Method for preparing single-crystal high-temperature alloy blade from seed crystal

Abstract

The invention provides a method for preparing a single-crystal high-temperature alloy blade from seed crystals, which comprises the following steps: S1) preparing a shell module of the single-crystal high-temperature alloy blade, and enabling the seed crystals to be in gapless contact with a shell of the shell module; and (S2) the shell module is placed on a water-cooling crystallizer, after the shell module is heated, single-crystal high-temperature alloy liquid is poured into a cavity through a transition pouring gate cavity of a pouring system, so that the speed of the single-crystal high-temperature alloy liquid entering the cavity is reduced, and the single-crystal high-temperature alloy blade is obtained after directional solidification. According to the method for preparing the single-crystal high-temperature alloy blade from the seed crystal, the gap between the seed crystal and the mold shell is eliminated, the transition runner cavity is introduced to control the process of filling the mold cavity with alloy liquid, it is guaranteed that a re-melting area of the seed crystal tends to be static and stable, grain proliferation caused by breaking of dendritic crystals in the re-melting area is reduced, and the yield of the single-crystal high-temperature alloy blade is improved. Therefore, the success rate of single crystal seeding is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of single crystal high temperature alloy blades for engines, and in particular to a method for preparing single crystal high temperature alloy blades by using seed crystals. Background Art

[0002] The working environment of aircraft engine turbine blades is high in temperature, complex in stress and the most severe in environment. Turbine blades are one of the key parts in aircraft engines, and their quality and performance significantly affect the performance of the engine.

[0003] Gas turbine engine blades are subjected to the combined effects of high temperature, complex stress, and corrosive atmosphere, and must withstand the instantaneous and drastic changes of starting and braking. The grain boundaries in the turbine blade structure, especially the transverse grain boundaries perpendicular to the stress axis, are the weakest links. The single crystal blade has the characteristic of no grain boundaries, so there is no high-temperature grain boundary weakening, which significantly reduces the tendency of fatigue cracking. Single crystal high temperature alloys are widely used in turbine engine blades due to their excellent creep, durability, high temperature resistance, and thermal mechanical fatigue resistance. The single crystal characteristics significantly increase the operating temperature of the alloy and are considered to be the best material for engine blades.

[0004] During the directional solidification of single crystal high temperature alloys, a phase transition from liquid phase to solid phase occurs, and the phase transition process is carried out through nucleation and growth. The directional solidification of single crystal high temperature alloys must avoid nucleation during the solidification process. The solidification depends on the growth from the solidified solid phase. Therefore, the crystal orientation of the previous solidification determines the crystal orientation of the blade. When preparing single crystal high temperature blades, a seed crystal or spiral crystal selection process structure is used at the beginning of the directional solidification, so that only one oriented grain enters the blade cavity. Directional solidification is carried out on the basis of this grain, thereby obtaining a single crystal casting with only one grain. Therefore, in order to obtain a single crystal, a seed crystal or a spiral structure can be used.

[0005] The seed crystal method can control the three-dimensional orientation of the blade as needed, including primary orientation and secondary orientation. However, when using seed crystals, on the one hand, the direction of the seed crystals needs to be strictly controlled when preparing the wax mold of the single crystal casting to ensure that the required orientation is obtained; on the other hand, when the seed crystal method is used to obtain a single crystal, the seed crystal is placed in the prepared shell mold, and there is a certain gap between the seed crystal and the shell. A large number of studies have shown that the gap between the seed crystal and the shell is one of the main reasons for the failure of seed crystal seeding; in addition, because the seed crystal has been partially melted before the alloy liquid is poured, there is a transition area between the melted and unmelted parts, and the transition area is prone to generate crystal defects.

[0006] Therefore, how to eliminate the gap between the seed crystal and the shell and reduce the seeding defects is of great significance for the preparation of single crystal high-temperature alloy blades. Summary of the invention

[0007] The technical problem solved by the present invention is to provide a method for preparing single crystal high-temperature alloy blades by seed crystal, which can reduce the external force of alloy liquid on dendrites in the remelting zone during the casting process, and realize the method for preparing single crystal high-temperature alloy blades by seed crystal method.

