Preparation method of high-plasticity TiAl intermetallic compound

Abstract

The invention relates to a preparation method of a high-plasticity TiAl intermetallic compound, and belongs to the technical field of TiAl intermetallic compounds. In order to solve the problems that at present, it is difficult to further achieve TiAl strong plasticization through fine grain strengthening, and TiAl PST single crystals and components thereof are difficult to prepare, the high-density crossed nano twin crystal strong plasticized TiAl intermetallic compound is provided, and in the TiAl intermetallic compound, the atomic percent concentration of Al is 44%-47%, the atomic percent concentration of Nb is 7%-10%, the atomic percent concentration of C is 0%-0.5%, and the balance is Ti. According to the preparation method disclosed by the invention, a preparation process combining powder metallurgy and forging is adopted, so that a large number of cross faults are generated in gamma crystal grains of a TiAl intermetallic compound, and high-density cross nano twin crystals are formed in a deformation process, so that strong plasticizing is effectively realized. The method is mainly applied to manufacturing of key hot end parts of power systems such as aero-engine blades.

Description

[0001] This invention is a divisional application. The original application is titled "A Strong Plastic TiAl Intermetallic Compound and Its Preparation Method and Application". The application number is CN202411747141.X and the application date is December 2, 2024. Technical Field

[0002] The present invention belongs to the technical field of TiAl intermetallic compounds, and in particular relates to a high-plasticity TiAl intermetallic compound and a preparation method and application thereof. Background Art

[0003] TiAl intermetallic compounds have low density (~4.0 g / cm 3 ), high specific strength, high specific modulus, good high-temperature oxidation resistance and creep resistance, and other excellent comprehensive properties, making it considered the most promising advanced high-temperature structural material in the 700-1000°C range. Although TiAl intermetallic compounds have initially achieved engineering applications in industrial fields such as aircraft engines and automobiles, there is still a certain gap before widespread application. The main reasons for this situation are intrinsic brittleness at room temperature, the difficulty in further improving high-temperature strength, and poor formability. Among them, how to further effectively improve the strength and plasticity of TiAl intermetallic compounds is the most urgent fundamental problem to be solved.

[0004] Microstructure refinement is an effective way to achieve the strengthening and plasticization of TiAl intermetallic compounds. Alloying is one of the important methods to refine the microstructure of TiAl intermetallic compounds. Adding appropriate alloying elements can effectively refine the grain size. However, grain refinement is difficult to further achieve the strengthening and plasticization of TiAl intermetallic compounds. When the grain size or interlamellar spacing is reduced to submicron or even nanoscale, the structure of TiAl intermetallic compounds becomes unstable in the potential service temperature range (700-1000℃). Studies have found that when the grain size is reduced to nanoscale, the room temperature plasticity of TiAl intermetallic compounds is almost zero.

[0005] In 2016, Guang Chen et al. successfully prepared a Ti-45Al-8Nb intermetallic compound 0°PST single crystal using a seedless directional solidification technique with controlled growth rate. The resulting room-temperature tensile strength, yield strength, and elongation reached 978 MPa, 708 MPa, and 6.9%, respectively, representing the best overall room-temperature tensile properties for TiAl intermetallic compounds to date. Furthermore, the material's creep performance at 900°C was significantly improved compared to the commercially available Ti-48Al-2Cr-2Nb. The study revealed that the room-temperature tensile deformation mechanism of the Ti-45Al-8Nb intermetallic compound 0°PST single crystal is the formation of high-density deformation nanotwins, making it a typical nanotwin-strengthened TiAl intermetallic material. The specific preparation method of the PST single crystal is as follows: the TiAl parent material ingot is electromagnetically inducingly levitated and melted in a water-cooled copper crucible, and the parent material rod is obtained by suction casting; the parent material rod is directionally solidified in a four-mirror optical floating zone directional solidification furnace to control the orientation of the TiAl intermetallic compound layer and obtain the PST crystal; the PST crystal is then heat treated in the α single phase region and stress-relief annealed in a vacuum heat treatment furnace to eliminate B2 phase segregation and residual stress, ultimately forming a TiAl intermetallic compound material with high strength and high plasticity.

