Nuclear high homogeneity and high purity GH4145 alloy and short process preparation method thereof

Abstract

The application discloses a high-homogeneity and high-purity GH4145 alloy for nuclear use and a short-process preparation method thereof, which comprises the following steps: selecting and pretreating a crucible, preparing raw materials, distributing materials, and vacuum smelting; the impurity element content in the alloy is as follows: S is less than or equal to 0.001%, O is less than or equal to 0.001%, and N is less than or equal to 0.002%. In the application, calcium oxide is coated on the inner wall of a magnesium oxide crucible and reacts with excess aluminum, so that the effects of deep deoxidation, denitrification and desulfurization are achieved, and the corresponding inclusions are avoided; nickel-chromium and nickel-niobium intermediate alloys are selected to replace high-melting-point elemental metals of chromium and niobium, so that high-melting-point non-melting blocks are avoided, the smelting time is effectively shortened, the composition is homogenized, electromagnetic stirring is carried out during smelting, the composition is further homogenized, and the discharge of gas and low-density inclusions is promoted, so that the high-homogeneity and high-purity GH4145 alloy is obtained, the short-process preparation is realized, and the application is suitable for fastening bolts and spring components in a pressurized water reactor control rod drive mechanism.

Description

Technical Field

[0001] This invention belongs to the field of alloy preparation technology, specifically relating to a high-homogeneity and high-purity GH4145 alloy for nuclear applications and its short-process preparation method. Background Technology

[0002] GH4145 alloy, due to its excellent fatigue resistance, radiation resistance, high temperature resistance, and corrosion resistance, is currently used in the fastening bolts and spring components of the control rod drive mechanism in pressurized water reactors. These fastening bolts and spring components are in direct contact with the primary coolant and are subjected to long-term high temperature, high pressure, and corrosion from the reactor coolant. Therefore, they are required to possess not only the aforementioned excellent properties but also long-term structural stability to ensure stable service performance.

[0003] GH4145 alloy is a nickel-based superalloy that undergoes age-hardening via the γ' phase. The addition of Al, Ti, and Nb elements promotes the formation of the Ni3(Al,Ti,Nb) type γ' phase, achieving age-hardening precipitation strengthening. However, current processes for preparing GH4145 alloy suffer from inconsistent compositional uniformity, inclusions, harmful gases, and impurity content, leading to significant batch-to-batch fluctuations in the mechanical properties of the finished GH4145 alloy. Therefore, to ensure stable service performance of GH4145 alloy, precise control of the alloy element content and uniformity is necessary during preparation, along with reducing the content of inclusions and impurity elements to obtain highly homogeneous and pure GH4145 alloy billets.

[0004] Patent publication number CN114635058A discloses a GH4145 alloy electroslag ingot and its manufacturing method. This method uses a four-stage smelting process—electric furnace + argon-oxygen decarburization furnace + ladle refining furnace + electroslag—to produce high-purity, large-size, and homogeneous GH4145 alloy ingots. However, this method has a very long process flow, low production efficiency, and significantly increased costs.

[0005] Patent publication number CN105483448A discloses a method for preparing nuclear-grade nickel-based superalloy GH4145 wire. This method involves a dual-stage vacuum induction and vacuum consumable metallurgy process, followed by casting into alloy ingots. After homogenization, the ingots are forged into alloy steel ingots, then hot-rolled into wire rods with a diameter of 8mm to 12mm. Finally, solution treatment, multiple cold drawing, and annealing are performed to obtain GH4145 alloy wire of the required diameter. This method utilizes a small-ingot production process with a dual-vacuum approach to produce small-sized wire, which is unsuitable for preparing large-sized nickel-based superalloy GH4145 ingots. Furthermore, this patent lacks specific requirements for raw materials, and the production process does not control impurities such as oxygen and nitrogen, as well as inclusions, making it impossible to consistently guarantee the uniformity and purity of the prepared GH4145 alloy ingots. Summary of the Invention

