Method for preparing Al-Sc-Zr alloy through selective laser melting
By improving the Al-Sc-Zr alloy preparation method, and utilizing plasma spheroidization treatment, interlayer gradient energy variation process, partitioned bidirectional orthogonal scanning, and vacuum dual-stage aging heat treatment, the problem that Al-Sc-Zr alloys in the prior art cannot simultaneously achieve high strength, high thermal conductivity, and high forming stability has been solved, and the high consistency of the preparation of heat dissipation components with complex structures has been realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI JIAOTONG UNIV
- Filing Date
- 2026-03-09
- Publication Date
- 2026-05-15
AI Technical Summary
Existing SLM methods for preparing Al-Sc-Zr alloys cannot simultaneously achieve precise control of bimodal microstructure decoupling, broaden the forming process window, and maximize the strengthening efficiency of precipitated phases without changing the basic alloy composition. As a result, the alloys cannot simultaneously achieve high strength, high thermal conductivity, and high forming stability, making it difficult to meet the requirements for large-scale and highly consistent fabrication of complex heat dissipation components.
Using high-purity Al, high-purity Sc, and high-purity Zr as raw materials, pre-alloyed powders are prepared by gas atomization, followed by plasma spheroidization and vacuum low-temperature annealing. Combined with the interlayer gradient energy variation process and partitioned bidirectional orthogonal scanning strategy of selective laser melting equipment, vacuum two-stage graded aging heat treatment is then carried out, including low-temperature pre-aging and high-temperature aging. Finally, water quenching, anhydrous ethanol ultrasonic cleaning, and vacuum dehydrogenation drying are performed.
It significantly improves the sphericity and flowability of powder, broadens the forming process window, and achieves high strength, high thermal conductivity and high forming stability of alloy. It solves the rigidity bottleneck of strength and thermal conductivity in the existing technology, and improves the preparation consistency and performance anisotropy of alloy.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of aluminum alloy additive manufacturing technology, and more specifically, to a method for preparing Al-Sc-Zr alloys using selective laser melting. Background Technology
[0002] With the rapid development of high-end equipment fields such as aerospace, new energy vehicles, and consumer electronics, equipment is placing increasingly stringent demands on structural and functional integrated materials that combine lightweight, high mechanical strength, and high thermal conductivity. Aluminum alloys, with their low density, excellent corrosion resistance, and processability, have become a core material for lightweight manufacturing. Among them, Al-Sc-Zr microalloying, through the microalloying design of trace amounts of Sc and Zr elements, can form nanoscale Al3(Sc,Zr) precipitates in the aluminum matrix with extremely low lattice mismatch with the matrix. This achieves significant precipitation strengthening while minimizing the loss of thermal conductivity to the matrix. It is currently one of the few aluminum alloy systems that can balance high strength and high thermal conductivity, perfectly matching the core performance requirements of high-end heat dissipation structural components.
[0003] Selective laser melting (SLM), as a typical metal additive manufacturing technology, can achieve near-net-shape forming of complex topological structures and conformal flow channel heat dissipation components, breaking through the limitations of traditional casting and forging processes on structural design. This makes it highly compatible with the application scenarios of Al-Sc-Zr alloys in high-end heat dissipation fields. Currently, the technological development of Al-Sc-Zr alloy preparation using SLM mainly focuses on three directions: component ratio optimization, SLM process parameter adaptation, and subsequent heat treatment regime adjustment. The mainstream technical route is as follows: Al-Sc-Zr pre-alloyed powder is prepared using a gas atomization process and then directly used for SLM forming. Forming is performed through a single overall scanning process with a fixed volumetric energy density matching laser power and scanning speed, followed by single-stage high-temperature annealing to achieve precipitation strengthening and matrix property optimization.
[0004] However, the existing technologies mentioned above have a core technical bottleneck that cannot be overcome: the existing SLM method for preparing Al-Sc-Zr alloys cannot simultaneously achieve precise control of the decoupling of the bimodal structure, broaden the forming process window, and maximize the strengthening efficiency of the precipitated phase without changing the basic composition of the alloy. As a result, the prepared Al-Sc-Zr alloys cannot simultaneously achieve high strength, high thermal conductivity, and high forming stability, making it difficult to meet the requirements for large-scale and highly consistent preparation of complex heat dissipation components.
