CN111593234A

CN111593234A - Aluminum alloy material for laser additive manufacturing

Info

Publication number: CN111593234A
Application number: CN202010663523.XA
Authority: CN
Inventors: 邓军旺; 陈超; 陈果; 李云平; 张桃梅; 李丹; 李瑞迪; 周科朝
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2020-07-10
Filing date: 2020-07-10
Publication date: 2020-08-28
Anticipated expiration: 2040-07-10
Also published as: CN111593234B

Abstract

The invention relates to the field of metal additive manufacturing, in particular to a laser additive manufacturing aluminum alloy material. The powder material comprises the following components in percentage by mass: ni: 1.0-8.0%, Cu: 0-2.0%, Mg: 0-3.0%, Mn: 0-1.0%, Zr: 0-0.5%, Fe: 0-0.1%, Si: 0 to 0.1 percent of aluminum and the balance of aluminum. The powder is prepared by a melt gas atomization method. The obtained aluminum alloy powder is used for at least one technical field of additive manufacturing, powder metallurgy, injection molding, hot isostatic pressing and welding repair. The aluminum alloy powder designed and prepared by the invention can be directly used for 3D printing; the performance of the product obtained by 3D printing is excellent; especially, the high-temperature mechanical property of the obtained product is far superior to that of the similar products.

Description

Aluminum alloy material for laser additive manufacturing

The technical field is as follows:

the invention relates to the field of metal additive manufacturing, in particular to an aluminum alloy material for laser additive manufacturing.

Background art:

additive manufacturing is a great hot spot of the research of the current material preparation technology, wherein the direct near-net forming of parts can be realized by selecting a laser melting technology (SLM) without a mould, so that the method is widely concerned by people. At present, the method is applied to the fields of aviation, medical instruments, automobiles and the like. Because the aluminum alloy has excellent specific strength, heat conductivity, electric conductivity, corrosion resistance and other properties, a great deal of research and application have been carried out in the technical field of SLM. The additive manufacturing part technology of the aluminum alloy systems such as AlSi12 and AlSi10Mg is relatively mature, but the mechanical property of the Al-Si alloy is not high. The Al-Mg alloy performance can be greatly improved by compositely adding Sc and Zr, a GE company develops a novel Al-Mg-Sc-Zr high-strength aluminum alloy and registers an alloy mark, and domestic patents CN 109909492A, CN 109175350A, CN 109487126A and the like disclose Al-Mg-Sc-Zr alloys similar to the United states, but the difference is that alloy elements such as Cu, Mn and the like are compositely added, so that high-strength and high-toughness aluminum alloy powder for additive manufacturing is obtained; but because of the addition of Sc, the material cost is very high, and the application and popularization are limited. Most of Al-Cu and Al-Zn high-strength aluminum alloys belong to non-eutectic alloy components, and from a phase diagram (shown in figure 1), the solidification interval span is large, thermal cracks are easily generated in the solidification process, and particularly in the field of laser additive manufacturing, the thermal cracks are hardly avoided under the non-equilibrium solidification condition caused by extremely high cooling speed, so that the application of the high-strength aluminum alloys in the field of additive manufacturing is limited.

