Magnesium-zirconium alloy, method for preparing the same, and use thereof

Abstract

The application relates to a magnesium-zirconium alloy and a preparation method and application thereof. The preparation method comprises the following steps: heating metal magnesium to be melted to obtain a metal magnesium liquid; adding metal zirconium into the metal magnesium liquid to form a mixed melt, stirring for 10-15 min, and then performing ultrasonic treatment on the mixed melt while keeping the stirring, to obtain a pre-formed melt; and forming the pre-formed melt to obtain the magnesium-zirconium alloy. In the preparation method, the combination of the stirring and the ultrasonic treatment can promote the dissolution of metal zirconium particles, and the magnesium-zirconium alloy with high zirconium content, fine particles and dispersed distribution is obtained.

Description

Technical Field

[0001] This application relates to the field of alloy materials technology, and in particular to a magnesium-zirconium alloy, its preparation method, and its application. Background Technology

[0002] Zirconium is one of the grain-refining elements in magnesium alloys, and it can also reduce the alloy's tendency to hot crack, thereby improving the alloy's strength, toughness, and creep resistance. Currently, the main method for adding zirconium to magnesium alloys is through magnesium-zirconium alloys. Specifically, this magnesium-zirconium alloy is added as an intermediate to pure magnesium melt, and then the zirconium in the magnesium-zirconium alloy dissolves in the melt. After the melt is formed, a zirconium-containing magnesium alloy is obtained. The grain-refining mechanisms of magnesium alloys mainly include peritectic reactions and heterogeneous nucleation. Therefore, during the preparation process, both dissolved and undissolved zirconium particles in the magnesium-zirconium alloy will affect the grain refinement of the magnesium alloy, thus affecting its overall performance. Therefore, in actual production, it is generally required that the zirconium particles in the magnesium-zirconium alloy be small and uniformly dispersed to ensure that the zirconium has suitable solubility, thereby forming an appropriate amount of dissolved zirconium particles and small undissolved zirconium particles during the preparation of the magnesium alloy.

[0003] The main methods for preparing magnesium-zirconium alloys include the magnesothermal reduction method and the metal doping method. In the magnesothermal reduction method, the reduced zirconium particles are very fine and easily dissolve into the magnesium matrix, resulting in a high content of soluble zirconium in the magnesium matrix. However, the magnesothermal reduction method still struggles to meet practical requirements in terms of product quality and production cost. The metal doping method involves gradually dissolving large raw material zirconium particles into finer zirconium particles, which then diffuse into the magnesium matrix. However, the degree of zirconium particle dissolution is affected by the raw material and its surface activation level. In actual production, a significant amount of undissolved zirconium particles often remain, resulting in a lower actual zirconium content in the resulting alloy. Furthermore, insufficient dissolved zirconium reduces the grain refinement effect of the zirconium particles, thus affecting the overall performance of the resulting magnesium-zirconium alloy. In addition, the aforementioned magnesium-zirconium alloys contain a large number of undissolved zirconium particles, which are not only large in size but also reduce the uniformity of zirconium in the alloy.

[0004] Therefore, how to provide a magnesium-zirconium alloy with high zirconium content, fine and dispersed zirconium particles, and its preparation method has become an urgent technical problem to be solved. Summary of the Invention

[0005] Therefore, it is necessary to provide a magnesium-zirconium alloy with high zirconium content, fine and dispersed zirconium particles, its preparation method, and its application.

[0006] A first aspect of this application provides a method for preparing a magnesium-zirconium alloy, comprising the following steps:

[0007] Magnesium metal is heated until it melts to obtain molten magnesium metal;

[0008] Zirconium metal is added to molten magnesium to form a mixed melt, and the mixture is stirred for 10 to 15 minutes. Then, while maintaining stirring, the mixed melt is ultrasonically treated to obtain a preformed melt.

[0009] The preformed melt is shaped to obtain a magnesium-zirconium alloy.

[0010] In the above preparation method, combining stirring and ultrasonic treatment promotes the dissolution of zirconium particles, resulting in a magnesium-zirconium alloy with high zirconium content, fine particles, and a dispersed distribution. After stirring the mixed melt for 10-15 minutes, some of the zirconium particles in the raw material have dissolved, and the particle size has decreased, allowing them to suspend in the mixed melt. Introducing ultrasonic treatment at this point, without affecting the melt flow state, works in conjunction with stirring to further dissolve the zirconium particles, thereby obtaining a magnesium-zirconium alloy with high zirconium content, fine zirconium particles, and a uniform component distribution. Furthermore, the above preparation method can reduce the melting temperature and shorten the melting time, thereby reducing energy consumption and improving production efficiency.

[0011] In some embodiments, the ultrasonic treatment time is 10 min to 70 min.

[0012] In some embodiments, the power of the ultrasonic treatment is 0.4 kW to 5 kW.

[0013] In some embodiments, the step of heating the magnesium metal to melting is performed by induction heating at a frequency of 1400 Hz to 1500 Hz.