[0008] In view of this, the present application also provides a method for preparing a single crystal high-temperature alloy blade using a seed crystal, comprising the following steps:

[0009] S1) preparing a shell mold set for a single crystal high-temperature alloy blade, so that the seed crystal and the shell of the shell mold set are in gapless contact;

[0010] S2) placing the shell mold assembly on a water-cooled crystallizer, and after the shell mold assembly is heated, pouring the single crystal high-temperature alloy liquid into the mold cavity through the transition runner cavity of the pouring system to reduce the speed at which the single crystal high-temperature alloy liquid enters the mold cavity, and obtaining the single crystal high-temperature alloy blade after directional solidification.

[0011] Preferably, the means for making the seed crystal and the shell of the shell mold set in gapless contact is:

[0012] When preparing the wax mold module, a seed crystal is placed in the shell mold, and the obtained wax mold module is subjected to shell mold coating, dewaxing and sintering to obtain a shell wax mold with the seed crystal.

[0013] Preferably, the means for making the seed crystal and the shell of the shell mold set in gapless contact is:

[0014] The seed crystal cavity of the wax mold module is set to have a taper that is larger at the bottom and smaller at the top, and a seed crystal with a matching taper is placed in the seed crystal cavity before pouring.

[0015] Preferably, the taper is 1° to 5°.

[0016] Preferably, the method of pouring into the mold cavity is bottom pouring, and the outlet from the transition runner cavity into the mold cavity is located at the upper part of the transition runner cavity.

[0017] Preferably, the pouring system includes a middle cavity with a large cross-sectional area, a first cavity located at the lower part of the middle cavity and away from the mold cavity, and a second cavity located at the upper part of the middle cavity and connected to the mold cavity, the cross-sectional areas of the first cavity and the second cavity are both smaller than the cross-sectional area of ​​the middle cavity, and the first cavity, the middle cavity and the second cavity are connected.

[0018] Preferably, the length of the seed crystal is 10 mm to 20 mm.

[0019] Preferably, the length of the seed crystal is 15 to 30 mm.

[0020] Preferably, the diameter of the middle cavity is 10-15 mm, the height is 10-20 mm, the diameter of the first cavity is 1-5 mm, and the diameter of the second cavity is 1-5 mm.

[0021] Preferably, the single crystal high-temperature alloy blade is a DD3 alloy blade, a DD6 alloy blade or a DD9 alloy blade.

[0022] The present application provides a method for preparing single crystal high-temperature alloy blades with seed crystals, which first prepares a shell mold group for the single crystal high-temperature alloy blades so that the seed crystal and the shell of the shell mold group are in gapless contact, and then the shell mold group is placed on a water-cooled crystallizer. After the shell mold group is heated, the single crystal high-temperature alloy liquid is poured into the mold cavity through the transition runner cavity of the pouring system to reduce the speed at which the single crystal high-temperature alloy liquid enters the mold cavity, and the high-temperature alloy blade is obtained after directional solidification; in the process of preparing the single crystal high-temperature alloy blades with seed crystals, in the shell mold group, the seed crystal and the shell of the shell mold group are in gapless contact, the gap between the seed crystal and the shell is eliminated, and the seeding defects caused by the gap are avoided. At the same time, by introducing the transition runner, the disturbance of the single crystal high-temperature alloy liquid on the partially melted mushy zone of the seed crystal is significantly reduced, thereby avoiding the problem of dendrite breakage in the mushy zone of the seed crystal caused by the momentum introduced by pouring, significantly improving the seed crystal seeding success rate, reducing seeding defects, and improving the success rate of single crystal high-temperature alloy blade preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of placing seed crystals to prepare single crystal blades when preparing a wax mold module before coating of the present invention;

[0024] Figure 2 This is a schematic diagram of a mold shell using a conical seed crystal cavity in the present invention;

