Heterogeneous metal synergistic high-quality solid-phase additive body and preparation method thereof

Abstract

The invention discloses a heterogeneous metal synergistic high-quality solid-phase additive body and a preparation method thereof, and belongs to the technical field of additive manufacturing. The method comprises the following steps: firstly, mixing a matrix raw material with a reinforced phase raw material, uniformly coating the reinforced phase raw material on the surface of a matrix through an optimized high-energy mechanical force mixing process to form composite powder, and then preparing the additive body by adopting a solid-phase additive manufacturing technology. The obtained additive body is uniform and compact in structure, crystal grains are remarkably refined, a strengthening phase is dispersed and separated out, the mechanical property is excellent, and the high-performance requirement can be met without relying on any post-treatment procedure. According to the method, energy consumption and carbon emission are remarkably reduced, and high-quality regeneration of waste metal and green and efficient additive manufacturing of high-performance metal components are achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of additive manufacturing, and particularly relates to a heterogeneous metal coordinated high-quality solid-phase additive body and a preparation method thereof. BACKGROUND

[0002] With the global emphasis on sustainable development and resource recycling, reducing resource consumption, reducing energy consumption and carbon emissions, and improving material utilization efficiency and product performance have become key goals for the development of manufacturing industry. In the field of metal material processing, whether it is to achieve the recycling of high-value metals such as aluminum alloys, or to carry out solid-phase additive manufacturing of high-performance metal components, the common challenges brought by the existing mainstream technology routes are faced. For metal recycling, although the widely used remelting recycling method can recycle waste metals, it has a long process flow, high energy consumption, and is prone to produce solidification defects, grain coarsening and element burning loss in the high-temperature smelting process, resulting in a decrease in the mechanical properties of the recycled metals, which can usually only be used at a lower level. Although a more sophisticated recycling smelting process including strict pretreatment, refining purification, and microstructure refinement modification is proposed for die-casting aluminum alloy waste, this process still has problems such as complex process, high cost, and serious pollution. In the field of solid-phase additive manufacturing, the traditional friction stir solid-phase additive manufacturing technology shows potential due to its high efficiency, low cost, and wide range of applicable materials, but it also encounters performance bottlenecks in actual application. This process relies on high temperature generated by high-speed rotation of the tool head to make the material plastic deformation and accumulate layer by layer, however, this purely mechanically driven process often fails to achieve full dynamic recrystallization of the raw materials, resulting in uneven distribution of grain size in the additive body; at the same time, high-temperature action easily causes the dissolution of the strengthening phase to fail or coarsens and aggregates, which seriously weakens its strengthening effect on the matrix, ultimately resulting in insufficient strength of the additive body. In order to make up for the performance defects, the traditional friction stir solid-phase additive body often has to rely on subsequent deformation or heat treatment and other post-processing procedures, but these procedures not only consume time and energy, but also bring significant carbon emissions, which is contrary to the core concept of green manufacturing.

[0003] Therefore, whether it is to pursue efficient recycling of waste metals at a high level or to realize green additive manufacturing of high-performance metal components, it is an urgent need for the industry to develop an innovative method that can overcome the disadvantages of high-temperature processes, effectively control the microstructure (grain and strengthening phase), avoid or reduce energy-intensive and pollution-intensive post-processing steps, and directly obtain high-performance products. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a heterogeneous metal coordinated high-quality solid-phase additive body and a preparation method thereof. Based on micro-alloying design, combined with process parameter optimization, the accurate control of precipitated phase is realized, aiming to break through the bottleneck of the prior art and provide a new way for the low-cost and efficient preparation of high-performance alloy structural parts.

[0005] To achieve the above object, the present application adopts the following technical solutions to achieve the above object: One of the purposes of the present application is to provide a preparation method of a high-quality solid-phase additive body with heterogeneous metal cooperation, comprising the following steps: Preparation of premixed powder: mixing the base material and the strengthening phase material to form a premixed powder; Preparation of composite powder: using high-energy mechanical force to mix the premixed powder to form a composite powder, and the base material in the composite powder is coated by the strengthening phase material; Solid-phase additive printing: using the composite powder as raw material to prepare an additive body by a solid-phase additive process.

[0006] Preferably, in the step of preparing the premixed powder, the particle size of the base material is 1-5 mm, and the particle size of the strengthening phase material is 2-200 μm. If the particle size of the strengthening phase is too large, the strengthening phase elements cannot be solid-solved into the base material, and large-size particles may be directly formed between the strengthening phase materials, which cannot significantly improve the performance. If the particle size is too small, the process cost will be increased. If the particle size of the base material is too large or too small, the formability will be poor.