[0014] In some embodiments, the steps of stirring and ultrasonicating the mixed melt are performed using induction heating at a frequency of 20 Hz to 200 Hz.

[0015] In some embodiments, the stirring process includes the following steps: performing a first stage stirring, a second stage stirring and a third stage stirring in sequence, wherein the first stage stirring includes a first method of stirring, the second stage stirring includes a second method of stirring, and the third stage stirring includes at least one of the first method of stirring, the second method of stirring and the third method of stirring.

[0016] The first stirring method is used to form a double-circulation flow of the mixed melt with the middle upward and the sides downward; the second stirring method is used to form a double-circulation flow of the mixed melt with the middle downward and the sides upward; the third stirring method is used to form a double-circulation flow of the upper mixed melt with the middle upward and the sides downward, and to form a double-circulation flow of the lower mixed melt with the middle downward and the sides upward.

[0017] In some embodiments, the first stage of stirring lasts for 20 to 50 minutes, and after the first stage of stirring has been carried out for 10 to 15 minutes, ultrasonic treatment is started while the first stage of stirring is maintained, so that the mixed melt is simultaneously subjected to stirring and ultrasonic treatment.

[0018] In some embodiments, the second stage of stirring takes 0 to 20 minutes.

[0019] In some embodiments, the third stage of stirring takes 6 to 40 minutes.

[0020] In some embodiments, the third stage of mixing includes a third-mode mixing, a second-mode mixing, and a first-mode mixing performed in a sequential cycle.

[0021] In some embodiments, the magnesium-zirconium alloy is prepared using an induction furnace, which is equipped with an ultrasonic rod for ultrasonic treatment, and there is a gap of 70 mm to 150 mm between the bottom of the ultrasonic rod and the bottom wall of the induction furnace.

[0022] A second aspect of this application provides a magnesium-zirconium alloy prepared using the method of the first aspect.

[0023] A third aspect of this application provides the application of the magnesium-zirconium alloy of the second aspect in the preparation of magnesium alloy articles.

[0024] A fourth aspect of this application provides a magnesium alloy article made of a magnesium-zirconium alloy as described in the second aspect. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the first stirring method in one embodiment;

[0026] Figure 2 This is a schematic diagram of the second stirring method in one embodiment;

[0027] Figure 3 This is a schematic diagram of the third stirring method in one embodiment;

[0028] Figure 4 The images shown are actual fracture surfaces of magnesium-zirconium alloy ingots from Example 1. (a) is ingot #1, and (b) is ingot #14.

[0029] Figure 5 The images shown are actual fracture surfaces of magnesium-zirconium alloy ingots from Example 3. (c) is ingot #1, and (d) is ingot #14.

[0030] Figure 6 The following are actual fracture images of magnesium-zirconium alloy ingots for Comparative Example 1: (e) is ingot #1 and (f) is ingot #14.

[0031] Figure 7 The images shown are actual fracture surfaces of magnesium-zirconium alloy ingots for Comparative Example 2. (g) is ingot #1 and (h) is ingot #14.

[0032] Figure 8 The image shows the microstructure of the magnesium-zirconium alloy in Example 1.

[0033] Figure 9 This is a microstructure diagram of the magnesium-zirconium alloy in Example 3;

[0034] Figure 10 The image shows the microstructure of the magnesium-zirconium alloy in Comparative Example 1. Detailed Implementation

[0035] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] In this description, it should be understood that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In this description, "multiple" means two or more, unless otherwise explicitly specified.

[0038] The weights of the relevant components mentioned in the embodiments herein can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments herein is within the scope disclosed in the embodiments herein. Specifically, the weights mentioned in the embodiments herein can be well-known units of mass in the chemical industry, such as μg, mg, g, and kg.

[0039] Currently, zirconium in magnesium alloys is mainly added via magnesium-zirconium alloys as intermediates. The zirconium content, particle size, and dispersion of zirconium particles in magnesium-zirconium alloys all affect the zirconium content, thus influencing grain refinement and ultimately the alloy's properties. Therefore, practical applications require fine zirconium particles and a high zirconium content in magnesium-zirconium alloys, especially a high content of soluble zirconium in the magnesium matrix. Metal doping with zirconium surface activation has proven to be an effective method for preparing high-zirconium-content magnesium-zirconium alloys. However, the solubility of zirconium particles in metal doping is affected by the type of raw material and its surface activation degree. In actual production, the solubility of zirconium particles is relatively low, resulting in a significant amount of residual zirconium particles in the melt. These residual particles are removed in subsequent processing, leading to a low actual zirconium yield in the resulting magnesium-zirconium alloy. Furthermore, the surface activation process for zirconium particles is complex, which reduces production efficiency. Based on the above problems, the inventors of this application have discovered that by improving the stirring process of the traditional metal doping method, the solubility of the raw material zirconium particles can be effectively improved, thereby obtaining a magnesium-zirconium alloy with high zirconium content, fine zirconium particles, and dispersed distribution.

[0040] One embodiment of this application provides a method for preparing a magnesium-zirconium alloy, comprising the following steps S10 to S30.

