Soft magnetic Co-based Co–Y–Nb–B bulk metallic glasses (BMGs) without Fe have been developed by micro-alloying Y and Nb into a Co₇₅B₂₅ alloy. First, addition of 3–4 at.% Y promotes the occurrence of glass transition and increases the supercooled liquid stability and magnetic softness. Co_71.5Y_3.5B₂₅ metallic glass possesses a large supercooled liquid region (ΔT_x) of 33 K and low coercivity (H_c) of 1.5 A/m. Subsequent alloying 2–4 at.% Nb into Co_71.5Y_3.5B₂₅ alloy further enlarges ΔT_x to 50 K, lowers H_c to 0.9 A/m, and enables the formation of BMGs with a critical sample diameter up to 2.0 mm. The alloying Nb causes the formation of complex (Co, Nb, Y)₂₃B₆ competing phase during crystallization and widens the melt undercooling during solidification, which improves the supercooled liquid stability and glass-forming ability, respectively. Co–Y–Nb–B BMGs also exhibit good soft magnetic and mechanical properties, i.e., low H_c of 0.9–1.2 A/m, relatively high saturation magnetic flux density of 0.36–0.57 T, high yielding strength of 3877–3930 MPa with plastic strain of 0.2%–0.3%, and high Vickers hardness of 1156–1201. The developed soft magnetic Co-based BMGs are promising for applications as structural and functional materials.

通过将Y和Nb微合金化成Co ₇₅ B ₂₅合金，已经开发出了不含Fe的软磁性Co基Co-Y-Nb-B大块金属玻璃（BMG）。首先，添加3–4 at。％Y会促进玻璃化转变的发生，并增加过冷液体的稳定性和磁软度。Co _71.5 Y _3.5 B ₂₅金属玻璃具有33 K的大过冷液体区域（ΔT _x）和1.5 A / m的低矫顽力（H _c）。随后将2–4 at。％Nb合金到Co _71.5 Y _3.5 B ₂₅合金中，进一步将ΔT _x扩大到50 K，降低H_c至0.9 A / m，并能够形成临界样品直径最大为2.0 mm的BMG。合金化的Nb导致在结晶过程中形成络合物（Co，Nb，Y）₂₃ B ₆竞争相，并扩大了凝固过程中的熔体过冷度，分别改善了过冷的液体稳定性和玻璃形成能力。Co–Y–Nb–B BMG还具有良好的软磁和机械性能，即H _c低至0.9–1.2 A / m，相对高的饱和磁通密度为0.36–0.57 T，高屈服强度为3877–3930 MPa塑性应变为0.2％–0.3％，维氏硬度为1156–1201。研发的软磁钴基BMG有望作为结构和功能材料应用。