Exceptional Strengthening via Nanostructure Engineering in Additively Manufactured Aluminum Alloys

We report a novel strategy that leverages ceramic microparticles and the thermal cycles of laser powder-bed fusion to achieve ultradense solute nanoclusters in aluminum alloys, resulting in unprecedented tensile properties. Using TiB₂ microparticles as an example, we minimize the interfacial energy differences between various crystallographic combinations of aluminum and microparticles through computational design, enabling an equiaxed grain structure. Meanwhile, the thermal misfit between microparticles and matrix induces high-density dislocations. The back-and-forth motion of these dislocations, driven by internal cyclic stresses, spontaneously generates dense vacancies (3.1 × 10²³ m^-3) in the as-built alloy and facilitates the creation of metastable, ultradense solute clusters (1.7 × 10²⁵ m^-3) after direct aging. Hence, remarkable strengthening and strain hardening can be achieved, exhibiting far superior tensile properties compared with additively manufactured counterparts. This study underscores the ability of additive manufacturing to broadly tune alloy nanostructures through a composite strategy and create future high-performance structural materials.