Research progress in interfacial microstructure，defect evolution and deformation mechanisms of Al/steel dissimilar materials based on synchrotron radiation in-situ characterization

Revealing the evolution and deformation mechanisms of interfacial microstructures and defects plays a crucial role in regulating the interfacial microstructures and properties of Al/steel dissimilar joints. However，conventional characterization methods are often inadequate for effectively elucidating the dynamic evolution mechanisms at the interface. This paper reviews the breakthrough progress of synchrotron radiation in-situ characterization techniques in elucidating the interfacial metallurgical reactions and strengthening-toughening mechanisms of Al/steel joints. By utilizing synchrotron radiation X-ray two-dimensional imaging，micro-tomography，and diffraction techniques，in-situ observations are achieved for the heterogeneous dissolution of steel，interfacial diffusion reactions，solidification behavior during Al/steel-liquid/solid interfacial reactions，as well as the deformation behavior of joints under load. These studies have provided deep insights into the growth kinetics and three-dimensional morphological evolution mechanisms of tongue-shaped Fe2Al5，irregular FeAl3，and faceted Si phases at Al/steel interfaces. Furthermore，the geometric morphology and spatial distribution characteristics of pores are remodelled，the evolution of residual stress distribution in components is characterized in-situ，and the mechanisms of crack initiation and propagation in heterogeneous components under loading conditions are clarified. Synchrotron radiation techniques overcome the limitations of traditional two-dimensional static characterization，providing dynamic experimental data for understanding the dissolution-diffusion-solidification processes and damage behavior under load at Al/steel interfaces. Future work should focus on in-situ studies of the metallurgical and mechanical behaviors at Al/steel interfaces under multi-field coupling or complex extreme conditions，as well as the development of intelligent in-situ characterization platforms.