Highly controllable additive manufacturing of heterostructured nickel-based composites

Owing to hetero-deformation induced (HDI) strengthening and HDI work hardening, heterostructured materials with both “hard” and “soft” features have been proven to achieve strength–ductility synergy. Laser-directed energy deposition (LDED) has shown tremendous potential in the fabrication of heterostructured materials, but faces challenges in accurately placing the required structures or materials at specific times and locations. This study developed a novel Ti₂AlC (MAX phase)-modified Inconel 718 composite material (MAX/Inconel 718) with multiscale precipitation (γ’, carbides, Laves phase) characteristics during solidification, highly sensitive to changes in cooling rates, and exhibiting excellent controllability of strength. A method called multibeam diameter laser-directed energy deposition (MBD-LDED), which allows the dynamic adjustment of the beam diameter during the building process to alter the cooling rate during solidification, is proposed. This enabled the placement of MAX/Inconel 718 with different strengths at suitable positions within the part. Different combinations of beam diameters can form periodic distributions and spatial interlocking structures with alternating “soft” and “hard” features perpendicular and parallel to the building direction. Compared to commercial Inconel 718, MAX/Inconel 718 demonstrated excellent manufacturability, strength, and high-temperature oxidation resistance. This study provides new insights into the design and performance optimisation of heterostructures using homogeneous materials and offers guidance for the integrated manufacturing of heterostructured components in the context of comprehensive material–structure–performance design.