Additively manufactured high thermal conductivity aluminum alloy and preparation method thereof

Abstract

The present invention provides an additively manufactured high thermal conductivity aluminum alloy and a preparation method thereof, wherein the alloy components are in the following proportions by mass percentage: Fe: 1‑4wt.%, Zr: 0.1‑1.2wt.%, Sr: 0.01‑0.2wt.%, and the total amount of other impurities does not exceed 0.8wt.%, with the balance being Al. The alloy is prepared by processes such as ingot melting, powder preparation, laser forming, and aging treatment. The low solubility and low diffusivity of Fe in Al are utilized to reduce the formation of solute atoms and precipitate phases. At the same time, the formation of primary Al3Zr can refine the grains and inhibit thermal cracking. The combination of the two enables the alloy to obtain more balanced mechanical properties and thermal conductivity. Compared with traditional aluminum alloys, the selective laser-melted aluminum alloy of the present invention has an extremely fine grain structure, which can realize the near-net-shape production of various complex-shaped structural parts and topologically optimized networks, and has broad application prospects in fields such as aerospace.

Description

Technical Field

[0001] The present invention relates to the field of metal additive manufacturing, and in particular to an additively manufactured high thermal conductivity aluminum alloy and a preparation method thereof. Background Art

[0002] Additive Manufacturing (AM), also known as 3D printing, is a processing method that is completely different from traditional molding processes. AM combines computer-aided design (CAD) with material molding, uses CAD software to deconstruct a two-dimensional image of a three-dimensional model, and then stacks layers to accumulate the molded components. This emerging production method has the advantages of short manufacturing cycle, high material utilization rate, and high product precision, and has good application prospects. Currently, commonly used additive manufacturing technologies include stereolithography (SLA), selective laser melting (SLM), and direct metal deposition (DMD). Among them, selective laser melting uses metal powder as raw material and laser as input energy source. It has fast processing speed, high molding accuracy, and strong complex structure molding capabilities. It is currently widely used in aerospace and other fields.

[0003] Aluminum alloy is currently a widely used alloy material with the characteristics of low density, high specific strength, good plasticity, corrosion resistance, and excellent electrical and thermal conductivity. It has an irreplaceable position in the fields of aerospace, transportation, equipment and instruments. The aluminum alloy prepared by SLM has a uniform microstructure distribution and significant fine grain strengthening. Combined with its lightweight advantage, it is gradually used in important aerospace mechanical structures such as satellite brackets and engine nacelles. However, due to problems such as the manufacturing of printing equipment, the production of alloy powders, and the regulation of process flow, the application range of aluminum alloy parts produced by domestic SLM is relatively small and has not been popularized in the field of large-scale machinery production. Imported printing equipment and metal powders have created relatively high economic costs, making it difficult to replace the traditional low-priced aluminum alloy materials.

[0004] However, the additive manufacturing production model is not suitable for traditional high-strength 2xxx and 7xxx aluminum alloys. The wide solid-liquid temperature range resulting from high solid solubility in Al-Cu and Al-Zn alloys leads to severe cracking under the rapid cooling and heating of laser processes, resulting in extremely poor component forming performance. Currently, most aluminum alloy powders used in 3D printing are near-eutectic aluminum-silicon alloys with relatively low mechanical properties. The narrow solidification temperature range of the eutectic Si phase and the excellent fluidity of the melt mitigate the tendency to hot cracking caused by high undercooling during SLM processes. For example, the AlSi10Mg alloy powder disclosed in Chinese patent CN 107716918A exhibits good formability but relatively low mechanical properties. The commonly used high-strength AlMgScZr alloy powder for additive manufacturing loses the cost advantage traditionally associated with aluminum alloys due to the high price of Sc, making it difficult to popularize in industrial production. Compared with high-strength aluminum alloys, the development and exploration of high thermal conductivity aluminum alloys for additive manufacturing is still relatively small. Studies have found that the thermal conductivity of aluminum alloys formed by SLM is generally lower than that formed by casting. This is mainly attributed to the higher supersaturation in the aluminum matrix in the deposited state. In addition, intermetallic compounds, residual stress and dislocation density are also important factors affecting thermal conductivity. Summary of the Invention

