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Microstructural control is both a major challenge and an opportunity in additive manufacturing of parts, and plays a particularly dominant role in the performance of components with complex geometries. Much effort has gone into metal additive manufacturing of metamaterials; yet a thorough understanding of microstructural controllability toward optimized part performance is lacking. Of interest is the development of functionally graded metamaterials, which locally optimize part properties to enhance overall part performance. 17‐4 precipitation hardened (PH) stainless steel has previously been shown to exhibit phase control as a function of printing parameters; yet the influence of geometry on phase evolution in printing of complex structures and metamaterials has so far remained unexplored. The present study aimed at elucidating the relationship between phase evolution and geometry in gyroid shell metamaterials printed in 17‐4 PH steel via laser powder bed fusion. Local hardening is demonstrated to occur as a function of geometry, likely prompted by topology‐induced variations in cooling profiles. The associated phase evolution is governed by the gyroid geometry and strongly correlates with geometry‐dependent loading paths therein. This demonstrates the possibility of inducing functional grading through geometric complexity, highlighting the possibility of significant property enhancements through local microstructural control. 

Electron backscatter diffraction (EBSD) is a powerful tool for determining the orientations of near-surface grains in engineering materials. However, many ceramics present challenges for routine EBSD data collection and indexing due to small grain sizes, high crack densities, beam and charge sensitivities, low crystal symmetries, and pseudo-symmetric pattern variants. Micro-cracked monoclinic hafnia, tetragonal hafnon, and hafnia/hafnon composites exhibit all such features, and are used in the present work to show the efficacy of a novel workflow based on a direct detecting EBSD sensor and a state-of-the-art pattern indexing approach. At 5 and 10 keV primary beam energies (where beam-induced damage and surface charge accumulation are minimal), the direct electron detector produces superior diffraction patterns with 10x lower doses compared to a phosphor-coupled indirect detector. Further, pseudo-symmetric variant-related indexing errors from a Hough-based approach (which account for at least 4%-14% of map areas) are easily resolved by dictionary indexing. In short, the workflow unlocks fundamentally new opportunities to characterize materials historically unsuited for EBSD. 

At the intersection of the outwardly disparate fields of nanoparticle science and three-dimensional printing lies the promise of revolutionary new “nanocomposite” materials. Emergent phenomena deriving from the nanoscale constituents pave the way for a new class of transformative materials with encoded functionality amplified by new couplings between electrical, optical, transport, and mechanical properties. We provide an overview of key scientific advances that empower the development of such materials: nanoparticle synthesis and assembly, multiscale assembly and patterning, and mechanical characterization to assess stability. The focus is on recent illustrations of approaches that bridge these fields, facilitate the design of ordered nanocomposites, and offer clear pathways to device integration. We conclude by highlighting the remaining scientific challenges, including the critical need for assembly-compatible particle–fluid systems that ultimately yield mechanically robust materials. The role of domain boundaries and/or defects emerges as an important open question to address, with recent advances in fabrication setting the stage for future work in this area.