High-temperature-resistant aluminum alloy, preparation method and application thereof

Abstract

This invention belongs to the field of aluminum alloy materials, specifically relating to a high-temperature resistant aluminum alloy, its preparation method, and its applications. The alloy comprises the following components by mass fraction: Cu 2.0-4.0%, Si 8.5-11.5%, Zn 0.5-1.5%, Mn 0.3-0.6%, Mg 0.3-0.8%, Fe≤0.45%, Sr 0.010-0.045%, Cr 0.3-1.0%, Ti 0.06-0.25%, (La+Ce) 0.05-0.6%, with the balance being Al and impurities; wherein the total impurity content is not greater than 0.25%, the Si / Cu mass fraction ratio is 4-5.5, the Cu / Mg mass fraction ratio is 4-7, the sum of the mass fractions of Cu+Zn+Mg is 3-5, and the Cu / Cr mass fraction ratio is 3-11. The aluminum alloy components disclosed in this invention, after being formed and subjected to T5 heat treatment, exhibit tensile strength of 350-400 MPa, yield strength of 240-300 MPa, elongation after fracture of 3.0-5.0%, and high-temperature strength exceeding 230 MPa in a working environment at 250°C, which is superior to the performance of conventional high-strength and tough aluminum alloy formed components.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy materials, specifically relating to a high-temperature resistant aluminum alloy, its preparation method, and its application. Background Technology

[0002] High-strength, wear-resistant materials are widely needed in the automotive industry. Looking at the development trends of automotive technology, the demand for lightweight, high-strength, high-wear-resistant, and high-toughness materials will further increase. For example, turbocharging technology can increase engine power by more than 30% compared to traditional naturally aspirated engines. However, the cylinder block operating temperature is generally above 250℃, which is a high-pressure, high-temperature, and high-flow-rate working environment (affecting stress and stress changes). Therefore, it places high demands on the strength and toughness of the materials. Currently, cylinder blocks are mostly made of aluminum alloy, whose maximum tensile strength is generally below 350MPa, which to some extent limits the improvement of engine power.

[0003] Currently, the commonly used aluminum alloy material for cylinder blocks in European automobiles is AlSi9Cu3Fe. This type of alloy belongs to eutectic die-cast aluminum alloy. The overall product has low hardness and strength, with tensile strength of (280-330) MPa, yield strength of (140-215) MPa, elongation after fracture of (1.5-2.5)%, and high-temperature strength of only (110-150) MPa at 250℃. It also lacks high-temperature strengthening elements, resulting in poor high-temperature performance and failing to meet the technical requirements for high-temperature strength of new engines.

[0004] Chinese patent CN110724861B describes an aluminum alloy material developed for engine cylinder heads. It introduces elements such as Zr and Ni to improve the material's strength, while introducing scandium to suppress the damage of Zr and Ni to the material's toughness. However, it is difficult for this type of material to avoid the "poisoning" phenomenon caused by Zr and Ni to the aluminum alloy, and the use of scandium greatly increases the manufacturing cost.

[0005] This shows that although significant progress has been made in the development of heat-treatable high-strength and high-toughness aluminum alloys in recent years, their performance is gradually approaching its limits, and the contradiction between strength and toughness, as well as between them and formability, needs to be overcome. Therefore, a new generation of heat-treatable high-strength, high-toughness, and wear-resistant materials urgently needs to be developed to meet the needs of automotive parts such as cylinder blocks. Summary of the Invention

[0006] To overcome the problems and shortcomings of existing aluminum alloy materials for cylinder blocks, this invention further improves the strength and toughness of the alloy by designing the composition, component ratio, and smelting technology of the aluminum alloy, so as to meet the performance requirements of high-strength and wear-resistant automotive parts.

[0007] Lightweighting is a crucial direction in automotive development, leading to the extensive use of aluminum alloys in automobile manufacturing, with engine blocks being a prime example. The engine block significantly determines a vehicle's output power and directly impacts its overall performance. However, the high-pressure, high-temperature, and high-flow-rate environment of the engine block places extremely stringent demands on the materials used. This creates a conflict with the lightweighting principles of aluminum alloys, meaning that the performance characteristics of aluminum alloys, to some extent, constrain the development of engine blocks.

