The superconducting Nb Ti alloy capillary tube comprises Mg, B, La, Ti and residual Nb; In the process of preparation, niobium sheet and titanium sheet are first melted, then magnesium bar and boron particle are added for smelting to produce ingot, which is then melted further, La is added for refining to produce electrode rod, and the electrode rod is smelted by vacuum consumable electric arc furnace to produce the resulting ingot, and then the ingot is heated and forged to produce forging rod, which is then skinning to produce alloy rod, perforated to produce tube blank. Finally, the tube blank was annealed and the capillary tube was prepared by reducing the diameter for many times. The low-temperature superconducting Nb Ti alloy capillary of the invention has high purity, no porosity, dense structure, fine and uniform grain, and the average grain is less than 60μm. At the same time, the preparation method is simple and operable.
With the development of science and technology, great breakthroughs have been made in the research of superconductivity theory and new materials. However, under the existing technology conditions, most superconducting materials with important practical value are alloys or compounds. As far as the domestic market is concerned, the common superconducting alloy materials are Nb-Zr and Nb-Ti, which are mainly used in the manufacture of various types of magnets, superconducting power cables, communication cables and superconducting electrical components. The results show that the main factors affecting the critical temperature Tc, critical magnetic field Hc and critical current density Ic of Nb-Ti superconducting materials are the composition, microstructure and electronic structure of Nb-Ti alloy materials as well as the internal force between electrons and lattice vibration. Therefore, it is very important to control the composition, inclusions, precipitates, dislocations and composition inhomogeneity of alloy materials and internal microstructure.
Preferably, the capillary prepared by the invention has a diameter of less than 3mm, a wall thickness of 0.1~0.3mm and a length of 1~10m. In the method of preparing the above low temperature superconducting Nb-Ti alloy capillary tubes, the high melting point Nb non-melts are eliminated through secondary vacuum melting to improve the uniformity of micro and macro components. At the same time, the vacuum consumable electric arc furnace is used to further remove the gas and evaporate the impurities, especially the high density impurities, so as to improve the plasticity of niobium-titanium alloy and facilitate forging. And make the role of trace magnesium, boron and rare earth elements more fully, make the alloy microstructure more refined, more uniform composition, and the vacuum annealing treatment of the tube blank before reducing the size of cold drawing, can avoid the oxidation of the alloy in the annealing process, and refine the grain, make the grain size more uniform, improve the alloy plasticity, reduce the work hardening rate, multiple vacuum annealing can improve the uniformity of mechanical properties.
