Aluminum alloy composite material and preparation method thereof

Abstract

The invention relates to an aluminum alloy composite material and a preparation method thereof. The preparation method comprises the following steps that a core material and a shell material are mixed and then pressed to obtain a blank; wherein the core material is aluminum alloy particles with hollow core structures inside, the shell material is aluminum alloy powder, and the liquidus Ta of the core material is 30 DEG C or above higher than the liquidus Tm of the shell material; the blank is heated to the temperature T1 of a solid-liquid two-phase region of the shell material under the protective atmosphere, heat preservation is conducted for 20-60 min, and first-stage sintering is completed; then, the temperature is increased to T2, heat preservation is conducted for 10-30 min, and second-stage sintering is completed; wherein T1 = Tm-(0.1-0.5) delta T, and delta T is a temperature difference between a solidus line and a liquidus line of the shell material; t2 = Ta-(0.1-0.3) delta T ', and delta T' is the temperature difference between the solidus and liquidus of the core material.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloys, and more specifically to an aluminum alloy composite material and its preparation method. Background Technology

[0002] This section is intended to provide background or context for the embodiments of the invention set forth in the claims. The description herein is not an admission that it is prior art simply because it is included in this section.

[0003] While aluminum alloys are lightweight, a single material cannot simultaneously meet the requirements for high strength, vibration damping, and sound insulation. Traditional aluminum-based composite materials often employ sandwich structures or add non-metallic reinforcing phases in hopes of improving their various properties, but these methods suffer from problems such as complex processes, weak interfacial bonding, and high costs.

[0004] For example, the high density of existing aluminum alloy structural components used in robotic arms limits their movement speed and energy efficiency. Rail vehicle components: Existing high-speed rail bodies mostly use aluminum alloy materials combined with sandwich structures (such as honeycomb aluminum panels), filled with sound-absorbing materials (such as polyurethane foam), and the interior of the body panels is lined with multiple layers of sound-insulating materials (such as fiberglass wool and rubber sound-insulating felt). While achieving structural strength and vibration damping, this results in complex structures, high costs, and the presence of materials prone to aging, leading to high replacement costs. Electronic equipment housings: A single aluminum alloy is difficult to balance in terms of heat dissipation and vibration damping performance. Adding non-metallic fillers (such as rubber particles) can improve damping performance, but it significantly reduces the material's temperature resistance (≤150℃) and thermal conductivity, failing to meet the heat dissipation requirements of electronic equipment.

[0005] With the development of high-speed industrial equipment, lightweight transportation vehicles, and highly integrated electronic devices, the requirements for material performance have shifted from single-attribute optimization to multi-objective synergistic optimization. A lightweight aluminum alloy that combines strength, rigidity, vibration damping, and sound insulation has become a key technological direction for addressing these application scenarios.

[0006] CN101876009A discloses a method for preparing ceramic particle-reinforced aluminum foam matrix composites. This method uses CaCO3 instead of TiH2 as the foaming agent, and prepares ceramic particle-reinforced aluminum foam through powder metallurgy combined with hot extrusion and diffusion annealing. The preparation process of this patent is relatively complex, and the interfacial bonding between the ceramic particles and the aluminum alloy matrix is ​​weak, making it prone to brittleness and cracking after long-term use.

[0007] CN203808357U discloses a high-strength, lightweight sound-absorbing and vibration-damping board, which adopts a multi-layer composite structure design of aluminum honeycomb core + rubber layer + inorganic fiber to achieve vibration reduction and sound insulation effects. This patent has a complex structure, requiring multiple steps of bonding and lamination in its preparation; the adhesive layer is prone to aging and has poor durability under humid and hot environments.

[0008] CN102205359A discloses a method for manufacturing aluminum foam sheets. This method involves pre-embedding a TiH2 foaming agent in an aluminum tube, then encapsulating the aluminum tube containing the TiH2 foaming agent within an aluminum box, and finally foaming the composite billet to prepare the aluminum foam sheet. This method, using TiH2 as the foaming agent, suffers from problems such as difficulty in controlling the gas release rate and uneven pore distribution. Furthermore, the method requires rolling before foaming, which further reduces the porosity of the material and makes it even more difficult to control. In addition, the aluminum foam prepared by this method also exhibits drawbacks such as easy interface peeling at high temperatures and weak interfacial bonding.