[0005] Specifically, the bottleneck of this core technology lies in three key dimensions: First, the existing single-integral scanning process can only passively control the bimodal structure of the alloy by adjusting the scanning speed. The proportion of fine-grained strengthening zone and coarse-grained thermally conductive zone, as well as the grain size, are strictly negatively correlated, making it impossible to achieve decoupled design of strengthening and thermal conductivity. This results in the inevitable loss of thermal conductivity accompanying the improvement of alloy strength, and there is a rigid upper limit to the synergistic optimization of the two. Second, the pre-alloyed powder prepared by gas atomization has problems such as excessive satellite powder, insufficient sphericity, and high internal stress. When directly used for SLM forming, the powder flow... Poor mobility and powder uniformity mean that low-defect formed parts can only be obtained within a very narrow range of process parameters. Small fluctuations in scanning speed and laser power can cause defects such as incomplete fusion and porosity. The forming process window is narrow and batch stability is poor. Thirdly, the existing single-stage high-temperature annealing process cannot achieve graded and controllable precipitation of Sc and Zr elements. It is difficult to accurately construct nano-precipitates with stable core-shell structures. This not only fails to fully utilize the strengthening potential of the precipitates, but also fails to completely remove the Sc and Zr solute atoms dissolved in the matrix, fundamentally limiting the simultaneous improvement of alloy strength and thermal conductivity. Summary of the Invention
[0006] The purpose of this invention is to provide a method for preparing Al-Sc-Zr alloys using selective laser melting, thereby addressing the aforementioned problems.
[0007] To achieve the above objectives, the present invention provides the following solution: A method for preparing Al-Sc-Zr alloys using selective laser melting includes the following steps: Step 1: Using high-purity Al, high-purity Sc and high-purity Zr as raw materials, the pre-alloyed powder is obtained by gas atomization after melting. The pre-alloyed powder is then subjected to plasma spheroidization treatment and vacuum low-temperature annealing treatment in sequence, and sieved to obtain powder for forming. Step 2: Using selective laser melting equipment, with pure aluminum as the substrate, the powder for forming is shaped by interlayer gradient energy conversion process combined with a partitioned bidirectional orthogonal scanning strategy to obtain an Al-Sc-Zr alloy billet; Step 3: Perform vacuum double-stage aging heat treatment on the Al-Sc-Zr alloy billet, and after completing the low-temperature pre-aging and high-temperature aging processes in sequence, quench it in water to room temperature to obtain the Al-Sc-Zr alloy finished product.
[0008] Furthermore, the sphericity of the powder after plasma spheroidization treatment in step 1 is ≥98%, and the process conditions for vacuum low-temperature annealing treatment are vacuum degree ≤1×10-3Pa, treatment temperature 200℃, and holding time 3h.
[0009] Furthermore, the particle size range of the forming powder obtained by sieving in step 1 is D10=25-35μm, D50=35-45μm, and D90=55-65μm.
[0010] Furthermore, in step 2, the laser spot diameter of the selective laser melting equipment is 80 μm, the substrate preheating temperature during the forming process is 200°C, the powder layer thickness is fixed at 30 μm, and high-purity argon gas is introduced into the forming cavity for protection while the oxygen content is controlled below 100 ppm.
[0011] Furthermore, the interlayer gradient energy variation process described in step 2 specifically employs a high volumetric energy density process for odd-numbered layers and a low volumetric energy density process for even-numbered layers. The process parameters for odd-numbered layers are: laser power 350W, scanning speed 600mm / s, scanning spacing 100μm, and volumetric energy density 194J / mm³. The process parameters for even-numbered layers are: laser power 300W, scanning speed 1200mm / s, scanning spacing 60μm, and volumetric energy density 139J / mm³.
[0012] Furthermore, the partitioned bidirectional orthogonal scanning strategy described in step 2 specifically involves dividing a single layer into square micro-regions of 400μm×400μm, with the scanning directions of adjacent micro-regions being orthogonal at 90°, and the overall scanning direction between layers being rotated by 67°.
[0013] Furthermore, the vacuum degree of the vacuum two-stage aging heat treatment in step 3 is ≤5×10-3Pa, and the process conditions for the low-temperature pre-aging are to heat up to 300℃ at a heating rate of 5℃ / min, hold for 4 hours, and then furnace cool to room temperature.
