A method for producing a master alloy by powder remelting of a nickel-based superalloy

Abstract

The application discloses a method for preparing a master alloy by recycling a nickel-based high-temperature alloy powder return material, and belongs to the technical field of recycling of return materials in a powder metallurgy process. The method comprises the following steps: a double-layer composite metal foil bag is used to composite package the powder-state return material; the packaged powder-state return material is put into a smelting crucible to perform smelting; after the smelting is completed, refining is performed; the refined melt is cooled to a pouring temperature and then subjected to three-stage filtration treatment; and the filtered melt is poured into a steel mold to obtain a master alloy ingot. The master alloy ingot prepared by the method has low gas element content, short smelting time, high efficiency, low cost and meets the requirements of large-scale application.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling returned materials in a powder metallurgy process, and particularly relates to a method for preparing a master alloy by remelting and recycling nickel-based high-temperature alloy powder. Background Art

[0002] Nickel-based high-temperature alloy powder prepared by argon atomization has important applications in the manufacture of advanced aero-engine powder turbine disks, but its particle size distribution exhibits a log-normal distribution characteristic, resulting in significant material waste in actual production.

[0003] Currently, only fine powder sieved between 20-60μm can be utilized in industrial production, with a yield of only about 60%. Approximately 40% of coarse powder remains unused due to inability to directly utilize it. With my country's aviation engine industry's annual demand for high-temperature alloy powder exceeding 100 tons, the accumulation of unused coarse powder not only wastes resources but also significantly increases the cost of turbine disc manufacturing.

[0004] Technical efforts to recycle coarse powder have faced two bottlenecks in traditional vacuum melting processes: First, the fine particle size of nickel-based superalloy powder return material makes it easy for it to penetrate the sealing structure and vacuum pump during the vacuum melting furnace evacuation process, increasing the system's gas leakage rate and causing equipment damage. Second, the powder material's high specific surface area causes it to absorb large amounts of ambient gases when exposed to the environment, resulting in the enrichment of impurities such as oxygen and nitrogen on the return material's surface. Directly remelting such powder will significantly degrade the purity of the master alloy ingot, seriously threatening the metallurgical quality and service reliability of the subsequent alloy preparation.

[0005] In this context, how to effectively utilize these idle high-temperature alloy coarse powders, reduce manufacturing costs, and effectively solve the equipment compatibility and metallurgical quality control in the powder return material recycling process has become an urgent problem to be solved. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for remelting and recycling nickel-based high-temperature alloy powder to prepare a master alloy, so as to achieve efficient reuse of idle high-temperature alloy coarse powder, reduce manufacturing costs, improve metallurgical quality, and meet my country's growing demand for high-temperature alloy powder.

[0007] In order to achieve the above object, the present invention discloses the following scheme:

[0008] In a first aspect, the present invention provides a method for remelting and recovering returned nickel-based high-temperature alloy powder to prepare a master alloy, the method comprising the following steps:

[0009] Step 1. Packaging of nickel-based high-temperature alloy powder return material

[0010] The nickel-based high-temperature alloy powder return material is filled into porous nickel foil bags in batches according to the particle size. The filled porous nickel foil bags are subjected to plasma activation treatment and then composite-packaged with dense iron foil bags to obtain a packaging unit packaged by a double-layer metal foil bag. The porous nickel foil bag has a thickness of 0.2 mm, a pore diameter of 5-10 μm, and a pore density of 5000-20000 / mm 2 , the thickness of the dense iron foil bag is 0.1mm, and the length, width and height of the packaging unit are 600mm×300mm×200mm;

[0011] Step 2. Add materials and smelt

[0012] 2-1. The encapsulated unit is first put into the crucible, evacuated to 30-50Pa, and smelted under the assistance of ultrasound at a frequency of 20-50kHz and a power of 50-100kW to form a molten pool. The initial feeding amount of the encapsulated unit is 50% of the crucible capacity, the heating power of the smelting is 250-800kW, and the smelting time is 1-2h.