[0006] The technical problem this invention aims to solve is to address the shortcomings of the prior art by providing a short-process preparation method for high-homogeneity and high-purity GH4145 alloy for nuclear applications. This method employs vacuum melting, where calcium oxide is coated onto the inner wall of a magnesium oxide crucible and reacts with excess aluminum to achieve deep deoxidation, denitrification, and desulfurization, while avoiding the formation of inclusions. By selecting nickel-chromium and nickel-niobium master alloys instead of the high-melting-point elemental metals chromium and niobium, the formation of high-melting-point infusible blocks is avoided, effectively shortening the melting time and promoting compositional homogenization. Furthermore, electromagnetic stirring during vacuum melting further homogenizes the composition and promotes the removal of gases and low-density inclusions, thereby obtaining a high-homogeneity and high-purity GH4145 alloy and achieving short-process preparation. This solves the problems of long process flows and the inability to consistently guarantee alloy homogeneity and purity in existing processes.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a short-process preparation method for high-homogeneity and high-purity GH4145 alloy for nuclear applications, characterized in that the method includes the following steps:

[0008] Step 1: Crucible selection and pretreatment: Select a magnesium oxide crucible, coat the inner wall of the magnesium oxide crucible with calcium oxide, and then dry it to obtain a pretreated crucible;

[0009] Step 2, Raw material preparation: Select blocky NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel, sponge titanium, metallic iron and metallic aluminum as raw materials. Then, according to the design composition of the target product GH4145 alloy, weigh the raw materials that meet the design composition requirements, and weigh metallic aluminum separately.

[0010] Step 3, Material Placement: Place a portion of the nickel metal weighed in Step 2 at the bottom of the pre-treatment crucible in Step 1. Place the aluminum metal weighed in Step 2 near the crucible wall. Then, sequentially add the sponge titanium, iron metal, remaining nickel metal, aluminum metal, blocky NiCr45 master alloy, and NiNb65 master alloy from the raw materials to complete the material placement.

[0011] Step 4, Vacuum Melting: After the material is laid out in Step 3, vacuum induction melting is carried out, accompanied by electromagnetic stirring. Then, it is cast into an ingot to obtain a high-homogeneity and high-purity GH4145 alloy.

[0012] This invention employs vacuum induction melting to prepare GH4145 alloy, using a magnesium oxide crucible with an inner wall coated with calcium oxide as the melting crucible. During melting, the calcium oxide on the inner wall of the crucible reacts with aluminum added to the alloy raw materials to form CaO-saturated CaO·Al2O3 slag. This reduces the activity of Al2O3, accelerating the reaction between aluminum and oxygen, thus facilitating deep deoxidation. Furthermore, CaO can react simultaneously with Al and S to form CaS and CaO·Al2O3, which is beneficial for desulfurization. Simultaneously, the improved deoxidation effect also reduces the concentration of free oxygen in the molten metal, decreasing the chance of oxidation of other impurities and further improving denitrification and desulfurization efficiency. Secondly, the raw materials used in this invention have melting points and densities close to those of the base nickel metal (melting point approximately 1455℃, density approximately 8.9 g / cm³). 3 Nickel-chromium master alloy (melting point approximately 1350℃, density approximately 8.1 g / cm³) 3 ) and nickel-niobium master alloy (melting point approximately 1290℃, density approximately 8.7 g / cm³) 3 This invention replaces high-melting-point elemental metals chromium (melting point approximately 1907℃) and niobium (melting point approximately 2477℃) with a high-melting-point non-melting-point inclusion, avoiding the formation of high-melting-point infusible inclusions and effectively reducing melting time and the loss of low-melting-point aluminum, thereby allowing for more precise control of alloying elements and compositional uniformity. Furthermore, the vacuum melting process of this invention is accompanied by electromagnetic stirring, which facilitates the diffusion of alloying elements and promotes the upward flotation and removal of gases and low-density inclusions, further homogenizing the alloy composition and improving alloy purity. Under the combined effects of the above, this invention produces a highly homogeneous and highly pure GH4145 alloy, suitable for use in nuclear equipment.

