High-strength high-conductivity al-mg-si-sc-zn alloy, preparation method and application thereof

Abstract

The application relates to the technical field of alloys for submarine cables, and more particularly to a high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy and a preparation method and application thereof. The high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy has the following element component mass percentages: Mg 0.5%-1.0%, Si 0.3%-0.8%, Sc 0.04%-0.4%, Zn 0.3%-1.1% and the balance of Al. Sc in the high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy is beneficial to forming fine dispersed phases and improving subsequent structure stability, and the addition of Sc changes Mg-Si precipitation behavior and peak aging response, so that the alloy can improve the strength while maintaining good plasticity. After further adding Zn on the basis of low Sc, the strengthening effect of Zn on the Al-0.5Si-0.7Mg-0.05Sc alloy is further enhanced, and the 1.0% Zn alloy obtains the best comprehensive mechanical properties, and exhibits good application potential for submarine cable conductors.

Description

Technical Field

[0001] This application relates to the technical field of alloys for submarine cables, and more specifically to high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloys, their preparation methods, and applications. Background Technology

[0002] With the continuous advancement of offshore wind power development, island interconnection, and cross-sea power transmission projects, submarine power cables have become a key infrastructure in marine energy development and long-distance power transmission systems. As the core carrier of power transmission, the performance and material selection of submarine cable conductors directly determine the operational reliability, structural safety, and engineering economy of the cable. In complex application scenarios such as deep-sea and floating offshore wind power, submarine cables need to withstand multiple external forces such as wave impact, ocean currents, self-weight, laying tension, and cyclic loads for extended periods. Coupled with complex cross-sectional structures, local stress concentrations, and multi-field coupling in the service environment, the requirements for the mechanical reliability and structural integrity of submarine cable conductors are further enhanced, making the economic issue of conductor material selection increasingly prominent.

[0003] From the current engineering application status, copper remains the mainstream material for submarine cable conductors. Its core advantage is low resistance loss. This characteristic has long made it the traditional preferred material for submarine cable conductors. It can stably ensure the basic efficiency of large-capacity, long-distance power transmission in submarine cables and meet the basic power transmission requirements for long-term service of submarine cables. At the same time, its mature application technology also provides convenience for engineering construction and operation and maintenance, making it the mainstream choice for submarine cable conductors at present. However, it also has the following disadvantages: (1) High cost pressure. With the continuous expansion of the scale of offshore power transmission, the high price of copper materials has gradually increased the pressure on the copper conductor scheme in terms of engineering cost control. Moreover, relevant research in 2025 has made it clear that the manufacturing cost of high voltage DC cables is mainly affected by conductor materials, which further highlights the cost disadvantage of copper conductors; (2) Limited resource supply. As a key mineral resource, copper has limited reserves and supply capacity. The continued growth in demand for submarine cables in the future will further constrain the supply of copper materials, which will bring hidden dangers to the large-scale promotion of engineering; (3) Insufficient engineering adaptability. Copper has a high density, and the weight of the submarine cable is relatively high. In dynamic service scenarios such as deep sea and floating offshore wind power, its engineering adaptability is poor compared with lightweight aluminum conductors, which is not conducive to deep water laying and long-term stable operation under dynamic loads.

[0004] Compared to copper conductors, aluminum and aluminum alloy conductors, although having lower conductivity per unit cross-sectional area, can meet power transmission requirements by reasonably increasing the cross-sectional area. Furthermore, their low density, light weight, and relatively low material cost make them significantly advantageous in submarine cables, especially deep-sea cables, and their application is gradually moving from theoretical feasibility to engineering feasibility. Among these, Al-Mg-Si alloys possess characteristics such as heat-treatable strengthening, good formability and processing properties, and adjustable conductivity, showing potential for development as novel submarine cable conductor materials. Therefore, researching Al-Mg-Si alloys that can meet the requirements of submarine cable conductors has significant theoretical and engineering application value. Summary of the Invention

[0005] This application provides a high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy, its preparation method, and its application, in order to solve the problems of high cost, limited resource supply, and poor engineering adaptability of existing copper conductors.

[0006] The implementation process of this invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy, wherein the alloy has the following elemental composition by mass percentage: Mg 0.5%~1.0%, Si 0.3%~0.8%, Sc 0.04%~0.4%, Zn 0.3%~1.1%, and the balance being Al; raw materials aluminum ingots, Al-20Si master alloy, Al-2Sc master alloy, magnesium ingots, and zinc ingots are prepared according to the elemental composition by mass percentage; the preparation method of the alloy includes the following steps: (1) adding aluminum ingots to a melting furnace and heating and melting them; (2) after heating the melting furnace, adding Al-20Si master alloy and Al-2Sc master alloy. (3) Reduce the power of the melting furnace and add zinc ingots and magnesium ingots after the furnace temperature drops; (4) Reduce the power of the melting furnace again and add aluminum alloy refining agent after the furnace temperature drops; (5) Increase the power of the melting furnace and add aluminum alloy slag removal agent after the furnace temperature rises. After heat preservation, remove slag and add Al-Ti-B grain refiner before casting to obtain alloy ingot rods; (6) Heat the alloy ingot rods for homogenization treatment and process the alloy ingot rods into rods using hot extrusion equipment; (7) Perform solid solution treatment on the rods and obtain supersaturated solid solution rods by rapid cooling. Use a vertical plate drawing machine to cold draw the solid solution rods to obtain wires. Perform aging treatment on the wires to obtain high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloys.

[0008] According to the preferred embodiment of the first aspect, in step (1), the aluminum ingot is heated and melted in the smelting furnace at a temperature of 680-720°C, and the power of the smelting furnace is 10kW.

[0009] According to the preferred embodiment of the first aspect, in step (2), the temperature of the smelting furnace after heating is at least 790°C; and the holding time is at least 10 min.

[0010] According to the preferred embodiment of the first aspect, in step (3), after reducing the power of the smelting furnace to lower the furnace temperature to 740°C, zinc ingots are added, and magnesium ingots are added after an interval of 5 minutes. During the process of adding magnesium ingots, a graphite bell jar is used to press the magnesium ingots into the molten liquid.

[0011] According to the preferred embodiment of the first aspect, in step (4), the power of the smelting furnace is reduced again to lower the furnace temperature to 730°C; the amount of aluminum alloy refining agent added is 0.1 to 0.3% of the total mass of the alloy.

[0012] According to the preferred embodiment of the first aspect, in step (5), the power of the melting furnace is increased to raise the furnace temperature to 730°C, the amount of aluminum alloy slag remover added is 0.1 to 0.3% of the total mass of the alloy, the holding time is at least 10 min, the amount of Al-Ti-B grain refiner added is 0.03 to 0.1% of the total mass of the alloy, and the casting temperature is 730 to 750°C.

[0013] According to the preferred embodiment of the first aspect, in step (6), the heating temperature is 560°C and the heating time is 12h.

[0014] According to the preferred embodiment of the first aspect, in step (7), the temperature of the solution treatment is 550°C and the time of the solution treatment is 2 hours; the temperature of the aging treatment is 180°C and the time of the aging treatment is at least 15 hours.

[0015] In a second aspect, the present invention provides a high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy obtained according to the first aspect.

[0016] Thirdly, the present invention provides an application of the high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy according to the second aspect in submarine cable conductors.

[0017] The positive effects of this invention:

[0018] (1) In the high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy described in this application, Sc is beneficial to the formation of fine and dispersed phases and improves the stability of subsequent microstructure. The addition of Sc changes the precipitation behavior of Mg-Si and the peak aging response, so that the alloy maintains good plasticity while improving strength. After further adding Zn on the basis of low Sc, the strengthening effect of Zn on Al-0.5Si-0.7Mg-0.05Sc alloy is further enhanced, and the 1.0%Zn alloy obtains the best comprehensive mechanical properties.

[0019] (2) The high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy described in this application can obtain high strength and relatively stable conductivity after drawing, showing good potential for application as a submarine cable conductor.

[0020] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0021] The accompanying drawings, which are incorporated herein and form part of this specification, illustrate one or more embodiments of the present application and, together with the description, serve to explain the principles of the present application and to enable those skilled in the art to make and use the present application.

[0022] Figure 1 The images show the hot extrusion production equipment and cold drawing production equipment for alloy wire used in the preparation process of this invention, wherein (1) is the hot extrusion production equipment and (2) is the cold drawing production equipment.

