Manufacturing method of scandium alloy

Abstract

To provide a method for manufacturing a scandium-containing alloy containing at least one metal selected from aluminum or magnesium, by reducing a scandium compound containing at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, in a way that is inexpensive, safe, environmentally friendly, and energy-efficient.SOLUTION: A method according to the present disclosure for manufacturing a scandium-containing alloy includes: a preparation step of preparing a composite powder including a scandium compound powder comprising at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, and a metal powder comprising at least one of aluminum and magnesium, or both aluminum and magnesium; and a heating step of heating the composite powder at 500°C or higher in a vacuum atmosphere or an inert gas atmosphere.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to Scandium alloy a manufacturing method, for example, a technique for manufacturing an aluminum-scandium alloy, a magnesium-scandium alloy or an aluminum magnesium scandium alloy at low cost and with even lower energy.

Background Art

[0002] Regarding scandium, an alloy obtained by adding a trace amount of scandium to aluminum, which is lightweight and has higher strength than duralumin, was used for military applications such as the Soviet Union's MIG29 during the Cold War. In addition, scandium alloys are being widely used as lightweight and high-strength structural materials for civilian use, such as the frames of high-end bicycles. Scandium alloys have far better mechanical properties and weldability than duralumin and have high industrial utility value.

[0003] In addition, scandium has attracted attention as a new proton conductor additive in a solid oxide fuel cell (SOFC) that generates electricity from natural gas, and it is expected that inexpensive electricity can be obtained using the solid oxide fuel cell.

[0004] Scandium is a main component of a gadolinium scandium gallium garnet (GSGG) laser crystal, which has an energy intensity more than three times that of yttrium aluminum garnet (YAG), a common laser material. In addition, scandium is used for studio lighting in photography, movies, and television stations because it can obtain a wide emission spectrum close to sunlight.

[0005] Furthermore, composite nitride thin films in which scandium is dissolved in aluminum nitride have been found to exhibit more than five times the piezoelectricity of aluminum nitride, and the highest value among nitrides. This allows for improved piezoelectric performance and heat resistance in line with the evolution of communication methods such as 5G, and is therefore being used as BAW high-frequency filters for mobile communications. Moreover, composite nitride thin films in which scandium is dissolved in aluminum nitride have the performance of piezoelectric elements in which the crystal structure does not change even when heated up to 500°C, and are therefore expected to be used as high-temperature pressure sensors that do not contain harmful elements such as lead (PZT).

[0006] Therefore, scandium is being commercialized for applications such as radio wave filters for ultra-high-speed 5G communication, control piezoelectric sensors for ultra-low-emission turbines, high-performance ultrasonic sensors that support autonomous driving, ultrasonic probes for medical devices, and MEMS (Micro Electro Mechanical Systems) applications, with scandium being the key material in these applications.

[0007] However, although scandium oxide is found worldwide, the refining process to convert scandium oxide into metallic scandium is environmentally damaging, energy-intensive, and raises safety concerns. Furthermore, this refining is only carried out in a few countries, such as China. As a result, metallic scandium is extremely expensive, and its use is limited.

[0008] The method for producing metallic scandium involves fluorinating scandium oxide, a thermodynamically very stable raw material, to obtain scandium fluoride, which is easily reduced. This reduction is carried out at a high temperature of 1600°C using metallic calcium as a reducing agent (see, for example, Non-Patent Document 1). The fluorination process has a significant environmental impact. Furthermore, the use of metallic calcium raises safety concerns. Additionally, the high temperature of 1600°C results in a high energy burden, limiting production to specific countries and driving up prices.

[0009] Scandium oxide is a thermodynamically very stable oxide and cannot be reduced in its original form. Therefore, it is usually reduced according to (Chemical Formula 1) and (Chemical Formula 2). (Chemical formula 1)Sc2O3+ 6NH4HF2→ 2ScF3+ 6NH4F + 3H2O (Chemical 2)2ScF3+ 3Ca → 2Sc + 3CaF2 There is a disclosure of a technology that develops upon this technology (see, for example, Patent Document 1). In Patent Document 1, scandium oxide and scandium fluoride are placed in a sealed container along with aluminum and magnesium, and furthermore, metallic calcium is heated to 1000°C in the sealed container to generate steam. This metallic calcium reduction steam reduces scandium oxide and scandium fluoride, achieving alloying with aluminum and magnesium.

[0010] Another method involves creating pellets by mixing aluminum and scandium oxide, and then adding them to molten aluminum or magnesium to form an alloy (see, for example, Patent Document 2). The technology described in Patent Document 2 involves mixing light metals such as aluminum with rare earth oxides such as scandium oxide to form pellets. Furthermore, aluminum or magnesium is melted, and the pellets are added to the molten metal to cause a reduction reaction.

[0011] Furthermore, there is a technique to create an AlSc alloy enriched portion by thermally reducing aluminum and scandium halide at 800°C to 1000°C using metal reducing agents such as Li, Ca, and Mg, and adding lithium fluoride or calcium chloride as a flux, and then slowly cooling the resulting melt. This results in a scandium concentration of 7% by weight or more, and the enriched portion is then machined off and used (see, for example, Patent Document 3).

[0012] Furthermore, there is a technique for producing AlSc alloys by heating scandium fluoride, aluminum fluoride, sodium fluoride, and scandium oxide to 1000°C and performing molten salt electrolysis (see, for example, Patent Document 4).

[0013] Furthermore, in molten salt electrolysis, there is a method for efficiently performing alloying by reducing rare earth oxides or fluorides in molten aluminum (see, for example, Patent Document 5).

