Recent progress on in-situ characterization of laser additive manufacturing process by synchrotron radiation

Laser additive manufacturing (LAM) has been widely used in high-end manufacturing fields such as aerospace, nuclear power, and shipbuilding. However, it is a grand challenge for direct and continuous observation of complex laser-matter interaction, melt flow, and defect formation during LAM due to extremely large temperature gradient, fast cooling rate, and small time (millisecond) and space (micron) scales. The emergence of synchrotron radiation provides a feasible approach for in situ observation of the LAM process. This paper outlines the current development in real-time characterization of LAM by synchrotron radiation, including laser-matter interaction, molten pool evolution, solidification structure evolution, and defects formation and elimination. Furthermore, the future development direction and application-oriented research are also discussed.