Method for preparing composite green body for niobium-tin superconducting wire based on copper-tin alloy powder

Abstract

The present invention discloses a method for preparing a composite body for niobium-tin superconducting wire based on copper-tin alloy powder. The specific steps are: preparing Cu-Sn-Ti alloy powder by gas atomization; surface treating several pure niobium rods; assembling the Cu-Sn-Ti alloy powder and pure niobium rods in a mold to obtain a Cu-Sn-Ti / Nb rod composite body; and placing the Cu-Sn-Ti / Nb rod composite body in a vacuum rapid hot pressing furnace for thermal-mechanical-electrical synergistic sintering and cooling to obtain a Cu-SnTi / Nb composite body. The composite body for niobium-tin superconducting wire obtained by the present method has improved plasticity, avoiding cracking during subsequent multi-pass drawing.

Description

Technical Field

[0001] The present invention belongs to the technical field of superconducting material preparation methods, and in particular relates to a method for preparing a composite green body for niobium-tin superconducting wire based on copper-tin alloy powder. Background Art

[0002] Nb3Sn is a typical intermetallic compound with an A15-type crystal structure. It has a high superconducting transition temperature (Tc) of 18.3K and an upper critical magnetic field (Hc) of 27T. Nb3Sn superconducting wires are primarily prepared using the internal tin method and the bronze method. The internal tin method produces Nb3Sn superconducting wires with a higher critical current density, but due to severe core-wire coupling, its AC losses also increase. The bronze method offers a moderate critical current density, excellent mechanical properties, and low AC losses, making it widely used in high-magnetic-field superconducting applications such as nuclear fusion reactors and nuclear magnetic resonance spectrometers.

[0003] The main steps of preparing Nb3Sn superconducting wire by the bronze method are: inserting Nb rods into Cu-Sn alloy ingots to obtain a composite green body, hot extruding the composite green body, and then performing multiple drawing passes to obtain CuSn / Nb composite wire; finally, the CuSn / Nb composite wire is subjected to phase-forming heat treatment, and Sn atoms diffuse and combine with Nb to form a Nb3Sn superconducting phase at the interface, ultimately obtaining Nb3Sn superconducting wire.

[0004] At present, the preparation of Nb3Sn superconducting wires by the bronze method has the following bottleneck problems: the performance of Nb3Sn superconducting wires produced by the bronze method is closely related to the content of the Nb3Sn superconducting phase. The higher the content of the Nb3Sn superconducting phase, the better the performance of the superconducting wire. However, the content of the Nb3Sn superconducting phase is closely related to the Sn content in the Cu-Sn alloy. The higher the Sn content in the Cu-Sn alloy, the higher the content of the Nb3Sn superconducting phase obtained. However, the solubility of Sn in Cu is limited, and the maximum solid solubility is 15.8 wt.% at high temperature, and the solid solubility at room temperature is almost 0. Therefore, too high a Sn content in the Cu-Sn alloy will lead to the precipitation of a large amount of tin-rich phase (mainly δ-Cu) in the microstructure of the Cu-Sn alloy at room temperature. 41 Sn 11 phase), deteriorating the plasticity of the Cu-Sn alloy, causing the Cu-Sn alloy to crack easily during the subsequent multi-pass drawing process, which limits the preparation of kilometer-scale high-performance Nb3Sn / Cu superconducting wires. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a composite body for niobium-tin superconducting wire based on copper-tin alloy powder, so as to solve the problem that a large amount of tin-rich phase is easily precipitated in the existing method, thereby deteriorating the plasticity of the copper-tin alloy.

[0006] The technical solution adopted by the present invention is a method for preparing a composite body for niobium-tin superconducting wire based on copper-tin alloy powder, and the specific steps are as follows:

[0007] Step 1, preparing Cu-Sn-Ti alloy powder by gas atomization method;

[0008] Step 2, surface treatment of the pure niobium rod;

[0009] Step 3: assembling Cu-Sn-Ti alloy powder and pure niobium rod in a mold to obtain a Cu-Sn-Ti / Nb rod composite billet;

[0010] Step 4: placing the Cu-Sn-Ti / Nb rod composite blank in a vacuum rapid hot pressing furnace for thermal-mechanical-electrical coordinated sintering, and removing it from the mold after cooling to obtain a CuSnTi / Nb composite blank.

