Nanocomposite ceramic particle modified aluminum alloy powder for 3D printing and method of making the same

Abstract

The application discloses a kind of nano-composite ceramic particles modified aluminum alloy powder for 3D printing and preparation method thereof, belong to metal additive manufacturing material technical field.The powder is composed of 7XXX series aluminum alloy powder matrix and TiC and TiB2 nanoparticles attached to its surface.TiC nanoparticle addition amount is 0.3%~1% of total mass, TiB2 is 0.1%~1%, total addition amount is controlled at 0.4%~1%.Two kinds of nanoparticles are uniformly coated on the surface of aluminum alloy powder by low-energy ball milling process, and the "TiB2-Al3Ti-Al" efficient heterogeneous nucleation path is constructed.The application realizes grain ultra-fining and completely crack-free forming under very low ceramic content, while avoiding the plasticity decline and surface treatment performance degradation caused by excessive ceramic phase.The obtained powder has excellent comprehensive performance, and is suitable for the manufacturing of high-strength, high-surface quality components.

Description

Technical Field

[0001] This invention relates to the field of metal additive manufacturing materials technology, specifically to a nanocomposite ceramic particle modified aluminum alloy powder for 3D printing and its preparation method. Background Technology

[0002] Laser bed fusion (LPBF), as a mainstream metal 3D printing technology, has attracted much attention due to its ability to directly manufacture dense metal parts with complex structures. However, the extremely high cooling rate and temperature gradient of this process make the material highly susceptible to hot cracking during rapid solidification. This defect is particularly prominent in high-strength 7XXX series aluminum alloys (such as 7075), whose inherent high crack sensitivity makes it difficult to directly form these alloys using LPBF technology. Currently, commercially successful printable aluminum alloys (such as AlSi10Mg) typically have room temperature tensile strengths below 400 MPa, while LPBF forming of 7XXX series aluminum alloys with strength potential exceeding 500 MPa has become a technical challenge that urgently needs to be overcome.

[0003] To suppress cracking of high-strength aluminum alloys during the LPBF process, researchers generally employ a modification strategy that introduces heterogeneous nucleation particles to refine the grain size. Existing technologies mainly focus on adding rare earth elements, alloying elements, or ceramic particles to the aluminum alloy. Among these, adding nano-ceramic particles is considered a superior modification approach because it can effectively strengthen grain boundaries, promote nucleation, and avoid introducing excessive harmful brittle phases. Existing patent literature discloses related solutions: for example, patent CN111975188A discloses a method for adding KAlF4 and TiC nanoparticles to aluminum alloy melt for electron beam filament additive manufacturing; patent CN113373355A discloses a multi-scale particle modification of 7000 series alloy wires containing micron-sized TiB2 and nano-sized TiC; and patents CN118726784A and CN109513943A respectively disclose the use of a single high-content (e.g., 1~5 wt.%) nano-TiC or TiB2 particles mixed with aluminum alloy powder through ball milling for the LPBF process.

[0004] However, the aforementioned existing technical solutions still have significant limitations and shortcomings. First, some solutions (such as CN111975188A and CN113373355A) are aimed at additive manufacturing processes using filament materials, and their material systems and preparation methods are not directly applicable to LPBF processes using powder as raw materials. More importantly, for LPBF powder modification solutions, in order to achieve sufficient crack suppression, it is usually necessary to add a high content (usually much greater than 1 wt.%) of a single type of nano-ceramic particles. Although a high content of hard ceramic phase can suppress cracking, it brings new problems: first, it introduces a large number of stress concentration points in the matrix, significantly impairing the plasticity of the material; second, during subsequent surface treatments (such as anodizing), the non-conductive or highly conductive ceramic phase will disrupt the continuity and uniformity of the oxide film, leading to surface defects in the parts and making it difficult to meet the stringent surface quality requirements of aerospace, precision instruments, and other fields. In other words, the existing technology is caught in a dilemma: "insufficient ceramic particle content cannot suppress cracking, while sufficient content impairs overall performance."

