Abstract
The magnetic properties and structure of nanocrystalline Fe-(Nb, Zr)-R-B (R=Pr, Nd) melt-spun alloys with high Fe concentrations were investigated. A nanocrystalline Fe88 Nb2Pr5B5 alloy obtained by annealing an amorphous phase exhibits a coercive force (iHr) of 216 kA/m, remanence (Ir) of 1.23 T and a maximum energy product((BH)max) of 110 kJ/m3, which exceed those for nanocrystalline Fe88Nb2Pr5B5 alloy directly obtained by melt quenching. Fe98-x-y(Nb, Zr)2-RxBy (4≤x≤7, 3≤ ≤y7 (at%)) alloys consist of an amorphous phase in as-quenched state and the amorphous phase gives way to nanoscale bcc-Fe and R2Fel4B1 phases upon annealing at temperatures between 973 and 1073 K. The alloys exhibit high Ir above 1.2 T in a region with high Fe and low R concentrations, and high iHc above 250 kA/m in a region with high R and B concentrations. High (BH)max values are obtained for the high-Ir alloys and exceed 90 kJ/m3 in the region where the Pr and Nd concentrations are below 5 at% for Fe-Nb-R-B systems.