[0007] Preferably, in the step of preparing the premixed powder, the base material is copper or aluminum, and the strengthening phase material is one or a combination of micro-alloying additives Cu, Zn, Mg, and Nb.

[0008] Preferably, in the step of preparing the premixed powder, the base material is aluminum, and the aluminum is derived from scrap metal; and the strengthening phase material is a heterogeneous particle.

[0009] Further preferably, before the step of preparing the premixed powder, the scrap metal chips or particles are pretreated, and the pretreatment step includes cleaning, screening, and drying the scrap metal, and the impurity removal rate of the scrap metal is ≥98%, and the mass fraction difference of the elements is ≤0.5%.

[0010] Further preferably, in the step of preparing the composite powder, the high-energy mechanical force is provided by a ball milling and mixing device, the ball milling and mixing is carried out in a positive pressure inert gas environment, the ball-to-powder ratio is (2-5):1, the ball milling speed is 200-400 rpm, and the ball milling time is 2-6 hours. If the ball-to-powder ratio is too large, more power is required during the ball milling process, which leads to increased energy consumption and cost, and may have the risk of overheating. If the ball-to-powder ratio is too small, the collision opportunity is insufficient, and the ball milling time may need to be extended, which is prone to segregation. The speed and time should ensure that the strengthening phase material is fully attached to the base material. Low speed and long time ball milling (the added powder mass is less than 5%), high speed and short time ball milling (more than 5%), and the added powder content is less than the maximum solid solubility of the element in the base material.

[0011] Preferably, in the solid phase additive printing step, the tool head rotation speed is 600-1800 rpm, the feed speed is 50-300 mm / min, and the layer thickness is 1.5-2.5 mm. Mismatch of parameters leads to poor formability and mechanical properties, low rotation speed matches low travel speed (the mass of added powder is less than 5%), and high rotation speed matches high travel speed (the mass of added powder is greater than 8%).

[0012] Preferably, after the solid phase additive printing, the workpiece is subjected to air cooling, thereby obtaining the additive body.

[0013] The second object of the present application is to provide a heterogeneous metal synergistic high-quality solid phase additive body prepared by the preparation method, wherein the grain morphology of the additive body is equiaxed crystal, the average grain size is less than or equal to 6 microns, and the additive body also has a uniformly precipitated second phase.

[0014] Preferably, the area percentage of the second phase is 1.5-15%, and the size of the second phase is 5-500 nm.

[0015] Compared with the prior art, the present application has the following beneficial effects: The additive body prepared by the present application realizes a significant improvement in the performance of the additive body through heterogeneous metal synergy and microstructure innovation. The additive body has a uniform and dense microstructure, the grain size is significantly refined, and the strengthening phase is dispersedly distributed, thereby obtaining excellent comprehensive mechanical properties. The significant advantage of the present application is that it does not need to rely on post-processing procedures such as plastic deformation or heat treatment to achieve excellent material performance, which significantly shortens the overall production cycle and simplifies the manufacturing process, while reducing the overall production cost.

[0016] The preparation method has the dual advantages of high efficiency and greenness in technology. Through the optimized solid phase additive manufacturing technology path, the high energy consumption and carbon emissions of the traditional recycling manufacturing process are significantly reduced. The method innovatively realizes the high-quality recycling of waste metal raw materials, successfully opens up the technical path from waste to high-end components, and provides a new solution for green, efficient and sustainable manufacturing of high-performance metal components. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments of the present application illustrated in the drawings and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 is the macroscopic morphology diagram of Example 1 and Comparative Example 1 of the present specification; Figure 2 is the reverse pole diagram of Comparative Example 1 of the present specification; Figure 3 is the reverse pole diagram of Example 1 of the present specification; Figure 4transmission map for Example 1 of the present specification; Figure 5 stress strain curve for Example 1 and Comparative Example 1 of the present specification; Figure 6 polarization map for Comparative Example 2 of the present specification; Figure 7 polarization map for Example 2 of the present specification; Figure 8 transmission map for Example 2 of the present specification; Figure 9 stress strain curve for Example 2 and Comparative Example 2 of the present specification; Figure 10 polarization map for Example 3 of the present specification; Figure 11 stress strain curve for Example 3 and Comparative Example 3 of the present specification; Figure 12 morphology map for pre-mixed powder and mixed powder; Figure 13 flow chart for preparing additive bodies according to the present specification. DETAILED DESCRIPTION

[0018] Various illustrative embodiments of the present application are now described in detail. The description made herein is not to be construed as limiting the present application, but rather merely as describing certain aspects, features, and embodiments of the present application.

