Micro-nano composite aluminum alloy powder for solid additive manufacturing and preparation method of micro-nano composite aluminum alloy powder

Abstract

The invention belongs to the technical field of additive manufacturing of high-strength aluminum alloy, and discloses micro-nano composite aluminum alloy powder for solid-state additive manufacturing and a preparation method thereof.The preparation method comprises the steps that pretreated nano ceramic powder and micron metal composite powder are mixed according to a certain proportion and put into a ball-milling tank to be subjected to ball milling through a planetary ball mill, and the mixed powder is obtained; the nano ceramic powder is uniformly coated on the surface of the micron spherical metal powder, so that the property of the metal powder is improved, and the powder can be used for solid metal additive manufacturing and remanufacturing.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing of high-strength aluminum alloys, and specifically relates to a micro-nano composite aluminum alloy powder for solid-state additive manufacturing and a preparation method thereof. Background Art

[0002] Aluminum-based materials are widely used in aerospace, transportation, military weapons, sports equipment and other fields due to their light weight, high strength, high modulus, excellent wear resistance, reproducibility and low cost. Especially in the aviation field, they are often used in aircraft structures and engine parts. Applying additive manufacturing technology to aluminum alloys can further improve the application scenarios of aluminum alloys and achieve lightweighting in defense, military industry, aerospace, industrial production and other fields. Especially in the aerospace field, the demand is more urgent. Compared with traditional aluminum alloys, ceramic-reinforced aluminum alloy materials manufactured by solid-state additive manufacturing have high forming efficiency, higher strength, wear resistance and fatigue performance.

[0003] When pure metal powder is used for solid-state additive manufacturing, the laser heating and softening effect on the powder is poor due to the high reflectivity of the metal powder surface to the laser. The powder fails to obtain better plastic deformation ability before deposition. As a result, metal powder particles are prone to rebound and poor bonding between particles during the deposition process, resulting in larger holes, which reduces the deposition efficiency of the powder material. The prepared additive manufacturing parts have a high porosity, which seriously affects the performance of the high-strength material and reduces the utilization efficiency of the powder. Summary of the invention

[0004] In view of the shortcomings of pure metal powder in the solid-state additive manufacturing process, the present invention aims to provide a micro-nano composite aluminum alloy powder for solid-state additive manufacturing and a preparation method thereof. By coating the surface of the aluminum alloy powder with nano-scale ceramic powder particles, the surface roughness of the metal powder is increased, thereby improving its thermal softening effect during laser heating and enhancing the plastic deformation ability of the powder. This innovative technology helps to improve deposition efficiency, increase the density of the solid-state additive manufacturing deposition layer, and significantly enhance the mechanical properties of the final product.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A micro-nano composite aluminum alloy powder for solid-state additive manufacturing comprises a micro-nano composite powder, wherein the micro-nano composite powder comprises a micron-shaped spherical aluminum alloy powder and a nano-ceramic powder coated on the surface of the micron-shaped spherical aluminum alloy powder.

[0006] Preferably, the micron spherical aluminum alloy powder is Al-Zn-Mg-Cu series alloy powder.

[0007] Preferably, the nano ceramic powder is Y 2 O 3Powder, TiB 2 Powder and Al 2 O 3 At least one of powders.

[0008] Preferably, Y 2 O 3 The powder is in the form of fine flakes, Al 2 O 3 The powder is irregular block, TiB 2 The powder is irregular lumps.

[0009] Preferably, the particle size of the micron spherical aluminum alloy powder is not greater than 45 μm, the particle size of the nano ceramic powder is not greater than 200 nm, and the thickness of the nano ceramic powder coated on the surface of the micron spherical aluminum alloy powder is 100-300 nm.

[0010] The present invention also provides a method for preparing the micro-nano composite aluminum alloy powder for solid-state additive manufacturing as described above, comprising the following steps: The micron spherical aluminum alloy powder and the nano ceramic powder are mixed and ball-milled to coat the nano ceramic powder on the surface of the micron spherical aluminum alloy powder, thereby obtaining the micro-nano composite aluminum alloy powder for solid-state additive manufacturing.

[0011] Preferably, in terms of mass percentage, the amount of micron spherical aluminum alloy powder is 90% to 99.4% of the total mass of the micron spherical aluminum alloy powder and the nano ceramic powder, and the amount of the nano ceramic powder is 90% to 99.4% of the total mass of the micron spherical aluminum alloy powder and the nano ceramic powder.

