Crystallization behavior and high temperature magnetic phase transitions of Nb-substituted FeCoSiBCu nanocomposites

The effect of Nb substitution on the nanocrystallization process and high temperature magnetic properties of FeCoSiBCu nanocomposites is reported. Magnetization changes accompany the primary crystallization of α-Fe(Co) nanocrystals and the secondary crystallization of (FeCo)₂₃B₆and (FeCo)₂B phases. With increasing the Nb fraction in the alloys, the diffusion barrier to growth of α-Fe(Co) nanocrystals increases, resulting in an increase of thermal stability and a delay of Fe(Co) dissolution required for (FeCo)₂₃B₆ phase formation. The transmission electron microscopy images reveal finer grains with increasing Nb content.