A multilayer superconducting tape of the Nb50Ti alloy obtained from a Cu/Nb/Ti composite with a solid phase

Abstract

Aim: Creation of multilayer superconducting tape made of Nb-Ti alloy. Methods: Using the methods of diffusion welding and packet rolling, for two cycles the prototypes of a multilayer tape based on a superconducting Nb–50%Ti alloy were made. Copper was used as a stabiliser of the superconducting state of the conductor. At the initial stage, a multilayer Nb-Ti pack was assembled from niobium and titanium foils. Copper stabilising layers were laid in the pack in the 2nd cycle of tape manufacturing. The mutual diffusion between the Nb- and Ti-layers took place generally at the expense of niobium diffusing into the layers of titanium, with the Nb-50%Ti alloy emerging in their place. Results: Measurements of the critical current I c with a perpendicular and parallel orientation of the magnetic field relative to the plane of the layers in the composite showed large anisotropy of I c , which was the result of the superconducting vortices fixing exclusively at the boundaries of the Nb-Ti-alloy and the Nb-solid solution. In general, the composite was capable of carrying large current in magnetic fields of 5-6 T without long-lasting low-temperature annealing for α-phase deposition, which is necessary in the case of Nb-Ti alloy composites produced by the known technology.