[0012] Preferably, the particle size of the micron spherical aluminum alloy powder is not greater than 45 μm, the particle size of the nano ceramic powder is not greater than 200 nm, and the thickness of the nano ceramic powder coated on the surface of the micron spherical aluminum alloy powder is 100-300 nm; The micron spherical aluminum alloy powder is Al-Zn-Mg-Cu alloy powder; the nano ceramic powder is Y 2 O 3 Powder, TiB 2 Powder and Al 2 O 3 At least one of the powders; wherein Y 2 O 3 The powder is in the form of fine flakes, Al 2 O 3 The powder is irregular block, TiB 2 The powder is irregular lumps.

[0013] Preferably, the above preparation method of the present invention further comprises the following process: The micron spherical aluminum alloy powder and the nano ceramic powder are both pretreated as follows: drying at 60 to 100° C. for 4 to 8 hours to make the powder dry; The pre-treated dried micron spherical aluminum alloy powder and nano ceramic powder are ball milled.

[0014] Preferably, the micron spherical aluminum alloy powder and the nano ceramic powder are mixed and ball milled using a planetary ball mill, and the ball milling parameters are as follows: Ball mill speed: 350~450rpm; Ball to material ratio: (2~3):1; Ball milling time: 4-12h; Grinding ball diameter: 4mm, 8mm, 10mm, among which the number ratio of 4mm, 8mm, 10mm grinding balls is 6:4:1; Grinding ball material: 316 stainless steel grinding ball or Al 2 O 3 Grinding balls; Tank material: 316 stainless steel or Al 2 O 3 ceramics.

[0015] The present invention has the following beneficial effects: In the micro-nano composite aluminum alloy powder for solid-state additive manufacturing of the present invention, nano-ceramic powder is coated on the surface of micron-shaped spherical aluminum alloy powder. Since the particle size of the nano-ceramic powder is relatively small, the roughness of the surface of the micron-shaped spherical aluminum alloy powder is improved, and the reflectivity to the laser is greatly reduced, so that the micro-nano composite aluminum alloy powder for solid-state additive manufacturing of the present invention can obtain better thermal softening during the laser heating process, thereby improving the plastic deformation ability. When the micro-nano composite aluminum alloy powder is used for solid-state additive manufacturing and remanufacturing, the wear resistance and corrosion resistance of the material can be effectively improved, the density of the additive parts / coating can be improved, and the deposition efficiency of the material can be improved, so that the material has higher density and better mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a process flow chart of preparing micro-nano composite aluminum alloy powder suitable for solid metal additive manufacturing in an embodiment of the present invention; FIG. 2 (a) shows the nano Y used in the embodiment of the present invention. 2 O 3 The microscopic morphology of the particles, FIG2 (b) is the TiB used in the embodiment of the present invention. 2 Microscopic morphology of powder, FIG2 (c) is a microscopic morphology of micron 7075Al alloy powder used in an embodiment of the present invention; FIG3 (a) is a particle size distribution diagram of the micron 7075Al alloy powder used in the embodiment of the present invention; FIG3 (b) is a micro-nano composite 7075Al / Y prepared in Example 1 of the present invention. 2 O 3 Figure 3 (c) shows the particle size distribution of the powder. The micro-nano composite 7075Al / TiB prepared in Example 2 of the present invention is shown in Figure 3 (c). 2 Powder particle size distribution diagram; Figure 3 (d) is the micro-nano composite 7075Al / TiB prepared in Example 3 of the present invention 2 Powder particle size distribution diagram; Figure 4 (a) shows the micro-nano composite 7075Al / Y prepared in Example 1 of the present invention 2 O 3 Microscopic morphology of alloy powder; Figure 4 (b) is the micro-nano composite 7075Al / TiB prepared in Example 2 of the present invention 2 Microscopic morphology of alloy powder; Figure 4 (c) is the micro-nano composite 7075Al / TiB prepared in Example 3 of the present invention 2 Microscopic morphology of alloy powder; Figure 5 (a) shows the micro-nano composite 7075Al / Y prepared in Example 1 of the present invention 2 O 3 Element distribution diagram of alloy powder, FIG5 (b) is a micro-nano composite 7075Al / TiB prepared in Example 2 of the present invention 2 Element distribution diagram of alloy powder; Figure 5 (c) is the micro-nano composite 7075Al / TiB prepared in Example 3 of the present invention 2 Elemental distribution profile of alloy powder; Figure 6 (a) shows the cross-sectional microstructure of the sample prepared using pure metal powder (control group) in the present invention, and Figure 6 (b) shows the micro-nano composite 7075Al / Y in Example 1 of the present invention. 2 O 3 The cross-sectional microstructure of the sample prepared from the alloy powder is shown in Figure 6 (c) as the micro-nano composite 7075Al / TiB in Example 2 of the present invention. 2 The cross-sectional microstructure of the sample prepared from the alloy powder; Figure 6 (d) is the micro-nano composite 7075Al / TiB in Example 3 of the present invention. 2 Cross-sectional microstructure of the specimens prepared from alloy powders; Figure 7 Schematic diagram of the single particle size of the micro-nano composite powder of the present invention. DETAILED DESCRIPTION

