Titanium-aluminum alloy blade with service temperature of 850 DEG C and preparation method and application thereof

Abstract

The invention belongs to the technical field of high-temperature structural materials and powder metallurgy forming, and particularly discloses a titanium-aluminum alloy blade with the service temperature being 850 DEG C and a preparation method and application of the titanium-aluminum alloy blade with the service temperature being 850 DEG C. The preparation method comprises the steps that 1, titanium-aluminum alloy powder containing specific components (Ti, Al, Ta, Nb and W and controlling the content of O and N in impurities) is prepared, and powder with the set granularity is screened; (2) bagging and degassing treatment; (3) performing hot isostatic pressing treatment of staged temperature control on the sheath filled with the powder; and (4) the sheath is removed through machining, and the titanium-aluminum alloy blade is obtained. The blade obtained through the preparation method is subjected to near-net forming, complex heat treatment is not needed, the preparation period is greatly shortened, the preparation efficiency is improved, meanwhile, the room-temperature elongation of the prepared titanium-aluminum alloy blade is larger than or equal to 1.3%, the yield strength at 850 DEG C is larger than or equal to 340 MPa, the oxidation resistance is excellent, and the endurance life is excellent. And the requirements of aero-engines, gas turbines and the like on high-temperature service and light weight of the blades are completely met.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature structural materials and powder metallurgy forming technology, and particularly relates to a titanium-aluminum alloy blade with a service temperature of 850 °C, a preparation method and an application thereof, and is particularly suitable for manufacturing lightweight hot-end components of high-end equipment such as aeroengines and gas turbines. Background Art

[0002] Titanium aluminide (TiAl) alloy has become an ideal material to replace nickel-based superalloys due to its low density (about 4.0 g / cm 3 ), high specific strength, and excellent high-temperature oxidation resistance, and has broad application prospects in high-end equipment fields such as low-pressure turbine blades of aeroengines and gas turbine blades. It can achieve equipment upgrade and performance improvement by reducing weight. For example, Ti-48Al-2Cr-2Nb (at.%) alloy was successfully applied to the sixth and seventh stages of the low-pressure turbine blades of the GEnX engine as early as 2012, which improved the fuel efficiency by about 20%, reduced the nitrogen oxide emissions by 80%, and reduced the noise by 50%. It is a commercially successful TiAl alloy. With the development of additive manufacturing technology, in 2020, Ti-48Al-2Cr-2Nb alloy blades prepared by additive manufacturing technology were applied in the GE9X engine. TNM alloy (Ti-43.5Al-4Nb-1Mo-0.1B, at.%) was also applied to a geared turbofan engine by Pratt & Whitney in 2014.

[0003] However, the Ti-48Al-2Cr-2Nb alloy has poor high-temperature performance and oxidation resistance and can only be applied under working conditions of about 650 °C. Although TNM alloy and high-Nb titanium-aluminum alloy have excellent high-temperature mechanical properties and oxidation resistance, their structures are unstable after long-term high-temperature service, which easily leads to performance degradation or even failure. Therefore, it is difficult to apply them to working conditions above 750 °C.

[0004] In casting, the peritectic titanium-aluminum alloy containing low contents of Nb and Ta has good oxidation resistance and tissue stability at 850 °C. However, the cast alloy needs to undergo high-temperature long-term homogenization and cyclic heat treatment or multi-step heat treatment for tissue regulation. The complex heat treatment method is not conducive to engineering application, and it is also difficult to avoid casting defects and composition segregation problems. For complex-shaped parts such as blades, there are also problems such as high processing difficulty and low yield.

[0005] Powder metallurgy technology can avoid defects such as composition segregation and inconsistent microstructure during the casting process, eliminate porosity and shrinkage cavities, and can directly prepare near-net-shaped products. For titanium aluminide alloys with poor plasticity, difficult machining, and refractory elements added, it has significant advantages in forming and homogenization. On this basis, by adopting a specific short-process hot isostatic pressing stage temperature control strategy, while meeting the service performance, the characteristics of short process and simple procedures are conducive to engineering promotion and are expected to be applied to the manufacture of low-pressure turbine blades of titanium aluminide alloys for the new generation of engines.

