High specific strength 3D printed aluminum alloy and method of making same

Abstract

The present application relates to a kind of high specific strength 3D printing aluminum alloy and its preparation method, by adding Mg and Li element not only can reduce the density of aluminum alloy, can also with Mn, Sc, Zr, Ti, Er and Yb element together play the role of strengthening, to improve the specific strength of aluminum alloy.In addition, the present application first prepares near-spherical aluminum alloy powder with low impurity content by gas atomization method, then utilizes the technical advantage that 3D printing rapid solidification can significantly expand the solute element solid solution limit, then cooperates with the advantages of double-stage aging heat treatment of dry ice cooling and combines multi-element microalloying, inhibits the coarsening of incoherent precipitate phase, realizes the step-by-step regulation of nanoscale coherent precipitate phase and submicron incoherent strengthening phase composition and organization, and improves the specific strength of aluminum alloy.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy additive manufacturing, specifically to a high specific strength 3D printed aluminum alloy and its preparation method. Background Technology

[0002] In the aerospace, marine, and rail transportation sectors, lightweighting has significant economic implications, necessitating the continuous advancement of integrated molding and topology optimization technologies. This makes the fabrication of components using traditional processes extremely challenging, while simultaneously requiring further improvements in the overall performance of in-service materials. Additive manufacturing (3D printing), hailed as a "rapid prototyping" technology, leverages the controllable material properties and point-by-point deposition to meet the requirements for "near-net-shape" forming of complex structures such as lattices, thin walls, and hollow interiors.

[0003] Aluminum alloys, with their abundant reserves and low density, are a highly sought-after lightweight material. Currently, the aluminum alloy systems researched in additive manufacturing and their main characteristics are as follows: Al-Si alloys offer good formability but low tensile strength; Al-Cu and Al-Zn alloys, as traditional high-strength aluminum alloys, have poor formability and a strong tendency to crack; and Al-Mn alloys with Sc and Zr microalloying can achieve strengths exceeding 500 MPa after heat treatment, meeting the requirements for high strength applications. However, in additive manufacturing, where high relative strength is required, these aluminum alloy systems are insufficient to meet the demands.

[0004] Therefore, there is an urgent need to develop a high specific strength aluminum alloy material for additive manufacturing. Summary of the Invention

[0005] In view of the problems existing in the background art, the present invention provides a high specific strength 3D printed aluminum alloy and its preparation method. The 3D printed aluminum alloy has good mechanical properties, low density, and high specific strength.

[0006] In a first aspect, the present invention provides a high specific strength 3D printing aluminum alloy comprising the following elements by weight percentage: Mg 3.5-10.0%, Li 0.2-3.5%, Mn 0.5-4.0%, Sc 0.2-1.5%, Zr 0.05-2.0%, Ti 0.02-1.5%, Er 0.2-2.5%, Yb 0.01-3.0%, with the remainder being Al and unavoidable impurities.

[0007] This invention not only reduces the density of aluminum alloys by adding Mg and Li elements, but also works with Mn, Sc, Zr, Ti, Er and Yb elements to strengthen them, thereby increasing the specific strength of the aluminum alloys.

[0008] In some embodiments, the weight percentage of Mg may be 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0009] In some embodiments, the weight percentage of Li may be 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, or 3.5%.

[0010] In some embodiments, the weight percentage of Mn may be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, or 4%.

[0011] In some embodiments, the weight percentage of Sc may be 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, or 1.5%.

[0012] In some embodiments, the weight percentage of Zr may be 0.05%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, or 2.0%.

[0013] In some embodiments, the weight percentage of Ti may be 0.02%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, or 1.5%.

[0014] In some embodiments, the weight percentage of Er may be 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, or 2.5%.

[0015] In some embodiments, the weight percentage of Yb may be 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.5%, 1.0%, 1.5%, 2%, 2.5%, or 3%.