[0041] S10: Heat metallic magnesium until it melts to obtain molten metallic magnesium.

[0042] In some embodiments, prior to step S10, a step of preparing raw materials according to the composition of the magnesium-zirconium alloy is included.

[0043] In some embodiments, the zirconium content is 1 wt% to 30 wt% based on the total mass of the magnesium-zirconium alloy.

[0044] In some embodiments, induction heating is used in step S10, with a frequency of 1400 Hz to 1500 Hz. Using a relatively high induction frequency to heat magnesium metal can promote its melting and improve production efficiency.

[0045] In some embodiments, the melting temperature of step S10 is 740 ℃~750 ℃.

[0046] S20: Add zirconium metal to molten magnesium to form a mixed melt, stir for 10 min to 15 min, and then sonicate the mixed melt while maintaining stirring to obtain a preformed melt.

[0047] Understandably, only stirring is performed at the beginning of step S20. Then, after 10-15 minutes of stirring, ultrasonic treatment begins while stirring continues, thus simultaneously subjecting the molten mixture to both stirring and ultrasonic treatment. Furthermore, the stirring and ultrasonic treatments operate independently, working in tandem to effectively promote the dissolution of zirconium and improve the compositional homogeneity of the molten mixture. Specifically, at the beginning of step S20, the newly added zirconium particles are relatively large. Introducing ultrasonic treatment at this time could hinder the circulation of zirconium particles in the molten mixture, affecting the effectiveness of the stirring and causing zirconium particles to deposit at the bottom of the molten mixture, reducing the degree of dissolution. However, after 10-15 minutes of stirring, the zirconium particles partially dissolve under the influence of stirring. At this point, the undissolved zirconium particles are smaller and can be uniformly suspended in the molten mixture. Introducing ultrasonic treatment at this time has almost no impact on the circulation of zirconium particles in the melt and can further promote the dissolution of undissolved zirconium particles. It also facilitates the diffusion of the dissolved zirconium particles, thereby improving the compositional homogeneity of the magnesium-zirconium alloy. Furthermore, ultrasonic treatment can effectively reduce oxidation inclusions caused by stirring, lower the sealing requirements of the production equipment, and reduce the amount of protective gas used during production. It should be noted that this embodiment uses ultrasonic treatment to assist stirring to improve the solubility of metallic zirconium. Stirring is performed simultaneously with ultrasonic treatment; that is, stirring is carried out throughout step S20, and the stirring and ultrasonic treatments operate independently. Starting and stopping the ultrasonic treatment, as well as changes in ultrasonic parameters, have almost no impact on the normal operation of the stirring treatment. Similarly, changes in the frequency and power of the stirring treatment, and switching of the stirring mode, also have almost no impact on the normal operation of the ultrasonic treatment.

[0048] Optionally, ultrasonic treatment may be performed after the stirring process has lasted for 10, 12, 14, or 15 minutes. Understandably, other options within the range of 10 to 15 minutes may also be selected.

[0049] In some of these embodiments, the metallic zirconium includes sponge zirconium.

[0050] In some embodiments, the melting temperature of step S20 is 720 ℃~770 ℃.

[0051] In some embodiments, the metallic zirconium in step S20 is added at a melting temperature of 740 °C to 750 °C.

[0052] In some embodiments, the ultrasonic treatment time is 10 min to 70 min. Understandably, if the ultrasonic treatment time is too short, it cannot effectively promote the dissolution of metallic zirconium; if the time is too long, it will result in excessively fine zirconium particles, exacerbating zirconium particle agglomeration at the grain boundaries of the magnesium matrix. Optionally, the ultrasonic treatment time can be 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, or 70 min. Understandably, the ultrasonic treatment time can also be selected from other options within the range of 10 min to 70 min.

[0053] In some embodiments, the power of the ultrasonic treatment is 0.4 kW to 5 kW.

[0054] In some embodiments, the ultrasonic treatment is performed using ultrasound at a frequency of 20 ± 1 kHz.

[0055] By controlling the power of the ultrasonic treatment to achieve a suitable intensity, and combining this with the ultrasonic time and frequency within the aforementioned range, a better ultrasonic effect can be achieved. It should be noted that in actual production, the equipment may experience some frequency fluctuations; therefore, the frequency of the ultrasonic treatment described above is limited to a fluctuation range of 1 kHz.

[0056] In some embodiments, in step S20, induction heating is employed, with a frequency of 20 Hz to 200 Hz. Optionally, the induction heating frequency can be 20 Hz, 40 Hz, 60 Hz, 80 Hz, 100 Hz, 120 Hz, 140 Hz, 160 Hz, 180 Hz, or 200 Hz. Using an induction heating frequency within the above range allows for more uniform stirring.

[0057] In some embodiments, the stirring process includes the following steps: sequentially performing a first-stage stirring, a second-stage stirring, and a third-stage stirring, wherein the first-stage stirring includes a first-mode stirring, the second-stage stirring includes a second-mode stirring, and the third-stage stirring includes at least one of the first-mode stirring, the second-mode stirring, and the third-mode stirring.

