Nanoparticle-reinforced high strength-to-toughness heat-resistant cast aluminum-copper alloy

Abstract

The application provides a nanoparticle-reinforced high-strength and high-toughness heat-resistant cast aluminum-copper alloy. A preparation method thereof comprises the following steps: mixing a niobium-titanium-aluminum alloy powder, a BN powder and a carbon powder to obtain a powder mixture 1; wrapping the powder mixture 1 into a wire material by using a pure aluminum strip; melting the wire material and mixing the melted wire material with a pure aluminum liquid to obtain a wire B; melting an aluminum-copper alloy, adding the wire B to obtain a mixed melt, and then performing mechanical stirring, ultrasonic treatment, slag removal, casting and T6 heat treatment on the mixed melt to obtain the nanoparticle-reinforced high-strength and high-toughness heat-resistant cast aluminum-copper alloy. Compared with a conventional aluminum-copper alloy, the tensile strength, the yield strength and the fracture strain of the aluminum-copper alloy at 200 DEG C are all greater than or equal to 340 MPa, greater than or equal to 198 MPa and greater than or equal to 13.2%, respectively, and the service performance of the aluminum-copper alloy at high temperature is simultaneously improved. Compared with a cast aluminum-copper alloy obtained by using the prior art, the raw material cost of the application is lower, the process is simplified and the comprehensive performance is better.

Description

Technical Field

[0001] This invention relates to the field of high-performance aluminum alloy technology, specifically to a high-strength, high-toughness, heat-resistant cast aluminum-copper alloy reinforced with nanoparticles. Background Technology

[0002] Al-Cu casting alloys are widely used in critical structural components operating in high-temperature environments, such as aerospace and automotive engine blocks, pistons, and turbocharger impellers, due to their excellent room-temperature mechanical properties, good machinability, and outstanding heat resistance. With the increasing demands of modern industry for lightweight and high-power-density equipment, even more stringent challenges are posed to the strength and toughness of heat-resistant cast aluminum alloys under high-temperature conditions.

[0003] Currently, traditional Al-Cu alloys primarily rely on precipitated phases (such as the θ' phase) for strengthening. However, under high-temperature service conditions, the strengthening phases within the alloy are prone to coarsening or even dissolution, leading to a sharp decrease in the alloy's high-temperature strength. Existing technologies typically involve adding rare earth elements and Ni to the aluminum-copper alloy matrix to refine the grains and strengthen the second phase, thereby improving the high-temperature strength of the aluminum-copper alloy. However, these methods are costly and have poor stability. Although they can improve strength to a certain extent, the improvement in plasticity is not significant, meaning it is difficult to achieve a simultaneous improvement in high-temperature strength and plasticity. Furthermore, excessively high rare earth and Ni contents increase the alloy density, which to some extent weakens the lightweight advantage of aluminum alloys. Therefore, how to reduce the cost of raw material additions, simplify the process, and achieve a synergistic improvement in the strength and plasticity of cast aluminum-copper alloys under high-temperature conditions while ensuring the lightweight of aluminum alloys is an urgent technical problem to be solved. Summary of the Invention

[0004] To address the aforementioned technical challenges, this invention provides a high-strength, high-toughness, and heat-resistant cast aluminum-copper alloy reinforced with nanoparticles, the preparation method of which includes the following steps: (1) Niobium-titanium-aluminum alloy powder, BN powder and carbon powder are mixed at a mass ratio of 64-86:12-18:1-5 at a rotation speed of 20-80 r / min for 13-23 hours to obtain powder mixture 1; then powder mixture 1 is coated with pure aluminum strip to obtain wire A, wherein the mass ratio of powder mixture 1 to pure aluminum strip is 70-90:15-25; wire A is heated to 900-1050℃ to form a melt, and then the melt is mixed with pure aluminum liquid, mechanically stirred and ultrasonically treated, and finally cast and rolled into intermediate alloy wire B containing nano-ceramic particles; The mechanical stirring is performed for 5-15 minutes at a speed of 300-600 r / min. The ultrasonic treatment lasts for 10-20 minutes and has a frequency of 18-21 kHz. The casting and rolling process involves a rolling temperature of 350℃-450℃ and a rolling speed of 0.1-0.3 m / s. The particle size of the niobium-titanium-aluminum alloy powder is 10 micrometers to 80 micrometers, the particle size of the BN powder is 1 micrometer to 10 micrometers, and the particle size of the carbon powder is 15 micrometers to 100 micrometers. The mass ratio of the melt to the pure aluminum liquid is 1-5:15-25; The nano-ceramic particles in the intermediate alloy wire B account for 5 wt.%-10 wt.% of the total content. (2) After melting the aluminum-copper alloy at 730-830℃, add the preheated intermediate alloy wire B from step (1). After the intermediate alloy wire B is completely melted, a mixed melt is obtained. Then, the mixed melt is subjected to mechanical stirring, ultrasonic treatment, slag removal, settling, casting molding process, and T6 heat treatment to obtain a high-strength, high-toughness, heat-resistant cast aluminum-copper alloy reinforced with nanoparticles. The aluminum-copper alloy composition, by mass percentage, is as follows: Cu: 4.2 wt.% - 5.2 wt.%; Mn: 0.2 wt.% - 0.5 wt.%; Ti: 0.15 wt.% - 0.35 wt.%; V: 0.05 wt.% - 0.3 wt.%; Zr: 0.05 wt.% - 0.15 wt.%; Cd: 0.1 wt.% - 0.3 wt.%; B: 0.005 wt.% - 0.06 wt.%; Si: ≤0.1 wt.%; balance Al.

