Heat-resistant high-strength high-conductivity aluminum alloy as well as preparation method and application thereof

Abstract

The invention discloses a heat-resistant, high-strength and high-conductivity aluminum alloy and a preparation method and application thereof, and belongs to the technical field of aluminum alloys, the heat-resistant, high-strength and high-conductivity aluminum alloy comprises the following components in percentage by weight: 0.4%-0.8% of Mg, 0.6%-1.3% of Si, 0.01%-0.3% of Mn, 0.001%-0.15% of Cu, 0.001%-0.15% of Zn, 0.001%-0.15% of Zr, 0.0001%-0.1% of Er, 0.0001%-0.05% of Sc, 0.001%-0.05% of Sr, less than 0.15% of Fe, less than 0.1% of other impurities and the balance of Al. The room-temperature mechanical properties of the heat-resistant high-strength high-conductivity aluminum alloy are as follows: the yield strength is greater than 96 MPa, the tensile strength is greater than 207 MPa, the elongation is greater than 16%, and the room-temperature conductivity is greater than 55% IACS (International Annealed Copper Standard); and the mechanical properties at 180 DEG C are as follows: the yield strength is greater than 92 MPa, the tensile strength is greater than 194 MPa, and the elongation is greater than 24%.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy technology, and particularly relates to a heat-resistant, high-strength, and high-conductivity aluminum alloy, its preparation method, and its application. Background Technology

[0002] With the continuous innovation in the new energy vehicle sector, the demand for metallic materials that integrate functionality and structure is increasing. In particular, given the significant increase in rotor speed of current and future new energy vehicle motors, the insufficient strength of existing pure aluminum materials, despite their excellent electrical conductivity, is becoming increasingly apparent in practical applications. Therefore, developing a new generation of aluminum alloy materials that combines high conductivity with moderate strength has become a top priority. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a heat-resistant, high-strength, and high-conductivity aluminum alloy, its preparation method, and its applications.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] One of the technical solutions of the present invention:

[0006] This invention provides a heat-resistant, high-strength, and high-conductivity aluminum alloy, which, by weight percentage, consists of the following components: Mg 0.4%-0.8%, Si 0.6%-1.3%, Mn 0.01-0.3%, Cu 0.001-0.15%, Zn 0.001-0.15%, Zr 0.001%-0.15%, Er 0.0001%-0.1%, Sc 0.0001%-0.05%, Sr 0.001%-0.05%, Fe <0.15%, other impurities <0.1%, and the balance being Al.

[0007] The room temperature mechanical properties (test standard GB / T 228.1-2021) of the heat-resistant, high-strength, and high-conductivity aluminum alloy of this invention are as follows: yield strength greater than 96 MPa, tensile strength greater than 207 MPa, elongation greater than 16%, and room temperature conductivity greater than 55% IACS; the mechanical properties at 180℃ (test standard GB / T 228.2-2015) are as follows: yield strength greater than 92 MPa, tensile strength greater than 194 MPa, and elongation greater than 24%.

[0008] Furthermore, the heat-resistant, high-strength, and high-conductivity aluminum alloy, by weight percentage, comprises the following components: Mg 0.4%-0.6%, Si 0.6%-0.9%, Mn 0.01%-0.3%, Cu 0.001%-0.1%, Zn 0.001%-0.1%, Zr 0.001%-0.1%, Er 0.0001%-0.005%, Sc 0.0001%-0.01%, Sr 0.001%-0.05%, Fe <0.15%, other impurities <0.1%, and the balance being Al.

[0009] Furthermore, the heat-resistant, high-strength, and high-conductivity aluminum alloy, by weight percentage, comprises the following components: Mg 0.6%-0.8%, Si 0.9%-1.3%, Mn 0.01-0.3%, Cu 0.001-0.1%, Zn 0.001-0.1%, Zr 0.001%-0.1%, Er 0.0001%-0.005%, Sc 0.0001%-0.01%, Sr 0.001%-0.05%, Fe <0.15%, other impurities <0.1%, and the balance being Al.

[0010] Furthermore, the heat-resistant, high-strength, and high-conductivity aluminum alloy, by weight percentage, comprises the following components: Mg 0.6%-0.8%, Si 0.9%-1.3%, Mn 0.01-0.3%, Cu 0.001-0.15%, Zn 0.1-0.15%, Zr 0.1%-0.15%, Er 0.005%-0.1%, Sc 0.01%-0.05%, Sr 0.001%-0.05%, Fe <0.15%, other impurities <0.1%, and the balance being Al.

[0011] The second technical solution of the present invention:

[0012] This invention also provides a method for preparing the above-mentioned heat-resistant, high-strength, and high-conductivity aluminum alloy, comprising the following steps:

[0013] Each raw material is accurately weighed by weight percentage and then dried. The raw materials are selected from pure Al, pure Si, pure Mg, pure Cu, pure Zn, Al-Er master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Mn master alloy and Al-Sr master alloy.

[0014] The pure Al is added to the melting device and heated to a first temperature until the pure Al is completely melted;

[0015] After the pure Al is melted, the Al-Mn master alloy, pure Si, pure Cu and pure Zn are added, and after melting, the temperature is raised to a second temperature;

[0016] After heating to the second temperature, the Al-Sc master alloy, Al-Zr master alloy and Al-Er master alloy are added, stirred and allowed to stand. Then the temperature is lowered to the third temperature, the pure Mg and Al-Sr master alloy are added, completely melted and allowed to stand. Then refining and degassing are carried out. After that, the temperature is lowered to the fourth temperature and allowed to stand again to obtain aluminum alloy melt.

