Role of disconnections in mobility of the austenite-ferrite inter-phase boundary in Fe

Abstract

Austenite ({\gamma}-Fe, face centered cubic (FCC)) to ferrite ({\alpha}-Fe, body centered cubic (BCC)) 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 nucleation and growth of the ferrite phase embedded in an austenite phase. We find that the disconnections present at the inter-phase boundary can act as the nucleation centers for 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.