[0011] The present invention is also characterized in that:

[0012] Furthermore, the specific process of step 1 is as follows: oxygen-free copper rod, tin particles and titanium powder are placed in a crucible for smelting, argon gas is filled in the smelting process to protect against oxidation, and after the smelting is completed, the crucible is placed in an electrode induction gas atomization powder spraying furnace and evacuated to a vacuum degree of 2.8×10 -3 Pa, and fill nitrogen into the electrode induction gas atomization powder spraying furnace at an inflation pressure of 35MPa until the pressure in the electrode induction gas atomization powder spraying furnace is not lower than the standard atmospheric pressure. After being filled with nitrogen, the air inlet valve and the air outlet valve of the electrode induction gas atomization powder spraying furnace are opened, the smelting frequency is adjusted to start working, and finally Cu-Sn-Ti alloy powder is obtained;

[0013] Furthermore, the mass percentages of the oxygen-free copper rod, tin particles, and titanium powder are as follows: 15.5% to 18% of tin particles, 0.1% to 0.3% of titanium powder, and the rest being the oxygen-free copper rod, and the sum of the mass percentages of the above components is 100%.

[0014] Furthermore, the specific process of step 2 is: washing the pure niobium rod with deionized water, and placing the washed pure niobium rod in an oven for drying.

[0015] Furthermore, the number of the pure niobium rods is 1 or a multiple of 7.

[0016] Furthermore, the specific process of step 3 is:

[0017] When the number of pure niobium rods is one, the pure niobium rod is placed in a mold, and the pure niobium rod is placed coaxially with the mold, and then the remaining space in the mold is filled with Cu-Sn-Ti alloy powder, and the height of the Cu-Sn-Ti alloy powder is not less than the height of the pure niobium rod, to obtain a Cu-Sn-Ti / Nb rod composite billet;

[0018] When the number of pure niobium rods is a multiple of 7, the first pure niobium rod is placed in the mold, coaxially with the mold, and the remaining pure niobium rods are evenly distributed in the remaining space in the mold, and the center distances between the pure niobium rods are ensured to be equal. Then, the remaining space in the mold is filled with Cu-Sn-Ti alloy powder, and the height of the Cu-Sn-Ti alloy powder filling is not less than the height of the pure niobium rods, to obtain a Cu-Sn-Ti / Nb rod composite billet.

[0019] Furthermore, the inner diameter of the mold is 40 mm and the height is 70 mm;

[0020] The diameter of each pure niobium rod is 8mm~15mm and the height is 20mm.

[0021] Furthermore, in step 4, the process parameters of the thermal-mechanical-electrical coordinated sintering are: the vacuum degree in the sintering chamber is not greater than 1 Pa, the sintering temperature is 650℃~750℃, the pressure is increased from 0.5T to 3T, and maintained at 3T after the pressure is increased, and the current value is 2300A~2700A.

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention is a method for preparing a composite blank for niobium-tin superconducting wire based on copper-tin alloy powder. First, micron-sized Cu-Sn-Ti alloy powder is prepared. Ultra-high cooling rate is used in the powder preparation process to suppress alloy component segregation and reduce the formation of tin-rich phase. Then, the Cu-Sn-Ti / Nb rod composite blank is subjected to a thermal-mechanical-electrical synergistic sintering treatment to achieve densification of the CuSnTi / Nb composite blank, thereby improving the plasticity of the CuSnTi / Nb composite blank and avoiding cracking in the subsequent multi-pass drawing process for preparing niobium-tin superconducting wire.

[0024] (2) The present invention is a method for preparing a composite blank for niobium-tin superconducting wire based on copper-tin alloy powder. Micron-sized copper-tin powder with high fluidity and low agglomeration tendency is used. Its particle size and plastic deformation ability can form a good synergistic effect with the niobium matrix. Through thermal-mechanical-electrical synergistic sintering, plastic flow and diffusion occur at the interface between the powder particles and the niobium rod, promoting alloying and avoiding microscopic defects caused by excessive agglomeration, thereby improving the tensile properties of the CuSnTi / Nb composite blank.

