High-strength powder metallurgy Ti175 alloy, preparation method and application thereof

Abstract

The application discloses a kind of high-strength powder metallurgy Ti175 alloy and its preparation method and application, belong to titanium and titanium alloy technical field.The method disclosed in the application first defines the component of Ti175 alloy, secondly limits hot rolling temperature to 800 DEG C~1300 DEG C, then the combination of single pass deformation 4%~15% and multi-pass cumulative total deformation 20%~200%, realizes the gradual breaking of biphase or widmanstatten initial organization, and grain is refined through dynamic recovery and recrystallization mechanism, the method is through the synergistic cooperation of powder metallurgy and hot deformation processing, solve the technical problem that existing method is difficult to control the room high-temperature performance of powder metallurgy Ti175 titanium alloy through hot deformation process.

Description

Technical Field

[0001] This invention belongs to the field of titanium and titanium alloy technology, specifically relating to a high-strength powder metallurgy Ti175 alloy, its preparation method, and its application. Background Technology

[0002] Currently, high-temperature titanium alloys have formed corresponding high-temperature titanium alloy systems at 350~600 ℃ and above. At 350~500 ℃, α+β type dual-phase titanium alloys have both room temperature hot workability and high temperature strength, and are widely used in low-pressure compressor blades of aero engines. Typical materials include TC4, TC17, TA19 and TC11. Near-α type Ti-Al-Zr-Mo-Si titanium alloys have stronger solid solution strengthening and precipitation strengthening capabilities, and can be used at temperatures up to 600 ℃. Through precipitation strengthening of silicides and α2 phase, they have high high-temperature creep resistance and thermal stability, making them ideal materials for high-pressure compressor disks and blades. Typical materials include Ti65 and Ti60. Furthermore, while the iterative design of high-temperature titanium alloys from the simple TC4 system to the ten-component Ti65 system has yielded core titanium alloy materials, it still faces the following challenges: 1) The mainstream Ti-Al-Zr-Sn-Mo-Si multi-component high-temperature titanium alloys still face difficulties in controlling microstructure stability and the narrow working / heat treatment window. For titanium alloys with thermal stability, high-temperature strength, fracture toughness, and creep resistance, the introduction of refractory elements Ta, W, and Mo can ensure the aforementioned performance indicators (in the form of intermediate alloys: Al-W, Al-Mo, Ti-Sn, etc.). For near-α type titanium alloys, the low β-stabilizing element content results in a narrow working temperature range in the (α+β) two-phase region, making precise control of the microstructure impossible. Hot working in the β single-phase region presents the problem of coarse initial β grain size. Furthermore, high-temperature titanium alloys, such as Ti60, Ti600, and Ti65, inevitably introduce precious metal elements like Mo, Ta, and Nb, as well as rare earth elements like Y and Nd. For complex and precision structural components of engines with general strength requirements, such as bladed disks, blades, and casings, their economic benefits are difficult to realize. 2) The high-temperature titanium alloys currently used in service at 550~600 ℃ are mainly designed for casting / forging technology. However, with the iteration of international aero-engine design technology, aero-engine disks and blades have shifted from separate structures to integral bladed disk structures. This means that blades and disks need to adopt the same hot working and heat treatment processes to ensure structural-microstructure consistency. Although researchers have proposed mature technical solutions for this integral bladed disk structure of aero-engines, the structural requirements for the manufacturing and post-processing of integral bladed disks mean that under the traditional forging technology route, long production cycles, low material utilization, and high processing costs are inevitable problems.

[0003] Ti175 alloy is a novel (α+β) dual-phase titanium alloy designed to further improve the strength and toughness of the Russian high-temperature titanium alloy TC25G (Ti-6.5Al-1.8Sn-4Zr-4Mo-1W-0.2Si). Its nominal composition is Ti-6.5Al-2.1Sn-3.5Zr-3.5Mo-1.3W-0.175Si, with a long-term service temperature of 550℃. It exhibits excellent fatigue resistance, crack propagation resistance, and machinability and weldability, and is primarily used in hot-end components such as engine compressor discs. At 500℃, its performance is significantly superior to in-service alloys such as TA15, TC11, and TC4, and it can replace some GH4169 components used in gas turbine blades.

