Endogenous titanium carbide reinforced ultrahigh-strength aluminum alloy and green laser directional energy deposition method thereof

Abstract

The invention discloses an endogenous titanium carbide reinforced ultrahigh-strength aluminum alloy and a green laser directional energy deposition method thereof, and relates to the technical field of aluminum alloy preparation, and the preparation method comprises the following steps: preparing an aluminum-titanium-carbon nanotube system compact; the aluminum-titanium-carbon nano tube system pressed blank is immersed into an aluminum alloy melt, titanium carbide pre-dispersion is carried out based on an in-situ reaction in the melt, and an endogenous titanium carbide reinforced aluminum alloy cast ingot is obtained; annealing and drawing the endogenous titanium carbide reinforced aluminum alloy cast ingot to obtain an endogenous titanium carbide reinforced aluminum alloy wire; the internally-coated titanium carbide aluminum alloy powder is prepared from the endogenous titanium carbide reinforced aluminum alloy wire, and the titanium carbide reinforced aluminum alloy is obtained through green laser directional energy deposition. The method is reasonable in technological process, has the advantages of being low in cost and short in period, and provides an innovative path for preparation of the high-performance additive manufacturing aluminum alloy.

Description

Technical Field

[0001] This invention relates to an endogenous titanium carbide-reinforced ultra-high strength aluminum alloy and its green laser-directed energy deposition method, belonging to the field of aluminum alloy preparation technology. Background Technology

[0002] In recent years, cutting-edge fields such as aerospace have created an urgent demand for high-performance, lightweight metal additive manufacturing technologies. Laser-directed energy deposition (LDED) technology for aluminum alloys, due to its high deposition efficiency, significant lightweight advantages, and suitability for forming large components, has become one of the key directions driving the upgrading of aerospace equipment. In particular, low-cost, high-strength 7xxx series aluminum alloys have shown great potential in achieving a synergistic effect of lightweighting and high performance in key components.

[0003] However, LDED forming of 7xxx series aluminum alloys still faces the following key challenges restricting the improvement of their strength and plasticity: i) Poor molten pool stability, manifested by low absorption of traditional infrared lasers, high thermal conductivity, severe burn-off of low-boiling-point elements such as Zn and Mg, and difficulty in effectively controlling porosity; ii) High residual stress and poor formability, due to the wide solidification range and large temperature gradient, which easily induces columnar crystal growth and leads to cracking; iii) Insufficient precipitation kinetics, the severe element burn-off during laser forming process weakens the nucleation ability of precipitated phases, resulting in low precipitation strengthening efficiency. Therefore, synergistically improving forming quality and precipitation strengthening effect is the core path to overcome the bottlenecks in the mechanical properties and engineering applications of this material.

[0004] Currently, adding reinforcing particles is the mainstream method for controlling the formability and strength of LDED 7xxx series aluminum alloys. It can effectively promote heterogeneous nucleation, inhibit columnar epitaxial growth, refine eutectic structure, and improve density. However, existing studies have reported that the yield strength and tensile strength of heat-treated particle-reinforced 7xxx series aluminum alloys are still lower than the ASTM standard. The reasons for this are twofold. First, the amount of added particles (1~10 wt.%) used in existing methods easily leads to local particle enrichment, hindering the full melting of aluminum powder and weakening the particle strengthening effect. At the same time, the oxide film on the surface of aluminum powder severely deteriorates the wettability between the reinforcing particles and the matrix, resulting in prominent problems of "difficult dispersion, low efficiency, and poor interfacial bonding" of particles. Second, the extremely low energy coupling efficiency between infrared laser and aluminum alloy forces the process to use high-power laser input, which not only causes severe turbulence in the molten pool and severe burn-off of key alloying elements such as Mg and Zn, but also leads to insufficient precipitation kinetics during subsequent aging, making it difficult for key nano-precipitates such as η' to nucleate and causing their size to coarsen. Although powder pre-alloying can be used to compensate for element burn-off, this method is prone to inducing molten pool vapor jetting during LDED, resulting in a significant increase in porosity.

[0005] Therefore, developing novel reinforced particle / 7xxx series aluminum alloy composite powders with internal coating structures to promote uniform particle dispersion, enhance process controllability, and improve particle / aluminum matrix interfacial bonding has become an important research direction for particle-reinforced LDED aluminum alloys. At the same time, there is an urgent need to introduce high-efficiency new energy sources to overcome the inherent technical bottlenecks of infrared lasers: "high power demand – molten pool instability – insufficient precipitation strengthening."

[0006] In recent years, green laser additive manufacturing technology, as a cutting-edge field in high-reflectivity metal forming, has achieved a series of successful cases in improving forming quality. Developing new high-reflectivity metal additive manufacturing materials based on the synergistic effect of green laser LDED process and internally coated reinforcing particles demonstrates significant technical feasibility and is expected to provide a breakthrough path for the preparation of high-performance 7xxx series aluminum alloys, with broad application prospects. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an endogenous titanium carbide-reinforced ultra-high strength aluminum alloy and its green laser directional energy deposition method. The process flow is reasonable and has the advantages of low cost and short cycle, providing an innovative path for the preparation of high-performance additive manufacturing aluminum alloys.

[0008] To achieve the above objectives, the present invention is implemented using the following technical solution: On one hand, the present invention provides a green laser-directed energy deposition method for endogenous titanium carbide-reinforced ultra-high strength aluminum alloys, comprising: Preparation of aluminum-titanium-carbon nanotube system compacts; The aluminum-titanium-carbon nanotube system compact is immersed in the aluminum alloy melt, and titanium carbide pre-dispersion is carried out based on the in-situ reaction in the melt to obtain an endogenous titanium carbide reinforced aluminum alloy ingot. An annealing and drawing process was performed on the ingot of endogenous titanium carbide reinforced aluminum alloy to obtain endogenous titanium carbide reinforced aluminum alloy wire. Intrinsically coated titanium carbide aluminum alloy powder was prepared from intrinsic titanium carbide reinforced aluminum alloy wire, and ultra-high strength aluminum alloy reinforced with intrinsic titanium carbide was obtained by green laser directional energy deposition.

[0009] Furthermore, the preparation of the aluminum-titanium-carbon nanotube system compact includes: Aluminum-titanium-carbon nanotube powder was ball-milled and activated to obtain ball-milled activated aluminum-titanium-carbon nanotube powder. The ball-milled and activated aluminum-titanium-carbon nanotube powder was mixed with titanium powder and aluminum powder to obtain a mixed powder. The mixed powder was ball-milled and then subjected to hydraulic pressure to obtain an aluminum-titanium-carbon nanotube system compact.

[0010] Furthermore, the particle size of the aluminum-titanium-carbon nanotube powder is 20-100 micrometers, the particle size of the titanium powder is 20-30 micrometers, and the particle size of the aluminum powder is 10-20 micrometers. And / or, in the aluminum-titanium-carbon nanotube system compact, the mass fraction of aluminum powder is 70~80% and the mass fraction of titanium powder is 16.0~22.5%.

[0011] Furthermore, the conditions for ball milling activation include ball milling at 200-300 r / min for 1-3 hours; And / or, the ball milling conditions include ball milling at 50~100 r / min for 20~50 hours; And / or, the hydraulic pressure includes: The mixed powder is wrapped and sealed with aluminum foil and placed in a mold. A unidirectional axial pressure of 50-100 MPa is applied to it at room temperature using a hydraulic press and the pressure is maintained for 1-3 minutes.

[0012] Furthermore, the step of immersing the aluminum-titanium-carbon nanotube system compact into the aluminum alloy melt, and pre-dispersing titanium carbide based on the in-situ reaction within the melt to obtain an endogenous titanium carbide-reinforced aluminum alloy ingot includes: Aluminum alloy melt is prepared from aluminum alloy bars; After preheating, the aluminum-titanium-carbon nanotube system compact is immersed in aluminum alloy melt and ultrasonically dispersed to obtain ceramic aluminum alloy melt. The ceramic aluminum alloy melt is injected into a preheated steel mold and cooled to obtain an endogenous titanium carbide reinforced aluminum alloy ingot.

