A method for preparing TiAl alloy engine blades

Abstract

A low-cost, high-performance TiAl alloy engine blade preparation method relates to the technical field of TiAl alloy preparation. The present invention proposes a method combining precision casting with vacuum isothermal forging to prepare TiAl alloy blades. The process route is "prefabric melting and precision casting-annealing heat treatment-vacuum isothermal forging of blade final forgings-heat treatment-blade processing". Compared with cast blades, the mechanical properties are significantly improved, and the yield rate is also significantly increased; compared with traditional forged blades, the process is greatly shortened, which greatly reduces the manufacturing cost; compared with ingot / rod casting + high-temperature forging, the method of the present invention improves material utilization and mechanical properties, and can also reduce manufacturing costs; in addition, compared with forging under atmospheric conditions, there is no severe oxidation problem, and the material utilization and mechanical properties are significantly improved. Therefore, the method proposed in the present invention has important commercial value.

Description

Technical Field

[0001] The present invention relates to the technical field of TiAl alloy preparation, and in particular to a method for preparing a TiAl alloy engine blade with low cost and high performance. Background Art

[0002] As a new lightweight, high-temperature resistant structural material, TiAl alloy boasts excellent properties such as low density, high specific strength, high specific stiffness, good oxidation resistance, creep resistance, fatigue resistance, and good flame retardancy. With a service temperature range of 600-850°C, it is an ideal lightweight, high-temperature resistant metal structural material to replace high-density high-temperature alloys, and has broad application prospects in industries such as aviation, aerospace, and engines. Blades, including low-pressure turbine blades and high-pressure compressor blades, are among the most critical components in aerospace engines. Currently, blades with a temperature resistance exceeding 550°C are primarily made of nickel-based high-temperature alloys. Since TiAl alloy has only half the density of nickel-based high-temperature alloys, replacing them with TiAl alloys can reduce disk weight by 40-50%, significantly improving aerospace engine performance.

[0003] At present, TiAl alloy blades are mainly prepared by two hot forming methods: casting and high-temperature forging. However, cast TiAl alloy blades have coarse structure and are prone to defects such as shrinkage cavities, porosity, and pores. Their strength and plasticity are low, and the yield rate is not high. TiAl alloy blades prepared by high-temperature forging have high mechanical properties, but the process is more complicated. It usually requires "ingot casting-annealing heat treatment-jacketed hot extrusion-annealing heat treatment-preform machining-high-temperature pre-forging of blade pre-forgings-high-temperature final forging of blade final forgings-heat treatment-blade processing". The process is long, the processing allowance is large, and the material utilization rate is low, resulting in very high costs. Before forging the blades, it is usually necessary to jacket and hot extrude the TiAl alloy to refine the grains, reduce the deformation resistance during the forging process, and improve the blade forming ability. In addition, if high-temperature forging under the atmosphere is used, due to the thin thickness of the blade body of the blade-like component, due to severe oxidation at the high temperature of forging, it is easy to cause oxygen to diffuse into the interior of the material, resulting in a significant decrease in the mechanical properties of the blade body. At present, in order to avoid the hazards of severe oxidation and oxygen diffusion under the atmosphere, the forgings are reserved with a large processing allowance, and precision forging cannot be achieved, which also reduces material utilization and increases costs. In response to the above problems, this patent proposes to first prepare a TiAl alloy blade prefabricated blank with a certain shape through a precision casting method, and then vacuum isothermally forge the prefabricated blank into a TiAl alloy blade forging. This not only reduces the process flow, but also allows for precision forging, significantly reduces processing allowances, improves material utilization, and reduces costs.

