Titanium carbide and element powder modification method for 5-series aluminum alloy and aluminum alloy composite material

Abstract

The invention discloses a titanium carbide and element powder modification method for a 5-series aluminum alloy and an aluminum alloy composite material, and aims to solve the problems that in existing additive manufacturing, due to the fact that the 5-series aluminum alloy contains a high-content Mg element, the additive manufacturing difficulty is large, and the cost is low. And due to hot cracks and evaporation of strengthening elements, the aluminum alloy composite material obtained through additive manufacturing has crack defects, and the densification effect is poor. The modification method comprises the steps that 5-series aluminum alloy powder is obtained; titanium carbide particles and elementary substance powder are added into 5-series aluminum alloy powder to be mixed, and mixed powder is obtained; after the mixed powder is subjected to heat preservation treatment, small-particle-size composite powder is collected through screening; and the composite powder is subjected to additive forming, modification of the 5-series aluminum alloy is completed, and the aluminum alloy composite material is obtained. According to the technical scheme, the titanium carbide and element powder modification method of the 5-series aluminum alloy and the aluminum alloy composite material are provided.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and more specifically, to a titanium carbide and element powder modification method of a 5-series aluminum alloy and an aluminum alloy composite material. Background Art

[0002] Additive Manufacturing (AM), also known as 3D printing technology, is an emerging manufacturing technology that uses digital models as the basis to stack materials layer by layer to create physical objects. It embodies the close integration of information network technology with advanced material technology and digital manufacturing technology, and is an important part of the advanced manufacturing industry.

[0003] Selective laser melting (LPBF) is one of the most commonly used additive manufacturing technologies for manufacturing metal parts with good preparation effects. It uses a computer-aided design model. During the printing process, a high-energy laser beam melts the powder and solidifies it at an extremely fast cooling rate. It adopts a layer-by-layer melting and superposition molding method to produce customized parts with almost unlimited design freedom. The component model comes from computer design, so this preparation technology does not require a mold, shortens the production cycle, and reduces material waste.

[0004] As a typical lightweight alloy, aluminum alloy has the advantages of low density, high specific strength, high thermal conductivity and easy processing. Commercially prepared high-strength aluminum alloys have been widely used in aerospace, navigation, automotive and other fields. 5 series aluminum alloys have excellent corrosion resistance, no low-temperature brittleness and magnetism, and are widely used in hull structures, such as ship propellers, impellers, marine heat exchangers and other parts. In additive manufacturing, since 5 series aluminum alloys have a high content of Mg, additive manufacturing is difficult, and the aluminum alloy composites obtained by additive manufacturing have crack defects and poor densification effects due to thermal cracks and evaporation of strengthening elements. Summary of the invention

[0005] The purpose of the present invention is to provide a titanium carbide and element powder modification method of 5 series aluminum alloy and an aluminum alloy composite material, which is used to solve the technical problems in existing additive manufacturing that the 5 series aluminum alloy has a high content of Mg element, the additive manufacturing is difficult, and the aluminum alloy composite material obtained by additive manufacturing has crack defects and poor densification effect due to thermal cracks and evaporation of strengthening elements. In view of this, the present invention is implemented through the following scheme.

[0006] In a first aspect, the present invention provides a method for modifying titanium carbide and element powder of a 5-series aluminum alloy, comprising: Obtaining 5 series aluminum alloy powder, wherein the magnesium content of the 5 series aluminum alloy is 4-6wt%; Adding titanium carbide particles and element powder to the 5-series aluminum alloy powder and mixing them so that the titanium carbide particles are evenly dispersed on the surface of the 5-series aluminum alloy powder to obtain a mixed powder; After the mixed powder is heat-insulated, the composite powder with small particle size is collected by sieving; wherein the temperature of the heat-insulating treatment is 80-120° C., the time is 2-8 hours, and the sieve aperture during the sieving process is 150-200 mesh; The composite powder is additively molded to complete the modification of the 5 series aluminum alloy and obtain an aluminum alloy composite material.

[0007] Compared with the prior art, in the titanium carbide and element powder modification method of the 5-series aluminum alloy of the present invention, a 5-series aluminum alloy with a magnesium content of 4-6wt% is selected, and the titanium carbide particles are dispersed on the surface of the 5-series aluminum alloy powder, that is, the titanium carbide particles are attached to the surface of the 5-series aluminum alloy powder to obtain the mixed powder. Since the titanium carbide particles have good stability, during the additive molding (or additive manufacturing) process, the titanium carbide particles attached to the surface of the 5-series aluminum alloy powder can improve the thermal diffusion between the composite powders, and maintain the molten pool temperature during the additive molding (or additive manufacturing) process at a certain temperature value, which can avoid excessive evaporation of the Mg (magnesium) element in the 5-series aluminum alloy powder, while maintaining the original characteristics of the 5-series aluminum alloy, reducing the difficulty of additive manufacturing. Further, the titanium carbide particles have the advantages of high hardness, high elastic modulus and good thermal stability, and the strength of the prepared aluminum alloy composite material can be improved after the above-mentioned additive molding; further, the lattice structure of the titanium carbide particles has a low mismatch with aluminum, and can be used as a grain refiner to eliminate the thermal cracking tendency of the aluminum alloy composite material printing process, and prepare a dense, crack-free, fine-grained, and isotropic aluminum alloy composite material. In the above-mentioned modification method, the present invention adds elemental powder to the mixed powder, and the selective addition of different types of elemental powders will bring different performance improvements to the aluminum alloy composite material. The elemental powder can be selected according to the performance of the desired aluminum alloy composite material. The addition type or addition amount of the elemental powder has the advantages of simplicity and economy for the modification of the 5 series aluminum alloy. Through the above-mentioned technical solution of the present invention, the existing additive manufacturing is solved. Due to the high content of Mg in the 5 series aluminum alloy, the additive manufacturing is difficult, and the aluminum alloy composite material obtained by additive manufacturing has crack defects and poor densification effect due to thermal cracks and evaporation of strengthening elements.