[0006] However, it is difficult to directly prepare PST single crystals with complex shapes using the optical floating zone melting directional solidification method, and the prepared PST single crystals are small in size; in addition, the preparation process of TiAl intermetallic compound PST single crystals is complicated, resulting in low yield and production efficiency and high cost; these conditions make the large-scale production and application of TiAl intermetallic compound PST single crystals technically difficult. Summary of the Invention

[0007] In view of the current problems that fine grain strengthening is difficult to further achieve strong plasticization of TiAl intermetallic compounds and TiAl intermetallic compound PST single crystals and components thereof are difficult to prepare, the present invention provides a strong plasticity TiAl intermetallic compound and its preparation method and application.

[0008] The technical solution of the present invention:

[0009] A strong plastic TiAl intermetallic compound, wherein the atomic percentage concentration of Al is 44-47 at.%, the atomic percentage concentration of Nb is 7-10 at.%, the atomic percentage concentration of C is 0-0.5 at.%, and the balance is Ti.

[0010] Furthermore, the microstructure of the TiAl intermetallic compound is a near-γ microstructure, mainly including a γ phase and an α2 phase, with the γ phase content being 75-95% and the α2 phase content being 5-25%.

[0011] Furthermore, the γ-phase grain size of the TiAl intermetallic compound is 7 to 20 μm, and the γ-phase grains contain a large number of cross-stacked faults; the TiAl intermetallic compound forms high-density cross-nano twins and at least two twins during plastic deformation at room temperature.

[0012] A preparation method for a high-density cross-nano twinned, highly plasticized TiAl intermetallic compound comprises the following steps: step 1, casing processing: pre-alloyed spherical powder of the TiAl intermetallic compound is loaded into a steel casing and vibrated to compact it. After the powder is loaded, the casing is vacuum-sealed and welded to obtain a casing filled with TiAl powder; step 2, hot isostatic pressing and sintering: the sealed and welded casing obtained in step 1 is subjected to hot isostatic pressing and sintering treatment, and the casing is removed after furnace cooling to obtain a TiAl billet; step 3, hot forging: the TiAl billet obtained in step 2 is subjected to two casing hot forging treatments, with the second hot forging direction being perpendicular to the first hot forging direction, to obtain a TiAl forging blank; step 4, heat treatment: the TiAl forging blank obtained in step 3 is heat treated, and after cooling, a high-density cross-nano twinned, highly plasticized TiAl intermetallic compound is obtained.

[0013] Furthermore, in step 1, the particle size distribution of the TiAl intermetallic compound pre-alloyed spherical powder is within the range of 60 to 220 μm, and the oxygen content of the TiAl intermetallic compound pre-alloyed spherical powder is controlled below 700 ppm.

[0014] Furthermore, the TiAl intermetallic compound pre-alloyed spherical powder in step 1 is prepared by a plasma rotating electrode atomization powder making method.

[0015] Furthermore, the specific preparation method of the plasma rotating electrode atomization powder making method is as follows: before the powder making starts, the vacuum degree of the processing chamber needs to be pumped to less than 10 -3 Pa, and then fill with a mixture of argon and helium until the pressure in the processing chamber reaches 2×10 1 Pa, oxygen content is less than 50ppm; the diameter of the TiAl consumable electrode prepared by conventional methods according to the target alloy element content is 51 to 75mm, it rotates at a speed of 30,000 to 33,000rpm, the electrode feed speed is 0.5 to 1.2mm / s, and the melting power of the plasma arc is 50 to 60kW.

[0016] Furthermore, in step 2, the temperature of hot isostatic pressing sintering is 1200-1300° C., the pressure is 140-170 MPa, and the heat and pressure holding time is 2-5 hours.

[0017] Furthermore, the temperature of the hot forging in step three is 1200-1300° C., the deformation amount of the first hot forging is 30-60%, and the deformation amount of the second hot forging is 50-80%.

[0018] Furthermore, the temperature of the heat treatment in step 4 is 1200-1300° C., and the holding time is 1-5 hours.

