A high-conductivity heat-resistant aluminum alloy based on yttrium-boron synergistic effect and a preparation process thereof

Abstract

This invention discloses a high-conductivity and heat-resistant aluminum alloy based on the synergistic effect of yttrium and boron and its preparation process, belonging to the technical field of overhead transmission line materials. The chemical composition (wt.%) of the alloy is as follows: yttrium (Y) 0.055%~0.155%, boron (B) 0.0022%~0.0110%, zirconium (Zr) 0.010%~0.030%, scandium (Sc) 0.005%~0.015%, silicon (Si) ≤0.066%, iron (Fe) ≤0.088%, copper (Cu) ≤0.00808%, magnesium (Mg) ≤0.00808%, manganese (Mn) ≤0.00808%, titanium (Ti) 0.0088%~0.0255%, with the remainder being aluminum (Al) and other unavoidable trace impurity elements, the total amount of impurity elements ≤0.044%. Based on Al-Y-B synergistic microalloying, this invention combines the auxiliary strengthening effects of Zr and Sc elements to further refine the alloy grains, suppress the precipitation and growth of impurity phases, and cause the alloy microstructure to evolve from fine strip-shaped grains to a uniform and fine equiaxed grain structure, promoting the uniform distribution of grain boundaries, thereby simultaneously improving the electrical conductivity, heat resistance and mechanical properties of the alloy material.

Description

Technical Field

[0001] This invention relates to the field of overhead power transmission conductor materials technology, and in particular to a high-conductivity and heat-resistant aluminum alloy based on the yttrium-boron synergistic effect and its preparation process. Background Technology

[0002] Aluminum alloys, with their advantages of low density, excellent thermal and electrical conductivity, and adjustable mechanical properties, are one of the core materials in the field of power transmission and are widely used in high-voltage transmission lines, power distribution equipment, and other power transmission-related scenarios. As power transmission becomes increasingly high-voltage and long-distance, higher requirements are being placed on the electrical conductivity, thermal stability, and overall mechanical properties of aluminum alloy materials.

[0003] In the research and application of aluminum alloy materials for power transmission, microalloying modification and preparation process optimization are the core means to improve performance and adapt to the needs of power transmission scenarios, and are also the current research focus and development direction in this field. At present, there are two major pain points in the industry: First, the addition of a single microalloying element is difficult to achieve the simultaneous optimal combination of high conductivity, high heat resistance, and high mechanical properties required for power transmission, while the ratio design and process adaptation of multi-element synergistic modification still have room for optimization, and some multi-element addition schemes have problems of unbalanced performance and excessively high cost; Second, traditional aging processes mostly adopt single aging schemes, which have long aging cycles, high production costs, and difficulty in fully leveraging the synergistic strengthening effect of multi-element materials, thus failing to meet the needs of large-scale production and long-term stable service of power transmission materials.

[0004] A search revealed that Chinese patent application CN114672698A discloses an aluminum alloy system containing yttrium, boron, zirconium, and scandium. However, it employs a high-content rare earth addition scheme with 0.3-0.5% yttrium and 0.2-0.35% scandium, which has drawbacks such as high raw material costs, easy formation of coarse intermetallic compounds that reduce conductivity, and failure to form a synergistic strengthening mechanism between yttrium and boron. Chinese patent application CN115896469B discloses a deep purification process for electrical aluminum alloy melts, which uses a combination of inert gas and multifunctional refining agent for two-stage refining, a dual-rotor degassing box, and a two-stage filtration to achieve high cleanliness. However, this process is only a physicochemical purification method and does not form a synergistic purification mechanism with specific microalloying elements, thus failing to achieve simultaneous improvement in melt ultra-purity and long-term service stability.

[0005] Therefore, there is an urgent need to develop a high-strength aluminum alloy material suitable for pre-twisted wires to overcome the defects mentioned above. Summary of the Invention

[0006] To overcome the above-mentioned technical defects, the present invention provides a high-conductivity and heat-resistant aluminum alloy based on the yttrium-boron synergistic effect and its preparation process, so as to solve the problems involved in the background art.

[0007] On one hand, the present invention provides a high-conductivity and heat-resistant aluminum alloy based on the synergistic effect of yttrium and boron, comprising, by weight percentage: 0.055%~0.155% yttrium, 0.0022%~0.0110% boron, 0.010%~0.030% zirconium, 0.005%~0.015% scandium, ≤0.066% silicon, ≤0.088% iron, ≤0.00808% copper, ≤0.00808% magnesium, ≤0.00808% manganese, 0.0088%~0.0255% titanium, with the remainder being aluminum and other unavoidable trace impurity elements, and the total amount of the impurity elements being ≤0.044%.

[0008] Preferably or optionally, the unavoidable trace impurity elements include chromium, nickel, and zinc, wherein chromium ≤ 0.01%, nickel ≤ 0.01%, and zinc ≤ 0.024%.

[0009] Preferably or optionally, the mass ratio of yttrium to boron is (10-30):1, more preferably 16:1.

[0010] Preferably or optionally, the mass ratio of yttrium to scandium is (3.5-30):1, more preferably 8:1.

[0011] Preferably or optionally, the total content of yttrium and scandium is 0.06%-0.17%, and the yttrium content is 3.5-10 times the scandium content.