[0004] The compositional design of Ti175 alloy provides it with a balance of mid-temperature high strength and thermal stability, as well as good room-temperature plasticity and fracture toughness, achieving a good match between strength, plasticity, and thermal stability. Furthermore, as a (α+β) type high-strength two-phase titanium alloy with excellent comprehensive performance for use at 500~600℃, Ti175 alloy exhibits good plasticity and can be processed into products such as bars, forgings, and rings. Currently, it is mainly used in the aerospace field to manufacture key load-bearing components such as disc forgings, blades, and casings. In summary, Ti175 alloy, as a (α+β) heat-strength high-temperature titanium alloy used in the 550~600 ℃ range, exhibits excellent high-temperature heat strength, stability, and excellent plasticity in its forgings and corresponding service parts. This allows Ti175 alloy to fill the gap in high-temperature titanium alloy systems that combine wide temperature range service from room temperature to 550 ℃, a wide hot working and heat treatment window (covering the two-phase to single-phase region), and economic benefits (without expensive V and Ta, Nb, rare earth elements Nd and Y, etc.).

[0005] Powder metallurgy offers advantages such as near-net-shape forming, uniform microstructure, and minimal compositional segregation, making it an effective method for preparing multi-component titanium alloys. Meanwhile, hot rolling is currently one of the most efficient methods for preparing titanium alloy sheets, not only altering the alloy's microstructure but also refining the grains and significantly improving its properties. To further enhance the room / high-temperature strength and ductility of powder metallurgy Ti175 titanium alloys and prepare high-performance Ti175 titanium alloy samples, further hot deformation treatment is necessary. Therefore, studying the influence of hot deformation processes on alloy properties is of great significance. However, current research on how to control the hot deformation process to achieve optimal room / high-temperature performance of powder metallurgy Ti175 titanium alloys is still insufficient. Summary of the Invention

[0006] The purpose of this invention is to provide a high-strength powder metallurgy Ti175 alloy, its preparation method, and its application, in order to solve the technical problem that existing methods are unable to control the high-temperature performance of powder metallurgy Ti175 titanium alloy through hot deformation processes.

[0007] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a method for preparing a high-strength powder metallurgy Ti175 alloy, comprising the following steps: S1: Provide Ti175 alloy spherical powder, which, by mass percentage, is composed of the following components: Al 6.20%~7.50%, Zr 3.00%~4.00%, Sn 1.50%~3.00%, Mo 3.50%~4.50%, Si 0.15%~0.35%, W 0.9%~2.0%, with the balance being Ti and unavoidable impurity elements; S2: Ti175 titanium alloy billet is prepared by powder metallurgy process from Ti175 alloy spherical powder. S3: Hold the Ti175 titanium alloy billet at 800 ℃~1300 ℃ for 5 min~120 min; S4: The Ti175 titanium alloy billet after heat preservation is hot rolled in multiple passes at 800 ℃~1300 ℃, with a single pass deformation of 4%~15% and a total deformation of 20%~200%. The billet is then heat-preserved in the furnace between each pass. S5: After hot rolling, the mixture is cooled to room temperature to obtain a high-strength powder metallurgy Ti175 alloy.

[0008] Furthermore, in S1, the particle size of the Ti175 alloy spherical powder is 10 μm to 250 μm; In S2, the powder metallurgy process is either spark plasma sintering or hot pressing sintering.

[0009] Furthermore, in S2, the discharge plasma sintering conditions are: pressure 20 MPa~40 MPa, sintering temperature 900 ℃~1300 ℃, and holding time 0.5 h~1.5 h; The hot pressing sintering conditions are: pressure 20 MPa~40 MPa, sintering temperature 900 ℃~1300 ℃, and holding time 0.5 h~1 h.

[0010] Furthermore, in step S2, after obtaining the Ti175 titanium alloy billet, the step of vacuum drying the Ti175 titanium alloy billet is also included. The vacuum drying conditions are: 40 ℃~90 ℃, and the drying time is 1 h~8 h.

[0011] Furthermore, in S3, the insulation temperature is 930 ℃ or 960 ℃; In S4, the number of passes in the multi-pass hot rolling is 2 to 6, and the deformation amount of each pass is 2.6 mm; the reheating time between each pass is 5 min to 20 min.

[0012] Furthermore, in S5, the cooling method is water cooling, oil cooling, air cooling, or air cooling.