[0023] Figure 2 XRD patterns of as-cast alloys A, B, C, and D;

[0024] Figure 3 The diagram shows the hardness and electrical conductivity of as-cast alloys A, B, C, and D, where (1) hardness and (2) electrical conductivity.

[0025] Figure 4 The graphs show the changes in hardness and electrical conductivity of alloys A and D over aging time, where (1) hardness and (2) electrical conductivity.

[0026] Figure 5 The diagrams show the metallographic structures of alloys A and D in their solution-treated and aged states, where (a, e) represents alloy A in its solution-treated state; (b, f) represents alloy A in its aged state; (c, g) represents alloy D in its solution-treated state; and (d, h) represents alloy D in its aged state.

[0027] Figure 6 Metallographic diagrams of Al-Mg-Si-Sc alloys with different Zn contents are shown, where (a,d) represents 0% Zn; (b,e) represents 0.5% Zn; and (c,f) represents 1% Zn.

[0028] Figure 7 The electrical conductivity and microhardness diagrams of E, D and F as-cast alloys with different Zn contents are shown, where (1) electrical conductivity and (2) microhardness.

[0029] Figure 8 The graphs show the changes in hardness and electrical conductivity of Al-Mg-Si-Sc alloys with different Zn contents over aging time, where (a) hardness and (b) electrical conductivity.

[0030] Figure 9 Metallographic images of Al-Mg-Si-Sc alloys with different Zn contents at the peaks during aging, where (a,d) represent 0% Zn; (b,e) represent 0.5% Zn; and (c,f) represent 1% Zn.

[0031] Figure 10 Stress-strain curves of Al-Mg-Si-Sc alloys with different Zn contents in the solution-treated and peak-aged states are shown, where (a) is the solution-treated state and (b) is the peak-aged state.

[0032] Figure 11 Metallographic images of alloys A, D, E, F, and G after solution treatment and drawing to different diameters: (a) Alloy A, Φ5.5 mm; (b) Alloy A, Φ5.0 mm; (c) Alloy A, Φ4.5 mm; (d) Alloy A, Φ3.0 mm; (e) Alloy D, Φ5.5 mm; (f) Alloy D, Φ5.0 mm; (g) Alloy D, Φ4.5 mm; (h) Alloy D, Φ3.0 mm; (i) Alloy E, Φ5.5 mm; (j) Alloy E, Φ5.0 mm; (k) Alloy E, Φ4.5 mm; (l) Alloy E, Φ3.0 mm; (m) Alloy F, Φ5.5 mm; (n) Alloy F, Φ5.0 mm; (o) Alloy F, Φ4.5 mm; (p) Alloy F, Φ3.0 mm; (q) Alloy G, Φ5.5 mm; (r) Alloy G, Φ5.0 mm. mm; (s)G alloy Φ4.5 mm; (t)G alloy Φ3.0 mm. Detailed Implementation

[0033] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, the description of these embodiments is intended to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to provide a deeper understanding of embodiments of this application.

[0034] In this application, the experimental raw materials used were Al-20Si master alloy, Al-30La master alloy, Al-30Ce master alloy, Al-2Sc master alloy, and aluminum ingots, magnesium ingots, and zinc ingots with a mass percentage of 99.9%. The equipment for hot extrusion and cold drawing of alloy wire in this application is described in [link to relevant documentation]. Figure 1 .

[0035] Use existing formulas to calculate ingredient quantities:

[0036]

[0037]

[0038] In the formula W t For the mass of alloy that needs to be added; W s W represents the total mass of alloy required for smelting. Al The required Al ingot mass is [value missing]; W0% is the partial intermediate alloy burn-off ratio, which, according to previous tests, is approximately 5% for Zn and approximately 5% for Mg; w t % represents the percentage by mass of the added element in the alloy design; w m % represents the mass percentage of a certain alloying element in the intermediate alloy.

[0039] To ensure uniform alloy composition and obtain ingots with dense microstructure and fewer defects, this application requires strict control of melt temperature and the order of addition of each alloying element during the melting and casting process. Al-20Si master alloy and rare earth master alloys (Al-30La, Al-30Ce, and Al-2Sc master alloys) are added at 790 °C and held for 10 min to promote complete melting and initial uniform diffusion of the alloying elements. The reason for choosing a higher temperature to add Si and rare earth master alloys is that the melting and diffusion processes of these master alloys are relatively slow; appropriately increasing the melt temperature helps improve their melting efficiency and avoids localized component segregation. Zn is added after reducing the furnace power to lower the furnace temperature to 740 °C, followed by Mg after a 5-min interval, because Zn and Mg have high reactivity, especially Mg, which is easily oxidized and burned off. Adding them at a lower temperature helps reduce element volatilization and oxidation losses, improving the accuracy of actual composition control. Because Mg has a low density, it tends to float on the surface of the melt after being added. If it is not pressed into the melt in time, it will not only exacerbate oxidation loss but may also affect its uniform distribution in the melt. Therefore, a graphite bell jar is used to press the magnesium ingot into the melt during the Mg addition process, allowing it to melt quickly and fully, thereby effectively reducing the loss rate and improving the composition yield. A refining agent is added for degassing to remove impurities and improve the density of the ingot. The casting temperature in this application is set at 740 ℃. Too high a casting temperature will lead to prolonged solidification time, resulting in abnormally large grains and porosity; too low a temperature will result in insufficient fluidity of the molten aluminum, causing bubbles and impurities to remain inside the ingot, forming pores.

[0040] The alloy compositions of Comparative Examples 1-5 and Examples 1-2 are shown in Table 1.

[0041] Table 1. Elemental composition (mass percentage) of alloy AG

[0042]

[0043] Comparative Example 1 Alloy A

[0044] The preparation method of Al-Mg-Si alloy includes the following steps:

[0045] (1) Prepare raw material aluminum ingots, Al-20Si master alloy and magnesium ingots according to the elemental composition mass percentage of alloy A in Table 1: Mg 0.7%, Si 0.5% and the balance Al;

[0046] (2) Add the aluminum ingots to a 10kW melting furnace and heat them at 720℃ to melt them;

[0047] (3) After heating the furnace to 790°C, add Al-20Si master alloy and hold for 10 min;

[0048] (4) Reduce the power of the smelting furnace, and add magnesium ingots after the furnace temperature drops to 740°C. During the process of adding magnesium ingots, use a graphite bell jar to press the magnesium ingots into the molten liquid.

[0049] (5) Reduce the power of the smelting furnace again, and after the furnace temperature drops to 730°C, add aluminum alloy refining agent. The amount of aluminum alloy refining agent added is 0.2% of the total mass of the alloy.

[0050] (6) Increase the power of the smelting furnace, and after the furnace temperature is raised to 730°C, add aluminum alloy slag remover. The amount of aluminum alloy slag remover added is 0.3% of the total mass of the alloy. After holding the temperature for 10 min, remove the slag, add Al-Ti-B grain refiner, and then cast at 740°C to obtain alloy ingot bars (as-cast state). The amount of Al-Ti-B grain refiner added is 0.05% of the total mass of the alloy.

[0051] (7) The alloy ingot rod is heated at 560℃ for 12h to homogenize it. The alloy ingot rod is processed into a rod using hot extrusion equipment. The extrusion ratio is fixed at 6.0, the extrusion speed is 4 mm / s, and the extrusion temperature is 450℃.

[0052] (8) The rod is solution treated at 550°C for 2 hours and then rapidly cooled to obtain a supersaturated solution rod. The solution rod is then cold-drawn using a vertical drawing machine to obtain a wire. The wire is then aged at 180°C for at least 15 hours to obtain an Al-Mg-Si alloy.

[0053] Comparative Example 2: Alloy B

[0054] The preparation method of Al-Mg-Si-La alloy includes the following steps:

[0055] (1) Prepare raw material aluminum ingots, Al-20Si master alloy, Al-30La master alloy and magnesium ingots according to the element composition mass percentage of alloy B in Table 1: Mg 0.7%, Si 0.5%, La 0.3% and the balance is Al;

[0056] (2) Add the aluminum ingots to a 10kW melting furnace and heat them at 720℃ to melt them;

[0057] (3) After heating the furnace to 790℃, add Al-20Si master alloy and Al-30La master alloy and hold for 10 min;

[0058] (4) Reduce the power of the smelting furnace, and add magnesium ingots after the furnace temperature drops to 740°C. During the process of adding magnesium ingots, use a graphite bell jar to press the magnesium ingots into the molten liquid.

