Ti2AlNb alloy thin strip with high Nb content O-rich phase interlayer and preparation method thereof

Abstract

The application belongs to the technical field of metallurgy, and particularly relates to a Ti2AlNb alloy thin strip with a high-Nb-content O-phase interlayer and a preparation method thereof. The following steps are performed: (1) a Ti2AlNb alloy thin strip is prepared through thin strip casting and rolling, the thin strip is single B2 phase, sandwich structure, the grain size in the middle is 20-100 mu m, and the grain size in the outer layer is 100-300 mu m; (2) the Ti2AlNb alloy thin strip is treated through ultra-short-time high-temperature treatment, the treatment temperature is 750-950 DEG C, and the holding time is 3-15 min; (3) a Ti2AlNb alloy thin strip with uniformly dispersed nano O phase is obtained, the nano O phase is distributed in the B2 phase grain, the high-Nb interlayer has more nano O phase, the thin strip has the dual advantages of high strength and plasticity, and the Ti2AlNb alloy thin strip with a high-Nb-content interlayer structure and nano O phase is prepared through thin strip casting and rolling + ultra-short-time high-temperature treatment.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically a Ti2AlNb alloy thin strip with a high Nb content and O-rich phase interlayer and its preparation method. Background Technology

[0002] Against the backdrop of rapid iteration in aerospace and high-end equipment manufacturing towards lightweight, high-temperature resistance, and high reliability, traditional structural materials are no longer sufficient to meet the performance requirements under extreme operating conditions. Ti2AlNb-based alloys, as a novel intermetallic compound material, inherit the excellent specific strength and corrosion resistance of titanium alloys while also possessing the lightweight advantages and high-temperature structural stability of aluminum alloys. Their operating temperature can stably reach 650~750℃, far exceeding that of conventional titanium alloys, making them one of the ideal candidate materials to replace nickel-based high-temperature alloys.

[0003] The most advantageous product of Ti2AlNb alloy is Ti2AlNb alloy strip. With its thinness, high formability potential, and flexible structural design, it shows broad application prospects in core components such as aero-engine blades, spacecraft skins, and critical load-bearing structures in high-speed trains. Compared to bulk Ti2AlNb alloy materials, strips not only further reduce equipment weight and improve power efficiency, but also allow for complex shape forming through plastic processing techniques such as rolling and stamping, meeting the integrated and precision design requirements of high-end equipment. However, Ti2AlNb alloy itself has inherent challenges such as low room temperature plasticity, narrow processing window, susceptibility to cracking during forming, and high springback. These problems are further amplified in the processing and application of strips, severely hindering their industrialization. Therefore, there is an urgent need to develop Ti2AlNb alloy strips with excellent comprehensive performance.

[0004] Chinese invention patent (CN121911839A) discloses a method for preparing Ti2AlNb thin strips with controllable phase composition based on thin strip casting and rolling. Although the invention prepares Ti2AlNb thin strips with controllable phase composition by spraying helium and argon gas on the roll surface and the surface of the cast strip, the cost of helium is too high.

[0005] Chinese invention patent (CN112410698A) discloses a method for controlling the uniformity of multi-layered microstructure in a three-phase Ti2AlNb alloy. The method involves extruding a Ti2AlNb alloy ingot to obtain a billet with a fully broken B2 phase; subjecting the billet to B2 phase recrystallization heat treatment to obtain a billet with a uniformly refined metastable B2 phase microstructure; then holding the billet at 950℃~1000℃, followed by rapid cooling to obtain a billet with an α2 phase uniformly dispersed in the B2 phase matrix; holding the billet with the α2 phase uniformly dispersed in the B2 phase matrix at 550℃~650℃, followed by heating to 700℃~850℃, and finally cooling to obtain an alloy material with an O phase and α2 phase uniformly dispersed in the B2 phase matrix. Although the microstructure can be controlled, the preparation steps are complex, time-consuming, and cannot form a layered structure.