[0013] 2-2. The remaining encapsulated units were added to the molten pool of step 2-1 in batches and smelted until clear with the assistance of ultrasound at a frequency of 20-50kHz and a power of 50-100kW to obtain a fully molten melt. The heating power for smelting was 1250-1300kW and the smelting time was 0.5-0.8h.

[0014] Step 3. Refining

[0015] The fully molten melt was heated to 1580±10°C, vacuumed to ≤0.1 Pa, and refined for 20 minutes under stirring in an external magnetic field to obtain a refined melt;

[0016] Step 4. Three-stage filtration

[0017] After the refined melt is allowed to cool to the pouring temperature, it is filtered through a first-stage filter disc, a second-stage filter disc, and a third-stage filter element in sequence, and then the filtered melt is poured into a steel mold to obtain a mother alloy ingot. The porosity of the first-stage filter disc is 10PPI, the porosity of the second-stage filter disc is 30PPI, the third-stage filter element is a microchannel filter element with a pore size of 5μm, and the pouring temperature is 1450-1480℃.

[0018] Preferably, in step 1, the nickel-based high-temperature alloy powder return material is filled into the porous nickel foil bag in batches according to the particle size: first, the bottom of the porous nickel foil bag is filled with alloy coarse powder with a particle size of 60-150 μm, and then the alloy fine powder with a particle size of 10-20 μm is filled thereon, wherein the mass ratio of the alloy coarse powder to the alloy fine powder is 3:2.

[0019] Preferably, the plasma activation treatment in step 1 is as follows: placing the filled porous nickel foil bag in a mixed atmosphere of argon and hydrogen with a volume ratio of 9:1, a gas flow rate of 5-10 L / min, and performing plasma activation treatment for 10 minutes under a 10-15 kW plasma generator.

[0020] Preferably, the mass of the packaging unit in step 1 is 50 kg / bag.

[0021] Preferably, the crucible capacity in step 2-1 is 3000 kg; and in step 2-2, the remaining packaging units are added to the molten pool in step 2-1 in 5 batches, with the mass of the packaging units added each time being 300 kg.

[0022] Preferably, the magnetic field frequency of the external magnetic field stirring in step 3 is 50 Hz, and the magnetic induction intensity is 0.3 T.

[0023] Preferably, the primary filter disc and the secondary filter disc in step 4 are zirconia foam ceramic filter discs, and the microchannel filter element is a zirconia filter element.

[0024] In a second aspect, the present invention provides a master alloy, which is prepared according to the method described in the first aspect.

[0025] Beneficial effects of the present invention:

[0026] The present invention fills powdered return materials into metal foil bags with a double-layer composite structure in batches according to particle size, performs plasma activation treatment and packaging on the metal foil bags after filling, and then melts, refines, filters and pours the packaged powdered return materials to obtain master alloy ingots. Among them, the inner layer of the metal foil bag is a porous nickel foil bag, and the outer layer is a dense iron foil bag. Compared with nickel foil, iron foil has a higher melting point and low oxygen diffusion performance. It forms an oxygen barrier during preheating and the initial stage of smelting, which can inhibit powder oxidation, and the outer iron foil still maintains a large tensile strength at high temperature, preventing the density unevenness caused by the collapse of fine powder and reducing the breakage rate, thereby ensuring the uniformity and stability of the molten pool composition; the inner porous nickel foil realizes the release of adsorbed H2O, O2 and other gases in the plasma activation stage through the pore structure, and at the same time, with the help of capillary action, the liquid metal in the smelting process is diffused and infiltrated at a faster speed, shortening the penetration time, improving efficiency and reducing costs. Therefore, the master alloy ingot prepared by the method of the present invention has a low content of gas elements, short smelting time, high efficiency and low cost, which meets the requirements of large-scale application. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] The technical solutions of the present invention are further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely used to explain the present invention and are not intended to limit the present invention.

