Aluminum matrix composite material continuously precipitating heat-resistant strengthening phase during high temperature service and method of making

Abstract

This invention discloses an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service and its preparation method. At room temperature, the composite material comprises a nanocrystalline aluminum alloy matrix, heat-resistant nanoparticle reinforcing phases at grain boundaries, and an intracrystalline heat-resistant strengthening phase. Under high-temperature service conditions, a large amount of the heat-resistant strengthening phase, highly coherent with the aluminum alloy matrix, continuously precipitates within the matrix. Through the combined action of a triple strengthening mechanism—nanocrystalline strengthening, grain boundary pinning strengthening of the heat-resistant nano-oxide phase and the heat-resistant nano-intermetallic compound phase, and continuous precipitation strengthening of the intracrystalline nanocluster structure—the material maintains sustained high-temperature strength during service at 200-400°C. Simultaneously, the nanocrystalline structure exhibits strong coordinated deformation capability, and the intracrystalline precipitated nanocluster structure is highly coherent with the matrix. Under the combined action of these two toughening mechanisms, the material displays good plasticity and toughness between room temperature and 400°C.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, specifically to an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service and its preparation method. Background Technology

[0002] Aluminum alloys, as lightweight structural materials, possess excellent specific strength, corrosion resistance, and ease of processing and forming, making them widely used in aerospace, transportation, and other fields. Most aluminum alloys are precipitation-strengthened alloys, their strengthening mechanism primarily involving the large-scale dispersion of a second phase in the matrix, effectively hindering dislocation and grain boundary movement. However, at temperatures of 200°C or higher, the precipitated phase rapidly coarsens, drastically reducing its ability to hinder dislocation and grain boundary movement, leading to a sharp decline in strengthening effect. Currently, the service temperature of most commercially available medium-to-high strength aluminum alloys is generally limited to 200°C. Further increasing the service temperature of aluminum alloys is of great significance for expanding the application areas of medium-to-high strength aluminum alloys.

[0003] Currently, heat-resistant aluminum materials can be broadly classified into two categories: heat-resistant aluminum alloys and heat-resistant aluminum-based composite materials. Heat-resistant aluminum alloys mainly include three types. The first type is heat-resistant aluminum alloys with modified precipitates, typically Al-Cu-Mg-Ag alloys. By utilizing the segregation of Mg and Ag to the interface between the Ω phase (Al2Cu) and the matrix, the growth of the Ω phase can be significantly suppressed, but its service temperature generally does not exceed 250℃. The second type is aluminum alloys reinforced with heat-resistant precipitates, typically L12 phase-reinforced rare-earth aluminum alloys. By introducing slowly diffusing rare-earth element X, L12-Al3X nanophases or ternary or quaternary composite L12 structures with good thermal stability are formed during aging, increasing the alloy's service temperature to 300–350℃. However, the solid solubility of rare-earth element X in the aluminum matrix is ​​extremely limited, resulting in a low number density of precipitated L12 phases, leading to low room temperature and high-temperature strength of the alloy. The third type is heat-resistant eutectic aluminum alloys, including Al-Si, Al-Ce, Al-Fe, Al-Ni, and Al-Fe-Ni. Common characteristics of eutectic phases include high melting points and stable size and structure within the aluminum matrix. However, they are hard, brittle, and coarse (several micrometers or even larger). Furthermore, the content of elements forming the eutectic phase is generally high, leading to poor alloy ductility and toughness. Unlike the above types of heat-resistant aluminum alloys, heat-resistant aluminum-based composites achieve strengthening by directly introducing high-melting-point ceramic reinforcements (such as nitrides, carbides, borides, and oxides) that are insoluble in the aluminum matrix to pin grain boundaries, restricting grain growth and intragranular dislocation activation. The strength and toughness of this material heavily depend on the size and amount of the ceramic reinforcement. When the reinforcement size is large (e.g., several micrometers to tens of micrometers), a high content (10 wt.% or even higher) is often required to achieve the strengthening effect, but this often severely compromises the material's ductility and toughness. When the size of the reinforcement is reduced to the nanoscale, only a small amount (0.5-5 wt.%) is needed to achieve a significant strengthening effect and maintain a certain degree of plasticity and toughness. However, the nanoscale reinforcement is mainly distributed on the grain boundaries and is difficult to disperse evenly, which limits the plasticity and toughness of the material.

[0004] In particular, the microstructure and thermal stability of current major heat-resistant aluminum materials remain limited, with long-term service temperatures not exceeding 300–350℃. When the temperature exceeds 300–350℃, intragranular precipitates dissolve back, easily leading to dislocation recovery and substructure degradation; grain boundary grains coarsen, and grains grow continuously; precipitation strengthening and grain boundary strengthening mechanisms at room temperature fail, causing the material to soften rapidly. Currently, there are no heat-resistant aluminum materials, either domestically or internationally, capable of "long-term stability" at 400℃.

[0005] A search revealed Chinese patent CN110747380A, which discloses a nano-ceramic particle-reinforced aluminum matrix composite material and its preparation method. The composite material is obtained by mixing and ball-milling nano-ceramic particles with aluminum matrix powder, followed by semi-solid sintering. The high-density stacking faults / microtwins in the composite material enable it to achieve high strength at 400℃. However, without nano-phase pinning, the high-density stacking faults / microtwins only maintain high strength for a short time at 400℃. The measured stress continuously decreased during compressive deformation at temperatures between 200-400℃, indicating rapid degradation of the stacking faults / microtwins at high temperatures. Due to the continuous softening of the material, it cannot maintain high strength persistently at temperatures between 200-400℃. Secondly, the inventors completely disregarded the design of the material's plasticity and toughness. The material matrix has a coarse-grained structure, with a large number of nano-ceramic particles (up to 40% by volume) completely distributed on the grain boundaries. This results in extremely low grain boundary strength, indicating that the material has poor high-temperature plasticity and toughness and almost no plasticity and toughness at room temperature. This may be the reason why the authors did not provide room-temperature compressive stress-strain curves.

