Ex-situ PIT法 Nb3Al線材の作製と特性

Abstract

A15 Nb3Al has gained much interests for high-field and large-scale applications due to its excellent critical current density Jc and strain tolerance. However, the shift of Nb3Al composition from stoichiometry at temperatures below 1800°C causes difficulties in the fabrication of conductors with inherent Nb3Al characteristics. In this study, Nb3Al powders prepared by arc melting in an Ar / H2 atmosphere were encased in a sheath and fabricated into tapes through the ex-situ PIT (Powder in Tube) process. The present study revealed that the oxygen content in the Nb3Al powder plays a crucial role in yielding large Jc in the tape. Furthermore, the addition of Ag powder to the Nb3Al powder was found to appreciably enhance the Jc of the tape in lower fields. The superconducting performance of the tapes is discussed in relating to their structures.