[0006] Chinese invention patent (CN112281043A) discloses a Ti2AlNb-based alloy with high fracture toughness, its preparation method and application. The method prepares parts made of Ti2AlNb-based alloy with high fracture toughness through multiple vacuum melting + forging + solution heat treatment + aging heat treatment. Although it has good fracture toughness, it requires a long heat treatment time, with a total solution aging time of more than 18 hours.

[0007] Chinese invention patent (CN106637013A) discloses a heat treatment method to improve the high-temperature strength of Ti2AlNb-based alloys. The method involves pretreatment, solution treatment, quenching, and aging treatment. The heat treatment process is still complex, and solution treatment and aging are time-consuming.

[0008] The above-mentioned methods for preparing Ti2AlNb alloys and controlling their microstructure (heat treatment methods) often involve high investment costs or complex and time-consuming preparation processes. Summary of the Invention

[0009] To address the current problems of long development cycles, high costs, and the need for prolonged heat treatment to control the microstructure of high-performance Ti2AlNb alloy strips, the present invention aims to provide a Ti2AlNb alloy strip with a high Nb content and O-rich phase interlayer and its preparation method. The strip prepared by strip casting and rolling only requires ultra-short heating to achieve high strength without loss of performance. The ultra-short high temperature treatment can precipitate nano-O phase, achieving an excellent match between strip strength and plasticity in a short process and at low cost.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows:

[0011] A Ti2AlNb alloy strip with a high Nb content and an O phase interlayer includes a B2 phase matrix and precipitated O phase. The Ti2AlNb alloy strip has a sandwich-like structure, consisting of a high Nb interlayer in the middle and upper and lower surface layers. The Nb content of the high Nb interlayer is 3-5 at% higher than that of the surface layer. The O phase is dispersed in the B2 phase grains at the nanoscale, and the distribution density of the O phase in the high Nb interlayer is higher than that in the upper and lower surface layers.

[0012] The Ti2AlNb alloy strip with a high Nb content and an O-rich phase interlayer has the following composition by atomic percentage: Al 18~25%, Nb 17~27%, Mo 0~1%, and the balance being Ti.

[0013] The aforementioned Ti2AlNb alloy strip with a high Nb content and O-rich phase interlayer has a thickness of 1~4mm; the grain size of the high Nb interlayer is 20~100μm, and the grain size of the upper and lower surface layers is 100~300μm.

[0014] The aforementioned Ti2AlNb alloy strip with a high Nb content and O-rich interlayer has an average niobium content of 30 at in the high Nb interlayer and an average niobium content of 25 at in the upper and lower surface layers.

[0015] The Ti2AlNb alloy strip with a high Nb content and O-rich phase interlayer has a tensile strength of 1000~1300MPa and an elongation of 5~17%.

[0016] The Ti2AlNb alloy strip with a high Nb content and rich O phase interlayer has, by volume percentage, a B2 phase matrix of 4-15% and an O phase of 85-96% in the high Nb interlayer region.

[0017] A method for preparing a Ti2AlNb alloy thin strip with a high Nb content and O-rich phase interlayer, comprising the following steps:

[0018] (1) Ti2AlNb alloy strips were prepared by strip casting and rolling. The cast strips were single B2 phases with a sandwich structure. The grain size of the middle layer was 20~100μm and the grain size of the outer layer was 100~300μm.

[0019] (2) The Ti2AlNb alloy strip was subjected to ultra-short-time high-temperature treatment at a temperature of 750~950℃ and a holding time of 3~15min.

[0020] (3) After cooling, a Ti2AlNb alloy ribbon with uniformly dispersed nano-O phase is obtained. The nano-O phase is distributed in the B2 phase grains. The high Nb interlayer has more nano-O phase, and the ribbon has higher strength and plasticity.

