Effect of Co Content on Properties of Fe-B-Nb-Y Bulk Metallic Glasses

Fe-based bulk metallic glasses have limited applications owing to the difficulty in simultaneously realizing both an excellent glass-forming ability and soft magnetic properties. Therefore, in this study, (Fe_1 − xCo_x)₆₉B₂₃Nb₄Y₄ (x = 0−0.5) bulk metallic glass was selected to study the effect of the Co content on its thermodynamic properties, soft magnetic properties, and mechanical properties. The results show that when the Co content was 0.05 at%, the supercooled liquid region ΔT_x of (Fe_1 − xCo_x)₆₉B₂₃Nb₄Y₄ (x = 0−0.5) bulk metallic glass reached 117 K, the γ parameter reached 0.426, and the glass-forming ability reached the maximum extent (corresponding to a critical diameter of 8 mm). The addition of Co also improved the overall soft magnetic properties of this glass system. The saturation magnetic induction intensity increased from 0.85  to 0.98 T, and then decreased slightly to 0.96 T. The coercivity increased slightly but was less than 2.8 A/m. The compressive fracture strength of the system increased from 2900 MPa to more than 3100 MPa, and reached a maximum of 3691 MPa when the Co content is 0.15 at%; however, almost no plastic deformation was observed.