Niobium titanium alloy

Abstract

To provide a niobium-titanium alloy having high plasticity.SOLUTION: The niobium-titanium alloys for superconducting applications in accordance with the standard specifications of ASTMB884 11 are characterized in that the measured values of the niobium-titanium alloys satisfy all the following conditions (1), (2) and (3): (1) Tensilestrength: 350MPa or less (2) Yieldstrength: 350MPa or less (3) Elongation (Relativeelongationatbase25mm): 21% or more SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to niobium titanium alloys. [Background technology]

[0002] Niobium-titanium alloys (NbTi alloys) are already well known as metallic superconducting materials used in medical analysis fields such as MRI devices and NMR devices, power generation and power storage fields such as the ITER experimental nuclear fusion reactor and superconducting magnetic energy storage (SMES), and various physical property analysis fields (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-062544 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional niobium-titanium alloys have low plasticity and are brittle, making them difficult to process. For example, there are limitations to how fine the alloy can be made, and there are also restrictions on how the niobium-titanium alloy can be placed as a filament in a stabilizer (usually oxygen-free copper), preventing the alloy from fully demonstrating its performance.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide a niobium-titanium alloy having high plasticity.

[0006] The main invention for achieving the above object is a niobium-titanium alloy for superconducting applications that conforms to the standard specifications of ASTM B884-11, characterized in that the measured values ​​of the niobium-titanium alloy satisfy all of the following conditions (1), (2), and (3): (1) Tensile strength: 350 MPa or less (2) Yield strength: 350 MPa or less (3) Elongation (Relative elongation at base 25mm): 21% or more

[0007] Other features of the present invention will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0008] The niobium-titanium alloy according to the present invention is a niobium-titanium alloy for superconducting applications that conforms to the standard specifications of ASTM B884-11, and is characterized in that the measured values ​​of the niobium-titanium alloy satisfy all of the following conditions (1), (2), and (3): (1) Tensile strength: 350 MPa or less (2) Yield strength: 350 MPa or less (3) Elongation (Relative elongation at base 25mm): 21% or more [Effects of the Invention]

[0009] According to the present invention, there can be provided a niobium-titanium alloy for superconducting applications that conforms to the standard specifications of ASTM B884-11, characterized in that the measured values ​​of the niobium-titanium alloy satisfy all of the following conditions (1), (2), and (3): (1) Tensile strength: 350 MPa or less (2) Yield strength: 350 MPa or less (3) Elongation (Relative elongation at base 25mm): 21% or more [Brief explanation of the drawings]

[0010] The drawings illustrate specific embodiments of the invention according to the present disclosure, including essential features of the invention as well as alternative and preferred embodiments. [Figure 1] 1 is a table showing physical properties of niobium titanium alloys. [Figure 2] 1 is a table showing the component contents of niobium titanium alloys. [Figure 3] Measurement results for niobium titanium alloy. [Figure 4] Measurement results for niobium titanium alloy. [Figure 5] Measurement results for niobium titanium alloy. [Figure 6] Measurement results for niobium titanium alloy. [Figure 7] Measurement results for niobium titanium alloy. [Figure 8] Measurement results for niobium titanium alloy. [Figure 9] Measurement results for niobium titanium alloy. [Figure 10] Measurement results for niobium titanium alloy. [Figure 11] Measurement results for niobium titanium alloy. [Figure 12] Measurement results for niobium titanium alloy. [Figure 13] 1 is a flowchart showing the manufacturing process up to the point where a niobium-titanium alloy is processed into a cable shape. [Figure 14] Photographs showing the appearance of a niobium titanium alloy at each manufacturing step. [Figure 15] 1 is a graph of the titanium content in the cross section of a cable. [Figure 16] FIG. 16(a) is a diagram showing the first and second regions, and FIG. 16(b) is a diagram showing the third and fourth regions. [Figure 17] Figure 17(a) is a photograph showing the filament in a cherry blossom petal shape, Figure 17(b) is a photograph showing the filament in a hexagonal shape, and Figure 17(c) is a photograph showing the filament in a spiral shape. [Figure 18]FIG. 1 is a diagram showing a portion of the nuclear fusion experimental reactor (ITER) in which the product of the present invention is adopted.

[0011] At least the following matters will become clear from the description of this specification and the accompanying drawings.