[0029] In the present invention:

[0030] GH4169 nickel-based high-temperature alloy powder return material: purchased from Guangdong Huaao Alloy New Materials Co., Ltd.;

[0031] GH3536 nickel-based high-temperature alloy powder return material: purchased from Guangdong Huaao Alloy New Materials Co., Ltd.;

[0032] GH4099 nickel-based high-temperature alloy powder return material: purchased from Guangdong Huaao Alloy New Materials Co., Ltd.;

[0033] Porous nickel foil: purchased from Shaanxi Zhongyan New Materials Metal Materials Co., Ltd.

[0034] Dense iron foil: purchased from Shaanxi Zhongyan New Materials Metal Materials Co., Ltd.

[0035] Other raw materials are commercially available.

[0036] Example 1: Method for Recycling and Remelting Returned GH4169 Nickel-Based High-Temperature Alloy Powder

[0037] Step 1. Packaging of nickel-based high-temperature alloy powder return material

[0038] The nickel-based high-temperature alloy powder is returned to the porous nickel foil bag, and the filled porous nickel foil bag is subjected to plasma activation treatment. After treatment, it is composite-packaged with a dense iron foil bag to obtain a packaging unit packaged by a double-layer metal foil bag, wherein the porous nickel foil bag has a thickness of 0.2 mm, a pore diameter of 5 μm, and a pore density of 20,000 / mm 2The thickness of the dense iron foil bag is 0.1 mm, the length, width and height of the packaging unit are 600 mm × 300 mm × 200 mm, and the mass of the packaging unit is 50 kg / bag. The filling is carried out in batches according to the particle size. The bottom of the metal foil bag is first filled with alloy coarse powder with a particle size of 60-150 μm, and then the alloy fine powder with a particle size of 10-20 μm is filled on it. The mass ratio of the alloy coarse powder to the alloy fine powder is 3:2. The plasma activation treatment is to place the filled metal foil bag in a mixed atmosphere of argon and hydrogen with a volume ratio of 9:1, with a gas flow rate of 10 L / min, and perform plasma activation treatment under a 15 kW plasma generator for 10 minutes;

[0039] Step 2. Add materials and smelt

[0040] 2-1. The encapsulated unit was first placed in a crucible with a capacity of 3000kg, evacuated to 30Pa, and smelted under ultrasonic assistance at a frequency of 20kHz and a power of 50kW to form a molten pool. The initial charge of the encapsulated unit was 50% of the crucible capacity. The heating power for smelting was: an initial power of 250kW, which was then increased to 700kW within 20min, and the smelting time was 2h.

[0041] 2-2. The remaining encapsulated units were added to the molten pool of step 2-1 in 5 portions, each time adding an encapsulated unit mass of 300 kg, and the melting was continued under ultrasonic assistance at a frequency of 20 kHz and a power of 50 kW until the melt was clear to obtain a fully molten melt, wherein the heating power for melting was 1250 kW and the melting time was 0.8 h.

[0042] Step 3. Refining

[0043] The fully molten melt was heated to 1580°C, vacuumed to 0.1 Pa, and refined for 20 minutes under external magnetic field stirring to obtain a refined melt, wherein the external magnetic field stirring had a magnetic field frequency of 50 Hz and a magnetic induction intensity of 0.3 T;

[0044] Step 4. Three-stage filtration

[0045] After the refined melt is allowed to stand and cool to the pouring temperature, the slag is first blocked by a slag plate, and then filtered through a first-level zirconia foam ceramic filter disc, a second-level zirconia foam ceramic filter disc, and a third-level zirconia foam ceramic filter disc in sequence. The filtered melt is then poured into a steel mold to obtain a mother alloy ingot, wherein the porosity of the first-level filter disc is 10PPI, the porosity of the second-level filter disc is 30PPI, the porosity of the third-level filter disc is 50PPI, and the pouring temperature is 1480°C.