[0005] The mass ratio of wire B to aluminum-copper alloy is 0.5-2:50-150; The mechanical stirring is performed at a speed of 200-500 r / min for 3-10 minutes. The ultrasonic treatment has a frequency of 19-21 kHz and a duration of 1-15 minutes. The casting process involves pouring at 710-740℃, preheating the mold at 220-280℃, and pouring at a speed of 0.15-0.35 kg / s. The T6 heat treatment involves holding at 530-540℃ for 10-14 hours, followed by water quenching at 60-80℃; then holding at 170-180℃ for 6-10 hours, and air cooling to room temperature. The nanoparticle-reinforced high-strength, high-toughness, heat-resistant cast aluminum-copper alloy achieves a synergistic improvement in strength and plasticity at high temperatures; at 200℃, the tensile strength is ≥340 MPa, the yield strength is ≥198 MPa, and the fracture strain is ≥13.2%, which contains nano-ceramic particles with a mass percentage of ≤0.15% and a particle size of 60-100 nm.

[0006] Further, in step (1), the niobium-titanium-aluminum alloy powder, BN powder and carbon powder are mixed at a mass ratio of 70-80:14-16:2-4 and a rotation speed of 40-60 r / min for 15-18 hours to obtain powder mixture 1.

[0007] Further, the powder mixture 1 obtained in step (1) is coated with pure aluminum strip to obtain wire A, wherein the mass ratio of the powder mixture 1 to the pure aluminum strip is 75-85:16-23.

[0008] Further, in step (1), the wire A is heated to 950-1000℃ to form a melt, and then the melt is mixed with pure aluminum liquid, and after mechanical stirring and ultrasonic treatment, it is finally cast and rolled into intermediate alloy wire B containing nano-ceramic particles. The proportion of nano-ceramic particles in the intermediate alloy wire B is 6wt.%-8wt.%.

[0009] Furthermore, in step (1), the particle size of the niobium-titanium-aluminum alloy powder is 15 micrometers to 50 micrometers, the particle size of the BN powder is 2 micrometers to 8 micrometers, and the carbon powder is 20 micrometers to 80 micrometers.

[0010] Further, in step (1), the mechanical stirring time is 8-12 minutes and the rotation speed is 400-550 r / min; the ultrasonic treatment time is 13-18 minutes and the frequency is 18.6-20.3 kHz; the rolling temperature is 360℃-410℃ and the rolling speed is 0.17-0.23 m / s.

[0011] Further, in step (2), after melting the aluminum-copper alloy matrix at 760-820℃, the preheated intermediate alloy wire B from step (1) is added. After the intermediate alloy wire B is completely melted, a mixed melt is obtained. Then, the mixed melt is subjected to mechanical stirring, ultrasonic treatment, slag removal, settling, casting forming process, and T6 heat treatment to obtain a high-strength, high-toughness, heat-resistant cast aluminum-copper alloy reinforced with nanoparticles.

[0012] Furthermore, in step (2), the mechanical stirring time is 5-7 minutes and the rotation speed is 300-450 r / min; the ultrasonic treatment time is 3-12 minutes and the frequency is 19.8-20.2 kHz.

[0013] Further, the composition of the cast aluminum-copper alloy mentioned in step (2) mainly includes: Cu: 4.4wt.%-5.1wt.%; Mn: 0.22wt.%-0.4wt.%; Ti: 0.16wt.%-0.3wt.%; V: 0.1wt.%-0.25wt.%; Zr: 0.07wt.%-0.12wt.%; Cd: 0.15wt.%-0.25wt.%; B: 0.01wt.%-0.05wt.%; Si: ≤0.08wt.%; the balance is Al.

[0014] Furthermore, the high-strength, high-toughness, heat-resistant cast aluminum-copper alloy reinforced with nanoparticles described in step (2) achieves a synergistic improvement in strength and plasticity at high temperatures; at 200℃, the tensile strength is 340-350MPa, the yield strength is 198-215MPa, and the fracture strain is 13.2-18.1%, which contains nano-ceramic particles, the proportion of which is 0.05-0.15wt%, and the particle size is 70-90nm.

