Aluminum-scandium master alloy and method for preparing the same

Abstract

The application provides an aluminum-scandium intermediate alloy and a preparation method thereof. The preparation method of the aluminum-scandium intermediate alloy comprises the following steps: mixing a composite fluoride salt molten liquid with a scandium source to perform first melting treatment, to obtain a first molten liquid; mixing the first molten liquid with an aluminum source to perform second melting treatment, to obtain a second molten liquid; mixing a composite chloride salt in at least three batches with the second molten liquid to perform third melting treatment, to obtain a third molten liquid; after slag removal treatment of the third molten liquid, calcination, smelting and cooling treatment are performed, to obtain the aluminum-scandium intermediate alloy. The preparation method of the aluminum-scandium intermediate alloy can effectively control the reaction process in a non-vacuum environment, reduce aluminum liquid oxidation and scandium element burning loss, improve product purity, and obtain an intermediate alloy with uniform scandium element distribution and high purity.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal metallurgy technology and relates to an aluminum-scandium master alloy and its preparation method. Background Technology

[0002] Aluminum-scandium master alloys, as high-performance aluminum alloy additives, can significantly improve the strength, toughness, corrosion resistance, and high-temperature stability of aluminum alloys, and have broad application prospects in high-end fields such as aerospace, rail transportation, and shipbuilding. However, scandium, as a rare and dispersed metal, is scarce and difficult to extract, resulting in high production costs for aluminum-scandium master alloys, which limits their large-scale industrial application.

[0003] Currently, the main methods for preparing aluminum-scandium master alloys include molten salt electrolysis, vacuum aluminothermic reduction, and metallothermic reduction. Molten salt electrolysis suffers from high energy consumption, volatile electrolyte, and strong corrosiveness to equipment. Metallothermic reduction typically requires expensive reducing agents, and product purity is difficult to control. Vacuum aluminothermic reduction is one of the more commonly used methods. This method utilizes the reducing properties of aluminum to reduce scandium oxides in a vacuum environment to prepare aluminum-scandium master alloys. However, vacuum aluminothermic reduction places extremely high demands on equipment, requiring dedicated vacuum smelting equipment, resulting in large equipment investments, high maintenance costs for the vacuum system during production, and complex operating procedures in a vacuum environment, leading to low production efficiency and making it difficult to meet the needs of large-scale industrial production.

[0004] To address the aforementioned problems of the vacuum aluminothermic reduction method, developing a method for the efficient preparation of aluminum-scandium master alloys under non-vacuum conditions is of significant practical importance. Non-vacuum preparation methods can effectively reduce equipment investment and production maintenance costs, simplify operating procedures, and improve production efficiency. However, aluminothermic reduction reactions under non-vacuum conditions are prone to problems such as aluminum molten oxidation, severe scandium loss due to burning, and excessively high inclusion content in the product, resulting in low purity and non-uniform composition of the prepared aluminum-scandium master alloy, which fails to meet practical application requirements. Therefore, how to effectively control the reaction process under non-vacuum conditions, reduce aluminum molten oxidation and scandium loss due to burning, and improve product purity and compositional uniformity has become a key technical challenge that urgently needs to be solved in the preparation of aluminum-scandium master alloys using the non-vacuum aluminothermic reduction method. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an aluminum-scandium master alloy and its preparation method. The method described in this invention can effectively control the reaction process in a non-vacuum environment, reduce aluminum liquid oxidation and scandium element burn-off, improve product purity, and obtain a master alloy with uniform scandium element distribution and high purity.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing an aluminum-scandium master alloy, the method comprising the following steps: The composite fluoride molten liquid is mixed with a scandium source and subjected to a first melting treatment to obtain a first molten liquid; The first molten liquid is mixed with an aluminum source and subjected to a second melting process to obtain a second molten liquid; The composite chloride salt is mixed with the second melt in at least three batches and subjected to a third melt treatment to obtain the third melt. After slag removal from the third molten liquid, the aluminum-scandium master alloy is obtained through calcination, smelting, and cooling.