[0013] The present invention also discloses a high-strength powder metallurgy Ti175 alloy, which is prepared by the above-described preparation method.

[0014] Furthermore, the high-strength powder metallurgy Ti175 titanium alloy has a room temperature tensile strength of not less than 1226 MPa, a room temperature yield strength of not less than 710 MPa, and a room temperature elongation of not less than 16.5%; at 550 ℃, its tensile strength is not less than 905 MPa, its yield strength at 550 ℃ is not less than 714 MPa, and its elongation at 550 ℃ is not less than 14.1%.

[0015] Furthermore, the high-strength powder metallurgy Ti175 titanium alloy has a tensile strength of not less than 741 MPa at 600 ℃, a yield strength of not less than 670 MPa at 600 ℃, and an elongation of not less than 16.1% at 600 ℃.

[0016] This invention also discloses the application of the above-mentioned high-strength powder metallurgy Ti175 alloy in the preparation of high-temperature structural components for aero-engines.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing a high-strength powder metallurgy Ti175 alloy. Firstly, the defined Ti175 alloy composition (Al equivalent ≈ 7.8, Mo equivalent ≈ 4.5) ensures suitable hardenability and thermal stability. Spherical powder is used for powder metallurgy billet preparation, avoiding compositional segregation and coarse microstructures caused by melting and casting. This provides a uniform microstructure and fine grain initial billet for subsequent hot rolling, ensuring the uniformity of the microstructure response during hot deformation. Secondly, the hot rolling temperature is limited to 800 ℃~1300 ℃, covering the α+β two-phase region and the β single-phase region. By selecting different rolling temperatures, the dissolution and precipitation behavior of the primary α phase, secondary α phase, and silicides can be controlled. The combination of single-pass deformation of 4%–15% and multi-pass cumulative deformation of 20%–200% achieves gradual fragmentation of the bimorphic or Widmanstätten initial microstructure, and refines the grains through dynamic recovery and recrystallization mechanisms. Small single-pass deformation avoids local rheological instability caused by excessive instantaneous deformation, while large cumulative deformation across multiple passes ensures sufficient refinement and homogenization of the overall microstructure. Reheating between passes ensures the recovery of the microstructure and temperature consistency before deformation. Through the synergistic effect of powder metallurgy and hot deformation treatment, the grain size, quantity and size of primary α-phase, secondary α-phase, and silicides in the alloy can be effectively controlled, clarifying the microstructure and performance control window of the powder metallurgy rolled profile. These technical characteristics enable simultaneous improvement of room temperature and high-temperature strength and plasticity. Therefore, this method transforms the traditionally difficult-to-control hot deformation performance control of powder metallurgy Ti175 into a deterministic process with a clear process window and predictable microstructure evolution path, significantly improving the controllability and stability of the high-temperature performance of powder metallurgy Ti175 alloys.

[0018] This invention also discloses the high-strength powder metallurgy Ti175 alloy prepared by the above method. According to relevant experimental results, the alloy exhibits the following minimum mechanical properties at room temperature, 550 ℃, and 600 ℃: tensile strength ≥1226 MPa and elongation ≥16.5% at room temperature; tensile strength ≥905 MPa and elongation ≥14.1% at 550 ℃; and tensile strength ≥741 MPa and elongation ≥16.1% at 600 ℃. These performance indicators serve as the benchmark for product qualification and directly demonstrate that the hot rolling method can effectively control the microstructure and performance. Furthermore, as the rolling temperature increases from 930 ℃ to 960 ℃ and the total deformation increases from 20% to 60%, the tensile strength continuously improves, while the elongation does not show a significant decrease. The trend of simultaneous improvement in strength and plasticity verifies that the three-level control strategy of the present invention, which determines the uniformity of powder metallurgy, the phase composition by rolling temperature, and the grain size by deformation amount, is indeed feasible for controlling the microstructure and properties of powder metallurgy Ti175 rolled profiles. Attached Figure Description

[0019] Figure 1 These are micrographs of the alloy plates obtained after hot rolling in Examples 1 to 6 of this invention. Among them: (a-a1) 930 ℃ -20%; (b-b1) 930 ℃ -40%; (c-c1) 930 ℃ -60%; (d-d1) 960 ℃ -20%; (e-e1) 960 ℃ -40%; (f-f1) 960 ℃ -60%; Figure 2 This paper compares the room temperature properties of the high-strength powder metallurgy Ti175 alloy prepared in this invention with those of existing titanium alloys. Figure 3 This paper compares the room temperature properties of the high-strength powder metallurgy Ti175 alloy prepared in this invention with those of existing high-temperature titanium alloys. Detailed Implementation

