Enhancement of self-sustaining reaction by mechanical activation: case of an Fe-Si system

Mechanical high energy ball milling of an Fe + 2Si elemental powders mixtur e was used to activate a self sustaining combustion reaction or so-called s elf-propagating high-temperature synthesis (SHS) to form iron disilicide, a reaction for which the thermodynamic criterion is not favorable. A complet e characterization of the milled powders before reaction was performed with energy dispersive X-ray spectrometry, specific surface measurements and X- ray diffraction profile analysis. Thermal and structural information descri bing the combustion front initiated by heating up a sample to 400 degrees C in a Fe-Si system is communicated. In order to isolate the phases involved in the gasless reaction, a time-resolved X-ray diffraction experiment was designed to study in situ the formation of silicide phases (FeSi and beta-F eSi2) produced by the new process called MASHS (mechanically activated self -propagating high-temperature synthesis). (C) 1999 Elsevier Science S.A. Al l rights reserved.