[0005] In order to solve the problems of severe hot cracking of traditional high solid solution deformed aluminum alloys produced by laser deposition molding and generally low thermal conductivity of SLM aluminum alloys, the purpose of the present invention is to propose an additively manufactured high thermal conductivity aluminum alloy and a preparation method thereof. The low solubility and low diffusivity of Fe in Al are utilized to reduce the formation of solute atoms and precipitate phases. At the same time, the formation of primary Al3Zr can refine the grains and inhibit hot cracking. The combination of the two enables the alloy to obtain more balanced mechanical properties and thermal conductivity.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides an additively manufactured high thermal conductivity aluminum alloy, wherein the weight percentages of the components in the aluminum alloy are: Fe: 1-4wt.%, Zr: 0.1-1.2wt.%, Sr: 0.01-0.2wt.%, and the total amount of other impurities does not exceed 0.8wt.%, with the balance being Al.

[0008] As an embodiment of the present invention, the weight percentages of the components in the aluminum alloy are: Fe: 1-2wt.%, Zr: 0.5-1wt.%, Sr: 0.01-0.2wt.%, and the total amount of other impurities does not exceed 0.8wt.%, with the balance being Al.

[0009] In some embodiments of the present invention, the weight percentages of the components in the aluminum alloy are: Fe: 1.2-2wt.%, Zr: 0.5-1wt.%, Sr: 0.02-0.05wt.%, and the total amount of other impurities does not exceed 0.8wt.%, with the balance being Al.

[0010] In a second aspect, the present invention provides a method for additively manufacturing a high thermal conductivity aluminum alloy, comprising the following steps:

[0011] S1. Alloy smelting: Aluminum, aluminum-iron master alloy, aluminum-zirconium master alloy and aluminum-strontium master alloy are mixed according to the proportion, smelted and cast into alloy ingots;

[0012] S2. Powder preparation: remelting the ingot obtained in S1, atomizing it, cooling and solidifying it to form metal powder, and then sieving the powder to obtain aluminum alloy powder for additive manufacturing;

[0013] S3, laser forming: performing selective laser melting and forming on the aluminum alloy powder for additive manufacturing obtained in S2 to obtain a printed alloy;

[0014] S4. Heat treatment: Anneal the printed alloy obtained in S3 and perform aging treatment to obtain an additively manufactured high thermal conductivity aluminum alloy.

[0015] As an embodiment of the present invention, in step S1, the aluminum is commercially pure aluminum.

[0016] As an embodiment of the present invention, in step S1, the smelting temperature is 750-780°C; and the ratio satisfies the weight percentage of each component in the aluminum alloy.

[0017] As an embodiment of the present invention, in step S1, after the alloy is completely melted, the alloy melt is stirred with an electromagnetic stirrer until it is fully mixed and uniformly mixed, and then kept warm and allowed to stand for 30-120 minutes; the stirring time is 20-60 minutes.

[0018] As one embodiment of the present invention, in step S2, before atomization, an alumina conduit is used to guide the melt (i.e., alloy melt) from the smelting furnace. Alumina has a high melting point and can be used to transport molten metal. Using aluminum alloy oxide also avoids the introduction of other metal elements.

[0019] As an embodiment of the present invention, in step S2, the atomization method includes: using high-speed compressed nitrogen gas with a purity of ≥99.995% to impact the molten aluminum alloy, thereby breaking the melt into fine droplets.

[0020] As one embodiment of the present invention, in step S2, the atomization pressure is 8-15 MPa. When the atomization pressure is lower than 8 MPa, the atomized droplets are prone to bag-type crushing due to the low pressure, and the formed powder is prone to forming hollow powder. When the atomization pressure is higher than 15 MPa, the atomized droplets are prone to fragmentation due to the high pressure, and the powder particle size is too small, making it unsuitable for SLM printing.

