High performance gamma based titanium aluminide alloy and additive manufacturing method thereof

Abstract

The application discloses a high-performance gamma-based titanium-aluminum alloy and an additive manufacturing method thereof, and the additive manufacturing method comprises the following steps: selecting suitable titanium-aluminum alloy powder and aluminum powder; mixing the titanium-aluminum alloy powder and the aluminum powder to obtain mixed powder; feeding the mixed powder into an SLM device to print under an inert gas protection atmosphere, so that a printed alloy blank with a density of greater than or equal to 97% is obtained, and at this time, a mixed structure of titanium-aluminum intermetallic compounds and aluminum phases is preliminarily formed in the blank; placing the printed alloy blank into a hot isostatic pressing device to perform hot isostatic pressing treatment; and performing solid solution heat treatment on the alloy after the hot isostatic pressing treatment. The application breaks through the collaborative difficulties of 'SLM forming-defect elimination-phase regulation', optimizes the process chain, and has the advantages of process simplicity and cost advantage while ensuring the high performance of the gamma phase, is the optimal solution for solving the bottleneck of titanium-aluminum additive manufacturing at present, and meets the use requirements of aero-engine low-pressure turbine blades.

Description

Technical Field

[0001] This invention belongs to the field of titanium-aluminum alloy manufacturing technology, specifically relating to a high-performance γ-based titanium-aluminum alloy and its additive manufacturing method. Background Technology

[0002] Selective Laser Melting (SLM) additive manufacturing technology, as an important branch of metal additive manufacturing, has shown great application potential in high-end manufacturing fields such as aerospace, automotive manufacturing, and biomedical engineering due to its advantages such as near-net-shape forming of complex structural parts, high material utilization, and precise dimensional control. This technology selectively melts metal powder layer by layer using a high-energy laser beam to achieve the direct manufacturing of three-dimensional solid parts. It can overcome the limitations of traditional forging and casting processes in forming complex structures, providing a new technological path for the rapid fabrication of high-performance metal components.

[0003] Titanium-aluminum alloys based on titanium aluminum intermetallic compounds are characterized by their low density (approximately 3.9-4.7 g / cm³). 3 With its high specific strength, excellent high-temperature mechanical properties (capable of long-term operation at 600-800℃), and good oxidation resistance, titanium-aluminum intermetallic compound (TAC) has become an ideal candidate material to replace traditional nickel-based superalloys and reduce the weight of hot-end components such as aerospace engines. For example, in components such as low-pressure turbine blades and high-pressure compressor blades of aero-engines, the application of TAC can significantly reduce the overall weight of the engine, improve the thrust-to-weight ratio, and thus improve the fuel efficiency and maneuverability of the aircraft.

[0004] However, titanium-aluminum intermetallic compounds inherently possess high room-temperature brittleness and poor plasticity, posing numerous challenges to traditional forming processes (such as casting and forging). Casting is prone to defects like porosity and segregation, leading to fluctuations in mechanical properties; forging requires high temperatures, resulting in high energy consumption and stringent mold requirements, making it particularly difficult to form complex structural parts. Therefore, applying laser selective melting additive manufacturing technology to the forming of titanium-aluminum intermetallic compounds has become an important research direction for solving the challenges of preparing their complex structures.

[0005] Chinese invention patent CN117488144A discloses a high-performance aluminum-titanium metal composite material for additive manufacturing and its preparation method. The core of this method is an aluminum-based composite material: using aluminum alloy (85-98 wt%) as the matrix and titanium alloy powder (2-15 wt%) as the reinforcing phase. Essentially, it modifies the microstructure of the aluminum alloy with titanium alloy (e.g., refining equiaxed grains, forming a core-shell structure), and the final performance depends on the strengthening of the aluminum matrix. Its application scenarios are more inclined towards medium- and low-temperature structural components (such as general machinery and lightweight automotive parts), and it is not suitable for high-temperature aerospace components (such as engine blades and combustion chambers). Furthermore, this patent only uses titanium alloy as a passive reinforcing phase of the aluminum matrix, without actively controlling the phase composition of the titanium-aluminum intermetallic compound, and without designing subsequent treatments tailored to the characteristics of the titanium-aluminum intermetallic compound. Summary of the Invention

[0006] To address the problems in the prior art, the present invention aims to provide a high-performance γ-based titanium-aluminum alloy and its additive manufacturing method.