[0008] Improving the performance of aluminum alloys mainly focuses on composition design and refining methods, as discussed in the background section. Those skilled in the art have a basic understanding of the positive and negative effects of various elements on the properties of the finished product during aluminum alloy preparation. For example, elements such as Zr can form intermetallic compounds during smelting, which is beneficial for grain refinement, but may also cause Si poisoning; Cu can improve the fluidity of the material, but at the same time, it can impair the material's elongation properties and reduce corrosion resistance; Mg can also improve the strength of the material, but it also increases the material's susceptibility to hot cracking. Therefore, current mainstream improvements to aluminum alloy performance focus on selecting appropriate elements and designing their proportions based on the application conditions.

[0009] The strength of Al-Si alloys largely stems from silicon (Si), which enhances fluidity and strength. However, content exceeding 11.5% leads to the formation of primary silicon, which can fracture the aluminum matrix and increase brittleness. Current technologies address this by introducing elements like Ni and Zr to form intermetallic compounds that immobilize some Si and limit grain growth. However, Ni and Zr readily react with α-Al, resulting in poisoning and reducing strength instead of strengthening. To address this, recent technologies introduce TCB as a modifier phase, shortening nucleation and crystallization time and refining the grain size. However, mechanical performance tests show that the balance between strength and toughness is insufficient for next-generation turbochargers.

[0010] During the research and development process, the inventors of this application discovered that, based on the introduction of TCB, by rationally designing the Si / Cu mass fraction ratio, Cu / Mg mass fraction ratio, the sum range of the Cu+Mg+Zn mass fraction ratio, and the Cr content, and utilizing the different diffusion rates of Cr, different crystal forms of precipitates can be formed, resulting in a gradient and regularly distributed intermetallic compound, which is inherited into the aging stage. This can significantly improve the tensile strength and yield strength of aluminum alloys, with the tensile strength increasing to over 350 MPa and the yield strength increasing to over 240 MPa, while the elongation can still be maintained at 3.0-5.0%. The toughness and wear resistance are also greatly improved, making it very suitable for manufacturing automotive parts such as cylinder blocks.

[0011] Based on the above findings, the inventors of this invention, through extensive creative thinking and experimentation, solidified the selection and proportion of elements in aluminum alloys and conducted multiple verifications, resulting in a significant improvement in performance compared to existing technologies.

[0012] In summary, this invention provides a high-temperature resistant aluminum alloy, its preparation method, and its applications, specifically including the following:

[0013] A high-temperature resistant aluminum alloy comprises the following components in the indicated mass fractions: Cu 2.0-4.0%, Si 8.5-11.5%, Zn 0.5-1.5%, Mn 0.3-0.6%, Mg 0.3-0.8%, Fe≤0.45%, Sr 0.010-0.045%, Cr 0.3-1.0%, Ti 0.06-0.25%, (La+Ce) 0.05-0.6%, with the balance being Al and impurities; wherein the total impurity content is not greater than 0.25%, the Si / Cu mass fraction ratio is 4-5.5, the Cu / Mg mass fraction ratio is 4-7, the sum of the mass fractions of Cu+Zn+Mg is 3-5, and the Cu / Cr mass fraction ratio is 3-11.

[0014] Preferably, the high-temperature resistant aluminum alloy does not contain Ni, Zr, or Mo.

[0015] Preferably, the high-temperature resistant aluminum alloy, after T5 heat treatment, has a tensile strength ≥350MPa, a yield strength ≥240MPa, and an elongation after fracture of 3.0-5.0%.

[0016] Preferably, the high-temperature resistant aluminum alloy, after undergoing T5 heat treatment, has a tensile strength ≥230MPa at 250℃.

[0017] A method for preparing the aforementioned high-temperature resistant aluminum alloy includes the following steps:

[0018] (1) Prepare the ingredients according to the proportions, add the raw materials to the melting equipment, heat and melt the raw materials and stir evenly to obtain the alloy melt;

[0019] (2) Refine the alloy melt to remove gas and impurities;

[0020] (3) The refined alloy melt is shaped to obtain aluminum alloy components;

[0021] (4) The aluminum alloy component is subjected to T5 heat treatment to obtain the high temperature resistant aluminum alloy.

[0022] Preferably, step (1) further includes preheating and drying the raw material at a temperature of 100-450°C; the melting temperature in step (1) is 700-800°C; the stirring process in step (1) is: stirring once every 1.5-2.5 hours, and each stirring time is 2-15 minutes.

[0023] Preferably, the order in which the raw materials are added to the smelting equipment in step (1) is as follows: First, the Al-Si alloy ingot is added to the smelting furnace for melting. After it is completely melted, pure metals or intermediate alloys of Cu, Mg, and Zn are added. After they are completely melted, Al-Cr and TCB intermediate alloys are added. After they are completely melted, Al-RE and Al-Sr intermediate alloys are added. TCB is a complex composed of B-doped TiC and C-doped TiB2, and Al-RE represents an intermediate alloy of aluminum and rare earth elements.