[0058] The first stirring method is used to form a double-circulation flow of the mixed melt with the middle upward and the sides downward; the second stirring method is used to form a double-circulation flow of the mixed melt with the middle downward and the sides upward; the third stirring method is used to form a double-circulation flow of the upper mixed melt with the middle upward and the sides downward, and to form a double-circulation flow of the lower mixed melt with the middle downward and the sides upward.

[0059] Understandably, the first stage of stirring corresponds to the early stage of smelting, the second stage to the middle stage, and the third stage to the later stage. Staged stirring of the molten mixture allows for targeted stirring at different stages of the smelting process, thereby improving the effectiveness of the stirring treatment. Furthermore, the first stage stirring uses a relatively strong first-mode stirring, which effectively promotes the dissolution of zirconium particles; while the second stage stirring uses a relatively weaker second-mode stirring, which keeps the zirconium particles suspended in the lower part of the molten mixture, preventing them from settling at the bottom. This allows the zirconium particles to be subjected to ultrasonic treatment as much as possible, further dissolving them. The third stage stirring uses one or more specific stirring methods to improve the compositional homogeneity of the molten mixture. It should be noted that actual experiments have shown that the stirring force of the three methods is greater in the first mode than in the second mode, and greater in the third mode than in the second mode.

[0060] Furthermore, please refer to the attached diagram for information on the three different stirring methods. Figures 1-3 These are schematic diagrams illustrating the first, second, and third stirring methods in this embodiment. Figure 1 The first method shown is mixing and Figure 2 The second stirring method shown is a whole-body stirring method. The difference between the two lies in the flow direction of the mixed melt. That is, under the first stirring method, the mixed melt forms a circulating flow with the center flowing upward and the sides flowing downward; under the second stirring method, the mixed melt forms a circulating flow with the center flowing downward and the sides flowing upward. Figure 3 The third stirring method shown is a traditional electromagnetic induction stirring method, in which the molten mixture is divided into two sections and four zones. It should be noted that the above three stirring methods can be adjusted and switched according to the operating parameters of the production equipment itself. For example, in the preparation of magnesium-zirconium alloy in a three-phase induction furnace, the first, second, and third stirring methods can be obtained by adjusting the process parameters such as the power supply method of the three-phase induction furnace.

[0061] In some embodiments, the first stage of stirring lasts for 20 to 50 minutes, and after 10 to 15 minutes of stirring, ultrasonic treatment begins while the first stage of stirring is maintained, so that the mixed melt is simultaneously subjected to stirring and ultrasonic treatment. Understandably, in this embodiment, the stirring process is performed in stages, and ultrasonic treatment is added in the first stage of stirring (i.e., the early stage of melting), and ultrasonic treatment is only performed after the first stage of stirring has been underway for a period of time, allowing the zirconium particles to remain suspended in the mixed melt.

[0062] In some embodiments, the second stage of stirring takes 0 to 20 minutes.

[0063] In some embodiments, the third stage of stirring takes 6 to 40 minutes.

[0064] In some embodiments, the melting temperature of the first stage of stirring is 740 ℃~750 ℃.

[0065] In some embodiments, the melting temperature of the second stage stirring is 730 ℃~750 ℃.

[0066] In some embodiments, the melting temperature of the third stage stirring is 720 ℃~740 ℃.

[0067] Melting efficiency can be improved by adjusting the melting temperature at different stirring stages.

[0068] In some embodiments, the third stage of mixing includes first-mode mixing, second-mode mixing, or third-mode mixing.

[0069] In some embodiments, the third-stage mixing includes at least two of the following: first-mode mixing, second-mode mixing, and third-mode mixing. Specifically, the mixing can be a combination of two mixing methods, such as first-mode mixing and second-mode mixing, second-mode mixing and third-mode mixing, or a combination of first-mode mixing and third-mode mixing; it can also be a combination of first-mode mixing, second-mode mixing, and third-mode mixing. It should be noted that there is no specific order in which the above-mentioned mixing methods are combined. Combining multiple different mixing methods can further improve the uniformity of the mixing.

[0070] In some embodiments, the third-stage stirring includes sequentially cycling through third-mode stirring, second-mode stirring, and first-mode stirring. Understandably, in this embodiment, stirring and mixing performed in a specific order and manner can significantly improve the dispersibility of the components in the mixed melt, thereby producing a magnesium-zirconium alloy with uniform component distribution. Furthermore, compared to traditional mechanical stirring, the combination of electromagnetic induction stirring and ultrasonic treatment in this embodiment can avoid secondary contamination and gas entrainment, reduce impurities and porosity in the product, and also lower the melting temperature and reduce energy consumption.

[0071] Furthermore, the third stage of mixing includes alternating third-mode mixing, second-mode mixing, and first-mode mixing, which are performed 1 to 4 times in sequence. The time for each third-mode mixing, second-mode mixing, and first-mode mixing is independently selected from 2 min to 10 min, and the total time for the third stage of mixing is 6 min to 40 min.