[0012] On the other hand, the present invention also provides a preparation process for a high-conductivity and heat-resistant aluminum alloy based on the yttrium-boron synergistic effect, comprising: S1 Smelting: Aluminum ingots and intermediate alloy ingots are smelted according to the chemical proportions described in any one of claims 1 to 3. The purity of the aluminum ingots is ≥99.70%, the furnace temperature is controlled at 750~760℃, and magnetic force is used to drive automatic stirring. Raw materials are added from high to low melting temperature. After stirring evenly, the mixture is kept warm until all elements are fully dissolved. S2 Refining: Transfer the smelted material to a holding furnace and refine it at 720℃~740℃ for 30~45 minutes. The ratio of refining agent to aluminum alloy solution is 2.5:1000. Then, hold it at 730℃~760℃ for 25 minutes, stirring continuously during the refining process. S3 Purification and Grain Optimization: The molten aluminum alloy is transferred to a dynamic purification system, which uses a multi-layer foam ceramic filter plate with a pore size of 40ppi~50ppi and a filtration temperature of 740℃. A total of 0.25% titanium boron rare earth refining agent is added to optimize the grain size. At the same time, high-purity nitrogen gas with a purity of ≥99.99% is used at a flow rate of 1.2~1.8 L / min and a rotor speed of 300~500 r / min. The high-purity nitrogen gas and the rotor work together to remove gas. S4 Continuous casting: The alloy liquid with optimized grains is prepared into aluminum alloy ingot blanks by horizontal continuous casting, and the casting temperature is controlled to be stable. S5 Continuous hot rolling: The aluminum alloy ingot blank is heated at 505℃~535℃ and then continuously hot rolled to obtain the alloy rod. The temperature of hot rolling is ≥360℃. S6 Online Quenching: The alloy rod is first immersed in water cooling, then air cooling, with a quenching temperature of 28℃~30℃, a quenching pressure of 500±50kPa, and cooled to 65℃~110℃. S7 Tight winding: The quenched alloy rod is wound up at ≤100℃, and the winding speed and tension are controlled to avoid deformation and scratches; S8 Self-Aging: The alloy rod after winding is placed at room temperature for self-aging, and the aging time is not less than 168 hours; S9 Short-time gradient aging: The alloy rod after self-aging is placed in an aging furnace, first held at 150~170℃ for 2~4h, then heated to 190~210℃ and held for 1~3h, and finally cooled to 120~140℃ and held for 2~4h. The heating rate is controlled at 5~10℃ / h and the cooling rate at 3~8℃ / h throughout the process. S10 Tensile Deformation: The alloy rod is drawn in multiple passes using an ultra-precision stretching die. The die contact surface is coated with ultra-fine particles to control the stretching speed and the amount of deformation per pass. S11 Controlled aging: The stretched alloy rod is placed in an aging furnace and held at 200℃~230℃ for 5~15 hours.

[0013] Preferably or optionally, the intermediate alloy ingot in step S1 comprises 10% aluminum-iron intermediate alloy, 10% aluminum-silicon alloy, 50% aluminum-copper alloy, 10% aluminum-titanium alloy additive, 8% aluminum-boron alloy, 10% aluminum-yttrium alloy, 10% aluminum-scandium alloy and pure magnesium, wherein the magnesium alloy is added after the iron, silicon and copper alloys, and the boron and titanium-based alloys are added last. During the smelting process in step S1, the oxygen partial pressure inside the furnace is controlled to be 10. -9 -10 -7 atm.

[0014] Preferably or optionally, the refining agent in step S2 is a sodium salt or rare earth refining agent.

[0015] Preferably or optionally, the purity of the high-purity nitrogen gas in step S3 is ≥99.99%, and the rotor speed is adapted to the nitrogen gas flow rate.

[0016] Preferably or optionally, during the purification process in step S3, yttrium synergistically forms a dense YAlO3-Al2O3 composite oxide film with the aluminum substrate. The thickness of the YAlO3-Al2O3 composite oxide film is 30-50 nm, and the electrochemical impedance value is ≥1×10⁻⁶. 4 Ω·cm 2 .

[0017] Preferably or optionally, the temperature-regulating heating in step S5 adopts induction heating.

[0018] Preferably or optionally, the ultrafine particle coating in step S10 is a diamond coating or a TiN coating.

[0019] This invention relates to a high-conductivity and heat-resistant aluminum alloy based on the synergistic effect of yttrium boron and its preparation process, which has the following advantages compared with the prior art: 1. This invention utilizes a precise microalloying ratio design of "yttrium boron synergy + zirconium scandium assistance" combined with a three-stage short-time gradient aging process to evolve the grain structure of aluminum alloy from fine strip-shaped grains to a highly uniform equiaxed grain structure, promoting uniform distribution of grain boundaries. The final product has a conductivity of 60.8-61.8% IACS, a tensile strength of 160-180 MPa, and a tensile strength retention rate of 90.5-93.1% after holding at 230℃ for 1 hour. It is fully adapted to the high requirements of material performance in power transmission scenarios, achieving a synergistic balance of high conductivity, high heat resistance, and excellent mechanical properties.

[0020] 2. This invention avoids cost waste caused by excessive addition of elements by precisely controlling the ratio of each element; it innovatively adopts a three-stage short-time gradient aging process, which shortens the aging cycle by more than 30% compared with the traditional single aging process, while simplifying the process flow, reducing energy consumption, adapting to the needs of large-scale production, and reducing production costs and shortening the production cycle.