[0019] It should be understood that the terms used herein are merely descriptive, but that the application should not be construed as being limited thereto. In addition, with respect to numerical ranges recited in the present application, it is contemplated that every numerical value, including any intermediate value and any other stated value, within that range is specifically and explicitly contemplated. Each smaller range that falls within the broader range is also specifically and explicitly contemplated. The upper and lower limits of these smaller ranges can independently be included or excluded in the smaller ranges.

[0020] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In the case of conflict between the present specification and any document incorporated by reference, the present specification will control.

[0021] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, which will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary. The terms "comprising," "including," "having," "containing," etc., as used herein are open-ended, meaning they include but are not limited to.

[0022] The method of the present invention will be further described below with reference to the accompanying drawings and embodiments. In the following embodiments, conventional instruments and equipment in the art are used, and all raw materials and reagents used, unless otherwise stated, are conventional commercially available products with specifications in the art, or can be prepared or formulated by known methods or reagent instructions. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the manufacturer.

[0023] like Figure 13 The diagram shown is a flowchart of the additive manufacturing process according to an embodiment of this specification. The invention will now be described in further detail with reference to other accompanying drawings: Example 1 Step 1: Add Cu powder and AZ31 powder to 6061 aluminum alloy particles. The mass percentage of each element is: Cu 3%, AZ31 1.6%. The diameter of the 6061 aluminum alloy particles is 2.5 mm, and the particle size of the powder is 100~150 μm to obtain a premixed powder. Step 2: In this embodiment, ball milling is selected as the mixing method. The grinding balls and the mixed powder are placed in a ball mill jar at a ball-to-powder ratio of 3:1. The ball mill jar is subjected to vacuuming and gas-filling treatment three times to prevent oxidation during the ball milling process. The ball milling time is 6 hours at a speed of 200 rpm, ensuring the powder is uniformly adhered to the surface of the 6061 aluminum alloy particles, thus obtaining composite powder particles. See [link to relevant documentation]. Figure 12 ; Step 3: After ball milling, the milling beads and composite particles are separated using a sieve and then placed in a sample bag for storage. Step 4: Fix the substrate and form it using solid-state additive manufacturing process. The process parameters are: tool head speed 600 rpm, feed rate 50 mm / min, and layer thickness 1.5 mm. Step 5: After forming, the aluminum alloy additive body is directly air-cooled to obtain the additive body, and the microstructure and properties of the additive body are characterized.

[0024] Microscopic tissue observation methods: The grain size of the additive body was analyzed by electron backscatter diffraction (EBSD). In the experiment, electrolytic polishing technology was used to polish the sample, 10% perchloric acid + 90% ethanol solution was used as electrolyte, and the temperature of the electrolyte was controlled at about -40℃ by liquid nitrogen bath. A constant voltage of 20 volts was applied during electrolytic polishing. After polishing, the sample was quickly washed with clean water to remove surface residues.

[0025] The microstructure of the sample was analyzed by FEI Tecnai F30 transmission electron microscope (TEM). The sample was cut along the connecting surface with a size of 8 mm (long) x 8 mm (wide) x 1.2 mm (thick), and after mechanical polishing and polishing, it was punched into a 3 mm diameter disc, and electrolytic double spray thinning was carried out in a 30% HNO3+70% CH3OH solution. TEM was used to characterize the morphology and size of the second phase.

[0026] Performance test: according to GB / T 2651-2008 "welded joint tensile test method" standard, the joint in the example was tested at room temperature.

[0027] Example 2 Step 1, add Nb powder to copper alloy particles, the mass percentage of Nb powder is 3%, the powder particle size is 150-200 μm, and the diameter of copper alloy particles is 5 mm, to obtain mixed powder; Step 2, the mixing method of this embodiment is selected as ball milling, the ball milling beads and the mixed powder are put into the ball milling tank, the ball-to-powder ratio is 5:1, the ball milling tank is subjected to vacuum-air treatment for 3 times to prevent oxidation during ball milling, the ball milling time is 2 hours, and the rotating speed is 400 rpm, so that the powder is uniformly attached to the surface of the copper alloy particles, to obtain composite particles; Step 3, after ball milling, the ball milling beads and the composite particles are separated by using a screen, and then they are put into a sample bag for storage; Step 4, fix the substrate, and form by solid phase additive manufacturing process, the process parameters are: tool head rotating speed 1800 rpm, feeding speed 300 mm / min, and layer thickness 2.5 mm; Step 5, after forming, directly air cooling to obtain a copper alloy additive body, and the microstructure and performance of the additive body are characterized. The microstructure observation method is: The grain size of the additive body was analyzed by electron backscatter diffraction (EBSD). In the experiment, electrolytic polishing technology was used to polish the sample, 10% perchloric acid + 90% ethanol solution was used as electrolyte, and the temperature of the electrolyte was controlled at about -40℃ by liquid nitrogen bath. A constant voltage of 20 volts was applied during electrolytic polishing. After polishing, the sample was quickly washed with clean water to remove surface residues.