[0024] Preferably, the refining process in step (2) is as follows: nitrogen or argon is introduced into the alloy melt as a protective gas, and RJ-01 refining agent is added; the amount of protective gas introduced is 0.05-6 L / min, the refining time is 10-30 min, and the amount of refining agent added is 0.1-0.5% of the mass of the alloy melt.

[0025] Preferably, the equipment used for forming in step (3) is a high-pressure die casting machine or a liquid forging machine, wherein the injection pressure of the high-pressure die casting machine and the liquid forging machine is 50-100MPa.

[0026] Preferably, the T5 heat treatment process in step (4) is as follows: artificial aging is performed, and the temperature is raised to 180-210℃ within 45 minutes at a rate of 5-8℃ / min. Then, the temperature is gradually raised to 220-250℃, and the holding time is 2-5 hours. The furnace is then cooled, preferably to room temperature.

[0027] An engine that uses the aforementioned high-temperature resistant aluminum alloy.

[0028] An automobile that uses the aforementioned high-temperature resistant aluminum alloy.

[0029] The beneficial effects of this invention are:

[0030] (1) The aluminum alloy disclosed in this invention introduces TCB seed crystals. By rationally designing the composition ratio of the alloy, the poisoning phenomenon can be effectively avoided. In conjunction with designing the range of Si / Cu, Cu / Mg, Cu+Mg+Zn and controlling the design range of elements such as Cr, the source of "poisoning" is eliminated, and the dual effects of fine grain strengthening and interface coherent strengthening are achieved, fundamentally solving the above problems.

[0031] (2) In the aluminum alloy disclosed in this invention, strontium is used to refine the eutectic silicon, and Ti element is added to achieve simultaneous refinement and modification. Both the grains and the eutectic silicon are significantly refined. At the same time, the solid solution strengthening brought by Cu, Mg and Zn elements and the dispersion strengthening brought by the precipitation of Cr-rich nano-sized particles during artificial aging give the alloy excellent high-temperature mechanical properties. In addition, the addition of trace amounts of rare earth elements gives the alloy good corrosion resistance and high-temperature fatigue resistance.

[0032] (3) The present invention adopts a eutectic Al-Si-Cu-Mg-Mn aluminum alloy system, which is different from the existing AlSi9Cu3Fe aluminum alloy. It does not have poor high-temperature strength and hardness, and is suitable for high pressure casting and liquid die forging (extrusion casting) to produce parts with high requirements for high strength and high toughness.

[0033] (4) The aluminum alloy components disclosed in this invention are subjected to T5 heat treatment after forming. The tensile strength of the aluminum alloy components is 350-400MPa, the yield strength is 240-300MPa, the elongation after fracture is 3.0-5.0%, and the high temperature strength in the working environment at 250℃ reaches more than 230MPa, which is higher than the performance of conventional high strength and toughness aluminum alloy formed components. Attached Figure Description

[0034] Figure 1 This is a representative microstructure of the aluminum alloy after gravity casting and T5 heat treatment according to the present invention.

[0035] Figure 2 This is a representative microstructure after tensile fracture of the aluminum alloy after gravity casting and T5 heat treatment according to the present invention. Detailed Implementation

[0036] To facilitate a better understanding of this invention, the technical solutions described herein are further illustrated through the following practical examples. These examples fall within the scope of protection of this invention, but do not limit the scope of protection. Furthermore, the complete content of the structures illustrated in the following embodiments is not limited to those necessary for the solutions of the invention as described in the claims.

[0037] A high-temperature resistant aluminum alloy comprises the following components in the indicated mass fractions: Cu 2.0-4.0%, Si 8.5-11.5%, Zn 0.5-1.5%, Mn 0.3-0.6%, Mg 0.3-0.8%, Fe ≤0.45%, Sr 0.010-0.045%, Cr 0.3-1.0%, Ti 0.06-0.25%, (La+Ce) 0.05-0.6%, with the balance being Al and impurities; wherein the total impurity content is not greater than 0.25%, the Si / Cu mass fraction ratio is 4-5.5, the Cu / Mg mass fraction ratio is 4-7, the sum of the mass fractions of Cu+Zn+Mg is 3-5%, and the Cu / Cr mass fraction ratio is 3-11. The high-temperature resistant aluminum alloy does not contain Ni, Zr, or Mo. The high-temperature resistant aluminum alloy, after T5 heat treatment, has a tensile strength ≥350MPa, a yield strength ≥240MPa, and an elongation after fracture of 3.0-5.0%. After T5 heat treatment at 250℃, the high-temperature resistant aluminum alloy has a tensile strength ≥230MPa.