[0006] A search revealed Chinese patent CN 110331316 A, which discloses a high-strength, heat-resistant graphene composite conductor material and its preparation method. This patent utilizes oxygen naturally introduced during ball milling to generate an amorphous Al2O3 phase through in-situ reaction, achieving precipitation strengthening. However, relying on the randomness of naturally introduced oxygen and the inability to precisely control the amount of oxides generated results in poor batch stability of the material's microstructure and properties, making it difficult to apply in actual production. Furthermore, the amorphous Al2O3 phase lacks a definite atomic structure and physicochemical properties, exhibiting particularly insufficient thermal stability; it is prone to changes or crystallization at high temperatures, preventing long-term stable operation in high-temperature service environments. Moreover, this patent does not include research and testing on the material's high-temperature performance.

[0007] A search revealed Chinese patent CN 107099687 A, which discloses a method for preparing boron carbide particle-reinforced nano / ultrafine-crystalline aluminum-based composite materials. This patent emphasizes that the instability of nanocrystals makes them prone to growth at high temperatures, thus necessitating rapid heating of the sample using spark plasma technology. However, this rapid heating and sintering easily leads to insufficient material density (93.9-99.3%) and poor plasticity / toughness. The material cracks and fails when the true strain is below 8%, severely limiting its practical applications. More importantly, nanocrystals obtained through rapid sintering at low temperatures for a short time cannot maintain dimensional stability under prolonged high temperatures; the nanocrystals coarsen rapidly, leading to a rapid loss of material strength, making it unsuitable for long-term high-temperature service environments. Furthermore, this patent does not include any research or testing of the material's high-temperature performance.

[0008] A search revealed Chinese patent CN 113186418 A, which discloses a method for preparing a nano-Al2O3-reinforced aluminum matrix composite material. This patent argues that the content of the process control agent has a significant impact on the dispersibility of the nano-reinforcing particles and emphasizes the necessity of adding the process control agent in batches. This requirement necessitates repeated interruptions of the ball milling process in actual production, making the entire process extremely cumbersome and time-consuming (up to 50 hours), hindering practical application. Furthermore, the composite material uses 6061 aluminum alloy as the matrix, and the main precipitated phases (β and β') have poor thermal stability, causing the matrix to soften rapidly at high temperatures, making it unsuitable for long-term high-temperature service environments. Moreover, the patent does not include any research or testing on the material's high-temperature performance.

[0009] A search revealed Chinese patent CN 113667879 A, ​​which discloses an aluminum-based composite material reinforced by both Al2O3 and AlB2, and its preparation method. In this patent, both nano-sized Al2O3 and submicron-sized AlB2 are generated in situ, effectively addressing the dispersion issue and significantly improving the material's elastic modulus. However, the formed nano-Al2O3 and submicron-sized AlB2 phases are distributed along the grain boundaries, while the matrix is ​​submicron-sized, and no precipitated phases are introduced into the grains for reinforcement. This results in low room temperature and high temperature strength, and poor subsequent processing and formability. Furthermore, the patent does not include any research or testing on the material's high-temperature performance. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention provides an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service, and its preparation method. This enables the aluminum-based composite material to possess both excellent high-temperature strength and good ductility and toughness during long-term service at 200-400℃. The technical solution adopted by this invention is as follows:

[0011] A heat-resistant strengthening phase is continuously precipitated in an aluminum-based composite material during high-temperature service, wherein the high-temperature service refers to service at 200-400℃. The composite material is characterized in that, at room temperature, it comprises a nanocrystalline aluminum alloy matrix, heat-resistant nanoparticle reinforcing phases at grain boundaries, and an intracrystalline heat-resistant strengthening phase. The heat-resistant nanoparticle reinforcing phase comprises heat-resistant nano-oxide phases and heat-resistant nano-intermetallic compound phases, which are uniformly distributed at the grain boundaries of the nanocrystalline matrix. The heat-resistant strengthening phase is a nanocluster structure. When the aluminum-based composite material is placed under the high-temperature service conditions, the aluminum... The alloy matrix can continuously precipitate a large amount of heat-resistant strengthening phases that are highly coherent with the aluminum alloy matrix. Under the combined action of the triple strengthening mechanism of nanocrystalline strengthening, grain boundary pinning strengthening of heat-resistant nano-oxide phase and heat-resistant nano-intermetallic compound phase, and continuous precipitation strengthening of intracrystalline nanocluster structure, the aluminum matrix composite material can maintain high-temperature strength during service at 200-400℃. At the same time, the nanocrystalline structure has strong coordinated deformation ability and the intracrystalline precipitated nanocluster structure is highly coherent with the matrix. Under the combined action of these two toughening mechanisms, the aluminum matrix composite material exhibits good plasticity / toughness between room temperature and 400℃, and has good subsequent processing and formability.

[0012] Furthermore, the nanocluster structure is an AlCO-rich phase with a structural size of less than 20 nm and a number density of 1 × 10⁻⁶. 14 ~5×10 14 pcs / m 2 .