[0014] Furthermore, a method for producing AlSc alloy has been described in which a reducing agent, such as calcium or magnesium, is added to a container containing scandium oxide and aluminum, and the ceramics are heated with microwaves to vaporize the reducing agent and reduce the scandium oxide (see, for example, Patent Document 6). This method shows a reduction rate of 69.8% at a low temperature of 660°C. (See Non-Patent Document 2.)

[0015] Furthermore, while the scandium oxide reduction using microwaves is similar to that described in Patent Document 6, a technique has been provided to improve productivity by separating the microwaves used to heat the reducing metal into plasma and the microwaves used to heat the alloying components such as scandium oxide and aluminum, thereby enabling high efficiency (see, for example, Patent Document 7). [Prior art documents] [Patent Documents]

[0016] [Patent Document 1] Japanese Patent Publication No. 2007-254822 [Patent Document 2] Japanese Patent Application Publication No. 4-235231 [Patent Document 3] Japanese Patent Publication No. 2003-171724 [Patent Document 4] Special Publication No. 2021-515851 [Patent Document 5] Japanese Patent Application Publication No. 6-172887 [Patent Document 6] Japanese Patent Publication No. 2018-178180 [Patent Document 7] Japanese Patent Publication No. 2023-112725 [Non-patent literature]

[0017] [Non-Patent Document 1] Resource Processing Technology: Recovery of Rare Metals - Scandium, Vol. 39, No. 4, 1992, pp. 161-164 [Non-Patent Document 2] S. Fujii, E. Suzuki, N. Inazu, S. Tsubaki, J. Fukushima, H. Takizawa, and Y. Wada, “Micro-wave Irradiation Process for Al Sc Alloy Production,” Scientific Reports, Vol. 10, pp. 2689, February 14, 2020

Summary of the Invention

Problems to be Solved by the Invention

[0018] However, in the technology described in Patent Document 1, it is necessary to raise the temperature to 1000°C to produce metallic calcium vapor, and furthermore, it is necessary to use a pressure-resistant container. Although the reduction of scandium oxide and scandium fluoride has been achieved, due to the use of high temperature, high energy is required, and due to the use of a pressure-resistant container, there are also problems in terms of safety. In addition, the produced alloy also contains calcium as a reducing agent, and the process for removing it increases, so the process is complicated.

[0019] In addition, in the technology described in Patent Document 2, it is necessary to make the ratio of aluminum to scandium oxide greater than about 30. Furthermore, there is a problem that the yield is reduced due to oxidation from the molten atmosphere.

[0020] In addition, in the technology described in Patent Document 3, the temperature is also high, fluxes and metal reducing agents are mixed in, it is difficult to remove them, and furthermore, even if it is concentrated and the site is taken out, it takes a lot of man-hours and the yield is low.

[0021] In addition, in the technology described in Patent Document 4, there are problems in terms of safety because a molten salt using fluoride is made. Furthermore, since electrolysis is carried out at a high temperature of 1000°C, a lot of energy is required. Naturally, the mixing of impurities cannot be avoided and it is difficult to achieve high purity.

[0022] Furthermore, the technology described in Patent Document 5 is a method for obtaining AlSc alloys with high efficiency by performing the process at temperatures between 700°C and 1000°C, which are above the melting point of aluminum. However, because it involves molten salt electrolysis, it has drawbacks in terms of safety and energy efficiency. Moreover, in the molten salt electrolysis, rare earth oxides or fluorides are reduced in aluminum to form the alloy. Graphite and iron are given as examples for the cathode, but since iron reacts with aluminum to form impurities, graphite is mainly used. Therefore, because gases such as carbon tetrafluoride, carbon monoxide, and carbon dioxide are generated on the anode surface during electrolysis, it is recommended to provide a vent. In this method, aluminum is melted at 850°C and electrodeposited by passing a 50A current through a graphite electrode. The example shown is a yttrium-aluminum alloy, but the generation of harmful gases is unavoidable, and electrodeposition takes time, so the required energy tends to be high.

[0023] Furthermore, while the technology described in Patent Document 6 is a very simple and effective reduction method, the inclusion of reducing metals makes high-purity processing time-consuming. Moreover, industrially, it is necessary to improve the reduction rate, and a decrease in the reduction rate leads to increased costs. In addition, because microwaves are used, there are often constraints on the size and shape of the container, making mass production difficult.

[0024] Furthermore, the method described in Patent Document 7 is considered to improve productivity and contribute to cost reduction compared to the method in Patent Document 6. However, while this may be acceptable for quantities of a few kilograms, producing quantities on the order of hundreds of kilograms or tons would require large-scale equipment, potentially increasing the cost of AlSc alloy.

[0025] The purpose of this disclosure is to reduce scandium compounds, which include at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, in an inexpensive, safe, environmentally friendly, and energy-efficient manner, and which contain at least one of the metals aluminum or magnesium. Scandium alloy The objective is to provide a method for manufacturing [the product]. [Means for solving the problem]

[0026] In order to solve the above problems, the inventors have diligently studied and found a method that does not require high temperature and high pressure, uses low energy, ensures high safety by not using highly active reducing metals, and further solves the difficult problem of reducing man-hours and enabling inexpensive mass production. This method produces metallic scandium from scandium compounds containing scandium oxide, which was previously considered thermodynamically impossible, and uses aluminum and / or magnesium as the base material. Scandium alloy We have discovered a method for producing it in high purity, and have completed the present invention. That is, the present invention Scandium alloy The manufacturing method comprises: a preparation step of preparing a composite powder of a scandium compound powder, which is at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, and a metal powder which is either aluminum or magnesium, or both aluminum and magnesium (excluding cases where cryolite is included); a mechanical alloying step A of mechanically alloying the composite powder prepared in the preparation step; a molding step of putting the mechanically alloyed composite powder into a mold; a molding step of applying pressure to the composite powder to form a molded body; and a heating step of heating the molded body of the composite powder to 500°C or more and 900°C or less in a vacuum atmosphere or an inert gas atmosphere. Then, an aluminum scandium alloy, a magnesium scandium alloy, or an aluminum magnesium scandium alloy is obtained. This invention is characterized by the fact that the scandium compound powder and the metal powder come into greater contact, thereby further promoting the alloying reaction. Furthermore, the scandium compound powder and the metal powder are finely dispersed, and the scandium compound powder is dispersed within the metal powder, allowing the alloying reaction to be further promoted even at low temperatures.

