High-strength ductile aluminum-magnesium-silicon alloy matrix composite and method for manufacturing same

Abstract

The present application relates to a kind of high-strength toughness aluminum magnesium silicon alloy-based composite material and its preparation method.The present application introduces ceramic particles into aluminum magnesium silicon alloy by in-situ chemical reaction.At the same time, using extrusion pressure and rolling process, further refine the grain structure, strengthen the particle-matrix interface, so as to obtain the aluminum magnesium silicon alloy-based composite material mainly with α-Al and ceramic reinforced particles, which has excellent strength and plasticity under T6 condition.

Description

Technical Field

[0001] This invention relates to a high-strength, high-toughness aluminum-magnesium-silicon alloy-based composite material and its preparation method. Background Technology

[0002] In the past, aluminum-magnesium-silicon alloys (AMgSilicon) were widely used in the manufacture of high-strength automotive body parts due to their age-hardening properties. These alloys are formed under solution-treated conditions and then aged to impart strength. Because these alloys are transported under solution-treated conditions, long-term storage at room temperature is a serious problem, leading to performance degradation due to natural aging. Furthermore, these alloys exhibit grain growth during solution treatment and display moderate strength and poor ductility under aging conditions, thus limiting their formability. For the manufacture of high-performance automotive body parts, the strength-ductility relationship of AMgSilicon alloys is quite complex. Therefore, there is a need to develop new materials that offer higher strength and high ductility under aging conditions to achieve greater formability. Summary of the Invention

[0003] The purpose of this invention is to provide a ceramic particle-reinforced high-strength and high-toughness aluminum-magnesium-silicon alloy matrix composite material and its preparation method. While maintaining good formability, the ceramic particle-reinforced aluminum-magnesium-silicon alloy matrix composite material exhibits excellent comprehensive mechanical properties, thereby meeting the performance requirements of the automotive industry for sheet metal parts.

[0004] Extensive literature review revealed that the properties of aluminum-magnesium-silicon alloys are highly sensitive to grain structure and processing methods. As-cast alloys exhibit irregular, coarse grain sizes (>100 μm) and show grain growth during annealing due to particle dissolution. During aging, as the strength of the aluminum-magnesium-silicon alloy increases, its ductility decreases due to the excessively large grain size, hindering the plastic forming of high-strength automotive parts. To address this issue, this invention introduces ceramic particles into the aluminum-magnesium-silicon alloy through an in-situ chemical reaction. Simultaneously, extrusion pressure and rolling processes are employed to further refine the grain structure and strengthen the particle-matrix interface, thereby obtaining an aluminum-magnesium-silicon alloy matrix composite material primarily composed of α-Al and ceramic reinforcing particles, exhibiting excellent strength and plasticity under T6 conditions.

[0005] Based on this, the solution adopted by the present invention is as follows: First, the present invention relates to a ceramic particle-reinforced high-strength and high-toughness aluminum-magnesium-silicon alloy-based composite material, wherein the weight percentage of each element is: Mg = 0.48-0.52%, Si = 0.90-1.1%, Fe = 0.50-0.60%, Cu = 0.50-60%, Mn = 0.11-0.15%, Zn = 0.99-1.50%, B = 0.20-1.25%, Zr > 0.25%. The total amount of other impurities is less than 0.2 wt%, with the balance being Al.

[0006] Secondly, this invention also relates to a method for preparing a ceramic particle-reinforced high-strength and high-toughness aluminum-magnesium-silicon alloy-based composite material, comprising the following steps:

[0007] S1. Material preparation: Prepare materials according to the weight percentage of aluminum-magnesium-silicon alloy; obtain pure magnesium and Al-20%Si master alloys of Mg and Si; obtain industrial-grade KBF4, K2ZrF6 and Na2B4O7 salts in powder form.