[0007] To achieve the above objectives and technical effects, the technical solution adopted by this invention is as follows:

[0008] An additive manufacturing method for a high-performance γ-based titanium-aluminum alloy includes the following steps:

[0009] 1) Select appropriate titanium-aluminum alloy powder and aluminum powder;

[0010] 2) Powder mixing: Titanium-aluminum alloy powder and aluminum powder are mixed to obtain mixed powder;

[0011] 3) Laser melting additive manufacturing: The mixed powder is fed into the SLM equipment and printed in an inert gas protective atmosphere to obtain a printed alloy blank with a density of ≥97%. At this time, a mixed structure of titanium-aluminum intermetallic compounds and aluminum phase is initially formed in the blank.

[0012] 4) Place the printed alloy blank in a hot isostatic pressing (HIP) apparatus for hot isostatic pressing treatment;

[0013] 5) Perform solution heat treatment on the alloy after hot isostatic pressing.

[0014] Furthermore, in step 1), the titanium-aluminum alloy powder is a spherical titanium-aluminum alloy powder with a particle size of 25~53μm.

[0015] Furthermore, in step 1), the aluminum powder is spherical aluminum powder with a particle size of 18~45μm and a purity of ≥99.7%.

[0016] Furthermore, in step 2), the mass ratio of the titanium-aluminum alloy powder to the aluminum powder is 2.15~2.45:1.

[0017] Furthermore, in step 2), titanium-aluminum alloy powder and aluminum powder are mixed in a planetary ball mill. The ball milling parameters are set as follows: ball-to-material ratio 6:1 to 9:1, rotation speed 220 to 280 r / min, and ball milling time 2.5 to 3.5 h. An argon protective atmosphere is used to avoid powder oxidation.

[0018] Furthermore, in step 3), the process parameters are set as follows: laser power 280~320W, scanning speed 1000~1300mm / s, layer thickness 35~45μm, and scanning spacing 90~110μm.

[0019] Furthermore, in step 3), the scanning strategy is as follows: bidirectional cross scanning is adopted, interlayer rotation is 67° to reduce anisotropy, edge scanning speed is reduced by 20%, and spheroidization effect is reduced.

[0020] Furthermore, in step 4), the printed alloy blank is placed in a hot isostatic pressing apparatus and held at a temperature of 1100~1250℃ and a pressure of 100~200MPa for 2~4 hours, and then cooled to room temperature with the furnace.

[0021] Furthermore, in step 5), the alloy after hot isostatic pressing is heated to 900~1050℃, held at that temperature for 2~4 hours, and then rapidly cooled by oil cooling.

[0022] This invention also discloses a high-performance γ-based titanium-aluminum alloy prepared by an additive manufacturing method.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1) This invention discloses a titanium-aluminum alloy powder with 85% Ti and 15% Al (initial atomic ratio ≈ 5.67:1), instead of traditional TiAl pre-alloyed powder. Through a combination of "high Ti master powder + added pure Al powder," precise compositional space is reserved for the formation of the γ-phase (TiAl). Traditional pre-alloyed powders (such as Ti-48Al-2Cr-2Nb) have fixed compositions and cannot adjust the phase ratio according to the rapid solidification characteristics of SLM. However, this invention, with its high Ti base of titanium-aluminum alloy powder, can flexibly adapt to the subsequent Al powder addition, avoiding the direct use of pure Ti powder and pure Al powder. The problem of TiAl3 brittle phase caused by local Al enrichment during Al powder mixing is easily encountered; the fluctuation of Ti and Al content in titanium-aluminum alloy powder is controlled within ±0.5wt%, ensuring that after subsequent mixing with Al powder at a mass ratio of 2.15~2.45:1, the overall Ti:Al atomic ratio of the adjusted system is stable at 1.05~1.1:1 (the atomic ratio range of stable γ phase is 0.8~1.2:1), which solves the problem of "uncontrolled γ phase + α2 phase ratio" caused by component segregation during SLM process;

[0025] 2) Functional component design of aluminum powder, taking into account phase regulation and process adaptability: directional control of purity and impurities: aluminum powder purity ≥99.7%, and strictly limited Fe≤0.1wt%, Si≤0.05wt%, which is different from conventional industrial pure aluminum powder (Fe≤0.2wt%, Si≤0.1wt%), avoiding the formation of low-melting-point eutectic phases (such as Ti6Al4Fe, Ti5Si3) at the γ-TiAl phase grain boundaries, which would lead to grain boundary softening at high temperatures; this invention improves the γ-phase grain boundary bonding strength by more than 15% by reducing impurity content, and the tensile strength at 800℃ is 30~50MPa higher than that of conventional aluminum powder formulations;