[0027] According to the present invention Scandium alloyThe manufacturing method comprises: a preparation step of preparing a composite powder of a scandium compound powder, which is at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, and a metal powder which is either aluminum or magnesium, or both aluminum and magnesium (except when cryolite is included); a mechanical alloying step B in which the composite powder prepared in the preparation step further contains at least one selected from the group consisting of carboxylic acid, ascorbic acid, and higher fatty acid as an auxiliary, and the composite powder containing the auxiliary prepared in the preparation step is mechanically alloyed; a step of putting the mechanically alloyed composite powder into a mold; a molding step of applying pressure to the composite powder to form a molded body; and a heating step of heating the molded composite powder to 500°C or more and 900°C or less in a vacuum atmosphere or an inert gas atmosphere. Then, an aluminum scandium alloy, a magnesium scandium alloy, or an aluminum magnesium scandium alloy is obtained. This invention is characterized by the fact that the scandium compound powder and the metal powder come into greater contact, thereby further promoting the alloying reaction. Furthermore, it suppresses the formation of oxides on the surface of the metal powder and inhibits aggregation between scandium compound powders or between metal powders, thereby improving the contact area and further promoting the alloying reaction even at low temperatures.

[0028] According to the present invention Scandium alloy The manufacturing method comprises a preparation step of preparing a composite powder of a scandium compound powder, which is at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, and a metal powder which is either aluminum or magnesium, or both aluminum and magnesium (excluding cases where cryolite is included); a mechanical alloying step A of mechanically alloying the composite powder prepared in the preparation step; a molding step of putting the mechanically alloyed composite powder into a mold; and a heating step of heating the composite powder to 500°C or more and 900°C or less in a vacuum atmosphere or an inert gas atmosphere, wherein the heating step is a step of heating the composite powder put into the mold under pressure in a vacuum atmosphere or an inert gas atmosphere. This yields an aluminum scandium alloy, a magnesium scandium alloy, or an aluminum magnesium scandium alloy.The present invention is characterized by the fact that heating under pressure in a low-oxygen atmosphere brings the scandium compound powder and metal powder into greater contact, thereby further promoting the alloying reaction. Furthermore, the scandium compound powder and metal powder become finer, and the scandium compound powder disperses more evenly within the metal powder, allowing the alloying reaction to be further promoted even at low temperatures.

[0029] According to the present invention Scandium alloy The manufacturing method comprises a preparation step of preparing a composite powder of a scandium compound powder, which is at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, and a metal powder which is either aluminum or magnesium, or both aluminum and magnesium (except when cryolite is included); a mechanical alloying step B in which the composite powder prepared in the preparation step further contains at least one selected from the group consisting of carboxylic acid, ascorbic acid, and higher fatty acids as an auxiliary agent, and the composite powder containing the auxiliary agent prepared in the preparation step is mechanically alloyed; a molding step in which the mechanically alloyed composite powder is placed into a mold; and a heating step in which the composite powder is heated to 500°C or higher and 900°C or lower in a vacuum atmosphere or an inert gas atmosphere, wherein the heating step is a step of heating the composite powder placed in the mold under pressure in a vacuum atmosphere or an inert gas atmosphere. This yields an aluminum scandium alloy, a magnesium scandium alloy, or an aluminum magnesium scandium alloy. The present invention is characterized by the fact that heating under pressure in a low-oxygen atmosphere allows for greater contact between the scandium compound powder and the metal powder, thereby further promoting the alloying reaction. Furthermore, it suppresses the formation of oxides on the surface of the metal powder and inhibits aggregation between scandium compound powders or between metal powders, thereby improving the contact area and further promoting the alloying reaction even at low temperatures.

[0030]

[0031] According to the present invention Scandium alloyIn the manufacturing method, the particle size of the scandium compound powder is preferably 1000 μm or less. By making the particle size of the scandium compound powder finer, the alloying reaction can be further promoted.

[0032] According to the present invention Scandium alloy In the manufacturing method, the particle size of the metal powder is preferably 2000 μm or less. By making the particle size of the metal powder finer, the alloying reaction can be further promoted.

[0033] According to the present invention Scandium alloy In the manufacturing method, it is preferable that the pressure applied to the composite powder in the molding step is 5 MPa or higher. This allows for greater contact between the scandium compound powder and the metal powder, thereby further promoting the alloying reaction.

[0034] According to the present invention Scandium alloy In the manufacturing method, it is preferable that the pressure applied to the composite powder during the heating step is 5 MPa or higher. This allows for greater contact between the scandium compound powder and the metal powder, thereby further promoting the alloying reaction.

[0035] According to the present invention Scandium alloy In the manufacturing method, obtained through the heating step Scandium alloy but Aluminum scandium alloy Includes, The aluminum scandium alloy This includes forms that include at least one selected from the group consisting of aluminum scandium solid solution alloys, Al3Sc intermetallic compounds, Al2Sc intermetallic compounds, and AlSc intermetallic compounds.