[0009] In addition, existing aluminum alloy composite materials still need further improvement in terms of strength, lightweight properties, and sound insulation performance. Summary of the Invention

[0010] The purpose of this invention is to provide a new method for preparing aluminum alloy composite materials, which produces aluminum alloy composite materials with high strength, lightweight and excellent sound insulation properties.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] This invention provides a method for preparing an aluminum alloy composite material, comprising the following steps:

[0013] (1) The core material and the shell material are mixed and pressed to obtain a blank; wherein, the core material is aluminum alloy granules with a hollow internal structure, the shell material is aluminum alloy powder, and the liquidus line T of the core material is... a The liquidus T of the shell material m Temperatures of 30°C or higher;

[0014] (2) The billet is heated to temperature T1, the solid-liquid two-phase region of the shell material, under a protective atmosphere and held for 20-60 minutes to complete the first stage of sintering; then the temperature is raised to T2 and held for 10-30 minutes to complete the second stage of sintering; wherein, T1 = T m -(0.1~0.5)ΔT, where ΔT is the temperature difference between the solidus and liquidus of the shell material; T2=T a -(0.1~0.3)ΔT′, where ΔT′ is the temperature difference between the solidus and liquidus of the core material.

[0015] According to some specific embodiments, the particle size of the core material is 0.5-30mm, such as 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, etc.

[0016] According to some specific embodiments, the volume percentage of the solid portion of the core material is 20-60% of the total volume, for example, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, etc.

[0017] According to some specific embodiments, the aluminum alloy particles can be of any shape, preferably spherical.

[0018] According to some specific embodiments, the particle size of the shell material is 5-80μm, such as 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, etc.

[0019] According to some specific embodiments, the mass of the core material accounts for 15-50% of the total mass of the aluminum alloy composite material, for example, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, etc.

[0020] According to some specific embodiments, the liquidus line T of the core material is... a The liquidus T of the shell material m Temperatures can range from 30 to 80 degrees Celsius.

[0021] According to some specific embodiments, the particle size of the shell material is 10 times or more the particle size of the core material.

[0022] According to some specific embodiments, the liquidus line T of the core material is... a The liquidus T of the shell material is 640-660℃. m The temperature ranges from 570 to 620℃.

[0023] According to some specific embodiments, the alloy composition of the core material, by mass percentage, is: Si: 0.3-1.6%, Mg: 0.3-1.3%, Cu: 0-0.9%, Mn: 0-0.8%, Zn: 0-0.3%, Cr: 0-0.3%, Ti: 0-0.25%, Zr: 0-0.15%, Sc: 0-0.1%, with the balance being Al.

[0024] According to some specific embodiments, the alloy composition of the shell material, by mass percentage, is: Si: 7-14%, Mg: 0-3%, Cu: 0-2%, Mn: 0-1%, Zn: 0-0.5%, Cr: 0-0.5%, Ti: 0-0.25%, Zr: 0-0.15%, Sc: 0-0.1%, with the balance being Al.

[0025] According to some specific embodiments, in step (1), after mixing the core material and part of the shell material, a first cold pressing is performed. The pressure of the first cold pressing is controlled to be 100-400 MPa, for example, 100 MPa, 110 MPa, 120 MPa, 130 MPa, 140 MPa, 150 MPa, 160 MPa, 170 MPa, 180 MPa, 190 MPa, 200 MPa, 210 MPa, 220 MPa, 230 MPa, 240 MPa, 250 MPa. 260MPa, 270MPa, 280MPa, 290MPa, 300MPa, 310MPa, 320MPa, 330MPa, 340MPa, 350MPa, 360MPa, 370MPa, 380MPa, 390MPa, 400MPa, etc., for a time of 5-20 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, etc. The time intervals are 17 min, 18 min, 19 min, 20 min, etc.; then, the remaining shell material is used to cover the cold-pressed body after the first cold pressing, and a second cold pressing is performed. The pressure of the second cold pressing is controlled at 200-500 MPa, for example, 200 MPa, 210 MPa, 220 MPa, 230 MPa, 240 MPa, 250 MPa, 260 MPa, 270 MPa, 280 MPa, 290 MPa, 300 MPa, 310 MPa, 320 MPa, 330 MPa, etc. 340MPa, 350MPa, 360MPa, 370MPa, 380MPa, 390MPa, 400MPa, 410MPa, 420MPa, 430MPa, 440MPa, 450MPa, 460MPa, 470MPa, 480MPa, 490MPa, 500MPa, etc., with a time of 1-10 minutes, such as 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc.

[0026] According to some specific embodiments, before performing step (1), the core material is pretreated. The method for pretreatment of the core material is to heat the core material to the solution temperature, then cool it rapidly, and then perform aging treatment.

