High-strength high-conductivity heat-resistant aluminum alloy wire and preparation method thereof

Abstract

The application provides a high-strength high-conductivity heat-resistant aluminum alloy wire and a preparation method thereof. The aluminum alloy wire comprises the following components in percentage by mass: Ce 0.05-0.25%, La 0.03-0.20%, Sc 0.10-0.35%, Y 0.08-0.30%, Fe 0.10-0.40%, Si 0.02-0.20%, Ti+V+Cr < 0.005%, other impurities < 0.01% individually, < 0.05% in total, and the balance being Al. The aluminum alloy wire comprises micron-sized spherical composite bodies and nanometer-sized Al3Sc precipitates. The spherical composite bodies comprise Fe-rich phases and Si-rich phases. The Fe-rich phases comprise Al, Fe and Y. The Si-rich phases comprise Al, Si, Ce, La and Y. The aluminum alloy wire according to the application can realize the synergistic improvement of high strength, high conductivity and excellent heat resistance.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal material processing technology, specifically relating to an aluminum alloy wire and its preparation method that can achieve spheroidization control of Fe-rich and Si phases and efficient removal of harmful impurities, thereby obtaining a synergistic improvement in high strength, high conductivity and excellent heat resistance. Background Technology

[0002] Aluminum alloy conductors are widely used in overhead power transmission lines, electrical equipment, and automotive wiring harnesses due to their lightweight, good conductivity, and excellent corrosion resistance. With the continuous increase in power transmission capacity and increasingly stringent energy loss requirements, higher demands are being placed on the conductivity, strength, and heat resistance of aluminum alloy conductors.

[0003] Traditional industrial pure aluminum (such as 1070 and 1350 aluminum alloys) has high conductivity (up to 61%~62% IACS), but low strength (tensile strength of about 60~130MPa), making it difficult to meet the mechanical performance requirements of long-span, heavy-load lines. To improve strength, alloying elements such as Mg, Si, and Zr are usually added to form reinforcing phases (such as Mg2Si, Al3Zr, etc.). However, the solid solution alloying elements and the coarse second phase cause strong electron scattering, resulting in a significant decrease in conductivity (usually down to 50%~58% IACS).

[0004] In terms of heat resistance, the long-term operating temperature of ordinary aluminum alloy conductors generally does not exceed 90℃. After operating at higher temperatures (such as above 150℃), the strength decreases, making it difficult to meet the needs of capacity expansion and upgrading of large-capacity transmission lines.

[0005] In addition, Fe and Si in conventional aluminum alloys mostly exist as lamellar AlFeSi phases. This morphology leads to severe stress concentration and microcracks, which is the main reason for the poor ductility and toughness of aluminum alloys. It also reduces the electrical conductivity of aluminum alloys.

[0006] In addition, industrial pure aluminum usually contains trace impurity elements such as Ti, V, and Cr. These elements have extremely low solid solubility in aluminum, but they are extremely harmful to electrical conductivity. Although conventional boronizing treatment of Al-B alloys can partially remove these harmful elements, there are the following problems: (1) B in Al-B alloys has low activity and does not react fully with Ti, V, and Cr; (2) The generated borides (such as TiB2) are easy to aggregate and grow, and are difficult to effectively settle and remove, thus damaging the alloy properties.

[0007] To improve the overall performance of aluminum alloys, researchers have attempted to add rare earth elements. Literature reports aluminum alloy wires containing La and Ce rare earth elements, utilizing the reaction of rare earth elements with Fe to form compounds, causing Fe to change from a solid solution state to a precipitated state, thus improving conductivity. Other patents disclose aluminum alloy materials containing multiple rare earth elements such as Sc, Y, La, and Ce. However, improper order of rare earth element addition during the smelting process leads to the formation of coarse rare earth phases, making it difficult to effectively improve the morphology of Fe-rich and Si-rich phases, and offering limited improvement in heat resistance, thus failing to meet the requirements for long-term use under high-temperature conditions.

[0008] Therefore, there is a need to develop an aluminum alloy conductor with synergistic improvement in high strength, high conductivity, and excellent heat resistance, as well as its preparation method. Summary of the Invention

[0009] Technical problems to be solved The present invention aims to solve the technical problem that existing aluminum alloy wires are difficult to achieve simultaneously with high strength, high conductivity and excellent heat resistance, and provides an aluminum alloy wire and its preparation method that synergistically improves high strength, high conductivity and excellent heat resistance.

[0010] Technical solution To achieve the above objectives, the present invention adopts the following technical solution.

[0011] According to an embodiment of the present invention, a high-strength, high-conductivity, and heat-resistant aluminum alloy wire is provided. The aluminum alloy wire comprises the following components by mass percentage: Ce 0.05-0.25%, La 0.03-0.20%, Sc 0.10-0.35%, Y 0.08-0.30%, Fe 0.10-0.40%, Si 0.02-0.20%, Ti+V+Cr < 0.005%, other impurities ≤ 0.01% individually, ≤ 0.05% in total, and the balance being Al. The aluminum alloy wire comprises micron-sized spherical composites and nano-sized Al3Sc precipitates. The spherical composites comprise Fe-rich and Si-rich phases. The Fe-rich phase contains Al, Fe, and Y, and the Si-rich phase contains Al, Si, Ce, La, and Y.

[0012] Optionally, the Fe-rich phase further comprises Ce, La, and Si, and the atomic content of each of Ce, La, and Si in the Fe-rich phase is less than the atomic content of each of Al, Fe, and Y in the Fe-rich phase.