[0036] According to the present invention Scandium alloy In the manufacturing method, obtained through the heating step Scandium alloy but Magnesium scandium alloy Includes, The magnesium scandium alloy This includes forms that include at least one selected from the group consisting of magnesium-scandium solid solution alloys and MgSc intermetallic compounds.

[0037] According to the present invention Scandium alloy In the manufacturing method, obtained through the heating step Scandium alloy Preferably, the process further includes a purification step in which either aluminum or magnesium, or both aluminum and magnesium, are melted in a vacuum atmosphere or an inert gas atmosphere to remove impurities. Scandium alloy You can obtain this.

[0038] According to the present invention Scandium alloy The manufacturing method includes a form in which the impurity comprises at least one selected from the group consisting of aluminum oxide, magnesium oxide, and scandium oxide. Furthermore, according to the present invention Scandium alloy In the manufacturing method, the composite powder preferably contains at least aluminum as the metal powder, and the aluminum-scandium compound blended as the composite powder is preferably formulated in a molar ratio of metallic aluminum to metallic scandium in the range of 10:1 to 1:1. [Effects of the Invention]

[0039] According to this disclosure, a scandium compound comprising at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride is reduced in an inexpensive, safe, environmentally friendly, and energy-efficient manner, and contains at least one of the metals aluminum or magnesium. Scandium alloy A method for manufacturing this can be provided. [Brief explanation of the drawing]

[0040] [Figure 1] This is a phase diagram of an aluminum-scandium alloy. [Figure 2] This shows the particle size distribution of the Al powder used in Examples 1 to 19. [Figure 3] This shows the particle size distribution results for the Sc2O3 used in Examples 1 to 19. [Figure 4] This figure shows the X-ray diffraction results for Example 1. [Figure 5A]The images show (a) SEM images, (b) EDS mapping images of Al, and (c) EDS mapping images of Sc of the composite powder after treatment in the nanomec reactor (10 min) in Examples 16 to 18. [Figure 5B] The images show (a) SEM images, (b) EDS mapping images of Al, and (c) EDS mapping images of Sc of the composite powder after treatment in the nanomec reactor (55 min) in Examples 16 to 18. [Figure 5C] The images show (a) SEM images, (b) EDS mapping images of Al, and (c) EDS mapping images of Sc of the composite powder after treatment in the nanomec reactor (115 min) in Examples 16 to 18. [Figure 6] This figure shows the X-ray diffraction results of the composite powder after the nanomec reactor (10 min) in Examples 16 to 18. [Figure 7] This figure shows the X-ray diffraction results of the composite powder after treatment in the nanomec reactor (55 min) in Examples 16 to 18. [Figure 8] This figure shows the X-ray diffraction results of the composite powder after treatment in the nanomec reactor (115 min) in Examples 16 to 18. [Figure 9] This figure shows the X-ray diffraction results for Example 19. [Figure 10] The images show (a) a cross-sectional photograph, (b) an SEM image, (c) an EDS mapping of Al, and (d) an EDS mapping of Sc for the sample of Example 20. [Modes for carrying out the invention]

[0041] The present invention will be described in detail below with reference to embodiments, but the present invention is not limited to these descriptions. The embodiments may be modified in various ways as long as they achieve the effects of the present invention.

[0042] This package Scandium alloyThe manufacturing method comprises a preparation step of preparing a composite powder containing a scandium compound powder comprising at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, and a metal powder containing at least one of aluminum or magnesium, or both aluminum and magnesium; and a heating step of heating the composite powder to 500°C or higher in a vacuum atmosphere or an inert gas atmosphere. The steps will be described below.

[0043] [Preparation process] (raw materials) As raw materials, a composite powder containing scandium compound powder and metal powder is prepared. The scandium compound powders include (1) scandium oxide powder, (2) scandium fluoride powder, (3) scandium chloride powder, (4) a combination of scandium oxide powder and scandium fluoride powder, (5) a combination of scandium oxide powder and scandium chloride powder, (6) a combination of scandium fluoride powder and scandium chloride powder, and (7) a combination of scandium oxide powder, scandium fluoride powder and scandium chloride powder. The metal powders include (1) aluminum powder, (2) magnesium powder, and (3) a combination of aluminum powder and magnesium powder. The raw materials are prepared by combining these powders, and in this embodiment, the prepared powder is referred to as "composite powder". The composite powder is preferably a mixed powder. The particle size of the scandium compound powder is preferably 1000 μm or less, more preferably 800 μm or less, and even more preferably 100 μm or less. The lower limit of the particle size of the scandium compound powder is not particularly limited, but is preferably, for example, 1 μm or more. The volume-based D50 particle size of the scandium compound powder is preferably 10 to 500 μm, and more preferably 10 to 200 μm. The particle size of the metal powder is preferably 2000 μm or less, more preferably 1000 μm or less, and even more preferably 500 μm or less. The lower limit of the particle size of the metal powder is not particularly limited, but is preferably, for example, 10 μm or more. The volume-based D50 particle size of the metal powder is preferably 30 to 500 μm, and more preferably 30 to 200 μm. Smaller particle sizes allow for shorter mixing times. To produce a mixed powder, various powders are placed in a mixing device, the atmosphere inside the mixing tank is preferably filled with an inert gas such as argon, and the mixture is carried out while the oxygen is discharged.

[0044] In any blending ratio of the composite powder, the scandium compound is reduced. For example, scandium oxide is reduced to metallic scandium and alloys with aluminum. In this process, as shown in Figure 1, scandium does not dissolve well in the aluminum, so the intermetallic compound Al3Sc is formed. Therefore, it is best to blend the scandium compound with a molar ratio of metallic aluminum to metallic scandium of 3:1. Alternatively, the aluminum and scandium compound can be blended within a molar ratio range of 10:1 to 1:1. Specifically, molar ratios such as 9:1, 5:1, 2:1, and 1:1 are acceptable.

