Properties of Ag-Mg alloy sheathed Bi-2223 tapes

The mechanical properties of 37 filament, pure Ag and Ag alloy (0.2 and 0.5 wt% Mg) sheathed Bi-2223 high temperature superconductor tapes were invest igated. The use of Ag-Mg alloys enabled strengthening of the sheaths by an oxide dispersion strengthening (ODS) mechanism. The sheath hardness, tape t ensile strength and the tolerance of the superconducting critical current t o bending and axial strains increased with the concentration of the alloy a ddition. The sheath hardness results revealed evidence of overaging. Excess ive hardening of the sheath, however, lead to the formation of rolling defe cts during the intermediate deformation stage of tape processing. (C) 2000 Elsevier Science Ltd. All rights reserved.