A method for stepwise collaborative preparation of tin-titanium alloy rods for superconducting applications

Abstract

This invention relates to a stepwise synergistic method for preparing tin-titanium alloy rods for superconducting applications, belonging to the field of superconducting material preparation. Addressing the problems of tin volatility, component segregation, high impurity content, and poor process repeatability caused by large melting point differences in tin-titanium alloy smelting, this invention employs a method of raw material preparation and pretreatment → vacuum suspension melting → stepwise feeding and alloying → refining and homogenization → casting → post-treatment. This invention effectively suppresses tin volatilization, achieves good batch consistency, and is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of superconducting material preparation, specifically relating to a method for stepwise synergistic preparation of tin-titanium alloy rods for superconducting applications. Background Technology

[0002] Superconducting materials have broad application prospects in fields such as power transmission, magnetic levitation transportation, and medical imaging. Among them, tin-based alloys, as an important low-temperature superconducting material system, have attracted widespread attention due to their high critical transition temperature and good processing performance. Tin-titanium alloys, with their excellent superconducting properties and relatively low cost, have become one of the most promising practical superconducting materials.

[0003] Currently, the mainstream preparation methods for tin-titanium alloys include: 1. Traditional smelting method: Smelting is carried out under atmospheric or protective atmosphere. The equipment is simple and the cost is low, but oxidation is severe and many impurities are introduced. 2. Arc melting method: Smelting is carried out by arc heating under inert gas protection. The degree of oxidation is reduced to some extent, but the temperature control precision is poor. 3. Vacuum induction melting method: Smelting is carried out by induction heating in a vacuum environment. The oxidation problem is improved to some extent, but the adaptability to alloy systems with large differences in melting point and vapor pressure is poor. CN117845099A discloses a high-strength ultra-low elastic modulus titanium alloy bar and its preparation method. The ingot is prepared by vacuum electromagnetic levitation melting, which significantly improves the uniformity of the upper and lower parts of the ingot. However, this invention is aimed at biomedical titanium alloys. The alloy element ratio is very different from that of tin-titanium alloys used in superconducting applications, and the core problem of tin volatilization is not solved. CN117845080A discloses a tin-titanium alloy ingot and its preparation method, apparatus and application. It improves the uniformity of alloy liquid composition and degassing effect by short-time cooling and changes in magnetic field strength and direction. However, it is not optimized enough in terms of heating and cooling temperature and time parameters, and does not fundamentally solve the problem of composition deviation caused by tin volatilization.

[0004] The shortcomings of existing technologies are as follows: 1. Traditional smelting methods are carried out in atmospheric or protective atmospheres, resulting in severe oxidation, uneven composition, and high impurity content, which seriously affects the superconducting properties of the materials; 2. The temperature of the electric arc melting method is difficult to control precisely, and tin is easily lost through volatilization, causing the alloy composition to deviate from the design value; 3. For alloy systems such as tin and titanium, which have large differences in melting points (titanium melting point 1668℃, tin melting point 231.9℃) and vapor pressures, the vacuum induction melting method still cannot avoid a large amount of tin volatilization, making composition control difficult; 4. Tin-titanium alloys prepared by existing methods are prone to compositional segregation and uneven microstructure, resulting in large fluctuations in material properties; 5. Traditional smelting processes have poor repeatability, and the performance of different batches of products varies significantly, making it difficult to ensure product consistency and stability. Summary of the Invention

[0005] This invention provides a stepwise synergistic method for preparing tin-titanium alloy rods for superconducting applications, aiming to solve at least one of the following problems in the prior art: easy volatilization and loss of tin element, uneven microstructure of tin-titanium alloy, severe component segregation, high impurity content in alloy melt, and poor repeatability of traditional smelting processes.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for stepwise collaborative preparation of tin-titanium alloy rods for superconducting applications, comprising the following steps: S1. Raw material preparation and pretreatment: High-purity metallic titanium and metallic tin are selected as raw materials, wherein the purity of metallic titanium is ≥99.99% and the purity of metallic tin is ≥99.99%; they are processed into titanium particles and tin particles respectively; the surface of the raw materials is cleaned; S2. Vacuum Suspension Melting: Evacuate the vacuum melting chamber to a vacuum level of 1×10⁻⁶. -3 Below Pa, high-purity argon gas with a purity ≥99.999% is introduced as a protective gas; the titanium particles are first melted using suspension melting technology; S3. Stepwise feeding and alloying: After the titanium particles have completely melted and reached a stable temperature, the system pressure is increased; preheated tin is added to the titanium melt to form an alloy melt; S4. Refining and homogenization: Homogenization is performed using a magnetic field. The temperature range is controlled and adjusted by the magnetic field to make the temperature field distribution of the alloy melt uniform, and the temperature difference is controlled within ±10℃. S5. Casting: The homogenized alloy melt is poured into a mold preheated to 300-400℃ and ingots are formed by rapid solidification technology; S6. Subsequent processing: The ingot is subjected to vacuum homogenization annealing, with the vacuum degree controlled at 1×10⁻⁶. -3 Below Pa; the ingot is formed into a bar of the required specifications by hot extrusion process; and finally vacuum heat treatment is performed to obtain a tin-titanium alloy bar for superconducting applications.

[0007] Furthermore, in step S1, the raw material is processed into particles with a diameter of 8-12 mm and a length of 30-50 mm to facilitate suspension melting.

[0008] Furthermore, in S2, the melting temperature of titanium is controlled at 1500-1800℃ during suspension melting, and the temperature is maintained for 5-15 minutes.

[0009] Furthermore, in S3, the system pressure is increased to 0.5-0.8 atmospheres.

[0010] Furthermore, in step S3, the rate at which metallic tin is added to the titanium melt is 5-20 g / min; the melt temperature is 1300-1500℃ during the addition process; after the tin is added, the alloy melt temperature is maintained at 1500-1800℃.

[0011] Furthermore, in S4, the magnetic field power range is 120-140kW, the power adjustment speed is 5-10kW / min, and the homogenization processing time is 10-15 minutes.

[0012] Furthermore, in S5, the pouring temperature is 1000-1300℃; the controlled cooling rate of the rapid solidification technology is 10. 2 -10 4 K / s, cooled to room temperature under the protection of high-purity argon or nitrogen.

[0013] Furthermore, in step S6, the subsequent processing involves vacuum homogenization annealing at a temperature of 400-600℃ for 2-8 hours.

[0014] Furthermore, in step S6, the final vacuum heat treatment temperature is 200-400℃, and the time is 1-4 hours.