[0013] In the vacuum induction melting process of this invention, the bottom and middle parts of the crucible become high-temperature zones due to poor heat dissipation. Therefore, the relatively high-melting-point metallic nickel (1455℃), sponge titanium (1660℃), metallic iron (1539℃), and the remaining nickel are placed in the bottom position of the crucible, while the low-density sponge titanium (4.54 g / cm³) is placed in the middle position. 2 Placing the metal between nickel and iron helps to homogenize the elements after melting. Then, placing the low-melting-point aluminum, blocky NiCr45 master alloy, and NiNb65 master alloy on the top of the crucible improves the uniformity of melting.

[0014] The above-mentioned short-process preparation method for high-homogeneity and high-purity GH4145 alloy for nuclear applications is characterized in that the coating thickness of calcium oxide in step one is 1 mm to 3 mm; the drying temperature is 600℃ to 700℃, and the time is 15 min to 30 min. This invention, by controlling the coating thickness of calcium oxide and the temperature and time of the drying process, effectively removes the bound water from the calcium oxide, ensuring the dryness of the magnesium oxide crucible and the coated calcium oxide, which is beneficial for subsequent deoxidation, denitrification, and desulfurization.

[0015] The aforementioned short-process preparation method for high-homogeneity and high-purity GH4145 alloy for nuclear applications is characterized by the fact that the raw materials in step two—bulk NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel, sponge titanium, metallic iron, and metallic aluminum—all have a purity greater than 99.9% and a size of 10mm to 100mm. This invention, by strictly controlling the purity and size of the raw materials, facilitates the uniformity of composition during material preparation and subsequent melting, and ensures that the final product, GH4145 alloy, has low impurity content and high purity.

[0016] The above-mentioned short-process preparation method for high-homogeneity and high-purity GH4145 alloy for nuclear applications is characterized in that the mass of the additionally weighed metallic aluminum in step two is 0.5% of the total mass of the raw materials. The 0.5% aluminum mass fraction reacts with calcium oxide on the inner wall of the crucible during the smelting process to form CaO-saturated CaO·Al2O3 slag. This reduces the activity of Al2O3, accelerating the reaction between aluminum and oxygen, thus facilitating deep deoxidation. Furthermore, CaO can react simultaneously with Al and S to form CaS and CaO·Al2O3, which is beneficial for desulfurization. At the same time, the better deoxidation effect also reduces the concentration of free oxygen in the molten metal, reducing the oxidation opportunities of other impurities and further improving denitrification and desulfurization efficiency.

[0017] The above-mentioned short-process preparation method of high homogeneous and high-purity GH4145 alloy for nuclear applications is characterized in that the mass of the nickel in step three accounts for 1 / 2 of the total mass of nickel in the raw materials.

[0018] The aforementioned short-process preparation method for high-homogeneity and high-purity GH4145 alloy for nuclear applications is characterized by the following steps: The vacuum induction melting process in step four involves first evacuating to 0.005 Pa to 0.001 Pa, then introducing argon gas with a purity of 99.99% or higher to 0.1 Pa for gas washing. This evacuation and argon gas washing process is repeated twice. Melting then occurs at a temperature of 1500℃ to 1700℃, followed by holding at that temperature for 20 to 40 minutes after melting. This invention, through two gas washing processes and the high vacuum during melting, avoids contamination of the alloy by gases present in the furnace cavity during the melting process. Simultaneously, the appropriate melting temperature and time ensure uniform melting of the raw materials, avoiding incomplete melting and uneven diffusion of alloy elements due to insufficient melting temperature or time, or excessive loss of low-melting-point elements due to excessively high melting temperature or time.

[0019] The above-mentioned short-process preparation method for high-homogeneity and high-purity GH4145 alloy for nuclear applications is characterized in that the voltage of the electromagnetic stirring accompanying the vacuum induction melting process in step four is 100V~150V, and the current is 4kA~5kA. By performing electromagnetic stirring within the above parameter range during vacuum melting, this invention facilitates the diffusion of alloying elements and promotes the upward flotation and removal of gases and low-density inclusions, further homogenizing the composition of the GH4145 alloy and improving its purity.