[0019] A high-density cross-nano-twinned plasticized TiAl intermetallic compound is used in hot-end components of power systems, including aerospace engines, gas turbines, and automobile engines.

[0020] The present invention utilizes a combined powder metallurgy and forging process to produce a large number of cross-stacked faults within the γ grains of the resulting high-niobium TiAl intermetallic compound. These cross-stacked faults serve as effective nucleation sites for twins, enabling the formation of high-density cross-nano-twins during deformation, effectively achieving strong plasticization. The high-density cross-nano-twinned, strongly plasticized TiAl intermetallic compound exhibits excellent room-temperature compressive properties, with a compressive strength of 2500-2600 MPa, a yield strength of 650-700 MPa, and a fracture strain of 35-40%.

[0021] The present invention solves the problem of complex preparation process of TiAl intermetallic compound PST single crystal, can realize near-net forming of complex components such as aircraft engine blades, has high yield and production efficiency, low cost, and is easy to realize large-scale production and application.

[0022] The high-density cross-nano-twinned plasticized TiAl intermetallic compound provided by the present invention is expected to be applied to aircraft engine blades, rocket engine nozzles, micro gas turbine turbines and blades, as well as hot end components such as automotive power system supercharger turbines and exhaust valves. It can effectively achieve lightweight equipment, improve the power output and combustion efficiency of various engines, and effectively promote energy conservation and emission reduction. It is a typical green and low-carbon technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Band Contrast (diffraction band contrast) diagram obtained by EBSD (electron backscatter diffraction) analysis of the strong plastic TiAl intermetallic compound prepared in Example 2;

[0024] Figure 2 This is the phase content map obtained by EBSD analysis of the strong plastic TiAl intermetallic compound prepared in Example 2. In the figure, red and purple are γ phase, and green is α2 phase;

[0025] Figure 3 This is a transmission electron microscope photograph of high-density cross-nano twins formed during room temperature deformation of the highly plastic TiAl intermetallic compound prepared in Example 2;

[0026] Figure 4 This is a room temperature compression engineering stress-strain curve of the super-plastic TiAl intermetallic compound prepared in Example 2;

[0027] Figure 5 This is a transmission electron microscope photograph of the cross-stacking faults in the γ grains of the highly ductile TiAl intermetallic compound prepared in Example 3. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described below with reference to the embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be included in the scope of protection of the present invention. The process equipment or devices not specifically noted in the following examples are all conventional equipment or devices in the art. Unless otherwise specified, the raw materials used in the examples of the present invention can be obtained commercially; unless otherwise specified, the technical means used in the examples of the present invention are all conventional means well known to those skilled in the art.

[0029] Example 1 This example provides a high-density cross-nano twinned strong plasticized TiAl intermetallic compound and a preparation method thereof.

[0030] In this embodiment, the atomic percentage concentration of Al in the TiAl intermetallic compound is 47 at.%, the atomic percentage concentration of Nb is 7 at.%, the atomic percentage concentration of C is 0 at.%, and the balance is Ti.

[0031] The preparation method of high-density cross-nano twinned strong plasticized TiAl intermetallic compound in this embodiment includes the following steps: Step 1, sheathing processing: a plasma rotating electrode atomization powder making method is used to prepare TiAl intermetallic compound pre-alloyed spherical powder. The specific preparation method is as follows:

[0032] Before milling begins, the vacuum degree of the processing chamber must be pumped to less than 10 -3 Pa, and then fill with a mixture of argon and helium until the pressure in the processing chamber reaches 2×10 1 Pa, and the oxygen content is less than 50 ppm; the diameter of a TiAl consumable electrode prepared by a conventional method according to the target alloying element content is 60 mm, and it rotates at a speed of 30,000 rpm, the electrode feed speed is 1.0 mm / s, and the melting power of the plasma arc is 50 kW. The particle size distribution of the obtained TiAl intermetallic compound pre-alloyed spherical powder is in the range of 60 to 220 μm, and the oxygen content is controlled below 700 ppm.

