Refinement of the microstructure and enhancement of the magnetic properties in α-Fe/(Nd,Dy)2Fe14B nanocomposite using the two-step annealing technique

Abstract The Nd 8− x Dy x Fe 87.5 B 4.5 ( x = 0 – 1.0 ) nanocomposites have been prepared by melt spinning and subsequent two-step heat treatment technique. The crystallization behaviors, microstructures and magnetic properties of the samples have been investigated. The experimental results show that the crystallization temperature of α -Fe soft phase has no obvious change through Dy addition while the crystallization temperature of 2:14:1 hard phase increases remarkably with increasing Dy content. By adopting a two-step heat treatment technique, a finer and more uniform microstructure can be developed. A dramatic enhancement of remanence J r from 0.84 to 1.1 T, coercivity H cj from 417 to 520 kA/m and energy product ( BH ) m from 76.8 to 110 kJ/m 3 have been obtained in Nd 7 Dy 1 Fe 87.5 B 4.5 (30 vol% α -Fe ) nanocomposite.