Magnetic Properties of B-Rich Nano-Composite REyTM 90-y-xNbxB10 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 REyTM90-y-x NbxB10 (RE=Nd, Nd+Pr, TM=Fe, Fe+Co; y=8,10,12, 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 Co-containing compositions with y =10 and x =2,4. 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.