[0008] S2. Melting: Add aluminum-magnesium-silicon alloy and raise the temperature to 850-900℃ to obtain a melt. Add industrial-grade KBF4, K2ZrF6, and Na2B4O7 salts to the melt and apply an electromagnetic field (magnetic field frequency: 10Hz, excitation current: 100A) for 25-30 minutes to produce ceramic particles through a chemical reaction. During the reaction, the temperature is controlled within the range of 850-950℃. After the chemical reaction, the slag is removed at 780℃. Then, lower the melt temperature to 700℃. Press the weighed pure Mg and Al-20%Si master alloy into the bottom of the melt and maintain the temperature within the range of 680-700℃ for 10 minutes to adjust the composition.

[0009] S3. Cleaning and Degassing: After adjusting the composition, raise the melt temperature to 720°C, inject the refining agent powder into the melt for degassing, and clean the melt by removing the slag.

[0010] S4. Casting and Rolling: After refining at 720°C, the melt is poured into a steel mold. The cured composite material is remelted at 650°C for 5 minutes. A melt extrusion process is performed using a manual press, maintaining pressure (10-20 MPa) for 5 minutes to obtain the cured composite material. Plates (80mm × 30mm × 12mm) are cut from the composite material. After homogenization at 450°C for 1 hour, the thickness of each slab is gradually reduced through multiple rolling passes (e.g., 6.5mm, 4.5mm, 2.5mm), with a 10-minute holding time at 450°C between each rolling pass. The rolled slabs are then quenched in water.

[0011] Preferably, step S1 further includes preheating the raw salt to 250°C for drying.

[0012] Preferably, step S2 further includes waiting time for the melt reaction and stirring with an electromagnetic field to ensure uniform dispersion of the salt, performing melt composition analysis, and adjusting the composition to the desired range.

[0013] Preferably, the melting reaction time in step S2 is 25-30 minutes.

[0014] Preferably, step S2 further includes a process of melt composition analysis and adjustment.

[0015] Preferably, the refining agent in step S3 is a salt-based flux that does not contain Na ions.

[0016] Preferably, the extrusion temperature in step S4 is 640-650°C.

[0017] Preferably, the extrusion pressure in step S4 is 10-20 MPa.

[0018] Preferably, the annealing temperature for hot rolling in step S4 is 450°C, lasting for 1 hour.

[0019] Preferably, the thickness in step S4 is gradually reduced from 12 mm to 6.5 mm (45%), 4.5 mm (60%) and 2.5 mm (80%) through multiple rolling processes.

[0020] Preferably, the homogenization time between each rolling pass in step S4 is 10 minutes.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The ceramic particle-reinforced high-strength and high-toughness aluminum-magnesium-silicon alloy matrix composite material prepared by this invention has important industrial applications.

[0023] 2. The ceramic particle-reinforced aluminum-magnesium-silicon alloy matrix composite material exhibits excellent properties such as tensile strength of 344 MPa and fracture strain of ≈23% under heat treatment T6, and can obtain good formability, meeting the requirements of thin-walled metal sheet parts in the automotive industry. Attached Figure Description

[0024] Other features and advantages of the invention will become clearer after reading the detailed description in relation to the following figures:

[0025] Figure 1 The XRD pattern of the ceramic particle-reinforced aluminum-magnesium-silicon alloy matrix composite is shown.

[0026] Figure 2 The microstructure of ceramic particle-reinforced aluminum-magnesium-silicon alloy matrix composites is shown: Here, (a,c) 1 vol.% is mixed with (b,d) 2 vol.% is mixed with

[0027] Figure 3 The room temperature engineering stress versus engineering strain curves of aluminum-magnesium-silicon alloy matrix composites are shown: Here, (a,c) 1 vol.% of the mixture is mixed with (b,d) 2 vol.% of the mixture. Detailed Implementation

[0028] The present invention will now be described in detail with reference to specific tasks. These tasks will help those skilled in the art to further understand the invention without limiting its scope.

