Structure, thermodynamic behavior and static magnetic properties of Al addition FeCoNbCuB alloy ribbons

• We fabricated Hitperm amorphous ribbons with melt-spinning quenching method.
• Vertical variation structures were demonstrated on section morphology of ribbons.
• Different crystalline structures observed on the both sides of Al addition Hitperm.
• Al was precipitated from the upper side while Cu precipitated from the wheel side.
• Al addition embrittle ribbons without causing significant changes of static magnetic properties.

The effect of Al addition on the crystallization process and thermodynamic behavior of FeCoNbCuB melt-spinning quenched ribbon alloy is reported. There was no boride phases formed during differential scanning calorimetry observation in Al addition alloy. The section morphology of Al addition as-quenched ribbon showed a vertical variation structure. There were totally different crystalline structures observed on the both sides of Al addition ribbon, with highly crystallized AlCo phase on the upper side and amorphous phase on the wheel side. Al was found to be precipitated from the upper side, and Cu precipitated from the wheel side after vacuum annealing. We also demonstrated that 7.5% aluminum addition would embrittle the alloy ribbon, but without decreasing saturation magnetization and increasing coercivity in terms of static magnetic properties. Only a strong magnetic perpendicular anisotropy was induced in alloy with Al addition after heat treatment.