[0072] In some embodiments, the third-stage stirring includes alternating cycles of third-mode stirring, second-mode stirring, and first-mode stirring, with ultrasonic treatment being stopped simultaneously with the start of the third-stage stirring. Understandably, in this embodiment, the third-stage stirring includes multiple different stirring methods, requiring multiple switching between them. If ultrasonic treatment continues at this time, it will affect the flow state of the mixed melt and reduce its component homogeneity. Furthermore, since the mixed melt has already undergone first-stage and second-stage stirring during the third-stage stirring, if ultrasonic treatment continues for an excessively long time, it will result in zirconium particles that are too small, thereby exacerbating the agglomeration of zirconium particles at the grain boundaries of the magnesium matrix. Therefore, stopping ultrasonic treatment at the start of the third-stage stirring not only further improves the component homogeneity of the magnesium-zirconium alloy but also increases the zirconium content.

[0073] In some embodiments, stirring is performed in a first manner at an induction frequency of 80 Hz to 110 Hz, stirring is performed in a second manner at an induction frequency of 60 Hz to 80 Hz, and stirring is performed in a third manner at an induction frequency of 80 Hz to 100 Hz.

[0074] In some embodiments, stirring is performed in a first manner at an induction power of 40 kW to 60 kW, stirring is performed in a second manner at an induction power of 35 kW to 50 kW, and stirring is performed in a third manner at an induction power of 40 kW to 50 kW.

[0075] The strength of the stirring force can be altered and the stirring effect improved by adjusting the induction power and frequency under different stirring methods. It should be noted that the aforementioned frequency and power can be adjusted by modifying the operating parameters of the production equipment.

[0076] In some embodiments, the magnesium-zirconium alloy is prepared using an induction furnace, which is equipped with an ultrasonic rod for ultrasonic treatment, and there is a gap of 70 mm to 150 mm between the bottom of the ultrasonic rod and the bottom wall of the induction furnace.

[0077] Understandably, the ultrasonic effect of the ultrasonic rod is mainly concentrated on its bottom end face. The effective range of ultrasonic treatment is related to the emission point on the end face. Therefore, a gap needs to be set between the bottom of the ultrasonic rod and the bottom wall of the induction furnace to ensure the range of ultrasonic action and thus fully utilize the ultrasonic treatment effect. Furthermore, a better ultrasonic effect can be achieved when the distance between the bottom of the ultrasonic rod and the bottom wall of the induction furnace is 70 mm to 150 mm. When the distance is less than 70 mm, the ultrasonic treatment effect is mainly concentrated at the bottom of the induction furnace, and it is impossible to ultrasonically treat the large zirconium particles concentrated in the middle and lower parts of the melt. When the distance is greater than 150 mm, the ultrasonic treatment effect is mainly concentrated in the middle and upper parts of the induction furnace, and the large zirconium particles in the middle and lower parts cannot be subjected to strong ultrasonic action. Optionally, the above-mentioned distances are 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, or 150 mm.

[0078] In some embodiments, the number of ultrasonic rods is one or more. Understandably, the specific number of ultrasonic rods is determined by considering multiple factors such as melt volume, ultrasonic rod specifications, and ultrasonic effect requirements, combined with corresponding simulation calculations and experiments. This application does not limit the specific number of ultrasonic rods. For example, when using a device with a melt pool depth of approximately 400 mm and a diameter of approximately 205 mm for production, one ultrasonic rod is sufficient. Furthermore, theoretical calculations show that one ultrasonic rod can be inserted into the melt surface with a diameter less than or equal to 300 mm, centered on the ultrasonic rod.

[0079] In some embodiments, the induction furnace is a three-phase induction furnace.

[0080] S30: Forms the pre-formed melt to obtain a magnesium-zirconium alloy.

[0081] In some embodiments, a point-casting method is used to form the preformed melt. Furthermore, the preformed melt flows out from a casting port on the side of the induction furnace to achieve point-casting. Understandably, by introducing ultrasonic treatment in step S20, the casting characteristics of the mixed melt can be improved, effectively avoiding the problem of inability to cast caused by the thickening of the mixed melt.

[0082] In some embodiments, during the casting process, the uncast mixed melt is stirred using a first-mode stirring at an induction frequency of 90 Hz to 120 Hz.

[0083] In some embodiments, the casting temperature is controlled at 720 ℃~740 ℃ during the casting process.

[0084] In the above preparation method, combining stirring and ultrasonic treatment promotes the dissolution of zirconium particles, resulting in a magnesium-zirconium alloy with high zirconium content, fine particles, and a dispersed distribution. After stirring the mixed melt for 10-15 minutes, some of the zirconium particles in the raw material have dissolved, and the particle size has decreased, allowing them to suspend in the mixed melt. Introducing ultrasonic treatment at this point, without affecting the melt flow state, works in conjunction with stirring to further dissolve the zirconium particles, thereby obtaining a magnesium-zirconium alloy with high zirconium content, fine zirconium particles, and a uniform component distribution. Furthermore, the above preparation method can reduce the melting temperature and shorten the melting time, thereby reducing energy consumption and improving production efficiency.

