5. The method for producing an alloy of a rare earth element and a transition metal according to claim 4, wherein the rare earth element is either Dy or Tb, and the transition metal is either Fe or Cu.

6. 2. The method for producing an alloy of a rare earth element and a transition metal according to claim 1, wherein the reducing metal is at least one selected from the group consisting of Mg and Ca.

7. 2. The method for producing an alloy of rare earth elements and transition metals according to claim 1, wherein the step is carried out at a temperature of 900°C to 1000°C.

8. 2. The method for producing an alloy of a rare earth element and a transition metal according to claim 1, wherein the step is carried out for 60 minutes or more.

9. 1. A method for reducing an oxide of a rare earth element, comprising: A method for reducing a rare earth element oxide, comprising the step of heating a pellet containing a rare earth element oxide and a transition metal to 800°C or higher in a plasma of a reducing agent metal by induction heating using a high frequency of 1 MHz to 100 MHz, thereby carrying out a reduction reaction and an alloying reaction.

10. 10. The method for reducing rare earth element oxides according to claim 9, wherein the reducing metal and the pellet are placed apart from each other in a reaction chamber, the reducing metal is irradiated with microwaves of 1 GHz or more using a cavity resonator to form the plasma, and the induction heating is performed using an induction coil.

11. 10. The method for reducing oxides of rare earth elements according to claim 9, wherein the plasma is a plasma of a reducing metal only, or a mixed plasma of a reducing metal and an inert gas.

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