Nb3Sn superconducting material, method for improving Nb3Sn critical current density through rare earth yttrium doping and application
By doping rare-earth yttrium (Y) into Nb and Cu-Sn alloys to form diffusion couples, the problem of insufficient critical current density in Nb3Sn superconducting materials was solved, achieving uniform thickness and efficient synthesis, making it suitable for superconducting magnets in high-energy physics devices.
Patent Information
- Application Number
- CN202511352955.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-22
- Publication Date
- 2026-01-09
AI Technical Summary
The critical current density of existing Nb3Sn superconducting materials is insufficient to meet the needs of future high-energy physics equipment such as circular colliders, and traditional preparation methods are difficult to achieve uniform thickness and efficient synthesis.
By doping rare earth element yttrium (Y) into Nb and Cu-Sn alloys to form diffusion couples, controlling diffusion annealing conditions, promoting Sn diffusion, and forming Y2O3 nanoparticles as flux pinning centers, the growth rate and critical current density of Nb3Sn superconducting materials are improved.
Significant improvements were achieved in the thickness uniformity and critical current density of Nb3Sn superconducting materials, making them suitable for high-magnetic-field superconducting magnets and exhibiting excellent superconducting performance.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of superconducting material preparation, and particularly relates to a Nb3Sn superconducting material, a method for improving the critical current density of Nb3Sn by doping with rare earth yttrium and use. BACKGROUND
[0002] Superconducting magnets are widely used in particle accelerators, nuclear fusion devices and nuclear magnetic resonance equipment due to their excellent ability to carry high lossless current. NbTi and Nb3Sn are commonly used materials for manufacturing superconducting magnets, however, the low critical magnetic field (~14T) and critical current density (1200A / mm 2 at 1.9K and 8T) of NbTi make it only produce a lower magnetic field. To generate a higher magnetic field beyond the NbTi limit, Nb3Sn superconducting material is needed, which has a high critical magnetic field (~27T) and a high critical current density (3000A / mm 2 at 4.2K and 12T), and is considered as the preferred material for manufacturing high magnetic field superconducting magnets (>10T).
[0003] The future circular collider (FCC) aims to push the energy frontier of high-energy physics, which requires thousands of Nb3Sn superconductor-based dipole and quadrupole magnets with a magnetic field of 16T, which requires Nb3Sn wires to have excellent superconducting performance, especially a critical current density higher than 1500A / mm 2 at 16T, which is far beyond the current preparation technology level of Nb3Sn wires. Therefore, it is urgent to improve the critical current density of Nb3Sn superconductors.
[0004] Xu et al. found that by internal oxidation of Zr in Nb-1Zr alloy with SnO2 powder, ZrO2 oxide nanoparticles can be formed in Nb3Sn superconducting material, thereby further improving the critical current density. This is because the ZrO2 oxide nanoparticles formed in the Nb3Sn superconducting material by internal oxidation can hinder the growth of Nb3Sn grains to refine the grains, and on the other hand, it itself acts as an artificial pinning center to pin the magnetic flux line, and the combined effect of the two can significantly improve the critical current density of the Nb3Sn superconductor.
[0005] Studies have shown that element doping (Zr, Hf, Ti and Ta, etc.) can promote the diffusion of Sn and refine the grain size of Nb3Sn, thereby significantly improving the critical current density. In the research of element doping, the wire with a circular cross-section is usually used to analyze the Nb / Sn diffusion and superconducting performance. In these processes (for example, bronze method and internal tin method), Nb usually exists in the form of Nb wire (diameter of 5-10 μm), so after heat treatment, circular and ring-shaped Nb3Sn superconducting materials with different thicknesses are generated, and even some Nb3Sn superconducting materials are bridged together, which makes it difficult to infer the exact contribution of the doped elements to the synthesis of Nb3Sn superconducting phase and the critical current density.
[0006] Therefore, how to develop a Nb3Sn superconducting material with uniform thickness and higher critical current density and a preparation method with higher synthesis efficiency has become a problem to be solved at present. SUMMARY
[0007] To solve the above technical problems, the purpose of the present application is to provide a Nb3Sn superconducting material, a method for improving the critical current density of Nb3Sn by doping with rare earth yttrium and the use thereof. The diffusion couple process for preparing the Nb3Sn superconducting material accelerates the growth rate of the Nb3Sn layer by doping Y element, and improves the critical current density of the interface Nb3Sn superconducting material. Moreover, the diffusion couple can intuitively compare the growth difference of the Nb3Sn superconducting material layer in the doped and undoped samples, and facilitate the analysis of the influence mechanism of the doping element on the synthesis of the Nb3Sn superconducting material and the final critical current density.