[0021] As an embodiment of the present invention, in step S2, the screening method is cyclone separation and powder collection. A cyclone separation and powder collection device is used to screen the powder under a high-purity argon atmosphere.

[0022] As an embodiment of the present invention, in step S2, more than 60% of the aluminum alloy powder for additive manufacturing prepared has a particle size range of 20-60 μm.

[0023] As an embodiment of the present invention, in step S2, more than 90% of the aluminum alloy powder for additive manufacturing prepared is spherical or pear-shaped.

[0024] As an embodiment of the present invention, in step S3, in an argon atmosphere, when the oxygen content in the molding chamber is lower than 200ppm, the selective laser melting molding process starts laser printing. The selective laser molding process is carried out in an argon atmosphere, and argon is introduced before printing begins. Laser processing is then started when the oxygen content in the molding chamber is lower than 200ppm. During the molding process, a high-purity argon gas flow is used for directional blowing to prevent metal vapor and oxide inclusions from solidifying and falling back. If the oxygen content in the molding chamber is higher than 200ppm during processing, printing should be stopped immediately and argon should be introduced again until the ambient oxygen content meets the requirements before printing is resumed.

[0025] As one embodiment of the present invention, in step S3, the laser power used in the selective laser melting process is 300-400W and the scanning speed is 1000-2400mm / s. The laser power and scanning speed jointly determine the linear input energy density. When the laser power is less than 300W or the scanning speed is greater than 2400mm / s, the input energy is insufficient to completely melt the metal powder, and unfused voids are likely to appear. When the laser power is greater than 400W or the scanning speed is less than 1000mm / s, the linear input energy density is too high, and a large amount of metal vapor escapes, which can easily cause elemental burnout and microstructure coarsening, resulting in a significant decrease in the mechanical properties of the alloy.

[0026] In some embodiments of the present invention, the selective laser melting process uses a laser power of 350-400 W and a scanning speed of 1200-1400 mm / s.

[0027] As an embodiment of the present invention, in step S3, the scanning pitch used in the selective laser melting is 0.13-0.18 mm, the layer thickness is 40-60 μm, and the substrate preheating temperature is 100-120°C.

[0028] As an embodiment of the present invention, in step S4, the annealing temperature is 270-350° C. and the time is 2-6 hours.

[0029] In one embodiment of the present invention, in step S4, the aging treatment temperature is 165-400°C for 1-24 hours. When the aging temperature is below 165°C, the alloy undergoes insignificant age hardening and fails to achieve the desired aging strengthening effect. When the aging temperature is above 400°C, the grains grow due to the excessively high temperature, thereby reducing mechanical properties.

[0030] In some embodiments of the present invention, the aging treatment is performed at a temperature of 300-400° C. and for a time of 4-24 hours.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention uses Fe and Zr as the main alloying elements. The equilibrium solubility of Fe in Al is extremely low. The low solid solubility can ensure that the thermal conductivity of the matrix will not be greatly reduced. The relatively low vapor pressure also does not have too much impact on the input energy during burnout. The stable heat input can reduce the formation of pores and microcracks. At the same time, Al and Fe can form Al 13 Fe4 precipitation phase (second phase) improves the mechanical properties of the alloy while further improving the thermal conductivity of the alloy.

[0033] (2) The Zr added in the present invention forms an Al3Zr coherent with the α-Al matrix, acting as a heterogeneous nucleation site to incubate the alloy. The Sr modifier then hinders grain growth and promotes grain refinement, thereby reducing the tendency to hot cracking (while maintaining mechanical properties). The combined action of Zr and Sr replaces the precious metal Sc, reducing the production cost of laser additive manufacturing aluminum alloys.

[0034] (3) The added elements in the present invention only include Fe, Zr, and Sr, which avoids the technical defects of greatly reducing the thermal conductivity of the aluminum alloy due to too many types of added elements resulting in a high solid solubility of the alloy and a large number of precipitated phases formed during heat treatment.