[0004] Patent application number 201780038575.4 proposes a TiAl alloy forging method, but this method is a method of high-temperature forging of ingots. It does not use precision casting to prepare preforms before forging, and it does not use vacuum conditions for forging. Therefore, the machining allowance of the forgings must be large and severely oxidized. Patent application number 202310446326.6 also only performs isothermal forging on cast bars, without precision casting preforms before forging. Similarly, the forged forgings have large machining allowances and severe oxidation. The methods of the above two patents will inevitably significantly reduce material utilization and performance, while increasing the manufacturing cost of TiAl alloy blade forgings. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a method for preparing a low-cost and high-performance TiAl alloy engine blade.

[0006] The present invention provides a method for preparing a low-cost, high-performance TiAl alloy engine blade, which comprises the following steps:

[0007] Step 1: obtaining a TiAl alloy preform for vacuum isothermal forging by a precision casting method;

[0008] Step 2, pretreatment: evenly apply forging lubricant to the TiAl alloy preform and the surface of the forging die used in the vacuum isothermal forging equipment;

[0009] Step 3, vacuuming and heating before forging: After the lubricant is dried, the TiAl alloy preform is placed on the lower die of the vacuum isothermal forging equipment, and the equipment is vacuumed until the vacuum degree reaches 10 -4 After the pressure reaches 50 Pa, heating begins, and the set heating temperature is 1050-1450 ° C. When the TiAl alloy preform and the mold reach the set temperature, they are kept warm for 1-60 minutes.

[0010] Step 4, vacuum isothermal forging of the blade die forging: after the heat preservation is completed, the TiAl alloy preform is vacuum isothermal forged; the vacuum degree during the vacuum isothermal forging is maintained at the vacuum degree of step 3; the temperature of step 3 is maintained constant during the forging process; the strain rate during the forging process is kept constant and controlled between 0.1 and 0.0001 / s; after the die forging die is closed, isothermal pressure holding is performed under vacuum conditions, the pressure holding temperature is still maintained at the temperature of step 3, and the pressure holding time is 2-100 minutes. After the pressure holding is completed, the TiAl alloy preform is cooled. After cooling to room temperature -500°C, the TiAl alloy forging is removed from the vacuum isothermal forging equipment and the surface is cleaned to prepare the TiAl alloy blade die forging;

[0011] Step 5, post-processing of the blade die forging: heat treating the TiAl alloy blade die forging after forging in step 4, and then processing and polishing it to prepare a TiAl alloy engine blade;

[0012] Furthermore, the specific process of obtaining the TiAl alloy preform for vacuum isothermal forging by casting in step 1 is as follows:

[0013] A TiAl alloy blade preform casting for vacuum isothermal forging is obtained by a precision casting method. The casting riser is cut off and annealing is performed. The annealing process is 850-1050°C and 1-30 hours. Finally, the casting is surface finished to obtain a TiAl alloy blade preform that can be used for forging.

[0014] Furthermore, the precision casting method is a graphite-type precision casting method, a metal-type precision casting method or an oxide-ceramic-type precision casting method.

[0015] Furthermore, the forging lubricant in step 2 is one or more of boron nitride lubricant, glass lubricant, and graphite lubricant.

[0016] Furthermore, the die forging die material of the vacuum isothermal forging equipment described in step 2 is one or more of graphite, high-temperature alloy, molybdenum alloy, and tungsten alloy.

[0017] Further, the equipment is vacuumed as described in step 3 until the vacuum degree reaches 10 -2 After the pressure reaches 50 Pa, heating begins, and the set heating temperature is 1100-1400 ° C. When the TiAl alloy preform and the mold reach the set temperature, they are kept warm for 1-60 minutes.

[0018] Further, the equipment is vacuumed as described in step 3 until the vacuum degree reaches 10 -1 After the pressure reaches 50 Pa, heating is started, and the set heating temperature is 1200-1300 ° C. When the TiAl alloy preform and the mold reach the set temperature, they are kept warm for 1-60 minutes.

