Effect of milling time and investigation of thermodynamic analysis on amorphous phase formation in Fe-C-Ta alloy prepared by mechanical alloying

Nowadays, soft magnetic materials such as nanocrystalline and amorphous alloys with unique physical, mechanical and magnetic properties have attracted much attention. Recently, Fe-based amorphous alloys have been greatly developed due to their excellent magnetic properties and relatively low cost. In this study, effect of milling time on microstructure of Fe-C-Ta alloy prepared by mechanical alloying was studied. Besides, the possibility of glass formation was investigated according to thermodynamic calculations, performed based on advanced Miedema model. The X-ray diffraction (XRD) results proposed that the fraction of amorphous phase enhances by increasing milling time up to 70 h, and then it becomes unchanged up to 90 h milling. Moreover, the differential scanning calorimetry (DSC) results confirmed the formation of amorphous phase with a crystallization temperature of 678 K, after 70 h of milling. The thermodynamic calculations with respect to the advanced Miedema model revealed that the Gibbs free energy changes for glass formation (-42.35 kJ/mol) are larger than those of solid-solution formation (-28.5 kJ/mol) and consequently, the amorphous phase has a larger tendency to form after milling.