[0029] Example 1

[0030] The weight percentage of each element, in 1 vol.% of the ceramic particle-reinforced high-strength and high-toughness aluminum-magnesium-silicon alloy matrix composite material in this embodiment is as follows: Mg = 0.52%, Si = 1.10%, Fe = 0.55%, Cu = 0.50%, Mn = 0.11%, Zn = 0.99%, B = 0.20%, Zr > 0.25%. The total amount of other impurities is less than 0.2 wt.%, with the balance being Al.

[0031] The preparation of the high-strength and high-toughness aluminum-magnesium-silicon alloy-based composite material in this embodiment includes the following steps:

[0032] 1) Drying: The raw materials, including aluminum-magnesium-silicon alloy, pure magnesium, Al-20%Si master alloy, and industrial-grade KBF4, K2ZrF6 and Na2B4O7 salt, are preheated at 250℃ for 5 hours for drying.

[0033] 2) Melting: An induction furnace and graphite crucible are selected for composite material synthesis. The weighed aluminum-magnesium-silicon alloy is melted. After melting, the temperature is raised to 850-900℃. Industrial-grade KBF4, K2ZrF6, and Na2B4O7 salts are added to the melt to synthesize ceramic particles through in-situ reaction, and an electromagnetic field (magnetic field frequency: 10Hz, excitation current: 100A) is turned on for 30 minutes. During this period, the temperature is controlled within the range of 850-950℃. After the reaction is complete, the temperature is lowered to 780℃, and the slag is removed. The composition of the melt is analyzed. The melt temperature is lowered to 700℃. Weighed pure Mg and Al-20%Si master alloy are added and pressed to the bottom of the melt. The melt is stirred, and the temperature is controlled at 680-700℃ for 10 minutes to ensure the composition reaches the appropriate range. The melt temperature is raised to 720℃, and refining agent powder is injected into the melt for degassing and cleaning.

[0034] 3) Casting: After refining, the melt is cast into a steel mold (L=80mm, W=70mm, T=60mm) for solidification. The composite material is then remelted in a resistance heating furnace at ~650℃ for 5 minutes, followed by extrusion using a manual press at a pressure of 10-20MPa. The composite extruded at 10MPa is designated A1, and the composite extruded at 20MPa is designated A4.

[0035] 4) Rolling: Slabs with L=80mm, W=30mm, and T=12mm were cut from the extrusion-cast composite material. After homogenization at approximately 450°C for 1 hour, the thickness of one A1 slab was reduced from 12mm to 4.5mm (labeled A2) and another slab to 2.5mm (labeled A3) through multiple rolling passes, with a holding time of 10 minutes between each rolling pass. Similarly, the thickness of one A4 slab was reduced from 12mm to 6.5mm (labeled A5). The rolled composite slabs were cooled by quenching them in water at room temperature.

[0036] Example 2

[0037] The weight percentage of each element, in 2 vol.% of the ceramic particle-reinforced high-strength and tough aluminum-magnesium-silicon alloy matrix composite material in this embodiment is as follows: Mg = 0.48%, Si = 1.08%, Fe = 0.57%, Cu = 0.62%, Mn = 0.15%, Zn = 1.50%, B = 1.25%, Zr > 0.25%. The total amount of other impurities is less than 0.2 wt.%, with the balance being Al.

[0038] The preparation of the high-strength and high-toughness aluminum-magnesium-silicon alloy-based composite material in this embodiment includes the following steps:

[0039] 1) Drying: The raw materials, including aluminum-magnesium-silicon alloy, pure magnesium, Al-20%Si master alloy, and industrial-grade KBF4, K2ZrF6 and Na2B4O7 salt, are preheated at 250℃ for 5 hours for drying.