[0025] Figure 3 This is a schematic diagram of the present invention using conical seed crystal directional solidification to prepare blades;

[0026] Among them, 1 is the runner system; 2 is the seed crystal; 3 is the mold shell; 4 is the mold cavity; 5 is the water-cooled crystallizer; 1-1 is the runner, 1-2 is the first cavity, 1-3 is the middle cavity, and 1-4 is the second cavity. DETAILED DESCRIPTION

[0027] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0028] In the preparation of single crystal blades, the seed crystal process is an important method of seeding. During the directional solidification process, at the high temperature of directional solidification, the seed crystal is partially melted back, and the seed crystal surrounded by the shell is partially not melted back due to the strong cooling effect of the water-cooled crystallizer; the seed crystal part that is not melted back serves as the base to become the core of the single crystal growth, thereby growing into a single crystal. However, at the interface between the seed crystal and the shell and in the mushy area between the melted back and the non-melted back, it is easy to generate impurities, resulting in the failure of seeding; the crushing or deflection of dendrites in the mushy area where the seed crystal is partially melted back can also cause the failure of seeding. In response to the above problems, the present application provides a method for preparing single crystal high-temperature alloy blades by seed crystals, which eliminates the gap between the seed crystal and the shell by introducing a gapless contact between the seed crystal and the shell mold, and at the same time introduces a transition runner cavity, which reduces the external force of the single crystal high-temperature alloy liquid on the dendrites in the melted back area during the casting process, thereby significantly improving the success rate of seed crystal seeding, reducing seeding defects and even blade scrapping. The present application provides a method for preparing a single crystal high-temperature alloy blade using a seed crystal, comprising the following steps:

[0029] S1) preparing a shell mold set for a single crystal high-temperature alloy blade, so that the seed crystal and the shell of the shell mold set are in gapless contact;

[0030] S2) placing the shell mold assembly on a water-cooled crystallizer, and after the shell mold assembly is heated, pouring the single crystal high-temperature alloy liquid into the mold cavity through the transition runner cavity of the pouring system to reduce the speed at which the single crystal high-temperature alloy liquid enters the mold cavity, and obtaining the single crystal high-temperature alloy blade after directional solidification.

[0031] Usually, when the seed crystal method is adopted, a straight cylindrical seed crystal cavity is first prefabricated on the shell using a wax mold module, and then a seed crystal is placed in the cavity before pouring to prepare a single crystal blade; however, in this method, there is a gap between the side of the seed crystal and the shell, which is easy to form a crystal nucleus and cause a seeding defect. The shell mold module of the single crystal high-temperature alloy blade prepared in the present application makes the seed crystal and the shell of the shell mold module in gapless contact; in the present application, the means for the seed crystal and the shell of the shell mold module to be in gapless contact include two methods, one is: when the wax mold module is prepared, a seed crystal is placed in the shell, and the obtained wax mold module is successively subjected to shell coating, dewaxing and sintering, so that there is no gap between the shell surrounding the seed crystal and the seed crystal during the directional solidification process; the second is: the seed crystal cavity of the wax mold module is set to a taper with a large bottom and a small top, and the shell mold module is obtained after the wax model shell is coated, dewaxed and sintered, and a seed crystal with a matching taper is placed in the cavity before pouring. The taper is 1° to 5°, specifically, the taper is 1° to 2°. In the first method mentioned above, the length of the seed crystal is 10 to 20 mm, more specifically 12 to 15 mm, to ensure that the seed crystal surrounded by the mold shell at the blade directional solidification temperature is not completely melted back, and is separated from the effect of the mold shell on the mushy zone. Therefore, the mushy zone enters the mold cavity, avoiding the appearance of a mushy zone at the interface between the seed crystal and the mold shell; in the second method mentioned above, the length of the seed crystal is 15 to 30 mm, more specifically 20 to 28 mm, to ensure that the upper part of the seed crystal is completely melted back at the insulation temperature of the single crystal blade mold shell.