[0026] Gradient particle size matching design: Aluminum powder with a particle size of 18~45μm (D50=32μm) and titanium-aluminum alloy powder with a particle size of 25~53μm (D50=38μm) are mixed in a gradient ratio, rather than being mixed with equal particle sizes. The smaller particle size aluminum powder can fill the gaps between the larger particle size titanium-aluminum alloy powder, so that the loose packing density of the mixed powder is lower than that of a single-particle-size mixture of 2.5g / cm³. 3 Increased to 2.8g / cm 3 The density of the SLM powder layer is increased to over 92% (compared to ≤88% for conventional mixed powder), reducing defects caused by excessive powder gaps during printing due to lack of fusion.

[0027] 3) Dynamic composition compensation design of mixed powder, a creative solution to SLM burn-off; aluminum powder burn-off compensation mechanism; during the SLM process, aluminum is prone to burn-off of about 1.5~2wt% due to its low boiling point (2467℃). Traditional formulations do not consider this problem, resulting in insufficient Al content in the final component and an excessively high proportion of α2 phase (Ti3Al) (more than 15%), leading to decreased plasticity. The ingenuity of this invention lies in: adding an additional 0.3~0.5wt% of aluminum powder to the basic mass ratio of 2.15~2.45:1 to form a burn-off compensation margin, ensuring that the actual Al content of the printed component still meets the requirement of γ phase dominance (α2 phase proportion controlled at 5~8%).

[0028] 4) Innovative manufacturing process: Breaking through the synergistic challenges of "SLM forming-defect elimination-phase control", optimizing the process chain, while ensuring high performance dominated by the γ phase, it also has the advantages of process simplicity and cost, which is currently the best solution to solve the bottleneck of titanium-aluminum additive manufacturing.

[0029] 5) This invention, through the synergy of formulation and process, achieves a high-temperature tensile strength of ≥400MPa at 800℃ and a creep rupture life of ≥100 hours (100MPa load), meeting the requirements for low-pressure turbine blades in aero-engines (tensile strength ≥350MPa at 800℃, creep rupture life ≥50h); the oxidation weight gain of conventional Ti-48Al-2Cr-2Nb alloy is ≥0.3mg / cm³. 2The weight gain after oxidation at 800℃ for 100 hours according to this invention is ≤0.1mg / cm³. 2 , forming a dense The protective layer solves the industry problem of poor high-temperature oxidation resistance of γ-TiAl alloys;

[0030] 6) Traditional casting of γ-TiAl alloys cannot form complex thin-walled structures with a wall thickness of ≤3mm, and is prone to incomplete casting and cracks; This invention, through the synergy of SLM process and formulation, can form thin-walled blades with a wall thickness of 1.5mm (minimum fillet radius of 0.5mm), and after forming, there are no cracks or porosity defects (defect rate ≤0.1%), and the dimensional accuracy of the components reaches ±0.1mm, meeting the near-net-shape forming requirements of complex aerospace structures;

[0031] Creative principle: High flowability of the mixed powder (bulk density ≥ 2.8 g / cm³) 3 The precise energy control of SLM (Self-Drying Molding Machine) avoids deformation and cracking caused by heat accumulation during the printing of thin-walled parts, while traditional formulations suffer from poor powder flowability (bulk density ≤ 2.5 g / cm³). 3 The pass rate for forming thin-walled parts is only 50%, but this invention can increase it to over 95%. Detailed Implementation

[0032] The present invention will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0033] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0034] This invention discloses an additive manufacturing method for high-performance γ-based titanium-aluminum alloys, comprising the following steps:

[0035] 1) Material selection:

[0036] Titanium-aluminum alloy powder: Spherical titanium-aluminum alloy powder with a particle size range of 25~53μm is selected. Its main components are titanium and aluminum, and the titanium-aluminum atomic ratio can be pre-controlled according to the target γ (TiAl, atomic ratio 1:1) phase composition. This powder must meet the requirements of high sphericity (≥98%, and satellite powder content ≤0.5wt%), low oxygen content (≤0.12wt%), nitrogen content (≤0.05wt%), hydrogen content (≤0.0015wt%), and narrow particle size distribution to ensure powder flowability (loose packing density ≥2.8g / cm³). 3And the uniformity of melting during the SLM forming process;