[0006] In the inventions with application numbers 201710305177.6 and 202410307434.X, a cast titanium aluminide alloy suitable for 800 °C is disclosed. The above inventions are directed to high-Al medium-Nb cast γ-TiAl alloys with peritectic solidification, which improve the strength while ensuring good oxidation resistance and casting performance of the alloy, and are suitable for manufacturing hot-end components such as low-pressure turbine blades of aerospace aircraft. However, in this method, the titanium aluminide alloy adds elements with relatively high density such as Nb and Ta, and it is difficult to avoid composition segregation and non-uniform microstructure in the cast alloy. If an ideal microstructure with uniform fineness is to be obtained, complex heat treatment regulation is required, which is not conducive to engineering applications.

[0007] In the invention with application number 20201043700.1, a preparation method of powder metallurgy titanium aluminide alloy parts is disclosed. After mechanical mixing of raw material powders, cold isostatic pressing forming, hot pressing sintering, and finally hot isostatic pressing densification are adopted, but its oxygen content can only be controlled to be no more than 0.15 wt.%, which is not conducive to high-temperature service performance.

[0008] In view of this, this invention is specifically proposed. Summary of the Invention

[0009] The purpose of the present invention is to overcome the shortcomings of the above-mentioned existing technologies, and provide a titanium aluminide alloy blade with a service temperature of 850 °C, its preparation method and application, mainly to solve the problems of insufficient performance, complex process, and large blade processing difficulty of existing titanium aluminide alloys during high-temperature service. The present invention realizes the stable service of titanium aluminide alloy blades in a high-temperature environment of 850 °C through optimizing alloy composition design and short-process powder metallurgy technology, and at the same time significantly improves the engineering preparation efficiency.

[0010] The purpose of the present invention is solved by the following technical solutions: In the first aspect, the present invention provides a preparation method of a titanium aluminide alloy blade with a service temperature of 850 °C, and the preparation method includes the following steps: Step 1: Prepare titanium aluminide alloy powder First, prepare titanium-aluminum alloy powder by the plasma rotating electrode process. The composition of the titanium-aluminum alloy powder includes: 45 - 48.5 at.% of Al, 1 - 3 at.% of Ta, 1 - 3 at.% of Nb, and 0 - 0.5 at.% of W, with the rest being Ti and inevitable impurities. Also, control the impurities such that O ≤ 600 ppm and N ≤ 200 ppm. Then, screen to obtain titanium-aluminum alloy powder with a set particle size. Step 2: Package and degas Previously, design and fabricate a package according to the specifications of the titanium-aluminum alloy blade. Load the titanium-aluminum alloy powder obtained by screening in Step 1 into the package. During the powder loading process, vibrate and simultaneously introduce CO gas, and perform heat preservation and degassing. Subsequently, maintain the temperature and evacuate to ≤ 1×10 -3 Pa; Step 3: Perform hot isostatic pressing on the powder-loaded package with temperature controlled in stages. Step 4: Machine-process to remove the package to obtain a titanium-aluminum alloy blade.

[0011] Furthermore, in Step 1, the composition of the titanium-aluminum alloy powder is 46.5 - 48.3 at.% of Al, 1.3 - 3 at.% of Ta, 1 - 2.8 at.% of Nb, 0.1 - 0.5 at.% of W, with the rest being Ti and inevitable impurities.

[0012] Furthermore, in Step 1, for the impurities in the titanium-aluminum alloy powder, O ≤ 500 ppm and N ≤ 150 ppm.

[0013] Furthermore, in Step 1, the particle size of the titanium-aluminum alloy powder obtained by screening is 53 μm - 150 μm.

[0014] Furthermore, in Step 2, the material of the package is pure titanium.

[0015] Furthermore, in Step 2, the flow rate of the introduced CO gas is 50 mL / min - 100 mL / min; When performing heat preservation and degassing, the temperature is set to 600 °C - 700 °C, and the time is set to 0.5 h - 1.5 h.

[0016] Furthermore, in Step 3, the hot isostatic pressing process is divided into the following three stages: The first stage: In the α + γ two-phase region, the temperature is 1250 °C - 1300 °C, the pressure is 110 MPa - 160 MPa, and heat preservation is for 2 h - 5 h; The second stage: Heat up to the α single-phase region, the temperature is 1350 °C - 1420 °C, heat preservation is for 15 min - 40 min, and then furnace cool to the α + γ two-phase region, the temperature is 1250 °C - 1320 °C; The third stage: rapidly cool to 800 °C - 900 °C at a cooling rate of 15 °C / min - 25 °C / min, hold for 3 h - 5 h to relieve stress, and then cool to room temperature in the furnace.

