Modified AlSiMg high-thermal-conductivity aluminum alloy and forming method thereof

Abstract

The invention discloses a modified AlSiMg high-thermal-conductivity aluminum alloy and a forming method thereof, and relates to the technical field of additive manufacturing. A forming method of a modified AlSiMg high-thermal-conductivity aluminum alloy comprises the following steps that raw materials are mixed according to the proportion that the content of Si ranges from 9 wt% to 11 wt%, the content of Mg ranges from 0.2 wt% to 0.45 wt%, the content of Yb ranges from 0.05 wt% to 0.3 wt%, the total amount of impurities is smaller than or equal to 0.7 wt%, and the balance Al, smelting and casting are conducted, and an alloy ingot is obtained; after the alloy cast ingot is remelted, alloy powder is prepared through a gas atomization powder preparation technology, and after screening is conducted, the aluminum alloy powder for additive manufacturing is obtained; the aluminum alloy powder for additive manufacturing is subjected to laser powder bed fusion forming, and printed alloy is obtained; and the printed alloy is subjected to medium-temperature annealing treatment, and the high-thermal-conductivity aluminum alloy is obtained. The laser additive manufacturing aluminum alloy is good in formability, an AlSi10Mg strengthening mechanism is reconstructed through Yb microalloying, the heat conduction bottleneck caused by solid solution atomic scattering is broken through, and the heat conduction performance and the mechanical performance of the aluminum alloy are synchronously improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of additive manufacturing, in particular to a modified AlSiMg high-thermal-conductivity aluminum alloy and a forming method thereof. BACKGROUND

[0002] High-thermal-conductivity aluminum alloys generally adopt Al-Mg-Si aluminum alloys, which have the characteristics of light weight, high strength, high plasticity in processing, and excellent thermal conductivity, and are widely used in the preparation of finned heat sinks and tubular heat exchangers. However, in the process of metal laser powder bed fusion (L-PBF) additive manufacturing, such alloys are prone to a large number of thermal cracks under rapid melting and solidification cycles due to their large solidification temperature interval, resulting in high defect rates of formed parts and unguaranteed mechanical properties and thermal conductivity. To adapt to the characteristics of the L-PBF process, the prior art mostly uses near-eutectic Al-Si alloys (such as AlSi10Mg) or hypoeutectic Al-Si alloys (such as AlSi7Mg). Such alloys utilize the characteristics of a small solidification temperature interval and excellent melt fluidity of the eutectic Al-Si system to improve the thermal cracking tendency of the alloy in the L-PBF process, but are limited by the high solid-soluble silicon content, and thus have low thermal conductivity, which cannot meet the demand of related industries for high-thermal-conductivity aluminum alloys (the tensile strength needs to be ≥400 MPa, and the thermal conductivity needs to be ≥180 W•m -1 K -1 ). Therefore, there is an urgent need for an aluminum alloy that has good laser forming performance and excellent thermal conductivity and mechanical properties. SUMMARY

[0003] The main purpose of the present application is to provide a modified AlSiMg high-thermal-conductivity aluminum alloy and a forming method thereof, aiming to solve the technical problems of poor laser forming performance and insufficient thermal conductivity of existing high-thermal-conductivity aluminum alloys.

[0004] To achieve the above-mentioned purpose, the present application provides a forming method of a modified AlSiMg high-thermal-conductivity aluminum alloy, which comprises the following steps: According to the proportioning of Si content of 9wt%-11wt%, Mg content of 0.2wt%-0.45wt%, Yb content of 0.05wt%-0.3wt%, total impurity content of ≤0.7wt%, and Al as the balance, the raw materials are mixed, melted, and cast to obtain an alloy ingot; After remelting the alloy ingot, an alloy powder is prepared by a gas atomization powdering process, and after screening, an aluminum alloy powder for additive manufacturing is obtained; The aluminum alloy powder for additive manufacturing is subjected to laser powder bed fusion forming to obtain a printed alloy; The printed alloy is subjected to medium-temperature annealing treatment to obtain a high-thermal-conductivity aluminum alloy.

