Superconducting current capacities of composite-processed Laves phase tapes, V/HfxZr1−x

C-15 crystal-type Laves phase compounds, V2HfxZr1−x, were fabricated into a tape by a composite process in which the Laves phase layers were formed by the diffusion between the vanadium sheath and the HfxZr1−x alloy core. In the composition range 0.4 ⩾ x ⩾ 0.3, the composite tape showed the maximum values of superconducting transition temperature, upper critical field, and critical current density. The critical current of the tape did not degrade by winding into coils with diameters larger than 20 mm.