[0015] On the other hand, the present invention provides a tin-titanium alloy rod obtained by the preparation method described above, wherein the tin content deviation of the tin-titanium alloy rod is ≤±0.5%, the oxygen content is less than 45ppm, the nitrogen content is less than 25ppm, and the average grain size reaches a fine grain structure of 18-32μm.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The method of this invention utilizes a step-by-step feeding process of melting titanium first and then adding tin, combined with a full-process vacuum / protective atmosphere. Melting titanium first eliminates the long-term exposure of tin at high temperatures from the source. Specifically, the system pressure is increased. By melting titanium first and then adding tin, the volatilization loss of tin at high temperatures is effectively suppressed, resulting in a highly homogeneous alloy. Vacuum suspension melting significantly reduces the content of oxygen and nitrogen impurities. Magnetic field homogenization treatment ensures accurate alloy composition and obtains a uniform and fine-grained structure. The rapid solidification technology of casting can greatly suppress macroscopic segregation and grain coarsening of tin. Vacuum homogenization annealing further eliminates the internal stress and micro-region segregation generated by rapid solidification. Finally, vacuum heat treatment promotes the stable precipitation of the superconducting phase. At the same time, the process has good repeatability and stable performance between batches.

[0017] 2. The suspension melting technology of this invention controls the melting of titanium first, at a melting temperature of 1500-1800℃, and holds it at that temperature for 5-15 minutes. This ensures complete melting of titanium while preventing excessive volatilization. The holding time also ensures a uniform temperature field. This condition works closely with the subsequent pressurization and tin addition step: the uniform and stable titanium melt prevents tin segregation due to localized cold zones during tin addition, while also preventing excessive tin volatilization caused by excessively high temperatures, thus controlling the alloy composition deviation within ±0.5%.

[0018] 3. The stepwise feeding and alloying method of this invention directly increases the boiling point of tin by raising the system pressure to 0.5-0.8 atmospheres, thus suppressing the volatilization loss of tin during addition and subsequent alloying. This pressure range, combined with the stepwise feeding method of melting titanium first and then adding tin, allows tin to be smoothly integrated into the titanium melt under this pressure, significantly reducing the deviation in tin content, while avoiding splashing and ensuring batch-to-batch composition consistency.

[0019] 4. The stepwise feeding and alloying of this invention can significantly slow down the volatilization rate of tin; raising the temperature to 1500-1800℃ after feeding promotes rapid and complete diffusion and dissolution of tin, avoiding unmelted tin. This combination (feeding rate 5-20g / min, melt temperature 1300-1500℃ during feeding, and maintaining 1500-1800℃ after feeding) is connected with the magnetic field homogenization step to ensure uniform dispersion of tin and maintain good melt fluidity.

[0020] 5. The magnetic field of this invention can drive the alloy melt to form a stable macroscopic convection from the center to the edge with sufficient strength, effectively breaking up the local temperature gradient, making the temperature field of the melt uniform, and precisely controlling the temperature difference within ±10℃; at the same time, it can avoid melt splashing or gas entrapment caused by sudden power changes, and prevent the oxide film on the surface of the alloy melt from breaking due to violent disturbance and re-absorbing oxygen; it ensures that the tin element achieves uniform mixing at the molecular level in the titanium matrix, and allows sufficient time for the full floating and removal of gases and inclusions, thereby obtaining a high-quality melt with small composition deviation and low impurity content, ensuring consistent homogenization and purification effects of different batches of melt, eliminating performance fluctuations caused by local overheating or uneven stirring, and solving the problem of poor repeatability in traditional smelting processes.

[0021] 6. The rapid solidification technology of the present invention cools to room temperature under the protection of high-purity argon or nitrogen, which can significantly reduce the temperature difference and thermal stress between the alloy liquid and the mold, avoid solidification defects such as cracks and shrinkage cavities in the casting, and at the same time, rapid solidification can greatly suppress the macroscopic segregation and grain coarsening of tin, and obtain a fine-grained structure with a uniform average grain size, thereby laying the foundation for the consistency of subsequent superconducting material production.

[0022] 7. This invention utilizes vacuum homogenization annealing to completely relax the residual stress generated by rapid solidification, providing a uniformly structured, stress-free billet for subsequent hot extrusion and preventing extrusion cracking. Finally, vacuum heat treatment further eliminates residual stress and dislocation substructures in the hot-extruded bar. This heat treatment yields a stable superconducting phase, resulting in high-performance superconducting tin-titanium alloy bars with a tin content deviation controlled within ±0.5%, an oxygen content below 45 ppm, a nitrogen content below 25 ppm, and an average grain size of 18-32 μm.

[0023] To more clearly illustrate the technical solutions involved in the embodiments of the present invention or the prior art, the accompanying drawings included in the description of the embodiments or the prior art will be briefly introduced below. It should be noted that these drawings only show some specific embodiments recorded in the present invention and do not cover all possible implementations.

[0024] Figure Labels Figure 1 This is a metallographic structure diagram of the tin-titanium alloy in Example 1; Figure 2 This is a flowchart of the tin-titanium alloy preparation process in Example 1; Figure 3 This is a transverse CT image of the ingot from Example 1; Figure 4 This is a longitudinal CT image of the ingot from Example 1. Detailed Implementation

[0025] The technical solution of the present invention will now be described in detail and comprehensively. It should be noted that the embodiments described are only a part of the present invention and do not cover all embodiments. Furthermore, all other embodiments that can be obtained by those skilled in the art based on the embodiments provided by the present invention without creative effort should also fall within the protection scope of the present invention. In the following embodiments, unless otherwise specified, the instruments and materials used are commercially available.

[0026] Currently, the core technical challenges of mainstream methods for preparing tin-titanium alloys include: 1. Traditional smelting methods are carried out in atmospheric or protective atmospheres, resulting in severe oxidation, uneven composition, and high impurity content, which seriously affects the superconducting properties of the material. 2. The temperature of the electric arc melting method is difficult to control precisely, and tin is easily lost through volatilization, causing the alloy composition to deviate from the design value. 3. For alloy systems like tin and titanium, which have large differences in melting points (titanium melting point 1668℃, tin melting point 231.9℃) and vapor pressures, the vacuum induction melting method still cannot avoid a large amount of tin volatilization, making composition control difficult. 4. Tin-titanium alloys prepared by existing methods are prone to compositional segregation and uneven microstructure, leading to large fluctuations in material properties. 5. Traditional smelting processes have poor repeatability, and the performance of different batches of products varies significantly, making it difficult to ensure product consistency and stability.