[0005] Optionally, in the step of mixing the raw materials, smelting and casting to obtain the alloy ingot, the raw materials include industrial pure aluminum, industrial pure magnesium, aluminum-silicon master alloy and aluminum-ytterbium master alloy.

[0006] Optionally, the step of mixing the raw materials, smelting and casting to obtain an alloy ingot comprises: The raw materials are smelted at 750-780°C for 20-40 minutes, then cooled to 740-760°C, electromagnetically stirred for 15-20 minutes, mixed evenly, kept warm and allowed to stand for 20-30 minutes, and then cast to obtain alloy ingots.

[0007] Optionally, the step of remelting the alloy ingot and then preparing the alloy powder through a gas atomization powder making process comprises: Remelting the alloy ingot at 860° C.-880° C. for 30 min-50 min to obtain an aluminum alloy melt; The aluminum alloy melt is discharged through an alumina conduit at a flow rate of 4 kg / min-4.5 kg / min, and high-speed compressed argon gas is used to impact the aluminum alloy melt to atomize the aluminum alloy melt to form alloy powder; The purity of the high-speed compressed argon gas is ≥99.999%, and the pressure is 3MPa-7MPa.

[0008] Optionally, in the screening step, a cyclone separation powder collection method is adopted, and screening is performed under the high-speed compressed argon atmosphere.

[0009] Optionally, the aluminum alloy powder for additive manufacturing has a particle size of 15 μm-53 μm and a sphericity rate of ≥95%.

[0010] Optionally, in the step of performing laser powder bed melting on the aluminum alloy powder for additive manufacturing to obtain a printed alloy, the parameters of the laser powder bed melting process are set to: laser power of 200W-350W, scanning speed of 800mm / s-2000mm / s, scanning spacing of 80μm-120μm, and powder layer thickness of 20μm-60μm.

[0011] Optionally, in the step of performing laser powder bed melting on the aluminum alloy powder for additive manufacturing to obtain a printed alloy, the laser powder bed melting process is carried out in an argon atmosphere with an oxygen content of <100 ppm, while using directional blowing of argon gas flow.

[0012] Optionally, in the step of performing medium-temperature annealing on the printed alloy to obtain a high thermal conductivity aluminum alloy, the annealing temperature is 150° C.-350° C., and the annealing time is 1 hour-24 hours.

[0013] The present application also proposes a modified AlSiMg high thermal conductivity aluminum alloy, which is obtained by the forming method of the modified AlSiMg high thermal conductivity aluminum alloy.

[0014] This application has at least the following beneficial effects: This application is based on the smaller solidification temperature range of the Al-Si binary alloy system, which has a low solidification shrinkage rate, can reduce stress in the molten pool and inhibit thermal cracking, thereby giving the aluminum alloy good laser forming performance and solving the problem of laser powder bed melting forming of high thermal conductivity aluminum alloy; The present application uses Si and Mg as the main alloying elements. During the additive manufacturing process with a large temperature gradient and high solidification rate, Si and Mg will be dissolved into the aluminum matrix in large quantities due to the solute retention effect. At the same time, the microalloying Yb element added in the present application can form a nanoscale Al3(Yb, Si) phase, which is coherent with the α-Al matrix. In the subsequent medium-temperature annealing process, a large amount of Mg2Si and Si nanophases are precipitated in the aluminum matrix, and a large amount of Al3(Yb, Si) phase is also independently precipitated. The nanoscale Al3(Yb, Si) and Mg2Si / Si phase can not only synergistically strengthen the matrix, but also significantly reduce the content of solid solution atoms (especially Si atoms) in the aluminum matrix, thereby breaking through the thermal conductivity bottleneck caused by solid solution atom scattering. While giving the aluminum alloy good mechanical properties, it also achieves its high thermal conductivity. Compared with traditional aluminum alloys, the laser additively manufactured aluminum alloy of this application has good laser formability, and through Yb microalloying to reconstruct the AlSi10Mg strengthening mechanism, it solves the contradiction between the solid solution Si concentration and the strength, and simultaneously improves the thermal conductivity and mechanical properties of the aluminum alloy. It can realize the forming and preparation of three-dimensional topological optimized structures and complex configuration parts, and has broad application prospects in communications, microelectronics, semiconductors, automobiles, aviation, aerospace and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0016] Figure 1 This is a flow chart of the forming method of the modified AlSiMg high thermal conductivity aluminum alloy described in an embodiment of the present application.

