Review:cross-scale in-situ characterization techniques for dynamic evolution of microstructures in materials under multi-field coupling

In-situ characterization techniques fundamentally break through the static limitation of traditional ex-situ methods, which only capture the initial and final state data of materials, by real-time tracking of the dynamic evolution of microstructures under multi-field coupling environments. This article systematically reviews five major in-situ technique families, including in-situ X-ray diffraction (XRD)/synchrotron radiation and computed tomography (CT), digital image correlation (DIC), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). It elucidates the measurement principles, complementary advantages, and applicable boundaries of these techniques from the lattice/atomic scale to the engineering component level. The review highlights typical applications of these techniques in addressing key scientific problems such as load partitioning in multiphase alloys, three-dimensional evolution of damage, phase transformation kinetics, and fatigue fracture. Furthermore, it deeply analyzes four core challenges currently faced: the inherent trade-off between spatial and temporal resolution, difficulties in reproducing extreme service environments, the pressure of processing massive multimodal data, and the non-uniqueness dilemma in the inversion of microscopic model parameters. This work aims to provide a critical fundamental theoretical foundation for establishing the dynamic “processing–structure–property” relationship of materials.