Early stages of phase formation before the ignition peak during mechanically induced self-propagating reactions (MSRs) of titanium and graphite

The mechanism of mechanically induced self-propagating reaction (MSR) of titanium with graphite to produce TiC during reactive ball milling of elemental powders was investigated using high resolution electron microscopy, and Raman and X-ray photoelectron spectroscopies. Prior to the exothermic ignition, off-stoichiometric Ti(1+x)C(1 - x) nuclei are formed by reaction at the interface between the severely deformed Ti particles and graphite milling debris. After ignition, both rapid growth of existing nuclei, and nucleation and growth of additional off-stoichiometric Ti(1+x)C(1 - x) occurs. Local product morphologies after the ignition varied, depending local restrictions on the rate of diffusion of carbon into the TiC as it grows.