[0016] In some embodiments, the high specific strength 3D printed aluminum alloy comprises the following elements by weight percentage: Mg 3.5-9.0%, Li 0.4-2.8%, Mn 0.5-4%, Sc 0.2-1.1%, Zr 0.15-1.6%, Ti 0.1-1.2%, Er 0.3-2.2%, Yb 0.05-1.8%, with the remainder being Al and unavoidable impurities.

[0017] In some embodiments, the high specific strength 3D printed aluminum alloy comprises:

[0018] Nanoscale Al3X precipitates, wherein X is one or more of Sc, Zr, Ti, Er, and Yb, and the Al3X precipitates are dispersedly distributed in an Al matrix; and

[0019] Submicron-sized Al6Mn and ErMn2 precipitates are discontinuously distributed at grain boundaries or intragranular dislocations.

[0020] Al3X precipitates, Al6Mn precipitates, and ErMn2 precipitates are beneficial for improving the mechanical properties of aluminum alloys, such as tensile strength.

[0021] In some embodiments, the high specific strength 3D printed aluminum alloy further comprises, by weight percentage: 0.001-0.004% beryllium. The addition of beryllium helps reduce magnesium burn-off.

[0022] In some specific embodiments, the weight percentage of beryllium may be 0.001%, 0.002%, 0.003%, or 0.004%.

[0023] In some embodiments, the specific strength of the high-specific-strength 3D-printed aluminum alloy can be above 195 kN·m / kg.

[0024] In some embodiments, the high specific strength 3D printed aluminum alloy has a tensile strength of over 520 MPa and a yield strength of over 490 MPa.

[0025] The high specific strength 3D printed aluminum alloy of the present invention can be used in aerospace, shipbuilding and rail transportation fields.

[0026] Secondly, the present invention provides a method for preparing the high specific strength 3D printed aluminum alloy, comprising the following steps:

[0027] The elements are mixed in proportion and then successively smelted, atomized into powder, 3D printed and heat treated to obtain the high specific strength 3D printed aluminum alloy.

[0028] The heat treatment includes: holding the temperature under a protective atmosphere, cooling with dry ice, and then holding the temperature again.

[0029] This invention first prepares near-spherical aluminum alloy powder with low impurity content through gas atomization. Then, it leverages the technological advantage of 3D printing's rapid solidification, which significantly expands the solid solution limit of solute elements. Subsequently, it combines a two-stage aging heat treatment using dry ice cooling with the advantages of multi-element microalloying to suppress the coarsening of incoherent precipitates. This achieves stepwise control over the composition and microstructure of nanoscale coherent precipitates and submicron-scale incoherent strengthening phases, thereby improving the specific strength of the aluminum alloy.

[0030] In some embodiments, the melting temperature can be 700-800°C, for example 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, or 800°C. The melting time can be 5-8 minutes. The protective gas during melting is a mixture of argon and chlorine. Preferably, the volume ratio of argon to chlorine can be (95-99):(1-5), for example 95:5, 96:4, 97:3, 98:2, or 99:1. The melting can be carried out in a medium-frequency induction furnace. Using a mixture of argon and chlorine for protection, the furnace is heated to 800-850°C, then the power of the medium-frequency induction furnace is reduced, and the temperature is controlled at 700-800°C and held for 5-8 minutes.

[0031] In some embodiments, mixing the elements in proportion includes: using pure aluminum ingots, pure magnesium ingots, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloys as raw materials, mixing them according to the alloy composition, and placing them in a crucible of a medium-frequency induction furnace in a certain manner. The placement method is as follows: grooves are milled into a portion of the pure aluminum ingots, pure magnesium ingots and lithium aluminum master alloys are placed in the grooves, then the pure aluminum ingots containing pure magnesium ingots and lithium aluminum master alloys are placed at the bottom of the crucible, then another portion of pure aluminum ingots is placed in the center of the crucible, and the lithium aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloys are evenly placed around the pure aluminum ingots. This avoids the burning loss of lithium and magnesium elements.