[0017] The present invention is described below in conjunction with the accompanying drawings and embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0018] The present invention provides a technical solution for preparing micro-nano composite aluminum alloy powder suitable for solid-state metal additive manufacturing by using mechanical ball milling as the main means and nano ceramic particles and spherical aluminum alloy powder as raw materials.

[0019] Specifically, the preparation method of the micro-nano composite aluminum alloy powder of the present invention is as follows Figure 1 The powder preparation process described includes the following steps: Step 1: Take the mixed nano-ceramic powder and micron aluminum alloy spherical powder (also called micron spherical aluminum alloy powder) to be coated, grind and disperse the micron spherical aluminum alloy powder agglomerates, and put the nano-ceramic powder into an ethanol solution for ultrasonic vibration dispersion; then dry the treated nano-ceramic powder and micron aluminum alloy spherical powder respectively, and the drying process is as follows: dry for 4 to 8 hours at 80 to 120 ° C to ensure that the powder is in a dry state (the specific temperature and time are determined by the powder properties and ambient humidity). The powder properties of the dried micron-grade metal powder and nano-grade ceramic powder are tested, including: the particle size distribution, bulk density, and tap density of the powder. The measured powder data will be used to determine the mass distribution of the prepared micro-nano composite powder material. The amount of nano-ceramic powder added is determined according to the different coating layer thicknesses. In terms of mass percentage, the materials for preparing the micro-nano composite powder include: 90 wt% to 99.4 wt% of micron-grade spherical aluminum alloy powder and 0.6 wt% to 10 wt% of nano-grade ceramic powder.

[0020] Step 2: In order to calculate the material ratio of nano-ceramic powder and micron aluminum alloy spherical powder, the present invention establishes a theoretical model for determining the mass ratio of ball-milled micron aluminum alloy spherical powder and nano-ceramic particles, referring to Figure 7 The core is micron aluminum alloy spherical powder, and the outer layer is nano ceramic powder. The thickness of the nano ceramic powder coating is used to determine the mass ratio of nano particles. The specific calculation formula is as follows: The single particle powder coating mass ratio is as follows:

[0021] The added mass percentage of single-particle nanopowder is as follows:

[0022] Nano powder added mass percentage:

[0023] Where: R 1 : radius of micron aluminum alloy spherical powder; R2 : The radius of a single particle of micro-nano composite aluminum alloy powder; ΔR : Preset coating thickness of single particle of micro-nano composite aluminum alloy powder; V 1 : Volume of a single particle of micron aluminum alloy spherical powder, ; V 2 : The volume of micro-nano composite aluminum alloy powder, ; ΔV : Volume of nanopowder coating ; ρ 1 : Density of micron-sized metal powder, (micron-sized aluminum alloy powder); ρ 2 : Density of nano-scale ceramic powder, (nano Y 2 O 3 , TiB 2 、Al 2 O 3 powder); m 1 : The mass of a single metal powder particle ; m 2 :The quality of nano powder coating ; M s : Mass percentage of single nanoparticle powder added; M a : nano powder added mass percentage; r n : The proportion of micron aluminum alloy powder particle size distribution.

