Role of disconnections in mobility of the austenite-ferrite interphase boundary in Fe

Austenite (gamma-Fe, face-centered cubic) to ferrite (alpha-Fe, body-centered cubic) phase transformation in steel is of great significance from the point of view of industrial applications. In this work, using classical molecular dynamics simulations, we study the atomistic mechanisms involved during the growth of the ferrite phase embedded in an austenite phase. We find that the disconnections present at the interphase boundary assist in growth of the ferrite phase. Relatively small interface velocities (1.19-4.67 m/s) confirm a phase change via massive transformation mechanism. Boundary mobilities obtained in a temperature range of 1000 to 1400 K show an Arrhenius behavior, with activation energies ranging from 30-40 kJ/mol.