[0035] (4) This invention proposes a high-thermal-conductivity aluminum alloy suitable for selective laser melting (SLM), which exhibits good thermal conductivity while maintaining moderate mechanical properties. Compared to conventional aluminum alloys, SLM aluminum alloys have an extremely fine grain structure, enabling near-net-shape production of various complex-shaped structural parts and topologically optimized networks, and have broad application prospects in fields such as aerospace. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0037] Figure 1 The metallographic structure of the formed alloy in Example 1;

[0038] Figure 2 is the grain structure of the formed alloy in Example 1;

[0039] Figure 3 The microstructure of the formed alloy containing microcracks in Comparative Example 1;

[0040] Figure 4 This is a metallographic image of the formed alloy containing pores in Comparative Example 3. DETAILED DESCRIPTION

[0041] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The following examples are implemented under the premise of the technical solution of the present invention, provide detailed implementation methods and specific operating procedures, and will help those skilled in the art to further understand the present invention. It should be pointed out that the scope of protection of the present invention is not limited to the following embodiments, and a number of adjustments and improvements made under the premise of the concept of the present invention all fall within the scope of protection of the present invention.

[0042] Example 1

[0043] Chemical composition and element content of the aluminum alloy: Al-1.5Fe-1Zr-0.02Sr (wt.%).

[0044] S1: Alloy smelting: Commercial pure aluminum, aluminum-iron master alloy, aluminum-zirconium master alloy, and aluminum-strontium master alloy are placed in a 750°C melting furnace according to the proportions. The mixture is stirred with an electromagnetic stirrer for 30 minutes until the melt is evenly distributed. The mixture is then kept at this temperature and allowed to stand for 90 minutes before being cast into aluminum alloy ingots.

[0045] S2: Powder preparation: The ingot obtained in S1 is remelted, and the melt is discharged through an alumina tube. High-speed compressed nitrogen is used to impact the molten aluminum-magnesium-silicon alloy and atomize it to break it into fine droplets. The atomization pressure is 12 MPa, and the purity of the high-pressure nitrogen is ≥99.995%. The metal powder is cooled and solidified to form a metal powder. The powder is sieved by a cyclone separation powder collection device under a high-purity argon atmosphere to obtain Al-1.5Fe-1Zr-0.02Sr (wt.%) powder for additive manufacturing. More than 95% of the obtained powder is spherical or pear-shaped, and more than 60% of the powder particle size is between 20-53μm.

[0046] S3: Laser forming: In an argon atmosphere, when the oxygen content in the forming chamber is lower than 200 ppm, the powder obtained in S2 is subjected to a selective laser melting forming process with a laser power of 370 W, a scanning speed of 1400 mm / s, a scanning pitch of 0.13 mm, a layer thickness of 60 μm, and a substrate preheating temperature of 100°C to obtain a printed alloy.

[0047] S4: Heat treatment: The printed alloy obtained in S3 was first subjected to stress relief annealing at 300°C for 2 h, and then subjected to aging treatment at 400°C for 4 h.

[0048] The density ρ of the alloy was measured by Archimedes method and the density was calculated by comparing it with the theoretical density. The thermal diffusion coefficient α of the alloy was measured by LFA 467 laser thermal conductivity meter and the specific heat C was tested by comparison method. p , the thermal conductivity λ of the alloy is calculated using the formula λ=ρ×α×C p The room temperature tensile properties of the alloy were measured according to GB / T 228.1-2021.

[0049] Through testing, the alloy of this embodiment has excellent forming performance, the sample density is 99.7%, and the metallographic structure of the printed alloy is as follows: Figure 1 As shown, the grain structure is Figure 2 shown; among them, Figure 2 The alloy has a very fine grain structure. The thermal conductivity of the annealed sample is 122Wm -1 k -1 , tensile strength is 202MPa, yield strength is 128MPa, elongation is 25.1%; after aging treatment, the thermal conductivity of the sample is 187Wm -1 k -1 , the tensile strength is 344MPa, the yield strength is 309MPa, and the elongation is 13.6%.

[0050] Example 2

[0051] Chemical composition and element content of the aluminum alloy: Al-2Fe-0.8Zr-0.03Sr (wt.%).

