An ultra-high strength and toughness aluminum-based composite material and its preparation method

Abstract

This invention discloses an ultra-high strength and toughness aluminum-based composite material and its preparation method. The method includes: S1, preparing partially amorphous aluminum-based alloy powder A using ultrasonic gas atomization; S2, mixing pure metal powder and boron powder according to the atomic percentage of AlNiTiZr-based aluminum-based amorphous alloy, adding a dispersant, and preparing powder B using mechanical alloying; S3, mixing powders A and B obtained in S1 and S2, and then performing spark plasma sintering; S4, hot extruding and heat-treating the sintered material to obtain the ultra-high strength and toughness aluminum-based composite material; in S1, the cooling rate is ≥10... 5 K / s. The ultra-high strength and toughness aluminum-based composite material of the present invention has a yield strength of about 700-800 MPa, a tensile strength of about 800-900 MPa, and an elongation of 5%-12%, and its strength and toughness are far superior to existing high strength and toughness aluminum alloy materials.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-based composite materials, and particularly relates to an ultra-high strength and toughness aluminum-based composite material and its preparation method. Background Technology

[0002] With the advancement of carbon peaking, carbon neutrality, and energy conservation and emission reduction strategies, high-strength and ultra-high-toughness aluminum-based composite materials are experiencing a period of explosive growth. Replacing steel and titanium with aluminum has become a crucial development direction for high-performance aluminum alloys and aluminum-based composite materials. Aluminum-based composite materials are generally made by adding ceramic reinforcing phases (SiC, Al2O3, etc.) to an aluminum matrix through methods such as stir casting and powder metallurgy. Compared to traditional aluminum alloys, they possess superior specific strength, specific stiffness, and wear resistance, and are widely used in aerospace, transportation, and weaponry equipment. For example, the United States, Japan, and the United Kingdom have developed SiC / Al, B / Al, and Al2O3 / Al aluminum-based composite materials and applied them to engine pistons, aircraft fuselages, wings, rudders, and skins. However, due to problems such as adverse reactions at the matrix-reinforcing phase interface or difficulties in controlling the content and uniform distribution of the reinforcing phase, the strength of these aluminum-based composite materials remains limited, around 500 MPa, comparable to 7000 series precipitation-hardening aluminum alloys, and the cost is relatively high, making it difficult to balance strength and toughness.

[0003] In existing methods, while the in-situ precipitated reinforcing phase obtained by stirred casting solves problems such as uniform dispersion and microstructure refinement of the reinforcing phase, achieving a high level of strength and toughness in aluminum matrix composites, the content of the ceramic phase can only be controlled at a relatively low level. High content easily leads to agglomeration, causing a decline in material properties. This determines that the aluminum matrix composites prepared by this method have reached their strength limit and are difficult to improve further. Although powder metallurgy methods facilitate powder composition design, they often suffer from problems such as undesirable interfacial reactions, coarsening of crystal structure, and insufficient sintering density. Moreover, the matrix materials mostly use conventional gas-atomized or water-atomized aluminum alloy powders, which have a high surface oxygen content, unfavorable for the formation of sintering necks in powder metallurgy.

[0004] Therefore, the preparation of aluminum-based composite materials with a higher strength and toughness ratio has become one of the bottleneck issues in the industry's development. How to design and prepare ultra-high strength and toughness aluminum-based composite materials with tensile strength exceeding 800 MPa while maintaining an elongation of 10%, and truly realize the replacement of steel and titanium with aluminum, to achieve low-cost and lightweight manufacturing of important equipment, requires further exploration and research. Summary of the Invention

[0005] Based on the above-mentioned technical problems, this invention proposes an ultra-high strength and toughness aluminum-based composite material and its preparation method on the basis of existing powder metallurgy technology, which can obtain an ultra-high strength and toughness aluminum-based composite material with a tensile strength exceeding 800 MPa and an elongation of about 10%.