[0012] A niobium-titanium alloy for superconducting applications that conforms to the standard specifications of ASTM B884-11, characterized in that the measured values ​​of the niobium-titanium alloy satisfy all of the following conditions (1), (2), and (3). (1) Tensile strength: 350 MPa or less (2) Yield strength: 350 MPa or less (3) Elongation (Relative elongation at base 25mm): 21% or more

[0013] Such a niobium-titanium alloy satisfies the requirements for tensile strength, yield strength, and elongation (relative elongation at base 25 mm), thereby providing a niobium-titanium alloy with high plasticity.

[0014] In such a niobium titanium alloy, it is desirable that the average grain size G of the above-mentioned measured values ​​is 5.0 μm or less.

[0015] With such a niobium titanium alloy, by making the average grain size, G, 5.0 μm or less, a high-strength niobium titanium alloy can be provided.

[0016] In such a niobium titanium alloy, it is desirable that the Vickers hardness of the above-mentioned measured values ​​is 120 or less.

[0017] Such a niobium titanium alloy can be provided with a flexible Vickers hardness (HV 10) of 120 or less.

[0018] In such a niobium-titanium alloy, it is desirable that the component contents among the above-mentioned measured values ​​satisfy the following condition (4). (4): Ti=48% or more and 52% or less, Al=60ppm or less, C=100ppm or less, Cr=60ppm or less, Cu=60ppm or less, Fe=60ppm or less, Ni=60ppm or less, N=100ppm or less, O=500ppm or less, Si=100ppm or less, Ta=600ppm or less, H=35ppm or less

[0019] According to such a niobium titanium alloy, the component contents of H (hydrogen), N (nitrogen), O (oxygen), C (carbon), Al (aluminum), Cr (chromium), Cu (copper), Fe (iron), Ni (nickel), Si (silica), Ta (tungsten), and Ti (titanium) satisfy condition (4), so that a high-quality niobium titanium alloy can be provided.

[0020] Such a niobium-titanium alloy can be used as a cable by processing it into a wire, and it is desirable that the titanium content at the outer circumferential edge of the cross section of the cable is greater than the titanium content at the center of the cross section.

[0021] Such a niobium-titanium alloy can provide a niobium-titanium alloy having high plasticity.

[0022] In such a niobium titanium alloy, it is desirable that the titanium content at the outer peripheral edge in the cross section is at least twice as high as the titanium content at the center in the cross section.

[0023] Such a niobium titanium alloy can provide a niobium titanium alloy having higher plasticity.

[0024] In such a niobium titanium alloy, when the cross section is circular, a circular region that is 1 / 2 the radius from the center of the circle is defined as a first region, and the region of the cross section excluding the first region is defined as a second region, it is desirable that the titanium content of the second region be greater than the titanium content of the first region.

[0025] Such a niobium-titanium alloy can provide a niobium-titanium alloy having high plasticity.

[0026] In such a niobium titanium alloy, the titanium content of the second region is preferably at least twice as high as the titanium content of the first region.

[0027] Such a niobium titanium alloy can provide a niobium titanium alloy having higher plasticity.

[0028] In such a niobium titanium alloy, when the cross section is circular, a circular region that is 4 / 5 of the radius from the center of the circle is defined as a third region, and the region of the cross section excluding the third region is defined as a fourth region, it is desirable that the titanium content of the fourth region be greater than the titanium content of the third region.

[0029] Such a niobium-titanium alloy can provide a niobium-titanium alloy having high plasticity.

[0030] In such a niobium titanium alloy, it is desirable that the titanium content of the fourth region is at least twice as high as the titanium content of the third region.

[0031] Such a niobium titanium alloy can provide a niobium titanium alloy having higher plasticity.

[0032] In such a niobium-titanium alloy, the niobium-titanium alloy is a filament that is embedded in a stabilizing material and then composited and drawn, and it is desirable that the arrangement of the filaments in the cross section of the stabilizing material is arranged in the shape of cherry blossom petals.

[0033] Such a niobium titanium alloy has high plasticity, allowing the filaments to be arranged in a cherry blossom petal shape, thereby providing a superconductor with suitable performance.

[0034] In such a niobium-titanium alloy, the niobium-titanium alloy is a filament that is embedded in a stabilizing material and then composited and drawn, and it is desirable that the arrangement of the filaments is along a hexagonal shape in the cross section of the stabilizing material.

