Effect of third element additions on the properties of bronze processed Nb3Sn

The effect of additions of Al, Sn or Zr to the Nb core, together with additions of Al, Ga or In to the bronze matrix, on the rate of layer growths and critical current density of Nb3Sn formed by the bronze process has been studied. Small amounts of Al (1.25 wt%) in the core, separately or together with a few percent of Al in the matrix, replacing some of the Sn, increase the rate of growth of the Nb3Sn layer. Larger quantities of Al (>2 wt%), of Ga or of In in the matrix decrease the rate of layer growth by more than can be accounted for by the concomitant reduction in Sn content. Low field critical current density is more dependent upon layer thickness and growth rate than upon composition. High field critical current density is directly related to the upper critical field.