[0045] (Auxiliary agent) The composite powder preferably further contains at least one additive selected from the group consisting of carboxylic acids, ascorbic acid, and higher fatty acids. The additives include (1) carboxylic acids, (2) ascorbic acid, (3) higher fatty acids, (4) combinations of carboxylic acids and ascorbic acid, (5) combinations of carboxylic acids and higher fatty acids, (6) combinations of ascorbic acid and higher fatty acids, and (7) combinations of carboxylic acids, ascorbic acid, and higher fatty acids. By adding these additives to the composite powder, a composite powder containing the additives is obtained. It is preferable that the composite powder containing the additives is in a mixed state of the additives and the composite powder. The amount of additives blended per 100 parts by mass of composite powder is preferably 1 part by mass or less. The lower limit of the amount of additives blended is preferably 0.1 parts by mass. It is preferable to add additives in order to improve yield. Examples of additives include alcohols, hydrocarbons, carboxylic acids, and higher fatty acids. Examples of alcohols include methanol. Examples of hydrocarbons include heptane. Examples of carboxylic acids include acetic acid, oxalic acid, and benzoic acid. Examples of higher fatty acids include stearic acid and oleic acid. The factor that reduces yield is the strong oxide film present on the surface of aluminum or magnesium metal raw materials, which inhibits the reaction with scandium compounds. Therefore, the aforementioned additives are added to act as aids in removing the surface oxide film and improve yield.

[0046] [Mechanical Alloying Process A, Mechanical Alloying Process B] It is preferable to further include a mechanical alloying step A, in which the composite powder prepared in the preparation step is mechanically alloyed. Alternatively, it is preferable to further include a mechanical alloying step B, in which the composite powder containing the auxiliary agent prepared in the preparation step is mechanically alloyed. When mixing a scandium compound powder, such as scandium oxide, with the base material aluminum powder and / or magnesium powder, adding a step of high-energy mechanical alloying makes it possible to reduce the scandium compound at a lower temperature. Mechanical alloying is a method of obtaining an alloy by placing the composite powder or composite powder containing the auxiliary agent into a ball mill together with a grinding medium such as ceramics and rotating it, thereby repeatedly pressurizing and spreading the composite powder or composite powder containing the auxiliary agent. To mechanically alloy composite powders, various powders are placed in a mixing device, the atmosphere in the mixing tank is preferably filled with an inert gas such as argon, and the oxygen is removed before mixing. Furthermore, ceramic balls such as alumina or zirconia are added as mixing components and the device is sealed. For processes that require high energy and short time intervals, planetary ball mills, attritors, bead mills, etc., are used. To mechanically alloy composite powders containing additives, various powders are placed in a mixing device together with the additives, and the same process as for mechanically alloying composite powders without additives is performed. By performing mechanical alloying for 10 minutes or more, the mixed composite powder is obtained.

[0047] [Mold filling process] The molding process involves placing the composite powder or composite powder containing auxiliary agents into a mold. If mechanically alloyed composite powder is obtained in mechanical alloying process A or mechanical alloying process B, the molding process involves placing the mechanically alloyed composite powder into the mold. Examples of molds include press molds, carbon molds, and rubber molds for cold isostatic pressing.

[0048] [Molding process] In this embodiment, after the molding process, there may be a step of applying pressure to the composite powder or mechanically alloyed composite powder to form a molded body. In this case, a heating step is performed as a post-molding step. In the molding process, the pressure applied to the composite powder or mechanically alloyed composite powder is preferably 5 MPa or more, more preferably 30 MPa or more, and even more preferably 50 MPa or more.

[0049] [Heating process] The heating process has two variations: (1) Step A, in which the molded composite powder or mechanically alloyed composite powder is heated after the molding and molding processes; and (2) Step B, in which the composite powder or mechanically alloyed composite powder, which has been placed in the mold after the molding process but without going through the molding process, is heated under pressure in a vacuum atmosphere or inert gas atmosphere. In Step A, since the molded body is easy to handle, the heating process can be performed in a heating furnace, high-frequency furnace, etc., which can be adjusted to a vacuum atmosphere or inert gas atmosphere. In Step B, the heating and pressurizing process can be performed in a hot press, HIP, spark plasma sintering machine, etc., which can be adjusted to a vacuum atmosphere or inert gas atmosphere. The heating temperature should be 500°C or higher, preferably 550 to 900°C, and more preferably 600 to 750°C. In Step B of the heating process, the pressure applied to the composite powder is preferably 5 MPa or higher, and more preferably 30 MPa or higher. An inert gas atmosphere is, for example, an argon atmosphere or a nitrogen atmosphere. A vacuum atmosphere is, for example, 5 Pa or less.

[0050] [After heating process] Obtained through the heating process Scandium alloy teeth, Aluminum scandium alloy Includes, The aluminum scandium alloy It includes at least one selected from the group consisting of aluminum scandium solid solution alloy, Al3Sc intermetallic compound, Al2Sc intermetallic compound, and AlSc intermetallic compound. Furthermore, it is obtained through a heating process. Scandium alloy but Magnesium scandium alloy Includes, The magnesium scandium alloy It includes at least one selected from the group consisting of magnesium scandium solid solution alloys and MgSc intermetallic compounds. Furthermore, obtained through a heating process Scandium alloy but Aluminum magnesium scandium alloy Includes, The aluminum-magnesium-scandium alloy This includes at least one selected from the group consisting of aluminum scandium solid solution alloys, Al3Sc intermetallic compounds, Al2Sc intermetallic compounds, and AlSc intermetallic compounds, and at least one selected from the group consisting of magnesium scandium solid solution alloys and MgSc intermetallic compounds.