[0037] Aluminum powder: Spherical aluminum powder with a particle size range of 18~45μm and a purity of ≥99.7% is selected. It also needs to have high sphericity (≥98%) and low impurity content (oxygen content ≤0.08wt%, Fe≤0.1wt%, Si≤0.05wt%). Its function is to adjust the aluminum content of the system by mixing powders, provide a compositional basis for the subsequent formation of γ (TiAl) phase, reduce the porosity between powder layers, improve melting uniformity, and alleviate the thermal stress during SLM forming.

[0038] 2) Powder Mixing: Titanium-aluminum alloy powder and aluminum powder are mixed in a planetary ball mill at a specific mass ratio (2.15~2.45:1) to obtain a mixed powder. The ball milling parameters are set as follows: ball-to-powder ratio 6:1~9:1, rotation speed 220~280 r / min, and milling time 2.5~3.5 h. An argon atmosphere (purity ≥99.999%, dew point ≤-40℃) is used to prevent the powder from absorbing moisture during ball milling and to reduce the introduction of O and H elements caused by H2O decomposition during SLM. Experiments show that when the dew point is ≤-40℃, the oxygen content of the mixed powder increases by only 0.02wt% (compared to 0.05~0.08wt% under conventional argon protection), avoiding TiO2 inclusions formed by γ-phase oxidation (which would reduce elongation by 20~30%). Ball milling achieves uniform dispersion of the titanium-aluminum alloy powder and aluminum powder, while mechanical force refines the powder surface morphology and promotes interfacial bonding in the subsequent SLM process.

[0039] If the rotation speed is too high or the time is too long, the titanium-aluminum alloy powder will be excessively cold-welded, forming agglomerates larger than 100 μm, which cannot be melted during SLM. If the rotation speed is too low or the time is too short, the mixing uniformity will be poor, resulting in Ti-rich areas after printing and the formation of α2 brittle phase. Therefore, this invention optimizes the rotation speed and time to achieve macroscopic uniformity of the mixed powder (composition deviation ≤0.3wt%) and microscopic interface activation (formation of a 5~10nm plastic deformation layer on the surface of the titanium-aluminum alloy powder). This avoids agglomeration and promotes the Ti-Al diffusion reaction during SLM through interfacial mechanical activation, increasing the γ phase formation rate to over 90% (compared to ≤75% for conventional ball milling formulations).

[0040] 3) Laser Melting Additive Manufacturing: Mixed powder is fed into the powder cylinder of the SLM equipment, and printing is performed in an inert gas (such as argon) protective atmosphere (oxygen content ≤0.01%). The core process parameters are as follows: laser power 280~320W, scanning speed 1000~1300mm / s, corresponding to a relatively low energy density (70~100J / mm). 3If the energy density is too high, it can lead to local overheating, grain coarsening (γ phase grains ≥ 50 μm) and thermal stress cracks. The layer thickness is 35~45 μm, and the scanning spacing is 90~110 μm. The scanning strategy is to use bidirectional cross scanning, rotate the layers by 67° to reduce anisotropy, and reduce the edge scanning speed by 20% to increase the density to 120 J / mm. 3 Reduce sphericity effect;

[0041] By controlling the above parameters, the powder is fully melted and rapidly solidified to form fine grains (γ phase grains 10~20μm), and a printed alloy blank with a density ≥97% is obtained. At this time, a mixed structure of titanium-aluminum intermetallic compounds and aluminum phase is initially formed in the blank.

[0042] SLM components are prone to spheroidization at the edges due to rapid heat dissipation and insufficient melting (surface roughness Ra≥15μm). This invention achieves more complete edge melting through high energy density at the edges, reducing the surface roughness to Ra≤8μm. This eliminates the need for subsequent machining to meet the surface precision requirements of aero-engine blades (Ra≤10μm), reducing machining allowance by more than 30%.

