A cast heat-resistant aluminum alloy material and preparation method thereof

Abstract

The present invention discloses a cast heat-resistant aluminum alloy material and a preparation method thereof, which belong to the technical field of aluminum alloy materials. The cast heat-resistant aluminum alloy material comprises the following components in percentage by mass: 13% to 15% silicon, 3% to 4% cobalt, 2.5% to 3.5% neodymium, 2% to 3% copper, 0.3% to 0.5% TiB2, ≤0.3% iron, ≤0.2% impurities, and the balance is aluminum. The present application forms Al‑Si‑Co‑Cu‑Nd and Al‑Co‑Cu intermetallic compounds with high thermal stability in the matrix by adding elements such as Co, Nd, and Cu, which can greatly improve the high-temperature tensile strength and yield strength of the aluminum alloy. The added nano-TiB2 particles can hinder the growth of intermetallic compounds and eutectic Si during solidification, achieve a good microstructure refinement effect, and improve its toughness while further improving the room temperature and high-temperature strength of the alloy.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloy materials, and in particular relates to a cast heat-resistant aluminum alloy material and a preparation method thereof. Background Art

[0002] Resource and environmental issues are receiving increasing attention, and lightweighting vehicles is a key development direction to alleviate these issues. Due to the low density of aluminum alloy, using aluminum alloy instead of cast iron in engine manufacturing can significantly reduce weight. The continuous increase in engine power has significantly increased the operating temperature (nose bridge temperature approaches 300°C) and operating pressure (combustion chamber pressure rises to 20MPa) of the cylinder head, placing higher demands on the mechanical properties of the cylinder head aluminum alloy, especially its high-temperature performance.

[0003] Cast heat-resistant aluminum alloys are primarily categorized as Al-Si, Al-Cu, and Al-Mg. Al-Si alloys are currently the most widely used and versatile cast heat-resistant aluminum alloys. The Si element imparts casting properties such as improved fluidity, reduced solidification shrinkage, and a low tendency to hot cracking to Al-Si alloys, but unalloyed Al-Si alloys suffer from low strength. Al-Cu alloys exhibit excellent thermal stability and, after heat treatment, exhibit both good room-temperature and high-temperature mechanical properties. However, these alloys suffer from poor castability, are prone to hot cracking and shrinkage defects, and exhibit poor corrosion resistance. They are primarily used for castings with simple shapes, thin walls, and small volumes. Al-Mg alloys have relatively low room-temperature and high-temperature strength, but exhibit excellent corrosion resistance and machinability. Some studies have shown that the addition of Sc can effectively improve the high-temperature performance of Al-Mg alloys. However, Sc is expensive, resulting in limited application of Al-Mg-Sc alloys with superior performance.

[0004] Al-Si alloys are often alloyed with elements such as Cu, Ni, Mg, Mn, and rare earth elements to improve heat resistance. Currently, conventional hypoeutectic or eutectic Al-Si alloys such as ZL101, ZL108, ZL109, and ADC12 are commonly used in cylinder heads in China. These alloys typically exhibit strengths around 90 MPa at 300°C. Some hypereutectic Al-Si alloys, due to the presence of a large amount of primary Si in their microstructures, exhibit improved high-temperature strength and dimensional stability. For example, ZL117 boasts a tensile strength of 110 MPa at 300°C and is commonly used in engine pistons subjected to harsher service conditions. However, these alloys have high Si content (ZL117 has a Si content of 19% to 22%) and contain Ni. The resulting coarse primary Si or Ni-rich phases contribute to the alloy's brittleness and make further improvements to its room-temperature and high-temperature strength difficult, making it unsuitable for direct cylinder head use. Therefore, the research and preparation of aluminum alloys are of paramount importance. Summary of the Invention

[0005] In response to the shortcomings of the prior art, the present invention aims to provide a cast heat-resistant aluminum alloy material and a method for its preparation. By optimizing the composition and content of alloying elements and controlling the process conditions during the preparation process, the present invention improves the strength and toughness of the aluminum alloy, enabling its use in high-temperature service components such as engine cylinder heads, meeting the requirements of high-power density engines.