[0085] This application also provides a magnesium-zirconium alloy prepared by the above-described method. The magnesium-zirconium alloy has a high zirconium content, particularly a high content of soluble zirconium. Furthermore, the zirconium particles in the magnesium-zirconium alloy are fine and uniformly dispersed, making it suitable as an intermediate in the preparation of zirconium-containing magnesium alloy products.

[0086] Furthermore, this application provides the application of the above-mentioned magnesium-zirconium alloy in the preparation of magnesium alloy products.

[0087] Furthermore, this application provides magnesium alloy products made from the aforementioned magnesium-zirconium alloy. These magnesium alloy products have fine grains, resulting in superior overall performance, and can be applied in, but not limited to, aerospace, transportation, and chemical industries.

[0088] The following are specific examples.

[0089] Example 1

[0090] The raw materials were batched at a total mass of 25 kg per furnace, with a magnesium metal to sponge zirconium mass ratio of 1:0.22. The magnesium metal was placed in a sealed three-phase induction atmosphere furnace and heated to complete melting under high-frequency induction conditions (60 kW, 1400 Hz) in a mixed atmosphere of 99% CO2 and 1% SF6 to obtain molten magnesium metal.

[0091] The temperature of the molten magnesium was controlled between 740 ℃ and 750 ℃, and sponge zirconium was added to obtain a mixed melt. The three-phase induction furnace was operated at a low frequency, and the mixed melt was stirred in three stages. The first stage of stirring used the first stirring method, with the power of the three-phase induction atmosphere furnace at 50 kW, the frequency at 90 Hz, and the melting temperature maintained at 740 ℃ to 750 ℃ ​​for 45 minutes. After the first stage of stirring, the second stage of stirring was performed, using the second stirring method, with the power of the three-phase induction atmosphere furnace adjusted to 40 kW, the frequency to 70 Hz, and the melting temperature maintained at 730 ℃ to 750 ℃ ​​for 5 minutes. After the second stage of stirring, the third stage of stirring was performed, which involved a combination of various stirring methods. Specifically, the third stirring method, the second stirring method, and the first stirring method were alternately performed, each for 3 minutes, for a total of 3 cycles. Furthermore, after 10 minutes of the first stage of stirring, ultrasonic treatment was initiated and maintained in the first stirring mode. The ultrasonic treatment frequency was 20 ± 1 kHz, the power was 1 kW, and the bottom of the ultrasonic rod was 70 mm away from the bottom wall of the crucible in the three-phase induction atmosphere furnace. This ultrasonic treatment lasted for 60 minutes, specifically the last 35 minutes of the first stage of stirring, the entire second stage of stirring, and the first 20 minutes of the third stage of stirring. After the third stage of stirring was completed, a preformed melt was obtained. During the third stage of stirring, the power of the three-phase induction atmosphere furnace was adjusted to 45 kW and the frequency to 90 Hz during the third stirring mode; the power of the three-phase induction atmosphere furnace was adjusted to 40 kW and the frequency to 70 Hz during the second stirring mode; and the power of the three-phase induction atmosphere furnace was adjusted to 50 kW and the frequency to 90 Hz during the first stirring mode.

[0092] The pre-formed melt is poured into the three-phase induction furnace from the side pouring port at a fixed point. During the pouring process, the furnace maintains stirring in the first mode. The furnace power is 50 kW, the frequency is 90 Hz, and the pouring temperature is controlled between 720 ℃ and 740 ℃. Cast iron molds are used for the pouring process. In this fixed-point pouring process, the first magnesium-zirconium alloy ingot to be poured is designated as Ingot #1, the next ingot as Ingot #2, and so on, until all the pre-formed melt in the induction furnace has been poured. In other words, Ingot #1 is made from the pre-poured melt at the top of the three-phase induction furnace; therefore, the zirconium particles in this ingot are relatively small, and the zirconium content is relatively low.

[0093] Example 2

[0094] The preparation method of Example 2 is basically the same as that of Example 1, except that the bottom of the ultrasonic rod is 120 mm away from the bottom wall of the crucible of the three-phase induction atmosphere furnace.

[0095] Example 3

[0096] The preparation method of Example 3 is basically the same as that of Example 1, except that the ultrasonic treatment is performed for 40 minutes. That is, the ultrasonic treatment is accompanied by the last 35 minutes of the first stage of stirring and the entire second stage of stirring.

[0097] Example 4

[0098] The preparation method of Example 4 is basically the same as that of Example 1, except that the bottom of the ultrasonic rod is 120 mm away from the bottom wall of the crucible of the three-phase induction atmosphere furnace, and the ultrasonic treatment lasts for 30 min, that is, from the 10th to the 40th minute of the ultrasonic treatment accompanied by the first stage of stirring.