[0025] (3) The present invention is a method for preparing a composite blank for niobium-tin superconducting wire based on copper-tin alloy powder. The Cu-Sn-Ti / Nb rod composite blank is obtained by filling the gaps between Nb rods with Cu-Sn-Ti alloy powder, which can simplify the process and improve material utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an optical microscope image of the CuSnTi / Nb composite body obtained in Example 1 of the present invention;

[0027] Figure 2 This is an optical microscope image of the CuSnTi / Nb composite body obtained in Example 2 of the present invention;

[0028] Figure 3 This is an optical microscope image of the CuSnTi / Nb composite body obtained in Example 3 of the present invention;

[0029] Figure 4 This is an optical microscope picture of the CuSnTi / Nb composite body obtained in Example 5 of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] The present invention provides a method for preparing a composite body for a niobium-tin superconducting wire based on copper-tin alloy powder, and the specific steps are as follows:

[0032] Step 1, preparing Cu-Sn-Ti alloy powder by gas atomization method;

[0033] The specific process is as follows: oxygen-free copper rods, tin particles, and titanium powder are placed in a crucible for smelting. Argon gas is filled in the crucible to protect against oxidation. After the smelting is completed, the crucible is placed in an electrode induction gas atomization powder spraying furnace and evacuated to a vacuum degree of 2.8×10 -3 Pa, and fill nitrogen into the electrode induction gas atomization powder spraying furnace at an inflation pressure of 35MPa until the pressure in the electrode induction gas atomization powder spraying furnace is not lower than the standard atmospheric pressure. After being filled with nitrogen, the air inlet valve and the air outlet valve of the electrode induction gas atomization powder spraying furnace are opened, the smelting frequency is adjusted to start working, and finally Cu-Sn-Ti alloy powder is obtained;

[0034] The mass percentages of oxygen-free copper rod, tin particles and titanium powder are as follows: tin particles 15.5% to 18%, titanium powder 0.1% to 0.3%, and the rest is oxygen-free copper rod, and the sum of the mass percentages of the above components is 100%;

[0035] The obtained Cu-Sn-Ti alloy powder has a particle size of 0 μm ~106 μm;

[0036] Step 2, surface treatment of the pure niobium rod;

[0037] The specific process is as follows: the pure niobium rod is washed with deionized water, and the washed pure niobium rod is placed in an oven for drying;

[0038] The number of the pure niobium rods is 1 or a multiple of 7;

[0039] Step 3: assembling Cu-Sn-Ti alloy powder and pure niobium rod in a mold to obtain a Cu-Sn-Ti / Nb rod composite billet;

[0040] The specific process is:

[0041] When the number of pure niobium rods is one, the pure niobium rod is placed in a mold, and the pure niobium rod is placed coaxially with the mold, and then the remaining space in the mold is filled with Cu-Sn-Ti alloy powder, and the height of the Cu-Sn-Ti alloy powder is not less than the height of the pure niobium rod, to obtain a Cu-Sn-Ti / Nb rod composite billet;

[0042] When the number of pure niobium rods is a multiple of 7, the first pure niobium rod is placed in the mold, with the pure niobium rod and the mold being coaxially placed, and the remaining pure niobium rods are evenly arranged along the circumference of the first pure niobium rod, with the center distances between the remaining pure niobium rods and the first pure niobium rod being equal, and the remaining space in the mold is then filled with Cu-Sn-Ti alloy powder, with the filling height of the Cu-Sn-Ti alloy powder not less than the height of the pure niobium rod, to obtain a Cu-Sn-Ti / Nb rod composite billet;

[0043] Among them, the inner diameter of the mold is 40mm and the height is 70mm;

[0044] Each pure niobium rod has a diameter of 8mm~15mm and a height of 20mm;

[0045] Step 4: placing the Cu-Sn-Ti / Nb rod assembly blank in a vacuum rapid hot pressing furnace for thermal-mechanical-electrical coordinated sintering and cooling to no more than 150° C., removing the cooled Cu-Sn-Ti / Nb rod assembly blank from the mold to obtain a CuSnTi / Nb composite blank. The height of the CuSnTi / Nb composite blank is 30 mm. During the sintering process, only the height changes, and the diameter does not change. That is, the diameter of the CuSnTi / Nb composite blank is equal to the diameter of the Cu-Sn-Ti / Nb rod assembly blank.

[0046] Among them, the process parameters of thermal-mechanical-electrical coordinated sintering are: the vacuum degree in the sintering chamber is not greater than 1Pa, the sintering temperature is 650℃~750℃, the pressure increases from 0.5T to 3T, and maintains 3T after the pressure is increased, and the current value is 2300A~2700A.