[0013] Furthermore, the aluminum alloy bar is made of 7075 aluminum alloy, which includes 5~6.5wt% zinc, 2.0~3.0wt% magnesium, 1.0~2.5wt% copper, 0.15~0.30wt% chromium, 0.15~0.3wt% silicon, 0.20~0.45wt% iron, 0.10~0.30wt% manganese, and no more than 0.20wt% titanium, with the remainder being aluminum; And / or, the method for preparing aluminum alloy melt from aluminum alloy bars includes: The aluminum alloy bar is heated to 1073~1173K and held at that temperature for 30~50 minutes. After the aluminum alloy bar is completely melted, a slag remover of 0.05~0.15wt% of the total mass of the melt is added for refining. After slag removal, the temperature is held for another 2~5 minutes. The slag remover includes 40~50wt% KCl, 35~40wt% MgCl2, 6~8wt% AlF3, 12~15wt% Na3AlF6, 6~9wt% Mg3N2, 3~5wt.% Na2CO3, and 3~5wt.% C2Cl6. And / or, the preheating of the aluminum-titanium-carbon nanotube system compact followed by immersion in an aluminum alloy melt, and ultrasonic dispersion to obtain a ceramic aluminum alloy melt, comprises: The aluminum alloy melt was heated to 1023~1223K, and the aluminum-titanium-carbon nanotube system compact was preheated at 7772~823K. The preheated aluminum-titanium-carbon nanotube system compact was immersed in molten aluminum alloy to generate ceramic particles within the alloy. After the momentary flashover, the mixture was held for at least 1 minute, stirred, and then ultrasonically dispersed at 20–25 kHz to obtain a ceramic-aluminum alloy melt. The mass of the aluminum-titanium-carbon nanotube system compact accounted for 0.50–3.33 wt% of the ceramic-aluminum alloy melt, and the mass of the ceramic particles accounted for 0.15–1.00 wt% of the ceramic-aluminum alloy melt. And / or, the temperature range when the ceramic aluminum alloy melt is injected into the preheated steel mold is 973~1023K.

[0014] Furthermore, the annealing and drawing processes include: The endogenous titanium carbide reinforced aluminum alloy ingot was homogenized at 743~763K for 10~15 hours; The homogenized endogenous titanium carbide reinforced aluminum alloy ingot is hot extruded at 723~773K to obtain endogenous titanium carbide reinforced aluminum alloy profiles. The endogenous titanium carbide reinforced aluminum alloy profile is subjected to a first annealing treatment, a first drawing treatment, a second annealing treatment, a second drawing treatment, and a third annealing treatment in sequence to obtain endogenous titanium carbide reinforced aluminum alloy wire. And / or, the conditions for the first annealing treatment, the second annealing treatment, and the third annealing treatment are all stress-relief annealing treatment at 473~493K for 2.5~3.5 hours; The first drawing process involves successively reducing the cross-sectional diameter of the endogenous titanium carbide reinforced aluminum alloy profile by 2-3 mm. The second drawing process involves successively reducing the cross-sectional diameter of the endogenous titanium carbide reinforced aluminum alloy profile by 1.5~2.0 mm.

[0015] Furthermore, the preparation of in-situ titanium carbide-coated aluminum alloy powder from endogenous titanium carbide-reinforced aluminum alloy wire, and the obtaining of titanium carbide-reinforced aluminum alloy using green laser directional energy deposition, includes: Using 7075 aluminum alloy as the starting material, a high-frequency alternating magnetic field is used to generate eddy currents inside the starting material, causing it to melt and form a molten pool. The endogenous titanium carbide reinforced aluminum alloy wire is continuously fed into the molten pool. After the endogenous titanium carbide reinforced aluminum alloy wire is fully melted, the molten pool is maintained at 1023~1123K. The molten pool is formed into a liquid flow with a diameter of 2-5 mm by guiding the flow, and then torn into droplets with a diameter of 10-200 micrometers by the impact of argon gas flow. After cooling and solidification, spherical powder is obtained. Titanium carbide reinforced aluminum alloy is obtained by performing green laser directional energy deposition, solution treatment, water quenching, and two-stage aging treatment on spherical powder. The conditions and parameters of the green laser directional energy deposition include a green laser power of 900W and a scanning speed of 1500mm / min.

[0016] Furthermore, the magnetic induction intensity of the high-frequency alternating magnetic field is 60~100mT; And / or, before performing green laser directional energy deposition on spherical powder, the particle size of the spherical powder is sieved to select a particle size range of 53~150 micrometers; And / or, the conditions for the solution treatment include treatment at 743~763K for 1~2 hours; And / or, the condition parameters for the two-stage aging process include first processing at 353~403K for 5 hours, and then processing at 403~433K for 14 hours.

[0017] On the other hand, the present invention also provides an endogenous titanium carbide reinforced ultra-high strength aluminum alloy, which is prepared by the green laser directional energy deposition method for endogenous titanium carbide reinforced ultra-high strength aluminum alloy as described in any of the above claims.

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention combines in-melt reaction and powder atomization to encapsulate titanium carbide (TiC) particles within 7075 aluminum alloy powder, avoiding the drawbacks of agglomeration of externally added particles and poor controllability of endogenous reinforcing particles during additive manufacturing. Furthermore, by employing a green laser with low reflectivity and adding only 0.15–1.00 wt.% trace amounts of ceramic particles, the room-temperature yield strength and tensile strength of laser-directed energy deposition (LDED) 7075 aluminum alloy are significantly improved. In addition, considerable ductility is maintained while strength is increased. TiC particles released from 7075 aluminum alloy powder are uniformly dispersed in the formed block, significantly playing a role in grain refinement and dislocation strengthening. At the same time, the low reflectivity of aluminum alloy powder to green laser significantly reduces the burn-off of important alloying elements such as Zn and Mg, and significantly improves the precipitation kinetics during heat treatment. Combined with the two-stage aging system, it promotes the high-density synergistic precipitation of multi-level nanophases, playing an efficient orovan strengthening role, and finally obtaining laser-directed mass deposition 7075 aluminum alloy with excellent strength and toughness. This invention uses 7075 aluminum alloy as the matrix and generates nano-TiC ceramic reinforcing phase in situ by igniting an Al-Ti-CNTs reaction system in the melt. The resulting composite material has uniformly dispersed TiC particles. Combined with green laser directional energy deposition and subsequent two-stage aging, elemental burn-off is effectively suppressed, precipitation kinetics are accelerated, and the microstructure and mechanical properties of additively manufactured high-strength aluminum alloys are significantly improved, resulting in a simultaneous increase in yield strength and tensile strength while maintaining considerable plasticity. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the analysis of 0.15wt.% endogenous TiC-reinforced green laser-directed energy deposition 7075 aluminum alloy prepared in Example 1 of the present invention, wherein (a) is a schematic diagram of transmission analysis; and (b) is a schematic diagram of X-ray diffraction analysis. Figure 2 This is a schematic diagram of the morphology scanning analysis of the 0.15 wt.% endogenous TiC-enhanced green laser-directed energy deposition 7075 aluminum alloy prepared in Example 1 of the present invention; Figure 3 This is a schematic diagram of the cross-sectional composition analysis of the 0.50 wt.% endogenous TiC-reinforced green laser-directed energy deposition 7075 aluminum alloy prepared in Example 2 of the present invention; Figure 4 This is a schematic diagram of the laser reflectivity of the 1.00 wt.% endogenous TiC-enhanced green laser-directed energy deposition 7075 aluminum alloy prepared in Example 3 of the present invention; Figure 5 This is a schematic diagram comparing the real-time monitoring results of element burn-off during energy deposition between the 1.00 wt.% endogenous TiC-reinforced green laser-directed energy deposition 7075 aluminum alloy prepared in Example 3 of the present invention and the infrared laser-directed energy deposition 7075 aluminum alloy prepared in Comparative Example 1. Figure 6 This is a schematic diagram comparing the room temperature tensile properties of the 1.00 wt.% endogenous TiC-reinforced green laser-directed energy deposition 7075 aluminum alloy prepared in Example 3 of the present invention with those of existing laser-directed energy deposition aluminum alloys; Figure 7 This is a schematic diagram of green laser directional energy deposition in some embodiments of the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0021] Example 1

[0022] This invention provides a method for preparing 0.15 wt.% endogenous TiC-reinforced green laser-directed energy deposition 7075 aluminum alloy, comprising the following steps: Step 1: Preparation of Al-Ti-CNTs system compacts (1) Ball milling activation pretreatment of CNT powder with an initial length of 70 μm: The powder was placed in a ball milling jar and fed at a ball-to-material ratio of 50:1. The powder was ball milled for 2 hours at a speed of 250 r / min.

[0023] (2) Weigh out a certain amount of Al powder with a particle size of 15 μm and Ti powder with a particle size of 30 μm for later use.

[0024] (3) Weigh Ti powder and ball-milled activated CNTs powder at a mass ratio of 3.993:1. This ratio is intended to make the TiC phase generated by the reaction account for 20.0 wt.% of the compact. Then, mix the above powder with Al powder to finally prepare 400g of total mixed powder.

[0025] (4) Take 300 g of mixed powder and place it in the ball mill jar of the mixer. Set the rotation speed to 80 r / min and mix for 36 h. (5) After wrapping and sealing the mixed powder with thin aluminum foil, place it in a stainless steel mold. Then apply unidirectional axial pressure at room temperature using a hydraulic press: hold at 85 MPa for 3 minutes to finally obtain a cylindrical compact with a size of 25 mm × 45 mm and a density of 80%.