[0020] Meanwhile, the present invention also discloses a high homogeneous and high-purity GH4145 alloy for nuclear applications prepared by the method described above. The GH4145 alloy is characterized in that the main elements Ni, Cr, Al, Ti, Fe and Nb are uniformly distributed and there is no segregation. The mass percentage of key impurity elements is: S≤0.001%, O≤0.001%, N≤0.002%.

[0021] The GH4145 alloy prepared by this invention is characterized by high homogeneity, high purity, and low impurity content. The alloying elements are uniformly distributed, and there are no infusible inclusions formed by high-melting-point elemental metals or inclusions formed by impurity elements such as oxygen, nitrogen, and sulfur. Furthermore, the content of these impurity elements is low. Fastening bolts and spring components in the pressurized water reactor control rod drive mechanism prepared using this alloy billet can ensure excellent service performance and stability.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. This invention utilizes a magnesium oxide crucible with an inner wall coated with calcium oxide during the vacuum induction melting process of GH4145 alloy. The calcium oxide reacts with excess aluminum metal to deoxidize, denitrify, and desulfurize, reducing impurity content and the corresponding inclusion content. By using nickel-chromium and nickel-niobium master alloys instead of high-melting-point elemental metals chromium and niobium, the formation of high-melting-point unmelting block inclusions is avoided, effectively reducing melting time and the loss of low-melting-point aluminum metal, thus allowing for more precise control of alloy elements and compositional uniformity. Furthermore, electromagnetic stirring during vacuum melting facilitates the diffusion of alloy elements and promotes the upward flotation and discharge of gases and low-density inclusions, further homogenizing the alloy composition and improving alloy purity.

[0024] 2. The GH4145 alloy prepared by this invention has the characteristics of high homogeneity, high purity and low impurity content. The alloy elements are uniformly distributed, without non-melting block inclusions formed by high melting point elemental metals or inclusions formed by impurity elements such as oxygen, nitrogen and sulfur. Moreover, the impurity element content is low, making it suitable for fastening bolts and spring components in the control rod drive mechanism of pressurized water reactors, ensuring the superior performance and stability of the components.

[0025] 3. Compared with the four-stage process of electric furnace + argon-oxygen decarburization furnace + ladle refining furnace + electroslag to prepare GH4145 electroslag ingots, the present invention can prepare high-homogeneity and high-purity GH4145 alloy using only vacuum induction melting process. The process flow is short, the production efficiency is high, and the cost is significantly reduced.

[0026] 4. Compared with the conventional method of vacuum induction + vacuum consumable double smelting and casting into alloy ingots, the present invention coats the crucible wall with calcium oxide and adds excess aluminum for deep deoxidation, denitrification and desulfurization. Combined with the use of intermediate alloys with melting points and densities close to those of the base metal nickel for smelting, it is more conducive to uniform composition, reduced impurity content and improved alloy purity.

[0027] 5. The method for preparing high-homogeneity and high-purity GH4145 alloy of the present invention is simple and effective, and suitable for large-scale industrial production.

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0029] Figure 1 This is a scanned image of the GH4145 alloy prepared in Example 1 of the present invention.

[0030] Figure 2 This is a Ni element distribution diagram in the GH4145 alloy prepared in Example 1 of the present invention.

[0031] Figure 3 The image shows the Cr element distribution in the GH4145 alloy prepared in Example 1 of this invention.

[0032] Figure 4 The image shows the Al element distribution in the GH4145 alloy prepared in Example 1 of this invention.

[0033] Figure 5 The image shows the Ti element distribution in the GH4145 alloy prepared in Example 1 of this invention.

[0034] Figure 6 This is a distribution diagram of Fe element in the GH4145 alloy prepared in Example 1 of the present invention.

