Bi-2212 tapes and coils fabricated using Ag-Mg-Zr substrates

It is difficult to use Bi-2212/Ag composite tapes to high field superconducting magnet system, because of poor mechanical tolerance of annealed pure Ag against strong electromagnetic force. In this work, we tried to use Ag-Mg-Zr alloys as substrates of Bi-2212 tape conductors. Yield strength of the tape significantly increased with increasing Mg and Zr concentration. For the Ag-0.15at%(Mg,Zr) tape, yield strength of about 120MPa was obtained. This value was about three times higher than that of pure Ag tape. The Bi-2212/(Ag-alloy) tape conductors were fabricated applying doctor blade process or dip-coating process. Addition of second element to Ag substrate decreased Jc of the Bi-2212 layer. However, coil made with Ag-Mg-Zr alloy substrate showed better superconducting properties in high magnetic fields than that made using pure Ag, because of improved mechanical tolerance.