[0005] Therefore, to address the aforementioned problems, this invention provides a nanocomposite ceramic particle-modified aluminum alloy powder for 3D printing and its preparation method. By innovatively employing two types of nano-ceramic particles, TiC and TiB2, to form a composite nucleation system and optimizing their ratio and total addition, at an extremely low total ceramic particle addition (≤1 wt.%), TiB2 promotes the formation of the highly efficient Al3Ti phase, thereby constructing an efficient "TiB2-Al3Ti-Al" heterogeneous nucleation path and achieving ultra-fine grains. This fundamentally suppresses LPBF printing cracking in 7XXX series aluminum alloys while avoiding plasticity loss and surface treatment performance degradation caused by excessive ceramic phase, effectively solving the mutually exclusive problem between printability and overall component performance. Summary of the Invention

[0006] To address the challenges of forming high-strength aluminum alloys in laser powder bed fusion (LPBF) 3D printing due to their high susceptibility to thermal cracking, and the degradation of plasticity and surface treatment properties caused by high-content single ceramic particle modification, this invention provides a nanocomposite ceramic particle-modified aluminum alloy powder for 3D printing and its preparation method. This invention designs a composite ceramic system composed of TiC and TiB2 nanoparticles, achieving highly efficient synergistic nucleation at extremely low total addition levels. This ensures that the printed parts are completely dense and crack-free while also possessing excellent mechanical properties and good anodizing suitability.

[0007] The objective of this invention is achieved through the following technical solution: A nanocomposite ceramic particle modified aluminum alloy powder for 3D printing includes a 7XXX series aluminum alloy powder matrix and composite ceramic particles composed of TiC nanoparticles and TiB2 nanoparticles uniformly attached to the surface of the matrix.

[0008] Preferably, the 7XXX series aluminum alloy powder matrix is ​​7075 aluminum alloy powder with high sphericity, and its main element chemical composition by mass percentage is: Zn 5.0~8.0%, Mg 1.5~3.0%, Cu 1.0~2.5%, Cr 0.05~0.2%, with the balance being Al and unavoidable impurities. Choosing this composition range of 7075 aluminum alloy as the matrix aims to leverage the high strength potential of this alloy system. Using spherical powder ensures good flowability, high powder density, and uniform melting characteristics in the LPBF process, which are prerequisites for obtaining high-quality printed parts.

[0009] Preferably, in the composite ceramic particles, the mass content of TiC nanoparticles is 0.3%~1% of the total mass of the modified aluminum alloy powder, and the mass content of TiB2 nanoparticles is 0.1%~1% of the total mass. This specific ratio range is designed based on the synergistic effect mechanism of TiB2 and TiC in the aluminum alloy melt. Within this range, TiB2 particles can effectively adsorb Ti atoms in the melt and reduce the nucleation barrier of the Al3Ti phase, promoting the in-situ formation of a large number of fine L12-Al3Ti phases on or near the surface of TiC particles. The Al3Ti phase has an extremely low lattice mismatch (~0.09%) with the aluminum matrix, making it a highly efficient heterogeneous nucleation core.

[0010] Preferably, the total mass content of the TiC nanoparticles and TiB2 nanoparticles is 0.3% to 1% of the total mass of the modified aluminum alloy powder. Strictly controlling the total addition amount to below 1% is one of the key innovations of this invention. This is far lower than the content required for conventional single-particle modification (typically >5%). This low addition amount design, while fully refining the grains and completely suppressing solidification cracks through the efficient "TiB2-Al3Ti-Al" nucleation path, minimizes the damage to the plasticity of the hard ceramic relative to the matrix and avoids the negative impact on the subsequent anodizing surface quality caused by the presence of a large amount of second phase.

[0011] Preferably, the TiC nanoparticles and TiB2 nanoparticles each have an independent particle size of 50 nm to 500 nm. Using ceramic particles of this nanoscale ensures, on the one hand, that the particles can effectively embed into the surface of the aluminum alloy powder during ball milling and enter the molten pool along with the powder during printing; on the other hand, the nanoscale size provides a large specific surface area, increasing the contact interface with the melt, which is beneficial for the efficient execution of the aforementioned in-situ reaction and nucleation processes.

[0012] Preferably, the particle size range of the 7XXX series aluminum alloy powder matrix is ​​15 micrometers to 53 micrometers. This particle size range is a generally preferred range for the LPBF process, which can balance powder spreading quality, melting efficiency, and the density of the final part.