[0015] (1) Existing technologies improve the high-temperature performance of aluminum-copper alloys by adding more than 0.3% of high-cost metal elements such as rare earth and Ni, relying on a wide range of supercooling and the formation of certain coarse impurities for nucleation, inhibiting grain boundary migration and grain growth; while the present invention only adds nano-ceramic particles with a content of ≤0.15%, and changes the nucleation mode of the alloy by using nano-particles as heterogeneous nucleation cores, significantly refining the grains, improving the high-temperature performance of the alloy, and having a lower raw material production cost.

[0016] (2) Existing technologies can make the tensile strength of aluminum-copper alloys ≤335MPa at 200℃ by adding elements such as Ni and rare earth, while the high strength, toughness and heat resistance of the nanoparticle-reinforced cast aluminum-copper alloy prepared by the present invention has a tensile strength ≥340MPa at 200℃, which is significantly better than the existing technologies.

[0017] (3) In addition, the addition of a large amount of high-cost metals such as Ni and rare earth elements in the existing technology will increase the alloy density, which will easily form a brittle phase. Under stress, it is easy to generate crack sources, which will reduce the fatigue life and plasticity of the alloy. The present invention achieves the following technical effects by adding a small amount of nano ceramic particles and coordinating and controlling the composition, proportion, process and process parameters: hindering dislocation movement, pinning grain boundaries at high temperature, delaying grain growth, inhibiting grain boundary movement, reducing secondary dendrite spacing, solving the problem that the strengthening phase generated by adding Ni and rare earth elements is easy to coarsen at high temperature, and simultaneously improving the strength and plasticity of cast aluminum alloy, so that the alloy has a yield strength ≥198MPa and tensile strength ≥340MPa at 200℃, while the fracture strain ≥13.2%, breaking the technical bottleneck of the existing technology that it is difficult to improve the strength and plasticity at high temperature simultaneously. Attached Figure Description

[0018] Figure 1 These are high-temperature tensile comparison images of the cast aluminum-copper alloys prepared in Examples 1-3 and the comparative examples of the present invention.

[0019] Figure 2 This is a scanning electron microscope image of the cast aluminum-copper alloy T6 obtained in Example 1 after treatment.

[0020] Figure 3This is a scanning electron microscope image of the cast aluminum-copper alloy T6 obtained in Example 2 after treatment.

[0021] Figure 4 This is a scanning electron microscope image of the cast aluminum-copper alloy T6 obtained in Example 3 after treatment.

[0022] Figure 5 The image shows a scanning electron microscope (SEM) image of the cast aluminum-copper alloy T6 prepared in Comparative Example 1 after treatment. Specific Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0024] The preparation method of the nanoparticle-reinforced high-strength, high-toughness, and heat-resistant cast aluminum-copper alloy 1 includes the following steps: (1) Niobium-titanium-aluminum alloy powder, BN powder and carbon powder are mixed at a mass ratio of 70:16:2 and a rotation speed of 60 r / min for 15 hours to obtain powder mixture 1; then powder mixture 1 is coated with pure aluminum strip to obtain wire A, wherein the mass ratio of powder mixture 1 to pure aluminum strip is 76:23; wire A is heated to 1000℃ to form a melt, and then the melt is mixed with pure aluminum liquid, and after mechanical stirring and ultrasonic treatment, it is finally cast and rolled into intermediate alloy wire B containing nano-ceramic particles; The mechanical stirring time is 12 minutes and the rotation speed is 400 r / min; The ultrasonic treatment lasted for 18 minutes and had a frequency of 19.6 kHz. The casting and rolling process involves a rolling temperature of 410℃ and a rolling speed of 0.23 m / s. The niobium-titanium-aluminum alloy powder has a particle size of 50 micrometers, the BN powder has a particle size of 8 micrometers, and the carbon powder has a particle size of 30 micrometers. The mass ratio of the melt to the pure aluminum liquid is 2:23; The nano-ceramic particles in the intermediate alloy wire B account for 6.4 wt.%; (2) After melting the aluminum-copper alloy at 820℃, add the preheated intermediate alloy wire B from step (1). After the intermediate alloy wire B is completely melted, a mixed melt is obtained. Then, the mixed melt is subjected to mechanical stirring, ultrasonic treatment, slag removal, settling, casting molding process and T6 heat treatment to obtain a high-strength, high-toughness, heat-resistant cast aluminum-copper alloy reinforced with nanoparticles. The aluminum-copper alloy composition, by weight percentage, is: Cu: 4.4 wt.%; Mn: 0.36 wt.%; Ti: 0.17 wt.%; V: 0.23 wt.%; Zr: 0.08 wt.%; Cd: 0.25 wt.%; B: 0.05 wt.%; Si: 0.08 wt.%; balance Al; The mass ratio of wire B to aluminum-copper alloy is 0.8:101.6; The mechanical stirring was carried out at a speed of 420 r / min for 5 minutes. The ultrasonic treatment was performed at a frequency of 20.2 kHz for 5 minutes. The casting process involves pouring at 740°C, preheating the mold at 260°C, and using a pouring speed of 0.15 kg / s. The T6 heat treatment involves holding at 540℃ for 11 hours, followed by water quenching at 80℃; then holding at 180℃ for 7 hours, and air cooling to room temperature.

