Effect of Doping, Composite Geometry and Diffusion Annealing Schedules on the Structure of Nb_3Sn Layers in Nb/Cu-Sn Wires

摘要

Kinetics of formation of superconducting Nb_3Sn layers and the structure of bronze-processed Nb/Cu-Sn composites with Zr, Zn or Mg-doped matrixes or Ti-doped Nb filaments of different geometry have been studied by the methods of TEM, SEM and electron-probe microanalysis. All the doping elements have been found to accelerate the rate of growth of the diffusion Nb_3Sn layers and consequently their thickness. Correlation between the diffusion annealing schedules, the geometry of Nb filaments, the structure of the diffusion Nb_3Sn layers and the current-carrying characteristics of multifilamentary Nb/Cu-Sn composites has been established.