A laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy and a preparation method thereof

Abstract

The application discloses a laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy and a preparation method thereof. The alloy is prepared by using a selective laser melting method, and the alloy comprises the following components in percentage by mass: Mg 5.1-11.4%, Si 2.1-6.7%, Cu 0.5-2.3%, and the balance of aluminum, and the total percentage by mass is 100%. By optimizing printing process parameters, the application realizes the dense and crack-free forming of the Al-Mg-Si-Cu alloy. Based on the solidification characteristics of high temperature gradient and high cooling speed of the selective laser melting, the hierarchical microstructure with length scales spanning multiple orders of magnitude is obtained through component design, including the micrometer-scale bimodal grain structure, the sub-micrometer-scale cellular structure and the coherent nano precipitated phase, and the mechanical properties of the alloy are effectively improved. The application has reasonable component design, simple and controllable preparation process, and the obtained product has excellent performance and is convenient for industrial application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new material preparation, in particular to a laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy and a preparation method thereof. BACKGROUND

[0002] Al-Mg-Si (6 series) aluminum alloy has high specific strength and good corrosion resistance, and has been widely used in aerospace, high-speed rail, shipbuilding and automobile industries. With the development of aerospace and rail transportation, the parts are becoming more complex and lightweight, which puts higher requirements on the mechanical properties of aluminum alloys. At present, Al-Mg-Si alloy is usually manufactured by casting and subsequent thermal mechanical processing (including extrusion, hot rolling, cold rolling, etc.), but due to the complexity and time-consuming of the subsequent process, the cost-effectiveness is not high. In addition, the mechanical properties of the alloy prepared by the traditional method are insufficient, which is difficult to meet the increasingly stringent requirements of engineering applications.

[0003] Selective laser melting is a new metal additive manufacturing technology. Compared with traditional processing methods, selective laser melting has the ability of high efficiency and rapid manufacturing, which can manufacture complex internal structures and thin-walled materials. Due to the significant tendency of thermal cracking during solidification, most aluminum alloys are not suitable for selective laser melting. There are few maturely printed aluminum alloys, which are mainly concentrated in two aspects. One is to introduce elements or particles modification (Sc, Zr, TiB2, TiC) of commercial cast aluminum alloys Al-Cu, Al-Zn-Mg-Cu alloy, which can form crack-free alloys through heterogeneous nucleation, but the preparation process of this alloy is complex and difficult to control, and the introduction of rare elements also increases the cost. The other is on the binary eutectic alloy (Al-Si, Al-Ni, Al-Fe, Al-Ce), the narrow solidification range of these alloys exists in the last stage of solidification shrinkage, and the eutectic phase can effectively fill the liquid film, thereby avoiding the generation of cracks. However, the strength of the successfully printed binary alloy is generally low, and new eutectic alloy systems still need to be developed.

[0004] At present, due to the high crack sensitivity during solidification, the Al-Mg-Si alloy developed for traditional forging process produces serious thermal cracks during the forming process of selective laser melting, which greatly hinders the practical application of selective laser melting in industry. Therefore, it is of great significance to develop a new type of high-strength eutectic aluminum alloy with low cost, no cracks and excellent mechanical properties by using the characteristics of high gradient and high speed of SLM forming. SUMMARY

[0005] The present application proposes a laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy and a preparation method thereof to solve the above problems in the preparation of Al-Mg-Si alloy in the prior art.

[0006] The laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy according to the present application comprises the following components in percentage by mass: Mg 5.1-11.4%, Si 2.1-6.7%, Cu 0.5-2.3%, and the balance being aluminum, with the total percentage by mass being 100%; the multi-scale microstructure is composed of a bimodal grain structure in micron scale, a cellular structure in sub-micron scale, and a coherent nanometer precipitate phase.