[0035] Such niobium titanium alloys have high plasticity, allowing the filaments to be arranged in a hexagonal pattern, providing a superconductor with suitable performance.

[0036] In such a niobium-titanium alloy, the niobium-titanium alloy is a filament that is embedded in a stabilizing material and then composited and drawn, and it is desirable that the arrangement of the filament is along a spiral shape in the cross section of the stabilizing material.

[0037] Such niobium titanium alloys have high plasticity, allowing the filaments to be arranged in a spiral shape, providing a superconductor with suitable performance.

[0038] The niobium-titanium alloy is preferably produced by melting a niobium ingot having a niobium content of 99.95% or more and a titanium ingot having a titanium content of 99.95% or more in an electron beam melting furnace separately to produce a niobium melt and a titanium melt, then mixing the niobium melt and the titanium melt to produce a mixture having a titanium content of 48% or more and 52% or less, and repeating melting and solidification of the mixture multiple times in a vacuum arc melting furnace.

[0039] Such a niobium-titanium alloy can provide a niobium-titanium alloy having high plasticity. DETAILED DESCRIPTION OF THE INVENTION

[0040] [Present embodiment] <Physical properties and components of niobium titanium alloy (NT50)> The niobium-titanium alloy (trade name: NT50) according to this embodiment will be described below with reference to the drawings. The product of the present invention is a niobium-titanium alloy (NT50) conforming to ASTM (American Society for Testing and Materials) International B884-11 (Standard Specification For Niobium-Titanium Alloy Billets, Bar, And Rod For Superconducting Applications).

[0041] FIG. 1 is a table showing the physical properties of niobium titanium alloy (NT50), and FIG. 2 is a table showing the component contents (Ti is the component content) of niobium titanium alloy (NT50). FIGS. 3 to 12 show the measurement results of the niobium titanium alloy (NT50) of the present invention. Each of FIGS. 3 to 12 lists information such as the measured value, measurement date and time, and measuring equipment. Furthermore, the results of measurements not listed in the tables of FIGS. 1 and 2, such as the degree of recrystallization, surface roughness, ultrasonic testing, and radiography, are also listed, although they do not directly affect the present invention and will not be explained here.

[0042] Figure 1 shows the physical properties of Examples 1 and 2, which are niobium-titanium alloys (NT50) according to this embodiment, and Comparative Example 1, a conventional product. The physical properties shown include tensile strength, yield strength, relative elongation at base 25 mm, average grain size G, and Vickers hardness (HV10). The difference between Examples 1 and 2 is that they were made using the same manufacturing process, and the manufacturing lots were different.

[0043] 1, the tensile strength is 367 MPa for Comparative Example 1, while it is 343.5 MPa and 347.1 MPa for Examples 1 and 2. In other words, the tensile strengths of Examples 1 and 2 are 350 MPa or less.

[0044] The yield strength is 364 MPa for Comparative Example 1, whereas it is 342.6 MPa and 346.1 MPa for Examples 1 and 2. In other words, the yield strengths of Examples 1 and 2 are 350 MPa or less.

[0045] The elongation percentage is 20% in Comparative Example 1, while it is 24.4% and 23.4% in Examples 1 and 2. In other words, the elongation percentages of Examples 1 and 2 are 21% or more.

[0046] In this way, the niobium titanium alloy (NT50) of Examples 1 and 2 has high plasticity by reducing the tensile strength and yield strength and increasing the elongation rate compared to the conventional product, Comparative Example 1.

[0047] That is, the niobium titanium alloy (NT50) according to this embodiment is a niobium titanium alloy (NT50) for superconducting applications that conforms to the standard specifications of ASTM B884-11, and the measured values ​​of the niobium titanium alloy (NT50) are a tensile strength of 350 MPa or less, a yield strength of 350 MPa or less, and an elongation of 21% or more. This results in a niobium titanium alloy (NT50) with high plasticity.

[0048] Furthermore, the average particle size G is unclear in the comparative example and cannot be measured (measurable), whereas it is 3.3 μm and 3.0 μm in Examples 1 and 2. That is, the niobium titanium alloy (NT50) according to this embodiment has an average particle size G of 5.0 μm or less among the measured values. This results in a high-strength niobium titanium alloy (NT50).