[0024] According to the particle size distribution of pure metal powder and the above calculation formula, the content percentage of powders with different particle sizes in micron-sized metal powder is used to calculate the corresponding particle size of powder. m 1 : m 2 By performing weighted calculation, the total mass ratio of micron-sized metal powder and nano-ceramic particles for preparing micro-nano composite powder under a preset coating layer thickness of the corresponding powder can be obtained.

[0025] Step 3: Place the powder in a planetary ball mill for coating and mixing according to the material types and mass ratios obtained in step 1 and step 2, so that the micron ceramic powder is evenly coated on the surface of the micron aluminum alloy powder to obtain a micro-nano composite aluminum alloy powder, wherein the process parameters of the ball milling are as follows: Ball mill speed: 350~450rpm; Ball to material ratio: (2~3):1; Ball milling time: 4-12h; Grinding ball diameter: 4mm, 8mm, 10mm, among which the number ratio of 4mm, 8mm, 10mm grinding balls is 6:4:1; Grinding ball material: 316 stainless steel grinding ball or Al 2 O 3 Grinding balls; Tank material: 316 stainless steel or Al 2 O 3 ceramics.

[0026] After coating and mixing according to the above parameters, the powder samples were characterized by scanning electron microscopy to evaluate the morphological characteristics and coating integrity. 2 O 3 The microstructure of the composite powder prepared by nanopowder shows nanoscale Y 2 O 3 The particles are uniformly attached to the surface of the 7075 alloy matrix to form a continuous coating layer. EDS element surface distribution analysis (Figure 5 (a)) confirms that the Y element is uniformly dispersed on the matrix surface, which verifies the process for preparing 7075 / Y 2 O 3 The effectiveness of the composite powder. In contrast, TiB 2 The nanopowder composite system exhibits different characteristics: Figure 4 (b) and Figure 4 (c) show that TiB 2 Although nanoparticles can improve the surface roughness of alloy powders, they form a discontinuous coating structure on the surface of the matrix due to their physical properties and particle size distribution. This phenomenon is confirmed by the EDS element distribution spectrum (see Figure 5 (b) and Figure 5 (c)), and the characteristic signal of the Ti element shows a local enrichment feature.

[0027] Step 4: Test the powder properties of the micro-nano composite aluminum alloy powder obtained after ball milling, including: particle size distribution, loose density, tap density and laser absorptivity of the powder.

[0028] In the above scheme of the present invention, the particle size of the micron spherical aluminum alloy powder is less than 45μm (325 mesh), and the particle size of the nano ceramic powder is less than 200nm. The micron spherical aluminum alloy powder can be 7075Al alloy powder, and the nano ceramic powder can be Y 2 O 3Powder, TiB 2 Powder and Al 2 O 3 At least one of the powders, wherein Y 2 O 3 Powder, Al 2 O 3 The powder is irregular block, TiB 2 The powder is in the form of fine flakes.

[0029] In the following embodiments of the present invention, the micron-sized spherical aluminum alloy powder is a micron-sized Al-Zn-Mg-Cu alloy powder having a particle size range of 0-45 μm. The particle size distribution test results of the micron-sized Al-Zn-Mg-Cu alloy powder used in the embodiments are shown in FIG3 (a). The chemical composition (wt%) of the Al-Zn-Mg-Cu alloy powder is shown in Table 1. 2 O 3 The particle size of the ceramic powder ranges from 0 to 100 nm, and the microstructure is irregular and thin as shown in Figure 2 (a); nano-TiB 2 The particle size of the ceramic powder ranges from 0 to 200 nm, and the microstructure morphology is fine blocks as shown in Figure 2 (b).

[0030] Table 1

[0031] Example 1 Specifically, refer to Figure 1 In this embodiment, solid-state additive manufacturing uses 7075Al / Y 2 O 3 The preparation method of the micro-nano composite powder comprises the following steps: Step 1: Powder pretreatment: 7075 aluminum alloy powder is pretreated by mechanical grinding and dispersion. Figure 2 (c) shows that the powder after treatment presents a typical near-spherical structure with significant satellite sphere phenomenon. 2 O 3 The ceramic powder (particle size distribution 0-100 nm) was ultrasonically dispersed in anhydrous ethanol medium, and its SEM morphology is shown in Figure 2 (a), showing a nano-scale lamellar morphology. The two powder systems were then placed in a vacuum drying oven at 80°C for 6 hours.

