A gradient sequence titanium / aluminum isomeric composite material and a preparation method thereof

Abstract

The application discloses a gradient sequence titanium / aluminum isomer composite material and a preparation method thereof. The gradient sequence titanium / aluminum isomer composite material is obtained by compounding a gradient ordered titanium alloy lattice structure and an aluminum alloy. The gradient ordered titanium alloy lattice structure has holes with different sizes, and the holes are distributed in a gradient mode from small to large from inside to outside or from large to small from inside to outside. The aluminum alloy is filled in the holes of the gradient ordered titanium alloy lattice structure. The composite material has the characteristics of gradient ordered change of the base element soft and hard components, can inhibit local instability of plastic deformation of the components, and has the performance advantages of high strength, high specific strength and high specific modulus, so that the application field of the new type of lightweight high-strength titanium / aluminum composite structure material is expanded, and the composite structure material can be applied to the fields of aerospace, protective materials and rail transit and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of composite materials, and particularly relates to a gradient sequence titanium / aluminum heterogeneous composite material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of aerospace, rail transportation and other industries, people's demand for lightweight high-strength structural materials is increasingly urgent. Lightweight high-strength materials refer to new materials with high strength and light weight. Under the premise of meeting the performance requirements, lightweight high-strength structural materials can help improve the carrying capacity, increase the service life of materials, and reduce energy consumption. Lightweight high-strength materials have the performance characteristics of low density, high specific strength, and high specific modulus. Single metal structural materials have been difficult to meet the requirements of lightweight high-strength structural materials, and the development of heterogeneous composite materials with two or more metal characteristics has been increasingly valued.

[0003] Titanium alloy as a structural material has many excellent properties, such as high strength, high specific strength, corrosion resistance, and high temperature impact resistance, and has been widely used in the field of aerospace, such as being used to manufacture aircraft engine parts and fuselage components, satellites, etc. Pure titanium has excellent properties such as high specific strength, good plasticity, good low temperature toughness, and high corrosion resistance, and is mainly used to manufacture ship parts, aircraft skin, etc. However, pure titanium is expensive and has a significantly higher density than aluminum alloy, which limits its application. Aluminum alloy has the advantages of easy processing and good plasticity, and is one of the most widely used structural materials. 7 series and 2 series aluminum alloys have good mechanical properties, and typical alloy grades include 7075 aluminum alloy and 2024 aluminum alloy. 2024 aluminum alloy is a high-strength hard aluminum, while 7075 Al alloy belongs to super-hard aluminum alloy, which has a low density (density is only 2.7 g / cm 3) and other excellent properties (Wanda Y. Research on Selective Laser Melting of 7075 Aluminum Alloy and Its Composites[D]. South China University of Technology, 2019.). However, the highest tensile strength of current industrial aluminum alloy is less than 700 MPa, which is difficult to compete with high-strength steel and titanium alloy. Titanium / aluminum composite materials can fully exert the excellent properties of two light metals, such as high strength, low density, good thermal conductivity, etc. (Ma M, Meng X, Liu W C. Microstructure and mechanical properties of Ti / Al / Ti laminated composites prepared by hot rolling[J]. Journal of Materials Engineering and Performance, 2017, 26: 3569-3578.), which is expected to expand into a lightweight high-strength structural material.

[0004] Gradient materials are a new type of composite material composed of two or more materials with continuous gradient changes in composition and structure. It requires the material function and performance to change with the change of the internal position of the component, and through the design optimization of the overall performance of the component, a new type of functional material that can work normally repeatedly in extreme environments is developed. At present, there are few studies on gradient materials of titanium / aluminum composite materials, and most of them are micro-scale gradient designs. The research on macroscopic gradient materials needs to be further explored.

[0005] Additive manufacturing technology is a technology that uses gradual accumulation of materials to manufacture solid parts. Compared with traditional material removal-cutting processing technology, it is a "bottom-up" manufacturing method. Additive manufacturing technology can realize free manufacturing of parts and provide technical support for the preparation of three-dimensional ordered structure materials with complex shape. High-temperature extrusion refers to filling aluminum alloy powder into a three-dimensional continuous titanium alloy skeleton preform, applying a certain pressure at a temperature lower than the melting point of the aluminum alloy, and realizing the extrusion forming of the composite material to prepare titanium / aluminum composite materials. This process combines powder forming, densification, and heat treatment, effectively shortening the process flow, and compared with the melt infiltration process, it has higher density, fewer pore defects, and better forming quality.