[0028] Performance test method is same as example 1.

[0029] Example 3 Step 1, the recovered scrap metal chips, particles are cleaned, screened and dried, remove the surface oil, cutting fluid, oxide and dust and other impurities, get clean scrap metal materials, drying process in the atmosphere of protective gas nitrogen or argon gas, etc. to prevent oxidation of metal materials. Select 6061 aluminum alloy particles, Mg powder, Cu powder and Zn powder, through the standard mesh sieve, obtain the particle size of 1~2mm 6061 aluminum alloy particles, particle size of 2~10 μm Mg powder, particle size of 10~30 μm Cu powder, particle size of 30~50 μm Zn powder.

[0030] Step 2, the mixing method of this embodiment is selected by ball milling, the ball milling beads and the premixed powder are put into the ball milling tank, the ball to powder ratio is 2:1, the ball milling tank is subjected to vacuum-air treatment for 3 times to prevent oxidation during ball milling, the ball milling time is 4 hours, and the rotating speed is 300 rpm, so that the powder is uniformly attached to the surface of the copper alloy particles, and the composite powder particles are prepared; Step 3, after the ball milling is completed, the ball milling beads and the composite particles are separated by using a screen, and then they are put into a sample bag for storage; Step 4, the substrate is fixed, and a solid phase additive manufacturing process is used for forming, and the process parameters are as follows: tool head rotating speed 1200 rpm, feeding speed 180 mm / min, and layer thickness 2 mm; Step 5, after the forming, direct air cooling is carried out, the aluminum alloy additive body is prepared, and the microstructure and performance of the additive body are characterized.

[0031] Microstructure observation method: The grain size of the additive body is analyzed by using electron backscatter diffraction technology (EBSD). In the experiment, electrolytic polishing technology is used for polishing the sample, 10% perchloric acid + 90% ethanol solution is used as electrolyte, and the temperature of the electrolyte is controlled at about-40℃ by using liquid nitrogen bath. A constant voltage of 20 volts is applied in the electrolytic polishing. After polishing, the sample is quickly washed with clean water to remove the surface residue.

[0032] Performance test method is same as example 1.

[0033] Comparative example 1 Step 1, the substrate is fixed, and the 6061 aluminum alloy particles are directly subjected to solid phase additive manufacturing, the diameter of the aluminum alloy particles is 2.5 mm, and the process parameters are as follows: tool head rotating speed 800 rpm, feeding speed 50 mm / min, and layer thickness 1.5 mm; Step 2, after the forming, direct air cooling is carried out, and then the microstructure and performance of the 6061 aluminum alloy additive body are characterized.

[0034] Comparative example 2 Step 1, fixed substrate, directly solid-phase additive manufacturing on copper alloy particles, the diameter of the copper alloy particles is 5 mm, the tool head rotation speed is 1800 rpm, the feeding speed is 250 mm / min, and the layer thickness is 2.5 mm; Step 2, directly air cooling after forming, and then microstructure and performance of the copper alloy additive body are characterized.

[0035] Comparative Example 3 Step 1, cleaning, screening and drying of the recycled waste metal chips and particles, removing surface oil stains, cutting fluid, oxides and dust and other impurities, obtaining clean waste metal materials, the drying process is carried out in a protective gas atmosphere such as nitrogen or argon to prevent oxidation of the metal material. Through a standard mesh screen, 6061 aluminum alloy particles with a particle size of 1-2 mm are obtained; Step 2, fixed substrate, directly solid-phase additive manufacturing on aluminum alloy particles, the tool head rotation speed is 1200 rpm, the feeding speed is 180 mm / min, and the layer thickness is 2 mm.

[0036] Table 1 is the tensile property test results of the samples prepared in the examples and comparative examples of the present specification, and it can be seen that the strength of the examples is better than that of the comparative examples.