[0013] This invention also provides a method for preparing the above-mentioned nanocomposite ceramic particle modified aluminum alloy powder, the method comprising the following steps: S1. Raw material preparation: Prepare 7XXX series aluminum alloy powder, TiC nano ceramic powder and TiB2 nano ceramic powder; S2. Powder premixing: The TiC nano-ceramic powder and the TiB2 nano-ceramic powder are premixed to obtain composite nano-ceramic powder; then, the composite nano-ceramic powder and the 7XXX series aluminum alloy powder are mixed together at a preset mass ratio. S3. Low-energy mechanical ball milling: The mixed powder obtained in step S2 is placed in a ball mill and subjected to low-energy ball milling under an inert atmosphere to uniformly coat and embed the composite nano-ceramic particles into the surface of the 7XXX series aluminum alloy powder, thereby obtaining the nano-composite ceramic particle modified aluminum alloy powder.

[0014] Preferably, in step S1, the 7XXX series aluminum alloy powder is spherical with a purity ≥99.9% and a particle size D50 of 15~53μm; the TiC and TiB2 nano-ceramic powders both have a purity ≥99.9% and a particle size distribution in the range of 50~500nm. Using high-purity raw materials is fundamental to ensuring low impurity content and stable performance in the final modified powder.

[0015] Preferably, in step S3, the process parameters for the low-energy ball milling treatment are: ball mill speed of 100-150 rpm, ball milling time of 3-6 hours, stainless steel grinding balls, and a ball-to-material mass ratio of 2:1-5:1. These "low-energy" ball milling parameters are the core process control point. Their purpose is to utilize appropriate mechanical energy to achieve uniform adhesion and partial embedding of nano-ceramic particles on the surface of the aluminum alloy powder, rather than the severe plastic deformation, powder welding, or particle agglomeration caused by high-energy ball milling. This effectively maintains the original high sphericity of the aluminum alloy powder, which is crucial for the subsequent LPBF process.

[0016] Preferably, in step S3, the low-energy ball mill employs a layered loading method, specifically: the grinding balls and mixed powder are divided into at least three portions, and loaded into the ball mill jar alternately in the order of "bottom grinding balls - mixed powder - grinding balls". This unique loading method ensures more uniform mixing of powder and grinding balls in the initial stage of ball milling, avoids excessive concentration of powder at the bottom of the jar, and thus achieves a more consistent and gentler mixing effect throughout the ball milling process, further ensuring the uniform distribution of ceramic particles and the sphericity of the powder.

[0017] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art: 1. This invention fundamentally solves the problem of cracking in the printing of high-strength aluminum alloys. Through a unique composite design of TiC and TiB2 nanoparticles, it constructs an efficient heterogeneous nucleation path of "TiB2→Al3Ti→Al". It achieves ultra-fine solidification of the molten pool structure with extremely low ceramic addition, which fundamentally suppresses the tendency of high-strength aluminum alloys such as 7XXX series to crack during laser powder bed melting (LPBF) and enables the successful printing of dense and crack-free complex components.

[0018] 2. This invention achieves a synergistic improvement in high strength and good plasticity. The extremely low total ceramic phase content (≤1wt.%) minimizes the damage to the material's plasticity caused by hard particles as stress concentration points. At the same time, the significant fine grain strengthening effect further enhances the material's strength. This enables the printed parts to break through the strength limit of traditional printable aluminum alloys (>400MPa) while maintaining good elongation, achieving an excellent balance between high strength and plasticity.

[0019] 3. This invention is perfectly compatible with high-end surface treatment processes. The low content and uniform distribution of the nano-ceramic phase avoids serious damage to the continuity and conductivity uniformity of the aluminum alloy matrix. Therefore, the parts printed by the powder of this invention can be successfully subjected to high-quality anodizing treatment to obtain a uniform, dense, and well-adhesive oxide film, which fully meets the stringent requirements of aerospace, precision instruments and other fields for the corrosion resistance, wear resistance and appearance of the component surface.