[0007] As a preferred scheme, the laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy according to the present application comprises the following components in percentage by mass: Mg 6.2-8.4%, Si 3.0-5.3%, Cu 1.0-1.8%, and the balance being aluminum, with the total percentage by mass being 100%. The present application greatly increases the contents of Mg and Si on the basis of the conventional cast Al-Mg-Si aluminum alloy (generally with a total alloy element content less than 2%), and controls the contents of Mg and Si at 6.2-8.4% (preferably 6.3-7.9%) and 3.0-5.3% (preferably 3.1-3.7%), respectively. By using the characteristics of selective laser melting rapid solidification, a unique multi-scale microstructure is formed. If the contents are too low, too few nanometer-scale precipitates are formed, and if the contents are too high, the cellular structure in the grain no longer exists and a coarse Mg2Si phase can be formed. The content of Cu is controlled at 1.0-1.8%, so as to form a strengthened θ phase (Al2Cu). If the content of Cu is too low, Cu is completely solid-solved into the matrix, and if the content of Cu is too high, Cu is largely segregated at the cell boundaries, which can lead to the generation of cracks.

[0008] As a more preferred scheme, the laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy according to the present application comprises the following components in percentage by mass: Mg 6.3-7.9%, Si 3.1-3.7%, Cu 1.1-1.6%, and the balance being aluminum, with the total percentage by mass being 100%. As a preferred scheme, the bimodal grain is composed of coarse columnar grains in the center of the molten pool and fine equiaxed grains at the boundary of the molten pool, wherein the size ranges of the fine grains and the coarse grains are 4-11 μm and 40-120 μm, respectively.

[0009] As a further preferred scheme, the size range of the coarse grains is 40-60 μm. As a preferred scheme, the cellular structure is uniformly distributed in the grain interior and is modified by in-situ self-grown high-density dislocations, with the size range being 0.5-1 μm.

[0010] As a preferred solution, the coherent precipitates are theta phase (Al2Cu) and beta phase (Mg2Si), which are pinned at the grain boundaries, and the size ranges from 100 to 200 nm. The nanoscale theta phase and beta phase precipitates are around the subgrain structure. This is beneficial to pin the grain boundaries to improve the strength, while the subgrain has a strong hindering effect on dislocations, which can greatly improve the strength and plasticity of the alloy.

[0011] The application also provides a preparation method of the high-strength Al-Mg-Si-Cu alloy for laser selective melting, which comprises the following steps:

[0012] (1) using a computer to draw a three-dimensional model required for selective laser melting forming;

[0013] (2) using the alloy powder prepared by the gas atomization method as a raw material, performing selective laser melting forming on an aluminum alloy substrate to obtain a high-strength aluminum alloy.

[0014] As a preferred solution, the particle size of the alloy powder obtained by the gas atomization ranges from 15 to 53 μm. In this particle size range, the powder has good flowability and rowing property, and the powder can be fully melted to obtain a formed piece with a smooth surface.

[0015] As a preferred solution, the step (2) comprises: using the selective laser melting technology to prepare an alloy sample, the powder laying thickness is fixed at 0.03 mm, the scanning interval is fixed at 0.10 mm, the laser scanning power is 285-330 W, and the laser scanning rate is 780-1020 mm / s.

[0016] As a more preferred solution, the step (2) comprises: using the selective laser melting technology to prepare an alloy sample, the powder laying thickness is fixed at 0.03 mm, the scanning interval is fixed at 0.10 mm, the laser scanning power is 288-312 W, and the laser scanning rate is 800-1000 mm / s.

[0017] As a preferred solution, when the chemical composition of the aluminum alloy powder is Mg 7.6%, Si 3.5%, Cu 1.5%, and the balance is aluminum, the total mass percentage is 100%, the selective laser melting technology is used to prepare an alloy sample, the powder laying thickness is 0.03 mm, the scanning interval is 0.10 mm, the laser scanning power is 290 W, the laser scanning rate is 1000 mm / s, the substrate preheating temperature is 80°C, the density of the obtained printed piece is 99.91%, the hardness is 178 HV, the maximum tensile strength is 545 MPa, the yield strength is 443 MPa, and the elongation is 11.5%.

[0018] The particle size of the raw material is less than or equal to 74 μm.