[0019] Furthermore, the vacuum isothermal forging is as follows: during the forging process, the vacuum degree is maintained at the vacuum degree of step 3; during the forging process, the temperature of step 3 is maintained constant, and the temperature variation is within ±15°C; during the forging process, the strain rate is maintained constant and controlled between 0.1 and 0.001 / s; after the die forging die is closed, isothermal pressure holding is performed under vacuum conditions, the pressure holding temperature is still maintained at the temperature of step 3, and the pressure holding time is 2-100 minutes. After the pressure holding is completed, the TiAl alloy forging is cooled, and after cooling to room temperature -500°C, the TiAl alloy forging is removed from the vacuum isothermal forging equipment and the surface is cleaned to prepare a TiAl alloy blade die forging.

[0020] Furthermore, the vacuum isothermal forging is as follows: during the forging process, the vacuum degree is maintained at the vacuum degree of step 3; during the forging process, the temperature of step 3 is maintained constant, and the temperature variation is within ±15°C; during the forging process, the strain rate is maintained constant and controlled between 0.1 and 0.01 / s; after the die forging die is closed, isothermal pressure holding is performed under vacuum conditions, the pressure holding temperature is still maintained at the temperature of step 3, and the pressure holding time is 2-100 minutes. After the pressure holding is completed, the TiAl alloy forging is cooled, and after cooling to room temperature -500°C, the TiAl alloy forging is removed from the vacuum isothermal forging equipment and the surface is cleaned to prepare a TiAl alloy blade die forging.

[0021] Furthermore, the heat treatment in step 5 is one-step annealing heat treatment, solution aging heat treatment, multi-step heat treatment or cyclic heat treatment; the heat treatment temperature is 850-1420° C., and the heat treatment time is 5 minutes to 25 hours.

[0022] The present invention has the following beneficial effects:

[0023] (1) In view of the technical characteristics of the TiAl alloy blade preparation method, the present invention proposes a method of combining precision casting with vacuum isothermal forging to prepare TiAl alloy blades. The process route is "prefabricated billet melting and precision casting - annealing heat treatment - vacuum isothermal forging of blade final forging - heat treatment - blade processing". Compared with cast blades, due to high temperature forging, the disadvantages of casting such as coarse structure, easy formation of shrinkage cavities and porosity are eliminated, the mechanical properties are significantly improved, and the yield rate is also significantly increased;

[0024] (2) The process of preparing blades by traditional forging methods is relatively long: "ingot casting - annealing heat treatment - hot extrusion with jacketing - annealing heat treatment - preform machining - high-temperature preforging of blade preforgings - high-temperature final forging of blade final forgings - heat treatment - blade processing". Hot extrusion is required first to refine the grains, thereby reducing the deformation resistance of the blade during die forging and increasing the service life of the forging die. However, forging under vacuum isothermal conditions can achieve isothermal forging at a higher temperature, and the temperature field is uniform. There is no temperature drop problem of traditional high-temperature forging or jacketed hot forging methods, so the deformation resistance will be significantly reduced. There is no need to hot extrude the TiAl alloy first and then forge it at high temperature, which will not reduce the service life of the forging die, resulting in a significant reduction in cost. In addition, compared with traditional hot extrusion + high-temperature forging blades, the production cost will be greatly reduced due to the significant shortening of the process;

[0025] (3) Compared with ingot / rod casting + high-temperature forging, the method of the present invention can achieve precision forging, significantly reduce processing allowance, improve material utilization and mechanical properties, and at the same time reduce the manufacturing cost of TiAl alloy blade forgings.