[0014] Furthermore, the high-temperature aging process conditions described in step 3 are as follows: heating to 380°C at a heating rate of 3°C / min, holding at that temperature for 6 hours, and then immediately water quenching after the holding period.
[0015] Furthermore, in step 2, after every 3 layers are formed, the formed surface is subjected to low-power laser remelting and leveling treatment. The laser remelting power is 80-100W, and the scanning speed is consistent with the scanning speed of the current formed layer.
[0016] Furthermore, in step 3, the water-quenched Al-Sc-Zr alloy product is ultrasonically cleaned with anhydrous ethanol for 10-15 minutes, and then placed under a vacuum of ≤5×10⁻⁶. -3 The hydrogen removal and drying process is completed by keeping the product in an environment with a pressure of 100°C for 1 hour.
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: Al-Sc-Zr pre-alloyed powder prepared by gas atomization has inherent defects due to the rapid solidification process: the high proportion of satellite powder and irregularly shaped powder leads to insufficient powder sphericity and poor flowability, and uneven thickness and local powder shortage are easy to occur when spreading the powder, which directly causes defects such as non-fusion and porosity during SLM forming. At the same time, rapid solidification by gas atomization introduces residual stress and lattice distortion into the powder. The stress release after the powder is heated during SLM will cause spatter, resulting in an unstable molten pool state. Ultimately, the existing technology can only obtain low-defect samples within a very narrow parameter range. This invention utilizes plasma spheroidization treatment, employing a high-temperature flame of radio frequency plasma to melt the powder surface. Under the influence of metal surface tension, the powder spontaneously spheroidizes, completely eliminating satellite powder and irregularly shaped powder, increasing the powder sphericity to over 98%. This fundamentally optimizes the powder's flowability and uniformity, avoiding forming defects caused by uneven powder distribution. Furthermore, a 200°C vacuum low-temperature annealing treatment eliminates internal stress and lattice distortion introduced by gas atomization through short-range atomic diffusion without altering the powder's grain structure, significantly reducing powder splashing during SLM forming and stabilizing the molten pool's solidification state. Combined with narrow particle size sieving (D10-D90), the consistency of powder bulk density and powder layer thickness is significantly improved.
[0018] The grain size of aluminum alloys is directly related to the cooling rate: the faster the cooling rate, the greater the undercooling of the molten pool, the higher the non-uniform nucleation rate, and the finer the grains; conversely, the slower the cooling rate, the easier it is for the grains to grow epitaxially and form coarse grains. However, existing technologies use a uniform fixed volumetric energy density process across the entire layer, resulting in a basically consistent cooling rate throughout the formed part. Only by adjusting the scanning speed can local fine-grained and coarse-grained regions be passively formed. The proportion and size of these two regions are strictly negatively correlated—an increase in the proportion of fine-grained regions inevitably leads to a decrease in the proportion of coarse-grained regions, ultimately resulting in increased strength but decreased thermal conductivity, and vice versa. This invention utilizes an interlayer gradient energy conversion process, designating odd-numbered layers as high-volume-energy-density thermally conductive layers. Employing a low scan rate of 350W, the process extends the molten pool's existence time, smooths the temperature gradient, and reduces the cooling rate, thus directionally inducing epitaxial grain growth to form a continuous coarse-grained region. This coarse-grained region has extremely few grain boundaries, which are the core scattering sources of hot carriers (electrons and phonons) in aluminum alloys. Reducing the number of grain boundaries significantly lowers thermal resistance, creating a continuous, low-resistance heat conduction channel for the alloy and fundamentally ensuring its thermal conductivity. Simultaneously, even-numbered layers are designated as low-volume-energy-density strengthening layers, using an ultra-high scan rate of 300W to achieve a molten pool cooling rate of 10... 6 -10 7With a K / s ratio, the undercooling is significantly improved, resulting in the directional generation of uniformly dispersed fine-grained regions. These fine-grained regions, through the Hall-Petch grain boundary strengthening effect, significantly hinder dislocation movement, thereby significantly improving the alloy's yield strength and tensile strength. Building upon this, the partitioned bidirectional orthogonal scanning strategy of this invention disrupts the directional growth of grains along the heat flow direction, eliminating the strong grain texture easily formed during SLM forming. Furthermore, it causes the molten pool overlap direction to intersect in-plane and interlayer, eliminating the blind zone of molten pool overlap caused by unidirectional scanning. Supplemented by low-power laser remelting and leveling treatment every three layers, the low-power laser melts the protrusions and unfused gaps on the surface layer, improving the interlayer fusion problems caused by alternating high and low energy density forming, and ensuring the uniformity of the next layer's powder thickness.