[0046] Example 2: Method for Recycling and Remelting Returned GH3536 Nickel-Based High-Temperature Alloy Powder

[0047] Step 1. Packaging of nickel-based high-temperature alloy powder return material

[0048] The nickel-based high-temperature alloy powder return material is filled into porous nickel foil bags in batches according to the particle size. The filled porous nickel foil bags are subjected to plasma activation treatment and then composite-packaged with dense iron foil bags to obtain a packaging unit packaged by a double-layer metal foil bag. The porous nickel foil bag has a thickness of 0.2 mm, a pore diameter of 10 μm, and a pore density of 5000 / mm 2 The thickness of the dense iron foil bag is 0.1mm, the length, width and height of the packaging unit are 600mm×300mm×200mm, and the mass of the packaging unit is 50kg / bag. The filling is carried out in batches according to the particle size. The bottom of the metal foil bag is first filled with alloy coarse powder with a particle size of 60-150μm, and then the alloy fine powder with a particle size of 10-20μm is filled on it. The mass ratio of alloy coarse powder to alloy fine powder is 3:2. The plasma activation treatment is to place the filled metal foil bag in a mixed atmosphere of argon and hydrogen with a volume ratio of 9:1, with a gas flow rate of 5L / min, and perform plasma activation treatment under a 10kW plasma generator for 10min;

[0049] Step 2. Add materials and smelt

[0050] 2-1. The encapsulated unit was first placed in a crucible with a capacity of 3000 kg, evacuated to 50 Pa, and smelted under ultrasonic assistance at a frequency of 50 kHz and a power of 100 kW to form a molten pool. The initial charge of the encapsulated unit was 50% of the crucible capacity. The heating power for smelting was: an initial power of 250 kW, then increased to 750 kW within 20 minutes, and the smelting time was 1 hour.

[0051] 2-2. The remaining encapsulated units were added to the molten pool of step 2-1 in 5 portions, each time adding an encapsulated unit mass of 300 kg, and the smelting was continued under ultrasonic assisted conditions of 50 kHz and 100 kW to obtain a fully molten melt, wherein the heating power for smelting was 1300 kW and the smelting time was 0.5 h.

[0052] Step 3. Refining

[0053] The fully molten melt was heated to 1580°C, vacuumed to 0.1 Pa, and refined for 20 minutes under external magnetic field stirring to obtain a refined melt, wherein the magnetic field frequency of the external magnetic field stirring was 50 Hz and the magnetic induction intensity was 0.3 T;

[0054] Step 4. Three-stage filtration

[0055] After the refined melt is allowed to stand and cool to the pouring temperature, the slag is first blocked by a slag plate, and then filtered through a first-level zirconia foam ceramic filter disc, a second-level zirconia foam ceramic filter disc, and a third-level zirconia foam ceramic filter disc in sequence. The filtered melt is then poured into a steel mold to obtain a mother alloy ingot, wherein the porosity of the first-level filter disc is 10PPI, the porosity of the second-level filter disc is 30PPI, the porosity of the third-level filter disc is 50PPI, and the pouring temperature is 1450°C.

[0056] Example 3: Method for Recycling and Remelting Returned GH4099 Nickel-Based High-Temperature Alloy Powder

[0057] Step 1. Packaging of nickel-based high-temperature alloy powder return material

[0058] The nickel-based high-temperature alloy powder return material is filled into porous nickel foil bags in batches according to the particle size. The filled porous nickel foil bags are subjected to plasma activation treatment and then composite-packaged with dense iron foil bags to obtain a packaging unit packaged by a double-layer metal foil bag. The porous nickel foil bag has a thickness of 0.2 mm, a pore diameter of 7 μm, and a pore density of 10,000 / mm 2 The thickness of the dense iron foil bag is 0.1mm, the length, width and height of the packaging unit are 600mm×300mm×200mm, and the mass of the packaging unit is 50kg / bag. The filling is carried out in batches according to the particle size. The bottom of the metal foil bag is first filled with alloy coarse powder with a particle size of 60-150μm, and then the alloy fine powder with a particle size of 10-20μm is filled on it. The mass ratio of alloy coarse powder to alloy fine powder is 3:2. The plasma activation treatment is to place the filled metal foil bag in a mixed atmosphere of argon and hydrogen with a volume ratio of 9:1, with a gas flow rate of 8L / min, and perform plasma activation treatment under a 13kW plasma generator for 10min;

