FAR FROM EQUILIBRIUM CRYSTALLINE TO AMORPHOUS PHASE-TRANSITION INDUCED BY MECHANICAL ALLOYING IN THE FE-SI SYSTEM

Starting from a mixture of Fe and Si powders, the mechanical alloying leads to an expansion (up to 16%Si - in wt) of the A2 phase domain [1, 8]. In this composition field, we report on the influence of the stru ctural state and the grain size on the coercive force and the microhar dness. By Vicker's microhardness measurements, the expansion of the A2 phase domain up to 15 wt%-Si is confirmed. The starting of the orderi ng reaction A2 to B2 phase is above 16wt%-Si and the existence of the D03 phase is at 17 wt%-Si. A high coercive force for the 5 wt% sample has been reported.