Two-stage-like glass transition and the glass-forming ability of a soft magnetic Fe-based glassy alloy

The structure, thermal stability, and crystalline behavior of (Fe0.9 Co0.1) 67.5 Nb4 Gd3.5 B25 glassy alloy, which exhibits a two-stage-like glass transition phenomenon, were investigated using x-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. The nanoscale metastable (Fe,Co) 23 B6 phase precipitated in the glassy matrix after annealing, while the two-stage-like glass transition disappeared, indicating the two-stage-like glass transition results from the overlap of the endothermic reaction for the glass transition with the exothermic reaction for the formation of the (Fe,Co) 23 B6 phase in the supercooled liquid region. The (Fe0.9 Co0.1) 67.5 Nb4 Gd3.5 B25 glassy alloy exhibits high glass-forming ability, enabling the formation of glassy alloy rods with diameters exceeding 3.0 mm, rather high saturation magnetization of 0.91 T, low coercive force of 2.5 A/m, and high fracture strength of 3870 MPa.