[0032] The elimination of the gap between the seed crystal and the side of the shell avoids the nucleation of dendrites caused by the filling of alloy liquid due to the existence of the gap in the prior art.

[0033] According to the present invention, the shell mold is then placed on a water-cooled crystallizer, and after the shell mold is heated, the single crystal high-temperature alloy liquid is poured into the mold cavity through the transition runner cavity of the pouring system; the heating is performed so that the shell mold is heated to a temperature higher than the melting point of the alloy liquid, and then the single crystal high-temperature alloy liquid is poured.

[0034] The lower part of the seed crystal surrounded by the shell is strongly cooled by the water-cooled crystallizer and is at a low temperature; while the upper part of the seed crystal is melted back by the high temperature in the cavity; inside the seed crystal, there is a temperature gradient from top to bottom. Single crystal high-temperature alloys are multi-component alloys containing multiple alloy elements. There is a melting range during the solidification process, which makes the seed crystal have a mushy area. Liquid and solid coexist in the mushy area, part of the dendrite stem is solid, and the solid dendrite stem is surrounded by liquid alloy; it is equivalent to the solid dendrite stem standing upright in the liquid alloy. When the liquid phase flows, it generates a flushing force on the dendrite stem. When the force exceeds a certain level, it causes the dendrite stem to break. The broken dendrite stem will become the core, and the core grows into a miscellaneous crystal, resulting in the failure of seeding.

[0035] Therefore, in order to avoid the fracture of dendrites, the momentum of the molten metal poured into the mold cavity needs to be as small as possible. The present application introduces a transition runner cavity in the pouring system to reduce the external force of the alloy liquid on the dendrites in the remelting zone during the pouring process, and minimizes the momentum of the alloy liquid poured into the mold cavity when it reaches the vicinity of the seed crystal, so that the scouring effect of the poured alloy liquid on the seed crystal can be ignored, and the dendrite stem in the remelting mushy zone of the seed crystal remains stable under the action of small momentum.

[0036] The transition runner cavity is filled with single crystal high temperature alloy liquid bottom pouring, and the outlet from the transition runner cavity into the mold cavity is located at the upper part of the transition runner cavity. Furthermore, in order to minimize the effect of pouring the alloy liquid into the mold cavity, the setting of the transition runner cavity is as follows: Figure 1 , Figure 2 and Figure 3 As shown, an intermediate cavity 1-3 with a large cross-sectional area is introduced on the inner gate entering the cavity, a first cavity 1-2 located at the lower part of the intermediate cavity 1-3 and away from the cavity, and a second cavity 1-4 located at the upper part of the intermediate cavity 1-3 and connected to the cavity, and the cross-sectional areas of the first cavity 1-2 and the second cavity 1-4 are both smaller than the cross-sectional area of ​​the intermediate cavity 1-5; the momentum of the alloy liquid entering the second cavity 1-4 from the intermediate cavity 1-3 is dissipated, and the speed becomes very small, thereby reducing the external force of the alloy liquid on the dendrites in the remelting zone during the pouring process. The diameter of the intermediate cavity is 10-15mm, the height is 10-20mm, the diameter of the first cavity is 1-5mm, and the diameter of the second cavity is 1-5mm; more specifically, the diameter of the intermediate cavity is 12-14mm, the height is 15-18mm, the diameter of the first cavity is 3-5mm, and the diameter of the second cavity is 3.5-5mm.

[0037] After the improvement of the above-mentioned means, during the directional solidification process, at the high temperature of directional solidification, part of the seed crystal 2 is melted back, and the seed crystal surrounded by the shell is not melted back at all due to the strong cooling effect of the water-cooled crystallizer and is not disturbed by the pouring alloy liquid. The unmelted seed crystal part serves as the base and becomes the core of the single crystal growth, thereby growing into a single crystal blade.

[0038] The method provided in the present application is applicable to the preparation of single crystal high-temperature alloy blades currently known to those skilled in the art. For example, the single crystal high-temperature alloy blades are DD3 alloy blades, DD6 alloy blades or DD9 alloy blades.