[0017] The aluminum alloy melt is subjected to high-pressure casting to obtain a casting, wherein the pressure of high-pressure casting is 80-90 MPa.

[0018] The casting is subjected to two-stage heat treatment to obtain the heat-resistant, high-strength, and high-conductivity aluminum alloy.

[0019] Furthermore, the preheating temperature is 200-220℃.

[0020] Furthermore, the first temperature is 700℃-720℃;

[0021] And / or, the second temperature is 800-820℃;

[0022] And / or, the third temperature is 740-750°C;

[0023] And / or, the fourth temperature is 690-705°C.

[0024] Furthermore, during the high-pressure casting process, the injection speed is 4.5 m / s, and the mass ratio of the release agent to water is 1:100.

[0025] Furthermore, the heating rate of the first-stage heat treatment is 50℃ / h, the holding temperature is 350℃, and the holding time is 1h;

[0026] The second-stage heat treatment has a heating rate of 50℃ / h, a holding temperature of 175℃, and a holding time of 2h.

[0027] The third technical solution of the present invention:

[0028] The present invention also provides an application of the above-mentioned heat-resistant, high-strength, and high-conductivity aluminum alloy in the automotive field.

[0029] For example, the heat-resistant, high-strength, and high-conductivity aluminum alloy of this invention can be used to manufacture motors for new energy vehicles.

[0030] Compared with the prior art, the present invention has the following advantages and technical effects:

[0031] 1. The heat-resistant, high-strength, and high-conductivity aluminum alloy prepared by the method of this invention has significant industrial application value. It has good fluidity and low solidification shrinkage, which is conducive to casting. The strength and thermal conductivity of the aluminum alloy are greatly improved by a simple heat treatment process of the casting, thereby meeting the application requirements of the automotive industry.

[0032] 2. Compared with existing products, the heat-resistant, high-strength, and high-conductivity aluminum alloy obtained by this invention has higher room temperature strength and high temperature strength, while also having better conductivity. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 This is a low-magnification metallographic image (100 μm) of the heat-resistant, high-strength, and high-conductivity aluminum alloy in Example 1.

[0035] Figure 2 This is a high-magnification metallographic image (20 μm) of the heat-resistant, high-strength, and high-conductivity aluminum alloy in Example 1. Detailed Implementation

[0036] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0037] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0038] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0039] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0040] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0041] The embodiments of the present invention provide a heat-resistant, high-strength, and high-conductivity aluminum alloy, which, by weight percentage, is composed of the following components: Mg (magnesium) 0.4%-0.8%, Si (silicon) 0.6%-1.3%, Mn (manganese) 0.01%-0.3%, Cu (copper) 0.001%-0.15%, Zn (zinc) 0.001%-0.15%, Zr (zirconium) 0.001%-0.15%, Er (erbium) 0.0001%-0.1%, Sc (scandium) 0.0001%-0.05%, Sr (strontium) 0.001%-0.05%, Fe <0.15%, other impurities <0.1%, and the balance being Al.

[0042] The room temperature mechanical properties (test standard GB / T 228.1-2021) of the heat-resistant, high-strength, and high-conductivity aluminum alloy of this invention are as follows: yield strength greater than 96 MPa, tensile strength greater than 207 MPa, elongation greater than 16%, and room temperature conductivity greater than 55% IACS; the mechanical properties at 180℃ (test standard GB / T 228.2-2015) are as follows: yield strength greater than 92 MPa, tensile strength greater than 194 MPa, and elongation greater than 24%.

[0043] In some preferred embodiments of the present invention, the heat-resistant, high-strength, and high-conductivity aluminum alloy is composed of the following components by weight percentage: Mg 0.6%-0.8%, Si 0.9%-1.3%, Mn 0.01-0.3%, Cu 0.001-0.15%, Zn 0.1-0.15%, Zr 0.1%-0.15%, Er 0.005%-0.1%, Sc 0.01%-0.05%, Sr 0.001%-0.05%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al.

[0044] In some preferred embodiments of the present invention, the heat-resistant, high-strength, and high-conductivity aluminum alloy is composed of the following components by weight percentage: Mg 0.4%-0.6%, Si 0.6%-0.9%, Mn 0.01-0.3%, Cu 0.001-0.1%, Zn 0.001-0.1%, Zr 0.001%-0.1%, Er 0.0001%-0.005%, Sc 0.0001%-0.01%, Sr 0.001%-0.05%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al. For example, a heat-resistant, high-strength, and high-conductivity aluminum alloy, by weight percentage, consists of the following components: Mg 0.55%, Si 0.88%, Mn 0.19%, Cu 0.059%, Zn 0.043%, Zr 0.055%, Er 0.0028%, Sc 0.0049%, Sr 0.012%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al.

[0045] In some preferred embodiments of the present invention, the heat-resistant, high-strength, and high-conductivity aluminum alloy is composed of the following components by weight percentage: Mg 0.6%-0.8%, Si 0.9%-1.3%, Mn 0.01-0.3%, Cu 0.001-0.1%, Zn 0.001-0.1%, Zr 0.001%-0.1%, Er 0.0001%-0.005%, Sc 0.0001%-0.01%, Sr 0.001%-0.05%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al. For example, a heat-resistant, high-strength, and high-conductivity aluminum alloy, by weight percentage, consists of the following components: Mg 0.71%, Si 1.21%, Mn 0.21%, Cu 0.068%, Zn 0.057%, Zr 0.043%, Er 0.0043%, Sc 0.0094%, Sr 0.020%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al.