[0027] Furthermore, the solution treatment temperature is 520-550℃, for example, 520℃, 525℃, 530℃, 535℃, 540℃, 545℃, 550℃, etc.

[0028] Furthermore, after heating to the solution temperature, the temperature is maintained for 1-4 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, etc.

[0029] Furthermore, air cooling or water cooling is used for the rapid cooling.

[0030] Furthermore, the aging treatment temperature is 140-200℃, such as 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, 200℃, etc.

[0031] Furthermore, the time for the time-sensitive processing is 5-8 hours, such as 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, etc.

[0032] According to some specific embodiments, before performing step (1), the shell material is pretreated. The pretreatment method of the shell material is to heat the shell material to the annealing temperature and keep it at that temperature for 1-4 hours, such as 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, etc.

[0033] Furthermore, the annealing temperature is 320-420℃, such as 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, etc.

[0034] According to some specific implementations, T1 is 560-590℃, such as 560℃, 565℃, 570℃, 575℃, 580℃, 585℃, 590℃, etc.

[0035] Furthermore, the temperature is maintained at T1 for 20-60 minutes, for example, 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes, 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes, 40 minutes, 41 minutes, 42 minutes, 43 minutes, 44 minutes, 45 minutes, 46 minutes, 47 minutes, 48 ​​minutes, 49 minutes, 50 minutes, 51 minutes, 52 minutes, 53 minutes, 54 minutes, 55 minutes, 56 minutes, 57 minutes, 58 minutes, 59 minutes, 60 minutes, etc.

[0036] According to some specific implementations, T2 is 610-630℃, such as 610℃, 615℃, 620℃, 625℃, 630℃, etc.

[0037] Furthermore, the temperature is maintained at T2 for 10-30 minutes, for example, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes, 30 minutes, etc.

[0038] According to some specific embodiments, the preparation method further includes a post-processing step after step (2). The post-processing method is as follows: heating the sintered composite material to 500-550℃, for example 500℃, 505℃, 510℃, 515℃, 520℃, 525℃, 530℃, 535℃, 540℃, 545℃, 550℃, etc., and applying 50-120MPa (for example 50MPa, 60MPa, 70MPa, 80MPa, 90MPa, 100MPa, 110MPa, 12...). The composite material is subjected to a pressure of 0 MPa (or similar) and held for 1-3 hours, such as 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours, followed by hot isostatic pressing. After hot isostatic pressing, the composite material is rapidly cooled and then aged. The aging temperature is 140-180℃, such as 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, or 180℃, for 4-8 hours, such as 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, or 8 hours.

[0039] A second aspect of the present invention provides an aluminum alloy composite material, which is prepared by the preparation method described above.

[0040] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0041] This invention prepares aluminum alloy composite materials by using core and shell materials as raw materials and a temperature gradient sintering method. This preparation method has the advantages of simple process and low cost. The aluminum alloy composite materials prepared by this method have the advantages of lightweight, good interface bonding, high strength and good sound insulation. It is suitable for scenarios with high requirements for lightweight, high rigidity and shock absorption and sound insulation performance, such as robotic arms, rail vehicles and electronic equipment housings. Attached Figure Description

[0042] Figure 1 This is a flowchart illustrating the preparation process of aluminum alloy composite materials.

[0043] Figure 2 This is the temperature gradient sintering process curve;

[0044] Figure 3 This is the post-processing curve.

[0045] Figure 4 This is an optical microscope image of the interface between the core material and the shell material in Example 1;

[0046] Figure 5 This is an optical microscope image of the interface between the core material and the shell material in Comparative Example 1. Detailed Implementation

[0047] To address the challenges of synergistic effects of lightweighting, poor interfacial bonding, and vibration damping and sound insulation on traditional aluminum alloy materials and composites, this invention provides a method for preparing aluminum alloy composites with a gradient composite structure. This method is a simple and low-cost powder metallurgy approach.

[0048] Specifically, the method of the present invention includes: obtaining an aluminum alloy hollow geometry as the core material and aluminum alloy powder as the shell material; optionally, the core material is subjected to heat treatment for strengthening and the shell material is subjected to annealing and softening pretreatment; the core material and part of the shell material are mixed and cold-pressed to fill the gaps between the core geometry; the remaining shell material is wrapped around the cold-pressed body and cold-pressed a second time; after cold pressing, the material is subjected to temperature gradient sintering, and then optionally post-treatment is performed for strengthening to obtain an aluminum alloy composite material with a gradient composite structure.