[0019] Compared with the prior art, the laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy and the preparation method thereof have the following advantages:

[0020] 1) By adopting the selective laser melting technology, the forming problem of the high-strength Al-Mg-Si alloy complex component is solved as a whole, the machining process is reduced, no mold is needed, the manufacturing cost is reduced, the manufacturing cycle is shortened, and the production of the Al-Mg-Si alloy complex component is suitable.

[0021] 2) On the basis of the traditional cast aluminum alloy (Al-Mg-Si alloy), the content of Mg and Si elements is greatly increased, so that the alloy is suitable for the selective laser melting technology, then Cu is added for micro-alloying treatment, and the material system of the additive manufacturing aluminum alloy is enriched. Based on the high gradient and high speed solidification characteristics of the selective laser melting, the hierarchical microstructure with length scales spanning multiple orders of magnitude is obtained through alloy composition design, including the micron-scale bimodal grain structure, the sub-micron-scale cellular structure and the coherent nanometer precipitated phase, so that the mechanical properties of the alloy are effectively improved.

[0022] 3) The invention realizes the dense and crack-free forming of the eutectic Al-Mg-Si-Cu alloy by optimizing the printing process parameters, and does not need subsequent heat treatment process, the ultimate tensile strength of the alloy is greater than or equal to 545 MPa, the yield strength is greater than or equal to 443 MPa, and the elongation is greater than or equal to 11.5%, the mechanical properties are much higher than those of the cast and forged aluminum alloy, and the mechanical properties of the high-strength aluminum alloy component can meet the use requirements of the aerospace. BRIEF DESCRIPTION OF DRAWINGS

[0023] The invention will be further described below in combination with the drawings and examples.

[0024] Figure 1 It is a schematic diagram of the eutectic Al-Mg-Si-Cu alloy powder prepared by the gas atomization method.

[0025] Figure 2 It is an optical microscope graph of the eutectic Al-Mg-Si-Cu alloy prepared under the optimal process parameters of Example 4.

[0026] Figure 3 It is a grain graph of the eutectic Al-Mg-Si-Cu alloy prepared under the optimal process parameters of Example 4.

[0027] Figure 4 It is a cellular structure scanning electron microscope graph of the eutectic Al-Mg-Si-Cu alloy prepared under the optimal process parameters of Example 4.

[0028] Figure 5Transmission electron microscope image of nano precipitate of eutectic Al-Mg-Si-Cu alloy prepared in Example 4 under the optimal process parameters.

[0029] From Figure 1 It can be seen that the powder is spherical, the powder particle size is 14.7-53.6 μm, and the flowability is good, which is suitable for selective laser melting forming.

[0030] From Figure 2 It can be seen that the sample surface has less defects, is dense and crack-free, indicating good formability.

[0031] From Figure 3 It can be seen that the micron-sized columnar coarse grains and equiaxed fine grains are alternately distributed, forming a bimodal grain structure.

[0032] From Figure 4 It can be seen that the matrix is mainly composed of uniformly distributed sub-micron cell structures.

[0033] From Figure 5 It can be seen that the grain interior contains a large number of subcells, which are modified by in-situ self-grown high-density dislocations, and nanoscale theta phase and beta phase are dispersedly distributed at the subcell boundaries. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0035] The Al-Mg2Si alloy raw material powder used in the experiment is prepared by using pure aluminum ingot, pure magnesium ingot, aluminum-manganese intermediate alloy and aluminum-copper intermediate alloy as raw materials, using vacuum gas atomization to prepare alloy powder, and sieving the prepared powder through a 200-mesh screen to obtain spherical powder.

[0036] Example 1

[0037] A laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy comprises the following components in mass percentage: Mg 5.9%, Si 2.8%, Cu 0.9%, and the balance being aluminum, with a total mass percentage of 100%.

[0038] The preparation method is as follows:

[0039] (1) A three-dimensional model required for selective laser melting forming is drawn by computer;

[0040] (2) The alloy powder prepared by gas atomization method is used as raw material to perform selective laser melting forming on an aluminum alloy substrate to obtain a high-strength aluminum alloy.

[0041] The step (2) comprises: using selective laser melting technology to prepare the alloy sample, the powder laying thickness is fixed as 0.03 mm, the scanning interval is fixed as 0.10 mm, the laser scanning power is 290 W, and the laser scanning rate is 800 mm / s.