[0006] Currently, the literature reports on the use of Ti6Al4V titanium alloy reinforced aluminum matrix composites as follows:(1) Selecting laser melting and hot extrusion to prepare nano-structured aluminum alloy / TC4 titanium alloy three-dimensional interpenetrating composites(Wang Y,Zhang W,Wang Z,et al.Preparation and mechanical properties of aluminum / titanium three-dimensional interpenetrating composites[J].Special Casting and Non-ferrous Alloys,2022,42(12):1506-1511). However, due to the high volume fraction of brittle intermetallic compounds in nano-aluminum alloy, cracks are easily initiated and propagated during loading, limiting the strength and plasticity of the composite. And the pores in the titanium alloy framework of the composite are uniformly distributed, unlike the gradient ordered structure of the titanium alloy framework, so that the performance of the material cannot change with the change of the pore size and other parameters inside the component, making it difficult for the material to withstand uneven stress and strain during high-strength loading, limiting the mechanical properties of the material.(2) Using laser selective melting technology to prepare TC4 titanium alloy honeycomb-like topological structure preform, and using vacuum pressure infiltration to infiltrate 7075 aluminum alloy into it to obtain 7075 / TC4 composite(Dong Z Y,Zhao H D,Yang C,et al.Preparation and mechanical properties of 7075 / TC4 composite[J].Powder Metallurgy Industry,2023,33(04):7-14.) However, the sharp corners of the regular hexagonal honeycomb structure of TC4 lattice are prone to stress concentration, leading to the premature initiation of cracks in the composite. And due to the flowability of the 7075 aluminum alloy liquid, the volume shrinkage during solidification cannot be fully compensated, resulting in a porosity of 3.39-5.75% in the composite, limiting its mechanical properties. In addition, the honeycomb-like pores in the titanium alloy framework of the composite are uniformly distributed, limiting the mechanical properties of the material under high-strength, uneven stress and strain loading conditions.(3) By selecting laser melting to prepare Al-Mg-Mn-Sc-Zr alloy honeycomb ordered structure, and using hot extrusion process to combine nano-aluminum alloy powder with honeycomb ordered structure to prepare aluminum matrix composite(Lin Y,Wang D,Yang C,et al.An Al-Al interpenetrating-phase composite by 3D printing and hot extrusion[J].International Journal of Minerals,Metallurgy and Materials,2023,30(4):678-688.) However, the maximum tensile strength of the current industrial aluminum alloy is less than 700 MPa, and the regular hexagonal honeycomb structure is also uniformly distributed, and the sharp corners of the honeycomb structure are prone to stress concentration, limiting the strength and plasticity of the aluminum matrix composite. In summary, the mechanical properties of the composites developed so far are limited by their materials or preparation processes, making it difficult to meet the application requirements as structural materials. SUMMARY

[0007] In order to solve the defects and deficiencies of the prior art, the purpose of the present application is to provide a gradient ordered structure titanium / aluminum heterogeneous composite material with gradient distribution of titanium alloy pore and aluminum alloy powder and a preparation method thereof; the present application adopts selective laser sintering additive manufacturing technology to realize accurate design and control of the gradient ordered structure of titanium alloy round hole, adopts high-temperature extrusion technology to make the two phases form good combination at the interface, and finally prepares a titanium / aluminum composite material with high strength, high specific strength and high elastic modulus.

[0008] The present application is based on the uneven stress and uneven strain of high-strength bulk materials during high-strength loading, and the gradient structure and ordered structure of high-specific composite materials are constructed and designed, the gradient distribution of titanium alloy round hole ordered structure is designed, the selective laser melting (SLM) additive manufacturing process which is widely used at present is selected to prepare the titanium alloy gradient ordered structure, and the high-temperature extrusion process is combined, so that the titanium alloy and aluminum alloy combined super high specific strength composite material can be prepared, the strength and toughness limit of the single structure of the lattice structure pore is broken through, and the application field of the new type of lightweight high-strength titanium / aluminum composite structure material is expanded.

[0009] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0010] A gradient ordered structure titanium / aluminum heterogeneous composite material is obtained by compounding a gradient ordered titanium alloy lattice structure with aluminum alloy; the gradient ordered titanium alloy lattice structure has holes of different sizes, and the holes are gradient distributed from small to large from inside to outside, or the holes are gradient distributed from large to small from inside to outside; the aluminum alloy is filled in the holes of the gradient ordered titanium alloy lattice structure; the volume fraction of the gradient ordered titanium alloy lattice structure is 20-70%, and the volume fraction of the aluminum alloy is 30-80%.

[0011] Preferably, the titanium alloy is one or both of Ti6Al4V titanium alloy and pure titanium; the aluminum alloy is one or both of 7-series aluminum alloy and 2-series aluminum alloy.

[0012] Further preferably, the 7-series aluminum alloy is 7075Al alloy or 7050Al alloy, and the 2-series aluminum alloy is 2024Al alloy or 2014Al alloy.

[0013] Preferably, the holes of the gradient ordered titanium alloy lattice structure are round holes; the gradient ordered titanium alloy lattice structure is a cylinder, there are a large number of round hole through holes on the cross section of the cylinder, and all the round holes are distributed in a circular or hexagonal shape around the center hole.