[0021] In the preparation method of the Ti2AlNb alloy thin strip with high Nb content and rich O phase interlayer, in step (2), the thin strip is placed in a high temperature furnace at 750~950℃, kept at the temperature for 3~15min, and then taken out and air-cooled to room temperature.

[0022] In the preparation method of the Ti2AlNb alloy thin strip with high Nb content and rich O phase interlayer, in step (3), after short-time high temperature treatment, the original B2 phase grains of the thin strip do not grow significantly and basically retain the grain size gradient of the cast and rolled state; the nano O phase precipitates inside the original B2 phase grains and is mainly concentrated in the high Nb interlayer region.

[0023] The design concept of this invention is:

[0024] This invention fully utilizes the uneven cooling rate along the thickness direction of the strip during twin-roll thin strip casting and rolling, allowing Nb to naturally segregate during solidification, forming a compositional gradient with a high Nb content in the middle layer and low Nb content in the upper and lower surface layers. Simultaneously, a sandwich grain size gradient is achieved, with fine grains in the middle layer and coarse grains in the surface layer, resulting in a single-phase B2 microstructure in the cast-rolled strip. Based on this, an ultra-short-time high-temperature treatment of 750–950℃ for 3–15 minutes is employed. Taking advantage of Nb's ability to promote O phase precipitation, nano-O phase preferentially disperses and precipitates in the high-Nb middle interlayer region. This short-time treatment does not alter the original B2 phase grain size gradient, ultimately forming a synergistic structure where a fine-grained, high-Nb, O-rich interlayer provides excellent plasticity and toughness, while a coarse-grained, low-Nb surface layer provides high strength. Simultaneously, the ultra-short-time treatment eliminates internal stress introduced during casting and rolling, further enhancing the strip's plasticity. This achieves an excellent balance of strength and plasticity in Ti2AlNb alloy strips with extremely low process costs and a very short processing cycle.

[0025] Compared with the existing technology, the present invention has the following beneficial technical effects:

[0026] 1. The Ti2AlNb alloy strip of this invention has a "sandwich" structure formed by a high-Nb interlayer and upper and lower surface layers. The high-Nb interlayer has finer grains and is rich in nano-O phase, which improves the toughness, plasticity, and strength of the strip. The upper and lower surface layers have coarser grains and less nano-O phase, which improves the hardness and strength of the strip. Thus, through the synergistic effect of zoned properties, the strength and plasticity of the strip are improved simultaneously.

[0027] 2. The heat treatment time of this invention is only 3 to 15 minutes. The ultra-short time high temperature treatment can remove the internal stress of the thin strip during the thin strip casting and rolling process and improve the plasticity of the thin strip.

[0028] 3. This invention employs an ultra-short-time high-temperature treatment, which is simple and rapid, and can change the microstructure of the strip without complex multi-step heat treatment, forming a unique high-Nb-content, O-rich sandwich structure, further improving the overall performance of the strip. The ultra-short-time high-temperature treatment only induces the precipitation of nano-O phase within the B2 crystals, without changing the original grain size and compositional gradient structure of the cast-rolled state. It can stably retain the synergistic performance advantages of the sandwich structure, while effectively eliminating casting-rolled internal stress and improving the processability of the strip.

[0029] 4. This invention does not require expensive cooling and control methods such as helium injection. It only utilizes the natural element segregation of thin strip casting and rolling combined with ultra-short time heat treatment to form a unique high Nb content O-rich phase sandwich structure, which greatly reduces production costs and improves production efficiency. Attached Figure Description

[0030] Figure 1 Flowchart for the preparation of Ti2AlNb alloy thin strips with high Nb content and rich O phase interlayer.