[0038] Specifically, in the high-temperature resistant aluminum alloy: the Cu content can be 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, etc.; the Si content can be 8.6%, 8.8%, 9.0%, 9.2%, 9.4%, 9.6%, 9.8%, 10.0%, 10.2%, 10.4%, 10.6%, 10.8%, 11.0%, 11.2%, 11.4%, etc.; the Zn content can be 0.6%, 0.8%, 1.0%, 1. The content of Mn can be 0.4%, 0.42%, 0.45%, 0.5%, 0.55%, 0.58%, etc.; the content of Mg can be 0.35%, 0.4%, 0.45%, 0.5%, 0.6%, 0.7%, 0.75%, etc.; the content of Fe can be 0, ≤0.1%, ≤0.15%, ≤0.2%, ≤0.25%, ≤0.3%, ≤0.35%, ≤0.4%, etc.; the content of Sr can be 0.015%, 0.02%, 0.025%, 0.03%, etc. The Si / Cu mass fraction can be 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, etc.; the Ti content can be 0.08%, 0.10%, 0.12%, 0.15%, 0.18%, 0.20%, 0.22%, 0.24%, etc.; the total La and Ce content can be 0.06%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.55%, etc.; the Si / Cu mass fraction ratio can be 4.2%. The mass fractions of Cu, Zn, and Mg can be 4.4, 4.6, 4.8, 5.0, 5.2, 5.4, etc.; the Cu / Mg mass fraction ratio can be 4.2, 4.4, 4.6, 4.8, 5.0, 5.2, 5.5, 5.8, 6.0, 6.2, 6.5, 6.8, etc.; the sum of the mass fractions of Cu, Zn, and Mg can be 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, 4.6%, 4.8%, etc.; and the Cu / Cr mass fraction ratio can be 4, 5, 6, 7, 8, 9, 10, etc.

[0039] A method for preparing the aforementioned high-temperature resistant aluminum alloy includes the following steps:

[0040] (1) Prepare the raw materials according to the component ratio, and preheat and dry each raw material at a temperature of 100-450℃ (e.g., 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, etc.); then set the melting temperature of the melting furnace to 700-800℃ (e.g., 720℃, 740℃, 760℃, 780℃, etc.), first add the Al-Si alloy ingot to the melting furnace to melt, and after it is completely melted, add Cu, Mg, and Zn elements. Pure metals or master alloys are completely melted, and then Al-Cr and TCB master alloys are added. After they are completely melted, Al-RE and Al-Sr master alloys are added. During the melting process, the mixture is stirred once every 1.5-2.5 hours (e.g., 1.8 hours, 2.0 hours, 2.2 hours, 2.4 hours, etc.) for 2-15 minutes each time (e.g., 4 minutes, 6 minutes, 8 minutes, 10 minutes, 12 minutes, 14 minutes, etc.) until it is uniformly stirred to obtain the alloy melt.

[0041] (2) The alloy melt is refined to remove gas and impurities. The refining process is as follows: nitrogen or argon is introduced into the alloy melt as a protective gas, and RJ-01 refining agent is added. The amount of protective gas introduced is 0.05-6 L / min (e.g., 0.1 L / min, 0.5 L / min, 1 L / min, 2 L / min, 3 L / min, 4 L / min, 5 L / min, etc.), the refining time is 10-30 min (e.g., 12 min, 15 min, 18 min, 20 min, 25 min, 28 min, etc.), and the amount of refining agent added is 0.1-0.5% of the mass of the alloy melt (e.g., 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, etc.).

[0042] (3) Use a high-pressure die casting machine or a liquid forging machine to form the refined alloy melt. Set the injection pressure of the high-pressure die casting machine or the liquid forging machine to 50-100MPa (e.g., 55MPa, 60MPa, 70MPa, 80MPa, 90MPa, 95MPa, etc.) to obtain aluminum alloy components.

[0043] (4) The aluminum alloy component is subjected to T5 heat treatment. The T5 heat treatment process is as follows: artificial aging is performed within 45 minutes (e.g., 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.) to raise the temperature to 180-210℃ (e.g., 185℃, 190℃, 195℃, 200℃, 205℃, etc.), the heating rate is 5-8℃ / min (e.g., 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, etc.), and then gradually raised to 220-250℃ (e.g., 230℃, 235℃, 240℃, 245℃, etc.), the holding time is 2-5 hours (e.g., 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, etc.), and then cooled to room temperature with the furnace to obtain the high-temperature resistant aluminum alloy.

