Enhancement of Critical Current Density of Nb3Al Superconductors by B Doping

Boron (B)‐doped Nb 3 Al superconductors are prepared by mechanical alloying and subsequent sintering process in this work. Then, the critical current density ( J c ) of Nb 3 Al with different amounts of B doping is studied. In the results, it is shown that J c performance of Nb 3 Al is improved obviously after B doping. The best J c value obtained in this work is 2.2 × 10 4 A cm −2 (4.2 K, 5 T) for Nb 3 (Al 0.9 B 0.1 ) sample. Furthermore, the mechanism of enhanced J c performance for Nb 3 (Al 0.9 B 0.1 ) sample is comprehensively explored. It is found that B doping can significantly enhance the grain connectivity of Nb 3 Al superconductor, and the active cross‐sectional area fraction values increase from 0.11 for the undoped sample to 0.34 for Nb 3 (Al 0.9 B 0.1 ) 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 Nb 3 (Al 0.9 B 0.1 ).