[0047] Example 1

[0048] Step 1, preparing Cu-Sn-Ti alloy powder by gas atomization method;

[0049] The specific process is as follows: oxygen-free copper rods, tin particles, and titanium powder are placed in a crucible for smelting. Argon gas is filled in the crucible to protect against oxidation. After the smelting is completed, the crucible is placed in an electrode induction gas atomization powder spraying furnace and evacuated to a vacuum degree of 2.8×10-3 Pa, and nitrogen is filled into the electrode induction gas atomization powder spraying furnace at an inflation pressure of 35 MPa until the pressure in the electrode induction gas atomization powder spraying furnace is not lower than the standard atmospheric pressure. After being filled with nitrogen, the air inlet valve and the air outlet valve of the electrode induction gas atomization powder spraying furnace are opened, and the melting frequency is adjusted to start working, and finally a Cu-Sn-Ti alloy powder is obtained, and the particle size of the Cu-Sn-Ti alloy powder is 0 μm ~ 106 μm;

[0050] The mass percentages of oxygen-free copper rod, tin particles, and titanium powder are as follows: oxygen-free copper rod 84.2%, tin particles 15.5%, and titanium powder 0.3%;

[0051] The melting temperature is 1400℃ and the melting time is 60min;

[0052] Step 2: Wash the pure niobium rod with deionized water, and then place the washed pure niobium rod in an oven for drying;

[0053] Step 3: assembling Cu-Sn-Ti alloy powder and pure niobium rod in a mold to obtain a Cu-Sn-Ti / Nb rod composite billet;

[0054] The specific process is:

[0055] In this embodiment, a pure niobium rod is used. The pure niobium rod with a diameter of 15 mm and a height of 20 mm, processed in step 2, is placed in a mold with an inner diameter of 40 mm and a height of 70 mm, with the pure niobium rod and the mold coaxially positioned. The remaining space in the mold is then filled with Cu-Sn-Ti alloy powder. The filling height of the Cu-Sn-Ti alloy powder is 20 mm higher than that of the pure niobium rod, thereby obtaining a Cu-Sn-Ti / Nb rod composite billet.

[0056] Step 4: placing the Cu-Sn-Ti / Nb rod assembly blank in a vacuum rapid hot pressing furnace for thermal-mechanical-electrical coordinated sintering, cooling to no more than 150° C., and removing the cooled Cu-Sn-Ti / Nb rod assembly blank from the mold to obtain a CuSnTi / Nb composite blank having a height of 30 mm;

[0057] Among them, the process parameters of thermal-mechanical-electrical coordinated sintering are: the vacuum degree in the sintering chamber is not greater than 1Pa, the sintering temperature is 650℃, the pressure increases from 0.5T to 3.0T, the pressure increase time is 1min, and the pressure is maintained at 3.0T after the pressure increase, and the current value is 2300A.

[0058] The performance test of the CuSnTi part in the CuSnTi / Nb composite body obtained in this embodiment was carried out. The test showed that the elongation of the CuSnTi part obtained in this embodiment was 2.37% and the tensile strength was 410.4 MPa. Figure 1It can be seen that the CuSnTi / Nb composite green body obtained in this embodiment has uniform microstructure. In summary, the microstructure uniformity and tensile properties of the CuSnTi / Nb composite green body prepared in this embodiment meet the requirements for superconducting wire assembly green bodies, indicating that this embodiment can reliably prepare CuSnTi / Nb composite green bodies for Nb3Sn superconducting wires.

[0059] Example 2

[0060] Step 1, preparing Cu-Sn-Ti alloy powder by gas atomization method;

[0061] The specific process is as follows: oxygen-free copper rods, tin particles, and titanium powder are placed in a crucible for smelting. Argon gas is filled in the crucible to protect against oxidation. After the smelting is completed, the crucible is placed in an electrode induction gas atomization powder spraying furnace and evacuated to a vacuum degree of 2.8×10 -3 Pa, and nitrogen is filled into the electrode induction gas atomization powder spraying furnace at an inflation pressure of 35 MPa until the pressure in the electrode induction gas atomization powder spraying furnace is not lower than the standard atmospheric pressure. After being filled with nitrogen, the air inlet valve and the air outlet valve of the electrode induction gas atomization powder spraying furnace are opened, the melting frequency is adjusted to start working, and finally Cu-Sn-Ti alloy powder is obtained. The particle size of the obtained Cu-Sn-Ti alloy powder is 0μm~106μm;