[0040] 2) Melting: An induction furnace and graphite crucible are selected for composite material synthesis. The weighed aluminum-magnesium-silicon alloy is melted. After melting, the temperature is raised to 850-900℃. Industrial-grade KBF4, K2ZrF6, and Na2B4O7 salts are added to the melt to synthesize ceramic particles through in-situ reaction, and an electromagnetic field (magnetic field frequency: 10Hz, excitation current: 100A) is turned on for 30 minutes. During this period, the temperature is controlled within the range of 850-950℃. After the reaction is complete, the temperature is lowered to approximately 780℃, and the slag is removed. The composition of the melt is analyzed. The melt temperature is lowered to 700℃. A weighed amount of pure Mg and Al-20%Si master alloy is added to and pressed into the bottom of the melt. The melt is stirred, and the temperature is controlled at 680-700℃ for 10 minutes to ensure the composition reaches the appropriate range. The melt temperature is raised to 720℃, and refining agent powder is injected into the melt for degassing and cleaning.

[0041] 3) Casting: After refining, the melt is cast into a steel mold (L=80mm, W=70mm, T=60mm) for solidification. The composite material is then remelted in a resistance heating furnace at ~650℃ for 5 minutes, followed by extrusion using a manual press at a pressure of 10-20MPa. The composite extruded at 10MPa is designated B1, and the composite extruded at 20MPa is designated B4.

[0042] 4) Rolling: Slabs with L=80mm, W=30mm, and T=12mm were cut from the extrusion-cast composite material. After homogenization at approximately 450°C for 1 hour, the thickness of one B1 slab was reduced from 12mm to 4.5mm (labeled B2) and another slab to 2.5mm (labeled B3) through multiple rolling passes, with a holding time of 10 minutes between each rolling pass. Similarly, the thickness of one B4 slab was reduced from 12mm to 6.5mm (labeled B5). The rolled composite slabs were cooled by quenching them in water at room temperature.

[0043] The microstructure of samples obtained from castings A1, A4, B1, and B4 was observed. To visualize the grain structure more clearly, the samples were etched for 30 seconds using a 0.5% HF solution. The microstructure is shown below. Figure 1 As shown: (a) represents the microstructure of A1 in Example 1; (c) represents the microstructure of A4 in Example 1; (b) represents the microstructure of B1 in Example 2; and (d) represents the microstructure of B4 in Example 2. The results indicate that the composite material possesses a fine microstructure. Microstructure comparison has demonstrated that the ceramic reinforcing particles incorporated in this invention play a crucial role in refining the microstructure.

[0044] The samples obtained from the proposed implementation were subjected to room temperature tensile tests. The tensile stress-strain curves of specimens A1-A5 and B1-B5 are shown below. Figure 2 As shown in Table 1, the room temperature mechanical properties are summarized.

[0045] Table 1 shows the room temperature mechanical properties of aluminum-magnesium-silicon alloy matrix composites from various embodiments.

[0046] By comparing the room-temperature mechanical properties of test bars A1-A5 and B1-B5, it can be demonstrated that the extrusion and rolling of the aluminum-magnesium-silicon alloy-based composite material in this invention can significantly improve the mechanical properties, especially the ductility. Comparing the properties of A1-A5 and B1-B5 shows that ceramic particles and extrusion pressure can refine the microstructure and have a significant impact on mechanical properties. Higher extrusion pressures result in a more refined microstructure. When the alloy composition and ceramic particle content are within the range of claim 1, the mechanical properties of the A1-A5 and B1-B5 composite materials at room temperature are: ultimate tensile strength = 166–214 MPa, elongation under non-heat-treated conditions = 10–14%; ultimate tensile strength = 280–376 MPa, elongation under heat-treated T6 conditions = 16–26%.

[0047] The above is merely one embodiment of the present invention and therefore does not limit the scope of the invention. Any equivalent structural or process modifications made using the present invention specification or directly or indirectly applied to other related technical fields are also included within the patent protection scope of the present invention.