[0013] Optionally, the Si-rich phase further comprises Fe, and the atomic content of Fe in the Si-rich phase is less than the atomic content of each of Al, Si, Ce, La and Y in the Si-rich phase.

[0014] Optionally, the particle size of the spherical composite is 5 μm to 20 μm, the axial ratio of the spherical composite is less than 1.5, the particle size of the Al3Sc precipitate is 5 nm to 30 nm, and the axial ratio of the Al3Sc precipitate is less than 1.25.

[0015] Optionally, the mass ratio of Y to Fe in the aluminum alloy conductor is 0.5 to 1.5, wherein the mass ratio of the total Ce and La content to Si content (Ce+La) / Si in the aluminum alloy conductor is 2 to 10.

[0016] Optionally, the method for preparing the aluminum alloy wire includes: adding an Al-Ce-La-B seed alloy containing (Ce, La)B6 to the aluminum melt; and then adding an Al-Ce-La master alloy, an Al-Y master alloy, and an Al-Sc master alloy to the aluminum melt.

[0017] According to another embodiment of the present invention, a method for preparing a high-strength, high-conductivity, and heat-resistant aluminum alloy wire as described above is provided. The preparation method includes the following steps: adding an Al-Ce-La-B seed alloy containing (Ce, La)B6 to an aluminum melt and holding it at 730°C to 780°C for 20 to 40 minutes; adding an Al-Ce-La master alloy, an Al-Y master alloy, and an Al-Sc master alloy and holding it at 730°C to 780°C for 20 to 40 minutes; refining the aluminum melt at a temperature of 720°C to 750°C for 15 to 30 minutes, and holding it at 730°C to 780°C for 40 to 40 minutes; removing surface slag; and forming an aluminum alloy wire using the refined melt.

[0018] Optionally, based on the total mass of the aluminum alloy wire, the amount of Al-Ce-La-B seed alloy added is 0.5% to 3.5%, and the content of (Ce, La)B6 compound in the Al-Ce-La-B seed alloy is 1 wt% to 8 wt%, wherein the average particle size of (Ce, La)B6 compound is 0.5 μm to 5 μm.

[0019] Optionally, the step of forming aluminum alloy wires from the refined melt includes: casting the refined melt into aluminum alloy ingots; performing multi-stage homogenization treatment on the aluminum alloy ingots; hot extruding the homogenized ingots to form aluminum alloy rods; performing multiple cold drawing operations on the aluminum alloy rods to form aluminum alloy wires; and annealing the drawn aluminum alloy wires to form the aluminum alloy wires.

[0020] Optionally, the temperature of the cast aluminum molten metal is 690℃~720℃. The multi-stage homogenization treatment includes a first-stage homogenization treatment and a second-stage homogenization treatment. The temperature of the first-stage homogenization treatment is 600℃~640℃, the holding time is 8h~24h, and then it is water-cooled at room temperature. The temperature of the second-stage homogenization treatment is 350℃~450℃, the holding time is 4h~12h, and then it is air-cooled at room temperature. The temperature of the hot extrusion is 370℃~450℃. In the multi-pass cold drawing, the deformation amount per pass is 10%~25%, and the drawing speed is 2m / s~8m / s. The annealing temperature of the annealing treatment is 150℃~250℃, and the holding time is 2h~6h.

[0021] Beneficial effects Compared with the prior art, the present invention has the following beneficial effects: The aluminum alloy wire according to the present invention, by comprising a micron-sized spherical composite containing Fe-rich and Si-rich phases and a nano-sized Al3Sc precipitate phase, and reducing the total content of Ti+V+Cr to 0.005wt%, can achieve a synergistic improvement in high strength, high conductivity and excellent heat resistance.

[0022] According to the present invention, by adjusting the ratio of Y to Fe and the ratio of (Ce+La) to Si, the spheroidization of Fe- and Si-rich phases can be promoted.

[0023] Furthermore, according to the present invention, the following technical effects can be achieved by optimizing the composition and preparation method of aluminum alloy wires.

[0024] 1. ARB seed alloy design brings high-efficiency purification This invention achieves highly efficient removal of harmful impurities such as Ti, V, and Cr through the pre-formation of active (Ce, La)B6 compounds in an ARB seed alloy (Al-Ce-La-B). Compared with traditional Al-B alloys, the purification efficiency is increased from 50-60% to over 85%, and the total Ti+V+Cr content can be reduced from over 300 ppm in the raw material to below 45 ppm (i.e., below 0.0045%), resulting in an increase in conductivity of 1-2.5% IACS. Simultaneously, the substituted (Ce, La) enters the melt to participate in alloying, achieving dual utilization of rare earth elements.

[0025] 2. Spheroidization of Fe- and Si-rich phases improves electrical conductivity and elongation after fracture. This invention achieves simultaneous spheroidization control of Fe and Si impurity phases in industrial pure aluminum through the synergistic effect of Ce, La, and Y rare earth elements. Needle-like and plate-like Fe- and Si-rich phases are transformed into spherical composites (particle size 5–20 μm, axial ratio <1.5). These composites consist of Fe-rich and Si-rich phases: the Fe-rich phase mainly contains Al, Fe, and Y elements, and small amounts of Ce, La, and Si elements; the Si-rich phase mainly contains Al, Si, Ce, La, and Y elements, and a small amount of Fe element. This unique microstructure eliminates stress concentration, increasing the elongation after fracture from the conventional 2.5–5% to over 6%. Simultaneously, the content of dissolved Fe and Si in the matrix is ​​significantly reduced, and the conductivity reaches over 61.0% IACS, with a maximum of 61.8% IACS.

