Modified cast high-temperature alloy with high fluidity and low porosity defect and preparation method

Abstract

The invention belongs to the technical field of isometric crystal superalloy casting, and discloses a modified cast superalloy with high fluidity and low porosity defect and a preparation method thereof, the preparation method comprises the following steps: smelting and refining an additive and an unmodified superalloy in a vacuum induction smelting furnace to obtain the modified cast superalloy; the additive comprises a Ni-Mg intermediate alloy; the unmodified high-temperature alloy comprises an unmodified I N792 nickel-based cast high-temperature alloy. Wherein the modified cast high-temperature alloy comprises Mg with the mass percent of 0.004%-0.01%. In order to solve the problems that in the production process of a complex-structure casting of an aero-engine, mold filling is difficult, the number of internal loose defects is large and the like, the modified cast high-temperature alloy is prepared by adding Mg elements with different contents, the alloy fluidity is improved, the loose defects of the alloy casting are reduced, and the casting performance of the alloy casting is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of equiaxed crystal high-temperature alloy casting, and specifically relates to a modified casting high-temperature alloy with high fluidity and low porosity defects and a preparation method thereof. Background Art

[0002] In aircraft engines, complex structural castings such as high-temperature alloy casings carry important loads of aircraft engines and provide the main thrust. The quality of casting molding directly affects the performance, life and reliability of aircraft engines. With the requirements for high performance, high reliability and structural weight reduction of aircraft engines, complex structural castings such as centrifugal impellers are gradually developing towards integration, thin-walling and dimensional precision, which leads to problems such as difficulty in filling and many internal loose defects in the production process of complex structural parts, resulting in the current situation of high cost and low quality of complex structural parts, which seriously affects the production efficiency and service life of castings.

[0003] Therefore, a modified casting high temperature alloy and a preparation method are provided to improve the alloy filling capacity and reduce the internal loose defects of the casting. Summary of the invention

[0004] In view of the problems in the prior art that complex structural parts are prone to difficulty in filling and many internal porosity defects during the production process, the purpose of the present invention is to provide a modified casting high-temperature alloy with high fluidity and low porosity defects and a preparation method, which improves the alloy's filling capacity and reduces internal porosity defects in castings.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a modified cast high-temperature alloy having high fluidity and low porosity defects, the preparation method comprising:

[0007] The additive and the unmodified high-temperature alloy are placed in a vacuum induction melting furnace for melting and refining to obtain a modified casting high-temperature alloy;

[0008] The additive includes Ni-Mg master alloy;

[0009] The unmodified high temperature alloy includes unmodified IN792 nickel-based casting high temperature alloy.

[0010] In the present invention, the distribution coefficient of the Mg element during the solidification process is much less than 1, and it is a serious solidification segregation element. Mg is an element with a large atomic radius and has a low solid solubility in the matrix of the nickel-based cast high-temperature alloy. It is mainly segregated at phase boundaries and grain boundaries to form compounds with S, avoiding the harm of forming low-melting-point sulfide eutectics.

[0011] In the present invention, the atomic radius of the Mg element is relatively large, so it is difficult for the Mg atom to enter the octahedral gap of the face-centered cubic structure γ dendrite. Therefore, the appropriate amount of Mg element content reduces the mobility of atoms between the liquid and solid phases, reduces the growth rate of the γ dendrite, and increases the dendrite overlap time, thereby improving the fluidity of the modified high-temperature alloy.

[0012] In the present invention, the carbides in the cast alloy of I N792 nickel-based cast high-temperature alloy are mainly MC carbides (Ti C, TaC). The addition of Mg element will change the segregation of other elements such as Ti and Ta to the interdendritic space, promote the increase of the size of the interdendritic MC carbides, thereby occupying the interdendritic loose formation position and reducing the loose defects of the alloy.

[0013] The invention prepares a modified casting high-temperature alloy by adding Mg elements of different contents, thereby improving the fluidity of the alloy, reducing the loose defects of the alloy casting, and improving the casting performance of the alloy casting.

