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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. 

Abstract Materials based on minimal surface geometries have shown superior strength and stiffness at low densities, which makes them promising continuous‐based material platforms for a variety of engineering applications. In this work, it is demonstrated how these mechanical properties can be complemented by dynamic functionalities resulting from robust topological guiding of elastic waves at interfaces that are incorporated into the considered material platforms. Starting from the definition of Schwarz P minimal surface, geometric parametrizations are introduced that break spatial symmetry by forming 1D dimerized and 2D hexagonal minimal surface‐based materials. Breaking of spatial symmetries produces topologically non‐trivial interfaces that support the localization of vibrational modes and the robust propagation of elastic waves along pre‐defined paths. These dynamic properties are predicted through numerical simulations and are illustrated by performing vibration and wave propagation experiments on additively manufactured samples. The introduction of symmetry‐breaking topological interfaces through parametrizations that modify the geometry of periodic minimal surfaces suggests a new strategy to supplement the load‐bearing properties of this class of materials with novel dynamic functionalities.