[0025] In this embodiment, the nanoparticle-reinforced high-strength, high-toughness, and heat-resistant cast aluminum-copper alloy 1 has a uniformly distributed nanoparticle structure, with nano-ceramic particles accounting for 0.05 wt.% and having a size of 70-90 nm. Figure 1 It can be seen that its yield strength, tensile strength, and fracture strain at 200℃ are 198MPa, 343MPa, and 14.9%, respectively; Figure 2 The electron microscopy images clearly show that the microstructure of the alloy has been refined, and the second phase at the grain boundaries exhibits a skeletal or granular distribution, indicating that the nanoparticles act as heterogeneous nucleation cores during solidification, effectively suppressing grain boundary movement and reducing the secondary dendrite spacing. Example 2

[0026] The preparation method of the nanoparticle-reinforced high-strength, high-toughness, and heat-resistant cast aluminum-copper alloy 2 includes the following steps: (1) Niobium-titanium-aluminum alloy powder, BN powder and carbon powder are mixed at a mass ratio of 75:15:3 and a rotation speed of 50 r / min for 16 hours to obtain powder mixture 1; then powder mixture 1 is coated with pure aluminum strip to obtain wire A, wherein the mass ratio of powder mixture 1 to pure aluminum strip is 4:1; wire A is heated to 980°C to form a melt, and then the melt is mixed with pure aluminum liquid, and after mechanical stirring and ultrasonic treatment, it is finally cast and rolled into intermediate alloy wire B containing nano-ceramic particles; The mechanical stirring time is 10 minutes and the rotation speed is 500 r / min; The ultrasonic treatment lasted for 16 minutes and had a frequency of 18.8 kHz. The casting and rolling process involves a rolling temperature of 380℃ and a rolling speed of 0.2 m / s. The particle size of the niobium-titanium-aluminum alloy powder is 35 micrometers, the particle size of the BN powder is 5 micrometers, and the particle size of the carbon powder is 50 micrometers. The mass ratio of the melt to the pure aluminum liquid is 3:20; The proportion of nano-ceramic particles in the intermediate alloy wire B is 7.2 wt.%. (2) After melting the aluminum-copper alloy at 800℃, add the preheated intermediate alloy wire B from step (1). After the intermediate alloy wire B is completely melted, a mixed melt is obtained. Then, the mixed melt is subjected to mechanical stirring, ultrasonic treatment, slag removal, settling, casting molding process, and T6 heat treatment to obtain a high-strength, high-toughness, heat-resistant cast aluminum-copper alloy reinforced with nanoparticles. The aluminum-copper alloy, by weight percentage, mainly comprises: Cu: 4.7 wt.%; Mn: 0.3 wt.%; Ti: 0.22 wt.%; V: 0.18 wt.%; Zr: 0.1 wt.%; Cd: 0.2 wt.%; Fe:B: 0.03 wt.%; Si: 0.06 wt.%; with the balance being Al. The mass ratio of wire B to aluminum-copper alloy is 1.2:85.2; The mechanical stirring was performed at a speed of 380 r / min for 6 minutes. The ultrasonic treatment was performed at a frequency of 20 kHz for 8 minutes. The casting process involves pouring at 730°C, preheating the mold at 240°C, and a pouring speed of 0.2 kg / s. The T6 heat treatment involves holding at 535℃ for 12 hours, followed by water quenching at 70℃; then holding at 170℃ for 10 hours, and air cooling to room temperature. In this embodiment, the nanoparticles inside the nanoparticle-reinforced high-strength, high-toughness, and heat-resistant castable alloy 2 are uniformly distributed, with nano-ceramic particles accounting for 0.1 wt.% and having a size of 65-80 nm. Figure 1 It can be seen that its yield strength, tensile strength, and fracture strain at 200℃ are 208MPa, 340MPa, and 13.2%, respectively; Figure 3 The scanning electron microscope images show that the grain size has been further refined and the density of the strengthening phase in the matrix has increased, which provides the alloy with higher yield strength. Example 3