[0033] The TiAl intermetallic compound pre-alloyed spherical powder is loaded into a stainless steel sleeve and vibrated. After the powder is filled, the sleeve is vacuum-sealed to obtain a sleeve filled with TiAl powder; step 2, hot isostatic pressing sintering: the sealed sleeve obtained in step 1 is subjected to hot isostatic pressing sintering treatment, the hot isostatic pressing sintering temperature is 1200° C., the pressure is 170 MPa, and the holding time is 5 hours. After furnace cooling, the sleeve is removed to obtain a TiAl ingot; step 3, hot forging: the TiAl ingot obtained in step 2 is subjected to two sleeve upsetting hot forging treatments, the hot forging temperature is 1200° C., the deformation of the first hot forging is 30%, the deformation of the second hot forging is 50%, and the direction of the second hot forging is perpendicular to the direction of the first hot forging, to obtain a TiAl forging blank; step 4, heat treatment: the TiAl forging blank obtained in step 3 is heat treated, the heat treatment temperature is 1200° C., the holding time is 5 hours, and after air cooling, a high-density cross-nano twinned strong plasticized TiAl intermetallic compound is obtained.

[0034] The TiAl intermetallic compound prepared in this example exhibits a near-γ microstructure, primarily comprising γ and α2 phases, with the γ phase content being 95% and the α2 phase content being 5%. The γ phase grain size of the TiAl intermetallic compound ranges from 7 to 20 μm, and the γ phase grains contain a large number of cross-stacked faults. During plastic deformation at room temperature, the TiAl intermetallic compound produces high-density cross-nano-twins, with at least two twins formed.

[0035] Example 2 This example provides a high-density cross-nano twinned strong plasticized TiAl intermetallic compound and a preparation method thereof.

[0036] In this embodiment, the atomic percentage concentration of Al in the TiAl intermetallic compound is 45 at.%, the atomic percentage concentration of Nb is 8 at.%, the atomic percentage concentration of C is 0 at.%, and the balance is Ti.

[0037] The preparation method of high-density cross-nano-twinned plasticized TiAl intermetallic compound in this embodiment includes the following steps: Step 1, sheathing processing: The same plasma rotating electrode atomization powder making method as in Example 1 is used to prepare TiAl intermetallic compound pre-alloyed spherical powder, the particle size distribution of the spherical powder is in the range of 60 to 220 μm, and the oxygen content is controlled below 700 ppm.

[0038] The TiAl intermetallic compound pre-alloyed spherical powder is loaded into a stainless steel sleeve and vibrated. After the powder is filled, the sleeve is vacuum-sealed to obtain a sleeve filled with TiAl powder; step 2, hot isostatic pressing sintering: the sleeve obtained in step 1 after sealing and sintering is subjected to hot isostatic pressing sintering, the hot isostatic pressing sintering temperature is 1250° C., the pressure is 150 MPa, and the holding time is 5 hours. After furnace cooling, the sleeve is removed to obtain a TiAl ingot; step 3, hot forging: the TiAl ingot obtained in step 2 is subjected to two sleeve upsetting hot forging treatments, the hot forging temperature is 1250° C., the deformation of the first hot forging is 40%, and the deformation of the second hot forging is 70%, and the direction of the second hot forging is perpendicular to the direction of the first hot forging, to obtain a TiAl forging blank; step 4, heat treatment: the TiAl forging blank obtained in step 3 is heat treated, the heat treatment temperature is 1250° C., the holding time is 2 hours, and high-density cross-nano twinned strong plasticized TiAl intermetallic compound is obtained after air cooling.

[0039] Figure 1 and Figure 2 The Band Contrast (diffraction band contrast) diagram and phase content diagram obtained by EBSD (electron backscattered diffraction) analysis of the high-density cross-nano twinned strongly plasticized TiAl intermetallic compound prepared in this embodiment are respectively, Figure 2 Red and purple are γ phase, and green is α2 phase; Figure 2 As shown, the microstructure of the TiAl intermetallic compound in this embodiment is a near-γ structure, mainly including γ phase and α2 phase, with the γ phase content being 81% and the α2 phase content being 19%. The γ phase grain size of the TiAl intermetallic compound is 7-20 μm.

