Metallurgical Aspects of Additively Manufactured Aluminum Alloys: A Review

The Additive Manufacturing (AM) of aluminum alloys, especially via laser powder bed fusion (LPBF), offers exceptional potential for producing lightweight, high-strength components with tailored geometries. However, the rapid solidification and repeated thermal cycling inherent to LPBF-based AM often result in undesirable features such as porosity, anisotropy, residual stress, and solidification cracks, especially in high-strength alloys such as the 2XXX, 6 XXX, and 7 XXX series. This review critically examines the metallurgical landscape of aluminum alloys processed via LPBF, beginning with a comparative overview of conventional series (2XXX-8 XXX) and highlighting their printability and processing limitations. It then explores the influence of processing parameters and alloying additions on grain refinement, including the role of inoculants like TiB2, LaB, and Al3(Sc,Zr) in promoting equiaxed microstructures. Among these, VED is a critical processing parameter with an optimized range (typically 50–150 J/mm3), enabling fine grain structures, high densification, and6 superior mechanical performance. Phase stability was evaluated in terms of precipitation behavior, transformation kinetics, and defect formation under LPBF-specific conditions. Post-processing techniques, such as T6 Heat Treatment (HT) and hot isostatic pressing (HIP), have been shown to significantly improve mechanical performance by mitigating microstructural heterogeneity and enhancing the strength–ductility balance. Finally, the review outlines emerging trends such as data-driven alloy design and nanoparticle-assisted solidification control. By correlating process–structure–property relationships and synthesizing insights across microstructure, mechanical behavior, and process design, this study outlines a strategic roadmap for optimizing AM (LPBF) aluminum alloys to enable reliable, high-performance applications at the industrial scale. Graphical Abstract