Gradient alloy preparation apparatus and method

Abstract

The application provides a gradient alloy preparation device and method, which comprises a first chamber with adjustable air pressure and relative sealing, a nozzle on a crucible for containing molten alloy extending into the first chamber. The first chamber has a driving assembly, a cooling assembly and an annular mold. Before preparation, the air pressure in the first chamber is greater than that in the crucible, so that the molten alloy cannot flow out to affect the preparation. During the preparation, the air pressure in the first chamber is less than that in the crucible, and the molten alloy is sprayed out from the nozzle into the annular mold by using the pressure difference; at the same time, the driving assembly drives the cooling assembly and the annular mold to rotate, so that the molten alloy impacts layer by layer to refine the grains, and the layer-by-layer solidification is beneficial to reduce the internal stress. The cooling assembly is connected with continuously flowing cooling water for cooling the alloy in the annular mold. In this process, the gradient alloy with multiple requirements of strength, toughness, heat resistance, wear resistance and the like is formed by using the difference in the segregation degree of the melt.

Description

Technical Field

[0001] This invention generally relates to the field of aluminum alloy preparation technology, and specifically to a gradient alloy preparation apparatus and method. Background Technology

[0002] As core connectors in spacecraft, aluminum alloy structural components directly determine the overall operational safety of the spacecraft through their connection reliability. Currently, welding is the mainstream connection method. However, there is a significant contradiction between the alloying degree of aluminum alloys and their weldability: the higher the content of main alloying elements such as Zn and Mg, the better the alloy strength and toughness, but the sensitivity to welding cracks will increase sharply at the same time, which seriously limits the engineering application of highly alloyed aluminum alloy materials.

[0003] To avoid welding defects, riveting is often used as an alternative to welding. However, riveting has inherent drawbacks such as low connection strength, high assembly complexity, and redundant weight, making it difficult to meet the core requirements of spacecraft for lightweight, high strength, and high reliability. Therefore, existing alloy material theories have proposed a gradient alloy material. Gradient alloy materials are advanced materials whose composition, microstructure, or properties continuously change in space. Through multi-layer gradient design, different regions can perform different functions, thus taking into account diverse requirements such as strength, toughness, heat resistance, and wear resistance.

[0004] However, existing apparatuses for preparing gradient alloys do not consider the sealing issue at the nozzle, resulting in some molten alloy flowing out after the crucible is filled with molten alloy and before the gradient alloy is prepared. Since the cooling device has not yet been activated, the prematurely flowing alloy is not cooled as designed, making it difficult to control the composition of different parts of the gradient alloy. Consequently, the produced gradient alloy fails to meet the diverse requirements for strength, toughness, heat resistance, and wear resistance. Summary of the Invention

[0005] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a gradient alloy preparation apparatus and method.

[0006] On one hand, the present invention provides a gradient alloy preparation apparatus, comprising: First chamber; the first chamber is filled with inert gas; A crucible, disposed outside the first chamber, is used to contain molten alloy; the crucible has a nozzle extending into the first chamber; the crucible is also filled with an inert gas; Before preparing the gradient alloy, the gas pressure in the first chamber is greater than the gas pressure in the crucible to prevent the molten alloy from flowing out of the nozzle. During the preparation of gradient alloys, the gas pressure in the first chamber is lower than the gas pressure in the crucible, so that the molten alloy can be ejected from the nozzle. A drive assembly is disposed inside the first chamber; A cooling assembly, rotatably mounted on the drive assembly; An annular mold, which is fixedly mounted on a cooling assembly; the annular mold has an opening facing the nozzle for molten alloy ejected from the nozzle to enter the annular mold. The cooling assembly is used to cool the molten alloy inside the annular mold; The drive assembly is used to drive the cooling assembly and the annular mold to rotate around the vertical axis during the preparation of the gradient alloy. After the alloy is sprayed into the annular mold, it drives the alloy to rotate together to prepare the gradient alloy.

[0007] According to the technical solution provided by the present invention, the driving component is further configured to simultaneously drive the cooling component, the annular mold, and the alloy inside the annular mold to move downward in the vertical direction when driving the cooling component, the annular mold, and the alloy inside the annular mold to rotate.

[0008] According to the technical solution provided by the present invention, the driving component includes: A lifting platform is fixedly installed inside the first chamber; the cooling assembly is rotatably installed on the lifting platform. A drive mechanism is fixedly mounted on the lifting platform and connected to the cooling assembly, used to drive the cooling assembly to rotate relative to the lifting platform.

