LAUSR

Abstract This work investigated the effect of post heat treat time on the structure and superconducting properties of Nb3Al wires prepared around the current condition of getting Tc peak. Properties of Nb3Al wires rapidly heated at much lower current of 76 A were also studied for comparison. M-T results show that prolongation of post-heat treatment time can elevate the Tc value of all Nb3Al wires because of the stoichiometry improvement of Nb3Al phase. The best Jc of post heat treated Nb3Al wires rapidly heated at 76 A and 272 A were obtained after post heat treated for 2 h at 800 °C, compared to that of 10 h for the 276 A samples. The different optimism post heat treatment time to get best Jc of the wires might attribute to the disorder degree difference of the Nb(Al)ss phase fabricated under different rapid heating current. The main pinning mechanism of Nb3Al superconducting wires was grain boundary pinning, as deduced from the fitting of pinning curve. Gradually degrade of Jc of the Nb3Al wire performed at longer heat treatment time was attributed to the coarse of Nb3Al grain that attenuated grain boundary pinning.