[0020] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0021] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0022] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0023] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0024] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0025] This invention proposes a hot rolling method for high-strength Ti175 titanium alloy. This method simultaneously improves the room-temperature and high-temperature strength and plasticity of Ti175 titanium alloy by changing the rolling temperature and deformation amount. It clarifies the influence mechanism of deformation temperature and deformation rate on microstructure-property evolution and provides theoretical guidance for the hot working of novel high-temperature titanium alloy parts made by powder metallurgy. Furthermore, the process described in this invention is simple, which helps to shorten the production cycle of traditional high-strength titanium alloy preparation and broadens the diversified applications and service of powder metallurgy Ti175 titanium alloy parts.

[0026] This invention discloses a method for preparing a high-strength powder metallurgy Ti175 alloy, comprising the following steps: Step 1: Dry the atomized spherical Ti175 powder in a vacuum drying oven; Step 2: The dried powder is sintered by spark plasma sintering or hot pressing to obtain Ti175 titanium alloy samples. In the technical solution adopted in this invention, the Ti175 powder is composed of the following raw material components by mass percentage: Al: 6.20%~7.50%, Zr: 3.00%~4.00%, Sn: 1.50%~3.00%, Mo: 3.50%~4.50%, Si: 0.15%~0.35%, W: 0.9%~2.0%, with the balance being Ti and impurity elements, and the sum of the mass percentages of the above components is 100%.

[0027] Step 3: Heat the muffle furnace to 800~1300 ℃. After reaching the target temperature, put the sample into the muffle furnace and keep it warm for 5~120 min to ensure that the sample is fully heated to red temperature. Step 4: The rolled sample is hot deformed at 800~1300 ℃ using a multi-pass rolling process, with a single pass deformation of 4~15% and a total deformation of 20~200%. Step 5: After hot deformation, the cooling method is water cooling, oil cooling, air cooling or air cooling, in order to clarify the influence of the cooling medium on the rolled structure and properties.

[0028] The vacuum drying conditions in step one are: 40~90 ℃, and drying time is 1~8 h; The conditions for spark plasma sintering in step two are: pressure 20~40MPa, sintering temperature 900~1300 ℃, and holding time 0.5~1 h; The hot pressing sintering conditions in step two are: pressure 20~40 MPa, sintering temperature 900~1300 ℃, and holding time 0.5~1 h.

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0030] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0031] Example 1 A method for preparing a high-strength powder metallurgy Ti175 alloy includes the following steps: Step 1: Place the raw Ti175 alloy spherical powder into a vacuum drying oven and vacuum dry it at 60 °C for 2 h; the Ti175 alloy spherical powder, by mass percentage, consists of the following components: Ti-6.5Al-2.1Sn-3.5Zr-3.5Mo-1.3W-0.175Si, with the balance being Ti and unavoidable impurity elements; the powder particle size is 10~250 μm; Step 2: The powder is pre-pressed into a graphite mold, and then subjected to spark plasma sintering at 900 ℃ and 30 MPa for 1.5 h. After furnace cooling, a Ti175 titanium alloy billet with a dual-state structure is obtained. Step 3: The initial height of the powder metallurgy Ti175 titanium alloy billet is 26 mm. The billet is held at 930 ℃ for 20 min in a muffle furnace and rolled in two passes with a rolling amount of 2.6 mm per pass. The billet is held in the furnace for 5 min between each pass. The second pass reaches the target thickness of 20.8 mm with a total deformation of 20%. After rolling, the billet is water quenched to obtain a high-strength powder metallurgy Ti175 alloy plate.

[0032] The Ti175 titanium alloy sheet obtained in this embodiment was subjected to room temperature and high temperature tensile property tests, and the results are as follows: Room temperature tensile properties: tensile strength 1226 MPa, yield strength 710 MPa, elongation 17.2%; 550 ℃ high temperature tensile properties: tensile strength 944 MPa, yield strength 752 MPa, elongation 25.1%; 600 ℃ high temperature tensile properties: tensile strength 773 MPa, yield strength 695 MPa, elongation 26.9%.

