Effects of Cu cluster evolution on soft magnetic properties of Fe83B10C6Cu1 metallic glass in two-step annealing

Not all Cu clusters in Fe-based nanocrystalline alloys can significantly influence the soft magnetic properties. In this study, a density increment of beneficial Cu clusters serving as heterogeneous nucleation sites was obtained by the two-step annealing of the Fe83B10C6Cu1 alloy. The formation and growth of Cu clusters during pre-annealing process were investigated by Mössbauer spectra. An increase of saturation flux density (BS) from 1.76 T to 1.81 T and a distinct decrease of coercivity (HC) from 8.8 A/m to 3.2 A/m were achieved by the two-step annealing. The density increment of beneficial Cu clusters is believed to be the main reason why the two-step annealed Fe83B10C6Cu1 alloy has an increased BS and a decreased HC.