[0059] Step 2. Add materials and smelt

[0060] 2-1. The encapsulated unit was first placed in a crucible with a capacity of 3000kg, evacuated to 40Pa, and smelted under ultrasonic assistance at a frequency of 30kHz and a power of 80kW to form a molten pool. The initial charge of the encapsulated unit was 50% of the crucible capacity. The heating power for smelting was: an initial power of 250kW, which was then increased to 800kW within 20min, and the smelting time was 1.5h.

[0061] 2-2. The remaining encapsulated units were added to the molten pool of step 2-1 in 5 portions, each time adding an encapsulated unit mass of 300 kg, and the melting was continued under ultrasonic assisted conditions of 30 kHz and 80 kW to obtain a fully molten melt, wherein the heating power for melting was 1280 kW and the melting time was 0.6 h.

[0062] Step 3. Refining

[0063] The fully molten melt was heated to 1580°C, vacuumed to 0.1 Pa, and refined for 20 minutes under external magnetic field stirring to obtain a refined melt, wherein the external magnetic field stirring had a magnetic field frequency of 50 Hz and a magnetic induction intensity of 0.3 T;

[0064] Step 4. Three-stage filtration

[0065] After the refined melt is allowed to stand and cool to the pouring temperature, the slag is first blocked by a slag plate, and then filtered through a first-level zirconia foam ceramic filter disc, a second-level zirconia foam ceramic filter disc, and a third-level zirconia foam ceramic filter disc in sequence. The filtered melt is then poured into a steel mold to obtain a mother alloy ingot, wherein the porosity of the first-level filter disc is 10PPI, the porosity of the second-level filter disc is 30PPI, the porosity of the third-level filter disc is 50PPI, and the pouring temperature is 1460°C.

[0066] In order to verify the influence of each step in the remelting process on the properties of the returned remelted master alloy ingot, the steps are omitted or replaced based on Example 1, as follows:

[0067] Preparation method of comparative example 1

[0068] The double-layer metal foil bag in step 1 of Example 1 was replaced with a single-layer non-porous nickel foil bag, that is, the nickel-based high-temperature alloy powder return material was filled into the single-layer non-porous nickel foil bag in batches according to the particle size, and the filled single-layer non-porous nickel foil bag was plasma activated and then packaged to obtain a packaging unit packaged by the single-layer non-porous nickel foil bag, wherein the thickness of the single-layer non-porous nickel foil bag was 0.3 mm, the length, width and height of the packaging unit were 600 mm × 300 mm × 200 mm, and the mass of the packaging unit was 50 kg / bag. The remaining steps were consistent with Example 1 to obtain the mother alloy ingot of Comparative Example 1.

[0069] Preparation method of comparative example 2

[0070] The double-layer metal foil bag in step 1 of Example 1 is replaced with a single-layer dense iron foil bag, that is, the nickel-based high-temperature alloy powder return material is filled into the single-layer dense iron foil bag in batches according to the particle size, and the filled single-layer dense iron foil bag is plasma activated and then packaged to obtain a packaging unit packaged by the single-layer dense iron foil bag, wherein the thickness of the single-layer dense iron foil bag is 0.3 mm, the length, width and height of the packaging unit are 600 mm×300 mm×200 mm, and the mass of the packaging unit is 50 kg / bag. The remaining steps are consistent with Example 1 to obtain the mother alloy ingot of Comparative Example 2.

[0071] Preparation method of comparative example 3

[0072] The porous nickel foil bag filled in step 1 of Example 1 was not subjected to plasma activation treatment, but was directly packaged in a dense iron foil bag. The remaining steps were the same as those of Example 1 to obtain the mother alloy ingot of Comparative Example 3.