[0046] In some preferred embodiments of the present invention, the heat-resistant, high-strength, and high-conductivity aluminum alloy is composed of the following components by weight percentage: Mg 0.6%-0.8%, Si 0.9%-1.3%, Mn 0.01-0.3%, Cu 0.1-0.15%, Zn 0.1-0.15%, Zr 0.1%-0.15%, Er 0.0035%-0.1%, Sc 0.0001%-0.01%, Sr 0.001%-0.05%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al. For example, a heat-resistant, high-strength, and high-conductivity aluminum alloy, by weight percentage, consists of the following components: Mg 0.73%, Si 1.19%, Mn 0.24%, Cu 0.113%, Zn 0.133%, Zr 0.118%, Er 0.0039%, Sc 0.0088%, Sr 0.019%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al.

[0047] In some preferred embodiments of the present invention, the heat-resistant, high-strength, and high-conductivity aluminum alloy is composed of the following components by weight percentage: Mg 0.6%-0.8%, Si 0.9%-1.3%, Mn 0.01%-0.3%, Cu 0.1%-0.15%, Zn 0.1%-0.15%, Zr 0.1%-0.15%, Er 0.0045%-0.1%, Sc 0.01%-0.05%, Sr 0.001%-0.05%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al. For example, a heat-resistant, high-strength, and high-conductivity aluminum alloy, by weight percentage, consists of the following components: Mg 0.79%, Si 1.28%, Mn 0.28%, Cu 0.138%, Zn 0.119%, Zr 0.125%, Er 0.0041%, Sc 0.025%, Sr 0.021%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al.

[0048] The embodiments of the present invention also provide a method for preparing the above-mentioned heat-resistant, high-strength, and high-conductivity aluminum alloy, comprising the following steps:

[0049] Each raw material is accurately weighed according to its weight percentage and then dried. The raw materials are selected from pure Al, pure Si, pure Mg, pure Cu, pure Zn, Al-Er master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Mn master alloy and Al-Sr master alloy.

[0050] Pure Al is added to the melting apparatus and heated to the first temperature until the pure Al melts.

[0051] After pure Al is melted, Al-Mn master alloy, pure Si, pure Cu and pure Zn are added, and after melting, the temperature is raised to the second temperature;

[0052] After heating to the second temperature, Al-Sc master alloy, Al-Zr master alloy and Al-Er master alloy are added, stirred and allowed to stand. Then the temperature is lowered to the third temperature, pure Mg and Al-Sr master alloy are added, completely melted and allowed to stand. Then refining and degassing are carried out. After that, the temperature is lowered to the fourth temperature and allowed to stand again to obtain aluminum alloy melt.

[0053] The aluminum alloy melt is subjected to high pressure casting to obtain castings. The pressure of high pressure casting is 80-90MPa.

[0054] The casting is subjected to two-stage heat treatment, and then air-cooled after the second-stage heat treatment to obtain a heat-resistant, high-strength, and high-conductivity aluminum alloy.

[0055] Among metals, pure aluminum ranks fourth in electrical conductivity, following silver, copper, and gold. According to the free electron theory, the conductivity of a metal is attributed to the orderly migration of free electrons under the influence of an external electric field; any factor that interferes with this process will affect its conductivity. For aluminum alloys, their conductivity is influenced by a combination of factors, primarily including temperature, chemical composition, crystal structure, and the concentration and mobility of impurities and defects. Therefore, the conductivity of aluminum and its alloys is not only constrained by external conditions such as ambient temperature but also by factors such as the morphology, quantity, and distribution of solid-solution atoms, the characteristics of grain boundaries and substructures, the type, quantity, and distribution of the second phase, and the concentration of internal defects such as vacancies and dislocations. The high strength of alloys stems from the hindrance of dislocation line movement by internal defects, meaning it is difficult to simultaneously achieve high strength and high conductivity in alloy materials. Common strengthening methods for alloys include grain boundary strengthening, solid solution strengthening, work hardening (including texture strengthening and dislocation strengthening), and second-phase strengthening. Among these factors, solid-solution atoms have a particularly significant impact on the conductivity of aluminum alloys. They significantly enhance the scattering effect, thereby reducing the conductivity of the alloy. In this invention, to meet the requirement of avoiding heat treatment and precipitating solid-solution elements through subsequent aging treatment, thereby achieving the goal of improving strength and conductivity, this invention selects elements with low solid solubility or adds fewer elements with high solid solubility during the alloy development process, while simultaneously precipitating solid-solution elements through heat treatment, thus balancing the high strength and high conductivity of the aluminum alloy material.