[0013] Furthermore, the aluminum-based composite material can maintain its high-temperature strength for at least 1000 hours during service at 200-400°C.

[0014] Furthermore, the aluminum alloy matrix is ​​selected from binary or multi-component aluminum alloys capable of forming the heat-resistant nano-intermetallic compound phase.

[0015] Furthermore, the aluminum alloy matrix contains one or more of the elements Zr, Hf, Ti, V, Nb, Y, Sc, or Er.

[0016] Furthermore, the heat-resistant nano-oxide phase is a rare earth / near rare earth or transition metal oxide phase with high melting point and high thermal stability, which does not re-dissolve in the aluminum alloy matrix even during service at 400°C for more than 1000 hours.

[0017] Furthermore, the heat-resistant nano-oxide phase is one or more of Y2O3, Al2O3, CeO2, TiO2, HfO2, SiO2, ZrO2, or Y-Ti-O, Y-Zr-O, Y-Si-O, Y-Ce-O, Y-Al-O, and Y-Hf-O.

[0018] Furthermore, the heat-resistant nano-intermetallic compound phase is an intermetallic compound phase with high thermal stability and containing rare earth / near rare earth or transition metal elements with extremely slow diffusion rate, which does not re-dissolve in the aluminum alloy matrix even during service at 400°C for more than 1000 hours.

[0019] Furthermore, the heat-resistant nano-intermetallic compound phase has a D0... 23 Al3Zr or Al3Hf with structure D0 22 Al3Ti, Al3V, or Al3Nb structures have D0 19 One or more of the following: Al3Y with an L12 structure, Al3Sc or Al3Er with an L12 structure, or a composite structure phase formed therefrom.

[0020] Furthermore, a method for preparing an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service is also provided, comprising the following steps:

[0021] Step S1, Pretreatment: The aluminum alloy matrix powder is prepared by vacuum melting and gas atomization, with a powder particle size of less than 150 μm. The aluminum alloy is selected with a specific gravity of 2.62–2.73 g / cm³. 3 Binary or multi-element aluminum alloys.

[0022] Step S2, preparing critically supersaturated nanocrystalline structure by ball milling: 0.5-2 wt.% heat-resistant nano-oxide particles are added to the aluminum alloy matrix powder, and ethanol is added as a process control agent. The powder is then mixed and ball-milled in a ball mill for 14-30 hours. The intense plastic deformation caused by ball milling continuously refines the grains of the aluminum alloy matrix. This allows the heat-resistant nano-oxide particles to partially dissolve back into the aluminum alloy matrix, obtaining the critically supersaturated nanocrystalline structure. The heat-resistant nano-oxide particles are refined while achieving uniform dispersion.

[0023] Step S3, densification treatment: The powder obtained in step S2 is cold-pressed into a blank, placed in a sleeve and vacuumed, and densified by discharge plasma sintering / hot pressing sintering / hot extrusion / hot isostatic pressing to obtain a shaped block; during the thermal densification process, the heat-resistant intermetallic compound phase precipitates, and the grain boundaries of the critically supersaturated nanocrystalline structure are effectively pinned by the heat-resistant nano-oxide phase and the heat-resistant intermetallic compound phase; at the same time, solute atoms in the critically supersaturated nanocrystalline structure undergo desolvation, and a small amount of the nanocluster structure begins to precipitate in the crystal.

[0024] Step S5, Service at 200-400℃: The molded block is placed under continuous heat exposure conditions of 200-400℃. A large number of nanoclusters highly coherent with the aluminum alloy matrix continue to precipitate within the molded block; thus, an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service is obtained. The physical specific gravity of the obtained aluminum-based composite material is <2.73 g / cm³. 3 .

[0025] Furthermore, the critically supersaturated nanocrystalline structure refers to a critical state where the nanocrystals have just reached supersaturation but are sufficiently supersaturated. Only when the critical state is reached can the nanocrystals have the ability to continuously precipitate during service at 200-400°C, and the precipitation rate is appropriate.

[0026] Furthermore, in step S2, the ball milling equipment is an omnidirectional planetary ball mill, equipped with a compressor for auxiliary cooling. The ball mill speed is 150–300 rpm, the ball-to-material mass ratio is 4–10:1, the ball milling time is 14–20 hours, and after each ball milling session of 15–30 minutes, the machine is stopped for 5–10 minutes and the forward and reverse directions are changed.

[0027] Furthermore, in step S3, discharge plasma sintering is used for molding, with a pressure of 40-100 MPa, a holding time of 4-10 min, and a temperature of 450-550 °C.

[0028] Further, in step S3, the cold pressing is performed in a cold press at a pressure of 20–40 MPa for 1–2 hours; the cladding is evacuated to a vacuum degree of 2 × 10⁻⁶. -3 Pa.

[0029] Furthermore, in step S3, the hot isostatic pressing sintering method has a pressure of 150-200 MPa, a holding time of 4-6 h, and a temperature of 400-600 °C.