[0026] 3. High strength and excellent heat resistance During subsequent heat treatment, Sc element precipitates nanoscale L. 12 The dispersed Al3Sc reinforcing phases (particle size 5–30 nm) in the structure enable tensile strengths to reach over 185 MPa, with a maximum of 200 MPa. These Al3Sc phases exhibit extremely high thermal stability, retaining ≥90% of their tensile strength after 300℃×1h heat exposure, and achieving a heat resistance rating of 180℃.

[0027] 4. Optimized smelting process improves rare earth utilization. The smelting sequence of first adding ARB seed alloy for purification and then adding rare earth master alloy for alloying increases the utilization rate of rare earths by more than 30%, avoids the consumption of rare earth elements by impurities or the formation of coarse compounds, and ensures that Ce, La, Y, and Sc each perform their respective functions and fully exert their micro-alloying effects. At the same time, the smelting process is carried out in a normal atmospheric environment without the need for a protective atmosphere, reducing production costs and process complexity.

[0028] 5. Excellent overall performance Through the above innovations, the aluminum alloy conductor prepared by this invention achieves a synergistic improvement in high strength (≥185MPa), high conductivity (≥61.0%IACS), excellent heat resistance (strength retention rate ≥90% at 300℃×1h), and good plasticity (elongation after fracture ≥6%). ​​Its comprehensive performance is superior to existing similar products and can meet the stringent application requirements such as large-capacity power transmission and high-temperature conditions. Attached Figure Description

[0029] Figure 1 The SEM images and EDS results of (Ti, V, Cr)B2 at the bottom of the melt show the morphology and composition of (Ti, V, Cr)B2.

[0030] Figure 2The HAADF-TEM image and EDS results of the aluminum alloy wire prepared in Example 1 of this invention show the morphology and composition of the spherical Fe- and Si-rich composite phase.

[0031] Figure 3 The TEM bright-field, dark-field, and HRTEM images of the aluminum alloy wire prepared in Example 1 of this invention show the morphology and structure of the nanoscale Al3Sc precipitate phase.

[0032] Figure 4 This is a comparison chart of conductivity, tensile strength, elongation after fracture, and strength retention rate at 300℃ / 1h between Example 1 and Comparative Example 1 of the present invention.

[0033] Figure 5 The image shows a comparison of the Ti, V, and Cr elemental contents of Example 1 and Comparative Example 1 of this invention (ICP-MS analysis results), demonstrating the purification effect of active (Ce, La)B6 in the ARB seed alloy on harmful elements. Detailed Implementation

[0034] The following detailed embodiments are provided to aid the reader in gaining a comprehensive understanding of the products and methods described herein. However, after understanding this disclosure, various changes, modifications, and equivalents of the products and methods described herein will become clear. For example, the order of steps in the methods described herein is merely illustrative and is not limited to the order set forth herein, but may be changed as will become clear after understanding this disclosure, except for steps that must occur in a specific order. Furthermore, for clarity and conciseness, descriptions of features known in the art may be omitted.

[0035] The features described herein may be implemented in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein are provided only to illustrate some of the many feasible ways in which the products and methods described herein may be understood upon understanding the contents of this disclosure.

[0036] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains upon understanding this disclosure. Unless expressly defined herein, terms such as those defined in a general dictionary shall be interpreted as having the same meaning as in this disclosure and shall not be interpreted in an idealized or overly formalistic manner.

[0037] It should also be understood that the terms “comprising / including” or “having” as used throughout the specification indicate the presence of the said ingredient, step, or operation, but do not exclude the presence or addition of one or more other ingredients. Therefore, unless explicitly stated to the contrary, the words “comprising,” “including,” or “having” will be understood to imply the inclusion of the said ingredient, step, or operation but do not exclude any other ingredient, step, or operation.

[0038] High-strength, high-conductivity, heat-resistant rare-earth aluminum alloy wires The high-strength, high-conductivity, and heat-resistant aluminum alloy wire according to an embodiment of the present invention comprises the following components by mass percentage: Ce 0.05–0.25%, La 0.03–0.20%, Sc 0.10–0.35%, Y 0.08–0.30%, Fe 0.10–0.40%, Si 0.02–0.20%, Ti+V+Cr < 0.005%, other impurities ≤ 0.01% individually, ≤ 0.05% in total, with the balance being Al. According to an embodiment of the present invention, the aluminum alloy wire may include micron-sized spherical composites and nano-sized Al3Sc precipitates. The spherical composites may include Fe-rich and Si-rich phases. The Fe-rich phase may contain Al, Fe, and Y, and the Si-rich phase may contain Al, Si, Ce, La, and Y.

[0039] Figure 2 The HAADF-TEM image and EDS results of the aluminum alloy wire prepared in Example 1 of this invention show the morphology and composition of the spherical Fe- and Si-rich composite particles. Figure 2 As shown in the HAADF (High Angle Circular Dark Field Image), the aluminum alloy conductor may include a micron-sized spherical composite, which may include a Fe-rich phase and a Si-rich phase. The Fe-rich phase may contain Al, Fe, and Y, and the Si-rich phase may contain Al, Si, Ce, La, and Y.

[0040] According to embodiments of the present invention, such as Figure 2 As shown, the Fe-rich phase may also contain Ce, La, and Si, and the atomic content of each of Ce, La, and Si in the Fe-rich phase may be less than the atomic content of each of Al, Fe, and Y in the Fe-rich phase. That is to say, the Fe-rich phase may mainly contain Al, Fe, and Y elements, and may also contain small amounts of Ce, La, and Si elements.