[0056] In this invention, the trace addition of Mg and Si, while minimally impairing conductivity, can form the Mg2Si phase, providing heterogeneous nucleation sites, refining grains, and further improving the yield strength and tensile strength of the alloy. Simultaneously, the hypoeutectic Al-Si system exhibits good fluidity and corrosion resistance. Furthermore, the addition of Sr can effectively refine the magnesium-silicon phase, resulting in a more uniform phase distribution and reducing local segregation. Sc has been used in aluminum alloys for a long time; the introduction of trace amounts of Sc can significantly improve the performance of aluminum alloys. However, due to its high cost, it is mainly used in aerospace and military aluminum alloys. Therefore, it is necessary to find new alternative elements to reduce costs. Rare earth element Er achieves the same strengthening effect as Sc by forming Al3Er nanoprecipitates in aluminum alloys, making it a favorable candidate to replace Sc. However, compared to Sc, Er has a higher diffusion rate at high temperatures, causing the Al3Er nanoprecipitates to coarsen rapidly at high temperatures, leading to a decrease in the high-temperature mechanical properties of the alloy. To prevent the coarsening of the Al3Er precipitate phase at high temperatures, this invention introduces Zr while retaining trace amounts of Sc. Zr has the lowest diffusion rate in aluminum alloys, and the precipitation of Er, Sc, and Zr has a synergistic effect. During heat treatment, the Al3Er phase nucleates and grows first, followed by Sc precipitation adhering to the periphery of the Al3Er phase, forming a core-shell Al3Er-Al3Sc composite precipitate phase. Finally, Zr, with the lowest diffusion rate, precipitates around the Al3Sc, ultimately forming a nanoscale core-inner-shell Al3Er-Al3Sc-Al3Zr precipitate phase structure. In this core-shell structure, the diffusion rate of the relevant precipitates decreases sequentially from the core to the outside, locking the easily coarsening Al3Er precipitate phase inside the structure. This ensures that the nanoscale precipitate phase structure can still maintain its strengthening effect at high temperatures, effectively solving the problem of insufficient high-temperature strengthening. According to the Orowan mechanism, dislocations cannot pass through particles and can only bypass them. During the process of bypassing particles, dislocation lines grow, leading to increased stress that promotes dislocation movement and thus a strengthening effect. The size and density of the particles significantly affect the effectiveness of the Orowan mechanism: the finer the particles and the larger the radius of curvature during bypassing, the more pronounced the stress increase. Therefore, the nanoscale core-shell spherical nanoprecipitate structure can significantly improve the strength of the alloy. Due to the low solid solubility of Er and Zr in aluminum alloys, in order to achieve Er and Zr precipitation through non-equilibrium solidification to form a supersaturated solid solution, the casting temperature must be increased (greater than 750℃). The addition of Mn, Cu, and Zn serves two purposes: firstly, to adjust the solid-liquid phase lines of the alloy and optimize its fluidity; secondly, it can alter the precipitate sequence and structure of Mg2Si, further improving the strength of the aluminum alloy.

[0057] In some preferred embodiments of the present invention, the preheating temperature is 200-220°C. For example, the preheating temperature can be 200°C, 201°C, 205°C, 210°C, 215°C, or 220°C, as long as it is sufficient to dry the raw materials.

[0058] In some preferred embodiments of the present invention, the first temperature is 700℃-720℃; the second temperature is 800-820℃; the third temperature is 740-750℃; and the fourth temperature is 690-705℃.

[0059] In some preferred embodiments of the present invention, after obtaining the aluminum alloy melt, composition testing is performed. If the composition is qualified, high-pressure casting is then performed at a fourth temperature. During high-pressure casting, the injection speed is 4.5 m / s, the mass ratio of release agent to water is 1:100, and the mold temperature is 210°C. In the following embodiments of the present invention, the mold is a die-casting test bar mold.

[0060] In some preferred embodiments of the present invention, the settling time is 10-15 minutes each time.

[0061] In the following embodiments of the present invention, the refining process is as follows: 5% by weight of refining agent (a mixture of KCl, NaCl, NaF and CaF2 in a mass ratio of 1:1:1:1) is added to the melt and stirred continuously for 2 minutes. After floating slag is generated on the surface of the melt, the floating slag is removed. The degassing process is as follows: argon gas is introduced into the melt and the gas is continuously blown in for 3 minutes.

[0062] In some preferred embodiments of the present invention, the heating rate of the first-stage heat treatment is 50℃ / h, the holding temperature is 350℃, and the holding time is 1h; the heating rate of the second-stage heat treatment is 50℃ / h, the holding temperature is 175℃, and the holding time is 2h. Exemplarily, the first-stage heat treatment process is as follows: the casting is placed in a heat treatment furnace, heated with the furnace at a heating rate of 50℃ / h, held at 350℃, and held for 1h, then removed and water-quenched; the second-stage heat treatment process is as follows: the casting after the first-stage heat treatment is placed in a heat treatment furnace, heated with the furnace at a heating rate of 50℃ / h, held at 175℃, and held for 2h, after which it is removed and subjected to forced air cooling.

[0063] Forced air cooling is a cooling method that uses fans or blowers to drive airflow, enhancing heat dissipation. Its core principle is to utilize forced air convection to increase the convective heat transfer coefficient, thereby rapidly removing heat. Compared to natural convection, forced air cooling has lower thermal resistance and higher heat dissipation efficiency, typically reducing thermal resistance to 1 / 5 to 1 / 15 of that of natural air cooling.

[0064] The heat-resistant, high-strength, and high-conductivity aluminum alloy provided in this invention can be applied in the automotive field. For example, the heat-resistant, high-strength, and high-conductivity aluminum alloy of this invention can be used to manufacture motors for new energy vehicles.

[0065] IACS is an abbreviation for International Standard for Annealed Copper, which defines the standard for annealed copper at 20°C with a purity of 99.99% and a resistivity of 1.7241 × 10⁻⁶. -8 The conductivity of copper wire with an Ω·m is 100% IACS. Therefore, 55% IACS means that the conductivity of the tested material is 55% of that of standard annealed copper. This value indicates that the material has relatively good conductivity, but it is lower than that of pure copper. The higher the conductivity, the lower the resistivity of the material, and the less loss occurs during current transmission.

[0066] In the following embodiments and comparative examples of the present invention, the room temperature mechanical properties were tested in accordance with GB / T 228.1-2021, and the high temperature (180°C) mechanical properties were tested in accordance with GB / T 228.2-2015.

[0067] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0068] All raw materials used in the embodiments of this invention were obtained through commercial purchase.

[0069] It should be noted that all aspects not described in detail in this invention are conventional operating methods in the field and are not the focus of this invention. For example, specific methods such as preheating and forced air cooling are all accomplished using conventional methods.

[0070] The technical solution of the present invention will be further illustrated by the following embodiments.

