Correlation of superconductivity and microstructure in an in-situ formed Cu–20%Nb composite

The normal and superconducting properties of a wire-drawn Cu–20%Nb alloy, forming a fibre reinforced in-situ composite, are investigated. The results are correlated to microstructural attributes of the composite and compared to findings in analogously processed pure Cu. The microstructure of Cu–20%Nb is characterized by the curled and elongated morphology of the superconducting Nb ribbons which are embedded in the Cu matrix. Whereas superconductivity in the heavily deformed composite is accomplished by the Nb filaments, the normal conducting properties which are determined by the Cu phase are considerably influenced by the Nb filament spacings. Only a slight dependence of superconductivity on the enhancement of the density of internal boundaries due to different degrees of deformation was observed.