[0019] The strengthening and thermal conductivity properties of Al-Sc-Zr alloys are primarily determined by the structure of the Al3(Sc,Zr) precipitates and the content of solute atoms in the matrix. Sc has a much lower diffusion activation energy in the aluminum matrix than Zr, allowing it to diffuse and precipitate rapidly at low temperatures, while Zr requires higher temperatures for effective diffusion. Simultaneously, the dissolved Sc and Zr atoms in the matrix cause lattice distortion and strong scattering of hot carriers, which is one of the core reasons for the decrease in thermal conductivity of aluminum alloys. Current technologies employ a single-stage high-temperature annealing process, where Sc and Zr diffuse and precipitate simultaneously at high temperatures. This process easily leads to nucleation competition between the two, preventing the formation of a stable core-shell structure. The precipitates exhibit poor uniformity in size and a high risk of coarsening, hindering the full release of Orowan strengthening efficiency. Furthermore, single-stage annealing can result in incomplete precipitation of Sc and Zr solute atoms in the matrix, with residual dissolved atoms continuously reducing the alloy's thermal conductivity, ultimately failing to achieve a simultaneous improvement in both strength and thermal conductivity. This invention employs a vacuum two-stage graded aging heat treatment. The first stage is a low-temperature pre-aging process at 300℃. At this temperature, Sc atoms can diffuse effectively, while Zr atoms diffuse at an extremely low rate and hardly precipitate. Sc atoms preferentially precipitate uniformly from the matrix, forming a large number of small, dispersed Sc-rich nano-precipitate nuclei. This avoids nucleation competition between Sc and Zr, providing sufficient and uniform nucleation sites for subsequent Zr segregation. Furthermore, the low-temperature recovery process causes dislocations in the matrix to slip and annihilate, gradually releasing the interlayer residual stress introduced during SLM forming and preventing abnormal grain growth during subsequent high-temperature treatment. The second stage is a high-temperature process at 380℃. During the aging process, the diffusion of Zr atoms is fully activated at this temperature. Zr atoms spontaneously segregate towards the surface of the already formed Sc-rich precipitate core, forming a gradient core-shell structure of "Sc-rich core-Zr-rich shell." This structure is completely coherent with the aluminum matrix, with a lattice mismatch of <1.5%. This not only reduces the coarsening kinetics compared to the binary Al3Sc phase and significantly improves thermal stability, but also achieves a very strong precipitation strengthening effect through the Orowan mechanism, while not generating strong scattering of hot carriers. In addition, high-temperature aging can completely precipitate the residual Sc and Zr solute atoms in the matrix, greatly reducing matrix lattice distortion and reducing the scattering effect on hot carriers. Based on this, the present invention uses anhydrous ethanol ultrasonic cleaning followed by vacuum dehydrogenation and drying after water quenching. Utilizing the principle that the solid solubility of hydrogen in aluminum decreases sharply with decreasing temperature under vacuum, hydrogen atoms that have penetrated into the matrix during water quenching are fully diffused, precipitated, and removed by vacuum, eliminating the hydrogen embrittlement risk that easily occurs after water quenching of aluminum alloys, and further improving the long-term service stability and service life of the alloy product. Detailed Implementation
[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0021] Example 1
[0022] Powder preparation and pretreatment: Pre-alloyed powder was prepared by vacuum remelting according to the Al-0.4Sc-0.2Zr composition ratio and then by gas atomization. The powder was then subjected to plasma spheroidization treatment (sphericity ≥98% after treatment) and vacuum low-temperature annealing treatment (vacuum degree ≤1×10⁻⁶). -3 (Pa, temperature 200℃, heat preservation for 3h); sieve to obtain molding powder with particle size range of D10=30μm, D50=40μm, D90=60μm; SLM forming: A layer-by-layer gradient energy conversion process combined with a partitioned bidirectional orthogonal scanning strategy was employed. The process parameters for odd-numbered layers were: laser power 350W, scanning speed 