The Ni element is a transition element, is one of the most important elements for improving the high-temperature mechanical property of the aluminum alloy, and is an important element applied to the structural material aluminum-copper alloy. The main precipitated phase of the Al-Ni system aluminum-rich end is Al₃Ni。Al₃The lattice constant of Ni particles is 4.104 × 10^-10m, which is coherent with the matrix, thereby limiting dislocation motion, hindering grain growth, refining grains and strengthening alloy, and the aluminum alloy with Al-Ni eutectic structure shows excellent fluidity and fine grain strengthening effect. Meanwhile, Ni and Fe can form Al9FeNi and other precipitation phases to effectively remove part of Fe impurities in the aluminum alloy, and the nickel-rich phases have good dispersibility, thermal stability, distribution and appearance, can obviously improve the high-temperature mechanical property of the aluminum alloy, also have good wear resistance and corrosion resistance, and are suitable for more severe and stricter environments. Currently, scholars think that: an excessive addition of more than 0.7% causes Ni to be coarse inclusions; the stress corrosion cracking resistance, the tensile property and the processing property are also adversely affected (patent CN102482737A), and the traditional cast Al-Ni alloy has a coarse structure and poor performance, is hardly applied and has little Al-Ni series aluminum alloy mark for industrial application. The content of nickel in the Al-Ni eutectic composition point is 5.72 (wt)%, as shown in figure 2, the Al-Ni eutectic composition point is a liquid-solid boundary point, the solidification interval is extremely small, and the hot cracking tendency is extremely small. The cooling speed of the additive manufacturing is high and can reach 10⁶K/s, lack of growing environment of coarse phase, and favor to form nano-grade Al₃Ni particles, and is compatible with the matrix, as detailed in FIG. 3. The Al-Ni alloy is manufactured by adopting the additive manufacturing technology, so that the characteristics of eutectic components can be utilized to avoid the generation of thermal cracks, and meanwhile, the alloy has excellent fine grain strengthening effect and obtains higher strength.

The invention content is as follows:

the invention develops the application of the Al-Ni eutectic alloy in the field of additive manufacturing in order to exert the advantages of the Al-Ni eutectic alloy and enrich the additive of the aluminum alloyA material system is manufactured. The invention proposes to increase the amount of Ni; through the synergistic effect between the aluminum alloy and alloy elements such as Cu, Mg, Mn, Zr and the like which are added in proper amount, the strength of the alloy is improved and the plasticity of the alloy is improved by utilizing strengthening mechanisms such as micro-alloying, multi-stability nano particle precipitation, grain refinement and the like, the thermal stability, distribution and appearance are good, the high-temperature mechanical property of the aluminum alloy can be obviously improved (including the tensile property), and the aluminum alloy also has good wear resistance and corrosion resistance, and is suitable for more severe and strict environments. The invention can not only avoid the hot crack caused by the aluminum alloy material, but also obtain the coherent Al with the nanometer scale by utilizing the technical characteristics of rapid cooling in additive manufacturing₃The Ni particles obtain a high-strength additive manufacturing aluminum alloy, and an aluminum alloy system for additive manufacturing is widened.

The invention aims to provide an aluminum alloy for laser additive manufacturing, which comprises the following main alloy elements in percentage by mass: ni: 3.0-8.0%, Cu: 0% -2.0%, Mg: 0% -3.0%, Mn: 0-1.0%, Zr: 0-0.5%, Fe: 0-0.1%, Si: 0 to 0.1 percent of aluminum and the balance of aluminum.

Preferably, the aluminum alloy comprises the following components in percentage by mass: ni: 4.5-6.5%, Cu: 1.0% -1.5%, Mg: 0.5% -2.5%, Mn: 0.1% -0.3%, Zr: 0.1% -0.3%, Fe: 0.05 to 0.1%, Si: 0.05-0.1% of aluminum, and the balance of aluminum.

Further preferably, the aluminum alloy comprises the following components in percentage by mass: ni: 5.0-6.0%, Cu: 0-0.1%, Mg: 0-0.1%, Mn: 0-0.1%, Zr: 0-0.1%, Fe: 0-0.05%, Si: 0 to 0.05 percent of aluminum and the balance of aluminum.

Still further preferably, the aluminum alloy comprises the following components in percentage by mass: ni: 5.5-8.0%, Cu: 0.5% -1.5%, Mg: 0.5% -0.8%, Mn: 0.1% -1.0%, Zr: 0.1% -0.3%, Fe: 0.05 to 0.1%, Si: 0.05-0.1% of aluminum, and the balance of aluminum.

The invention also relates to a preparation method of the high-strength aluminum alloy powder for additive manufacturing, which comprises the following specific steps:

1. vacuum melting

(1) According to the component proportion of the aluminum alloy, weighing pure aluminum (the purity is more than or equal to 99.9 percent wt), pure magnesium (the purity is more than or equal to 99.9 percent wt), and the other elements are all aluminum intermediate alloy, the impurity content of the intermediate alloy is less than 0.1 percent, and putting the weighed aluminum into a crucible of a vacuum intermediate frequency induction furnace.

