Static stress effects in superconducting composites: Part I. Effect of uniaxial tensile stress on resistive critical field of Cu–Nb composites Original Research Article

Multifilamentary Cu–Nb in situ composite wires were subjected to tensile tests in liquid helium environment to study influence of the stress σ on resistive critical field Hr of the composites. External magnetic field H was parallel to wire axis and 4-probe scheme for resistive measurements was applied. The wires had various diameters, that is they differed in their overall manufacturing deformation. Our experiments evidence that values of both the critical fields Hr0 of the initial composites and stress sensitivity of the fields dHr/dσ are noticeably higher than those referenced for niobium. We conclude that it is the dislocation structure of Nb filaments and its effect on Ginzburg–Landau parameter and thermodynamic critical field Hc of the filaments that determine the observed dependences.