600mm / s, scanning spacing 100μm, and volumetric energy density 194J / mm³; the parameters for even-numbered layers were: laser power 300W, scanning speed 1200mm / s, scanning spacing 60μm, and volumetric energy density 139J / mm³. The partitioned bidirectional orthogonal scanning strategy involved dividing each layer into 400μm×400μm square micro-regions, with adjacent micro-regions scanning at 90° orthogonal directions, and the overall scanning direction rotating 67° between layers. After every three layers, the formed surface underwent low-power laser remelting and leveling treatment. The laser remelting power was 90W, and the scanning speed remained consistent with the current formed layer. This resulted in the preparation of an Al-Sc-Zr alloy billet. Heat treatment and post-treatment: The alloy billet was subjected to vacuum two-stage graded aging heat treatment with a vacuum degree ≤5×10 -3 Pa; First-stage low-temperature pre-aging: heating to 300℃ at a rate of 5℃ / min, holding for 4 hours, then furnace cooling to room temperature; Second-stage high-temperature aging: heating to 380℃ at a rate of 3℃ / min, holding for 6 hours, then immediately water quenching to room temperature after holding; The water-quenched alloy product is ultrasonically cleaned with anhydrous ethanol for 12 minutes, then placed in a vacuum of ≤5×10 -3 The Al-Sc-Zr alloy was dried by holding it at 100°C for 1 hour to remove hydrogen, and finally obtained the Al-Sc-Zr alloy product.
[0023] Example 2
[0024] The only difference between this embodiment and Embodiment 1 is that the particle size range of the forming powder obtained by sieving in step 1 is D10=25μm, D50=35μm, and D90=55μm. The remaining process steps and parameters are completely consistent with Embodiment 1.
[0025] Example 3
[0026] The only difference between this embodiment and embodiment 1 is that the laser remelting power in step 2 is 80W, while the other process steps and parameters are completely consistent with those in embodiment 1.
[0027] Example 4
[0028] The only difference between this embodiment and Embodiment 1 is that the low-temperature pre-aging holding time in step 3 is 3.5 hours and the high-temperature aging holding time is 6.5 hours. The remaining process steps and parameters are completely consistent with Embodiment 1.
[0029] Comparative Example 1
[0030] Powder preparation: Vacuum remelting according to the Al-0.4Sc-0.2Zr composition ratio, pre-alloyed powder is prepared by gas atomization process, and the powder with particle size D10=25-35μm, D50=35-45μm, and D90=55-65μm is obtained by sieving. No plasma spheroidization and vacuum low temperature annealing treatment are performed. SLM forming: A single integral scanning process with a fixed volumetric energy density of 230J / mm³ is adopted, with a laser power of 325W, a scanning speed of 785mm / s, a scanning spacing of 60μm, and a 67° rotation of the interlayer scanning direction. The alloy billet is prepared by non-partitioned orthogonal scanning and interlayer laser remelting. Heat treatment: The alloy billet was subjected to single-stage annealing in air atmosphere, held at 400℃ for 2 hours, and then water quenched to room temperature. No subsequent hydrogen removal and drying treatment was performed to obtain the finished alloy product.
[0031] Comparative Example 2
[0032] The only difference between this comparative example and Example 1 is that the gas-atomized powder is not subjected to plasma spheroidization and vacuum low-temperature annealing in step 1, but is directly sieved and used for SLM forming. The remaining process steps and parameters are completely consistent with Example 1.
[0033] Comparative Example 3
[0034] The only difference between this comparative example and Example 1 is that the interlayer gradient variable energy process is not used in step 2, and all forming layers use a single process parameter with a fixed volumetric energy density of 230J / mm³ (laser power 325W, scanning speed 785mm / s, scanning spacing 60μm). The remaining process steps and parameters are completely consistent with Example 1.
[0035] Comparative Example 4
[0036] The only difference between this comparative example and Example 1 is that the vacuum two-stage graded aging heat treatment is not used in step 3, but is replaced by air atmosphere single-stage annealing treatment (water quenching after holding at 400℃ for 2 hours). The remaining process steps and parameters are completely consistent with Example 1.