(2) Vacuum pumping is carried out to 10^-2Within Pa, starting heating, and starting to fill argon or nitrogen (the gas purity is more than or equal to 99.995%) to micro positive pressure (0.05-0.3MPa) after heating to the temperature of 300-; when pure aluminum is completely melted and the temperature is 720-850 ℃, gradually adding aluminum intermediate alloy, and sequentially adding alloy elements according to the sequence of high and low melting points;

(3) and after the alloy is completely melted, adding hexachloroethane for degassing and stirring, fully and uniformly mixing the alloy solution under the action of a magnetic field, keeping the temperature and standing for 40-50min, and casting after standing to obtain the aluminum alloy cast ingot for gas atomization.

2. Supersonic inert gas vacuum atomization

(1) Putting the aluminum alloy ingot into a crucible of an intermediate frequency furnace, and starting a vacuum pump;

(2) when the pressure in the furnace is less than or equal to 10^-2When Pa, starting a power supply to start heating;

(3) continuously increasing the power of the intermediate frequency furnace, and controlling the heating rate at 10-20 ℃/s; when the temperature reaches 350-;

(4) the gas pressure in the smelting furnace is maintained at 0.05-0.2MPa, the temperature is continuously increased to 780-830 ℃, and the temperature is kept for 50-90 min;

(5) starting an atomization gas circulation system to prepare for atomization;

preferably, the atomization medium is a mixed gas of argon and helium, and the mixing ratio is 1: 0.1-0.5.

Preferably, the purity of the atomizing medium is more than or equal to 99.995 percent, and the dew point is lower than-60 ℃.

(6) And starting an atomization system to prepare powder according to the operation specification, wherein the atomization pressure is controlled within the range of 4-10MPa, and the flow velocity of atomization gas is 1-3 times of the sound velocity.

(7) After the atomized powder is prepared and the powder is cooled, the powder is sieved and classified by ultrasonic vibration, the first screen is 200-mesh and 350-mesh, and the second screen is 1000-mesh and 1500-mesh.

(8) The yield of the powder with the particle size of 15-74 mu m after screening is more than or equal to 50 percent, the hollow rate of the powder is less than or equal to 0.2 percent, and the oxygen content is less than or equal to 300 ppm.

(9) And packaging the sieved aluminum alloy powder by using a vacuum bag for later use.

3. Selective laser melting additive manufacturing

(1) Drawing a three-dimensional graph of the required part through software;

(2) selecting 15-53 μm aluminum alloy powder, drying, degassing and dehydrating in a vacuum drying oven, wherein the specific process is 80-120 ℃, and keeping the temperature for 4-6 h;

(3) putting the powder after vacuum drying into a powder supply cylinder of an SLM printer, starting the SLM printer, and starting printing operation;

preferably, the laser power is 300-450W, the scanning speed is 800-1700mm/s, the scanning distance is 0.10-0.20mm, the layer thickness is 0.03-0.05mm, and the substrate temperature is 50-150 ℃;

preferably, the scanning strategy is that the rotation angle between adjacent layers is one of 0 °, 45 °, 67 °, 90 °, and further preferably 45 ° or 67 °;

preferably, the scanning strategy is one or a mixture of chessboard scanning or line scanning;

preferably, the chessmen scanned on the chessboard are square or rectangular, and the area of each chessmen is 4-25mm²。

(4) And separating the printed sample piece from the substrate by wire cutting, and cleaning the residual powder.

(5) And carrying out heat treatment on the printed sample.

Preferably, the solid solution temperature is 550-.

Preferably, the medium is water, the water temperature is 20-30 ℃, and the transfer time is less than or equal to 10 s.

Preferably, the aging temperature is 220-350 ℃, the heat preservation time is 4-16h, and the air cooling is carried out.

As further preference; the laser power is 380W, the scanning speed is 1500mm/s, the scanning interval is 0.17mm, the layer thickness is 0.045mm, and the substrate temperature is 150 ℃.

