Alloy Design Strategies for Additive Manufacturing: A Comprehensive Review of Microstructure Control and Performance Enhancement

Additive manufacturing (AM) enables the direct fabrication of complex metallic components, but achieving optimal microstructures and mechanical properties remains challenging due to rapid solidification, steep thermal gradients, and cyclic reheating. This review summarizes AM-specific alloy design strategies focused on controlling solidification, refining grains, and mitigating defects such as porosity, cracking, and anisotropy. Case studies across titanium alloys, aluminum-based systems, steels, nickel superalloys, refractory metals, and high-entropy alloys highlight advances in composition tuning, segregation control, and in-situ alloying. Computational approaches—including CALPHAD (Calculation of Phase Diagrams) modeling, phase-field simulations, and machine learning—accelerate the discovery of chemistries optimized for printability and performance. Breakthroughs include improved high-temperature stability, enhanced strength–ductility combinations, and defect mitigation via tailored microstructures. Persistent challenges involve balancing manufacturability with extreme service requirements, improving feedstock recyclability, and reducing costs for industrial adoption. This review provides a framework for integrating composition and process optimization to enable next-generation AM alloys for aerospace, biomedical, energy, and advanced manufacturing applications. Keywords: Additive manufacturing, Alloy design, Microstructure control, Solidification, Grain refinement, Mechanical performance, Process optimization.