Additive Manufacturing of Graded TPMS and Voronoi Lattices in AlSi10Mg: From Design to Mechanical Characterization

Laser Powder Bed Fusion (LPBF), a type of additive manufacturing (AM), allows for the production of metallic lattice structures with highly adaptable geometries and graded material properties. Functionally Graded Lattice Structures (FGLSs) are advantageous for high-performance applications, including biomedical implants. These advanced structures, produced through additive manufacturing, exhibit spatially varying mechanical properties that are crucial for mimicking biological gradients, thereby reducing stress shielding and promoting better integration.

This research explores the design, fabrication, and mechanical characterization of FGLS using AlSi10Mg. Three advanced lattice topologies were investigated: Gyroid, Split-P (a TPMS-derived surface), and Stochastic Voronoi (ST). Tensile and compression specimens were fabricated via LPBF, with functional gradation introduced by varying strut and wall thickness along the specimen length. The mechanical properties, including elastic modulus, ultimate tensile and compressive strength, and energy absorption, were evaluated through quasi-static tensile and compression tests. High-resolution computed tomography (CT) scans were used to capture the as-built geometry, verify dimensional accuracy, and identify potential manufacturing defects. These images were further analyzed to assess internal fidelity, strut thickness deviations, and porosity, supporting the mechanical testing with geometric validation. Moreover, scanning electron microscopy (SEM) analysis was carried out on the fracture surfaces of the broken specimens to better understand the behaviour of the material.

Considering compressive properties, in every case, at any density, cylindrical cell maps outperform cubic ones. In compression samples, switching from cylindrical to cubic in Split-P cuts energy absorption by only 10%, but in Gyroid it drops 24%. Considering tensile specimens, in ST and Split-P lattices, stiffness scales nearly one to one with relative volume. However, in gyroid lattices, lowering the thickest walls stiffens the structure while thinning the smallest walls softens it. AM defects resulting in sudden fracture under localized high stress and brittle behaviour, even in ductile alloys like AlSi10Mg.