[0033] Example 2 A method for preparing a high-strength powder metallurgy Ti175 alloy includes the following steps: Step 1: Place the raw Ti175 alloy spherical powder into a vacuum drying oven and vacuum dry it at 60 °C for 2 h; the Ti175 alloy spherical powder, by mass percentage, consists of the following components: Ti-6.5Al-2.1Sn-3.5Zr-3.5Mo-1.3W-0.175Si, with the balance being Ti and unavoidable impurity elements; the powder particle size is 10~250 μm; Step 2: The powder is pre-pressed into a graphite mold, and then subjected to spark plasma sintering at 900 ℃ and 30 MPa for 1.5 h. After furnace cooling, a Ti175 titanium alloy billet with a dual-state structure is obtained. Step 3: The initial height of the powder metallurgy Ti175 titanium alloy billet is 26 mm. The billet is held at 930 ℃ for 20 min in a muffle furnace and rolled in 4 passes with a rolling amount of 2.6 mm per pass. The billet is held in the furnace for 5 min between each pass. The second pass reaches the target thickness of 15.6 mm with a total deformation of 40%. After rolling, the billet is water quenched to obtain a high-strength powder metallurgy Ti175 alloy plate.

[0034] The Ti175 titanium alloy sheet obtained in this embodiment was subjected to room temperature and high temperature tensile property tests, and the results are as follows: Room temperature tensile properties: tensile strength 1293 MPa, yield strength 967 MPa, elongation 16.8%; 550 ℃ high temperature tensile properties: tensile strength 912 MPa, yield strength 719 MPa, elongation 14.1%; 600 ℃ high temperature tensile properties: tensile strength 750 MPa, yield strength 670 MPa, elongation 36.6%.

[0035] Example 3 A method for preparing a high-strength powder metallurgy Ti175 alloy includes the following steps: Step 1: Place the raw Ti175 alloy spherical powder into a vacuum drying oven and vacuum dry it at 60 °C for 2 h; the Ti175 alloy spherical powder, by mass percentage, consists of the following components: Ti-6.5Al-2.1Sn-3.5Zr-3.5Mo-1.3W-0.175Si, with the balance being Ti and unavoidable impurity elements; the powder particle size is 10~250 μm; Step 2: The powder is pre-pressed into a graphite mold, and then subjected to spark plasma sintering at 900 ℃ and 30 MPa for 1.5 h. After furnace cooling, a Ti175 titanium alloy billet with a dual-state structure is obtained. Step 3: The initial height of the powder metallurgy Ti175 titanium alloy billet is 26 mm. The billet is held at 930 ℃ for 20 min in a muffle furnace and rolled in 6 passes with a rolling amount of 2.6 mm per pass. The billet is held in the furnace for 5 min between each pass. The target thickness of 10.4 mm is reached in the sixth pass, with a total deformation of 60%. After rolling, the billet is water quenched.

[0036] The Ti175 titanium alloy sheet obtained in this embodiment was subjected to room temperature and high temperature tensile property tests, and the results are as follows: Room temperature tensile properties: tensile strength 1325 MPa, yield strength 955 MPa, elongation 16.5%; 550 ℃ high temperature tensile properties: tensile strength 905 MPa, yield strength 714 MPa, elongation 23.7%; 600 ℃ high temperature tensile properties: tensile strength 741 MPa, yield strength 671 MPa, elongation 18.0%.

[0037] Example 4 A method for preparing a high-strength powder metallurgy Ti175 alloy includes the following steps: Step 1: Place the raw Ti175 alloy spherical powder into a vacuum drying oven and vacuum dry it at 60 °C for 2 h; the Ti175 alloy spherical powder, by mass percentage, consists of the following components: Ti-6.5Al-2.1Sn-3.5Zr-3.5Mo-1.3W-0.175Si, with the balance being Ti and unavoidable impurity elements; the powder particle size is 10~250μm; Step 2: The powder is pre-pressed into a graphite mold, and then subjected to spark plasma sintering at 900 ℃ and 30 MPa for 1.5 h. After furnace cooling, a Ti175 titanium alloy billet with a dual-state structure is obtained. Step 3: The initial height of the powder metallurgy Ti175 titanium alloy billet is 26 mm. The billet is held at 960 ℃ for 20 min in a muffle furnace and rolled in two passes with a rolling amount of 2.6 mm per pass. The billet is held in the furnace for 5 min between each pass. The second pass reaches the target thickness of 20.8 mm with a total deformation of 20%. After rolling, the billet is water quenched.

