Stress/strain dependence of critical current in Nb 3Sn superconducting wires stabilized with Cu–Nb microcomposites – effect of Nb content

Abstract

The effects of niobium content in the Cu–Nb microcomposite on the mechanical property and the axial tensile or transverse compressive stress/strain characteristics of the critical current I c in a bronze processed Nb 3Sn multifilament superconducting wire with the Cu–Nb microcomposite were evaluated at a temperature of 4.2 K in a magnetic field of 14 T. An increase in niobium content increases the 0.2% proof stress as well as both tensile and transverse compressive stress tolerance of I c of the wire. High yield stress value of the Cu–Nb microcomposite increases the strain at peak I c, ε m, as well as the reversible strain limit of I c, ε irr in the wire as compared to those in the Cu stabilized wire. An increase in niobium content in Cu–Nb microcomposite, however, decreases them due to decrease in the coefficient of thermal expansion.