[0006] The specific solution of this invention is as follows:

[0007] One objective of this invention is to provide a method for preparing the ultra-high strength and toughness aluminum-based composite material, comprising: S1, preparing partially amorphous aluminum-based alloy powder A using ultrasonic gas atomization; S2, mixing pure metal powder and boron powder according to the atomic percentage of AlNiTiZr-based aluminum-based amorphous alloy, adding a dispersant, and preparing powder B using mechanical alloying; S3, mixing powders A and B obtained in S1 and S2, and then performing spark plasma sintering; S4, hot extruding and heat-treating the sintered material to obtain the ultra-high strength and toughness aluminum-based composite material; in S1, the cooling rate is ≥10... 5 K / s.

[0008] Preferably, in S1, the aluminum-based alloy is a 7000 series aluminum alloy; more preferably, the aluminum-based alloy is selected from any one of 7075 aluminum alloy, 7055 aluminum alloy, and Al-10Zn-3.5Mg-1.5Cu.

[0009] Preferably, in S1, the partially amorphous aluminum-based alloy powder A contains a surface oxide layer with a thickness of 1-5 nm.

[0010] The method described in this invention is applicable to any aluminum-based alloy. A significant improvement in strength and toughness can be achieved using any aluminum alloy as the substrate. The reason this invention preferentially uses 7000 series aluminum alloys is because 7000 series aluminum alloys inherently possess superior properties. Based on this, ultra-high strength and toughness aluminum-based composite materials with tensile strength ≥800MPa and elongation maintained at around 10% can be obtained.

[0011] This invention employs ultrasonic gas atomization, with a cooling rate ≥10 5 Partially amorphous aluminum-based alloy powder A can be prepared under K / s (ultra-fast cooling) conditions. It has an extremely thin oxide film on its surface, high activity, no compositional segregation, and the amorphous content in powder A can be controlled by adjusting the cooling rate.

[0012] Preferably, in S2, the amount of boron powder added is based on the molar amount of Ti in the AlNiTiZr aluminum-based amorphous alloy, and the Ti:B molar ratio is 1:2-3.

[0013] Preferably, in S2, the dispersant is stearic acid or sodium stearate; the amount of dispersant added is 1-3 wt.% of the total amount of pure metal powder and boron powder.

[0014] Preferably, in S2, the mechanical alloying method is ball milling. Specifically, ball milling is carried out under an inert atmosphere, with a ball-to-material ratio of 10-20:1, a ball milling speed of 300-600 r / min, and a ball milling time of 50-80 h.

[0015] The AlNiTiZr-based aluminum amorphous alloy of the present invention has a wide supercooled liquid phase region. In step S2, a certain amount of boron powder is added, which can react with Ti in situ in the aluminum amorphous alloy to generate an endogenous TiB2 nanophase, which further strengthens the alloy.

[0016] Preferably, in step S3, the amount of powder B added is 1-40 wt.% of the total amount of powders A and B.

[0017] Preferably, in step S3, powders A and B are mixed using a low-energy ball milling method, wherein the ball milling speed is 100-300 r / min and the ball milling time is 100-300 min.

[0018] Preferably, in S3, the spark plasma sintering process includes: adding the mixed powders A and B into a graphite mold; under vacuum and room temperature conditions, slowly applying pressure to the graphite mold to 25 MPa and holding the pressure for 5 minutes; raising the temperature to 200°C and simultaneously applying pressure to 50 MPa, holding the temperature and pressure for 5 minutes; raising the temperature to 400°C and maintaining the pressure at 50 MPa for 3 minutes; raising the temperature to 450°C and maintaining the pressure at 50 MPa for 5 minutes; and finally raising the temperature to 500°C and maintaining the pressure at 50 MPa for 5 minutes.

[0019] Step S3 of this invention employs a spark plasma sintering process, which leverages the combined effects of particle discharge, conductive heating, and pressurization. Besides heating and pressurization, which promote sintering, the plasma generated by the pulsed current induces Joule heating in the particles within the sintered body, leading to localized surface melting and the shedding of surface materials. Furthermore, the high-temperature plasma sputtering and discharge impact remove impurities and adsorbed gases from the powder particle surface, promoting diffusion, achieving rapid sintering at low temperatures, and increasing density. This invention, using spark plasma sintering, can sinter ultrafine grains at low temperatures, thereby obtaining ultra-high strength and toughness aluminum-based composite materials.