[0049] This invention achieves a core-shell gradient structure design for the material. The core utilizes high-melting-point aluminum alloy hollow units to provide sufficient rigidity and support. By adjusting the proportion and quantity of spherical hollow units, the material achieves lightweighting and controllable porosity. The uniform and controllable pore structure provides excellent vibration damping and sound insulation. The outer layer is coated with low-melting-point aluminum alloy powder through sintering, resulting in a low surface roughness after sintering, while also achieving good thermal conductivity and high wear resistance. This material features a simplified gradient sintering process, avoiding multi-step composite processes and interfacial adhesion, eliminating the weakness of brittle interfacial connections, and exhibiting greater structural stability. Furthermore, the core-shell gradient material can be selected according to application requirements, and the use of heat-treated strengthening materials can further enhance the material's strength.

[0050] This invention discloses a method for preparing an aluminum alloy composite material with a gradient composite structure through gradient temperature sintering. This method yields an aluminum alloy composite material with a good metallurgical bonding interface, possessing high strength, rigidity, vibration damping, and sound insulation properties, effectively avoiding defects such as porosity and cracks in the material. After sintering, the composite structure retains the hollow core geometry, effectively achieving material lightweighting, reducing the material density to 1.6–2.0 g / cm³. 3 .

[0051] The principle of this invention is as follows:

[0052] 1. Material pretreatment

[0053] Before cold pressing, the core material undergoes solution treatment, causing the second phase containing elements such as magnesium, silicon, and copper to dissolve and solidify into the aluminum matrix. Rapid cooling forms a supersaturated solid solution, followed by aging treatment to create nanoscale precipitates that enhance strength and hardness. The shell material undergoes annealing, which coarsens the nano / submicron-scale second phases and eliminates lattice distortion and residual stress, thereby reducing powder hardness. This pretreatment of the core and shell materials creates a significant hardness gradient, facilitating high rigidity support for the core material and high plasticity for the shell material during cold pressing, resulting in a high-quality cold-pressed blank.

[0054] Of course, if the core material and shell material already have a large hardness gradient, the pretreatment step can be omitted and cold pressing can be performed directly.

[0055] 2. Gradient sintering

[0056] To achieve bonding between the powder particles of the shell material and the interfacial bonding between the shell material and the core geometry, while maintaining the hollow geometric structure of the core material throughout the sintering process, this invention employs a gradient temperature sintering method. The first-stage sintering temperature is set between the solidus and liquidus lines of the shell material, enabling the powder particles of the shell material to form a semi-solid bond after cold pressing deformation, completing the initial bonding between the powder particles, and forming a fine grain structure within the shell material microstructure during this stage. The first-stage sintering temperature T1 is:

[0057] T1 = T m -(0.1~0.5)ΔT

[0058] Where ΔT is the temperature difference between the solidus and liquidus of the shell material, T m The liquidus line represents the liquidus of the shell material.

[0059] Because the liquidus temperature of the core material is higher than that of the shell material, the second-stage sintering temperature is increased to T2 to promote bonding between the shell material and the hollow core geometry material at the contact interface. At this temperature, the liquid phase network of the shell material further expands, and the liquid metal gradually wets and diffuses with the core material. With the expansion of the liquid phase network, the porosity at the shell interface is further reduced, while simultaneously ensuring the hollow geometry structure of the core material. The second-stage sintering temperature T2 is:

[0060] T2 = T a -(0.1~0.3)ΔT′

[0061] ΔT′ is the temperature difference between the solidus and liquidus of the core material, T aThis refers to the liquidus line of the core material.

[0062] 3. Hot isostatic pressing

[0063] This invention involves heating the sintered composite material to a temperature T3 and applying pressure for heat treatment. The pressure and high temperature further eliminate micro-closed pores at the bonding interface, thereby improving the interfacial bonding strength. Simultaneously, the high temperature allows alloying elements in the composite material to further dissolve into the aluminum matrix. Rapid cooling forms a supersaturated solid solution, and subsequent aging treatment promotes the precipitation of nanoscale reinforcing phases in both the core and shell materials, further enhancing the composite material's strength and hardness.

[0064] The present invention will be further described below with reference to embodiments. However, the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific applications, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0065] Unless otherwise specified in this document, the preparation and testing methods involved in the following examples or comparative examples are based on existing technologies. For instance, cold pressing is performed at room temperature.