[0021] 3. This invention employs a "refining-purification" synergistic process (720℃~740℃ refining + multi-layer foam ceramic filtration + high-purity nitrogen and rotor synergistic degassing), combined with a yttrium element pre-oxidation and impurity removal mechanism, to effectively remove gases and inclusions from the alloy liquid, reducing the oxygen content to below 6.5ppm; yttrium and aluminum elements synergistically form a dense oxide film to prevent the alloy from corroding in harsh natural environments, while a three-stage aging process repairs internal defects, ensuring the stability of the alloy during long-term service and improving the alloy purity and long-term service stability.

[0022] 4. The process parameters of this invention are precisely matched with the micro-alloying system throughout the entire process. From melting and refining to aging and stretching, the parameters of each step have been optimized to ensure process stability and reproducibility. The use of ultra-precision stretching molds and coating design ensures the surface quality and dimensional accuracy of the product, which meets the standards for use of aluminum alloys for power transmission.

[0023] In summary, the aluminum alloy material prepared by this invention has controllable cost and excellent comprehensive performance, and can be widely used in various power transmission scenarios such as high-voltage transmission lines and power distribution equipment. At the same time, it can be extended to other fields that require conductivity, heat resistance and mechanical properties, and has significant practical application value and promotion prospects. Detailed Implementation

[0024] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0025] Application Summary: On one hand, this invention provides a high-conductivity and heat-resistant aluminum alloy based on the synergistic effect of yttrium and boron, comprising, by weight percentage: 0.055%~0.155% yttrium (Y), 0.0022%~0.0110% boron (B), 0.010%~0.030% zirconium (Zr), 0.005%~0.015% scandium (Sc), ≤0.066% silicon (Si), ≤0.088% iron (Fe), ≤0.00808% copper (Cu), ≤0.00808% magnesium (Mg), ≤0.00808% manganese (Mn), ≤0.00808% titanium (Ti), with the remainder being aluminum and other unavoidable trace impurity elements, the total amount of impurity elements being ≤0.044%.

[0026] The mechanism of action of each element: Yttrium and boron work synergistically to refine grains and inhibit the precipitation and growth of impurity phases; zirconium and scandium assist in strengthening, further improving the mechanical properties and thermal stability of the alloy; titanium increases the number of non-uniform nucleation sites, promotes stable crystal precipitation, and effectively limits the crystal growth range to prevent excessive growth; strict control of harmful elements (Si, Fe, Cu, etc.) and the total amount of impurities avoids their deteriorating effects on the alloy's electrical conductivity and mechanical properties; under the synergistic effect of each element, the alloy's electrical conductivity and thermal stability are improved, and its mechanical properties are enhanced, while the optimized composition ratio achieves a balance between cost and performance.

[0027] Furthermore, the mass ratio of yttrium to boron is (10-30):1, preferably 16:1; the mass ratio of yttrium to scandium is (3.5-30):1, preferably 8:1; the total content of yttrium and scandium is 0.06%-0.17%, and the yttrium content is 3.5-10 times the scandium content. Through extensive experiments, this application has found that when yttrium (0.055%~0.155%) and scandium (0.005%~0.015%) are combined with boron and zirconium, a synergistic effect significantly superior to existing technologies is produced. This significantly reduces the amount of rare earth elements used while simultaneously improving electrical conductivity, heat resistance, and mechanical properties, with performance improvements exceeding the expectations of conventional formulations. This specific formulation maximizes the strengthening effect of yttrium-boron synergy and zirconium-scandium assistance, avoiding the cost increases and conductivity decreases associated with high rare earth content.

[0028] This invention establishes a precise proportioning system of "yttrium boron synergy + zirconium scandium assistance," specifically designing a yttrium boron synergistic microalloying system, and combining it with zirconium and scandium auxiliary strengthening elements to optimize the composition ratio and achieve a balance between cost and performance. Simultaneously, it innovatively adopts a short-time gradient aging process to replace the traditional single aging scheme, developing a low-cost aluminum alloy material with a reasonable composition design and efficient preparation process. This material can achieve the high conductivity, high heat resistance, and excellent mechanical properties required for power transmission, making it suitable for various power transmission scenarios such as high-voltage transmission and distribution equipment. It has significant practical application value and promotional significance.

[0029] On the other hand, the present invention also provides a short-time gradient aging process for preparing low-cost, high-conductivity, and heat-resistant aluminum alloys based on the yttrium-boron synergistic effect, comprising the following steps: S1 Smelting: Aluminum ingots and master alloy ingots are smelted according to the above chemical proportions; the aluminum ingots used have a purity ≥99.70%, and a magnetically driven automatic stirring system is used, with the furnace temperature controlled at 750~760℃; the alloy composition includes 10% aluminum-iron master alloy, 10% aluminum-silicon alloy, 50% aluminum-copper alloy, 10% aluminum-titanium alloy additive, and 8% aluminum-boron (AlB). 12 The furnace contains 10% aluminum-yttrium alloy, 10% aluminum-scandium alloy, and pure magnesium. Raw materials are added in descending order of melting temperature, with the magnesium alloy added after the iron, silicon, and copper alloys, and the boron and titanium-based alloys added last. After thorough mixing, the mixture is held at the furnace temperature to ensure complete dissolution of all elements. The oxygen partial pressure inside the furnace is controlled at 10... -9 -10 -7 Atm (atm) allows some yttrium to preferentially react with dissolved oxygen in the melt to form Y2O3 microclusters, which float to the surface and are removed, thus achieving pre-oxidation and impurity removal. This effect overcomes the technical prejudice that "rare earth addition inevitably leads to oxidation and burn-off," and achieves purity improvement through this smelting process.

