Seed alloys for refining magnesium alloys and their preparation methods

Abstract

This invention provides a seed alloy for refining magnesium alloys and its preparation method. The seed alloy comprises Al and multiple in-situ generated Al4C3 seed crystals, wherein the average grain size of the multiple Al4C3 seed crystals is 0.9 μm–1.5 μm, and at least a portion of the multiple Al4C3 seed crystals contain embedded nano-TiC. The seed alloy for refining magnesium alloys according to this invention exhibits high nucleation efficiency, enabling efficient and stable refining of Mg-Al alloys.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials, and specifically relates to a seed alloy for refining magnesium alloys and its preparation method. Background Technology

[0002] Magnesium alloys (e.g., Mg-Al alloys) have excellent specific strength, casting properties, and resistance to atmospheric corrosion. Their lightweight properties also meet the requirements of energy conservation and emission reduction, making them the most widely used magnesium alloys at room temperature. However, Mg-Al alloys have low absolute strength, poor plastic deformation ability, and are difficult to process and form, which limits their further application.

[0003] Grain refinement is a method that can simultaneously improve the strength and plasticity of alloys, especially for magnesium alloys with a close-packed hexagonal crystal structure and fewer slip systems, where grain refinement significantly improves their plasticity. However, current industrial applications of Mg-Al alloy grain refiners / methods still have various problems, such as complex processes, environmental pollution, and unstable results.

[0004] Al-C master alloys are promising for industrial application due to their ease of use, environmental friendliness, and high efficiency. However, some challenges remain in their preparation and optimization. These include the significant density and melting point differences between graphite and aluminum, their poor wettability, and the difficulty in effectively controlling the quantity and size of Al4C3 particles. Summary of the Invention

[0005] The purpose of this invention is to provide a seed alloy for refining magnesium alloys and a method for preparing the same, which can solve at least one of the above-mentioned technical problems.

[0006] One objective of this invention is to provide a seed alloy for refining magnesium alloys, wherein the seed alloy contains Al4C3 seed crystals embedded with nano-TiC. The Al4C3 seed crystals have uniform size and high nucleation efficiency, which can achieve efficient and stable refining of magnesium alloys.

[0007] Another objective of this invention is to provide a method for preparing a seed alloy for refining magnesium alloys. This preparation method is simple, environmentally friendly, and has broad prospects for industrial application.

[0008] According to one aspect of the present invention, a seed alloy for refining magnesium alloys is provided, the seed alloy comprising Al and a plurality of in-situ generated Al4C3 seed crystals, the plurality of Al4C3 seed crystals having an average grain size of 0.9 μm-1.5 μm, and at least a portion of the plurality of Al4C3 seed crystals having embedded nano-TiC.

[0009] Optionally, the size standard deviation of Al4C3 seed crystals is less than or equal to 0.2 μm.

[0010] Optionally, the average size of the nano-TiC is less than or equal to 200 nm.

[0011] Optionally, based on the total amount of the seed alloy, the content of Al4C3 seed crystals is greater than or equal to 0.3wt% and less than or equal to 5.0wt%.

[0012] Optionally, at least one portion of the Al4C3 seed crystals contains at least two nano-TiC crystals embedded within it.

[0013] According to another aspect of the present invention, a method for preparing a seed alloy for refining magnesium alloys is provided. The method includes: mixing aluminum powder and TiC powder and pressing them to form a block to be sintered; pre-sintering the block to be sintered at a temperature of 600°C-615°C under vacuum or inert gas protection to form a pre-sintered block; and sintering the pre-sintered block at a temperature of 640°C-665°C under vacuum or inert gas protection to form a sintered block.

[0014] Optionally, the block to be sintered may be pre-sintered at a temperature of 600℃-615℃ for 2h-4h.

[0015] Optionally, the pre-sintered block is sintered at a temperature of 640℃-665℃ for 1h-3h.

[0016] Optionally, the particle size of the TiC powder is 50nm-200nm.

[0017] According to another aspect of the present invention, a magnesium alloy is provided, wherein the magnesium alloy is refined using a magnesium alloy refinement seed alloy as described above.