[0008] To achieve this purpose, the present application adopts the following technical solutions:
[0009] In a first aspect, the present application provides a method for improving the critical current density of Nb3Sn by doping with rare earth yttrium, which comprises the following steps:
[0010] The surface of component A is attached to the surface of component B and placed in a fixing device to form a diffusion couple. The diffusion couple is subjected to diffusion annealing to obtain a Nb3Sn superconducting material. The component A comprises a Nb elemental ingot and / or a Nb-Y alloy ingot. The component B comprises a Cu-Sn alloy ingot and / or a Cu-Sn-Y alloy ingot. At least one of the component A and the component B contains Y.
[0011] The rare earth element Y can promote the diffusion rate of Sn, thereby accelerating the growth rate of the Nb3Sn superconducting material. Meanwhile, the rare earth element Y has strong oxygen affinity and can form Y2O3 nanoparticles through oxidation. These Y2O3 nanoparticles in the Nb3Sn layer can act as artificial pinning centers, improve the magnetic flux pinning force, and thus improve the critical current density of the interface Nb3Sn superconducting material. Y is a light rare earth element and is easy to oxidize to form yttrium oxide pinning. In addition, Y has a certain solid solubility in Nb and can also precipitate to form Cu(Y) solid solution pinning. Other rare earth elements are difficult to simultaneously have the above characteristics.
[0012] In addition, by constructing a diffusion couple, the growth difference of the Nb3Sn superconducting material in the doped and undoped samples can be directly compared, the influence mechanism of the doping element on the synthesis of the Nb3Sn superconducting material and the final critical current density can be analyzed, and the diffusion couple preparation process can be used for the research on the growth kinetics of the Nb3Sn superconducting material. Compared with the traditional wire preparation process for researching the influence of the doping element on the Nb3Sn superconductor, the diffusion couple preparation process is simple, efficient, and can be used for batch research.
[0013] The following is a preferred technical solution of the present application, but is not a limitation on the technical solutions provided by the present application. Through the following preferred technical solution, the technical purpose and beneficial effects of the present application can be better achieved and realized.
[0014] Preferably, the mass fraction of Y in the Nb-Y alloy ingot is 0.2wt.%-1wt.%, for example, it can be 0.2wt.%, 0.25wt.%, 0.3wt.%, 0.35wt.%, 0.4wt.%, 0.45wt.%, 0.5wt.%, 0.55wt.%, 0.6wt.%, 0.65wt.%, 0.7wt.%, 0.75wt.%, 0.8wt.%, 0.85wt.%, 0.9wt.%, 0.95wt.%, or 1wt.%, but is not limited to the listed values, and other unlisted values within the value range are also applicable.
[0015] Preferably, the mass fraction of Y in the Cu-Sn-Y alloy ingot is 0.2wt.%-1wt.%, for example, it can be 0.2wt.%, 0.25wt.%, 0.3wt.%, 0.35wt.%, 0.4wt.%, 0.45wt.%, 0.5wt.%, 0.55wt.%, 0.6wt.%, 0.65wt.%, 0.7wt.%, 0.75wt.%, 0.8wt.%, 0.85wt.%, 0.9wt.%, 0.95wt.%, or 1wt.%, but is not limited to the listed values, and other unlisted values within the value range are also applicable.
[0016] The application further controls the mass fraction of Y in the Nb-Y alloy ingot to be 0.2wt.%-1wt.% or the mass fraction of Y in the Cu-Sn-Y alloy ingot to be 0.2wt.%-1wt.%. If the Y content is too small, it may not promote the diffusion of Sn due to insufficient content. If the Y content is too large, it will hinder the diffusion process of Sn, thereby reducing the critical current density.
[0017] Preferably, the mass fraction of Sn in the Cu-Sn alloy ingot is 5wt.%-15wt.%, for example, it can be 5wt.%, 6wt.%, 7wt.%, 8wt.%, 9wt.%, 10wt.%, 11wt.%, 12wt.%, 13wt.%, 14wt.%, or 15wt.%, but is not limited to the listed values, and other values not listed in the value range are also applicable.
[0018] Preferably, the mass fraction of Sn in the Cu-Sn-Y alloy ingot is 5wt.%-15wt.%, for example, it can be 5wt.%, 6wt.%, 7wt.%, 8wt.%, 9wt.%, 10wt.%, 11wt.%, 12wt.%, 13wt.%, 14wt.%, or 15wt.%, but is not limited to the listed values, and other values not listed in the value range are also applicable.
[0019] Preferably, the diffusion annealing is carried out in a protective atmosphere.
[0020] Preferably, the protective atmosphere includes argon.
[0021] Preferably, the temperature of the diffusion annealing is 600℃-800℃, for example, it can be 600℃, 650℃, 700℃, 750℃, or 800℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.
[0022] The application further controls the temperature of the diffusion annealing to be 600℃-800℃. Under this diffusion annealing process, Sn forms a Nb3Sn superconducting phase by diffusion. If the temperature of the diffusion annealing is too low, it will form phases such as NbSn2 and Nb6Sn5, thereby reducing the content of the Nb3Sn phase. If the temperature of the diffusion annealing is too high, although it will promote the diffusion of Sn, it will also cause excessive growth of the Nb3Sn grains, thereby reducing the critical current density.