[0059] (5) Reduce the power of the smelting furnace again, and after the furnace temperature drops to 730°C, add aluminum alloy refining agent. The amount of aluminum alloy refining agent added is 0.2% of the total mass of the alloy.

[0060] (6) Increase the power of the smelting furnace, and after the furnace temperature is raised to 730°C, add aluminum alloy slag remover. The amount of aluminum alloy slag remover added is 0.3% of the total mass of the alloy. After holding the temperature for 10 min, remove the slag, add Al-Ti-B grain refiner, and then cast at 740°C to obtain alloy ingot bars (as-cast state). The amount of Al-Ti-B grain refiner added is 0.05% of the total mass of the alloy.

[0061] (7) The alloy ingot rod is heated at 560℃ for 12h to homogenize it. The alloy ingot rod is processed into a rod using hot extrusion equipment. The extrusion ratio is fixed at 6.0, the extrusion speed is 4 mm / s, and the extrusion temperature is 450℃.

[0062] (8) The rod is solution treated at 550°C for 2 hours and then rapidly cooled to obtain a supersaturated solution rod. The solution rod is then cold-drawn using a vertical drawing machine to obtain a wire. The wire is then aged at 180°C for at least 15 hours to obtain an Al-Mg-Si-La alloy.

[0063] Comparative Example 3: C Alloy

[0064] The preparation method of Al-Mg-Si-Ce alloy includes the following steps:

[0065] (1) Prepare raw material aluminum ingots, Al-20Si master alloy, Al-30Ce master alloy and magnesium ingots according to the element composition mass percentage of C alloy in Table 1: Mg 0.7%, Si 0.5%, Ce 0.3% and the balance is Al;

[0066] (2) Add the aluminum ingots to a 10kW melting furnace and heat them at 720℃ to melt them;

[0067] (3) After heating the melting furnace to 790℃, add Al-20Si master alloy and Al-30Ce master alloy and hold for 10 min;

[0068] (4) Reduce the power of the smelting furnace, and add magnesium ingots after the furnace temperature drops to 740°C. During the process of adding magnesium ingots, use a graphite bell jar to press the magnesium ingots into the molten liquid.

[0069] (5) Reduce the power of the smelting furnace again, and after the furnace temperature drops to 730°C, add aluminum alloy refining agent. The amount of aluminum alloy refining agent added is 0.2% of the total mass of the alloy.

[0070] (6) Increase the power of the smelting furnace, and after the furnace temperature is raised to 730°C, add aluminum alloy slag remover. The amount of aluminum alloy slag remover added is 0.3% of the total mass of the alloy. After holding the temperature for 10 min, remove the slag, add Al-Ti-B grain refiner, and then cast at 740°C to obtain alloy ingot bars (as-cast state). The amount of Al-Ti-B grain refiner added is 0.05% of the total mass of the alloy.

[0071] (7) The alloy ingot rod is heated at 560℃ for 12h to homogenize it. The alloy ingot rod is processed into a rod using hot extrusion equipment. The extrusion ratio is fixed at 6.0, the extrusion speed is 4 mm / s, and the extrusion temperature is 450℃.

[0072] (8) The rod is solution treated at 550°C for 2 hours and then rapidly cooled to obtain a supersaturated solution rod. The solution rod is then cold-drawn using a vertical drawing machine to obtain a wire. The wire is then aged at 180°C for at least 15 hours to obtain an Al-Mg-Si-Ce alloy.

[0073] Comparative Example 4: Alloy D

[0074] The preparation method of Al-Mg-Si-Sc alloy includes the following steps:

[0075] (1) Prepare raw material aluminum ingots, Al-20Si master alloy, Al-2Sc master alloy and magnesium ingots according to the element composition mass percentage of alloy D in Table 1: Mg 0.7%, Si 0.5%, Sc 0.3% and the balance Al;

[0076] (2) Add the aluminum ingots to a 10kW melting furnace and heat them at 720℃ to melt them;

[0077] (3) After heating the melting furnace to 790℃, add Al-20Si master alloy and Al-2Sc master alloy and hold for 10 min;

[0078] (4) Reduce the power of the smelting furnace, and add magnesium ingots after the furnace temperature drops to 740°C. During the process of adding magnesium ingots, use a graphite bell jar to press the magnesium ingots into the molten liquid.

[0079] (5) Reduce the power of the smelting furnace again, and after the furnace temperature drops to 730°C, add aluminum alloy refining agent. The amount of aluminum alloy refining agent added is 0.2% of the total mass of the alloy.

[0080] (6) Increase the power of the smelting furnace, and after the furnace temperature is raised to 730°C, add aluminum alloy slag remover. The amount of aluminum alloy slag remover added is 0.3% of the total mass of the alloy. After holding the temperature for 10 min, remove the slag, add Al-Ti-B grain refiner, and then cast at 740°C to obtain alloy ingot bars (as-cast state). The amount of Al-Ti-B grain refiner added is 0.05% of the total mass of the alloy.

[0081] (7) The alloy ingot rod is heated at 560℃ for 12h to homogenize it. The alloy ingot rod is processed into a rod using hot extrusion equipment. The extrusion ratio is fixed at 6.0, the extrusion speed is 4 mm / s, and the extrusion temperature is 450℃.

[0082] (8) The rod is solution treated at 550°C for 2 hours and then rapidly cooled to obtain a supersaturated solution rod. The solution rod is then cold-drawn using a vertical drawing machine to obtain a wire. The wire is then aged at 180°C for at least 15 hours to obtain an Al-Mg-Si-Sc alloy.

[0083] Comparative Example 5 E Alloy

[0084] The preparation method of Al-Mg-Si-Sc alloy includes the following steps:

[0085] (1) Prepare raw material aluminum ingots, Al-20Si master alloy, Al-2Sc master alloy and magnesium ingots according to the element composition mass percentage of alloy E in Table 1: Mg 0.7%, Si 0.5%, Sc 0.05% and the balance Al;

[0086] (2) Add the aluminum ingots to a 10kW melting furnace and heat them at 720℃ to melt them;

[0087] (3) After heating the melting furnace to 790℃, add Al-20Si master alloy and Al-2Sc master alloy and hold for 10 min;

[0088] (4) Reduce the power of the smelting furnace, and add magnesium ingots after the furnace temperature drops to 740°C. During the process of adding magnesium ingots, use a graphite bell jar to press the magnesium ingots into the molten liquid.

[0089] (5) Reduce the power of the smelting furnace again, and after the furnace temperature drops to 730°C, add aluminum alloy refining agent. The amount of aluminum alloy refining agent added is 0.2% of the total mass of the alloy.

[0090] (6) Increase the power of the smelting furnace, and after the furnace temperature is raised to 730°C, add aluminum alloy slag remover. The amount of aluminum alloy slag remover added is 0.3% of the total mass of the alloy. After holding the temperature for 10 min, remove the slag, add Al-Ti-B grain refiner, and then cast at 740°C to obtain alloy ingot bars (as-cast state). The amount of Al-Ti-B grain refiner added is 0.05% of the total mass of the alloy.

[0091] (7) The alloy ingot rod is heated at 560℃ for 12h to homogenize it. The alloy ingot rod is processed into a rod using hot extrusion equipment. The extrusion ratio is fixed at 6.0, the extrusion speed is 4 mm / s, and the extrusion temperature is 450℃.

[0092] (8) The rod is solution treated at 550°C for 2 hours and then rapidly cooled to obtain a supersaturated solution rod. The solution rod is then cold-drawn using a vertical drawing machine to obtain a wire. The wire is then aged at 180°C for at least 15 hours to obtain an Al-Mg-Si-Sc alloy.

[0093] Example 1: Alloy F

[0094] The preparation method of high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy includes the following steps:

[0095] (1) Prepare raw materials aluminum ingots, Al-20Si master alloy, Al-2Sc master alloy, magnesium ingots and zinc ingots according to the elemental composition mass percentage of F alloy in Table 1: Mg 0.7%, Si 0.5%, Sc 0.05%, Zn 0.5% and the balance is Al;

[0096] (2) Add the aluminum ingots to a 10kW melting furnace and heat them at 720℃ to melt them;

[0097] (3) After heating the melting furnace to 790℃, add Al-20Si master alloy and Al-2Sc master alloy and hold for 10 min;

[0098] (4) Reduce the power of the smelting furnace, add zinc ingots after the furnace temperature drops to 740℃, add magnesium ingots after an interval of 5 minutes, and use a graphite bell jar to press the magnesium ingots into the molten liquid during the magnesium ingot addition process.