[0017] It should be noted that in the hypereutectic titanium aluminide alloy system containing Al of the present invention, Ta, Nb and W elements with specific ratios are innovatively added. Ta, Nb and W synergistically improve the high-temperature strength, creep resistance and oxidation resistance of the alloy. Among them, the effects of Ta and Nb are significant and the effect of Ta is better; Ta can also reduce the interfacial energy, promote the transformation of metastable structures, and achieve grain refinement. However, high-melting-point elements are prone to cause compositional segregation, and adding a large amount will increase the density and cost. Therefore, the addition amount needs to be strictly controlled. In addition, the present invention selects a vacuum arc consumable melting method to prepare a high-purity titanium aluminide alloy ingot as the raw material, combines the ultra-high-speed plasma rotating electrode process (SS-PREP ® ), powders are made, and powder hot isostatic pressing is carried out. This process can effectively improve the segregation problem of Ta, Nb and W elements, ensure that the structure is uniform and fine; combined with the temperature control strategy in the hot isostatic pressing stage, the structure transformation is accurately regulated, and finally a titanium aluminide alloy blade with a fine near-lamellar structure is obtained, meeting the stringent requirements for high-temperature service at 850 °C.

[0018] In the second aspect, the present invention also provides a titanium aluminide alloy blade with a service temperature of 850 °C, and the titanium aluminide alloy blade is prepared based on the above preparation method.

[0019] Furthermore, the properties of the titanium aluminide alloy blade are as follows: the room-temperature tensile elongation rate ≥ 1.3%, the 850 °C tensile yield strength ≥ 340 MPa, the 850 °C oxidation weight gain ≤ 0.9 mg / cm 2 , the 850 °C / 125 MPa creep rupture life ≥ 130 h.

[0020] In the third aspect, the present invention also provides an application of the above titanium aluminide alloy blade, and the titanium aluminide alloy blade is applied to the manufacture of lightweight blades for aeroengines or gas turbines in a high-temperature service environment at 850 °C.

[0021] Specifically, due to its excellent high-temperature strength, creep resistance, oxidation resistance and lightweight characteristics, the titanium aluminide alloy blade can directly replace traditional nickel-based superalloy blades and is suitable for the following scenarios: Aeroengine field: As the low-pressure turbine blade (such as the sixth and seventh stages of the low-pressure turbine of a turbofan engine), by reducing the weight, the moment of inertia is reduced, the thrust-to-weight ratio and fuel efficiency of the engine are improved (10% - 15% higher than traditional alloys), and at the same time, the nitrogen oxide emissions are reduced (by more than 30%).

[0022] Field of gas turbines: Applied to high-temperature section blades (such as the rear section of the compressor, turbine guide vanes), it can adapt to long-term high-temperature working conditions while maintaining high strength, extend the service life of equipment, and reduce maintenance costs.

[0023] Compared with the prior art, the present invention has the following beneficial effects: By adding appropriate amounts of Ta, Nb, and W elements to the hypereutectic titanium aluminide alloy and strictly controlling the contents of O and N impurities, the present invention significantly improves the room-temperature plasticity, high-temperature strength, creep properties, and oxidation resistance of the alloy. Among them, the Ta element realizes grain refinement and strengthening by reducing the formation energy of the metastable γ-phase structure. At the same time, a short-process powder hot isostatic pressing strategy with staged temperature control is adopted, effectively improving the problem of compositional segregation of high-melting-point elements and obtaining a fine, uniform, and isotropic near-lamellar structure. Specifically, in the first stage, hot isostatic pressing is carried out in the α + γ two-phase region to achieve powder densification and forming, obtaining a titanium aluminide alloy blade with a dense structure; in the second stage, short-time heat preservation is carried out in the α single-phase region to approximately transform the microstructure of the titanium aluminide alloy blade into an α single-phase structure, preparing for the next tissue regulation; in the third stage, during the rapid cooling from the α single-phase region to 800 °C - 900 °C, the α→α2 + γ phase transformation occurs. Since the γ phase and the α phase follow the Blackburn orientation relationship, six γ-phase variants can be formed within a single α grain, and the γ lamellae precipitate along different directions, obtaining a near-lamellar structure and simultaneously realizing grain refinement. Subsequently, stress relief is carried out by heat preservation at 800 °C - 900 °C, and then furnace cooling to room temperature, finally obtaining a titanium aluminide alloy blade with performance meeting service requirements. The present invention can complete near-net forming and tissue regulation through only one hot isostatic pressing process, without traditional complex heat treatment, not only greatly shortening the preparation cycle, but also improving the material utilization rate. At the same time, the prepared blade has excellent properties of a tensile yield strength ≥ 340 MPa, an oxidation weight gain ≤ 0.9 mg / cm 2 and a creep rupture life ≥ 130 h at a high temperature of 850 °C, breaking through the bottleneck of insufficient high-temperature service performance and high engineering preparation difficulty of traditional titanium aluminide alloys, and providing an efficient and low-cost solution for the manufacturing of lightweight hot-end components of high-end equipment such as aeroengines and gas turbines. Description of the Drawings

