Tensile and Bending Strain Tolerance of Ex Situ MgB2/Ni/Cu Superconductor Tape

This paper describes the strain tolerance of MgB₂/Ni/Cu tape produced by Columbus Superconductors subjected to tension and bending stress. A tension test instrument with freestanding sample was used for stress-strain, I_c-stress, and I_c-strain characteristics at liquid helium temperature. Bending of MgB₂/Ni/Cu tape to variable diameters was done at room temperature and in two directions: 1) with a Cu strip on the outer surface (Cu out) of a bent sample; and 2) with a Cu strip on the inner side (Cu in). I_c-bending strain characteristics were measured at 4.2 K and external field B = 6 T oriented perpendicularly to the sample's width. Obtained results have shown the strain limits, which should not be exceeded during the winding process of superconductor containing brittle MgB₂ filaments.