STRUCTURAL STUDY OF FE-SI NANOSTRUCTURED MATERIALS

The mechanical alloying (MA) of Fe and Si powder with ball milling con ditions corresponding to an injected shock power of 1.3 TN g(-1), lead s to an expansion of the A2 crystalline disordered solid solution phas e region up to 27.5 at.% Si (the equilibrium value is 9 at.% Si). In t his composition range, an amorphous phase is also detected. In the mec hanically alloyed states, Mossbauer spectroscopy reveals that for a Si content less than 15 at.%, the Fe and Si atoms are randomly distribut ed according to a binomial law in agreement with a bcc structure. For higher Si content, even the X-ray diffraction (XRD) patterns reveal th e bce crystalline structure, the Mossbauer spectra show that the rando m distribution of the Fe and Si atoms in the crystalline lattice can n o longer be maintained. (C) 1997 Elsevier Science S.A.