Angular dependence of residual strain in CuNb/(Nb, Ti)3Sn wires

We evaluated three-dimensional residual strains for practical Nb3Sn wires with different architectures and residual strains at low temperature by neutron diffraction, and the upper critical fields under the tensile strains were discussed on the basis of the three-dimensional strain model. We found that the angular dependence of the residual strain can be described well by the two representative strains, i.e. the axial and lateral strains. The differences in the three-dimensional residual strains, which depend on the wire architecture and mechanical treatment history, play an important role in the superconducting properties of composite Nb3Sn wires under axial stress/strain.