[0030] The preparation principle and heat resistance mechanism of this invention are as follows: Lightweight aluminum alloy powder is prepared, mixed with nano-oxide particles and a process control agent, and subjected to intense plastic deformation by ball milling to obtain a lightweight nanocrystalline alloy matrix, while simultaneously refining and dispersing the nano-oxide particles. The refined nano-oxide particles are dispersed on the nanocrystalline grain boundaries, and together with the intermetallic compound phase with good thermal stability precipitated during the subsequent thermal densification process, they pin the grain boundaries, making it difficult for the grain boundaries to migrate and effectively inhibiting the growth of nanocrystals. Furthermore, during thermal densification and thermal exposure, highly coherent nanocluster structures can be continuously precipitated within the grains, pinning dislocation movement. The triple strengthening mechanism of nanocrystalline strengthening, biphase grain boundary pinning strengthening, and continuous precipitation strengthening within the grains works together to enable the material strength to remain stable at high temperatures for a long time. At the same time, the strong coordinated deformation ability of the nanocrystalline structure and the high coherence between the nanocluster structures precipitated within the grains and the matrix, these two toughening mechanisms work together to enable the composite material to also obtain excellent plasticity and toughness. Strict control of the ball milling time is crucial to obtaining the critically supersaturated nanocrystalline structure, which refers to a state of just reaching supersaturation but being sufficiently supersaturated. Only by reaching this critical state can the nanocrystalline structure maintain continuous precipitation capability and an appropriate precipitation rate during long-term service at 400°C. Based on the above preparation principle and heat resistance mechanism, the heat-resistant nanocrystalline aluminum-based composite material has been experimentally verified to achieve excellent strength and toughness at 400°C and maintain performance stability for at least 1000 hours.

[0031] The beneficial effects of this invention are:

[0032] 1. The aluminum-based composite material designed in this invention has a triple strengthening mechanism of nanocrystal reinforcement, grain boundary pinning, and continuous precipitation of intracrystalline nanocluster structures, which ensures that the aluminum-based composite material can maintain high-temperature strength during long-term service at 400℃; at the same time, the nanocrystals have strong coordinated deformation ability and the intracrystalline precipitated nanocluster structures are highly coherent with the matrix. Under the combined effect of these two toughening mechanisms, the aluminum-based composite material exhibits good plasticity / toughness between room temperature and 400℃.

[0033] 2. The aluminum-based composite material designed in this invention can continuously precipitate highly coherent nanocluster structures within the nanocrystals during 400℃ heat exposure, effectively pinning dislocation movement and reducing stress concentration caused by local deformation gradients. This ability to continuously precipitate strengthening phases within the grains under high-temperature service conditions is unprecedented.

[0034] 3. The critically supersaturated nanocrystalline structure of the present invention is a critical state structure obtained by controlling the ball milling time. This critically supersaturated nanocrystalline structure provides a strong guarantee for the continuous precipitation of the nanocluster structure during long-term service at 400°C.

[0035] 4. The aluminum-based composite material designed in this invention, wherein grain boundary pinning reinforcement includes heat-resistant nano-oxide phase and heat-resistant nano-intermetallic compound phase, which do not re-dissolve in the aluminum alloy matrix even during service at 400°C for more than 1000 hours, i.e., the "heat-resistant" nano-oxide phase and the "heat-resistant" nano-intermetallic compound phase, because most nano-precipitated phases will re-dissolve at a high temperature of 400°C.

[0036] 5. The aluminum-based composite material designed in this invention can achieve a high room temperature yield strength of 440 MPa and a yield strength of 120 MPa at 400℃, and has good processability (stable compression reduction of 70% without cracking); at 400℃

[0037] After 1000 hours of continuous exposure, the hardness and strength remained basically stable, confirming that the microstructure and properties have extremely high thermal stability.

[0038] 6. The alloying elements used in this invention are low in cost, lightweight, and present in small quantities. The resulting aluminum-based composite material is also lightweight, with a physical specific gravity of less than 2.73 g / cm³. 3 . Attached Figure Description

[0039] To more clearly illustrate the technical implementation effects of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 The inverse pole figure (IPF) and the size distribution statistics of aluminum grains of the aluminum-based composite material prepared in Example 1 of the present invention are shown.

[0041] Figure 2 The first set of scanning transmission electron micrographs (STEM) images and corresponding elemental distributions of the aluminum-based composite material prepared in Example 1 of the present invention;

[0042] Figure 3 The second set of scanning transmission electron microscopy (STEM) images and corresponding elemental distributions of the aluminum-based composite material prepared in Example 1 of this invention;

[0043] Figure 4 The true stress-strain curves of the aluminum-based composite material prepared in Example 1 of this invention are shown at room temperature and high temperature.

[0044] Figure 5 The room temperature and high temperature compressive yield strengths of the aluminum-based composite material prepared in Example 1 of this invention and aluminum and heat-resistant aluminum alloys reported in other literature are shown.

[0045] Figure 6 The micro Vickers hardness of the aluminum-based composite material prepared in Example 1 of this invention was measured after continuous heat exposure at 400°C for different times. Detailed Implementation

[0046] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be further described below.

[0047] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0048] The following specific embodiments illustrate in detail the aluminum-based composite material and its preparation method provided by the present invention.

