Magnetic properties of as-quenched Fe–Cu–Mo–Si–B nanocrystalline ribbons

Nanocrystalline ribbons Fe–Cu–Mo–Si–B with excellent soft magnetic properties can be fabricated by melt-spinning technique without additional annealing processes. For as-quenched nanocrystalline ribbon Fe71.5Cu3Mo3Si13.5B9 (numbers indicate at.%) with a grain size of D = 9 nm for α-Fe(Si), values of the effective permeability μe (at 1 kHz and 0.8 A/m) = 5.43 × 104, saturation magnetostriction λs = 1 × 10−6, saturation magnetic induction Bs = 1.25 T can be obtained. Giant magnetoimpedance was observed in as-quenched nanocrystalline ribbons of Fe–Cu–Mo–Si–B. The maximum magnetoimpedance ΔZ/Z0 occurs at the sample x = 3, since it has the largest permeability-variation under field, the largest permeability and smallest saturation magnetostriction among as-quenched ribbons Fe74.5−xCuxMo3Si13.5B9. The sample with an optimal Cu content (x = 3) may have the maximum effective number density of Cu clusters that can serve as heterogeneous nucleation sites for α-FeSi grains.