[0009] According to the technical solution provided by the present invention, the cooling assembly includes: A rotary joint having a fixed part and a rotating part that can rotate relative to each other; the fixed part is fixedly installed on the lifting platform; the rotary joint has a water inlet passage and a water outlet passage inside. A connecting flange, which is fixedly installed on the rotating part; A water cavity is fixedly installed on the connecting flange; the water cavity has an inlet and an outlet for connecting flowing cooling water; the inlet is connected to the water inlet passage; the outlet is connected to the water outlet passage; the annular mold is installed on the water cavity, and the cooling water flowing in the water cavity is used to cool the alloy inside the annular mold.

[0010] According to the technical solution provided by the present invention, the connecting flange has external teeth; The drive mechanism includes: The motor is fixedly mounted on the lifting platform; The gear is fixedly mounted on the rotating shaft of the motor and meshes with the external teeth. It is used to drive the connecting flange, water cavity, annular mold, and alloy inside the annular mold to rotate under the driving action of the motor.

[0011] According to the technical solution provided by the present invention, the cooling assembly further includes: A water pump, which is connected to the water inlet passage, is used to drive the flow of cooling water; A water tank is used to store low-temperature cooling water and to cool high-temperature cooling water; one side of the water tank is connected to the water pump, and the other side is connected to the water outlet passage.

[0012] On the other hand, the present invention provides a gradient alloy preparation method, applied to the gradient alloy preparation apparatus described above; the method includes: Molten alloy is poured into a crucible and inert gas at a first set pressure is introduced into the crucible. Inert gas at a second set pressure is introduced into the first chamber. The first set pressure is less than the second set pressure. The drive component drives the cooling component, the ring mold, and the alloy inside the ring mold to rotate at a first set speed; and connects the cooling component to cooling water with a set flow rate; The gas pressure in the first chamber is adjusted to the third set gas pressure, so that the molten alloy in the crucible is sprayed into the mold through the nozzle under the action of gas pressure; the third set gas pressure is less than the first set gas pressure.

[0013] According to the technical solution provided by the present invention, before pouring the molten alloy into the crucible, the method further includes: Preparing an alloy in a molten state includes: The alloy is formulated according to its chemical composition, including: the main component of the alloy, a first intermediate alloy, and a second intermediate alloy; the main component of the alloy is aluminum. The first intermediate alloy comprises the following raw materials in weight percentages: 8.5%–9% Mg, 0.8%–0.12% Zn, 0.08%–0.2% Zr, and 0%–0.2% Sc; the second intermediate alloy comprises an Al-Ti-B alloy in a weight ratio of 1:5:1. The main components of the alloy are melted to bring them into a molten state; and a first intermediate alloy is added. Refining agents are added to the molten alloy main components to remove impurities; An inert gas is added to the molten alloy main component for degassing; at the same time, a second intermediate alloy is added. After standing for a set time, the alloy is obtained in a molten state.

[0014] According to the technical solution provided by the present invention, it further includes: The drive assembly moves the cooling assembly, the annular mold, and the alloy inside the annular mold downward in a vertical direction at a first speed, so that the distance from the nozzle to the upper surface of the alloy inside the mold remains constant.

[0015] According to the technical solution provided by the present invention, the first speed satisfies the following formula to ensure that the distance from the nozzle to the upper surface of the alloy inside the mold remains constant:

[0016] in, Indicates the first velocity. Represents the flow coefficient. Represents pi (π). Indicates the diameter of the nozzle. The density of an alloy in its molten state. This indicates the first set air pressure. This indicates the second set air pressure. This represents the bottom area inside the annular mold.

[0017] The beneficial effects of this invention are as follows: To address the problem that existing equipment often produces gradient alloys that fail to meet diverse requirements such as strength, toughness, heat resistance, and wear resistance, this invention provides a gradient alloy preparation apparatus and method. The apparatus includes: a first chamber with adjustable and relatively sealed air pressure, into which a nozzle on a crucible containing molten alloy extends. The first chamber contains a driving assembly, a cooling assembly, and an annular mold. Before preparation, the air pressure in the first chamber is made higher than the air pressure inside the crucible to prevent molten alloy from flowing out and affecting the preparation process. During preparation, by making the air pressure in the first chamber lower than the air pressure inside the crucible, the pressure difference forces the molten alloy to be ejected from the nozzle and enter the annular mold. Simultaneously, the driving assembly rotates the cooling assembly and the annular mold, causing the molten alloy to impact the crystals layer by layer to refine the grains. Layer-by-layer solidification helps reduce internal stress. A continuous flow of cooling water is supplied to the cooling assembly to cool the alloy within the annular mold. This process utilizes the difference in melt segregation to form a gradient alloy that meets diverse requirements such as strength, toughness, heat resistance, and wear resistance.

