Metallurgy and superconductivity in Nb-Al

Abstract
The formation of the Nb3Al A15 phase under equilibrium conditions is studied on bulk, homogenized samples. Due to compositional effects, Tcof samples annealed during long periods at temperatures below 900°C is found to be close to 12 K. It follows that the high Tcvalues (15-16 K) observed on multifilamentary Nb3Al wires reacted at these temperatures cannot be interpreted on the basis of the equilibrium phase diagram.