[0020] Preferably, in S4, the hot extrusion temperature is 400-500℃, the extrusion ratio is 4-16:1, and the extrusion speed is 0.1-5mm / s; the heat treatment is the T6 heat treatment process.

[0021] The second objective of this invention is to provide an ultra-high strength and toughness aluminum-based composite material, which is prepared by any of the above methods.

[0022] The beneficial effects of this invention are:

[0023] This invention utilizes the high activity, high uniformity, and partially amorphous properties of ultrafast-cooled aluminum alloy powder, combined with in-situ reaction strengthening in powder metallurgy. By controlling the alloy composition and employing spark plasma sintering, hot extrusion, and heat treatment technologies, multi-dimensional composite strengthening of amorphous / nanocrystalline / endogenous precipitates during sintering is achieved, resulting in lightweight structural materials comparable to titanium alloys and high-strength steel. The ultra-high strength and toughness aluminum-based composite material exhibits a yield strength of approximately 700–800 MPa, a tensile strength of approximately 800–900 MPa, and an elongation of 5%–12%, demonstrating strength and toughness far superior to existing high-strength and toughness aluminum alloy materials. Attached Figure Description

[0024] Figure 1 SEM images of partially amorphous aluminum alloy powder A obtained in Example 1 at different magnifications:

[0025] Figure 2 The images shown are micrographs of powder B obtained in Example 1, where (a) is a SEAD image and (b) is a TEM image.

[0026] Figure 3 The image shows the EBSD diagram of the ultra-high strength and toughness aluminum-based composite material obtained in Example 1. Detailed Implementation

[0027] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0028] Example 1

[0029] A method for preparing an ultra-high strength and toughness aluminum-based composite material includes:

[0030] S1. Preparation of partially amorphized aluminum-based alloy powder A

[0031] An ultrasonic atomization device is used to control the cooling rate to ≥10. 5 K / s, after melting 7055 aluminum alloy, guides it to the inner wall of a tubular resonator excited by ultrasonic frequency, and is broken by vibration tension wave atomization; at the same time, nitrogen gas is introduced to generate unsteady shock wave, and pressure pulse further breaks the molten droplets atomized by tension wave, to obtain a partially amorphous aluminum alloy powder A with a surface oxide layer of 2nm.

[0032] The SEM images of the partially amorphized aluminum-based alloy powder A obtained in Example S1 at different magnifications are as follows: Figure 1 As shown, by Figure 1 (a) It can be seen that powder A is spherical powder; Figure 1 (b) It can be seen that the surface of powder A has an extremely thin oxide layer of 2-3 nm;

[0033] S2, Preparation of powder B

[0034] Based on the atomic percentage of Al76Ni8Ti8Zr4Y4 aluminum alloy, pure Al powder, Ni powder, Ti powder, Zr powder, Y powder, and boron powder were mixed, and 2 wt.% sodium stearate dispersant (the total amount of pure metal powder and boron powder) was added. Powder B was prepared by ball milling. The amount of boron powder added was based on the molar amount of Ti in the Al76Ni8Ti8Zr4Y4 aluminum alloy, with a Ti:B molar ratio of 1:2. The ball milling method specifically involved:

[0035] GCr15 bearing steel balls were selected, and the ball-to-material ratio was controlled at 10:1. Four types of grinding balls with diameters of 20mm, 12mm, 10mm, and 5mm were mixed together, with a ratio of 1:5:38:10. The ball mill speed was 400r / min. Under argon protection, the mill was stopped for 30 minutes every 2 hours to prevent the powder from overheating. The ball milling time was 80 hours.

