Effects of yttrium on the formation and magnetic properties of bulk metallic glassy (Fe, Co)-B-Si-Nb alloys

The bulk metallic glassy (BMG) rods of [(Fe0.5Co0.5)0.72B0.192Si0.048Nb0.04]100−xYx (x=0−6) and [(FexCo1−x)0.72B0.192Si0.048Nb0.04]96Y4 (x=0.5−0.8) were prepared by copper mold casting. The structure, thermal stability, and magnetic properties of the samples were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and vibrating sample magnetometer (VSM). Adding 1at% to 6at% of yttrium, the bulk glassy alloy rods of [(Fe0.5Co0.5)0.72B0.192Si0.048Nb0.04]100−xYx (x=0−6) with the diameter of 3 mm were not formed, and the sample with 4at% of yttrium showed less crystalline phase than others. When the Fe/Co atomic ratio was between 5:5 and 7:3, the bulk glassy alloy rods of [(Fe1−xCox)0.72B0.192Si0.048Nb0.04]96Y4 (x=0.5−0.8) with the diameter of 2 mm were fabricated. In the (Fe, Co)-B-Si-Nb-Y BMGs, when the Fe content increased, the thermal stability, the supercooled liquid region, and the glass-forming ability (GFA) decreased, but the saturation magnetization (Ms) increased.