[0017] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0019] At present, Al-Mg-Si alloys have a large solidification temperature range, which makes them prone to a large number of thermal cracks under rapid melting cycles, resulting in a high defect rate of formed parts, and the mechanical properties and thermal conductivity cannot be guaranteed. In order to adapt to the characteristics of the L-PBF process, existing technologies mostly use near-eutectic Al-Si alloys (such as AlSi10Mg) or hypoeutectic Al-Si alloys (such as AlSi7Mg). These alloys take advantage of the characteristics of the eutectic Al-Si system with a small solidification temperature range and excellent melt fluidity, which can improve the alloy's tendency to thermal cracking in the L-PBF process. For example, the AlSi10Mg alloy manufactured by L-PBF additive manufacturing has a large amount of Si and Mg atoms dissolved in the aluminum matrix due to the large temperature gradient and high cooling rate during the printing process, resulting in a high tensile strength (510MPa), but a low thermal conductivity (95W•m -1 K -1 -110W•m -1 K -1 After heat treatment at 300℃ for 2h, a large amount of Mg2Si and Si nanophases precipitate in the matrix, and the alloy reaches its optimal thermal conductivity (162W•m -1 K -1 ) and good mechanical properties (tensile strength 320MPa), but this performance still cannot meet the demand of related industries for high thermal conductivity aluminum alloys (tensile strength ≥400MPa, thermal conductivity ≥180W•m -1 K -1 ), if the heat treatment temperature is raised to 530℃, after 6h treatment, the precipitated phase in the alloy will coarsen and grow to micron level, which will increase the thermal conductivity (150W•m -1 K -1 ) and mechanical properties (tensile strength 280MPa) decreased simultaneously. Consequently, conventional Al-Mg-Si aluminum alloys formed using additive manufacturing suffer from severe hot cracking, and the thermal conductivity of existing mainstream additive manufacturing aluminum alloys is insufficient.

[0020] In view of the technical problems existing in the prior art, the embodiments of the present application provide a forming method of a modified AlSiMg high thermal conductivity aluminum alloy, such as Figure 1 As shown, the following steps are included: S10. Mix the raw materials, melt them, and cast them according to a ratio of Si content of 9wt%-11wt%, Mg content of 0.2wt%-0.45wt%, Yb content of 0.05wt%-0.3wt%, total impurities ≤0.7wt% and Al as the balance to obtain an alloy ingot.

[0021] Based on the characteristics of eutectic Al-Si alloy, the present application prepares an aluminum alloy with a Si content of 9wt%-11wt%. By utilizing its narrow solidification temperature range, the laser formability can be guaranteed in the additive manufacturing process with a large temperature gradient and a high solidification rate, and the generation of thermal cracks can be suppressed. In addition, Si and Mg are used as the main alloying elements. Since Mg and Si are low-melting-point elements, in order to avoid the deviation of the alloy powder composition caused by the volatilization of Mg and Si low-melting-point elements during the preparation of the alloy powder, the Si addition amount is preferably 10.5wt%-11wt%, and the Mg addition amount is preferably 0.4wt%-0.45wt%. At the same time, a trace amount of Yb element is added to modify the AlSiMg aluminum alloy. By reconstructing the AlSi10Mg strengthening mechanism through Yb micro-alloying, nano-scale Al3(Yb, Si) phase and Mg2Si / Si phase can be precipitated in large quantities during the subsequent medium-temperature annealing treatment, forming a dual strengthening system, which gives the aluminum alloy good mechanical properties. At the same time, Al3(Yb, Si) phase and Mg2Si / Si phase can be precipitated in large quantities to form a dual strengthening system, which gives the aluminum alloy good mechanical properties. The large amount of precipitation of Mg2Si) phase and Mg2Si / Si phase also reduces the content of solid solution atoms in the aluminum matrix, thereby breaking through the thermal conductivity bottleneck caused by the scattering of solid solution atoms and greatly improving the thermal conductivity of aluminum alloys.