[0023] Preferably, the time of the diffusion annealing is 50h-80h, for example, it can be 50h, 52h, 55h, 58h, 60h, 62h, 65h, 68h, 70h, 72h, 75h, 78h, or 80h, but is not limited to the listed values, and other values not listed in the value range are also applicable.
[0024] Preferably, the fixing device can be a stainless steel sleeve and a screw.
[0025] Preferably, the component A and the component B can be any shape with a planar structure, such as a cube, a cuboid, a cylinder, etc., and preferably a cube and / or a cuboid for easy preparation and observation.
[0026] Preferably, the size (length x width x thickness) of the component A and the component B is independently (1 mm-10 mm) x (1 mm-10 mm) x (1 mm-10 mm), for example, it can be 5 mm x 10 mm x 2 mm, 1 mm x 5 mm x 2 mm, 2 mm x 5 mm x 2 mm, 3 mm x 5 mm x 2 mm, 5 mm x 5 mm x 2 mm, 5 mm x 10 mm x 1 mm, 5 mm x 10 mm x 2 mm, 5 mm x 10 mm x 3 mm, 5 mm x 10 mm x 4 mm, 5 mm x 10 mm x 5 mm, or 5 mm x 5 mm x 5 mm, but not limited to the listed values, and other values not listed within the value range are also applicable.
[0027] Preferably, the size of the component A and the component B can be the same or different, and preferably the size of the component A and the component B is the same for easy preparation and observation.
[0028] Preferably, the component A and the component B further include polishing the surface of the component A and the component B, respectively, before surface bonding.
[0029] Preferably, the polishing step includes using 1000-2000 mesh sandpaper for polishing, then using polishing liquid for polishing, ultrasonic cleaning with ethanol and drying.
[0030] Preferably, the preparation method of the Nb-Y alloy ingot comprises:
[0031] Mixing Nb and Y according to the mass ratio, and obtaining the Nb-Y alloy ingot through first melting and first annealing.
[0032] Preferably, the first melting is performed in a vacuum environment.
[0033] Preferably, the first annealing is performed in an inert atmosphere.
[0034] Preferably, the inert atmosphere includes argon.
[0035] Preferably, the temperature of the first annealing is 800-1000°C, for example, it can be 800°C, 820°C, 850°C, 880°C, 900°C, 920°C, 950°C, 980°C, or 1000°C, but not limited to the listed values, and other values not listed within the value range are also applicable.
[0036] Preferably, the first annealing time is 50h-100h, for example, it can be 50h, 55h, 60h, 65h, 70h, 75h, 80h, 85h, 90h, 95h or 100h, but is not limited to the listed values, and other values not listed in the value range are also applicable.
[0037] Preferably, the preparation method of the Cu-Sn alloy ingot or Cu-Sn-Y alloy ingot comprises:
[0038] The required elemental metals are mixed according to the mass ratio, and the Cu-Sn alloy ingot or Cu-Sn-Y alloy ingot is obtained through second melting and second annealing.
[0039] Preferably, the second melting is carried out in a vacuum environment.
[0040] Preferably, the second annealing is carried out in an inert atmosphere.
[0041] Preferably, the inert atmosphere comprises argon.
[0042] Preferably, the second annealing temperature is 500℃-800℃, for example, it can be 500℃, 520℃, 550℃, 580℃, 600℃, 620℃, 650℃, 680℃, 700℃, 720℃, 750℃, 780℃ or 800℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.
[0043] Preferably, the second annealing time is 5h-10h, for example, it can be 5h, 5.55h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h or 10h, but is not limited to the listed values, and other values not listed in the value range are also applicable.
[0044] As a preferred technical solution of the preparation method of the present application, the preparation method comprises the following steps:
[0045] (1) Mix Nb and Y according to the mass ratio, carry out first melting in a vacuum environment, the first melting temperature is 2500℃-2600℃, and the time length is 5min-10min, then first anneal at 800℃-1000℃ under argon atmosphere for 50h-100h, to obtain an Nb-Y alloy ingot; mix Cu and Sn according to the mass ratio, carry out second melting in a vacuum environment, the second melting temperature is 1100℃-1200℃, and the time length is 3min-5min, then second anneal at 500℃-800℃ for 5h-10h, to obtain a Cu-Sn alloy ingot;
[0046] (2) Polishing treatment of the Nb-Y alloy ingot and the Cu-Sn alloy ingot: using 1000-2000 mesh sandpaper to polish the surface of the Nb-Y alloy ingot and the Cu-Sn alloy ingot, then using polishing liquid for polishing, ultrasonic cleaning with ethanol and drying;
[0047] (3) The polished surface of the Nb-Y alloy ingot and the Cu-Sn alloy ingot obtained in step (2) is bonded, placed in a fixing device to form a diffusion couple, and subjected to diffusion annealing treatment at 600-800℃ for 50-80h in an argon atmosphere to obtain a Nb3Sn superconducting material.