[0040] Figure 3 This is a transmission electron microscope photograph of high-density cross-nano twins formed during the deformation process of the high-density cross-nano twinned strongly plasticized TiAl intermetallic compound prepared in this embodiment; Figure 3 As shown, the TiAl intermetallic compound of this embodiment forms high-density cross-nano twins and at least two twins during the plastic deformation process at room temperature.

[0041] Figure 4 The room temperature compression engineering stress-strain curve of the high-density cross-nano twinned strong plasticized TiAl intermetallic compound prepared in this embodiment is shown in FIG. Figure 4 It can be seen that the room temperature compressive strength, yield strength and fracture strain of the TiAl intermetallic compound of this embodiment can reach 2592 MPa, 672 MPa and 38.2% respectively.

[0042] Example 3 This example provides a high-density cross-nano twinned strong plasticized TiAl intermetallic compound and a preparation method thereof.

[0043] In this embodiment, the atomic percentage concentration of Al in the TiAl intermetallic compound is 44 at.%, the atomic percentage concentration of Nb is 9 at.%, the atomic percentage concentration of C is 0.2 at.%, and the balance is Ti.

[0044] The preparation method of high-density cross-nano-twinned plasticized TiAl intermetallic compound in this embodiment includes the following steps: Step 1, sheathing processing: The same plasma rotating electrode atomization powder making method as in Example 1 is used to prepare TiAl intermetallic compound pre-alloyed spherical powder, the particle size distribution of the spherical powder is in the range of 60 to 220 μm, and the oxygen content is controlled below 700 ppm.

[0045] The TiAl intermetallic compound pre-alloyed spherical powder is loaded into a stainless steel sleeve and vibrated. After the powder is filled, the sleeve is vacuum-sealed to obtain a sleeve filled with TiAl powder; step 2, hot isostatic pressing sintering: the sealed sleeve obtained in step 1 is subjected to hot isostatic pressing sintering treatment, the hot isostatic pressing sintering temperature is 1250° C., the pressure is 150 MPa, and the holding time is 4 hours. After furnace cooling, the sleeve is removed to obtain a TiAl ingot; step 3, hot forging: the TiAl ingot obtained in step 2 is subjected to two sleeve upsetting hot forging treatments, the hot forging temperature is 1260° C., the deformation of the first hot forging is 50%, the deformation of the second hot forging is 70%, and the direction of the second hot forging is perpendicular to the direction of the first hot forging, to obtain a TiAl forging blank; step 4, heat treatment: the TiAl forging blank obtained in step 3 is heat treated, the heat treatment temperature is 1250° C., the holding time is 2.5 hours, and high-density cross-nano twinned strong plasticized TiAl intermetallic compound is obtained after air cooling.

[0046] The microstructure of the TiAl intermetallic compound prepared in this embodiment is a near-γ structure, mainly including γ phase and α2 phase, with the γ phase content being 77% and the α2 phase content being 23%. The γ phase grain size of the TiAl intermetallic compound is 7-20 μm. Figure 5 This is a transmission electron microscope photo of the cross stacking fault in the γ grains of the strong plasticity TiAl intermetallic compound prepared in this embodiment, as shown in FIG. Figure 5 As shown in the figure, the γ phase grains contain obvious cross stacking faults; the TiAl intermetallic compound forms high-density cross nanotwins and at least two twins during the plastic deformation process at room temperature.

[0047] Example 4 This example provides a high-density cross-nano twinned strong plasticized TiAl intermetallic compound and a preparation method thereof.

[0048] In this embodiment, the atomic percentage concentration of Al in the TiAl intermetallic compound is 47 at.%, the atomic percentage concentration of Nb is 10 at.%, the atomic percentage concentration of C is 0.5 at.%, and the balance is Ti.

[0049] The preparation method of high-density cross-nano-twinned plasticized TiAl intermetallic compound in this embodiment includes the following steps: Step 1, sheathing processing: The same plasma rotating electrode atomization powder making method as in Example 1 is used to prepare TiAl intermetallic compound pre-alloyed spherical powder, the particle size distribution of the spherical powder is in the range of 60 to 220 μm, and the oxygen content is controlled below 700 ppm.