[0062] The mass percentages of oxygen-free copper rod, tin particles, and titanium powder are as follows: oxygen-free copper rod 84.2%, tin particles 15.5%, and titanium powder 0.3%;

[0063] The melting temperature is 1400℃ and the melting time is 60min;

[0064] Step 2: Wash the pure niobium rod with deionized water, and then place the washed pure niobium rod in an oven for drying;

[0065] Step 3: assembling Cu-Sn-Ti alloy powder and pure niobium rod in a mold to obtain a Cu-Sn-Ti / Nb rod composite billet;

[0066] The specific process is:

[0067] In this embodiment, a pure niobium rod is used. The pure niobium rod with a diameter of 15 mm and a height of 20 mm, processed in step 2, is placed in a mold with an inner diameter of 40 mm and a height of 70 mm, with the pure niobium rod and the mold coaxially positioned. The remaining space in the mold is then filled with Cu-Sn-Ti alloy powder. The filling height of the Cu-Sn-Ti alloy powder is 20 mm higher than that of the pure niobium rod, thereby obtaining a Cu-Sn-Ti / Nb rod composite billet.

[0068] Step 4: placing the Cu-Sn-Ti / Nb rod assembly blank in a vacuum rapid hot pressing furnace for thermal-mechanical-electrical coordinated sintering, cooling to no more than 150° C., and removing the cooled Cu-Sn-Ti / Nb rod assembly blank from the mold to obtain a CuSnTi / Nb composite blank having a height of 30 mm;

[0069] Among them, the process parameters of thermal-mechanical-electrical coordinated sintering are: the vacuum degree in the sintering chamber is not greater than 1Pa, the sintering temperature is 700℃, the pressure increases from 0.5T to 3.0T, the pressure increase time is 1min, and the pressure is maintained at 3.0T after the pressure increase, and the current value is 2500A.

[0070] The performance test of the CuSnTi part in the CuSnTi / Nb composite body obtained in this embodiment was carried out. The test showed that the elongation of the CuSnTi part obtained in this embodiment was 13.0% and the tensile strength was 476.0 MPa. Figure 2 It can be seen that the CuSnTi / Nb composite green body obtained in this embodiment has uniform microstructure. In summary, the microstructure uniformity and tensile properties of the CuSnTi / Nb composite green body prepared in this embodiment meet the requirements for superconducting wire assembly green bodies, indicating that this embodiment can reliably prepare CuSnTi / Nb composite green bodies for Nb3Sn superconducting wires.

[0071] Example 3

[0072] Step 1, preparing Cu-Sn-Ti alloy powder by gas atomization method;

[0073] The specific process is as follows: oxygen-free copper rods, tin particles, and titanium powder are placed in a crucible for smelting. Argon gas is filled in the crucible to protect against oxidation. After the smelting is completed, the crucible is placed in an electrode induction gas atomization powder spraying furnace and evacuated to a vacuum degree of 2.8×10 -3 Pa, and nitrogen is filled into the electrode induction gas atomization powder spraying furnace at an inflation pressure of 35MPa until the pressure in the electrode induction gas atomization powder spraying furnace is not lower than the standard atmospheric pressure. After being filled with nitrogen, the air inlet valve and the air outlet valve of the electrode induction gas atomization powder spraying furnace are opened, and the melting frequency is adjusted to start working, and finally Cu-Sn-Ti alloy powder is obtained. The obtained Cu-Sn-Ti alloy powder has a particle size of 0μm~106μm;

[0074] The mass percentages of oxygen-free copper rod, tin particles, and titanium powder are as follows: oxygen-free copper rod 84.2%, tin particles 15.5%, and titanium powder 0.3%;

[0075] The melting temperature is 1400℃ and the melting time is 60min;

[0076] Step 2: Wash the pure niobium rod with deionized water, and then place the washed pure niobium rod in an oven for drying;

[0077] Step 3: assembling Cu-Sn-Ti alloy powder and pure niobium rod in a mold to obtain a Cu-Sn-Ti / Nb rod composite billet;

[0078] The specific process is:

[0079] In this embodiment, a pure niobium rod is used. The pure niobium rod with a diameter of 15 mm and a height of 20 mm, processed in step 2, is placed in a mold with an inner diameter of 40 mm and a height of 70 mm, with the pure niobium rod and the mold coaxially positioned. The remaining space in the mold is then filled with Cu-Sn-Ti alloy powder. The filling height of the Cu-Sn-Ti alloy powder is 20 mm higher than that of the pure niobium rod, thereby obtaining a Cu-Sn-Ti / Nb rod composite billet.