[0014] Further preferably, the diameter of the circular hole, the radial hole spacing, and the circular hole distribution parameter of the gradient-ordered titanium alloy lattice structure continuously change with the radial direction of the cylinder to form a gradient distribution, and the volume fraction of titanium alloy decreases from 80% to 20% from the outside to the inside, while the volume fraction of aluminum alloy increases from 20% to 80% from the outside to the inside, or the volume fraction of aluminum alloy increases from 20% to 80% from the outside to the inside, while the volume fraction of aluminum alloy decreases from 80% to 20% from the outside to the inside.

[0015] Further preferably, the diameter of the cylinder is 10-18 mm, and the height is 20-50 mm.

[0016] Further preferably, the diameter of the circular hole is 0.311-0.689 mm, the radial spacing between the circular holes is 0.1-0.4 mm, and the number of circular holes in the circular distribution is 6-44.

[0017] Preferably, the theoretical density of the gradient-ordered titanium / aluminum heterogeneous composite material is 3.13-3.83 g / cm 3 .

[0018] The preparation method of the gradient-ordered titanium / aluminum heterogeneous composite material described above comprises the following steps:

[0019] (1) Preparation of a gradient-ordered titanium alloy lattice structure

[0020] Spherical titanium alloy powder is used to form a gradient-ordered titanium alloy lattice structure by selective laser melting technology, and annealing treatment is performed;

[0021] (2) Filling aluminum alloy powder into the gradient-ordered titanium alloy lattice structure

[0022] The gradient-ordered titanium alloy lattice structure obtained in step (1) is placed in a pure copper jacket, aluminum alloy powder is added into the gradient-ordered titanium alloy lattice structure and cold extrusion is performed to obtain a bulk billet, and the bulk billet obtained by cold extrusion is subjected to high-temperature extrusion to obtain a gradient-ordered titanium / aluminum heterogeneous composite material.

[0023] Preferably, the diameter of the circular hole in the gradient-ordered titanium alloy lattice structure in step (1) increases or decreases from the center to the outside, and is 1-1.8 mm, forming 4-6 layers of circumferential arrays; the minimum spacing between adjacent holes in the radial direction is 0.2-0.6 mm; and the number of circular holes in the circumferential direction is 6-44.

[0024] Preferably, the annealing temperature in step (1) is 750-1000°C, and the annealing time is 3-6 h.

[0025] Preferably, the average particle size of the aluminum alloy powder in step (2) is 13-53 μm;

[0026] Preferably, the pressure for the cold extrusion forming in step (2) is 600-1000 MPa, and the pressure holding time is 3-6 min.

[0027] Preferably, the temperature for the high-temperature extrusion in step (2) is 350-500 ℃, the extrusion pressure is 400-1000 MPa, the extrusion speed is 2-6 mm / s, and the extrusion ratio is 4-8:1.

[0028] Preferably, the mold is preheated to 300-450 ℃ before the high-temperature extrusion in step (2).

[0029] Preferably, the sleeve is placed on an ultrasonic and mechanical vibration machine for vibration before the cold extrusion forming.

[0030] Finally, the principle of the present application is that the 7-series and 2-series aluminum alloys have low density, high strength, and good plasticity, and can coordinate deformation with the Ti6Al4V or pure titanium lattice under high stress, inhibit premature failure, and are beneficial to expanding the mechanical properties of the composite material. By selecting the above two materials with different properties, the pore diameter, spacing, or arrangement of the two materials from the inside to the outside is gradually changed, the material properties change with the change of the material structure, and a gradient material with performance change characteristics is formed.

[0031] The preparation method and the obtained composite material of the present application have the following advantages and beneficial effects:

[0032] (1) The gradient structure of the Ti6Al4V or pure titanium lattice can be designed and controlled in multiple ways, and the preparation method of the gradient ordered structure integrates the advantages of the 3D printing technology, so that the titanium alloy gradient ordered structure can be designed and prepared more freely.

[0033] (2) The 7-series and 2-series aluminum alloys have the advantages of low density, high modulus, and good plasticity, which can help the composite material to obtain lower density, higher specific modulus, and more excellent comprehensive mechanical properties.

[0034] (3) The high-temperature extrusion process enables the composite material to achieve good metallurgical bonding and excellent density; at the same time, the extrusion ratio parameter can be controlled to make the composite material obtain different levels of mechanical properties, and when the extrusion ratio reaches the maximum, the composite material has the optimal strength value.

[0035] (4) The gradient ordered change characteristics of the soft and hard components of the gradient ordered titanium / aluminum heterogeneous composite material can inhibit local instability of the component plastic deformation and realize the synergistic improvement of strength and toughness. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A three-dimensional model diagram of Ti6Al4V titanium alloy reinforced 7075 Al alloy gradient sequential structure Ti / Al isomeric composite material designed for Example 1.

[0037] Figure 2 A tensile curve diagram of Ti6Al4V titanium alloy reinforced 7075 Al alloy gradient sequential structure Ti / Al isomeric composite material and pure 7075 Al alloy prepared for Example 1.

[0038] Figure 3 A transverse and longitudinal optical microscope diagram of Ti6Al4V titanium alloy reinforced 7075 Al alloy gradient sequential structure Ti / Al isomeric composite material prepared for Examples 1, 2, and 3.

