Enhancement of Critical Current Density of Nb3Al Superconductors by B Doping

Abstract

Boron (B)‐doped Nb3Al superconductors are prepared by mechanical alloying and subsequent sintering process in this work. Then, the critical current density (Jc) of Nb3Al with different amounts of B doping is studied. In the results, it is shown that Jc performance of Nb3Al is improved obviously after B doping. The best Jc value obtained in this work is 2.2 × 104 A cm−2 (4.2 K, 5 T) for Nb3(Al0.9B0.1) sample. Furthermore, the mechanism of enhanced Jc performance for Nb3(Al0.9B0.1) sample is comprehensively explored. It is found that B doping can significantly enhance the grain connectivity of Nb3Al superconductor, and the active cross‐sectional area fraction values increase from 0.11 for the undoped sample to 0.34 for Nb3(Al0.9B0.1) sample. In addition, the lattice distortion caused by the interstitially dissolved B may also serve as flux pinning centers, which strengthens the flux pinning force of Nb3(Al0.9B0.1).