[0026] Therefore, the preparation method of TiAl alloy engine blades proposed in the present invention significantly improves material utilization and mechanical properties, reduces processing allowance, and is a low-cost, high-performance, short-process high-quality TiAl alloy engine blade preparation method that can meet the application of blade-type components for aerospace engines. The method is used to prepare TiAl alloy engine blades, which can be used for large-scale industrial production and has important commercial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The microstructure of the prepared Ti-45Al-4Nb-0.5Mo-0.1B alloy blade die forging;

[0028] Figure 2 The microstructure of the prepared Ti-44.5Al-8Nb-0.2Y alloy blade die forging;

[0029] Figure 3 This is the microstructure diagram of the prepared Ti-45.5Al-4Nb-1Cr-0.05B ​​alloy blade die forging. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the embodiments of the present invention more clearly understood, the spirit of the contents disclosed in the present invention will be described in detail below. After understanding the embodiments of the contents of the present invention, any technician in the relevant technical field can change and modify the contents of the present invention based on the techniques taught by the contents of the present invention without departing from the spirit and scope of the contents of the present invention.

[0031] The exemplary embodiments of the present invention and the description thereof are used to explain the present invention but are not intended to limit the present invention.

[0032] Example 1:

[0033] A TiAl alloy blade with a nominal composition of Ti-45Al-4Nb-0.5Mo-0.1B (at.%) was prepared by combining metal mold precision casting with vacuum isothermal forging. The specific process is as follows:

[0034] (1) A steel mold required for the melting and casting of the TiAl alloy preform before vacuum isothermal forging was prepared by machining. The TiAl alloy raw material was melted in a water-cooled copper crucible vacuum induction melting and casting equipment and poured into a metal mold. The TiAl alloy preform casting was removed from the mold, the pouring head was cut off and annealed at 900°C for 10 hours. Finally, the surface of the casting was smoothed to obtain a TiAl alloy preform that can be used for forging.

[0035] (2) A layer of boron nitride lubricant is evenly coated on the surface of the TiAl alloy blade preform and the forging die used in the vacuum isothermal forging equipment;

[0036] (3) After the lubricant is dried, the TiAl alloy blade preform is placed on the lower die of the vacuum isothermal forging equipment, and the equipment is vacuumed and heated. When the TiAl alloy preform and the die reach the set temperature, they are kept warm. When the vacuum degree reaches 10 -2 After that, heating was started, and the set temperature of heating was 1250℃. When the TiAl alloy preform and the mold reached the set temperature, they were kept warm for 10 minutes.

[0037] (4) After the heat preservation is completed, the TiAl alloy preform is subjected to vacuum isothermal forging; during the forging process, the vacuum degree is maintained at the vacuum degree of step 3; during the forging process, the temperature of step 3 is maintained constant, and the temperature change is within ±5°C; during the forging process, the strain rate is kept constant and controlled at 0.0005 / s; after the die forging die is closed, isothermal pressure holding is performed under vacuum conditions, and the pressure holding temperature is still maintained at the temperature of step 3, and the pressure holding time is 10 minutes. After the pressure holding is completed, the preform is cooled, and after cooling to room temperature, the TiAl alloy forging is taken out of the vacuum isothermal forging equipment to prepare a TiAl alloy blade die forging;

[0038] (5) After forging, the die forging was subjected to vacuum annealing heat treatment at 900°C for 6 hours, the flash of the TiAl alloy blade die forging was removed, and then the die forging was processed to remove the excess and polished to prepare the TiAl alloy engine blade.

[0039] The prepared Ti-45Al-4Nb-0.5Mo-0.1B alloy blade die forgings have a smooth appearance and no defects. The microstructure is shown in the figure below. Figure 1 As shown, the grain size is fine and uniform, the room temperature tensile strength is 915 MPa, the room temperature elongation is 2.6%, and the material utilization rate for preparing TiAl alloy blades reaches 87%. The method proposed in this invention combines precision casting with vacuum isothermal forging to produce Ti-45Al-4Nb-0.5Mo-0.1B alloy blade die forgings, which has significant cost and performance advantages.