[0008] Further, in the titanium carbide and element powder modification method of the 5 series aluminum alloy of the present invention, the 5 series aluminum alloy includes 5083 aluminum alloy, 5056 aluminum alloy, 5154 aluminum alloy, 5754 aluminum alloy and Al-Mg-Sc-Zr alloy; and / or, The particle size of the 5 series aluminum alloy powder is 10-60 μm.

[0009] Furthermore, in the titanium carbide and element powder modification method of the 5-series aluminum alloy of the present invention, the particle size of the titanium carbide particles is 50nm~5µm; and / or, The proportion of titanium carbide particles in the mixed powder is 2-8wt%.

[0010] Furthermore, in the titanium carbide and element powder modification method of the 5-series aluminum alloy of the present invention, the elemental substance includes one or more of magnesium, manganese, copper, titanium, zinc and zirconium.

[0011] Furthermore, in the titanium carbide and element powder modification method of the 5-series aluminum alloy of the present invention, the particle size of the element single substance powder is 1-100 μm; and / or, The proportion of elemental powder in the mixed powder is 0.5-8wt%.

[0012] Furthermore, in the titanium carbide and element powder modification method of the 5-series aluminum alloy of the present invention, the additive molding of the composite powder comprises: Performing selective laser melting on the composite powder to complete additive manufacturing; The power of the laser is 200-400W, the scanning speed is 400-1200mm / s, and the layer thickness is 30-60µm.

[0013] Furthermore, in the titanium carbide and element powder modification method of the 5-series aluminum alloy of the present invention, during the selective laser melting of the composite powder, the oxygen content is less than 0.05% and the forming chamber pressure is 8-12 mbar.

[0014] Furthermore, in the titanium carbide and element powder modification method of the 5 series aluminum alloy of the present invention, the titanium carbide particles and the element powder are added to the 5 series aluminum alloy powder for mixing, comprising: Adding titanium carbide particles and element powder to the 5 series aluminum alloy powder; The titanium carbide particles are uniformly dispersed on the surface of the 5 series aluminum alloy powder by vibrating and mixing the powder.

[0015] Furthermore, in the titanium carbide and element powder modification method of the 5 series aluminum alloy of the present invention, during the vibration powder mixing process, grinding balls with a particle size of 5 to 10 mm are used, the mass ratio of the mixture to the grinding balls is 1: (2 to 4), the vibration frequency is 40 to 60 Hz, and the vibration time is 1 to 4 hours.

[0016] In a second aspect, the present invention provides an aluminum alloy composite material prepared by the titanium carbide and element powder modification method of the above 5 series aluminum alloy.

[0017] Compared with the prior art, the beneficial effects of the aluminum alloy composite material of the present invention are the same as the beneficial effects of the titanium carbide and element powder modification method of the 5 series aluminum alloy described in the above technical solution, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 It is a schematic diagram of a titanium carbide and element powder modification method of a 5 series aluminum alloy of the present invention; Figure 2 This is a schematic diagram of the SEM morphology of the composite powder of Example 1 of the present invention; Figure 3 Schematic diagram of the distribution energy spectrum of aluminum element in the composite powder of Example 1 of the present invention; Figure 4 Schematic diagram of the distribution energy spectrum of magnesium element in the composite powder of Example 1 of the present invention; Figure 5 This is a schematic diagram of the energy spectrum distribution of titanium element in the composite powder of Example 1 of the present invention; Figure 6 This is a schematic diagram of the horizontal microstructure of the 5083 aluminum alloy composite material in Example 1 of the present invention; Figure 7 This is a schematic diagram of the microstructure of the 5083 aluminum alloy composite material in the construction direction in Example 1 of the present invention; Figure 8 Schematic diagram of the microstructure of the 5083 aluminum alloy composite material of Example 1; Fig. 9 Schematic diagram of the distribution spectrum of aluminum element in the 5083 aluminum alloy composite material of Example 1; Fig.10 Schematic diagram of the distribution energy spectrum of magnesium element in the 5083 aluminum alloy composite material of Example 1; Fig.11 Schematic diagram of the energy spectrum distribution of titanium element in the 5083 aluminum alloy composite material of Example 1; Fig.12 This is a schematic diagram of the direct IPF of the 5083 aluminum alloy composite material in Example 1 of the present invention; Fig.13 Schematic diagram of texture orientation and maximum texture index of the 5083 aluminum alloy composite material in Example 1 of the present invention; Fig.14 Schematic diagram of grain size distribution of the 5083 aluminum alloy composite material in Example 1 of the present invention; Fig.15This is a schematic diagram of the horizontal microstructure of the 5083 aluminum alloy composite material in Example 2 of the present invention; Fig.16 This is a schematic diagram of the microstructure of the 5083 aluminum alloy composite material in the construction direction in Example 2 of the present invention; Fig.17 This is a schematic diagram of the horizontal microstructure of the 5083 aluminum alloy composite material in Example 3 of the present invention; Fig.18 This is a schematic diagram of the microstructure of the 5083 aluminum alloy composite material in the construction direction in Example 3 of the present invention; Fig.19 It is a schematic diagram of the horizontal microstructure of the 5083 aluminum alloy composite material in the comparative example of the present invention; Fig. 20 A schematic diagram of the microstructure of the 5083 aluminum alloy composite material in the comparative example of the present invention in the construction direction; Fig.21 It is a schematic diagram of the mechanical properties of the 5083 aluminum alloy composite material containing different titanium carbides and elemental single substances in the present invention. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0022] Selective laser melting (LPBF) is one of the most commonly used additive manufacturing technologies for manufacturing metal parts with good preparation effects. It uses a computer-aided design model. During the printing process, a high-energy laser beam melts the powder and solidifies it at an extremely fast cooling rate. It adopts a layer-by-layer melting and superposition molding method to produce customized parts with almost unlimited design freedom. The component model comes from computer design, so this preparation technology does not require a mold, shortens the production cycle, and reduces material waste.