[0039] Figure 4 A three-dimensional modeling diagram of the gradient sequential structure Ti / Al isomeric composite material in Example 4.

[0040] Figure 5 A physical diagram of the Ti6Al4V titanium alloy round hole gradient sequential structure obtained by 3D printing in Example 4.

[0041] Figure 6 A physical diagram of the Ti6Al4V titanium alloy round hole gradient sequential structure obtained by 3D printing in Example 5.

[0042] Figure 7 A transverse and longitudinal optical microscope diagram of the infiltrated Ti6Al4V titanium alloy sequential structure reinforced 7075 Al alloy composite material by hot extrusion with an 8:1 extrusion ratio in Comparative Example 1.

[0043] Figure 8 A transverse and longitudinal optical microscope diagram of the Al 84 A transverse and longitudinal optical microscope diagram of the Ni7Gd6Co3 / TC4 composite material at an 8:1 extrusion ratio.

[0044] Figure 9 A transverse and longitudinal optical microscope diagram of pure Al 84 A tensile curve diagram of the Ni7Gd6Co3 alloy and the Al 84 A tensile curve diagram of the Ni7Gd6Co3 / TC4 composite material. DETAILED DESCRIPTION

[0045] In order to facilitate the understanding of the present application, the present application will be described in more detail and in a more complete and specific manner below in conjunction with the accompanying drawings and preferred embodiments, but the scope of protection of the present application is not limited to the following specific embodiments.

[0046] Example 1

[0047] The raw materials required for preparing the Ti6Al4V titanium alloy reinforced 7075 Al alloy composite material in this embodiment are: Ti6Al4V titanium alloy powder with a particle size distribution of 15-53 μm, pure copper, and 7075 Al alloy powder prepared by gas atomization method with a particle size of 48 μm. The preparation method of the Ti6Al4V titanium alloy reinforced 7075 Al alloy material described in this embodiment. Specifically includes the following steps:

[0048] (1) Design a Ti6Al4V titanium alloy lattice with a circular hole structure by using a three-dimensional modeling software UG. The size of the lattice skeleton is Ф11.8 x 35 mm. The diameter of the ordered structure circular hole is 1 mm, the minimum spacing between the ordered structure through holes is 0.5 mm, there are six circular holes around any one circular hole, and the six circular holes can form a regular hexagon with the center connected, and the side length of the regular hexagon is 1.5 mm. A three-dimensional model of the lattice is established. The Ti6Al4V titanium alloy is printed by using an EOSINT M280 type metal 3D printer, and the porosity is 40%;

[0049] (2) Put the Ti6Al4V titanium alloy skeleton printed in step (1) into a vacuum heat treatment furnace, and heat at 800℃ for 4 hours, and then cool in the furnace;

[0050] (3) The Ti-6Al-4V titanium alloy skeleton model obtained in step (2) is treated by abrasive flow. The abrasive used in the abrasive flow is silicon carbide, the abrasive flow pressure is 100 Kg, and the abrasive flow time is 4 h. The residual powder attached to the surface of the lattice material is removed;

[0051] (4) Put the three-dimensional Ti-6Al-4V titanium alloy skeleton obtained in step (3) into a pure copper jacket, inject 7075 Al alloy powder into the Ti6Al4V titanium alloy in the jacket, seal the jacket, place the jacket on an ultrasonic mechanical vibration machine for vibration, and finally perform normal temperature extrusion forming treatment on the Ti6Al4V titanium alloy skeleton / aluminum alloy powder composite material, with a pressure of 700 MPa and a pressure holding time of 3 min;

[0052] (5) Put the Ti6Al4V titanium alloy / 7075 Al alloy powder composite material after normal temperature extrusion in step (4) into a resistance furnace and preheat to 450℃, and then put it into a high temperature extrusion equipment for extrusion molding. The mold is preheated to 450℃, the extrusion pressure is about 700 MPa, the extrusion speed is 2.7 mm / s, the extrusion ratio is 8:1, the lubricant is graphite powder, and after the hot extrusion is completed, the rod is cut and shaped to obtain the Ti6Al4V titanium alloy reinforced 7075 Al alloy material.

[0053] Figure 1 The three-dimensional model diagram of the Ti6Al4V titanium alloy reinforced 7075 Al alloy composite material is shown; Figure 2The tensile curves are for the composite material and pure 7075Al alloy in Example 1.

[0054] Testing revealed that the actual yield strength of the Ti6Al4V titanium alloy reinforced 7075Al alloy was 1077 MPa, far exceeding the theoretical yield strength of 722 MPa calculated using the mixed-strength method. Its tensile strength reached 1138 MPa, elongation after fracture was 5.7%, Vickers hardness was 309 HV, and density was 3.73 g / cm³. 3 Furthermore, its specific strength and specific modulus are 305 Nm / g and 32 GPa / g / cm, respectively. 3 It significantly exceeds Ti6Al4V (specific strength 224 Nm / g; specific modulus 24 GPa / g / cm). 3 ) and 7075Al (specific strength 180 Nm / g; specific modulus 26 GPa / g / cm) prepared under the same conditions 3 And through Figure 2 It can be seen that, compared with the 7075Al metal material commonly used in industry, the specific strength and specific modulus of Example 1 have significant advantages.

