Nb3Sn diffusion layers an experimental study of their superconducting properties as related to the Zr content and cold-work amount of the Nb base ribbons

In the present work the results of a systematic experimental analysis on current-carrying properties of superconducting Nb3Sn diffusion layers are presented. The influence of the Zr content (up to a maximum of 7%) and of cold-work of Nb base ribbons on the critical current (at 64kG) is discussed. It is shown that, while the presence of zirconium leads to a higher critical current density, at the same time it affects the diffusion coefficients, so that the thickness of diffusion layer is decrease. Results concerning pinning mechanism are also presented and discussed