[0048] In a second aspect, the present application provides a Nb3Sn superconducting material prepared according to the method of the first aspect; the thickness of the Nb3Sn superconducting material is more than 100μm.
[0049] The thickness of the Nb3Sn superconducting material is more than 100μm, which is thicker than the Nb3Sn superconducting material prepared by the method of the prior art, and the critical current density is 5.01×10 5 A / m 2 The above has excellent superconducting performance.
[0050] In a third aspect, the present application provides a use of the Nb3Sn superconducting material of the first aspect, wherein the diffusion couple process is used to prepare the Nb3Sn superconducting material for the field of superconducting technology.
[0051] The numerical range of the present application includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed, and the present application does not exhaustively list the specific point values included in the range for the sake of brevity and simplicity.
[0052] Compared with the prior art, the present application has at least the following beneficial effects:
[0053] (1) The present application can accelerate the growth rate of Nb3Sn by doping Y element and rare earth elements to promote the diffusion rate of Sn, and at the same time, the rare earth element Y has strong oxygen affinity and can form Y2O3 nanoparticles by oxidation, which can act as artificial pinning centers to improve the magnetic flux pinning force and thus improve the critical current density of the interface Nb3Sn superconducting material.
[0054] (2) The application can intuitively compare the growth difference of Nb3Sn superconducting materials in doped and undoped samples by constructing diffusion couples, facilitate the analysis of the influence mechanism of doping elements on the synthesis of Nb3Sn superconducting materials and the final critical current density, and can be used for the study of the growth kinetics of Nb3Sn superconducting materials. Compared with the traditional wire preparation process for studying the influence of doping elements on Nb3Sn superconductor, the diffusion couple preparation process is simple, efficient, and can be batched.
[0055] (3) The thickness of the Nb3Sn superconducting material is more than 100 μm, and the critical current density is 5.01 x 10 5 A / m 2 The above has excellent superconducting performance. BRIEF DESCRIPTION OF DRAWINGS
[0056] Figure 1 is a schematic diagram of the diffusion couple fixing device in Example 1 of the application, wherein 1 represents a screw, 2 represents a stainless steel sleeve, 3 represents an alumina gasket, 4 represents a Nb-Y alloy ingot, and 5 represents a Cu-Sn alloy ingot.
[0057] Figure 2 is a SEM image of the diffusion couple interface obtained in Example 1 of the application, wherein 6 represents a Cu-Sn alloy ingot, 7 represents a Nb3Sn superconducting material, 8 represents Y2O3 particles, and 9 represents a Nb-Y alloy ingot.
[0058] Figure 3 is a SEM image of the diffusion couple interface obtained in Example 2 of the application, wherein 6 represents a Cu-Sn alloy ingot, 7 represents a Nb3Sn superconducting material, 8 represents Y2O3 particles, and 9 represents a Nb-Y alloy ingot.
[0059] Figure 4 is a SEM image of the diffusion couple interface obtained in Example 3 of the application, wherein 6 represents a Cu-Sn alloy ingot, 7 represents a Nb3Sn superconducting material, 8 represents Y2O3 particles, and 9 represents a Nb-Y alloy ingot.
[0060] Figure 5 is a SEM image of the diffusion couple interface obtained in Example 4 of the application, wherein 7 represents a Nb3Sn superconducting material, 10 represents a Cu-Sn-Y alloy ingot, and 11 represents a Nb single block.
[0061] Figure 6 is a SEM image of the diffusion couple interface obtained in Comparative Example 1 of the application, wherein 6 represents a Cu-Sn alloy ingot, 7 represents a Nb3Sn superconducting material, and 11 represents a Cu-Sn-Y alloy ingot.
[0062] Figure 7is a SEM image of the interface of the diffusion couple obtained in Comparative Example 2 of the present application, wherein 6 represents a Cu-Sn alloy ingot, 7 represents Nb3Sn superconducting material, and 12 represents a Nb-Ni alloy ingot.
[0063] Figure 8 is a graph of critical current density test results of the diffusion couple block obtained in Example 1 and Comparative Example 1 of the present application.
[0064] Figure 9 is a graph of critical current density test results of the diffusion couple block obtained in Example 2 and Comparative Example 1 of the present application.
[0065] Figure 10 is a graph of critical current density test results of the diffusion couple block obtained in Example 3 and Comparative Example 1 of the present application.
[0066] Figure 11 is a graph of critical current density test results of the diffusion couple block obtained in Example 4 and Comparative Example 1 of the present application.