[0055] Example 2

[0056] The raw materials required for preparing the Ti6Al4V titanium alloy reinforced 7075Al alloy composite material in this embodiment are: Ti6Al4V titanium alloy powder with a particle size distribution of 15-53 μm, pure copper, and 7075Al alloy powder with a particle size of 48 μm prepared by gas atomization. The preparation method of the Ti6Al4V titanium alloy reinforced 7075Al alloy material described in this embodiment specifically includes the following steps:

[0057] (1) This step is the same as step (1) in Example 1;

[0058] (2) This step is the same as step (2) in Example 1;

[0059] (3) This step is the same as step (3) in Example 1;

[0060] (4) This step is the same as step (4) in Example 1;

[0061] (5) The difference between this step and step (5) in Example 1 is that the extrusion ratio of high temperature extrusion is 6:1.

[0062] Testing revealed that the Ti6Al4V titanium alloy reinforced 7075Al alloy material exhibits a tensile strength of 1064 MPa, an elongation after fracture of 4.3%, a Vickers hardness of 297 HV, and a density of 3.73 g / cm³. 3 .

[0063] Example 3

[0064] The raw materials required for preparing the Ti6Al4V titanium alloy reinforced 7075Al alloy composite material in this embodiment are: Ti6Al4V titanium alloy powder with a particle size distribution of 15-53 μm, pure copper, and 7075Al alloy powder with a particle size of 48 μm prepared by gas atomization. The preparation method of the Ti6Al4V titanium alloy reinforced 7075Al alloy material described in this embodiment specifically includes the following steps:

[0065] (1) This step is the same as step (1) in Example 1;

[0066] (2) This step is the same as step (2) in Example 1;

[0067] (3) This step is the same as step (3) in Example 1;

[0068] (4) This step is the same as step (4) in Example 1;

[0069] (5) The difference between this step and step (5) in Example 1 is that the extrusion ratio of high temperature extrusion is 4:1.

[0070] Testing revealed that the Ti6Al4V titanium alloy reinforced 7075Al alloy material exhibits a tensile strength of 936 MPa, an elongation after fracture of 3.8%, a Vickers hardness of 280 HV, and a density of 3.73 g / cm³. 3 .

[0071] Figure 3 The images show the transverse and longitudinal optical microscopic images of the Ti6Al4V titanium alloy reinforced 7075Al alloy composite materials prepared in Examples 1, 2, and 3. It can be seen that the columnar porous structure of Ti6Al4V titanium alloy is fully filled with 7075Al with good plasticity, and almost no defects such as pores and cracks can be observed at the interface. A good metallurgical bond is formed between the two materials.

[0072] Example 4

[0073] The raw materials required for preparing the Ti6Al4V titanium alloy reinforced 7075Al alloy composite material in this embodiment are: Ti6Al4V titanium alloy powder with a particle size distribution of 15-53 μm, pure copper, and 7075Al alloy powder with a particle size of 48 μm prepared by gas atomization. The preparation method of the Ti6Al4V titanium alloy reinforced 7075Al alloy material described in this embodiment specifically includes the following steps:

[0074] (1) The difference between this step and step (1) in Example 1 is that the Ti6Al4V titanium alloy dot matrix with circular holes is designed using the 3D modeling software UG. The size of the dot matrix skeleton is Ф17.2×35mm. In the Ti6Al4V titanium alloy circular hole gradient ordered structure obtained by 3D printing, the diameter of the circular holes gradually increases from the center to the outside, which are 1mm, 1.2mm, 1.4mm, 1.6mm and 1.8mm respectively. The diameter of each circular array (the circle formed by the center of the circular holes on the circular array) is 3mm, 6.4mm, 10.2mm and 14.4mm respectively. The number of circular holes in each circular array is 6, 10, 13 and 18 respectively. The minimum spacing between adjacent holes in the radial direction is 0.4mm. The circular holes are distributed in a circular pattern around the center on the circumference, with a distribution number of 6 to 18. The overall porosity is still 40%.

[0075] (2) This step is the same as step (2) in Example 1;

[0076] (3) This step is the same as step (3) in Example 1;

[0077] (4) This step is the same as step (4) in Example 1;

[0078] (5) This step is the same as step (5) in Example 1;

[0079] Figure 4 This is a three-dimensional model of the gradient-order titanium / aluminum heteropolymer composite material from Example 4. Figure 5 The image shows a physical picture of the Ti6Al4V titanium alloy circular hole gradient ordered structure obtained by 3D printing in Example 4. It can be seen that the diameter of the circular holes gradually increases from the inside to the outside, and each layer of circular holes is distributed in a circle around the center.