[0040] Comparative Example 1:

[0041] A TiAl alloy blade die forging with a nominal composition of Ti-45Al-4Nb-0.5Mo-0.1B (at%) was produced using conventional ingot / rod casting followed by isothermal forging under atmospheric conditions. The forging process parameters were identical to those in Example 1, except for the absence of vacuum (atmospheric conditions). After forging, the die forgings were subjected to a vacuum annealing heat treatment at 900°C for 6 hours. The flash of the TiAl alloy blade die forgings was removed, and the forgings were then machined to remove excess material and polished. This resulted in a TiAl alloy engine blade. However, the material utilization rate was only 15-21%. Compared to Example 1, this low material utilization rate significantly increased the manufacturing cost of the TiAl alloy blade. Furthermore, due to the intense oxidation and oxygen diffusion during the forging process, the room temperature tensile strength was only 518 MPa, and the room temperature elongation was only 0.4%.

[0042] Comparative Example 2:

[0043] A TiAl alloy blade die forging with a nominal composition of Ti-45Al-4Nb-0.5Mo-0.1B (at.%) was prepared by using a high-temperature forging technology in which a conventional ingot is hot-extruded into a bar and then pre-forged and final-forged. The forging process parameters were the same as those in Example 1. After forging, the die forging was subjected to a vacuum annealing heat treatment at 900°C for 6 hours. The flash of the TiAl alloy blade die forging was removed, and the die forging was then processed to remove the excess and polished to prepare a TiAl alloy engine blade. The mechanical properties of the TiAl alloy engine blade were similar to those in Example 1, but the material utilization rate was only 26%. Compared with Example 1, the low material utilization rate significantly increased the manufacturing cost of the TiAl alloy blade.

[0044] Example 2:

[0045] A TiAl alloy blade with a nominal composition of Ti-44.5Al-8Nb-0.2Y (at.%) was prepared by combining graphite mold precision casting with vacuum isothermal forging. The specific process is as follows:

[0046] (1) A graphite mold required for the melting and casting of a TiAl alloy preform before vacuum isothermal forging is prepared by machining. The TiAl alloy raw material is melted in a vacuum induction suspension casting device and poured into the graphite mold. The TiAl alloy preform casting is taken out of the mold, the pouring head is cut off, and the casting is annealed at 970°C for 15 hours. Finally, the casting is surface finished to obtain a TiAl alloy preform that can be used for forging.

[0047] (2) A layer of graphite lubricant is evenly coated on the surface of the TiAl alloy blade preform and the forging die used in the vacuum isothermal forging equipment;

[0048] (3) After the lubricant is dried, the TiAl alloy blade preform is placed on the lower die of the vacuum isothermal forging equipment, and the equipment is vacuumed and heated. When the TiAl alloy preform and the die reach the set temperature, they are kept warm. When the vacuum degree reaches 10 -1 After that, heating was started, and the set heating temperature was 1310℃. When the TiAl alloy preform and the mold reached the set temperature, they were kept warm for 15 minutes.

[0049] (4) After the heat preservation is completed, the TiAl alloy preform is subjected to vacuum isothermal forging; during the forging process, the vacuum degree is maintained at the vacuum degree of step 3; during the forging process, the temperature of step 3 is maintained constant, and the temperature change is within ±3°C; during the forging process, the strain rate is kept constant and controlled at 0.0001 / s; after the die forging die is closed, isothermal pressure holding is carried out under vacuum conditions, and the pressure holding temperature is still maintained at the temperature of step 3, and the pressure holding time is 20 minutes. After the pressure holding is completed, it is cooled, and after cooling to room temperature, the TiAl alloy forging is taken out of the vacuum isothermal forging equipment to prepare a TiAl alloy blade die forging.

[0050] (5) After forging, the die forging was subjected to vacuum annealing heat treatment at 1000°C for 10 hours, the flash of the TiAl alloy blade die forging was removed, and then the die forging was processed to remove the excess and polished to prepare the TiAl alloy engine blade.