[0044] The high-temperature resistant aluminum alloy material disclosed in this invention can be used to manufacture gasoline engine cylinder blocks, gear chambers or intercooler end caps, and applied in automobiles.

[0045] The present invention will be further described in detail below with reference to specific embodiments.

[0046] Example 1

[0047] A method for preparing a high-temperature resistant aluminum alloy, wherein the alloy composition and mass percentages are: Cu 2.2%, Si 8.8%, Mn 0.4%, Mg 0.45%, Fe ≤0.45%, Zn 0.6%, Sr 0.025%, (La+Ce) 0.15%, Ti 0.15%, Cr 0.45%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%; the Si / Cu ratio is approximately 4.0, the Cu / Mg ratio is approximately 4.8, the Cu / Cr ratio is approximately 4.89, and the sum of the mass fractions of Cu+Mg+Zn is 3.25%; no Ni, Mo, or Zr is added to the alloy. The method includes the following steps:

[0048] (1) Prepare the raw materials according to the proportions and preheat and dry each raw material at 200℃. Then set the melting temperature of the smelting furnace to 720℃. First, add the Al-Si alloy ingot to the smelting furnace to melt. After it is completely melted, add pure metals or intermediate alloys of Cu, Mg and Zn elements. After they are completely melted, add Al-Cr and TCB intermediate alloys. After they are completely melted, add Al-RE and Al-Sr intermediate alloys. Stir the molten raw materials for 4 minutes every 2 hours. After stirring evenly, the alloy melt is obtained.

[0049] (2) The alloy melt is refined to complete degassing and impurity removal. The refining process is as follows: nitrogen or argon is introduced into the alloy melt as a protective gas, and RJ-01 refining agent is added; the amount of protective gas introduced is 1L / min, the refining time is 12min, and the amount of refining agent added is 0.2% of the mass of the alloy melt.

[0050] (3) Use a high-pressure die casting machine or a liquid forging machine to form the refined alloy melt. Set the injection pressure of the high-pressure die casting machine or the liquid forging machine to 100MPa to obtain aluminum alloy components.

[0051] (4) The aluminum alloy component is subjected to T5 heat treatment. The T5 heat treatment process is as follows: artificial aging is performed by heating to 180-210°C within 45 minutes, with a temperature increase of 5-8°C per minute, and then gradually heating to 220-250°C. The holding time is 2-5 hours, and the furnace is cooled to room temperature to obtain the high temperature resistant aluminum alloy.

[0052] (5) The high-temperature resistant aluminum alloy is made into a standard-sized sample and its mechanical properties are tested.

[0053] The main mechanical properties of the standard sample prepared in this embodiment are as follows: tensile strength 355 MPa, yield strength 262 MPa, and elongation after fracture 4.65%.

[0054] Example 2

[0055] A method for preparing a high-temperature resistant aluminum alloy, wherein the alloy composition and mass percentages are: Cu 2.35%, Si 9.5%, Mn 0.35%, Mg 0.55%, Fe ≤ 0.45%, Zn 0.88%, Sr 0.018%, (La+Ce) 0.15%, Ti 0.2%, Cr 0.54%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%; the Si / Cu ratio is approximately 4.04, the Cu / Mg ratio is approximately 4.27, the Cu / Cr ratio is approximately 4.35, and the sum of the mass fractions of Cu+Mg+Zn is 3.78%; no Ni, Mo, or Zr is added to the alloy. The method includes the following steps:

[0056] (1) Prepare the raw materials according to the proportions and preheat and dry each raw material at 350℃. Then set the melting temperature of the smelting furnace to 760℃. First, add the Al-Si alloy ingot to the smelting furnace to melt. After it is completely melted, add pure metals or intermediate alloys of Cu, Mg and Zn elements. After they are completely melted, add Al-Cr and TCB intermediate alloys. After they are completely melted, add Al-RE and Al-Sr intermediate alloys. Stir the molten raw materials for 8 minutes every 2.2 hours. After stirring evenly, the alloy melt is obtained.

[0057] (2) The alloy melt is refined to complete degassing and impurity removal. The refining process is as follows: nitrogen or argon is introduced into the alloy melt as a protective gas, and RJ-01 refining agent is added; the amount of protective gas introduced is 3L / min, the refining time is 15min, and the amount of refining agent added is 0.2% of the mass of the alloy melt.

