Mechanically activated synthesis studied by X-ray diffraction in the Fe-Alsystem

The nanocrystalline phase formation in the Fe-Al binary system induced by a new low temperature process, called mechanically activated self-propagatin g high-temperature synthesis (MASHS)', was investigated by X-ray diffractio n (XRD) analysis. Some parameters of this alternative powder processing met hod which associates a short ball milling duration (leading to nanoscale 3- D polyinterfaces of the elemental components) and a self-propagating high-t emperature synthesis (SHS) reaction, were studied. Their influence on the s olid (liquid) state kinetic paths of phase formation was characterized. The XRD profile line analysis shows that it is possible to synthesize, for exa mple, an FeAl intermetallic compound possessing a nanostructure (40 nm) usi ng the MASHS process. Moreover, an infrared camera revealed that the mechan ical activation step implemented before the SHS process decreases the ignit ion temperature of the exothermic reaction (100 K) between pure Fe and Al, whatever the composition. (C) 1999 Elsevier Science S.A. All rights reserve d.