On the formation of pure and Pt-doped iron silicides using ball milling

The sequence of phase formations for elemental powders of stoichiometric Fe Si2 and Fe1-xPtxSi2 (0.03 less than or equal to x less than or equal to 0.5 0) mixtures prepared by mechanical alloying at room temperature in an Ar at mosphere in a horizontal mill is presented. Sample evolution was followed b y means of Mossbauer spectroscopy and x-ray diffraction. After the milling, the results indicate the formation of different disordered iron silicides, depending on milling time. The kinetics of iron silicide formation was als o studied; a diffusion-controlled process with decreasing nucleation rate w as found. In the case of Pt-doped samples, the segregation of Pt silicides was observed even for the smallest concentration, and no noticeable incorpo ration of Pt into the beta -FeSi2 lattice could be inferred. Samples were a lso subjected to annealing at 1123 K for 4 h to produce ordering in the str uctures.