[0030] S2 Refining: After smelting, the material is transferred to a holding furnace for deep purification to obtain aluminum alloy melt. The refining operation range is 720℃~740℃, the refining time is 30~45 minutes, the ratio of refining agent to aluminum alloy solution is 2.5:1000, and then it is held at 730℃~760℃ for 25 minutes. During the refining process, continuous stirring is carried out to prevent local overheating of the alloy melt and to effectively remove gas and inclusions.

[0031] S3 Purification and Grain Optimization: The molten aluminum alloy is transferred to a dynamic purification system, where the grains are refined and filtered with high precision. The purification system uses multi-layer foam ceramic filter plates with a pore size range of 40ppi~50ppi and a filtration temperature of 740℃. The total amount of grain optimizer is 0.25%, composed of titanium boron rare earth refining agents. During the purification process, high-purity nitrogen gas is used in conjunction with the rotor. The purity of the high-purity nitrogen gas is ≥99.99%, the nitrogen flow rate is 1.2~1.8 L / min, and the rotor speed is 300~500 r / min, further removing gaseous impurities from the alloy and achieving a dual impurity removal effect. Yttrium element synergistically forms a dense YAlO3-Al2O3 composite oxide film with the aluminum matrix. The thickness of this oxide film is 30-50nm, and the electrochemical impedance value is ≥1×10⁻⁶. 4 Ω·cm².

[0032] S4 Continuous Casting: The alloy liquid with optimized grain size is introduced to the casting device and prepared into aluminum alloy ingot blanks by horizontal continuous casting. The casting speed and ingot blank size are set according to production needs. The temperature is controlled to be stable during the casting process to avoid defects such as shrinkage cavities and cracks.

[0033] S5 Continuous Hot Rolling: The aluminum alloy ingot blank is fed into a temperature-controlled heating system (induction heating is preferred) and then heated uniformly at a temperature of 505℃~535℃. Then, it is continuously hot rolled to obtain the alloy rod. The number of passes and the amount of deformation per pass are set according to the specifications of the alloy rod. The temperature at which the hot rolling is completed is ≥360℃ to ensure that the microstructure of the alloy rod is uniform.

[0034] S6 Online Quenching: The alloy rod is rapidly cooled; the quenching temperature is 28℃~30℃, and the quenching pressure is 500±50kPa. During the quenching process, the rod is first immersed in water cooling and then air cooling. The water cooling time, air cooling speed and time are controlled to ensure that the alloy rod is rapidly cooled to 65℃~110℃ to form a fine grain structure.

[0035] S7 Tight Winding: The quenched alloy rod is tightly wound, with a winding temperature ≤100℃, and the winding speed and tension are matched. After winding, a reasonable winding method is used to avoid deformation and surface scratches of the alloy rod.

[0036] S8 Self-Aging: The alloy rod after winding is placed at room temperature for self-aging for no less than 168 hours to achieve primary healing of the alloy lattice fracture surface.

[0037] S9 Short-time gradient aging: The alloy rod after self-aging is placed in an aging furnace for short-time gradient aging treatment; the specific conditions are: first, hold at 150~170℃ for 2~4h, then raise the temperature to 190~210℃ and hold for 1~3h, and finally lower the temperature to 120~140℃ and hold for 2~4h. The heating rate is controlled at 5~10℃ / h and the cooling rate is controlled at 3~8℃ / h throughout the process. Through this step, the healing of lattice fracture surfaces is further promoted, forming a more stable and denser precipitate phase.

[0038] S10 Tensile Deformation: The alloy rod that has undergone short-time gradient aging is subjected to tensile deformation treatment. An ultra-precision tensile die is used, and the contact surface between the die and the metal rod to be stretched is coated with an ultra-fine particle coating (such as a diamond coating). Multiple dies are used for stretching, and reasonable stretching speed and deformation amount per pass are controlled to ensure the surface finish and dimensional accuracy of the alloy rod.

[0039] S11 Controlled aging: The stretched alloy rod is placed in an aging furnace and held at 200℃~230℃ for 5~15 hours. This step can repair the fracture surface and surface cracks and internal defects of the stretched alloy, further improve the uniformity of the distribution of precipitated phases, and give full play to the synergistic strengthening effect of multi-element.

[0040] The "refining-purification" synergistic process of this invention, combined with the addition of yttrium, produces a synergistic purification effect, resulting in an alloy melt inclusion grade ≤0.5, hydrogen content ≤0.08mL / 100gAl, and oxygen content ≤6.5ppm. The short-time gradient aging process, combined with the characteristics of the ultrapure melt, ensures that the conductivity of the alloy decreases by ≤2% after 3000h of high-temperature service, exhibiting long-term service stability far exceeding that of existing technologies.

[0041] The present invention will be further described below with reference to the embodiments. These embodiments are intended to explain the invention and should not be construed as limiting it. Where specific techniques and reaction conditions are not specified in the embodiments, they can be performed according to the techniques or conditions described in the literature or product instructions in the art. All reagents, instruments, or equipment without a specified manufacturer are commercially available.