[0073] Preparation method of comparative example 4

[0074] The batch filling according to particle size in step 1 of Example 1 was changed to random filling, and the remaining steps were consistent with Example 1 to obtain the mother alloy ingot of Comparative Example 4.

[0075] Preparation method of comparative example 5

[0076] The ultrasonic assisted melting in steps 2-1 and 2-2 of Example 1 was changed to ordinary heating melting without ultrasonic assisted treatment. The remaining steps were consistent with Example 1 to obtain the mother alloy ingot of Comparative Example 5.

[0077] Performance Testing

[0078] The prepared master alloy ingot was taken to test the oxygen content, nitrogen content, hydrogen content and inclusion content in the master alloy according to the following testing methods:

[0079] The oxygen content test refers to ASTM E1019-2011 "Standard Test Methods for Carbon, Sulfur, Nitrogen, and Oxygen in Steel and Iron, Nickel, and Cobalt Alloys by Combustion and Fusion Methods";

[0080] Nitrogen content detection refers to ASTM E1019-2011 "Standard Test Method for Carbon, Sulfur, Nitrogen, and Oxygen in Steel and Iron, Nickel, and Cobalt Alloys by Combustion and Fusion Methods";

[0081] The hydrogen content test refers to ASTM E1447-22 "Standard Test Method for Hydrogen in Reactive Metals and Reactive Metal Alloys by Inert Gas Fusion Method Using Thermal Conductivity or Infrared Spectroscopy";

[0082] The inclusion content test refers to the electrolytic extraction-filtration weighing method in ISO 4967 "Determination of non-metallic inclusion content of steel";

[0083] The testing conditions of the samples were the same. Three samples were randomly selected from the same batch of master alloy ingots (i.e., three parallel experiments were set up). The results were averaged and shown in Table 1.

[0084] Table 1 Test results of master alloy ingot

[0085]

[0086] Result analysis:

[0087] According to the results in Table 1, compared with Comparative Examples 1 and 2, the oxygen content, nitrogen content, hydrogen content and inclusion content of the master alloy ingot in Example 1 are significantly reduced. This is because Comparative Example 1 uses a single-layer non-porous nickel foil, which is unable to process the internal return material during plasma activation treatment, and the supporting capacity of the nickel foil during low vacuum melting is relatively poor, resulting in an increase in impurities in the master alloy ingot, while Comparative Example 2 is a single-layer dense iron foil, which is also unable to perform plasma activation treatment on the internal return material, resulting in an increase in impurities in the master alloy ingot.

[0088] Compared with Comparative Example 3, the oxygen content, nitrogen content, hydrogen content and impurities of the master alloy ingot in Example 1 are reduced. This is because the oxygen content in the alloy powder return material that has undergone plasma activation treatment is reduced, thereby inhibiting the alloy powder from generating oxides during the low vacuum smelting process. In the subsequent smelting process, reducing oxides can reduce impurities in the molten pool, improve the purity of the master alloy, and improve its mechanical properties and high-temperature stability.

[0089] Compared with Comparative Example 4, the oxygen content of the master alloy ingot in Example 1 is reduced by 79%, the nitrogen content is reduced by 69%, the hydrogen content is reduced by 75%, and the impurities are reduced. This is because when the return material is filled in batches according to the particle size, the coarse powder at the bottom has a large particle size and high porosity, which forms a stable skeleton structure, delays melting and provides a uniform heat conduction path. At the same time, its large gaps reserve diffusion channels for gases such as CO and N2 released in the early stage of smelting, reducing the content of impurity elements. The fine powder on the top melts quickly due to its high specific surface area, and the melt quickly penetrates downward through capillary action to fill the gaps between the coarse powder, thereby shortening the overall penetration time.