[0023] As a typical lightweight alloy, aluminum alloy has the advantages of low density, high specific strength, high thermal conductivity and easy processing. Commercially prepared high-strength aluminum alloys have been widely used in aerospace, navigation, automotive and other fields. 5 series aluminum alloys have excellent corrosion resistance, no low-temperature brittleness and magnetism, and are widely used in hull structures, such as ship propellers, impellers, marine heat exchangers and other parts. In additive manufacturing, since 5 series aluminum alloys have a high content of Mg, additive manufacturing is difficult, and the aluminum alloy composites obtained by additive manufacturing have crack defects and poor densification effects due to thermal cracks and evaporation of strengthening elements.

[0024] In order to solve the above technical problems, in a first aspect, the present invention provides a method for modifying titanium carbide and element powder of a 5 series aluminum alloy, comprising: Obtaining 5 series aluminum alloy powder, wherein the magnesium content of the 5 series aluminum alloy is 4-6wt%; Adding titanium carbide particles and element powder to the 5-series aluminum alloy powder and mixing them so that the titanium carbide particles are evenly dispersed on the surface of the 5-series aluminum alloy powder to obtain a mixed powder; After the mixed powder is heat-insulated, the composite powder with small particle size is collected by sieving; wherein the temperature of the heat-insulating treatment is 80-120° C., the time is 2-8 hours, and the sieve aperture during the sieving process is 150-200 mesh; The composite powder is additively molded to complete the modification of the 5 series aluminum alloy and obtain an aluminum alloy composite material.

[0025] In the case of adopting the above technical scheme, in the titanium carbide and element powder modification method of the 5-series aluminum alloy of the present invention, a 5-series aluminum alloy with a magnesium content of 4-6wt% is selected, and the titanium carbide particles are dispersed on the surface of the 5-series aluminum alloy powder, that is, the titanium carbide particles are attached to the surface of the 5-series aluminum alloy powder to obtain the mixed powder. Since the titanium carbide particles have good stability, during the additive molding (or additive manufacturing) process, the titanium carbide particles attached to the surface of the 5-series aluminum alloy powder can improve the thermal diffusion between the composite powders, and maintain the molten pool temperature during the additive molding (or additive manufacturing) process at a certain temperature value, which can avoid excessive evaporation of the Mg (magnesium) element in the 5-series aluminum alloy powder, while maintaining the original characteristics of the 5-series aluminum alloy, reducing the difficulty of additive manufacturing. Further, the titanium carbide particles have the advantages of high hardness, high elastic modulus and good thermal stability, and the strength of the prepared aluminum alloy composite material can be improved after the above-mentioned additive molding; further, the lattice structure of the titanium carbide particles has a low mismatch with aluminum, and can be used as a grain refiner to eliminate the thermal cracking tendency of the aluminum alloy composite material printing process, and prepare a dense, crack-free, fine-grained, and isotropic aluminum alloy composite material. In the above-mentioned modification method, the present invention adds elemental powder to the mixed powder, and the selective addition of different types of elemental powders will bring different performance improvements to the aluminum alloy composite material. The elemental powder can be selected according to the performance of the desired aluminum alloy composite material. The addition type or addition amount of the elemental powder has the advantages of simplicity and economy for the modification of the 5 series aluminum alloy. Through the above-mentioned technical solution of the present invention, the existing additive manufacturing is solved. Due to the high content of Mg in the 5 series aluminum alloy, the additive manufacturing is difficult, and the aluminum alloy composite material obtained by additive manufacturing has crack defects and poor densification effect due to thermal cracks and evaporation of strengthening elements.

[0026] For further information, see Figure 1 , Figure 1 The schematic diagram of the modification method of titanium carbide and element powder of 5 series aluminum alloy of the present invention is as follows. Figure 1 The method is to first mix 5083 aluminum alloy powder (particle size of 15~53μm), TiC particles (particle size of 50nm~5μm) and elemental powder Mg / Mn / Cu (particle size of 5~100μm), and then evenly disperse the composite powder by vibration mixing (frequency of 60Hz, time of 1~4h), and then obtain a high-strength matrix composite material (i.e., 5083 aluminum alloy composite material) by laser forming (i.e., additive manufacturing). It should be noted that in the technical solution of the present invention, the aluminum alloy is not limited to the 5 series aluminum alloy.

