FAR FROM EQUILIBRIUM PHASE-TRANSITION INDUCED BY SOLID-STATE REACTIONIN THE FE-SI SYSTEM

In the first part of this paper, this special issue gives us the oppor tunity to overview systems which have been mechanically synthesized. I n the second part, we report on the far from equilibrium phase transit ions induced by mechanical alloying and post-milling isothermal anneal ing in the Fe-Si system. The end-product structures were characterized using X-ray diffraction patterns. Specific attention was paid to two particular phases exhibiting some very interesting physical properties : Fe(Si) (a crystalline phase exhibiting a magnetic effect) in which e xtension of the solubility limit of silicon of the crystalline Fe(Si) phase (up to 16 wt.% silicon) was observed, and beta-FeSi2 (a semicond uctor-type phase exhibiting a direct optical gap and a thermoelectric power) crystalline phases.