Annealing effects on the electrical and superconducting properties of a Cu-15vol%Nb composite conductor

In this paper, annealing effects on the electrical and superconducting properties of a multifilamentary Cu-Nb composite were investigated. During annealing, noticeable changes in the microstructure take place, in special those related to recovery and recrystallization of copper and niobium followed by spheroidization and further coarsening of the Nb-filaments. Results show that spheroidization becomes significant only above 800°C and, even after annealing at severe conditions, e.g., 1050°C for 32 h, the continuity of the niobium-conducting path is partially preserved. The influence of these microstructural changes on the superconducting and normal properties of the multifilamentary Cu-15vol%Nb composite conductor is discussed.