[0058] (3) Use a high-pressure die casting machine or a liquid forging machine to form the refined alloy melt. Set the injection pressure of the high-pressure die casting machine or the liquid forging machine to 60MPa to obtain aluminum alloy components.

[0059] (4) The aluminum alloy component is subjected to T5 heat treatment. The T5 heat treatment process is as follows: artificial aging is performed by heating to 180-210°C within 45 minutes, with a temperature increase of 5-8°C per minute, and then gradually heating to 220-250°C. The holding time is 2-5 hours, and the furnace is cooled to room temperature to obtain the high temperature resistant aluminum alloy.

[0060] (5) The high-temperature resistant aluminum alloy is made into a standard-sized sample and its mechanical properties are tested.

[0061] The main mechanical properties of the standard specimen prepared in this embodiment are as follows: tensile strength 379.8 MPa, yield strength 277.4 MPa, and elongation after fracture 4.27%.

[0062] Example 3

[0063] A method for preparing a high-temperature resistant aluminum alloy, wherein the alloy composition and mass percentages are: Cu 2.48%, Si 10.5%, Mn 0.45%, Mg 0.45%, Fe ≤0.45%, Zn 1.0%, Sr 0.030%, (La+Ce) 0.10%, Ti 0.15%, Cr 0.45%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%; the Si / Cu ratio is approximately 4.23, the Cu / Mg ratio is approximately 5.51, the Cu / Cr ratio is approximately 5.51, and the sum of the mass fractions of Cu+Mg+Zn is 4.13%; no Ni, Mo, or Zr is added to the alloy. The method includes the following steps:

[0064] (1) Prepare the raw materials according to the proportions and preheat and dry each raw material at 450℃. Then set the melting temperature of the smelting furnace to 800℃. First, add the Al-Si alloy ingot to the smelting furnace to melt. After it is completely melted, add pure metals or intermediate alloys of Cu, Mg and Zn elements. After they are completely melted, add Al-Cr and TCB intermediate alloys. After they are completely melted, add Al-RE and Al-Sr intermediate alloys. Stir the molten raw materials for 15 minutes every 1.8 hours. After stirring evenly, the alloy melt is obtained.

[0065] (2) The alloy melt is refined to complete degassing and impurity removal. The refining process is as follows: nitrogen or argon is introduced into the alloy melt as a protective gas, and RJ-01 refining agent is added. The amount of protective gas introduced is 5L / min, the refining time is 30min, and the amount of refining agent added is 0.5% of the mass of the alloy melt.

[0066] (3) Use a high-pressure die casting machine or a liquid forging machine to form the refined alloy melt. Set the injection pressure of the high-pressure die casting machine or the liquid forging machine to 95MPa to obtain aluminum alloy components.

[0067] (4) The aluminum alloy component is subjected to T5 heat treatment. The T5 heat treatment process is as follows: artificial aging is performed by heating to 180-210°C within 45 minutes, with a temperature increase of 5-8°C per minute, and then gradually heating to 220-250°C. The holding time is 2-5 hours, and the furnace is cooled to room temperature to obtain the high temperature resistant aluminum alloy.

[0068] (5) The high-temperature resistant aluminum alloy is made into a standard-sized sample and its mechanical properties are tested.

[0069] The main mechanical properties of the standard sample prepared in this embodiment are as follows: tensile strength 389 MPa, yield strength 287.6 MPa, and elongation after fracture 3.77%.

[0070] Example 4

[0071] A method for preparing a high-temperature resistant aluminum alloy, wherein the alloy composition and mass percentages are: Cu 2.38%, Si 11.0%, Mn 0.35%, Mg 0.45%, Fe ≤0.45%, Zn 1.2%, Sr 0.032%, (La+Ce) 0.15%, Ti 0.13%, Cr 0.65%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%; the Si / Cu ratio is approximately 4.62, the Cu / Mg ratio is approximately 5.28, the Cu / Cr ratio is approximately 3.66, and the sum of the mass fractions of Cu+Mg+Zn is 4.03%; no Ni, Mo, or Zr is added to the alloy. The method includes the following steps:

[0072] (1) Prepare the raw materials according to the proportions and preheat and dry each raw material at 280℃. Then set the melting temperature of the smelting furnace to 800℃. First, add the Al-Si alloy ingot to the smelting furnace to melt. After it is completely melted, add pure metals or intermediate alloys of Cu, Mg and Zn elements. After they are completely melted, add Al-Cr and TCB intermediate alloys. After they are completely melted, add Al-RE and Al-Sr intermediate alloys. Stir the molten raw materials for 15 minutes every 2 hours. After stirring evenly, the alloy melt is obtained.

