Effects of the IVa element addition on the composite-processed superconducting Nb3Sn

The effect of the IVa element addition to the niobium core and that of gallium addition to the matrix on the composition, growth rate and superconducting properties of the composite-processed Nb₃Sn have been studied. The IVa elements added to the niobium core enhance the growth rate of Nb₃Sn, and prevent the grain coarsening of Nb₃Sn. A much larger amount of titanium is incorporated into Nb₃Sn than zirconium or hafnium. T_c shows a slight maximum against the IVa element concentration in the niobium core. J_c at high magnetic fields is more significantly increased by titanium addition than zirconium or hafnium additions. The gallium substitution for tin in the matrix is effective for increasing T_c and J_c in high fields, except for the specimen with Nb-Ti alloy core. The simultaneous addition of hafnium and gallium is most effective for the enhancement of J_c in high fields.