[0035] Figure 7 The Nb element distribution diagram is shown in the GH4145 alloy prepared in Example 1 of this invention. Detailed Implementation

[0036] Example 1

[0037] This embodiment includes the following steps:

[0038] Step 1: Crucible selection and pretreatment: Select a magnesium oxide crucible and coat the inner wall of the magnesium oxide crucible with a thickness of 2 mm of calcium oxide. Then dry it at a temperature of 650℃ for 20 min to obtain a pretreated crucible.

[0039] Step 2: Raw Material Preparation: Select bulk NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron, and metallic aluminum as raw materials. Then, according to the design composition of the target product GH4145 alloy, weigh the raw materials that meet the design composition requirements, and separately weigh metallic aluminum. The mass purity of the raw materials, including bulk NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron, and metallic aluminum, is greater than 99.9%, and the size is 10mm to 100mm. The mass of the separately weighed metallic aluminum is 0.5% of the total mass of the raw materials.

[0040] Step 3, Material Placement: Place half of the nickel plates (accounting for 1 / 2 of the total mass of nickel in the raw materials) at the bottom of the pre-treatment crucible in Step 1. Place the aluminum metal weighed in Step 2 near the crucible wall. Then, sequentially add the sponge titanium, iron metal, remaining nickel plates, aluminum metal, blocky NiCr45 master alloy, and NiNb65 master alloy from the raw materials to complete the material placement.

[0041] Step 4, Vacuum Melting: After the material is laid out in Step 3, vacuum induction melting is performed, accompanied by electromagnetic stirring. The resulting ingot is then cast to obtain a highly homogeneous and highly purified GH4145 alloy. The vacuum induction melting process is as follows: first, a vacuum is drawn to 0.005 Pa to 0.001 Pa, then argon gas with a purity of 99.99% or higher is introduced to 0.1 Pa for gas washing. This vacuuming and argon gas washing process is repeated twice. Then, melting is performed at a temperature of 1600℃, and the melt is held at that temperature for 30 minutes after melting. The electromagnetic stirring during the vacuum induction melting process uses a voltage of 130V and a current of 4.5kA.

[0042] The impurity elements of the GH4145 alloy prepared in this embodiment were detected, and the results are shown in Table 1 below:

[0043] Table 1. Impurity element content (wt%) of the GH4145 alloy prepared in this embodiment.

[0044] element S O N content 0.001 0.001 0.002

[0045] As shown in Table 1, the GH4145 alloy has very low levels of impurity elements, especially oxygen, nitrogen, and sulfur. When used in the fastening bolts and spring components of the pressurized water reactor control rod drive mechanism, it can ensure superior service performance and stability.

[0046] Figure 1This is a scanned image of the GH4145 alloy prepared in this embodiment. Figures 2-7 The distribution diagrams of Ni, Cr, Al, Ti, Fe, and Nb elements in the GH4145 alloy prepared in this embodiment are shown below, combined with... Figure 1 and Figures 2-7 It can be seen that all alloying elements in the GH4145 alloy are uniformly distributed overall, with no segregation or high-melting-point infusible inclusions.

[0047] Example 2

[0048] This embodiment includes the following steps:

[0049] Step 1: Crucible selection and pretreatment: Select a magnesium oxide crucible and coat the inner wall of the magnesium oxide crucible with a thickness of 1 mm of calcium oxide. Then dry it at 600℃ for 30 min to obtain a pretreated crucible.

[0050] Step 2: Raw Material Preparation: Select bulk NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron, and metallic aluminum as raw materials. Then, according to the design composition of the target product GH4145 alloy, weigh the raw materials that meet the design composition requirements, and separately weigh metallic aluminum. The mass purity of the raw materials, including bulk NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron, and metallic aluminum, is greater than 99.9%, and the size is 10mm to 100mm. The mass of the separately weighed metallic aluminum is 0.5% of the total mass of the raw materials.

