Observation of Cu nanometre scale clusters formed in Fe₈₅Si₂B₈P₄Cu₁ nanocrystalline soft magnetic alloy by a spherical aberration-corrected TEM/STEM

Abstract

Microstructure of a nanocrystalline soft magnetic Fe₈₅Si₂B₈P₄Cu₁ alloy (NANOMET^®) was investigated by the state of the art spherical aberration-corrected TEM/STEM. Observation by TEM shows that the microstructure of NANOMET^® heat treated at 738 K for 600 s which exhibits the optimum soft magnetic properties has homogeneously distributed bcc-Fe nanocrystallites with the average grain size of 30 nm embedded in an amorphous matrix. Elemental mappings indicate that P is excluded from bcc-Fe grains and enriched outside the grains, which causes to retard the grain growth of bcc-Fe crystallites. The aberration-corrected STEM-EDS analysis with the ultrafine electron probe successfully proved that Cu atoms form nanometre scale clusters inside and/or outside the bcc-Fe nanocrystallites.

Keywords:

• nanocrystalline materials
• TEM/STEM
• microstructure characterization
• Cu cluster

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, under ‘Tohoku Innovative Materials Technology Initiatives for Reconstruction’ project, ‘Ultra-low Core Loss Magnetic Material Technology Area’. A part of this work was supported by the Center for Integrated Nanotechnology Center at Tohoku University and also by Nanotechnology Network.