[0037] Comparative Example 5
[0038] The only difference between this comparative example and Example 1 is that: in step 2, the partitioned bidirectional orthogonal scanning strategy is not used, but replaced by a unidirectional overall scan with the interlayer scanning direction rotated by 67°, and the low-power laser remelting process is not performed every 3 layers. The remaining process steps and parameters are completely consistent with Example 1.
[0039] Examples 1-4 and Comparative Examples 1-5 were tested, and the test results are shown in Tables 1 and 2.
[0040] Table 1
[0041] Table 2
[0042] Wherein, the performance anisotropy rate = |tensile strength perpendicular to the forming direction - tensile strength parallel to the forming direction| / tensile strength perpendicular to the forming direction × 100%; the effective process window width = maximum scanning speed with a density ≥ 99.80% - minimum scanning speed.
[0043] Results Analysis
[0044] The beneficial effects of powder pretreatment characteristics were verified by comparing Example 1 with Comparative Example 2 and Comparative Example 1. Example 1, through powder pretreatment involving plasma spheroidization and vacuum low-temperature annealing, achieved a relative density of 99.92%, significantly higher than Comparative Example 2's 99.51%. The effective process window width reached 700 mm / s, 3.5 times that of Comparative Example 1 (200 mm / s). The core reason for this is that powder pretreatment eliminates satellite powder and internal stress, optimizes powder flowability and melt pool stability, and solves the pain points of high sensitivity to forming defects and narrow process window in existing technologies from the raw material end, significantly improving forming quality and batch stability.
[0045] The beneficial effects of the interlayer gradient variable energy process were verified by comparing Example 1 and Comparative Example 3. Example 1 showed a tensile strength of 308 MPa and a thermal conductivity of 227 W. m -1 K -1 In contrast, the tensile strength of Comparative Example 3 was only 272 MPa and the thermal conductivity was only 212 W. m -1 K -1 The two cannot be improved simultaneously. The core reason is that the interlayer gradient variable energy process realizes the decoupling design of the coarse-grained thermally conductive layer and the fine-grained strengthening layer, breaking the rigid bottleneck of the inverse relationship between strength and thermal conductivity in the existing technology. The odd-numbered coarse-grained region constructs a low-resistance thermal conduction channel to ensure thermal conductivity, while the even-numbered fine-grained region improves mechanical properties through grain boundary strengthening, ultimately achieving a synergistic leapfrog improvement in both.
[0046] The beneficial effects of the two-stage aging heat treatment were verified by comparing Example 1 and Comparative Example 4. The results showed that the yield strength of Example 1 was increased by 21 MPa and the thermal conductivity was increased by 12 W / m² compared to Comparative Example 4. m -1 K -1 This achieves a simultaneous improvement in strength and thermal conductivity. The core reason is that the two-stage aging process preferentially precipitates Sc-rich nuclei through low-temperature pre-aging, while high-temperature aging induces Zr element segregation to form a stable core-shell structure precipitate. This maximizes the Orowan precipitation strengthening efficiency and completely removes dissolved Sc and Zr solute atoms from the matrix, reducing the scattering of hot carriers by lattice distortion. To a certain extent, this solves the problem that existing single-stage annealing technology cannot simultaneously achieve both strengthening and thermal conductivity.
[0047] The beneficial effects of partitioned orthogonal scanning and interlayer remelting were verified by comparing Example 1 and Comparative Example 5. The results show that the anisotropy rate of Example 1 was only 2.4%, far lower than the 7.6% of Comparative Example 5, while the fracture elongation increased by 3.3 percentage points and the relative density increased by 0.2%. The core reason is that partitioned bidirectional orthogonal scanning eliminates the blind zone of grain texture and melt pool overlap, significantly reducing performance anisotropy; interlayer laser remelting improves the problem of poor interlayer fusion caused by alternating high and low energy densities, eliminates micropores and step effects, and further improves the density and plasticity of the alloy.
[0048] The comprehensive effect verification of the whole process collaboration shows that, according to Example 1 and Comparative Example 1, the tensile strength of Example 1 of the present invention is increased by 23 MPa and the thermal conductivity is increased by 8 W. m -1 K -1 The elongation at break increased by 1.6 percentage points, the anisotropy rate of performance decreased by 70.7%, and the effective process window was widened by 250%.
[0049] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the present invention.