[0051] [Refining process] The purification process is obtained through a heating process. Scandium alloy This process involves melting either aluminum or magnesium, or both aluminum and magnesium, in a vacuum atmosphere or an inert gas atmosphere to remove impurities. Scandium alloy This process allows us to obtain a high-purity material. Here, the impurities include at least one selected from the group consisting of aluminum oxide, magnesium oxide, and scandium oxide. The inert gas atmosphere is, for example, an argon atmosphere or a nitrogen atmosphere. The vacuum atmosphere is, for example, 5 Pa or less. The melting temperature is, for example, 700 to 1450°C. Through this process, the impurities do not dissolve into the molten phase consisting of either aluminum or magnesium, or both aluminum and magnesium, but remain on the outside of the molten phase. By removing the outer portion of the molten phase containing impurities after cooling, a high-purity material can be obtained. Scandium alloy This can be obtained. Methods for removing impurities include physical cutting, such as band sawing or shearing.

[0052] This package Scandium alloy In the manufacturing method, for example, the adjustment of the composition ratio of Al and Sc can be done by preparing the composite powder from the beginning so that the final composition ratio is achieved, or by first adjusting the composite powder from the beginning to achieve the desired composition ratio. Scandium alloy This includes cases where a compound is manufactured and then the concentration of the Al-Sc alloy is adjusted with Al, and cases where the concentration of the Al-Sc alloy is adjusted with Sc. Furthermore, for example, adjusting the composition ratio of Mg and Sc may involve adjusting the composite powder to achieve the desired composition ratio, or, initially, Scandium alloyThis includes cases where a compound is manufactured, and then the concentration of the Mg-Sc alloy is adjusted with Mg, and cases where the concentration of the Mg-Sc alloy is adjusted with Sc. Furthermore, for example, the adjustment of the composition ratio of Al, Mg, and Sc includes cases where the composite powder is adjusted to finally achieve the desired composition ratio, as well as cases where, Scandium alloy This includes cases where a product is manufactured, and then the concentration of the Al-Mg-Sc alloy is adjusted with Al or Mg, and cases where the concentration of the Al-Mg-Sc alloy is adjusted with Sc. [Examples]

[0053] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples.

[0054] (Example 1) Aluminum powder having the particle size distribution shown in Figure 2 (particle size 300 μm or less, volume-based D50 particle diameter 45 μm, purity 99.99%) and scandium oxide powder having the particle size distribution shown in Figure 3 (particle size 100 μm or less, volume-based D50 particle diameter 16 μm, purity 99.99%) were mixed in a molar ratio of Al:Sc = 5:1. The powders were then mixed uniformly in a mixing bottle to obtain a composite powder. Next, the composite powder was placed in a stainless steel mold and compacted under a pressure of 111 MPa to obtain pellets (molded bodies). The pellets were placed in a high-frequency furnace under a vacuum atmosphere of 1-2 kPa and heat-treated at 700°C for 1 hour. After the heat-treated pellets were crushed, measurements were taken using an X-ray diffractometer. The measurement results are shown in Figure 4. Subsequently, the conversion rate to Al3Sc was determined from the X-ray diffraction graph according to (Equation 1). The conversion rate was 58%. (Mathematics 1) Conversion rate (%) = Intensity of the strongest line of Al3Sc (A) / (Intensity of the strongest line of Al3Sc (A) + Intensity of the strongest line of Sc2O3 (B)) × 100

[0055] (Examples 2-3) Alloying was carried out under the same conditions as in Example 1, except for the heat treatment temperature. X-ray diffraction measurements were performed on the obtained sample in the same manner as in Example 1, and the conversion rate to Al3Sc was calculated from the X-ray diffraction graph using the same method as in Example 1. The results are shown below. Example 2: Heat treatment temperature 800°C, conversion rate to Al3Sc 32% Example 3: Heat treatment temperature 900°C, conversion rate to Al3Sc 19%

[0056] (Example 4) Instead of placing the powder in a mixing bottle, the powder was placed in a planetary mill pot along with zirconia balls. The pot was then filled with argon, the oxygen was removed, and the pot was sealed. Mechanical alloying was performed for 3 hours at 180 rpm. This composite powder was processed in the same manner as in Example 1, and the resulting sample was subjected to X-ray diffraction measurements in the same manner as in Example 1. The conversion rate to Al3Sc was calculated from the X-ray diffraction graph in the same manner as in Example 1. The conversion rate was 82%.

[0057] (Examples 5 to 15) Alloying was carried out under the same conditions as in Example 4, except for the mixing time and heat treatment temperature. X-ray diffraction measurements were performed on the obtained sample in the same manner as in Example 1, and the conversion rate to Al3Sc was calculated from the X-ray diffraction graph using the same method as in Example 1. The results are shown below. Example 5: Mixing time 3 hours, heat treatment temperature 600°C, conversion rate to Al3Sc 9% Example 6: Mixing time 3 hours, heat treatment temperature 800°C, conversion rate to Al3Sc 78% Example 7: Mixing time 3 hours, heat treatment temperature 900°C, conversion rate to Al3Sc 44% Example 8: Mixing time 6 hours, heat treatment temperature 600°C, conversion rate to Al3Sc 14% Example 9: Mixing time 6 hours, heat treatment temperature 700°C, conversion rate to Al3Sc 88% Example 10: Mixing time 6 hours, heat treatment temperature 800°C, conversion rate to Al3Sc 85% Example 11: Mixing time 6 hours, heat treatment temperature 900°C, conversion rate to Al3Sc 35% Example 12: Mixing time 9 hours, heat treatment temperature 600°C, conversion rate to Al3Sc 35% Example 13: Mixing time 9 hours, heat treatment temperature 700°C, conversion rate to Al3Sc 92% Example 14: Mixing time 9 hours, heat treatment temperature 800°C, conversion rate to Al3Sc 88% Example 15: Mixing time 9 hours, heat treatment temperature 900°C, conversion rate to Al3Sc 51%