[0018] Accordingly, the preparation method includes: injecting molten alloy into a crucible, filling the crucible with an inert gas at a first set pressure, and filling a first chamber with an inert gas at a second set pressure; the first set pressure is lower than the second set pressure; a driving component drives a cooling component, an annular mold, and the alloy within the annular mold to rotate at a first set speed; and connecting the cooling component to cooling water at a set flow rate; adjusting the pressure in the first chamber to a third set pressure, so that the molten alloy in the crucible is sprayed into the mold through a nozzle under the action of the pressure; the third set pressure is lower than the first set pressure. This method can prevent the molten alloy from flowing out before preparation, and the spraying of the molten alloy can be controlled by adjusting the pressure difference during preparation to complete the process. Attached Figure Description

[0019] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of a gradient alloy preparation apparatus; Figure 2 for Figure 1 A magnified view of a section at point A in the middle; Figure 3 This is a cross-sectional schematic diagram of the fixed part; Figure 4 This is a schematic diagram of the connecting flange; Figure 5 This is a schematic diagram showing the distance between the position points and the bottom surface in the prepared alloy, and the zinc content. Figure 6 This is a schematic diagram showing the distance between the position points and the bottom surface in the prepared alloy, and the magnesium content. The components are as follows: 1. First chamber; 2. Crucible; 3. Nozzle; 4. Ring mold; 5. Opening; 6. Lifting platform; 7. Rotary joint; 8. Fixing part; 9. Rotating part; 10. Water inlet passage; 11. Water outlet passage; 12. Connecting flange; 13. Water chamber; 14. Water inlet; 15. Water outlet; 16. Motor; 17. Gear; 18. Molten alloy; 19. Air pressure regulating port; 20. External gear; 21. Connecting part; 22. Transmission part; 23. Through hole. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] Example 1 refer to Figure 1-2 The arrow indicates the direction of cooling water flow.

[0023] This invention provides a gradient alloy preparation apparatus, comprising: First chamber 1; the first chamber 1 is filled with inert gas; A crucible 2 is disposed outside the first chamber 1 and is used to contain the molten alloy 18; the crucible 2 has a nozzle 3 that extends into the first chamber 1; the crucible 2 is also filled with an inert gas; Before preparing the gradient alloy, the gas pressure in the first chamber 1 is greater than the gas pressure in the crucible 2, in order to prevent the molten alloy 18 from flowing out of the nozzle 3. During the preparation of gradient alloys, the gas pressure in the first chamber 1 is lower than the gas pressure in the crucible 2, so that the molten alloy 18 can be ejected from the nozzle 3. A drive assembly is disposed inside the first chamber 1; A cooling assembly, rotatably mounted on the drive assembly; An annular mold 4 is fixedly mounted on a cooling assembly; the annular mold 4 has an opening 5 facing the nozzle 3 for the molten alloy 18 ejected from the nozzle 3 to enter the annular mold 4. The cooling assembly is used to cool the molten alloy 18 inside the annular mold 4; The drive assembly is used to drive the cooling assembly and the annular mold 4 to rotate around the vertical axis during the preparation of the gradient alloy. After the alloy is sprayed into the annular mold 4, it drives the alloy to rotate together to prepare the gradient alloy.

[0024] In this embodiment, the alloy is specifically an aluminum alloy. When the nozzle 3 continuously sprays molten alloy, the annular mold continues to rotate, which allows the molten alloy to cover the surface layer by layer, thereby refining the grains. Layer-by-layer solidification helps to reduce internal stress.

[0025] A continuous flow of cooling water is introduced into the cooling assembly to cool the alloy within the annular mold. During this process, because the cooling is performed layer by layer, the distance from each layer to the cooling assembly varies, resulting in different cooling efficiencies. This utilizes the differences in melt segregation to create a gradient alloy that meets diverse requirements such as strength, toughness, heat resistance, and wear resistance.

[0026] Melt segregation refers to the phenomenon where different components of magma or metal separate during crystallization or cooling due to changes in physical or chemical conditions, resulting in rocks or alloys with heterogeneous composition.

[0027] In this embodiment, the alloy closer to the cooling component (i.e., the alloy with lower height) cools faster, while the alloy farther from the cooling component (i.e., the alloy with higher height) cools slower. Furthermore, the alloys with different heights are injected into the annular mold at different times and under different physical conditions.

[0028] Specifically, the alloy at the lower level has gradually solidified at a lower temperature, is closer to the cooling components at an even lower temperature, and is in a molten state at a higher temperature above. The alloy at the higher level has just been ejected and is at a higher temperature; its lower surface overlaps with the alloy at the lower level and exchanges heat, while its upper surface is in contact with an inert gas. It is evident that the physical conditions of the alloy at different locations in this embodiment are different; moreover, different metallic elements have different melting points, and the environment set in this embodiment will cause melt segregation. Therefore, during the solidification process, the cooling rate of the alloy at different locations is different, and the proportion of the alloy composition after solidification will gradually change. Alloys with different composition proportions also have different physical properties. Based on the above, gradient alloys with different properties such as strength, toughness, heat resistance, and wear resistance can be formed in different layers.

