Atomic unveiling of segregation-induced grain boundary structural transition in intermetallic compound

Grain boundary (GB) structural transition extensively exists in various materials and has significant influences on material properties. However, the atomic investigation of GB structural transition and how this transition acts on
GB properties such as stability and migration remain elusive. In this study, we have atomically observed the structural transition between low-angle and high-angle GBs in Ni3Al intermetallic after thermomechanical
processes. Based on spectrum and structural analyses, we discover that solute elements tend to segregate at dislocations in low-angle GBs rather than structural units in high-angle GBs. The element segregation plays a
crucial role in stabilizing GBs owing to the atom size effect and electron configuration. Through correlated electron microscopy observations, we directly demonstrate that the transition from dislocation arrays to structural
units changes GB properties including stability and migration. This study enhances our understanding of the effect of element segregation on GB structures and stabilities, offering new insights for performance optimization
by customizing GB on demand.