[0051] Step 3, Material Placement: Place half of the nickel plates (accounting for 1 / 2 of the total mass of nickel in the raw materials) at the bottom of the pre-treatment crucible in Step 1. Place the aluminum metal weighed in Step 2 near the crucible wall. Then, sequentially add the sponge titanium, iron metal, remaining nickel plates, aluminum metal, blocky NiCr45 master alloy, and NiNb65 master alloy from the raw materials to complete the material placement.

[0052] Step 4, Vacuum Melting: After the fabric is laid out in Step 3, vacuum induction melting is performed, accompanied by electromagnetic stirring. The resulting ingot is then cast to obtain a highly homogeneous and highly purified GH4145 alloy. The vacuum induction melting process is as follows: first, a vacuum is drawn to 0.005 Pa to 0.001 Pa, then argon gas with a purity of 99.99% or higher is introduced to 0.1 Pa for gas washing. This vacuuming and argon gas washing process is repeated twice. Then, melting is performed at a temperature of 1500℃, and the melt is held at that temperature for 40 minutes after it is completely melted. The electromagnetic stirring during the vacuum induction melting process uses a voltage of 100V and a current of 4kA.

[0053] The impurity elements in the GH4145 alloy prepared in this embodiment were detected, and the results are shown in Table 2 below:

[0054] Table 2. Impurity element content (wt%) of the GH4145 alloy prepared in this embodiment.

[0055] element S O N content 0.001 0.001 0.002

[0056] As shown in Table 2, the GH4145 alloy has very low levels of impurity elements, especially oxygen, nitrogen, and sulfur. When used in the fastening bolts and spring components of the pressurized water reactor control rod drive mechanism, it can ensure superior service performance and stability.

[0057] Testing revealed that all alloying elements in the GH4145 alloy prepared in this embodiment were uniformly distributed, with no segregation or high-melting-point infusible inclusions.

[0058] Example 3

[0059] This embodiment includes the following steps:

[0060] Step 1: Crucible selection and pretreatment: Select a magnesium oxide crucible and coat the inner wall of the magnesium oxide crucible with calcium oxide with a thickness of 3 mm. Then dry it at 700℃ for 15 min to obtain a pretreated crucible.

[0061] Step 2: Raw Material Preparation: Select bulk NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron, and metallic aluminum as raw materials. Then, according to the design composition of the target product GH4145 alloy, weigh the raw materials that meet the design composition requirements, and separately weigh metallic aluminum. The mass purity of the raw materials, including bulk NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron, and metallic aluminum, is greater than 99.9%, and the size is 10mm to 100mm. The mass of the separately weighed metallic aluminum is 0.5% of the total mass of the raw materials.

[0062] Step 3, Material Placement: Place half of the nickel plates (accounting for 1 / 2 of the total mass of nickel in the raw materials) at the bottom of the pre-treatment crucible in Step 1. Place the aluminum metal weighed in Step 2 near the crucible wall. Then, sequentially add the sponge titanium, iron metal, remaining nickel plates, aluminum metal, blocky NiCr45 master alloy, and NiNb65 master alloy from the raw materials to complete the material placement.

[0063] Step 4, Vacuum Melting: After the fabric is laid out in Step 3, vacuum induction melting is performed, accompanied by electromagnetic stirring. The resulting ingot is then cast to obtain a highly homogeneous and highly purified GH4145 alloy. The vacuum induction melting process is as follows: first, a vacuum is drawn to 0.005 Pa to 0.001 Pa, then argon gas with a purity of 99.99% or higher is introduced to 0.1 Pa for gas washing. This vacuuming and argon gas washing process is repeated twice. Melting then takes place at a temperature of 1700℃, and the melt is held at that temperature for 20 minutes after it is completely melted. The electromagnetic stirring during the vacuum induction melting process uses a voltage of 150V and a current of 5kA.

[0064] The impurity elements in the GH4145 alloy prepared in this embodiment were detected, and the results are shown in Table 3 below:

[0065] Table 3. Impurity element content (wt%) of the GH4145 alloy prepared in this embodiment.