[0036] The micrograph of powder B obtained in Example S2 is as follows: Figure 2 As shown;

[0037] S3, SPS sintering

[0038] Powder A obtained from S1 and powder B obtained from S2 were mixed using a low-energy ball milling method, wherein the amount of powder B added was 5 wt.% of the total amount of powders A and B; the mixed powder was then placed into a graphite mold for SPS sintering, and the specific sintering process is as follows:

[0039] ① Under vacuum and room temperature conditions, slowly apply pressure to the graphite mold up to 25 MPa and hold the pressure for 5 minutes;

[0040] ② Raise the temperature to 200℃, simultaneously apply pressure to 50MPa, and maintain the temperature and pressure for 5 minutes;

[0041] ③ Heat to 400℃, maintain pressure at 50MPa, and hold for 3 minutes;

[0042] ④ Heat to 450℃, maintain pressure at 50MPa, and hold for 5 minutes;

[0043] ⑤ Finally, raise the temperature to 500℃, maintain the pressure at 50MPa, and hold the temperature and pressure for 5 minutes;

[0044] S4, Hot Extrusion Forming and Heat Treatment

[0045] The hot extrusion temperature was controlled at 420℃, the extrusion ratio was 9:1, and the extrusion speed was 0.5mm / s. Then, the T6 heat treatment method was adopted, which is to first subject the hot extruded sample to 470℃ for 120min for solution treatment, and then age it at 120℃ for 24h to obtain the ultra-high strength and toughness aluminum-based composite material.

[0046] The EBSD diagram of the ultra-high strength and toughness aluminum-based composite material obtained in this embodiment is shown below. Figure 3 As shown.

[0047] Example 2

[0048] A method for preparing an ultra-high strength and toughness aluminum-based composite material includes:

[0049] S1. Preparation of partially amorphized aluminum-based alloy powder A

[0050] An ultrasonic atomization device is used to control the cooling rate to ≥10. 5 K / s, after melting Al-10Zn-3.5Mg-1.5Cu aluminum alloy, it is guided to the inner wall of a tubular resonator excited by ultrasonic frequency, and broken by vibration tension wave atomization; at the same time, nitrogen gas is introduced to generate unsteady shock wave, and pressure pulse further breaks the molten droplets atomized by tension wave, to obtain partially amorphous aluminum alloy powder A with a surface oxide layer of 2nm.

[0051] S2, Preparation of powder B

[0052] Based on the atomic percentage of Al70Ni10Ti10Zr5Ta5 aluminum alloy, pure Al powder, Ni powder, Ti powder, Zr powder, Ta powder, and boron powder were mixed, and sodium stearate dispersant (2 wt.% of the total amount of pure metal powder and boron powder) was added. Powder B was prepared by ball milling. The amount of boron powder added was based on the molar amount of Ti in the Al70Ni10Ti10Zr5Ta5 aluminum alloy, with a Ti:B molar ratio of 1:2. The specific parameters of the ball milling method were the same as in Example 1.

[0053] S3, SPS sintering

[0054] Powder A obtained in S1 and powder B obtained in S2 were mixed using a low-energy ball milling method, wherein the amount of powder B added was controlled to be 5 wt.% of the total amount of powder A and B; the mixed powder was placed into a graphite mold for SPS sintering, and the specific sintering process was the same as in Example 1.

[0055] S4, Hot Extrusion Forming and Heat Treatment

[0056] The hot extrusion temperature was controlled at 450℃, the extrusion ratio was 9:1, and the extrusion speed was 0.3 mm / s. Then, the T6 heat treatment method was adopted, which is to first subject the hot extruded sample to 500℃ for 120 min and then perform solution treatment, followed by aging treatment at 120℃ for 24 h to obtain ultra-high strength and toughness aluminum-based composite material.