[0031] Figure 2 This is a microstructure image of Example 3 after ultra-short-time high-temperature treatment at 950℃ for 10 minutes. Detailed Implementation

[0032] like Figure 1 As shown, this invention proposes a Ti2AlNb alloy thin strip with a high Nb content and a rich O phase interlayer and its preparation method, which is carried out according to the following steps: (1) Ti2AlNb alloy thin strip is prepared by thin strip casting and rolling. The thin strip is a single B2 phase with a sandwich structure. The middle grain size is about 20~100μm and the outer grain size is 100~300μm; (2) Ti2AlNb alloy thin strip is subjected to ultra-short time high temperature treatment. The treatment temperature is 750~950℃ and the holding time is 3~15min; (3) Ti2AlNb alloy thin strip with uniformly dispersed nano O phase is obtained. The nano O phase is distributed in the B2 phase grains. The high Nb interlayer has more nano O phase. The thin strip has the dual advantages of high strength and plasticity.

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0034] Example 1

[0035] In this embodiment, a method for preparing a Ti2AlNb alloy thin strip with a high Nb content and O-rich phase interlayer specifically includes the following steps:

[0036] 1. Using metallic Ti (99.9wt%), Al (99.9wt%), Nb (99.9wt%) and AlMo 60wt% master alloy as raw materials, weigh the raw materials according to the nominal composition, with atomic percentages of Ti: 52.5%, Al: 22%, Nb: 25%, Mo: 0.5%, and a total mass of 10kg.

[0037] 2. Place the raw materials into the water-cooled copper crucible in order of their melting points, close the vacuum chamber, and evacuate to a pressure of 10. -2 Pa.

[0038] 3. Purge the vacuum chamber with high-purity argon gas (99.999% volume purity) to 45000 Pa. Use induction melting technology to melt the raw materials into a homogeneous melt. Hold at this temperature for 5 minutes, then turn off the power and allow the furnace to cool to room temperature.

[0039] 4. Open the vacuum chamber, turn the ingot inside the water-cooled copper crucible over and put it back into the crucible, then remelt the ingot to ensure uniform composition. During the second melting, hold the ingot at that temperature for 5 minutes after it has completely melted.

[0040] 5. Adjust the gap between the horizontal casting rolls to 1.5 mm and the roll speed to 20 m / min. The molten metal flows from the tundish nozzle to the middle of the two horizontal water-cooled rolls. Under the rapid cooling effect of the casting rolls, it quickly forms a strip with a thickness of about 1.5 mm.

[0041] 6. The Ti2AlNb alloy strip is composed of a single B2 phase and exhibits a sandwich structure. The high Nb interlayer grain size is about 20~60μm, and the outer layer grain size is 150~250μm.

[0042] 7. Place the thin strip into a muffle furnace at 750 ℃, keep it at that temperature for 10 minutes, then remove it and air cool it to room temperature.

[0043] 8. The nano-O phase is mainly concentrated in the high-Nb interlayer within the original B2 phase grains. By volume percentage, the B2 phase matrix accounts for 15% and the O phase accounts for 85% in the high-Nb interlayer region. The average niobium content of the high-niobium interlayer is approximately 30 at, and the average niobium content of the upper and lower surface layers is approximately 25 at. The mechanical properties of the Ti2AlNb alloy strip are: tensile strength R... m It has a strength of approximately 1230 MPa and an elongation of approximately 8% at.

[0044] Example 2

[0045] In this embodiment, a method for preparing a Ti2AlNb alloy thin strip with a high Nb content and O-rich phase interlayer specifically includes the following steps:

[0046] 1. Using metallic Ti (99.9wt%), Al (99.9wt%), Nb (99.9wt%) and AlMo 60wt% master alloy as raw materials, weigh the raw materials according to the nominal composition, with atomic percentages of Ti: 52.5%, Al: 22%, Nb: 25%, Mo: 0.5%, and a total mass of 10kg.

[0047] 2. Place the raw materials into the water-cooled copper crucible in order of their melting points, close the vacuum chamber, and evacuate to a pressure of 10. -2 Pa.

[0048] 3. Purge the vacuum chamber with high-purity argon gas (99.999% volume purity) to 45000 Pa. Use induction melting technology to melt the raw materials into a homogeneous melt. Hold at this temperature for 5 minutes, then turn off the power and allow the furnace to cool to room temperature.

