Preparation method of low-cost high-performance TiAl alloy engine blade

Abstract

The invention discloses a preparation method of a low-cost high-performance TiAl alloy engine blade, relates to the technical field of TiAl alloy preparation, and provides a method for preparing the TiAl alloy blade by combining precision casting and vacuum isothermal forging. The process route comprises the steps of prefabricated blank smelting and precision casting, annealing heat treatment, vacuum isothermal forging of a blade final forging piece, heat treatment and blade machining, and compared with a cast blade, the mechanical property is remarkably improved, and the yield is also remarkably increased; compared with a traditional forged blade, the manufacturing cost is greatly reduced due to the fact that the process is greatly shortened; compared with ingot casting / rod casting and high-temperature forging, the method has the advantages that the material utilization rate and the mechanical property are improved, and the manufacturing cost can be reduced; in addition, compared with forging under the atmospheric condition, the problem of severe oxidation does not exist, and the material utilization rate and the mechanical property are obviously improved. Therefore, the method provided by the invention has important commercial value.

Description

Technical Field

[0001] The 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 type of lightweight high-temperature resistant structural material, TiAl alloy has excellent performance characteristics such as low density, high specific strength, high specific stiffness, good oxidation resistance, creep resistance, fatigue resistance, and good flame retardancy. The service temperature range reaches 600-850℃. It is an ideal lightweight high-temperature resistant metal structural material to replace high-density high-temperature alloys, and has broad application prospects in aviation, aerospace and engine industries. In aerospace engines, blade components including low-pressure turbine blades and high-pressure compressor blades are one of the most important parts. At present, the blade material with a temperature resistance of more than 550℃ is mainly nickel-based high-temperature alloys. Since the density of TiAl alloy is only half of that of nickel-based high-temperature alloys, the use of TiAl alloys to replace high-temperature alloys can achieve a 40-50% weight reduction of disks, thereby greatly improving the performance of aerospace engines.

[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, shrinkage porosity and pores, so 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 melting-annealing heat treatment-jacket 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 in the atmosphere is used, due to the thin thickness of the blade body of the blade-like components, due to severe oxidation at the high temperature of forging, it is easy to cause oxygen to diffuse into the material, resulting in a significant decrease in the mechanical properties of the blade body. At present, in order to avoid the harm caused by severe oxidation and oxygen diffusion in the atmosphere, the forgings have a large reserved 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 preform with a certain shape by a precision casting method, and then vacuum isothermally forge the preform into a TiAl alloy blade forging, which not only reduces the process flow, but also allows precision forging, significantly reduces the processing allowance, improves material utilization, and reduces costs.

[0004] The patent with 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 prepare pre-forging preforms through precision casting, and it does not use vacuum conditions for forging. Therefore, the machining allowance of the forgings must be large and severely oxidized. The patent with application number 202310446326.6 also only performs isothermal forging on cast bars, without precision casting pre-forging preforms. 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] A method for preparing a low-cost and high-performance TiAl alloy engine blade of the present invention 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 coating the TiAl alloy preform and the surface of the die forging die used in the vacuum isothermal forging equipment with a forging lubricant;

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

[0010] Step 4, vacuum isothermal forging of blade die forgings: after the heat preservation is completed, the TiAl alloy preform is subjected to vacuum isothermal forging; the vacuum isothermal forging: during the forging process, the vacuum degree maintains the vacuum degree of step 3; during the forging process, the temperature of step 3 is maintained constant; during the forging process, the strain rate is maintained 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, the pressure holding time is 2-100 minutes, and after the pressure holding is completed, cooling is performed, and after cooling to room temperature -500°C, the TiAl alloy forging is taken out of 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 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 pouring head 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 described 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 device is evacuated as described in step 3 until the vacuum degree reaches 10 -2 After the pressure reaches 50Pa, 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 to 60 minutes.

[0018] Further, the device is evacuated as described in step 3 until the vacuum degree reaches 10 -1 After the pressure reaches 50Pa, heating begins, 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 to 60 minutes.

[0019] Furthermore, the vacuum isothermal forging: during the forging process, the vacuum degree maintains 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 still maintains the temperature of step 3, and the pressure holding time is 2-100 minutes. After the pressure holding is completed, cooling is performed, and after cooling to room temperature -500°C, the TiAl alloy forging is taken out 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: during the forging process, the vacuum degree maintains 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 still maintains the temperature of step 3, and the pressure holding time is 2-100min. After the pressure holding is completed, cooling is performed, and after cooling to room temperature -500°C, the TiAl alloy forging is taken out from the vacuum isothermal forging equipment, and the surface is cleaned to prepare a TiAl alloy blade die forging.