[0037] Table 1 Tensile properties

[0038] As shown in the present application examples and comparative examples, the additive body is well macroformed. Figure 1

[0039] Figure 2 , Figure 3 , Figure 6 , Figure 7 , Figure 10 The present application examples and comparative examples are shown in the inverse pole figure diagram, the average grain size of the additive body of examples 1-3 prepared by the manufacturing method of the present application is ≤6 μm. As shown in Figure 2 , Figure 3 Comparing the grain size of example 1 after adding micro-alloying elements with comparative example 1, it can be seen that the grain size is obviously refined, the average grain size of comparative example 1 is 10.6 μm, and the average grain size of example 1 after adding micro-alloying elements is reduced to 3.7 μm; as shown in Figure 6 , Figure 7 Comparing the grain size of example 2 after adding micro-alloying elements with comparative example 2, it can be seen that the grain size is also obviously refined, the average grain size of comparative example 2 is 10.2 μm, and the average grain size of example 2 after adding micro-alloying elements is reduced to 4.5 μm; as shown in Figure 9 ​The average grain size of example 3 after adding micro-alloying elements is 5.2 μm.

[0040] Figure 4 and Figure 8 The transmission electron microscope images of example 1 and example 2 are shown. From the images, it can be seen that the second phase is uniformly distributed at the grain boundaries and in the grains, which can play a role of pinning the grain boundaries to refine the grains and improve the strength, and can hinder the dislocation movement in the grains to improve the strength. The area percentage of the micro-alloying second phase is between 1.5 and 15%, and the size is between 5 and 500 nm. Figure 5 、 Figure 9 、 Figure 11 The mechanical properties of the examples and the comparative examples are shown. After adding the micro-alloying elements, the strength is improved.

[0041] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for preparing a high-quality solid-phase additive with heterogeneous metal synergy, characterized in that, Includes the following steps: Preparation of premixed powder: Mix matrix raw materials and reinforcing phase raw materials to form premixed powder; Preparation of composite powder: The premixed powder is mixed using high-energy mechanical force to form composite powder, wherein the matrix raw material in the composite powder is coated with a reinforcing phase raw material; Solid-phase additive printing: using the composite powder as raw material, an additive body is prepared by solid-phase additive manufacturing process.

2. The method for preparing high-quality solid-phase additives with heterogeneous metal synergy according to claim 1, characterized in that, In the step of preparing the premixed powder, the particle size of the matrix raw material is 1~5 mm, and the particle size of the reinforcing phase raw material is 2~200 μm.

3. The method for preparing high-quality solid-phase additives with heterogeneous metal synergy according to claim 1, characterized in that, In the step of preparing the premixed powder, the matrix material is copper or aluminum, and the reinforcing phase material is one or a combination of microalloying additives Cu, Zn, Mg, and Nb.

4. The method for preparing high-quality solid-phase additives with heterogeneous metal synergy according to claim 1, characterized in that, In the step of preparing the premixed powder, the matrix raw material is aluminum, which is derived from scrap metal; the reinforcing phase raw material is heterogeneous particles.

5. The method for preparing a high-quality solid-phase additive with heterogeneous metal synergy according to claim 4, characterized in that, Before the preparation of the premixed powder, the scrap metal scraps or particles are pretreated. The pretreatment step includes cleaning, screening and drying the scrap metal, and the impurity removal rate in the scrap metal is ≥98%, and the mass fraction difference of the elements is ≤0.5%.

6. The method for preparing a high-quality solid-phase additive with heterogeneous metal synergy according to claim 3 or 4, characterized in that, In the step of preparing the composite powder, the high-energy mechanical force is provided by the ball milling mixing equipment. The ball milling mixing is carried out in a positive pressure inert gas environment. The ball-to-powder ratio of the grinding balls to the premixed powder is (2~5):

1. The ball milling speed is 200~400 rpm and the ball milling time is 2~6 hours.

7. The method for preparing a high-quality solid-phase additive with heterogeneous metal synergy according to claim 1, characterized in that, In the solid-phase additive printing step, the tool head of the solid-phase additive printing equipment rotates at 600~1800 rpm, the feed rate is 50~300 mm / min, and the layer thickness of the solid-phase additive printing is 1.5~2.5 mm.

8. The method for preparing high-quality solid-phase additives with heterogeneous metal synergy according to claim 1, characterized in that, After the solid-phase additive printing is completed, the part is air-cooled to obtain the additive body.

9. The additive body prepared by the method according to any one of claims 1-8, characterized in that, The grain morphology is equiaxed, with an average grain size ≤6 μm, and has a uniformly precipitated second phase.

10. The additive body prepared by the preparation method according to any one of claims 9, characterized in that, The area percentage of the second phase is 1.5 to 15%, and the size of the second phase is 5 to 500 nm.

Images