[0039] In order to further understand the present invention, the method for preparing single crystal high-temperature alloy blades from seed crystals provided by the present invention is described in detail below in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0040] Example 1

[0041] Method for preparing single crystal high temperature alloy blade DD6 based on static stable seed crystal:

[0042] When preparing the wax mold module, a seed crystal 2 is placed, and then the single crystal wax mold module with the seed crystal is coated, dewaxed, and sintered to obtain a mold shell 3 inlaid with the seed crystal 2, and the length of the seed crystal in the mold shell is 15 mm;

[0043] An intermediate cavity 1-3 with a larger cross-sectional area is introduced into the inner gate entering the cavity. The diameter of 1-3 is 12mm and the height is 15mm. The inner gate is divided into two parts: the first cavity 1-2 and the second cavity 1-4. The diameter of the first cavity 1-2 is 3mm, and the diameter of the second cavity 1-4 is 3.5mm. The first cavity 1-2 is located at the lower part of the intermediate cavity 1-3, and the second cavity 1-4 connected to the cavity is located at the upper part of the intermediate cavity 1-3. Figure 1 As shown; the DD3 alloy liquid enters the first cavity 1-2 from the runner 1-1, and then enters the second cavity 1-4 from the middle cavity 1-3. The momentum of the metal liquid in the middle cavity 1-3 is dissipated, the speed becomes very small, and enters the cavity 4 for directional solidification;

[0044] During the directional solidification process, the directional solidification temperature is as low as 1500℃, which ensures that the seed crystal surrounded by the shell at the blade directional solidification temperature does not melt back at all, and is separated from the effect of the shell on the mushy zone, so that the mushy zone enters the cavity, avoiding the appearance of a mushy zone at the interface between the seed crystal and the shell, and obtaining a single crystal high-temperature alloy blade DD6 after cooling;

[0045] 200 blades were prepared by using the seed crystal seeding method, and the seeding success rate reached 96%.

[0046] Example 2

[0047] Method for preparing single crystal high temperature alloy blade DD6 based on static stable seed crystal:

[0048] When preparing the wax mold module, a seed crystal 2 is placed, and then the single crystal wax mold module with the seed crystal is coated, dewaxed, and sintered to obtain a mold shell 3 inlaid with the seed crystal 2, and the length of the seed crystal in the mold shell is 20 mm;

[0049] An intermediate cavity 1-3 with a larger cross-sectional area is introduced into the inner gate entering the cavity. The diameter of 1-3 is 12mm and the height is 15mm. The inner gate is divided into two parts: the first cavity 1-2 and the second cavity 1-4. The diameter of the first cavity 1-2 is 3mm, and the diameter of the second cavity 1-4 is 3.5mm. The first cavity 1-2 is located at the lower part of the intermediate cavity 1-3, and the second cavity 1-4 connected to the cavity is located at the upper part of the intermediate cavity 1-3. Figure 1As shown; the DD6 alloy liquid enters the first cavity 1-2 from the 1-1 runner, and then enters the second cavity 1-4 from the middle cavity 1-3. The momentum of the metal liquid in the middle cavity 1-3 is dissipated, the speed becomes very small, and enters the cavity 4 for directional solidification;

[0050] During the directional solidification process, the directional solidification temperature is as low as 1540℃, which ensures that the seed crystal surrounded by the shell at the blade directional solidification temperature does not melt back at all, and is separated from the effect of the shell on the mushy zone, so that the mushy zone enters the cavity, avoiding the appearance of a mushy zone at the interface between the seed crystal and the shell, and obtaining a single crystal high-temperature alloy blade DD6 after cooling;

[0051] 120 blades were prepared by using the seed crystal seeding method, and the seeding success rate reached 93%.