[0080] Step 4: placing the Cu-Sn-Ti / Nb rod assembly blank in a vacuum rapid hot pressing furnace for thermal-mechanical-electrical coordinated sintering, cooling to no more than 150° C., and removing the cooled Cu-Sn-Ti / Nb rod assembly blank from the mold to obtain a CuSnTi / Nb composite blank having a height of 30 mm;

[0081] Among them, the process parameters of thermal-mechanical-electrical coordinated sintering are: the vacuum degree in the sintering chamber is not greater than 1Pa, the sintering temperature is 750℃, the pressure increases from 0.5T to 3.0T, the pressure increase time is 1min, and the pressure is maintained at 3.0T after the pressure increase, and the current value is 2700A.

[0082] The performance test of the CuSnTi part in the CuSnTi / Nb composite body obtained in this embodiment was carried out. The test showed that the elongation of the CuSnTi part obtained in this embodiment was 24.9%, and the tensile strength was 537.9 MPa. Figure 3 It can be seen that the CuSnTi / Nb composite green body obtained in this embodiment has uniform microstructure. In summary, the microstructure uniformity and tensile properties of the CuSnTi / Nb composite green body prepared in this embodiment meet the requirements for superconducting wire assembly green bodies, indicating that this embodiment can reliably prepare CuSnTi / Nb composite green bodies for Nb3Sn superconducting wires.

[0083] Example 4

[0084] Step 1, preparing Cu-Sn-Ti alloy powder by gas atomization method;

[0085] The specific process is as follows: oxygen-free copper rods, tin particles, and titanium powder are placed in a crucible for smelting. Argon gas is filled in the crucible to protect against oxidation. After the smelting is completed, the crucible is placed in an electrode induction gas atomization powder spraying furnace and evacuated to a vacuum degree of 2.8×10 -3Pa, and nitrogen is filled into the electrode induction gas atomization powder spraying furnace at an inflation pressure of 35MPa until the pressure in the electrode induction gas atomization powder spraying furnace is not lower than the standard atmospheric pressure. After being filled with nitrogen, the air inlet valve and the air outlet valve of the electrode induction gas atomization powder spraying furnace are opened, and the melting frequency is adjusted to start working, and finally Cu-Sn-Ti alloy powder is obtained. The obtained Cu-Sn-Ti alloy powder has a particle size of 0μm~106μm;

[0086] The mass percentages of oxygen-free copper rod, tin particles, and titanium powder are as follows: oxygen-free copper rod 81.9%, tin particles 18%, and titanium powder 0.1%;

[0087] The melting temperature is 1400℃ and the melting time is 60min;

[0088] Step 2: Wash the pure niobium rod with deionized water, and then place the washed pure niobium rod in an oven for drying;

[0089] Step 3: assembling Cu-Sn-Ti alloy powder and pure niobium rod in a mold to obtain a Cu-Sn-Ti / Nb rod composite billet;

[0090] The specific process is:

[0091] In this embodiment, a pure niobium rod is used. The pure niobium rod with a diameter of 15 mm and a height of 20 mm, processed in step 2, is placed in a mold with an inner diameter of 40 mm and a height of 70 mm, with the pure niobium rod and the mold coaxially positioned. The remaining space in the mold is then filled with Cu-Sn-Ti alloy powder. The filling height of the Cu-Sn-Ti alloy powder is 20 mm higher than that of the pure niobium rod, thereby obtaining a Cu-Sn-Ti / Nb rod composite billet.

[0092] Step 4: placing the Cu-Sn-Ti / Nb rod assembly blank in a vacuum rapid hot pressing furnace for thermal-mechanical-electrical coordinated sintering, cooling to no more than 150° C., and removing the cooled Cu-Sn-Ti / Nb rod assembly blank from the mold to obtain a CuSnTi / Nb composite blank having a height of 30 mm;

[0093] Among them, the process parameters of thermal-mechanical-electrical coordinated sintering are: the vacuum degree in the sintering chamber is not greater than 1Pa, the sintering temperature is 750℃, the pressure increases from 0.5T to 3.0T, the pressure increase time is 1min, and the pressure is maintained at 3.0T after the pressure increase, and the current value is 2700A.

