Abstract
Nb3Al superconducting wires are fabricated by the Clad-Chip Extrusion (CCE) method which is characterized by extruding the chipped Nb-Al clad sheets. Maximum reduction ratio in CCE-processed Nb-Al composite wires is 3×106, which corresponds to the Nb-layer thickness of 80 nm. The obtained wires with reduction ratios from 1×105 to 3×106 are heat-treated at temperatures below 1300 K to form Nb3Al by solid-state diffusion and the influence of reduction ratio on superconductive properties is studied. The Nb-Al composite wires with a higher reduction ratio allow the preferential formation of A15 phase at those temperature ranges, which enhances the critical current density. The wire heat-treated under an optimized condition shows the critical transition temperature of 17.1 K and the critical current density of 108 A/m2 in the applied magnetic field of 18.8 T at 4.2 K.