[0052] S1: Alloy smelting: Commercial pure aluminum, aluminum-magnesium master alloy, aluminum-silicon master alloy, aluminum-manganese master alloy, aluminum-titanium master alloy, aluminum-zirconium master alloy and aluminum-strontium master alloy are placed in a smelting furnace at 770°C according to the proportions. The alloys are stirred with an electromagnetic stirrer for 30 minutes until the melt is evenly distributed. The alloys are then kept at this temperature and allowed to stand for 120 minutes before being cast into aluminum-magnesium-silicon alloy ingots.

[0053] S2: Powder preparation: The ingot obtained in S1 is remelted, and the melt is discharged through an alumina tube. High-speed compressed nitrogen is used to impact the molten aluminum-magnesium-silicon alloy to break it into fine droplets. The atomization pressure is 15 MPa, and the purity of the high-pressure nitrogen is ≥99.995%. The metal powder is cooled and solidified to form a metal powder. The powder is sieved by a cyclone separation powder collecting device under a high-purity argon atmosphere to obtain Al-2Fe-0.8Zr-0.03Sr (wt.%) powder for additive manufacturing. More than 90% of the obtained powder is spherical or pear-shaped, and more than 60% of the powder particle size is between 20-60μm.

[0054] S3: Laser forming: In an argon atmosphere, when the oxygen content in the forming chamber is lower than 200 ppm, the powder obtained in S2 is subjected to a selective laser melting forming process with a laser power of 350 W, a scanning speed of 1300 mm / s, a scanning pitch of 0.17 mm, a layer thickness of 40 μm, and a substrate preheating temperature of 120°C to obtain a printed alloy.

[0055] S4: Heat treatment: The printed alloy obtained in S3 was first subjected to stress relief annealing at 280°C for 4 h, and then subjected to aging treatment at a temperature of 350°C for 8 h.

[0056] Through testing (testing method is the same as Example 1), the alloy of this embodiment has excellent forming performance, and the density of the sample is 98.9%. The thermal conductivity of the annealed sample is 113Wm -1 k -1 , tensile strength is 257MPa, yield strength is 136MPa, elongation is 22.3%; after aging treatment, the thermal conductivity of the sample is 176Wm -1 k -1 , the tensile strength is 363MPa, the yield strength is 311MPa, and the elongation is 11.9%.

[0057] Example 3

[0058] Chemical composition and element content of the aluminum alloy: Al-1.2Fe-0.5Zr-0.05Sr (wt.%).

[0059] S1: Alloy smelting: Commercial pure aluminum, aluminum-iron master alloy, aluminum-zirconium master alloy, and aluminum-strontium master alloy are placed in a 760°C melting furnace according to the proportions. The mixture is stirred with an electromagnetic stirrer for 30 minutes until the melt is evenly distributed. The mixture is then kept at this temperature and allowed to stand for 100 minutes before being cast into aluminum-magnesium-silicon alloy ingots.

[0060] S2: Powder preparation: The ingot obtained in S1 is remelted, and the melt is discharged through an alumina tube. The molten aluminum-magnesium-silicon alloy is impacted with high-speed compressed nitrogen to break it into fine droplets. The atomization pressure is 10 MPa, and the purity of the high-pressure nitrogen is ≥99.995%. The metal powder is cooled and solidified to form a metal powder. The powder is sieved by a cyclone separation powder collecting device under a high-purity argon atmosphere to obtain Al-1.2Fe-0.5Zr-0.05Sr (wt.%) powder for additive manufacturing. More than 90% of the obtained powder is spherical, and more than 60% of the powder particle size is between 20-50μm.

[0061] S3: Laser forming: In an argon atmosphere, when the oxygen content in the forming chamber is lower than 200 ppm, the powder obtained in S2 is subjected to a selective laser melting forming process with a laser power of 400 W, a scanning speed of 1200 mm / s, a scanning pitch of 0.15 mm, a layer thickness of 50 μm, and a substrate preheating temperature of 140°C to obtain a printed alloy.

[0062] S4: Heat treatment: The printed alloy obtained in S3 was first subjected to stress relief annealing at 350°C for 2h, and then subjected to aging treatment at 300°C for 24h.

