METAL ADDITIVE MANUFACTURING (AM) IS REVOLUTIONIZING INDUSTRY. METAL AM ENABLES OPPORTUNITIES TO ENHANCE THE PERFORMANCE AND EFFICIENCY OF COMPONENTS BY CUSTOMIZING THEM TO RELEVANT USE CASES. TODAY, METAL AM IS USED TO BUILD PARTS THAT WERE PREVIOUSLY INACCESSIBLE IN INDUSTRY, BUT ITS IMPLEMENTATION IS LIMITED BY THE SIGNIFICANT VARIABILITY IN PERFORMANCE OF THE RESULTING COMPONENTS. UNLIKE CLASSICAL METALLURGICAL PROCESSES, METAL AM IMPOSES RAPIDLY EVOLVING HARSH ENVIRONMENTS THAT TRANSFORM AND DEGRADE MATERIALS IN WAYS THAT WE STRUGGLE TO PREDICT AND CONTROL. FUNDAMENTAL STUDIES OF THE DELETERIOUS DEFECTS THAT DEGRADE PERFORMANCE HAVE GIVEN KEY INSIGHTS AT THE MACROSCALE, BUT TO CONTROL PROPERTIES WE MUST EXTEND THIS TO THE MULTISCALE PICTURE. AT THE NANOSCALE, WE UNDERSTAND THAT HIERARCHICAL STRUCTURES OF DEFECTS ORIGINATE AT THE LATTICE LEVEL AND PACK INTO 3D HIERARCHICAL STRUCTURES THAT GOVERN STRENGTH, FAILURE, FATIGUE, ETC. OUR PROJECT WILL DEVELOP A NEW CLASS OF OPERANDO NANOSCOPIC X-RAY IMAGING METHODS TO DIRECTLY MAP THE ONSET OF DEFECTS IN METAL-AM – FOCUSING ON LASER POWDER BED FUSION (LPBF). BY BUILDING A SUITE OF TIME-RESOLVED 2D AND 3D X-RAY MICROSCOPES WITH ANALYSIS METHODS TO TRACK THE STATISTICAL BEHAVIORS WE RESOLVE, WE WILL BUILD A NEW EXPERIMENTAL “TOOLBOX” THAT CONNECTS DEFECTS TO THE COMPLEX MULTIPHASE DYNAMICS NATIVE TO LPBF.