[0027] To address the above problems, this invention provides a method for the stepwise collaborative preparation of tin-titanium alloy rods for superconducting applications, comprising the following steps: S1. Raw material preparation and pretreatment: High-purity metallic titanium and metallic tin are selected as raw materials, with the purity of metallic titanium ≥99.99% and the purity of metallic tin ≥99.99%; they are processed into titanium particles and tin particles respectively; the surface of the raw materials is cleaned; S2. Vacuum Suspension Melting: Evacuate the vacuum melting chamber to a vacuum level of 1×10⁻⁶. -3 Below Pa, high-purity argon gas with a purity ≥99.999% is introduced as a protective gas; suspension melting technology is used to melt the titanium particles first; S3. Stepwise feeding and alloying: After the titanium particles are completely melted and reach a stable temperature, the system pressure is increased; preheated tin is added to the titanium melt to form an alloy melt. S4. Refining and Homogenization: Homogenization is achieved by using a magnetic field. The temperature range is controlled and adjusted by the magnetic field to ensure a uniform temperature field distribution in the alloy melt, with the temperature difference controlled within ±10℃. S5. Casting: The homogenized alloy melt is poured into a mold preheated to 300-400℃ and ingots are formed by rapid solidification technology; S6. Subsequent processing: The ingot is subjected to vacuum homogenization annealing, with the vacuum degree controlled at 1×10⁻⁶. -3 Below Pa; the ingot is formed into a bar of the required specifications by hot extrusion process; and finally vacuum heat treatment is performed to obtain a tin-titanium alloy bar for superconducting applications.

[0028] This invention first pre-treats high-purity titanium and tin raw materials through granulation and ultrasonic cleaning. Then, high-melting-point titanium is melted separately in a vacuum environment using suspension melting technology. After the titanium is completely melted, the system pressure is increased, and preheated tin is added to the titanium melt to form an alloy melt. Subsequently, a magnetic field is used for homogenization, and the temperature difference of the melt is controlled within ±10℃. The alloy melt is then poured into a preheated mold, and finally, the ingot undergoes vacuum homogenization annealing, hot extrusion, and final vacuum heat treatment. Through the step-by-step feeding of titanium first and then tin, combined with the synergy of vacuum / protective atmosphere throughout the process, the volatilization loss of tin at high temperatures is effectively suppressed, and the deviation of the alloy tin content is controlled within ±0.5%. The magnetic field homogenization treatment eliminates component segregation, resulting in a uniform and fine-grained structure. The suspension melting and multi-stage vacuum lock design significantly reduce the content of oxygen and nitrogen impurities. At the same time, the process has good repeatability and stable performance between batches.

[0029] Furthermore, in S1, the raw materials are processed into particles with a diameter of 8-12 mm and a length of 30-50 mm to facilitate suspension melting.

[0030] Furthermore, in S1, the surface of the raw material is ultrasonically cleaned for 5-10 minutes with anhydrous ethanol or acetone to remove oxides and oil stains, and then dried for later use.

[0031] Step S1 involves selecting titanium and tin with a purity ≥99.99%, processing them into particles with a diameter of 8-12 mm and a length of 30-50 mm, and then subjecting them to 5-10 minutes of ultrasonic cleaning and drying. This significantly reduces the content of harmful impurities such as oxygen and nitrogen, ensuring superconducting performance. The appropriate particle size satisfies the requirements for suspension stability and rapid melting in suspension melting, while avoiding crucible contamination due to excessively large particles or the risk of splashing and spontaneous combustion due to excessively small particles. Ultrasonic cleaning combined with drying thoroughly removes surface oxide films and oil stains, reduces gas release during melting, and ensures a high vacuum environment. If the purity is below 99.99%, impurities (especially oxygen and iron) exceeding the specified particle size can easily cause sedimentation or uneven melting. If the size is too small, the surface area will be too large, leading to severe oxidation and even causing titanium powder combustion. Insufficient cleaning time may result in residual oxides causing oxygen content to exceed 500 ppm, while excessive cleaning time will over-corrode the tin surface and reduce efficiency. Without drying, residual solvents will decompose in the vacuum, leading to excessive hydrogen content, hydrogen embrittlement, and microcracks. Therefore, the raw materials are processed into particles with a diameter of 8-12 mm and a length of 30-50 mm, such as diameters of 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, and lengths of 30 mm, 35 mm, 40 mm, 45 mm, and 50 mm. The surface of the raw materials is then ultrasonically cleaned with anhydrous ethanol or acetone for 5-10 minutes, such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, and 10 minutes.

[0032] Furthermore, in S2, the melting temperature of titanium is controlled at 1500-1800℃ during suspension melting, and the temperature is held for 5-15 minutes.

[0033] In step S2, the vacuum melting chamber is evacuated to 1×10⁻⁶ ppm. -3Below Pa, adsorbed gases on the raw material surface can be effectively removed, oxygen partial pressure reduced, titanium oxidation prevented at high temperatures, and conditions created for subsequent precise pressure determination. Introducing high-purity argon gas (≥99.999%) further dilutes residual oxygen and nitrogen, maintains a positive pressure environment, prevents air infiltration, and ensures the stability of suspension melting. Suspension melting technology is used to melt metallic titanium first, preventing titanium from contacting the crucible and eliminating crucible material contamination. More importantly, it melts high-melting-point titanium (before tin is added) at the source, fundamentally eliminating the subsequent tin volatilization problem. Controlling the titanium melting temperature to 1500-1800℃ and holding it for 5-15 minutes ensures complete titanium melting while preventing excessive volatilization. The holding time ensures a uniform temperature field. This condition closely coordinates with the subsequent pressure-boosting and tin-addition steps: a uniform and stable titanium melt prevents tin solidification segregation due to localized cold zones during tin addition, while also preventing excessive tin volatilization due to excessive temperature, allowing alloy composition deviations to be controlled within ±0.5%. If the vacuum degree is higher than 1×10⁻⁶, -3 Higher pressure (Pa) leads to increased residual oxygen and nitrogen content, which severely oxidizes the titanium melt, resulting in excessive oxygen content in the alloy. If the argon purity is too low, the introduced oxygen and water vapor will contaminate the melt, reducing its superconducting properties. Without suspension melting or pre-melting of titanium, crucible contamination and tin volatilization are unavoidable, causing large deviations in tin content and large grain size. Too low a melting temperature may result in incomplete melting and uneven composition, while too high a temperature exacerbates titanium volatilization and shortens equipment lifespan. Insufficient holding time leads to an uneven temperature field in the titanium melt, while excessive holding time increases energy consumption and oxidation risk. Therefore, the melting temperature of titanium should be controlled at 1500-1800℃, with a holding time of 5-15 minutes. Examples include 1500℃, 1550℃, 1600℃, 1650℃, 1700℃, 1750℃, and 1800℃, with holding times of 5 minutes, 10 minutes, and 15 minutes, respectively.

[0034] Furthermore, in S3, the system pressure increases to 0.5-0.8 atmospheres.

[0035] Furthermore, in S3, the rate at which metallic tin is added to the titanium melt is 5-20 g / min; the melt temperature is 1300-1500℃ during the addition process; after the tin is added, the alloy melt temperature is maintained at 1500-1800℃.

