Interfacial Kagome lattice transitions induced by segregation of solute atoms

Interfacial structural transformations arising from solute segregation play a crucial role in the performance of materials. However, these micro-transitions are often difficult to reveal due to their buried nature. Here, in a typical Mg-rare-earth model system, we present the discovery of interfacial Kagome lattice transitions triggered by segregation of solutes coupled with bi-crystalline lattice interactions, in three types of partially coherent tilt grain boundaries (GBs), using atomic-resolution scanning transmission electron microscopy observations plus theoretical calculations. The results demonstrate that the minimization of GB elastic strain is responsible for the selective segregation of solutes at interfacial specific sites, resulting in a confined phase transition of the embedded triangular-quadrilateral ( 10 1 ¯ 1 ) _Mg lattice to a topological hexagonal-triangular Kagome lattice via atomic shuffling. Furthermore, the pressure-temperature conditions that trigger such interfacial Kagome lattice transitions have also been determined. These findings not only enrich the transition pathways formed by the Kagome lattice but also provide a bottom-up approach for investigating interfacial structural transformations induced by solute/impurity segregation in polycrystalline materials.