The aluminum alloy powder is preferably applied to the field of selective laser melting additive manufacturing, preferably used in the fields of electron beam powder bed additive manufacturing, electron beam powder injection type additive manufacturing and the like;

the aluminum alloy powder of the invention can be used for additive manufacturing, and can also be used as powder materials for powder metallurgy, injection molding, hot isostatic pressing, welding repair and the like.

The invention develops the aluminum alloy powder for additive manufacturing, which does not contain rare earth, has low magnesium and high nickel for the first time. The product obtained by the invention has excellent mechanical property and good corrosion resistance.

The density of a sample formed by SLM of the high-strength aluminum alloy powder can reach more than 99%, the tensile strength of a sample piece in a printing state is more than or equal to 350MPa, the yield strength is more than or equal to 300MPa, and the elongation is more than or equal to 8%; after heat treatment, the tensile strength of the sample piece is more than or equal to 420MPa, the yield strength is more than or equal to 350MPa, and the elongation is more than or equal to 6%. After heat treatment, the tensile property of the material is more than or equal to 360MPa and the yield strength is more than or equal to 320MPa at the temperature of 300 ℃.

Drawings

FIG. 1 is a phase diagram of an Al-Cu alloy;

FIG. 2 is a phase diagram of Al-Ni alloy;

FIG. 3 is Al in combination with matrix aluminum₃Characterization of Ni nanoparticles.

The specific implementation mode is as follows:

example 1

The embodiment provides a special aluminum alloy for selective laser printing, which comprises the following components in percentage by mass: ni: 6.0%, Cu: less than or equal to 0.15 percent, Mg: less than or equal to 0.15 percent, Mn: less than or equal to 0.05 percent, Zr: less than or equal to 0.05 percent, Fe: less than or equal to 0.05 percent, Si: less than or equal to 0.05 percent and the balance of aluminum.

The preparation method comprises the following steps:

1. vacuum melting

(1) Weighing pure aluminum (the purity is more than or equal to 99.9 percent wt), pure magnesium (the purity is more than or equal to 99.9 percent wt) and other elements which are aluminum intermediate alloy, wherein the impurity content of the intermediate alloy is less than 0.1 percent, putting the weighed aluminum into a crucible of a vacuum intermediate frequency induction furnace,

(2) vacuum pumping is carried out to 10^-2Heating is started within Pa, argon or nitrogen (the gas purity is more than or equal to 99.995%) is filled into the reactor to the micro positive pressure (0.2MPa) after the reactor is heated to 320 ℃; when pure aluminum is completely melted and the temperature is 760 ℃, gradually adding aluminum intermediate alloy, and sequentially adding alloy elements according to the sequence of high and low melting points;

(3) and after the alloy is completely melted, adding hexachloroethane for degassing and stirring, fully and uniformly mixing the alloy solution under the action of a magnetic field, keeping the temperature and standing for 40min, and casting after standing to obtain the aluminum alloy cast ingot for gas atomization.

2. Supersonic inert gas vacuum atomization

(3) continuously increasing the power of the intermediate frequency furnace, wherein the heating rate is 20 ℃/s; when the temperature reaches 350 ℃, the vacuum pump is closed, and high-purity inert gas, namely one of argon and nitrogen, is fed;

(4) keeping the gas pressure in the smelting furnace at 0.2MPa, continuously heating to 800 ℃, and keeping for 60 min;

(5) starting an atomization gas circulation system to prepare for atomization;

preferably, the atomizing medium is argon;

preferably, the purity of the atomizing medium is more than or equal to 99.995 percent, and the dew point is lower than-60 ℃;

(6) starting an atomization system to prepare powder according to the operation specification, wherein the atomization pressure is controlled to be 6-8MPa, and the flow velocity of atomization gas is 2-3 times of the sound velocity;

(7) after the atomized powder is prepared and the powder is cooled, sieving and grading the powder by ultrasonic vibration, wherein the first sieve is 200 meshes, and the second sieve is 1340 meshes;

(8) the yield of the screened powder with the particle size of 15-74 mu m is more than or equal to 50 percent, the hollow rate of the powder is less than or equal to 0.2 percent, and the oxygen content is less than or equal to 300 ppm;