[0014] As a preferred technical solution of the present invention, the vacuum pressure of the vacuum induction melting furnace for melting is set at 1×10 -2 MPa~6×10 -2 MPa, for example, 1×10 -2 MPa, 2×10 -2 MPa, 3×10 -2 MPa, 4×10 -2 MPa, 5×10 -2 MPa or 6×10 -2 MPa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] As a preferred technical solution of the present invention, the temperature for refining in the vacuum induction melting furnace is 1400°C to 1450°C, for example, it can be 1400°C, 1410°C, 1420°C, 1430°C, 1440°C or 1450°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] As a preferred technical solution of the present invention, the refining time using the vacuum induction melting furnace is 1 min to 7 min, for example, it can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min or 7 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] In a second aspect, the present invention provides a modified cast high-temperature alloy with high fluidity and low porosity defects obtained by the preparation method described in the first aspect, wherein the modified cast high-temperature alloy includes Cr, Co, Mo, W, Al, Ti, C, Ta, B, Mg, Ni, and impurities.

[0018] As a preferred technical solution of the present invention, in the modified cast high-temperature alloy, the mass percentage of Mg is 0.004% to 0.01%, by mass percentage, for example, it can be 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Exemplarily, the present invention provides a method for preparing a modified cast high-temperature alloy with high fluidity and low porosity defects, the preparation method comprising the following steps:

[0020] (1) According to the required content of Mg component in the modified cast high-temperature alloy, the Ni-Mg master alloy and the unmodified IN792 nickel-based cast high-temperature alloy are weighed and proportioned;

[0021] (2) When melting, the unmodified IN792 nickel-based cast high-temperature alloy is first placed in a vacuum induction melting furnace for melting. The vacuum pressure of the melting is set at 1×10 -2 MPa~6×10 -2 MPa, electromagnetic stirring is used in the smelting process, and when the unmodified IN792 nickel-based casting high-temperature alloy is completely melted, the Ni-Mg intermediate alloy is added into the unmodified IN792 nickel-based casting high-temperature alloy through the charging bin of the vacuum induction melting furnace according to the mass ratio of the unmodified IN792 nickel-based casting high-temperature alloy to the Ni-Mg intermediate alloy of 2500:4-10 for refining to obtain the modified casting high-temperature alloy, the refining temperature is 1400°C-1450°C, and the refining time is 1min-7min.

[0022] Beneficial effects of the present invention:

[0023] 1. Prepare modified high-temperature alloys by adding different contents of Mg elements, improve alloy fluidity, reduce the loose defects of alloy castings, and improve the casting properties of alloy castings;

[0024] 2. Specifically, the distribution coefficient of Mg in the solidification process is much less than 1, and it is a serious solidification segregation element. Moreover, Mg is an element with a large atomic radius and has a low solid solubility in the matrix of nickel-based cast high-temperature alloys. It mainly segregates at phase boundaries and grain boundaries to form compounds with S, avoiding the harm of forming low-melting-point sulfide eutectics;

[0025] 3. Specifically, the atomic radius of the Mg element is relatively large, which makes it difficult for Mg atoms to enter the octahedral gap of the face-centered cubic structure γ dendrite. Therefore, the appropriate amount of Mg element content reduces the mobility of atoms between the liquid and solid phases, reduces the growth rate of the γ dendrite, and increases the time of dendrite overlap, thereby improving the fluidity of the modified casting high-temperature alloy;

[0026] 4. Specifically, in I N792 nickel-based cast high-temperature alloy, the carbides in the cast alloy are mainly MC carbides (Ti C, TaC), and the addition of Mg element will change the segregation of other elements such as Ti and Ta to the interdendritic space, promote the increase of the size of interdendritic MC carbides, thereby occupying the interdendritic loose formation position and reducing the alloy loose defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings;

[0028] Figure 1 This is a diagram showing the actual results of the fluidity test of the comparative example of the present invention;

[0029] Figure 2 This is a diagram showing the actual results of the fluidity test of Example 1 of the present invention;

[0030] Figure 3 This is a diagram showing the actual results of the fluidity test of Example 2 of the present invention;

[0031] Figure 4 This is a diagram showing the actual results of the fluidity test of Example 3 of the present invention;