[0032] Step 2: Test the particle size distribution of micron 7075Al alloy powder and preset the surface nano Y 2 O 3 The thickness of the ceramic powder coating layer is 100nm, 140nm, and 200nm respectively. After calculation, the nano Y 2 O 3The mass proportions of ceramic powders were 3.51%, 5.20%, and 6.85%, respectively (the experimental groups were named 1-1#, 1-2#, and 1-3#, and the control group was pure metal powder).

[0033] Step 3: Put the pretreated powder obtained in step 1 into a ball mill according to the mass fraction ratio calculated in step 2 for powder coating and mixing. The mechanical ball milling parameters are: ball-to-material ratio is 3:1, ball milling speed is 400rpm, ball milling time is 4h, grinding ball diameter and ratio: 4mm, 8mm, 10mm (quantity ratio is 6:4:1); grinding ball material: 316 stainless steel; tank material: 316 stainless steel.

[0034] After drying the mixed powder obtained in step 3, the micro-nano composite 7075Al / Y for solid-state rapid additive manufacturing of aluminum alloy can be obtained. 2 O 3 The microscopic morphology test results of the powder (test group 1-2#) are shown in Figure 4(a). 2 O 3 The particles form a continuous coating structure on the surface of the matrix, which improves the surface roughness of the powder.

[0035] Step 4: Prepare the micro-nano composite 7075Al / Y 2 O 3 The powder properties were tested (including the particle size distribution, bulk density, tap density, fluidity and laser absorptivity of the powder). After micro-nano composite treatment, the particle size distribution test results of the powder (test group 1-2#) are shown in Figure 3 (b). 2 O 3 The particle size range of the powder is 0-30μm, which meets the powder particle size requirements of solid-state additive processing. Compared with pure metal powder (control group), the average particle size of the composite powder has been improved to varying degrees, and the median particle size has increased from 11.70μm to 12.90μm. The results of the bulk density, tap density, fluidity test and laser absorption rate test of the micro-nano composite powder prepared by this method are shown in Table 2. Compared with pure metal powder, with the increase of nanoparticle content, the surface roughness of the composite powder increases, and the bulk density decreases, with a minimum of 1.221 g / cm 3 However, the tap density increased significantly with the increase of nanoparticle content, reaching a maximum of 1.690 g / cm 3 The laser absorption rate of the composite powder was tested. The test results showed that with the increase of nanoparticle content, the laser absorption rate of the powder increased significantly, with the maximum increase of 18.24%.

[0036] Table 2

[0037] Comparing the additive manufacturing samples made of micro-nano composite powder with those made of pure metal powder, many performance indicators have been significantly improved. 2 O 3 The microstructure of the additive sample (test group 1-2#) prepared by powder is shown in Figure 6 (b). The plastic deformation of the metal powder can be clearly observed, and the nanoparticles are filled at the edge of the deformed metal powder, which effectively reduces the porosity of the additive sample. Compared with the additive sample prepared by pure metal powder, the deposition efficiency is increased from 27.42% to 49.31%; the porosity is reduced from 1.89% to 0.34%; and the microhardness is increased from 145HV to 169HV.

[0038] Example 2 Specifically, refer to Figure 1 In this embodiment, 7075Al / TiB is used for solid-state additive manufacturing. 2 The preparation method of the micro-nano composite powder comprises the following steps: Step 1: Powder pretreatment: 7075 aluminum alloy powder is pretreated by mechanical grinding and dispersion. Figure 2 (c) shows that the powder after treatment presents a typical near-spherical structure with significant satellite sphere phenomenon. 2 The ceramic powder (particle size distribution 0-200 nm) was ultrasonically dispersed in anhydrous ethanol medium, and its SEM morphology is shown in Figure 2 (b), showing a nanoscale irregular block morphology. The two powders were then placed in a vacuum drying oven at 80°C and dried for 6 hours.

[0039] Step 2: Test and obtain the particle size distribution of micron 7075Al alloy powder, and preset the surface nano-TiB 2 The thickness of the ceramic powder coating layer is 100nm and 200nm respectively. After calculation, the nano-TiB to be added is obtained. 2 The mass proportions of ceramic powders were 2.56% and 5.05%, respectively (the experimental groups were named 2-1# and 2-2#, and the control group was pure metal powder).