[0099] (5) Reduce the power of the smelting furnace again, and after the furnace temperature drops to 730°C, add aluminum alloy refining agent. The amount of aluminum alloy refining agent added is 0.2% of the total mass of the alloy.

[0100] (6) Increase the power of the smelting furnace, and after the furnace temperature is raised to 730°C, add aluminum alloy slag remover. The amount of aluminum alloy slag remover added is 0.3% of the total mass of the alloy. After holding the temperature for 10 min, remove the slag, add Al-Ti-B grain refiner, and then cast at 740°C to obtain alloy ingot bars (as-cast state). The amount of Al-Ti-B grain refiner added is 0.05% of the total mass of the alloy.

[0101] (7) The alloy ingot rod is heated at 560℃ for 12h to homogenize it. The alloy ingot rod is processed into a rod using hot extrusion equipment. The extrusion ratio is fixed at 6.0, the extrusion speed is 4 mm / s, and the extrusion temperature is 450℃.

[0102] (8) The rod is solution treated at 550℃ for 2 hours and then rapidly cooled to obtain a supersaturated solution rod. The solution rod is then cold-drawn using a vertical drawing machine to obtain a wire. The wire is then aged at 180℃ for at least 15 hours to obtain a high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy.

[0103] Example 2 G Alloy

[0104] The preparation method of high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy includes the following steps:

[0105] (1) Prepare raw materials aluminum ingots, Al-20Si master alloy, Al-2Sc master alloy, magnesium ingots and zinc ingots according to the elemental composition mass percentage of alloy G in Table 1: Mg 0.7%, Si 0.5%, Sc 0.05%, Zn 1.0% and the balance is Al;

[0106] (2) Add the aluminum ingots to a 10kW melting furnace and heat them at 720℃ to melt them;

[0107] (3) After heating the melting furnace to 790℃, add Al-20Si master alloy and Al-2Sc master alloy and hold for 10 min;

[0108] (4) Reduce the power of the smelting furnace, add zinc ingots after the furnace temperature drops to 740℃, add magnesium ingots after an interval of 5 minutes, and use a graphite bell jar to press the magnesium ingots into the molten liquid during the magnesium ingot addition process.

[0109] (5) Reduce the power of the smelting furnace again, and after the furnace temperature drops to 730°C, add aluminum alloy refining agent. The amount of aluminum alloy refining agent added is 0.2% of the total mass of the alloy.

[0110] (6) Increase the power of the smelting furnace, and after the furnace temperature is raised to 730°C, add aluminum alloy slag remover. The amount of aluminum alloy slag remover added is 0.3% of the total mass of the alloy. After holding the temperature for 10 min, remove the slag, add Al-Ti-B grain refiner, and then cast at 740°C to obtain alloy ingot bars (as-cast state). The amount of Al-Ti-B grain refiner added is 0.05% of the total mass of the alloy.

[0111] (7) The alloy ingot rod is heated at 560℃ for 12h to homogenize it. The alloy ingot rod is processed into a rod using hot extrusion equipment. The extrusion ratio is fixed at 6.0, the extrusion speed is 4 mm / s, and the extrusion temperature is 450℃.

[0112] (8) The rod is solution treated at 550℃ for 2 hours and then rapidly cooled to obtain a supersaturated solution rod. The solution rod is then cold-drawn using a vertical drawing machine to obtain a wire. The wire is then aged at 180℃ for at least 15 hours to obtain a high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy.

[0113] Example 3

[0114] The preparation method of high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy includes the following steps:

[0115] (1) Prepare raw materials aluminum ingots, Al-20Si master alloy, Al-2Sc master alloy, magnesium ingots and zinc ingots according to the mass percentage of the elemental composition of the alloy: Mg 0.5%, Si 0.3%, Sc 0.04%, Zn 0.3% and the balance being Al;

[0116] (2) Add the aluminum ingots to a 10kW melting furnace and heat them at 680℃ to melt them;

[0117] (3) After heating the melting furnace to 790℃, add Al-20Si master alloy and Al-2Sc master alloy and hold for 10 min;

[0118] (4) Reduce the power of the smelting furnace, add zinc ingots after the furnace temperature drops to 740℃, add magnesium ingots after an interval of 5 minutes, and use a graphite bell jar to press the magnesium ingots into the molten liquid during the magnesium ingot addition process.

[0119] (5) Reduce the power of the smelting furnace again, and after the furnace temperature drops to 730°C, add aluminum alloy refining agent. The amount of aluminum alloy refining agent added is 0.1% of the total mass of the alloy.

[0120] (6) Increase the power of the smelting furnace, and after the furnace temperature is raised to 730°C, add aluminum alloy slag remover. The amount of aluminum alloy slag remover added is 0.1% of the total mass of the alloy. After holding the temperature for 10 min, remove the slag, add Al-Ti-B grain refiner, and then cast at 730°C to obtain alloy ingot bars (as-cast state). The amount of Al-Ti-B grain refiner added is 0.03% of the total mass of the alloy.

[0121] (7) The alloy ingot rod is heated at 560℃ for 12h to homogenize it. The alloy ingot rod is processed into a rod using hot extrusion equipment. The extrusion ratio is fixed at 6.0, the extrusion speed is 4 mm / s, and the extrusion temperature is 450℃.

[0122] (8) The rod is solution treated at 550℃ for 2 hours and then rapidly cooled to obtain a supersaturated solution rod. The solution rod is then cold-drawn using a vertical drawing machine to obtain a wire. The wire is then aged at 180℃ for at least 15 hours to obtain a high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy.

[0123] Example 4

[0124] The preparation method of high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy includes the following steps:

[0125] (1) Prepare raw materials aluminum ingots, Al-20Si master alloy, Al-2Sc master alloy, magnesium ingots and zinc ingots according to the mass percentage of the elemental composition of the alloy: Mg 1.0%, Si 0.8%, Sc 0.4%, Zn 1.1% and the balance being Al;

[0126] (2) Add the aluminum ingots to a 10kW melting furnace and heat them at 700℃ to melt them;

[0127] (3) After heating the melting furnace to 790℃, add Al-20Si master alloy and Al-2Sc master alloy and hold for 10 min;

[0128] (4) Reduce the power of the smelting furnace, add zinc ingots after the furnace temperature drops to 740℃, add magnesium ingots after an interval of 5 minutes, and use a graphite bell jar to press the magnesium ingots into the molten liquid during the magnesium ingot addition process.

[0129] (5) Reduce the power of the smelting furnace again, and after the furnace temperature drops to 730°C, add aluminum alloy refining agent. The amount of aluminum alloy refining agent added is 0.3% of the total mass of the alloy.

[0130] (6) Increase the power of the smelting furnace, and after the furnace temperature is raised to 730°C, add aluminum alloy slag remover. The amount of aluminum alloy slag remover added is 0.1% of the total mass of the alloy. After holding the temperature for 10 min, remove the slag, add Al-Ti-B grain refiner, and then cast at 750°C to obtain alloy ingot bars (as-cast state). The amount of Al-Ti-B grain refiner added is 0.1% of the total mass of the alloy.

[0131] (7) The alloy ingot rod is heated at 560℃ for 12h to homogenize it. The alloy ingot rod is processed into a rod using hot extrusion equipment. The extrusion ratio is fixed at 6.0, the extrusion speed is 4 mm / s, and the extrusion temperature is 450℃.

[0132] (8) The rod is solution treated at 550℃ for 2 hours and then rapidly cooled to obtain a supersaturated solution rod. The solution rod is then cold-drawn using a vertical drawing machine to obtain a wire. The wire is then aged at 180℃ for at least 15 hours to obtain a high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy.

[0133] Example 5

[0134] The preparation method of high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy includes the following steps:

[0135] (1) Prepare raw materials aluminum ingots, Al-20Si master alloy, Al-2Sc master alloy, magnesium ingots and zinc ingots according to the mass percentage of the elemental composition of the alloy: Mg 1.0%, Si 0.3%, Sc 0.3%, Zn 0.8% and the balance being Al;

[0136] (2) Add the aluminum ingots to a 10kW melting furnace and heat them at 680℃ to melt them;

[0137] (3) After heating the melting furnace to 790℃, add Al-20Si master alloy and Al-2Sc master alloy and hold for 10 min;

[0138] (4) Reduce the power of the smelting furnace, add zinc ingots after the furnace temperature drops to 740℃, add magnesium ingots after an interval of 5 minutes, and use a graphite bell jar to press the magnesium ingots into the molten liquid during the magnesium ingot addition process.

