Improved high field performance of Nb-Al powder metallurgy processed superconducting wires

Abstract

Improved overall critical current densities Jc’s were achieved with powder metallurgy processed Nb-A1 which combined reduced powder sizes and increased nominal areal reductions R. Increased Jc values were obtained for a variety of different heat treatments. For a Nb-8 wt. % A1 wire with R=3.4×105 a very short treatment at 1100 °C followed by a 750 °C treatment gave (at 4.2 K)Jc>104 A/cm2 at 19 T; a 900 °C treatment followed by a 750 °C treatment gave Jc=104 A/cm2 at 18 T and, at 2 K, Jc was greater than 104 A/cm2 at 20 T; and a treatment of 800 °C for 8 h gave (at 4.2 K)Jc=104 A/cm2 at 17.5 T.