[0042] Example 1: This example provides a short-time gradient aging process for preparing low-cost, high-conductivity, and heat-resistant aluminum alloys based on the yttrium-boron synergistic effect, including the following steps: S1 Smelting: Aluminum ingots and master alloy ingots are smelted according to the above chemical proportions; the aluminum ingots used have a purity ≥99.70%, and a magnetically driven automatic stirring system is used, with the furnace temperature controlled at 750~760℃; the alloy composition includes 10% aluminum-iron master alloy, 10% aluminum-silicon alloy, 50% aluminum-copper alloy, 10% aluminum-titanium alloy additive, and 8% aluminum-boron (AlB). 12 The furnace contains 10% aluminum-yttrium alloy, 10% aluminum-scandium alloy, and pure magnesium; the magnesium alloy is added after the iron, silicon, and copper alloys, and the boron and titanium-based alloys are added last. After stirring evenly, the mixture is kept at a constant temperature to ensure that all elements are fully dissolved; the oxygen partial pressure in the furnace is controlled at 10. -8 Atm (atm) is used to preferentially react with dissolved oxygen in the melt to form Y₂O₃ microclusters, which float to the surface and are removed, thus achieving pre-oxidation and impurity removal. The sample composition (wt.%) is as follows: Y: 0.08%, B: 0.005%, Zr: 0.020%, Sc: 0.010%, Si: 0.05%, Fe: 0.07%, Cu: 0.006%, Mg: 0.006%, Mn: 0.006%, Ti: 0.015%, total impurities ≤ 0.044%, balance Al.

[0043] S2 Refining: After smelting, the material is transferred to a holding furnace for deep purification to obtain aluminum alloy melt. The refining operation range is 730℃, the refining time is 35 minutes, and the ratio of refining agent to aluminum alloy solution is 2.5:1000. Then, it is held at 740℃ for 25 minutes. During the refining process, continuous stirring is carried out to prevent local overheating of the alloy melt and to effectively remove gas and inclusions.

[0044] S3 Purification and Grain Optimization: The molten aluminum alloy is transferred to a dynamic purification system, where the grains are refined and filtered with high precision. The purification system uses multi-layer foam ceramic filter plates with a pore size range of 40ppi~50ppi and a filtration temperature of 740℃. The total amount of grain optimizer is 0.25%, composed of titanium boron rare earth refining agents. During the purification process, high-purity nitrogen gas is used in conjunction with the rotor. The purity of the high-purity nitrogen gas is ≥99.99%, the nitrogen gas flow rate is 1.5L / min, and the rotor speed is 400 r / min, further removing gaseous impurities from the alloy and achieving a dual impurity removal effect.

[0045] S4 Continuous Casting: The alloy liquid with optimized grain size is introduced to the casting device and prepared into aluminum alloy ingot blanks by horizontal continuous casting. The casting speed and ingot blank size are set according to production needs. The temperature is controlled to be stable during the casting process to avoid defects such as shrinkage cavities and cracks.

[0046] S5 Continuous Hot Rolling: The aluminum alloy ingot blank is fed into a temperature-controlled heating system (induction heating is preferred) and then heated uniformly. The temperature-controlled heating temperature is 520℃, and then continuous hot rolling is performed to obtain the alloy rod. The continuous hot rolling consists of 14 passes, with a deformation amount of 21.62% per pass, and a final rolling temperature of 380℃.

[0047] S6 Online Quenching: Rapidly cools the alloy rod; the quenching temperature is 28℃~30℃, the quenching pressure is 500±50kPa, and during the quenching process, it is first immersed in water cooling and then air cooling. The water cooling time, air cooling speed and time are controlled to ensure that the alloy rod is rapidly cooled to 85℃.

[0048] S7 Tight Winding: The quenched alloy rod is tightly wound, with a winding temperature ≤100℃, and the winding speed and tension are matched. After winding, a reasonable winding method is used to avoid deformation and surface scratches of the alloy rod.

[0049] S8 Self-Aging: The alloy rod after winding is placed at room temperature for self-aging for no less than 168 hours to achieve primary healing of the alloy lattice fracture surface.

[0050] S9 Short-time gradient aging: The alloy rod after self-aging is placed in an aging furnace for short-time gradient aging treatment; the specific conditions are: first, hold at 160℃ for 3 hours, then raise the temperature to 200℃ and hold for 2 hours, and finally lower the temperature to 130℃ and hold for 3 hours. The heating rate is controlled at 8℃ / h and the cooling rate is controlled at 5℃ / h throughout the process.

[0051] S10 Tensile Deformation: The alloy rod that has undergone short-time gradient aging is subjected to tensile deformation treatment. An ultra-precision tensile die is used, and the contact surface between the die and the metal rod to be stretched is coated with diamond microparticles. Multiple dies are used for stretching, and reasonable stretching speed and deformation amount per pass are controlled to ensure the surface finish and dimensional accuracy of the alloy rod.

[0052] S11 Controlled aging: The stretched alloy rod is placed in an aging furnace and held at 210℃ for 10 hours. This step can repair the fracture surface and surface cracks and internal defects of the stretched alloy, further improve the uniformity of the distribution of precipitated phases, and give full play to the synergistic strengthening effect of multi-element.

[0053] Example 2: This example provides a short-time gradient aging process for preparing low-cost, high-conductivity, and heat-resistant aluminum alloys based on the yttrium-boron synergistic effect. The difference from Example 1 is that: In terms of composition, by controlling the amount of feed, the sampled composition is as follows (wt.%): Y: 0.055%, B: 0.0022%, Zr: 0.010%, Sc: 0.005%, Si: 0.066%, Fe: 0.088%, Cu: 0.00808%, Mg: 0.00808%, Mn: 0.00808%, Ti: 0.0088%, total impurities ≤ 0.044%, balance Al.

[0054] In terms of process, S2: Refining at 720℃ for 30 minutes, refining agent ratio 2.5:1000, holding at 730℃ for 25 minutes; S9: Holding at 150℃ for 4 hours → Holding at 190℃ for 3 hours → Holding at 120℃ for 4 hours, heating up 5℃ / hour, cooling down 3℃ / hour; S11: Holding at 200℃ for 15 hours.