[0024] The drawings here are incorporated into the specification and form a part of this specification, and are used together with the specification to explain the principles of the present invention.

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0026] Figure 1This is the flow chart of the preparation method of the titanium-aluminum alloy blade of the present invention; Figure 2 This is the microstructure diagram of the titanium-aluminum alloy blade A prepared in Example 1 of the present invention; Figure 3 This is the microstructure diagram of the titanium-aluminum alloy blade B prepared in Example 2 of the present invention; Figure 4 This is the microstructure diagram of the titanium-aluminum alloy blade C prepared in Example 3 of the present invention. Detailed implementation manners

[0027] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present invention. On the contrary, they are only examples consistent with some aspects of the present invention detailed in the appended claims.

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0029] Please refer to Figure 1 , a preparation method of a titanium-aluminum alloy blade with a service temperature of 850 °C provided by the present invention specifically includes the following steps: Step 1, preparing titanium-aluminum alloy powder First, prepare titanium-aluminum alloy powder by the plasma rotating electrode process. The composition of the titanium-aluminum alloy powder includes: 45-48.5 at.% of Al, 1-3 at.% of Ta, 1-3 at.% of Nb, and 0-0.5 at.% of W, and the rest is Ti and inevitable impurities, and control O≤600 ppm and N≤200 ppm in the impurities; then screen to obtain titanium-aluminum alloy powder with a set particle size.

[0030] Specifically, when preparing titanium-aluminum alloy powder by the plasma rotating electrode process, the end of the titanium-aluminum alloy rod is uniformly melted, and the atomized droplets are thrown out from the end of the titanium-aluminum alloy rod under the action of centrifugal force to form fine droplets. The droplets are rapidly cooled into spherical particles in an inert gas environment and fall into the collector at the bottom of the reaction chamber to obtain full-size titanium-aluminum alloy powder; then, after screening under the protection of an inert atmosphere, titanium-aluminum alloy powder with a particle size of 53 μm to 150 μm is obtained. The reason why the present invention uses powder with this particle size range is as follows: If the powder particle size is too fine, it will lead to too high oxygen content and is also likely to form original particle boundaries in the powder metallurgy structure, thereby affecting the part performance; if the powder particle size is too coarse, it will cause too large initial grain size; if the powder particle size range is too wide, it will lead to poor uniformity of the powder metallurgy structure.

[0031] Preferably, the titanium-aluminum alloy powder has the following composition: 46.5 - 48.3 at.% Al, 1.3 - 3 at.% Ta, 1 - 2.8 at.% Nb, and 0.1 - 0.5 at.% W, with the balance being Ti and inevitable impurities, and controlling O ≤ 500 ppm and N ≤ 150 ppm in the impurities.

[0032] Step 2: Packing with a sheath and degassing treatment Previously, design and fabricate a sheath according to the specifications of the titanium-aluminum alloy blade, load the titanium-aluminum alloy powder obtained by sieving in Step 1 into the sheath, vibrate during the powder loading process, simultaneously introduce CO gas, and perform heat preservation and degassing. Subsequently, maintain the temperature and evacuate to ≤ 1×10 -3 Pa.