[0020] 4. This invention significantly reduces material costs and broadens the process window. Compared with existing technologies that require the addition of high content (usually much greater than >1 wt.%) of single ceramic particles, this invention greatly reduces the amount of expensive nano-ceramic raw materials used, resulting in a significant cost advantage. At the same time, the excellent crack resistance provides a wider and more stable selection range for LPBF process parameters (such as laser power and scanning speed), reduces the difficulty of printing process debugging, and improves production stability and yield.

[0021] 5. This invention ensures the performance of the powder processing and the quality of the forming. Through the optimized low-energy ball milling process, while achieving uniform coating of nanoparticles, the original high sphericity and flowability of aluminum alloy powder are well maintained. This ensures that the powder has good powder spreading performance and high packing density in the LPBF equipment, which is an important basis for finally obtaining high-density and high-dimensional precision formed parts. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, some of the drawings in the following description are some embodiments of the present invention. For those skilled in the art, other drawings can be made based on these drawings without creative effort.

[0023] Figure 1 This is a comparison curve of the crack density of the printed samples of Example 1, Comparative Example 1, and Comparative Example 2 of the present invention.

[0024] Figure 2 The images show a comparison of metallographic cracks in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention, wherein (a) is Example 1; (b) is Comparative Example 1; and (c) is Comparative Example 2.

[0025] Figure 3 This is an SEM image of the modified powder obtained by low-energy ball milling in Example 1 of the present invention. Detailed Implementation

[0026] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific implementation schemes are now described in detail.

[0027] The present invention will be further described below with reference to embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0028] Example 1 See appendix Figure 1 ~Appendix Figure 3 This embodiment provides a nanocomposite ceramic particle modified 7075 aluminum alloy powder for laser powder bed melting (LPBF) and its preparation method.

[0029] Raw material preparation: Spherical 7075 aluminum alloy powder (chemical composition: Zn 5.6%, Mg 2.5%, Cu 1.6%, Cr 0.23%, balance Al and unavoidable impurities) prepared by gas atomization, with a purity ≥99.9% and a particle size D50 of 30μm (range 15~53μm). Irregular TiC powder and TiB2 powder with a purity ≥99.9% and a particle size of 50~500nm were also used.

[0030] Powder formulation design: Based on the total mass of the final composite powder, the amount of TiC added is 0.8 wt.%, the amount of TiB2 added is 0.1 wt.%, the total content of composite ceramic particles is 0.9 wt.%, and the 7075 aluminum alloy matrix powder is 99.1 wt.

[0031] Powder mixing and ball milling: a. TiC and TiB2 nanopowders were premixed in a V-type mixer for 1 hour to obtain composite nano-ceramic powder.

[0032] b. Place the premixed composite ceramic powder and 7075 aluminum alloy powder together in the grinding jar of a planetary ball mill.

[0033] c. Use a layered loading method: First, put 1 / 3 of the total stainless steel grinding balls (ball-to-material mass ratio of 3:1) into the bottom of the tank, then add 1 / 3 of the mixed powder, then add 1 / 3 of the grinding balls, then add 1 / 3 of the powder, and finally put in the remaining 1 / 3 of the grinding balls.

[0034] d. Seal the ball mill jar, evacuate it, and then fill it with high-purity argon as a protective atmosphere.

[0035] e. Set the ball mill speed to 130 rpm and the ball milling time to 3.5 hours for low-energy ball milling.

[0036] Powder characterization: The obtained composite powder is shown in the attached figure. Figure 3 As shown, the powder sphericity is well maintained, and the nano-ceramic particles are uniformly attached to the surface of the aluminum alloy powder without obvious agglomeration.

[0037] LPBF Printing and Testing: The modified powder described above was used for printing on a commercial LPBF equipment. Multiple sets of process parameters (laser power P=300~400W, scanning speed v=800~1400mm / s, layer thickness d=30μm) were selected to print standard cubic specimens.

[0038] Performance testing: After grinding and polishing the printed samples, the cross-section was observed using a metallographic microscope, and the crack density (total crack length / observed area) was calculated. Samples under the optimal process window (P=370W, v=1200mm / s) were selected for room temperature tensile testing.

[0039] Example 2 This embodiment is based on the above embodiment 1, and the similarities with the above embodiment 1 will not be repeated.

