Abstract: The correlation between the stress relief and magnetism improvement during the annealing process, and the influence of annealing embrittlement on the magnetic application of Fe-based amorphous alloys are analyzed. After isochronal annealing, the saturation induction and maximum permeability of as-quenched amorphous Fe79B16Si5 alloy increase by 72 % and 22 times, respectively, concurrently with the reduction of coercive force and power loss by 86 % and 83 %, respectively. These changes are primarily due to the effective removal of the stress - induced magnetic anisotropy resulted from the complete relaxation of internal stresses during annealing. However, because of the ductile - brittle transition which occours well below the temperatures for magnetism improvement, amorphous alloy strips be-come very brittle after magnetism improvement annealing and cannot be deformed any more. As a result, this will obviously affect the application of Fe - based amorphous alloys: Annealing by pulse current heating can effectively improve the magnetic properties of as – quenched Fe - based amorphous alloys with no or few loss of ductility. So it is hopeful to become a practical method for obtaining optimum ductility and magnetic properties of amorphous Fe-based alloys.

Key words: Amorphous alloy, Embrittle ment, Magnetism Annealing, Stress relief