Influence of the as-cast state on the crystallization process and magnetic properties for FeSiBCuNb wires

The authors have recently reported studies of the influence of crystallization to a nanophase structure on the magnetic properties of FeSiBCuNb wires. As in the case of ribbons of similar composition, magnetic softening was observed after heating at about 550 C when α-Fe(Si) nanocrystallites are segregated. The aim of this work is to present results concerning the influence of the as-cast state on the evolution of structure and magnetic and magnetoelastic properties with subsequent thermal treatments. Magnetic and structural studies reveal different as-cast states ranging from completely amorphous to partially crystalline states depending on melt temperature. The most significant observation is that the same degree of magnetic softening (i.e. coercivity, linear magnetostriction...), as previously reported after heating from initially amorphous sample at 550 C, is observed in all samples irrespective of the as-cast state. Nevertheless, in the intermediate states (annealing below 550 C) a different evolution to the nanophase structure is observed for each case