[0067] Figure 12 is a graph of critical current density test results of the diffusion couple block obtained in Example 1 and Comparative Example 2 of the present application;
[0068] Figure 13 is a graph of thickness of the Nb3Sn superconducting material in the diffusion couples of Example 1-Example 4 and Comparative Example 1-Comparative Example 2 of the present application. DETAILED DESCRIPTION
[0069] The technical solutions of the present application will be further described below in combination with the accompanying drawings and through specific embodiments. However, the following examples are only simple examples of the present application and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims.
[0070] In the following examples and comparative examples, all reagents and consumables are purchased from conventional reagent manufacturers in the art unless otherwise specified; and the experimental methods and technical means used are conventional methods and means in the art unless otherwise specified.
[0071] For convenience of comparison, the pressure applied by the fixing device in the examples and comparative examples of the present application is kept consistent, i.e., the pressure applied by the adhering surface of component A and component B is the same between different examples and comparative examples.
[0072] Example 1
[0073] This embodiment provides a method for preparing Nb3Sn superconducting material by diffusion couple process, using a fixing device as shown in Figure 1 The method comprises the following steps:
[0074] (1) Mix Nb and Y according to the mass ratio of 0.99:0.01, first melt at 2600℃ for 5 min in a vacuum environment, then first anneal at 900℃ for 50 h in an argon atmosphere to obtain a Nb-1wt.%Y alloy ingot; mix Cu and Sn according to the mass ratio of 0.9:0.1, second melt in a vacuum environment, second anneal at 600℃ for 6 h in an argon atmosphere to obtain a Cu-10wt.%Sn alloy ingot;
[0075] (2) Cut the alloy ingot after homogenization annealing into an alloy block with a size of 5mmx10mmx2mm (thickness) by using a diamond wire cutting machine, then polish the Nb-1wt.%Y alloy ingot and the Cu-10wt.%Sn alloy ingot: polish the surface of the Nb-1wt.%Y alloy ingot and the Cu-10wt.%Sn alloy ingot by using 1000 mesh sandpaper, then polish by using polishing liquid, ultrasonic clean by using ethanol and dry;
[0076] (3) Paste the polished surfaces of the Nb-1wt.%Y alloy ingot 4 and the Cu-10wt.%Sn alloy ingot 5 obtained in step (2), apply mechanical pressure to them by using a stainless steel sleeve 2 and a screw 1 to fix and lock them, and insulate the space between the upper surface of the Nb-1wt.%Y alloy ingot 4 and the screw 1 and the space between the lower surface of the Cu-10wt.%Sn alloy ingot 5 and the stainless steel sleeve 2 by using an alumina sheet 3 to form a diffusion couple, diffusion anneal at 800℃ in an argon atmosphere for 80 h to obtain a Nb3Sn superconducting material;
[0077] The SEM image of the Nb3Sn diffusion couple interface is shown in Figure 2 From Figure 2 it can be seen that the target Nb3Sn superconducting material is formed after diffusion annealing, the thickness of the finally formed Nb3Sn superconducting material is 148μm, and the layer thickness shows uniform distribution, which shows that the diffusion couple process can be used to prepare the Nb3Sn superconducting material, and it can also be seen that there are nanoscale black spots in the Nb3Sn superconducting material, which are Y2O3 particles by EDS point scanning test, and these oxide particles may act as magnetic flux pinning centers, which have a positive effect on the improvement of critical current density.
[0078] Example 2
[0079] The embodiment provides a method for preparing a Nb3Sn superconducting material by a diffusion couple process, which is different from example 1 only in that the diffusion annealing temperature in step (3) is changed from 800℃ to 750℃, and the remaining steps are unchanged.
[0080] The SEM image of the Nb3Sn diffusion couple interface is shown in Figure 3 From Figure 3As can be seen, the thickness of the Nb3Sn superconducting material in the diffusion-annealed sample at 750℃ is 134μm, which is thinner than the thickness of the Nb3Sn superconducting material in Example 1 (148μm) in the diffusion-annealed sample at 800℃. This indicates that increasing the diffusion annealing temperature within a certain range will promote Sn diffusion, thereby generating a thicker Nb3Sn superconducting material.
[0081] Example 3
[0082] This embodiment provides a method for preparing Nb3Sn superconducting materials using a diffusion couple process. The only difference from Embodiment 1 is that in step (1), the mass ratio of Nb to Y changes from 0.99:0.01 to 0.995:0.005, resulting in an Nb-0.5wt.%Y alloy ingot. The remaining steps remain unchanged.
[0083] SEM image of the Nb3Sn diffusion couple interface as shown in Figure Figure 4 As shown, from Figure 4 As can be seen, the thickness of the Nb3Sn superconducting layer of the sample doped with 0.5 wt.% Y is 137 μm, which is thinner than the thickness of the Nb3Sn superconducting material of the sample doped with 1 wt.% Y in Example 1 (148 μm). This indicates that increasing the doping amount of Y within a certain range will promote the diffusion of Sn, thereby generating a thicker Nb3Sn superconducting material.
