Tensile Strain and Transverse Compressive Stress Dependence of the Critical Current in Zr Reinforced Ag Sheath Bi(2212) Superconducting Tapes

Abstract

The mechanical properties and the axial tensile strain and transverse compressive stress dependence of the critical current (I_c) in mono-core and 19 core Bi(2212) superconducting tapes with different sheaths were evaluated at a temperature of 4.2K and a magnetic field of 14T. Replacement of the Ag sheath with an Ag-Zr alloy sheath increased the 0.2% proof stress and the tensile strain for I_c degradation onset although I_c decreased markedly. A two-layer sheath with an Ag inner layer and Ag-Zr alloy outer layer improved both the stress-strain and strain characteristics of I_c without remarkable degradation of the I_c. Increasing the number of cores from 1 to 19 degraded the tensile strain vs. I_c characteristics of the tape, although no marked change in the critical current density was observed. The alloying of the sheath also improved the transverse compressive stress vs. I_c characteristics. The effects of Zr alloying of the Ag sheath on the mechanical behavior and stress/strain dependence of the I_c of superconducting composites are briefly discussed with emphasis on texturing of oxide superconductors.