Fabrication and superconducting properties of Nb_3Al prepared from Nb_2Al and Nb powders

Bulk and tape specimens of Nb_3Al have been fabricated by the powder metallurgy method between Nb_2Al and Nb. The microstructure and superconducting properties on the starting materials and the temperature of a heat treatment have been studied. X-ray diffraction analysis was carried out in order to identify the phases formed by the heat treatment. The A15 single phase, Nb_3Al, were formed at 1100℃ for the bulk specimen prepared from the Nb_2Al/Nb mixed powders. The temperature of a heat treatment formed the A15 single phase prepared from the Nb_2Al/Nb was down 100-200℃ in comparison to that prepared from the Nb/Al mixed powders. The highest critical temperature, Tc, obtained in the bulk specimens prepared from the Nb_2Al/Nb mixed powders is 16.0 K.