[0006] On the one hand, the present invention provides a cast heat-resistant aluminum alloy material, which includes the following components in percentage by mass: 13% to 15% silicon, 3% to 4% cobalt, 2.5% to 3.5% neodymium, 2% to 3% copper, 0.3% to 0.5% TiB2, ≤0.3% iron, ≤0.2% impurities, and the balance being aluminum.

[0007] Optionally, the impurities include one or more of magnesium, zinc, calcium, tin, and lead.

[0008] Another aspect of the present invention provides a method for preparing a cast heat-resistant aluminum alloy material, the method comprising the following steps:

[0009] Step 1: Select pure aluminum, pure copper, master alloy and TiB2 nanoparticles as raw materials;

[0010] Step 2: mixing the raw materials and placing them into a smelting furnace for smelting, and then refining to obtain an alloy melt;

[0011] Step three: pouring the alloy melt into a metal mold for casting to obtain the heat-resistant aluminum alloy casting.

[0012] Optionally, the intermediate alloy in step one includes aluminum silicon alloy, aluminum cobalt alloy, aluminum neodymium alloy, and TiB2 is nanoparticles with an average particle size of 30 nm to 80 nm.

[0013] Optionally, the master alloy is Al-20% Si, Al-10% Co, Al-30% Nd, and TiB2 is nanoparticles with an average particle size of 40 nm to 60 nm.

[0014] Optionally, the smelting temperature in step 2 is 710°C to 740°C.

[0015] Optionally, the refining is carried out by rotating argon blowing.

[0016] Optionally, the refining temperature is 700°C to 730°C, and the refining time is 15min to 20min.

[0017] Optionally, the preheating temperature of the metal mold in step three is 300°C to 350°C, and the pouring temperature of the alloy melt is 680°C to 700°C.

[0018] Another aspect of the present invention provides a use of the above-mentioned cast heat-resistant aluminum alloy material, and / or the cast heat-resistant aluminum alloy material prepared by the above-mentioned method for preparing the cast heat-resistant aluminum alloy material, in engine cylinder head materials.

[0019] The beneficial effects of the present invention include at least one of the following:

[0020] 1. The cast heat-resistant aluminum alloy material provided by the present invention optimizes the mass percentage of each metal element in the aluminum alloy to ensure that the obtained heat-resistant aluminum alloy has both excellent mechanical properties and casting properties. Among them, the Si element makes the alloy have excellent casting properties such as good fluidity, small solidification shrinkage and low thermal cracking tendency. The Co element has a low solid solubility in the aluminum alloy. During the solidification process, it forms Al-Si-Co-Cu-Nd and Al-Co-Cu intermetallic compounds with high thermal stability with elements such as Al, Si, Cu, and Nd, which can greatly improve the high-temperature tensile strength and yield strength of the aluminum alloy. In addition to participating in the formation of heat-resistant intermetallic compounds, Nd can also be partially dissolved in the aluminum matrix, improving the room temperature and high temperature strength of the alloy. The remaining Cu element is distributed at the grain boundary in the form of Al2Cu, forming a θ" strengthening phase during the T6 heat treatment process, improving the room temperature and high temperature strength of the aluminum alloy.

[0021] 2. The cast heat-resistant aluminum alloy material provided by the present invention, by adding an appropriate amount of nano-TiB2 particles, not only promotes the formation of a large amount of θ" phase in the matrix, but also refines the eutectic Si, Al-Si-Co-Cu-Nd and Al-Co-Cu intermetallic compounds, thereby improving the room temperature and high-temperature strength of the aluminum alloy while improving its toughness. During the solidification process, the nano-TiB2 particles are enriched at the growth interface of the eutectic Si, Al-Si-Co-Cu-Nd and Al-Co-Cu compounds, restricting their growth, achieving good microstructure refinement and homogenization effects, thereby fully exerting its high-temperature strengthening effect. In addition, due to the large difference in thermal expansion coefficient between the nano-TiB2 particles and the aluminum matrix, a large number of dislocations will be induced in the matrix, prompting a large amount of θ" phase to precipitate at the dislocations during heat treatment, thereby fully exerting the strengthening effect of the Cu element;