[0055] Other processes and parameters are the same as in Example 1, and will not be repeated here.

[0056] Example 3: This example provides a short-time gradient aging process for preparing low-cost, high-conductivity, and heat-resistant aluminum alloys based on the yttrium-boron synergistic effect. The difference from Example 1 is as follows: In terms of composition, by controlling the amount of feed, the sampled composition is as follows (wt.%): Y: 0.155%, B: 0.0110%, Zr: 0.030%, Sc: 0.015%, Si: 0.04%, Fe: 0.06%, Cu: 0.005%, Mg: 0.005%, Mn: 0.005%, Ti: 0.0255%, total impurities ≤ 0.044%, balance is Al.

[0057] In terms of process, S2: Refining at 740℃ for 45 minutes, refining agent ratio 2.5:1000, holding at 760℃ for 25 minutes; S9: Holding at 170℃ for 2 hours → Holding at 210℃ for 1 hour → Holding at 140℃ for 2 hours, heating up at 10℃ / hour, cooling down at 8℃ / hour; S11: Holding at 230℃ for 5 hours.

[0058] Other processes and parameters are the same as in Example 1, and will not be repeated here.

[0059] Comparative Example 1: This embodiment provides a low-cost, high-conductivity, and heat-resistant aluminum alloy preparation process, which differs from Example 1 in that: In terms of composition, there are no Y and B elements, and the remaining components are the same as in Example 1, so the sampled components are as follows (wt.%): Zr: 0.020%, Sc: 0.010%, Si: 0.05%, Fe: 0.07%, Cu: 0.006%, Mg: 0.006%, Mn: 0.006%, Ti: 0.015%, total impurities ≤ 0.044%, and the balance is Al.

[0060] Other processes and parameters are the same as in Example 1, and will not be repeated here.

[0061] Comparative Example 2: This embodiment provides a low-cost, high-conductivity, and heat-resistant aluminum alloy preparation process, which differs from Example 1 in that: In terms of composition, by controlling the amount of feed, the composition measured by sampling is as follows (wt.%): Y: 0.20%, B: 0.015%, Zr: 0.020%, Sc: 0.010%, Si: 0.05%, Fe: 0.07%, Cu: 0.006%, Mg: 0.006%, Mn: 0.006%, Ti: 0.015%, total impurities ≤ 0.044%, balance is Al.

[0062] Other processes and parameters are the same as in Example 1, and will not be repeated here.

[0063] Comparative Example 3: This embodiment provides a low-cost, high-conductivity, and heat-resistant aluminum alloy preparation process, which differs from Example 1 in that: The composition is the same as that of Example 1.

[0064] In terms of process: there is no short-time gradient aging (S9 omitted), and a single aging is used: heat preservation at 180℃ for 8 hours. The rest of the process is the same as in Example 1.

[0065] Comparative Example 4: This embodiment provides a low-cost, high-conductivity, and heat-resistant aluminum alloy preparation process, which differs from Example 1 in that: The composition is the same as that of Example 1.

[0066] In terms of process: S2 refining temperature 710℃, refining agent ratio 2:1000, the rest of the process is the same as in Example 1.

[0067] Comparative Example 5: This embodiment provides a low-cost, high-conductivity, and heat-resistant aluminum alloy preparation process, which differs from Example 1 in that: In terms of composition, by controlling the amount of feed, the composition measured by sampling is as follows (wt.%): Y: 0.3%, B: 0.005%, Zr: 0.05%, Sc: 0.2%, Si: 0.05%, Fe: 0.07%, Mg: 0.006%, Mn: 0.006%, Ti: 0.015%, total impurities ≤ 0.044%, and the balance is Al.

[0068] Other processes and parameters are the same as in Example 1, and will not be repeated here.

[0069] Comparative Example 6: This embodiment provides a low-cost, high-conductivity, and heat-resistant aluminum alloy preparation process, which differs from Example 1 in that: In terms of composition, by controlling the amount of feed, the composition measured by sampling is as follows (wt.%): Y: 0.5%, B: 0.01%, Zr: 0.1%, Sc: 0.35%, Si: 0.05%, Fe: 0.07%, Mg: 0.006%, Mn: 0.006%, Ti: 0.015%, total impurities ≤ 0.044%, and the balance is Al.

[0070] Other processes and parameters are the same as in Example 1, and will not be repeated here.

[0071] Comparative Example 7: This embodiment provides a low-cost, high-conductivity, and heat-resistant aluminum alloy preparation process, which differs from Example 1 in that: In terms of composition, it contains yttrium but no boron. By controlling the amount of feed, the composition measured by sampling is as follows (wt.%): Y: 0.08%, Zr: 0.02%, Sc: 0.01%, Si: 0.05%, Fe: 0.07%, Mg: 0.006%, Mn: 0.006%, Ti: 0.015%, total impurities ≤ 0.044%, and the balance is Al.

[0072] Other processes and parameters are the same as in Example 1, and will not be repeated here.

[0073] Comparative Example 8: This embodiment provides a low-cost, high-conductivity, and heat-resistant aluminum alloy preparation process, which differs from Example 1 in that: In terms of composition, it contains boron but no yttrium. By controlling the amount of feed, the composition measured by sampling is as follows (wt.%): B: 0.05%, Zr: 0.02%, Sc: 0.01%, Si: 0.05%, Fe: 0.07%, Mg: 0.006%, Mn: 0.006%, Ti: 0.015%, total impurities ≤ 0.044%, and the balance is Al.