[0036] Step S3. Stepwise feeding and alloying: By increasing the system pressure to 0.5-0.8 atmospheres, the boiling point of tin is directly increased, suppressing tin volatilization loss during addition and subsequent alloying. This pressure range, combined with the stepwise feeding method of melting titanium first and then adding tin, ensures that tin is smoothly integrated into the titanium melt, significantly reducing tin content deviation, while avoiding splashing and ensuring batch-to-batch composition consistency.

[0037] Tin is preheated to 200-250℃ and added to the titanium melt at a rate of 5-20 g / min to ensure a smooth addition and avoid molten splashing. The relatively low temperature during addition (1300-1500℃) significantly slows down the tin's volatilization rate, effectively suppressing tin volatilization and ensuring stable and uniform alloying, avoiding molten splashing and localized overcooling. Controlling the melt temperature at 1300-1500℃ during addition and maintaining it at 1500-1800℃ after addition, followed by a rise to 1500-1800℃ after addition, promotes rapid and complete diffusion and dissolution of tin, preventing unmelted tin. This approach balances sufficient tin dissolution with good flowability of the titanium melt, resulting in a highly homogeneous alloy with a compositional deviation of ≤±0.5%. Furthermore, this combination (addition rate 5-20 g / min, melt temperature 1300-1500℃ during addition, and maintaining 1500-1800℃ after addition) is integrated with the magnetic field homogenization step, ensuring uniform tin dispersion and maintaining good melt flowability. If the system pressure is too low, tin volatilization loss increases dramatically, causing the tin content to deviate significantly from the design value; if the pressure is too high, the equipment sealing requirements become excessive without any additional benefit. If the tin preheating temperature is too low, the large temperature difference will cause violent splashing of the melt, while if it is too high, the oxidation of the tin surface will accelerate, introducing more oxides. If the feeding rate is too low, the high-temperature melting time will be excessively prolonged, exacerbating tin volatilization; if it is too high, it will easily cause localized overcooling or unmelted tin nuclei, leading to segregation. If the melt temperature is too low during the feeding process, the high viscosity will prevent the tin from being evenly dispersed; if it is too high, tin volatilization will increase significantly. If the melt temperature is kept too low after the tin is added, the melt may solidify prematurely; if it is too high, energy will be wasted and volatilization will increase. Therefore, the above parameter ranges are the key to achieving precise control of the tin-titanium alloy composition. Therefore, the system pressure is increased to 0.5-0.8 atmospheres, exemplarily 0.5 atmospheres, 0.6 atmospheres, 0.7 atmospheres, and 0.8 atmospheres; metallic tin preheated to 200-250°C is added to the titanium melt, exemplarily 200°C, 210°C, 220°C, 230°C, 240°C, and 250°C; the feeding rate is controlled at 5-20 g / min, exemplarily 5 g / min, 10 g / min, 15 g / min, and 20 g / min. g / min; During the feeding process, control the melt temperature at 1300-1500℃, for example 1300℃, 1350℃, 1400℃, 1450℃, 1500℃; After the tin is added, maintain the melt temperature at 1500-1800℃, for example 1500℃, 1550℃, 1600℃, 1650℃, 1700℃, 1750℃, 1800℃.

[0038] Furthermore, in S4, the magnetic field power ranges from 120 to 140 kW, the power adjustment speed is 5 to 10 kW / min, and the homogenization time is 10 to 15 minutes.

[0039] In step S4, a magnetic field is used for homogenization. By precisely controlling the temperature range of the melt through magnetic field control, the alloy liquid can be driven to produce orderly macroscopic flow without contact with the melt. This forcibly eliminates local overheating and undercooling areas caused by uneven heating or natural convection, rapidly unifying the temperature field of the entire molten pool, with the temperature difference stably controlled within ±10℃. First, the uniform temperature distribution effectively suppresses the accelerated volatilization of tin in local high-temperature areas, further ensuring the accuracy of the alloy composition (tin content deviation can be controlled within ±0.5%). Second, it eliminates compositional segregation and thermal stress caused by temperature gradients, avoiding the formation of macroscopic segregation or cracks during solidification. Finally, the stable temperature field provides uniform initial conditions for subsequent rapid solidification, helping to obtain ingots with uniform grain size and dense structure, thereby significantly improving the superconducting critical current density and batch consistency of the tin-titanium alloy rods used in the subsequent preparation of superconducting wires. Compared with traditional melting methods without magnetic field control, magnetic field treatment significantly improves the uniformity of the temperature field.

[0040] In the S4 refining and homogenization step, controlling the magnetic field power range to 120-140 kW, adjusting the speed to 5-10 kW / min, and setting the processing time to 10-15 minutes allows for a sufficiently strong drive to form stable macroscopic convection from the center to the edge of the alloy melt, effectively breaking up local temperature gradients and ensuring a uniform temperature field distribution with precise temperature difference control within ±10℃. Simultaneously, the 5-10 kW / min adjustment speed avoids melt splashing or gas entrapment caused by sudden power changes, preventing the oxide film on the alloy melt surface from rupturing due to severe disturbances and subsequent oxygen reabsorption. The 10-15 minute processing time ensures that tin elements achieve molecular-level uniform mixing in the titanium matrix and allows sufficient time for the full flotation and removal of gases and inclusions, resulting in a high-quality melt with small compositional deviations and low impurity content. This ensures consistent homogenization and purification effects across different batches of melt, eliminates performance fluctuations caused by localized overheating or uneven stirring, and solves the problem of poor repeatability in traditional smelting processes. If the power of the magnetic field is too low, the electromagnetic force cannot penetrate the entire molten pool, and the central area is prone to stagnation, resulting in an uneven temperature field and a temperature difference that may expand to ±30℃ or more, leading to localized overcooling or overheating and severe compositional segregation. If the power is too high, the surface of the melt will tumble violently or even splash, increasing contact with the residual atmosphere, causing secondary oxidation and accelerated tin volatilization, and may also damage the equipment coils. If the adjustment speed is too fast, it will generate impact electromagnetic force, inducing melt splashing or slag entrapment, affecting the purity of the alloy. If the adjustment speed is too slow, it will prolong the high-power application time, increasing tin volatilization loss and energy consumption. If the processing time is too short, macroscopic convection and impurity flotation will be insufficient, the temperature field and composition field will not be uniform, and segregation cannot be effectively eliminated. If the processing time is too long, the further improvement effect is limited, and the prolonged high-temperature stirring may cause trace contaminants from the crucible wall to dissolve into the melt, reducing the purity of the alloy. Therefore, the power range of the magnetic field is controlled at 120-140 kW, the adjustment speed is set at 5-10 kW / min, and the processing time is set at 10-15 minutes. Examples include 120 kW, 125 kW, 130 kW, 135 kW, and 140 kW; the adjustment speed is set at 5 kW / min, 6 kW / min, 7 kW / min, 8 kW / min, 9 kW / min, and 10 kW / min; and the processing time is set at 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, and 15 minutes.