[0032] Figure 5 The metallographic diagram of the loose defects in the upper, middle and lower parts of the real object obtained in the comparative example of the present invention;

[0033] Figure 6 The metallographic image of the loose defects in the upper, middle and lower parts of the object obtained in Example 1 of the present invention;

[0034] Figure 7 The metallographic image of the loose defects in the upper, middle and lower parts of the actual object obtained in Example 2 of the present invention;

[0035] Figure 8 This is a metallographic diagram of the loose defects in the upper, middle and lower parts of the actual object obtained in Example 3 of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments recorded herein are specific embodiments of the present invention, which are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limitations on the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments recorded herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments recorded herein.

[0037] Alloy fluidity and porosity defects are closely related to alloy composition, thermophysical parameters, temperature and other factors. The strength of alloy fluidity is directly related to the filling capacity of castings, and porosity defects will have a certain impact on the mechanical properties of alloys. Both of them jointly affect the molding quality of alloy castings, the production qualification rate of large and complex structural parts, and the service life.

[0038] At present, under the current situation that casting process parameters are not easy to change, the casting properties of alloys can be improved to a certain extent by changing the alloy composition and its content. However, due to the excessive composition of high-temperature alloys, changing the main alloy elements has a greater impact on the alloy structure and mechanical properties. Therefore, selecting appropriate trace elements and regulating the content of trace elements are of great engineering significance for improving alloy fluidity, reducing loose defects, and improving the quality of castings.

[0039] In the following examples and comparative examples, the present invention selects unmodified IN792 nickel-based casting high-temperature alloy, and prepares modified high-temperature alloys by adding different contents of Mg elements, and studies how to improve the fluidity of the nickel-based casting high-temperature alloy, reduce the loose defects, and thus improve the casting performance of the casting. It should be noted that the unmodified IN792 nickel-based casting high-temperature alloy selected by the present invention is only to illustrate that the method disclosed in the present invention can improve the casting performance of IN792 nickel-based casting high-temperature alloy by adding different Mg contents. For unmodified IN792 nickel-based casting high-temperature alloys composed of other component contents, the casting performance of IN792 can also be improved by this method.

[0040] Example 1

[0041] This embodiment provides a method for preparing a modified cast high-temperature alloy with high fluidity and low porosity defects, comprising:

[0042] (1) The mass percentage of Mg component in the modified cast high-temperature alloy is 0.004%. According to this mass percentage, the Ni-Mg master alloy and the unmodified IN792 nickel-based cast high-temperature alloy are weighed and mixed;

[0043] (2) When melting, the unmodified IN792 nickel-based cast high-temperature alloy is first placed in a vacuum induction melting furnace for melting. The vacuum pressure of the melting is set at 5×10 -2 MPa, electromagnetic stirring is used in the smelting process. When the unmodified IN792 nickel-based casting high-temperature alloy is completely melted, the Ni-Mg intermediate alloy is added into the unmodified IN792 nickel-based casting high-temperature alloy through the charging bin of the vacuum induction melting furnace for refining. The refining temperature is 1450℃ and the refining time is 3min to obtain the modified casting high-temperature alloy.

[0044] In this embodiment, the obtained modified cast high-temperature alloy includes 0.004% by mass of Mg. The alloy component contents of the modified cast high-temperature alloy are shown in Table 1.

[0045] Table 1

[0046]

[0047] Example 2

[0048] This embodiment provides a method for preparing a modified cast high-temperature alloy with high fluidity and low porosity defects, comprising:

[0049] (1) The mass percentage of Mg component in the modified cast high-temperature alloy is 0.007%. According to this mass percentage, the Ni-Mg master alloy and the unmodified IN792 nickel-based cast high-temperature alloy are weighed and mixed;

[0050] (2) When melting, the unmodified IN792 nickel-based cast high-temperature alloy is first placed in a vacuum induction melting furnace for melting. The vacuum pressure of the melting is set at 5×10 -2 MPa, electromagnetic stirring is used in the smelting process. When the unmodified IN792 nickel-based casting high-temperature alloy is completely melted, the Ni-Mg intermediate alloy is added into the unmodified IN792 nickel-based casting high-temperature alloy through the charging bin of the vacuum induction melting furnace for refining. The refining temperature is 1450℃ and the refining time is 3min to obtain the modified casting high-temperature alloy.