[0027] Furthermore, in the titanium carbide and element powder modification method of the 5-series aluminum alloy of the present invention, after the mixed powder is heat-insulated, the composite powder with small particle size is collected by screening. The heat-insulating treatment can remove the moisture that may exist in the mixed powder to obtain a dry composite powder, thereby improving the efficiency of subsequent additive manufacturing. For example, the temperature of the heat-insulating treatment can be 80°C, 100°C or 120°C, the time of the heat-insulating treatment can be 2 hours, 6 hours or 8 hours, and the mesh aperture during the screening process is 150 mesh, 180 mesh or 200 mesh.

[0028] It should be understood that in the titanium carbide and element powder modification method of the 5 series aluminum alloy of the present invention, in order to further reduce the difficulty of powder laying and additive molding (or additive manufacturing), it is also necessary to control the type of 5 series aluminum alloy in the above process and control the particle size of the 5 series aluminum alloy powder within a reasonable range; exemplarily, the 5 series aluminum alloy includes 5083 aluminum alloy, 5056 aluminum alloy, 5154 aluminum alloy, 5754 aluminum alloy and Al-Mg-Sc-Zr alloy; the particle size of the 5 series aluminum alloy powder is 10~60µm; as another example, the 5 series aluminum alloy can be 5083 aluminum alloy, 5056 aluminum alloy, 5154 aluminum alloy, 5754 aluminum alloy or Al-Mg-Sc-Zr alloy, and the particle size of the 5 series aluminum alloy powder can be 10µm, 30µm, 50µm or 60µm.

[0029] It should be noted that the composition and content of each component of the above-mentioned different 5 series aluminum alloys are different. For example, in the 5083 aluminum alloy, the silicon (Si) content is 0.40wt%, the copper (Cu) content is 0.10wt%, the magnesium (Mg) content is 4.0~4.9wt%, the zinc (Zn) content is 0.25wt%, the manganese (Mn) content is 0.40~1.0wt%, the titanium (Ti) content is 0.15wt%, the chromium (Cr) content is 0.05~0.25wt%, the iron (Fe) content is 0.00~0.40wt%, and the balance is aluminum (A1). In 5056 aluminum alloy, the silicon (Si) content is 0.30wt%, the iron (Fe) content is 0.40wt%, the copper (Cu) content is 0.10wt%, the manganese (Mn) content is 0.05~0.20wt%, the chromium (Cr) content is 0.05~0.200wt%, the magnesium (Mg) content is 4.5~5.6wt%, the zinc (Zn) content is 0.10wt%, and the balance is aluminum (A1). In 5154 aluminum alloy, the silicon (Si) content is ≤0.25wt%, the copper (Cu) content is ≤0.10wt%; the magnesium (Mg) content is 2.4~3.0wt%, the zinc (Zn) content is ≤0.25wt%, the manganese (Mn) content is 0.50~1.0wt%, the titanium (Ti) content is ≤0.20wt%, the chromium (Cr) content is 0.05~0.20wt%, and the iron (Fe) content is 0.00~0.40wt%. In the Al-Mg-Sc-Zr alloy, the magnesium (Mg) content is 4.2~5.1wt%, the scandium (Sc) content is 0.6~0.88wt%, the zirconium (Zr) content is 0.2~0.5wt%, the manganese (Mn) content is 0.3~0.8wt%, and the balance is aluminum (A1).

[0030] It should also be understood that in the titanium carbide and element powder modification method of the 5 series aluminum alloy of the present invention, in order to further reduce the difficulty of powder laying and additive molding (or additive manufacturing), and to make the prepared aluminum alloy composite material have higher strength characteristics, it is also necessary to control the particle size of the titanium carbide particles and the proportion of the titanium carbide particles in the mixed powder within a reasonable range; exemplarily, the particle size of the titanium carbide particles is 50nm~5µm; the proportion of the titanium carbide particles in the mixed powder is 2~8wt%; as another example, the particle size of the titanium carbide particles can be 50nm, 500nm, 1µm, 3µm or 5µm, and the proportion of the titanium carbide particles in the mixed powder can be 2wt%, 4wt%, 6wt% or 8wt%.

[0031] As described above, the present invention adds elemental powder to the mixed powder. Selectively adding different types of elemental powder will bring different performance improvements to the aluminum alloy composite material. The elemental powder can be selected according to the performance of the required aluminum alloy composite material. The elemental powder can be selected according to the type or amount of addition. For example, the elemental powder includes one or more of magnesium, manganese, copper, titanium, zinc and zirconium. In another example, the elemental powder can be one or more of magnesium, manganese, copper, titanium, zinc and zirconium. The particle size of the elemental powder can be 1~100µm; the proportion of the elemental powder in the mixed powder can be 0.5~8wt%; for example, the particle size of the elemental powder can be 1µm, 30µm, 60µm or 100µm, and the proportion of the elemental powder in the mixed powder can be 0.5wt%, 1wt%, 4wt% or 8wt%.

[0032] As a possible implementation, in the titanium carbide and element powder modification method of the 5-series aluminum alloy of the present invention, the additive molding of the composite powder comprises: Performing selective laser melting on the composite powder to complete additive manufacturing; The power of the laser is 200-400W, the scanning speed is 400-1200mm / s, and the layer thickness is 30-60µm.

