Influence of mechanical-thermal treatment on the microstructure and current-carrying capacity of Nb-Ti-superconductor

• Main Authors: Storozhilov, G.E., Andrievskaya, N.F., Tikhonovsky, M.A.
• Format: Article
• Language: English
• Published: Національний науковий центр «Харківський фізико-технічний інститут» НАН України 2020
• Series: Вопросы атомной науки и техники
• Subjects: Physics and the technology of construction materials
• Online Access: http://dspace.nbuv.gov.ua/handle/123456789/194744

A correlation between the modes of mechanical-thermal treatment, main microstructure parameters and the critical current density Jc in the superconducting alloy Nb-49 wt.% Ti was established. The studies were carried out on the alloy that was preliminary deformed by the “upsetting-extrusion” severe plastic deformation (SPD) method and subsequently drawn with multiple intermediate heat treatments (HT) at 390 °C for 400 and 2000 h. After completion of the heat treatments, the superconductor was finally drawn with the degree of deformation efin. It was shown that the volume fraction of a-Ti phase precipitates increases with the increasing in number of heat treatments up to ≈ 24 and 27% for a total heat treatment duration of 400 and 2000 h, respectively, and reaches maximum values at HT quantity of 4-5 and 7. The highest critical current density level in a magnetic field 5 T, Jc ≈ 3.8*105 A/cm2, was obtained for a total heat treatments duration of 2000 h, 7 number of HT and final true strain ≈ 5.05. The dependence of the pinning volume force Fp on the reduced magnetic field b in such superconductor is described by a function in form Fp ~ b(1-b)2, a characteristic of superconducting materials with strong vortex magnetic lattice on the precipitates.