[0026] Step 2: In-situ reaction within the melt and pre-dispersion of TiC particles (1) Place a dry crucible in a crucible-type resistance melting furnace and add the weighed 7075 aluminum alloy bar stock; the bar stock composition is: aluminum Al: balance; zinc Zn: 5.8wt.%; magnesium Mg: 2.4wt.%; copper Cu: 1.9wt.%; chromium Cr: 0.23wt.%; silicon Si: 0.24wt.%; iron Fe: 0.35wt.%; manganese Mn: 0.18wt.%; titanium Ti: 0.16wt.%; heat the melt to 1123K, and then hold it in this temperature range for 45 minutes for melting; (2) After the bar stock has completely melted, add 0.12 wt.% of a slag remover to the total mass of the melt for refining. After the slag removal operation is completed, continue to keep it at the temperature for 3 minutes.

[0027] (3) The melting furnace was heated to 1123 K. At the same time, the Al-Ti-CNTs system compact obtained in step one was preheated at 803 K for 0.5 h. Then, the compact was pressed into the melt in the crucible, and the amount added was controlled at 0.50 wt.% of the total mass of the melt. After this process, the final content of ceramic particles in the alloy was 0.15 wt.%.

[0028] (4) After the Al-Ti-CNTs system compact is immersed, wait for the instantaneous flash phenomenon it causes to end, and continue to immerse it in the melt for at least 1 minute, followed by mechanical stirring for 4 minutes.

[0029] (5) Lower the ultrasonic probe to 5 cm above the surface of the melt and preheat for 6 minutes. Then turn on the ultrasonic equipment and use the ultrasonic probe at a frequency of 21 kHz to ultrasonically disperse the ceramic particles in the melt for 3 minutes to ensure uniform dispersion. After the treatment, remove the probe and keep the melt warm for another 2 minutes.

[0030] (6) The temperature of the melt was monitored using a thermocouple. When it reached 1023 K, it was poured into a preheated steel mold. After cooling, an endogenous TiC-reinforced 7075 aluminum alloy ingot with a diameter of 82 mm × 90 mm was obtained.

[0031] Step 3: Preparation of endogenous TiC-reinforced 7075 aluminum alloy wire (1) Homogenization treatment: Homogenize at 753 K for 12 h.

[0032] (2) Hot extrusion: The homogenized ingot is hot extruded at 773 K with an extrusion ratio of 67.2:1 to obtain an endogenous TiC reinforced 7075 aluminum alloy profile with a cross section of Φ10 mm×1000 mm.

[0033] (3) First annealing: The hot-extruded endogenous TiC reinforced 7075 aluminum alloy profile is subjected to stress-relief annealing at 493 K for 3 hours.

[0034] (4) First round of drawing: The annealed profile is drawn on a continuous wire drawing machine in the order of 10.00 mm → 8.00 mm → 6.00 mm in cross-sectional diameter, decreasing by 2 mm each time.

[0035] (5) Second annealing: The endogenous TiC reinforced 7075 aluminum alloy filaments after the first round of drawing were subjected to stress relief annealing at 493 K for 3 hours.

[0036] (6) Second round of drawing: The filaments after the second annealing are drawn on a continuous drawing machine in the order of 6.00 mm → 4.50 mm → 3.00 mm → 1.50 mm, decreasing by 1.5 mm each time.

[0037] (7) Third annealing: The endogenous TiC reinforced 7075 aluminum alloy wire after the second round of drawing was subjected to stress relief annealing at 493 K for 3 hours to obtain Φ1.5 mm endogenous TiC reinforced 7075 aluminum alloy wire.

[0038] Step 4: Preparation of TiC7075 aluminum alloy powder with internal coating and its green laser-directed energy deposition like Figure 7 As shown, (1) Preparation of the wire feeding system: The spool with Φ1.5 mm endogenous TiC reinforced 7075 aluminum alloy wire is installed on the wire feeding mechanism, and the wire end is passed through the guide device to prepare to be fed into the crucible; (2) Generating an alternating magnetic field: The alternating current through the 30 kW / 30 kHz induction coil will generate a high-frequency alternating magnetic field with a magnetic induction intensity of 80 mT in the crucible area inside the coil. (3) Initial melting and continuous wire feeding: 100 g of 7075 aluminum alloy is placed in the crucible as the "starting material". The magnetic field generates eddy currents inside it, causing the starting material to heat up and melt rapidly, forming a molten pool. Then the wire feeder is started to continuously feed the endogenous TiC reinforced 7075 aluminum alloy wire into the molten pool at a speed of 10 r / min.

[0039] (4) Melt holding and refining: After the filaments are fully melted, the molten pool is kept at 1063 K.

[0040] (5) Melt flow: After the temperature of the molten pool stabilizes, open the flow guide pipe at the bottom of the crucible to form a stable and continuous liquid flow with a diameter of 3.5 mm, which flows into the top of the atomizing tower.

[0041] (6) Droplet formation: After the metal liquid flows out of the guide tube, it is impacted by the high-speed gas flow of 99.99% high-purity argon surrounding it, which tears the liquid flow into tiny droplets with a diameter of 10~200 μm.

[0042] (7) Cooling and solidification: Under the action of gravity, the spherical droplets fly downward in the 7m atomization tower, rapidly cool and solidify into solid spherical powder particles.

[0043] (8) Powder collection and sieving: The completely cooled powder particles fall into the collection tank at the bottom of the atomizing tower and are sieved by a vibrating sieve according to different particle size ranges (15~53μm, 53~150μm) to meet the specific requirements of different applications.

[0044] (9) Additive manufacturing and heat treatment: Powder with a particle size of 53-150μm was selected for green laser directional energy deposition. The green laser power used was 900W and the scanning speed was 1500mm / min. The obtained bulk material was then subjected to a solid solution treatment at 743K for 1 hour and immediately quenched in water. Finally, it was subjected to a two-stage aging process at 383K for 5 hours and 423K for 14 hours to finally prepare 0.15wt.% endogenous TiC-reinforced green laser directional energy deposition 7075 aluminum alloy.

[0045] Transmission electron microscopy analysis of 0.15 wt.% endogenous TiC-enhanced green laser-directed energy deposition 7075 aluminum alloy is as follows: Figure 1 As shown, the endogenous TiC has a rounded morphology and good bonding with the matrix interface. X-ray diffraction analysis further confirms the formation of an in-situ TiC phase within the melt. Figure 2 The morphology of 0.15wt.% endogenous TiC-enhanced green laser-directed energy deposition 7075 aluminum alloy is regular and the size distribution is uniform, with no obvious impurities observed.

[0046] Example 2

[0047] This embodiment provides a method for preparing 7075 aluminum alloy with 0.50 wt.% endogenous TiC-enhanced green laser-directed energy deposition, including the following steps: Step 1: Preparation of Al-Ti-CNTs system compacts (1) Ball milling activation pretreatment of CNT powder with an initial length of 90 μm: The powder was placed in a ball milling jar and fed at a ball-to-material ratio of 50:1. The powder was ball milled for 2 hours at a speed of 250 r / min. (2) Weigh out a certain amount of Al powder with a particle size of 15μm and Ti powder with a particle size of 27μm for later use; (3) Weigh Ti powder and ball-milled activated CNTs powder at a mass ratio of 3.993:1. This ratio is intended to make the TiC phase generated by the reaction account for 30.0 wt.% of the compact. Then, mix the above powder with Al powder to finally prepare 400g of total mixed powder; (4) Place 300 g of the mixed powder in the ball mill jar of the mixer, set the rotation speed to 85 r / min, and mix for 48 h; (5) After wrapping and sealing the mixed powder with thin aluminum foil, place it in a stainless steel mold. Then apply unidirectional axial pressure at room temperature using a hydraulic press: hold at 92 MPa for 3 minutes to finally obtain a cylindrical compact with a size of 25 mm × 33 mm and a density of 77%.

[0048] Step 2: In-situ reaction within the melt and pre-dispersion of TiC particles (1) Place a dry crucible in a crucible-type resistance melting furnace and add the weighed 7075 aluminum alloy bar. The bar composition is as follows: Aluminum Al: balance; Zinc Zn: 6.2wt.%; Magnesium Mg: 2.6wt.%; Copper Cu: 2.0wt.%; Chromium Cr: 0.27wt.%; Silicon Si: 0.19wt.%; Iron Fe: 0.35wt.%; Manganese Mn: 0.23wt.%; Titanium Ti: 0.14wt.%; Heat the melt to 1073 K and then heat it in this temperature range for 35 minutes.

[0049] (2) After the bar stock has completely melted, add 0.05 wt.% of a slag remover to the total mass of the melt for refining. After the slag removal operation is completed, continue to keep it at the temperature for 5 minutes.

[0050] (3) The melting furnace was heated to 1223 K. Simultaneously, the Al-Ti-CNTs system compact obtained in step one was preheated at 773 K for 0.5 h. Subsequently, the compact was pressed into the melt in the crucible, with the addition amount controlled at 1.67 wt.% of the total melt mass. Through this process, the final ceramic particle content in the alloy was 0.50 wt.%.

