Role of Minor Ta Substitution on Thermal Behavior and Soft Magnetic Properties of Co-Fe-Mo-Si-B Metallic Glass Ribbon

Cobalt-based metallic glasses have sparked intensive attention because of their extraordinary properties. In this work, a series of Co₆₆Fe₄Mo_2-TaSi₁₆B₁₂ (x = 0, 0.5, 1.0, 1.5, 2.0) metallic glass ribbons were systematically designed to investigate the influence of the minor Ta substitution for Mo on the thermal behavior and magnetic performance. The results reveal that the width of the supercooled liquid region initially increases with Ta content, reaching 98 K at x = 1.0, and subsequently decreases with further Ta addition. It indicates that the Co₆₆Fe₄Mo_1.0Ta_1.0Si₁₆B₁₂ alloy has the optimal glass-forming ability. Moreover, the crystallization onset temperature and crystallization peak temperature of all as-quenched ribbons were improved with the Ta content x increasing to 2.0, which is due to the higher melting temperature of the element Ta (3290 K). In addition, these ribbons exhibit outstanding soft magnetic properties, including ultralow coercivity (H_c < 1.1 A/m) and moderate saturation magnetization, which indicates that these ribbons are suitable for magnetic shielding. These results offer valuable insights into the design of soft magnetic metallic glass.