[0051] The prepared Ti-44.5Al-8Nb-0.2Y alloy blade die forging has a smooth appearance and no defects. Its microstructure is shown in the figure below. Figure 2 As shown, the grain size is fine and uniform, the room temperature tensile strength is 978 MPa, the room temperature elongation is 2.7%, and the material utilization rate for preparing TiAl alloy blades reaches 83%. The method proposed in this invention combines precision casting with vacuum isothermal forging to produce Ti-44.5Al-8Nb-0.2Y alloy blade die forgings, which has significant cost and performance advantages.

[0052] Example 3:

[0053] A TiAl alloy blade with a nominal composition of Ti-45.5Al-4Nb-1Cr-0.05B ​​(at.%) was prepared by combining oxide ceramic mold investment casting with vacuum isothermal forging. The specific process is as follows:

[0054] (1) The oxide ceramic investment casting mold required for the melting and casting of the TiAl alloy preform before vacuum isothermal forging was prepared by using ceramic shell preparation technology. The TiAl alloy raw materials were melted in a water-cooled copper crucible vacuum induction melting and casting equipment and poured into the oxide ceramic casting mold. The TiAl alloy preform casting was taken out from the casting mold, the pouring riser was cut off and annealed at 920℃ for 10 hours. Finally, the casting was surface finished to obtain a TiAl alloy preform that can be used for forging.

[0055] (2) A layer of boron nitride lubricant is evenly coated on the surface of the TiAl alloy blade preform and the forging die used in the vacuum isothermal forging equipment;

[0056] (3) After the lubricant is dried, the TiAl alloy blade preform is placed on the lower die of the vacuum isothermal forging equipment, and the equipment is vacuumed and heated. When the TiAl alloy preform and the die reach the set temperature, they are kept warm. When the vacuum degree reaches 10 -1 After that, heating was started, and the set heating temperature was 1270℃. When the TiAl alloy preform and the mold reached the set temperature, they were kept warm for 15 minutes.

[0057] (4) After the heat preservation is completed, the TiAl alloy preform is subjected to vacuum isothermal forging; during the forging process, the vacuum degree is maintained at the vacuum degree of step 3; during the forging process, the temperature of step 3 is maintained constant, and the temperature change is within ±5°C; during the forging process, the strain rate is kept constant and controlled at 0.001 / s; after the die forging die is closed, isothermal pressure holding is carried out under vacuum conditions, and the pressure holding temperature is still maintained at the temperature of step 3, and the pressure holding time is 15 minutes. After the pressure holding is completed, it is cooled, and after cooling to room temperature, the TiAl alloy forging is taken out of the vacuum isothermal forging equipment to prepare a TiAl alloy blade die forging.

[0058] (5) After forging, the die forging was subjected to vacuum annealing heat treatment at 920°C for 15 hours, the flash of the TiAl alloy blade die forging was removed, and then the die forging was processed to remove the excess and polished to prepare the TiAl alloy engine blade.

[0059] The prepared Ti-45Al-4Nb-1Cr-0.05B ​​alloy blade die forging has a smooth appearance and no defects. Its microstructure is shown in the figure below. Figure 3 As shown, the grains are fine and uniform, with a room temperature tensile strength of 736 MPa and a room temperature elongation of 2.3%. The utilization rate of TiAl alloy blades produced reaches 86%. The method proposed in this invention combines precision casting with vacuum isothermal forging to produce Ti-45Al-4Nb-1Cr-0.05B ​​alloy blade die forgings, offering significant cost and performance advantages.

[0060] The present invention is not limited to the enumerated embodiments, and all improvements and variations based on this method and this method are included in the patent scope of the present invention.

