Effect of the thickness of aluminum layer on the transport properties of Nb3Al superconducting wires

As reported in preceding papers multifilamentary Nb3Al wires have been successfully developed by using a peculiar fabrication technique. Taking advantage of this technique it has been possible to investigate the effect of the thickness of aluminum layer on the transport properties of the superconducting compound Nb3Al. This thickness plays an important role in the formation of the intermetallic compound with good superconducting properties as an aluminum thickness above a certain value leads to the presence of spurious phases. Experimental results concerning critical current densities, and critical temperatures are given and discussed in terms of their aluminum thickness dependence. As a general feature Jcincreases with decreasing aluminum thickness and this can be accounted for in terms of low temperature (<1000°C) formation mechanisms of the superconducting phase.