MOSSBAUER-EFFECT EVIDENCE FOR DISORDERING INDUCED BY MECHANICAL ALLOYING IN THE FE-SI SYSTEM

Based on X - ray diffraction (XRD) patterns, differential calorimetry (DSC) investigations, the phase transitions induced by mechanical allo ying (MA) on the Fe rich side of the Fe - Si system has been studied. Starting from a mixture of Fe and Si powders, MA leads to an expansion (up to 27.5 at. % Si) of the A2 crystalline disordered solid solution phase domain. In this composition field, an amorphous phase is also d etected. The expansion of the. disordered A2 phase domain up to 27.5 a t.% Si has been confirmed by Mossbauer spectroscopy investigations. An annealing of the mechanically alloyed powders at 800-degrees-C for 48 hours leads exactly to the thermodynamically stable structures consis tent with the sample stoechiometry. A high coercive force value of 17. 2 kA/m at 1 kHz frequency and 0.15 T magnetic induction was reported f or the 9.5 at. % Si.