[0022] 3. The method for preparing a cast heat-resistant aluminum alloy provided by the present invention can ensure that the obtained aluminum alloy material has low gas content, less shrinkage cavities and porosity, a fine and uniform microstructure, and excellent mechanical properties by controlling process parameters such as the pouring temperature and the preheating temperature of the mold. The tensile strength, yield strength, and elongation at room temperature and high temperature are all higher than those of commonly used aluminum alloy materials;

[0023] 4. The preparation method of the present invention adopts batch raw materials and industrial equipment, has strong versatility, is easy to produce on a large scale, and has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The microstructure of the T6 state of the cast heat-resistant aluminum alloy prepared in Example 5 of the present invention is shown. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the overall concept of the present invention, a detailed description is given below in the form of examples.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0027] In the present invention, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0028] Hereinafter, the cast heat-resistant aluminum alloy material and the preparation method thereof of the present invention will be described in detail with reference to exemplary embodiments.

[0029] The present invention provides a cast heat-resistant aluminum alloy, which comprises the following components in percentage by mass:

[0030] Silicon 13%-15%, cobalt 3%-4%, neodymium 2.5%-3.5%, copper 2%-3%, TiB2 0.3%-0.5%, iron ≤0.3%, impurities ≤0.2%, and the balance is aluminum. Impurities include one or more of magnesium, zinc, calcium, tin, and lead.

[0031] Specifically, changes in the composition of aluminum alloys will have an important impact on the mechanical properties of the material. Silicon elements usually form primary silicon and eutectic silicon phases in aluminum alloys, which can effectively hinder the dislocation movement of the matrix, thereby improving the mechanical properties of the material to a certain extent, while making the material have a low expansion coefficient and high corrosion resistance. Another important role of silicon elements is to make the alloy have excellent casting properties such as good air tightness, fluidity, small solidification shrinkage and low thermal cracking tendency. However, the Si element content should not be too high, otherwise a large primary silicon phase will be formed, which will reduce the high temperature and room temperature strength and elongation of the alloy. For this reason, the silicon content of the present invention is controlled at 13.0% to 15.0%;

[0032] The solid solubility of cobalt in aluminum is very low. During the solidification process, it forms Al-Si-Co-Cu-Nd and Al-Co-Cu intermetallic compounds with elements such as Al, Si, Cu, and Nd, which have high thermal stability and can greatly improve the high-temperature tensile strength and yield strength of aluminum alloys. However, if the cobalt content is too high, the intermetallic compounds formed will be in the form of thick strips. On the one hand, it makes it difficult for the high-temperature strengthening effect of the compound to be fully exerted. On the other hand, it affects the flow and shrinkage of the molten metal in the late solidification period, forming shrinkage defects in the casting, which in turn reduces the strength and toughness of the casting. In order to give full play to the strengthening effect of the heat-resistant phase containing cobalt and avoid shrinkage in the casting, the cobalt content is controlled at 3.0% to 4.0% in the present invention.

[0033] Neodymium is mainly involved in the formation of heat-resistant intermetallic compounds. In addition, as a rare earth element, neodymium can also purify the aluminum alloy melt and increase the supercooling of the alloy during solidification, thereby improving the fluidity of the alloy. At the same time, neodymium can play a good solid solution strengthening role. When the neodymium content is excessive, it will segregate at the grain boundaries to form an Al-Nd phase with good thermal stability, which has a good pinning strengthening effect on the matrix. Taking into account the high price of neodymium, the present invention controls the neodymium content to 2.5% to 3.5% in order to reduce the cost of the alloy;

[0034] Copper has high solubility in molten aluminum. During the late solidification phase, it typically segregates at grain boundaries in the form of Al2Cu. After solutionization, most of it dissolves in the aluminum matrix and, during the subsequent aging process, is distributed in the matrix as the θ" phase, significantly improving the room-temperature and high-temperature strength of the alloy. When Si, Co, and Nd are present in the alloy, Cu forms Al-Si-Co-Cu-Nd and Al-Co-Cu intermetallic compounds with these elements, which have higher thermal stability, further enhancing the high-temperature strength of the aluminum alloy. However, excessive copper content reduces the alloy's fluidity and increases its tendency to hot cracking. To ensure good melt fluidity and both room-temperature and high-temperature strength, the present invention controls the copper content to 2.0% to 3.0%.