[0040] Step 3: Put the pretreated powder obtained in step 1 into a ball mill according to the mass fraction ratio calculated in step 2 for powder coating and mixing. The mechanical ball milling parameters are: ball-to-material ratio is 3:1, ball milling speed is 350rpm, ball milling time is 4h, grinding ball diameter and ratio: 4mm, 8mm, 10mm (quantity ratio is 6:4:1); grinding ball material: 316 stainless steel; tank material: 316 stainless steel.

[0041] After drying the mixed powder obtained in step 3, the micro-nano composite 7075Al / TiB for solid-state rapid additive manufacturing of aluminum alloy can be obtained. 2The microstructure of the powder (test group 2-2#) is shown in Figure 4(b). It can be seen that the nano-TiB 2 The particles gather in a point-like manner on the surface of the matrix to form a discontinuous coating structure, which improves the surface roughness of the powder.

[0042] Step 4: Prepare the micro-nano composite 7075Al / TiB 2 The powder properties test (including powder particle size distribution, bulk density, tap density and laser absorptivity) of the powder after micro-nano composite treatment is shown in Figure 3 (c). The micro-nano composite 7075Al / TiB 2 The particle size range of the powder is 0-30μm, which meets the powder particle size requirements of solid-state additive processing. Compared with pure metal powder (control group), the average particle size of the composite powder has been improved to varying degrees, and the median particle size has increased from 11.70μm to 13.25μm. The results of the bulk density, tap density, fluidity test and laser absorption rate test of the micro-nano composite powder prepared by this method are shown in Table 3. Compared with pure metal powder, with the increase of nanoparticle content, the surface roughness of the composite powder increases, and the bulk density decreases, with a minimum of 1.172 g / cm 3 However, as the content of nanoparticles increases, the tap density increases to a maximum of 1.591 g / cm 3 The laser absorption rate of the composite powder was tested. The test results showed that with the increase of nanoparticle content, the laser absorption rate of the powder increased significantly, with the maximum increase of 16.82%.

[0043] Table 3

[0044] Comparing the additive manufacturing samples made of micro-nano composite powder with those made of pure metal powder, many performance indicators have been significantly improved. 2 O 3 The microstructure of the additive sample (test group 2-2#) prepared by powder is shown in Figure 6 (c). The plastic deformation of the metal powder can be clearly observed, and the nanoparticles are filled at the edge of the deformed metal powder, which effectively reduces the porosity of the additive sample. Compared with the additive sample prepared by pure metal powder, the deposition efficiency is increased from 27.42% to 46.39%; the porosity is reduced from 1.89% to 0.52%; and the microhardness is increased from 145HV to 163HV.

[0045] Example 3 Specifically, refer to Figure 1 In this embodiment, 7075Al / TiB is used for solid-state additive manufacturing. 2 The preparation method of the micro-nano composite powder comprises the following steps: Step 1: Powder pretreatment: 7075 aluminum alloy powder is pretreated by mechanical grinding and dispersion. Figure 2 (c) shows that the powder after treatment presents a typical near-spherical structure with significant satellite sphere phenomenon. 2 The ceramic powder (particle size distribution 0-200 nm) was ultrasonically dispersed in anhydrous ethanol medium, and its SEM morphology is shown in Figure 2 (b), showing a nanoscale irregular block morphology. The two powders were then placed in a vacuum drying oven at 80°C and dried for 6 hours.

[0046] Step 2: Test and obtain the particle size distribution of micron 7075Al alloy powder, and preset the surface nano-TiB 2 The thickness of the ceramic powder coating layer is 100nm and 200nm. After calculation, the nano-TiB to be added is obtained. 2 The mass proportions of ceramic powders were 2.56% and 5.05% respectively (the experimental groups were named 3-1# and 3-2#, and the control group was pure metal powder).

[0047] Step 3: Put the pretreated powder obtained in step 1 into a ball mill according to the mass fraction ratio calculated in step 2 for powder coating and mixing. The mechanical ball milling parameters are: ball-to-material ratio is 3:1, ball milling speed is 450rpm, ball milling time is 4h, grinding ball diameter and ratio: 4mm, 8mm, 10mm (quantity ratio is 6:4:1); grinding ball material: 316 stainless steel; tank material: 316 stainless steel.