[0022] In a specific implementation process, the step of mixing the raw materials, smelting and casting to obtain an alloy ingot includes: Industrial pure aluminum, industrial pure magnesium, aluminum silicon master alloy and aluminum ytterbium master alloy are smelted at 750-780°C for 20-40 minutes to completely melt the aluminum ytterbium master alloy, then cooled to 740-760°C, electromagnetically stirred for 15-20 minutes, mixed evenly, kept warm and allowed to stand for 20-30 minutes, and then cast to obtain an alloy ingot.

[0023] S20. After remelting the alloy ingot, the alloy powder is made into alloy powder through a gas atomization powder making process, and then the alloy powder is sieved to obtain aluminum alloy powder for additive manufacturing.

[0024] The step of remelting the alloy ingot and then preparing the alloy powder through a gas atomization powder making process comprises: Remelting the alloy ingot at 860° C.-880° C. for 30 min-50 min to obtain an aluminum alloy melt; The aluminum alloy melt is discharged through the alumina pipe at a flow rate of 4 kg / min-4.5 kg / min, and the aluminum alloy melt is atomized to form an alloy powder by using high-speed compressed argon to impact the aluminum alloy melt.

[0025] Since the melting point of alumina is high, the molten aluminum alloy melt can be discharged from the smelting furnace while avoiding the introduction of other metal elements, and in order to ensure the yield of the alloy powder, the mass flow rate of the aluminum alloy melt needs to be controlled at 4 kg / min-4.5 kg / min.

[0026] The purity of the high-speed compressed argon is ≥99.999%, and the pressure is 3 MPa-7 MPa. When the atomization pressure is lower than 3 MPa, the atomized droplets are prone to bag-type breakage due to the low pressure, and the formed alloy is prone to form hollow powder. When the atomization pressure is higher than 7 MPa, the atomized droplets are prone to sheet-type breakage due to the high pressure, and the alloy powder is too small in size and is not suitable for L-PBF metal additive manufacturing.

[0027] In the step of screening, a cyclone separation powder collection device is used, and the screening is carried out in the high-speed compressed argon atmosphere. The additive manufacturing aluminum alloy powder obtained after screening has a particle size of 15 μm-53 μm and a sphericity of ≥95%, and is suitable for L-PBF metal additive manufacturing.

[0028] S30, laser powder bed fusion forming is performed on the additive manufacturing aluminum alloy powder to obtain a printed alloy.

[0029] In the specific implementation process, the laser powder bed fusion forming process is carried out in an argon atmosphere with an oxygen content of <100 ppm. Argon is introduced before printing starts, and the laser printing is started when the oxygen content in the forming cabin is <100 ppm. Argon gas flow is used for directional blowing during printing to avoid metal spatter and oxidation inclusion solidification backfall. If the oxygen content in the forming cabin during printing is ≥100 ppm, the printing should be stopped immediately and argon should be introduced again until the environmental oxygen content meets the requirements before printing.

[0030] In the specific implementation process, the parameter settings of the laser powder bed fusion forming process are as follows: the laser power is 200 W-350 W, the scanning speed is 800 mm / s-2000 mm / s, the scanning pitch is 80 μm-120 μm, and the powder layer thickness is 20 μm-60 μm.