[0035] TiB2, as a ceramic particle, exhibits excellent high-temperature stability. Existing as solid particles in aluminum alloy melts, it not only inhibits the growth of eutectic Si, Al-Si-Co-Cu-Nd, and Al-Co-Cu intermetallic compounds during alloy solidification, but also promotes the formation of numerous dislocations in the matrix, intensifying the precipitation of the θ" phase during aging, thereby fully leveraging the strengthening effects of elements such as Co, Nd, and Cu. TiB2 particles are nanometer-sized, and the van der Waals forces between them are strong. Excessive TiB2 content leads to agglomeration and difficulty in dispersion, failing to refine the microstructure and instead forming loose, clustered inclusions. To ensure a finer solidified microstructure and avoid inclusion defects in the present invention, the TiB2 particle content is controlled within a range of 0.3% to 0.5%.

[0036] Other impurity elements such as magnesium, zinc, calcium, tin, lead, etc. are all impurities and their content should be strictly controlled, otherwise they will hinder the formation of Al-Si-Co-Cu-Nd and Al-Co-Cu intermetallic compounds, seriously affecting the high-temperature properties of the alloy. The total content of the above impurity elements is controlled below 0.20%.

[0037] In an exemplary embodiment of the present invention, the method for preparing the above-mentioned cast heat-resistant aluminum alloy material can be achieved by the following steps:

[0038] S1. Select pure aluminum, pure copper, a master alloy, and TiB2 nanoparticles as raw materials. The master alloys include aluminum-silicon alloys, aluminum-cobalt alloys, and aluminum-neodymium alloys. The TiB2 nanoparticles have an average particle size of 30 nm to 80 nm. Preferably, the master alloys are Al-20% Si (an aluminum-silicon master alloy containing 20% ​​silicon), Al-10% Co (an aluminum-cobalt master alloy containing 10% cobalt), or Al-30% Nd (an aluminum-neodymium master alloy containing 30% neodymium). The TiB2 nanoparticles have an average particle size of 40 nm to 60 nm.

[0039] S2. Mix the raw materials uniformly according to the proportion and place them in a smelting furnace. Smelt them at 710°C to 740°C. After the raw materials are smelted, adjust the temperature of the smelting furnace to 700°C to 730°C. Then, perform refining treatment by rotating argon blowing to remove gas and impurities. After refining for 15 to 20 minutes, let it stand for 5 minutes, and skim off the slag to obtain an alloy melt.

[0040] S3. The alloy melt at 680° C. to 700° C. is poured into a mold preheated at 300° C. to 350° C. for casting to obtain a heat-resistant aluminum alloy casting.

[0041] The strength of the cast castings can be greatly improved by T6 heat treatment. The specific T6 heat treatment process steps are: solution treatment at 525℃ for 7 to 9 hours, quenching, and then aging treatment at 190℃ for 10 to 12 hours. The quenching medium is 80℃ water.

[0042] Example 1

[0043] S1. Select pure aluminum, pure copper, master alloy and TiB2 nanoparticles with an average particle size of 50 nm as raw materials, and prepare the raw materials according to the proportions of the five alloy components in Table 1, only changing the content of Si element.

[0044] S2. The five groups of raw materials in S1 are mixed evenly and placed in a smelting furnace respectively, and smelted at 740°C. After the raw materials are smelted, the temperature of the smelting furnace is adjusted to 730°C, and then refining treatment is carried out by rotating argon blowing to remove gas and impurities. After refining for 20 minutes, the mixture is allowed to stand for 5 minutes, and the alloy melt is obtained after slag removal.

[0045] S3. Pouring the alloy melt into a mold to form a casting, wherein the preheating temperature of the mold is 320° C. and the pouring temperature of the alloy melt is 700° C.