[0043] 4) Hot Isostatic Pressing (HIP) Treatment: The printed alloy billet is placed in a hot isostatic pressing apparatus and held at 1100~1250℃ and 100~200MPa for 2~4 hours, then cooled to room temperature with the furnace. This step, through low temperature and high pressure, can eliminate defects such as porosity and microcracks generated during the printing process, increase the density of the billet to ≥99%, and promote atomic diffusion, laying the microstructure basis for the formation of the γ phase. The γ phase grain growth rate is controlled at ≤20%, achieving a synergistic effect of defect elimination and grain refinement.

[0044] 5) Solution heat treatment: The alloy after hot isostatic pressing is heated to 900~1050℃ and held for 2~4h. Then, it is rapidly cooled by oil cooling at a rate of ≥50℃ / min. Finally, a microstructure with γ (TiAl) phase as the matrix and a small amount of α2 (Ti3Al) phase is uniformly distributed is obtained, so as to achieve synergistic optimization of strength and plasticity.

[0045] In this step, rapid oil cooling can suppress the transformation of the γ phase to the α2 phase, stabilizing the α2 phase ratio at 5-8%, while conventional air cooling results in an α2 phase ratio of 12-15%. At the same time, the solution temperature of 900-1000℃ can ensure the uniform distribution of solute atoms (such as Ti and Al) within the γ phase, avoiding brittle fracture caused by local α2 phase enrichment. The room temperature elongation is increased by 0.8-1.2 percentage points compared to the conventional air cooling process.

[0046] This invention also discloses a high-performance γ-based titanium-aluminum alloy prepared by an additive manufacturing method.

[0047] Example 1

[0048] An additive manufacturing method for a high-performance γ-based titanium-aluminum alloy includes the following steps:

[0049] 1) Material selection:

[0050] Titanium-aluminum alloy powder: Spherical titanium-aluminum alloy powder with a particle size range of 25~53μm (D10=25μm, D50=38μm, D90=53μm) is selected. Its main components are titanium (Ti 84.3285%) and aluminum (Al 15%), and the fluctuation of Ti and Al content is controlled within ±0.5wt%. The sphericity is 98%, the satellite powder content is 0.5wt%, the oxygen content is 0.12wt%, the nitrogen content is 0.05wt%, and the hydrogen content is 0.0015wt%.

[0051] Aluminum powder: Spherical aluminum powder with a particle size range of 18~45μm (D50=32μm) is selected, with a purity of 99.85%, an iron content of 0.1wt%, and a silicon content of 0.05wt%.

[0052] 2) Powder Mixing: Titanium-aluminum alloy powder and aluminum powder were mixed in a planetary ball mill at a specific mass ratio (2.3:1). Considering the loss of about 1.5~2wt% of aluminum during the SLM process, an additional 0.4wt% of aluminum powder was added to obtain the mixed powder. The ball milling parameters were set as follows: ball-to-powder ratio 8:1, rotation speed 250r / min, ball milling time 3h. An argon atmosphere (purity ≥99.999%, dew point ≤-40℃) was used to prevent the powder from absorbing moisture during the ball milling process and to reduce the introduction of O and H elements caused by H2O decomposition during SLM. Experiments showed that when the dew point was ≤-40℃, the oxygen content of the mixed powder increased by only 0.02wt% (compared to 0.05~0.08wt% under conventional argon protection), avoiding TiO2 inclusions formed by γ-phase oxidation (which would reduce the elongation by 20~30%). Ball milling is used to achieve uniform dispersion of titanium-aluminum alloy powder and aluminum powder. At the same time, mechanical force is used to refine the surface morphology of the powder and promote interfacial bonding in the subsequent SLM process.

[0053] 3) Laser Melting Additive Manufacturing: The mixed powder is fed into the powder cylinder of the SLM equipment, and printing is performed under an inert gas (argon) protective atmosphere (oxygen content ≤0.01%). The core process parameters are as follows: laser power 300W, scanning speed 1200mm / s, corresponding to a relatively low energy density (80J / mm²). 3 The layer thickness is 40 μm and the scanning interval is 100 μm. The scanning strategy is as follows: bidirectional cross scanning is adopted, interlayer rotation is 67° to reduce anisotropy, and the edge scanning speed is reduced by 20% to reduce sphericity.

[0054] By controlling the above parameters, the powder is fully melted and rapidly solidified to obtain a printed alloy blank with a density of 97.5% and a surface roughness Ra≤8μm. At this time, a mixed structure of titanium-aluminum intermetallic compounds and aluminum phase is initially formed in the blank.