[0099] Example 5

[0100] The preparation method of Example 5 is basically the same as that of Example 1, except that the bottom of the ultrasonic rod is 120 mm away from the bottom wall of the crucible of the three-phase induction atmosphere furnace, and the ultrasonic treatment lasts for 40 min, that is, the ultrasonic treatment is accompanied by the last 35 min of the first stage of stirring and the entire second stage of stirring.

[0101] Example 6

[0102] The preparation method of Example 6 is basically the same as that of Example 1, except that the bottom of the ultrasonic rod is 120 mm away from the bottom wall of the crucible of the three-phase induction atmosphere furnace, the power is 5 kW, and the ultrasonic treatment lasts for 40 min, that is, the ultrasonic treatment is accompanied by the last 35 min of the first stage of stirring and the entire second stage of stirring.

[0103] Example 7

[0104] The preparation method of Example 7 is basically the same as that of Example 1, except that: after stirring in the first manner for 15 minutes, ultrasonic treatment is performed immediately while stirring is maintained.

[0105] Comparative Example 1

[0106] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that ultrasonic treatment was not performed.

[0107] Comparative Example 2

[0108] In Comparative Example 2, after 10 minutes of stirring in the first method, mechanical stirring (stirring speed of 180 r / min) was used instead of ultrasonic treatment, while maintaining stirring. The bottom of the mechanical stirring paddle was 120 mm away from the bottom wall of the crucible in the three-phase induction atmosphere furnace, and the mechanical stirring continued for 40 minutes. Other steps were the same as in Example 1.

[0109] Comparative Example 3

[0110] The preparation method of Comparative Example 3 is basically the same as that of Example 1, except that Comparative Example 3 is subjected to ultrasonic treatment at the beginning of the second stage of stirring, that is, ultrasonic treatment is performed after stirring the mixed melt for 45 min, and the ultrasonic treatment lasts for 30 min while stirring is maintained. Other steps are the same as those of Example 1.

[0111] Comparative Example 4

[0112] Comparative Example 4 involved ultrasonic treatment at the start of the first stage of stirring, meaning that the mixed melt was simultaneously stirred and ultrasonicated throughout the entire smelting process, with the ultrasonic treatment lasting for 60 minutes. Other steps were the same as in Example 1.

[0113] The zirconium content and zirconium content in the magnesium matrix of the magnesium-zirconium alloy ingots prepared in Examples 1-7 and Comparative Examples 1-4 were tested, and the test results are shown in Tables 1 and 2 below. The test conditions or test standards for each performance test item are as follows: (1) The zirconium content in the magnesium-zirconium alloy ingot was determined according to the standard YS / T 372.21-2006; (2) The zirconium content in the magnesium matrix was determined according to the standard GB / T 13748.7-2013 and combined with energy dispersive spectroscopy analysis. In Table 1, ingots 1# to 14# represent ingots obtained from different batches of the same preformed melt.

[0114] Table 1. Zirconium content (wt%) of different magnesium-zirconium alloy ingots from the same heat batch

[0115] Group #1 casting ingot #4 casting ingot 7# Ingot 10# Ingot 14# Ingot Example 1 18.28 19.78 20.52 21.28 23.78 Example 2 18.88 19.90 20.12 21.28 22.43 Example 3 20.11 20.76 20.59 20.04 20.97 Example 4 18.14 18.72 18.83 20.91 23.23 Example 5 19.91 19.73 19.98 19.32 20.73 Example 6 19.73 19.95 20.90 19.73 20.95 Example 7 18.20 19.75 19.96 21.83 23.72 Comparative Example 1 18.98 18.56 19.55 20.54 23.90 Comparative Example 2 17.45 18.16 19.12 21.67 22.84 Comparative Example 3 18.35 18.72 20.17 21.04 24.86 Comparative Example 4 18.01 18.34 19.11 22.27 25.04

[0116] As shown in Table 1, ingots #1, #4, #7, #10, and #14 from Examples 1-7 all have high zirconium content. In Example 3, the zirconium content of all five ingots reaches over 20 wt%, indicating that the preparation method of this application can effectively increase the zirconium content of magnesium-zirconium alloys. In contrast, the zirconium content of Comparative Examples 1-4 is lower, and the zirconium particles in the resulting magnesium-zirconium alloys are coarse and unevenly distributed, which is detrimental to subsequent use and processing. It should be noted that ingot #1 in Table 1 is the first product formed by pre-forming melt point casting; similarly, ingot #4 is the fourth product formed by the above pre-forming melt point casting, and so on for ingots #7, #10, and #14.

