Micro structure of nanocrystalline Fe-Nb-Pr-B alloys produced by crystallization of amorphous phase

The crystallization behavior and magnetic properties of the melt-spun amorphous Fe88Pr7B5, Fe88Nb2Pr5B5 and Fe86Nb2Pr7B5 alloys were investigated. These alloys have a nanocrystalline structure consisting of bcc-Fe, Fe14Pr2B and remaining amorphous phases and exhibit rather good hard magnetic properties, Hc of 210–270 kA m−1, Ir of 0.93–1.23 T, after annealing for 180 s at 923–1023 K. The Fe88Nb2Pr5B5 alloy exhibits the highest (BH)max of 110 kJ m−3 among the three alloys and has the fine nanocrystalline mixed structure with grain sizes of 10–20 nm. The fine grain size is presumably due to the high thermal stability of the remaining amorphous phase with enriched Nb concentrations.