[0031] Specifically, since the volume energy density of the printing process is jointly determined by laser power, scanning speed, scanning pitch, and powder layer thickness, when the laser power is less than 200W, or the scanning speed is higher than 2000mm / s, or the scanning pitch is greater than 120μm, or the powder layer thickness is greater than 60μm, the input energy density will be too low to completely melt the metal powder, and unfused voids will easily appear. When the laser power is higher than 350W, or the scanning speed is lower than 800mm / s, or the scanning pitch is less than 80μm, or the powder layer thickness is less than 20μm, the input energy density is too high, which will cause the printed structure to coarsen, and thus lead to a significant decrease in the thermal conductivity of the alloy.

[0032] S40, performing a medium-temperature annealing treatment on the printed alloy to obtain a high thermal conductivity aluminum alloy.

[0033] In the specific implementation process, the annealing temperature is 150°C-350°C, and the annealing time is 1 hour-24 hours. When the annealing temperature is lower than 150°C, the nanophase is difficult to precipitate, resulting in difficulty in reducing the content of solid solution elements in the aluminum matrix and ineffectively improving the thermal conductivity of the aluminum alloy. When the annealing temperature is higher than 350°C, the precipitated phase is severely coarsened, which not only reduces the thermal conductivity of the aluminum alloy but also leads to a loss of mechanical properties.

[0034] Preferably, the annealing temperature is 300°C and the annealing time is 2 hours, which can achieve a balance between precipitation strengthening and avoiding coarsening, realize precise control of the size of the nano-precipitated phase, ensure that a large amount of Mg2Si and Si nanophases are precipitated in the aluminum matrix, and at the same time, a large amount of Al3(Yb, Si) phase is also independently precipitated, thereby synergistically strengthening the matrix and reducing the content of solid solution atoms.

[0035] An embodiment of the present application further provides a modified AlSiMg high thermal conductivity aluminum alloy, which is obtained by the forming method of the modified AlSiMg high thermal conductivity aluminum alloy described above.

[0036] The above technical solutions of the present application are described in detail below with reference to specific embodiments.

[0037] Example 1 A modified AlSiMg high thermal conductivity aluminum alloy is prepared by the following steps: After mixing industrial pure aluminum (99.7%), industrial pure magnesium (99.9%), Al-20Si master alloy and Al-10Yb master alloy, the mixture was smelted in a resistance melting furnace at 765°C for 30 minutes, then cooled to 750°C, stirred with an electromagnetic stirrer for 18 minutes, mixed evenly, kept at the temperature and allowed to stand for 25 minutes, and then cast to obtain an alloy ingot; The contents of the alloy ingot are as follows: Si 10.5wt%, Mg 0.4wt%, Yb 0.15wt%, total impurities 0.3wt%, and the balance Al; Remelting the alloy ingot at 870° C. for 40 minutes to obtain an aluminum alloy melt; The aluminum alloy melt is introduced into an atomizer using an alumina conduit with a mass flow rate controlled at 4.2 kg / min, and the aluminum alloy melt is impacted with 5 MPa high-speed compressed argon gas (purity ≥ 99.999%) to break the aluminum alloy melt into fine droplets to obtain alloy powder; The powder is then sieved using a cyclone separation device under a high-speed compressed argon atmosphere to obtain aluminum alloy powder for additive manufacturing. The particle size is 15μm-53μm, and more than 95% of the powder is spherical or nearly spherical. Laser powder bed melting is performed on the aluminum alloy powder for additive manufacturing by laser selective melting forming equipment. In an argon atmosphere, when the oxygen content in the forming chamber is less than 100 ppm, laser printing is started. If the oxygen content in the forming chamber is ≥100 ppm during printing, printing should be stopped immediately and argon should be reintroduced until the ambient oxygen content meets the requirement before printing is resumed. The laser power is set to 270 W, the scanning speed is 1400 mm / s, the scanning spacing is 100 μm, the powder layer thickness is 40 μm, the substrate preheating temperature is 80°C, and a high-purity argon gas flow is used for directional blowing during the forming process to avoid metal splashing and solidification of oxide inclusions to obtain a printed alloy. After printing is completed, the printed alloy is subjected to a medium-temperature annealing treatment at 300° C. for 2 hours to obtain a high thermal conductivity aluminum alloy.