[0040] The difference between this embodiment and Embodiment 1 is that the total amount of composite ceramic particles added is designed to be 0.8 wt.%, of which TiC is 0.5 wt.% and TiB2 is 0.3 wt.%.

[0041] The ball milling process parameters were adjusted to: rotation speed 120 rpm, time 4 hours, and other conditions were the same as in Example 1. Printing and testing were performed using the same LPBF process parameter window as in Example 1.

[0042] Example 3 This embodiment is based on the above embodiment 1, and the similarities with the above embodiment 1 will not be repeated.

[0043] The difference between this embodiment and Embodiment 1 is that the total amount of composite ceramic particles added is designed to be 0.6 wt.%, of which TiC is 0.5 wt.% and TiB2 is 0.1 wt.%.

[0044] The ball milling process parameters were adjusted to: rotation speed 140 rpm, time 3 hours, and other conditions were the same as in Example 1. Printing and testing were performed using the same LPBF process parameter window as in Example 1.

[0045] Comparative Example 1 This comparative example is based on Example 1 above, and the similarities with Example 1 above will not be repeated.

[0046] The difference between this comparative example and Example 1 is that TiB2 powder is not added; only single TiC nanoparticles are added at a concentration of 0.9 wt.%, which is the same as the total ceramic content in Example 1. The ball milling process and LPBF printing and testing methods are exactly the same as in Example 1.

[0047] Comparative Example 2 This comparative example is based on Example 1 above, and the similarities with Example 1 above will not be repeated.

[0048] The difference between this comparative example and Example 1 is that TiC powder is not added; only single TiB2 nanoparticles are added at a concentration of 0.9 wt.%, which is the same as the total ceramic content in Example 1. The ball milling process and LPBF printing and testing methods are exactly the same as in Example 1.

[0049] Comparative Example 3 This comparative example is based on Example 1 above, and the similarities with Example 1 above will not be repeated.

[0050] The difference between this comparative example and Example 1 is that only a single TiC nanoparticle was added, but the amount added was increased to 5.0 wt.%. To accommodate the high content, the ball milling time was extended to 5 hours, while other ball milling conditions were similar to those in Example 1. Printing and testing were performed using the same LPBF process parameter window as in Example 1.

[0051] The test results of the printed samples of the above embodiments and comparative examples under the optimal process parameters (P=370W, v=1200mm / s) are summarized in Table 1.

[0052] Table 1

[0053] Comparison of Examples 1-3 with Comparative Examples 1-2 (see appendix) Figure 1 Appendix Figure 2 It can be seen that, under the same total addition amount (0.9 wt.%), the TiC+TiB2 composite system used in this invention (Example 1) can completely suppress printing cracks (crack density < 0.1 mm). -1 In contrast, single TiC or TiB2 systems (Comparative Example 1 and Comparative Example 2) produced a large number of cracks, demonstrating the critical role of composite synergy.

[0054] A comparison of Example 1 and Comparative Example 3 shows that while Comparative Example 3, by significantly increasing the single TiC content (to 5.0 wt.%), could suppress cracking, it led to a sharp decrease in material plasticity (elongation of only 2.0%) and unsatisfactory anodized surface quality. In contrast, Example 1 of this invention, using only 0.9 wt.% of the total content, not only achieved crack-free printing but also maintained excellent plasticity (8.5%) and perfect surface treatment compatibility, fully demonstrating the outstanding advantages of this invention in balancing "formability-mechanical properties-surface properties".

[0055] Examples 1 to 13 show that within the composition and process range described in this invention (TiC 0.3-1%, TiB2 0.1-1%, total 0.4-2%), crack-free or extremely low crack density printing can be achieved, and high strength, good plasticity and surface quality can be obtained, verifying the effectiveness and feasibility of the present invention.