[0042] The performance test is conducted on the aluminum alloy sample prepared in the embodiment, and the density is 98.56%, the hardness is 165 HV, the maximum tensile strength is 421 MPa, the yield strength is 310 MPa, and the elongation is 9.4%.

[0043] Embodiment 2

[0044] The laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy comprises the following components in percentage by mass: Mg 6.3%, Si 3.1%, Cu 1.1%, and the balance is aluminum, and the total percentage by mass is 100%.

[0045] The preparation method comprises the following steps:

[0046] (1) a three-dimensional model required for selective laser melting forming is drawn by using a computer;

[0047] (2) the alloy powder prepared by using the gas atomization method is used as raw material to perform selective laser melting forming on an aluminum alloy substrate to obtain high-strength aluminum alloy.

[0048] The step (2) comprises: using selective laser melting technology to prepare the alloy sample, the powder laying thickness is fixed as 0.03 mm, the scanning interval is fixed as 0.10 mm, the laser scanning power is 310 W, and the laser scanning rate is 800 mm / s.

[0049] The performance test is conducted on the aluminum alloy sample prepared in the embodiment, and the density is 99.26%, the hardness is 172 HV, the maximum tensile strength is 531 MPa, the yield strength is 425 MPa, and the elongation is 11.7%.

[0050] Embodiment 3

[0051] The laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy comprises the following components in percentage by mass: Mg 6.3%, Si 3.1%, Cu 1.1%, and the balance is aluminum, and the total percentage by mass is 100%.

[0052] The preparation method comprises the following steps:

[0053] (1) a three-dimensional model required for selective laser melting forming is drawn by using a computer;

[0054] (2) using the alloy powder prepared by the gas atomization method as raw material, carrying out selective laser melting forming on the aluminum alloy substrate to obtain high-strength aluminum alloy.

[0055] The step (2) comprises: using the selective laser melting technology to prepare the alloy sample, fixing the powder laying thickness as 0.03 mm, fixing the scanning interval as 0.10 mm, and setting the laser scanning power as 330 W and the laser scanning rate as 800 mm / s.

[0056] The aluminum alloy sample prepared in the embodiment is subjected to performance testing, and the density thereof is 99.51%, and the mechanical performance indexes thereof are as follows: the hardness is 174 HV, the maximum tensile strength is 510 MPa, the yield strength is 407 MPa, and the elongation is 10.1%.

[0057] Embodiment 4

[0058] A laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy comprises the following components in percentage by mass: Mg 7.6%, Si 3.5%, Cu 1.5%, and the balance being aluminum, and the total percentage by mass is 100%.

[0059] The preparation method comprises the following steps:

[0060] (1) using a computer to draw a three-dimensional model required for selective laser melting forming;

[0061] (2) using the alloy powder prepared by the gas atomization method as raw material, carrying out selective laser melting forming on the aluminum alloy substrate to obtain high-strength aluminum alloy.

[0062] The step (2) comprises: using the selective laser melting technology to prepare the alloy sample, fixing the powder laying thickness as 0.03 mm, fixing the scanning interval as 0.10 mm, and setting the laser scanning power as 290 W and the laser scanning rate as 1000 mm / s.

[0063] The aluminum alloy sample prepared in the embodiment is subjected to performance testing, and the density thereof is 99.91%, and the mechanical performance indexes thereof are as follows: the hardness is 178 HV, the maximum tensile strength is 545 MPa, the yield strength is 443 MPa, and the elongation is 11.5%.

[0064] Embodiment 5

[0065] A laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy comprises the following components in percentage by mass: Mg 10.4%, Si 5.7%, Cu 2.1%, and the balance being aluminum, and the total percentage by mass is 100%.

[0066] The preparation method comprises the following steps:

[0067] (1) using a computer to draw a three-dimensional model required for selective laser melting;

[0068] (2) using alloy powder prepared by a gas atomization method as raw material to perform selective laser melting on an aluminum alloy substrate to obtain high-strength aluminum alloy.