[0049] Example 1

[0050] A method for preparing an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service includes the following steps:

[0051] Step S1, Pretreatment: Al-Zr-Y alloy powder (particle size less than 150 μm) was prepared by vacuum melting and gas atomization, wherein the Zr content was 0.2 wt.% and the Y content was 0.2 wt.%, and the physical specific gravity of the alloy powder was 2.71 g / cm³. 3 ;

[0052] Step S2, Powder Mixing and Ball Milling: 1 wt.% Y2O3 particles with a particle size less than 200 nm are added to the Al-Zr-Y alloyed powder; 3 wt.% ethanol is added as a process control agent; powder mixing and ball milling are carried out in a ball mill equipped with a compressor for auxiliary cooling, and the temperature is set to 0℃. The ball mill speed is 250 rpm, the ball-to-powder mass ratio is 8:1, the ball milling time is 16 h, and the mill is stopped for 5 min after every 15 min of ball milling, and the forward and reverse directions are changed; through intense plastic deformation, a supersaturated nanocrystalline structure is formed, and the nano-oxides are refined and uniformly dispersed;

[0053] Step S3, densification treatment: The powder after mechanical ball milling is cold-pressed into a blank, placed in a sleeve and vacuum-sealed, and densified by spark plasma sintering to obtain a shaped block. During the thermal densification process, the grain boundaries of the nanocrystals formed by ball milling are effectively pinned by a large number of uniformly dispersed nano-oxide particles; at the same time, the supersaturated [O], [Y], and [Zr] are desoluble, and nano-Y2O3 and D0 precipitate at the grain boundaries. 23 -Al3Zr phase; the nanocrystals have a particle size of 50-700 nm; D0 at the grain boundaries. 23 The particle size of the Al3Zr phase is 20–70 nm; the particle size of the nano-Y2O3 particles at the grain boundaries is 20–100 nm.

[0054] Step S4, 200-400℃ service: The molded block is placed under continuous heat exposure conditions of 200-400℃ for more than 1000 hours. A large number of highly coherent nanoclusters, rich in AlCO, continuously precipitate within the aluminum alloy matrix of the molded block. Thus, an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service is obtained, with a specific gravity of 2.70 g / cm³. 3 .

[0055] Figure 1 The inverse pole figure (IPF) and the size distribution statistics of aluminum grains of the aluminum-based composite material prepared in Example 1 of the present invention show that the matrix has a nanocrystalline structure with an average particle size of ~100 nm. Figure 2 The first set of scanning transmission electron micrographs (STEM) images and corresponding elemental distributions of the aluminum-based composite material prepared in Example 1 of this invention show the nano-oxide phase Y2O3 and the intermetallic compound phase D0 distributed on the nanocrystal boundaries. 23 -Al3Zr; Figure 3 The second set of scanning transmission electron microscopy (STEM) images and corresponding elemental distributions of the aluminum-based composite material prepared in Example 1 of the present invention show that a large number of highly coherent AlCO-rich nanoclusters are precipitated within the nanocrystals. Figure 4 The true stress-strain curves of the aluminum-based composite material prepared in Example 1 of the present invention at room temperature and high temperature show that the true strain during compression can reach 0.7. Figure 5 The room temperature and high temperature compressive yield strengths of the aluminum-based composite material prepared in Example 1 of the present invention and aluminum and heat-resistant aluminum alloys reported in other literature show that the aluminum-based composite material of Example 1 of the present invention has excellent mechanical properties in the range of 200 to 400°C. Figure 6The micro Vickers hardness of the aluminum-based composite material prepared in Example 1 of this invention was measured after continuous heat exposure at 400°C for different times, showing almost no change over 1000 hours. Table 1 shows the room temperature and high temperature compressive strength of the aluminum-based composite material prepared in Example 1 of this invention.

[0056] Table 1

[0057]

[0058] Example 2

[0059] A method for preparing an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service includes the following steps:

[0060] Step S1, Pretreatment: Al-Zr-Sc alloy powder (particle size less than 150 μm) was prepared by vacuum melting and gas atomization, wherein the Zr content was 0.4 wt.% and the Sc content was 0.2 wt.%, and the physical specific gravity of the alloy powder was 2.71 g / cm³. 3 ;;

[0061] Step S2, Powder Mixing and Ball Milling: 0.5 wt.% α-Al2O3 nanoparticles are added to the Al-Zr-Sc alloy powder, along with 3 wt.% ethanol as a process control agent. Ball milling is performed in an omnidirectional planetary ball mill to uniformly disperse Al2O3 within the alloy powder. A compressor is used for auxiliary cooling, with the temperature set to 0°C. The ball mill speed is 250 rpm, the ball-to-powder mass ratio is 8:1, and the milling time is 16 hours. After every 15 minutes of milling, the mill is stopped for 5 minutes, and the forward and reverse rotation directions are changed. This process involves intense plastic deformation to form a supersaturated nanocrystalline structure, refining the nano-oxides and ensuring uniform dispersion.

[0062] Step S3, densification treatment: The powder after mechanical ball milling is cold-pressed into a blank, placed in a sleeve and vacuum-sealed, and densified by hot isostatic pressing to obtain a shaped block. During the hot densification process, the grain boundaries of the nanocrystals formed by ball milling are effectively pinned by a large number of uniformly dispersed nano-Al2O3 particles; at the same time, the supersaturated [O], [Sc], and [Zr] are desoluble, and nano-Al2O3 and L12-Al3(Sc,Zr) composite phases precipitate at the grain boundaries; the particle size of the nanocrystals is 50-400 nm; the particle size of the L12-Al3(Sc,Zr) phase at the grain boundaries is 20-70 nm; and the particle size of the nano-Al2O3 particles at the grain boundaries is 20-100 nm.

[0063] Step S4, Long-term service at 200-400℃: The molded block is placed under continuous heat exposure conditions of 200-400℃ for more than 1000 hours. A large number of highly coherent nanoclusters, rich in AlCO, continuously precipitate within the aluminum alloy matrix of the molded block. Thus, an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service is obtained, with a specific gravity of 2.71 g / cm³. 3 .