[0052] Example 3

[0053] Method for preparing single crystal high temperature alloy blade DD9 based on static stable seed crystal:

[0054] When preparing the wax mold module, a seed crystal 2 is placed, and then the single crystal wax mold module with the seed crystal is coated, dewaxed, and sintered to obtain a mold shell 3 inlaid with the seed crystal 2, and the length of the seed crystal in the mold shell is 20 mm;

[0055] An intermediate cavity 1-3 with a larger cross-sectional area is introduced into the inner gate entering the cavity. The diameter of 1-3 is 12mm and the height is 15mm. The inner gate is divided into two parts: the first cavity 1-2 and the second cavity 1-4. The diameter of the first cavity 1-2 is 3mm, and the diameter of the second cavity 1-4 is 3.5mm. The first cavity 1-2 is located at the lower part of the intermediate cavity 1-3, and the second cavity 1-4 connected to the cavity is located at the upper part of the intermediate cavity 1-3. Figure 1 As shown; the DD9 alloy liquid enters the first cavity 1-2 from the runner 1-1, and then enters the second cavity 1-4 from the middle cavity 1-3. The momentum of the metal liquid in the middle cavity 1-3 is dissipated, the speed becomes very small, and enters the cavity 4 for directional solidification;

[0056] During the directional solidification process, the directional solidification temperature is as low as 1540℃, which ensures that the seed crystal surrounded by the shell at the blade directional solidification temperature does not melt back at all, and is separated from the effect of the shell on the mushy zone, so that the mushy zone enters the cavity, avoiding the appearance of a mushy zone at the interface between the seed crystal and the shell, and obtaining a single crystal high-temperature alloy blade DD9 after cooling;

[0057] 390 blades were prepared by using the seed crystal seeding method, and the seeding success rate reached 97%.

[0058] In Example 1, the prepared blade is a second-generation single crystal high-temperature alloy blade with a low alloy melting point; and, due to the weak core and other reasons, the directional solidification temperature of the blade is as low as 1500°C, the length of the seed crystal in the shell is 15mm, and during the directional solidification process, the seed crystal buried in the shell does not melt back at all and remains in a solid state; in order to ensure a good seeding effect, the upper part of the seed crystal needs to be melted back, and the length of the seed crystal is 25mm.

[0059] In Example 2, the prepared blade is a third-generation single crystal high-temperature alloy blade with a high alloy melting point; and the blade shape is simple. In order to obtain a higher single crystal qualified rate, the blade directional solidification temperature reaches 1600°C, and the length of the seed crystal in the shell is 10mm. During the directional solidification process, the seed crystal buried in the shell does not melt back at all and remains in a solid state; in order to ensure a good crystal induction effect, the upper part of the seed crystal needs to be melted back, and the length of the seed crystal is 20mm.

[0060] In Example 3, the prepared single crystal alloy has a high melting point and a complex blade shape. The blade directional solidification temperature reaches 1500°C, and the length of the seed crystal in the mold shell is 20 mm. During the directional solidification process, the seed crystal buried in the mold shell does not melt back at all and remains in a solid state. In order to ensure a good seeding effect, the upper part of the seed crystal needs to be melted back. The length of the seed crystal is 30 mm.

[0061] Example 4

[0062] Method for preparing single crystal high temperature alloy blade DD6 based on static stable seed crystal:

[0063] At the bottom of the blade wax mold, a wax strip with a taper of 2° is prepared or a ceramic tube with an internal cavity taper of 2° is added, and a plurality of wax molds and a pouring system are welded to prepare a wax mold module, and the obtained wax mold module is successively subjected to shell coating, dewaxing and sintering, and a seed crystal cavity with a taper of 2° is formed at the lower part of the shell, and the lower diameter of the seed crystal cavity is 3mm and the length is 20mm; a seed crystal with a taper of 2°, a large end diameter of 2.9mm and a length of 25mm is placed from the lower part of the seed crystal cavity, and the taper side of the seed crystal is closely fitted with the seed crystal cavity, and then the cross section of the seed crystal cavity is filled with ceramic slurry, so that the seed crystal is firmly placed in the seed crystal cavity; then the shell mold module is placed on a water-cooled crystallizer, and after the shell mold module is heated, the single crystal high-temperature alloy liquid is poured into the mold cavity through the transition runner cavity of the pouring system; the heating is performed so that the shell mold module is heated to a temperature above the melting point of the alloy liquid, and then the single crystal high-temperature alloy liquid is poured;

