Synthesis, characterization and amorphization of mechanically alloyed Fe75Si12Ti6B7 and Fe73Si15Ti5B7 powders

In this study, Fe75Si12Ti6B7 and Fe73Si15Ti5B7 (wt. %) alloy powders were synthesized from pure elemental powders by a mechanical alloying (MA) method under argon atmosphere. The evolution in particles morphology, chemical composition, crystalline structure, magnetic and hyperfine proprieties of the mixture elements during MA(0-80 h) was investigated by scanning electron microscopy attached with energy-dispersive spectroscopy, X-ray diffraction (XRD), vibrating sample magnetometer and Mossbauer spectroscopy (MS). The Rietveld refinement of the XRD pattern of the samples milled 5 h shows the formation of several structures: Fe3Si, alpha-Fe nanostructured, Fe2Ti and Fe2B, in addition, that the structure became much more amorphous together with increasing milling time at 80 h. The thermal stability of powders milled was characterized by differential scanning calorimetry (DSC). The annealing of samples milled 80 h shows that the crystallization of the amorphous phases and the activation energy determined by using Kissinger's equation was 462.23 +/- 16.11 kJ mol(-1) and 798.43 +/- 16.12 kJ mol(-1) for the Fe73Si15Ti5B7 and Fe75Si12Ti6B7, respectively. Moreover, the results from XRD and DSC for 80 h of milling were approved by the Mossbauer spectroscopy, and the spectra revealed that the sample Fe73Si15Ti5B7 is fully amorphous, but the sample Fe75Si12Ti6B7 still contains some of Fe with a 2.8% fraction non- detected by XRD. The saturation magnetization (Ms) and coercivity values were of about 151 emu/g, 38.5 G for Fe73Si15Ti5B7 and 171.6 emu/g, 35 G for Fe75Si12Ti6B7, respectively, after 80 h of milling.