[0021] Furthermore, the heat treatment described 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-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 "preform 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 coarse structure, easy formation of shrinkage cavities, shrinkage and porosity caused by casting 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 - jacket hot extrusion - 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 jacket 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, which will greatly reduce costs. In addition, compared with traditional hot extrusion + high temperature forging blades, the process is greatly shortened, which will greatly reduce production costs;

[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 reduce the manufacturing cost of TiAl alloy blade forgings.

[0026] Therefore, the preparation method of the TiAl alloy engine blade proposed in the present invention significantly improves the material utilization rate and mechanical properties, reduces the 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 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 by 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 them according to 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] Embodiment 1:

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

[0034] (1) preparing a steel mold required for melting and casting a TiAl alloy preform before vacuum isothermal forging by machining, melting the TiAl alloy raw material in a water-cooled copper crucible vacuum induction melting and casting equipment and pouring it into a metal mold, taking out the TiAl alloy preform casting from the mold, cutting off the pouring head and annealing the casting, the annealing process is 900° C. for 10 hours, and finally performing surface finishing on the casting to obtain a TiAl alloy preform that can be used for forging;

[0035] (2) uniformly coating a layer of boron nitride lubricant on the surface of a TiAl alloy blade preform and a die forging die used in a vacuum isothermal forging device;

[0036] (3) After the coated lubricant is dried, the TiAl alloy blade preform is placed on the lower die of the forging die of the vacuum isothermal forging equipment, the equipment is evacuated, and the heating treatment is performed. When the TiAl alloy preform and the die reach the set temperature, the temperature is kept constant; 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 10min.

[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 maintained 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, cooling is performed, and after cooling to room temperature, the TiAl alloy forging is taken out from 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 cut off, and then the excess was removed and polished to prepare the TiAl alloy engine blade.

[0039] The prepared Ti-45Al-4Nb-0.5Mo-0.1B alloy blade forging has a smooth appearance and no defects. Its microstructure is shown in the figure below. Figure 1 As shown, the grains are fine and uniform, the room temperature tensile strength is 915MPa, the room temperature elongation is 2.6%, and the material utilization rate for preparing TiAl alloy blades reaches 87%. The method proposed by the present invention combines precision casting with vacuum isothermal forging to prepare Ti-45Al-4Nb-0.5Mo-0.1B alloy blade die forgings, which has obvious 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 prepared by using conventional ingot / rod casting + isothermal forging technology under atmospheric conditions. The forging process parameters were consistent with those in Example 1 except for non-vacuum (atmospheric conditions). 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 cut off, and then the excess was removed and polished to prepare a TiAl alloy engine blade, but the material utilization rate was only 15-21%. Compared with Example 1, the low material utilization rate significantly increased the manufacturing cost of the TiAl alloy blade; in addition, due to the intense oxidation and oxygen diffusion during the forging process, the room temperature tensile strength was only 518MPa, and the room temperature elongation was 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 adopting a high-temperature forging technology of hot extruding a traditional ingot into a rod and then pre-forging and final forging. The forging process parameters were consistent with 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 cut off, and then the excess was removed and polished to prepare a TiAl alloy engine blade. Its mechanical properties 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] Embodiment 2:

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

[0046] (1) preparing a graphite mold required for melting and casting a TiAl alloy preform before vacuum isothermal forging by machining, melting the TiAl alloy raw material in a vacuum induction suspension melting and casting device and pouring it into the graphite mold, taking out the TiAl alloy preform casting from the mold, cutting off the pouring head and annealing the casting at 970° C. for 15 hours, and finally performing surface finishing on the casting to obtain a TiAl alloy preform that can be used for forging;

[0047] (2) uniformly coating a layer of graphite lubricant on the surface of the TiAl alloy blade preform and the die forging die used in the vacuum isothermal forging equipment;

[0048] (3) After the coated lubricant is dried, the TiAl alloy blade preform is placed on the lower die of the forging die of the vacuum isothermal forging equipment, the equipment is evacuated, and the heating treatment is performed. When the TiAl alloy preform and the die reach the set temperature, the temperature is kept constant; when the vacuum degree reaches 10 -1 After that, heating was started, and the set heating temperature was 1310°C. When the TiAl alloy preform and the mold reached the set temperature, they were kept warm for 15 minutes.

[0049] (4) After the insulation 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 maintained constant and controlled at 0.0001 / 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 20 minutes. After the pressure holding is completed, cooling is performed, and after cooling to room temperature, the TiAl alloy forging is taken out from 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 cut off, and then the excess was removed 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 grains are fine and uniform, the room temperature tensile strength is 978MPa, the room temperature elongation is 2.7%, and the material utilization rate for preparing TiAl alloy blades reaches 83%. The method proposed by the present invention combines precision casting with vacuum isothermal forging to prepare Ti-44.5Al-8Nb-0.2Y alloy blade die forgings, which has obvious cost and performance advantages.