[0066] element S O N content 0.0003 0.0002 0.001

[0067] As shown in Table 3, the GH4145 alloy has very low levels of impurity elements, especially oxygen, nitrogen, and sulfur. When used in the fastening bolts and spring components of the pressurized water reactor control rod drive mechanism, it can ensure superior service performance and stability.

[0068] Testing revealed that all alloying elements in the GH4145 alloy prepared in this embodiment were uniformly distributed, with no segregation or high-melting-point infusible inclusions.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A short-process preparation method for high-homogeneity, high-purity GH4145 alloy for nuclear applications, characterized in that, The method includes the following steps: Step 1: Crucible selection and pretreatment: Select a magnesium oxide crucible, coat the inner wall of the magnesium oxide crucible with calcium oxide, and then dry it to obtain a pretreated crucible; Step 2, Raw material preparation: Select blocky NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel, sponge titanium, metallic iron and metallic aluminum as raw materials. Then, according to the design composition of the target product GH4145 alloy, weigh the raw materials that meet the design composition requirements, and weigh metallic aluminum separately. Step 3, Material Placement: Place a portion of the nickel metal weighed in Step 2 at the bottom of the pre-treatment crucible in Step 1. Place the aluminum metal weighed in Step 2 near the crucible wall. Then, sequentially add the sponge titanium, iron metal, remaining nickel metal, aluminum metal, blocky NiCr45 master alloy, and NiNb65 master alloy from the raw materials to complete the material placement. Step 4, Vacuum Melting: After the material is laid out in Step 3, vacuum induction melting is carried out, accompanied by electromagnetic stirring. Then, it is cast into an ingot to obtain a high-homogeneity and high-purity GH4145 alloy.

2. The method for preparing high-homogeneity, high-purity GH4145 alloy for nuclear applications using a short-process method according to claim 1, characterized in that, The coating thickness of calcium oxide in step one is 1 mm to 3 mm; the drying temperature is 600℃ to 700℃ and the time is 15 min to 30 min.

3. The method for preparing high-homogeneity, high-purity GH4145 alloy for nuclear applications using a short-process method according to claim 1, characterized in that, In step two, the raw materials, including blocky NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel, sponge titanium, metallic iron, and metallic aluminum, all have a purity greater than 99.9% and a size of 10mm to 100mm.

4. The method for preparing high-homogeneity, high-purity GH4145 alloy for nuclear applications using a short-process method according to claim 1, characterized in that, The mass of the additional aluminum metal weighed in step two is 0.5% of the total mass of the raw materials.

5. The method for short-process preparation of high-homogeneity, high-purity GH4145 alloy for nuclear applications according to claim 1, characterized in that, The mass of the nickel metal mentioned in step three accounts for 1 / 2 of the total mass of nickel metal in the raw material.

6. The method for preparing high-homogeneity, high-purity GH4145 alloy for nuclear applications using a short-process method according to claim 1, characterized in that, The vacuum induction melting process described in step four is as follows: first, evacuate to 0.005 Pa to 0.001 Pa, then fill with argon gas with a mass purity of 99.99% or higher to 0.1 Pa for gas washing. Repeat the evacuation and argon filling gas washing process twice. Then, melt the gas at a temperature of 1500℃ to 1700℃. After melting, keep the temperature for 20 min to 40 min.

7. The method for preparing high-homogeneity, high-purity GH4145 alloy for nuclear applications using a short-process approach according to claim 1, characterized in that, The voltage of the electromagnetic stirring accompanying the vacuum induction melting process described in step four is 100V to 150V, and the current is 4kA to 5kA.

8. A high-homogeneity, high-purity GH4145 alloy for nuclear applications prepared by the method described in any one of claims 1 to 7, characterized in that, The GH4145 alloy has a uniform distribution of main elements Ni, Cr, Al, Ti, Fe, and Nb without segregation, and the mass percentages of key impurity elements are: S≤0.001%, O≤0.001%, and N≤0.002%.

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