[0041] According to embodiments of the present invention, such as Figure 2 As shown, the Si-rich phase may also contain Fe, and the atomic content of Fe in the Si-rich phase is less than that of each of Al, Si, Ce, La, and Y in the Si-rich phase. That is to say, the Si-rich phase may mainly contain Al, Si, Ce, La, and Y, and may also contain a small amount of Fe.

[0042] According to embodiments of the present invention, such as Figure 2 As shown, the particle size of the spherical composite can be 5μm to 20μm, and the axial ratio (the ratio of the major axis to the minor axis) of the spherical composite can be less than 1.5.

[0043] According to this invention, through the synergistic effect of Ce, La, and Y multi-element rare earth elements, the simultaneous spheroidization control of Fe and Si impurity phases in industrial pure aluminum is achieved, transforming needle-like and plate-like Fe and Si-rich phases into spherical composites. This unique microstructure eliminates stress concentration, increasing the elongation after fracture from the conventional 2.5%–5% to over 6%. Simultaneously, the content of Fe and Si dissolved in the matrix is ​​significantly reduced, resulting in an electrical conductivity exceeding 61.0% IACS, with a maximum of 61.8% IACS.

[0044] Figure 3 TEM bright-field, dark-field, and HRTEM images of the aluminum alloy wire prepared in Example 1 of this invention show the morphology and structure of the nanoscale Al3Sc precipitates. Figure 3 As shown, the aluminum alloy wire may also contain nanoscale Al3Sc precipitates. According to embodiments of the present invention, the particle size of the Al3Sc precipitates can be 5 nm to 30 nm, and the axial ratio of the Al3Sc precipitates can be less than 1.25.

[0045] According to the present invention, Sc element is in nanoscale L 12 The Al3Sc dispersed reinforcing phase (particle size 5nm~30nm) precipitates, resulting in a tensile strength of over 185MPa, with a maximum of 200MPa. These Al3Sc phases exhibit extremely high thermal stability, retaining ≥90% of their tensile strength after 300℃×1h heat exposure, and achieving a heat resistance rating of 180℃.

[0046] Furthermore, according to embodiments of the present invention, the mass ratio of Y to Fe in the aluminum alloy conductor, Y / Fe, can be 0.5 to 1.5. When the mass ratio of Y to Fe in the aluminum alloy conductor, Y / Fe, is 0.5 to 1.5, Y can fully participate in the formation of the Fe-rich phase and synergistically promote the spheroidization of the Fe-rich and Si-rich phases with Ce and La.

[0047] Furthermore, according to embodiments of the present invention, the mass ratio of the total Ce and La content to the Si content in the aluminum alloy conductor (Ce+La) / Si can be 2 to 10. When the mass ratio of the total Ce and La content to the Si content in the aluminum alloy conductor (Ce+La) / Si satisfies 2 to 10, Ce and La can fully combine with Si to form a Si-rich phase, ensuring that Si precipitates from the solid solution state and participates in the formation of the spherical composite.

[0048] According to an embodiment of the present invention, a method for preparing aluminum alloy wires may include: adding an Al-Ce-La-B seed alloy (also known as an ARB seed alloy) containing (Ce,La)B6 to an aluminum melt; and then adding an Al-Ce-La master alloy, an Al-Y master alloy, and an Al-Sc master alloy to the aluminum melt.

[0049] According to the present invention, the Al-Ce-La-B seed alloy has a unique structure and function, namely, the seed alloy contains an active (Ce, La)B6 compound, which has high reactivity in the melt and can preferentially undergo the following substitution reaction with harmful impurities such as Ti, V, and Cr in the melt: (Ce, La)B6+ (Ti, V, Cr) → (Ti, V, Cr)B2+ (Ce, La) The (Ti, V, Cr)B2 compound generated by the above reaction has a high density (approximately 4.5 g / cm³). 3 During the settling process, the rare earth elements rapidly settle to the bottom of the melt (the bottom is not poured during subsequent casting), facilitating the efficient removal of these elements that severely degrade conductivity, resulting in a final product with a total Ti+V+Cr mass percentage of less than 0.005%. Simultaneously, the displaced Ce and La enter the melt and participate in subsequent Fe- and Si-rich phase formation reactions, achieving a dual utilization of rare earth elements. Furthermore, the addition of the ARB seed alloy provides the melt with numerous heterogeneous nucleation sites, refining the as-cast grains and improving the uniformity of the ingot microstructure.

[0050] Preparation method of high-strength, high-conductivity, heat-resistant rare-earth aluminum alloy wire The preparation method of high-strength, high-conductivity, and heat-resistant aluminum alloy wire according to an embodiment of the present invention may include the following steps: adding an Al-Ce-La-B seed alloy containing (Ce, La)B6 to an aluminum melt and holding it at 730℃~780℃ for 20min~40min; adding an Al-Ce-La master alloy, an Al-Y master alloy, and an Al-Sc master alloy and holding it at 730℃~780℃ for 20min~40min; refining the aluminum melt at a refining temperature of 720℃~750℃ for 15min~30min, and holding it at 730℃~780℃ for 40min~60min after refining, and removing surface slag; and forming an aluminum alloy wire using the refined melt.

[0051] First, prepare the raw materials. Weigh out industrial pure aluminum (containing Fe and Si impurity elements), ARB seed alloy (Al-Ce-La-B seed alloy), Al-Ce-La master alloy, Al-Y master alloy, and Al-Sc master alloy according to the designed proportions.