[0038] According to performance tests, the tensile strength of this high thermal conductivity aluminum alloy is 462MPa (GB / T 228.1-2021) and the thermal conductivity is 190W•m -1 K -1 (Laser flash method, ASTM E1461).

[0039] Example 2 A modified AlSiMg high thermal conductivity aluminum alloy is prepared by the following steps: After mixing industrial pure aluminum (99.7%), industrial pure magnesium (99.9%), Al-20Si master alloy and Al-10Yb master alloy, the mixture was smelted in a resistance melting furnace at 750°C for 40 minutes, cooled to 740°C, stirred with an electromagnetic stirrer for 20 minutes, mixed evenly, kept at the temperature and allowed to stand for 30 minutes, and then cast to obtain an alloy ingot; The contents of the alloy ingot are as follows: Si 9wt%, Mg 0.2wt%, Yb 0.05wt%, total impurities 0.4wt%, and the balance Al; Remelting the alloy ingot at 860° C. for 50 minutes to obtain an aluminum alloy melt; The aluminum alloy melt is introduced into an atomizer using an alumina conduit with a mass flow rate controlled at 4 kg / min, and the aluminum alloy melt is impacted with 3 MPa high-speed compressed argon gas (purity ≥ 99.999%) to break the aluminum alloy melt into fine droplets to obtain alloy powder; The powder is then sieved using a cyclone separation device under a high-speed compressed argon atmosphere to obtain aluminum alloy powder for additive manufacturing. The particle size is 15μm-53μm, and more than 95% of the powder is spherical or nearly spherical. Laser powder bed melting is performed on the aluminum alloy powder for additive manufacturing by laser selective melting forming equipment. In an argon atmosphere, when the oxygen content in the forming chamber is less than 100 ppm, laser printing is started. If the oxygen content in the forming chamber is ≥100 ppm during printing, printing should be stopped immediately and argon should be reintroduced until the ambient oxygen content meets the requirement before printing is resumed. The laser power is set to 200 W, the scanning speed is 800 mm / s, the scanning spacing is 80 μm, the powder layer thickness is 20 μm, and the substrate preheating temperature is 80° C. During the forming process, high-purity argon gas flow is used for directional blowing to avoid metal splashing and solidification of oxide inclusions to obtain a printed alloy. After printing is completed, the printed alloy is subjected to a medium-temperature annealing treatment at 150° C. for 18 hours to obtain a high thermal conductivity aluminum alloy.

[0040] According to performance tests, the tensile strength of this high thermal conductivity aluminum alloy is 450MPa and the thermal conductivity is 180W•m -1 K -1 .