[0046] S4. The casting is solution treated at 525℃ for 7h and then quenched. It is then aged at 190℃ for 10h. The quenching medium is water at 80℃.

[0047] Table 1 Material composition of cast heat-resistant aluminum alloys with different Si contents

[0048]

[0049] The cast heat-resistant aluminum alloys in Table 1 were prepared according to the above process parameters, and the mechanical properties (tensile strength, yield strength, elongation) of the cast heat-resistant aluminum alloys with different Si contents were measured and shown in Table 2.

[0050] Table 2 Room temperature and high temperature mechanical properties of cast heat-resistant aluminum alloys with different Si contents

[0051]

[0052] As shown in Table 2, when the Si content is lower than 13%, the strength of the alloy is significantly low; and when the Si content is higher than 15%, although the tensile strength is high, the yield strength and elongation decrease sharply. Therefore, the preferred ratio of Si is 13.0% to 15.0%.

[0053] Example 2

[0054] S1. Select pure aluminum, pure copper, master alloy and TiB2 nanoparticles with an average particle size of 60 nm as raw materials, and prepare the raw materials according to the proportions of the five alloy components in Table 3, only changing the content of the Co element.

[0055] S2. The five groups of raw materials in S1 are mixed evenly and placed in a melting furnace respectively, and smelted at 720°C. After the raw materials are smelted, the temperature of the melting furnace is adjusted to 710°C, and then refining treatment is carried out by rotating argon blowing to remove gas and impurities. After refining for 15 minutes, the mixture is allowed to stand for 5 minutes, and the alloy melt is obtained after slag removal.

[0056] S3. Pouring the alloy melt into a mold to form a casting, wherein the preheating temperature of the mold is 320° C. and the pouring temperature of the alloy melt is 690° C.

[0057] S4. The casting is solution treated at 525℃ for 7h and then quenched. It is then aged at 190℃ for 10h. The quenching medium is water at 80℃.

[0058] Table 3 Material composition of cast heat-resistant aluminum alloys with different Co contents

[0059]

[0060] The cast heat-resistant aluminum alloys in Table 3 were prepared according to the above process parameters, and the mechanical properties (tensile strength, yield strength, elongation) of the cast heat-resistant aluminum alloys with different Co contents were measured and shown in Table 4.

[0061] Table 4 Room temperature and high temperature mechanical properties of cast heat-resistant aluminum alloys with different Co contents

[0062]

[0063] As shown in Table 4, when the Co content is less than 3.0%, the resulting heat-resistant aluminum alloy has good room temperature strength and high elongation, but low high-temperature strength. When the Co content exceeds 4.0%, both the strength and elongation of the material decrease significantly. Therefore, the preferred Co content is 3.0% to 4.0%.

[0064] Example 3

[0065] S1. Select pure aluminum, pure copper, master alloy and TiB2 nanoparticles with an average particle size of 45 nm as raw materials, and prepare the raw materials according to the proportions of the five alloy components in Table 5, only changing the content of the Nd element.

[0066] S2. The five groups of raw materials in S1 are mixed evenly and placed in a melting furnace respectively, and smelted at 730°C. After the raw materials are smelted, the temperature of the melting furnace is adjusted to 710°C, and then refining treatment is carried out by rotating argon blowing to remove gas and impurities. After refining for 20 minutes, the mixture is allowed to stand for 5 minutes, and the alloy melt is obtained after slag removal.

[0067] S3. Pouring the alloy melt into a mold to form a casting, wherein the preheating temperature of the mold is 350° C. and the pouring temperature of the alloy melt is 680° C.

[0068] S4. The casting is solution treated at 525℃ for 7h and then quenched. It is then aged at 190℃ for 10h. The quenching medium is water at 80℃.

[0069] Table 5 Material composition of cast heat-resistant aluminum alloys with different Nd contents

[0070]

[0071] The cast heat-resistant aluminum alloys in Table 5 were prepared according to the above process parameters, and the mechanical properties (tensile strength, yield strength, elongation) of the cast heat-resistant aluminum alloys with different Nd contents were measured and shown in Table 6.