[0007] This invention directly mixes the composite fluoride molten liquid with the scandium source, which facilitates the rapid and uniform dispersion and initial dissolution / reaction of the scandium source in the fluoride salt, creating a favorable thermodynamic and kinetic environment for subsequent reduction. After melting, an aluminum source is added for a second melting treatment, followed by the batch addition of composite chloride salt. The chloride salt rapidly disperses throughout the melt, making full contact with the aluminothermic reduction products, significantly improving reaction efficiency. Simultaneously, a dense, continuous, and effectively air-isolated liquid protective layer is formed on the melt surface with good permeability. This protective layer not only prevents the oxidation of aluminum and scandium but also dissolves the reaction product alumina, reduces slag viscosity, and promotes reaction kinetics. This allows the entire reduction reaction to proceed safely and stably under atmospheric pressure, eliminating the need for expensive vacuum equipment and significantly reducing investment and production costs. The batch addition of the composite chloride salt described in this invention continuously disrupts the oxide film in the melt, promoting impurity flotation and acting as a dynamic refining agent. This greatly optimizes the reaction kinetics, improves scandium recovery rate and alloy composition uniformity, and effectively promotes impurity separation. Since the chloride salts described in this invention are added in batches, slag removal treatment is required to remove the slag generated during the reaction. After that, calcination is performed to remove volatile salts or moisture from the system, further improving the purity of the alloy. Finally, after melting and homogenization and cooling, the aluminum-scandium master alloy can be obtained.

[0008] Preferably, the temperatures of the first melting treatment, the second melting treatment, and the third melting treatment are each independently 900℃~1000℃, for example: 900℃, 920℃, 950℃, 980℃, or 1000℃, etc., and are not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0009] Preferably, the times for the first melting treatment, the second melting treatment, and the third melting treatment are each independently 30 min to 60 min, for example: 30 min, 35 min, 40 min, 50 min, or 60 min, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0010] Preferably, the fluoride salts in the composite fluoride melt include NaF, AlF3, and Na3AlF6.

[0011] The present invention uses a composite fluoride salt melting system with common composition, which can effectively reduce the melting point and interfacial tension of the slag system and improve the thermodynamic and kinetic conditions of the reaction. Excess aluminum and continuous stirring ensure that scandium oxide and aluminum liquid are in full contact, making the reduction reaction more thorough. The scandium yield in the method can be stably reached above 95%.

[0012] Preferably, the mass ratio of NaF, AlF3, and Na3AlF6 in the composite fluoride molten liquid is (1~2):(0.1~1):(1.5~3.5), for example: 1:0.1:1.5, 1:0.5:2, 1.5:0.5:3, 1.8:0.8:2, or 2:1:3.5, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] Preferably, the scandium source includes scandium oxide.

[0014] Preferably, the mass ratio of the composite fluoride molten liquid to the scandium source is (1.5~5):1, for example: 1.5:1, 2:1, 3:1, 4:1 or 5:1, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] Preferably, the aluminum source comprises elemental aluminum.

[0016] Preferably, the mass ratio of the first molten liquid to the aluminum source is (0.1~0.4):1, for example: 0.1:1, 0.15:1, 0.2:1, 0.3:1 or 0.4:1, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] Preferably, the composite chloride salt includes sodium chloride and potassium chloride.

[0018] Preferably, the mass ratio of sodium chloride to potassium chloride is 1:(2~4), for example: 1:2, 1:2.5, 1:3, 1:3.5 or 1:4, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] Preferably, the mass ratio of the composite chloride salt to the second melt is 1:(3~5), for example: 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the mixing process involves stirring.

[0021] The mixing process described in this invention includes mixing the composite fluoride molten liquid with a scandium source, mixing the first molten liquid with an aluminum source, and mixing the composite chloride salt with the second molten liquid in at least three batches. That is, stirring is carried out during each mixing step. Stirring can ensure that the scandium oxide and the aluminum liquid are in full contact, so that the reduction reaction is more thorough.

[0022] Preferably, the stirring speed is 200 rpm to 400 rpm, for example: 200 rpm, 250 rpm, 300 rpm, 350 rpm or 400 rpm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] Preferably, the composite chloride salt is added to the second melt in 5 to 8 batches, for example, 5, 6, 7 or 8 batches.

[0024] The amount of the composite chloride salt added in each batch of the present invention is similar, with a difference of ≤10%.

[0025] Preferably, the calcination temperature is 820℃~880℃, for example: 820℃, 830℃, 850℃, 860℃ or 880℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] Preferably, the calcination time is 20 min to 40 min, for example: 20 min, 25 min, 30 min, 35 min or 40 min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Preferably, the melting temperature is 920℃~980℃, for example: 920℃, 940℃, 950℃, 960℃ or 980℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] Preferably, the melting time is 20 min to 40 min, for example: 20 min, 25 min, 30 min, 35 min or 40 min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] In a second aspect, the present invention provides an aluminum-scandium master alloy, which is prepared by the preparation method described in the first aspect.