[0052] Industrial pure aluminum can be melted, and then an Al-Ce-La-B seed alloy (ARB seed alloy) containing (Ce, La)B6 can be added to the aluminum melt. The mixture is then kept at 730℃~780℃ for 20min~40min.

[0053] According to embodiments of the present invention, the amount of Al-Ce-La-B seed alloy added can be 0.5% to 3.5% based on the total mass of the aluminum alloy wire. According to embodiments of the present invention, the content of (Ce, La)B6 compound in the Al-Ce-La-B seed alloy can be 1 wt% to 8 wt%. The amount of Al-Ce-La-B seed alloy added can be adjusted according to the content of (Ce, La)B6 compound in the Al-Ce-La-B seed alloy. According to embodiments of the present invention, the average particle size of the (Ce, La)B6 compound is 0.5 μm to 5 μm.

[0054] According to the present invention, by adding an ARB seed alloy to the aluminum melt, the active (Ce,La)B6 in the ARB seed alloy can fully react with the Ti, V, and Cr impurity elements in the melt to generate a (Ti, V, Cr)B2 compound (the reaction formula is: (Ce,La)B6 + (Ti, V, Cr) → (Ti, V, Cr)B2 + (Ce, La)). As mentioned above, the (Ti, V, Cr)B2 compound has a high density and will quickly settle to the bottom of the melt during the settling process. Figure 1 The SEM images and EDS results of (Ti, V, Cr)B2 at the bottom of the melt show the morphology and composition of (Ti, V, Cr)B2.

[0055] After the above reactions have been fully carried out, Al-Ce-La master alloys, Al-Y master alloys, and Al-Sc master alloys can be added to the melt and held at 730℃~780℃ for 20min~40min. In this step, Ce, La, and Y elements are fully alloyed with Al, Fe, and Si in the melt to form spherical composites including Fe-rich and Si-rich phases. Sc element is used to precipitate the Al3Sc dispersion strengthening phase during subsequent heat treatment. Since the (Ti, V, Cr)B2 compound settles to the bottom of the melt, the rare earth elements are avoided from being consumed by impurities or forming coarse compounds, ensuring that Ce, La, Y, and Sc each perform their respective functions and fully exert their microalloying effects.

[0056] According to the present invention, the smelting process of the above-mentioned raw materials can be carried out in a normal atmospheric environment without the need for a protective atmosphere.

[0057] Next, the aluminum melt is refined at a temperature of 720℃~750℃ for 15min~30min. After refining, it is allowed to stand for 40min~60min to allow the (Ti, V, Cr)B2 compound to settle completely and remove surface slag. As an example, refining can be performed by adding a refining agent to the aluminum melt, by introducing argon gas into the melt, or by using a combination of refining agent and argon gas.

[0058] Finally, the refined melt is used to form aluminum alloy wires. The method for forming aluminum alloy wires from the refined melt is described below.

[0059] First, the refined melt can be cast into aluminum alloy ingots at a temperature of 690℃~720℃. The (Ti, V, Cr)B2 compound settles to the bottom of the melt. This part can be omitted during casting to remove the (Ti, V, Cr)B2 compound.

[0060] Next, the aluminum alloy ingot undergoes a multi-stage homogenization treatment. This multi-stage homogenization treatment includes a first-stage homogenization treatment and a second-stage homogenization treatment. The first-stage homogenization treatment can be carried out at a temperature of 600℃–640℃ for 8–24 hours, followed by water cooling at room temperature. The second-stage homogenization treatment can be carried out at a temperature of 350℃–450℃ for 4–12 hours, followed by air cooling at room temperature. Water cooling in the first-stage homogenization annealing aims to retain the high-temperature solution state and promote the precipitation of nano-phases during the subsequent second-stage homogenization process; air cooling in the second-stage homogenization annealing is beneficial for controlling the size and distribution of the precipitated phases.

[0061] Next, the homogenized ingot is hot-extruded to form an aluminum alloy rod. For example, the homogenized ingot can be heated to 370°C to 450°C and then hot-extruded.

[0062] Next, the aluminum alloy rod is subjected to multiple cold drawing passes to form aluminum alloy wire. The deformation amount per pass can be 10% to 25%, and the drawing speed can be 2m / s to 8m / s.

[0063] Finally, the drawn aluminum alloy wire is annealed to form an aluminum alloy conductor. The annealing temperature can be 150℃~250℃, and the holding time can be 2h~6h.

[0064] According to the present invention, the (Ti, V, Cr)B2 compound formed by the reaction of (Ce, La)B6 with Ti, V, and Cr impurities in the melt has a high density (approximately 4.5 g / cm³). 3During the settling process, the rare earth elements (ARB) rapidly settle, efficiently removing these elements that severely degrade conductivity, resulting in a final product with a total Ti+V+Cr mass percentage of less than 0.005%. Simultaneously, the substituted Ce and La enter the melt and participate in subsequent Fe- and Si-rich phase formation reactions, achieving dual utilization of rare earth elements. Furthermore, the addition of ARB seed alloys provides the melt with numerous heterogeneous nucleation sites, refining the as-cast grains and improving the uniformity of the ingot microstructure.

[0065] This invention achieves highly efficient removal of harmful impurities such as Ti, V, and Cr through the pre-formation of active (Ce, La)B6 compounds in an ARB seed alloy (Al-Ce-La-B). Compared with traditional Al-B alloys, the purification efficiency is increased from 50%–60% to over 85%, and the total mass of Ti+V+Cr can be reduced from over 300 ppm in the raw materials to below 45 ppm (i.e., below 0.0045%), resulting in an increase in conductivity of 1–2.5% IACS. Simultaneously, the substituted Ce and La enter the melt to participate in alloying, achieving dual utilization of rare earth elements.