3. Selective laser melting additive manufacturing

(1) Drawing a three-dimensional graph of the required part through software;

(2) selecting 15-74 mu m aluminum alloy powder, drying, degassing and dehydrating in a vacuum drying oven, wherein the specific process is 100 ℃, and keeping the temperature for 5 hours;

wherein the laser power is 380W, the scanning speed is 1500mm/s, the scanning interval is 0.17mm, the layer thickness is 0.045mm, and the substrate temperature is 150 ℃;

wherein, the rotation angle between adjacent layers is 67 degrees, the scanning is carried out by a strip, and the width of the strip is 10 mm;

(4) separating the printed sample piece from the substrate by linear cutting, and cleaning the residual powder;

(5) carrying out heat treatment on the printed sample piece;

preferably, the solid solution temperature is 580 ℃, the heating rate is 5 ℃/min, the heat preservation time is 6h, and the vacuum or argon protection is carried out;

preferably, the medium is water, the water temperature is 25 ℃, and the transfer time is less than or equal to 10 s;

preferably, the aging temperature is 260 ℃, the heat preservation time is 8 hours, and air cooling is carried out;

through tests, the yield of the fine powder (15-74 μm) in the embodiment is 56.3%, the sphericity is 98.8%, the compactness of the sample formed by the SLM is 99.2%, the tensile strength of the sample in a printing state is 386MPa, the yield strength is 309MPa, and the elongation is 9.5%; after heat treatment, the tensile strength of the sample piece is 468MPa, the yield strength is 415MPa, and the elongation is 7.8%. After heat treatment, the tensile property of the material is 374MPa and the yield strength is 326MPa at the temperature of 300 ℃.

Example 2:

the embodiment provides a special aluminum alloy for selective laser printing, which comprises the following components in percentage by mass: ni: 5.4%, Cu: 1.2%, Mg: 0.6%, Mn: 0.2%, Zr: 0.1%, Fe: 0.05%, Si: 0.05% and the balance of aluminum. Other implementation conditions were the same as in example 1.

Through tests, the yield of the fine powder in the embodiment is 54.1%, the sphericity is 98.3%, the compactness of the sample formed by SLM is 99.4%, the tensile strength of the sample in a printing state is 394MPa, the yield strength is 346MPa, and the elongation is 8.7%; after heat treatment, the tensile strength of the sample piece is 519MPa, the yield strength is 447MPa, and the elongation is 6.9%. After heat treatment, the tensile property of the material is 413MPa and the yield strength is 346MPa at 300 ℃.

Example 3:

the embodiment provides a special aluminum alloy for selective laser printing, which comprises the following components in percentage by mass: ni: 4.8%, Cu: 1.8%, Mg: 2.2%, Mn: 0.3%, Zr: 0.15%, Fe: 0.05%, Si: 0.05% and the balance of aluminum. Other implementation conditions were the same as in example 1.

Through tests, the yield of the fine powder in the embodiment is 57.6%, the sphericity is 98.4%, the compactness of the sample formed by the SLM is 99.6%, the tensile strength of the sample in a printing state is 387MPa, the yield strength is 334MPa, and the elongation is 9.3%; after heat treatment, the tensile strength of the sample piece is 535MPa, the yield strength is 468MPa, and the elongation is 7.1%. After heat treatment, the tensile property of the material is 431MPa and the yield strength is 357MPa at the temperature of 300 ℃.

Comparative example 1:

the comparative example contains the following components in percentage by mass: ni: 1.0%, Cu: 5.0%, Mg: 2.2%, Mn: 0.3%, Zr: 0.15%, Fe: 0.05%, Si: 0.05% and the balance of aluminum. Other implementation conditions were the same as in example 1.

Through tests, the yield of the fine powder in the embodiment is 50.6%, the sphericity is 96.4%, the density of a sample formed by SLM is 98.3%, the tensile strength of a sample in a printing state is 278MPa, the yield strength is 235MPa, the elongation is 4.3%, and the micro-cracks of a material in the printing state are more; after heat treatment, the tensile strength of the sample piece is 255MPa, the yield strength is 168MPa, and the elongation is 3.1%, and due to the existence of printing cracks, the performance of the material is not increased or decreased after heat treatment. After heat treatment, the tensile property of the material is 223MPa and the yield strength is 157MPa at the temperature of 300 ℃.