[0038] The Ti175 titanium alloy sheet obtained in this embodiment was subjected to room temperature and high temperature tensile property tests, and the results are as follows: Room temperature tensile properties: tensile strength 1293 MPa, yield strength 843 MPa, elongation 17.5%; 550 ℃ high temperature tensile properties: tensile strength 1013 MPa, yield strength 840 MPa, elongation 15.5%; 600 ℃ high temperature tensile properties: tensile strength 836 MPa, yield strength 723 MPa, elongation 23.9%.

[0039] Example 5 A method for preparing a high-strength powder metallurgy Ti175 alloy includes the following steps: Step 1: Place the raw Ti175 alloy spherical powder into a vacuum drying oven and vacuum dry it at 60 °C for 2 h; the Ti175 alloy spherical powder, by mass percentage, consists of the following components: Ti-6.5Al-2.1Sn-3.5Zr-3.5Mo-1.3W-0.175Si, with the balance being Ti and unavoidable impurity elements; the powder particle size is 10~250 μm; Step 2: The powder is pre-pressed into a graphite mold, and then subjected to spark plasma sintering at 900 ℃ and 30 MPa for 1.5 h. After furnace cooling, a Ti175 titanium alloy billet with a dual-state structure is obtained. Step 3: The initial height of the powder metallurgy Ti175 titanium alloy billet is 26 mm. The billet is held at 960 ℃ for 20 min in a muffle furnace and rolled in 4 passes with a rolling amount of 2.6 mm per pass. The billet is held in the furnace for 5 min between each pass. The fourth pass reaches the target thickness of 15.6 mm with a total deformation of 40%. After rolling, the billet is water quenched.

[0040] The Ti175 titanium alloy sheet obtained in this embodiment was subjected to room temperature and high temperature tensile property tests, and the results are as follows: Room temperature tensile properties: tensile strength 1303 MPa, yield strength 1048 MPa, elongation 16.4%; 550 ℃ high temperature tensile properties: tensile strength 962 MPa, yield strength 746 MPa, elongation 18.2%; 600 ℃ high temperature tensile properties: tensile strength 800 MPa, yield strength 678 MPa, elongation 16.1%.

[0041] Example 6 A method for preparing a high-strength powder metallurgy Ti175 alloy includes the following steps: Step 1: Place the raw Ti175 alloy spherical powder into a vacuum drying oven and vacuum dry it at 60 °C for 2 h; the Ti175 alloy spherical powder, by mass percentage, consists of the following components: Ti-6.5Al-2.1Sn-3.5Zr-3.5Mo-1.3W-0.175Si, with the balance being Ti and unavoidable impurity elements; the powder particle size is 10~250 μm; Step 2: The powder is pre-pressed into a graphite mold, and then subjected to spark plasma sintering at 900 ℃ and 30MPa pressure for 1.5 h. After furnace cooling, a Ti175 titanium alloy billet with a dual-state structure is obtained. Step 3: The initial height of the powder metallurgy Ti175 titanium alloy billet is 26 mm. The billet is held at 960 ℃ for 20 min in a muffle furnace and rolled in 6 passes with a rolling amount of 2.6 mm per pass. The billet is held in the furnace for 5 min between each pass. The target thickness of 10.4 mm is reached in the sixth pass, with a total deformation of 60%. After rolling, the billet is water quenched.

[0042] The Ti175 titanium alloy sheet obtained in this embodiment was subjected to room temperature and high temperature tensile property tests, and the results are as follows: Room temperature tensile properties: tensile strength 1360 MPa, yield strength 986 MPa, elongation 19.8%; 550 ℃ high temperature tensile properties: tensile strength 1003 MPa, yield strength 859 MPa, elongation 17.2%; 600 ℃ high temperature tensile properties: tensile strength 814 MPa, yield strength 715 MPa, elongation 23.8%.