[0032] In some embodiments, the heat treatment includes: holding at 250-350°C for 2-8 hours under the protective atmosphere, cooling with dry ice, and then holding at 350-425°C for 0.5-3 hours. This invention utilizes a two-stage aging heat treatment with dry ice cooling, which is beneficial for suppressing the coarsening of incoherent precipitates. In some specific embodiments, the heat treatment includes: holding at 300-350°C for 4-6 hours under the protective atmosphere, cooling with dry ice, and then holding at 375-390°C for 1.5-3 hours.

[0033] In some embodiments, the protective atmosphere is nitrogen.

[0034] In some embodiments, the mixture is kept at 350-425°C for 0.5-3 hours and then cooled with dry ice. Rapid cooling with dry ice helps to suppress the coarsening of the incoherent precipitates.

[0035] In some embodiments, the atomization pressure can be 2-7 MPa, for example, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa or 7 MPa. The atomization medium can be argon gas.

[0036] In some embodiments, after atomization, the resulting powder is sieved. The sieved powder is then used for 3D printing.

[0037] In some embodiments, the 3D printing can be performed using a selective laser melting device.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1. This invention provides a high-specific-strength 3D-printable aluminum alloy. The density of the aluminum alloy is reduced by adding Mg and Li elements; the coarsening of incoherent precipitates is suppressed by adding Mn, Sc, Zr, Ti, Er, and Yb elements, thereby improving the mechanical properties of the aluminum alloy and thus increasing its specific strength. The aluminum alloy of this invention can be used in aerospace, shipbuilding, and rail transportation fields.

[0040] 2. This invention also provides a method for preparing the high specific strength 3D printed aluminum alloy. First, near-spherical aluminum alloy powder with low impurity content is prepared by gas atomization. Then, the technical advantage of rapid solidification in 3D printing can significantly expand the solid solution limit of solute elements. Subsequently, combined with the advantages of dual-stage aging heat treatment using dry ice cooling and multi-element microalloying, the coarsening of incoherent precipitates is suppressed, and the composition and structure of nanoscale coherent precipitates and submicron-scale incoherent strengthening phases are controlled stepwise, thereby improving the specific strength of the aluminum alloy. Attached Figure Description

[0041] Figure 1 The image shows the scanning electron microscope (SEM) morphology of the aluminum alloy powder prepared in Example 1.

[0042] Figure 2 The images show the non-coherent precipitated phase (a) and its energy dispersive spectroscopy (EDS) analysis (b, c) of Example 1.

[0043] Figure 3 Scanning electron microscope (SEM) images of the aluminum alloy prepared in Example 2, perpendicular to the forming direction (a) and along the forming direction (b);

[0044] Figure 4 Transmission electron microscopy (TEM) images of the coherent precipitate (a) and the incoherent precipitate (b) of the aluminum alloy prepared in Example 2;

[0045] Figure 5 The image shows the XRD pattern of the aluminum alloy prepared in Example 2. Detailed Implementation

[0046] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that these embodiments are provided to enable a more thorough understanding of this disclosure and to fully convey the scope of this disclosure to those skilled in the art. After reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0047] Example 1

[0048] This embodiment provides a high specific strength 3D printed aluminum alloy, which is composed of the following components by weight percentage: Mg 6.0wt.%, Li 0.6wt.%, Mn 0.8wt.%, Sc 0.9wt.%, Zr 0.5wt.%, Ti 0.2wt.%, Er 0.3wt.%, Yb 0.05%, with the remainder being Al and unavoidable impurities.

[0049] The above-mentioned method for preparing high-strength 3D printed aluminum alloy includes the following steps:

[0050] (1) Using pure aluminum, pure magnesium, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy as raw materials, a groove is milled out of an aluminum ingot, pure magnesium and lithium aluminum master alloy are placed in the groove and pressed at the bottom of the crucible, a large piece of pure aluminum is placed in the middle of the crucible, and aluminum manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy are evenly placed around the large piece of aluminum ingot, while 0.002 wt.% aluminum beryllium alloy is added at the same time.

