Microstructure and some magnetic properties of annealed Vitrovac® 6025X amorphous ribbons

Microstructure, initial magnetic permeability and coercivity of amorphous Vitrovac® 6025X ribbons isothermally annealed in the temperature range 473–813 K are reported. Superior magnetic properties are attained after annealing at 693 K. Such behavior is attributed to the growth of domains of medium-range order existing in the as-quenched state. This effect is also responsible for the local magnetic anisotropy with the easy axis perpendicular to the ribbon edge. Nanocrystallization starts at 773 K resulting in hexagonal Co grains with a diameter of about 5 nm and is accompanied by magnetic hardening. Further increase of annealing temperature leads to further gradual magnetic hardening due to grain growth.