[0072] Table 6 Room temperature and high temperature mechanical properties of cast heat-resistant aluminum alloys with different Nd contents

[0073]

[0074] As shown in Table 6, when the Nd content is less than 2.5%, the resulting heat-resistant aluminum alloy has high room-temperature strength and elongation, but low high-temperature strength. When the Nd content exceeds 3.5%, both the room-temperature strength and elongation of the material decrease significantly. Therefore, the preferred Nd content is 2.5% to 3.5%.

[0075] Example 4

[0076] S1. Select pure aluminum, pure copper, master alloy and TiB2 nanoparticles with an average particle size of 55 nm as raw materials, and prepare the raw materials according to the proportions of the five alloy components in Table 7, only changing the content of Cu element.

[0077] S2. The five groups of raw materials in S1 are mixed evenly and placed in a smelting furnace respectively, and smelted at 740°C. After the raw materials are smelted, the temperature of the smelting furnace is adjusted to 720°C, and then refining treatment is carried out by rotating argon blowing to remove gas and impurities. After refining for 15 minutes, the mixture is allowed to stand for 5 minutes, and the alloy melt is obtained after slag removal.

[0078] S3. Pouring the alloy melt into a mold to form a casting, wherein the preheating temperature of the mold is 300° C. and the pouring temperature of the alloy melt is 700° C.

[0079] S4. The casting is solution treated at 525℃ for 7h and then quenched. It is then aged at 190℃ for 10h. The quenching medium is water at 80℃.

[0080] Table 7 Material composition of cast heat-resistant aluminum alloys with different Cu contents

[0081]

[0082] The cast heat-resistant aluminum alloys in Table 7 were prepared according to the above process parameters, and the mechanical properties (tensile strength, yield strength, elongation) of the cast heat-resistant aluminum alloys with different Cu contents were measured and shown in Table 8.

[0083] Table 8 Room temperature and high temperature mechanical properties of cast heat-resistant aluminum alloys with different Cu contents

[0084]

[0085] As shown in Table 8, when the Cu content is less than 2.0%, the room temperature strength and elongation of the resulting heat-resistant aluminum alloy are high, but the high-temperature strength is low. When the Cu content exceeds 3.0%, the strength and elongation of the material are significantly reduced. Therefore, the preferred Cu content is 2.0% to 3.0%.

[0086] Example 5

[0087] S1. Select pure aluminum, pure copper, master alloy and TiB2 nanoparticles with an average particle size of 40 nm as raw materials, and prepare the raw materials according to the proportions of the 7 groups of alloy components in Table 1.

[0088] S2. The 7 groups of raw materials in S1 were mixed evenly and placed in a smelting furnace for smelting at 730°C. After the raw materials were smelted, the temperature of the smelting furnace was adjusted to 710°C. Then, a rotary argon blowing method was used for refining to remove gas and impurities. After refining for 15 minutes, the mixture was allowed to stand for 5 minutes, and the alloy melt was obtained after slag removal.

[0089] S3. Pouring the alloy melt into a mold to form a casting, wherein the preheating temperature of the mold is 300° C. and the pouring temperature of the alloy melt is 690° C.

[0090] S4. The casting is solution treated at 525℃ for 7h and then quenched. It is then aged at 190℃ for 10h. The quenching medium is water at 80℃.

[0091] Table 9 Material composition of cast heat-resistant aluminum alloys with different component ratios

[0092]

[0093]

[0094] According to the above process parameters, 7 groups of cast heat-resistant aluminum alloys in Table 9 were prepared, and the room temperature mechanical properties and high temperature mechanical properties (tensile strength, yield strength, elongation) of the 7 groups of cast heat-resistant aluminum alloys were measured and shown in Table 10.

[0095] Table 10 Room temperature and high temperature mechanical properties of cast heat-resistant aluminum alloys with different composition ratios

[0096]

[0097] Comparative Example 1

[0098] The room temperature mechanical properties and high temperature mechanical properties (tensile strength, yield strength, elongation) of heat-resistant aluminum alloy materials (ZL702A, ZL108, and ZL109) commonly used on the market were tested. The measured results are shown in Table 11.