[0049] 4. Open the vacuum chamber, turn the ingot inside the water-cooled copper crucible over and put it back into the crucible, then remelt the ingot to ensure uniform composition. During the second melting, hold the ingot at that temperature for 5 minutes after it has completely melted.

[0050] 5. Adjust the gap between the horizontal casting rolls to 1.5 mm and the roll speed to 20 m / min. The molten metal flows from the tundish nozzle to the middle of the two horizontal water-cooled rolls. Under the rapid cooling effect of the casting rolls, it quickly forms a strip with a thickness of about 1.5 mm.

[0051] 6. The Ti2AlNb alloy strip is composed of a single B2 phase and exhibits a sandwich structure. The high Nb interlayer grain size is about 20~60μm, and the outer layer grain size is 150~250μm.

[0052] 7. Place the thin strip into a muffle furnace at 850 ℃, keep it at that temperature for 10 minutes, then remove it and air cool it to room temperature.

[0053] 8. The nano-O phase is mainly concentrated in the high-Nb interlayer within the original B2 phase grains. By volume percentage, the B2 phase matrix accounts for 9% and the O phase accounts for 91% in the high-Nb interlayer region. The average niobium content of the high-niobium interlayer is approximately 30 at, and the average niobium content of the upper and lower surface layers is approximately 25 at. The mechanical properties of the Ti2AlNb alloy strip are: tensile strength R... m It has a strength of approximately 1200 MPa and an elongation of approximately 10%.

[0054] Example 3

[0055] In this embodiment, a method for preparing a Ti2AlNb alloy thin strip with a high Nb content and O-rich phase interlayer specifically includes the following steps:

[0056] 1. Using metallic Ti (99.9wt%), Al (99.9wt%), Nb (99.9wt%) and AlMo 60wt% master alloy as raw materials, weigh the raw materials according to the nominal composition, with atomic percentages of Ti: 52.5%, Al: 22%, Nb: 25%, Mo: 0.5%, and a total mass of 10kg.

[0057] 2. Place the raw materials into the water-cooled copper crucible in order of their melting points, close the vacuum chamber, and evacuate to a pressure of 10. -2 Pa.

[0058] 3. Purge the vacuum chamber with high-purity argon gas (99.999% volume purity) to 45000 Pa. Use induction melting technology to melt the raw materials into a homogeneous melt. Hold at this temperature for 5 minutes, then turn off the power and allow the furnace to cool to room temperature.

[0059] 4. Open the vacuum chamber, turn the ingot inside the water-cooled copper crucible over and put it back into the crucible, then remelt the ingot to ensure uniform composition. During the second melting, hold the ingot at that temperature for 5 minutes after it has completely melted.

[0060] 5. Adjust the gap between the horizontal casting rolls to 1.5 mm and the roll speed to 20 m / min. The molten metal flows from the tundish nozzle to the middle of the two horizontal water-cooled rolls. Under the rapid cooling effect of the casting rolls, it quickly forms a strip with a thickness of about 1.5 mm.

[0061] 6. The Ti2AlNb alloy strip is composed of a single B2 phase and exhibits a sandwich structure. The high Nb interlayer grain size is about 20~60μm, and the outer layer grain size is 150~250μm.

[0062] 7. Place the thin strip into a muffle furnace at 950 ℃, keep it at that temperature for 10 minutes, then remove it and air cool it to room temperature.

[0063] 8. The nano-O phase is mainly concentrated in the high-Nb interlayer within the original B2 phase grains. By volume percentage, the B2 phase matrix accounts for 4% and the O phase accounts for 96% in the high-Nb interlayer region. The average niobium content of the high-niobium interlayer is approximately 30 at, and the average niobium content of the upper and lower surface layers is approximately 25 at. The mechanical properties of the Ti2AlNb alloy strip are: tensile strength R... m It has a strength of approximately 1250 MPa and an elongation of approximately 11% at.