[0066] This invention achieves simultaneous spheroidization control of Fe and Si impurity phases in industrial pure aluminum through the synergistic effect of Ce, La, and Y rare earth elements. Needle-like and plate-like Fe- and Si-rich phases are transformed into spherical composites (particle size 5–20 μm, axial ratio <1.5). These composites consist of Fe-rich and Si-rich phases: the Fe-rich phase mainly contains Al, Fe, and Y elements, and small amounts of Ce, La, and Si elements; the Si-rich phase mainly contains Al, Si, Ce, La, and Y elements, and a small amount of Fe element. This unique microstructure eliminates stress concentration, increasing the elongation after fracture from the conventional 2.5–5% to over 6%. Simultaneously, the content of dissolved Fe and Si in the matrix is ​​significantly reduced, and the conductivity reaches over 61.0% IACS, with a maximum of 61.8% IACS.

[0067] According to the present invention, Sc element precipitates nanoscale L during subsequent heat treatment. 12 The dispersed Al3Sc reinforcing phases (particle size 5–30 nm) in the structure enable tensile strengths to reach over 185 MPa, with a maximum of 200 MPa. These Al3Sc phases exhibit extremely high thermal stability, retaining ≥90% of their tensile strength after 300℃×1h heat exposure, and achieving a heat resistance rating of 180℃.

[0068] According to the present invention, the smelting sequence of first adding ARB seed alloy for purification and then adding rare earth intermediate alloy for alloying increases the utilization rate of rare earth by more than 30%, avoids the consumption of rare earth elements by impurities or the formation of coarse compounds, and ensures that Ce, La, Y and Sc each perform their respective functions and give full play to their micro-alloying effects.

[0069] In addition, according to the present invention, the smelting process is carried out in a conventional atmospheric environment without the need for a protective atmosphere, which reduces production costs and process complexity.

[0070] Example 1 The aluminum alloy conductor of Example 1 has the following composition by mass percentage: Ce 0.16%, La 0.12%, Sc 0.22%, Y 0.18%, Fe 0.15%, Si 0.05%, Ti+V+Cr total 0.002%, other impurities ≤0.01% individually and ≤0.05% in total, with the balance being Al. The Y / Fe ratio is 1.2, and the (Ce+La) / Si ratio is 5.6. The preparation method is as follows: (1) Raw material preparation: Weigh industrial pure aluminum (purity 99.7%), 3.0wt% of ARB seed alloy (Al-3%(Ce, La)B6, of which (Ce, La)B6 average particle size 2μm), Al-15(Ce, La) master alloy, Al-20Y master alloy and Al-2Sc master alloy according to the proportion.

[0071] (2) Melting and alloying: First, industrial pure aluminum is melted at 750℃, ARB seed alloy is added, and the mixture is kept at the temperature for 30 minutes to allow the active (Ce, La)B6 to fully react with the Ti, V, and Cr impurities in the melt to generate (Ti, V, Cr)B2 compound; then Al-15(Ce, La) master alloy, Al-20Y master alloy, and Al-2Sc master alloy are added in sequence, stirred evenly, and kept at the temperature for another 30 minutes; the melting process is carried out under normal atmospheric conditions.

[0072] (3) Refining and settling: Add 0.2% of sodium-free refining agent by total mass of melt to the melt, and simultaneously introduce argon gas (flow rate 1.0 L / min) for compound refining. The refining temperature is 740℃ and the refining time is 15 min. After refining, let it stand for 50 min to allow the (Ti, V,Cr)B2 compound to settle fully and remove the surface scum. (4) Casting: Cast into ingots at 710℃; (5) Multi-stage homogenization annealing: First stage: 630℃ for 10h, water cooling at room temperature; Second stage: 350℃ for 6h, air cooling at room temperature; (6) Hot extrusion: The ingot is heated to 400℃ and extruded into a Φ9.5mm rod; (7) Multi-pass drawing: Six drawing passes are performed, with a deformation of 15-20% per pass and a drawing speed of 5m / s, to finally obtain Φ 3mm wire; (8) Annealing treatment: heat at 230℃ for 4 hours to obtain aluminum alloy wire.

[0073] Example 2 Example 2 is basically the same as Example 1, except that the composition of the aluminum alloy wire and the amount of ARB seed alloy added to the raw materials are adjusted. The composition of the aluminum alloy wire is adjusted as follows: Ce 0.10%, La 0.08%, Sc 0.15%, Y 0.12%, Fe 0.20%, Si 0.08%, Ti+V+Cr total 0.003%, Y / Fe=0.6, (Ce+La) / Si=2.25. The amount of ARB seed alloy added is adjusted to 2.0wt%.

[0074] Example 3 This embodiment is basically the same as Embodiment 1, except that the composition of the aluminum alloy conductor and the amount of ARB seed alloy added to the raw materials are adjusted. The composition of the aluminum alloy conductor is adjusted as follows: Ce 0.22%, La 0.18%, Sc 0.28%, Y 0.25%, Fe 0.35%, Si 0.15%, Ti+V+Cr total 0.0025%, Y / Fe=0.71, (Ce+La) / Si=2.67. The amount of ARB seed alloy added is adjusted to 2.5wt%.

[0075] Comparative Example 1 Commercially available 1070 aluminum alloy wire is used. The composition is: Fe 0.15%, Si 0.05%, with the balance being Al and impurities. No rare earth elements or ARB seed alloys are added.

[0076] Comparative Example 2 It is basically the same as Example 1, except that Sc element is not added (i.e., Al-2Sc master alloy is not added), and the other components are the same.