[0018] In the seed alloy according to an embodiment of the present invention, the Al4C3 seed crystals have uniform size and high nucleation efficiency, which can effectively refine the α-Mg phase.

[0019] According to an embodiment of the present invention, by embedding nano-TiC within Al4C3 seed crystals, when refining Mg alloys using seed crystal alloys, the embedded TiC will continuously evolve into Al4C3. Therefore, Al4C3 seed crystals can always maintain high nucleation activity, improve nucleation efficiency, and achieve efficient refining.

[0020] According to embodiments of the present invention, nucleation efficiency can be improved by controlling the average grain size and size standard deviation of Al4C3 seeds.

[0021] The method for preparing seed alloys for refining magnesium alloys according to embodiments of the present invention is simple, environmentally friendly, and has broad prospects for industrial application. Attached Figure Description

[0022] Figure 1This is a microstructure image of a seed alloy for refining magnesium alloys according to an embodiment of the present invention, taken using a scanning electron microscope (SEM).

[0023] Figure 2 These are images of a magnesium alloy seed alloy for refining according to an embodiment of the present invention, analyzed using EPMA (electron probe microanalysis).

[0024] Figure 3A This is a microstructure diagram of AZ63 magnesium alloy without the addition of a seed alloy for refining magnesium alloys according to an embodiment of the present invention.

[0025] Figure 3B Microstructure diagram of AZ63 magnesium alloy, a seed alloy for refining magnesium alloys according to an embodiment of the present invention. Detailed Implementation

[0026] The following detailed embodiments are provided to aid the reader in gaining a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, upon understanding this disclosure, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will become apparent. For example, the order of operations described herein is merely illustrative and is not limited to those orders set forth herein, but may be changed as will become clear upon understanding this disclosure, except for operations that must occur in a specific order. Furthermore, for clarity and conciseness, descriptions of features known in the art may be omitted.

[0027] The features described herein may be implemented in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein are provided only to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein, which will become clear upon understanding the disclosure of this disclosure.

[0028] Unless otherwise defined, all terms used herein, including technical and scientific terms, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains upon understanding this disclosure. Unless expressly defined herein, terms such as those defined in a general dictionary shall be interpreted as having a meaning consistent with their meaning in the context of the relevant field and in this disclosure, and shall not be interpreted in an idealized or overly formalistic manner.

[0029] It should also be understood that the terms “comprising / including” or “having” as used throughout the specification indicate the presence of the said ingredient, step, or operation, but do not exclude the presence or addition of one or more other ingredients. Therefore, unless explicitly stated to the contrary, the words “comprising,” “including,” or “having” will be understood to imply the inclusion of the said ingredient, step, or operation but do not exclude any other ingredient, step, or operation.

[0030] Seed alloy for refining magnesium alloys

[0031] As described in the background section, Mg-Al alloys possess excellent specific strength, casting properties, and atmospheric corrosion resistance, making them the most widely used magnesium alloys at room temperature. However, excessively large α-Mg phases in Mg-Al alloys can lead to adverse effects such as decreased mechanical properties, reduced corrosion resistance, limited processing performance, and uneven distribution of the second phase. Therefore, it is necessary to refine the α-Mg phase.

[0032] Al4C3 seed crystals can be used to refine the α-Mg phase. For example, Al-C master alloys containing Al4C3 seed crystals can be added to Mg-Al alloys as a refining agent. However, the Al4C3 particles in current Al-C master alloys are large, non-uniform, few in number, and unevenly distributed, making them difficult to use effectively as a refining agent for the α-Mg phase.

[0033] This invention provides a seed alloy for refining magnesium alloys. The Al4C3 seed crystals in this seed alloy have uniform size and high nucleation efficiency, which can effectively refine the α-Mg phase.

[0034] According to an embodiment of the present invention, the seed alloy for refining magnesium alloys may include an aluminum (Al) matrix and an Al4C3 seed crystal distributed on the Al matrix and generated in situ, wherein the Al4C3 seed crystal contains embedded nano-TiC.