[0069] In step (2), the alloy sample is prepared by using selective laser melting technology, the powder laying thickness is fixed at 0.03 mm, the scanning interval is fixed at 0.10 mm, the laser scanning power is 310 W, and the laser scanning rate is 1000 mm / s.

[0070] The aluminum alloy sample prepared in the embodiment is subjected to performance testing, and the density thereof is 98.89%, and the mechanical performance indexes thereof are as follows: the hardness is 167 HV, the maximum tensile strength is 413 MPa, the yield strength is 311 MPa, and the elongation is 10.2%.

[0071] Example 6

[0072] A laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy includes the following components in mass percentage: Mg 5.1%, Si 2.7%, Cu 1.9%, and the balance being aluminum, with the total mass percentage being 100%.

[0073] The preparation method includes the following steps:

[0074] (1) using a computer to draw a three-dimensional model required for selective laser melting;

[0075] (2) using alloy powder prepared by a gas atomization method as raw material to perform selective laser melting on an aluminum alloy substrate to obtain high-strength aluminum alloy.

[0076] In step (2), the alloy sample is prepared by using selective laser melting technology, the powder laying thickness is fixed at 0.03 mm, the scanning interval is fixed at 0.10 mm, the laser scanning power is 330 W, and the laser scanning rate is 1000 mm / s.

[0077] The aluminum alloy sample prepared in the embodiment is subjected to performance testing, and the density thereof is 97.56%, and the mechanical performance indexes thereof are as follows: the hardness is 164 HV, the maximum tensile strength is 397 MPa, the yield strength is 304 MPa, and the elongation is 13.1%.

[0078] Comparative Example 1

[0079] A laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si alloy comprises the following components in percentage by mass: Mg 1.0%, Si 0.6%, and the balance being aluminum, with the total percentage by mass being 100%.

[0080] The preparation method comprises the following steps:

[0081] (1) a three-dimensional model required for selective laser melting forming is drawn by using a computer;

[0082] (2) an alloy powder prepared by using an air atomization method is used as raw material to perform selective laser melting forming on an aluminum alloy substrate to obtain a high-strength aluminum alloy.

[0083] In the step (2), the alloy sample is prepared by using a selective laser melting technology, the powder laying thickness is fixed as 0.03 mm, the scanning interval is fixed as 0.10 mm, the laser scanning power is 290 W, and the laser scanning rate is 1000 mm / s.

[0084] The performance of the aluminum alloy sample prepared in the example is tested, and the density is 95.31%, the hardness is 154 HV, the maximum tensile strength is 310 MPa, the yield strength is 230 MPa, and the elongation is 6.3%.

[0085] Example 2

[0086] A laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si alloy comprises the following components in percentage by mass: Mg 14.1%, Si 8.4%, and the balance being aluminum, with the total percentage by mass being 100%.

[0087] The preparation method comprises the following steps:

[0088] (1) a three-dimensional model required for selective laser melting forming is drawn by using a computer;

[0089] (2) an alloy powder prepared by using an air atomization method is used as raw material to perform selective laser melting forming on an aluminum alloy substrate to obtain a high-strength aluminum alloy.

[0090] In the step (2), the alloy sample is prepared by using a selective laser melting technology, the powder laying thickness is fixed as 0.03 mm, the scanning interval is fixed as 0.10 mm, the laser scanning power is 290 W, and the laser scanning rate is 1000 mm / s.

[0091] The performance of the aluminum alloy sample prepared in the example is tested, and the density is 99.56%, the hardness is 157 HV, the maximum tensile strength is 350 MPa, the yield strength is 274 MPa, and the elongation is 5.9%.

[0092] Comparative Example 3

[0093] A laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy, by mass percentage, comprises the following components: Mg 7.6%, Si 3.5%, Cu 0.4%, the balance being aluminum, and the total mass percentage being 100%.

[0094] The preparation method comprises the following steps:

[0095] (1) A three-dimensional model required for selective laser melting forming is drawn by a computer;

[0096] (2) An alloy powder prepared by an air atomization method is used as raw material to perform selective laser melting forming on an aluminum alloy substrate to obtain a high-strength aluminum alloy.