[0058] (Example 16) Aluminum powder having the particle size distribution shown in Figure 2 (particle size 300 μm or less, volume-based D50 particle diameter 45 μm, purity 99.99%) and scandium oxide powder having the particle size distribution shown in Figure 3 (particle size 100 μm or less, volume-based D50 particle diameter 16 μm, purity 99.99%) were mixed in a molar ratio of Al:Sc = 1:1. Instead of a planetary mill, the mixture was placed in a mixing tank of a nanomech reactor capable of High Energy Milling (HEM), filled with argon, and after the oxygen was discharged, it was sealed and mechanical alloying was performed. Mechanical alloying was carried out under conditions of alternating 1000 rpm × 45 seconds and 500 rpm × 15 seconds for a mixing time of 115 minutes. This composite powder was placed in a stainless steel mold and compacted under a pressure of 87 MPa to obtain pellets (molded bodies). Subsequently, the sample was processed in the same manner as in Example 1, and X-ray diffraction measurements were performed on the obtained sample in the same manner as in Example 1. The conversion rate to Al3Sc was calculated from the X-ray diffraction graph using the same method as in Example 1. The conversion rate was 45%.

[0059] (Examples 17-18) Alloying was carried out under the same conditions as in Example 16, except for the heat treatment temperature. X-ray diffraction measurements were performed on the obtained sample in the same manner as in Example 1, and the conversion rate to Al3Sc was calculated from the X-ray diffraction graph using the same method as in Example 1. The results are shown below. Example 17: Heat treatment temperature 500°C, conversion rate to Al3Sc 16% Example 18: Heat treatment temperature 600°C, conversion rate to Al3Sc 45%

[0060] In the HEM treatment using the nanomec reactor in Examples 16-18, SEM observation and EDS mapping were performed on the composite powder after HEM treatment for 10 minutes, 55 minutes, and 155 minutes. The observation results are shown in Figures 5(A), 5(B), and 5(C).

[0061] (Example 19) A mechanically alloyed composite powder was obtained in the same manner as in Example 4, except that the mixing time for the mechanical alloying was set to 9 hours. After placing the mechanically alloyed composite powder into a carbon mold, it was subjected to a discharge-coupled plasma (SPS) device in a vacuum atmosphere of approximately 2 Pa, followed by heating and pressurizing treatment at 600°C and a pressure of 30 MPa for 1 hour. X-ray diffraction measurements were performed on the obtained sample in the same manner as in Example 1. The measurement results are shown in Figure 9. Subsequently, the conversion rate to Al3Sc was calculated from the X-ray diffraction graph using the same method as in Example 1. The conversion rate was 98%.

[0062] (Example 20) The sample obtained in Example 19 and Al were placed in a boron nitride crucible and heated to 1450°C using high-frequency heating to dissolve the Al. Scandium alloy The sample was cooled, and cross-sectional SEM observation and EDS mapping were performed. The observation results are shown in Figures 10(a), 10(b), 10(c), and 10(d). From the SEM observation and EDS mapping results, Al and Sc were confirmed in the Al phase. Oxygen (O) was not detected.

[0063] In a comparison of Examples 1 to 3, reduction proceeded even at heat treatment temperatures of 800°C and 900°C, but the conversion rate was highest at 700°C. The results showed that reduction proceeded more easily the closer the temperature was to the melting point of Al (660°C).

[0064] In a comparison of Examples 4 to 15, a tendency was observed for higher conversion rates with longer mechanical alloying times at all temperatures. This is thought to be due to the increased particle size reduction and increased contact area between powder particles that were promoted with longer alloying times.

[0065] In Examples 16 to 18, Al3Sc was detected not only at a heat treatment temperature of 700°C, but also at 500°C and 600°C. This suggests that the reaction from Sc2O3 to Al3Sc is accelerated by HEM using a nanomec reactor. Furthermore, the dispersion of Sc2O3 in the Al powder was confirmed from SEM images and EDS mapping results of the composite powder after HEM treatment. After 10 minutes, Sc2O3 was sufficiently dispersed and in contact with Al, suggesting that pseudo-alloying occurred. In addition, X-ray diffraction measurements were performed on the composite powder after HEM treatment using an X-ray diffractometer. The measurement results are shown in Figures 6 to 8. XRD analysis revealed that the peak width at half maximum broadened in the initial stages of mixing (Figures 6 and 7), indicating refinement. Subsequently, the width at half maximum returned to normal (Figure 8), and furthermore, the Al3Sc peak could not be detected at this point. In this state, the scandium oxide is not reduced, but the aluminum metal is in sufficient contact with the scandium oxide, forming an alloy like an oxide dispersant, which is thought to have contributed to reduction at lower temperatures.

[0066] In Example 19, the conversion rate was 98%. This suggests that heating under pressure accelerates the reaction from Sc2O3 to Al3Sc.

[0067] In Example 20, Al and Sc were confirmed in the Al phase. The Al3Sc (melting point: approximately 1320°C) produced in Example 19 melted together with Al (melting point: approximately 660°C) upon heating. It is thought that the Al3Sc then precipitated within the Al phase during cooling. Furthermore, oxides such as Sc2O3, having a higher melting point relative to the heating temperature, are thought to have remained as solid masses without melting. Al 3 Sc alloy Sc2O3 can be physically separated and removed.