[0055] 4) Hot Isostatic Pressing (HIP) Treatment: The printed alloy billet is placed in a hot isostatic pressing apparatus and held at 1180℃ and 160MPa for 3 hours, then cooled to room temperature with the furnace. This step, through low temperature and high pressure, can eliminate defects such as porosity and microcracks generated during the printing process, increase the density of the billet to ≥99%, and promote atomic diffusion, laying the microstructure basis for the formation of the γ phase. The γ phase grain growth rate is controlled at ≤20%, achieving a synergistic effect of defect elimination and grain refinement.

[0056] 5) Solution heat treatment: The alloy after hot isostatic pressing is heated to 980℃ and held for 2.5h. Then, it is rapidly cooled by oil cooling at a rate of 50℃ / min. Finally, a microstructure with γ (TiAl) phase as the matrix and a small amount of α2 (Ti3Al) phase uniformly distributed is obtained, which achieves synergistic optimization of strength and plasticity.

[0057] This embodiment also discloses a high-performance γ-based titanium-aluminum alloy prepared by an additive manufacturing method.

[0058] Example 2

[0059] An additive manufacturing method for a high-performance γ-based titanium-aluminum alloy includes the following steps:

[0060] 1) Material selection:

[0061] Titanium-aluminum alloy powder: Spherical titanium-aluminum alloy powder with a particle size range of 28~50μm (D10=28μm, D50=40μm, D90=50μm) is selected.

[0062] Aluminum powder: Spherical aluminum powder with a particle size range of 20~42μm (D50=30μm) is selected;

[0063] 2) Powder mixing: Titanium-aluminum alloy powder and aluminum powder are mixed in a planetary ball mill at a specific mass ratio (2.25:1). Considering the loss of about 1.5~2wt% of aluminum during the SLM process, an additional 0.35wt% of aluminum powder is added to obtain mixed powder. The ball milling parameters are set as follows: ball-to-material ratio 7.5:1, rotation speed 230r / min, ball milling time 3.2h, and argon gas (purity ≥99.999%, dew point ≤-40℃) protective atmosphere is used.

[0064] 3) Laser Melting Additive Manufacturing: The mixed powder is fed into the powder cylinder of the SLM equipment, and printing is performed under an inert gas (argon) protective atmosphere (oxygen content ≤0.01%). The core process parameters are as follows: laser power 290W, scanning speed 1100mm / s, corresponding to a relatively low energy density (75J / mm). 3 The layer thickness is 38 μm and the scanning interval is 95 μm. The scanning strategy is as follows: bidirectional cross scanning is used, interlayer rotation is 67° to reduce anisotropy, and the edge scanning speed is reduced by 20% to reduce sphericity.

[0065] By controlling the above parameters, the powder is fully melted and rapidly solidified to obtain a printed alloy blank with a density of 97.8%. At this time, a mixed structure of titanium-aluminum intermetallic compound and aluminum phase is initially formed in the blank. For complex structural parts with a wall thickness of 2mm, the forming accuracy reaches ±0.08mm.

[0066] 4) Hot Isostatic Pressing (HIP) treatment: The printed alloy billet is placed in a hot isostatic pressing equipment and held at 1160℃ and 170MPa for 3.2h, and then cooled to room temperature with the furnace.

[0067] 5) Solution heat treatment: The alloy after hot isostatic pressing is heated to 960℃ and held for 2.8h. Then, it is rapidly cooled by oil cooling at a rate of 50℃ / min. Finally, a microstructure with γ (TiAl) phase as the matrix and a small amount of α2 (Ti3Al) phase uniformly distributed is obtained, which achieves synergistic optimization of strength and plasticity.

[0068] This embodiment also discloses a high-performance γ-based titanium-aluminum alloy prepared by an additive manufacturing method.

[0069] The rest is the same as in Example 1.

[0070] The high-temperature performance of the high-performance γ-based titanium-aluminum alloys obtained in Examples 1-2 was tested, and the results are as follows:

[0071] Example 1: The tensile strength at 800℃ is 420MPa, and the creep rupture life reaches 110h under a 100MPa load; the oxidation weight gain at 800℃ / 100h is only 0.08mg / cm³. 2 Anisotropy: The ratio of horizontal to vertical tensile strength is 0.96.