[0064] Example 3

[0065] A method for preparing an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service includes the following steps:

[0066] Step S1, Pretreatment: Al-0.35wt.%Fe-0.4wt.%Zr alloy matrix powder (particle size less than 300 mesh) was prepared by vacuum melting and gas atomization. The physical specific gravity of the alloy powder was 2.73 g / cm³. 3 ;

[0067] Step S2, Preparation of ternary nano-oxide powder: Y₂O₃ and TiO₂ powders with particle sizes of 20–100 nm are mixed at a molar ratio of 1:2, with 3 wt.% ethanol added as a process control agent. The mixture is ball-milled in an omnidirectional planetary ball mill at 300 r / min for 20–30 h. The milled powder is then removed and subjected to solid-state sintering at 1150–1200 °C for 5 h to obtain Y-Ti-O ternary nano-oxide, mainly Y₂Ti₂O₇.

[0068] Step S3, Powder Mixing and Ball Milling: 2 wt.% of nano-Y₂Ti₂O₇ particles are added to Al-0.35wt.%Fe-0.4wt.%Zr alloy powder, and mechanically ball-milled in an omnidirectional planetary ball mill to uniformly disperse Y-Ti-O within the micro-alloy powder. A compressor-assisted cooling system is used, with the temperature set to 0℃. The ball mill speed is 250 rpm, the ball-to-powder mass ratio is 8:1, and the ball milling time is 20 hours. After every 15 minutes of ball milling, the mill is stopped for 5 minutes, and the forward and reverse rotation directions are changed. This process induces a supersaturated nanocrystalline structure through intense plastic deformation, refining and uniformly dispersing the nano-Y₂Ti₂O₇ oxide.

[0069] Step S4, Densification Treatment: The powder after mechanical ball milling is cold-pressed into a blank, placed in a sleeve and vacuum-sealed, and then densified by hot extrusion to obtain a shaped block. During the hot densification process, the grain boundaries of the nanocrystals formed by ball milling are effectively pinned by a large number of uniformly dispersed nano-oxide particles. At the same time, the supersaturated solid dissolved in the matrix [Zr], [Y], and [O] undergo desolvation, and nano-Y2Ti2O7 and D0 precipitate at the grain boundaries. 23 -Al3(Zr,Fe) phase; the nanocrystals have a particle size of 50–200 nm; DO at the grain boundaries 23 The particle size of the Al3(Zr,Fe) phase is 20–60 nm; the particle size of the nano-Y2Ti2O7 at the grain boundaries is 20–80 nm.

[0070] Step S4, 200-400℃ service: The molded block is placed under continuous heat exposure conditions of 200-400℃ for more than 1000 hours. A large number of highly coherent nanoclusters, rich in AlCO, continuously precipitate within the aluminum alloy matrix of the molded block. Thus, an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service is obtained. The physical specific gravity of the aluminum-based composite material is 2.73 g / cm³. 3 .

[0071] Example 4

[0072] A method for preparing an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service includes the following steps:

[0073] Step S1, Pretreatment: Al-5wt.%Mg-0.4wt.%Si-0.4wt.%Zr powder (particle size less than 150μm) was prepared by vacuum melting and gas atomization. The physical specific gravity of the alloy powder was 2.63 g / cm³. 3 ;

[0074] Step S2, Preparation of Y-Zr-O ternary nano-oxides: Y₂O₃ and ZrO₂ powders with particle sizes of 20–100 nm were mixed at a molar ratio of 1:2, with 3 wt.% ethanol added as a process control agent. The mixture was then mechanically ball-milled in a planetary ball mill at 300 r / min for 20–30 h. The milled powder was then removed and solid-state sintered at 1150–1200 °C for 5 h to obtain Y-Zr-O ternary nano-oxides, mainly Y₂Zr₂O₇.

[0075] Step S3, Powder Mixing and Ball Milling: 1 wt.% Y-Zr-O nanoparticles are added to Al-5wt.%Mg-0.4wt.%Si-0.4wt.%Zr powder, and mechanically ball-milled in an omnidirectional planetary ball mill to uniformly disperse Y-Zr-O within the microalloyed powder. A compressor-assisted cooling system is used, with the temperature set to 0℃. The ball mill speed is 250 rpm, the ball-to-powder mass ratio is 8:1, and the ball milling time is 20 hours. After every 15 minutes of ball milling, the mill is stopped for 5 minutes, and the forward and reverse rotation directions are changed. This process induces a supersaturated nanocrystalline structure through intense plastic deformation, refining and uniformly dispersing the nano-Y2Zr2O7 oxide.

[0076] Step S4, densification treatment: The powder after mechanical ball milling is cold-pressed into a billet, placed in a sleeve and vacuum-sealed, and then densified by hot extrusion to obtain a shaped block. During the hot densification process, the grain boundaries of the nanocrystals formed by ball milling are effectively pinned by a large number of uniformly dispersed nano-Y₂Zr₂O₇ particles. At the same time, the supersaturated [Zr], [Y], and [O] atoms in the matrix undergo desolvation, and nano-Y₂Zr₂O₇ and D₀ precipitate at the grain boundaries. 23 -Al3Zr phase. The nanocrystals have a particle size of 50–200 nm; grain boundaries D0 23 The particle size of the Al3Zr phase is 20–60 nm; the particle size of the grain boundary nano-Y2Zr2O7 is 20–80 nm.

[0077] Step S4, 200-400℃ service: The molded block is placed under continuous heat exposure conditions of 200-400℃ for more than 1000 hours. A large number of highly coherent nanoclusters, rich in AlCO, continuously precipitate within the aluminum alloy matrix of the molded block. Thus, an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service is obtained, with a specific gravity of 2.64 g / cm³. 3 .