[0049] Furthermore, the Vickers hardness of Comparative Example 1 is 123, while the Vickers hardness of Examples 1 and 2 is 115 and 116. In other words, the niobium titanium alloy (NT50) according to this embodiment has a Vickers hardness of 120 or less among the measured values. This results in a flexible niobium titanium alloy (NT50).

[0050] 2 shows the component contents of Example 1 and Example 2, which are niobium-titanium alloys (NT50) according to the present embodiment, and Comparative Example 2, which shows the component contents required for niobium-titanium alloys in ASTM B884-11. The component contents listed are Ti (titanium), Al (aluminum), C (carbon), Cr (chromium), Cu (copper), Fe (iron), Ni (nickel), N (nitrogen), O (oxygen), Si (silicon), Ta (tungsten), and H (hydrogen).

[0051] 2, Example 1 and Example 2 have lower component contents than Comparative Example 2, fully satisfying the component contents of ASTM B884-11. More specifically, Ti = 48% (46-48%), Al = 60 ppm or less (100 ppm), C = 41.43 ppm (200 ppm), Cr = 60 ppm or less (100 ppm), Cu = 60 ppm or less (100 ppm), Fe = 60 ppm or less (200 ppm), Ni = 60 ppm or less (100 ppm), N = 67.64 ppm (150 ppm), O = 257.210 ppm (1000 ppm), Si = 100 ppm or less (100), Ta = 600 ppm or less (2500 ppm), and H = 10.7 ppm (45 ppm) (values ​​in parentheses are for Comparative Example 2).

[0052] That is, the niobium titanium alloy (NT50) according to this embodiment has the following measured component contents: Ti = 48% or more and 52% or less, Al = 60 ppm or less, C = 100 ppm or less, Cr = 60 ppm or less, Cu = 60 ppm or less, Fe = 60 ppm or less, Ni = 60 ppm or less, N = 100 ppm or less, O = 500 ppm or less, Si = 100 ppm or less, Ta = 600 ppm or less, and H = 35 ppm or less. This results in a high-quality niobium titanium alloy (NT50).

[0053] <About the cable manufacturing process> Next, the process of processing the niobium titanium alloy (NT50) according to this embodiment into a cable shape will be described with reference to the drawings. Figure 13 is a flowchart showing the manufacturing process up to processing the niobium titanium alloy (NT50) into a cable shape.

[0054] First, a niobium ingot with an Nb content of 99.95% or more is melted in an electron beam melting furnace (Step S1). Then, a titanium ingot with a Ti content of 99.95% or more is melted in the same electron beam melting furnace (Step S2). In this way, by separately melting a high-purity niobium ingot and a high-purity titanium ingot, a niobium-titanium alloy (NT50) with high plasticity is obtained.

[0055] Next, the niobium melt and the titanium melt are mixed so that the titanium content is 48% or more and 52% or less (step S3). The mixture is then melted and solidified multiple times in a vacuum arc melting furnace to obtain a niobium-titanium alloy (NT50) (step S4). By repeating the process of melting and solidifying the niobium-titanium alloy multiple times (three times in this embodiment), a niobium-titanium alloy (NT50) with high homogeneity is obtained. The dimensions of the niobium-titanium alloy (NT50) here are adjusted to a diameter of 250 to 450 mm and a length of 2000 to 2500 mm.

[0056] That is, the niobium titanium alloy (NT50) according to this embodiment is a niobium titanium alloy (NT50) characterized in that a niobium ingot having a niobium content of 99.95% or more and a titanium ingot having a titanium content of 99.95% or more are melted separately in an electron beam melting furnace to produce a niobium melt and a titanium melt, and then the niobium melt and the titanium melt are mixed so that the ratio of each of the melted niobium and the melted titanium is 50%, and the resulting mixture is melted multiple times in a vacuum arc melting furnace.

[0057] Such a niobium titanium alloy (NT50) can provide a niobium titanium alloy (NT50) having high plasticity.

[0058] Then, the niobium titanium alloy (NT50) is forged and pressed to form rod-shaped fixed-length billets (step S5). Niobium titanium alloy (NT50) with a diameter of 250 to 450 mm is forged and pressed to a diameter of 150 to 170 mm, cut to a length of 700 to 800 mm, and heat treated to form fixed-length billets.

