Glass Formation and Magnetic Properties in the Co and Fe-based Amorphous Alloy with Small Mo or Nb Additions

Abstract

The ferromagnetic metallic glass alloys in the Co-Fe-B-Si-M (M = Mo or Nb) system were investigated. Ingots of [(Co1-xFex)(0.75)B0.2Si0.05](96)Mo-4 (x = 0, 0.2, 0.5, 0.8, 1.0) and [(Co1-xFex)(0.75) B0.2Si0.05](96)Nb-4 (x = 0, 0.2, 0.5, 0.8, 1.0) alloys were cast into about 30 mu m-thick ribbons by using a melt spinning method. As-spun ribbons were identified as being fully amorphous by using X-ray diffraction (XRD). The thermal stability parameters, such as the supercooled liquid region (Delta T-x = T-g - T-x) and the exothermic heat (Delta H-Exo), were measured by using differential scanning calorimetry (DSC). For Co-Fe-B-Si-Mo alloys, Delta T-x and Delta H-Exo were in the range of 41.4 - 81.7 K and 23.40 - 104.21 J/g, and for Co-Fe-B-Si-Nb alloys, Delta T-x and Delta H-Exo were in the range of 60.4 - 88.0 K and 18.45 - 62.05 J/g, respectively. These glassy ribbons also exhibited semi-hard magnetic properties, i.e., a coercive force (H-c) of 67.26 - 100.68 Oe and a saturation magnetization (M-s) of 341.288 - 746.176 emu.cm(3).