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Information × Registration Number 0203U008360, 0101U006705 , R & D reports Title . Development niobium - titanium superconductors with high a critical current density and studying their thin structure popup.stage_title Head Chernyi Oleg Vladimirovich, Registration Date 11-11-2003 Organization National Science Center "Kharkiv Institute of Physics and Technology popup.description2 The goal of this project has been to search for ways to increase the critical current density, Jc, in superconducting Nb-Ti and Nb-Ti-Ta alloys, by studying and quantifying their microstructures and determining any correlation between Jc and the quantified parameters of the microstructure. The superconductors under investigation are based on binary Nb-48 wt.% Ti and ternary Nb-37%Ti-22 Ta (wt.%) alloys. At present commercial Nb-Ti based strands typically achieve Jc values of 2.5-3.2·105 А/сm2 in a magnetic field 5T at 4.2K. In such strands the amount of ?-Ti phase precipitated in Nb-Ti superconductors, (the key determinant in Jc) reaches 18-25 % of the filament volume after heat treatment of the alloy. Using complex long multistage treatments we increased the level of precipitation to 25-33 vol.% ?-Ti phase. Both FESEM and TEM methods were used to quantify the microstructures and the values obtained by the two techniques were found to be consistent with each other. The value of Jc(5Т, 4.2К) for both the 1- and 121-filamentary Nb-48 wt.%Ti superconductors exceeded 4·105 А/сm2. In this case the duration of heat treatments was approximately 1000 hrs and longer. In order to reduce the heat treatment duration, while retaining the high level of Jc, cryogenic processing was applied. A Jc(5Т, 4.2К) value in the sample deformed in cryogenic conditions (77K) of 3.7 105 А/cm2 was achieved, while reducing the total heat treatment duration by factor of 5. A patent was obtained related to these methods of processing for Nb-Ti superconductors. The highest current-carrying characteristics in the Nb-Ti alloys were obtained in rolled specimens with an oriented heterophase microstructures. The value of Jc(5Т, 4.2) obtained in this way, was as high as 6·105 A/сm?. For ternary Nb-Ti-Ta alloys the value of Jc is strongly dependent on the composition and microstructure parameters. A 210-filamentary Nb-37Ti-22Ta, wt.% superconductor was fabricated with a high value of Jc in a wide range of applied fields: Jc(10.4T,2.05K)=1.6·105 А/сm2; Jc(5T, 4.2K)=3·105 А/сm2. At the present time there is particular interest in superconducting composites with artificial pinning centers. Using ion-plasma deposition and magnetron sputtering methods, multilayer NbTi/Ti and NbTi/Fe composites were produced. For Nb-Ti/ Ti composites with the same thickness of superconducting and nonsuperconducting layer (11nm) Jc was as high as: Jc(2T, 4.2K)= 7.5·105 A/сm? and Jc(5T, 4.2K)= 4·105 A/сm2. The results obtained in this project reach or surpass the highest levels achieved in the field of applied superconductivity and can be used to obtain commercial superconducting strands of high quality for the manufacture of a number of superconducting magnetic systems. Product Description popup.authors popup.nrat_date 2020-04-02 Close