Claims

1. A method for preparing a TiAl alloy engine blade, characterized in that It includes the following steps: Step 1: obtaining a TiAl alloy preform for vacuum isothermal forging by a precision casting method; Step 2, pretreatment: evenly apply forging lubricant to the TiAl alloy preform and the surface of the forging die used in the vacuum isothermal forging equipment; Step 3, vacuuming and heating before forging: After the lubricant is dried, the TiAl alloy preform is placed on the lower die of the vacuum isothermal forging equipment, and the equipment is vacuumed until the vacuum degree reaches 10 -4 After the pressure reaches 50 Pa, heating begins, and the set heating temperature is 1050-1450 ° C. When the TiAl alloy preform and the mold reach the set temperature, they are kept warm for 1-60 minutes. Step 4, vacuum isothermal forging of the blade die forging: after the heat preservation is completed, the TiAl alloy preform is vacuum isothermal forged; the vacuum degree during the vacuum isothermal forging is maintained at the vacuum degree of step 3; the temperature of step 3 is maintained constant during the forging process; the strain rate during the forging process is kept constant and controlled between 0.1 and 0.0001 / s; after the die forging die is closed, isothermal pressure holding is performed under vacuum conditions, the pressure holding temperature is still maintained at the temperature of step 3, and the pressure holding time is 2-100 minutes. After the pressure holding is completed, the TiAl alloy preform is cooled. After cooling to room temperature, the TiAl alloy forging is removed from the vacuum isothermal forging equipment and the surface is cleaned to prepare the TiAl alloy blade die forging; Step 5, post-processing of the blade die forging: heat treating the TiAl alloy blade die forging after forging in step 4, and then processing and polishing it to prepare a TiAl alloy engine blade; The specific process of obtaining the TiAl alloy preform for vacuum isothermal forging by casting in step 1 is as follows: A TiAl alloy blade preform for vacuum isothermal forging is obtained by precision casting, the casting is cut off from the pouring head and annealed at 850-1050°C for 1-30 hours, and the casting is surface finished to obtain a TiAl alloy blade preform for forging; The precision casting method is a graphite mold precision casting method, a metal mold precision casting method or an oxide ceramic mold precision casting method; The heat treatment in step 5 is one-step annealing heat treatment, solution aging heat treatment, multi-step heat treatment or cyclic heat treatment; the heat treatment temperature is 850-1420° C., and the heat treatment time is 5 minutes to 25 hours.

2. The method for preparing a TiAl alloy engine blade according to claim 1, characterized in that The forging lubricant described in step 2 is one or more of boron nitride lubricant, glass lubricant, and graphite lubricant.

3. The method for preparing a TiAl alloy engine blade according to claim 1, characterized in that The die forging die material of the vacuum isothermal forging equipment described in step 2 is one or more of graphite, high-temperature alloy, molybdenum alloy, and tungsten alloy.

4. The method for preparing a TiAl alloy engine blade according to claim 1, characterized in that Vacuum the equipment as described in step 3 until the vacuum degree reaches 10 -2 After the pressure reaches 50 Pa, heating begins, and the set heating temperature is 1100-1400 ° C. When the TiAl alloy preform and the mold reach the set temperature, they are kept warm for 1-60 minutes.

5. The method for preparing a TiAl alloy engine blade according to claim 1, characterized in that Vacuum the equipment as described in step 3 until the vacuum degree reaches 10 -1 After the pressure reaches 50 Pa, heating is started, and the set heating temperature is 1200-1300 ° C. When the TiAl alloy preform and the mold reach the set temperature, they are kept warm for 1-60 minutes.

6. The method for preparing a TiAl alloy engine blade according to claim 1, characterized in that The vacuum isothermal forging process: during the forging process, the vacuum degree is maintained at the vacuum degree of step 3; during the forging process, the temperature of step 3 is maintained constant, and the temperature variation is within ±15°C; during the forging process, the strain rate is maintained constant and controlled between 0.1 and 0.001 / s.

7. The method for preparing a TiAl alloy engine blade according to claim 1, characterized in that The vacuum isothermal forging process: during the forging process, the vacuum degree is maintained at the vacuum degree of step 3; during the forging process, the temperature of step 3 is maintained constant, and the temperature variation is within ±15°C; during the forging process, the strain rate is maintained constant and controlled between 0.1 and 0.01 / s.

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