Dislocation and grain structure formation in Nb filaments of different geometry at fabrication of Nb3Sn-based superconducting wires

The structure of Nb filaments of different geometry artificially doped with NbTi alloy in Nb/Cu-Sn composites after various regimes of deformation beginning from the very first stages of fabrication of thin multifilamentary wires has been studied by transmission electron microscopy, optical microscopy and X-ray analysis. The structure of Nb filaments in composites of different designs is compared, and the development of dislocation and grain structure and texture of niobium in monolithic and assembled filaments under deformation with intermediate annealings is analyzed. •Assembled Nb filaments have better conformity with bronze in Nb/Cu-Sn composites.•Grain structure develops faster in assembled Nb filaments than in monolithic.•Application of assembled filaments ensures grain refinement in Nb.•Microhardness and dislocation density are higher in assembled Nb filaments.