Influence of the tin diffusion process in multifilamentaryNb-Cu-Sn-Mg-Ta wire on Nb3Sn inter-filamentary bridging

摘要

An understanding of the correlation between the diffusion of tin from a high tin reservoir to the niobium filaments and the uniform properties of the intermetallic Nb3Sn diffusion layers of “high tin” multifilamentary conductors formed during multistage heat treatment is essential for the further improvement of the superconducting electromagnetic properties of advanced conductors. A detailed study has been made of the formation of the A-15 layer in multifilamentary Nb-Cu-Sn-Mg-Ta wire during multistage heat treatment. The importance of the rapid conversion of ε-Cu3Sn on filament displacement and mechanically induced inter-filamentary bridging within the individual bundles is demonstrated. It is concluded that the architecture of the conductor and phase development in the Cu-Sn-Mg matrix are the two major factors responsible for Nb3Sn inter-filamentary bridging