Stress effects on superconducting properties of the composite-processed V2(Hf,Zr)

The superconducting critical current Ic (4.2 K) of V2(Hf,Zr) composite tape was measured under tensile load. Ic values of the V2(Hf,Zr) composite tape do not change at all up to a strain level of 0.55%, and then decrease irreversibly with respect to strain, although the stress-strain curves for these tapes exhibit no irreversible behavior. Many cracks were observed in the V2(Hf,Zr) layer of the composite tape strained up to 0.6%. Thermal expansion data indicate that the residual tensile stress may be produced in the V2(Hf,Zr) layer by the large thermal contraction of the layer and may reduce the strain tolerance of the composite tape.