Competition driven nanocrystallization in high Bs and low coreloss Fe-Si-B-P-Cu soft magnetic alloys

Based on experimental results and Johnson-Mehl-Avrami analysis, we have identified the nanocrystallization mechanism of newly developed Fe-rich Fe-Si-B-P-Cu soft magnetic alloys. Competition for growth among a large number of nuclei that are present in as-quenched state (grain density ∼3 × 1021 m−3) and nucleated after annealing above the critical temperature for new nucleation (grain density ∼8 × 1022 m−3) governs the grain size. A model of nanocrystallization is made to predict the magnetic/structural properties.