[0030] The method described in this invention produces an aluminum-scandium master alloy with uniform composition and good quality. Scandium atoms generated under liquid phase conditions can rapidly diffuse and dissolve into the aluminum melt. Combined with subsequent slag removal processes, gravity segregation can be effectively avoided, resulting in a master alloy with uniform scandium distribution. The resulting alloy ingot has a dense structure with few pores and inclusions.

[0031] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0032] Compared with the prior art, the present invention has the following beneficial effects: (1) The method of the present invention uses a solid-liquid mixing method to disperse the scandium source in the composite fluoride molten liquid. In the subsequent reaction process, the generated scandium atoms can rapidly diffuse and dissolve into the aluminum liquid. The composite chloride salt is added to the molten liquid in multiple batches, and the chloride salt is rapidly dispersed to all parts of the melt, making full contact with the aluminothermic reduction products. This significantly improves the reaction efficiency and forms a dense, continuous liquid protective layer on the surface of the melt that can effectively isolate air and has good permeability. This protective layer can not only prevent the oxidation of aluminum and scandium, but also dissolve the reaction product alumina, reduce the viscosity of the slag phase, and promote the reaction kinetics process. This allows the entire reduction reaction to proceed safely and stably under normal pressure air atmosphere.

[0033] (2) The scandium yield of the aluminum-scandium alloy prepared by the present invention is over 95%, with fewer inclusions and an impurity content of less than 0.25%. It is a high-purity, low-inclusion, and low-cost aluminum-scandium intermediate alloy. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the preparation process of the aluminum-scandium master alloy according to an embodiment of the present invention.

[0035] Figure 2 This is a metallographic microstructure of the aluminum-scandium master alloy described in Example 1 of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0037] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0038] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0039] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0040] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0041] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0042] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0043] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0044] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0045] In this invention, "optional" means that something is optional, that is, it refers to any one of the two parallel solutions of "having" or "not having". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0046] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0047] Example 1 This embodiment provides an aluminum-scandium master alloy, and the preparation process flow diagram of the aluminum-scandium master alloy is shown below. Figure 1 As shown, the aluminum-scandium master alloy is prepared by the following method: A composite fluoride salt melt with a mass ratio of NaF, AlF3, and Na3AlF6 of 1.5:0.5:2.5 was mixed with scandium oxide at a mass ratio of 3:1, and subjected to a first melting treatment at 950°C for 45 min to obtain a first melt. The first molten liquid was mixed with elemental aluminum at a mass ratio of 0.25:1, and then subjected to a second melting treatment at 950℃ for 35 minutes to obtain the second molten liquid. The second melt was stirred at 300 rpm. The composite chloride salt (sodium chloride and potassium chloride in a mass ratio of 1:3) was added in equal amounts in 6 batches to the second melt under stirring (the mass ratio of composite chloride salt to the second melt was 1:4). The third melt was then subjected to a third melting treatment at 950℃ for 40 minutes to obtain the third melt. After removing slag from the third molten liquid, it is calcined at 850°C for 25 minutes and smelted at 950°C for 30 minutes, and then cooled to obtain the aluminum-scandium master alloy.

[0048] The metallographic microstructure of the aluminum-scandium master alloy is shown in the figure below. Figure 2 As shown, by Figure 2 It can be seen that the Sc element in the aluminum-scandium master alloy described in this application is relatively uniformly distributed, with a maximum particle size of 21.1µm and no obvious segregation phenomenon. The experiment shows that the method described in this invention can obtain an aluminum-scandium master alloy with a high scandium yield and a relatively uniform scandium element distribution.

[0049] Example 2 This embodiment provides an aluminum-scandium master alloy, and the preparation process flow diagram of the aluminum-scandium master alloy is shown below. Figure 1 As shown, the aluminum-scandium master alloy is prepared by the following method: A composite fluoride salt melt with a mass ratio of NaF, AlF3, and Na3AlF6 of 1:0.1:1.5 was mixed with scandium oxide at a mass ratio of 5:1, and subjected to a first melting treatment at 1000℃ for 30 min to obtain a first melt. The first molten liquid was mixed with elemental aluminum at a mass ratio of 0.1:1, and then subjected to a second melting treatment at 1000℃ for 30 minutes to obtain the second molten liquid. The second melt was stirred at a stirring speed of 400 rpm. The composite chloride salt (sodium chloride and potassium chloride in a mass ratio of 1:2) was added in 8 batches in equal amounts to the second melt under stirring (the mass ratio of composite chloride salt to the second melt was 1:5). The third melt was then subjected to a third melting treatment at 1000℃ for 30 min to obtain the third melt. After removing slag from the third molten liquid, it is calcined at 820°C for 40 min and smelted at 920°C for 40 min, and then cooled to obtain the aluminum-scandium master alloy.