[0117] Table 2. EDS data statistics on zirconium content in magnesium matrix

[0118] Group Average zirconium content (wt%) in magnesium matrix variance Example 1 3.90 1.34 Example 2 3.98 1.08 Example 3 4.07 0.96 Example 4 3.74 1.13 Example 5 4.00 1.38 Example 6 3.97 1.40 Example 7 3.96 1.22 Comparative Example 1 3.65 1.49 Comparative Example 2 3.68 2.35 Comparative Example 3 3.73 1.71 Comparative Example 4 3.60 2.14

[0119] As shown in Table 2, the magnesium matrix in Examples 1-7 has a high zirconium content, indicating that the preparation method of this application can effectively increase the soluble zirconium content in the magnesium-zirconium alloy and reduce the segregation of zirconium in the magnesium-zirconium alloy. Furthermore, when preparing magnesium alloys using the magnesium-zirconium alloys of Examples 1-7, more zirconium particles can be dissolved and formed, which can improve the ability of the magnesium-zirconium alloy to refine the grains of the magnesium alloy, thereby improving the performance of the magnesium alloy. In Example 3, the zirconium content in the magnesium matrix can reach 4.07 wt%, which is more than 10% higher than that in Comparative Examples 1 and 2. It should be noted that the data in Table 2 are EDS energy dispersive spectroscopy data. The data in Table 2 are obtained by detecting 20 different locations on the same sample, obtaining 20 corresponding data points, and then statistically calculating the average zirconium content and variance in the magnesium matrix.

[0120] Depend on Figures 4-7 It can be seen that in Examples 1 and 3, the magnesium-zirconium alloys contained relatively few undissolved zirconium particles (black and dark gray areas in the figure) and oxide inclusions (white areas in the figure), while Comparative Examples 1 and 2 contained a relatively large number of undissolved zirconium particles and oxide inclusions. This indicates that the preparation method of this application can improve the solubility of zirconium particles while reducing the formation of oxide inclusions. Figures 8-10 As can be seen from the microstructure diagrams, compared with Comparative Example 1, the dispersion of zirconium particles at the grain boundaries in Examples 1 and 3 was significantly improved, especially in Example 3, indicating that the present application can obtain a magnesium-zirconium alloy with better zirconium particle dispersion.

[0121] In summary, this application combines stirring and ultrasonic treatment to promote the dissolution of metallic zirconium particles, resulting in a magnesium-zirconium alloy with high zirconium content, especially high soluble zirconium content, and fine, dispersed zirconium particles.

[0122] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0123] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a magnesium-zirconium alloy, characterized in that, Includes the following steps: Magnesium metal is heated until it melts to obtain molten magnesium metal; Zirconium metal is added to the molten magnesium to form a mixed melt, and the mixture is stirred for 10 to 15 minutes. Then, while maintaining the stirring process, the mixed melt is ultrasonically treated to obtain a preformed melt. The preformed melt is shaped to obtain the magnesium-zirconium alloy; The ultrasonic treatment time is 10 min to 70 min; the ultrasonic treatment power is 0.4 kW to 5 kW; the magnesium-zirconium alloy is prepared by an induction furnace, and the induction furnace is equipped with an ultrasonic rod for ultrasonic treatment, and there is a gap of 70 mm to 150 mm between the bottom of the ultrasonic rod and the bottom wall of the induction furnace.

2. The method for preparing magnesium-zirconium alloy as described in claim 1, characterized in that, The step of heating the magnesium metal to melting is performed using induction heating, with a frequency of 1400 Hz to 1500 Hz. And / or, the stirring and ultrasonic treatment steps of the mixed melt are performed using induction heating, with an induction heating frequency of 20 Hz to 200 Hz.

3. The method for preparing the magnesium-zirconium alloy according to any one of claims 1 to 2, characterized in that, The stirring process includes the following steps: performing a first stage stirring, a second stage stirring and a third stage stirring in sequence, wherein the first stage stirring includes a first method of stirring, the second stage stirring includes a second method of stirring, and the third stage stirring includes at least one of the first method of stirring, the second method of stirring and the third method of stirring. The first stirring method is used to form a double-circulation flow of the mixed melt with the center upward and the sides downward; the second stirring method is used to form a double-circulation flow of the mixed melt with the center downward and the sides upward; the third stirring method is used to form a double-circulation flow of the upper mixed melt with the center upward and the sides downward, and to form a double-circulation flow of the lower mixed melt with the center downward and the sides upward.

4. The method for preparing magnesium-zirconium alloy as described in claim 3, characterized in that, The stirring time in the first stage is 20 min to 50 min, and after the stirring in the first stage is carried out for 10 min to 15 min, the ultrasonic treatment is started and the stirring in the first stage is maintained, so that the stirring treatment and the ultrasonic treatment are carried out on the mixed melt at the same time. And / or, the stirring time in the second stage is 0~20 min; And / or, the stirring time for the third stage is 6 min to 40 min.

5. The method for preparing magnesium-zirconium alloy as described in claim 3, characterized in that, The third stage of mixing includes the third type of mixing, the second type of mixing, and the first type of mixing, which are performed in a sequential cycle.

6. A magnesium-zirconium alloy, characterized in that, The magnesium-zirconium alloy was prepared using the method described in any one of claims 1 to 5.

7. The application of the magnesium-zirconium alloy according to claim 6 in the preparation of magnesium alloy products.

8. A magnesium alloy product, characterized in that, Its raw materials include the magnesium-zirconium alloy as described in claim 6.

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