Magnetic properties of B-rich nanocomposite α-(Fe,Co)/(NdPr)2Fe14B alloys

We report and discuss the results of a study of the structures and magnetic properties of B-rich (10 at%) nanocomposite alloys, based on the formula (Nd0.75Pr0.25)y(Fe0.9Co0.1)90−y−xNbxB10 (y=8, 10; x=0, 2,4) and processed by devitrification of melt-spun amorphous precursors. Considerable enhancement of the intrinsic coercivity, together with good to excellent remanence and energy density values were observed for the composition with y=10, x=2, (1042 kA/m, 0.88 T and 123 kJ/m3, respectively). The intrinsic coercivity and remanence enhancements are ascribed to the grain-refining effects of Nb, particularly with respect to the soft-magnetic phases, and thus to more complete exchange coupling of the soft grains to the hard-phase grains than for the Nb-free alloy.