[0057] Comparative Example 1

[0058] An aluminum-based composite material, the preparation method of which includes:

[0059] (1) Preparation of amorphous aluminum-based alloy powder A: Same as S1 in Example 1;

[0060] (2) Preparation of powder B: Same as S2 in Example 1;

[0061] (3) Powder A and powder B are mixed by low-energy ball milling, wherein the amount of powder B added is controlled to be 5 wt.%; the mixed powder is subjected to hot extrusion and heat treatment in sequence; specifically, the hot extrusion temperature is controlled at 420℃, the extrusion ratio is 9:1, and the extrusion speed is 0.5 mm / s; then the T6 heat treatment method is used, that is, the hot extruded sample is first subjected to 470℃ and kept at 120 min for solution treatment, and then aged at 120℃ / 24h to obtain the final product.

[0062] Comparative Example 2

[0063] An aluminum-based composite material, the preparation method of which includes:

[0064] (1) 7055 aluminum alloy powder was prepared by conventional gas atomization method;

[0065] (2) Preparation of powder B: Same as S2 in Example 1;

[0066] (3) SPS sintering: Same as S3 in Example 1;

[0067] (4) Hot extrusion forming and heat treatment: Same as S4 in Example 1.

[0068] The properties of the aluminum-based composite materials obtained in the above embodiments and comparative examples were tested, and the test results are shown in Table 1 below:

[0069] Table 1. Properties of Aluminum-based Composite Materials

[0070] Yield strength / MPa Tensile strength / MPa Elongation / % Example 1 793 825 10.2 Example 2 824 861 8.4 Comparative Example 1 645 706 7.5 Comparative Example 2 612 680 9.6

[0071] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an ultra-high strength and toughness aluminum-based composite material, characterized in that, include: S1. Partially amorphous aluminum-based alloy powder A is prepared by ultrafast cooling ultrasonic gas atomization; S2. Pure metal powder and boron powder are mixed according to the atomic percentage of AlNiTiZr aluminum-based amorphous alloy, a dispersant is added, and powder B is prepared by mechanical alloying; S3. Powders A and B obtained in S1 and S2 are mixed and then subjected to spark plasma sintering; S4. The sintered material is hot extruded and heat-treated to obtain an ultra-high strength and toughness aluminum-based composite material. In S1, the cooling rate is ≥10 5 K / s; In S1, the aluminum-based alloy is a 7000 series aluminum alloy; In S1, the partially amorphous aluminum-based alloy powder A contains a surface oxide layer with a thickness of 1-5 nm; In S2, the amount of boron powder added is based on the molar amount of Ti in the AlNiTiZr aluminum-based amorphous alloy, and the Ti:B molar ratio is 1:2-3. In S3, the amount of powder B added is 1-40 wt.% of the total amount of powders A and B.

2. The method for preparing ultra-high strength and toughness aluminum-based composite materials according to claim 1, characterized in that, The aluminum-based alloy is selected from any one of 7075 aluminum alloy, 7055 aluminum alloy, and Al-10Zn-3.5Mg-1.5Cu.

3. The method for preparing the ultra-high strength and toughness aluminum-based composite material according to claim 1 or 2, characterized in that, In S2, the dispersant is stearic acid or sodium stearate; the amount of dispersant added is 1-3 wt.% of the total amount of pure metal powder and boron powder.

4. The method for preparing the ultra-high strength and toughness aluminum-based composite material according to claim 1 or 2, characterized in that, In S2, the mechanical alloying method is ball milling. Specifically, ball milling is carried out under an inert atmosphere with a ball-to-material ratio of 10-20:1, a ball milling speed of 300-600 r / min, and a ball milling time of 50-80 h.

5. The method for preparing the ultra-high strength and toughness aluminum-based composite material according to claim 1 or 2, characterized in that, In S3, powders A and B are mixed using a low-energy ball milling method. The ball milling speed is 100-300 r / min and the ball milling time is 100-300 min.

6. The method for preparing the ultra-high strength and toughness aluminum-based composite material according to claim 1 or 2, characterized in that, In S4, the hot extrusion temperature is 400-500℃, the extrusion ratio is 4-16:1, and the extrusion speed is 0.1-5mm / s; the heat treatment is the T6 heat treatment process.

7. A high-strength and high-toughness aluminum-based composite material, characterized in that, It is prepared by the method described in any one of claims 1-6.

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