Method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloy through duplex process
By combining TaTi intermediate alloying in the consumable melting stage and composite scanning trajectory control in the electron beam melting stage, the problems of uneven composition and difficulty in removing impurities in V-Nb-Ta-Ti alloys were solved, and high-purity and high-uniformity alloy preparation was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING INST OF TECH
- Filing Date
- 2025-12-02
- Publication Date
- 2026-04-28
AI Technical Summary
Existing technologies struggle to achieve high compositional uniformity and low impurity content in V-Nb-Ta-Ti refractory high-entropy alloys, especially given the significant differences in melting points among the components, high chemical reactivity, difficulty in removing impurities, and challenges in controlling composition during the smelting process.
By employing TaTi intermediate alloying and composition pre-compensation in the self-consumable melting stage, combined with a composite scanning trajectory control method in the electron beam melting stage, including the alternating use of parallel trajectory scanning and sinusoidal trajectory scanning, the full melting, uniform convection and stable volatilization of the melt are achieved.
A high-purity V-Nb-Ta-Ti alloy with uniform composition and extremely low impurity content was obtained, solving the problems of compositional inhomogeneity and impurity residue, and improving the quality and performance stability of the alloy.
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Figure CN121928048A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process, belonging to the field of alloy technology. Background Technology
[0002] Refractory high-entropy alloys composed of high-melting-point elements such as Nb, Ta, V, Mo, W, and Ti have attracted widespread attention due to their excellent high-temperature strength, outstanding creep resistance, and corrosion resistance. Among them, V-Nb-Ta-Ti alloys, as a typical representative of refractory high-entropy alloys, possess both excellent strength and ductility and high-temperature structural stability, demonstrating great application potential in extreme environments such as aerospace and nuclear power industries. However, achieving high compositional homogeneity and low impurity content in these alloys remains a core challenge restricting their large-scale preparation and performance improvement. Currently, vacuum arc remelting technology is commonly used to prepare these alloys. However, the melting points of the components in the V-Nb-Ta-Ti system differ greatly (for example, Ta has a melting point as high as 3017 ℃, while Ti's is only 1668 ℃), and the elements have high chemical reactivity, which brings significant difficulties to homogenization control during the melting process. In the traditional self-consumable melting process, on the one hand, interstitial impurities (such as C, N, and O) are difficult to remove effectively; on the other hand, high-melting-point components (especially Ta) are often difficult to melt completely due to insufficient local temperature, which easily leads to unmelted residues or coarse segregation in the ingot, resulting in uneven composition distribution and unstable structure.
[0003] Electron beam melting technology, with its high vacuum environment and extremely high energy density, is an effective means of deep purification and improving ingot uniformity. However, in the V-Nb-Ta-Ti system, the saturated vapor pressures of V and Ti components are relatively high, making them highly volatile under high-temperature electron beam conditions. This leads to deviations from the designed composition, severely affecting the stability of the alloy's properties. Furthermore, if electron beam melting is performed directly with elemental raw materials, the differences in melting points and vapor pressures between the elements will cause violent splashing and evaporation in the initial stage of melting, making it difficult to precisely control the melt composition and obtain ingots with uniform composition. Summary of the Invention
[0004] In view of this, the purpose of this invention is to provide a method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process. This method achieves full melting, uniform convection, and stable volatilization of the alloy melt through TaTi intermediate alloying and composition pre-compensation in the consumable melting stage, and a composite scanning trajectory control method in the electron beam melting stage, thereby obtaining a high-purity V-Nb-Ta-Ti alloy with uniform composition and extremely low impurity content.
[0005] To achieve the above objectives, the technical solution of the present invention is as follows.