[0071] Example 1

[0072] This embodiment provides a heat-resistant, high-strength, and high-conductivity aluminum alloy, which, by weight percentage, consists of the following components: Mg 0.55%, Si 0.88%, Mn 0.19%, Cu 0.059%, Zn 0.043%, Zr 0.055%, Er 0.0028%, Sc 0.0049%, Sr 0.012%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al.

[0073] The preparation method of the above-mentioned heat-resistant, high-strength, and high-conductivity aluminum alloy includes the following steps:

[0074] S1. Drying: Accurately weigh each raw material (pure Al, pure Si, pure Mg, pure Cu, pure Zn, Al-Er master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Mn master alloy and Al-Sr master alloy) according to weight percentage, and dry the prepared raw materials at 210℃.

[0075] S2. Melting: Pure Al is added to the melting furnace and heated to 710℃. After the pure Al melts, Al-Mn master alloy, pure Si, pure Cu, and pure Zn are added. After all the Al is melted, the temperature is raised to 810℃. Then Al-Sc master alloy, Al-Zr master alloy, and Al-Er master alloy are added. After stirring, the mixture is allowed to stand for 12 minutes. Then the temperature is lowered to 745℃, and pure Mg and Al-Sr master alloy are added. After complete melting, the mixture is allowed to stand for 12 minutes. Then refining and degassing are carried out. The temperature is lowered to 695℃, and the mixture is allowed to stand for 12 minutes again. After standing, the aluminum alloy melt is obtained.

[0076] S3. High-pressure casting: The aluminum alloy melt is subjected to compositional testing. After the composition is qualified, high-pressure casting is carried out at 695℃, the injection speed is 4.5m / s, the casting pressure is 90MPa, the mass ratio of mold release agent to water is 1:100, and the mold temperature is 210℃ to obtain aluminum alloy casting 1.

[0077] S4. First stage heat treatment (high temperature heat treatment): Place aluminum alloy casting 1 in a heat treatment furnace, heat it up with the furnace at a rate of 50℃ / h, hold it at 350℃ for 1h, and then take it out and quench it in water.

[0078] S5. Second-stage heat treatment (aging heat treatment): The aluminum alloy casting 1 that has undergone the first-stage heat treatment is placed in a heat treatment furnace and heated with the furnace at a rate of 50℃ / h. The holding temperature is 175℃ and the holding time is 2h. After the holding time is completed, the casting is taken out and forced to cool by air to obtain the heat-resistant, high-strength and high-conductivity aluminum alloy 1.

[0079] Example 2

[0080] This embodiment provides a heat-resistant, high-strength, and high-conductivity aluminum alloy, which, by weight percentage, consists of the following components: Mg 0.71%, Si 1.21%, Mn 0.21%, Cu 0.068%, Zn 0.057%, Zr 0.043%, Er 0.0043%, Sc 0.0094%, Sr 0.020%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al.

[0081] The preparation method of the above-mentioned heat-resistant, high-strength, and high-conductivity aluminum alloy includes the following steps:

[0082] S1. Drying: Accurately weigh each raw material (pure Al, pure Si, pure Mg, pure Cu, pure Zn, Al-Er master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Mn master alloy and Al-Sr master alloy) according to weight percentage, and dry the prepared raw materials at 210℃.

[0083] S2. Melting: Pure Al is added to the melting furnace and heated to 710℃. After the pure Al melts, Al-Mn master alloy, pure Si, pure Cu, and pure Zn are added. After all the Al is melted, the temperature is raised to 810℃. Then Al-Sc master alloy, Al-Zr master alloy, and Al-Er master alloy are added. After stirring, the mixture is allowed to stand for 12 minutes. Then the temperature is lowered to 745℃, and pure Mg and Al-Sr master alloy are added. After complete melting, the mixture is allowed to stand for 12 minutes. Then refining and degassing are carried out. The temperature is lowered to 695℃, and the mixture is allowed to stand for 12 minutes again. After standing, the aluminum alloy melt is obtained.

[0084] S3. High pressure casting: The aluminum alloy melt is subjected to compositional testing. After the composition is qualified, high pressure casting is carried out at 695℃, the injection speed is 4.5m / s, the casting pressure is 90MPa, the mass ratio of mold release agent to water is 1:100, and the mold temperature is 210℃ to obtain aluminum alloy casting 2.

[0085] S4. First stage heat treatment (high temperature heat treatment): Place the aluminum alloy casting 2 in a heat treatment furnace, heat it up with the furnace at a rate of 50℃ / h, hold it at 350℃ for 1h, and then take it out and quench it in water.

[0086] S5. Second-stage heat treatment (aging heat treatment): The aluminum alloy casting 2 that has undergone the first-stage heat treatment is placed in a heat treatment furnace and heated with the furnace at a rate of 50℃ / h. The holding temperature is 175℃ and the holding time is 2h. After the holding time is completed, the casting is removed and forced to cool by air to obtain the heat-resistant, high-strength, and high-conductivity aluminum alloy 2.

[0087] Example 3

[0088] This embodiment provides a heat-resistant, high-strength, and high-conductivity aluminum alloy, which, by weight percentage, consists of the following components: Mg 0.73%, Si 1.19%, Mn 0.24%, Cu 0.113%, Zn 0.133%, Zr 0.118%, Er 0.0039%, Sc 0.0088%, Sr 0.019%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al.

[0089] The preparation method of the above-mentioned heat-resistant, high-strength, and high-conductivity aluminum alloy includes the following steps:

[0090] S1. Drying: Accurately weigh each raw material (pure Al, pure Si, pure Mg, pure Cu, pure Zn, Al-Er master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Mn master alloy and Al-Sr master alloy) according to weight percentage, and dry the prepared raw materials at 210℃.