[0094] Performance testing of the CuSnTi portion of the CuSnTi / Nb composite blank obtained in this example revealed an elongation of 15.0% and a tensile strength of 550.0 MPa. The resulting CuSnTi / Nb composite blank exhibited uniform microstructure. In summary, the microstructure uniformity and tensile properties of the CuSnTi / Nb composite blank prepared in this example met the requirements for superconducting wire assembly blanks, demonstrating that this example can reliably produce CuSnTi / Nb composite blanks for Nb3Sn superconducting wires.

[0095] Example 5

[0096] Step 1, preparing Cu-Sn-Ti alloy powder by gas atomization method;

[0097] The specific process is as follows: oxygen-free copper rods, tin particles, and titanium powder are placed in a crucible for smelting. Argon gas is filled in the crucible to protect against oxidation. After the smelting is completed, the crucible is placed in an electrode induction gas atomization powder spraying furnace and evacuated to a vacuum degree of 2.8×10 -3 Pa, and nitrogen is filled into the electrode induction gas atomization powder spraying furnace at an inflation pressure of 35MPa until the pressure in the electrode induction gas atomization powder spraying furnace is not lower than the standard atmospheric pressure. After being filled with nitrogen, the air inlet valve and the air outlet valve of the electrode induction gas atomization powder spraying furnace are opened, and the melting frequency is adjusted to start working, and finally Cu-Sn-Ti alloy powder is obtained. The obtained Cu-Sn-Ti alloy powder has a particle size of 0μm~106μm;

[0098] The mass percentages of oxygen-free copper rod, tin particles, and titanium powder are as follows: oxygen-free copper rod 84.2%, tin particles 15.5%, and titanium powder 0.3%;

[0099] The melting temperature is 1400℃ and the melting time is 60min;

[0100] Step 2: Wash the pure niobium rod with deionized water, and then place the washed pure niobium rod in an oven for drying;

[0101] Step 3: assembling Cu-Sn-Ti alloy powder and pure niobium rod in a mold to obtain a Cu-Sn-Ti / Nb rod composite billet;

[0102] The specific process is:

[0103] In this embodiment, there are seven pure niobium rods: the first pure niobium rod having a diameter of 8 mm and a height of 20 mm, processed in step 2, is placed in a mold having a diameter of 40 mm and a height of 70 mm, with the pure niobium rod and the mold coaxially arranged. The remaining pure niobium rods are evenly arranged around the circumference of the first pure niobium rod, and the center distances between the remaining pure niobium rods and the first pure niobium rod are equal. The remaining space in the mold is then filled with Cu—Sn—Ti alloy powder. The filling height of the Cu—Sn—Ti alloy powder is 20 mm higher than that of the pure niobium rod, thereby obtaining a Cu—Sn—Ti / Nb rod composite billet.

[0104] Step 4: placing the Cu-Sn-Ti / Nb rod assembly blank in a vacuum rapid hot pressing furnace for thermal-mechanical-electrical coordinated sintering, cooling to no more than 150° C., and removing the cooled Cu-Sn-Ti / Nb rod assembly blank from the mold to obtain a CuSnTi / Nb composite blank having a height of 30 mm;

[0105] Among them, the process parameters of thermal-mechanical-electrical coordinated sintering are: the vacuum degree in the sintering chamber is not greater than 1Pa, the sintering temperature is 750℃, the pressure increases from 0.5T to 3.0T, the pressure increase time is 1min, and the pressure is maintained at 3.0T after the pressure increase, and the current value is 2700A.

[0106] The performance test of the CuSnTi part in the CuSnTi / Nb composite body obtained in this embodiment was carried out. The test showed that the elongation of the CuSnTi part obtained in this embodiment was 40.9% and the tensile strength was 548.2 MPa. Figure 4 It can be seen that the CuSnTi / Nb composite blank obtained in this embodiment has uniform microstructure. In summary, the microstructure uniformity and tensile properties of the combined blank prepared in this embodiment meet the requirements for combined blanks for superconducting wires, indicating that this embodiment can reliably prepare CuSnTi / Nb composite blanks for Nb3Sn superconducting wires.