[0051] (4) After the Al-Ti-CNTs system compact is immersed, wait for the instantaneous flash phenomenon it causes to end, and continue to immerse it in the melt for at least 1 minute, followed by mechanical stirring for 3 minutes.

[0052] (5) Lower the ultrasonic probe to 10 cm above the surface of the melt and preheat for 8 minutes. Then turn on the ultrasonic equipment and use the ultrasonic probe at a frequency of 25 kHz to ultrasonically disperse the ceramic particles in the melt for 5 minutes to ensure uniform dispersion. After the treatment, remove the probe and keep the melt warm for another 3 minutes.

[0053] (6) The temperature of the melt was monitored by thermocouples. When it reached 1023 K, it was poured into a preheated steel mold. After cooling, an endogenous TiC-reinforced 7075 aluminum alloy ingot with a diameter of 82 mm × 80 mm was obtained.

[0054] Step 3: Preparation of endogenous TiC-reinforced 7075 aluminum alloy wire (1) Homogenization treatment: Homogenize at 763 K for 15 h.

[0055] (2) Hot extrusion: The homogenized ingot is hot extruded at 773 K with an extrusion ratio of 67.2:1 to obtain an endogenous TiC reinforced 7075 aluminum alloy profile with a cross section of Φ10 mm×1100 mm.

[0056] (3) First annealing: The hot-extruded endogenous TiC reinforced 7075 aluminum alloy profile is subjected to stress-relief annealing at 473 K for 3 hours.

[0057] (4) First round of drawing: The annealed profile is drawn on a continuous wire drawing machine in the order of 10.00 mm → 8.00 mm → 6.00 mm in cross-sectional diameter, decreasing by 2 mm each time; (5) Second annealing: The endogenous TiC reinforced 7075 aluminum alloy filaments after the first round of drawing were subjected to stress-relief annealing at 473 K for 3 hours.

[0058] (6) Second round of drawing: The filaments after the second annealing are drawn on a continuous drawing machine in the order of 6.00 mm → 4.50 mm → 3.00 mm → 1.50 mm, decreasing by 1.5 mm each time.

[0059] (7) Third annealing: The endogenous TiC reinforced 7075 aluminum alloy wire after the second round of drawing was subjected to stress relief annealing at 473 K for 3 hours to obtain Φ1.5 mm endogenous TiC reinforced 7075 aluminum alloy wire.

[0060] Step 4: Preparation of TiC7075 aluminum alloy powder with internal coating and its green laser-directed energy deposition (1) Preparation of the wire feeding system: Install the spool with Φ1.5 mm endogenous TiC reinforced 7075 aluminum alloy wire on the wire feeding mechanism, and pass the wire end through the guide device to prepare to feed it into the crucible.

[0061] (2) Generating an alternating magnetic field: The alternating current through the 30 kW / 30 kHz induction coil will generate a high-frequency alternating magnetic field with a magnetic induction intensity of 75 mT in the crucible area inside the coil.

[0062] (3) Initial melting and continuous wire feeding: 100 g of 7075 aluminum alloy is placed in the crucible as the "starting material". The magnetic field generates eddy currents inside it, causing the starting material to heat up and melt rapidly, forming a molten pool. Then the wire feeder is started to continuously feed the endogenous TiC reinforced 7075 aluminum alloy wire into the molten pool at a speed of 10 r / min.

[0063] (4) Melt holding and refining: After the filaments are fully melted, the molten pool is kept at 1123 K.

[0064] (5) Melt flow: After the temperature of the molten pool stabilizes, open the flow guide pipe at the bottom of the crucible to form a stable and continuous liquid flow with a diameter of 3 mm, which flows into the top of the atomizing tower.

[0065] (6) Droplet formation: After the metal liquid flows out of the guide tube, it is impacted by the high-speed gas flow of 99.99% high-purity argon surrounding it, which tears the liquid flow into tiny droplets with a diameter of 10~200 μm.

[0066] (7) Cooling and solidification: Under the action of gravity, the spherical droplets fly downward in the 7m atomization tower, rapidly cool and solidify into solid spherical powder particles.

[0067] (8) Powder collection and sieving: The completely cooled powder particles fall into the collection tank at the bottom of the atomizing tower and are sieved by a vibrating sieve according to different particle size ranges (15~53μm, 53~150μm) to meet the specific requirements of different applications.

[0068] (9) Additive manufacturing and heat treatment: Powder with a particle size of 53~150μm was selected for green laser directional energy deposition. The green laser power used was 900W and the scanning speed was 1500mm / min. Then, the obtained bulk material was subjected to solid solution treatment at 763K for 1.5 hours and immediately water quenched. Finally, it was subjected to two-stage aging at 383K for 5 hours and 423K for 14 hours to finally prepare 0.50wt.% endogenous TiC-reinforced green laser directional energy deposition 7075 aluminum alloy.

[0069] The elemental distribution of the powder cross section of 0.50 wt.% endogenous TiC-enhanced green laser-directed energy deposition 7075 aluminum alloy is shown in the figure. Figure 3 As shown, TiC particles are uniformly dispersed within the powder without obvious agglomeration.

[0070] Example 3

[0071] This embodiment provides a method for preparing 1.00 wt.% endogenous TiC-enhanced green laser-directed energy deposition 7075 aluminum alloy, including the following steps: Step 1: Preparation of Al-Ti-CNTs system compacts (1) Ball milling activation pretreatment of CNT powder with an initial length of 65 μm: The powder was placed in a ball milling jar and fed at a ball-to-material ratio of 50:1. The powder was ball milled for 2 hours at a speed of 250 r / min.

[0072] (2) Weigh out a certain amount of Al powder with a particle size of 14 μm and Ti powder with a particle size of 22 μm for later use.

[0073] (3) Weigh Ti powder and ball-milled activated CNTs powder at a mass ratio of 3.993:1. This ratio is intended to make the TiC phase generated by the reaction account for 20.0 wt.% of the compact. Then, mix the above powder with Al powder to finally prepare 300g of total mixed powder.

[0074] (4) Place 300 g of mixed powder in the ball mill jar of the mixer, set the rotation speed to 70 r / min, and mix for 48 h.

[0075] (5) After wrapping and sealing the mixed powder with thin aluminum foil, place it in a stainless steel mold. Then apply unidirectional axial pressure at room temperature using a hydraulic press: hold at 65 MPa for 2 minutes to finally obtain a cylindrical compact with a size of 25 mm × 35 mm and a density of 73%.

[0076] Step 2: In-situ reaction within the melt and pre-dispersion of TiC particles (1) Place a dry crucible in a crucible-type resistance melting furnace and add the weighed 7075 aluminum alloy bar; the bar composition is: aluminum Al: balance; zinc Zn: 6.2wt.%; magnesium Mg: 2.6wt.%; copper Cu: 1.7wt.%; chromium Cr: 0.22wt.%; silicon Si: 0.27wt.%; iron Fe: 0.36wt.%; manganese Mn: 0.26wt.%; titanium Ti: 0.11wt.%; heat the melt to 1073K and then hold it in this temperature range for 30 minutes.

[0077] (2) After the bar stock has completely melted, add 0.12 wt.% of a slag remover to the total mass of the melt for refining. After the slag removal operation is completed, continue to keep it at the temperature for 3 minutes.

[0078] (3) The melting furnace was heated to 1223 K. At the same time, the Al-Ti-CNTs system compact obtained in step one was preheated at 803 K for 0.5 h. Then, the compact was pressed into the melt in the crucible, and the amount added was controlled at 3.33 wt.% of the total mass of the melt. After this process, the final content of ceramic particles in the alloy was 1.00 wt.%.

[0079] (4) After the Al-Ti-CNTs system compact is immersed, wait for the instantaneous flash phenomenon it causes to end, and continue to immerse it in the melt for at least 1 minute, followed by mechanical stirring for 3 minutes.

[0080] (5) Lower the ultrasonic probe to 8 cm above the surface of the melt and preheat for 6 minutes. Then turn on the ultrasonic equipment and use the ultrasonic probe at a frequency of 22 kHz to ultrasonically disperse the ceramic particles in the melt for 3 minutes to ensure uniform dispersion. After the treatment, remove the probe and keep the melt warm for another 3 minutes.

[0081] (6) The temperature of the melt was monitored by thermocouples. When it reached 1003 K, it was poured into a preheated steel mold. After cooling, an endogenous TiC-reinforced 7075 aluminum alloy ingot with a diameter of 82 mm × 90 mm was obtained.

[0082] Step 3: Preparation of endogenous TiC-reinforced 7075 aluminum alloy wire (1) Homogenization treatment: Homogenize at 753 K for 12 h.

[0083] (2) Hot extrusion: The homogenized ingot is hot extruded at 723-773 K with an extrusion ratio of 67.2:1 to obtain an endogenous TiC reinforced 7075 aluminum alloy profile with a cross section of Φ10 mm×1400 mm.