[0041] Furthermore, in S5, the pouring temperature is 1000-1300℃; the controlled cooling rate of the rapid solidification technology is 10. 2 -10 4 K / s, cooled to room temperature under the protection of high-purity argon or nitrogen.

[0042] Step S5 involves preheating the mold to 300-400℃, setting the pouring temperature to 1000-1300℃, and using a 10²-10...4 K / s rapid solidification technology, cooled under the protection of high-purity argon or nitrogen, can significantly reduce the temperature difference and thermal stress between the alloy liquid and the mold, avoiding solidification defects such as cracks and shrinkage cavities in the casting. At the same time, rapid solidification can greatly suppress macroscopic segregation and grain coarsening of tin, and obtain a fine-grained structure with uniform average grain size, thus laying the foundation for subsequent hot working and consistency of superconducting properties.

[0043] Specifically, this invention uses 10 2 -10 4 Rapid solidification technology using K / s precisely controls the cooling rate to achieve a fine-grained microstructure. First, the mold is preheated to 300–400℃, while the pouring temperature is controlled at 1000–1300℃ to maintain a moderate, non-drastic temperature difference between the alloy melt and the mold, preventing cracks caused by rapid cooling. Immediately after pouring, forced cooling is performed under high-purity argon or nitrogen protection. Utilizing the high thermal conductivity of the mold itself (especially for copper or graphite materials) and the convective heat transfer of the protective gas, rapid solidification technology is employed to precisely control the cooling rate at 10²–10⁻⁶ K / s. 4 Within the K / s range, at this cooling rate, the alloy melt exhibits high undercooling and a significantly increased nucleation rate. Simultaneously, tin atoms do not have sufficient time for long-range diffusion and macroscopic segregation, strongly suppressing grain growth. This results in a uniform, fine-grained structure with an average grain size of 18-25 μm, effectively avoiding the coarse grains and tin segregation that occur under traditional slow solidification conditions. This lays the microstructural foundation for subsequent hot working and consistent superconducting properties. If the mold preheating temperature is too low, the alloy melt will produce a chilling layer and hot cracks upon contact with the cold mold; if it is too high, the cooling rate decreases, and grains are prone to growth. If the pouring temperature is too low, the melt fluidity deteriorates, leading to incomplete filling; if it is too high, it will exacerbate tin volatilization and mold interface reactions. If the cooling rate is too low, it cannot effectively suppress grain coarsening and compositional segregation, resulting in grain sizes exceeding 100 μm and uneven tin distribution; if it is too high, it may produce amorphous or metastable phases, making subsequent hot working difficult and even causing microcracks. Therefore, the pouring temperature described in S5 is 1000-1300℃; rapid solidification technology is used, and the cooling rate is controlled at 10. 2 -10 4 K / s, exemplary pouring temperatures are 1000℃, 1050℃, 1150℃, 1200℃, 1250℃, and 1300℃, and the cooling rate is controlled at 10 K / s. 2 K / s, 10 3 K / s, 10 4 K / s.

[0044] Furthermore, in S6, the subsequent processing is: vacuum homogenization annealing at a temperature of 400-600℃ for 2-8 hours.

[0045] Furthermore, in S6, the final vacuum heat treatment temperature is 200-400℃, and the time is 1-4 hours.

[0046] Step S6 involves vacuum homogenization annealing of the ingot, with the vacuum level controlled at 1×10⁻⁶. -3Below Pa, vacuum homogenization annealing eliminates internal stress and micro-segregation caused by rapid solidification, and further homogenizes the diffusion of tin. Simultaneously, the high vacuum environment prevents surface oxidation of the alloy, resulting in a uniform, segregation-free cast billet. The hot extrusion process, combined with a hot-fitting mold design, reduces temperature drop and friction between the billet and the mold, ensuring dimensional accuracy and surface quality of the bar. Hot deformation also refines the grains and closes internal micropores. Vacuum homogenization annealing utilizes a high vacuum environment to prevent surface oxidation of the ingot. The temperature range of 400-600℃ activates the solid-state diffusion of tin atoms in the titanium matrix, eliminates dendritic segregation and internal stress caused by rapid solidification, without causing grain coarsening or localized melting. A holding time of 2-8 hours ensures sufficient and uniform diffusion of tin, resulting in homogenized ingot composition. Vacuum homogenization annealing completely relaxes the residual stress generated by rapid solidification, providing a uniform, stress-free billet for subsequent hot extrusion and preventing extrusion cracking. Hot extrusion involves heating the ingot to the extrusion temperature and then rapidly transferring it into a preheated die. This significantly reduces the temperature difference and heat loss between the billet and the die, lowers deformation resistance, and prevents extrusion cracks. Simultaneously, the intense stress breaks down residual coarse grains and closes micropores, resulting in dense, fine-grained, and dimensionally precise rods. Final vacuum heat treatment (200-400℃, 1-4h) at a lower temperature further eliminates residual stress and dislocation substructures in the hot-extruded rods. This heat treatment yields a stable superconducting phase, resulting in high-performance tin-titanium alloy rods with tin content deviations controlled within ±0.5%, oxygen content below 45ppm, nitrogen content below 25ppm, and an average grain size of 18-32μm. If the annealing temperature is too low, stress relief and inhomogenization are incomplete, and segregation remains within the alloy. If it is too high, grain coarsening or even the appearance of a liquid phase occurs, deteriorating performance. Insufficient annealing time leads to inadequate homogenization, while excessive annealing time increases energy consumption and may cause secondary oxidation. If the vacuum level is too high, residual oxygen will cause surface oxidation, contaminating the alloy. If hot extrusion does not employ a die-fitting design, the billet cools rapidly, exhibits high deformation resistance, and is prone to cracking and dimensional deviations. If the final heat treatment temperature is too low, it cannot effectively stabilize the superconducting phase; if it is too high, it may cause grain growth or superconducting phase decomposition. Insufficient time yields poor results, while excessive time leads to diminishing returns and increased costs. Therefore, in S6, the annealing temperature is 400-600℃, and the time is 2-8 hours, exemplarily 400℃, 450℃, 500℃, 550℃, and 600℃, with times of 2 hours, 4 hours, 6 hours, and 8 hours; the final vacuum heat treatment temperature is 200-400℃, and the time is 1-4 hours, exemplarily 200℃, 250℃, 300℃, 350℃, and 400℃, with times of 1 hour, 2 hours, 3 hours, and 4 hours.

[0047] Furthermore, the hot extrusion process temperature is 700℃~900℃.

