Nanocrystallization and soft magnetic properties of Fe23M6 (M: C or B) phase in Fe-based bulk metallic glass

•Homogeneously dispersed medium range ordering (MRO) and extremely fine nanocrystals in amorphous matrix.•Enhancement of saturation magnetization (Ms) and soft magnetic properties with nano-scale Fe23M6 structure.•Soft magnetic nanocrystalline alloys with amorphous precursor having high glass forming ability (GFA).

Nanocrystallization effect of primary Fe23M6-type phase (M: C or B) on magnetic properties of Fe-based bulk metallic glass (BMG) has been investigated. Under controlled microstructural modification with Fe23M6-type phase, the soft magnetic properties of Fe76.5C6Si3.3B5.5P8.7 (at.%) BMG were significantly improved: saturation magnetization (Ms) and initial permeability (μi) of the alloy were dramatically enhanced from 1.35 T and 3500 to 1.57 T and 9890, respectively. The present study about introducing medium range atomic orderings and nanocrystallization of Fe23M6-type structure in amorphous matrix suggests a strategy to enhance the soft magnetic properties of ferromagnetic BMGs having the primary crystallized phase Fe23M6. This result provides useful insight to develop soft magnetic nanocrystalline materials, stating from BMG precursor with large glass forming ability.