Core-shell structure and stability of nanocrystalline precipitates in Fe83.3Si4B8P4Cu0.7 soft magnetic amorphous alloy

摘要

The core-shell nanostructure of alpha-Fe precipitates was investigated in a recently developed high-performance Fe83.3Si4B8P4Cu0.7 nanocrystalline soft magnetic alloy utilizing small-angle neutron scattering (SANS) and atom probe tomography (APT). SANS measurements under a saturating magnetic field provided evidence of coreshell structures at the nanoscale. Moreover, the core-shell structure was directly visualized from APT analysis, where P-enriched shells were found around Fe-enriched cores due to the large negative heat of mixing between Fe and P elements and the slow diffusion of P atoms. The core-shell nanostructures induced by nanoscale partitioning are effective in stabilizing the residual amorphous matrix and suppressing the crystal growth. Our findings provide insight into the microstructure of Fe-based amorphous alloys and have direct implications in alloy design for the improvement of the soft magnetic properties.

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