[0029] The specific working methods include: Before preparing the gradient alloy, the gas pressure in the first chamber 1 is greater than the gas pressure in the crucible 2, in order to prevent the molten alloy 18 from flowing out of the nozzle 3. During the preparation of gradient alloys, the gas pressure in the first chamber 1 is lower than the gas pressure in the crucible 2, which is used to spray the molten alloy 18 from the nozzle 3; at the same time, the cooling component cools the molten alloy 18 in the annular mold 4; the driving component drives the cooling component, the annular mold 4, and the alloy in the annular mold 4 to rotate around the vertical axis to prepare gradient alloys.

[0030] Specifically, since crucible 2 is not usually completely filled with molten metal and there will be empty space, in this embodiment, the empty space is filled with an inert gas (e.g., argon) to avoid oxidation or other chemical reactions of the molten alloy by active gases such as oxygen.

[0031] In this embodiment, the internal pressure of the crucible remains constant (maintaining one standard atmosphere). By adjusting the pressure inside the first chamber to make it greater than the pressure inside the crucible, the molten metal can be prevented from leaking out of the nozzle before the alloy is formally prepared.

[0032] When molten metal needs to be ejected, the air pressure in the first chamber is reduced to be lower than the air pressure inside the crucible, and the pressure difference is used to force the molten alloy to be ejected.

[0033] Specifically, the first chamber has a pressure regulating port 19 on its side wall; the pressure regulating port 19 connects the internal space of the first chamber to an inert gas storage tank (e.g., storing argon gas), and a solenoid valve and a gas pump are installed on the pipeline connecting the pressure regulating port 19 and the inert gas storage tank to regulate the pressure in the first chamber. To avoid chemical reactions between the ejected alloy and reactive gases such as oxygen, the first chamber is also filled with an inert gas, preferably argon gas.

[0034] Furthermore, the driving component is also used to simultaneously drive the cooling component, the annular mold 4, and the alloy inside the annular mold 4 to move downward in the vertical direction when rotating the cooling component, the annular mold 4, and the alloy inside the annular mold 4.

[0035] In this embodiment, during the continuous spraying of molten alloy, the height of the alloy inside the annular mold gradually increases, which shortens the time between the spraying of the molten alloy and its falling into the annular mold. This situation not only affects the shape of the alloy after cooling, but also causes local temperatures to be too high or too low, thereby affecting the properties of the alloy.

[0036] For the reasons mentioned above, it is necessary to eliminate interference factors as much as possible when preparing gradient alloys. Therefore, this embodiment takes into account the increase in alloy height within the annular mold, and controls the drive component to drive the cooling component of the annular mold, and the alloy within it to gradually decrease, so that the height of the upper surface of the alloy remains constant, thereby keeping the distance from the upper surface of the alloy to the nozzle constant, and ultimately eliminating the aforementioned interference factors.

[0037] Furthermore, the driving component includes: A lifting platform 6 is fixedly installed inside the first chamber 1; the cooling assembly is rotatably installed on the lifting platform 6. A drive mechanism is fixedly installed on the lifting platform 6 and connected to the cooling assembly, used to drive the cooling assembly to rotate relative to the lifting platform 6.

[0038] Specifically, the lifting platform 6 can drive the cooling component, the annular mold, and the alloy therein to move vertically, thereby maintaining a constant distance between the upper surface of the alloy and the nozzle 3. The drive mechanism can drive the cooling component, the annular mold, and the alloy therein to rotate, in order to complete the preparation.

[0039] Furthermore, the cooling assembly includes: Rotary joint 7 has a fixed part 8 and a rotating part 9 that can rotate relative to each other; the fixed part 8 is fixedly installed on the lifting platform 6; the rotary joint 7 has a water inlet passage 10 and a water outlet passage 11 inside. A connecting flange 12 is fixedly installed on the rotating part 9; A water cavity 13 is fixedly installed on the connecting flange 12; the water cavity 13 has an inlet 14 and an outlet 15 for connecting flowing cooling water; the inlet 14 is connected to the water inlet passage 10; the outlet 15 is connected to the water outlet passage 11; the annular mold 4 is installed on the water cavity 13, and the cooling water flowing in the water cavity 13 is used to cool the alloy in the annular mold 4.

[0040] Specifically, the water inlet passage 10 inside the fixing part 8 has a circular cross-section along the vertical direction, while the water outlet passage 11 has an annular cross-section. (Reference) Figure 3 The water inlet passage 10 is located inside the water outlet passage 11, and the two are not connected to each other.

