K.A. Unocic
NC State University, North Carolina, United States
Keywords: In Situ Laser Processing, Laser Powder Bed Fusion (LPBF), Process–Microstructure Relationships, Electron Microscopy, Advanced Manufacturing
The rapid qualification of advanced structural alloys remains a major challenge for additive manufacturing because current process development relies on costly iterative powder production and full-scale builds. We have developed an operando laser microscopy platform that combines in situ scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and multi-scale simulations to directly observe melting, solidification, phase transformations, and microstructural evolution during laser processing with nanometer-scale spatial resolution. Initial studies on Fe-Cr-Ni alloys establish correlations between laser processing parameters, melt pool evolution, defect formation, and non-equilibrium phase transformations. The platform is being extended to nickel-based superalloys (IN718) and high-entropy alloys to investigate alloy-specific solidification behavior, microstructural stability, and processing pathways relevant to laser powder bed fusion. Experimental observations are integrated with physics-based simulations to improve predictive models of laser-material interactions in representative alloy geometries, including thin films and powder particles. This operando framework uniquely bridges atomic-, nano-, and microscale observations with predictive simulations, enabling validation of digital manufacturing models, rapid screening of new alloy chemistries before expensive powder production, and accelerated qualification of advanced structural materials for aerospace, defense, and energy applications.