[0077] Comparative Example 3 It is basically the same as Example 1, except that Y element is not added (i.e., Al-20Y master alloy is not added), and the other components are the same.

[0078] Comparative Example 4 It is basically the same as Example 1, except that Ce and La elements are not added (i.e., Al-15(Ce, La) master alloy is not added), only Sc and Y are added, and the other components are the same.

[0079] Comparative Example 5 The composition is basically the same as in Example 1, except that no ARB seed alloy is added, while the other components are the same (Ce and La are added only through ordinary Al-Ce-La intermediate alloy).

[0080] Performance testing The performance of the aluminum alloy wires prepared in the above embodiments and comparative examples was tested using the following methods: Conductivity: The resistivity was measured using a DC double-arm bridge and then the conductivity was calculated, in accordance with GB / T 351-2019 standard.

[0081] Tensile strength (room temperature): Measured using an electronic universal testing machine, in accordance with GB / T 228.1-2021 standard; Elongation after fracture: in accordance with GB / T 228.1-2021 standard; Strength after 300℃×1h: The sample was kept at 300℃ for 1h, then air-cooled to room temperature before the tensile strength was tested. High-temperature strength retention rate: The sample was kept at 300℃ for 1 hour, then air-cooled to room temperature, and the tensile strength was tested. The ratio of the tensile strength to the original strength was calculated. Trace impurity element content: The contents of Ti, V, and Cr were analyzed by inductively coupled plasma mass spectrometry (ICP-MS); Microscopic observation: The morphology and distribution of the second phase were observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

[0082] Table 1 shows the conductivity, tensile strength, elongation after fracture, composite morphology, and total mass (Ti+V+Cr) of each embodiment and comparative example.

[0083] Table 1

[0084] Table 2 shows the tensile strength, strength after 300°C for 1 hour, and high-temperature strength retention rate of each embodiment and comparative example.

[0085] Table 2

[0086] As shown in Table 1, the aluminum alloy wires prepared in Examples 1-3 of this invention exhibit excellent comprehensive performance in terms of conductivity, tensile strength, and elongation after fracture. The conductivity reaches over 61.1% IACS, the tensile strength is over 185 MPa, and the elongation after fracture is over 6.0%. In particular, Example 2 achieves a conductivity of 61.8% IACS, a tensile strength of 186 MPa, and an elongation after fracture of 8.0%, realizing a synergistic improvement in high strength, high conductivity, and good plasticity.

[0087] The morphological characteristics of the composites show that the composites in Examples 1-3 of this invention are all spherical, while the Fe- and Si-rich phases in Comparative Example 1 (without rare earth elements) exhibit a plate-like morphology. The total Ti+V+Cr content in Example 1 was reduced to 38 ppm (0.0038 wt%), far lower than the 320 ppm of the raw material, confirming the highly efficient purification effect of the ARB seed alloy.

[0088] Comparative Example 2 (without Sc) showed a significant decrease in strength, indicating that Sc's nano-reinforcing effect is indispensable. Comparative Example 3 (without Y) exhibited reduced conductivity and elongation after fracture, and contained lamellar Fe- and Si-rich phases, suggesting the crucial role of Y in the formation of the spherical composite. Comparative Example 4 (without Ce or La) showed the lowest conductivity and poorest elongation after fracture, proving that Ce and La play a key role in the formation of the spherical composite. Comparative Example 5 (without ARB seed alloy) showed poor purification effect, with a total Ti+V+Cr content of 258 ppm.

[0089] As shown in Table 2, Examples 1-3 of the present invention exhibit excellent heat resistance, with strength retention rates exceeding 90% after heat exposure at 300℃ for 1 hour. Comparative Example 1 (without rare earth elements) showed the worst heat resistance, with a retention rate of only 62.5%. Comparative Example 2 (without Sc elements) showed a significant decrease in heat resistance, with a retention rate of 64.0%, demonstrating the crucial role of Al3Sc in improving relative heat resistance. Furthermore, Comparative Example 5, without the addition of ARB seed alloy, showed a significant decrease in heat resistance, with a retention rate of 65.0%, indicating that using ARB seed alloy to purify impurity elements (Ti, V, Cr) has a significant effect on improving heat resistance.

[0090] Figure 4 This is a comparison chart of conductivity, tensile strength, elongation after fracture, and strength retention at 300℃ / 1h between Example 1 and Comparative Example 1 of the present invention. Figure 4 As can be seen, compared with Comparative Example 1, Example 1 has significantly higher performance than Comparative Example 1 in all four dimensions: conductivity, tensile strength, elongation after fracture, and strength retention at 300℃ / 1h.

[0091] Figure 5 The image shows a comparison of the Ti, V, and Cr elemental contents of Example 1 and Comparative Example 1 (ICP-MS analysis results), demonstrating the purification effect of the active (Ce, La)B6 in the ARB seed alloy on harmful elements. Figure 5 It can be seen that the content of each impurity element, Ti, V, and Cr, in Example 1 is lower than that in Comparative Example 1.

[0092] The above results demonstrate that this invention, through innovative design of ARB seed alloy, synergistic effect of multiple rare earth elements, optimized melting sequence and multi-stage heat treatment process, successfully achieved spheroidization control of Fe- and Si-rich phases, efficient removal of harmful impurities and dispersion precipitation of nano-reinforcing phases, resulting in aluminum alloy wires with synergistic improvement in high strength, high conductivity and excellent heat resistance.