[0027] The preparation method of the nanoparticle-reinforced high-strength, high-toughness, and heat-resistant cast aluminum-copper alloy 3 includes the following steps: (1) Niobium-titanium-aluminum alloy powder, BN powder and carbon powder are mixed at a mass ratio of 80:14:4 and a rotation speed of 40 r / min for 18 hours to obtain powder mixture 1; then powder mixture 1 is coated with pure aluminum strip to obtain wire A, wherein the mass ratio of powder mixture 1 to pure aluminum strip is 83:18; wire A is heated to 950°C to form a melt, and then the melt is mixed with pure aluminum liquid, and after mechanical stirring and ultrasonic treatment, it is finally cast and rolled into intermediate alloy wire B containing nano-ceramic particles; The mechanical stirring time is 8 minutes and the rotation speed is 550 r / min; The ultrasonic treatment lasted for 13 minutes and had a frequency of 19.2 kHz. The casting and rolling process involves a rolling temperature of 360℃ and a rolling speed of 0.17 m / s. The particle size of the niobium-titanium-aluminum alloy powder is 20 micrometers, the particle size of the BN powder is 3 micrometers, and the particle size of the carbon powder is 80 micrometers. The mass ratio of the melt to the pure aluminum liquid is 1:5; The proportion of nano-ceramic particles in the intermediate alloy wire B is 7.8 wt.%. (2) After melting the aluminum-copper alloy at 760℃, add the preheated intermediate alloy wire B from step (1). After the intermediate alloy wire B is completely melted, a mixed melt is obtained. Then, the mixed melt is subjected to mechanical stirring, ultrasonic treatment, slag removal, settling, casting molding process, and T6 heat treatment to obtain a high-strength, high-toughness, heat-resistant cast aluminum-copper alloy reinforced with nanoparticles. The aluminum-copper alloy, by weight percentage, mainly comprises: Cu: 4.9 wt.%; Mn: 0.24 wt.%; Ti: 0.28 wt.%; V: 0.1 wt.%; Zr: 0.12 wt.%; Cd: 0.15 wt.%; B: 0.01 wt.%; Si: 0.05 wt.%; with the balance being Al. The mass ratio of wire B to aluminum-copper alloy is 1.5:76.5; The mechanical stirring is performed at a speed of 350 r / min for 8 minutes. The ultrasonic treatment had a frequency of 19.8 kHz and a duration of 10 minutes. The casting process involves pouring at 720°C, preheating the mold at 220°C, and a pouring speed of 0.2 kg / s. The T6 heat treatment is as follows: holding at 530℃ for 14 hours, followed by water quenching at 60℃; then holding at 170℃ for 10 hours, and air cooling to room temperature; In this embodiment, the nanoparticle-reinforced high-strength, high-toughness, and heat-resistant cast aluminum-copper alloy 3 has a uniformly distributed nanoparticle structure, with nano-ceramic particles accounting for 0.15 wt.% and having a size of 75-95 nm. Figure 1It can be seen that its yield strength, tensile strength, and fracture strain at 200℃ are 215MPa, 350MPa, and 18.1%, respectively; Figure 4 Scanning electron microscopy (SEM) images show that the nano-ceramic particles are dispersed within the aluminum matrix, effectively eliminating agglomeration. The grains are significantly refined into a uniform fine-grained structure, and the precipitates at the grain boundaries are distributed in a dot-like pattern. These uniformly dispersed nanoparticles not only strongly pin dislocations but also stabilize the high-density substructure within, effectively hindering grain boundary sliding and crack propagation at high temperatures. Comparative Example 1

[0028] Traditional aluminum-copper cast aluminum alloys are prepared using the following steps: After melting the aluminum-copper alloy at 820℃, the slag is removed and the casting is completed. The resulting casting is then subjected to T6 heat treatment to obtain the cast aluminum-copper alloy. The aluminum-copper alloy composition, by weight percentage, is: Cu: 4.4 wt.%; Mn: 0.36 wt.%; Ti: 0.17 wt.%; V: 0.23%; Zr: 0.08 wt.%; Cd: 0.25%; B: 0.05%; Si: 0.08 wt.%; balance Al; The casting process involves pouring at 740°C, preheating the mold at 260°C, and using a pouring speed of 0.2 kg / s. The T6 heat treatment involves holding at 540℃ for 11 hours, followed by water quenching at 80℃; then holding at 180℃ for 7 hours, and air cooling to room temperature.

[0029] The cast aluminum-copper alloy prepared in Comparative Example 1 differs from that in Example 1 in that it did not contain nanoparticles; all other process parameters were the same. Figure 1 It can be seen that the yield strength, tensile strength, and fracture strain of Comparative Example 1 at 200℃ are 185MPa, 318MPa, and 12.8%, respectively; Figure 5 It can be seen that the microstructure of the cast aluminum-copper alloy obtained in Comparative Example 1 is relatively coarse, the size of the second phase precipitated at the grain boundaries is large, and it exhibits a continuous or semi-continuous network distribution, which easily leads to stress concentration and microcracks.