[0063] Through testing (testing method is the same as Example 1), the alloy of this embodiment has excellent forming performance, and the density of the sample is 98.5%. The thermal conductivity of the annealed sample is 132Wm -1 k -1 , tensile strength is 209MPa, yield strength is 119MPa, elongation is 26.5%; after aging treatment, the thermal conductivity of the sample is 190Wm -1 k -1 , the tensile strength is 354MPa, the yield strength is 301MPa, and the elongation is 10.7%.

[0064] Comparative Example 1

[0065] Chemical composition and element content of the aluminum alloy: Al-1.5Fe-0.02Sr (wt.%).

[0066] Other experimental conditions are the same as those in Example 1.

[0067] Through testing (testing method is the same as that of Example 1), the forming performance of the comparative alloy is general, the density of the sample is 95.3%, but there are some micro cracks in the matrix, such as Figure 3As shown. The thermal conductivity of the annealed sample is 134Wm -1 k -1 , tensile strength is 271MPa, yield strength is 226MPa, elongation is 20.4%; after aging treatment, the thermal conductivity of the sample is 182Wm -1 k -1 , the tensile strength is 298MPa, the yield strength is 249MPa, and the elongation is 7.9%.

[0068] Comparative Example 2

[0069] The alloy composition and production process of this comparative example are basically the same as those of Example 1, with only the aging treatment parameters being changed: aging temperature of 500° C. and time of 12 h.

[0070] Through testing (testing method is the same as Example 1), the comparative alloy has excellent forming performance and the sample density is 99.6%. The thermal conductivity of the annealed sample is 118Wm -1 k -1 , tensile strength is 196MPa, yield strength is 134MPa, elongation is 24.8%; after aging treatment, the thermal conductivity of the sample is 162Wm -1 k -1 , the tensile strength is 315MPa, the yield strength is 269MPa, and the elongation is 14.1%.

[0071] Comparative Example 3

[0072] The alloy composition and production process described in this comparative example are basically the same as those in Example 2, with only some additive manufacturing process parameters changed: the laser power is 450 W, and the scanning speed is 800 mm / s.

[0073] Through testing (testing method is the same as that of Example 1), the density of the comparative alloy sample is 92.3%. Due to the high power and low scanning speed, the alloy has multiple element burnout and pores, such as Figure 4 As shown. The thermal conductivity of the annealed sample is 94Wm -1 k -1 , tensile strength is 188MPa, yield strength is 113MPa, elongation is 16.3%; after aging treatment, the thermal conductivity of the sample is 145Wm -1 k -1 , the tensile strength is 266MPa, the yield strength is 197MPa, and the elongation is 6.4%.

[0074] Comparative Example 4

[0075] Chemical composition and element content of aluminum alloy: Al-1.5Fe-1Zr (wt.%).

[0076] Other experimental conditions are the same as those in Example 1.

[0077] Through testing (testing method is the same as Example 1), the density of the comparative alloy sample is 98.1%. The thermal conductivity of the annealed sample is 125Wm -1 k -1 , tensile strength is 183MPa, yield strength is 108MPa, elongation is 22.1%; after aging treatment, the thermal conductivity of the sample is 179Wm -1 k -1 , the tensile strength is 329MPa, the yield strength is 292MPa, and the elongation is 11.3%.

[0078] Comparative Example 5

[0079] Chemical composition and element content of the aluminum alloy: Al-1Fe-0.5Mg-0.1Mn-0.5Si-0.5Zr-0.01Sr (wt.%).

[0080] Other experimental conditions are the same as those in Example 1.

[0081] Through testing (testing method is the same as Example 1), the density of the comparative alloy sample is 97.8%. The thermal conductivity of the annealed sample is 102Wm -1 k -1 , tensile strength is 224MPa, yield strength is 158MPa, elongation is 29.3%; after aging treatment, the thermal conductivity of the sample is 144Wm -1 k -1 , the tensile strength is 359MPa, the yield strength is 301MPa, and the elongation is 14.5%.