[0073] (2) The alloy melt is refined to remove gas and impurities. The refining process is as follows: nitrogen or argon is introduced into the alloy melt as a protective gas, and RJ-01 refining agent is added. The amount of protective gas introduced is 5 L / min, the refining time is 25 min, and the amount of refining agent added is 0.1-0.5% of the mass of the alloy melt.

[0074] (3) Use a high-pressure die casting machine or a liquid forging machine to form the refined alloy melt. Set the injection pressure of the high-pressure die casting machine or the liquid forging machine to 100MPa to obtain aluminum alloy components.

[0075] (4) The aluminum alloy component is subjected to T5 heat treatment. The T5 heat treatment process is as follows: artificial aging is performed by heating to 180-210°C within 45 minutes, with a temperature increase of 5-8°C per minute, and then gradually heating to 220-250°C. The holding time is 2-5 hours, and the furnace is cooled to room temperature to obtain the high temperature resistant aluminum alloy.

[0076] (5) The high-temperature resistant aluminum alloy is made into a standard-sized sample and its mechanical properties are tested.

[0077] The main mechanical properties of the standard specimen prepared in this embodiment are as follows: tensile strength 393 MPa, yield strength 297.6 MPa, and elongation after fracture 3.27%.

[0078] The metallographic structures of the samples prepared in Examples 1-4 above were observed under an electron microscope and showed that they were generally similar in distribution (for representative structures, see Appendix). Figure 1As shown in the figure, the introduction of TCB results in a uniform distribution of the α-Al matrix without well-developed dendrites. Simultaneously, TCB, acting as a seed crystal, further disperses the intermetallic compounds, effectively limiting the size of the dispersed particles, weakening the grain boundary segmentation effect, and significantly enhancing the pinning effect. Furthermore, since Ni, Mo, or Zr were not incorporated into the alloy composition, α-Al did not exhibit "poisoning," providing sufficient strength and toughness as the matrix. Additionally, considering the proportions of Si / Cu, Cu / Mg, and Cu / Cr, as well as the total mass fraction of Cu+Mg+Zn, the design elements significantly improved grain size, precipitate size, and concentration gradient, fully leveraging the combined effect of fine-grain strengthening on strength and toughness. Also, taking into account the special working environment of the cylinder block, the elongation after fracture was not excessively pursued. Therefore, by utilizing appropriate proportions of Si / Cu and Cu / Cr, and a suitable total mass fraction of Cu+Mg+Zn, combined with rare earth elements and Ti, the strength was further enhanced.

[0079] From the cross-sectional microstructure (selecting representative structures, see appendix) Figure 2 It can also be seen that the dimples at the cross-section are evenly distributed, with moderate density and relatively uniform size. Combined with the measurement data, it can be determined that the material described in this application can meet the mechanical performance requirements for increasing the power of the next generation of cylinder blocks.

[0080] To further verify the mechanical performance advantages of the material described in this application compared to the prior art, the laboratory organized the following comparative tests.

[0081] Comparative Example 1

[0082] Standard high-pressure casting samples were prepared using the same process as commonly used Al-Si-Cu die-cast aluminum alloys ADC12 and AlSi9Cu3Fe (both Al-Si-Cu series die-cast aluminum alloys) and the high-strength and tough aluminum alloy described in this invention: artificial aging involved heating to 180-210℃ within 45 minutes, with a temperature increase controlled at 5-8℃ per minute, then gradually increasing to 220-250℃ and holding for 2-5 hours, followed by furnace cooling to room temperature. The main chemical composition and mechanical properties were tested, and the results are shown in Table 1.

[0083] Table 1 Comparison of Main Chemical Compositions and Mechanical Properties of Different Aluminum Alloys

[0084]

[0085]

[0086] As shown in Table 1, under the same conditions, the aluminum alloy material designed in this invention has superior mechanical properties after high-pressure casting and T5 heat treatment. Its tensile strength and yield strength are significantly better than those of existing materials, and its high-temperature strength is particularly excellent and significantly better than that of existing materials.

[0087] Example 5

[0088] To verify whether the aluminum alloy prepared by the method of this invention meets the requirements, different batches of high-temperature resistant aluminum alloys prepared by the method of this invention were randomly selected, and their composition and mechanical properties (standard samples) were determined, as shown in Table 2. Artificial aging: the temperature was raised to 180-210℃ within 45 minutes, with a rate increase of 5-8℃ per minute, then gradually raised to 220-250℃, and held for 2-5 hours, followed by furnace cooling to room temperature. The main chemical composition and mechanical properties were tested, and the results are shown in Table 2.