[0041] Example 3 A modified AlSiMg high thermal conductivity aluminum alloy is prepared by the following steps: After mixing industrial pure aluminum (99.7%), industrial pure magnesium (99.9%), Al-20Si master alloy and Al-10Yb master alloy, the mixture was melted at 780°C for 20 minutes in a resistance melting furnace, then cooled to 760°C, stirred with an electromagnetic stirrer for 15 minutes, and after uniform mixing, the mixture was kept at the temperature and allowed to stand for 20 minutes before casting to obtain an alloy ingot. The contents of the alloy ingot are as follows: Si 11wt%, Mg 0.45wt%, Yb 0.3wt%, total impurities 0.7wt%, and the balance Al; Remelting the alloy ingot at 880° C. for 30 minutes to obtain an aluminum alloy melt; The aluminum alloy melt is introduced into an atomizer using an alumina conduit with a mass flow rate controlled at 4.5 kg / min, and the aluminum alloy melt is impacted with 7 MPa high-speed compressed argon gas (purity ≥ 99.999%) to break the aluminum alloy melt into fine droplets to obtain alloy powder; The powder is then sieved using a cyclone separation device under a high-speed compressed argon atmosphere to obtain aluminum alloy powder for additive manufacturing. The particle size is 15μm-53μm, and more than 95% of the powder is spherical or nearly spherical. Laser powder bed melting is performed on the aluminum alloy powder for additive manufacturing by laser selective melting forming equipment. In an argon atmosphere, when the oxygen content in the forming chamber is less than 100 ppm, laser printing is started. If the oxygen content in the forming chamber is ≥100 ppm during printing, printing should be stopped immediately and argon should be reintroduced until the ambient oxygen content meets the requirement before printing is resumed. The laser power is set to 350 W, the scanning speed is set to 2000 mm / s, the scanning spacing is set to 120 μm, the powder layer thickness is set to 60 μm, the substrate preheating temperature is set to 80° C. During the forming process, high-purity argon gas flow is used for directional blowing to avoid metal splashing and solidification of oxide inclusions to obtain a printed alloy. After printing is completed, the printed alloy is subjected to a medium-temperature annealing treatment at 350° C. for 1 hour to obtain a high thermal conductivity aluminum alloy.

[0042] According to performance tests, the tensile strength of this high thermal conductivity aluminum alloy is 455MPa and the thermal conductivity is 182W•m -1 K -1 .

[0043] Comparative Example 1 Compared with Example 1, the raw materials do not contain Al-10Yb master alloy. The contents of the components in the alloy ingot are: Si 10.5wt%, Mg 0.4wt%, total impurities 0.3wt%, and the balance Al. The subsequent steps remain unchanged. The performance test shows that the obtained aluminum alloy has a tensile strength of 385MPa and a thermal conductivity of 158W·m -1 K -1 .

[0044] In summary, based on the small solidification temperature interval of the Al-Si binary alloy system, the solidification shrinkage of the present application is low, which can reduce the stress in the molten pool and inhibit thermal cracks, thereby endowing the aluminum alloy with good laser forming performance, solving the problem of laser powder bed fusion forming of high thermal conductivity aluminum alloy; in the additive manufacturing process with large temperature gradient and high solidification rate, Si and Mg will be dissolved into the aluminum base due to solute trapping effect, and the micro-alloying Yb element added in the present application can form nanoscale Al3(Yb, Si) phase and be coherent with the alpha-Al matrix, in the subsequent medium temperature annealing process, a large amount of Mg2Si and Si nanophase is precipitated from the aluminum matrix, at the same time, a large amount of Al3(Yb, Si) phase is also precipitated independently, the nanoscale Al3(Yb, Si) and Mg2Si / Si phase not only can synergistically strengthen the matrix, but also significantly reduce the content of solid solution atoms (especially Si atoms) in the aluminum matrix, thereby breaking through the heat conduction bottleneck caused by the scattering of solid solution atoms, achieving good mechanical properties of the aluminum alloy, and also realizing its high thermal conductivity. Compared with the Al-Si eutectic alloy without introducing Yb in the comparative example, the tensile strength and thermal conductivity of the laser additive manufacturing aluminum alloy of the present application embodiment are significantly improved, which shows that the present application can significantly reduce the solid solution Si concentration by Yb micro-alloying reconstruction of AlSi10Mg strengthening mechanism, and simultaneously improve the thermal conductivity and mechanical properties of the aluminum alloy.

[0045] The above is only an optional embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made by utilizing the content of the present application specification and drawings, or directly / indirectly applied in other related technical fields under the inventive concept of the present application is included in the patent protection scope of the present application.