[0035] Figure 1 This is a microstructure image of a seed alloy for refining magnesium alloys according to an embodiment of the present invention, taken using a scanning electron microscope (SEM). Figure 2 These are images of a magnesium alloy seed alloy for refining according to an embodiment of the present invention, analyzed using EPMA (electron probe microanalysis).

[0036] like Figure 1 and Figure 2 As shown, a large number of small and uniformly sized particles are distributed on the Al matrix, combined with... Figure 2 SEM-EDS analysis revealed that the particle was an Al4C3 seed crystal, with nano-TiC embedded within it. Additionally, as... Figure 1 As shown, Al4C3 seeds embedded with nano-TiC are uniformly distributed on the Al matrix.

[0037] According to the present invention, Al4C3 seed crystals can be formed by the in-situ reaction of TiC particles with Al, and the reaction conditions can be controlled to prevent the TiC particles from reacting completely, thereby forming Al4C3 seed crystals with embedded TiC. By embedding nano-TiC within the Al4C3 seed crystals, when refining Mg-Al alloys using seed alloys, the embedded TiC will continuously evolve into Al4C3. Therefore, the Al4C3 seed crystals can always maintain high nucleation activity, improve nucleation efficiency, and achieve efficient refining. In addition, the Al4C3 seed crystals formed through in-situ reaction result in a clean and well-bonded interface between the seed crystal and the aluminum matrix, thereby fully leveraging the refining effect on α-Mg.

[0038] In addition, such as Figure 2 As shown, an Al4C3 particle may contain two or more nano-TiC particles, meaning that two or more nano-TiC particles may aggregate together to form an Al4C3 particle.

[0039] Furthermore, the seed alloy for refining magnesium alloys according to embodiments of the present invention may also include Al4C3 without embedded nano-TiC. That is, a portion of the TiC particles have completely reacted to form Al4C3.

[0040] According to embodiments of the present invention, the average particle size of Al4C3 seeds can be 0.9 μm-1.5 μm. When the average particle size of Al4C3 seeds is less than 0.9 μm, the nucleation ability is weak; furthermore, small-sized Al4C3 has high surface energy and easily agglomerates, resulting in low nucleation efficiency. When the average particle size of Al4C3 seeds is greater than 1.5 μm, the nucleation efficiency is low; furthermore, large-sized Al4C3 seeds easily settle, and the settled Al4C3 seeds cannot be fully used as nucleation sites, leading to low nucleation efficiency. According to the present invention, when the average particle size of Al4C3 seeds is 0.9 μm-1.5 μm, the nucleation efficiency can be improved. As an example, the average particle size of Al4C3 seeds can be 1.0 μm-1.3 μm.

[0041] According to embodiments of the present invention, the standard deviation of the Al4C3 seed size can be less than or equal to 0.2 μm. A smaller standard deviation indicates a more uniform size distribution of the Al4C3 seed and higher nucleation efficiency. When the standard deviation of the Al4C3 seed size is less than or equal to 0.2 μm, the nucleation efficiency can be improved. When the standard deviation of the Al4C3 seed size is greater than 0.2 μm, the size distribution of the Al4C3 seed is less uniform, leading to a decrease in nucleation efficiency. As an example, the standard deviation of the Al4C3 seed size can be less than or equal to 0.15 μm, or less than or equal to 0.09 μm. The lower limit of the standard deviation of the Al4C3 seed size according to the present invention is not specifically limited.

[0042] According to embodiments of the present invention, the average grain size of Al4C3 seeds in a seed alloy can be measured by the following method: preparing a seed alloy sample, obtaining an SEM image of the seed alloy sample using SEM, selecting at least five Al4C3 seeds in the SEM image, measuring the size of each Al4C3 seed, and calculating the average size of the at least five Al4C3 seeds. The size of each Al4C3 seed can be the average of its major axis and minor axis. Alternatively, the seed alloy sample can be prepared by cutting, mounting, grinding, and polishing; however, the sample preparation method of the present invention is not limited to these methods, and any solid sample preparation method known in the art can be used.