[0093] Industrial applicability The rare-earth aluminum alloy wire provided by this invention has high strength, high conductivity, and excellent heat resistance, and can be widely used in the following fields: Overhead transmission conductors: suitable for large-capacity transmission lines, capacity expansion and renovation lines, long-span lines, etc., which can increase transmission capacity and reduce line loss; Electrical equipment connection wires: transformers, motors, switchgear, etc., can improve equipment efficiency and reliability; Automotive wiring harnesses: High-voltage wiring harnesses for new energy vehicles can reduce weight and improve conductivity; Rail transit: Contact wires can improve conductivity and wear resistance; Aerospace: Lightweight conductive components can reduce weight and improve reliability.

[0094] This product has broad market application prospects and significant economic and social benefits.

[0095] While this disclosure has been described in conjunction with what is now considered to be actual embodiments, it should be understood that the invention is not limited to the disclosed embodiments. Rather, it is intended to cover various variations and equivalents that are included within the spirit and scope of the appended claims.

Claims

1. A high-strength, high-conductivity, heat-resistant aluminum alloy conductor, characterized in that, The aluminum alloy conductor comprises the following components by mass percentage: Ce 0.05–0.25%, La 0.03–0.20%, Sc 0.10–0.35%, Y 0.08–0.30%, Fe 0.10–0.40%, Si 0.02–0.20%, Ti+V+Cr < 0.005%, other impurities ≤ 0.01% individually, total ≤ 0.05%, with the balance being Al. The aluminum alloy wire comprises a micron-sized spherical composite and a nano-sized Al3Sc precipitate phase. The spherical composite comprises a Fe-rich phase and a Si-rich phase. The Fe-rich phase contains Al, Fe, and Y, and the Si-rich phase contains Al, Si, Ce, La, and Y.

2. The high-strength, high-conductivity, heat-resistant aluminum alloy wire according to claim 1, characterized in that, The Fe-rich phase further comprises Ce, La, and Si, and the atomic content of each of Ce, La, and Si in the Fe-rich phase is less than the atomic content of each of Al, Fe, and Y in the Fe-rich phase.

3. The high-strength, high-conductivity, heat-resistant aluminum alloy wire according to claim 1, characterized in that, The Si-rich phase also contains Fe, and the atomic content of Fe in the Si-rich phase is less than the atomic content of each of Al, Si, Ce, La and Y in the Si-rich phase.

4. The high-strength, high-conductivity, heat-resistant aluminum alloy wire according to claim 1, characterized in that, The spherical composite has a particle size of 5 μm to 20 μm and an axial ratio of less than 1.

5. The Al3Sc precipitate has a particle size of 5 nm to 30 nm and an axial ratio of less than 1.

25.

5. The high-strength, high-conductivity, heat-resistant aluminum alloy wire according to claim 1, characterized in that, The mass ratio of Y to Fe in the aluminum alloy conductor is 0.5 to 1.

5. The mass ratio of the total Ce and La content to the Si content in the aluminum alloy wire (Ce+La) / Si is 2 to 10.

6. The high-strength, high-conductivity, heat-resistant aluminum alloy wire according to claim 1, characterized in that, The method for preparing the aluminum alloy wire includes: adding an Al-Ce-La-B seed alloy containing (Ce, La)B6 to an aluminum melt; and then adding an Al-Ce-La master alloy, an Al-Y master alloy, and an Al-Sc master alloy to the aluminum melt.

7. A method for preparing a high-strength, high-conductivity, heat-resistant aluminum alloy wire as described in any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: Add an Al-Ce-La-B seed alloy containing (Ce, La)B6 to the aluminum melt and hold it at 730℃~780℃ for 20min~40min. Add Al-Ce-La master alloy, Al-Y master alloy and Al-Sc master alloy, and hold at 730℃~780℃ for 20min~40min; The aluminum melt is refined at a temperature of 720℃~750℃ for 15min~30min. After refining, it is allowed to stand for 40min~60min and the surface slag is removed. Aluminum alloy wires are formed from the refined melt.

8. The preparation method according to claim 7, characterized in that, Based on the total mass of the aluminum alloy wire, the addition amount of the Al-Ce-La-B seed alloy is 0.5% to 3.5%, and the content of (Ce, La)B6 compound in the Al-Ce-La-B seed alloy is 1 wt% to 8 wt%. The average particle size of the (Ce, La)B6 compound is 0.5 μm to 5 μm.

9. The preparation method according to claim 7, characterized in that, The steps involved in forming aluminum alloy wires from refined melt include: The refined melt is cast into aluminum alloy ingots; The aluminum alloy ingot is subjected to multi-stage homogenization treatment; The homogenized ingot is hot-extruded to form an aluminum alloy rod. Aluminum alloy rods are cold-drawn in multiple passes to form aluminum alloy wires. The drawn aluminum alloy wire is annealed to form the aluminum alloy conductor.

10. The preparation method according to claim 9, characterized in that, The temperature of the cast aluminum molten metal is 690℃~720℃. The multi-stage homogenization process includes a first-stage homogenization process and a second-stage homogenization process. The first-stage homogenization process is carried out at a temperature of 600℃ to 640℃ for 8 hours to 24 hours, followed by water cooling at room temperature. The second-stage homogenization process is carried out at a temperature of 350℃ to 450℃ for 4 hours to 12 hours, followed by air cooling at room temperature. The hot extrusion temperature is 370℃~450℃. In the multi-pass cold drawing process, the deformation per pass is 10%–25%, and the drawing speed is 2 m / s–8 m / s. The annealing temperature for the annealing treatment is 150℃~250℃, and the holding time is 2h~6h.

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