[0064] like Figure 2As shown, the thin strip exhibits a distinct "sandwich" distribution pattern along its thickness: the bright areas near the surface at the top and bottom are the low-Nb surface layer; the black area in the middle is the high-Nb intermediate layer. Since Nb promotes the precipitation of the O phase, the Nb content gradient formed by casting and rolling can be converted into an O phase distribution gradient. The precipitated O phase is at the nanometer / submicron scale, and after ultra-short-time high-temperature treatment, no significant grain growth was observed in the thin strip as a whole.

[0065] Comparative Example 1

[0066] In this embodiment, a method for preparing a Ti2AlNb alloy thin strip with a high Nb content and O-rich phase interlayer specifically includes the following steps:

[0067] 1. Using metallic Ti (99.9wt%), Al (99.9wt%), Nb (99.9wt%) and AlMo 60wt% master alloy as raw materials, weigh the raw materials according to the nominal composition, with atomic percentages of Ti: 52.5%, Al: 22%, Nb: 25%, Mo: 0.5%, and a total mass of 10kg.

[0068] 2. Place the raw materials into the water-cooled copper crucible in order of their melting points, close the vacuum chamber, and evacuate to a pressure of 10. -2 Pa.

[0069] 3. Purge the vacuum chamber with high-purity argon gas (99.999% volume purity) to 45000 Pa. Use induction melting technology to melt the raw materials into a homogeneous melt. Hold at this temperature for 5 minutes, then turn off the power and allow the furnace to cool to room temperature.

[0070] 4. Open the vacuum chamber, turn the ingot inside the water-cooled copper crucible over and put it back into the crucible, then remelt the ingot to ensure uniform composition. During the second melting, hold the ingot at that temperature for 5 minutes after it has completely melted.

[0071] 5. Adjust the gap between the horizontal casting rolls to 1.5 mm and the roll speed to 20 m / min. The molten metal flows from the tundish nozzle to the middle of the two horizontal water-cooled rolls. Under the rapid cooling effect of the casting rolls, it quickly forms a strip with a thickness of about 1.5 mm.

[0072] 6. The Ti2AlNb alloy thin strip is composed of a single B2 phase and exhibits a sandwich structure. The high Nb interlayer grain size is about 30~100μm, and the outer layer grain size is 100~300μm.

[0073] 7. Place the thin strip into a muffle furnace at 950 ℃, hold for 25 s, then remove and air cool to room temperature.

[0074] 8. The nano-O phase within the original B2 phase grains is mainly concentrated in the upper and lower surface layers. The average niobium content in the high-niobium interlayer is approximately 30 at, while the average niobium content in the upper and lower surface layers is approximately 25 at. Due to the short holding time, the overall O phase precipitation is extremely low, failing to form a clear gradient distribution. Insufficient precipitation leads to low strength. The mechanical properties of the Ti2AlNb alloy strip are: tensile strength R... m It has a strength of approximately 960 MPa and an elongation of approximately 9%.

[0075] The results showed that the distribution pattern of nano-O phase was consistent in Examples 1 (750℃ for 10 min), 2 (850℃ for 10 min), and 3 (950℃ for 10 min), although the relative content varied with increasing temperature. The nano-O phase was diffusely precipitated within the original B2 phase grains, exhibiting a clear gradient distribution: the high-Nb interlayer region had a greater number and higher density of nano-O phase; the upper and lower surface regions had fewer and sparser nano-O phases. As the treatment temperature increased from 750℃ to 950℃, the overall precipitation of nano-O phase gradually increased. Example 3 (950℃) had the highest total precipitation of nano-O phase, followed by Example 2 (850℃), while Example 1 (750℃) had the lowest relative precipitation. Comparative Example 1 (held at 950℃ for 25s) showed insufficient O phase precipitation due to the short holding time, resulting in a significantly lower overall precipitation of nano-O phase compared to the examples, leading to inadequate strengthening effect. The nano-O phase was mainly concentrated in the upper and lower surface layers, failing to form a gradient distribution pattern characteristic of the high-Nb interlayer rich in O phase, which is contrary to the distribution characteristics of the examples. Therefore, this invention utilizes thin strip casting and rolling combined with ultra-short-time high-temperature treatment to prepare a Ti2AlNb alloy thin strip with a high-Nb content interlayer structure containing nano-O phase, providing a new technical route for the preparation of high-performance Ti2AlNb alloy thin strips.