[0043] Tables 1 to 3 show the properties of the Ti175 titanium alloy plates prepared in Examples 1 to 6. As can be seen from Tables 1 to 3, through the synergistic combination of powder metallurgy and hot deformation treatment, the present invention achieves a tensile strength of not less than 1226 MPa and an elongation of not less than 16.5% at room temperature, a tensile strength of not less than 905 MPa and a yield strength of not less than 714 MPa at 550 ℃, and a tensile strength of not less than 741 MPa and a yield strength of not less than 670 MPa at 600 ℃, thus achieving a simultaneous improvement in strength and plasticity at both room temperature and high temperature.

[0044] Table 1. Room temperature tensile properties of Examples 1-6

[0045] Table 2. High-temperature tensile properties (550 °C) of Examples 1 to 6

[0046] Table 3. High-temperature tensile properties (600 °C) of Examples 1 to 6

[0047] Figure 1These are micrographs of the alloy plates obtained after hot rolling in Examples 1 to 6 of this invention. Yellow indicates silicides, and red indicates secondary α phase. The images show that at the same rolling temperature, when the deformation is 20%, the area of ​​α lath twisting is small, and no obvious deformation is observed within the grains. No spheroidized α phase is also observed. When the deformation is 40%, the grains undergo significant deformation, and some α laths rotate: α laths parallel to the rolling direction elongate along the RD direction; α laths perpendicular to the rolling direction bend and twist. When the deformation increases to 60%, spheroidized α grains are clearly observed inside the sample. The microstructure of the rolled sample consists of nearly equiaxed α grains, α laths parallel to the rolling direction, and the β phase.

[0048] Compared to samples with deformation amounts of 20% and 40%, the sample with a deformation amount of 60% showed significantly refined grains and a markedly reduced α-lamellae length, attributed to α-lamellae breakage during rolling. Under high-magnification SEM, fine secondary α-phase distributions within the β-phase were observed in both the 40% and 60% deformation samples, indicating that larger deformation amounts favor the precipitation of small-scale α-phase from the β-phase. Furthermore, with increasing rolling passes, the reheating process during each pass promotes spheroidization; the α→β phase transformation during this process also transforms the α-lamellae into near-equiaxed α-phase, thus making the grain boundary α-phase increasingly difficult to observe with increasing deformation. At the same deformation amount, as the rolling temperature increased from 930℃ to 960℃, the α-phase content decreased, the volume fraction of spheroidized α-phase increased, and the β-phase content increased. On the one hand, as the rolling temperature increases, more α-phase transforms into β-phase; on the other hand, higher temperatures lead to faster migration rates of solute atoms, which facilitates the fracture and spheroidization of the lamellar α-phase through the α / β phase interface. Furthermore, SEM characterization revealed precipitated silicides, which are beneficial for improving the high-temperature mechanical properties of the material.

[0049] Figure 2To compare the room-temperature properties of the high-strength powder metallurgy Ti175 alloy prepared in this invention with those of existing titanium alloys, the tensile strengths of the samples prepared at 930 ℃-20%, 930 ℃-40%, 930 ℃-60%, 960 ℃-20%, 960 ℃-40%, and 960 ℃-60% were 1226 MPa, 1250 MPa, 1283 MPa, 1306 MPa, 1301 MPa, and 1320 MPa, respectively, with elongations of 17.2%, 16.8%, 16.5%, 17.5%, 16.4%, and 17.8%, respectively. The 960 ℃-60% sample exhibited the best performance in both tensile strength and elongation. Furthermore, with increasing deformation amount and deformation temperature, the tensile strength of the samples continuously increased, while the elongation showed a trend of first decreasing and then increasing. Compared with the sintered samples, the tensile strength of the samples prepared using the hot deformation method was significantly improved.

[0050] Compared to the PMTi175-900 (tensile strength: 1106 MPa) and PMTi175-1000 (tensile strength: 1230 MPa) samples, the tensile strength of the 960 ℃-60% sample (tensile strength: 1320 MPa) increased by 19.3% and 7.3%, respectively. Furthermore, the hot-deformed sample in this study outperformed the forged bladed disk (tensile strength: 1265 MPa, elongation 15.0%) (CN115194069 A). Even under conditions of relatively small deformation (20%), taking the 960 ℃-20% sample as an example, the ultimate tensile strength significantly increased to 1306 MPa, exceeding the sintered sample by 18%.

