クラッド・チップ押出し法によるNb₃Alの線材化とその超電導特性

抄録

A new fabrication technique of Nb₃Al wires, called the clad-chip extrusion (CCE) method, is proposed in this study. It is characterized by chipping and extruding Nb-Al clad sheets. The shear deformation stratifies Nb-Al clad chips in the extrusion process, and fine-multilayer Nb-Al wires are finally obtained by subsequent conventional drawing. An extruded Nb-Al composite bar shows excellent deformability in cold-working up to high reductions and Nb-Al composite wires with fine structure are easily fabricated because Nb plates containing low level oxygen are used as a starting material in this method.
Heat-treated Nb₃Al wires show the superconducting transition temperature of 17 K, the critical current density of 10⁸ A/m² in the field up to 15 T at 4.2 K and the critical field of 23.3 T is extrapolated from the Kramer plots.