[0091] S2. Melting: Pure Al is added to the melting furnace and heated to 710℃. After the pure Al melts, Al-Mn master alloy, pure Si, pure Cu, and pure Zn are added. After all the Al is melted, the temperature is raised to 810℃. Then Al-Sc master alloy, Al-Zr master alloy, and Al-Er master alloy are added. After stirring, the mixture is allowed to stand for 12 minutes. Then the temperature is lowered to 745℃, and pure Mg and Al-Sr master alloy are added. After complete melting, the mixture is allowed to stand for 12 minutes. Then refining and degassing are carried out. The temperature is lowered to 695℃, and the mixture is allowed to stand for 12 minutes again. After standing, the aluminum alloy melt is obtained.

[0092] S3. High-pressure casting: The aluminum alloy melt is subjected to compositional testing. After the composition is qualified, high-pressure casting is carried out at 695℃, the injection speed is 4.5m / s, the casting pressure is 90MPa, the mass ratio of mold release agent to water is 1:100, and the mold temperature is 210℃ to obtain aluminum alloy casting 3.

[0093] S4. First stage heat treatment (high temperature heat treatment): Place the aluminum alloy casting 3 in a heat treatment furnace, heat it up with the furnace at a rate of 50℃ / h, hold it at 350℃ for 1h, and then take it out and quench it in water.

[0094] S5. Second-stage heat treatment (aging heat treatment): The aluminum alloy casting 3 that has undergone the first-stage heat treatment is placed in a heat treatment furnace and heated with the furnace at a rate of 50℃ / h. The holding temperature is 175℃ and the holding time is 2h. After the holding time is completed, the casting is removed and forced to cool by air to obtain the heat-resistant, high-strength, and high-conductivity aluminum alloy 3.

[0095] Example 4

[0096] This embodiment provides a heat-resistant, high-strength, and high-conductivity aluminum alloy, which, by weight percentage, consists of the following components: Mg 0.79%, Si 1.28%, Mn 0.28%, Cu 0.138%, Zn 0.119%, Zr 0.125%, Er 0.0041%, Sc 0.025%, Sr 0.021%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al.

[0097] The preparation method of the above-mentioned heat-resistant, high-strength, and high-conductivity aluminum alloy includes the following steps:

[0098] S1. Drying: Accurately weigh each raw material (pure Al, pure Si, pure Mg, pure Cu, pure Zn, Al-Er master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Mn master alloy and Al-Sr master alloy) according to weight percentage, and dry the prepared raw materials at 210℃.

[0099] S2. Melting: Pure Al is added to the melting furnace and heated to 710℃. After the pure Al melts, Al-Mn master alloy, pure Si, pure Cu, and pure Zn are added. After all the Al is melted, the temperature is raised to 810℃. Then Al-Sc master alloy, Al-Zr master alloy, and Al-Er master alloy are added. After stirring, the mixture is allowed to stand for 12 minutes. Then the temperature is lowered to 745℃, and pure Mg and Al-Sr master alloy are added. After complete melting, the mixture is allowed to stand for 12 minutes. Then refining and degassing are carried out. The temperature is lowered to 695℃, and the mixture is allowed to stand for 12 minutes again. After standing, the aluminum alloy melt is obtained.

[0100] S3. High pressure casting: The aluminum alloy melt is subjected to compositional testing. After the composition is qualified, high pressure casting is carried out at 695℃, the injection speed is 4.5m / s, the casting pressure is 90MPa, the mass ratio of mold release agent to water is 1:100, and the mold temperature is 210℃ to obtain aluminum alloy casting 4.

[0101] S4. First stage heat treatment (high temperature heat treatment): Place the aluminum alloy casting 4 in a heat treatment furnace, heat it up with the furnace at a rate of 50℃ / h, hold it at 350℃ for 1h, and then take it out and quench it in water.

[0102] S5. Second-stage heat treatment (aging heat treatment): The aluminum alloy casting 4 that has undergone the first-stage heat treatment is placed in a heat treatment furnace and heated with the furnace at a rate of 50℃ / h. The holding temperature is 175℃ and the holding time is 2h. After the holding is completed, the casting is taken out and forced to cool by air to obtain the heat-resistant, high-strength and high-conductivity aluminum alloy 4.

[0103] Example 5

[0104] This embodiment provides a heat-resistant, high-strength, and high-conductivity aluminum alloy, which, by weight percentage, consists of the following components: Mg 0.8%, Si 0.6%, Mn 0.01%, Cu 0.001%, Zn 0.15%, Zr 0.001%, Er 0.0001%, Sc 0.0001%, Sr 0.001%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al.

[0105] The preparation method of the above-mentioned heat-resistant, high-strength, and high-conductivity aluminum alloy includes the following steps:

[0106] S1. Drying: Accurately weigh each raw material (pure Al, pure Si, pure Mg, pure Cu, pure Zn, Al-Er master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Mn master alloy and Al-Sr master alloy) according to weight percentage, and preheat the prepared raw materials at 200℃.

[0107] S2. Melting: Pure Al is added to the melting furnace and heated to 700℃. After the pure Al melts, Al-Mn master alloy, pure Si, pure Cu, and pure Zn are added. After all the Al is melted, the temperature is raised to 800℃. Then Al-Sc master alloy, Al-Zr master alloy, and Al-Er master alloy are added. After stirring, the mixture is allowed to stand for 10 minutes. Then the temperature is lowered to 740℃, and pure Mg and Al-Sr master alloy are added. After complete melting, the mixture is allowed to stand for 10 minutes. Then refining and degassing are carried out. The temperature is lowered to 690℃, and the mixture is allowed to stand for 10 minutes again. After standing, the aluminum alloy melt is obtained.