[0051] In this embodiment, the obtained modified cast high-temperature alloy includes 0.007% by mass of Mg. The alloy component contents of the modified cast high-temperature alloy are shown in Table 2.

[0052] Table 2

[0053]

[0054] Example 3

[0055] This embodiment provides a method for preparing a modified cast high-temperature alloy with high fluidity and low porosity defects, comprising:

[0056] (1) The mass percentage of Mg component in the modified cast high-temperature alloy is 0.01%. According to this mass percentage, the Ni-Mg master alloy and the unmodified 1 N792 nickel-based cast high-temperature alloy are weighed and prepared;

[0057] (2) When melting, the unmodified IN792 nickel-based cast high-temperature alloy is first placed in a vacuum induction melting furnace for melting. The vacuum pressure of the melting is set at 5×10 -2 MPa, electromagnetic stirring is used in the smelting process. When the unmodified IN792 nickel-based casting high-temperature alloy is completely melted, the Ni-Mg intermediate alloy is added into the unmodified IN792 nickel-based casting high-temperature alloy through the charging bin of the vacuum induction melting furnace for refining. The refining temperature is 1450℃ and the refining time is 3min to obtain the modified casting high-temperature alloy.

[0058] In this embodiment, the obtained modified cast high-temperature alloy includes Mg in an amount of 0.01% by mass. The alloy component contents of the modified cast high-temperature alloy are shown in Table 3.

[0059] Table 3

[0060]

[0061] Comparative Example

[0062] This comparative example provides a method for preparing a high-temperature alloy. The difference from Example 1 is that no Ni-Mg intermediate alloy is added to obtain an unmodified I N792 nickel-based casting high-temperature alloy, and its alloy composition is shown in Table 4.

[0063] Table 4

[0064]

[0065] The modified cast high temperature alloys prepared in Examples 1 to 3 and the comparative example and the unmodified 1 N792 nickel-based cast high temperature alloy were subjected to fluidity test and porosity defect statistics. The methods of fluidity test and porosity defect statistics are as follows:

[0066] (1) Liquidity test

[0067] After heating a spiral flowable mold with a spiral section thickness of 3 mm and a height of 10 mm to 910°C and keeping it warm for 12 hours, the test product (the modified cast high-temperature alloy prepared by Examples 1 to 3 and the comparative example and the unmodified I N792 nickel-based cast high-temperature alloy, the main difference between which is the different Mg content) is placed in a vacuum induction melting furnace for smelting. After the high-temperature alloy is completely melted, it is refined at 1450°C for 3 minutes, and then the test product is cooled to 1410°C, and the melted test product is poured into the preheated spiral flowable mold at a pouring rate of 0.5 Kg / s. After the alloy liquid is naturally cooled to room temperature, the spiral alloy test sample is taken out, and its streamline length is measured to determine its flow performance. This method mainly characterizes its flowability by the streamline length of the alloy liquid in the spiral section after solidification.

[0068] The fluidity test results of each embodiment and comparative example are shown in Table 5.

[0069] Table 5

[0070]

[0071] As can be seen from Table 5, the present invention prepares a modified cast high-temperature alloy by adding different Mg element contents. Compared with the unmodified I N792 nickel-based cast high-temperature alloy, when the Mg element is added to 0.01%, the fluidity of the modified cast high-temperature alloy is improved by 33% compared with the fluidity of the unmodified I N792 nickel-based cast high-temperature alloy.

