Effect of Co addition on crystallization and magnetic properties of FeSiBPCu alloy

The effects of Co addition on the microstructure, crystallization processes and soft magnetic properties of (Fe_1?xCo_x)₈₃Si₄B₈P₄Cu₁ (x=0.35, 0.5, 0.65) alloys were investigated. The experimental results demonstrated that the addition of Co decreased the thermal stability against crystallization of the amorphous phase, and thus improved the heat treatment temperature of this alloy. FeCoSiBPCu nanocrystalline alloys with a dispersed α′-FeCo phase were obtained by appropriately annealing the as-quenched ribbons at 763 K for 10 min. The α′-FeCo with grains size ranging from 9 to 28 nm was identified in primary crystallization. The coercivity (H_c) markedly increased with increasing x and exhibited a minimum value at x=0.35, while the saturation magnetic flux density (B_s) shows a slight decrease. The (Fe_0.65Co_0.35)₈₃Si₄B₈P₄Cu₁ nanocrystalline alloy exhibited a high saturation magnetic flux density B_s of 1.68 T, a low coercivity, H_c of 5.4 A/m and a high effective permeability µ_e of 29,000 at 1 kHz.