[0043] The standard deviation σ is used to characterize the dispersion of particle size distribution, and the calculation formula is as follows:

[0044]

[0045] In the formula: σ is the standard deviation of particle size. This represents the average particle size. d i For the first i Measurement size of each particle n This represents the total number of particles measured.

[0046] According to embodiments of the present invention, the content of Al4C3 seed crystals can be greater than or equal to 0.3 wt% based on the total amount of the seed alloy. If the content of Al4C3 seed crystals is less than 0.3 wt% based on the total amount of the seed alloy, then a large amount of seed alloy needs to be added when refining the Mg-Al alloy. The upper limit of the mass fraction of Al4C3 seed crystals is not specifically limited; as an example, the content of Al4C3 seed crystals can be less than or equal to 5.0 wt% or less than or equal to 3.0 wt% based on the total amount of the seed alloy. Figure 1 The Al4C3 seed content in the seed alloy shown is 5wt%.

[0047] According to embodiments of the present invention, the content of Al4C3 seed crystals can be measured using X-ray diffraction (XRD). However, the present invention is not limited thereto, and other mass measurement methods known in the art can also be used to measure the content of Al4C3 seed crystals in the seed alloy.

[0048] According to embodiments of the present invention, the TiC particles embedded within the Al4C3 seed crystal are nanoscale, for example, the size of the TiC particles can be less than or equal to 200 nm. If the size of the TiC particles is greater than 200 nm, the size of the Al4C3 seed crystal formed by the reaction may be too small, resulting in weak nucleation ability. The present invention does not specifically limit the lower limit of the TiC particle size, but considering that an excessively small TiC particle size may not sufficiently guarantee the nucleation activity of the Al4C3 seed crystal in which the TiC particles are embedded, the size of the TiC particles can be, for example, greater than or equal to 20 nm, greater than or equal to 30 nm, or greater than or equal to 50 nm.

[0049] For example, the size of TiC particles can be measured in the SEM image as described above. For example, five Al4C3 seed crystals can be selected in the SEM image, and the size of the TiC particles embedded within them can be measured, then the average value can be calculated. When there are no TiC particles within the selected Al4C3 seed crystals, the size can be recorded as 0. For example, the size of each TiC particle can be the average of its major and minor axis dimensions.

[0050] Preparation method of seed alloy for magnesium alloy refinement

[0051] The following describes a method for preparing a seed alloy for refining magnesium alloys according to an embodiment of the present invention, omitting descriptions that are repeated above to avoid redundancy.

[0052] The preparation method of the seed alloy for refining magnesium alloy according to an embodiment of the present invention may include: mixing aluminum powder and TiC powder and pressing them to form a block to be sintered (S1); pre-sintering the block to be sintered at a temperature of 600°C-615°C under vacuum or inert gas protection to form a pre-sintered block (S2); and sintering the pre-sintered block at a temperature of 640°C-665°C under vacuum or inert gas protection to form a sintered block (S3).

[0053] In step S1, aluminum powder and TiC powder are weighed according to the content of the target Al4C3 seed crystals and mixed evenly. A mixing device known in the art can be used for mixing. Then, the evenly mixed material can be pressed into a sintering block using isostatic pressing. The size of the sintering block is not specifically limited but can be reasonably determined as needed. According to embodiments of the present invention, the particle size of the TiC powder can be 50 nm-200 nm.

[0054] In step S2, during the pre-sintering process, a vacuum or inert gas is used for protection to prevent gas-absorbed oxidation. The purpose of pre-sintering the block to be sintered is to first wet the TiC-Al interface and initiate the interfacial reaction to generate Al4C3, providing a basis for the subsequent rapid reaction. According to an embodiment of the present invention, the pre-sintering time can be 2-4 hours.

[0055] If the pre-sintering temperature is less than 600℃ or the pre-sintering time is less than 2h, the TiC-Al interface may not be sufficiently wetted and the reaction may not begin, resulting in insufficient Al4C3 density in the final product. If the pre-sintering temperature is greater than 615℃ or the pre-sintering time is greater than 4h, the Al4C3 particles in the final product tend to aggregate.

