Synthesis and characterization of Co-Fe-based amorphous ribbons with small Nb additions

The ferromagnetic metallic glass alloys in the Co-Fe-B-Si-Nb system were investigated. Such glassy alloys exhibit high glass-forming ability (GFA), as well as good mechanical and magnetic properties. Based on those results, [(Co0.5Fe0.5)0.75B0.2Si0.05]100-xNbx (x = 5, 6, 7, 8 at.%) were chosen for this investigation with increasing Nb contents. Amorphous ribbons with [(Co0.5-Fe0.5)0.75B0.2Si0.05]100-xNbx (x = 5, 6, 7, 8 at.%) were obtained by single-roller melt spinning. As-spun ribbons were identified as fully amorphous by using X-ray diffraction (XRD). The thermal stability parameters, such as the supercooled liquid region (ΔTx = Tg - Tx), were measured by using differential scanning calorimetry (DSC). The mechanical properties of the Co-Fe-B-Si-Nb system were measured by using a nano-indentation test. Co-Fe-B-Si-Nb glassy ribbons also exhibited good soft magnetic properties, a low coercive force (Hc) and a high saturation magnetization (Ms). We report here that a small amount of Nb addition (microalloying) can enhance the thermal stability of the alloy without deteriorating its soft magnetic properties.