[0051] (2) Use a mixture of argon and chlorine (volume ratio 98:2) for protection. After the furnace is heated to 820℃, reduce the power of the medium frequency furnace and keep the temperature at 750℃ for 6 minutes.

[0052] (3) The above melt was poured into an intermediate ladle, and argon gas was selected as the atomizing medium. The pressure was controlled at 4 MPa for atomization. After sieving, aluminum alloy powder was obtained, and its scanning electron microscope morphology is shown in the figure. Figure 1 As shown;

[0053] (4) Aluminum alloys are formed using selective laser melting equipment;

[0054] (5) The 3D-printed aluminum alloy was heat-treated using a muffle furnace at 300℃ for 6 hours, followed by dry ice cooling and then holding at 380℃ for 2 hours. Nitrogen protection was required throughout the process. The resulting non-coherent precipitates and their energy dispersive spectroscopy (EDS) analysis results are shown below. Figure 2 As shown.

[0055] Example 2

[0056] This embodiment provides a high specific strength 3D printed aluminum alloy, which is composed of the following components by weight percentage: Mg 4.5wt.%, Li 0.4wt.%, Mn 1.2wt.%, Sc 0.7wt.%, Zr 0.4wt.%, Ti 0.2wt.%, Er 0.3wt.%, Yb 0.08%, with the remainder being Al and unavoidable impurities.

[0057] The above-mentioned method for preparing high-strength 3D printed aluminum alloy includes the following steps:

[0058] (1) Using pure aluminum, pure magnesium, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy as raw materials, a groove is milled out of an aluminum ingot, pure magnesium and lithium aluminum master alloy are placed in the groove and pressed at the bottom of the crucible, a large piece of pure aluminum is placed in the middle of the crucible, and aluminum manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy are evenly placed around the large piece of aluminum ingot, while 0.003 wt.% aluminum beryllium alloy is added at the same time.

[0059] (2) Use a mixture of argon and chlorine (volume ratio 97:3) for protection. After the furnace is heated to 830℃, reduce the power of the medium frequency furnace and keep the temperature at 740℃ for 5 minutes.

[0060] (3) The above melt is poured into an intermediate ladle, argon is selected as the atomizing medium, the pressure is controlled at 5MPa for atomization, and then sieved.

[0061] (4) Aluminum alloys are formed using selective laser melting equipment;

[0062] (5) The 3D-printed aluminum alloy was heat-treated using a muffle furnace at 310℃ for 6 hours, followed by dry ice cooling and then holding at 390℃ for 1.5 hours. Nitrogen protection was required throughout the process. The final scanning electron microscope (SEM) images of the 3D-printed aluminum alloy perpendicular to the forming direction (a) and along the forming direction (b) are shown below. Figure 3 As shown. Transmission electron microscopy (TEM) images of the coherent and incoherent precipitates are shown below. Figure 4 As shown. Its XRD pattern is as follows. Figure 5 As shown.

[0063] Example 3

[0064] This embodiment provides a high specific strength 3D printed aluminum alloy, which is composed of the following components by weight percentage: Mg 5.0wt.%, Li 0.8wt.%, Mn 0.7wt.%, Sc 0.5wt.%, Zr 0.6wt.%, Ti 0.35wt.%, Er 0.4wt.%, Yb 0.1%, with the remainder being Al and unavoidable impurities.

[0065] The above-mentioned method for preparing high-strength 3D printed aluminum alloy includes the following steps:

[0066] (1) Using pure aluminum, pure magnesium, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy as raw materials, a groove is milled out of an aluminum ingot, pure magnesium and lithium aluminum master alloy are placed in the groove and pressed at the bottom of the crucible, a large piece of pure aluminum is placed in the middle of the crucible, and aluminum manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy are evenly placed around the large piece of aluminum ingot, while 0.002 wt.% aluminum beryllium alloy is added at the same time.

[0067] (2) Use a mixture of argon and chlorine (volume ratio 97.5:2.5) for protection. After the furnace is heated to 810℃, reduce the power of the medium frequency furnace and keep the temperature at 760℃ for 5 minutes.