[0066] Unless otherwise specified in the following embodiments, all raw materials are commercially available or prepared using conventional methods in the art. For example, core materials can be purchased from manufacturers or custom-made, or prepared in-house using conventional methods. For instance, the hollow sphere can be manufactured using any of the following methods: Method 1: Lost-wax casting to form a hollow sphere with openings, then sealing the openings with mortises. Method 2: Casting to form a hollow hemisphere, then connecting two hemispheres into a sphere through rotational friction. Method 3: 3D printing, which is more expensive.

[0067] The hollow spherical geometry refers to a sphere with a hollow internal structure and a dense, non-porous outer surface to prevent powder from entering the core material. The percentage of the solid portion's volume to the total volume is calculated as the percentage of the volume of a solid sphere of a certain mass to the volume of the hollow spherical geometry of the same mass.

[0068] Example 1

[0069] A method for preparing aluminum alloy composite materials with a gradient composite structure includes the following steps:

[0070] (1) Material selection

[0071] A powder with a particle size D50 of 50 μm was selected as the shell material. Its specific chemical composition by mass percentage is: Si: 13%, Mg: 2.6%, Cu: 2%, Mn: 0.8%, Zn: 0.4%, Cr: 0.35%, Ti: 0.2%, Zr: 0.1%, Sc: 0.06%, with the balance being Al. Its liquidus T... m =571℃.

[0072] A spherical hollow geometric body with a diameter of 0.5 mm and a solid portion accounting for 25% of the total volume was selected as the core material. Its specific chemical composition by mass percentage is: Si: 1.4%, Mg: 1.1%, Cu: 0.75%, Mn: 0.65%, Zn: 0.25%, Cr: 0.2%, Ti: 0.15%, Zr: 0.1%, Sc: 0.07%, with the balance being Al. Its liquidus T... a =647℃. The core material accounts for 20% of the total weight of the composite material.

[0073] (2) Pretreatment

[0074] The core material is heated to 530℃, held for 3 hours, water-cooled to room temperature, and then aged at 180℃ for 6 hours. The shell material is heated to 420℃, held for 1 hour, and then annealed.

[0075] (3) Cold pressing

[0076] After mixing the core material with part of the shell material, the mixture is placed into a pressing mold. The first cold pressing pressure is 360 MPa and the holding pressure is 20 minutes. Then, the remaining shell material is used to cover the first cold-pressed body and it is cold-pressed again. The second cold pressing pressure is 450 MPa and the holding pressure is 10 minutes.

[0077] (4) Temperature gradient sintering

[0078] The cold-pressed blank is heated under a protective atmosphere to temperature T1, which is the solid-liquid two-phase region of the shell material (ΔT = 71℃). T1 = T m -0.1ΔT≈564℃, hold at this temperature for 60 minutes to complete the first stage of sintering. Then raise the temperature to T2, where ΔT′=142℃, T2=T a -0.2ΔT′≈619℃, hold for 30 minutes to complete the second stage of sintering.

[0079] (5) Post-processing

[0080] The sintered composite material was heated to 500℃, subjected to a pressure of 100MPa, and held at that pressure for 3 hours for hot isostatic pressing (HIP). After HIP, the composite material was water-cooled and then aged at 175℃ for 8 hours. After natural cooling to room temperature, a gradient composite aluminum alloy composite material with a good metallurgical interface and a relatively intact hollow structure was obtained. A cross-sectional photograph of this material under an optical microscope is shown below. Figure 4 As shown.

[0081] Example 2

[0082] A method for preparing aluminum alloy composite materials with a gradient composite structure includes the following steps:

[0083] (1) Material selection

[0084] A powder with a particle size D50 of 10 μm was selected as the shell material. Its specific chemical composition by mass percentage is: Si: 11%, Mg: 1.2%, Cu: 1.2%, Mn: 0.4%, Zn: 0.2%, Cr: 0.15%, Ti: 0.1%, with the balance being Al. Its liquidus T... m =581℃.

[0085] A spherical hollow geometric body with a diameter of 5 mm and a solid portion accounting for 20% of the total volume was selected as the core material. Its specific chemical composition by mass percentage is: Si: 0.6%, Mg: 0.7%, Cu: 0.3%, Mn: 0.25%, Zn: 0.1%, Ti: 0.05%, with the balance being Al. Its liquidus T... a =654℃. The core material accounts for 16% of the total weight of the composite material.

[0086] (2) Pretreatment

[0087] The core material is heated to 540℃, held for 2 hours, water-cooled to room temperature, and then aged at 180℃ for 5 hours. The shell material is heated to 320℃, held for 4 hours, and then annealed.