[0084] (3) First annealing: The hot-extruded endogenous TiC reinforced 7075 aluminum alloy profile is subjected to stress-relief annealing at 493 K for 3 hours.

[0085] (4) First round of drawing: The annealed profile is drawn on a continuous wire drawing machine in the order of 10.00 mm → 8.00 mm → 6.00 mm in cross-sectional diameter, decreasing by 2 mm each time.

[0086] (5) Second annealing: The endogenous TiC reinforced 7075 aluminum alloy filaments after the first round of drawing were subjected to stress relief annealing at 493 K for 3 hours.

[0087] (6) Second round of drawing: The filaments after the second annealing are drawn on a continuous drawing machine in the order of 6.00 mm → 4.50 mm → 3.00 mm → 1.50 mm, decreasing by 1.5 mm each time.

[0088] (7) Third annealing: The endogenous TiC reinforced 7075 aluminum alloy filaments after the second round of drawing were subjected to stress relief annealing at 493 K for 3 hours.

[0089] Step 4: Preparation of TiC7075 aluminum alloy powder with internal coating and its green laser-directed energy deposition (1) Preparation of the wire feeding system: Install the spool with Φ1.5 mm aluminum alloy wire on the wire feeding mechanism and pass the wire end through the guide device to prepare to feed it into the crucible.

[0090] (2) Generating an alternating magnetic field: The alternating current through the 30 kW / 30 kHz induction coil will generate a high-frequency alternating magnetic field with a magnetic induction intensity of 75 mT in the crucible area inside the coil.

[0091] (3) Initial melting and continuous wire feeding: 100 g of 7075 aluminum alloy is placed in the crucible as the "starting material". The magnetic field generates eddy currents inside it, which causes the starting material to heat up and melt rapidly, forming a molten pool. Then the wire feeder is started to continuously feed the aluminum alloy wire into the molten pool at a speed of 10 r / min.

[0092] (4) Melt holding and refining: After the fine wire is fully melted, the molten pool is kept at 1003 K.

[0093] (5) Melt flow: After the temperature of the molten pool stabilizes, open the flow guide tube at the bottom of the crucible to form a stable and continuous liquid flow with a diameter of 2-5 mm, which flows into the top of the atomizing tower.

[0094] (6) Droplet formation: After the metal liquid flows out of the guide tube, it is impacted by the high-speed gas flow of 99.99% high-purity argon surrounding it, which tears the liquid flow into tiny droplets with a diameter of 10-200 μm.

[0095] (7) Cooling and solidification: Under the action of gravity, the spherical droplets fly downward in the 7m atomization tower, rapidly cool and solidify into solid spherical powder particles.

[0096] (8) Powder collection and sieving: The completely cooled powder particles fall into the collection tank at the bottom of the atomizing tower and are sieved by a vibrating sieve according to different particle size ranges (15~53μm, 53~150μm) to meet the specific requirements of different applications.

[0097] (9) Additive manufacturing and heat treatment: Powder with a particle size of 53~150μm was selected for green laser directional energy deposition. The green laser power used was 900W and the scanning speed was 1500mm / min. Then, the obtained bulk material was subjected to solid solution treatment at 743K for 1 hour and water quenching immediately. Finally, it was subjected to two-stage aging at 383K for 5 hours and 423K for 14 hours to prepare 1.00wt.% endogenous TiC-reinforced green laser directional energy deposition 7075 aluminum alloy.

[0098] The powder laser reflectivity test results of 1.00 wt.% endogenous TiC-enhanced green laser-directed energy deposition 7075 aluminum alloy are as follows: Figure 4 As shown, the laser reflectivity of the powder is significantly reduced after being coated with TiC, thereby reducing the energy input requirement of the laser-directed energy deposition process.

[0099] Comparative Example 1: This comparative example provides a method for preparing 7075 aluminum alloy (without ceramic particle reinforcement) by infrared laser directional energy deposition, including the following steps: Step 1: In-situ reaction within the melt (1) Place a dry crucible in a crucible-type resistance melting furnace and add the weighed 7075 aluminum alloy bar; the bar composition is: aluminum Al: balance; zinc Zn: 5.5wt.%; magnesium Mg: 2.7wt.%; copper Cu: 1.8wt.%; chromium Cr: 0.18wt.%; silicon Si: 0.25wt.%; iron Fe: 0.25wt.%; manganese Mn: 0.20wt.%; titanium Ti: 0.14wt.%; heat the melt to 1173 K, and then hold it in this temperature range for 30 minutes to melt; (2) After the bar stock has completely melted, add 0.05 wt.% of a slag remover to refine the stock. After the slag removal operation is completed, continue to hold the stock at that temperature for 3 minutes. (3) Lower the ultrasonic probe to 7 cm above the melt surface and preheat for 5 minutes. Then turn on the ultrasonic equipment and use the ultrasonic probe to ultrasonically treat the melt at a frequency of 23 kHz for 3 minutes. After the treatment, remove the probe and keep the melt warm for another 2 minutes; (4) The temperature of the melt is monitored by thermocouples. When it reaches 1003 K, it is poured into the preheated steel mold. After cooling, a 7075 aluminum alloy ingot with a diameter of 82 mm × 82 mm is obtained.

[0100] Step 2: Preparation of 7075 aluminum alloy wire (1) Homogenization treatment: Homogenize at 743 K for 10 h.

[0101] (2) Hot extrusion: The homogenized ingot is hot extruded at 723 K with an extrusion ratio of 67.2:1 to obtain an endogenous TiC reinforced 7075 aluminum alloy profile with a cross section of Φ10 mm×1100 mm; (3) First annealing: The hot-extruded endogenous TiC reinforced 7075 aluminum alloy profile was subjected to stress-relief annealing at 483 K for 3 hours; (4) First round of drawing: The annealed profile is drawn on a continuous wire drawing machine in the order of 10.00 mm → 8.00 mm → 6.00 mm in cross-sectional diameter, decreasing by 2 mm each time; (5) Second annealing: The endogenous TiC reinforced 7075 aluminum alloy wire after the first round of drawing was subjected to stress relief annealing at 483 K for 3 hours; (6) Second round of drawing: The filaments after the second annealing are drawn on a continuous wire drawing machine in the order of 6.00 mm → 4.50 mm → 3.00 mm → 1.50 mm, decreasing by 1.5 mm each time; (7) Third annealing: The endogenous TiC reinforced 7075 aluminum alloy filaments after the second round of drawing were subjected to stress relief annealing at 483 K for 3 hours.

[0102] Step 3: Preparation of 7075 aluminum alloy powder and its infrared laser-directed energy deposition (1) Preparation of the wire feeding system: Install the spool with Φ1.5 mm aluminum alloy wire on the wire feeding mechanism and pass the wire end through the guide device to prepare to feed it into the crucible; (2) Generating an alternating magnetic field: The alternating current through the 30 kW / 30 kHz induction coil will generate a high-frequency alternating magnetic field with a magnetic induction intensity of 65 mT in the crucible area inside the coil. (3) Initial melting and continuous wire feeding: 100 g of 7075 aluminum alloy is placed in the crucible as the "starting material". The magnetic field generates eddy currents inside it, which causes the starting material to heat up and melt rapidly, forming a molten pool. Then the wire feeder is started to continuously feed the aluminum alloy wire into the molten pool at a speed of 10 r / min. (4) Melt holding and refining: After the fine wire is fully melted, the molten pool is kept at 1023 K; (5) Melt flow guidance: After the temperature of the molten pool stabilizes, open the flow guide pipe at the bottom of the crucible to form a stable and continuous liquid flow with a diameter of 3 mm, which flows into the top of the atomizing tower; (6) Droplet formation: After the metal liquid flows out of the guide tube, it is impacted by the high-speed gas flow of 99.99% high-purity argon surrounding it, which tears the liquid flow into tiny droplets with a diameter of 10-200 μm. (7) Cooling and solidification: Under the action of gravity, the spherical droplets fly downward in the 7m atomization tower, rapidly cool and solidify into solid spherical powder particles; (8) Powder collection and sieving: The completely cooled powder particles fall into the collection tank at the bottom of the atomizing tower and are sieved by a vibrating sieve according to different particle size ranges (15-53μm, 53-150μm) to meet the specific requirements of different applications.

[0103] (9) Additive manufacturing and heat treatment: Powder with a particle size of 53-150μm was selected for infrared laser directional energy deposition. The infrared laser power used was 1100W and the scanning speed was 1500mm / min. Then, the obtained bulk material was subjected to solid solution treatment at 743K for 1 hour and water quenching immediately. Finally, it was subjected to two-stage aging at 383K for 5 hours and 423K for 14 hours to finally prepare infrared laser directional energy deposition 7075 aluminum alloy.