[0006] A method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process, comprising the following steps: (1) Prepare and clean the raw materials according to the composition of the V-Nb-Ta-Ti refractory high-entropy alloy; (2) Homogeneous mixing is carried out under an inert atmosphere, and the mixture is loaded into a mold for cold isostatic pressing to obtain a dense electrode block; (3) Place the electrode block in a vacuum consumable melting furnace and melt it 2-3 times to obtain a pre-alloyed ingot; (4) Place the pre-alloyed ingot in a water-cooled copper crucible inside the electron beam melting furnace and evacuate it to 1.5 × 10⁻⁶. - Below 2 Pa, parallel trajectory scanning and sinusoidal trajectory scanning are used for periodic alternating processing. After melting, the beam is instantly lowered and cooled to obtain the alloy after melting on one side. (5) Flip the alloy after one side has been melted and repeat step (4) to obtain a high-purity V-Nb-Ta-Ti refractory high-entropy alloy; In step (1), the V-Nb-Ta-Ti refractory high entropy alloy is composed of four elements: V, Nb, Ta, and Ti. The atomic percentage content of each element is 2% to 50%, and the atomic percentage content of Ta is less than that of Ti. The raw material Ta is added in the form of TaTi master alloy, and V, Nb and the balance Ti are added in the form of elemental vanadium, elemental niobium and elemental titanium, and the amount of elemental titanium and elemental vanadium is 2% to 30% excess.
[0007] Preferably, in step (1), the atomic percentage content of V is 20%~50%, the atomic percentage content of Nb is 15%~35%, the atomic percentage content of Ta is 5%~20%, and the atomic percentage content of Ti is 10%~35%; the molar ratio of Ta to Ti in the TaTi master alloy is 1:1.
[0008] Preferably, in step (1), the raw material is ultrasonically treated in propanol for 15-20 minutes during cleaning.
[0009] Preferably, in step (2), the homogenization mixing time is 10~20 min.
[0010] Preferably, in step (2), the cold isostatic pressure is 200~600MPa and the holding time is 3~5min.
[0011] Preferably, in step (3), the vacuum degree inside the furnace during melting is less than or equal to 5 × 10⁻⁶. -1 Pa, melting current is 8~12kA, melting voltage is 20~35V.
[0012] Preferably, in step (4), during parallel trajectory scanning, the beam moves back and forth along the parallel line direction, the scanning frequency is 50~200Hz, the melting power is 20~60kW, and the melt temperature is maintained at 2000~2500℃; during sinusoidal trajectory scanning, the beam moves continuously along the sinusoidal path, the scanning frequency is 100~300Hz, the melting power is 30~70kW, and the melt temperature is maintained at 2200~2800℃; during parallel trajectory scanning, it can ensure that the melt is heated relatively uniformly, and a temperature gradient can be formed in the melt to initially generate convection and solute transport; during sinusoidal trajectory scanning, rotation and cross disturbances are generated on the basis of the original flow, forming a more complex melt flow field structure, further enhancing the convection intensity and element diffusion rate, which is beneficial to impurity removal and compositional homogenization. More preferably, during parallel trajectory scanning, the beam moves back and forth along the parallel line direction, with a scanning frequency of 50~100Hz, a melting power of 40~50kW, and the melt temperature maintained at 2300~2400℃; during sinusoidal trajectory scanning, the beam moves continuously along a sinusoidal path, with a scanning frequency of 150~250Hz, a melting power of 60~70kW, and the melt temperature maintained at 2500~2600℃.
[0013] Preferably, in step (4), the alternating treatment cycle is 1~3 min, and the overall smelting time is 5~30 min.
[0014] Preferably, in step (4), the electron gun beam current is instantaneously reduced to 0 at a rate of 0.8~1 A / s.
[0015] A high-purity V-Nb-Ta-Ti refractory high-entropy alloy was prepared by the above method.
[0016] Beneficial effects The dual-process of this invention combines "consumable pre-alloying" and "electron beam refining." In the consumable melting stage, compositional pre-compensation and intermediate alloying resolve the contradiction between the refractory nature of high-melting-point components and the volatilization of low-melting-point components. In the electron beam stage, composite scanning trajectories enhance three-dimensional convection, achieving deep control over composition and impurities. The synergy of these two processes overcomes the bottlenecks of uneven composition and impurity residue in existing technologies.