Comparative example 2:

the material composition of example 2 was used, the printing process parameters were changed, the laser power was 260W, the scanning speed was 1000mm/s, and the rest was the same as example 2.

Through the test, the tensile strength of the sample piece in the printing state is 276MPa, the yield strength is 202MPa, and the elongation is 7.3%; after heat treatment, the tensile strength of the sample piece is 325MPa, the yield strength is 273MPa, and the elongation is 6.3%. After heat treatment, the tensile property of the material is 266MPa and the yield strength is 215MPa under the condition of 300 ℃.

Comparative example 3:

the material composition of example 2 was used, the printing process parameters were changed, the laser power was 350W, the scanning speed was 2000mm/s, and the rest was the same as example 2.

Through the test, the tensile strength of the sample piece in the printing state is 339MPa, the yield strength is 247MPa, and the elongation is 7.7%; after heat treatment, the tensile strength of the sample piece is 435MPa, the yield strength is 343MPa, and the elongation is 6.6%. After heat treatment, the tensile property of the material is 327MPa and the yield strength is 264MPa at the temperature of 300 ℃.

Comparative example 4:

samples were made in a conventional casting manner with the composition of example 2. The tensile strength of the sample piece is 144MPa, the yield strength is 106MPa, and the elongation is 17.7%; after heat treatment, the tensile strength of the sample piece is 332MPa, the yield strength is 234MPa, and the elongation is 16.9%. After heat treatment, the tensile property of the material is 231MPa and the yield strength is 164MPa at the temperature of 300 ℃. Compared with additive manufacturing, the performance of the aluminum-nickel alloy is greatly different.

Claims

1. The aluminum alloy for laser additive manufacturing is characterized in that: the aluminum alloy comprises the following components in percentage by mass: ni: 1.0-8.0%, Cu: 0-2.0%, Mg: 0-3.0%, Mn: 0-1.0%, Zr: 0-0.5%, Fe: 0-0.1%, Si: 0 to 0.1 percent of aluminum and the balance of aluminum.

2. The aluminum alloy for laser additive manufacturing according to claim 1, wherein: the aluminum alloy comprises the following components in percentage by mass: ni: 4.5-6.5%, Cu: 1.0% -1.5%, Mg: 0.5% -2.5%, Mn: 0.1% -0.3%, Zr: 0.1% -0.3%, Fe: 0.05 to 0.1%, Si: 0.05-0.1% of aluminum, and the balance of aluminum.

3. The aluminum alloy for laser additive manufacturing according to claim 2, wherein: the aluminum alloy comprises the following components in percentage by mass: ni: 5.0-6.0%, Cu: 0% -0.1%, Mg: 0% -0.1%, Mn: 0% -0.1%, Zr: 0-0.1%, Fe: 0-0.05%, Si: 0 to 0.05 percent of aluminum and the balance of aluminum.

4. The aluminum alloy for laser additive manufacturing according to claim 3, wherein: the aluminum alloy comprises the following components in percentage by mass: ni: 5.5-8.0%, Cu: 0.5% -1.8%, Mg: 0.5% -0.8%, Mn: 0.1% -1.0%, Zr: 0.1% -0.3%, Fe: 0.05 to 0.1%, Si: 0.05-0.1% of aluminum, and the balance of aluminum.

