The mechanically activated combustion reaction in the Fe–Si system: in situ time-resolved synchrotron investigations

Mechanical high-energy ball milling of Fe+2Si elemental powder mixtures was used to activate self sustaining combustion reaction in the case of iron disilicide synthesis. The reaction path as well as the influence of the microstructural parameters on phase transformation have been investigated in detail. Time-resolved X-ray diffraction (TRXRD) using the fast recording kinetics offered by the synchrotron radiation was coupled to an infrared camera in order to study the internal structure of the combustion wave. The crystallite size and the amount of mechanically induced phases play an important role during the combustion; the reaction path and the end product composition mainly depend on the degree of mechanical activation (i.e. shock power and ball milling duration). β-FeSi2 is formed during a slow diffusion process in the post-combustion zone. The polyinterfaces created at a nanometric scale during the mechanical activation stage are responsible for this peculiar behaviour.