[0048] In the hot extrusion process of step S6, controlling the extrusion temperature between 700℃ and 900℃ allows the tin-titanium alloy to achieve good thermoplasticity within this temperature range, significantly reducing deformation resistance and thus enabling the smooth extrusion of dense, dimensionally accurate bars through the die. Simultaneously, this temperature range allows for dynamic recrystallization to refine the grains without causing abnormal grain growth or overheating and decomposition of tin-enriched phases (such as TiSn2). If the extrusion temperature is below 700℃, the alloy's fluidity is poor, deformation resistance increases sharply, and internal cracks or even die blockage are likely to occur. If the temperature is above 900℃, grain coarsening and localized tin volatilization may occur. Therefore, the hot extrusion process temperature is 700℃ to 900℃, with 700℃, 750℃, 800℃, 850℃, and 900℃ being exemplary values.

[0049] On the other hand, the tin-titanium alloy rods obtained by the above preparation method of the present invention have a tin content deviation of ≤±0.5%, an oxygen content of less than 45ppm, a nitrogen content of less than 25ppm, and an average grain size of 18-32μm, forming a fine-grained structure.

[0050] In summary, this invention first pre-treats high-purity titanium and tin raw materials by granulation and ultrasonic cleaning. Then, high-melting-point titanium is melted separately in a vacuum environment using suspension melting technology. After the titanium is completely melted, the system pressure is increased, and preheated tin is added to the titanium melt to form an alloy melt. Subsequently, a magnetic field is used for refining and homogenization, and the temperature difference of the melt is controlled within ±10℃. The alloy melt is then poured into a preheated mold. Finally, the ingot is subjected to vacuum homogenization annealing, hot extrusion, and final vacuum heat treatment. By employing the step-by-step feeding method of "melting titanium first and then adding tin" in conjunction with the synergistic effect of vacuum / protective atmosphere throughout the entire process, melting titanium first eliminates the long-term exposure of tin at high temperatures from the source; increases the system pressure; and effectively suppresses the volatilization loss of tin at high temperatures by melting titanium first and then adding tin, resulting in a highly homogeneous alloy. Suspension melting and multi-stage vacuum lock design significantly reduce the content of oxygen and nitrogen impurities; magnetic field homogenization treatment ensures the accuracy of alloy composition and obtains a fine-grained structure with uniform grain size; rapid solidification technology for casting produces ingots that can greatly suppress macroscopic segregation and grain coarsening of tin, resulting in a fine-grained structure with uniform average grain size; vacuum homogenization annealing further eliminates the internal stress and micro-area segregation generated by rapid solidification, and finally, vacuum heat treatment promotes the stable precipitation of the superconducting phase. Meanwhile, the process has good repeatability and stable performance between batches; the final alloy has a tin content deviation that can be controlled within ±0.5%, an oxygen content of less than 45ppm, a nitrogen content of less than 25ppm, an average grain size of 18-32μm, and Sn and Ti elements are evenly distributed throughout the ingot. No obvious enrichment or depletion regions of elements were observed, indicating that the alloy ingot has a uniform composition and no obvious segregation. This lays the foundation for the consistency of subsequent hot working and superconducting performance. The product has good batch consistency and is suitable for industrial mass production.

[0051] The following is a further explanation with reference to specific embodiments: Example 1 S1. Raw material preparation and pretreatment: High-purity 99.99% titanium and 99.99% tin are selected as raw materials, processed into titanium particles with a diameter of 11mm and a length of 46mm, ultrasonically cleaned with ethanol for 6 minutes, and dried for later use.

[0052] S2. Vacuum Suspension Melting: The titanium particles are melted first using suspension melting technology; the melting temperature of titanium is controlled at 1750℃ and held for 12 minutes.

[0053] S3. Step-by-step feeding and alloying: After the titanium particles are completely melted and reach a stable temperature, the system pressure is increased to 0.75 atmospheres. The preheated tin in the feeding bin is added at a rate of 13g / min. The melt temperature is 1420℃ during the feeding process. After the tin is added, the alloy melt temperature is maintained at 1720℃.

[0054] S4. Refining and homogenization: Homogenization is performed using a magnetic field. The temperature range is controlled and adjusted by the magnetic field to make the temperature field distribution of the alloy melt uniform. The magnetic field power range is 135kW, the power adjustment speed is 6kW / min, and the homogenization time is 11 minutes.

[0055] S5. Casting: The homogenized alloy melt is poured into a mold preheated to 345°C, with a pouring temperature of 1050°C; ingots are formed using rapid solidification technology, with a cooling rate of 10... 3 K / s, rapidly cooled to room temperature under the protection of high-purity argon gas.

[0056] S6. Post-processing: The ingot is subjected to vacuum homogenization annealing, with the vacuum degree controlled at 1×10⁻⁶. -3 Below Pa, vacuum homogenization annealing temperature is 550℃ for 6.5 hours, and Φ25mm rods are produced by hot extrusion at 700℃. Finally, vacuum heat treatment is performed at 355℃ for 3.2 hours to obtain tin-titanium alloy rods for superconducting applications.

[0057] The performance of the superconducting tin-titanium alloy rod prepared in this embodiment was tested: tin content deviation ±0.3%, oxygen content 32ppm, nitrogen content 18ppm, and average grain size 25μm.

[0058] Figure 3 , 4 The Sn and Ti elements are uniformly distributed throughout the ingot, and no obvious enrichment or depletion areas were observed, indicating that the alloy ingot has a uniform composition and no obvious segregation.

[0059] Example 2 This embodiment is similar to the method in Embodiment 1, with the main difference being: S1. Raw material preparation and pretreatment: Select high-purity 99.99% titanium and 99.99% tin, process them into titanium particles with a diameter of 10mm and a length of 40mm, ultrasonically clean them with acetone for 5 minutes, and blow them dry for later use.

[0060] S2. Vacuum Suspension Melting: The titanium particles are melted first using suspension melting technology; the melting temperature of titanium is controlled at 1600℃ and held for 10 minutes.

[0061] S3. Step-by-step feeding and alloying: After the titanium particles are completely melted and reach a stable temperature, the system pressure is increased to 0.6 atmospheres. Metallic tin preheated with the furnace body is added to the feeding bin at a rate of 15g / min. The melt temperature is 1400℃ during the feeding process. After the tin is added, the alloy melt temperature is maintained at 1600℃.

[0062] S4. Refining and homogenization: Homogenization is performed using a magnetic field. The temperature range is controlled and adjusted by the magnetic field to make the temperature field distribution of the alloy melt uniform. The magnetic field power range is 140kW, the power adjustment speed is 7kW / min, and the homogenization time is 13 minutes.