[0041] The water inlet passage 10 and water outlet passage 11 inside the rotating part 9 are as follows Figure 2 As shown. The water inlet passage 10 is connected to the water inlet 14 of the water chamber; the water outlet passage 11 is connected to the water outlet 15 of the water chamber through a pipeline.

[0042] The specific structure of connecting flange 12 is as follows: Figure 4 As shown, the connecting flange 12 has a connecting part 21 and a transmission part 22. The connecting part 21 is fixedly connected to the water cavity and the rotating part 9; the transmission part 22 has a through hole 23 for the pipeline connecting the water outlet passage 11 and the water outlet 15 to pass through.

[0043] Furthermore, the transmission part of the connecting flange 12 has external teeth 20; The external teeth 20 and the through hole 23 are offset from each other for connection with the drive mechanism. The power generated by the drive mechanism drives the connecting flange 12, the rotating part 9, the cooling assembly, the annular mold, and the alloy in the annular mold to rotate, while the fixed part remains stationary. During this process, although there is relative rotation between the fixed part and the rotating part, the water inlet passage 10 and the water outlet passage 11 inside them always remain connected, thus continuously providing a path for the flow of cooling water.

[0044] The drive mechanism includes: Motor 16, which is fixedly installed on the lifting platform 6; Gear 17 is fixedly mounted on the rotating shaft of the motor and meshes with the external gear. It is used to drive the connecting flange 12, water cavity 13, annular mold 4, and the alloy inside the annular mold 4 to rotate under the driving action of the motor 16.

[0045] Specifically, the rotation axis of the motor 16 is parallel to the vertical direction, making the rotation axis of the gear 17 vertical. After meshing with the external teeth of the connecting flange, the gear 17 can drive the connecting flange to rotate.

[0046] Furthermore, the cooling assembly also includes: A water pump, which is connected to the water inlet passage 10, is used to drive the flow of cooling water; The water tank is used to store low-temperature cooling water and to cool high-temperature cooling water; one side of the water tank is connected to the water pump, and the other side is connected to the water outlet passage 11.

[0047] The overall circulation of the cooling system includes: The water pump drives the low-temperature cooling water through the pipeline into the water inlet passage 10, and then into the water chamber through the water inlet 14, where it exchanges heat with the molten alloy, thus raising the temperature of the cooling water. High-temperature cooling water passes through outlet 15 and pipes, enters outlet passage 11, and finally returns to the water tank; The water tank cools the cooling water, and then the low-temperature cooling water is pumped back into the water inlet passage 10 to complete the circulation.

[0048] Example 2 This invention provides a method for preparing gradient alloys, applied to the gradient alloy preparation apparatus described in the above embodiments. The method includes: S1: Preparation of alloys in a molten state, including: S1-1: The alloy is formulated according to its chemical composition, including: the main component of the alloy, a first intermediate alloy, and a second intermediate alloy; the main component of the alloy is aluminum; The first intermediate alloy comprises the following raw materials in weight percentages: 8.5%–9% Mg (magnesium ingot), 0.8%–0.12% Zn (zinc ingot), 0.08%–0.2% Zr (Al-Zr alloy), and 0%–0.2% Sc (Al-Sc alloy); the second intermediate alloy comprises an Al-Ti-B alloy in a weight ratio of 1:5:1, added at a ratio of 1.5‰ of the total weight.

[0049] Specifically, the main component of the alloy is aluminum; the alloy composition meets the requirements of Table 1.

[0050] Table 1 Alloy Composition Table

[0051] The total mass of the alloy is 100%, and the mass proportions of the metallic elements Si, Fe, Cu, Mn, Mg, Zn, Ti, Zr, and Sc are calculated according to Table 1. The remaining mass is aluminum.

[0052] S1-2: Melt the main components of the alloy to bring them into a molten state; and add the first intermediate alloy. The specific process is as follows: first, add aluminum ingots, then heat the temperature to 780 degrees Celsius to melt the aluminum ingots, and then add the first intermediate alloy.

[0053] S1-3: Add refining agent to the molten alloy main component to remove impurities; The refining agent is specifically composed of 4AB solvent (including 40% by mass of NaCl, 10% by mass of KCl, 20% by mass of SiO2, and 30% by mass of Na3AlF6). During this process, the temperature is maintained at 720 degrees Celsius.

[0054] After the addition of the refining agent, the chemical substances react with the impurities in the molten alloy, thereby removing the impurities. Then, a slag removal process is performed to remove the impurities.

[0055] S1-4: Inert gas is added to the molten alloy main component for degassing; at the same time, a second intermediate alloy is added; During this process, a second intermediate alloy is added at a ratio of 1.5‰ of the total mass, and an inert gas (argon) is introduced into the molten alloy. The inert gas is used to generate an extraction-like effect to remove residual hydrogen from the molten metal.