[0052] Embodiment 3:

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

[0054] (1) an oxide ceramic mold precision casting mold required for melting and casting a TiAl alloy preform before vacuum isothermal forging is prepared by using a ceramic shell preparation technology, the TiAl alloy raw material is melted in a water-cooled copper crucible vacuum induction melting and casting equipment and poured into the oxide ceramic mold, the TiAl alloy preform casting is taken out from the mold, the pouring riser is cut off and annealing is performed, the annealing process is 920° C. for 10 hours, and finally the casting is surface finished to obtain a TiAl alloy preform that can be used for forging;

[0055] (2) uniformly coating a layer of boron nitride lubricant on the surface of a TiAl alloy blade preform and a die forging die used in a vacuum isothermal forging device;

[0056] (3) After the coated lubricant is dried, the TiAl alloy blade preform is placed on the lower die of the forging die of the vacuum isothermal forging equipment, the equipment is evacuated, and the heating treatment is performed. When the TiAl alloy preform and the die reach the set temperature, the temperature is kept constant; when the vacuum degree reaches 10 -1 After that, heating was started, and the set heating temperature was 1270°C. When the TiAl alloy preform and the mold reached the set temperature, they were kept warm for 15 minutes.

[0057] (4) After the insulation 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 maintained constant and controlled at 0.001 / 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 15 minutes. After the pressure holding is completed, cooling is performed, and after cooling to room temperature, the TiAl alloy forging is taken out from 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 cut off, and then the excess was removed and polished to prepare the TiAl alloy engine blade.

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

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

Claims

1. A method for preparing a low-cost and high-performance 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 coating the TiAl alloy preform and the surface of the die forging die used in the vacuum isothermal forging equipment with a forging lubricant; Step 3, vacuuming and heating before forging: After the coated lubricant is dried, the TiAl alloy preform is placed on the lower die of the forging die of the vacuum isothermal forging equipment, and the equipment is vacuumed until the vacuum degree reaches 10 -4 After the pressure reaches 50Pa, heating begins, and the set heating temperature is 1050-1450℃. When the TiAl alloy preform and the mold reach the set temperature, they are kept warm for 1 to 60 minutes. Step 4, vacuum isothermal forging of blade die forgings: after the heat preservation is completed, the TiAl alloy preform is subjected to vacuum isothermal forging; the vacuum isothermal forging: during the forging process, the vacuum degree maintains the vacuum degree of step 3; during the forging process, the temperature of step 3 is maintained constant; during the forging process, the strain rate is maintained 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, the pressure holding time is 2-100 minutes, and after the pressure holding is completed, cooling is performed, and after cooling to room temperature -500°C, the TiAl alloy forging is taken out of 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 to prepare a TiAl alloy engine blade.

2. A method for preparing a low-cost and high-performance TiAl alloy engine blade according to claim 1, characterized in that The specific process of obtaining the TiAl alloy preform for vacuum isothermal forging by casting described in step 1 is as follows: A TiAl alloy blade preform casting for vacuum isothermal forging is obtained by a precision casting method. The casting pouring head 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.

3. A method for preparing a low-cost and high-performance TiAl alloy engine blade according to claim 1 or 2, characterized in that 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.

4. A method for preparing a low-cost and high-performance 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.

5. The method for preparing a low-cost and high-performance 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.

6. A method for preparing a low-cost and high-performance TiAl alloy engine blade according to claim 1, characterized in that Evacuate the equipment as described in step 3 until the vacuum reaches 10 -2 After the pressure reaches 50Pa, 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 to 60 minutes.

7. A method for preparing a low-cost, high-performance TiAl alloy engine blade according to claim 1 or 6, characterized in that Evacuate the equipment as described in step 3 until the vacuum reaches 10 -1 After the pressure reaches 50Pa, heating begins, 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 to 60 minutes.

8. The method for preparing a low-cost and high-performance TiAl alloy engine blade according to claim 1, characterized in that The vacuum isothermal forging comprises the following steps: 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, cooling is performed, and after cooling to room temperature -500°C, the TiAl alloy forging is taken out from the vacuum isothermal forging equipment, and the surface is cleaned to prepare the TiAl alloy blade die forging.

9. A method for preparing a low-cost and high-performance TiAl alloy engine blade according to claim 1 or 8, characterized in that The vacuum isothermal forging comprises the following steps: 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, cooling is performed, and after cooling to room temperature -500°C, the TiAl alloy forging is taken out from the vacuum isothermal forging equipment, and the surface is cleaned to prepare the TiAl alloy blade die forging.

10. A method for preparing a low-cost and high-performance TiAl alloy engine blade according to claim 1, characterized in that The heat treatment described 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.

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