Alloys of Nb73Al12Si14.5B0.5were rapidly quenched using the melt spinning technique to form fine amorphous ribbons. These were then annealed intoA‐15 tapes with a variety of grain sizes. The smaller the grain was the more flexible the tape and the higher the critical current densityJc. The best results were obtained for a tape with a grain size of 15 nm; it could be bent to a diameter of 1 mm without breaking and it had aJcof 3.3×1010A/m2at a magnetic field of 20 T.