[0050] Example 3 This embodiment provides an aluminum-scandium master alloy, and the preparation process flow diagram of the aluminum-scandium master alloy is shown below. Figure 1 As shown, the aluminum-scandium master alloy is prepared by the following method: A composite fluoride salt melt with a mass ratio of NaF, AlF3, and Na3AlF6 of 2:1:3.5 was mixed with scandium oxide at a mass ratio of 1.5:1, and subjected to a first melting treatment at 900℃ for 30 min to obtain a first melt. The first molten liquid was mixed with elemental aluminum at a mass ratio of 0.4:1, and then subjected to a second melting treatment at 900℃ for 60 minutes to obtain the second molten liquid. The second melt was stirred at 200 rpm. The composite chloride salt (sodium chloride and potassium chloride in a mass ratio of 1:4) was added in 5 batches in equal amounts to the second melt under stirring (the mass ratio of composite chloride salt to the second melt was 1:3). The third melt was then subjected to a third melting treatment at 900℃ for 60 min to obtain the third melt. After removing slag from the third molten liquid, it is calcined at 880°C for 20 min, smelted at 980°C for 20 min, and then cooled to obtain the aluminum-scandium master alloy.

[0051] Example 4 The only difference between this embodiment and Embodiment 1 is that the mass ratio of the composite fluoride molten liquid to the scandium source is 1:1; all other conditions and parameters are exactly the same as in Embodiment 1.

[0052] Example 5 The only difference between this embodiment and Embodiment 1 is that the mass ratio of the composite fluoride molten liquid to the scandium source is 6:1, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0053] Example 6 The only difference between this embodiment and Embodiment 1 is that the mass ratio of the composite chloride salt to the second molten liquid is 1:2, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0054] Example 7 The only difference between this embodiment and Embodiment 1 is that the mass ratio of the composite chloride salt to the second molten liquid is 1:6, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0055] Comparative Example 1 The only difference between this comparative example and Example 1 is that the composite fluoride molten liquid is directly mixed with the scandium oxide solid phase before melting. All other conditions and parameters are exactly the same as in Example 1.

[0056] Comparative Example 2 The only difference between this comparative example and Example 1 is that the composite chloride salt is added to the second melt at once; all other conditions and parameters are exactly the same as in Example 1.

[0057] Performance testing: The aluminum-scandium master alloys obtained in the examples and comparative examples were sampled and tested: the scandium content in the aluminum-scandium master alloys was analyzed by ICP, and the scandium yield was calculated. The scandium yield is the ratio of the total mass of scandium in the prepared aluminum-scandium alloy to the total mass of scandium element contained in the added raw materials. The test results are shown in Table 1. Table 1 As can be seen from Table 1, the aluminum-scandium master alloy prepared by the present invention, as obtained from Examples 1 to 7, has an average scandium content of 2±0.2%, relatively uniform composition, high scandium yield, and low impurity content. The scandium yield exceeds 95%, and the impurity content is less than 0.25%. It is a high-purity, low-cost, and homogenized aluminum-scandium master alloy.

[0058] Comparing Examples 1 and 4-5, it can be seen that the mass ratio of the composite fluoride salt melt to the scandium source affects the preparation effect of the aluminum-scandium master alloy described in this invention. Controlling the mass ratio of the composite fluoride salt melt to the scandium source at (1.5~5):1 yields a better aluminum-scandium master alloy. If the amount of composite fluoride salt melt added is too large, it will dilute the concentration of the key reaction interface between the scandium source and aluminum in the system, resulting in a decrease in the driving force of the aluminothermic reduction reaction, a slower reaction rate, or even incomplete reaction. If the amount of composite fluoride salt melt added is too small, the amount of molten salt is insufficient, and a continuous and effective liquid phase reaction environment cannot be formed, resulting in uneven dispersion of the scandium source and a small contact area with the aluminum melt, which is insufficient to effectively dissolve and adsorb impurities such as alumina generated in the reaction, leading to an increase in non-metallic inclusions in the alloy.