[0080] The density of the Ti6Al4V titanium alloy reinforced 7075Al alloy material was tested to be 3.73 g / cm³. 3 With a Vickers hardness of 318HV, a tensile strength of 1247MPa, and an elongation after fracture of 5%, its specific strength is 334.3Nm / g, exhibiting superior mechanical properties.

[0081] Example 5

[0082] The raw materials required for preparing the Ti6Al4V titanium alloy reinforced 7075Al alloy composite material in this embodiment are: Ti6Al4V titanium alloy powder with a particle size distribution of 15-53 μm, pure copper, and 7075Al alloy powder with a particle size of 48 μm prepared by gas atomization. The preparation method of the Ti6Al4V titanium alloy reinforced 7075Al alloy material described in this embodiment specifically includes the following steps:

[0083] (1) The difference between this step and step (1) in Example 1 is that the Ti6Al4V titanium alloy lattice with gradient circular hole structure is designed using the 3D modeling software UG. The size of the lattice skeleton is Ф17.2×35mm. The diameter of the Ti6Al4V titanium alloy ordered structure circular holes obtained by 3D printing gradually decreases from the center to the outside, and is 1.8mm, 1.6mm, 1.4mm, 1.2mm, and 1.1mm respectively. The diameter changes from 1.8mm to 1.1mm. Four layers of circular arrays were formed. The diameters of each circular array (the circles formed by the centers of the holes in the circular array) were 4.2 mm, 8 mm, 11.4 mm, and 14.6 mm, respectively. The number of holes in each circular array was 6, 14, 24, and 33, respectively. The minimum spacing between adjacent holes in the radial direction was 0.4 mm, 0.4 mm, 0.4 mm, and 0.45 mm, respectively. The holes were distributed in a circular pattern around the center along the circumference, with the number of holes ranging from 6 to 44. The overall porosity remained at 40%.

[0084] (2) This step is the same as step (2) in Example 1;

[0085] (3) This step is the same as step (3) in Example 1;

[0086] (4) This step is the same as step (4) in Example 1;

[0087] (5) This step is the same as step (5) in Example 1;

[0088] Figure 6 The image shows a physical image of the Ti6Al4V titanium alloy circular hole gradient ordered structure obtained by 3D printing in Example 5. It can be seen that the diameter of the circular holes gradually decreases from the inside to the outside, and each layer of circular holes is distributed in a circular pattern around the center.

[0089] The density of the Ti6Al4V titanium alloy reinforced 7075Al alloy material was tested to be 3.73 g / cm³. 3 It has a Vickers hardness of 307HV, a tensile strength of 1134MPa, an elongation after fracture of 6.4%, and improved plasticity, exhibiting better overall mechanical properties.

[0090] Comparative Example 1

[0091] The molding process is performed before the extrusion process in Example 1, using a vacuum pressure impregnation process.

[0092] The preparation method of the Ti6Al4V ordered structure toughened 7075Al composite material described in this comparative example specifically includes the following steps:

[0093] (1) A Ti6Al4V titanium alloy lattice with circular holes was designed using the 3D modeling software UG. The lattice skeleton has dimensions of Ф11.8×35mm, where the diameter of the ordered circular holes is 1mm, the minimum spacing between the ordered through holes is 0.5mm, and each circular hole is surrounded by six other circular holes. Connecting the centers of these six holes forms a regular hexagon with a side length of 1.5mm. A 3D model of the lattice was then established. The Ti6Al4V titanium alloy with a porosity of 40% was obtained by printing using an EOSINT M280 metal 3D printer.

[0094] (2) The Ti6Al4V titanium alloy skeleton printed in step (1) is placed in a vacuum heat treatment furnace and kept at 800℃ for 4 hours, and then cooled with the furnace.

[0095] (3) The Ti-6Al-4V titanium alloy skeleton model obtained in step (2) is subjected to abrasive flow treatment. The abrasive used in the abrasive flow is silicon carbide, the abrasive flow pressure is 100Kg, and the abrasive flow time is 4h to remove residual powder attached to the surface of the lattice material.

[0096] (4) Place the Ti-6Al-4V titanium alloy lattice obtained in step (3) into a corundum crucible with a diameter of 30mm, and then place the 7075 aluminum alloy block to be impregnated on top of the Ti-6Al-4V lattice.

[0097] (5) A titanium alloy lattice reinforced aluminum matrix composite material was prepared using a vacuum pressure liquid metal infiltration furnace. The corundum crucible containing Ti-6Al-4V lattice and 7075 aluminum alloy block was raised into the furnace tube of the resistance furnace through the lifting mechanism of the equipment. The furnace tube was sealed and a vacuum was drawn. When the vacuum degree reached 100Pa, the temperature was raised from room temperature to 350℃ at a heating rate of 10℃ / min and held for 10min. The temperature was raised from 350℃ to 600℃ at a heating rate of 8℃ / min and held for 10min. The temperature was raised from 600℃ to 750℃ at a heating rate of 5℃ / min and held for 15min.