[0089] Table 2. Main components and mechanical properties of different batches of high-temperature resistant aluminum alloys

[0090]

[0091] As shown in Table 2, the high-temperature resistant aluminum alloy materials prepared according to the design principles and methods of this invention have tensile strengths greater than 350 MPa, yield strengths greater than 240 MPa, and elongation after fracture greater than 3.0%, which fully meet the requirements of the automotive industry for lightweight, high strength, high wear resistance, and high toughness. They can be used in the manufacture of automotive engine blocks, providing excellent materials for improving automotive power.

[0092] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-temperature resistant aluminum alloy, characterized in that, The composition includes the following components by mass fraction: Cu 2.0-4.0%, Si 8.5-11.5%, Zn 0.5-1.5%, Mn 0.3-0.6%, Mg 0.3-0.8%, Fe≤0.45%, Sr 0.010-0.045%, Cr 0.3-1.0%, Ti 0.06-0.25%, (La+Ce) 0.05-0.6%, with the balance being Al and impurities; wherein the total impurity content is not greater than 0.25%, the Si / Cu mass fraction ratio is 4-5.5, the Cu / Mg mass fraction ratio is 4-7, the sum of the mass fractions of Cu+Zn+Mg is 3-5, and the Cu / Cr mass fraction ratio is 3-11. The high-temperature resistant aluminum alloy does not contain Ni, Zr, or Mo; after T5 heat treatment, the high-temperature resistant aluminum alloy has a tensile strength ≥230MPa at 250℃.

2. The high-temperature resistant aluminum alloy according to claim 1, characterized in that, The high-temperature resistant aluminum alloy, after T5 heat treatment, has a tensile strength ≥350MPa, a yield strength ≥240MPa, and an elongation after fracture of 3.0-5.0%.

3. A method for preparing the high-temperature resistant aluminum alloy according to any one of claims 1-2, characterized in that, Includes the following steps: (1) Prepare the ingredients according to the proportions, add the raw materials to the melting equipment, heat and melt the raw materials and stir evenly to obtain the alloy melt; (2) Refine the alloy melt to remove gas and impurities; (3) The refined alloy melt is shaped to obtain aluminum alloy components; (4) The aluminum alloy component is subjected to T5 heat treatment to obtain the high temperature resistant aluminum alloy.

4. The method for preparing a high-temperature resistant aluminum alloy according to claim 3, characterized in that, Step (1) also includes preheating and drying the raw material at a temperature of 100-450℃; the melting temperature in step (1) is 700-800℃; the stirring process in step (1) is: stirring once every 1.5-2.5 hours, and each stirring time is 2-15 minutes.

5. The method for preparing a high-temperature resistant aluminum alloy according to claim 3, characterized in that, The order in which the raw materials are added to the smelting equipment in step (1) is as follows: first, Al-Si alloy ingots are added to the smelting furnace to melt. After they are completely melted, pure metals or intermediate alloys of Cu, Mg and Zn elements are added. After they are completely melted, Al-Cr and TCB intermediate alloys are added. After they are completely melted, Al-RE and Al-Sr intermediate alloys are added.

6. The method for preparing a high-temperature resistant aluminum alloy according to claim 3, characterized in that, The refining process in step (2) is as follows: nitrogen or argon is introduced into the alloy melt as a protective gas, and RJ-01 refining agent is added; the amount of protective gas introduced is 0.05-6 L / min, the refining time is 10-30 min, and the amount of refining agent added is 0.1-0.5% of the mass of the alloy melt.

7. The method for preparing a high-temperature resistant aluminum alloy according to claim 3, characterized in that, The equipment used for forming in step (3) is a high-pressure die casting machine or a liquid forging machine, wherein the injection pressure of the high-pressure die casting machine and the liquid forging machine is 50-100MPa.

8. The method for preparing a high-temperature resistant aluminum alloy according to claim 3, characterized in that, The T5 heat treatment process in step (4) is as follows: artificial aging is performed by heating to 180-210℃ within 45 minutes at a heating rate of 5-8℃ / min, and then gradually heating to 220-250℃. The holding time is 2-5 hours, and the furnace is cooled.

9. The application of the high-temperature resistant aluminum alloy according to any one of claims 1-2 in an engine.

10. The application of the high-temperature resistant aluminum alloy according to any one of claims 1-2 in automobiles.

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