Claims

1. A Ti2AlNb alloy thin strip with a high Nb content and O-rich phase interlayer, characterized in that, The Ti2AlNb alloy ribbon, consisting of a B2 phase matrix and precipitated O phase, has a sandwich-like layered structure, composed of a high-Nb interlayer in the middle and two surface layers. The Nb content of the high-Nb interlayer is 3-5 at higher than that of the surface layer. The O phase is dispersed in the B2 phase grains at the nanoscale, and the distribution density of the O phase in the high-Nb interlayer is higher than that in the two surface layers.

2. The Ti2AlNb alloy strip with a high Nb content and O-rich phase interlayer according to claim 1, characterized in that, The composition of Ti2AlNb alloy strips by atomic percentage is: Al 18~25%, Nb 17~27%, Mo 0~1%, with the balance being Ti.

3. The Ti2AlNb alloy strip with a high Nb content and O-rich phase interlayer according to claim 1, characterized in that, The thickness of the thin strip is 1~4mm; the grain size of the high Nb interlayer is 20~100μm, and the grain size of the upper and lower surface layers is 100~300μm.

4. A Ti2AlNb alloy strip with a high Nb content and O-rich phase interlayer according to claim 1, characterized in that, The niobium content of the high-Nb interlayer averages 30 at, while the niobium content of the upper and lower surface layers averages 25 at.

5. A Ti2AlNb alloy thin strip with a high Nb content and O-rich phase interlayer according to claim 1, characterized in that, The tensile strength of the thin strip is 1000~1300MPa, and the elongation is 5~17%.

6. A Ti2AlNb alloy thin strip with a high Nb content and O-rich phase interlayer according to claim 1, characterized in that, By volume percentage, the B2 phase matrix accounts for 4-15% and the O phase accounts for 85-96% in the high Nb interlayer region.

7. A method for preparing a Ti2AlNb alloy thin strip with a high Nb content and O-rich phase interlayer as described in any one of claims 1 to 6, characterized in that, Follow these steps: (1) Ti2AlNb alloy strips were prepared by strip casting and rolling. The cast strips were single B2 phases with a sandwich structure. The grain size of the middle layer was 20~100μm and the grain size of the outer layer was 100~300μm. (2) The Ti2AlNb alloy strip was subjected to ultra-short-time high-temperature treatment at a temperature of 750~950℃ and a holding time of 3~15min; (3) After cooling, a Ti2AlNb alloy ribbon with uniformly dispersed nano-O phase is obtained. The nano-O phase is distributed in the B2 phase grains. The high Nb interlayer has more nano-O phase, and the ribbon has higher strength and plasticity.

8. The method for preparing Ti2AlNb alloy thin strips with high Nb content and rich O phase interlayers according to claim 7, characterized in that, In step (2), the thin strip is placed in a high-temperature furnace at 750~950℃, kept at that temperature for 3~15 minutes, and then taken out and air-cooled to room temperature.

9. The method for preparing Ti2AlNb alloy thin strips with high Nb content and rich O phase interlayers according to claim 7, characterized in that, In step (3), after short-term high-temperature treatment, the original B2 phase grains of the thin strip do not grow significantly and basically retain the grain size gradient of the cast and rolled state; the nano O phase precipitates inside the original B2 phase grains and is mainly concentrated in the high Nb interlayer region.

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