[0068] (3) The above melt is poured into an intermediate ladle, argon is selected as the atomizing medium, and the pressure is controlled at 4.5MPa for atomization and sieving;

[0069] (4) Aluminum alloys are formed using selective laser melting equipment;

[0070] (5) Heat treatment of 3D printed aluminum alloy: the process is to hold at 330℃ in a muffle furnace for 4 hours, cool with dry ice, and then place in the furnace at 375℃ for 3 hours. Nitrogen protection is required throughout the process.

[0071] Example 4

[0072] This embodiment provides a high specific strength 3D printed aluminum alloy, which is composed of the following components by weight percentage: Mg 5.5wt.%, Li 0.7wt.%, Mn 0.5wt.%, Sc 0.6wt.%, Zr 0.65wt.%, Ti 0.4wt.%, Er 0.45wt.%, Yb 0.15%, with the remainder being Al and unavoidable impurities.

[0073] The above-mentioned method for preparing high-strength 3D printed aluminum alloy includes the following steps:

[0074] (1) Using pure aluminum, pure magnesium, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy as raw materials, mill a groove into an aluminum ingot, place pure magnesium and lithium aluminum master alloy in the groove and press it at the bottom of the crucible, place a large piece of pure aluminum in the middle of the crucible, and evenly place aluminum manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy around the large piece of aluminum ingot, while adding 0.001 wt.% aluminum beryllium alloy.

[0075] (2) Use a mixture of argon and chlorine (volume ratio 96:4) for protection. After the furnace is heated to 825℃, reduce the power of the medium frequency furnace and keep the temperature at 750℃ for 7 minutes.

[0076] (3) The above melt is poured into an intermediate ladle, argon is selected as the atomizing medium, the pressure is controlled at 6MPa for atomization, and then sieved.

[0077] (4) Aluminum alloys are formed using selective laser melting equipment;

[0078] (5) Heat treatment of 3D printed aluminum alloy: the process is to hold at 350℃ in a muffle furnace for 4 hours, cool with dry ice, and then place in the furnace at 380℃ for 2 hours. Nitrogen protection is required throughout the process.

[0079] Example 5

[0080] This embodiment provides a high specific strength 3D printed aluminum alloy, which is composed of the following components by weight percentage: Mg 9wt.%, Li 0.5wt.%, Mn 1.2wt.%, Sc 0.2wt.%, Zr 1.6wt.%, Ti 0.1wt.%, Er 2.2wt.%, Yb 0.1%, with the remainder being Al and unavoidable impurities.

[0081] The above-mentioned method for preparing high-strength 3D printed aluminum alloy includes the following steps:

[0082] (1) Using pure aluminum, pure magnesium, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy as raw materials, mill a groove into an aluminum ingot, place pure magnesium and lithium aluminum master alloy in the groove and press it at the bottom of the crucible, place a large piece of pure aluminum in the middle of the crucible, and evenly place aluminum manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy around the large piece of aluminum ingot, while adding 0.001 wt.% aluminum beryllium alloy.

[0083] (2) Use a mixture of argon and chlorine (volume ratio 97:3) for protection. After the furnace is heated to 825℃, reduce the power of the medium frequency furnace and keep the temperature at 750℃ for 7 minutes.

[0084] (3) The above melt is poured into an intermediate ladle, argon is selected as the atomizing medium, the pressure is controlled at 6MPa for atomization, and then sieved.

[0085] (4) Aluminum alloys are formed using selective laser melting equipment;

[0086] (5) Heat treatment of 3D printed aluminum alloy: the process is to hold at 330℃ in a muffle furnace for 3 hours, cool with dry ice, and then place it in the furnace at 370℃ for 3 hours. Nitrogen protection is required throughout the process.

[0087] Example 6

[0088] This embodiment provides a high specific strength 3D printed aluminum alloy, which is composed of the following components by weight percentage: Mg 3.5wt.%, Li 2.8wt.%, Mn 4.0wt.%, Sc 1.1wt.%, Zr 0.15wt.%, Ti 1.2wt.%, Er 0.7wt.%, Yb 1.8%, with the remainder being Al and unavoidable impurities.

