強化ブロンズ法Nb₃Sn線材の機械的性質と臨界電流の応力/ひずみ特性

抄録

This paper reviews the stress/strain characteristics of some typical highly strengthened bronze-processed practical Nb₃Sn superconducting wires examined in the HFLSM, IMR of Tohoku University up to the magnetic field of 14.5 T at a temperature of 4.2 K. Internal reinforcement of the superconducting composite wires using the materials with high strength and high electrical conductivity such as in situ processed or jelly rolled Cu-Nb microcomposite, Ta, and recently developed Cu-Nb-Ti compound was proved to be promising, although the stability of the wire is decreased to some extent. Although the intrinsic axial tensile strain sensitivity of I_c was not markedly changed, the reinforcements changed not only mechanical properties such as the 0.2% proof stress but also the parameters relevant to the tensile strain characteristics of I_c, the strain corresponding to the I_c peak, ε_m, and reversible strain limit, ε_irr, where permanent damage such as cracking starts to take place in the Nb₃Sn filaments. Furthermore, the transverse compressive stress sensitivity of I_c decreased and the reversible stress limit increased. The effect of parameters on the Cu-Nb composite reinforced bronze-processed Nb₃Sn wires and the strain characteristics are intensively discussed.