[0098] (6) After the heat preservation is completed, turn off the vacuum pump and pressurize with inert argon gas for 2 minutes at a pressure of 0.5 MPa for 5 minutes.

[0099] (7) After the heat preservation and pressure preservation are completed, the sample is cooled with the furnace. After cooling, the sample is taken out and excess aluminum material is removed.

[0100] (8) The material obtained in step (7) is placed in an electric resistance furnace and preheated to 450°C, and then placed in a high-temperature extrusion device for extrusion molding. The mold is preheated to 450°C, the extrusion pressure is about 700MPa, the extrusion speed is 2.7mm / s, the extrusion ratio is 8:1, the lubricant is graphite powder, after the high-temperature extrusion is completed, the bar is cut and shaped to obtain the extruded infiltrated 7075Al / Ti-6Al-4V composite material.

[0101] Figure 7 The images show transverse and longitudinal optical microscopic images of the titanium alloy-reinforced aluminum matrix composite material, which is a comparative example of titanium alloy infiltration with an ordered structure. As can be seen from the images, a large, obvious crack exists in the longitudinal section of the composite material, disrupting the continuity of its microstructure.

[0102] The tensile strength of the extruded impregnated 7075Al / Ti-6Al-4V composite material was only 518 MPa, with an elongation after fracture of 1.3%. The tensile strength of the 7075Al alloy prepared under the same conditions was about 487 MPa, with an elongation after fracture of 13.2%. Although the addition of vacuum pressure impregnation process slightly improved the strength of 7075Al material, it significantly reduced its plasticity.

[0103] Comparative Example 2

[0104] Using Al 84 The preparation method of the titanium alloy ordered structure toughened nanostructured aluminum alloy material described in this comparative example, which replaces the 7075Al alloy in Example 1 with Ni7Gd6Co3 (at.%) amorphous powder, specifically includes the following steps:

[0105] (1) A Ti6Al4V titanium alloy dot matrix with circular holes was designed using the 3D modeling software UG. The dimensions of the dot matrix skeleton are Ф11.8×35mm. The diameter of the ordered circular holes is 1mm, the minimum spacing between the ordered through holes is 0.5mm, and six circular holes surround any one circular hole. The centers of the six circular holes connected together can form a regular hexagon with a side length of 1.5mm. A 3D model of the dot matrix was established. The Ti6Al4V titanium alloy with a porosity of 40% was obtained by printing using an EOSINT M280 metal 3D printer.

[0106] (2) The Ti-6Al-4V titanium alloy skeleton printed in step (1) is placed in a vacuum heat treatment furnace and kept at 800℃ for 4 hours, and then cooled with the furnace.

[0107] (3) The Ti-6Al-4V titanium alloy skeleton model obtained in step (2) is subjected to abrasive flow treatment. The abrasive used in the abrasive flow is silicon carbide, the abrasive flow pressure is 100Kg, and the abrasive flow time is 4h to remove residual powder attached to the surface of the lattice material.

[0108] (4) Place the three-dimensional Ti-6Al-4V titanium alloy skeleton obtained in step (3) into a pure copper cladding, and then place the Al... 84 Ni7Gd6Co3 (at.%) amorphous alloy powder was injected into the ordered structure of titanium alloy within a casing, and the casing was then sealed. The casing was placed on an ultrasonic and mechanical vibration machine for compaction. Finally, the Ti-6Al-4V titanium alloy skeleton / aluminum alloy powder composite material was subjected to room temperature extrusion molding at a pressure of 700 MPa for a holding time of 3 min. The volume fraction of Ti-6Al-4V titanium alloy was 60%, and the volume fraction of amorphous alloy powder was 40%.

[0109] (5) The ordered structure of Ti-6Al-4V titanium alloy after room temperature extrusion in step (4)

[0110] / Al 84 The Ni7Gd6Co3 (at.%) amorphous alloy powder composite material is preheated to 500°C in an electric resistance furnace, and then placed in a hot extrusion device for high-temperature extrusion molding. The die in the high-temperature extrusion device is preheated to 450°C, the extrusion pressure is about 700MPa, the extrusion speed is 2.7mm / s, the extrusion ratio is 8:1 (or 6:1, 4:1), and the lubricant is graphite powder. After the high-temperature extrusion is completed, the bar stock is cut and shaped to obtain a titanium alloy ordered structure toughened nanostructured aluminum alloy material.

[0111] Figure 8 For Al 84 Lateral and longitudinal optical micrographs of Ni7Gd6Co3 / TC4 composite material at an 8:1 extrusion ratio. Figure 9 For pure Al 84 Ni7Gd6Co3 alloy and Al under different extrusion ratios 84 The engineering stress-strain curves of Ni7Gd6Co3 / TC4 composite material are shown, where ER=8 represents the mechanical property curves of the composite material with an extrusion ratio of 8:1.

