Atomic-Scale Structural Evolution upon Crystallite Nucleation and Growth in Amorphous Fe78B13Si9

The structural evolution upon nucleation and growth of nanocrystals was investigated for Fe78B13Si9 alloy. Upon the onset of α-Fe nanocrystallization, free volumes dominantly surrounded by Fe atoms are developed in the intergranular amorphous phase. Along with the growth of Fe-based nanocrystallites, free volumes in the intergranular amorphous phase enlarge and Fe atoms in the surroundings of the free volumes get partially replaced by B and Si. The results suggest that nanocrystallization is associated with a local structural relaxation in the metastable intergranular amorphous phase.