Degradation mechanism of Nb3Sn composite wires under tensile strain at 4.2K

Bronze-processed Nb3Sn composite wire conductors exhibit changes in their superconducting parameters when strained in tension. This paper describes a detailed study of the effect of strain on critical current and an analysis by optical and SEM techniques of crack formation in the Nb3Sn layer under strain. The effect of strain history on both reversible and irreversible changes in critical current and the roles of differential thermal contraction induced residual strains and of Nb3Sn cracking are discussed.