[0089] The above-mentioned method for preparing high-strength 3D printed aluminum alloy includes the following steps:

[0090] (1) Using pure aluminum, pure magnesium, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy as raw materials, mill a groove into an aluminum ingot, place pure magnesium and lithium aluminum master alloy in the groove and press it at the bottom of the crucible, place a large piece of pure aluminum in the middle of the crucible, and evenly place aluminum manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy around the large piece of aluminum ingot, while adding 0.001 wt.% aluminum beryllium alloy.

[0091] (2) Use a mixture of argon and chlorine (volume ratio 99:1) for protection. After the furnace is heated to 825℃, reduce the power of the medium frequency furnace and keep the temperature at 750℃ for 7 minutes.

[0092] (3) The above melt is poured into an intermediate ladle, argon is selected as the atomizing medium, the pressure is controlled at 6MPa for atomization, and then sieved.

[0093] (4) Aluminum alloys are formed using selective laser melting equipment;

[0094] (5) Heat treatment of 3D printed aluminum alloy: the process is to hold at 340℃ in a muffle furnace for 4 hours, cool with dry ice, and then place it in the furnace at 375℃ for 3 hours. Nitrogen protection is required throughout the process.

[0095] Comparative Example 1

[0096] This embodiment provides a 3D printed aluminum alloy, which is composed of the following components by weight percentage: Mn 0.8wt.%, Sc 0.9wt.%, Zr 0.5wt.%, Ti 0.2wt.%, Er 0.3wt.%, Yb 0.05%, with the remainder being Al and unavoidable impurities.

[0097] The above-mentioned method for preparing 3D printed aluminum alloys includes the following steps:

[0098] (1) Using pure aluminum, pure magnesium, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy as raw materials, a groove is milled out of an aluminum ingot, pure magnesium and lithium aluminum master alloy are placed in the groove and pressed at the bottom of the crucible, a large piece of pure aluminum is placed in the middle of the crucible, and aluminum manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy are evenly placed around the large piece of aluminum ingot, while 0.002 wt.% aluminum beryllium alloy is added at the same time.

[0099] (2) Use a mixture of argon and chlorine (volume ratio 98:2) for protection. After the furnace is heated to 820℃, reduce the power of the medium frequency furnace and keep the temperature at 750℃ for 6 minutes.

[0100] (3) The above melt is poured into an intermediate ladle, argon is selected as the atomizing medium, and the pressure is controlled at 4MPa for atomization and sieving.

[0101] (4) Aluminum alloys are formed using selective laser melting equipment;

[0102] (5) Heat treatment of 3D printed aluminum alloy: the process is to hold at 300℃ in a muffle furnace for 6 hours, cool with dry ice, and then place it in the furnace at 380℃ for 2 hours. Nitrogen protection is required throughout the process.

[0103] Comparative Example 2

[0104] This embodiment provides a 3D printed aluminum alloy, which is composed of the following components by weight percentage: Mg 4.5wt.%, Li 0.4wt.%, Sc 0.7wt.%, Zr 0.4wt.%, Ti 0.2wt.%, Er 0.3wt.%, Yb 0.08%, with the remainder being Al and unavoidable impurities.

[0105] The above-mentioned method for preparing 3D printed aluminum alloys includes the following steps:

[0106] (1) Using pure aluminum, pure magnesium, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy as raw materials, a groove is milled out of an aluminum ingot, pure magnesium and lithium aluminum master alloy are placed in the groove and pressed at the bottom of the crucible, a large piece of pure aluminum is placed in the middle of the crucible, and aluminum manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy are evenly placed around the large piece of aluminum ingot, while 0.003 wt.% aluminum beryllium alloy is added at the same time.

[0107] (2) Use a mixture of argon and chlorine (volume ratio 97:3) for protection. After the furnace is heated to 830℃, reduce the power of the medium frequency furnace and keep the temperature at 740℃ for 5 minutes.