[0056] In summary, this invention successfully solves the core problem of "easy cracking and difficult forming" of high-strength aluminum alloys in LPBF printing by incorporating TiC and TiB2 nanoparticles in a specific ratio and in extremely low total amount (≤1 wt.%) into 7XXX series aluminum alloy powder and preparing them using an optimized low-energy ball milling process. This scheme utilizes TiB2 to promote the formation of the highly efficient Al3Ti phase, constructing a unique "TiB2-Al3Ti-Al" efficient heterogeneous nucleation pathway. This significantly refines the grains and completely suppresses solidification cracks while avoiding the plasticity loss and anodized surface quality problems caused by high ceramic phase content. Ultimately, it achieves a synergistic improvement in the high strength, good plasticity, and excellent surface treatment compatibility of the printed parts, and possesses comprehensive advantages such as low cost, wide process window, and good powder flowability, providing an ideal material solution for the additive manufacturing of complex high-performance aluminum alloy components.

[0057] The embodiments described above merely illustrate more specific and detailed implementations of the present invention, and should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A nanocomposite ceramic particle modified aluminum alloy powder suitable for use in a laser powder bed fusion additive manufacturing process, characterized in that, The powder comprises: 7XXX series aluminum alloy powder matrix; and composite ceramic particles uniformly attached to the surface of the 7XXX series aluminum alloy powder matrix, wherein the composite ceramic particles are composed of TiC nanoparticles and TiB2 nanoparticles in a certain proportion.

2. The nanocomposite ceramic particle modified aluminum alloy powder of claim 1, wherein, The 7XXX series aluminum alloy powder matrix is ​​7075 aluminum alloy powder with a spherical morphology. Its main element chemical composition by mass percentage is: Zn 5.0~8.0%, Mg 1.5~3.0%, Cu 1.0~2.5%, Cr 0.05~0.2%, with the balance being Al and unavoidable impurities.

3. The nanocomposite ceramic particle modified aluminum alloy powder according to claim 1, characterized in that, In the composite ceramic particles, the mass content of TiC nanoparticles is 0.3% to 1% of the total mass of the modified aluminum alloy powder, and the mass content of TiB2 nanoparticles is 0.1% to 1% of the total mass of the modified aluminum alloy powder.

4. The nanocomposite ceramic particle modified aluminum alloy powder according to claim 3, characterized in that, The total mass content of the TiC nanoparticles and TiB2 nanoparticles is 0.5% to 1% of the total mass of the modified aluminum alloy powder.

5. The nanocomposite ceramic particle modified aluminum alloy powder according to claim 1, characterized in that, The particle size of the TiC nanoparticles and TiB2 nanoparticles is independently 50 nm to 500 nm.

6. The nanocomposite ceramic particle modified aluminum alloy powder according to claim 1, characterized in that, The particle size range of the 7XXX series aluminum alloy powder matrix is ​​15 micrometers to 53 micrometers.

7. A method for preparing nanocomposite ceramic particle-modified aluminum alloy powder as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Raw material preparation: Prepare 7XXX series aluminum alloy powder, TiC nano ceramic powder and TiB2 nano ceramic powder; S2. Powder premixing: The TiC nano-ceramic powder and the TiB2 nano-ceramic powder are premixed to obtain composite nano-ceramic powder; then, the composite nano-ceramic powder and the 7XXX series aluminum alloy powder are mixed together at a preset mass ratio. S3. Low-energy mechanical ball milling: The mixed powder obtained in step S2 is placed in a ball mill and subjected to low-energy ball milling under an inert atmosphere to uniformly coat and embed the composite nano-ceramic particles into the surface of the 7XXX series aluminum alloy powder, thereby obtaining the nano-composite ceramic particle modified aluminum alloy powder.

8. The method according to claim 7, characterized in that, In step S1, the purity of the 7XXX series aluminum alloy powder is ≥99.9%, and the particle size D50 is 15~53μm; the purity of the TiC and TiB2 nano-ceramic powders is ≥99.9%, and the particle size is distributed in the range of 50~500nm.

9. The method according to claim 7, characterized in that, In step S3, the process parameters for the low-energy ball milling treatment are: ball mill speed of 100~150 rpm, ball milling time of 3~6 hours, grinding balls of stainless steel, and ball-to-material mass ratio of 2:1 to 5:

1.

10. The method according to claim 9, characterized in that, In step S3, the low-energy ball mill adopts a layered loading method, specifically: the grinding balls and mixed powder are divided into at least three parts, and are loaded into the ball mill jar in an alternating order of "bottom grinding balls - mixed powder - grinding balls".

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