[0033] Specifically, the sheath is made of pure titanium to avoid introducing other impurities during hot isostatic pressing. The flow rate of the introduced CO gas is 50 mL / min - 100 mL / min. During heat preservation and degassing, the temperature is set to 600 °C - 700 °C, and the time is set to 0.5 h - 1.5 h to remove surface oxides. Subsequently, maintain the temperature and evacuate to ≤ 1×10 -3 Pa.

[0034] Step 3: Perform hot isostatic pressing treatment with temperature control in stages on the powder-packed sheath.

[0035] Specifically, the hot isostatic pressing treatment is divided into the following three stages: The first stage: In the α + γ two-phase region, the temperature is 1250 °C - 1300 °C, the pressure is 110 MPa - 160 MPa, and heat preservation is carried out for 2 h - 5 h. During this stage, densification and forming are achieved while avoiding excessive grain growth; The second stage: Heat up to the α single-phase region, the temperature is 1350 °C - 1420 °C, heat preservation is carried out for 15 min - 40 min, and then furnace cool to the α + γ two-phase region, the temperature is 1250 °C - 1320 °C; The third stage: Rapidly cool at a cooling rate of 15 °C / min - 25 °C / min to 800 °C - 900 °C, heat preservation is carried out for 3 h - 5 h to remove stress, and then furnace cool to room temperature.

[0036] Step 4: Remove the sheath by machining to obtain the titanium-aluminum alloy blade.

[0037] To further verify the efficacy of the present invention, the inventor conducted the following specific experiments: Example 1

[0038] In this example, a certain model of titanium-aluminum alloy blade A for an aeroengine is prepared, and its detailed preparation process is as follows: 1) Prepare titanium aluminide powder by the plasma rotating electrode process, and screen it under the protection of an inert atmosphere (argon gas) to obtain titanium aluminide powder with a particle size of 53 μm to 150 μm.

[0039] Specifically, the composition of the titanium aluminide powder is as follows: the Al content is 46.5 at.%, the Ta content is 1.3 at.%, the Nb content is 2.8 at.%, the W content is 0.3 at.%, and the rest is Ti and inevitable impurities. The O content in the impurities is 500 ppm, and the N content is 150 ppm.

[0040] 2) Design and fabricate a pure titanium sheath in advance according to the specifications of the titanium aluminide blade A, and load the titanium aluminide powder obtained by screening in step 1) into the sheath. During the powder loading process, vibrate and simultaneously introduce CO gas with a flow rate of 50 mL / min. Keep it at 650 °C for 1 h for degassing. After 1 h, stop introducing CO gas and keep it at 650 °C and evacuate to 8.3×10 -4 Pa.

[0041] 3) Perform hot isostatic pressing on the powder-loaded sheath with temperature controlled in stages.

[0042] Specifically, the hot isostatic pressing process is divided into the following three stages: The first stage: in the α+γ two-phase region, the temperature is 1250 °C, the pressure is 110 MPa, and the holding time is 5 h; The second stage: heat up to the α single-phase region, the temperature is 1350 °C, the holding time is 15 min, and then cool in the furnace to the α+γ two-phase region, the temperature is 1250 °C; The third stage: quickly cool to 800 °C at a cooling rate of 15 °C / min, hold for 5 h, and then cool in the furnace to room temperature.

[0043] Step 4, remove the sheath by machining to obtain the titanium aluminide blade A. Example 2

[0044] In this example, a certain model of titanium aluminide blade B for a gas turbine is prepared, and its detailed preparation process is as follows: 1) Prepare titanium aluminide powder by the plasma rotating electrode process, and screen it under the protection of an inert atmosphere (argon gas) to obtain titanium aluminide powder with a particle size of 53 μm to 150 μm.

[0045] Specifically, the composition of the titanium aluminide powder is as follows: the Al content is 47.2 at.%, the Ta content is 2.2 at.%, the Nb content is 1.5 at.%, the W content is 0.1 at.%, and the rest is Ti and inevitable impurities. The O content in the impurities is 400 ppm, and the N content is 100 ppm.

[0046] 2) Design and fabricate a pure titanium sheath in advance according to the specifications of the titanium-aluminum alloy blade B. Load the titanium-aluminum alloy powder obtained by sieving in step 1) into the sheath. During the powder loading process, vibrate and simultaneously introduce CO gas at a flow rate of 75 mL / min. Keep the temperature at 600 °C for 1.5 h for degassing. After 1.5 h, stop introducing CO gas and keep the temperature at 600 °C while evacuating to 9.8×10 -4 Pa.