[0063] S5. Casting: The homogenized alloy melt is poured into a mold preheated to 365°C at a casting temperature of 1200°C; ingots are formed using rapid solidification technology with a cooling rate of 10... 3 K / s, rapidly cooled to room temperature under the protection of high-purity nitrogen.

[0064] S6. Post-processing: The ingot is subjected to vacuum homogenization annealing, with the vacuum degree controlled at 1×10⁻⁶. -3 Below Pa, the vacuum homogenization temperature is 500℃ for 7 hours, and Φ25mm rods are produced by hot extrusion at 900℃. Finally, the rods undergo vacuum heat treatment at 300℃ for 3 hours to obtain tin-titanium alloy rods for superconducting applications.

[0065] Performance testing: Tin content deviation ±0.4%, oxygen content 41ppm, nitrogen content 24ppm, average grain size 32μm.

[0066] The CT test of the same example 1 shows that Sn and Ti elements are evenly distributed throughout the ingot, and no obvious enrichment or depletion areas of elements were observed, indicating that the alloy ingot has a uniform composition and no obvious segregation.

[0067] Example 3 This embodiment is similar to the method in Embodiment 1, with the main difference being: S1. Raw material preparation and pretreatment: Select high-purity 99.99% metallic titanium and 99.99% metallic tin, process them into titanium particles with a diameter of 12mm and a length of 50mm, ultrasonically clean them with ethanol for 10 minutes, and blow them dry for later use.

[0068] S2. Vacuum Suspension Melting: The titanium particles are melted first using suspension melting technology; the melting temperature of titanium is controlled at 1800℃ and held for 15 minutes.

[0069] S3. Step-by-step feeding and alloying: After the titanium particles are completely melted and reach a stable temperature, the system pressure is increased to 0.8 atmospheres. The preheated tin in the feeding bin is added at a rate of 20g / min. During the feeding process, the melt temperature is controlled at 1500℃. After the tin is added, the melt temperature is maintained at 1800℃.

[0070] S4. Refining and homogenization: Homogenization is performed using a magnetic field. The temperature range is controlled and adjusted by the magnetic field to make the temperature field distribution of the alloy melt uniform. The magnetic field power range is 140kW, the power adjustment speed is 8kW / min, and the homogenization time is 15 minutes.

[0071] S5. Casting: The homogenized alloy melt is poured into a mold preheated to 400°C, with a casting temperature of 1300°C; ingots are formed using rapid solidification technology, with a cooling rate of 10... 4 Rapidly cool to room temperature at K / s.

[0072] S6. Post-processing: The ingot is subjected to vacuum homogenization annealing, with the vacuum degree controlled at 1×10⁻⁶. -3 Below Pa, vacuum homogenization annealing temperature is 600℃ for 8 hours, and Φ25mm rods are produced by hot extrusion at 800℃. Finally, vacuum heat treatment is performed at 400℃ for 4 hours to obtain tin-titanium alloy rods for superconducting applications.

[0073] Performance testing: Tin content deviation ±0.2%, oxygen content 26ppm, nitrogen content 15ppm, average grain size 18μm.

[0074] The CT test of the same example 1 shows that Sn and Ti elements are evenly distributed throughout the ingot, and no obvious enrichment or depletion areas of elements were observed, indicating that the alloy ingot has a uniform composition and no obvious segregation.

[0075] Example 4 This embodiment is similar to the method in Embodiment 1, with the main difference being: S1. Raw material preparation and pretreatment: Select high-purity 99.99% titanium and 99.99% tin, process them into titanium particles with a diameter of 8mm and a length of 30mm, ultrasonically clean them with ethanol for 8 minutes, and blow them dry for later use.

[0076] S2. Vacuum Suspension Melting: The titanium particles are melted first using suspension melting technology; the melting temperature of titanium is controlled at 1500℃ and held for 5 minutes.

[0077] S3. Step-by-step feeding and alloying: After the titanium particles are completely melted and reach a stable temperature, the system pressure is increased to 0.5 atmospheres. The preheated tin in the feeding bin is added at a rate of 5g / min. During the feeding process, the melt temperature is controlled at 1300℃. After the tin is added, the melt temperature is maintained at 1500℃.

[0078] S4. Refining and homogenization: Homogenization is performed using a magnetic field. The temperature range is controlled and adjusted by the magnetic field to make the temperature field distribution of the alloy melt uniform. The magnetic field power range is 120kW, the power adjustment speed is 5kW / min, and the homogenization time is 10 minutes.

[0079] S5. Casting: The homogenized alloy melt is poured into a mold preheated to 300°C, with a casting temperature of 1000°C; ingots are formed using rapid solidification technology, with a cooling rate of 10... 2 K / s, rapidly cooled to room temperature under the protection of high-purity argon gas.

[0080] S6. Post-processing: The ingot is subjected to vacuum homogenization annealing, with the vacuum degree controlled at 1×10⁻⁶. -3 Below Pa, the vacuum homogenization temperature is 400℃ for 2 hours, and Φ25mm rods are produced by hot extrusion at 750℃. Finally, the rods undergo vacuum heat treatment at 200℃ for 1 hour to obtain tin-titanium alloy rods for superconducting applications.

[0081] Performance testing: Tin content deviation ±0.2%, oxygen content 25ppm, nitrogen content 15ppm, average grain size 22μm.

[0082] The CT test of the same example 1 shows that Sn and Ti elements are evenly distributed throughout the ingot, and no obvious enrichment or depletion areas of elements were observed, indicating that the alloy ingot has a uniform composition and no obvious segregation.

[0083] Comparative Example 1 The method for producing a tin-titanium alloy rod in this comparative example is similar to that in Example 1, except that in step S3, stepwise feeding and alloying: after the titanium particles are completely melted and reach a stable temperature, the system pressure is increased to 0.4 atmospheres; the preheated tin is added at a feeding rate of 4 g / min; the melt temperature is controlled at 1100°C during the feeding process, and after the tin is added, the melt temperature is maintained at 1200°C.

[0084] Performance testing: Tin content deviation ±1.0%, oxygen content 50ppm, nitrogen content 55ppm, average grain size 60μm.

[0085] Comparative Example 2 The method for producing a tin-titanium alloy rod in this comparative example is similar to that in Example 1, except that in step S4, the magnetic field power is adjusted to a power speed of 4 kW / min, and the homogenization time is 10 minutes. The rest is the same as in Example 1.

[0086] Performance testing: Tin content deviation ±1.0%, oxygen content 56ppm, nitrogen content 65ppm, average grain size 62μm.

[0087] Comparative Example 3 The method for producing a tin-titanium alloy rod in this comparative example is similar to that in Example 1, except that in step S5, the homogenized alloy melt is poured into a mold preheated to 200°C; the pouring temperature is controlled at 800°C; the rest is the same as in Example 1.