[0051] Figure 3 The room temperature properties of the high-strength powder metallurgy Ti175 alloy prepared in this invention are compared with those of existing high-temperature titanium alloys (550 ℃). As shown in the figure, the tensile strengths of the 960 ℃-20% and 960 ℃-60% samples, under the test condition of 550 ℃, exceed 1000 MPa, reaching 1013 MPa and 1003 MPa respectively, with an error not exceeding 5 MPa. Compared with the PMTi175-900 sample (695 MPa), the tensile strength is increased by 45.8% and 44.3% respectively. This demonstrates superior high-temperature performance compared to reported high-temperature titanium alloys.

[0052] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a high-strength powder metallurgy Ti175 alloy, characterized in that, Includes the following steps: S1: Provide Ti175 alloy spherical powder, which, by mass percentage, is composed of the following components: Al 6.20%~7.50%, Zr 3.00%~4.00%, Sn 1.50%~3.00%, Mo 3.50%~4.50%, Si 0.15%~0.35%, W 0.9%~2.0%, with the balance being Ti and unavoidable impurity elements; S2: Ti175 titanium alloy billet is prepared by powder metallurgy process from Ti175 alloy spherical powder. S3: Hold the Ti175 titanium alloy billet at 800 ℃~1300 ℃ for 5 min~120 min; S4: The Ti175 titanium alloy billet after heat preservation is hot rolled in multiple passes at 800 ℃~1300 ℃, with a single pass deformation of 4%~15% and a total deformation of 20%~200%. The billet is then heat-preserved in the furnace between each pass. S5: After hot rolling, the mixture is cooled to room temperature to obtain a high-strength powder metallurgy Ti175 alloy.

2. The method for preparing a high-strength powder metallurgy Ti175 alloy according to claim 1, characterized in that, In S1, the particle size of the Ti175 alloy spherical powder is 10 μm to 250 μm; In S2, the powder metallurgy process is either spark plasma sintering or hot pressing sintering.

3. The method for preparing a high-strength powder metallurgy Ti175 alloy according to claim 1, characterized in that, In S2, the discharge plasma sintering conditions are: pressure 20 MPa~40 MPa, sintering temperature 900 ℃~1300 ℃, and holding time 0.5 h~1.5 h; The hot pressing sintering conditions are: pressure 20 MPa~40 MPa, sintering temperature 900 ℃~1300 ℃, and holding time 0.5 h~1 h.

4. The method for preparing a high-strength powder metallurgy Ti175 alloy according to claim 1, characterized in that, In step S2, after obtaining the Ti175 titanium alloy billet, the step of vacuum drying the Ti175 titanium alloy billet is also included. The vacuum drying conditions are 40 ℃~90 ℃ and the drying time is 1 h~8 h.

5. The method for preparing a high-strength powder metallurgy Ti175 alloy according to claim 1, characterized in that, In S3, the insulation temperature is 930 ℃ or 960 ℃; In S4, the number of passes in the multi-pass hot rolling is 2 to 6, and the deformation amount of each pass is 2.6 mm; the reheating time between each pass is 5 min to 20 min.

6. The method for preparing a high-strength powder metallurgy Ti175 alloy according to claim 1, characterized in that, In S5, the cooling method is water cooling, oil cooling, air cooling, or air cooling.

7. A high-strength powder metallurgy Ti175 alloy, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 6.

8. The high-strength powder metallurgy Ti175 alloy according to claim 7, characterized in that, The high-strength powder metallurgy Ti175 titanium alloy has a room temperature tensile strength of not less than 1226 MPa, a room temperature yield strength of not less than 710 MPa, and a room temperature elongation of not less than 16.5%; at 550 ℃, its tensile strength is not less than 905 MPa, its yield strength at 550 ℃ is not less than 714 MPa, and its elongation at 550 ℃ is not less than 14.1%.

9. A high-strength powder metallurgy Ti175 alloy according to claim 7, characterized in that, The high-strength powder metallurgy Ti175 titanium alloy has a tensile strength of not less than 741 MPa at 600 ℃, a yield strength of not less than 670 MPa at 600 ℃, and an elongation of not less than 16.1% at 600 ℃.

10. The application of the high-strength powder metallurgy Ti175 alloy according to any one of claims 7 to 9 in the preparation of high-temperature structural components for aero-engines.

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