[0072] (2) Loose defect statistics

[0073] After heating the alloy mechanical properties test bar mold to 910°C and keeping it warm for 12 hours, the test product (the modified cast high-temperature alloy prepared by Examples 1 to 3 and the comparative example and the unmodified I N792 nickel-based cast high-temperature alloy, the main difference between which is the different Mg content) is placed in a vacuum melting furnace for melting. After the test product is completely melted, it is refined at 1450°C for 3 minutes and then cooled to 1410°C. The melted test product is poured into the preheated test bar mold. After the mold is naturally cooled to room temperature after the alloy liquid is poured, the test bar mold is knocked open, and samples are taken at three positions: the upper part, the middle part, and the lower part of the test bar. Then, the sample is prepared and the loose defects are counted to determine the loose defects.

[0074] The fluidity test results of each embodiment and comparative example are shown in Table 6.

[0075] Table 6

[0076]

[0077] It can be seen from Table 6 that the modified cast high-temperature alloy prepared by adding different Mg element contents in the present invention, compared with the unmodified IN792 nickel-based cast high-temperature alloy, when the Mg content is 0.004% and 0.007%, the loose area percentage of the modified cast high-temperature alloy is reduced by 50%; especially when the Mg content is 0.01%, the loose area percentage of the modified cast high-temperature alloy is 0.04%, and the loose content is the lowest.

[0078] The IN792 high-temperature alloy is modified by adding different Mg element contents to change the fluidity and loose defects of the IN792 high-temperature alloy. The main points are as follows:

[0079] The reason why the flow of IN792 nickel-based cast high-temperature alloy stops is that it grows in the form of dendrites during the solidification process of the alloy. As the temperature decreases, the viscosity of the alloy liquid increases and the flow rate of the alloy liquid decreases. When the dendrites in the IN792 nickel-based cast high-temperature alloy overlap each other to form a continuous dendrite network and the remaining alloy liquid's own pressure cannot overcome the resistance of the dendrite network, the flow of the IN792 nickel-based cast high-temperature alloy stops. At the same time, when the alloy dendrites overlap to form a microscopic molten pool, as the temperature decreases, the alloy liquid in the microscopic molten pool solidifies and shrinks, and the subsequent liquid phase cannot supplement the microscopic molten pool, thereby forming a loose defect. Therefore, delaying the dendrite overlap time of IN792 nickel-based cast high-temperature alloy can effectively improve the flowability of the alloy and reduce the loose defects of alloy castings.

[0080] Alloy viscosity refers to the frictional resistance caused by the relative movement of molecules inside the melt, which affects the fluidity of the alloy. As the temperature decreases, the viscosity of the alloy melt increases, the fluidity of the alloy decreases, and the shrinkage compensation capacity decreases. At the same temperature, the greater the alloy viscosity, the greater the resistance to the fluidity of the high-temperature alloy, thereby reducing the fluidity of the high-temperature alloy.

[0081] Due to the difference between the physical structure of Mg atoms and the matrix properties such as atomic mass and atomic radius, the viscosity of the alloy decreases with the increase of Mg content; at the same time, Mg can reduce the diffusion barrier of atomic binding energy in the melt. When the melt solidifies, it becomes looser, which effectively reduces the viscosity of the alloy melt, thereby improving the fluidity and shrinkage compensation ability of the modified IN792 nickel-based casting high-temperature alloy.

[0082] The solidification temperature range of the alloy also has a certain degree of influence on the flowability of the alloy. For alloys with a narrow crystallization temperature range, the alloy tends to solidify layer by layer, and the effect of the latent heat of crystallization can be fully exerted. The release of the latent heat of crystallization can reduce the solidification rate and prolong the solidification time, thereby improving the fluidity of the alloy.

[0083] Table 7 is the solidification temperature range test results of each embodiment and comparative example.

[0084]

[0085] As shown in Table 7, after the addition of Mg element, the solidification temperature range of the alloy shows a trend of first increasing and then decreasing. For the I N792 nickel-based cast high-temperature alloy with a modified Mg content of 0.01%, its solidification temperature range is lower than that of the other two embodiments and the comparative example, so its flowability is the longest; when the modified Mg content is 0.004%, the solidification temperature range is the largest, so the flowability is the shortest. The solidification temperature range and viscosity affect each other to form the test results.

[0086] Therefore, increasing the Mg content in IN792 nickel-based casting high-temperature alloy to 0.01% can improve the alloy fluidity and reduce the alloy porosity defects to meet the needs of advanced aero-engine castings.