[0104] Comparative Example 2: This comparative example provides a method for preparing 7075 aluminum alloy with 0.10 wt.% endogenous TiC-enhanced green laser-directed energy deposition, including the following steps: Step 1: Preparation of Al-Ti-CNTs system compacts (1) Ball milling activation pretreatment of CNT powder with an initial length of 35 μm: The powder was placed in a ball milling jar and fed at a ball-to-material ratio of 50:1. The powder was ball milled for 2 hours at a speed of 250 r / min.

[0105] (2) Weigh out a certain amount of Al powder with a particle size of 15 μm and Ti powder with a particle size of 25 μm for later use.

[0106] (3) Weigh Ti powder and ball-milled activated CNTs powder at a mass ratio of 3.993:1. This ratio is intended to make the TiC phase generated by the reaction account for 20.0 wt.% of the compact. Then, mix the above powder with Al powder to finally prepare 300g of total mixed powder.

[0107] (4) Place 300 g of mixed powder in the ball mill jar of the mixer, set the rotation speed to 70 r / min, and mix for 24 h.

[0108] (5) After wrapping and sealing the mixed powder with thin aluminum foil, place it in a stainless steel mold. Then apply unidirectional axial pressure at room temperature using a hydraulic press: hold at 70 MPa for 2 minutes to finally obtain a cylindrical compact with a size of 25 mm × 35 mm and a density of 75 ± 5%.

[0109] Step 2: In-situ reaction within the melt and pre-dispersion of TiC particles (1) Place a dry crucible in a crucible-type resistance melting furnace and add the weighed 7075 aluminum alloy bar; the bar composition is: aluminum Al: balance; zinc Zn: 5.8wt.%; magnesium Mg: 2.5wt.%; copper Cu: 1.4wt.%; chromium Cr: 0.17wt.%; silicon Si: 0.20wt.%; iron Fe: 0.25wt.%; manganese Mn: 0.18wt.%; titanium Ti: 0.12wt.%; heat the melt to 1073 K, and then hold it in this temperature range for 30 minutes.

[0110] (2) After the bar stock has completely melted, add 0.12 wt.% of a slag remover to the total mass of the melt for refining. After the slag removal operation is completed, continue to keep it at the temperature for 3 minutes.

[0111] (3) The melting furnace was heated to 1023 K. Simultaneously, the Al-Ti-CNTs powder compact obtained in step one was preheated at 773 K for 0.5 h. Subsequently, the compact was pressed into the melt in the crucible, with the addition amount controlled at 0.33 wt.% of the total melt mass. Through this process, the final content of ceramic particles in the alloy was 0.10 wt.%.

[0112] (4) After the Al-Ti-CNTs compact is immersed, wait for the instantaneous flash phenomenon it causes to end, and continue to immerse it in the melt for at least 1 minute, followed by mechanical stirring for 3 minutes.

[0113] (5) Lower the ultrasonic probe to 5 cm above the surface of the melt and preheat for 5 minutes. Then turn on the ultrasonic equipment and use the ultrasonic probe at a frequency of 20 kHz to ultrasonically disperse the ceramic particles in the melt for 3 minutes to ensure uniform dispersion. After the treatment, remove the probe and keep the melt warm for another 2 minutes.

[0114] (6) The temperature of the melt was monitored using a thermocouple. When it reached 973 K, it was poured into a preheated steel mold. After cooling, an endogenous TiC-reinforced 7075 aluminum alloy ingot with a diameter of 82 mm × 80 mm was obtained.

[0115] Step 3: Preparation of endogenous TiC-reinforced 7075 aluminum alloy wire (1) Homogenization treatment: Homogenize at 743 K for 12 h.

[0116] (2) Hot extrusion: The homogenized ingot is hot extruded at 773 K with an extrusion ratio of 67.2:1 to obtain an endogenous TiC reinforced 7075 aluminum alloy profile with a cross section of Φ10 mm×1200 mm.

[0117] (3) First annealing: The hot-extruded endogenous TiC reinforced 7075 aluminum alloy profile is subjected to stress-relief annealing at 483 K for 3 hours.

[0118] (4) First round of drawing: The annealed profile is drawn on a continuous wire drawing machine in the order of 10.00 mm → 8.00 mm → 6.00 mm in cross-sectional diameter, decreasing by 2 mm each time.

[0119] (5) Second annealing: The endogenous TiC reinforced 7075 aluminum alloy filaments after the first round of drawing were subjected to stress relief annealing at 483 K for 3 hours.

[0120] (6) Second round of drawing: The filaments after the second annealing are drawn on a continuous drawing machine in the order of 6.00 mm → 4.50 mm → 3.00 mm → 1.50 mm, decreasing by 1.5 mm each time.

[0121] (7) Third annealing: The endogenous TiC reinforced 7075 aluminum alloy filaments after the second round of drawing were subjected to stress relief annealing at 483 K for 3 hours.

[0122] Step 4: Preparation of TiC7075 aluminum alloy powder with internal coating and its green laser-directed energy deposition (1) Preparation of the wire feeding system: Install the spool with Φ1.5 mm aluminum alloy wire on the wire feeding mechanism and pass the wire end through the guide device to prepare to feed it into the crucible.

[0123] (2) Generating an alternating magnetic field: The alternating current through the 30 kW / 30 kHz induction coil will generate a high-frequency alternating magnetic field with a magnetic induction intensity of 60 mT in the crucible area inside the coil.

[0124] (3) Initial melting and continuous wire feeding: 100 g of 7075 aluminum alloy is placed in the crucible as the "starting material". The magnetic field generates eddy currents inside it, which causes the starting material to heat up and melt rapidly, forming a molten pool. Then the wire feeder is started to continuously feed the aluminum alloy wire into the molten pool at a speed of 10 r / min.

[0125] (4) Melt holding and refining: After the fine wire is fully melted, the molten pool is kept at 1023 K.

[0126] (5) Melt flow: After the temperature of the molten pool stabilizes, open the flow guide pipe at the bottom of the crucible to form a stable and continuous liquid flow with a diameter of 2 mm, which flows into the top of the atomizing tower.

[0127] (6) Droplet formation: After the metal liquid flows out of the guide tube, it is impacted by the high-speed gas flow of 99.99% high-purity argon surrounding it, which tears the liquid flow into tiny droplets with a diameter of 10-200 μm.

[0128] (7) Cooling and solidification: Under the action of gravity, the spherical droplets fly downward in the 7m atomization tower, rapidly cool and solidify into solid spherical powder particles.

[0129] (8) Powder collection and sieving: The completely cooled powder particles fall into the collection tank at the bottom of the atomizing tower and are sieved by a vibrating sieve according to different particle size ranges (15-53μm, 53-150μm) to meet the specific requirements of different applications.

[0130] (9) Additive manufacturing and heat treatment: Powder with a particle size of 53-150μm was selected for green laser directional energy deposition. The green laser power was 1100W and the scanning speed was 1500mm / min. The obtained bulk material was then subjected to solid solution treatment at 743 K for 1 hour and immediately water quenched. Finally, it was subjected to two-stage aging at 383 K for 5 hours and 423 K for 14 hours to finally prepare green laser directional energy deposition endogenous TiC reinforced ultra-high strength aluminum alloy.

[0131] Comparative Example 3: This comparative example provides a method for preparing 7075 aluminum alloy with 1.50 wt.% endogenous TiC-enhanced green laser-directed energy deposition, including the following steps: Step 1: Preparation of Al-Ti-CNTs system compacts (1) Ball milling activation pretreatment of CNT powder with an initial length of 75 μm: The powder was placed in a ball milling jar and fed at a ball-to-material ratio of 50:1. The powder was ball milled for 2 hours at a speed of 250 r / min. (2) Weigh out a certain amount of Al powder with a particle size of 18 μm and Ti powder with a particle size of 23 μm for later use; (3) Weigh Ti powder and ball-milled activated CNTs powder at a mass ratio of 3.993:1. This ratio is intended to make the TiC phase generated by the reaction account for 20.0 wt.% of the compact. Then, mix the above powder with Al powder to finally prepare 500g of total mixed powder; (4) Place 300 g of the mixed powder in the ball mill jar of the mixer, set the rotation speed to 75 r / min, and mix for 35 h; (5) After wrapping and sealing the mixed powder with thin aluminum foil, place it in a stainless steel mold. Then apply unidirectional axial pressure at room temperature using a hydraulic press: hold at 80 MPa for 3 minutes to finally obtain a cylindrical compact with a size of 25 mm × 45 mm and a density of 74%.