[0090] Compared with Comparative Example 5, the oxygen content of the master alloy ingot in Example 1 was reduced by 81%, the nitrogen content was reduced by 50%, and the hydrogen content was reduced by 50%. At the same time, the inclusion content was significantly reduced. This is because the use of ultrasound in the smelting stage can break the oxide layer on the powder surface through the cavitation effect of ultrasound, promote the reduction reaction, and reduce the formation of oxide inclusions. At the same time, the acoustic streaming effect can promote the flow of the melt and help the inclusions float and disperse.

[0091] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a master alloy by remelting and recovering returned nickel-based high-temperature alloy powder, characterized in that: The method comprises the following steps: Step 1. Packaging of nickel-based high-temperature alloy powder return material The nickel-based high-temperature alloy powder return material is filled into porous nickel foil bags in batches according to the particle size. The filled porous nickel foil bags are subjected to plasma activation treatment and then composite-packaged with dense iron foil bags to obtain a packaging unit packaged by a double-layer metal foil bag. The porous nickel foil bag has a thickness of 0.2 mm, a pore diameter of 5-10 μm, and a pore density of 5000-20000 / mm 2 , the thickness of the dense iron foil bag is 0.1mm, and the length, width and height of the packaging unit are 600mm×300mm×200mm; Step 2. Add materials and smelt 2-1. The encapsulated unit is first put into the crucible, evacuated to 30-50Pa, and smelted under the assistance of ultrasound at a frequency of 20-50kHz and a power of 50-100kW to form a molten pool. The initial feeding amount of the encapsulated unit is 50% of the crucible capacity, the heating power of the smelting is 250-800kW, and the smelting time is 1-2h. 2-2. The remaining encapsulated units were added to the molten pool of step 2-1 in batches and smelted until clear with the assistance of ultrasound at a frequency of 20-50kHz and a power of 50-100kW to obtain a fully molten melt. The heating power for smelting was 1250-1300kW and the smelting time was 0.5-0.8h. Step 3. Refining The fully molten melt was heated to 1580±10°C, vacuumed to ≤0.1 Pa, and refined for 20 minutes under stirring in an external magnetic field to obtain a refined melt; Step 4. Three-stage filtration After the refined melt is allowed to cool to the pouring temperature, it is filtered through a first-stage filter disc, a second-stage filter disc, and a third-stage filter element in sequence, and then the filtered melt is poured into a steel mold to obtain a mother alloy ingot. The porosity of the first-stage filter disc is 10PPI, the porosity of the second-stage filter disc is 30PPI, the third-stage filter element is a microchannel filter element with a pore size of 5μm, and the pouring temperature is 1450-1480℃.

2. The method according to claim 1, characterized in that In step 1, the nickel-based high-temperature alloy powder return material is filled into the porous nickel foil bag in batches according to the particle size: first, the bottom of the porous nickel foil bag is filled with alloy coarse powder with a particle size of 60-150 μm, and then the alloy fine powder with a particle size of 10-20 μm is filled thereon, wherein the mass ratio of the alloy coarse powder to the alloy fine powder is 3:

2.

3. The method according to claim 1, characterized in that The gases for plasma activation treatment in step 1 are argon and hydrogen with a volume ratio of 9:1, a gas flow rate of 5-10 L / min, a treatment power of 10-15 kW, and a treatment time of 10 min.

4. The method according to claim 1, wherein The mass of the packaging unit in step 1 is 50 kg / bag.

5. The method according to claim 1, characterized in that The crucible capacity in step 2-1 is 3000 kg; in step 2-2, the remaining packaging units are added to the molten pool in step 2-1 in 5 times, and the mass of the packaging units added each time is 300 kg.

6. The method according to claim 1, characterized in that The magnetic field frequency of the external magnetic field stirring in step 3 is 50 Hz, and the magnetic induction intensity is 0.3 T.

7. The method according to claim 1, characterized in that In step 4, the primary filter disc and the secondary filter disc are zirconia foam ceramic filter discs, and the microchannel filter element is a zirconia filter element.

8. A master alloy, characterized in that: The master alloy is prepared according to the method according to any one of claims 1-6.

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