[0078] Example 5

[0079] A method for preparing an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service includes the following steps:

[0080] Step S1, Pretreatment: Al-Zr-Ti alloy powder (particle size less than 150 μm) was prepared by vacuum melting and gas atomization, wherein the Zr content was 0.4 wt.% and the Ti content was 0.2 wt.%, and the physical specific gravity of the alloy powder was 2.71 g / cm³. 3 ;;

[0081] Step S2, Powder Mixing and Ball Milling: 0.5 wt.% Y2O3 nanoparticles are added to the Al-Zr-Ti alloy powder, along with 3 wt.% ethanol as a process control agent. Ball milling is performed in an omnidirectional planetary ball mill to uniformly disperse the Y2O3 within the alloy powder. A compressor is used for auxiliary cooling, with the temperature set to 0°C. The ball mill speed is 250 rpm, the ball-to-powder mass ratio is 8:1, and the milling time is 20 hours. After every 15 minutes of milling, the mill is stopped for 5 minutes, and the forward and reverse rotation directions are changed. This process induces a supersaturated nanocrystalline structure through intense plastic deformation, refining and uniformly dispersing the nano-oxides.

[0082] Step S3, densification treatment: The powder after mechanical ball milling is cold-pressed into a blank, placed in a sleeve and vacuum-sealed, and densified by hot isostatic pressing to obtain a shaped block. During the hot densification process, the grain boundaries of the nanocrystals formed by ball milling are effectively pinned by a large number of uniformly dispersed nano-Y2O3 particles; at the same time, the supersaturated [O], [Zr], and [Ti] are desoluble, and nano-Y2O3 and L12-Al3(Zr,Ti) composite phases precipitate at the grain boundaries; the particle size of the nanocrystals is 50-400 nm; the particle size of the L12-Al3(Zr,Ti) phase at the grain boundaries is 20-60 nm; and the particle size of the nano-Y2O3 particles at the grain boundaries is 20-100 nm.

[0083] Step S4, Long-term service at 200-400℃: The molded block is placed under continuous heat exposure conditions of 200-400℃ for more than 1000 hours. A large number of highly coherent nanoclusters, rich in AlCO, continuously precipitate within the aluminum alloy matrix of the molded block. Thus, an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service is obtained, with a specific gravity of 2.71 g / cm³. 3 .

[0084] Example 6

[0085] A method for preparing an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service includes the following steps:

[0086] Step S1, Pretreatment: Al-Er-Hf alloy powder (particle size less than 150 μm) was prepared by vacuum melting and gas atomization, wherein the content of Er was 0.2 wt.%, the content of Hf was 0.2 wt.%, and the physical specific gravity of the alloy powder was 2.71 g / cm³. 3 ;;

[0087] Step S2, Powder Mixing and Ball Milling: 0.5 wt.% Y2O3 nanoparticles are added to the Al-Er-Hf alloy powder, along with 3 wt.% ethanol as a process control agent. Ball milling is performed in an omnidirectional planetary ball mill to uniformly disperse the Y2O3 within the alloy powder. A compressor is used for auxiliary cooling, with the temperature set to 0°C. The ball mill speed is 250 rpm, the ball-to-powder mass ratio is 8:1, and the milling time is 20 hours. After every 15 minutes of milling, the mill is stopped for 5 minutes, and the forward and reverse rotation directions are changed. This process induces a supersaturated nanocrystalline structure through intense plastic deformation, refining and uniformly dispersing the nano-oxides.

[0088] Step S3, densification treatment: The powder after mechanical ball milling is cold-pressed into a block, placed in a sleeve and vacuum-sealed, and densified by hot isostatic pressing to obtain a shaped block. During the hot densification process, the grain boundaries of the nanocrystals formed by ball milling are effectively pinned by a large number of uniformly dispersed nano-Y2O3 particles; at the same time, the supersaturated [O], [Er], and [Hf] are desoluble, and a composite phase of nano-Y2O3 and L12-Al3(Er,Hf) precipitates at the grain boundaries; the particle size of the nanocrystals is 50-400 nm; the particle size of the L12-Al3(Er,Hf) phase at the grain boundaries is 20-60 nm; and the particle size of the nano-Y2O3 particles at the grain boundaries is 20-100 nm.

[0089] Step S4, Long-term service at 200-400℃: The molded block is placed under continuous heat exposure conditions of 200-400℃ for more than 1000 hours. A large number of highly coherent nanoclusters, rich in AlCO, continuously precipitate within the aluminum alloy matrix of the molded block. Thus, an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service is obtained, with a specific gravity of 2.71 g / cm³. 3 .

[0090] The specific embodiments described above are used to explain and illustrate the present invention, rather than to limit it. Any modifications and changes made to the present invention within the scope of protection of the present invention and the claims shall fall within the scope of protection of the present invention.