[0139] (5) Reduce the power of the smelting furnace again, and after the furnace temperature drops to 730°C, add aluminum alloy refining agent. The amount of aluminum alloy refining agent added is 0.1% of the total mass of the alloy.

[0140] (6) Increase the power of the smelting furnace, and after the furnace temperature is raised to 730°C, add aluminum alloy slag remover. The amount of aluminum alloy slag remover added is 0.1% of the total mass of the alloy. After holding the temperature for 10 min, remove the slag, add Al-Ti-B grain refiner, and then cast at 740°C to obtain alloy ingot bars (as-cast state). The amount of Al-Ti-B grain refiner added is 0.03% of the total mass of the alloy.

[0141] (7) The alloy ingot rod is heated at 560℃ for 12h to homogenize it. The alloy ingot rod is processed into a rod using hot extrusion equipment. The extrusion ratio is fixed at 6.0, the extrusion speed is 4 mm / s, and the extrusion temperature is 450℃.

[0142] (8) The rod is solution treated at 550℃ for 2 hours and then rapidly cooled to obtain a supersaturated solution rod. The solution rod is then cold-drawn using a vertical drawing machine to obtain a wire. The wire is then aged at 180℃ for at least 15 hours to obtain a high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy.

[0143] Characterization and performance testing:

[0144] (a) Testing methods

[0145] (1) X-ray diffraction observation

[0146] Phase analysis of the samples was performed using a Rigaku X-ray diffractometer (XRD). Before testing, the sample surface was polished and cleaned to ensure flatness and reduce interference from impurities on the diffraction results. Continuous scanning was used during testing, with the diffraction angle 2θ measured within the range of 20°–90° and a scanning rate of 4° / min. Based on the position and relative intensity of each diffraction peak in the obtained XRD diffraction pattern, the precipitated phases and matrix phases in the sample were determined, thus providing experimental evidence for the analysis of alloy microstructure evolution.

[0147] (2) Metallographic observation

[0148] A rectangular metallographic specimen measuring 10 mm × 8 mm × 6 mm was cut from the cross-section of the ingot, avoiding areas with numerous defects such as shrinkage cavities and abnormally large grains on the top and surface. To ensure the comparability of experimental results, the sampling position and direction of different ingot specimens were kept consistent. The cut specimens were then manually ground sequentially with 400#, 800#, 1200#, 1500#, and 2000# sandpaper to ensure a smooth observation surface and consistent grinding marks. Subsequently, the specimens were first coarsely polished on a polishing machine using 1 μm abrasive paste and a cloth to achieve a mirror finish; then, fine polishing was performed using 0.5 μm abrasive paste until the specimen surface was free of obvious scratches and trailing. After polishing, the specimens were etched using Keller's reagent. The etching time was adjusted appropriately according to the specimen composition and heat treatment state to ensure sufficient visualization of the metallographic structure and clear contours. Finally, the microstructure of the sample was observed and photographed using a ZEISS AXIO Imager A2m optical microscope.

[0149] (3) Mechanical property testing

[0150] Room temperature tensile properties: The room temperature tensile properties of the specimens were tested using an Instron 5966 mini universal testing machine. Uniaxial tension was performed according to the set loading program, with a tensile strain rate of 1×10⁻³ s⁻¹. At least three parallel specimens were taken from each group, and the average value was used. The specimens were processed according to GB / T228.1-2021 "Metallic Materials - Tensile Test Specimens". Based on the stress-strain curves obtained from the tests, the tensile strength, yield strength, and elongation after fracture were calculated to characterize the differences in room temperature mechanical properties of alloys under different compositions and processing conditions.

[0151] Hardness testing: The samples were tested using a Wilson VHX-1102 micro Vickers hardness tester. A load of 100 g was applied and the holding time was 30 s. At least 10 points were selected for hardness testing on each sample, and the average value was taken.

[0152] After the test is completed, the micro Vickers hardness value of the sample is calculated based on the indentation size, which is used to evaluate the degree of hardening and resistance to local deformation of the material under different composition design and process conditions.

[0153] (4) Conductivity test

[0154] The DC resistance of the conductor samples was measured using the four-contact method, and the test was conducted according to the relevant standards of GB / T351-2019 "Methods for Measurement of Resistivity of Metallic Materials" and GB / T3048.4-2025 "Test Methods for Electrical Properties of Wires and Cables Part 4: DC Resistance Test of Conductors". The samples were selected from conductors with smooth surfaces, free from cracks and obvious defects. Before testing, the surface was cleaned to remove dust and oil. The sample length was uniformly 500 mm. The testing equipment was a PC36C DC resistance tester.

[0155] (II) Test Results

[0156] (1) Al-Mg-Si alloy with or without the addition of three different rare earth elements

[0157] Figure 2 The XRD patterns of the as-cast alloys prepared in Comparative Examples 1-4 are shown. In the figures, the diffraction peaks of the four alloys A, B, C and D are mainly concentrated around 238°, 45°, 65°, 78° and 82°, which all correspond to the characteristic diffraction peaks of the α-Al matrix, indicating that each alloy is mainly composed of α-Al solid solution.

[0158] Table 2 Tensile properties of as-cast alloys A, B, C and D prepared in Comparative Examples 1-4

[0159]

[0160] As can be seen from Table 2, the addition of Sc to the alloy significantly improves the load-bearing capacity and deformation resistance, but at the same time significantly reduces the plasticity, making it more inclined to obtain a mechanical response with high strength rather than high plasticity.

[0161] Figure 3 The hardness and electrical conductivity diagrams of the as-cast alloys A, B, C, and D prepared in Comparative Examples 1-4 are shown below. Figure 3 As can be seen from (1), the addition of La and Ce to the alloy reduces the hardness to a certain extent, while Sc has a significant effect on improving the strength. Figure 3 As can be seen from (2), the alloy conductivity further decreased by 1.6% IACS after the addition of Sc. Although Sc can also interact with Si to form the (Al,Si)3Sc phase, the typical precipitation behavior of Sc in aluminum alloys is to form fine reinforcing phases such as Al3Sc / (Al,Si)3Sc and remain in the matrix. These particles cause more lattice distortion and fine defects, and increase electron scattering.

[0162] The D alloy with added Sc showed a more significant improvement in hardness and mechanical properties, demonstrating considerable value for subsequent heat treatment research. Subsequent solution-aging treatment studies selected the A alloy without rare metal elements and the D alloy with added Sc as representative samples, focusing on the influence of aging time on its microstructure and properties, and further analyzing the microstructure and property characteristics under peak aging conditions.

[0163] Figure 4 The figures show the changes in hardness (1) and electrical conductivity (2) of alloys A and D over aging time. Both alloys exhibit typical aging response characteristics, with overall hardness increasing and electrical conductivity also showing an upward trend. This indicates that the supersaturated solid solution formed after solution treatment undergoes continuous precipitation during aging, gradually reducing the solute atom content in the matrix, thereby enhancing precipitation strengthening and weakening electron scattering. Alloy A exhibits a faster aging response and a higher peak strengthening effect at 180 ℃, while the peak aging time of alloy D shifts significantly later, and the peak hardness is lower. This suggests that the addition of Sc alters the precipitation behavior of Mg and Si elements in the alloy and the state of solute atoms in the matrix, thus changing the aging precipitation kinetics.

[0164] Figure 5 The figures show the metallographic structures of alloys A and D in the solution-treated and aged state. In the Al-Mg-Si alloy, a certain number of coarse granular and short rod-shaped secondary phases remain in the solution-treated state. Based on the common microstructural characteristics of Al-Mg-Si alloys, these residual phases are likely Al-Fe-Si intermetallic compounds, indicating that some refractory phases failed to completely dissolve into the α-Al matrix after solution treatment. After peak aging, the morphology of the coarse secondary phases does not change significantly, but the overall microstructure becomes more uniform, indicating that peak aging strengthening mainly originates from the formation of fine, dispersed precipitates within the matrix, rather than an increase in coarse, visible secondary phases. In contrast, alloy D with added Sc shows a significant reduction in coarse, isolated secondary phases in the solution-treated state, with clearer grain boundary outlines and better microstructure uniformity. After peak aging, fine dot-like or chain-like secondary phases are still visible near the grain boundaries, and the overall microstructure is finer than that of the base alloy. This indicates that the addition of Sc not only improved the initial microstructure in the as-cast state, but also retained a relatively fine and uniform microstructure after solution treatment and aging, which is closely related to its grain refinement effect.

