Superconducting properties of powder metallurgy processed Nb3Al wires

Powder metallurgy processed Nb3Al wires with low areal reduction ratios of R = 8×10³to 1×10⁴have been investigated on superconducting properties. We have done the optimization of high field Jcvalues for Nb-8 wt.%Al with different areal reduction ratios. Tcwas 17.1 K for the sample with a two stage heat treatment such as 1200 °C for 15 sec followed by 750 °C for 3 days in contrast to the low Tcvalues below 16 K for the samples with a single heat treatment at 800°C. Bc2for a two stage heat treated sample increased about 5 T at 4.2 K in comparison with a single heat treated sample. The measured Bc2values were well fitted to the theoretical curve of the upper critical field. The overall Jcvalues were measured up to 23 T at 4.2 K and Jc= 10⁴A/cm²at 17.5 T was achieved.