[0056] As an example, the pre-sintering temperature can be 600℃-610℃, and the pre-sintering time can be 2.5h-3h.

[0057] In step S3, a vacuum or inert gas is used for protection during sintering to prevent gas-absorbed oxidation. Furthermore, sintering the pre-sintered block at a temperature of 640℃-665℃ improves reaction efficiency, allowing TiC and Al to fully react and generate TiC-embedded Al4C3 seed crystals. According to an embodiment of the present invention, the sintering time can be 1h-3h.

[0058] If the sintering temperature is less than 640℃ or the sintering time is less than 1 hour, it may not be possible to generate TiC-embedded Al4C3 seeds, and the size of the generated TiC-embedded Al4C3 seeds may be too small. If the sintering temperature is greater than 665℃ or the sintering time is greater than 3 hours, the final Al4C3 particles tend to grow.

[0059] As an example, the sintering temperature can be 650℃-655℃, and the sintering time can be 1.5h-2.5h.

[0060] As an example, the pre-sintered blocks can be placed in a vacuum sintering furnace to perform the above steps S2 and S3. For example, the pre-sintered blocks can be placed in a vacuum sintering furnace, held at 600℃-615℃ for 2h-4h, then gradually heated to 640℃-665℃ and held for 1h-3h, and then cooled with the furnace.

[0061] According to an embodiment of the present invention, in steps S2 and S3, the temperature is controlled below the melting point of aluminum, so that Al and TiC react in situ, which can ensure that the Al4C3 seed crystals are small and uniform in size.

[0062] According to an embodiment of the present invention, after sintering is completed, the sintered block is cooled in the furnace. Additionally, the sintered block can be deformed according to the desired seed alloy shape. Before deformation, the sintered block can be first heated and then extruded to the desired shape. For example, the sintered block can be processed into a rod shape.

[0063] In the above description, only Al powder and TiC powder are mentioned as raw materials for preparation. Al powder and TiC powder are the main raw materials for the reaction. Binders, sintering aids and other auxiliary materials can also be added as needed. This invention does not impose specific limitations on this, nor does it intend to exclude them from the scope of protection of this application.

[0064] The method for preparing seed alloys for refining magnesium alloys according to embodiments of the present invention is simple, environmentally friendly, and has broad prospects for industrial application.

[0065] Magnesium alloy

[0066] The magnesium alloys in the embodiments of the present invention can be AZ31, AZ63 or AZ91, etc., however the present invention is not limited to these, as long as they are magnesium alloys containing α-Mg particles.

[0067] The α-Mg particles in the magnesium alloy described above can be refined using a seed alloy according to an embodiment of the present invention. The refining temperature can be 690℃-720℃, and the holding time can be 10min-120min.

[0068] In addition, according to an embodiment of the present invention, the amount of seed alloy added to every 100 parts by weight of magnesium alloy may be 0.1-1 parts by weight.

[0069] Examples and comparisons

[0070] First, aluminum powder and TiC powder are mixed, with 8 parts by weight of TiC powder added for every 100 parts by weight of Al. The well-mixed powder is then pressed into sintering blocks.

[0071] The block to be sintered was placed in a vacuum furnace, and pre-sintering was performed according to the pre-sintering temperature and pre-sintering time listed in Table 1. Sintering was then performed according to the sintering temperature and sintering time listed in Table 1, yielding Comparative Example 1. * Examples 2 to 4 and Comparative Example 5 * Seed alloys.

[0072] The above-mentioned seed alloy samples were prepared by cutting, embedding, grinding, and polishing. SEM images of the samples were then obtained using SEM. Ten Al4C3 seed crystals and TiC particles were selected from the SEM images, and the size of each Al4C3 seed crystal and TiC particle was measured. The average grain size and standard deviation of the Al4C3 seed crystals, and the average size of the TiC particles were calculated. The size of each Al4C3 seed crystal is the average of its major and minor axis dimensions, and the size of each TiC particle is the average of its major and minor axis dimensions. The measured average grain size, standard deviation of the size of the Al4C3 seed crystals, and average size of the TiC particles are listed in Table 1.

