CORRELATION OF SUPERCONDUCTIVITY AND MICROSTRUCTURE IN AN IN-SITU FORMED CU-20-PERCENT-NB COMPOSITE

The normal and superconducting properties of a wire-drawn Cu-20% Nb al loy, forming a fibre reinforced-in-situ composite, are investigated. T he results are correlated to microstructural attributes of the composi te and compared to findings in analogously processed pure Cu. The micr ostructure of Cu-20%Nb is characterized by the curled and elongated mo rphology of the superconducting Nb ribbons which are embedded in the C u 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 th e Nb filament spacings. Only a slight dependence of superconductivity on the enhancement of the density of internal boundaries due to differ ent degrees of deformation was observed.