[0017] This invention enhances the melt temperature gradient by precisely controlling the scanning strategy and temperature during the electron beam melting process, thereby inducing melt convection, effectively promoting solute diffusion and gas discharge, and achieving deep homogenization and efficient purification of the melt.
[0018] The V-Nb-Ta-Ti refractory high-entropy alloy prepared by the dual-process provided by this invention has high compositional precision, low impurity content, and uniform composition, achieving a breakthrough in ingot quality. Attached Figure Description
[0019] Figure 1This is a schematic diagram of different scanning trajectories in the electron beam melting process of Embodiment 1 of the present invention.
[0020] Figure 2 This is a physical image of the refractory high-entropy alloy prepared in Example 1 of the present invention. Detailed Implementation
[0021] The present invention will be further described in detail below with reference to specific embodiments.
[0022] Example 1 A method for preparing high-purity V by electron beam melting 40 Nb 40 Ta 10 Ti 10 The method for processing refractory high-entropy alloys includes the following steps: S1. Increase the proportion of V component in raw materials by 4% and Ti by 8%, according to V... 44 Nb 31 Ta7Ti 18 The raw materials were weighed, consisting of sponge titanium, electrolytic dendritic vanadium, and niobium shavings, with Ta added using a Ta-Ti (1:1) master alloy. The raw materials were then ultrasonicated in acetone at 100 kHz for 15 min.
[0023] S2. Homogenize the mixture under an inert atmosphere for 20 minutes, then load the mixture into a mold and cold isostatically press it under a pressure of 300 MPa for 5 minutes to form a dense electrode block, ensuring uniform element distribution and stable arc discharge.
[0024] S3. Place the electrode in a vacuum consumable melting furnace, with a vacuum level of 3×10⁻⁶. -1 Pa, melting current 10 kA, melting voltage 35 V, and remelting 3 times to obtain a pre-alloyed ingot; S4. Place the obtained pre-alloyed ingot in a water-cooled copper crucible inside an electron beam melting furnace, and then evacuate to a high vacuum of 5×10⁻⁶. - 3 Pa.
[0025] S5. A composite scanning trajectory strategy is used for melting, with alternating high-purity homogenization treatment performed periodically, such as... Figure 1 As shown: S51. First, perform parallel trajectory scanning: the beam moves back and forth along the parallel line direction, the scanning frequency is 100 Hz, the melting power is 30 kW, the melt temperature is maintained at 2200 ℃, and preliminary convection and solute transport are formed in the melt. S52. Then, a sinusoidal trajectory scanning is adopted: the beam moves continuously along a sinusoidal path, the scanning frequency is 150 Hz, the melting power is 40 kW, and the melt temperature is maintained at 2300 ℃; rotation and cross disturbances are generated on the basis of the original flow, forming a more complex melt flow field structure, further enhancing the convection intensity and element diffusion rate, and realizing impurity removal and deep homogenization of composition.
[0026] During the above process, the melting time is maintained at 15 min, and the scanning trajectory switching cycle is 1 min.
[0027] S5. After melting, the beam is instantly lowered at a rate of 1 A / s to obtain a sample cooled to room temperature; S6. The sample cooled to room temperature is flipped and remelted, and steps S4-S6 are repeated to obtain a high-purity, homogeneous, refractory, high-entropy alloy, as shown in the figure. Figure 2 As shown.
[0028] The C, N, and O contents of the V-Nb-Ta-Ti refractory high-entropy alloy before and after two smelting processes are shown in Table 1. It can be seen that the impurity removal effect of the ingot is significant, with uniform distribution of impurities at different locations, and the C, N, and O contents are all below 100 ppm. The ingot composition test results are shown in Table 2. The alloy components exhibit some volatility, and the composition is uniformly distributed across the ingot (with intervals of 4-8 mm between the upper, middle, and lower parts), and meets the V... 40 Nb 40 Ta 10 Ti 10 The target component.
