  Using classical molecular dynamics simulations, we study austenite to ferrite
phase transformation in iron, focusing on the role of interface morphology. We
compare two different morphologies; a \textit{flat} interface in which the two
phases are joined according to Nishiyama-Wasserman orientation relationship vs.
a \textit{ledged} one, having steps similar to the vicinal surface. We identify
the atomic displacements along a misfit dislocation network at the interface
leading to the phase transformation. In case of \textit{ledged} interface,
stacking faults are nucleated at the steps, which hinder the interface motion,
leading to a lower mobility of the inter-phase boundary, than that of flat
interface. Interestingly, we also find the temperature dependence of the
interface mobility to show opposite trends in case of \textit{flat} vs.
\textit{ledged} boundary. We believe that our study is going to present a
unified and comprehensive view of martensitic transformation in iron with
different interface morphology, which is lacking at present, as \textit{flat}
and \textit{ledged} interfaces are treated separately in the existing
literature.