[0048] After drying the mixed powder obtained in step 3, the micro-nano composite 7075Al / TiB for solid-state additive manufacturing of aluminum alloy can be obtained. 2 The microstructure test results of the powder (test group 3-2#) are shown in Figure 4(b). It can be seen that the nano-TiB 2 The particles gather in a point-like manner on the surface of the matrix to form a discontinuous coating structure, which improves the surface roughness of the powder.

[0049] Step 4: Prepare the micro-nano composite 7075Al / TiB 2 The powder properties test (including powder particle size distribution, bulk density, tap density and laser absorptivity) of the powder after micro-nano composite treatment is shown in Figure 3 (d). The micro-nano composite 7075Al / TiB 2The particle size range of the powder is 0-30μm, which meets the powder particle size requirements of solid-state additive processing. Compared with pure metal powder (control group), the average particle size of the composite powder has been improved to varying degrees, and the median particle size has increased from 11.70μm to 14.87μm. The results of the bulk density, tap density, fluidity test and laser absorptivity test of the micro-nano composite powder prepared by this method are shown in Table 4. Compared with pure metal powder, with the increase of nanoparticle content, the surface roughness of the composite powder increases, and the bulk density decreases, with a minimum of 1.193 g / cm 3 However, as the content of nanoparticles increases, the tap density increases significantly, reaching a maximum of 1.577 g / cm 3 The laser absorption rate of the composite powder was tested. The test results showed that with the increase of nanoparticle content, the laser absorption rate of the powder increased significantly, with the maximum increase of 15.27%.

[0050] Table 4

[0051] Comparing the additive manufacturing samples made of micro-nano composite powder with those made of pure metal powder, many performance indicators have been significantly improved. 2 The microstructure of the additive sample (test group 3-2#) prepared by powder is shown in Figure 6 (d). The plastic deformation of the metal powder can be clearly observed, and the nanoparticles are filled at the edge of the deformed metal powder, which effectively reduces the porosity of the additive sample. Compared with the additive sample prepared by pure metal powder, the deposition efficiency is increased from 27.42% to 44.13%; the porosity is reduced from 1.89% to 0.65%; and the microhardness is increased from 145HV to 161HV.

[0052] Comparative Example Step 1: Powder pretreatment: 7075 aluminum alloy powder was mechanically ground and dispersed. Figure 2 (c) shows that the powder after treatment presents a typical near-spherical structure with significant satellite sphere phenomenon. The powder was then placed in a vacuum drying oven at 80°C for 6 hours.

[0053] Step 2: Test the powder properties of the pretreated powder obtained in step 1 (including the particle size distribution, bulk density, tap density and laser absorptivity of the powder). The particle size distribution of the micron 7075Al alloy powder is obtained by testing. The test results are shown in Figure 3 (a). The particle size range is 0-30μm, and the median particle size is 11.7μm, which meets the powder particle size requirements for solid-state additive processing; the test results of the bulk density, tap density and laser absorptivity are detailed in the data in the above embodiment. It can be seen that its bulk density and tap density are slightly greater than the micro-nano composite powder prepared in the embodiment, but because there are no nanoparticles attached to the surface of the powder, its laser absorptivity is low.

[0054] Step three, the pretreated powder obtained in step one is used for solid-state additive manufacturing of aluminum alloy. The test results of the microstructure morphology of the prepared additive manufacturing sample (control group) are shown in Figure 6 (a). Due to the low laser absorption rate of pure metal powder, the softening degree of the powder by laser-assisted heating is low, and the plastic deformation capacity of the powder particles is insufficient. As can be seen in Figure 6 (a), there are many pores formed in the unbonded area, and its porosity is measured to be 1.89%. At the same time, the deposition efficiency of the control group is measured to be only 27.42%, and the utilization efficiency of the powder is low. Its maximum microhardness is 145HV, and the mechanical properties of the additive manufacturing sample are poor.

[0055] Combining the above three embodiments and comparative examples, the conclusion shows that the Y 2 O 3 / TiB 2 -7075 aluminum alloy micro-nano composite system, the addition of nano powder can achieve surface modification of metal powder and improve the laser absorption rate of metal powder, so that micro-nano composite powder shows significant performance advantages in solid-state additive manufacturing, with deposition efficiency increased by up to 21.89%, density increased by up to 99.66%, and microhardness increased by up to 24HV, proving that micro-nano composite powder can improve the comprehensive performance of solid-state additive manufacturing aluminum alloy.

