Atomic structure of the Fe/Fe3C interface with the Isaichev orientation in pearlite

The pronounced mechanical property of pearlitic steels highly correlates with the ferrite (bcc-Fe)/cementite (Fe3C) boundaries inside. Unraveling the interface structure at an atomic level is essential for interpreting the material's property. In the present study, using aberration-corrected scanning/transmission electron microscopy combined with density functional theory calculations, we reveal the atomic configuration as well as the electronic structure of the Fe/Fe3C interfaces with the Isaichev orientation in pearlite. The interface with terminating layer Fe–C–Fe in cementite has the lowest energy due to the formation of interfacial Fe–C bonds. Terrace steps which are frequently observed at the interfaces would not break the lattice match between the two phases.