TENSILE STRAIN TRANSVERSE COMPRESSIVE STRESS EFFECTS IN BRONZE-PROCESSED NB-MATRIX NB3SN WIRES

Mechanical properties and the strain/stress dependence of the critical current I-c of Nb-matrix Nb3Sn multifilamentary wires fabricated through bronze route were evaluated up to a magnetic field of 14T at 4.2K. The wire showed a 0.2% proof stress of 550MPa, which is 3.4 times higher than that In the conventional bronze processed Nb3Sn wires. The strain sensitivity of I-c and the reversible strain limit, 0.8%, were almost the same, but the axial tensile strain for the peak I-c, 0.1%, was small as compared with those in the conventional wires. On the other hand, the transverse compressive stress sensitivity of I-c was remarkably low. The irreversible stress where I-c on unloading no longer recovers to the initial value was larger than 300MPa, which is several times higher than those in conventional wires. Thus, these results show that the wire is highly tolerant to the external stress/strain.