Interface dislocation trajectory and long-range strain associated with the migration of semicoherent interfaces

Abstract

Semicoherent interfaces are frequently developed during phase transformations within materials like steels and Ti alloys. Gaining insight into dislocation motion and the macroscopic strain during the migration of semicoherent interfaces is vital for understanding phase transformations. This research employs molecular dynamics simulations to explore the migration of diverse semicoherent α/β interfaces in pure Ti, providing new insights into the interface dislocation trajectories during interface migration. The simulation vividly reveals complex dislocation interactions within the interface during its migration, leading to substantial deviations in interface dislocation trajectories from individual dislocation slip planes. In such a complex scenario, pre-existing theories rooted in conventional slip planes often produce inconsistent atom conservation or slip-sequence-dependent results. A novel geometric model has been developed, generating self-consistent descriptions of dislocation shear planes and shear displacement during the migration of general semicoherent interfaces while ensuring atom conservation. It introduces a comprehensive framework for assessing the macroscopic strain engendered by interface migration in varied phase transformation processes, including precipitation and martensite transformation. Validation of this model has been accomplished through simulations, and its generality is verified effectively by encompassing the simpler cases addressed by the pre-existing models.