Influence of Nb doping on magnetic properties of nanocrystalline Ndy Fe86−x−y B14 Nbx (y =7, 8; x=0, 2, 4) alloys

BILOVOL, V.; L. G. PAMPILLO; FERRARI, S.; DEREWNICKA, D.; F. D. SACCONE

Buenos Aires

Workshop; Latin American Workshop on Magnetism and Magnetic Materials; 2013

Nanocomposite permanent magnets with a low Nd content have been attracted the interest of researchers and industryduring the last years, due to their enhanced magnetic properties (such as high coercive fields and energy product, (BH)M AXand corrosion resistance. The use of refractory metals, i. e. Ti, Nb and Mo, helps to control the nanosized grains during themelt-spinning production of this kind of magnets. Rapidly quenched ribbons of nominal composition Ndy Fe(86−y−x) B14 Nbx(y =7, 8; x=0, 2, 4) were annealed at 973 K for ten minutes. Structural characterization of the ribbons after annealing wasmade by X-Ray diffraction and M ̈βbauer spectroscopy. They revealed that for the higher Nb and Nd contents, the fractionoof the hard magnetic phase Nd2 Fe14 B precipitates as the majority one. However, this is not the situation for the ternariesand for the Nd7 Fe77 B14 Nb2 alloys. The magnetic properties of the as-quenched and annealed ribbons were measured usinga vibrating sample magnetometer. As it is expected, the hardening of the alloys after annealing was notable for those alloyswith a higher content of the Nd2 Fe14 B phase. Likewise, the addition of Nb inhibited the precipitation of the bcc-Fe phase,independently of the Nd content. For the complete set of samples studied in this work, we found that the sample withcomposition Nd8 Fe74 B14 Nb4 exhibits the highest coercive field 573 kA/m and a (BH)M AX = 436.5 kJ/m3 .