[0107] The results of the five examples above demonstrate that the use of copper-tin alloy powder to prepare CuSnTi / Nb composite billets for niobium-tin superconducting wires reliably achieves ultra-high tin content (tin content ≥ 15.5 wt.%), with tensile properties that meet practical requirements. This demonstrates that the method of the present invention perfectly resolves the conflict between Sn content and alloy plasticity in the traditional Nb3Sn superconducting wire preparation process. Furthermore, the method of the present invention employs a powder-filled gap filling method, significantly saving raw materials and simplifying the tedious process of drilling holes in the Cu-Sn alloy block and inserting niobium rods. Therefore, the results of these examples demonstrate that the method of the present invention can achieve its intended goals and provides a method option for the reliable preparation of kilometer-scale, high-performance Nb3Sn superconducting wires.

Claims

1. A method for preparing a composite body for niobium-tin superconducting wire based on copper-tin alloy powder, characterized in that: The specific steps are as follows: Step 1, preparing Cu-Sn-Ti alloy powder by gas atomization method; Step 2, surface treatment of the pure niobium rod; The number of the pure niobium rods is 1 or a multiple of 7; Step 3: assembling Cu-Sn-Ti alloy powder and pure niobium rod in a mold to obtain a Cu-Sn-Ti / Nb rod composite billet; The specific process of step 3 is: When the number of pure niobium rods is one, the pure niobium rod is placed in a mold, and the pure niobium rod is placed coaxially with the mold, and then the remaining space in the mold is filled with Cu-Sn-Ti alloy powder, and the height of the Cu-Sn-Ti alloy powder is not less than the height of the pure niobium rod, to obtain a Cu-Sn-Ti / Nb rod composite billet; When the number of pure niobium rods is a multiple of 7, the first pure niobium rod is placed in the mold, with the pure niobium rod and the mold being coaxially placed, and the remaining pure niobium rods are evenly arranged along the circumference of the first pure niobium rod, with the center distances between the remaining pure niobium rods and the first pure niobium rod being equal, and the remaining space in the mold is then filled with Cu-Sn-Ti alloy powder, with the filling height of the Cu-Sn-Ti alloy powder not less than the height of the pure niobium rod, to obtain a Cu-Sn-Ti / Nb rod composite billet; Step 4: placing the Cu-Sn-Ti / Nb rod composite blank in a vacuum rapid hot pressing furnace for thermal-mechanical-electrical coordinated sintering, cooling, and then removing it from the mold to obtain a CuSnTi / Nb composite blank; In step 4, the process parameters of the thermal-mechanical-electrical coordinated sintering are: the vacuum degree in the sintering chamber is not greater than 1 Pa, the sintering temperature is 650℃~750℃, the pressure is increased from 0.5T to 3T, and maintained at 3T after the pressure is increased, and the current value is 2300A~2700A.

2. The method for preparing a composite body for niobium-tin superconducting wire based on copper-tin alloy powder according to claim 1, characterized in that: The specific process of step 1 is as follows: oxygen-free copper rod, tin particles and titanium powder are placed in a crucible for smelting, and argon gas is filled in the crucible for protection during the smelting process. After the smelting is completed, the crucible is placed in an electrode induction gas atomization powder spraying furnace and evacuated to a vacuum degree of 2.8×10 -3 Pa, and fill nitrogen into the electrode induction gas atomization powder spraying furnace at an inflation pressure of 35MPa until the pressure inside the electrode induction gas atomization powder spraying furnace is not lower than the standard atmospheric pressure. After being filled with nitrogen, the air inlet valve and the air outlet valve of the electrode induction gas atomization powder spraying furnace are opened, the smelting frequency is adjusted to start working, and finally Cu-Sn-Ti alloy powder is obtained.

3. The method for preparing a composite body for niobium-tin superconducting wire based on copper-tin alloy powder according to claim 2, characterized in that: The mass percentages of oxygen-free copper rod, tin particles and titanium powder are as follows: tin particles 15.5%~18%, titanium powder 0.1%~0.3%, and the rest is oxygen-free copper rod, and the sum of the mass percentages of the above components is 100%.

4. The method for preparing a composite body for niobium-tin superconducting wire based on copper-tin alloy powder according to claim 1, characterized in that: The specific process of step 2 is: washing the pure niobium rod with deionized water, and placing the washed pure niobium rod in an oven for drying.

5. The method for preparing a composite body for niobium-tin superconducting wire based on copper-tin alloy powder according to claim 1, characterized in that: The inner diameter of the mold is 40 mm and the height is 70 mm; The diameter of each pure niobium rod is 8 mm to 15 mm, and the height is 20 mm.

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