[0056] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A micro-nano composite aluminum alloy powder for solid-state additive manufacturing, characterized in that: The invention comprises micro-nano composite powder, wherein the micro-nano composite powder comprises micron-shaped spherical aluminum alloy powder and nano ceramic powder coated on the surface of the micron-shaped spherical aluminum alloy powder.

2. The micro-nano composite aluminum alloy powder for solid-state additive manufacturing according to claim 1, characterized in that: The micron spherical aluminum alloy powder is Al-Zn-Mg-Cu alloy powder.

3. The micro-nano composite aluminum alloy powder for solid-state additive manufacturing according to claim 1, characterized in that: The nano ceramic powder is at least one of Y2O3 powder, TiB2 powder and Al2O3 powder.

4. The micro-nano composite aluminum alloy powder for solid-state additive manufacturing according to claim 3, characterized in that: The Y2O3 powder is in the form of fine flakes, the Al2O3 powder is in the form of irregular blocks, and the TiB2 powder is in the form of irregular blocks.

5. The micro-nano composite aluminum alloy powder for solid-state additive manufacturing according to any one of claims 1 to 4, characterized in that: The particle size of the micron spherical aluminum alloy powder is not greater than 45 μm, the particle size of the nano ceramic powder is not greater than 200 nm, and the thickness of the nano ceramic powder coated on the surface of the micron spherical aluminum alloy powder is 100-300 nm.

6. A method for preparing micro-nano composite aluminum alloy powder for solid-state additive manufacturing, characterized in that: The process includes the following: The micron spherical aluminum alloy powder and the nano ceramic powder are mixed and ball-milled to coat the nano ceramic powder on the surface of the micron spherical aluminum alloy powder, thereby obtaining the micro-nano composite aluminum alloy powder for solid-state additive manufacturing.

7. The method for preparing a micro-nano composite aluminum alloy powder for solid-state additive manufacturing according to claim 6, characterized in that: In terms of mass percentage, the amount of micron spherical aluminum alloy powder is 90% to 99.4% of the total mass of the micron spherical aluminum alloy powder and the nano ceramic powder, and the amount of the nano ceramic powder is 90% to 99.4% of the total mass of the micron spherical aluminum alloy powder and the nano ceramic powder.

8. The method for preparing a micro-nano composite aluminum alloy powder for solid-state additive manufacturing according to claim 6, characterized in that: The particle size of the micron spherical aluminum alloy powder is not greater than 45 μm, the particle size of the nano ceramic powder is not greater than 200 nm, and the thickness of the nano ceramic powder coated on the surface of the micron spherical aluminum alloy powder is 100-300 nm; The micron spherical aluminum alloy powder is Al-Zn-Mg-Cu alloy powder; the nano ceramic powder is at least one of Y2O3 powder, TiB2 powder and Al2O3 powder; the Y2O3 powder is in the form of fine flakes, the Al2O3 powder is in the form of irregular blocks, and the TiB2 powder is in the form of irregular blocks.

9. The method for preparing a micro-nano composite aluminum alloy powder for solid-state additive manufacturing according to claim 6, characterized in that: It also includes the following processes: The micron spherical aluminum alloy powder and the nano ceramic powder are both pretreated as follows: drying at 60 to 100° C. for 4 to 8 hours to make the powder dry; The pre-treated dried micron spherical aluminum alloy powder and nano ceramic powder are ball milled.

10. The method for preparing a micro-nano composite aluminum alloy powder for solid-state additive manufacturing according to any one of claims 6 to 9, characterized in that: The micron spherical aluminum alloy powder and nano ceramic powder were mixed and ball milled using a planetary ball mill. The ball milling parameters were as follows: Ball mill speed: 350~450rpm; Ball to material ratio: (2~3):1; Ball milling time: 4-12h; Grinding ball diameter: 4mm, 8mm, 10mm, among which the number ratio of 4mm, 8mm, 10mm grinding balls is 6:4:1; Grinding ball material: 316 stainless steel grinding ball or Al2O3 grinding ball; Tank material: 316 stainless steel or Al2O3 ceramic.

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