[0047] 3) Perform hot isostatic pressing on the powder-loaded sheath with temperature controlled in stages.

[0048] Specifically, the hot isostatic pressing process is divided into the following three stages: The first stage: in the α+γ two-phase region, the temperature is 1275 °C, the pressure is 135 MPa, and the holding time is 3 h; The second stage: Raise the temperature to the α single-phase region, the temperature is 1385 °C, the holding time is 25 min, and then cool in the furnace to the α+γ two-phase region, the temperature is 1285 °C; The third stage: Rapidly cool to 850 °C at a cooling rate of 18 °C / min, hold for 4 h, and then cool in the furnace to room temperature.

[0049] Step 4, Remove the sheath by machining to obtain the titanium-aluminum alloy blade B. Example 3

[0050] In this example, a certain model of titanium-aluminum alloy blade C for an aeroengine is prepared, and its detailed preparation process is as follows: 1) Prepare titanium-aluminum alloy powder by the plasma rotating electrode process, and sieve it under the protection of an inert atmosphere (argon) to obtain titanium-aluminum alloy powder with a particle size of 53 μm to 150 μm.

[0051] Specifically, the composition of the titanium-aluminum alloy powder is as follows: the Al content is 48.3 at.%, the Ta content is 3 at.%, the Nb content is 1 at.%, the W content is 0.5 at.%, and the rest is Ti and unavoidable impurities. The O content in the impurities is 350 ppm, and the N content is 60 ppm.

[0052] 2) Design and fabricate a pure titanium sheath in advance according to the specifications of the titanium-aluminum alloy blade C. Load the titanium-aluminum alloy powder obtained by sieving in step 1) into the sheath. During the powder loading process, vibrate and simultaneously introduce CO gas at a flow rate of 100 mL / min. Keep the temperature at 700 °C for 0.5 h for degassing. After 0.5 h, stop introducing CO gas and keep the temperature at 700 °C while evacuating to 9.2×10 -4 Pa.

[0053] 3) Perform hot isostatic pressing on the powder-loaded sheath with temperature controlled in stages.

[0054] Specifically, the hot isostatic pressing process is divided into the following three stages: The first stage: in the α+γ two-phase region, the temperature is 1300 °C, the pressure is 160 MPa, and the heat preservation time is 2 h; The second stage: heat up to the α single-phase region, the temperature is 1420 °C, the heat preservation time is 40 min, and furnace cool to the α+γ two-phase region, the temperature is 1320 °C; The third stage: rapidly cool to 900 °C at a cooling rate of 25 °C / min, keep warm for 3 h, and then furnace cool to room temperature.

[0055] Step 4, remove the cladding by machining to obtain the titanium aluminide blade C.

[0056] Performance detection The internal microstructure, mechanical properties at room temperature and at 850 °C high temperature of the titanium aluminide blades prepared in Examples 1 to 3 were respectively detected. Among them, Figures 2 to 4 are the scanning electron microscope microstructures of the titanium aluminide blades prepared in Examples 1 to 3; Table 1 below shows the mechanical property test results of the titanium aluminide blades prepared in Examples 1 to 3 at room temperature and at 850 °C high temperature. Table 1 Mechanical property test results of the titanium aluminide blades prepared in Examples 1 to 3

[0057]

[0058] Through Figures 2 to 4 the corresponding microstructures, it can be seen that the titanium aluminide blades prepared in Examples 1 to 3 of the present invention all have fine near-lamellar stable microstructures, the α2 lamellae and γ lamellae are arranged alternately to form lamellar clusters, the average lamellar cluster size is about 100 μm to 200 μm, and fine equiaxed γ phases are distributed between the lamellar clusters; in addition, through the mechanical property test results of the titanium aluminide blades prepared in Examples 1 to 3 in Table 1, it can be seen that the room temperature tensile elongation rate ≥ 1.3%, the 850 °C tensile yield strength ≥ 340 MPa, the 850 °C oxidation weight gain ≤ 0.9 mg / cm 2 , the 850 °C / 125 MPa creep life ≥ 130 h. It fully meets the requirements of aeroengines and gas turbines for the high-temperature service and lightweight of blades.