[0059] Next, the fixed-length billet is inserted into a copper pipe with a diameter of 250 mm and hot-pressed to form a bimetal rod with a diameter of 25 mm (step S6). The hot-pressing (hot isostatic pressing) is carried out at 500 to 700°C, and the cross section of the formed bimetal rod shows a niobium-titanium alloy (NT50) in the center surrounded by copper.

[0060] Then, multiple bimetal rods are inserted into the copper pipe and hot press-formed to form bimetal rods with a diameter of 25 mm (step S7). For example, 15 bimetal rods (with one niobium-titanium alloy (NT50) inside) obtained in step S6 are inserted into the copper pipe with a diameter of 250 mm that was also used in step S6. Then, hot press-formed in the same manner as in step S6 to form bimetal rods with a diameter of 25 mm. In this way, the bimetal rod obtained in step S7 becomes a bimetal rod containing 15 niobium-titanium alloy (NT50) inside.

[0061] Then, it is confirmed whether or not there are 1500 or more niobium titanium alloy (NT50) particles inside the bimetal rod (step S8). If there are less than 1500 particles, step S7 is repeated until there are 1500 or more particles.

[0062] For example, if 15 bimetal rods containing niobium titanium alloy (NT50) are inserted into a 250 mm diameter copper tube and hot pressed again, 15 x 15 = 225 bimetal rods containing niobium titanium alloy (NT50) will be produced. If seven bimetal rods containing 225 niobium titanium alloy (NT50) rods are inserted into an optimal copper tube and hot pressed again, 225 x 7 = 1575 bimetal rods containing niobium titanium alloy (NT50) will be produced.

[0063] Once a bimetal rod containing 1,500 or more niobium-titanium alloy (NT50) rods with a diameter of 25 mm has been produced, the bimetal rod is drawn. Specifically, the rod is pressed and rolled to a diameter of 15 mm, annealed, and drawn into a cable with a diameter of, for example, several μm to several mm (step S9).

[0064] <About niobium titanium alloy (NT50) cables> Next, we will explain the characteristics of the niobium titanium alloy (NT50) according to this embodiment when it is processed into a cable. Figure 14 is a photograph showing the appearance of the niobium titanium alloy (NT50) at each manufacturing process. It shows that the shape differs at each manufacturing process. The fine linear object in the center of the photograph is the niobium titanium alloy (NT50) according to this embodiment processed into a cable with a diameter of 10 μm.

[0065] Figure 15 is a graph of the titanium content in a cable cross section with a diameter of 10 μm. The horizontal axis runs from one radial end (0 μm) through the center (5 μm) to the other radial end (10 μm), and the vertical axis represents the titanium content.

[0066] As shown in Figure 15, the titanium content is higher at the outer periphery than at the center. In other words, the niobium titanium alloy (NT50) according to this embodiment can be used as a cable by processing it into a wire, and in the cross section of the cable, the titanium content at the outer periphery is higher than the titanium content at the center of the cross section. This results in a niobium titanium alloy (NT50) with high plasticity.

[0067] Furthermore, the titanium content is more than twice as high at the outer peripheral surface as at the center. In other words, in the niobium titanium alloy (NT50) according to this embodiment, the titanium content at the outer peripheral edge in the cross section is more than twice as high as the titanium content at the center in the cross section. This results in a niobium titanium alloy (NT50) with higher plasticity. In the niobium titanium alloy (NT50) according to this embodiment, the titanium content is about 15 times higher.

[0068] 16(a) is a diagram showing the first region and the second region. The first region here refers to a circular region at 1 / 2 the radius from the center in the cross section of a cable obtained by processing the niobium titanium alloy (NT50) according to this embodiment into a circular shape (the region with diagonal lines that slope downward to the right). The second region here refers to the region of the cable cross section excluding the first region (the region with diagonal lines that slope upward to the right).

[0069] 15 and 16(a), the second region has a higher titanium content than the first region. In other words, when the niobium titanium alloy (NT50) according to this embodiment has a circular cross section, and the circular region at 1 / 2 the radius from the center of the circle is defined as the first region, and the region of the cross section excluding the first region is defined as the second region, the titanium content of the second region is higher than the titanium content of the first region. This results in a niobium titanium alloy (NT50) with high plasticity.

