Systematic Design of Metallic Functionally Graded Materials & Structures

As performance demands on metallic structures increase, multi-material solutions like compositionally graded alloys (CGAs) are essential for achieving localized performance objectives where a single alloy is insufficient. Metal additive manufacturing (AM) provides unique potential for producing complex CGA structures due to its spatial control over composition. To realize effective multi-material design, sophisticated methods are required to handle the intricate alloy processing landscape. This dissertation presents a framework to address this intricate landscape for systematic materials design of CGAs. First, this work presents a comprehensive materials information schema to connect alloy processing to the resultant structure and properties. At the core of this framework is the proposed Alloy Topology-Linked informAtion Schema (ATLAS), a graph-based schema for instantiating materials graph databases for systematic materials design of CGAs. Unlike previous approaches, ATLAS graphs not only enable the design of 'two-terminal' gradient paths between two terminal ('end point') alloys, but also complex 'multi-terminal' gradients between an arbitrary number of terminal alloys. Multi-terminal gradient design is achieved through a novel formulation of the CGA design problem as a minimum Steiner tree problem in graphs. Additionally, the use of several other graph algorithms is also proposed for efficient, targeted experimental assessment of the alloy processing state space. Furthermore, the Tree-based Material Adjacency Propagation (TreeMAP) algorithm is proposed to map multi-terminal CGAs into discretized 3D structures, linking material processing with spatial performance targets. This algorithm enables the connection of alloy processing states with properties and performance in corresponding discretized part geometries, fully enabling systematic materials design of CGAs for structure-driven performance constraints and objectives. Lastly, a proposed framework integrates ATLAS, multi-terminal gradient design, and TreeMAP, establishing a first-of-its-kind approach for systematic CGA design. This work concludes by demonstrating this systematic approach by designing a compositionally graded structure using real materials, starting with the terminal alloys, then the multi-terminal gradient to join them, and, ultimately, the compositionally graded structure itself. This demonstration shows the framework's ability to enable optimized, location-specific structural performance beyond traditional single-alloy structures. Overall, this integrated framework extends the materials design and metal AM state-of-the-art, expanding the capabilities of metallic materials for demanding engineering applications.