Characteristics of strengthened Ag substrates for Bi2Sr2CaCu2Ox doctor-bladed tapes

Abstract
The characteristics of Ag‐(Mg,Ni) and Ag‐Mn alloys as substrate materials for Bi2Sr2CaCu2Ox (Bi‐2212) tapes and their influence on the superconducting properties were studied. Alloying with Mg+Ni or Mn drastically decreased the grain size of Ag after heat treatment. The additives in Ag‐(Mg,Ni) and Ag‐Mn alloys were oxidized during heat treatment in air. Both the fine grain structure and the internal oxidation of the additives increased the mechanical strength of the Ag alloys. Both alloys were 3–6 times stronger than pure Ag. The superconducting properties of Bi‐2212 prepared on these Ag alloys were slightly degraded; however the critical current densities at 4.2 K in 8 T were still well over 104 A/cm2.