[0033] In the case of the above technical solution, the computer-aided design model can be used for selective laser melting. During the molding (or printing) process, the composite powder is melted by a high-energy laser beam and solidified at an extremely fast cooling rate. The layer-by-layer melting and superposition molding method can produce customized parts (or aluminum alloy composite materials) with almost unlimited design freedom. The component model comes from computer design, so this preparation technology does not require a mold, shortens the production cycle, and reduces material waste. For example, during the selective laser melting of the composite powder, the laser power can be 200W, 300W or 400W, the scanning speed can be 400mm / s, 600mm / s, 800mm / s or 1200mm / s, and the layer thickness can be 30µm, 40µm, 50µm or 60µm. Furthermore, during the selective laser melting of the composite powder, the oxygen content is lower than 0.05%, and the pressure in the forming chamber is 8-12 mbar; illustratively, the oxygen content may be 0%, 0.02% or 0.03%, and the pressure in the forming chamber may be 8 mbar, 10 mbar or 12 mbar.

[0034] As a possible implementation, in the titanium carbide and element powder modification method of the 5 series aluminum alloy of the present invention, titanium carbide particles and element powder are added to the 5 series aluminum alloy powder for mixing, comprising: Adding titanium carbide particles and element powder to the 5 series aluminum alloy powder; The titanium carbide particles are uniformly dispersed on the surface of the 5 series aluminum alloy powder by vibrating and mixing the powder.

[0035] When the above technical solution is adopted, the vibration powder mixing can utilize the energy generated by mechanical vibration to evenly disperse the titanium carbide particles and elemental powder in the 5-series aluminum alloy powder, and evenly disperse (or adhere) the titanium carbide particles on the surface of the 5-series aluminum alloy powder, thereby avoiding the inability to perform additive molding due to the aggregation of particles or powder, or the uneven performance of the aluminum alloy composite material obtained by additive molding. For example, in the process of the vibration powder mixing, grinding balls with a particle size of 5 to 10 mm are used, the mass ratio of the mixture to the grinding balls is 1: (2 to 4), the vibration frequency is 40 to 60 Hz, and the vibration time is 1 to 4 hours.

[0036] As another example, the particle size of the grinding balls can be 5 mm, 8 mm or 10 mm, the mass ratio of the mixture to the grinding balls can be 1:2, 1:3 or 1:4, the vibration frequency can be 40 Hz, 50 Hz or 60 Hz, and the vibration time can be 1 hour, 3 hours or 4 hours.

[0037] In a second aspect, the present invention provides an aluminum alloy composite material prepared by the titanium carbide and element powder modification method of the above 5 series aluminum alloy.

[0038] In the case of adopting the above technical scheme, the aluminum alloy composite material of the present invention is prepared by the titanium carbide and element powder modification method of the 5 series aluminum alloy described in the above technical scheme. In the modification method, a 5 series aluminum alloy with a magnesium content of 4-6wt% is selected, and the mixed powder is obtained by dispersing titanium carbide particles on the surface of the 5 series aluminum alloy powder, that is, the titanium carbide particles are attached to the surface of the 5 series aluminum alloy powder. Since the titanium carbide particles have good stability, during the additive molding (or additive manufacturing) process, the titanium carbide particles attached to the surface of the 5 series aluminum alloy powder can improve the thermal diffusion between the composite powders, and maintain the molten pool temperature during the additive molding (or additive manufacturing) process at a certain temperature value, which can avoid excessive evaporation of the Mg (magnesium) element in the 5 series aluminum alloy powder, while maintaining the original characteristics of the 5 series aluminum alloy, improving the fluidity of the alloy powder, thereby reducing the difficulty of powder spreading or additive manufacturing. Furthermore, titanium carbide particles have the advantages of high hardness, high elastic modulus and good thermal stability, and can improve the strength of the prepared aluminum alloy composite material after the above-mentioned additive molding; further, the lattice structure of titanium carbide particles has a low mismatch with aluminum, and can be used as a grain refiner to eliminate the thermal cracking tendency of the aluminum alloy composite material printing process, and prepare a dense, crack-free, fine-grained and isotropic aluminum alloy composite material. In the above-mentioned modification method, the present invention adds elemental powder to the mixed powder, and the selective addition of different types of elemental powder will bring different performance improvements to the aluminum alloy composite material.

[0039] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with specific embodiments, but the content of the present invention is not limited to the following embodiments.

[0040] Unless otherwise specified, the raw materials used in the following examples are commercially available.

[0041] In the following embodiments, a 5 series aluminum alloy (5083 aluminum alloy) is taken as an example for detailed description. In the 5083 aluminum alloy used in the following embodiments and comparative examples, the silicon (Si) content is 0.40wt%, the copper (Cu) content is 0.10wt%, the magnesium (Mg) content is 4.9wt%, the zinc (Zn) content is 0.25wt%, the manganese (Mn) content is 0.40wt%, the titanium (Ti) content is 0.15wt%, the chromium (Cr) content is 0.05wt%, the iron (Fe) content is 0.40wt%, and the balance is aluminum (A1). Example 1