[0029] Table 1 Impurity element content
[0030] Table 2 Atomic percentage of each element / %
[0031] Example 2 A method for preparing high-purity VNbTaTi refractory high-entropy alloy by electron beam melting, comprising the following steps: S1. Increase the proportion of V in the raw material by 5% and Ti by 10%, according to V... 30 Nb 15 Ta 20 Ti 35 The raw materials were weighed, consisting of sponge titanium, electrolytic dendritic vanadium, and niobium shavings, with Ta added using a Ta-Ti (1:1) master alloy. The raw materials were then ultrasonicated in acetone at 100 kHz for 15 min.
[0032] S2. Homogenize the mixture under an inert atmosphere for 20 minutes, then load the mixture into a mold and cold isostatically press it under a pressure of 300 MPa for 5 minutes to form a dense electrode block, ensuring uniform element distribution and stable arc discharge.
[0033] S3. Place the electrode in a vacuum consumable melting furnace, with a vacuum level of 2×10⁻⁶. -1 Pa, melting current 12 kA, melting voltage 35 V, and remelting 3 times to obtain pre-alloyed ingots.
[0034] S4. Place the obtained pre-alloyed ingot in a water-cooled copper crucible inside an electron beam melting furnace, and then evacuate to a high vacuum of 5×10⁻⁶. - 3 Pa.
[0035] S5. A composite scanning trajectory strategy is used for melting, with alternating cycles for high-purity homogenization treatment: S51. First, perform parallel trajectory scanning: the beam moves back and forth along the parallel line direction, the scanning frequency is 100 Hz, the melting power is 50 kW, the melt temperature is maintained at 2400 ℃, and preliminary convection and solute transport are formed in the melt. S52. Then, a sinusoidal trajectory scanning is adopted: the beam moves continuously along a sinusoidal path, the scanning frequency is 150 Hz, the melting power is 60 kW, and the melt temperature is maintained at 2500 ℃; rotation and cross disturbances are generated on the basis of the original flow, forming a more complex melt flow field structure, further enhancing the convection intensity and element diffusion rate, and realizing impurity removal and deep homogenization of composition.
[0036] Throughout the above process, the melting time remains at 15 minutes, and the scanning trajectory switching cycle is 1 minute.
[0037] S5. After melting, the beam is instantly lowered at a rate of 1 A / s to obtain a sample cooled to room temperature; S6. The sample cooled to room temperature is flipped over and remelted. Steps S4-S6 are repeated to obtain a high-purity, homogeneous, refractory, high-entropy alloy.
[0038] The C, N, and O contents of the V-Nb-Ta-Ti refractory high-entropy alloy after two rounds of forward and reverse melting are shown in Table 3 below. It can be seen that the O content decreased significantly, impurities were evenly distributed in different locations, and the C and N contents were both below 100 ppm, indicating good purification effect from electron beam melting. The ingot composition test results are shown in Table 4. The composition distribution in each part of the ingot is uniform (interval of 4-8 mm between the upper, middle, and lower parts), and the composition is accurate, meeting the target composition of VNbTaTi.
[0039] Table 3 Impurity element content
[0040] Table 4. Atomic percentage of each element / %
[0041] Comparative Example 1 A method for preparing high-purity V by electron beam melting 40 Nb 40 Ta 10 Ti 10 The method for producing refractory high-entropy alloys follows the process described in Example 1, except that a direct melting strategy is adopted, and the steps include: S1. Increase the proportion of V component in raw materials by 4% and Ti by 8%, according to V... 44 Nb 31 Ta7Ti 18 Weighing was performed using sponge titanium, electrolytic dendritic vanadium, and niobium shavings, with Ta added as a Ta-Ti (1:1) master alloy. The raw materials were then ultrasonicated in acetone at 100 kHz for 15 min.
[0042] S2. Homogenize the mixture under an inert atmosphere for 20 minutes, then load the mixture into a mold and cold isostatically press it under a pressure of 300 MPa for 5 minutes to form a dense electrode block, ensuring uniform element distribution and stable arc discharge.
[0043] S3. Place the electrode in a vacuum consumable melting furnace, with a vacuum level of 3×10⁻⁶. -1 Pa, melting current 10 kA, melting voltage 35 V, and remelting 3 times to obtain pre-alloyed ingots.