[0132] Step 2: In-situ reaction within the melt and pre-dispersion of TiC particles (1) Place a dry crucible in a crucible-type resistance melting furnace and add the weighed 7075 aluminum alloy bar; the bar composition is: aluminum Al: balance; zinc Zn: 6.2wt.%; magnesium Mg: 2.7wt.%; copper Cu: 1.9wt.%; chromium Cr: 0.20wt.%; silicon Si: 0.25wt.%; iron Fe: 0.30wt.%; manganese Mn: 0.18wt.%; titanium Ti: 0.12wt.%; heat the melt to 1173 K, and then hold it in this temperature range for 45 minutes for melting; (2) After the bar stock has completely melted, add 0.13 wt.% of a slag remover to refine it. After the slag removal operation is completed, continue to keep it at the temperature for 5 minutes; (3) The melting furnace was heated to 1123 K. Simultaneously, the Al-Ti-CNTs powder compact obtained in step one was preheated at 823 K for 0.5 h. Subsequently, the compact was pressed into the melt in the crucible, with the addition amount controlled to be between 5.00 wt.% of the total melt mass. Through this process, the final content of ceramic particles in the alloy was 1.50 wt.%. (4) After the Al-Ti-CNTs compact is immersed, wait for the instantaneous flash phenomenon it causes to end, and continue to immerse it in the melt for at least 1 minute, followed by mechanical stirring for 3 minutes; (5) Lower the ultrasonic probe to 5 cm above the surface of the melt and preheat for 7 minutes. Then turn on the ultrasonic equipment and use the ultrasonic probe at a frequency of 24 kHz to ultrasonically disperse the ceramic particles in the melt for 5 minutes to ensure uniform dispersion. After the treatment, remove the probe and keep the melt warm for another 3 minutes. (6) The temperature of the melt was monitored using a thermocouple. When it reached 1023 K, it was poured into a preheated steel mold. After cooling, an endogenous TiC-reinforced 7075 aluminum alloy ingot with a diameter of 82 mm × 88 mm was obtained.

[0133] Step 3: Preparation of endogenous TiC-reinforced 7075 aluminum alloy wire (1) Homogenization treatment: Homogenize at 763 K for 15 h.

[0134] (2) Hot extrusion: The homogenized ingot is hot extruded at 773 K with an extrusion ratio of 67.2:1 to obtain an endogenous TiC reinforced 7075 aluminum alloy profile with a cross section of Φ10 mm×1200 mm; (3) First annealing: The hot-extruded endogenous TiC reinforced 7075 aluminum alloy profile was subjected to stress-relief annealing at 473 K for 3 hours; (4) First round of drawing: The annealed profile is drawn on a continuous wire drawing machine in the order of 10.00 mm → 8.00 mm → 6.00 mm in cross-sectional diameter, decreasing by 2 mm each time; (5) Second annealing: The endogenous TiC reinforced 7075 aluminum alloy wire after the first round of drawing was subjected to stress relief annealing at 473 K for 3 hours; (6) Second round of drawing: The filaments after the second annealing are drawn on a continuous wire drawing machine in the order of 6.00 mm → 4.50 mm → 3.00 mm → 1.50 mm, decreasing by 1.5 mm each time; (7) Third annealing: The endogenous TiC reinforced 7075 aluminum alloy filaments after the second round of drawing were subjected to stress relief annealing at 473 K for 3 hours.

[0135] Step 4: Preparation of TiC7075 aluminum alloy powder with internal coating and its green laser-directed energy deposition (1) Preparation of the wire feeding system: Install the spool with Φ1.5 mm aluminum alloy wire on the wire feeding mechanism and pass the wire end through the guide device to prepare to feed it into the crucible; (2) Generating an alternating magnetic field: The alternating current through the 30 kW / 30 kHz induction coil will generate a high-frequency alternating magnetic field with a magnetic induction intensity of 70 mT in the crucible area inside the coil. (3) Initial melting and continuous wire feeding: 100 g of 7075 aluminum alloy is placed in the crucible as the "starting material". The magnetic field generates eddy currents inside it, which causes the starting material to heat up and melt rapidly, forming a molten pool. Then the wire feeder is started to continuously feed the aluminum alloy wire into the molten pool at a speed of 10 r / min. (4) Melt holding and refining: After the fine wire is fully melted, the molten pool is kept at 1123 K; (5) Melt flow guidance: After the temperature of the molten pool stabilizes, open the flow guide pipe at the bottom of the crucible to form a stable and continuous liquid flow with a diameter of 2.5 mm, which flows into the top of the atomizing tower; (6) Droplet formation: After the metal liquid flows out of the guide tube, it is impacted by the high-speed gas flow of 99.99% high-purity argon surrounding it, which tears the liquid flow into tiny droplets with a diameter of 10-200 μm. (7) Cooling and solidification: Under the action of gravity, the spherical droplets fly downward in the 7m atomization tower, rapidly cool and solidify into solid spherical powder particles; (8) Powder collection and sieving: The completely cooled powder particles fall into the collection tank at the bottom of the atomizing tower and are sieved by a vibrating sieve according to different particle size ranges (15-53μm, 53-150μm) to meet the specific requirements of different applications.

[0136] (9) Additive manufacturing and heat treatment: Powder with a particle size of 53-150μm was selected for green laser directional energy deposition. The green laser power used was 900W and the scanning speed was 1500mm / min. The obtained bulk material was then subjected to a solid solution treatment at 763K for 1 hour and immediately quenched in water. Finally, it was subjected to a two-stage aging process at 383K for 5 hours and 423K for 14 hours to finally prepare 1.50wt.% endogenous TiC-reinforced green laser directional energy deposition 7075 aluminum alloy.

[0137] The performance of the aluminum alloys prepared in Examples 1-3 and Comparative Examples 1-3 is analyzed below.

[0138] According to the national standard for tensile testing, aluminum alloy was made into tensile specimens that meet the national standard and tensile tests were conducted. The mechanical properties are shown in Table 1.

[0139] Table 1: Mechanical property test results of aluminum alloys prepared in Examples 1-3 and Comparative Examples 1-3

[0140] As shown in Table 1, compared with Comparative Example 1, after strengthening with 0.15 wt.% TiC ceramic particles and undergoing two-stage aging treatment, the yield strength, tensile strength, and fracture strain of the 7075 aluminum alloy were 445 MPa, 507 MPa, and 8.5%, respectively. These values ​​represent an increase of 25.0% and 9.3% compared to the 356 MPa yield strength and 464 MPa tensile strength of the infrared laser directed energy deposition (IRED) 7075 aluminum alloy, while maintaining good fracture toughness. Therefore, adding 0.15 wt.% TiC ceramic particles combined with green laser directed energy deposition technology can slightly improve the strength of IRED 7075 aluminum alloy while maintaining its plasticity.

[0141] Compared with Comparative Example 2, the addition of 0.15 wt.% TiC in Example 1 further promotes grain refinement and equiaxed grains, as well as Marangoni convection in the molten pool, on top of the 0.1 wt.% addition. This reduces the energy requirement of the molten pool, lowers the forming green laser power from 1100 W to 900 W, reduces elemental burn-off, and improves grain boundary strengthening and precipitation strengthening efficiency. Therefore, compared with Comparative Example 2, Example 1 shows a significant improvement in strength while maintaining good plasticity.

[0142] Compared with Comparative Example 1, Example 2, strengthened with 0.50 wt.% TiC ceramic particles and subjected to a two-stage aging treatment, showed that the yield strength, tensile strength, and fracture strain of the 7075 aluminum alloy were 497 MPa, 526 MPa, and 7.7%, respectively. This represents an increase of 39.6% and 13.4% compared to the 356 MPa yield strength and 464 MPa tensile strength of the infrared laser-directed energy deposition (IRED) 7075 aluminum alloy, while maintaining good fracture toughness. Therefore, the addition of 0.50 wt.% TiC ceramic particles combined with green laser-directed energy deposition technology significantly improves the strength of IRED 7075 aluminum alloy while maintaining its ductility. Example 2, based on the 0.15 wt.% particle addition in Example 1, further increases the particle content, which can further refine the constructed microstructure, reduce elemental burn-off, and improve grain boundary strengthening and precipitation strengthening efficiency, resulting in a further increase in strength without a significant decrease in ductility.

[0143] Compared with Comparative Example 1, Example 3, strengthened with 1.00 wt.% TiC ceramic particles and subjected to a two-stage aging treatment, showed that the yield strength, tensile strength, and fracture strain of the 7075 aluminum alloy were 543 MPa, 591 MPa, and 6.2%, respectively. These represent increases of 52.5% and 27.4% compared to the 356 MPa yield strength and 464 MPa tensile strength of the infrared laser-directed energy deposition (IRED) 7075 aluminum alloy, while maintaining good fracture toughness. Therefore, the addition of 1.00 wt.% TiC ceramic particles combined with green laser-directed energy deposition technology significantly improves the strength of IRED 7075 aluminum alloy, exceeding the strength of traditionally forged 7075 aluminum alloy, while maintaining the plasticity of IRED 7075 aluminum alloy. This effectively demonstrates that 1 wt.% TiC addition is the optimal addition ratio in the green laser-directed energy deposition 7075 aluminum alloy system, achieving the best strength-plasticity balance.

[0144] like Figure 5As shown, Example 3, by combining the effect of green laser on improving powder absorption, further suppressed elemental burn-off during the deposition process. Under green laser directed energy deposition conditions, Example 3 achieved excellent synergy between strength and plasticity by optimizing the TiC addition amount and improving the powder structure and laser absorption characteristics. Its performance is superior to previously reported laser-directed energy deposition aluminum alloys, such as... Figure 6 As shown.

