クラッド-チップ押出し法による合金系超伝導材料の線材化

Abstract

This paper describes a new fabrication process of V-Ti and Nb-Ti superconducting alloy wires by the clad-chip extrusion (CCE) method. It is one of unique fabrication method of alloy wire without melting and casting process. The CCE method is characterized by the extrusion of thin chips of metal-clad sheet. Its chemical composition is controlled by the thickness ratio of the layers of constituent metals at clad-rolling. The CCE method produces the segregation-free composite because each chip is regarded as the deformation element with the intended chemical composition. The CCE-processed precursor wires with fine-layered structure of constituent metals are then converted to the alloys with the intended chemical composition by the heat treatment of solid state diffusion. The finally obtained wires are measured the critical transition temperature Tc and the critical current density Jc at 4.2 K under the applied magnetic field up to 9 T. The present experiments showed that V-Ti and Nb-Ti superconducting wires were successfully fabricated by the CCE method and the following diffusive heat treatment. Their superconducting properties were measured as follows; (1) 7.82 K of Tc and 80 A/mm2 of Jc at 6 T for the V-Ti wire. (2) 10.0 K of Tc and 100 A/mm2 of Jc at 8 T for the Nb-Ti wire.