[0088] (3) Cold pressing

[0089] After mixing the core material with part of the shell material, the mixture is placed into a pressing mold. The first cold pressing pressure is 200 MPa and the pressure is held for 20 minutes. Then, the remaining shell material is used to cover the first cold-pressed body and it is cold-pressed again. The second cold pressing pressure is 350 MPa and the pressure is held for 5 minutes.

[0090] (4) Temperature gradient sintering

[0091] The cold-pressed blank is heated under a protective atmosphere to temperature T1, which is the solid-liquid two-phase region of the shell material (ΔT = 75℃). T1 = T m-0.2ΔT = 566℃, hold at this temperature for 40 minutes to complete the first stage of sintering. Then raise the temperature to T2, where ΔT′ = 124℃, T2 = T a -0.3ΔT′≈617℃, hold for 20 minutes to complete the second stage of sintering.

[0092] (5) Post-processing

[0093] The sintered composite material was heated to 510℃, subjected to a pressure of 60MPa, and held at that pressure for 2 hours for hot isostatic pressing. After hot isostatic pressing, the composite material was water-cooled and then aged at 180℃ for 6 hours. After natural cooling to room temperature, a gradient composite aluminum alloy composite material with a good metallurgical interface and a relatively complete hollow structure was obtained.

[0094] Example 3

[0095] A method for preparing aluminum alloy composite materials with a gradient composite structure includes the following steps:

[0096] (1) Material selection

[0097] A powder with a particle size D50 of 30 μm was selected as the shell material. Its specific chemical composition by mass percentage is: Si: 7.2%, Mg: 0.2%, Cu: 0.4%, Mn: 0.6%, Zn: 0.5%, Ti: 0.05%, Zr: 0.15%, Sc: 0.1%, with the balance being Al. Its liquidus T... m =612℃.

[0098] A spherical hollow geometric body with a diameter of 15 mm and a solid portion accounting for 60% of the total volume was selected as the core material. Its specific chemical composition by mass percentage is: Si: 0.3%, Mg: 0.4%, Zr: 0.15%, Sc: 0.1%, with the balance being Al. Its liquidus T... a =657℃. The core material accounts for 50% of the total weight of the composite material.

[0099] (2) Pretreatment

[0100] The core material is heated to 550℃, held for 4 hours, water-cooled to room temperature, and then aged at 180℃ for 6 hours. The shell material is heated to 360℃, held for 2 hours, and then annealed.

[0101] (3) Cold pressing

[0102] After mixing the core material with part of the shell material, the mixture is placed into a pressing mold. The first cold pressing pressure is 400 MPa and the pressure is held for 5 minutes. Then, the remaining shell material is used to cover the cold-pressed body and it is cold-pressed again. The second cold pressing pressure is 500 MPa and the pressure is held for 1 minute.

[0103] (4) Temperature gradient sintering

[0104] The cold-pressed blank is heated under a protective atmosphere to temperature T1, which is the solid-liquid two-phase region of the shell material (ΔT = 87℃). T1 = T m -0.5ΔT≈569℃, hold at this temperature for 20 minutes to complete the first stage of sintering. Then raise the temperature to T2, where ΔT′=102℃, T2=T a -0.3ΔT′≈626℃, hold for 20 minutes to complete the second stage of sintering.

[0105] (5) Post-processing

[0106] The sintered composite material was heated to 530℃, subjected to a pressure of 50MPa, and held at that pressure for 1 hour for hot isostatic pressing. After hot isostatic pressing, the composite material was water-cooled and then aged at 140℃ for 8 hours. After natural cooling to room temperature, a gradient composite aluminum alloy composite material with a good metallurgical interface and a relatively complete hollow structure was obtained.

[0107] Example 4

[0108] A method for preparing aluminum alloy composite materials with a gradient composite structure includes the following steps:

[0109] (1) Material selection

[0110] Powder with a particle size D50 of 80 μm was selected as the shell material. Its specific chemical composition by mass percentage is: Si: 10%, Mg: 2%, Cr: 0.2%, Ti: 0.15%, with the balance being Al. Its liquidus T m =592℃.

[0111] A spherical hollow geometric body with a diameter of 30 mm and a solid portion accounting for 30% of the total volume was selected as the core material. Its specific chemical composition by mass percentage is: Si: 1.6%, Mg: 1.3%, Mn: 0.4%, Zn: 0.2%, Cr: 0.1%, Ti: 0.05%, with the balance being Al. Its liquidus T... a =646℃. The core material accounts for 30% of the total weight of the composite material.