[0042] This embodiment provides a method for modifying titanium carbide and element powder of a 5 series aluminum alloy, comprising: S100, obtaining 5083 aluminum alloy powder with a particle size of 15-53µm; the magnesium content in the 5083 aluminum alloy is 4.9wt%; S200, adding 4wt% of titanium carbide (TiC) particles and 6wt% of metal magnesium powder to 90wt% of 5083 aluminum alloy powder, and mixing them by a vibrating powder mixer, so that the titanium carbide particles are evenly dispersed on the surface of the 5 series aluminum alloy powder to obtain a mixed powder; The particle size of titanium carbide (TiC) particles is 50 nm, and the particle size of magnesium powder is between 15 and 53 µm. The particle size of the grinding balls of the vibration mixer is 10 mm, the mass ratio of the mixture to the grinding balls is 1:2, the vibration frequency of the vibration mixer is 60 Hz, and the vibration time is 2 hours. S300, placing the mixed powder in step S200 in an oven for heat preservation treatment, and collecting the composite powder with small particle size by sieving; wherein the temperature of the oven during the heat preservation treatment is 120° C. and the heat preservation time is 4 hours; and the sieve aperture during the sieving process is 200 mesh; S400, performing selective laser melting forming on the composite powder in step S300 to complete the modification of the 5083 aluminum alloy and obtain a 5083 aluminum alloy composite material; Among them, the selective laser melting printing parameters are: laser power 300W, scanning speed 800mm / s, layer thickness 30µm; the oxygen content in the selective laser melting forming process is less than 0.05%, and the forming chamber pressure is maintained at 8~12mbar.

[0043] In this embodiment, after the composite powder is obtained in step S300, the morphology and element distribution thereof are observed. Figure 2 As shown in Figure 2, the 5083 aluminum alloy powder in the composite powder presents a certain irregular state, but the particle size distribution meets the requirements of selective laser melting. Figures 3 to 5 It can be seen that the titanium carbide (TiC) particles are mainly attached to the surface of the 5083 aluminum alloy powder and are relatively uniform. The metal magnesium powder still maintains good sphericity and is evenly dispersed in the 5083 aluminum alloy powder, which is beneficial to improving the fluidity of the composite powder and ensuring smooth powder spreading during the selective laser melting process.

[0044] The 5083 aluminum alloy composite material prepared in this embodiment was cut and separated, and vertical and horizontal surfaces were ground to observe its microstructure. Figure 6 and Figure 7 As shown in the figure, after modification with TiC particles and Mg (magnesium) element powder, there are no cracks on the horizontal and vertical surfaces of the 5083 aluminum alloy composite material, and the number and size of defects such as pores and unfused are effectively controlled. Figures 8 to 11In this 5083 aluminum alloy composite material, due to the influence of laser recoil pressure, Marangoni convection and gravity during the printing process, the nano-scale TiC particles are small in mass and form particle agglomerates of a certain size under force, but the overall distribution is uniform. The Mg single substance powder is completely melted and can still be fully diffused at an extremely fast cooling rate. The Mg element is evenly distributed in the printed sample without element segregation. Please refer to Figure 12 to Figure 14 , Fig.12 Schematic diagram of the IPF of the 5083 aluminum alloy composite material in this embodiment (polar figure); Fig.13 Schematic diagram of texture orientation and maximum texture index of the 5083 aluminum alloy composite material in this embodiment; Fig.14 Schematic diagram of grain size distribution of 5083 aluminum alloy composite material in Example 1. Fig.12 It can be seen that the grain structure of the 5083 aluminum alloy composite material of this embodiment is a completely equiaxed crystal region, and the grains are submicron grains without preferential orientation. Fig.13 It can be seen that the texture orientation of the 5083 aluminum alloy composite material in this embodiment is equiaxed crystal without texture orientation, and the maximum texture index is only 1.66, indicating that the orientation of the fine grains is disordered. Fig.14 It can be seen that most of the grain sizes in the aluminum alloy composite material of this embodiment are about 1.5 microns, the grain size difference is small, the average grain size is 1.74 microns, and the refinement effect is obvious. Example 2

[0045] This embodiment provides a method for modifying titanium carbide and element powder of a 5 series aluminum alloy, comprising: S100, obtaining 5083 aluminum alloy powder with a particle size of 15-53 μm, wherein the magnesium content of the 5083 aluminum alloy is 4.9 wt%; S200, adding 4wt% of titanium carbide (TiC) particles and 2wt% of metal manganese (Mn) powder to 94wt% of 5083 aluminum alloy powder, and mixing them by a vibrating powder mixer, so that the titanium carbide particles are evenly dispersed on the surface of the 5 series aluminum alloy powder to obtain a mixed powder; The particle size of titanium carbide (TiC) particles is 50 nm, and the particle size of metal manganese (Mn) powder is 20 µm; the particle size of the grinding balls of the vibration mixer is 5 mm, the mass ratio of the mixture to the grinding balls is 1:4, the vibration frequency of the vibration mixer is 60 Hz, and the vibration time is 4 hours; S300, placing the mixed powder in step S200 in an oven for heat preservation treatment, and collecting the composite powder with small particle size by sieving; wherein the temperature of the oven during the heat preservation treatment is 120° C. and the heat preservation time is 4 hours; and the sieve aperture during the sieving process is 200 mesh; S400, performing selective laser melting forming on the composite powder in step S300 to complete the modification of the 5083 aluminum alloy and obtain a 5083 aluminum alloy composite material; Among them, the selective laser melting printing parameters are: laser power 300W, scanning speed 800mm / s, layer thickness 30µm; the oxygen content in the selective laser melting forming process is less than 0.05%, and the forming chamber pressure is maintained at 8~12mbar.