[0050] The TiAl intermetallic compound pre-alloyed spherical powder is placed in a stainless steel bag and vibrated to compact the powder. After the powder is filled, the bag is vacuum-sealed to obtain a bag filled with TiAl powder.

[0051] Step 2, hot isostatic pressing and sintering: the sealed and welded package obtained in step 1 is subjected to hot isostatic pressing and sintering treatment. The hot isostatic pressing and sintering temperature is 1300° C., the pressure is 140 MPa, and the heat and pressure holding time is 2 h. After the furnace is cooled, the package is removed to obtain a TiAl ingot.

[0052] Step 3, hot forging: The TiAl ingot obtained in step 2 is subjected to two canned upsetting hot forging treatments, the hot forging temperature is 1300°C, the deformation amount of the first hot forging is 60%, and the deformation amount of the second hot forging is 80%, and the second hot forging direction is perpendicular to the first hot forging direction, to obtain a TiAl forging billet;

[0053] Step 4: Heat treatment: The TiAl forging blank obtained in step 3 is heat treated at a temperature of 1300° C. for 1 h, and air-cooled to obtain a high-density cross-nano twinned, strongly plasticized TiAl intermetallic compound.

[0054] The TiAl intermetallic compound prepared in this example exhibits a near-γ microstructure, primarily comprising γ and α2 phases, with the γ phase comprising 75% and the α2 phase comprising 25%. The γ phase grains of the TiAl intermetallic compound range from 7 to 20 μm, and the γ phase grains contain cross-stacked faults. The TiAl intermetallic compound exhibits a high density of cross-nano-twins, with at least two twins formed.

[0055] Comparative Example 1 This comparative example provides a TiAl intermetallic compound with low niobium content and a preparation method thereof.

[0056] In the comparative example, the atomic percentage concentration of Al in the TiAl intermetallic compound is 47 at.%, the atomic percentage concentration of Nb is 2 at.%, the atomic percentage concentration of C is 0.3 at.%, and the balance is Ti.

[0057] The preparation method of the TiAl intermetallic compound in this comparative example includes the following steps: Step 1, sheathing processing: The same plasma rotating electrode atomization powder making method as in Example 1 is used to prepare a TiAl intermetallic compound pre-alloyed spherical powder, the particle size distribution of the spherical powder is in the range of 60 to 220 μm, and the oxygen content is controlled below 700 ppm.

[0058] The TiAl intermetallic compound pre-alloyed spherical powder is placed in a stainless steel bag and vibrated to compact the powder. After the powder is filled, the bag is vacuum-sealed to obtain a bag filled with TiAl powder.

[0059] Step 2, hot isostatic pressing and sintering: the sealed and welded package obtained in step 1 is subjected to hot isostatic pressing and sintering at a temperature of 1300° C., a pressure of 160 MPa, and a holding time of 3 hours. After the furnace is cooled, the package is removed to obtain a TiAl ingot;

[0060] Step 3, hot forging: The TiAl ingot obtained in step 2 is subjected to two canned upsetting hot forging treatments, the hot forging temperature is 1250°C, the deformation of the first hot forging is 40%, and the deformation of the second hot forging is 60%, and the direction of the second hot forging is perpendicular to the direction of the first hot forging, to obtain a TiAl forging billet;

[0061] Step 4: Heat treatment: The TiAl forging blank obtained in step 3 is heat treated at a temperature of 1250° C. for 2 h, and then air-cooled to obtain a TiAl intermetallic compound.

[0062] The TiAl intermetallic compound prepared in this comparative example exhibited a near-γ microstructure, primarily comprising γ and α2 phases, with the γ phase content being 89% and the α2 phase content being 11%. The γ phase grain size of the TiAl intermetallic compound prepared in this comparative example ranged from 10 to 20 μm, with essentially no cross-stacking faults within the γ phase grains. High-density cross-nano-twins were not formed during room-temperature plastic deformation.