[0112] (2) Pretreatment

[0113] The core material is heated to 550℃, held for 1 hour, water-cooled to room temperature, and then aged at 140℃ for 8 hours. The shell material is heated to 380℃, held for 3 hours, and then annealed.

[0114] (3) Cold pressing

[0115] After mixing the core material with part of the shell material, the mixture is placed into a pressing mold. The first cold pressing pressure is 100MPa and the pressure is held for 20 minutes. Then, the remaining shell material is used to cover the first cold pressing body and cold pressing is performed again. The second cold pressing pressure is 200MPa and the pressure is held for 10 minutes.

[0116] (4) Temperature gradient sintering

[0117] The cold-pressed blank is heated under a protective atmosphere to temperature T1, which is the solid-liquid two-phase region of the shell material (ΔT = 35℃). T1 = T m -0.1ΔT≈588℃, hold at this temperature for 40 minutes to complete the first stage of sintering. Then raise the temperature to T2 temperature ΔT′=91℃, where T2=T a -0.3ΔT′≈619℃, hold for 10 minutes to complete the second stage of sintering.

[0118] (5) Post-processing

[0119] The sintered composite material was heated to 550℃, subjected to a pressure of 50MPa, and held at that pressure for 3 hours for hot isostatic pressing. After hot isostatic pressing, the composite material was water-cooled and then aged at 140℃ for 8 hours. After natural cooling to room temperature, a gradient composite aluminum alloy composite material with a good metallurgical interface and a relatively complete hollow structure was obtained.

[0120] Comparative Example 1

[0121] A method for preparing aluminum alloy composite materials includes the following steps:

[0122] (1) Material selection

[0123] A powder with a particle size D50 of 50 μm was selected as the shell material. Its specific chemical composition by mass percentage is: Si: 13%, Mg: 2.6%, Cu: 2%, Mn: 0.8%, Zn: 0.4%, Cr: 0.35%, Ti: 0.2%, Zr: 0.1%, Sc: 0.06%, with the balance being Al. Its liquidus T... m =571℃.

[0124] A spherical hollow geometric body with a diameter of 0.5 mm and a solid portion accounting for 25% of the total volume was selected as the core material. Its specific chemical composition by mass percentage is: Si: 10%, Mg: 2%, Cr: 0.2%, Ti: 0.15%, with the balance being Al. Its liquidus T... a =592℃. Does not meet T a -T m ≥30℃. The core material accounts for 20% of the total weight of the composite material.

[0125] (2) Pretreatment

[0126] The core material is heated to 540℃, held for 2 hours, water-cooled to room temperature, and then aged at 180℃ for 5 hours. The shell material is heated to 320℃, held for 4 hours, and then annealed.

[0127] (3) Cold pressing

[0128] After mixing the core material with part of the shell material, the mixture is placed into a pressing mold. The first cold pressing pressure is 360 MPa and the holding pressure is 20 minutes. Then, the remaining shell material is used to cover the first cold pressing body and cold pressing is performed again. The second cold pressing pressure is 450 MPa and the holding pressure is 10 minutes.

[0129] (4) Sintering

[0130] The cold-pressed billet was heated to 614℃ under a protective atmosphere and held for 30 minutes to complete sintering. After sintering, it was naturally cooled to room temperature to obtain an aluminum alloy composite material, which had poor metallurgical interface and hollow structure integrity.

[0131] (5) Post-processing

[0132] The sintered composite material was heated to 500℃, subjected to a pressure of 100MPa, and held at that pressure for 3 hours for hot isostatic pressing (HIP). After HIP, the composite material was water-cooled and then aged at 175℃ for 8 hours. After natural cooling to room temperature, the aluminum alloy composite material was obtained. A cross-sectional photograph of its structure under an optical microscope is shown below. Figure 5 As shown, from Figure 5 It is evident that the aluminum alloy composite material has numerous pores (unbonded defects in the figure), indicating poor bonding strength.

[0133] Comparative Example 2

[0134] The material is traditional 6061 rolled plate, and its specific chemical composition by mass percentage is: Si: 0.64%, Mg: 0.85%, Cu: 0.22%, Mn: 0.05%, Cr: 0.05%, Ti: 0.02%, with the balance being Al.

[0135] The density, flexural strength, and sound insulation of the products in each embodiment and comparative example were tested, and the test results are shown in Table 1 below.

[0136] Test methods:

[0137] The density was calculated using Archimedes' displacement method to accurately determine the volume through buoyancy differences.

[0138] The bending strength was tested using the three-point bending test method, with a loading rate of 1 mm / min and a span-to-thickness ratio of 16:1.

