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 [(Fe 0.5 Co 0.5 ) 0.72 B 0.192 Si 0.048 Nb 0.04 ] 100− x Y x ( x =0−6) and [(Fe x Co 1− x ) 0.72 B 0.192 Si 0.048 Nb 0.04 ] 96 Y 4 ( 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 [(Fe 0.5 Co 0.5 ) 0.72 B 0.192 Si 0.048 Nb 0.04 ] 100− x Y x ( 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 [(Fe 1− x Co x ) 0.72 B 0.192 Si 0.048 Nb 0.04 ] 96 Y 4 ( 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 ( M s ) increased.