Soft Magnetic Properties of Ring-Shaped Fe-Co-B-Si-Nb Bulk Metallic Glasses

The reduction of the Nb content in the $(Fe_0.75B_0.20Si_0.05)₉₆Nb_4$ bulk metallic glass (BMG) has been studied. The glass-forming ability (GFA) is reduced by decreasing the Nb content, but it can be enhanced by replacing partially Fe by Co. Furthermore, the saturation magnetization of the $(Fe_0.8Co_0.2)₇₆B₁₈Si_3Nb_3$ BMG is 1.35 T, being with 13% larger than that of the base alloy $(Fe_0.75B_0.20Si_0.05)₉₆Nb_4$. $(Fe_0.8Co_0.2)₇₆B₁₈Si_3Nb_3$ BMG exhibits slightly larger $B₈₀₀$ (the magnetic flux density at 800 A/m) and smaller core losses (20%-30%) compared with the commercial Fe-6.5 mass% Si steel.