[0056] S1-5: After standing for a set time (15 minutes), the alloy is obtained in a molten state.

[0057] S2: The molten alloy is poured into the crucible, and an inert gas at a first set pressure is filled into the crucible. An inert gas at a second set pressure is filled into the first chamber. The first set pressure is less than the second set pressure. In this embodiment, the first set air pressure is 1 standard atmosphere (approximately 100 kPa), and the second set air pressure is 105 kPa to 110 kPa.

[0058] Before spraying the molten alloy, the gas pressure in the first chamber is made slightly higher than the gas pressure in the crucible. This prevents the molten metal from flowing out of the nozzle prematurely, which would affect the quality of the prepared alloy.

[0059] S3: The drive component drives the cooling component, the ring mold, and the alloy inside the ring mold to rotate at a first set speed; and connects the cooling component to cooling water with a set flow rate; Preferably, the first set rotational speed is 1 revolution / min; the set flow rate is 350 to 450 L / min.

[0060] In this embodiment, an annular mold is used to prepare the alloy by rotating the nozzle relative to the mold. This allows the alloy sprayed out before and after to be in different layers, while ensuring the gradual change of material properties between adjacent layers.

[0061] S4: Adjust the air pressure in the first chamber to the third set air pressure, so that the molten alloy in the crucible is sprayed into the mold through the nozzle under the action of air pressure; the third set air pressure is less than the first set air pressure. In this embodiment, the third set gas pressure is set to 90 to 98 kPa. The third set gas pressure is lower than the first set gas pressure, and the pressure difference can be used to cause the molten alloy to be ejected from the nozzle, thereby completing the preparation of the gradient alloy.

[0062] S5: The drive assembly drives the cooling assembly, the ring mold, and the alloy inside the ring mold to move downward in the vertical direction at a first speed, so that the distance from the nozzle to the upper surface of the alloy inside the mold remains unchanged.

[0063] Specifically, to maintain a constant distance between the upper surface of the alloy and the nozzle as the upper surface of the alloy gradually rises relative to the annular mold while continuously spraying molten alloy, it is necessary to combine multiple data points and calculate the first velocity.

[0064] Furthermore, the first velocity satisfies the following formula to ensure that the distance from the nozzle to the upper surface of the alloy inside the mold remains constant: Formula 1; in, Indicates the first velocity. This represents the flow coefficient (in this embodiment, the flow coefficient was experimentally measured to be approximately 0.62). Represents pi (π). Indicates the diameter of the nozzle. The density of an alloy in its molten state. This indicates the first set air pressure. This indicates the second set air pressure. This represents the bottom area inside the annular mold.

[0065] Specifically, according to existing theories, if there is a pressure difference between two closed spaces, the flow rate generated after they are connected satisfies the following formula: Formula 2; in, Q Indicates flow rate. In this embodiment, the pressure difference is indicated. .

[0066] In this embodiment, the volume V of molten alloy ejected per unit time is numerically equal to the flow rate. QMeanwhile, since the molten alloy is uniformly injected into the annular mold in this embodiment, the height D of the alloy inside the annular mold is equal to the ratio of its volume to the bottom area S of the annular mold. Therefore, the distance that needs to be moved downward per unit time is equal to the flow rate. Q The ratio of the area of ​​the bottom S inside the ring mold to the area of ​​the bottom S inside the ring mold.

[0067] Finally, the first velocity is calculated according to Formula 2, as shown in Formula 1.

[0068] Based on the above, the first velocity can be accurately calculated, so as to control the downward speed more accurately and eliminate the influence of interference factors on the preparation of gradient alloys as much as possible.

[0069] Specifically, gradient alloys are prepared according to the apparatus and method provided by the present invention.

[0070] For example, the component ratio is: Si=0.006%, Fe=0.085%, Mg=8.5%, Zn=0.95%, Zr=0.11% (for illustrative purposes only). All values ​​here, as well as in Table 2, are expressed as percentages of total mass.

[0071] The core of the preparation method in this embodiment lies in utilizing the melt segregation effect. During the process of layer-by-layer spraying, rotary spreading, and forced cooling of the alloy, the thermal history and solidification conditions experienced at different locations vary significantly: Near the bottom (lower area): The molten alloy sprayed first can directly contact the water chamber of the cooling component, thus solidifying relatively quickly. This method results in an extremely fast cooling rate, constituting a rapid solidification condition.

[0072] Far bottom region (higher area): The molten alloy sprayed later can only transfer heat through the alloy solidifying at the bottom, resulting in slower solidification. Because there is a solidified or semi-solid alloy layer below and an inert gas above, the cooling rate is relatively slow, belonging to medium-speed or slow-speed solidification conditions.

