Study of the Specific Features of Kinetics Formation and Structure of the Superconducting Nb3Sn Phase in Technical Superconductors

Abstract

The growth kinetics of a layer of intermetallic compound Nb₃Sn in bronze-processed multifilamentary superconductors of different designs and diameters, developed and fabricated at the A.A. Bochvar High-Technology Research Institute of Inorganic Materials (JSC “VNIINM”), has been studied. The influence of diffusion annealing conditions in a wide range of temperatures and exposure times on the formation of Nb₃Sn phase in superconductors has been investigated by methods of metallographic analysis using optical microscopy, electron microscopy, and microanalysis. The structural features of Nb₃Sn layers in the initial formation stage and after long-term diffusion annealing are analyzed, their thickness is measured, and the grain structure and composition are studied. Recommendations on improvement of the diffusion annealing conditions for Nb₃Sn superconductors of different designs, aimed at obtaining high current-carrying ability, are elaborated.