The microstructure and properties of J-R Nb3Al superconducting wires fabricated by diffusion method at an intermediate temperature

The precursor Nb-Al strands were fabricated by the method of Jelly-Roll. The effects of sintering temperature and time on the diffusion degree and superconducting property of the binary Nb-Al system were investigated under isothermal heat treatment at 1100-1500 °C. The results show that the Tc of superconducting wires increased with the heat-treatment temperature rising at the isothermal region. Excessive heat-treatment time led to the decrease of the properties of Nb3Al wires under a certain heat-treatment temperature. The magnetic analysis results showed that the optimal Tc of J-R Nb3Al wires was about 16.8 K at a teat-treatment temperature of 1500 °C for 3 h.