Claims

1. A forming method of a modified AlSiMg high thermal conductivity aluminum alloy, characterized in that: The following steps are involved: The raw materials are mixed, smelted, and cast according to a ratio of Si content of 9wt%-11wt%, Mg content of 0.2wt%-0.45wt%, Yb content of 0.05wt%-0.3wt%, total impurities ≤0.7wt% and Al as the balance to obtain an alloy ingot; After remelting the alloy ingot, the alloy powder is prepared by gas atomization powder making process, and then sieving to obtain aluminum alloy powder for additive manufacturing; Performing laser powder bed melting on the aluminum alloy powder for additive manufacturing to obtain a printed alloy; The printed alloy is subjected to a medium-temperature annealing treatment to obtain a high thermal conductivity aluminum alloy.

2. The forming method of the modified AlSiMg high thermal conductivity aluminum alloy according to claim 1, characterized in that: In the step of mixing the raw materials, smelting and casting to obtain the alloy ingot, the raw materials include industrial pure aluminum, industrial pure magnesium, aluminum-silicon master alloy and aluminum-ytterbium master alloy.

3. The forming method of the modified AlSiMg high thermal conductivity aluminum alloy according to claim 2, characterized in that: The step of mixing the raw materials, smelting and casting to obtain an alloy ingot comprises: The raw materials are smelted at 750-780°C for 20-40 minutes, then cooled to 740-760°C, electromagnetically stirred for 15-20 minutes, mixed evenly, kept warm and allowed to stand for 20-30 minutes, and then cast to obtain alloy ingots.

4. The forming method of the modified AlSiMg high thermal conductivity aluminum alloy according to claim 1, characterized in that: The step of remelting the alloy ingot and then preparing the alloy powder through a gas atomization powder making process comprises: Remelting the alloy ingot at 860° C.-880° C. for 30 min-50 min to obtain an aluminum alloy melt; The aluminum alloy melt is discharged through an alumina conduit at a flow rate of 4 kg / min-4.5 kg / min, and high-speed compressed argon gas is used to impact the aluminum alloy melt to atomize the aluminum alloy melt to form alloy powder; The purity of the high-speed compressed argon gas is ≥99.999%, and the pressure is 3MPa-7MPa.

5. The forming method of the modified AlSiMg high thermal conductivity aluminum alloy according to claim 4, characterized in that: In the screening step, a cyclone separation powder collection method is adopted, and screening is performed under the high-speed compressed argon atmosphere.

6. The forming method of the modified AlSiMg high thermal conductivity aluminum alloy according to claim 1, characterized in that: The aluminum alloy powder for additive manufacturing has a particle size of 15 μm-53 μm and a sphericity rate of ≥95%.

7. The forming method of the modified AlSiMg high thermal conductivity aluminum alloy according to claim 1, characterized in that: In the step of performing laser powder bed melting on the aluminum alloy powder for additive manufacturing to obtain a printed alloy, the parameters of the laser powder bed melting process are set to: laser power of 200W-350W, scanning speed of 800mm / s-2000mm / s, scanning spacing of 80μm-120μm, and powder layer thickness of 20μm-60μm.

8. The forming method of the modified AlSiMg high thermal conductivity aluminum alloy according to claim 1, characterized in that: In the step of subjecting the aluminum alloy powder for additive manufacturing to laser powder bed melting to obtain a printed alloy, the laser powder bed melting process is carried out in an argon atmosphere with an oxygen content of <100 ppm, while using directional blowing of argon gas.

9. The forming method of the modified AlSiMg high thermal conductivity aluminum alloy according to claim 1, characterized in that: In the step of performing medium-temperature annealing on the printed alloy to obtain a high thermal conductivity aluminum alloy, the annealing temperature is 150° C.-350° C., and the annealing time is 1 hour-24 hours.

10. A modified AlSiMg high thermal conductivity aluminum alloy, characterized in that: The modified AlSiMg high thermal conductivity aluminum alloy is obtained by the forming method according to any one of claims 1 to 9.

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