Claims

1. A preparation step of preparing a powder of a scandium compound, which is at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, and a composite powder of a metal powder which is either aluminum or magnesium, or both aluminum and magnesium (except when cryolite is included), Mechanical alloying step A involves mechanically alloying the composite powder prepared in the above preparation step, The aforementioned composite powder is a mechanically alloyed composite powder which is placed into a mold in a molding process, A molding process in which pressure is applied to the composite powder to form a molded body, A heating step of heating the molded composite powder to 500°C or more and 900°C or less in a vacuum atmosphere or an inert gas atmosphere, It has, A method for producing a scandium alloy, characterized by obtaining an aluminum scandium alloy, a magnesium scandium alloy, or an aluminum magnesium scandium alloy.

2. A preparation step of preparing a powder of a scandium compound, which is at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, and a composite powder of a metal powder which is either aluminum or magnesium, or both aluminum and magnesium (except when cryolite is included), The composite powder prepared in the above preparation step further contains at least one selected from the group consisting of carboxylic acids, ascorbic acid, and higher fatty acids as an auxiliary agent. Mechanical alloying step B involves mechanically alloying the composite powder containing the auxiliary agent prepared in the above preparation step, The process involves placing the mechanically alloyed composite powder, as the aforementioned composite powder, into a mold. A molding process in which pressure is applied to the composite powder to form a molded body, A heating step of heating the molded composite powder to 500°C or more and 900°C or less in a vacuum atmosphere or an inert gas atmosphere, It has, A method for producing a scandium alloy, characterized by obtaining an aluminum scandium alloy, a magnesium scandium alloy, or an aluminum magnesium scandium alloy.

3. A preparation step of preparing a powder of a scandium compound, which is at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, and a composite powder of a metal powder which is either aluminum or magnesium, or both aluminum and magnesium (except when cryolite is included), Mechanical alloying step A involves mechanically alloying the composite powder prepared in the above preparation step, The aforementioned composite powder is a mechanically alloyed composite powder which is placed into a mold in a molding process, A heating step of heating the composite powder to 500°C or more and 900°C or less in a vacuum atmosphere or an inert gas atmosphere, It has, The heating step is a step of heating the composite powder placed in the mold under pressure in a vacuum atmosphere or an inert gas atmosphere. A method for producing a scandium alloy, characterized by obtaining an aluminum scandium alloy, a magnesium scandium alloy, or an aluminum magnesium scandium alloy.

4. A preparation step of preparing a powder of a scandium compound, which is at least one selected from the group consisting of scandium oxide, scandium fluoride, and scandium chloride, and a composite powder of a metal powder which is either aluminum or magnesium, or both aluminum and magnesium (except when cryolite is included), The composite powder prepared in the above preparation step further contains at least one selected from the group consisting of carboxylic acids, ascorbic acid, and higher fatty acids as an auxiliary agent. Mechanical alloying step B involves mechanically alloying the composite powder containing the auxiliary agent prepared in the above preparation step, The aforementioned composite powder is a mechanically alloyed composite powder which is placed into a mold in a molding process, A heating step of heating the composite powder to 500°C or more and 900°C or less in a vacuum atmosphere or an inert gas atmosphere, It has, The heating step is a step of heating the composite powder placed in the mold under pressure in a vacuum atmosphere or an inert gas atmosphere. A method for producing a scandium alloy, characterized by obtaining an aluminum scandium alloy, a magnesium scandium alloy, or an aluminum magnesium scandium alloy.

5. The method for producing a scandium alloy according to any one of claims 1 to 4, characterized in that the particle size of the scandium compound powder is 1000 μm or less.

6. A method for producing a scandium alloy according to any one of claims 1 to 4, characterized in that the particle size of the metal powder is 2000 μm or less.

7. The method for producing a scandium alloy according to claim 1 or 2, characterized in that the pressure applied to the composite powder in the molding step is 5 MPa or more.

8. The method for producing a scandium alloy according to claim 3 or 4, characterized in that the pressure applied to the composite powder in the heating step is 5 MPa or more.

9. The scandium alloy obtained through the aforementioned heating process includes an aluminum scandium alloy, and the aluminum scandium alloy is an aluminum scandium solid solution alloy, Al ３ Sc intermetallic compound, Al ２ A method for producing a scandium alloy according to any one of claims 1 to 4, characterized by comprising at least one selected from the group consisting of Sc intermetallic compounds and AlSc intermetallic compounds.

10. A method for producing a scandium alloy according to any one of claims 1 to 4, characterized in that the scandium alloy obtained through the heating step includes a magnesium scandium alloy, and the magnesium scandium alloy includes at least one selected from the group consisting of magnesium scandium solid solution alloys and MgSc intermetallic compounds.

11. A method for producing a scandium alloy according to any one of claims 1 to 4, further comprising a purification step of melting the scandium alloy obtained through the heating step with either aluminum or magnesium, or both aluminum and magnesium, in a vacuum atmosphere or an inert gas atmosphere to remove impurities.

12. The method for producing a scandium alloy according to claim 11, characterized in that the impurity includes at least one selected from the group consisting of aluminum oxide, magnesium oxide, and scandium oxide.

13. The composite powder contains at least aluminum as the metal powder, and The method for producing a scandium alloy according to any one of claims 1 to 4, characterized in that the aluminum and scandium compound blended as the composite powder is formulated in a molar ratio of metallic aluminum to metallic scandium in the range of 10:1 to 1:1.

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