Improvements in high field properties of RHQT-processed Nb3Al wire

Long Nb₃Al multifilamentary wires with high J_c in high fields can be produced through a rapid heating, quenching and transforming (RHQT) process. Recently three different processes (Cu-added RHQ, DRHQ, and TRUQ) were proposed in order to improve the superconducting properties of the RHQT-processed Nb₃Al wires. In this paper we make a comparison of the three processes. Although the best values of T_c = 18.5 K and B_c2 (4.2 K) = 29.5 T were obtained for the DRHQ-processed Nb₃Al wire, the best values of J_c in magnetic inductions below 23 T were obtained for the Cu-added RHQ-processed Nb₃Al wire. On the other hand, the stabilization with Cu-coating is relatively easy for the TRUQ-processed Nb₃Al.