Changes of Superconducting Properties Due to the Unidirectional Tensile Deformation on Bronze-Processed Nb3Sn Multifilamentary Wires Using Various Cu-Sn-Zn Ternary Alloy Matrices

The degradation of transport current property by the mechanical strain on the practical Nb3Sn wire is a serious problem for the future fusion magnet operated under higher electromagnetic force. Recently, we developed various Zinc (Zn) solid solution ternary Cu-Sn alloy (Cu-Sn-Zn) matrices for the internal strengthened matrix and Nb3Sn multifilamentary precursor wires using various Cu-Sn-Zn matrices through the conventional bronze process. After the Nb3Sn synthesis heat treatment, the additional Zn remained in the matrix and it may act as a solid solution strength factor of the matrix. We carried out the unidirectional tensile test under 4.2 K and 15 T on the Nb3Sn wires using various Cu-Sn-Zn matrices in order to investigate the remaining Zn effect on the mechanical property. The peak tensile stress in the maximum critical current density on the 10 mass% Zn additional sample was obtained to approximately 200 MPa and it became remarkably higher compared with conventional bronze processed Nb3Sn wire. This tensile stress was similar to the CuNb and ODS-Cu reinforced Nb3Sn wires. The internal strengthened matrix due to the solid solution was one of the most effective methods for improving mechanical property of Nb3Sn wire.