[0072] Example 2: The tensile strength at 800℃ is 410MPa, and the creep rupture life reaches 105h under a 100MPa load; the oxidation weight gain at 800℃ / 100h is only 0.09mg / cm³. 2Complex structure forming effect: A complex combustion chamber structure with multiple cooling film holes (0.8 mm in diameter) and a wall thickness of 2 mm was successfully prepared. There were no internal defects such as cracks and pores, and the defect rate was ≤0.08%.

[0073] Compared with existing technologies, the present invention has at least the following technical effects:

[0074] Compared to traditional casting processes, which are unable to form complex thin-walled structures with a wall thickness of ≤3mm and are prone to problems such as incomplete filling and cracking, this invention successfully fabricates structural parts with a wall thickness of 2mm and tiny cooling film pores by optimizing powder properties (such as particle size matching and high purity) and SLM process parameters (such as energy density and scanning strategies optimized for complex structures). The forming qualification rate has been increased from 50% in traditional processes to 96%.

[0075] Compared to other additive manufacturing cases of γ-TiAl alloys, some existing additive manufacturing processes do not consider powder burn-off compensation, leading to component composition deviations and unstable performance. This invention, through precise burn-off compensation design, ensures stable component composition and good performance consistency. Furthermore, in terms of forming accuracy and defect control for complex structures, this case, through refined process parameters, outperforms most similar studies, providing a more reliable solution for manufacturing complex structural components of gas turbine combustors.

[0076] Any parts or structures not specifically described in this invention can be made using existing technologies or products, and will not be elaborated upon here.

[0077] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for additive manufacturing of high-performance γ-based titanium-aluminum alloys, characterized in that, Includes the following steps: 1) Select titanium-aluminum alloy powder and aluminum powder; 2) Powder mixing: Titanium-aluminum alloy powder and aluminum powder are mixed to obtain mixed powder; 3) Laser melting additive manufacturing: The mixed powder is fed into the SLM equipment and printed in an inert gas protective atmosphere to obtain a printed alloy blank with a density of ≥97%. At this time, a mixed structure of titanium-aluminum intermetallic compounds and aluminum phase is initially formed in the blank. 4) Place the printed alloy blank in a hot isostatic pressing (HIP) apparatus for hot isostatic pressing treatment; 5) The alloy after hot isostatic pressing is subjected to solution heat treatment; In step 1), the titanium-aluminum alloy powder is spherical titanium-aluminum alloy powder with a particle size of 25~53μm; the aluminum powder is spherical aluminum powder with a particle size of 18~45μm and a purity of ≥99.7%. In step 2), the mass ratio of the titanium-aluminum alloy powder to the aluminum powder is 2.15~2.45:1, and aluminum powder is added in addition at 0.3~0.5wt%.

2. The additive manufacturing method for a high-performance γ-based titanium-aluminum alloy according to claim 1, characterized in that, In step 2), titanium-aluminum alloy powder and aluminum powder are mixed in a planetary ball mill. The ball milling parameters are set as follows: ball-to-material ratio 6:1 to 9:1, rotation speed 220 to 280 r / min, and ball milling time 2.5 to 3.5 h. An argon protective atmosphere is used to avoid powder oxidation.

3. The additive manufacturing method for a high-performance γ-based titanium-aluminum alloy according to claim 1, characterized in that, In step 3), the process parameters are set as follows: laser power 280~320W, scanning speed 1000~1300mm / s, layer thickness 35~45μm, and scanning spacing 90~110μm.

4. The additive manufacturing method for a high-performance γ-based titanium-aluminum alloy according to claim 1, characterized in that, In step 3), the scanning strategy is as follows: bidirectional cross scanning is adopted, interlayer rotation is 67° to reduce anisotropy, edge scanning speed is reduced by 20%, and spheroidization effect is reduced.

5. The additive manufacturing method for a high-performance γ-based titanium-aluminum alloy according to claim 1, characterized in that, In step 4), the printed alloy blank is placed in a hot isostatic pressing equipment and held at a temperature of 1100~1250℃ and a pressure of 100~200MPa for 2~4 hours, and then cooled to room temperature with the furnace.

6. The additive manufacturing method for a high-performance γ-based titanium-aluminum alloy according to claim 1, characterized in that, In step 5), the alloy after hot isostatic pressing is heated to 900~1050℃, held for 2~4 hours, and then rapidly cooled by oil cooling.

7. The high-performance γ-based titanium-aluminum alloy prepared by the additive manufacturing method of any one of claims 1-6.