The Processing of J-R Nb3Al Superconducting Wires through the Diffusion Method at Low Temperature

Eighteen-core Nb-Al strands have been fabricated by the jelly-roll (J-R) method followed by the thermal diffusion method. The effects of sintering temperature and time on the extent of diffusion and the superconducting properties of the binary Nb-Al system were investigated, with thermal diffusion taking place under isothermal heat treatment at 750 °C-1000 °C. Results showed that the J-R Nb3Al superconducting phase could be obtained by the low-temperature diffusion method, and a higher critical temperature (T
_c
) was obtained with sintering between 800 °C and 900 °C. On optimizing the sintering temperature and time, it was indicated that the sintering temperature had more significant effects on the superconducting properties than the sintering time. The magnetic analysis showed that the J-R Nb3Al samples were obtained with an optimal T
_c
of about 15.1 K by the low-temperature diffusion method with sintering for 24 h under 900 °C.