Recent Progress of Synchrotron X-Ray Imaging and Diffraction on the Solidification and Deformation Behavior of Metallic Materials

Characterizing the microstructure and deformation mechanism associated with the performances and properties of metallic materials is of great importance in understanding the microstructure-property relationship. The past few decades have witnessed the rapid development of characterization techniques from optical microscopy to electron microscopy, although these conventional methods are generally limited to the sample surface because of the intrinsic opaque nature of metallic materials. Advanced synchrotron radiation (SR) facilities can produce X-rays with strong penetrability and high spatiotemporal resolution, and thereby enabling the non-destructive visualization of full-field structural information in three dimensions. Tremendous endeavors were devoted to the 3rd generation SR over the past three decades, in which X-ray beams have been focused down to 100 nm. In this paper, recent progresses on SR-related characterization technologies were reviewed, with particular emphases on the fundamentals of synchrotron X-ray imaging and synchrotron X-ray diffraction, as well as their applications in the in situ observations of material preparation (e.g., in situ dendrite growth during solidification) and service under extreme environment (e.g., in situ mechanics). Future innovations toward next-generation SR and newly emerging SR-based technologies such as dark-field X-ray microscopy and Bragg coherent X-ray diffraction imaging were also advocated.