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

The Nd8−xDyxFe87.5B4.5 (x=0–1.0x=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 Jr from 0.84 to 1.1 T, coercivity Hcj from 417 to 520 kA/m and energy product (BH)m from 76.8 to 110 kJ/m3 have been obtained in Nd7Dy1Fe87.5B4.5 (30 vol%α-Fe ) nanocomposite.