[0059] Comparing Examples 1 and 6-7, it can be seen that the mass ratio of the composite chloride salt to the second molten liquid affects the preparation effect of the aluminum-scandium master alloy described in this invention. Controlling the mass ratio of the composite chloride salt to the second molten liquid at 1:(3-5) yields a better aluminum-scandium master alloy. If the amount of composite chloride salt added is too large, it increases the penetration of chloride ions into the alloy, or introduces harmful impurities such as hydrogen and sulfur into the melt due to its own purity problems (such as water or sulfate content), affecting the final performance of the alloy. If the amount of composite chloride salt added is too small, the melt viscosity is relatively high, which is not conducive to the final uniform distribution of scandium in the aluminum matrix and affects the final reduction rate of scandium.

[0060] As can be seen from the comparison between Example 1 and Comparative Example 1, the present invention directly uses the composite fluoride molten liquid to mix with the scandium source, which is conducive to the rapid and uniform dispersion and initial dissolution / reaction of the scandium source in the fluoride salt, creating a good thermodynamic and kinetic environment for subsequent reduction.

[0061] As can be seen from the comparison between Example 1 and Comparative Example 2, the present invention adds the composite chloride salt in batches under stirring. This stirring allows the chloride salt to be rapidly dispersed throughout the melt, ensuring full contact with the aluminothermic reduction products. This significantly improves reaction efficiency while forming a dense, continuous, and effectively air-barrier liquid protective layer on the melt surface. This protective layer not only prevents the oxidation of aluminum and scandium but also dissolves the reaction product alumina, reduces slag viscosity, and promotes reaction kinetics. This allows the entire reduction reaction to proceed safely and stably under atmospheric pressure, eliminating the need for expensive vacuum equipment and significantly reducing investment and production costs.

[0062] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing an aluminum-scandium master alloy, characterized in that, The preparation method includes the following steps: The composite fluoride molten liquid is mixed with a scandium source and subjected to a first melting treatment to obtain a first molten liquid; The first molten liquid is mixed with an aluminum source and subjected to a second melting process to obtain a second molten liquid; The composite chloride salt is mixed with the second melt in at least three batches and subjected to a third melt treatment to obtain the third melt. After slag removal from the third molten liquid, the aluminum-scandium master alloy is obtained through calcination, smelting, and cooling.

2. The preparation method according to claim 1, characterized in that, The temperatures of the first melting treatment, the second melting treatment, and the third melting treatment are each independently 900℃~1000℃; Preferably, the times for the first melting treatment, the second melting treatment, and the third melting treatment are each 30 min to 60 min independently.

3. The preparation method according to claim 1 or 2, characterized in that, The fluoride salts in the composite fluoride melt include NaF, AlF3, and Na3AlF6; Preferably, the mass ratio of NaF, AlF3 and Na3AlF6 in the composite fluoride molten liquid is (1~2):(0.1~1):(1.5~3.5).

4. The preparation method according to any one of claims 1-3, characterized in that, The scandium source includes scandium oxide; Preferably, the mass ratio of the composite fluoride molten liquid to the scandium source is (1.5~5):

1.

5. The preparation method according to any one of claims 1-4, characterized in that, The aluminum source includes elemental aluminum; Preferably, the mass ratio of the first molten liquid to the aluminum source is (0.1~0.4):

1.

6. The preparation method according to any one of claims 1-5, characterized in that, The complex chloride salt includes sodium chloride and potassium chloride; Preferably, the mass ratio of sodium chloride to potassium chloride is 1:(2~4); Preferably, the mass ratio of the composite chloride salt to the second molten liquid is 1:(3~5).

7. The preparation method according to any one of claims 1-6, characterized in that, The mixing process involves stirring. Preferably, the stirring speed is 200 rpm to 400 rpm; Preferably, the composite chloride salt is added to the second melt in 5 to 8 batches.

8. The preparation method according to any one of claims 1-7, characterized in that, The calcination temperature is 820℃~880℃; Preferably, the calcination time is 20 min to 40 min.

9. The preparation method according to any one of claims 1-8, characterized in that, The melting temperature is 920℃~980℃; Preferably, the melting time is 20 min to 40 min.

10. An aluminum-scandium master alloy, characterized in that, The aluminum-scandium master alloy is prepared by the preparation method according to any one of claims 1-9.

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