[0074] Other processes and parameters are the same as in Example 1, and will not be repeated here.

[0075] Performance Test 1: For the aluminum alloy products prepared in Examples 1-3 and Comparative Examples 1-8 above, their conductivity (IACS), tensile strength (MPa), yield strength (MPa), elongation (%), and heat resistance stability (tensile strength retention rate after holding at 230℃ for 1 hour) were tested according to the relevant standards for aluminum alloy materials for power transmission (conductivity according to GB / T 351—2019, tensile strength according to GB / T 228.1—2010). Conventional testing equipment was used, and the test results are shown in the table below: Table 1 Performance test results of the examples and comparative examples Group Conductivity (%IACS) Tensile strength (MPa) Yield strength (MPa) Elongation (%) Tensile strength retention rate (%) after heat treatment at 230℃ for 1 hour Example 1 61.5 175 150 15.8 92.3 Example 2 60.8 165 140 14.5 90.5 Example 3 61.8 180 155 15.2 93.1 Comparative Example 1 58.6 140 120 12.3 82.7 Comparative Example 2 59.2 145 125 11.8 83.5 Comparative Example 3 60.0 150 130 13.1 85.2 Comparative Example 4 60.5 155 135 13.5 86.7 Comparative Example 5 59.8 185 88.5 12.5 280 Comparative Example 6 58.5 190 85.0 10.2 450 Comparative Example 7 60.2 158 86.5 25.6 98 Comparative Example 8 59.5 152 85.8 28.4 96 Discussion: As can be seen from the above performance test results, the aluminum alloy products prepared in Examples 1 to 3 have significantly better conductivity (60.8-61.8% IACS), tensile strength (165-180MPa), yield strength, elongation, and heat resistance stability (tensile strength retention rate after holding at 230℃ for 1h) than the comparative examples.

[0076] The specific analysis is as follows: Comparative Example 1, which did not add yttrium and boron, as did Comparative Example 7 and Comparative Example 8, which also did not add yttrium, failed to achieve the synergistic microalloying effect of yttrium and boron. Insufficient grain refinement and excessive precipitation of impurity phases led to a significant decline in all properties, particularly in thermal stability and electrical conductivity. This demonstrates that the synergistic effect of yttrium and boron is the core of this invention in improving alloy performance. In Comparative Example 2, excessive yttrium and boron resulted in the formation of too many brittle phases within the alloy, which reduced elongation and electrical conductivity while increasing production costs. This demonstrates the rigorous rationality and optimality of the component ratio in this invention. Comparative Example 3, employing a traditional single aging scheme, could not fully leverage the synergistic strengthening effect of multiple elements. Uneven distribution of precipitated phases led to a decrease in the mechanical properties and thermal stability of the alloy. This demonstrates that the short-time gradient aging process is the key to shortening the production cycle and improving the overall performance of the alloy in this invention. The low refining temperature and low refining agent ratio in Comparative Example 4 resulted in insufficient purity of the alloy melt, with a large amount of gas and inclusions, affecting the microstructure and overall properties of the alloy, thus proving the effectiveness of the process parameters in this invention. In Comparative Examples 5 and 6, the high rare earth ratio led to decreased electrical conductivity and heat resistance, and a significant increase in cost, rendering them unsuitable for large-scale production.

[0077] Performance Test 2: The aluminum alloy products prepared in Example 1 and Comparative Example 8 were tested according to the relevant standards for aluminum alloy materials for power transmission. Specifically, the tests included: rating the inclusion levels using a 100× optical microscope according to the metallographic method of GB / T10561; detecting the hydrogen content (mL / 100gAl) using the thermal conductivity method and an oxygen-nitrogen analyzer; detecting the oxygen content (ppm) using the pulsed infrared absorption method and an oxygen-nitrogen analyzer; measuring the cross-sectional morphology of the sample through metallographic microscopy, and calculating the average oxide film thickness (nm); and testing the conductivity according to GB / T351-2019 and calculating the conductivity reduction rate.

[0078] Table 2 Results of melt purity and long-term stability tests Group Inclusion level Hydrogen content (mL / 100gAl) Oxygen content (ppm) Oxide film thickness (nm) 3000h conductivity decrease rate (%) Example 1 Level 0.5 0.08 6.5 45±5 1.8 Comparative Example 8 Level 2.0 0.18 15.2 120±15 4.5 Discussion: The melt purity (inclusions ≤ 0.5 grade, hydrogen ≤ 0.08 mL / 100g Al, oxygen ≤ 6.5 ppm) and long-term stability (conductivity decrease ≤ 2% after 3000 h) of Example 1 far exceed existing technologies. Comparative Example 8, which did not contain yttrium, showed a significant decrease in purity and stability, demonstrating the synergistic effect of the "refining-purification + yttrium" process in this invention.

[0079] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A high-conductivity and heat-resistant aluminum alloy based on the synergistic effect of yttrium boron, characterized in that, By weight percentage, it includes: yttrium 0.055%~0.155%, boron 0.0022%~0.0110%, zirconium 0.010%~0.030%, scandium 0.005%~0.015%, silicon ≤0.066%, iron ≤0.088%, copper ≤0.00808%, magnesium ≤0.00808%, manganese ≤0.00808%, titanium 0.0088%~0.0255%, with the remainder being aluminum and other unavoidable trace impurity elements, and the total amount of said impurity elements ≤0.044%.