[0030] Compared with Comparative Example 1, the nanoparticle-reinforced high-strength, high-toughness, and heat-resistant cast aluminum-copper alloy obtained in Example 1 of this invention exhibits significantly improved strength and plasticity at high temperatures. Its yield strength (198 MPa), tensile strength (343 MPa), and fracture strain (14.9%) are significantly higher than those of the matrix alloy without added nanoparticles (185 MPa, 318 MPa, and 12.8%, respectively). Furthermore, the microstructure of Example 1 shows smaller grain sizes compared to Comparative Example 1, with more uniform, dispersed, and fine distribution of second-phase particles precipitated at grain boundaries, thus significantly reducing the risk of early cracking due to stress concentration. In terms of mechanical properties, compared with Comparative Example 1, the yield strength (198 MPa), tensile strength (343 MPa), and fracture strain (14.9%) of the nanoparticle-reinforced high-strength, high-toughness, and heat-resistant cast aluminum-copper alloy prepared in Example 1 are all significantly and simultaneously improved, successfully breaking the traditional mutual constraint of "increased strength, decreased plasticity" and "decreased strength, increased plasticity" in metallic materials.

[0031] Table 1. Yield strength, tensile strength, and elongation at break of the Examples and Comparative Example 1 Comparative Example 2

[0032] Sun et al. published an article in the Journal of Alloys and Compounds, Volume 1034, entitled "Enhancement of high-temperature properties of WA-DED 205A aluminum alloy via the addition of nickel." They improved the high-temperature properties of 205A aluminum alloy produced by arc-directed energy deposition by adding 0.32% Ni. After T6 heat treatment, the 205A(Ni) grains exhibited better stability. This was attributed to the formation of a high-temperature heat-resistant phase γ (Al7Cu4Ni) during solidification, which effectively suppressed grain boundary migration and grain growth, thus significantly improving high-temperature performance. At an operating temperature of 200℃, the transverse and longitudinal ultimate tensile strengths of the WA-DED 205A(Ni) alloy were 331 MPa and 335 MPa, respectively, with a fracture strain ≤8%.

[0033] Compared with Comparative Example 2, the nanoparticle-reinforced high-strength, high-toughness, and heat-resistant cast aluminum-copper alloy prepared by this invention exhibits superior comprehensive mechanical properties and structural stability. First, the content of nanoparticles added in this invention is ≤0.15wt%, which is far lower than the 0.32% Ni element added in Comparative Example 2, and the cost of the elements used is also lower. Second, Comparative Example 2 uses arc-directed energy deposition to prepare aluminum-copper alloys, which includes substrate treatment, arc-layer deposition, multi-stage solution treatment and aging, etc. The process control is complex and the equipment and manufacturing costs are high. In contrast, this invention does not use the additive manufacturing process and complex processes such as multi-stage solution treatment and aging as in Comparative Example 2. Instead, it uses a single-stage solution treatment and aging process. Compared with Comparative Example 2, this invention greatly simplifies the process and significantly reduces manufacturing costs. In addition, compared with Comparative Example 2, which improves the high-temperature performance of the alloy by alloying to generate a coarse heat-resistant phase, this invention utilizes the heterogeneous nucleation effect of nanoparticles to significantly refine the grains, pin dislocations, reduce the secondary dendrite spacing, refine the second phase, and improve the high-temperature strength and plasticity of the alloy in multiple ways. Therefore, Comparative Example 2 has higher costs, more complex processes, and lower high-temperature strength and plasticity than this invention. Experimental results show that at 200℃, the tensile strengths of the alloys in Examples 1-3 reached 343MPa, 340MPa, and 350MPa, respectively, which are significantly higher than the highest tensile strength of 335MPa in Comparative Example 2. Meanwhile, the elongation of the alloys in the examples can reach 18.1%, which is significantly higher than that of Comparative Example 2 (≤8%), achieving a synergistic improvement in strength and plasticity under high-temperature service conditions.