[0112] Tests showed that the titanium alloy with ordered structure and toughened nanostructure aluminum alloy with an extrusion ratio of 8:1 had a tensile strength of 960 MPa, an elongation after fracture of 4%, a density of 4.174 g / cm³, an elastic modulus of 112.696 GPa, a specific strength of 230 Nm / g, and a specific elastic modulus of 27 GPa / g / cm³. 3 Al prepared under the same conditions 84 The tensile curve of Ni7Gd6Co3(at.%) amorphous alloy is also as follows: Figure 8 As shown, the addition of the Ti-6Al-4V titanium alloy lattice not only improves strength but also enhances plasticity. However, compared to the strengthening effect of the embodiments in this application, the improvement in strength and plasticity in this comparative example is inferior.

[0113] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A gradient-order titanium / aluminum heterogeneous composite material, characterized in that, The composite material is obtained by combining a gradient-ordered titanium alloy lattice structure with an aluminum alloy. Specifically, aluminum alloy powder is added to the gradient-ordered titanium alloy lattice structure and extruded at room temperature to obtain a bulk blank. The bulk blank obtained from room temperature extrusion is then subjected to high-temperature extrusion to obtain a gradient-ordered titanium / aluminum heterogeneous composite material. The gradient-ordered titanium alloy lattice structure has pores of different sizes, which are either gradient-distributed from small to large from the inside out, or gradient-distributed from large to small from the inside out. The aluminum alloy fills the pores of the gradient-ordered titanium alloy lattice structure. The volume fraction of the gradient-ordered titanium alloy lattice structure is 20-70%, and the volume fraction of the aluminum alloy is 30-80%. The holes in the gradient-ordered titanium alloy lattice structure are circular holes. The gradient-ordered titanium alloy lattice structure is a cylinder with numerous circular through holes on its cross-section, and all the circular holes are distributed in a circular or hexagonal pattern around the central hole. The diameter of the circular holes, the radial spacing between the holes, and the number of circumferential circular holes in the gradient-ordered titanium alloy lattice structure change continuously with the radius of the cylinder, thus forming a gradient distribution.

2. The gradient-order titanium / aluminum heterogeneous composite material according to claim 1, characterized in that, The titanium alloy is Ti6Al4V titanium alloy; the aluminum alloy is one or both of 7-series and 2-series aluminum alloys.

3. The gradient-order titanium / aluminum heteropolymer composite material according to claim 2, characterized in that, The 7-series aluminum alloy is 7075Al alloy or 7050Al alloy, and the 2-series aluminum alloy is 2024Al alloy or 2014Al alloy.

4. The gradient-order titanium / aluminum heterogeneous composite material according to claim 1, characterized in that, In gradient-order titanium / aluminum heterocomposites, the volume fraction of titanium alloy decreases from 80% to 20% from the outside to the inside, while the volume fraction of aluminum alloy increases from 20% to 80%, or the volume fraction of titanium alloy increases from 20% to 80% from the outside to the inside, while the volume fraction of aluminum alloy decreases from 80% to 20%.

5. The gradient-order titanium / aluminum heteropolymer composite material according to claim 1, characterized in that, The cylinder has a diameter of 10-18 mm and a height of 20-50 mm.

6. The gradient-order titanium / aluminum heterogeneous composite material according to claim 1, characterized in that, The theoretical density range of the gradient-order titanium / aluminum isomer composite material is 3.13~3.83 g / cm³. 3 .

7. The method for preparing the gradient-ordered titanium / aluminum heterogeneous composite material according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Preparation of gradient-ordered titanium alloy lattice structure Spherical titanium alloy powder is used to form a gradient-ordered titanium alloy lattice structure using selective laser melting technology, followed by annealing treatment. (2) Aluminum alloy powder filled with gradient-ordered titanium alloy lattice structure The gradient-ordered titanium alloy lattice structure obtained in step (1) is placed in a pure copper cladding. Aluminum alloy powder is added into the gradient-ordered titanium alloy lattice structure and extruded at room temperature to obtain a bulk blank. The bulk blank obtained by room temperature extrusion is then extruded at high temperature to obtain a gradient-ordered titanium / aluminum heterogeneous composite material.

8. The preparation method according to claim 7, characterized in that, In step (1), the diameter of the circular holes in the gradient-ordered titanium alloy lattice structure increases or decreases from the center outwards, ranging from 1 mm to 1.8 mm, forming 4 to 6 layers of circumferential array; the minimum spacing between adjacent holes in the radial direction is 0.2 to 0.6 mm; the number of circular holes in the circumferential direction is 6 to 44. The annealing temperature in step (1) is 750~1000℃, and the annealing time is 3~6h; The average particle size of the aluminum alloy powder in step (2) is 13~53μm; The pressure for room temperature extrusion molding in step (2) is 600~1000MPa, and the holding time is 3~6min; The high-temperature extrusion temperature in step (2) is 350~500℃, the extrusion pressure is 400-1000MPa, the extrusion speed is 2~6mm / s, and the extrusion ratio is 4~8:1; In step (2), the mold is preheated to 300~450℃ before high-temperature extrusion.

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