[0073] Due to the different melting points, diffusion coefficients, and segregation tendencies of the elements in the alloy, the distribution behavior of each element at the solid / liquid interface changes systematically under different cooling rates, resulting in a spatial redistribution of the composition.

[0074] The alloy ring can be prepared by following the above steps. Then, it is tested in two different regions of the ring (region 1 located at the edge of the ring and region 2 located at the center of the ring). The obtained data are shown in Table 2. Table 2 Composition data of various parts of the ring component

[0075] The zinc and magnesium contents at different locations from the bottom of the alloy at a certain point are respectively referenced. Figures 5 to 6It is evident that the content of magnesium and zinc is negatively correlated with the distance from the bottom. Furthermore, the variations in the content of different metals are also different, as shown in Table 2. For example, the content of Zr is positively correlated with the distance from the bottom.

[0076] Specifically, the changes in the content of each element include: Changes in Mg and Zn content: The content of both showed a systematic decreasing trend with increasing distance from the bottom surface (see...). Figure 5 , Figure 6 This is because Mg and Zn are both solute elements in the aluminum matrix. Under rapid solidification (bottom) conditions, the solute trapping effect is stronger, and the elements are more easily retained in the initially solidified solid phase. Under slower solidification conditions in the upper part, the solute has more time to diffuse into the residual liquid phase and accumulate. However, this process involves continuous spraying and layer-by-layer coverage. The accumulated solute in the upper layer is diluted by the new melt in subsequent sprays, macroscopically manifested as a decrease in Mg and Zn content from bottom to top. This aligns with the design goal of coordinating strength and toughness in high-strength aluminum alloys through the gradient distribution of Mg and Zn strengthening phases (such as MgZn2).

[0077] Zr content variation: The Zr content shows a slight increasing trend with increasing distance from the bottom surface. Zr often exists in the form of Al3Zr dispersed phase, and its formation and precipitation are extremely sensitive to the cooling rate. Under the extremely high cooling rate at the bottom, Zr atoms may be supersaturated and dissolved in the matrix, forming fine coherent Al3Zr nanoparticles; while under the slower cooling conditions at the top, Zr has more time to aggregate and grow, forming slightly coarser precipitates with a potentially higher volume fraction. This results in a slight increase in the apparent mass fraction of Zr with height. This distribution is beneficial for improving the recrystallization resistance and high-temperature stability of the alloy from top to bottom.

[0078] Impurity elements such as Si and Fe: Their content fluctuates little at different altitudes and is generally at an extremely low level (≤0.1%), indicating that the pretreatment process (impurity removal and degassing) is effective, avoiding macroscopic agglomeration of impurity elements and ensuring the purity of the material matrix.

[0079] Differences between the edge and the core: At the same height, the Mg content in the core (region 2) is generally slightly higher than that in the edge (region 1). This is related to the centrifugal effect caused by the mold rotation and the radial temperature gradient. The melt residence time in the core is slightly longer, and the solute retention is slightly greater. This subtle difference in radial composition further enriches the three-dimensional gradient characteristics of the material.

[0080] Because the content of each metal element varies in different parts, different parts of the alloy have different physical properties, ultimately forming a gradient alloy.

[0081] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention is not limited to the specific combination of the above-described technical features, but also includes other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this invention.

Claims

1. A gradient alloy preparation apparatus, characterized in that, include: First chamber (1); the first chamber (1) is filled with inert gas; A crucible (2) is disposed outside the first chamber (1) for containing molten alloy (18); the crucible (2) has a nozzle (3) extending into the first chamber (1); the crucible (2) is also filled with an inert gas; Before preparing the gradient alloy, the gas pressure in the first chamber (1) is greater than the gas pressure in the crucible (2) to prevent the molten alloy (18) from flowing out from the nozzle (3); During the preparation of gradient alloys, the gas pressure in the first chamber (1) is lower than the gas pressure in the crucible (2), so that the molten alloy (18) can be ejected from the nozzle (3); A drive assembly disposed inside the first chamber (1); A cooling assembly, rotatably mounted on the drive assembly; An annular mold (4) is fixedly mounted on a cooling assembly; the annular mold (4) has an opening (5) facing the nozzle (3) for the molten alloy (18) ejected from the nozzle (3) to enter the annular mold (4). The cooling assembly is used to cool the molten alloy (18) inside the annular mold (4); The driving component is used to drive the cooling component and the annular mold (4) to rotate in the vertical direction during the preparation of gradient alloy, and after the alloy is sprayed into the annular mold (4), it drives the alloy to rotate together to prepare gradient alloy.