[0099] Table 11 Room temperature and high temperature mechanical properties of commonly used heat-resistant aluminum alloys

[0100]

[0101]

[0102] Figure 1 The T6 microstructure of the 23# cast heat-resistant aluminum alloy prepared in Example 5 is shown. The figure demonstrates that the addition of elements such as Co, Nd, and Cu forms highly thermally stable Al-Si-Co-Cu-Nd and Al-Co-Cu intermetallic compounds in the matrix, significantly improving the alloy's high-temperature tensile strength and yield strength. The addition of nano-TiB2 particles hinders the growth of intermetallic compounds and eutectic Si during solidification, resulting in excellent microstructure refinement. This further enhances the alloy's room-temperature and high-temperature strength while also improving its toughness.

[0103] By comparing the data in Table 10 and Table 11, it can be seen that the tensile strength, yield strength and elongation of the cast heat-resistant aluminum alloy prepared by the preparation method of the present application at room temperature and high temperature are higher than those of the commonly used ZL702A, ZL108 and ZL109 alloys. Therefore, the cast heat-resistant aluminum alloy provided by the present invention has excellent mechanical properties.

[0104] The foregoing is merely an embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. A cast heat-resistant aluminum alloy material, characterized in that: According to the percentage by mass, it includes the following components: silicon 13% to 15%, cobalt 3% to 4%, neodymium 2.5% to 3.5%, copper 2% to 3%, TiB2 0.3% to 0.5%, iron ≤ 0.3%, impurities ≤ 0.2%, and the balance is aluminum. The method for preparing the cast heat-resistant aluminum alloy material comprises the following steps: Step 1: selecting pure aluminum, pure copper, master alloy and TiB2 nanoparticles as raw materials; Step 2: mixing the raw materials and placing them into a smelting furnace for smelting, and then refining to obtain an alloy melt; Step three: pouring the alloy melt into a metal mold for casting to obtain the heat-resistant aluminum alloy casting.

2. The cast heat-resistant aluminum alloy material according to claim 1, characterized in that: The impurities include one or more of magnesium, zinc, calcium, tin and lead.

3. A method for preparing the cast heat-resistant aluminum alloy material according to claim 1, characterized in that: The preparation method comprises the following steps: Step 1: Select pure aluminum, pure copper, master alloy and TiB2 nanoparticles as raw materials; Step 2: mixing the raw materials and placing them into a smelting furnace for smelting, and then refining to obtain an alloy melt; Step three: pouring the alloy melt into a metal mold for casting to obtain the heat-resistant aluminum alloy casting.

4. The method for preparing a cast heat-resistant aluminum alloy material according to claim 3, wherein: The intermediate alloy in step 1 includes aluminum silicon alloy, aluminum cobalt alloy, and aluminum neodymium alloy, and TiB2 is nanoparticles with an average particle size of 30nm to 80nm.

5. The method for preparing a cast heat-resistant aluminum alloy material according to claim 4, wherein: The master alloy is Al-20% Si, Al-10% Co, and Al-30% Nd, and TiB2 is nanoparticles with an average particle size of 40nm to 60nm.

6. The method for preparing a cast heat-resistant aluminum alloy material according to claim 3, wherein: The smelting temperature in the step 2 is 710° C. to 740° C.

7. The method for preparing a cast heat-resistant aluminum alloy material according to claim 6, wherein: The refining is carried out by means of rotating argon blowing.

8. The method for preparing a cast heat-resistant aluminum alloy material according to claim 7, characterized in that: The refining temperature is 700° C. to 730° C., and the refining time is 15 min to 20 min.

9. The method for preparing a cast heat-resistant aluminum alloy material according to claim 3, wherein: The preheating temperature of the metal mold in step three is 300°C to 350°C, and the pouring temperature of the alloy melt is 680°C to 700°C.

10. Use of the cast heat-resistant aluminum alloy material according to any one of claims 1 to 2, or the cast heat-resistant aluminum alloy material prepared by the method for preparing the cast heat-resistant aluminum alloy material according to any one of claims 3 to 9, in engine cylinder head materials.

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