[0063] Comparative Example 2 The only difference between this comparative example and Example 3 is that the heat treatment in step four of this comparative example adopts a traditional heat treatment process, which is as follows: Step four, heat treatment: After completing the hot forging in step three, the obtained TiAl forging billet is directly subjected to annealing heat treatment. The heat treatment temperature is 850°C, the holding time is 2h, and the TiAl intermetallic compound is obtained after furnace cooling.

[0064] The TiAl intermetallic compound prepared in this comparative example exhibits a dual-state microstructure, primarily comprising γ-phase grains and γ / α2 lamellae. The γ-phase grain content is 75%, and the γ / α2 lamellae content is 25%. The γ-phase grain size of the TiAl intermetallic compound prepared in this comparative example ranges from 5 to 17 μm, and the γ-phase grains contain numerous dislocations, forming a high density of dislocations during plastic deformation at room temperature.

[0065] The mechanical properties of the TiAl intermetallic compounds prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were measured using GB / T 7314-2017. The results are shown in Table 1.

[0066] Table 1

[0067] Test items Compressive strength MPa Yield strength MPa Fracture strain% Example 1 2507 653 35.3 Example 2 2592 672 38.2 Example 3 2597 697 39.6 Example 4 2583 687 36.5 Comparative Example 1 2315 608 31.4 Comparative Example 2 2189 627 34.2

[0068] Comparison of the data in Table 1 demonstrates that the TiAl intermetallic compound of the present invention is a high-niobium TiAl intermetallic compound with a low stacking fault energy, which favors the formation of twins during deformation. The present invention utilizes a non-traditional preparation process combining powder metallurgy and forging to generate a large number of cross-stacking faults within the γ grains of the resulting high-niobium TiAl intermetallic compound. These cross-stacking faults serve as effective nucleation sites for twins, enabling the prepared TiAl intermetallic compound to form high-density cross-nano-twins during deformation, effectively achieving strong plasticization and resulting in exceptionally excellent room-temperature compressive properties.

Claims

1. A method for preparing a strong plastic TiAl intermetallic compound, characterized in that: The steps include: Step 1: Cannula processing: TiAl intermetallic compound pre-alloyed spherical powder is placed in a steel cannula and vibrated to compact the powder. After the powder is filled, the cannula is vacuum-sealed to obtain a cannula filled with TiAl powder. Step 2: Hot isostatic pressing and sintering: The sealed and welded package obtained in step 1 is subjected to hot isostatic pressing and sintering treatment, and the package is removed after furnace cooling to obtain a TiAl ingot; Step 3, hot forging: The TiAl ingot obtained in step 2 is subjected to two canned hot forging treatments, with the second hot forging direction being perpendicular to the first hot forging direction, to obtain a TiAl forging billet; Step 4: Heat treatment: The TiAl forging blank obtained in step 3 is heat treated to obtain a high-density cross-nano twinned, strongly plasticized TiAl intermetallic compound after cooling.

2. The method for preparing a high-plasticity TiAl intermetallic compound according to claim 1, characterized in that: Step 1: The particle size distribution of the TiAl intermetallic compound pre-alloyed spherical powder is in the range of 60 to 220 μm, and the oxygen content of the TiAl intermetallic compound pre-alloyed spherical powder is controlled to be below 700 ppm.

3. The method for preparing a high-plasticity TiAl intermetallic compound according to claim 1, characterized in that: Step 1: The TiAl intermetallic compound pre-alloyed spherical powder is prepared by a plasma rotating electrode atomization powder making method.

4. The method for preparing a high-plasticity TiAl intermetallic compound according to claim 3, characterized in that: The temperature of the hot isostatic pressing sintering in step 2 is 1200-1300° C., the pressure is 140-170 MPa, and the heat preservation and pressure holding time is 2-5 hours.

5. The method for preparing a high-plasticity TiAl intermetallic compound according to claim 4, characterized in that: The temperature of the hot forging in step 3 is 1200-1300° C., the deformation amount of the first hot forging is 30-60%, and the deformation amount of the second hot forging is 50-80%.

6. The method for preparing a high-plasticity TiAl intermetallic compound according to claim 5, characterized in that: The heat treatment temperature in step 4 is 1200-1300° C., and the holding time is 1-5 hours.

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