[0108] S3. High pressure casting: The aluminum alloy melt is subjected to compositional testing. After the composition is qualified, high pressure casting is carried out at 690℃, the injection speed is 4.5m / s, the casting pressure is 80MPa, the mass ratio of mold release agent to water is 1:100, the mold temperature is 210℃, and aluminum alloy casting 5 is obtained.

[0109] S4. First stage heat treatment (high temperature heat treatment): Place the aluminum alloy casting 5 in a heat treatment furnace, heat it up with the furnace at a rate of 50℃ / h, hold it at 350℃ for 1h, and then take it out and quench it in water.

[0110] S5. Second-stage heat treatment (aging heat treatment): The aluminum alloy casting 5 that has undergone the first-stage heat treatment is placed in a heat treatment furnace and heated with the furnace at a rate of 50℃ / h. The holding temperature is 175℃ and the holding time is 2h. After the holding time is completed, the casting is removed and forced to cool by air to obtain the heat-resistant, high-strength, and high-conductivity aluminum alloy 5.

[0111] Example 6

[0112] This embodiment provides a heat-resistant, high-strength, and high-conductivity aluminum alloy, which, by weight percentage, consists of the following components: Mg 0.4%, Si 1.3%, Mn 0.3%, Cu 0.15%, Zn 0.002%, Zr 0.15%, Er 0.1%, Sc 0.05%, Sr 0.05%, Fe < 0.15%, other impurities < 0.1%, and the balance being Al.

[0113] The preparation method of the above-mentioned heat-resistant, high-strength, and high-conductivity aluminum alloy includes the following steps:

[0114] S1. Drying: Accurately weigh each raw material (pure Al, pure Si, pure Mg, pure Cu, pure Zn, Al-Er master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Mn master alloy and Al-Sr master alloy) according to weight percentage, and preheat the prepared raw materials at 220℃.

[0115] S2. Melting: Pure Al is added to the melting furnace and heated to 720℃. After the pure Al melts, Al-Mn master alloy, pure Si, pure Cu, and pure Zn are added. After all the Al is melted, the temperature is raised to 820℃. Then Al-Sc master alloy, Al-Zr master alloy, and Al-Er master alloy are added. After stirring, the mixture is allowed to stand for 15 minutes. Then the temperature is lowered to 750℃, and pure Mg and Al-Sr master alloy are added. After complete melting, the mixture is allowed to stand for 15 minutes. Then refining and degassing are carried out. The temperature is lowered to 705℃, and the mixture is allowed to stand for 15 minutes again. After standing, the aluminum alloy melt is obtained.

[0116] S3. High pressure casting: The aluminum alloy melt is subjected to compositional testing. After the composition is qualified, high pressure casting is carried out at 705℃, the injection speed is 4.5m / s, the casting pressure is 90MPa, the mass ratio of mold release agent to water is 1:100, the mold temperature is 210℃, and aluminum alloy casting 6 is obtained.

[0117] S4. First stage heat treatment (high temperature heat treatment): Place the aluminum alloy casting 6 in a heat treatment furnace, heat it up with the furnace at a rate of 50℃ / h, hold it at 350℃ for 1h, and then take it out and quench it in water.

[0118] S5. Second-stage heat treatment (aging heat treatment): The aluminum alloy casting 6 that has undergone the first-stage heat treatment is placed in a heat treatment furnace and heated with the furnace at a rate of 50℃ / h. The holding temperature is 175℃ and the holding time is 2h. After the holding time is completed, the casting is removed and forced to cool by air to obtain the heat-resistant, high-strength, and high-conductivity aluminum alloy 6.

[0119] Figure 1 This is a low-magnification metallographic image (100 μm) of the heat-resistant, high-strength, and high-conductivity aluminum alloy in Example 1. Figure 2 The image shows a high-magnification metallographic image (20 μm) of the heat-resistant, high-strength, and high-conductivity aluminum alloy in Example 1. It can be seen that the heat-resistant, high-strength, and high-conductivity aluminum alloy obtained after heat treatment has dot-like precipitates within the grains.

[0120] Comparative Example 1

[0121] The material used in Comparative Example 1 was aluminum ingot, in which the weight percentage of Al was >99.5 wt.%, and the remainder was unavoidable impurity elements.

[0122] The steps for preparing aluminum alloys using the above-mentioned aluminum ingots are as follows:

[0123] S1. Drying: Dry the aluminum ingots at 200℃;

[0124] S2. Melting: Heat to 700℃ until the aluminum ingot is completely melted, then let stand for 10 minutes; then refine and degas (process as in Example 1), then let stand for 10 minutes again; after standing, the melt is obtained.

[0125] S3. High-pressure casting: High-pressure casting is carried out at 690℃, with an injection speed of 4.5m / s, a casting pressure of 90MPa, a release agent to water mass ratio of 1:100, and a mold temperature of 210℃, to obtain aluminum alloy casting 7.

[0126] The spectral results of the aluminum alloy castings in Examples 1-6 and Comparative Example 1 are shown in Table 1.

[0127] Table 1. Spectral results of aluminum alloy castings in Examples 1-6 and Comparative Example 1 (unit: weight percentage, wt.%)

[0128]

[0129]

[0130] Note: "Bal." in Table 1 indicates a margin.

[0131] Sampling and testing of mechanical properties at room temperature and high temperature (180℃) were carried out in accordance with GB / T 228.1-2021 and GB / T 228.2-2015. The mechanical properties and conductivity results of aluminum alloy castings and heat-resistant high-strength high-conductivity aluminum alloys in Examples 1-6, and aluminum alloy castings in Comparative Example 1 are shown in Table 2.