[0073] In addition, using Comparative Example 1 respectively * Examples 2 to 4 and Comparative Example 5 *A seed alloy was used to refine AZ63 magnesium alloy. The refining treatment temperature was 700℃, and the holding time was 15 min. The amount of seed alloy added was 0.5 parts by weight per 100 parts by weight of AZ63 magnesium alloy.

[0074] AZ63 magnesium alloy samples before and after refinement were prepared by cutting, inlaying, grinding, and polishing. Images were then obtained using an optical microscope or scanning electron microscope. Ten α-Mg particles were selected from the images, and the size of each α-Mg particle was measured, and the average size of the ten α-Mg particles was calculated. The size of each α-Mg particle is the average of its major axis and minor axis. The average size of the α-Mg particles in the AZ63 magnesium alloy sample before refinement was 545 μm. The average size of the α-Mg particles in the AZ63 magnesium alloy sample after refinement is listed in Table 1.

[0075] Table 1

[0076]

[0077] As shown in Table 1, in Examples 2 to 4, the pre-sintering temperature was in the range of 600℃-615℃, the pre-sintering time was in the range of 2h-4h, the sintering temperature was in the range of 640℃-665℃, and the sintering time was in the range of 1h-3h. The average grain size of the generated Al4C3 seeds was in the range of 0.9μm-1.5μm, the size standard deviation was less than or equal to 0.2μm, and the average size of TiC was less than or equal to 200nm. Furthermore, as shown in Table 1, using the seed alloys of Examples 2 to 4 to refine the AZ63 magnesium alloy, the average size of the α-Mg particles was refined to below 170μm. Therefore, when the pre-sintering temperature is within the range of 600℃-615℃, the pre-sintering time is within the range of 2h-4h, and the sintering temperature is within the range of 640℃-665℃ with a sintering time within the range of 1h-3h, the average grain size of the generated Al4C3 seeds meets the requirement of 0.9μm-1.5μm, the size standard deviation meets the requirement of less than or equal to 0.2μm, and the average size of TiC meets the requirement of less than or equal to 200nm. Under these conditions, the α-Mg particles in the AZ63 magnesium alloy can be refined to below 170μm.

[0078] In contrast, in Comparative Example 1 * In Comparative Example 5, the pre-sintering temperature and sintering temperature were too low, and the pre-sintering time and sintering time were too short. Therefore, the average grain size of the generated Al4C3 seeds was small, at 0.6 μm, falling below the 0.9 μm-1.5 μm range, and the size standard deviation was also large, exceeding 0.2 μm. Furthermore, the average size of the remaining TiC was large, at 250 nm, exceeding 200 nm. *In the above example, the pre-sintering temperature and sintering temperature were too high, and the pre-sintering time and sintering time were too long. Therefore, the average grain size of the generated Al4C3 seeds was relatively large, at 1.7 μm, exceeding the range of 0.9 μm-1.5 μm, and the size standard deviation was also large, exceeding 0.2 μm. Furthermore, the average size of the remaining TiC was relatively small, at 16 nm. Additionally, as shown in Table 1, Comparative Example 1 was used... * and 5 * The seed alloy was used to refine the AZ63 magnesium alloy, resulting in α-Mg particles with average sizes of 345 μm and 276 μm, respectively. This indicates that when the pre-sintering temperature, pre-sintering time, sintering temperature, and sintering time are outside the range of this invention, the average particle size of the generated Al4C3 seeds is too small or too large, with a large standard deviation in size, and the average size of TiC is too large or too small. In such cases, the seed alloy cannot effectively refine the α-Mg particles in the AZ63 magnesium alloy.

[0079] Figure 3A This is a microstructure diagram of AZ63 magnesium alloy without the addition of a seed alloy for refining magnesium alloys according to an embodiment of the present invention. Figure 3B Microstructure diagram of AZ63 magnesium alloy, a seed alloy for refining magnesium alloys according to an embodiment of the present invention, is added. Specifically, Figure 3B The microstructure diagram corresponds to the refined microstructure diagram of AZ63 magnesium alloy using Example 4.