[0064] An intermediate cavity 1-3 with a larger cross-sectional area is introduced into the inner gate entering the cavity. The diameter of 1-3 is 12mm and the height is 15mm. The inner gate is divided into two parts: the first cavity 1-2 and the second cavity 1-4. The diameter of the first cavity 1-2 is 3mm, and the diameter of the second cavity 1-4 is 3.5mm. The first cavity 1-2 is located at the lower part of the intermediate cavity 1-3, and the second cavity 1-4 connected to the cavity is located at the upper part of the intermediate cavity 1-3. Figure 1 As shown; the DD6 alloy liquid enters the first cavity 1-2 from the 1-1 runner, and then enters the second cavity 1-4 from the middle cavity 1-3. The momentum of the metal liquid in the middle cavity 1-3 is dissipated, the speed becomes very small, and enters the cavity 4 for directional solidification;

[0065] Due to reasons such as the blade structure, the directional solidification temperature is as low as 1500°C, and the length of the seed crystal in the mold shell is 15mm. During the directional solidification process, the seed crystal buried in the mold shell does not melt back at all and remains in a solid state. In order to ensure a good seeding effect, the upper part of the seed crystal needs to be melted back, and the length of the seed crystal is 25mm.

[0066] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0067] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a single crystal high temperature alloy blade from a seed crystal, comprising the following steps: S1) preparing a shell mold set for a single crystal high-temperature alloy blade, so that the seed crystal and the shell of the shell mold set are in gapless contact; S2) placing the shell mold assembly on a water-cooled crystallizer, and after the shell mold assembly is heated, pouring the single crystal high-temperature alloy liquid into the mold cavity through the transition runner cavity of the pouring system to reduce the speed at which the single crystal high-temperature alloy liquid enters the mold cavity, and obtaining the single crystal high-temperature alloy blade after directional solidification.

2. The method according to claim 1, characterized in that The means for making the seed crystal and the shell of the shell mold set in gapless contact is: When preparing the wax mold module, a seed crystal is placed in the shell mold, and the obtained wax mold module is subjected to shell mold coating, dewaxing and sintering to obtain a shell wax mold with the seed crystal.

3. The method according to claim 1, characterized in that The means for making the seed crystal and the shell of the shell mold set in gapless contact is: The seed crystal cavity of the wax mold module is set to have a taper that is larger at the bottom and smaller at the top, and a seed crystal with a matching taper is placed in the seed crystal cavity before pouring.

4. The method according to claim 3, characterized in that The taper is 1° to 5°.

5. The method according to claim 1, characterized in that The method of pouring into the cavity is bottom pouring, and the outlet from the transition runner cavity into the cavity is located at the upper part of the transition runner cavity.

6. The method according to claim 5, characterized in that The pouring system includes a middle cavity with a large cross-sectional area, a first cavity located at the lower part of the middle cavity and away from the mold cavity, and a second cavity located at the upper part of the middle cavity and connected to the mold cavity. The cross-sectional areas of the first cavity and the second cavity are both smaller than the cross-sectional area of ​​the middle cavity, and the first cavity, the middle cavity and the second cavity are connected.

7. The method according to claim 2, characterized in that The length of the seed crystal is 10 mm to 20 mm.

8. The method according to claim 3, characterized in that The length of the seed crystal is 15 to 30 mm.

9. The method according to claim 5, characterized in that The diameter of the middle cavity is 10-15 mm, and the height is 10-20 mm. The diameter of the first cavity is 1-5 mm, and the diameter of the second cavity is 1-5 mm.

10. The method according to any one of claims 1 to 9, characterized in that: The single crystal high temperature alloy blade is a DD3 alloy blade, a DD6 alloy blade or a DD9 alloy blade.

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