[0046] In this embodiment, after the above 5083 aluminum alloy composite material is prepared, its microstructure is observed. Please refer to 15 and Fig.16 , there are no cracks on different construction surfaces of the 5083 aluminum alloy composite material of this embodiment, and the densification effect is good. Combining Example 1 and Example 2, it can be shown that TiC particles of different sizes can effectively inhibit the generation of hot cracks in the crack-prone aluminum alloy, and adding element single substance powders of different types, sizes and mass proportions will not affect the forming effect of the aluminum alloy composite material. Example 3

[0047] This embodiment provides a method for modifying titanium carbide and element powder of a 5 series aluminum alloy, comprising: S100, obtaining 5083 aluminum alloy powder with a particle size of 15-53 μm, wherein the magnesium content of the 5083 aluminum alloy is 4.9 wt%; S200, adding 4wt% of titanium carbide (TiC) particles and 4wt% of metal magnesium (Mg) powder to 92wt% of 5083 aluminum alloy powder, and mixing them by a vibrating powder mixer, so that the titanium carbide particles are evenly dispersed on the surface of the 5 series aluminum alloy powder to obtain a mixed powder; The particle size of titanium carbide (TiC) particles is 5µm, and the particle size of metal magnesium (Mg) powder is 100µm; the particle size of the grinding balls of the vibration mixer is 5mm, the mass ratio of the mixture to the grinding balls is 1:3, the vibration frequency of the vibration mixer is 60Hz, and the vibration time is 4 hours; S300, placing the mixed powder in step S200 in an oven for heat preservation treatment, and collecting the composite powder with small particle size by sieving; wherein the temperature of the oven during the heat preservation treatment is 80° C. and the heat preservation time is 8 hours; and the sieve aperture during the sieving process is 150 mesh; S400, performing selective laser melting forming on the composite powder in step S300 to complete the modification of the 5083 aluminum alloy and obtain a 5083 aluminum alloy composite material; Among them, the selective laser melting printing parameters are: laser power 200W, scanning speed 1200mm / s, layer thickness 60µm; the oxygen content in the selective laser melting forming process is less than 0.05%, and the forming chamber pressure is maintained at 8~12mbar.

[0048] In this embodiment, after the above 5083 aluminum alloy composite material is prepared, its microstructure is observed. Fig.17 and Fig.18 , which is basically the same as the above-mentioned Embodiment 1 and Embodiment 2, there are no cracks on different construction surfaces of the 5083 aluminum alloy composite material in this embodiment, and the densification effect is good. Example 4

[0049] This embodiment provides a method for modifying titanium carbide and element powder of a 5 series aluminum alloy, comprising: S100, obtaining 5083 aluminum alloy powder with a particle size of 15-53 μm, wherein the magnesium content of the 5083 aluminum alloy is 4.9 wt%; S200, adding 8wt% of titanium carbide (TiC) particles and 8wt% of metal manganese (Mn) powder to 84wt% of 5083 aluminum alloy powder, and mixing them by a vibrating powder mixer, so that the titanium carbide particles are evenly dispersed on the surface of the 5 series aluminum alloy powder to obtain a mixed powder; The particle size of titanium carbide (TiC) particles is 3-5µm, and the particle size of metal manganese (Mn) powder is 15-53µm; the particle size of the grinding balls of the vibration mixer is 5mm, the mass ratio of the mixture to the grinding balls is 1:3, the vibration frequency of the vibration mixer is 60Hz, and the vibration time is 4 hours; S300, placing the mixed powder in step S200 in an oven for heat preservation treatment, and collecting the composite powder with small particle size by sieving; wherein the temperature of the oven during the heat preservation treatment is 80° C. and the heat preservation time is 8 hours; and the sieve aperture during the sieving process is 150 mesh; S400, performing selective laser melting forming on the composite powder in step S300 to complete the modification of the 5083 aluminum alloy and obtain a 5083 aluminum alloy composite material; Among them, the selective laser melting printing parameters are: laser power 200W, scanning speed 1200mm / s, layer thickness 60µm; the oxygen content in the selective laser melting forming process is less than 0.05%, and the forming chamber pressure is maintained at 8~12mbar.

[0050] After the 5083 aluminum alloy composite material is prepared in this embodiment, its microstructure is observed. There are no cracks on different construction surfaces of the 5083 aluminum alloy composite material in this embodiment, and the densification effect is good, which is basically the same as the above-mentioned embodiments 1 to 3.

[0051] Comparative Example This comparative example provides a modification method for a 5-series aluminum alloy. Compared with Example 2, titanium carbide (TiC) particles and element powder (metal manganese powder in Example 2) are not added. The modification method includes: S100, placing 5083 aluminum alloy powder with a particle size of 15-53µm in an oven for heat preservation treatment, and then collecting aluminum alloy powder with small particle size by sieving; wherein, the temperature of the oven during the heat preservation treatment is 120°C and the heat preservation time is 4 hours; and the sieve aperture during the sieving process is 200 mesh; S200, performing selective laser melting molding on the aluminum alloy powder after the heat preservation treatment and screening collection in step S100 to obtain a 5083 aluminum alloy composite material; Among them, the selective laser melting printing parameters are: laser power 300W, scanning speed 800mm / s, layer thickness 30µm; the oxygen content in the selective laser melting forming process is less than 0.05%, and the forming chamber pressure is maintained at 8~12mbar.

[0052] It should be noted that 5083 aluminum alloy is an easy-to-crack aluminum alloy. In the selective laser melting forming (or selective laser melting printing) process of this comparative example, there are serious powder splashing and solute segregation phenomena, which leads to a large number of pores and unfused defects in the obtained 5083 aluminum alloy composite material. For specific microstructure, please refer to Fig.19 and Fig. 20 In addition, the fewer crystal nuclei in the 5083 aluminum alloy composite material grow along the temperature gradient direction inside the molten pool and eventually form coarse columnar crystals. Since there is no possible filling phase between the crystals, a large number of thermal cracks that are consistent with the growth direction of the columnar crystals often form between the columnar crystals.