[0080] like Figure 3A As shown, the average size of α-Mg particles in the AZ63 magnesium alloy sample before refinement was 545 μm, and the average size of α-Mg particles after refinement of the AZ63 magnesium alloy using Example 4 was 155 μm.

[0081] In addition, when the seed alloy according to the embodiment of the present invention is used to refine the AZ31 magnesium alloy, the α-Mg particles can be refined from 800μm-900μm to about 200μm; when the seed alloy according to the embodiment of the present invention is used to refine the AZ91 magnesium alloy, the α-Mg particles can be refined from about 400μm to about 100μm.

[0082] As described above, the magnesium alloy seed alloy for refining and the manufacturing method thereof according to the present invention can achieve beneficial technical effects, not limited to those described below.

[0083] In the seed alloy according to an embodiment of the present invention, the Al4C3 seed crystals have uniform size and high nucleation efficiency, which can effectively refine the α-Mg phase.

[0084] According to an embodiment of the present invention, by embedding nano-TiC within Al4C3 seed crystals, when refining Mg-Al alloys using seed crystal alloys, the embedded TiC will continuously evolve into Al4C3. Therefore, Al4C3 seed crystals can always maintain high nucleation activity, improve nucleation efficiency, and achieve efficient refining.

[0085] According to embodiments of the present invention, nucleation efficiency can be improved by controlling the average grain size and size standard deviation of Al4C3 seeds.

[0086] The method for preparing seed alloys for refining magnesium alloys according to embodiments of the present invention is simple, environmentally friendly, and has broad prospects for industrial application.

[0087] While this disclosure has been described in conjunction with what is now considered to be actual embodiments, it should be understood that the invention is not limited to the disclosed embodiments. Rather, it is intended to cover various variations and equivalents that are included within the spirit and scope of the appended claims.

Claims

1. A seed alloy for refining magnesium alloys, characterized in that, The seed alloy comprises Al and multiple in-situ generated Al4C3 seeds, the average grain size of the multiple Al4C3 seeds being 0.9 μm-1.5 μm, and at least a portion of the multiple Al4C3 seeds embedding nano-TiC. The size standard deviation of Al4C3 seed crystals is less than or equal to 0.20 μm.

2. The seed alloy for refining magnesium alloys according to claim 1, characterized in that, The average grain size of the plurality of Al4C3 seeds is 1.2μm-1.5μm, and the size standard deviation of the Al4C3 seeds is less than or equal to 0.15μm.

3. The seed alloy for refining magnesium alloys according to claim 1, characterized in that, The average size of the nano-TiC is less than or equal to 200 nm.

4. The seed alloy for refining magnesium alloys according to claim 1, characterized in that, Based on the total amount of the seed alloy, the content of Al4C3 seed crystals is greater than or equal to 0.3wt% and less than or equal to 5.0wt%.

5. The seed alloy for refining magnesium alloys according to claim 1, characterized in that, At least one portion of the Al4C3 seed crystals contains at least two nano-TiC crystals embedded within it.

6. A method for preparing a seed alloy for refining magnesium alloys according to any one of claims 1 to 5, characterized in that, The preparation method includes: Aluminum powder and TiC powder are mixed and then pressed to form a block to be sintered. In a vacuum or inert gas protected environment, the block to be sintered is pre-sintered at a temperature of 600℃-615℃ to form a pre-sintered block. The pre-sintered block is sintered in a vacuum or inert gas protected environment at a temperature of 640℃-665℃ to form a sintered block.

7. The preparation method according to claim 6, characterized in that, The blocks to be sintered are pre-sintered at a temperature of 600℃-615℃ for 2-4 hours.

8. The preparation method according to claim 6, characterized in that, The pre-sintered blocks were sintered at a temperature of 640℃-665℃ for 1-3 hours.

9. The preparation method according to claim 6, characterized in that, The TiC powder has a particle size of 50nm-200nm.

10. A magnesium alloy, characterized in that, The magnesium alloy is refined using a seed alloy for refining magnesium alloys according to any one of claims 1 to 5.

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