[0044] S4. Place the obtained pre-alloyed ingot in a water-cooled copper crucible inside an electron beam melting furnace, and then evacuate to a high vacuum of 5×10⁻⁶. - 3 Pa.
[0045] S5. Direct melting using a single scanning trajectory: The melt temperature is maintained at 2300℃, and the melting time is 15 minutes.
[0046] S5. After melting, the beam is instantly lowered at a rate of 1 A / s to obtain a sample cooled to room temperature; S6. The sample cooled to room temperature is flipped over and remelted. Steps S4-S6 are repeated to obtain the final refractory high-entropy alloy ingot.
[0047] The C, N, and O contents of the V-Nb-Ta-Ti refractory high-entropy alloy before and after the two-stage melting process are shown in Table 5. It can be seen that the direct melting strategy resulted in significant differences in impurity removal between the edge and middle regions. The ingot composition analysis results are shown in Table 6. Significant segregation was also observed in different parts of the ingot (with intervals of 4-8 mm between the upper, middle, and lower parts), indicating different degrees of element volatilization in different regions and deviations from the target composition.
[0048] Table 5 Impurity element content
[0049] Table 6. Atomic percentage of each element / %
[0050] Comparative Example 2 A method for preparing high-purity VNbTaTi refractory high-entropy alloy by electron beam melting, the process is carried out according to the method of Example 2, the difference being that: the elemental raw materials are directly laid on a cooling bed for electron beam melting, and the steps include: A method for preparing high-purity VNbTaTi refractory high-entropy alloy by electron beam melting, the specific steps of which are as follows: S1. Increase the proportion of V in the raw material by 5% and Ti by 10%, according to V... 30 Nb 15 Ta 20 Ti 35 Weighing was performed using sponge titanium, electrolytic dendritic vanadium, and niobium shavings, with Ta added as a Ta-Ti (1:1) master alloy. The raw materials were then ultrasonicated in acetone at 100 kHz for 15 min.
[0051] S2. Homogenize the mixture under an inert atmosphere for 20 minutes, then load the mixture into a mold and cold isostatically press it under a pressure of 300 MPa for 5 minutes to form a dense electrode block, ensuring uniform element distribution and stable arc discharge.
[0052] S3. Place the electrode in a water-cooled copper crucible inside the electron beam melting furnace, then evacuate to a high vacuum of 5×10⁻⁶. -3 Pa.
[0053] S5. A composite scanning trajectory strategy is used for melting, with alternating cycles for high-purity homogenization treatment: S51. First, perform parallel trajectory scanning: the beam moves back and forth along the parallel line direction, the scanning frequency is 100 Hz, the melting power is 50 kW, the melt temperature is maintained at 2400 ℃, and preliminary convection and solute transport are formed in the melt. S52. Then, a sinusoidal trajectory scanning is adopted: the beam moves continuously along a sinusoidal path, the scanning frequency is 150 Hz, the melting power is 60 kW, and the melt temperature is maintained at 2500 ℃; rotation and cross disturbances are generated on the basis of the original flow, forming a more complex melt flow field structure, further enhancing the convection intensity and element diffusion rate, and realizing impurity removal and deep homogenization of composition.
[0054] During the above process, the melting time is maintained at 15 min, and the scanning trajectory switching cycle is 1 min.
[0055] S5. After melting, the beam is instantly lowered at a rate of 1 A / s to obtain a sample cooled to room temperature; S6. The sample cooled to room temperature is flipped over and remelted. Steps S4-S6 are repeated to obtain a refractory high-entropy alloy ingot.
[0056] The C, N, and O contents of the VNbTaTi refractory high-entropy alloy after two rounds of forward and reverse melting are shown in Table 7 below. It can be seen that the impurity content decreased significantly when a composite scanning trajectory strategy was adopted during melting. The ingot composition test results are shown in Table 8. It is evident that the alloy obtained by electron beam melting of the ingot without vacuum arc remelting pre-alloying of the raw material exhibits severe compositional inhomogeneity (intervals of 4-8 mm between the upper, middle, and lower sections).