[0053] See also Fig.21 , Fig.21 It shows that the 5083 aluminum alloy composites obtained by adding TiC particles of different sizes and mass ratios, as well as elemental powders of different types, particle sizes and mass ratios to 5083 aluminum alloy powder exhibit different mechanical properties. Fig.21 There are multiple curves in the figure, among which the curve corresponding to "5083 powder printing state" is the mechanical property curve of the 5083 aluminum alloy composite material obtained in the above comparative example, indicating that TiC and element single substance are not added to the 5083 aluminum alloy composite material; "4TiC 50nm +6Mg 15-53μm The curve corresponding to the "printed state of 5083 composite powder" is the mechanical property curve of the 5083 aluminum alloy composite material obtained in the above Example 1, indicating that 4wt% TiC particles and 6wt% metal Mg powder are added to the 5083 aluminum alloy powder; "4TiC 50nm +2Mn 20μm The curve corresponding to the "printed state of 5083 composite powder" is the mechanical property curve of the 5083 aluminum alloy composite material obtained in the above Example 2, indicating that 4wt% TiC particles and 2wt% metal Mn powder are added to the 5083 aluminum alloy powder. The meanings of the remaining curves are the same as the above three curves. Fig.21 It can be concluded that the 5083 aluminum alloy composite material corresponding to the above-mentioned comparative example, that is, the "5083 composite powder printed state", has a large number of defects such as cracks and pores, and has no mechanical properties at all. On the contrary, it can be seen from the curves corresponding to Example 1 and Example 2, as well as other curves, that after adding TiC and / or elemental single substances to the 5083 aluminum alloy powder, the 5083 aluminum alloy composite material obtained by additive molding exhibits different mechanical properties. It is explained that on the basis of taking TiC particles of different sizes as the core to ensure the printability (or additive molding) of the 5 series aluminum alloy, further simple addition of elemental single substance powder can effectively regulate the mechanical properties of the material. In practice, the technical solution of the present invention can prepare high-strength aluminum alloy composite materials that meet different application environment conditions.

[0054] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0055] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for modifying titanium carbide and element powder of 5 series aluminum alloy, characterized in that: include: Obtaining 5 series aluminum alloy powder, wherein the magnesium content of the 5 series aluminum alloy is 4-6wt%; Adding titanium carbide particles and element powder to the 5-series aluminum alloy powder and mixing them so that the titanium carbide particles are evenly dispersed on the surface of the 5-series aluminum alloy powder to obtain a mixed powder; After the mixed powder is heat-insulated, the composite powder with small particle size is collected by sieving; wherein the temperature of the heat-insulating treatment is 80-120° C., the time is 2-8 hours, and the sieve aperture during the sieving process is 150-200 mesh; The composite powder is additively molded to complete the modification of the 5 series aluminum alloy and obtain an aluminum alloy composite material.

2. The titanium carbide and element powder modification method of 5 series aluminum alloy according to claim 1, characterized in that: The 5 series aluminum alloys include 5083 aluminum alloy, 5056 aluminum alloy, 5154 aluminum alloy, 5754 aluminum alloy and Al-Mg-Sc-Zr alloy; and / or, The particle size of the 5 series aluminum alloy powder is 10-60 μm.

3. The titanium carbide and element powder modification method of 5 series aluminum alloy according to claim 2, characterized in that: The particle size of the titanium carbide particles is 50nm~5µm; and / or, The proportion of titanium carbide particles in the mixed powder is 2-8wt%.

4. The titanium carbide and element powder modification method of 5 series aluminum alloy according to claim 3, characterized in that: The elemental substance includes one or more of magnesium, manganese, copper, titanium, zinc and zirconium.

5. The titanium carbide and element powder modification method of 5 series aluminum alloy according to claim 4, characterized in that: The particle size of the element powder is 1-100 μm; and / or, The proportion of elemental powder in the mixed powder is 0.5-8wt%.

6. The titanium carbide and element powder modification method of 5 series aluminum alloy according to claim 5, characterized in that: The method of additively molding the composite powder comprises: Performing selective laser melting on the composite powder to complete additive manufacturing; The power of the laser is 200-400W, the scanning speed is 400-1200mm / s, and the layer thickness is 30-60µm.

7. The titanium carbide and element powder modification method of 5 series aluminum alloy according to claim 6, characterized in that: During the selective laser melting of the composite powder, the oxygen content is lower than 0.05% and the pressure in the forming chamber is 8-12 mbar.

8. The titanium carbide and element powder modification method of 5 series aluminum alloy according to claim 7, characterized in that: The step of adding titanium carbide particles and element powder to the 5 series aluminum alloy powder for mixing comprises: Adding titanium carbide particles and element powder to the 5 series aluminum alloy powder; The titanium carbide particles are uniformly dispersed on the surface of the 5 series aluminum alloy powder by vibrating and mixing the powder.

9. The titanium carbide and element powder modification method of 5 series aluminum alloy according to claim 8, characterized in that: During the vibration powder mixing process, grinding balls with a particle size of 5-10 mm are used, the mass ratio of the mixed material to the grinding balls is 1:(2-4), the vibration frequency is 40-60 Hz, and the vibration time is 1-4 hours.

10. An aluminum alloy composite material, characterized in that: The invention is prepared by the titanium carbide and element powder modification method of the 5 series aluminum alloy according to any one of claims 1 to 9.

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