Claims
1. A method for preparing Al-Sc-Zr alloys using selective laser melting, characterized in that, Includes the following steps: Step 1: Using high-purity Al, high-purity Sc and high-purity Zr as raw materials, the pre-alloyed powder is obtained by gas atomization after melting. The pre-alloyed powder is then subjected to plasma spheroidization treatment and vacuum low-temperature annealing treatment in sequence, and sieved to obtain powder for forming. Step 2: Using selective laser melting equipment, with pure aluminum as the substrate, the powder for forming is shaped by interlayer gradient energy conversion process combined with a partitioned bidirectional orthogonal scanning strategy to obtain an Al-Sc-Zr alloy billet; Step 3: Perform vacuum double-stage aging heat treatment on the Al-Sc-Zr alloy billet, and after completing the low-temperature pre-aging and high-temperature aging processes in sequence, quench it in water to room temperature to obtain the Al-Sc-Zr alloy finished product.
2. The method for preparing Al-Sc-Zr alloy using selective laser melting according to claim 1, characterized in that, The sphericity of the powder after plasma spheroidization treatment in step 1 is ≥98%, and the process conditions for vacuum low-temperature annealing treatment are vacuum degree ≤1×10⁻⁶. -3 Pa, processing temperature 200℃, holding time 3h.
3. The method for preparing Al-Sc-Zr alloy using selective laser melting according to claim 1, characterized in that, The particle size range of the forming powder obtained by sieving in step 1 is D10=25-35μm, D50=35-45μm, and D90=55-65μm.
4. The method for preparing Al-Sc-Zr alloy using selective laser melting according to claim 1, characterized in that, In step 2, the laser spot diameter of the selective laser melting equipment is 80 μm, the substrate preheating temperature during the forming process is 200℃, the powder layer thickness is fixed at 30 μm, and high-purity argon gas is introduced into the forming cavity for protection while the oxygen content is controlled below 100 ppm.
5. The method for preparing Al-Sc-Zr alloy using selective laser melting according to claim 4, characterized in that, The interlayer gradient energy conversion process described in step 2 specifically involves using a high volumetric energy density process for odd-numbered layers and a low volumetric energy density process for even-numbered layers. The process parameters for odd-numbered layers are: laser power 350W, scanning speed 600mm / s, scanning spacing 100μm, and volumetric energy density 194J / mm³. The process parameters for even-numbered layers are: laser power 300W, scanning speed 1200mm / s, scanning spacing 60μm, and volumetric energy density 139J / mm³.
6. The method for preparing Al-Sc-Zr alloy using selective laser melting according to claim 4, characterized in that, The partitioned bidirectional orthogonal scanning strategy described in step 2 specifically involves dividing a single layer into 400μm×400μm square micro-regions, with the scanning directions of adjacent micro-regions being 90° orthogonal, and the overall scanning direction between layers being rotated by 67°.
7. The method for preparing Al-Sc-Zr alloy using selective laser melting according to claim 1, characterized in that, The vacuum degree of the vacuum two-stage aging heat treatment in step 3 is ≤5×10⁻⁶. -3 Pa, the process conditions for the low-temperature pre-aging are to heat to 300°C at a heating rate of 5°C / min, hold at that temperature for 4 hours, and then furnace cool to room temperature.
8. The method for preparing Al-Sc-Zr alloy using selective laser melting according to claim 1, characterized in that, The high-temperature aging process conditions described in step 3 are as follows: heating to 380°C at a heating rate of 3°C / min, holding at that temperature for 6 hours, and then immediately water quenching after the holding period.
9. The method for preparing Al-Sc-Zr alloy using selective laser melting according to claim 4, characterized in that, In step 2, after every 3 layers are formed, the formed surface is subjected to low-power laser remelting and leveling treatment. The laser remelting power is 80-100W, and the scanning speed is consistent with the scanning speed of the current formed layer.
10. The method for preparing Al-Sc-Zr alloys using selective laser melting according to claim 8, characterized in that, In step 3, the water-quenched Al-Sc-Zr alloy product is ultrasonically cleaned with anhydrous ethanol for 10-15 minutes, and then placed under a vacuum of ≤5×10⁻⁶. -3 The hydrogen removal and drying process is completed by keeping the product in an environment with a pressure of 100°C for 1 hour.