5. An aluminum alloy for laser additive manufacturing, characterized in that; the preparation of the powder comprises the following steps:

step one vacuum melting

(1) Weighing pure aluminum, pure magnesium and other elements which are aluminum intermediate alloy according to the component proportion of the aluminum alloy, wherein the impurity content of the intermediate alloy is less than 0.1 percent, putting the weighed aluminum into a crucible of a vacuum intermediate frequency induction furnace,

(2) vacuum pumping is carried out to 10^-2Within Pa, starting heating, and starting to fill argon or nitrogen to micro positive pressure after heating to the temperature of 300-350 ℃; when pure aluminum is completely melted and the temperature is 720-850 ℃, gradually adding aluminum intermediate alloy, and sequentially adding alloy elements according to the sequence of high and low melting points;

(3) after the alloy is completely melted, adding hexachloroethane for degassing and stirring, fully and uniformly mixing the alloy solution under the action of a magnetic field, keeping the temperature and standing for 40-50min, and casting after standing to obtain an aluminum alloy ingot for gas atomization;

step two supersonic inert gas vacuum atomization

(1) Putting the aluminum alloy ingot for gas atomization obtained in the step one into a crucible of an intermediate frequency furnace, and starting a vacuum pump;

(5) starting an atomization gas circulation system to prepare for atomization;

(6) starting an atomization system to prepare powder according to the operating specification, wherein the atomization pressure is controlled within the range of 4-10MPa, and the flow velocity of atomization gas is 1-3 times of the sound velocity;

(7) after the atomized powder preparation is finished and the powder is cooled, sieving and grading are carried out by ultrasonic vibration, wherein the first screen is 200-mesh and 350-mesh, and the second screen is 1000-mesh and 1500-mesh;

(8) the yield of the powder with the particle size of 15-74 mu m after screening is more than or equal to 50 percent, the hollow rate of the powder is less than or equal to 0.2 percent, and the oxygen content is less than or equal to 300 ppm;

6. The aluminum alloy for laser additive manufacturing according to claim 5, wherein: in the second step;

the atomization medium is the mixed gas of argon and helium, and the mixing ratio is 1: 0.1-0.5;

the purity of the atomizing medium is more than or equal to 99.995 percent, and the dew point is lower than-60 ℃.

7. Use of an aluminium alloy according to any one of claims 1 to 6 for laser additive manufacturing, wherein: after being made into powder, the aluminum alloy is used for at least one technical field of additive manufacturing, powder metallurgy, injection molding, hot isostatic pressing and welding repair.

8. Use of an aluminum alloy for laser additive manufacturing according to claim 7; the method is characterized in that: when the aluminum alloy powder is used for selective laser melting additive manufacturing, the method comprises the following steps:

(1) drawing a three-dimensional graph of the required part through software;

during printing, the laser power is controlled to be 300-450W, the scanning speed is 800-1700mm/s, the scanning distance is 0.10-0.20mm, the layer thickness is 0.03-0.05mm, and the substrate temperature is 50-150 ℃;

(5) and (3) heat treatment: carrying out solid solution treatment on the printed sample piece, adopting water quenching after the solid solution treatment, and carrying out aging treatment after the water quenching; the solid solution temperature is 550-; during water quenching, the water temperature is 20-30 ℃, and the transfer time is less than or equal to 10 s; and in the aging treatment, the aging temperature is controlled to be 220-350 ℃, the heat preservation time is 4-16h, and air cooling is carried out.

9. Use of an aluminum alloy for laser additive manufacturing according to claim 7; the method is characterized in that: 3D printing; the scanning strategy is that the rotation angle between adjacent layers is one of 0 degrees, 45 degrees, 67 degrees and 90 degrees, preferably 45 degrees or 67 degrees; the scanning strategy is one or a mixture of chessboard scanning and line scanning; the chess grids scanned by the chessboard are square or rectangular, and the area of the chess grids is 4-25mm²。

10. Use of an aluminum alloy for laser additive manufacturing according to claim 7; the method is characterized in that: the density of a sample formed by the aluminum alloy powder through the SLM can reach more than 99%, the tensile strength of the sample in a printing state is more than or equal to 350MPa, the yield strength is more than or equal to 300MPa, and the elongation is more than or equal to 8%; after heat treatment, the tensile strength of the sample piece is more than or equal to 420MPa, the yield strength is more than or equal to 350MPa, and the elongation is more than or equal to 6%. After the product obtained after 3D printing is subjected to heat treatment, the tensile property of the material at 300 ℃ is more than or equal to 360MPa, and the yield strength is more than or equal to 320 MPa.