[0132] Table 2. Mechanical Properties and Electrical Conductivity

[0133]

[0134]

[0135] As can be seen from the data in Table 2, the aluminum alloy material prepared according to the method of this invention can simultaneously possess high yield strength, tensile strength, and electrical conductivity, and exhibits high performance when serving in high-temperature environments. The die-cast pure aluminum used in Comparative Example 1 has the best electrical conductivity, but its strength is the lowest, which cannot meet practical application requirements. Comparing aluminum alloy castings 1-6 with heat-resistant, high-strength, and high-conductivity aluminum alloys 1-6 shows that a short-time heat treatment process can further improve mechanical properties while minimizing elongation loss. This invention, through a short-time heat treatment process, allows the coarse second phase formed during die-casting solidification to re-dissolve into the matrix and disperse, optimizing phase distribution and thus significantly improving the mechanical properties of the aluminum alloy while minimizing the loss of electrical conductivity. Comparing Examples 1-4 shows that increasing the Mg and Si content can improve yield strength and tensile strength, but will result in a loss of electrical conductivity and elongation; increasing the Cu and Sc content can improve yield strength and tensile strength, but will impair elongation, with a smaller impact on electrical conductivity, and compared to increasing the Mg and Si content, it exhibits better high-temperature mechanical properties.

[0136] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A heat-resistant, high-strength, and high-conductivity aluminum alloy, characterized in that, The composition, by weight percentage, is as follows: Mg 0.4%-0.8%, Si 0.6%-1.3%, Mn 0.01%-0.3%, Cu 0.001%-0.15%, Zn 0.001%-0.15%, Zr 0.001%-0.15%, Er 0.0001%-0.1%, Sc 0.0001%-0.05%, Sr 0.001%-0.05%, Fe <0.15%, other impurities <0.1%, and the balance being Al.

2. The heat-resistant, high-strength, and high-conductivity aluminum alloy according to claim 1, characterized in that, The composition, by weight percentage, is as follows: Mg 0.4%-0.6%, Si 0.6%-0.9%, Mn 0.01%-0.3%, Cu 0.001%-0.1%, Zn 0.001%-0.1%, Zr 0.001%-0.1%, Er 0.0001%-0.005%, Sc 0.0001%-0.01%, Sr 0.001%-0.05%, Fe <0.15%, other impurities <0.1%, and the balance being Al.

3. The heat-resistant, high-strength, and high-conductivity aluminum alloy according to claim 1, characterized in that, The composition, by weight percentage, is as follows: Mg 0.6%-0.8%, Si 0.9%-1.3%, Mn 0.01%-0.3%, Cu 0.001%-0.1%, Zn 0.001%-0.1%, Zr 0.001%-0.1%, Er 0.0001%-0.005%, Sc 0.0001%-0.01%, Sr 0.001%-0.05%, Fe <0.15%, other impurities <0.1%, and the balance being Al.

4. The heat-resistant, high-strength, and high-conductivity aluminum alloy according to claim 1, characterized in that, The composition, by weight percentage, is as follows: Mg 0.6%-0.8%, Si 0.9%-1.3%, Mn 0.01%-0.3%, Cu 0.001%-0.15%, Zn 0.1%-0.15%, Zr 0.1%-0.15%, Er 0.005%-0.1%, Sc 0.01%-0.05%, Sr 0.001%-0.05%, Fe <0.15%, other impurities <0.1%, and the balance being Al.

5. A method for preparing a heat-resistant, high-strength, and high-conductivity aluminum alloy according to any one of claims 1-4, characterized in that, Includes the following steps: Each raw material is accurately weighed by weight percentage and then dried. The raw materials are selected from pure Al, pure Si, pure Mg, pure Cu, pure Zn, Al-Er master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Mn master alloy and Al-Sr master alloy. The pure Al is added to the melting device and heated to a first temperature until the pure Al melts. After the pure Al is melted, the Al-Mn master alloy, pure Si, pure Cu and pure Zn are added, and after melting, the temperature is raised to a second temperature; After heating to the second temperature, the Al-Sc master alloy, Al-Zr master alloy and Al-Er master alloy are added, stirred and allowed to stand. Then the temperature is lowered to the third temperature, the pure Mg and Al-Sr master alloy are added, completely melted and allowed to stand. Then refining and degassing are carried out. After that, the temperature is lowered to the fourth temperature and allowed to stand again to obtain aluminum alloy melt. The aluminum alloy melt is subjected to high-pressure casting to obtain a casting. The pressure of high-pressure casting is 80-90 MPa. The casting is subjected to two-stage heat treatment to obtain the heat-resistant, high-strength, and high-conductivity aluminum alloy.

6. The preparation method according to claim 5, characterized in that, The preheating temperature is 200-220℃.

7. The preparation method according to claim 5, characterized in that, The first temperature is 700℃-720℃; And / or, the second temperature is 800-820℃; And / or, the third temperature is 740-750°C; And / or, the fourth temperature is 690-705°C.

8. The preparation method according to claim 5, characterized in that, During the high-pressure casting process, the injection speed is 4.5 m / s, and the mass ratio of release agent to water is 1:

100.

9. The preparation method according to claim 5, characterized in that, The heating rate for the first stage of heat treatment is 50℃ / h, the holding temperature is 350℃, and the holding time is 1h. The second-stage heat treatment has a heating rate of 50℃ / h, a holding temperature of 175℃, and a holding time of 2h.

10. The application of a heat-resistant, high-strength, and high-conductivity aluminum alloy as described in any one of claims 1-4 in the automotive field.

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