Interfaces can significantly influence a material’s strength, ductility, conductivity, and corrosion resistance. Understanding metal interfaces is fundamental for predicting and controlling the mechanical, electrical, thermal, and chemical properties of materials. Despite extensive theoretical and experimental research on interfaces, some questions remain unresolved. For instance, the detailed structure and free energy of semicoherent interfaces in metals have been seldom studied. Experimentally, calculating the energy of a specific interface is challenging. In simulations, the lack of accurate interatomic potentials has limited studies on interface free energy. Additionally, the kinetic properties of heterophase interfaces are rarely explored.

This research aims to elucidate the structure, thermodynamics, and kinetics of interfaces in metals. Atomistic simulations are a powerful approach for examining the atomic-scale behavior of metal interfaces. I studied the structure, thermodynamics, and kinetics of coherent and semicoherent Titanium 𝛼/𝛽 interfaces using molecular dynamics (MD) simulations, thermodynamic integration, and DFT-trained Deep Potential. The structure of an equilibrium semicoherent interface consists of an array of steps, misfit dislocations, and coherent terraces. MD simulations reveal the detailed interface morphology dictated by intersecting disconnection arrays. Asymmetric mobility was observed during interface migration, which analysis shows is a characteristic of the heterophase interface caused by the different elastic constants of the two phases. The interface migration occurs through the nucleation and glide of interface disconnections and movement of interface dislocations. For heterophase interfaces, predicting the energy of disconnections is relatively difficult, but for grain boundary disconnections, a simple formula can describe the disconnection energy. Extensive calculations using Al grain boundaries verified the accuracy of this formula and determined the energy barrier of disconnections during the glide process. Furthermore, analyzing these energy barriers revealed that disconnection motion can be categorized into two types: those requiring atomic movement along the disconnection line and those that do not. For the latter, the energy barrier is proportional to the area traversed.

This research provides a comprehensive understanding of the structure, thermodynamics, and kinetics of metal interfaces, particularly in Titanium 𝛼/𝛽 systems. The findings contribute valuable insights into interface behavior, which can inform future studies and applications in materials science.