[0088] Performance testing: Microcracks were found.

[0089] Comparative Example 4 The method for producing a tin-titanium alloy rod in this comparative example is similar to that in Example 1, except that step S5 employs rapid solidification technology, controlling the cooling rate at 10 K / s, and cooling to room temperature under high-purity argon protection. The rest is the same as in Example 1.

[0090] Performance testing: Tin content deviation ±1.0%, oxygen content 50ppm, nitrogen content 55ppm, average grain size 45μm.

[0091] Comparative Example 5 The method for producing a tin-titanium alloy rod in this comparative example is similar to that in Example 1, except that in step S6, the ingot is subjected to vacuum homogenization annealing at a temperature of 300°C for 1 hour; the ingot is then formed into a rod of the required specifications using a hot extrusion process, with the hot working process employing a mold hot fitting design; and a final vacuum heat treatment is performed at a temperature of 100°C for 0.5 hours to obtain a tin-titanium alloy rod for superconducting applications.

[0092] Performance testing: Tin content deviation ±1.0%, oxygen content 54ppm, nitrogen content 57ppm, average grain size 80μm.

[0093] Comparative Example 6 The method for producing a tin-titanium alloy rod in this comparative example is similar to that in Example 1, except that step S3 involves adding titanium and tin particles simultaneously.

[0094] Performance testing: Tin content deviation ±1.3%, oxygen content 56ppm, nitrogen content 68ppm, average grain size 100μm.

[0095] The method of this invention can control the tin content deviation within ±0.5% (optimal ±0.2%), the oxygen and nitrogen contents below 45ppm and 25ppm respectively, and refine the grains to 18-32μm, making it suitable for industrial production.

[0096] Comparative Example 1: Insufficient system pressure failed to effectively suppress tin volatilization; inadequate preheating exacerbated thermal shock and splashing; excessively slow feeding speed prolonged high-temperature exposure time; and excessively low melt temperature resulted in incomplete tin dissolution and poor fluidity. Results: Significant tin volatilization loss occurred, with compositional deviations exceeding ±0.5%, and oxygen and nitrogen content increased substantially.

[0097] Comparative Example 2: The S4 magnetic field power adjustment speed was too slow and the time was too short, failing to form macroscopic convection throughout the molten pool. Tin and titanium segregated due to their density difference. Result: The alloy composition was uneven, with local tin enrichment or depletion, resulting in macroscopic segregation after solidification.

[0098] Comparative Example 3: Low preheating temperature and low pouring temperature led to excessively rapid cooling at the bottom of the alloy ingot, resulting in localized microcracks.

[0099] Comparative Example 4: The cooling rate is too low, which cannot effectively suppress grain coarsening and compositional segregation, resulting in larger grain size and uneven tin distribution.

[0100] Comparative Example 5: The homogenization annealing temperature was too low and the time was too short, which could not eliminate dendrite segregation and internal stress, and the diffusion of tin atoms was insufficient; the final heat treatment temperature was too low and the time was insufficient, resulting in residual work hardening, compositional segregation and residual stress inside the alloy.

[0101] Comparative Example 6 uses the method of adding titanium and tin particles at the same time, which makes crucible contamination and tin volatilization problems unavoidable, resulting in large deviations in tin content and large grain size.

[0102] The technical solutions of this invention are not limited to the specific embodiments described above. Any technical modifications, alterations, substitutions, and variations made to the technical solutions of this invention without departing from the spirit and scope of the claims are within the protection scope of this invention.

Claims

1. A method for stepwise synergistic preparation of tin-titanium alloy rods for superconducting applications, characterized in that, Includes the following steps: S1. Raw material preparation and pretreatment: High-purity metallic titanium and metallic tin are selected as raw materials, wherein the purity of metallic titanium is ≥99.99% and the purity of metallic tin is ≥99.99%; they are processed into titanium particles and tin particles respectively; the surface of the raw materials is cleaned; S2. Vacuum Suspension Melting: Evacuate the vacuum melting chamber to a vacuum level of 1×10⁻⁶. -3 Below Pa, high-purity argon gas with a purity ≥99.999% is introduced as a protective gas; the titanium particles are first melted using suspension melting technology; S3. Stepwise feeding and alloying: After the titanium particles have completely melted and reached a stable temperature, the system pressure is increased; preheated tin is added to the titanium melt to form an alloy melt; S4. Refining and homogenization: Homogenization is performed using a magnetic field. The temperature range is controlled and adjusted by the magnetic field to make the temperature field distribution of the alloy melt uniform, and the temperature difference is controlled within ±10℃. S5. Casting: The homogenized alloy melt is poured into a mold preheated to 300-400℃ and ingots are formed by rapid solidification technology; S6. Subsequent processing: The ingot is subjected to vacuum homogenization annealing, with the vacuum degree controlled at 1×10⁻⁶. -3 Pa below; the ingot is produced into bars of the required specifications using a hot extrusion process; The final vacuum heat treatment yields tin-titanium alloy rods for superconducting applications.

2. The method according to claim 1, characterized in that, In step S1, the raw material is processed into particles with a diameter of 8-12 mm and a length of 30-50 mm to facilitate suspension melting.

3. The method according to claim 1, characterized in that, In step S2, the melting temperature of titanium is controlled at 1500-1800℃ during suspension melting, and the temperature is maintained for 5-15 minutes.

4. The method according to claim 1, characterized in that, In S3, the system pressure increases to 0.5-0.8 atmospheres.

5. The method according to claim 1, characterized in that, In step S3, the rate at which metallic tin is added to the titanium melt is 5-20 g / min; the melt temperature is 1300-1500℃ during the addition process; after the tin is added, the alloy melt temperature is maintained at 1500-1800℃.

6. The method according to claim 1, characterized in that, In S4, the magnetic field power range is 120-140kW, the power adjustment speed is 5-10kW / min, and the homogenization processing time is 10-15 minutes.

7. The method according to claim 1, characterized in that, In S5, the pouring temperature is 1000-1300℃; the controlled cooling rate of the rapid solidification technology is 10. 2 -10 4 K / s, cooled to room temperature under the protection of high-purity argon or nitrogen.

8. The method according to claim 1, characterized in that, In step S6, the subsequent processing is: vacuum homogenization annealing at a temperature of 400-600℃ for 2-8 hours.

9. The method according to claim 1, characterized in that, In step S6, the final vacuum heat treatment temperature is 200-400℃, and the time is 1-4 hours.

10. A tin-titanium alloy rod obtained by the preparation method according to any one of claims 1-9, characterized in that, The tin-titanium alloy rod has a tin content deviation of ≤±0.5%, an oxygen content of less than 45ppm, a nitrogen content of less than 25ppm, and an average grain size of 18-32μm, forming a fine-grained structure.

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