[0084] Example 4
[0085] This embodiment provides a method for preparing Nb3Sn superconducting materials using a diffusion couple process, the method comprising the following steps:
[0086] (1) Commercial Nb elemental block (purity: 99.99 wt.%) was used as component A; Cu, Sn and Y were mixed in a mass ratio of 0.895:0.1:0.005, and a second melting was carried out at 1200℃ for 3 min in a vacuum environment, followed by a second annealing at 800℃ for 10 h in an argon atmosphere to obtain Cu-10wt.%Sn-0.5wt.%Y alloy ingot;
[0087] (2) The homogenized annealed alloy ingot was cut into alloy blocks with a thickness of 5mm×10mm×2mm using a diamond wire cutter. Then, the Nb element block and Cu-10wt.%Sn-0.5wt.%Y alloy ingot were polished: the surface of the Nb element block and Cu-10wt.%Sn-0.5wt.%Y alloy ingot was polished with 2000-grit sandpaper, then polished with polishing liquid, ultrasonically cleaned with ethanol and dried.
[0088] (3) The Nb elemental block obtained in step (2) is bonded to the polished surface of Cu-10wt.%Sn-0.5wt.%Y alloy ingot, and placed in a fixing device to form a diffusion couple. Under argon atmosphere and 800℃, diffusion annealing is performed for 70h to obtain Nb3Sn superconducting material.
[0089] SEM image of the Nb3Sn diffusion couple interface as shown in Figure Figure 5 As shown, from Figure 5 As can be seen, after diffusion annealing, the target Nb3Sn superconducting material was formed, and the layer thickness showed a uniform distribution. The final Nb3Sn superconducting material thickness was 154 μm, which is nearly 5 times that of the undoped bulk material (32 μm). This shows that by doping Y element in Cu-Sn component, the content of Nb3Sn superconducting material can also be significantly increased, which is very beneficial to improving critical current density.
[0090] Example 5
[0091] This embodiment provides a method for preparing Nb3Sn superconducting materials using a diffusion couple process. The only difference from Embodiment 1 is that the diffusion annealing temperature in step (3) is changed from 800℃ to 500℃, while the other steps remain unchanged.
[0092] Example 6
[0093] This embodiment provides a method for preparing Nb3Sn superconducting materials using a diffusion couple process. The only difference from Embodiment 1 is that the diffusion annealing temperature in step (3) is changed from 800℃ to 1000℃, while the other steps remain unchanged.
[0094] Example 7
[0095] This embodiment provides a method for preparing Nb3Sn superconducting materials using a diffusion couple process. The only difference from Embodiment 1 is that the mass ratio of Nb to Y in step (1) is changed from 0.99:0.01 to 0.999:0.001, resulting in an Nb-0.1wt.%Y alloy ingot. The remaining steps remain unchanged.
[0096] Example 8
[0097] This embodiment provides a method for preparing Nb3Sn superconducting materials using a diffusion couple process. The only difference from Embodiment 1 is that the mass ratio of Nb to Y in step (1) is changed from 0.99:0.01 to 0.95:0.05, resulting in an Nb-5wt.%Y alloy ingot. The remaining steps remain unchanged.
[0098] Comparative Example 1
[0099] The comparative example provides a method for preparing Nb3Sn superconducting material by diffusion couple process, which is different from example 1 only in that steps (1), (2) and (3) are replaced by Nb single block instead of Nb-1wt.% Y alloy ingot, and the remaining steps are unchanged.
[0100] The SEM image at the diffusion couple interface of Nb3Sn is shown in FIG. 2, and it can be known from the figure that when Y element is not doped in component A and component B, although Nb3Sn superconducting material is finally generated, the thickness of the Nb3Sn superconducting material is only 32 μm, which is far less than that of example 1. Figure 6 Figure 6 The SEM image at the diffusion couple interface of Nb3Sn is shown in FIG. 2, and it can be known from the figure that when Y element is not doped in component A and component B, although Nb3Sn superconducting material is finally generated, the thickness of the Nb3Sn superconducting material is only 32 μm, which is far less than that of example 1.
[0101] Comparative example 2
[0102] The comparative example provides a method for preparing Nb3Sn superconducting material by diffusion couple process, which is different from example 1 only in that step (1) is replaced by Ni instead of Y, and steps (2) and (3) are replaced by Nb-0.1wt.% Ni alloy ingot instead of Nb-0.1wt.% Y alloy ingot, and the remaining steps are unchanged.
[0103] The SEM image at the diffusion couple interface of Nb3Sn is shown in FIG. 2, and it can be known from the figure that when Y element is not doped in component A and component B, although Nb3Sn superconducting material is finally generated, the thickness of the Nb3Sn superconducting material is only 32 μm, which is far less than that of example 1. Figure 7 Figure 7 The SEM image at the diffusion couple interface of Nb3Sn is shown in FIG. 2, and it can be known from the figure that when Y element is not doped in component A and component B, although Nb3Sn superconducting material is finally generated, the thickness of the Nb3Sn superconducting material is only 32 μm, which is far less than that of example 1.