[0097] The step (2) comprises: using a selective laser melting technology to prepare an alloy sample, the powder laying thickness is fixed at 0.03 mm, the scanning interval is fixed at 0.10 mm, the laser scanning power is 290 W, and the laser scanning rate is 1000 mm / s.

[0098] The performance of the aluminum alloy sample prepared in the comparative example is tested, and the density thereof is 98.71%, and the mechanical performance indexes are as follows: the hardness is 161 HV, the maximum tensile strength is 393 MPa, the yield strength is 328 MPa, and the elongation is 8.1%.

[0099] Comparative Example 4

[0100] A laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy, by mass percentage, comprises the following components: Mg 7.6%, Si 3.5%, Cu 2.9%, the balance being aluminum, and the total mass percentage being 100%.

[0101] The preparation method comprises the following steps:

[0102] (1) A three-dimensional model required for selective laser melting forming is drawn by a computer;

[0103] (2) An alloy powder prepared by an air atomization method is used as raw material to perform selective laser melting forming on an aluminum alloy substrate to obtain a high-strength aluminum alloy.

[0104] The step (2) comprises: using a selective laser melting technology to prepare an alloy sample, the powder laying thickness is fixed at 0.03 mm, the scanning interval is fixed at 0.10 mm, the laser scanning power is 290 W, and the laser scanning rate is 1000 mm / s.

[0105] The performance of the aluminum alloy sample prepared from the comparative example is tested, and the density thereof is 97.56%, and the mechanical performance indexes thereof are as follows: the hardness is 155HV, the maximum tensile strength is 321MPa, the yield strength is 210MPa, and the elongation is 7.4%.

[0106] Comparative example 5

[0107] A laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy comprises the following components in percentage by mass: Mg 7.6%, Si 3.5%, Cu 1.5%, and the balance being aluminum, with the total percentage by mass being 100%.

[0108] The preparation method comprises the following steps:

[0109] (1) a three-dimensional model required for selective laser melting forming is drawn by using a computer;

[0110] (2) an alloy powder prepared by using an air atomization method is used as raw material to perform selective laser melting forming on an aluminum alloy substrate to obtain a high-strength aluminum alloy.

[0111] The step (2) comprises the following steps: an alloy sample is prepared by using a selective laser melting technology, the powder laying thickness is fixed as 0.03mm, the scanning interval is fixed as 0.10mm, the laser scanning power is 250W, and the laser scanning rate is 600mm / s.

[0112] The performance of the aluminum alloy sample prepared from the comparative example is tested, and the density thereof is 97.56%, and the mechanical performance indexes thereof are as follows: the hardness is 155HV, the maximum tensile strength is 321MPa, the yield strength is 210MPa, and the elongation is 7.4%.

[0113] Comparative example 6

[0114] A laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy comprises the following components in percentage by mass: Mg 7.6%, Si 3.5%, Cu 1.5%, and the balance being aluminum, with the total percentage by mass being 100%.

[0115] The preparation method comprises the following steps:

[0116] (1) a three-dimensional model required for selective laser melting forming is drawn by using a computer;

[0117] (2) an alloy powder prepared by using an air atomization method is used as raw material to perform selective laser melting forming on an aluminum alloy substrate to obtain a high-strength aluminum alloy.

[0118] The step (2) comprises: using selective laser melting technology to prepare the alloy sample, the powder laying thickness is fixed at 0.03 mm, the scanning interval is fixed at 0.10 mm, the laser scanning power is 370 W, and the laser scanning rate is 1400 mm / s.

[0119] The performance of the aluminum alloy sample prepared in the example is tested, and the density of the sample is 97.56%, and the mechanical performance indexes of the sample are as follows: the hardness is 148 HV, the maximum tensile strength is 275 MPa, the yield strength is 221 MPa, and the elongation is 5.4%.