[0070] Furthermore, the titanium content is more than twice as high in the second region as in the first region. In other words, the titanium content in the second region is more than twice as high as the titanium content in the first region. This results in a niobium-titanium alloy (NT50) with higher plasticity. In the niobium-titanium alloy (NT50) according to this embodiment, the plasticity is about 15 times higher.

[0071] 16(b) is a diagram showing the third region and the fourth region. The third region here refers to a circular region (horizontal line region) that is 4 / 5 of the radius from the center in the cross section of a cable obtained by processing the niobium titanium alloy (NT50) according to this embodiment into a circular shape. The fourth region here refers to the region of the cable cross section excluding the third region (vertical line region).

[0072] 15 and 16(b), the fourth region has a higher titanium content than the third region. In other words, when the niobium titanium alloy (NT50) according to this embodiment has a circular cross section, and the third region is a circular region that is 4 / 5 of the radius from the center of the circle, and the fourth region is the region of the cross section excluding the third region, the titanium content of the fourth region is higher than the titanium content of the third region. This results in a niobium titanium alloy (NT50) with high plasticity.

[0073] Furthermore, the titanium content is more than twice as high in the fourth region as in the third region. In other words, the titanium content in the fourth region is more than twice as high as the titanium content in the third region. This results in a niobium-titanium alloy (NT50) with higher plasticity. In the niobium-titanium alloy (NT50) according to this embodiment, the plasticity is about four times higher.

[0074] <Example of placement of niobium titanium alloy (NT50)> Next, an example of the arrangement of the niobium titanium alloy (NT50) according to this embodiment will be described. Normally, when the niobium titanium alloy (NT50) is used as a superconductor, it is embedded in a stabilizing material (oxygen-free copper, etc.), combined, and arranged as a drawn filament.

[0075] The term "arrangement" used here includes the position, shape, size, and area occupied by the niobium titanium alloy (NT50) in the stabilizer. For example, when arranging niobium titanium alloy (NT50) in a superconducting cable with a diameter of 1.5 mm, this arrangement includes the meaning of arranging 1,500 niobium titanium alloy (NT50) cables with a diameter of 10 μm (occupying an area of ​​15%) concentrically from the center.

[0076] This arrangement affects the performance of the superconductor, so changing the arrangement depending on the required performance will result in a better superconductor. The flexibility of this arrangement is related to the plasticity of the niobium titanium alloy (NT50), and the higher the plasticity, the greater the freedom of arrangement.

[0077] Figure 17 shows photographs of a cross section of a stabilizer in which the niobium titanium alloy (NT50) according to this embodiment is placed as a filament. Figure 17(a) shows the filament in a cherry blossom petal shape, Figure 17(b) shows the filament in a hexagonal shape, and Figure 17(c) shows the filament in a spiral shape.

[0078] In other words, the niobium titanium alloy (NT50) according to this embodiment is a filament that is embedded in a stabilizer and then drawn into a composite, and the filaments can be arranged in the shape of cherry blossom petals in the cross section of the stabilizer, which allows for a superconductor with optimal performance.

[0079] Furthermore, in the niobium titanium alloy (NT50) according to this embodiment, the filaments can be arranged along a hexagonal shape in the cross section of the stabilizer, which allows for a superconductor with optimal performance.

[0080] Furthermore, the niobium titanium alloy (NT50) according to this embodiment allows the filaments to be arranged along a spiral shape in the cross section of the stabilizer, which allows the superconductor to exhibit appropriate performance.

[0081] <Adoption of niobium titanium alloy (NT50) in ITER> Next, an example will be described in which the niobium titanium alloy (NT50) according to this embodiment has actually been adopted in an important device. Figure 18 is a diagram showing the part in which the product of the present invention is adopted in the nuclear fusion experimental reactor (ITER).

[0082] The niobium titanium alloy (NT50) according to this embodiment is being used in the ITER (International Thermonuclear Experimental Reactor) which is planned to be built in Saint-Paul-les-Durance, France. It is being used as the superconductors in the toroidal field (TF) coil, central solenoid (CS) coil, and divertor, which are shown enclosed by dashed lines in Figure 18. Each of these areas requires extremely high performance.