[0108] (3) The above melt is poured into an intermediate ladle, argon is selected as the atomizing medium, the pressure is controlled at 5MPa for atomization, and then sieved.

[0109] (4) Aluminum alloys are formed using selective laser melting equipment;

[0110] (5) Heat treatment of 3D printed aluminum alloy: hold at 310℃ in muffle furnace for 6 hours, cool with dry ice, and then place in the furnace at 390℃ for 1.5 hours. Nitrogen protection is required throughout the process.

[0111] Comparative Example 3

[0112] This embodiment provides a 3D printed aluminum alloy, which is composed of the following components by weight percentage: Mg 5.0 wt.%, Li 0.8 wt.%, Mn 0.7 wt.%, Sc 0.5 wt.%, Zr 0.6 wt.%, Ti 0.35 wt.%, Er 0.4 wt.%, Yb 0.1%, with the remainder being Al and unavoidable impurities.

[0113] The above-mentioned method for preparing 3D printed aluminum alloys includes the following steps:

[0114] (1) Using pure aluminum, pure magnesium, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy as raw materials, a groove is milled out of an aluminum ingot, pure magnesium and lithium aluminum master alloy are placed in the groove and pressed at the bottom of the crucible, a large piece of pure aluminum is placed in the middle of the crucible, and aluminum manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy are evenly placed around the large piece of aluminum ingot, while 0.002 wt.% aluminum beryllium alloy is added at the same time.

[0115] (2) Use a mixture of argon and chlorine (volume ratio 97.5:2.5) for protection. After the furnace is heated to 810℃, reduce the power of the medium frequency furnace and keep the temperature at 760℃ for 5 minutes.

[0116] (3) The above melt is poured into the intermediate ladle, argon is selected as the atomizing medium, and the pressure is controlled at 4.5MPa for atomization and sieving;

[0117] (4) Aluminum alloys are formed using selective laser melting equipment;

[0118] (5) Heat treatment of 3D printed aluminum alloy is carried out by holding at 330℃ in a muffle furnace for 4 hours, and nitrogen protection is required throughout the process.

[0119] Comparative Example 4

[0120] This embodiment provides a 3D printed aluminum alloy, which is composed of the following components by weight percentage: Mg 5.5wt.%, Li 0.7wt.%, Mn 0.5wt.%, Sc 0.6wt.%, Zr 0.65wt.%, Ti 0.4wt.%, Er 0.45wt.%, Yb 0.15%, with the remainder being Al and unavoidable impurities.

[0121] The above-mentioned method for preparing 3D printed aluminum alloys includes the following steps:

[0122] (1) Using pure aluminum, pure magnesium, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloy as raw materials, and adding 0.001 wt.% aluminum beryllium alloy, and placing it directly in a crucible;

[0123] (2) Use a mixture of argon and chlorine for protection (volume ratio 96:4). After the furnace is heated to 825℃, reduce the power of the medium frequency furnace and keep the temperature at 750℃ for 7 minutes.

[0124] (3) The above melt is poured into an intermediate ladle, argon is selected as the atomizing medium, the pressure is controlled at 6MPa for atomization, and then sieved.

[0125] (4) Aluminum alloys are formed using selective laser melting equipment;

[0126] (5) Heat treatment of 3D printed aluminum alloy: the process is to hold at 350°C in a muffle furnace for 4 hours, cool with the furnace, and then place it in the furnace at 380°C for 2 hours. Nitrogen protection is required throughout the process.

[0127] The mechanical properties of the 3D-printed aluminum alloys prepared in Examples 1-4 and Comparative Examples 1-4 were tested according to the test methods in GB / T 228.1-2010. Density was measured according to GB4472-84. The test results are shown in Table 1.

