Structural Heterogeneity of the Melt-spun (Fe, Co)-Si-B-P-Cu Alloy with Excellent Soft Magnetic Properties

Abstract A structural heterogeneity of a newly developed soft magnetic Fe 81.2 Co 4 Si 0.5 B9.5P4Cu0.8 melt-spun alloy has been studied by transmission electron microscopy (TEM) and electron diffraction. Hollow-cone dark-field TEM imaging revealed that the density of coherent scattering regions in the as-quenched Fe 81.2 Co 4 Si 0.5 B 9.5 P 4 Cu 0.8 alloy is as high as that in the Fe 85.2 Si 2 B 8 P 4 Cu 0.8 hetero-amorphous alloy (NANOMET ® ). According to the aberration-corrected high-resolution TEM, crystalline atomic clusters, typically of ∼1 nm in diameter, are densely distributed in an amorphous matrix of Fe 81.2 Co 4 Si 0.5 B 9.5 P 4 Cu 0.8 alloy, while nanobeam electron diffraction detected weak Bragg reflections from Fe clusters with the body centered cubic structure. These results unambiguously reveal structural heterogeneity of the as-quenched Fe 81.2 Co 4 Si 0.5 B 9.5 P 4 Cu 0.8 alloy, which is similar to that observed in the NANOMET ® .