[0165] Table 3 Tensile properties of cast alloys A and D prepared in Comparative Examples 1 and 4 after solution treatment and solution aging.

[0166]

[0167] Table 3 shows that solution treatment significantly improved the plasticity of both alloys compared to the as-cast state. The alloy containing Sc maintained a high strength level while further improving plasticity, exhibiting a superior strength-plasticity balance. This indicates that solution treatment promoted microstructure homogenization, mitigating the destructive effects of segregation and coarse second phases on deformation compatibility in the as-cast microstructure, while the addition of Sc still effectively contributed to the matrix strength. Peak-aged tensile results showed that, compared to alloy A, the tensile strength of the alloy with added Sc was significantly improved. Although the yield strength was close to that of the matrix alloy, the elongation was greatly increased, indicating that the addition of Sc did not sacrifice plasticity for increased strength, but rather significantly optimized the strength-plasticity balance of the alloy under the existing solution-aging regime. The addition of Sc not only improved the load-bearing capacity of the alloy but also effectively delayed local strain concentration and crack initiation and propagation. The reason may be related to the refining effect of Sc on the as-cast structure, the reduction of coarse primary phases after solution treatment, and the more dispersed and uniform distribution of precipitated phases during peak aging, so that the alloy can maintain good deformation coordination while improving strength.

[0168] In summary, in the as-cast state, the addition of 0.3% Sc significantly improved the tensile strength and yield strength of the alloy, but reduced its plasticity. Based on the comparison of as-cast properties, alloy A (matrix) and alloy D (containing 0.3% Sc) were selected as the subjects for subsequent heat treatment research. During aging at 180℃, both alloys exhibited typical aging response characteristics, but the peak aging time of alloy D was extended from 12 h for alloy A to 18 h, indicating that the addition of Sc altered the Mg-Si precipitation kinetics. In the peak-aged state, the tensile strength and elongation after fracture of alloy D were significantly better than those of alloy A; at the same time, the conductivity of alloy D was 49.47% IACS, lower than that of alloy A (54.35% IACS), indicating that the addition of Sc resulted in higher strength and better plasticity while sacrificing some conductivity. Based on the results of metallography, SEM, TEM, EDS and statistical analysis of precipitates, it can be seen that the addition of Sc not only refines the grains, but also provides experimental basis for the composition design and heat treatment process optimization of this type of high-strength conductive aluminum alloy.

[0169] (2) Combining Comparative Example 1, Comparative Example 5, and Examples 1-2, the influence of Zn on the microstructure and mechanical properties of Al-Mg-Si alloy was systematically studied by adjusting the Zn content.

[0170] Figure 6The figures show the metallographic structures of Al-Mg-Si-Sc alloys with different Zn contents. Alloys E, F, and G are mainly composed of equiaxed α-Al grains with relatively clear grain boundaries and a relatively uniform overall microstructure, without obvious coarse dendrites. Alloy E has a relatively clean microstructure with fewer dark phases at grain boundaries, but the grains are generally large and have a wide size distribution, with some coarse grains visible locally, indicating a certain tendency for mixed crystals. However, the microstructure uniformity is significantly improved compared to the alloy with 0.3% Sc added. As the Sc content decreases in the three alloys, the corresponding grain refinement effect weakens, and the average grain size increases. After adding 0.5% Zn, the F alloy shows an increase in dark granular or short-chain structures at grain boundaries and triple-grain boundaries, with grain refinement compared to the unadded alloy and a decrease in the number of coarse grains. When the Zn content increases to 1.0%, the G alloy has a more regular grain morphology and a further increase in dark phases near the grain boundaries, with increased local microstructure inhomogeneity. This indicates that the addition of Zn did not change the basic microstructure of the alloy, which is dominated by equiaxed crystals, but it will promote the precipitation of the second phase or the segregation of elements near the grain boundaries to a certain extent.

[0171] Table 4 Tensile properties of as-cast alloys A, E, F, and G prepared in Comparative Examples 1, 5, and 1-2

[0172]

[0173] As shown in Table 4, compared with alloy A, the addition of 0.05% Sc significantly improved the tensile strength and yield strength of alloy E, while the elongation remained relatively unchanged. This indicates that trace amounts of Sc can still significantly improve the strength of alloy A without significantly sacrificing plasticity. Further comparison of the three low-Sc alloys E, F, and G reveals that alloy E has the highest yield strength but the lowest plasticity. The addition of 0.5% Zn slightly decreased the tensile strength and yield strength of alloy E, but significantly increased the elongation after fracture, indicating that an appropriate amount of Zn is beneficial for improving plasticity. When the Zn content increased to 1.0%, alloy G achieved the highest tensile strength while maintaining a high elongation, exhibiting the best overall mechanical properties. This demonstrates that the addition of Zn can further regulate the strength-plasticity balance of the Al-0.5Si-0.7Mg-0.05Sc alloy, with 1.0% Zn being more beneficial for optimizing overall performance.

[0174] Figure 7The figures show the electrical conductivity (1) and microhardness (2) of as-cast alloys E, D, and F with different Zn contents. It can be seen that the electrical conductivity of alloys E, F, and G are 51.06%, 50.27%, and 49.62% IACS, respectively, indicating that the addition of Zn leads to a continuous decrease in the alloy's electrical conductivity. With increasing Zn content, the overall hardness of the alloy increases, indicating that the addition of Zn has a significant strengthening effect on the alloy. This change is usually related to solid solution strengthening, precipitation strengthening, and changes in the distribution of dispersed phases in the microstructure. Zn atoms entering the α-Al matrix cause certain lattice distortion, thereby increasing the resistance to dislocation movement; simultaneously, the addition of Zn may also change the distribution state of Mg and Si elements in the matrix and affect subsequent precipitation behavior, thus improving the overall hardening level of the alloy.

[0175] Figure 8 The figures show the changes in hardness and electrical conductivity of Al-Mg-Si-Sc alloys with different Zn contents over aging time. (a) Hardness; (b) Electrical conductivity. In the figures, alloys E, F, and G all exhibit a common pattern of "hardness increasing first, electrical conductivity decreasing first and then increasing" during aging at 180 ℃, indicating that all three alloys underwent a transition from a quenched supersaturated solid solution to a precipitation-strengthened state. In the initial stage of aging, solute atoms agglomerate and form numerous atomic clusters or GP regions, leading to a rapid increase in hardness. Simultaneously, due to enhanced scattering from fine clusters, interfaces, and defects, electrical conductivity temporarily decreases. As aging continues, the strengthening phase further precipitates, reducing the matrix solubility, thus gradually increasing the electrical conductivity. For alloy E, the quenched hardness is 47.4 HV, which increases to 63.9 HV and 76.9 HV after aging for 0.5 h and 1 h, respectively, indicating a rapid early-stage hardening response. The hardness of alloy F in the quenched state was 43.1 HV; its electrical conductivity increased from 47.73 % IACS to 51.95 % IACS after 15 hours, indicating that 0.5% Zn slowed down the precipitation kinetics and widened the aging window. The hardness of alloy G in the quenched state was 42.91 HV, the lowest among the three alloys, but its aging response speed was significantly improved, reaching 98 HV after only 3 hours of aging, surpassing the other two alloys. However, its electrical conductivity dropped to a minimum of 46.57 % IACS after 1 hour, then rebounded to 51.42 % IACS after 15 hours. This indicates that 1.0% Zn significantly enhanced early precipitation strengthening, but also exacerbated early electron scattering.

[0176] Based on the peak aging characteristics of the three alloys, alloy E maintains a high hardness plateau of approximately 100 HV within 6–18 h, while its conductivity reaches 52.9% IACS at 18 h, exhibiting the best conductivity. The peak aging of alloy F shifts significantly later, maintaining 96.8–98.5 HV between 15 and 18 h, and its conductivity reaches 51.95% IACS at 15 h, indicating that it has the widest process window. Alloy G achieves its highest peak hardness of 106.1 HV at 6 h, but its conductivity is only 49.13% IACS at this point. If the aging is extended to 15 h, the hardness is still 99.8 HV, only about 5.85% lower than the peak value, while the conductivity increases by 2.29% IACS.

[0177] Figure 9 The figures show the peak-aged metallographic structures of Al-Mg-Si-Sc alloys with different Zn contents: (a,d) 0% Zn; (b,e) 0.5% Zn; (c,f) 1% Zn. In the figures, alloy E has medium grain size, but some black particles and agglomeration still exist in local areas, indicating that some coarse second phase remains after solution treatment. Alloy F has relatively large grains, clear grain boundaries, and a relatively clean structure, indicating that the second phase is fully dissolved, but accompanied by some grain growth. Alloy G has finer and more uniform grains than F, with a certain number of dispersed particles within the grains, exhibiting obvious fine-grained and dispersed particle distribution characteristics. Overall, the change in Zn content has a significant impact on the grain size and second phase distribution of the alloy after solution treatment and aging.

