Magnetic and structural properties and crystallization behavior of Si-rich FINEMET materials

Abstract The magnetic and structural properties of an Si-rich grade FINEMET alloy with a composition of Fe 73.5 Si 16.1 B 6.4 Nb 2.9 Cu 1.1 in at% [Fe 82.7 Si 9.1 B 1.4 Nb 5.4 Cu 1.4 (wt%)] were investigated after primary and secondary crystallization of ribbon samples. Optimally annealed ribbons exhibited a homogeneous microstructure composed of ∼7 nm DO 3 nanocrystals surrounded by the retained amorphous phase. This is similar to the base FINEMET. Also, a chemical partitioning model, especially of Si, on slowly heated ribbons above the secondary crystallization temperature (∼700°C), is presented herein in conjunction with the reaction products and the magnetic transitions. A self-consistent magnetization analysis is presented which for the first time in FINEMET materials correlates a macroscopic approach from the sample magnetization (using experimentally determined microstructural data such as volume fractions of magnetic phases) with an atomistic approach such as nearest-neighbor calculations and the atomic magnetic dipole moments. The estimated magnetic moment exerted by one Fe atom in the as-spun sample is ∼1.67 μ B on average, while that in a unit cell of the DO 3 phase crystallized from the amorphous is estimated as ∼1.85 μ B per Fe atom (∼24.2 μ B per a unit cell of the DO 3 phase).