Claims

1. An aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service, wherein high-temperature service refers to service at 200-400℃, characterized in that: At room temperature, the aluminum-based composite material comprises a nanocrystalline aluminum alloy matrix, a heat-resistant nanoparticle reinforcing phase at the grain boundaries, and a heat-resistant strengthening phase within the grains. The heat-resistant nanoparticle reinforcing phase includes a heat-resistant nano-oxide phase and a heat-resistant nano-intermetallic compound phase, which are uniformly distributed at the grain boundaries of the nanocrystalline structure. The heat-resistant strengthening phase has a nanocluster structure. When the aluminum-based composite material is placed under the high-temperature service conditions, a large amount of aluminum alloy matrix containing the heat-resistant nanoparticles can continuously precipitate within the grains of the aluminum alloy matrix. The heat-resistant strengthening phase, which is highly coherent with the gold matrix, ensures that the aluminum-based composite material maintains sustained high-temperature strength during service at 200-400℃ under the combined action of a triple strengthening mechanism: nanocrystalline strengthening, grain boundary pinning strengthening of the heat-resistant nano-oxide phase and the heat-resistant nano-intermetallic compound phase, and continuous precipitation strengthening of the intracrystalline nanocluster structure. At the same time, the nanocrystalline structure has strong coordinated deformation ability, and the intracrystalline precipitated nanocluster structure is highly coherent with the matrix. Under the combined action of these two toughening mechanisms, the aluminum-based composite material exhibits good plasticity / toughness between room temperature and 400℃.

2. The aluminum-based composite material according to claim 1, which continuously precipitates a heat-resistant strengthening phase during high-temperature service, is characterized in that, The nanocluster structure is an AlCO-rich phase with a structural size of less than 20 nm.

3. The aluminum-based composite material according to claim 1, which continuously precipitates a heat-resistant strengthening phase during high-temperature service, is characterized in that... The aluminum-based composite material can maintain its strength for at least 1000 hours during service at 200-400°C.

4. The aluminum-based composite material according to claim 3, which continuously precipitates a heat-resistant strengthening phase during high-temperature service, is characterized in that... The aluminum alloy matrix contains one or more of the elements Zr, Hf, Ti, V, Nb, Y, Sc, or Er.

5. The aluminum-based composite material according to claim 1, which continuously precipitates a heat-resistant strengthening phase during high-temperature service, is characterized in that... The heat-resistant nano-oxide phase is a rare earth / near rare earth or transition metal oxide phase with high melting point and high thermal stability, which does not re-dissolve in the aluminum alloy matrix even during service at 400°C for more than 1000 hours.

6. The aluminum-based composite material according to claim 5, which continuously precipitates a heat-resistant strengthening phase during high-temperature service, is characterized in that... The heat-resistant nano-oxide phase is one or more of Y2O3, Al2O3, CeO2, TiO2, HfO2, SiO2, ZrO2, or Y-Ti-O, Y-Zr-O, Y-Si-O, Y-Ce-O, Y-Al-O, and Y-Hf-O.

7. The aluminum-based composite material according to claim 1, which continuously precipitates a heat-resistant strengthening phase during high-temperature service, is characterized in that, The heat-resistant nano-intermetallic compound phase is an intermetallic compound phase with high thermal stability and containing rare earth / near rare earth or transition metal elements with extremely slow diffusion rate. It does not re-dissolve in the aluminum alloy matrix even during service at 400°C for more than 1,000 hours.

8. The aluminum-based composite material according to claim 7, which continuously precipitates a heat-resistant strengthening phase during high-temperature service, is characterized in that... The heat-resistant nano-intermetallic compound phase has a D0 23 Al3Zr or Al3Hf with structure D0 22 Al3Ti, Al3V, or Al3Nb structures have D0 19 One or more of the following: Al3Y with an L12 structure, Al3Sc or Al3Er with an L12 structure, or a composite structure phase formed therefrom.

9. A method for preparing an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service, as described in any one of claims 1-8, characterized in that... Includes the following steps: Step S1, Pretreatment: The aluminum alloy matrix powder is prepared by vacuum melting and gas atomization, and the powder particle size is less than 150 μm; Step S2, preparing critically supersaturated nanocrystalline structure by ball milling: 0.5-2 wt.% heat-resistant nano-oxide particles are added to the aluminum alloy matrix powder, and ethanol is added as a process control agent. The powder is then mixed and ball-milled in a ball mill for 14-20 hours. The intense plastic deformation caused by ball milling continuously refines the grains of the aluminum alloy matrix. This allows the heat-resistant nano-oxide particles to partially dissolve back into the aluminum alloy matrix, obtaining the critically supersaturated nanocrystalline structure. The heat-resistant nano-oxide particles are refined while simultaneously achieving uniform dispersion. Step S3, densification treatment: The powder obtained in step S2 is cold-pressed into a blank, placed in a sleeve and vacuumed, and densified by discharge plasma sintering / hot pressing sintering / hot extrusion / hot isostatic pressing to obtain a shaped block; During the thermal densification process, the heat-resistant intermetallic compound phase precipitates out, and the grain boundaries of the critically supersaturated nanocrystalline structure are effectively pinned by the heat-resistant nano-oxide phase and the heat-resistant intermetallic compound phase; at the same time, solute atoms in the critically supersaturated nanocrystalline structure undergo desolvation, and a small amount of the nanocluster structure begins to precipitate within the crystal. Step S4, High-temperature service: The molded block is placed in a continuous heat exposure condition of 200-400℃, and a large number of nano-clusters that are highly coherent with the aluminum alloy matrix can be continuously precipitated in the aluminum alloy matrix of the molded block; thereby, an aluminum-based composite material that continuously precipitates heat-resistant strengthening phase during high-temperature service is obtained.

10. The method for preparing an aluminum-based composite material that continuously precipitates a heat-resistant strengthening phase during high-temperature service, as described in claim 9, is characterized in that... The nanocrystalline structure described in the critical supersaturation refers to a critical state where the nanocrystals have just reached supersaturation but are sufficiently supersaturated. Only when the critical state is reached can the nanocrystals have the ability to continuously precipitate during service at 200-400°C.

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