[0034] In summary, compared with existing technologies that add more than 0.3% Ni and other alloying elements, as well as traditional cast aluminum-copper alloys, this invention, by adding trace amounts (≤0.15%) of nanoparticles, and without employing high-cost metal elements such as rare earth elements and Ni, or additive manufacturing processes such as substrate treatment, arc deposition, multi-stage solution treatment, and aging, significantly improves the service performance of aluminum-copper alloys at 200°C, while also offering a simpler process and lower raw material production costs. Its core mechanism lies in the dispersed distribution of nanoparticles within the alloy, effectively pinning dislocations, and suppressing grain coarsening at high temperatures through a higher proportion of substructure-stabilizing phases. Therefore, it not only significantly improves the strength and plasticity of the cast aluminum-copper alloy matrix, but also, compared with traditional strengthening methods such as alloying, avoids the formation of coarse second phases and the resulting strength reduction, decreases the secondary dendrite spacing, and ensures that the second-phase particles precipitated at grain boundaries are more uniformly, dispersed, and fine, thus achieving a better synergistic improvement in strength and plasticity. Compared with traditional cast aluminum-copper alloy matrices, the high-strength, high-toughness, and heat-resistant cast aluminum-copper alloy prepared by this invention exhibits yield strength, tensile strength, and elongation at break at 200℃ increased by up to 16.2%, 10.1%, and 41.4%, respectively. Compared with alloying methods involving the addition of elements such as Ni, tensile strength and plasticity are increased from 335 MPa and 8% to 350 MPa and 18%, respectively. Compared with existing technologies, this invention does not use high-cost metal elements such as rare earth elements and Ni, simplifying the heat treatment process. For example, it eliminates the need for multi-stage solution treatment and aging, thus reducing raw material production costs. Furthermore, existing technologies improve the high-temperature strength and plasticity of alloys through single approaches such as generating coarse, high-temperature heat-resistant phases. In contrast, this invention achieves improved high-temperature strength and plasticity by synergistically controlling the microstructure through multiple approaches, including grain refinement, dislocation pinning, reducing secondary dendrite spacing, and reducing second-phase particle size. This breakthrough overcomes the technical bottleneck of simultaneously improving high-temperature strength and plasticity in existing technologies.

[0035] Furthermore, the raw material ratios and process parameter ranges differ in each embodiment of the present invention, resulting in different final performance. This demonstrates that the optimal effect obtained by the present invention is not determined by a certain component or process, but is achieved through the interaction of components, ratios, processes, and synergistic regulation of process parameters. Only within the scope of protection of the claims of the present invention can the optimal technical effect be achieved.

Claims

1. A high-strength, high-toughness, heat-resistant cast aluminum-copper alloy reinforced with nanoparticles, characterized in that... Its preparation method includes the following steps: (1) Niobium-titanium-aluminum alloy powder, BN powder and carbon powder are mixed at a mass ratio of 64-86:12-18:1-5 at a rotation speed of 20-80 r / min for 13-23 hours to obtain powder mixture 1; then powder mixture 1 is coated with pure aluminum strip to obtain wire A, wherein the mass ratio of powder mixture 1 to pure aluminum strip is 70-90:15-25; wire A is heated to 900-1050℃ to form a melt, and then the melt is mixed with pure aluminum liquid, mechanically stirred and ultrasonically treated, and finally cast and rolled into intermediate alloy wire B containing nano-ceramic particles; The mechanical stirring is performed for 5-15 minutes at a speed of 300-600 r / min. The ultrasonic treatment lasts for 10-20 minutes and has a frequency of 18-21 kHz. The casting and rolling process involves a rolling temperature of 350-450℃ and a rolling speed of 0.1-0.3 m / s. The particle size of the niobium-titanium-aluminum alloy powder is 10 micrometers to 80 micrometers, the particle size of the BN powder is 1 micrometer to 10 micrometers, and the particle size of the carbon powder is 15 micrometers to 100 micrometers. The mass ratio of the melt to the pure aluminum liquid is 1-5:15-25; The proportion of nano-ceramic particles in the intermediate alloy wire B is 5wt.%-10wt.%. (2) After melting the aluminum-copper alloy at 730-830℃, add the preheated intermediate alloy wire B from step (1). After the intermediate alloy wire B is completely melted, a mixed melt is obtained. Then, the mixed melt is subjected to mechanical stirring, ultrasonic treatment, slag removal, settling, casting molding process and T6 heat treatment to obtain a high-strength, high-toughness, heat-resistant cast aluminum-copper alloy reinforced with nanoparticles. The aluminum-copper alloy, by weight percentage, mainly comprises: Cu: 4.2 wt.% - 5.2 wt.%; Mn: 0.2 wt.% - 0.5 wt.%; Ti: 0.15 wt.% - 0.35 wt.%; V: 0.05 wt.% - 0.3 wt.%; Zr: 0.05 wt.% - 0.15 wt.%; Cd: 0.1 wt.% - 0.3 wt.%; B: 0.005 wt.% - 0.06 wt.%; Si: ≤0.1 wt.%; with the balance being Al. The mass ratio of wire B to aluminum-copper alloy is 0.5-2:50-150; The mechanical stirring is performed at a speed of 200-500 r / min for 3-10 minutes. The ultrasonic treatment has a frequency of 19-21 kHz and a duration of 1-15 minutes. The casting process involves pouring at 710-740℃, preheating the mold at 220-280℃, and pouring at a speed of 0.15-0.35 kg / s. The T6 heat treatment involves holding at 530-540℃ for 10-14 hours, followed by water quenching at 60-80℃; then holding at 170-180℃ for 6-10 hours, and air cooling to room temperature. The nanoparticle-reinforced high-strength, high-toughness, heat-resistant cast aluminum-copper alloy achieves a synergistic improvement in strength and plasticity at high temperatures; at 200℃, the tensile strength is ≥340 MPa, the yield strength is ≥198 MPa, and the fracture strain is ≥13.2%, which contains nano-ceramic particles with a mass percentage of ≤0.15% and a particle size of 60-100 nm.