[0083] Furthermore, the toroidal field (TF) coil, central solenoid (CS) coil, and divertor each require different performance, but the niobium titanium alloy (NT50) of this embodiment has high plasticity, making it possible to process it to meet the performance requirements for each.

[0084] [Other embodiments] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and it goes without saying that the present invention includes equivalents thereof.

Claims

1. A niobium-titanium alloy for superconducting applications conforming to the standard specification of ASTM B884-11, A niobium-titanium alloy characterized in that the measured values ​​of the niobium-titanium alloy satisfy all of the following conditions (1), (2), and (3): (1) Tensile strength: 350 MPa or less (2) Yield strength: 350 MPa or less (3) Elongation (Relative elongation at base 25mm): 21% or more

2. 2. The niobium titanium alloy of claim 1, A niobium-titanium alloy characterized in that the average grain size G of the above measured values ​​is 5.0 μm or less.

3. 2. The niobium titanium alloy of claim 1, A niobium-titanium alloy characterized in that the Vickers hardness of the above-mentioned measured values ​​is 120 or less.

4. 2. The niobium titanium alloy of claim 1, A niobium-titanium alloy characterized in that the component contents of the above-mentioned measured values ​​satisfy the following condition (4). (4): Ti=48% or more and 52% or less, Al=60ppm or less, C=100ppm or less, Cr=60ppm or less, Cu=60ppm or less, Fe=60ppm or less, Ni=60ppm or less, N=100ppm or less, O=500ppm or less, Si=100ppm or less, Ta=600ppm or less, H=35ppm or less

5. 2. The niobium titanium alloy of claim 1, The niobium-titanium alloy can be used as a cable by processing it into a wire shape, In the cross section of the cable, A niobium-titanium alloy characterized in that the titanium content at the outer circumferential edge in the cross section is greater than the titanium content at the center in the cross section.

6. 6. The niobium titanium alloy of claim 5, A niobium-titanium alloy characterized in that the titanium content at the outer peripheral edge in the cross section is at least twice as high as the titanium content at the center in the cross section.

7. 6. The niobium titanium alloy of claim 5, The cross section is circular, When a circular region of 1 / 2 the radius from the center of the circular shape is defined as a first region, and a region of the cross section excluding the first region is defined as a second region, A niobium titanium alloy, wherein the second region has a titanium content greater than the titanium content of the first region.

8. 8. The niobium titanium alloy of claim 7, A niobium titanium alloy, characterized in that the titanium content of the second region is at least twice as high as the titanium content of the first region.

9. 6. The niobium titanium alloy of claim 5, The cross section is circular, When a circular region having a radius of 4 / 5 from the center of the circular shape is defined as a third region, and a region of the cross section excluding the third region is defined as a fourth region, A niobium titanium alloy, wherein the fourth region has a titanium content greater than the titanium content of the third region.

10. 10. The niobium titanium alloy of claim 9, A niobium titanium alloy, characterized in that the titanium content of the fourth region is at least twice as high as the titanium content of the third region.

11. 2. The niobium titanium alloy of claim 1, The niobium-titanium alloy is a filament that is embedded in a stabilizing material, combined with the niobium-titanium alloy, and then drawn. A niobium titanium alloy characterized in that, in the cross section of the stabilizer, the filaments are arranged in the shape of cherry blossom petals.

12. 2. The niobium titanium alloy of claim 1, The niobium-titanium alloy is a filament that is embedded in a stabilizing material, combined with the niobium-titanium alloy, and then drawn. A niobium titanium alloy characterized in that, in the cross section of the stabilizer, the filaments are arranged along a hexagonal shape.

13. 2. The niobium titanium alloy of claim 1, The niobium-titanium alloy is a filament that is embedded in a stabilizing material, combined with the niobium-titanium alloy, and then drawn. A niobium titanium alloy characterized in that, in the cross section of the stabilizer, the filaments are arranged in a spiral shape.

14. 2. The niobium titanium alloy of claim 1, A niobium ingot having a niobium content of 99.95% or more and a titanium ingot having a titanium content of 99.95% or more are melted separately in an electron beam melting furnace to produce a niobium melt and a titanium melt, and then producing a mixture by mixing the niobium melt and the titanium melt so that the titanium content is 48% or more and 52% or less; A niobium-titanium alloy is produced by repeating melting and solidification of the mixture multiple times in a vacuum arc melting furnace.

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