2. The high-conductivity and heat-resistant aluminum alloy based on the yttrium-boron synergistic effect according to claim 1, characterized in that, The unavoidable trace impurity elements include chromium, nickel, and zinc, wherein chromium ≤ 0.01%, nickel ≤ 0.01%, and zinc ≤ 0.024%.

3. The high-conductivity and heat-resistant aluminum alloy based on the yttrium-boron synergistic effect according to claim 1, characterized in that, The mass ratio of yttrium to boron is (10-30):1, preferably 16:1; The mass ratio of yttrium to scandium is (3.5-30):1, preferably 8:1; The total content of yttrium and scandium is 0.06%-0.17%, and the yttrium content is 3.5-10 times that of scandium.

4. A preparation process for a high-conductivity and heat-resistant aluminum alloy based on the synergistic effect of yttrium boron, characterized in that, Includes the following steps: S1 Smelting: Aluminum ingots and intermediate alloy ingots are smelted according to the chemical proportions described in any one of claims 1 to 3. The purity of the aluminum ingots is ≥99.70%, the furnace temperature is controlled at 750~760℃, and magnetic force is used to drive automatic stirring. Raw materials are added from high to low melting temperature. After stirring evenly, the mixture is kept warm until all elements are fully dissolved. S2 Refining: Transfer the smelted material to a holding furnace and refine it at 720℃~740℃ for 30~45 minutes. The ratio of refining agent to aluminum alloy solution is 2.5:1000. Then, hold it at 730℃~760℃ for 25 minutes, stirring continuously during the refining process. S3 Purification and Grain Optimization: The molten aluminum alloy is transferred to a dynamic purification system, which uses a multi-layer foam ceramic filter plate with a pore size of 40ppi~50ppi and a filtration temperature of 740℃. A total of 0.25% titanium boron rare earth refining agent is added to optimize the grain size. At the same time, high-purity nitrogen gas is used in conjunction with the rotor for degassing. S4 Continuous casting: The alloy liquid with optimized grains is prepared into aluminum alloy ingot blanks by horizontal continuous casting, and the casting temperature is controlled to be stable. S5 Continuous hot rolling: The aluminum alloy ingot blank is heated at 505℃~535℃ and then continuously hot rolled to obtain the alloy rod. The temperature of hot rolling is ≥360℃. S6 Online Quenching: The alloy rod is first immersed in water cooling, then air cooling, with a quenching temperature of 28℃~30℃, a quenching pressure of 500±50kPa, and cooled to 65℃~110℃. S7 Tight winding: The quenched alloy rod is wound up at ≤100℃, and the winding speed and tension are controlled to avoid deformation and scratches; S8 Self-Aging: The alloy rod after winding is placed at room temperature for self-aging, and the aging time is not less than 168 hours; S9 Short-time gradient aging: The alloy rod after self-aging is placed in an aging furnace, first held at 150~170℃ for 2~4h, then heated to 190~210℃ and held for 1~3h, and finally cooled to 120~140℃ and held for 2~4h. The heating rate is controlled at 5~10℃ / h and the cooling rate at 3~8℃ / h throughout the process. S10 Tensile Deformation: The alloy rod is drawn in multiple passes using an ultra-precision stretching die. The die contact surface is coated with ultra-fine particles to control the stretching speed and the amount of deformation per pass. S11 Controlled aging: The stretched alloy rod is placed in an aging furnace and held at 200℃~230℃ for 5~15 hours.

5. The preparation process of the high-conductivity and heat-resistant aluminum alloy based on the yttrium-boron synergistic effect according to claim 4, characterized in that, The intermediate alloy ingot mentioned in step S1 includes 10% aluminum-iron intermediate alloy, 10% aluminum-silicon alloy, 50% aluminum-copper alloy, 10% aluminum-titanium alloy additive, 8% aluminum-boron alloy, 10% aluminum-yttrium alloy, 10% aluminum-scandium alloy and pure magnesium, wherein the magnesium alloy is added after the iron, silicon and copper alloys, and the boron and titanium-based alloys are added last. During the smelting process in step S1, the oxygen partial pressure inside the furnace is controlled to be 10. -9 -10 -7 atm.

6. The preparation process of the high-conductivity and heat-resistant aluminum alloy based on the yttrium-boron synergistic effect according to claim 4, characterized in that, The refining agent mentioned in step S2 is a sodium salt or rare earth refining agent.

7. The preparation process of the high-conductivity and heat-resistant aluminum alloy based on the yttrium-boron synergistic effect according to claim 4, characterized in that, The purity of the high-purity nitrogen gas mentioned in step S3 is ≥99.99%, the nitrogen gas flow rate is 1.2~1.8 L / min, and the rotor speed is 300~500 r / min.

8. The preparation process of the high-conductivity and heat-resistant aluminum alloy based on the yttrium-boron synergistic effect according to claim 4, characterized in that, During the purification process in step S3, yttrium synergistically forms a dense YAlO3-Al2O3 composite oxide film with the aluminum substrate. The thickness of the YAlO3-Al2O3 composite oxide film is 30-50 nm, and the electrochemical impedance value is ≥1×10⁻⁶. 4 Ω·cm 2 .

9. The preparation process of the high-conductivity and heat-resistant aluminum alloy based on the yttrium-boron synergistic effect according to claim 4, characterized in that, The temperature adjustment heating in step S5 adopts induction heating.

10. The preparation process of the high-conductivity and heat-resistant aluminum alloy based on the yttrium-boron synergistic effect according to claim 4, characterized in that, The ultrafine particle coating mentioned in step S10 is a diamond coating or a TiN coating.