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

The magnetic and structural properties of an Si-rich grade FINEMET alloy With a composition of Fe73.5Si16.1B6.4Nb2.9Cu1.1 in at% [Fe82.7Si9.1B1.4Nb5.4Cu1.4 (wt%)] were investigated after primary and secondary crystallization of ribbon samples. Optimally annealed ribbons exhibited a homogeneous microstructure composed of similar to7 nm DO3 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 (similar to700 degreesC), 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 similar to1.67 mu(B) on average, while that in a unit cell of the DO3 phase crystallized from the amorphous is estimated as similar to1.85 mu(B) per Fe atom (similar to24.2 mu(B) per a unit cell of the DO3 phase). (C) 2003 Elsevier B.V. All rights reserved.