[0120] Table 1 below lists the yield strength, ultimate tensile strength and elongation of the eutectic Al-Mg-Si-Cu alloy prepared by laser selective melting under different laser powers, and the mechanical properties of the Al-Mg-Si cast and forged parts are also given for comparison. The results show that the Al-Mg-Si-Cu alloy formed by laser selective melting under the optimal process parameters exhibits excellent comprehensive mechanical properties, the tensile strength reaches 545 MPa, the yield strength is 443 MPa, and the elongation is 11.5%. The mechanical properties are better than those of the cast and forged parts. At the same time, it can be seen that the mechanical properties of the alloy under different process parameters are good in consistency and have no large difference.

[0121] Table 1

[0122]

[0123] The above specific embodiments can be adjusted in different ways by those skilled in the art without departing from the principles and purposes of the present application. The protection scope of the present application is subject to the claims and is not limited by the above specific embodiments. Each implementation scheme within the scope is subject to the constraints of the present application.

Claims

1. A laser additive manufactured multi-scale microstructured reinforced eutectic Al-Mg-Si-Cu alloy, characterized in that: By mass percent, the following components are included: Mg 6.2-8.4%, Si 3.0-5.3%, Cu 1.0-1.8%, the balance being aluminum, with the total mass percent being 100%; The multi-scale microstructure is composed of a bimodal grain structure of micron scale, a cellular structure of sub-micron scale, and coherent nano precipitates. The laser additive manufacturing multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy is prepared by the following steps: (1) a three-dimensional model required for selective laser melting is drawn by a computer; (2) an alloy powder prepared by an air atomization method is used as a raw material to perform selective laser melting on an aluminum alloy substrate to obtain a high-strength aluminum alloy; In the step (2), an alloy sample is prepared by using a selective laser melting technology, the powder laying thickness is fixed at 0.03 mm, the scanning interval is fixed at 0.10 mm, the laser scanning power is 285-330 W, and the laser scanning rate is 780-1020 mm / s.

2. The laser additive manufactured multi-scale microstructure reinforced eutectic Al-Mg-Si-Cu alloy according to claim 1, characterized in that: By mass percent, the following components are included: Mg 6.3-7.9%, Si 3.1-3.7%, Cu 1.1-1.6%, the balance being aluminum, with the total mass percent being 100%.

3. The laser additive manufactured multi-scale microstructure reinforced hypereutectic Al-Mg-Si-Cu alloy according to claim 1, characterized in that: The bimodal grain is composed of coarse columnar grains in the center of the molten pool and fine equiaxed grains at the boundary of the molten pool, wherein the size ranges of the fine grains and the coarse grains are 4-11 μm and 40-120 μm, respectively.

4. The laser additive manufactured multi-scale microstructure reinforced hypereutectic Al-Mg-Si-Cu alloy according to claim 1, characterized in that: The cellular structure is uniformly distributed in the grain interior and is modified by in-situ self-grown high-density dislocations, and the size range is 0.5-1 μm.

5. The laser additive manufactured multi-scale microstructured synergic Al-Mg-Si-Cu alloy according to claim 1, characterized in that: The coherent nano precipitates are θ phase and β phase, which are pinned at the boundary of the cellular structure, and the size range is 100-200 nm; the nano-scale θ phase and β phase are precipitated around the sub-cellular structure.

6. The laser additive manufactured multi-scale microstructured synergic Al-Mg-Si-Cu alloy according to claim 1, characterized in that: In the step (2), the laser scanning power is 288-312 W, and the laser scanning rate is 800-1000 mm / s.

7. The laser additive manufactured multi-scale microstructured synergic Al-Mg-Si-Cu alloy according to claim 1, characterized in that: When the chemical composition of the aluminum alloy powder is Mg 7.6%, Si 3.5%, Cu 1.5%, the balance being aluminum, with the total mass percent being 100%, an alloy sample is prepared by using a selective laser melting technology, the powder laying thickness is 0.03 mm, the scanning interval is 0.10 mm, the laser scanning power is 290 W, the laser scanning rate is 1000 mm / s, and the substrate preheating temperature is 80°C, and the obtained printed piece has a density of 99.91%, a hardness of 178 HV, a maximum tensile strength of 545 MPa, a yield strength of 443 MPa, and an elongation of 11.5%.

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