[0145] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A green laser-directed energy deposition method for endogenous titanium carbide-reinforced ultra-high strength aluminum alloys, characterized in that, include: Preparation of aluminum-titanium-carbon nanotube system compacts; The aluminum-titanium-carbon nanotube system compact is immersed in the aluminum alloy melt, and titanium carbide pre-dispersion is carried out based on the in-situ reaction in the melt to obtain an endogenous titanium carbide reinforced aluminum alloy ingot. An annealing and drawing process was performed on the ingot of endogenous titanium carbide reinforced aluminum alloy to obtain endogenous titanium carbide reinforced aluminum alloy wire. Intrinsically coated titanium carbide aluminum alloy powder was prepared from intrinsic titanium carbide reinforced aluminum alloy wire, and ultra-high strength aluminum alloy reinforced with intrinsic titanium carbide was obtained by green laser directional energy deposition.

2. The green laser-directed energy deposition method for endogenous titanium carbide-reinforced ultra-high strength aluminum alloys according to claim 1, characterized in that, The preparation of the aluminum-titanium-carbon nanotube system compact includes: Aluminum-titanium-carbon nanotube powder was ball-milled and activated to obtain ball-milled activated aluminum-titanium-carbon nanotube powder. The ball-milled and activated aluminum-titanium-carbon nanotube powder was mixed with titanium powder and aluminum powder to obtain a mixed powder. The mixed powder was ball-milled and then subjected to hydraulic pressure to obtain an aluminum-titanium-carbon nanotube system compact.

3. The green laser-directed energy deposition method for endogenous titanium carbide-reinforced ultra-high strength aluminum alloys according to claim 2, characterized in that, The aluminum-titanium-carbon nanotube powder has a particle size of 20-100 micrometers, the titanium powder has a particle size of 20-30 micrometers, and the aluminum powder has a particle size of 10-20 micrometers. And / or, in the aluminum-titanium-carbon nanotube system compact, the mass fraction of aluminum powder is 70~80% and the mass fraction of titanium powder is 16.0~22.5%.

4. The green laser-directed energy deposition method for endogenous titanium carbide-reinforced ultra-high strength aluminum alloys according to claim 2, characterized in that, The conditions for ball milling activation include ball milling at 200-300 r / min for 1-3 hours; And / or, the ball milling conditions include ball milling at 50~100 r / min for 20~50 hours; And / or, the hydraulic pressure includes: The mixed powder is wrapped and sealed with aluminum foil and placed in a mold. A unidirectional axial pressure of 50-100 MPa is applied to it at room temperature using a hydraulic press and the pressure is maintained for 1-3 minutes.

5. The green laser-directed energy deposition method for endogenous titanium carbide-reinforced ultra-high strength aluminum alloys according to claim 2, characterized in that, The process of immersing an aluminum-titanium-carbon nanotube system compact into a melt of aluminum alloy, and pre-dispersing titanium carbide based on in-situ reactions within the melt to obtain an endogenous titanium carbide-reinforced aluminum alloy ingot includes: Aluminum alloy melt is prepared from aluminum alloy bars; After preheating, the aluminum-titanium-carbon nanotube system compact is immersed in aluminum alloy melt and ultrasonically dispersed to obtain ceramic aluminum alloy melt. The ceramic aluminum alloy melt is injected into a preheated steel mold and cooled to obtain an endogenous titanium carbide reinforced aluminum alloy ingot.

6. The green laser-directed energy deposition method for endogenous titanium carbide-reinforced ultra-high strength aluminum alloys according to claim 5, characterized in that, The aluminum alloy bar is made of 7075 aluminum alloy, which includes 5~6.5wt% zinc, 2.0~3.0wt% magnesium, 1.0~2.5wt% copper, 0.15~0.30wt% chromium, 0.15~0.3wt% silicon, 0.20~0.45wt% iron, 0.10~0.30wt% manganese, and no more than 0.20wt% titanium, with the remainder being aluminum; And / or, the method for preparing aluminum alloy melt from aluminum alloy bars includes: The aluminum alloy bar is heated to 1073~1173K and held at that temperature for 30~50 minutes. After the aluminum alloy bar is completely melted, a slag remover of 0.05~0.15wt% of the total mass of the melt is added for refining. After slag removal, the temperature is held for another 2~5 minutes. The slag remover includes 40~50wt% KCl, 35~40wt% MgCl2, 6~8wt% AlF3, 12~15wt% Na3AlF6, 6~9wt% Mg3N2, 3~5wt.% Na2CO3, and 3~5wt.% C2Cl6. And / or, the preheating of the aluminum-titanium-carbon nanotube system compact followed by immersion in an aluminum alloy melt, and ultrasonic dispersion to obtain a ceramic aluminum alloy melt, comprises: The aluminum alloy melt was heated to 1023~1223K, and the aluminum-titanium-carbon nanotube system compact was preheated at 7772~823K. The preheated aluminum-titanium-carbon nanotube system compact was immersed in molten aluminum alloy to generate ceramic particles within the alloy. After the momentary flashover, the mixture was held for at least 1 minute, stirred, and then ultrasonically dispersed at 20–25 kHz to obtain a ceramic-aluminum alloy melt. The mass of the aluminum-titanium-carbon nanotube system compact accounted for 0.50–3.33 wt% of the ceramic-aluminum alloy melt, and the mass of the ceramic particles accounted for 0.15–1.00 wt% of the ceramic-aluminum alloy melt. And / or, the temperature range when the ceramic aluminum alloy melt is injected into the preheated steel mold is 973~1023K.

7. The green laser-directed energy deposition method for endogenous titanium carbide-reinforced ultra-high strength aluminum alloys according to claim 1, characterized in that, The annealing and drawing processes include: The endogenous titanium carbide reinforced aluminum alloy ingot was homogenized at 743~763K for 10~15 hours; The homogenized endogenous titanium carbide reinforced aluminum alloy ingot is hot extruded at 723~773K to obtain endogenous titanium carbide reinforced aluminum alloy profiles. The endogenous titanium carbide reinforced aluminum alloy profile is subjected to a first annealing treatment, a first drawing treatment, a second annealing treatment, a second drawing treatment, and a third annealing treatment in sequence to obtain endogenous titanium carbide reinforced aluminum alloy wire. And / or, the conditions for the first annealing treatment, the second annealing treatment, and the third annealing treatment are all stress-relief annealing treatment at 473~493K for 2.5~3.5 hours; The first drawing process involves successively reducing the cross-sectional diameter of the endogenous titanium carbide reinforced aluminum alloy profile by 2-3 mm. The second drawing process involves successively reducing the cross-sectional diameter of the endogenous titanium carbide reinforced aluminum alloy profile by 1.5~2.0 mm.

8. The green laser-directed energy deposition method for endogenous titanium carbide-reinforced ultra-high strength aluminum alloys according to claim 1, characterized in that, The process of preparing internally coated titanium carbide aluminum alloy powder from endogenous titanium carbide reinforced aluminum alloy wire and obtaining titanium carbide reinforced aluminum alloy using green laser directional energy deposition includes: Using 7075 aluminum alloy as the starting material, a high-frequency alternating magnetic field is used to generate eddy currents inside the starting material, causing it to melt and form a molten pool. The endogenous titanium carbide reinforced aluminum alloy wire is continuously fed into the molten pool. After the endogenous titanium carbide reinforced aluminum alloy wire is fully melted, the molten pool is maintained at 1023~1123K. The molten pool is formed into a liquid flow with a diameter of 2-5 mm by guiding the flow, and then torn into droplets with a diameter of 10-200 micrometers by the impact of argon gas flow. After cooling and solidification, spherical powder is obtained. Titanium carbide reinforced aluminum alloy is obtained by performing green laser directional energy deposition, solution treatment, water quenching, and two-stage aging treatment on spherical powder. The green laser directional energy deposition conditions include a green laser power of 900W and a scanning speed of 1500mm / min.

9. The green laser-directed energy deposition method for endogenous titanium carbide-reinforced ultra-high strength aluminum alloys according to claim 8, characterized in that, The magnetic induction intensity of the high-frequency alternating magnetic field is 60~100mT; And / or, before performing green laser directional energy deposition on spherical powder, the particle size of the spherical powder is sieved to select a particle size range of 53~150 micrometers; And / or, the conditions for the solution treatment include treatment at 743~763K for 1~2 hours; And / or, the condition parameters for the two-stage aging process include first processing at 353~403K for 5 hours, and then processing at 403~433K for 14 hours.

10. An endogenous titanium carbide-reinforced ultra-high strength aluminum alloy, characterized in that, It is prepared by the green laser directional energy deposition method for endogenous titanium carbide-reinforced ultra-high strength aluminum alloy as described in any one of claims 1 to 9.

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