[0128] Table 1

[0129] Tensile strength (MPa) <![CDATA[Density (g / cm 3 )]]> Specific strength (kN·m / kg) Example 1 538 2.6237 205.05 Example 2 534 2.6365 202.54 Example 3 529 2.6412 200.29 Example 4 522 2.6408 197.67 Example 5 551 2.6316 209.38 Example 6 544 2.6334 206.58 Comparative Example 1 447 2.7204 164.31 Comparative Example 2 496 2.6304 167.38 Comparative Example 3 475 2.6472 179.43 Comparative Example 4 490 2.6403 182.18

[0130] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high specific strength 3D printed aluminum alloy, characterized in that, The composition by weight percentage includes the following elements: Mg 3.5-10.0%, Li 0.2-3.5%, Mn 0.5-4.0%, Sc 0.2-1.5%, Zr 0.05-2.0%, Ti 0.02-1.5%, Er 0.2-2.5%, Yb 0.01-3.0%, with the remainder being Al and unavoidable impurities; The method for preparing the high specific strength 3D printed aluminum alloy includes the following steps: The elements are mixed in proportion and then successively smelted, atomized into powder, 3D printed and heat treated to obtain the high specific strength 3D printed aluminum alloy. The heat treatment includes: holding at 250-350℃ for 2-8 hours under a protective atmosphere, cooling with dry ice, and then holding at 350-425℃ for 0.5-3 hours.

2. The high specific strength 3D printed aluminum alloy according to claim 1, characterized in that, The composition by weight percentage includes the following elements: Mg 3.5-9.0%, Li 0.4-2.8%, Mn 0.5-4%, Sc 0.2-1.1%, Zr 0.15-1.6%, Ti 0.1-1.2%, Er 0.3-2.2%, Yb 0.05-1.8%, with the remainder being Al and unavoidable impurities.

3. The high specific strength 3D printed aluminum alloy according to claim 1 or 2, characterized in that, include: Nanoscale Al3X precipitates, wherein X is one or more of Sc, Zr, Ti, Er, and Yb, the Al3X precipitates being dispersedly distributed in an Al matrix; and submicron-scale Al6Mn and ErMn2 precipitates, the Al6Mn and ErMn2 precipitates being discontinuously distributed at grain boundaries and intragranular dislocations.

4. The high specific strength 3D printed aluminum alloy according to claim 1 or 2, characterized in that, It also includes, by weight percentage: 0.001-0.004% beryllium.

5. The high specific strength 3D printed aluminum alloy according to claim 1 or 2, characterized in that, The specific strength of the high-strength 3D-printed aluminum alloy is above 195 kN·m / kg.

6. The method for preparing high specific strength 3D printed aluminum alloy according to any one of claims 1-3 or 5, characterized in that, Includes the following steps: The elements are mixed in proportion and then successively smelted, atomized into powder, 3D printed and heat treated to obtain the high specific strength 3D printed aluminum alloy. The heat treatment includes: holding the temperature under a protective atmosphere, cooling with dry ice, and then holding the temperature again.

7. The preparation method according to claim 6, characterized in that, After holding at 350-425℃ for 0.5-3 hours, cool with dry ice.

8. The preparation method according to claim 6 or 7, characterized in that, The protective gas used during smelting is a mixture of argon and chlorine. The atomizing medium is argon gas, and the atomizing pressure is 2-7 MPa.

9. The preparation method according to claim 8, characterized in that, The volume ratio of argon to chlorine is (95-99):(1-5).

10. The preparation method according to claim 6 or 7, characterized in that, The process of mixing the elements in proportion includes: using pure aluminum ingots, pure magnesium ingots, lithium aluminum, manganese aluminum, scandium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloys as raw materials, mixing them according to the alloy composition, and placing them in a crucible in a certain way; the placement method is as follows: a groove is milled into a part of the pure aluminum ingots, pure magnesium ingots and lithium aluminum master alloys are placed in the grooves, then the pure aluminum ingots containing pure magnesium ingots and lithium aluminum master alloys are placed at the bottom of the crucible, then another part of the pure aluminum ingots are placed in the middle of the crucible, and the lithium aluminum, zirconium aluminum, titanium aluminum, erbium aluminum, and ytterbium aluminum master alloys are evenly placed around the pure aluminum ingots.

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