[0104] Test method: the conditions of critical current density test are that a 2mmx2mmx2mm cubic block is cut from the obtained diffusion couple Nb3Sn superconducting material, then hysteresis loop (M-H) is measured in the range of 0T-8T of external magnetic field at the temperature of 4.2K by using comprehensive physical property measurement system (PPMS), and finally the critical current density is calculated by using Bean model.
[0105] The diffusion couple process for preparing Nb3Sn superconducting material prepared in the examples and comparative examples is subjected to SEM test and critical current density test, and the test results are shown in Table 1 and FIG. 3. Figures 1-13
[0106] Figure 13 The thickness of the Nb3Sn superconducting material layer prepared in examples 1-4 and comparative examples 1-2 is shown, and it can be seen that the synthesis of Nb3Sn superconducting material can be significantly promoted by doping Y element in the component, and the content of Nb3Sn superconducting material is increased.
[0107] Figure 8 The critical current density test results of the diffusion couple blocks obtained from Example 1 and Comparative Example 1 are shown. As can be seen from the figure, the critical current density of the block doped with Y element in Nb is significantly higher than that of the undoped (Nb element) block in the whole test magnetic field range, which shows that the critical current density can be significantly improved by doping Y element in Nb component.
[0108] Figure 9 The critical current density test results of the diffusion couple blocks obtained from Example 2 and Comparative Example 1 are shown. As can be seen from the figure, the critical current density of the block doped with Y element in Nb is significantly higher than that of the undoped (Nb element) block in the whole test magnetic field range, which shows that the critical current density can be significantly improved by doping Y element in Nb component.
[0109] Figure 10 The critical current density test results of the diffusion couple blocks obtained from Example 3 and Comparative Example 1 are shown. As can be seen from the figure, the critical current density of the block doped with Y element in Nb is significantly higher than that of the undoped (Nb element) block in the whole test magnetic field range, which shows that the critical current density can be significantly improved by doping Y element in Nb component.
[0110] Figure 11 The critical current density test results of the diffusion couple blocks obtained from Example 4 and Comparative Example 1 are shown. As can be seen from the figure, the critical current density of the block doped with Y element in Nb is significantly higher than that of the undoped (Nb element) block in the whole test magnetic field range, which shows that the critical current density can be significantly improved by doping Y element in Nb component.
[0111] Figure 12 The critical current density test results of the diffusion couple blocks obtained from Example 1 and Comparative Example 2 are shown. As can be seen from the figure, the critical current density of the block doped with Y element in Nb is significantly higher than that of the block doped with Ni element in the whole test magnetic field range, which shows that the critical current density can be significantly improved by doping Y element in Nb component.
[0112] Table 1
[0113]
[0114]
[0115] As can be seen from the test results:
[0116] (1) From Example 1-Example 4, it can be seen that the present application can accelerate the growth rate of the Nb3Sn superconducting material by doping the rare earth element Y in the diffusion component, and the rare earth element Y has strong oxygen affinity, and the Y2O3 nanoparticles in the Nb3Sn layer can act as artificial pinning centers to improve the flux pinning force, thereby improving the critical current density of the interface Nb3Sn superconducting material.
[0117] (2) From Example 1 and Example 5-Example 6, it can be seen that the present application can further control the temperature of the diffusion annealing to be 600-800 DEG C, and under this diffusion annealing process, Sn forms a Nb3Sn superconducting phase by diffusion, and if the temperature of the diffusion annealing is too low, NbSn2 and Nb6Sn5 phases will be formed, thereby reducing the content of the Nb3Sn phase; if the temperature of the diffusion annealing is too high, although the diffusion of Sn will be promoted, but at the same time, the Nb3Sn grains will be excessively grown, thereby reducing the critical current density.
[0118] (3) From Example 1 and Example 7-Example 8, it can be seen that the present application can further control the mass fraction of Y in the Nb-Y alloy ingot to be 0.2wt.%-1wt.%, and if the Y content is too small, it may not promote the diffusion of Sn due to insufficient content; if the Y content is too large, it will hinder the diffusion process of Sn, thereby reducing the critical current density.
[0119] (4) From Example 1 and Comparative Example 1-Comparative Example 2, it can be seen that the present application can accelerate the growth rate of the Nb3Sn superconducting material by doping the specific rare earth element Y in the diffusion component, and the rare earth element Y has strong oxygen affinity, and the Y2O3 nanoparticles in the Nb3Sn layer can act as artificial pinning centers to improve the flux pinning force, thereby improving the critical current density of the interface Nb3Sn superconducting material.
[0120] In summary, the present application can accelerate the growth rate of the Nb3Sn superconducting material by doping the rare earth element Y in the diffusion component, and the rare earth element Y has strong oxygen affinity, and the Y2O3 nanoparticles in the Nb3Sn layer can act as artificial pinning centers to improve the flux pinning force, thereby improving the critical current density of the interface Nb3Sn superconducting material.