2. The gradient alloy preparation apparatus according to claim 1, characterized in that, The drive assembly is also used to simultaneously drive the cooling assembly, the annular mold (4), and the alloy inside the annular mold (4) to move downward in the vertical direction when the cooling assembly, the annular mold (4), and the alloy inside the annular mold (4) are rotated.

3. The gradient alloy preparation apparatus according to claim 2, characterized in that, The driving component includes: A lifting platform (6) is fixedly installed inside the first chamber (1); the cooling assembly is rotatably installed on the lifting platform (6); A drive mechanism is fixedly installed on the lifting platform (6) and connected to the cooling component, for driving the cooling component to rotate relative to the lifting platform (6).

4. The gradient alloy preparation apparatus according to claim 3, characterized in that, The cooling assembly includes: Rotary joint (7) has a fixed part (8) and a rotating part (9) that can rotate relative to each other; the fixed part (8) is fixedly installed on the lifting platform (6); the rotary joint (7) has a water inlet passage (10) and a water outlet passage (11) inside. A connecting flange (12) is fixedly installed on the rotating part (9); Water cavity (13), which is fixedly installed on the connecting flange (12); water cavity (13) has inlet (14) and outlet (15) for connecting flowing cooling water; inlet (14) is connected to inlet passage (10); outlet (15) is connected to outlet passage (11); annular mold (4) is installed on water cavity (13), and cooling water flowing in water cavity (13) is used to cool the alloy in annular mold (4).

5. The gradient alloy preparation apparatus according to claim 4, characterized in that, The connecting flange (12) has external teeth (20); The drive mechanism includes: Motor (16), which is fixedly installed on the lifting platform (6); Gear (17), which is fixedly mounted on the rotating shaft of the motor and meshes with the external gear (20), is used to drive the connecting flange (12), water cavity (13), annular mold (4), and alloy inside the annular mold (4) to rotate under the driving action of the motor (16).

6. The gradient alloy preparation apparatus according to claim 4, characterized in that, The cooling assembly also includes: A water pump, which is connected to the water inlet passage (10), is used to drive the flow of cooling water; The water tank is used to store low-temperature cooling water and to cool high-temperature cooling water; one side of the water tank is connected to the water pump, and the other side is connected to the water outlet passage (11).

7. A method for preparing gradient alloys, characterized in that, Applied to a gradient alloy preparation apparatus as described in any one of claims 1-6; The methods include: Molten alloy (18) is poured into crucible (2), and inert gas at a first set pressure is filled into crucible (2), and inert gas at a second set pressure is filled into first chamber (1); the first set pressure is less than the second set pressure. The drive assembly drives the cooling assembly, the annular mold (4), and the alloy inside the annular mold (4) to rotate at a first set speed; and connects the cooling assembly to cooling water with a set flow rate; Adjust the gas pressure in the first chamber (1) to the third set gas pressure so that the alloy in the molten state in the crucible (2) is sprayed into the mold from the nozzle (3) through the opening (5) under the action of gas pressure; the third set gas pressure is less than the first set gas pressure.

8. The method for preparing a gradient alloy according to claim 7, characterized in that, Before pouring the molten alloy (18) into the crucible (2), the following steps are also included: The preparation of the alloy (18) in the molten state includes: The alloy is formulated according to its chemical composition, including: the main component of the alloy, a first intermediate alloy, and a second intermediate alloy; the main component of the alloy is aluminum. The first intermediate alloy comprises the following raw materials in weight percentages: 8.5%–9% Mg, 0.8%–0.12% Zn, 0.08%–0.2% Zr, and 0%–0.2% Sc; the second intermediate alloy comprises an Al-Ti-B alloy in a weight ratio of 1:5:

1. The main components of the alloy are melted to bring them into a molten state; and a first intermediate alloy is added. Refining agents are added to the molten alloy main components to remove impurities; An inert gas is added to the molten alloy main component for degassing; at the same time, a second intermediate alloy is added. After standing for a set time, a molten alloy (18) is obtained.

9. The method for preparing a gradient alloy according to claim 7, characterized in that, Also includes: The drive assembly drives the cooling assembly, the annular mold (4), and the alloy inside the annular mold (4) to move downward in the vertical direction at a first speed, so that the distance from the nozzle (3) to the upper surface of the alloy inside the mold remains unchanged.

10. The method for preparing a gradient alloy according to claim 9, characterized in that, The first velocity satisfies the following formula so that the distance from the nozzle (3) to the upper surface of the alloy inside the mold remains constant: in, Indicates the first velocity. Indicates the flow coefficient. Represents pi (π). Indicates the diameter of the nozzle. The density of an alloy in its molten state. This indicates the first set air pressure. This indicates the second set air pressure. This indicates the bottom area inside the annular mold.

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