[0057] Table 7 Impurity Element Content
[0058] Table 8. Atomic percentage of each element / %
[0059] In summary, the invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the protection scope of this invention.
Claims
1. A method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process, characterized in that: The method steps include: (1) Prepare and clean the raw materials according to the composition of the V-Nb-Ta-Ti refractory high-entropy alloy; (2) Homogeneous mixing is carried out under an inert atmosphere, and the mixture is loaded into a mold for cold isostatic pressing to obtain a dense electrode block; (3) Place the electrode block in a vacuum consumable melting furnace and melt it 2-3 times to obtain a pre-alloyed ingot; (4) Place the pre-alloyed ingot in a water-cooled copper crucible inside the electron beam melting furnace and evacuate it to 1.5 × 10⁻⁶. - Below 2 Pa, parallel trajectory scanning and sinusoidal trajectory scanning are used for periodic alternating processing. After melting, the beam is instantly lowered and cooled to obtain the alloy after melting on one side. (5) Flip the alloy after one side has been melted and repeat step (4) to obtain a high-purity V-Nb-Ta-Ti refractory high-entropy alloy; In step (1), the V-Nb-Ta-Ti refractory high entropy alloy is composed of four elements: V, Nb, Ta, and Ti. The atomic percentage content of each element is 2% to 50%, and the atomic percentage content of Ta is less than that of Ti. The raw material Ta is added in the form of TaTi master alloy, and V, Nb and the balance Ti are added in the form of elemental vanadium, elemental niobium and elemental titanium, and the amount of elemental titanium and elemental vanadium is 2% to 30% excess.
2. A method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process as described in claim 1, characterized in that: In step (1), the atomic percentage content of V is 20%~50%, the atomic percentage content of Nb is 15%~35%, the atomic percentage content of Ta is 5%~20%, and the atomic percentage content of Ti is 10%~35%; the molar ratio of Ta to Ti in the TaTi master alloy is 1:
1.
3. A method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process as described in claim 1 or 2, characterized in that: In step (1), during cleaning, the raw material is ultrasonically treated in propanol for 15-20 minutes.
4. A method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process as described in claim 1, characterized in that: In step (2), the homogenization mixing time is 10~20 min.
5. A method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process as described in claim 1 or 4, characterized in that: In step (2), the cold isostatic pressure is 200~600MPa and the holding time is 3~5min.
6. A method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process as described in claim 1, characterized in that: In step (3), during smelting, the vacuum degree inside the furnace is less than or equal to 5 × 10⁻⁶. -1 Pa, melting current is 8~12kA, melting voltage is 20~35V.
7. A method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process as described in claim 1, characterized in that: In step (4), during parallel trajectory scanning, the beam moves back and forth along the parallel line direction, with a scanning frequency of 50~200Hz, a melting power of 20~60kW, and a melt temperature maintained at 2000~2500℃; during sinusoidal trajectory scanning, the beam moves continuously along the sinusoidal path, with a scanning frequency of 100~300Hz, a melting power of 30~70kW, and a melt temperature maintained at 2200~2800℃; preferably, during parallel trajectory scanning, the beam moves back and forth along the parallel line direction, with a scanning frequency of 50~100Hz, a melting power of 40~50kW, and a melt temperature maintained at 2300~2400℃; during sinusoidal trajectory scanning, the beam moves continuously along the sinusoidal path, with a scanning frequency of 150~250Hz, a melting power of 60~70kW, and a melt temperature maintained at 2500~2600℃.
8. A method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process as described in claim 1 or 7, characterized in that: In step (4), the alternating treatment cycle is 1~3 min, and the overall smelting time is 5~30 min.
9. A method for preparing high-purity V-Nb-Ta-Ti refractory high-entropy alloys using a dual-process as described in claim 1 or 7, characterized in that: In step (4), the electron gun beam current is instantaneously reduced to 0 at a rate of 0.8~1 A / s.
10. A high-purity V-Nb-Ta-Ti refractory high-entropy alloy, characterized in that: It is prepared by the method described in any one of claims 1 to 9.