2. The nanoparticle-reinforced high-strength, high-toughness, heat-resistant cast aluminum-copper alloy according to claim 1, characterized in that, Niobium-titanium-aluminum alloy powder, BN powder and carbon powder are mixed at a mass ratio of 70-80:14-16:2-4 and a rotation speed of 40-60 r / min for 15-18 hours to obtain powder mixture 1.

3. The nanoparticle-reinforced high-strength, high-toughness, heat-resistant cast aluminum-copper alloy according to claim 1, characterized in that, The powder mixture 1 is coated with pure aluminum strip to obtain wire A, wherein the mass ratio of the powder mixture 1 to the pure aluminum strip is 75-85: 16-23.

4. The high-strength, high-toughness, heat-resistant cast aluminum-copper alloy reinforced with nanoparticles according to claim 1, characterized in that, After heating wire A to 950-1000℃ to form a melt, the melt is mixed with pure aluminum liquid, mechanically stirred and ultrasonically treated, and finally cast and rolled into intermediate alloy wire B containing nano-ceramic particles. The proportion of nano-ceramic particles in intermediate alloy wire B is 6wt.%-8wt.%.

5. The nanoparticle-reinforced high-strength, high-toughness, heat-resistant cast aluminum-copper alloy according to claim 1, characterized in that, In step (1), the particle size of the niobium-titanium-aluminum alloy powder is 15 micrometers to 50 micrometers, the particle size of the BN powder is 2 micrometers to 8 micrometers, and the particle size of the carbon powder is 20 micrometers to 80 micrometers.

6. The nanoparticle-reinforced high-strength, high-toughness, heat-resistant cast aluminum-copper alloy according to claim 1, characterized in that, In step (1), the mechanical stirring time is 8-12 minutes and the rotation speed is 400-550 r / min; the ultrasonic treatment time is 13-18 minutes and the frequency is 18.6-20.3 kHz; the rolling temperature is 360-410℃ and the rolling speed is 0.17-0.23 m / s.

7. The nanoparticle-reinforced high-strength, high-toughness, heat-resistant cast aluminum-copper alloy according to claim 1, characterized in that, Step (2) After melting the aluminum-copper alloy matrix at 760-820℃, add the preheated intermediate alloy wire B from step (1). After the intermediate alloy wire B is completely melted, a mixed melt is obtained. Then, the mixed melt is subjected to mechanical stirring, ultrasonic treatment, slag removal, settling, casting molding process, and T6 heat treatment to obtain a high-strength, high-toughness, heat-resistant cast aluminum-copper alloy reinforced with nanoparticles.

8. The nanoparticle-reinforced high-strength, high-toughness, heat-resistant cast aluminum-copper alloy according to claim 1, characterized in that, In step (2), the mechanical stirring time is 5-7 minutes and the rotation speed is 300-450 r / min; the ultrasonic treatment time is 3-12 minutes and the frequency is 19.8-20.2 kHz.

9. The nanoparticle-reinforced high-strength, high-toughness, heat-resistant cast aluminum-copper alloy according to claim 1, characterized in that, The composition of the cast aluminum-copper alloy mentioned in step (2) mainly includes: Cu: 4.4wt.%-5.1wt.%; Mn: 0.22wt.%-0.4wt.%; Ti: 0.16wt.%-0.3wt.%; V: 0.1wt.%-0.25wt.%; Zr: 0.07wt.%-0.12wt.%; Cd: 0.15wt.%-0.25wt.%; B: 0.01wt.%-0.05wt.%; Si: ≤0.08wt.%; with the balance being Al.

10. The nanoparticle-reinforced high-strength, high-toughness, heat-resistant cast aluminum-copper alloy according to claim 1, wherein the nanoparticle-reinforced high-strength, high-toughness, heat-resistant cast aluminum-copper alloy achieves synergistic improvement in strength and plasticity at high temperature; at 200℃, the tensile strength is 340-350MPa, the yield strength is 198-215MPa, and the fracture strain is 13.2-18.1%, wherein it contains nano-ceramic particles, the proportion of which is 0.05wt.%-0.15wt%, and the particle size is 70-90nm.

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