[0087] The formation of porosity defects is mainly caused by insufficient shrinkage compensation of the liquid phase between dendrites in the late stage of solidification. In the late stage of alloy solidification, the primary dendrites have grown and formed, and the space between the two primary dendrite arms is still in the liquid phase. As the temperature decreases, the liquid phase between the dendrites solidifies and shrinks. Due to the existence of pressure drop, the liquid phase on the upper part of the mold shell is affected by resistance such as viscosity, resulting in insufficient shrinkage compensation and the formation of porosity defects. The factors affecting the formation of porosity defects can be expressed by the following formula:

[0088]

[0089] In formula (1), ΔP* represents the porosity formation tendency; μ is the alloy viscosity; β is the alloy solidification shrinkage rate; n is the number of inner diameters per unit area; ΔT is the solidification temperature range; G is the temperature gradient of the mushy zone; and dfs / dt is the average solidification rate during solidification.

[0090] ΔP* indicates the formation trend of loose defects. The smaller the value, the smaller the formation trend of loose defects. With the increase of Mg content in the modified I N792 nickel-based casting high-temperature alloy, the viscosity of the alloy is Figures 5 to 8 As shown in the figure, the viscosity shows a decreasing trend at the same temperature, so the tendency of porosity defects is reduced, and when the Mg content in the modified I N792 nickel-based casting high-temperature alloy is 0.01%, the solidification temperature range is the smallest, which makes the value of ΔP* the smallest and the porosity defects the least.

[0091] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing a modified cast high-temperature alloy with high fluidity and low porosity defects, characterized in that: The preparation method comprises: The additive and the unmodified high-temperature alloy are placed in a vacuum induction melting furnace for melting and refining to obtain a modified casting high-temperature alloy; The additive includes a Ni-Mg master alloy; The unmodified high temperature alloy includes unmodified IN792 nickel-based casting high temperature alloy.

2. The method for preparing a modified cast high-temperature alloy with high fluidity and low porosity defects according to claim 1, characterized in that: The vacuum pressure of the vacuum induction melting furnace for melting is set at 1×10 -2 MPa~6×10 -2 Between MPa.

3. The method for preparing a modified cast high-temperature alloy with high fluidity and low porosity defects according to claim 1, characterized in that: The temperature for refining in the vacuum induction melting furnace is 1400°C to 1450°C.

4. The method for preparing a modified cast high-temperature alloy with high fluidity and low porosity defects according to claim 3, characterized in that: The refining time using the vacuum induction melting furnace is 1 min to 7 min.

5. The method for preparing a modified cast high-temperature alloy with high fluidity and low porosity defects according to claim 1, characterized in that: Before smelting, the Ni-Mg master alloy and the unmodified IN792 nickel-based casting high-temperature alloy were weighed and proportioned according to the required content of the Mg component in the modified high-temperature casting alloy.

6. The method for preparing a modified cast high-temperature alloy with high fluidity and low porosity defects according to claim 5, characterized in that: During smelting, an unmodified IN792 nickel-based cast high-temperature alloy is first placed in a vacuum induction melting furnace for smelting, and electromagnetic stirring is used in the smelting process. When the unmodified IN792 nickel-based cast high-temperature alloy is completely melted, the Ni-Mg intermediate alloy is added to the unmodified IN792 nickel-based cast high-temperature alloy through a charging bin of the vacuum induction melting furnace according to a mass ratio of the unmodified IN792 nickel-based cast high-temperature alloy to the Ni-Mg intermediate alloy of 2500:4-10 for refining to obtain a modified cast high-temperature alloy.

7. A modified cast high-temperature alloy having high fluidity and low porosity defects obtained by the preparation method according to any one of claims 1 to 6, characterized in that: In terms of mass percentage, the mass percentage of Mg is 0.004% to 0.01%.

8. A modified cast high temperature alloy with high fluidity and low porosity defects according to claim 7, characterized in that: The components of the modified casting high-temperature alloy include Cr, Co, Mo, W, Al, Ti, C, Ta, B, Mg, and Ni.

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