[0178] Table 5 Tensile properties of cast alloys E, F, and G prepared in Comparative Example 5 and Examples 1-2 after solution treatment and solution aging.

[0179]

[0180] Figure 10 Stress-strain curves of Al-Mg-Si-Sc alloys with different Zn contents in the solution-treated and peak-aged states are shown: (a) solution-treated state; (b) peak-aged state. Figure 10 As shown in Table 5, alloy F exhibits the highest yield strength at peak aging, indicating that the addition of 0.5% Zn enhances the initial resistance to plastic deformation. Alloy G, on the other hand, shows the highest tensile strength at peak aging, suggesting that 1.0% Zn is more beneficial for achieving a better strength-ductility balance. Overall, the addition of Zn significantly improves the mechanical properties of the Al-0.5Si-0.7Mg-0.05Sc alloys in the peak-aged state, with alloy G showing the best comprehensive performance. The tensile test results in the solution-treated state show that alloy G has the highest yield strength, indicating that the addition of 1.0% Zn improves the initial resistance to deformation.

[0181] In summary, the alloy hardness gradually increases with increasing Zn content, while the electrical conductivity decreases, indicating that the addition of Zn has a positive effect on material strengthening. However, combining the tensile results in the solution-treated and peak-aged states, it is clear that the property regulation by Zn is not primarily derived from simple solution strengthening, but mainly manifested in its influence on precipitation behavior and microstructure evolution during aging. In the solution-treated state, Zn has limited effect on tensile strength, and excessively high Zn content can even lead to a decrease in plasticity. In the peak-aged state, the addition of Zn significantly improves the strength-plasticity balance of the alloy. Specifically, 0.5% Zn is beneficial for improving yield strength, while 1.0% Zn gives the alloy the highest tensile strength, hardness, and elongation after fracture, exhibiting the best comprehensive mechanical properties. Overall, the addition of appropriate Zn can significantly improve the comprehensive properties of Al-0.5Si-0.7Mg-0.05Sc alloys by regulating precipitation strengthening and microstructure characteristics during the solution-aging process, with the 1.0% Zn alloy exhibiting the optimal strength-plasticity balance.

[0182] (3) Metallographic structure of alloys A, D, E, F, and G after solution treatment and drawing to wires of different diameters

[0183] Figure 11 Metallographic structures of alloys A, D, E, F, and G drawn to wires of different diameters after solution treatment are shown in the figures. (ad) Alloy A; (eh) Alloy D; (il) Alloy E; (mp) Alloy F; (qt) Alloy G. In the figures, the original polygonal equiaxed grain outlines are still clearly visible in the Φ5.5 mm and Φ5.0 mm samples of alloy A during the initial drawing stage. The microstructure is still dominated by the grain skeleton after early solution treatment or recrystallization, and the deformation has not yet fully altered the microstructure. When the size is reduced to Φ4.5 mm, the grain boundary outlines gradually weaken, and the banded and parallel streamline features begin to strengthen, showing a trend of transition from equiaxed grains to elongated grains. After further reducing to Φ3.0 mm, the parallel bands are most obvious in the microstructure, and the original equiaxed grain boundaries have been significantly weakened, exhibiting a typical strong deformation fibrous microstructure.

[0184] Alloy D maintained a stable fibrous microstructure throughout the drawing process. In the early stages of drawing, strong parallel streamlines and banded fibrous structures were observed in the samples, unlike Alloy A, which still exhibited a clear equiaxed grain profile. As the size further decreased to Φ5.0 mm, Φ4.5 mm, and Φ3.0 mm, the microstructure maintained significant directionality, with finer, more parallel, and more uniformly distributed bands, without any obvious coarse equiaxed grain residue. The addition of Sc significantly enhanced the thermal stability and deformation retention of the microstructure, allowing the material to exhibit obvious banded streamline characteristics even at larger sizes, and continuing to evolve towards a finer, more uniform fibrous structure during subsequent large deformation drawing, rather than undergoing a distinct "equiaxed grain to elongated grain" transition process.

[0185] Similar to alloy A, alloys E, F, and G retain a predominantly coarse recrystallized grain structure in the early, larger-sized stages. However, when the size is further reduced to Φ4.5 mm and Φ3.0 mm, the original coarse grain profile rapidly weakens, and the microstructure quickly transforms into a banded and fibrous streamline structure extending clearly along the drawing direction. The elongation marks are significantly enhanced. This is likely due to the addition of Zn altering the initial microstructure and the response to subsequent drawing deformation, resulting in a distinct staged and transitional microstructure evolution. Overall, Sc is the dominant factor controlling the microstructure stability and fibrous uniformity during the drawing process.

[0186] The novel high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy described in this application undergoes a homogenization treatment at 560 ℃ for 12 h. This homogenization treatment effectively promotes the redistribution of elements such as Mg, Si, Sc, and Zn, and provides a relatively stable initial microstructure for subsequent hot working. The hot extrusion process significantly breaks down the coarse as-cast microstructure and improves casting defects, resulting in a significantly refined wire microstructure. After solution treatment, Sc has the effect of inhibiting recrystallization and stabilizing the inherited microstructure from hot extrusion. However, reducing the Sc content or further adding Zn weakens this inhibitory effect, making the material more prone to recrystallization during solution treatment, accompanied by a certain degree of grain growth. Cold drawing causes all five alloy wires to form typical fibrous deformed microstructures, with significant elongation of grains along the drawing direction, reduced transverse characteristic dimensions, and increased local orientation gradient and deformation energy storage. In this application, there are significant differences in dislocation evolution, substructure formation, and microstructure homogenization capabilities among different composition systems during the drawing process. During wire processing, a clear microstructure evolution pattern emerges: "homogenization and desegregation – hot extrusion refinement and formation of reverting substructure – solid solution re-dissolution and induced recrystallization – cold drawing fiberization and energy accumulation." Among these, Sc plays a positive role in the thermal stability of the microstructure and the maintenance of the deformed microstructure, while the addition of Zn further alters the recrystallization behavior and the subsequent drawn microstructure characteristics.

[0187] (4) Properties of alloy wire

[0188] Table 6 Tensile properties of alloy wires A, D, E, F and G prepared by Comparative Examples 1, 4-5 and Examples 1-2 after homogenization, hot extrusion, solution treatment, cold drawing and aging treatment

[0189]

[0190] As can be seen from Table 6, after homogenization, hot extrusion, solution treatment and cold drawing to 4mm, the tensile properties of the five alloy wires can be summarized as follows: yield strength is E > G > F > D > A, tensile strength is G > F > E > D > A, and elongation after fracture is G > E > F > D > A.

[0191] Among them, alloy A had the lowest strength and plasticity, indicating that relying solely on solid solution strengthening and cold drawing deformation strengthening of the Al-0.5Si-0.7Mg matrix is ​​insufficient to achieve an excellent strength-plasticity balance. After adding 0.3% Sc, the yield strength, tensile strength, and elongation after fracture of alloy D all increased compared to A, indicating that the addition of Sc helps improve microstructure stability and enhance dislocation movement resistance; however, the performance improvement is limited. When the Sc content decreased to 0.05%, the yield strength and plasticity of alloy E significantly improved, exhibiting an excellent strength-plasticity balance. This shows that a lower Sc content can retain a certain degree of microstructure stability and dispersion strengthening while mitigating the damage to plasticity caused by the coarse second phase under high Sc conditions, thus enabling the wire to achieve higher load-bearing capacity and better elongation after fracture after cold drawing. Further addition of Zn to alloy E further increased the tensile strength of alloys F and G, indicating that Zn in the unequal cold-drawn state mainly functions through additional solid solution strengthening and improving the load-bearing capacity during the plastic flow stage. In particular, alloy G achieved the highest elongation after fracture while maintaining high strength, indicating that 1.0% Zn is more beneficial for improving the material's ability to undergo local deformation and resist early cracking, thus achieving optimal overall tensile properties. All five alloys exhibited more pronounced cold work strengthening characteristics after being drawn to 3 mm, but the responses of different composition systems showed significant differentiation. For alloy A, the yield strength, tensile strength, and elongation after fracture all increased after reducing the wire diameter; for alloy D, the yield strength and tensile strength also increased, but the elongation after fracture decreased, indicating that its plasticity coordination weakened after further drawing. The changes in alloy E were relatively stable, with both yield strength and tensile strength increasing, and the elongation after fracture still slightly increasing, indicating that the material still has good plasticity reserves after further cold deformation under low Sc conditions. In contrast, Zn-containing alloys are more sensitive to additional drawing: F's tensile strength increases to 298 MPa, making it the alloy with the highest ultimate bearing capacity among the five alloys, but its elongation after fracture drops sharply from 19.1% to 11.6%, exhibiting typical "high strength, low plasticity" characteristics; G's yield strength increases from 254 MPa to 276 MPa, its tensile strength remains at a high level, and it still maintains 15% elongation after fracture, indicating that 1.0% Zn is more conducive to balancing strength and plasticity after further drawing. Overall, after the wire diameter is reduced from 4 mm to 3 mm, the material strengthening mainly comes from the further increase in dislocation density and the accumulation of work hardening. The regulatory role of Sc and Zn on this cold deformation response determines the final performance differentiation: the high Sc system has more obvious plasticity loss, the low Sc system has better stability, 0.5% Zn tends to promote the development of materials towards high strength, while 1.0% Zn is more conducive to obtaining a better strength-plasticity balance. Among them, the G alloy maintains the best comprehensive tensile properties after both stages of drawing.