[0139] The sound insulation was measured using acoustic building and building component sound insulation measurement methods. The sample was installed between the reverberation chamber and the anechoic chamber with edge sealing treatment. White noise (frequency range 100-5000Hz) was emitted at the sound source end, and the incident sound and transmitted sound were recorded at the receiving end to calculate the sound insulation.

[0140] Table 1

[0141]

[0142] As can be seen from the various embodiments and comparative examples, the products obtained by each embodiment have high strength, high sound insulation and low density. Furthermore, since the products of each embodiment retain a relatively complete hollow structure, they must have good shock absorption and rigidity.

[0143] The present invention has been described in detail above, with the aim of enabling those skilled in the art to understand and implement the invention. However, this description should not be construed as limiting the scope of protection of the invention. All equivalent changes or modifications made in accordance with the spirit and essence of the invention should be included within the scope of protection of the invention.

Claims

1. A method of making an aluminum alloy composite material, characterized by: comprising the following steps: (1) mixing the core material and the shell material, and then pressing to obtain a blank; wherein the core material is an aluminum alloy particle with an empty core structure, the shell material is an aluminum alloy powder, the liquidus T a of the core material is 30℃ and above higher than the liquidus T m of the shell material; (2) heating the blank under a protective atmosphere to a temperature T1 in the solid-liquid two-phase region of the shell material, holding for 20-60 min to complete the first-stage sintering; then increasing the temperature to T2, holding for 10-30 min to complete the second-stage sintering; wherein T1 = T m -(0.1-0.5)ΔT, ΔT being the temperature difference between the solidus and liquidus of the shell material; T2 = T a -(0.1-0.3)ΔT', ΔT' being the temperature difference between the solidus and liquidus of the core material.

2. The method of claim 1, wherein: The particle size of the core material is 0.5-30 mm, and the solid part volume accounts for 20-60% of the total volume; and / or, the particle size of the shell material is 5-80 μm.

3. The method of claim 1, wherein: The mass of the core material accounts for 15-50% of the total mass of the aluminum alloy composite material.

4. The method of claim 1, wherein: the liquidus T of the shell material a 30-80°C higher than the liquidus T of the shell material m 30-80°C higher than the liquidus T of the shell material 5. The method of claim 1, wherein: The alloy composition of the core material is, in terms of mass percentage: Si: 0.3-1.6%, Mg: 0.3-1.3%, Cu: 0-0.9%, Mn: 0-0.8%, Zn: 0-0.3%, Cr: 0-0.3%, Ti: 0-0.25%, Zr: 0-0.15%, Sc: 0-0.1%, and the balance being Al; and / or, the alloy composition of the shell material is, in terms of mass percentage: Si: 7-14%, Mg: 0-3%, Cu: 0-2%, Mn: 0-1%, Zn: 0-0.5%, Cr: 0-0.5%, Ti: 0-0.25%, Zr: 0-0.15%, Sc: 0-0.1%, and the balance being Al.

6. The method of claim 1, wherein: In step (1), after the core material and part of the shell material are mixed, first cold pressing is performed, the pressure of the first cold pressing is controlled to be 100-400 MPa, and the time is controlled to be 5-20 min; then the remaining shell material is used to coat the cold-pressed body after the first cold pressing, second cold pressing is performed, the pressure of the second cold pressing is controlled to be 200-500 MPa, and the time is controlled to be 1-10 min.

7. The method of claim 1, wherein: Before the step (1) is performed, the core material and the shell material are respectively pretreated, the pretreatment method of the core material is: the core material is heated to a solid solution temperature, then rapidly cooled, and then aged treatment is performed; the pretreatment method of the shell material is: the shell material is heated to an annealing temperature, and the temperature is maintained for 1-4 hours.

8. The method of claim 7, wherein: The solid solution temperature is 520-550 ℃, the temperature of the aging treatment is 140-200 ℃, and the annealing temperature is 320-420 ℃.

9. The method of claim 1, wherein: The preparation method further comprises a post-treatment step after step (2), and the post-treatment method is: after sintering, the composite material is heated to 500-550 ℃, a pressure of 50-120 MPa is applied, and the pressure is maintained for 1-3 h to perform hot isostatic pressing; after the hot isostatic pressing, the composite material is rapidly cooled; then aging treatment is performed, the temperature of the aging treatment is 140-180 ℃, and the time is 4-8 h.

10. An aluminum alloy composite material, characterized by: The aluminum alloy composite material is prepared by the preparation method in any one of claims 1 to 9.

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