[0082] Comparative Example 6

[0083] Chemical composition and element content of the aluminum alloy: Al-1Zr-0.02Sr (wt.%).

[0084] Other experimental conditions are the same as those in Example 1.

[0085] Through testing (testing method is the same as Example 1), the density of the comparative alloy sample is 98.6%. The thermal conductivity of the annealed sample is 161Wm -1 k -1 , tensile strength is 154MPa, yield strength is 93MPa, elongation is 30.1%; after aging treatment, the thermal conductivity of the sample is 195Wm -1 k -1 , the tensile strength is 217MPa, the yield strength is 141MPa, and the elongation is 22.9%.

[0086] In summary, according to Comparative Examples 1, 4 and Example 1, the Zr added in the present invention can form Al3Zr with Al and is coherent with the α-Al matrix, and can play a role in incubation as a heterogeneous nucleation site, and then the Sr modification effect hinders grain growth and promotes grain refinement, thereby reducing the tendency of hot cracking, ensuring mechanical properties, and improving thermal conductivity; Comparative Example 6 and Example 1, the present invention can form Al3Zr with Al by adding Fe. 13 Fe4 precipitation phase (second phase) leads to a decrease in Fe as a solid solution atom in the alloy, thereby improving the mechanical properties of the alloy; in Comparative Example 5 and Example 1, the present invention only adds three elements, Fe, Zr, and Sr, to avoid the technical defects of greatly reducing the thermal conductivity of the aluminum alloy due to too many types of added elements and a large number of precipitated phases formed during heat treatment; in Comparative Example 2 and Example 1, the aging temperature of Comparative Example 2 is higher than 400°C, and the grains grow due to the high temperature, thereby reducing the mechanical properties; in Comparative Example 3 and Example 1, the laser power of Comparative Example 3 is higher than 400W and the scanning speed is lower than 1000mm / s, the line input energy density is too high, and a large amount of metal vapor escapes, which easily causes element burnout and tissue coarsening, resulting in a significant decrease in the mechanical properties of the alloy.

[0087] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. An additively manufactured high thermal conductivity aluminum alloy, characterized in that: The weight percentages of the components in the aluminum alloy are as follows: Fe: 1.2-1.5 wt.%, Zr: 0.5-1 wt.%, Sr: 0.01-0.2 wt.%, the total amount of other impurities does not exceed 0.8 wt.%, and the balance is Al; The preparation method of the aluminum alloy comprises the following steps: S1. Alloy smelting: Aluminum, aluminum-iron master alloy, aluminum-zirconium master alloy and aluminum-strontium master alloy are mixed according to the proportion, smelted and cast into alloy ingots; S2. Powder preparation: remelting the ingot obtained in S1, atomizing it, cooling and solidifying it to form metal powder, and then sieving the powder to obtain aluminum alloy powder for additive manufacturing; The atomization pressure is 8-15MPa; S3, laser forming: performing selective laser melting and forming on the aluminum alloy powder for additive manufacturing obtained in S2 to obtain a printed alloy; S4, heat treatment: annealing the printed alloy obtained in S3, and performing aging treatment to obtain an additively manufactured high thermal conductivity aluminum alloy; The aging treatment is carried out at a temperature of 165-400° C. and for a time of 1-24 hours.

2. The preparation method according to claim 1, characterized in that In step S2, the screening method is cyclone separation to collect powder.

3. The preparation method according to claim 1, characterized in that In step S3, the oxygen content in the molding chamber during the selective laser melting molding is lower than 200 ppm.

4. The preparation method according to claim 1, characterized in that In step S3, the laser power used in the selective laser melting is 300-400W and the scanning speed is 1000-2400mm / s.

5. The preparation method according to claim 1, characterized in that In step S3, the scanning pitch used in the selective laser melting is 0.13-0.18 mm, the layer thickness is 40-60 μm, and the substrate preheating temperature is 100-120°C.

6. The preparation method according to claim 1, characterized in that In step S4, the annealing temperature is 270-350° C. and the time is 2-6 hours.

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