[0121] The applicant states that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and it should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought out by those skilled in the art, and all of them fall within the protection scope and disclosure scope of the present application.
Claims
1. A method of improving the critical current density of Nb3Sn by rare earth yttrium doping, characterized in that, The method comprises the following steps: The surface of the component A is adhered to the surface of the component B in a fixing device to form a diffusion couple, and the diffusion couple is diffusion annealed to obtain the Nb3Sn superconducting material; The component A comprises a Nb single-element ingot and / or a Nb-Y alloy ingot; The component B comprises a Cu-Sn alloy ingot and / or a Cu-Sn-Y alloy ingot; At least one of the component A and the component B contains Y.
2. The method of claim 1, wherein, The mass fraction of Y in the Nb-Y alloy ingot is 0.2wt.% to 1wt.%; Preferably, the mass fraction of Sn in the Cu-Sn alloy ingot is 5wt.% to 15wt.%; Preferably, the mass fraction of Y in the Cu-Sn-Y alloy ingot is 0.2wt.% to 1wt.%; Preferably, the mass fraction of Sn in the Cu-Sn-Y alloy ingot is 5wt.% to 15wt.%.
3. The method according to claim 1 or 2, characterized in that, The diffusion annealing is performed in a protective atmosphere; Preferably, the protective atmosphere comprises argon.
4. The method according to any one of claims 1 to 3, characterized in that, The temperature of the diffusion annealing is 600°C to 800°C; Preferably, the time of the diffusion annealing is 50h to 80h.
5. The method according to any one of claims 1 to 4, characterized in that, Before the surface of the component A is adhered to the surface of the component B, the surface of the component A and the surface of the component B are further subjected to polishing treatment respectively; Preferably, the polishing treatment comprises the following steps: polishing by using sandpaper with a mesh number of 1000 to 2000, then polishing by using polishing liquid, ultrasonic cleaning by using ethanol and drying.
6. The method according to any one of claims 1 to 5, characterized in that, The preparation method of the Nb-Y alloy ingot comprises the following steps: Nb and Y are mixed according to a mass ratio, and a Nb-Y alloy ingot is obtained through first melting and first annealing; Preferably, the first melting is performed in a vacuum environment; Preferably, the first annealing is performed in an inert atmosphere; Preferably, the inert atmosphere comprises argon; Preferably, the temperature of the first annealing is 800°C to 1000°C; Preferably, the time of the first annealing is 50h to 100h.
7. The method according to any one of claims 1 to 6, characterized in that, The preparation method of the Cu-Sn alloy ingot or the Cu-Sn-Y alloy ingot comprises the following steps: The required elemental metals are mixed according to a mass ratio, and a Cu-Sn alloy ingot or a Cu-Sn-Y alloy ingot is obtained through second melting and second annealing; Preferably, the second melting is performed in a vacuum environment; Preferably, the second annealing is performed in an inert atmosphere; Preferably, the inert atmosphere comprises argon; Preferably, the temperature of the second annealing is 500°C to 800°C; Preferably, the time of the second annealing is 5h to 10h.
8. The method according to any one of claims 1 to 7, characterized in that, The preparation method comprises the following steps: (1) Nb and Y are mixed according to a mass ratio, first melting is performed in a vacuum environment, the first melting temperature is 2500°C to 2600°C, and the time is 5min to 10min, then first annealing is performed in an argon atmosphere at 800°C to 1000°C for 50h to 100h to obtain a Nb-Y alloy ingot; Cu and Sn are mixed according to a mass ratio, second melting is performed in a vacuum environment, the second melting temperature is 1100°C to 1200°C, and the time is 3min to 5min, then second annealing is performed in an argon atmosphere at 500°C to 800°C for 5h to 10h to obtain a Cu-Sn alloy ingot; (2) polishing the Nb-Y alloy ingot and the Cu-Sn alloy ingot: using 1000-2000 mesh sandpaper to polish the surface of the Nb-Y alloy ingot and the Cu-Sn alloy ingot, then using polishing liquid to polish, using ethanol to ultrasonic clean and dry; (3) bonding the polished surface of the Nb-Y alloy ingot and the Cu-Sn alloy ingot obtained in step (2), placing in a fixing device to form a diffusion couple, under the condition of argon atmosphere, 600-800℃, diffusion annealing treatment for 50-80h, obtaining the Nb3Sn superconducting material.
9. A Nb3Sn superconducting material, characterized in that, The Nb3Sn superconducting material is prepared according to the method of any one of claims 1-8. The thickness of the Nb3Sn superconducting material is above 100μm.
10. Use of a Nb3Sn superconducting material as claimed in claim 9, characterized in that The Nb3Sn superconducting material is used in the field of superconducting technology.