[0192] Table 7. Unaged and peak-aged electrical conductivity of alloy wires A, D, E, F, and G prepared by Comparative Examples 1, 4-5, and 1-2 after homogenization, hot extrusion, solution treatment, cold drawing, and aging treatment.

[0193]

[0194] As shown in Table 7, after the wire was further drawn from Φ4mm to Φ3mm, the change in the unaged conductivity of each alloy was generally small. This indicates that within the current deformation range, simply increasing the drawing deformation has a relatively limited direct impact on the conductivity of the wire, and the conductivity does not fluctuate significantly with increasing deformation. This suggests that, compared to electron scattering caused by deformation defects such as dislocations and substructures, the conductivity of the wire is still mainly controlled by the state of solid solution atoms in the matrix and subsequent precipitation behavior. According to the literature, the effect of drawing deformation on the conductivity of Al-Mg-Si conductor alloys is usually not a simple monotonic relationship, but mainly depends on the competition between the effects of "deformation defects enhancing electron scattering" and "deformation promoting subsequent precipitation and purifying the matrix."

[0195] After peak aging, alloys of different compositions exhibit significant differences in their response to deformation: some alloys show almost unchanged conductivity at Φ4mm and Φ3mm, indicating they are insensitive to the amount of drawing deformation; some alloys show a slight increase in conductivity at Φ3mm, suggesting that the larger pre-deformation may promote the precipitation and redistribution of solute atoms during aging, thereby reducing electron scattering in the matrix; while the matrix alloy shows a more significant change in conductivity, indicating that its precipitation process is more sensitive to early deformation defects. Overall, alloys of different compositions are not equally sensitive to the amount of drawing deformation. This difference essentially reflects the differences in the stability of the defect structure after deformation, the migration ability of solute atoms, and the peak aging precipitation response of each alloy. Therefore, the effect of the amount of drawing deformation on conductivity is not simply "the greater the deformation, the lower the conductivity" or "the higher the conductivity," but rather it is indirectly manifested by regulating the defect structure and subsequent precipitation kinetics, and shows a clear compositional dependence.

[0196] In the alloys described in this application, Sc is more conducive to the formation of fine dispersed phases and improves the stability of subsequent microstructure. Among the elements studied, Sc has the most significant strengthening effect on the alloy. After solution-aging treatment, the D alloy containing 0.3% Sc exhibits a better strength-ductility match. The addition of Sc changes the precipitation behavior of Mg-Si and the peak aging response, allowing the alloy to maintain good ductility while improving strength. The peak aging tensile strength and elongation after fracture of the D alloy are improved, but the conductivity is lower than that of the matrix alloy, indicating that Sc strengthening has a significant effect on strength improvement, while its adverse effect on conductivity still needs to be comprehensively weighed. After further adding Zn to the low Sc base, the strengthening effect of Zn on the Al-0.5Si-0.7Mg-0.05Sc alloy is further enhanced. With the increase of Zn content, the alloy hardness increases while the conductivity decreases, indicating that Zn helps to improve the material strength, but also exacerbates electron scattering. In the peak aging state, Zn can significantly improve the strength-ductility match of the alloy, with the 1.0% Zn alloy achieving the best comprehensive mechanical properties. After the alloy described in this application is further drawn from Φ4 mm to Φ3 mm, the overall strength of the wires with different compositions shows a certain degree of improvement, but the changes in plasticity and conductivity differ significantly. The results indicate that the drawn properties are not only affected by the amount of deformation, but also closely related to dislocation accumulation, substructure formation, grain boundary characteristics, and texture evolution. Overall, the low Sc-Zn composite-controlled alloy can achieve high strength and relatively stable conductivity after drawing, showing good potential for use as a submarine cable conductor.

[0197] Other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and this application is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A method for preparing a high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy, characterized in that, The alloy has the following elemental composition by mass percentage: Mg 0.5%~1.0%, Si 0.3%~0.8%, Sc 0.04%~0.4%, Zn 0.3%~1.1%, with the balance being Al; raw materials aluminum ingots, Al-20Si master alloy, Al-2Sc master alloy, magnesium ingots, and zinc ingots are prepared according to the elemental composition by mass percentage of the alloy. The preparation method of the alloy includes the following steps: (1) Add aluminum ingots to a smelting furnace and heat to melt them; (2) After heating the smelting furnace, add Al-20Si master alloy and Al-2Sc master alloy and keep it at the temperature; (3) Reduce the power of the smelting furnace and add zinc ingots and magnesium ingots after the furnace temperature drops; (4) Reduce the power of the smelting furnace again, and add aluminum alloy refining agent after the furnace temperature drops; (5) Increase the power of the melting furnace, add aluminum alloy slag remover after the furnace temperature is raised, remove slag after heat preservation, add Al-Ti-B grain refiner and then cast to obtain alloy ingot bar material. (6) Heat the alloy ingot bar to homogenize it, and process the alloy ingot bar into rods using hot extrusion equipment; (7) The rod is subjected to solution treatment and rapid cooling to obtain a supersaturated solution rod. The solution rod is then cold-drawn using a vertical drawing machine to obtain a wire. The wire is then aged to obtain a high-strength and high-conductivity Al-Mg-Si-Sc-Zn alloy.

2. The method for preparing the high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy according to claim 1, characterized in that: In step (1), the aluminum ingot is heated and melted in the smelting furnace at a temperature of 680-720°C, and the power of the smelting furnace is 10kW.

3. The method for preparing the high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy according to claim 1, characterized in that: In step (2), the temperature of the smelting furnace after heating is at least 790°C; the holding time is at least 10 min.

4. The method for preparing the high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy according to claim 1, characterized in that: In step (3), zinc ingots are added after the furnace power is reduced to 740°C, and magnesium ingots are added after a 5-minute interval. During the addition of magnesium ingots, a graphite bell jar is used to press the magnesium ingots into the molten liquid.

5. The method for preparing the high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy according to claim 1, characterized in that: In step (4), the power of the smelting furnace is reduced again to lower the furnace temperature to 730°C; the amount of aluminum alloy refining agent added is 0.1 to 0.3% of the total mass of the alloy.

6. The method for preparing the high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy according to claim 1, characterized in that: In step (5), the power of the melting furnace is increased to raise the furnace temperature to 730°C. The amount of aluminum alloy slag remover added is 0.1 to 0.3% of the total mass of the alloy, and the holding time is at least 10 min. The amount of Al-Ti-B grain refiner added is 0.03 to 0.1% of the total mass of the alloy. The casting temperature is 730 to 750°C.

7. The method for preparing the high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy according to claim 1, characterized in that: In step (6), the heating temperature is 560℃ and the heating time is 12h.

8. The method for preparing the high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy according to claim 1, characterized in that: In step (7), the solution treatment temperature is 550°C and the solution treatment time is 2 hours; the aging treatment temperature is 180°C and the aging treatment time is at least 15 hours.

9. A high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy obtained by the method according to any one of claims 1 to 8.

10. The application of the high-strength, high-conductivity Al-Mg-Si-Sc-Zn alloy according to claim 9 in submarine cable conductors.

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