[0048] Table 1

[0049]

Claims

1. A method for preparing a high-strength, high-toughness aluminum-magnesium-silicon alloy-based composite material, wherein the weight percentage of each element in the high-strength, high-toughness aluminum-magnesium-silicon alloy-based composite material is: Mg=0.48-0.52%, Si=0.90-1.1%, Fe=0.50-0.60%, Cu=0.50-60%, Mn=0.11-0.15%, Zn=0.99-1.50%, B=0.20-1.25%, Zr>0.25%, the total amount of other impurities is less than 0.2wt%, and the balance is Al, characterized in that... The specific steps are as follows: S1. Material preparation: Prepare materials according to the weight percentage of aluminum-magnesium-silicon alloy; obtain pure magnesium and Al-20%Si master alloys of Mg and Si; obtain industrial-grade KBF4, K2ZrF6 and Na2B4O7 salts in powder form; S2. Melting: Add aluminum-magnesium-silicon alloy, raise the temperature to 850-900°C to obtain a melt, add industrial-grade KBF4, K2ZrF6 and Na2B4O7 salts to the melt, and apply an electromagnetic field to produce ceramic particles through a chemical reaction; during the reaction, the temperature is controlled within the range of 850-950°C; after the chemical reaction, the slag is removed at 780°C, and then the melt temperature is lowered to 700°C; the weighed pure Mg and Al-20%Si master alloy are pressed into the bottom of the melt, and the temperature is maintained within the range of 680-700°C for composition adjustment; S3. Cleaning and Degassing: After adjusting the composition, raise the melt temperature to 720°C, inject the refining agent powder into the melt for degassing, and clean the melt by removing the slag; S4. Casting and rolling: After refining at 720°C, the melt is poured into a steel mold; the cured composite material is remelted at 650°C for 5 minutes; A melt extrusion process is performed using a manual press to obtain a cured composite material. Slabs are cut from the composite material, homogenized at 450°C for 1 hour, and then the thickness of each slab is gradually reduced through multiple rolling processes. Finally, the rolled slabs are quenched in water.

2. The method for preparing a high-strength, high-toughness aluminum-magnesium-silicon alloy-based composite material as described in claim 1, characterized in that, Step S1 also includes preheating the raw salt to 250°C for drying.

3. The method for preparing a high-strength, high-toughness aluminum-magnesium-silicon alloy-based composite material as described in claim 1, characterized in that, In step S2, the salt is stirred by an electromagnetic field to make it evenly dispersed. The electromagnetic field frequency is 10Hz and the excitation current is 100A.

4. The method for preparing a high-strength, high-toughness aluminum-magnesium-silicon alloy-based composite material as described in claim 1, characterized in that, In step S2, the melting reaction takes 25-30 minutes.

5. The method for preparing a high-strength, high-toughness aluminum-magnesium-silicon alloy-based composite material as described in claim 1, characterized in that, Step S2 also includes a process of melt composition analysis and adjustment, in which the temperature is maintained in the range of 680-700°C for 10 minutes to adjust the composition.

6. The method for preparing a high-strength, high-toughness aluminum-magnesium-silicon alloy-based composite material as described in claim 1, characterized in that, In step S3, the refining agent is a salt-based flux that does not contain Na ions.

7. The method for preparing a high-strength, high-toughness aluminum-magnesium-silicon alloy-based composite material as described in claim 1, characterized in that, In step S4, the extrusion temperature is 640-650°C, the extrusion pressure is 10-20MPa, and the pressure is held for 5 minutes.

8. The method for preparing a high-strength, high-toughness aluminum-magnesium-silicon alloy-based composite material as described in claim 1, characterized in that, In step S4, the annealing temperature for hot rolling is 450°C for 1 hour, and the temperature is held at 450°C for 10 minutes between each rolling pass.

9. The method for preparing a high-strength, high-toughness aluminum-magnesium-silicon alloy-based composite material as described in claim 1, characterized in that, In step S4, the slab size is 80mm×30mm×12mm. The thickness of the slab is gradually reduced from 12mm to 6.5mm, 4.5mm and 2.5mm through multiple rolling processes.

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