[0059] The above are only the specific embodiments of the present invention, which enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0060] It should be understood that the present invention is not limited to the above-described content and can be modified and changed without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A preparation method of a titanium-aluminum alloy blade with a service temperature of 850 °C, characterized in that, The preparation method comprises the following steps: Step 1: Prepare titanium-aluminum alloy powder First, prepare titanium-aluminum alloy powder by the plasma rotating electrode process. The composition of the titanium-aluminum alloy powder includes: 45-48.5 at.% of Al, 1-3 at.% of Ta, 1-3 at.% of Nb, and 0-0.5 at.% of W, with the balance being Ti and inevitable impurities, and control the impurities so that O≤600 ppm and N≤200 ppm; then screen to obtain titanium-aluminum alloy powder with a set particle size; Step 2: Package and degas treatment Pre-manufacture a sheath according to the specifications of the titanium-aluminum alloy blade in advance, load the titanium-aluminum alloy powder obtained by sieving in step 1 into the sheath, vibrate during the powder loading process, simultaneously introduce CO gas, and keep warm for degassing. Subsequently, keep the temperature and evacuate to ≤1×10 -3 Pa; Step 3: Perform hot isostatic pressing treatment on the packaged powder with temperature controlled in stages; Step 4: Machine-process to remove the package to obtain a titanium-aluminum alloy blade.

2. The preparation method of the titanium aluminide blade with a service temperature of 850 °C according to claim 1, characterized in that In Step 1, the composition of the titanium-aluminum alloy powder is 46.5-48.3 at.% of Al, 1.3-3 at.% of Ta, 1-2.8 at.% of Nb, and 0.1-0.5 at.% of W, with the balance being Ti and inevitable impurities.

3. The preparation method of the titanium aluminide blade with a service temperature of 850 °C according to claim 2, characterized in that, In Step 1, O≤500 ppm and N≤150 ppm in the impurities of the titanium-aluminum alloy powder.

4. The preparation method of the titanium-aluminum alloy blade with a service temperature of 850 °C according to claim 1, characterized in that, In Step 1, the particle size of the titanium-aluminum alloy powder obtained by screening is 53 μm-150 μm.

5. The preparation method of the titanium aluminide blade with a service temperature of 850 °C according to claim 1, characterized in that, In Step 2, the material of the package is pure titanium.

6. The preparation method of the titanium aluminide blade with a service temperature of 850 °C according to claim 1, wherein, In Step 2, the flow rate of the CO gas introduced is 50 mL / min-100 mL / min; When heat-preserving and degassing, the temperature is set at 600°C-700°C and the time is set at 0.5 h-1.5 h.

7. The preparation method of the titanium-aluminum alloy blade with a service temperature of 850 °C according to claim 1, characterized in that, In Step 3, the hot isostatic pressing treatment is divided into the following three stages: The first stage: In the α+γ two-phase region, the temperature is 1250°C-1300°C, the pressure is 110 MPa-160 MPa, and heat is preserved for 2 h-5 h; The second stage: Heat up to the α single-phase region, the temperature is 1350°C-1420°C, heat is preserved for 15 min-40 min, and then furnace-cool to the α+γ two-phase region, the temperature is 1250°C-1320°C; The third stage: Rapidly cool at a cooling rate of 15°C / min-25°C / min to 800°C-900°C, heat is preserved for 3 h-5 h to remove stress, and then furnace-cool to room temperature.

8. A titanium aluminide blade with a service temperature of 850 °C, characterized in that, The titanium-aluminum alloy blade is prepared by the preparation method according to any one of claims 1-7.

9. The titanium aluminide blade with a service temperature of 850°C according to claim 8, wherein The properties of the titanium-aluminum alloy blade are as follows: the tensile elongation at room temperature is ≥1.3%, the tensile yield strength at 850°C is ≥340 MPa, the oxidation weight gain at 850°C is ≤0.9 mg / cm 2 , and the creep rupture life at 850°C / 125 MPa is ≥130 h.

10. Use of a titanium-aluminum alloy blade as described in claim 8 or 9, characterized in that, The titanium-aluminum alloy blade is applied to the manufacture of lightweight blades for aeroengines or gas turbines in a high-temperature service environment of 850°C.

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