Laser powder bed fusion (LPBF) was adopted to manufacture AlSi10Mg, and two post-processing schedules, T4 (510 °C/2 h + water quench) and T6 (T4 + 180 °C/6 h), were applied to elucidate how Si precipitation size controls ductility. The as-built alloy consisted of an α-Al matrix with a grid-like eutectic Si network and achieved UTS > 480 MPa but exhibited build-direction-dependent tensile anisotropy. Heat treatment promoted Si precipitation from the supersaturated α-Al matrix and transformed the eutectic network via fragmentation, spheroidization, and Ostwald ripening, leading to pronounced softening and improved elongation. After T4, the yield strength and UTS decreased by >50%, while elongation increased from 10.9% to 22.27%; T6 provided a slight strength recovery accompanied by a marginal ductility reduction. Mechanistically, a high number density of fine Si precipitates enhances dislocation storage and delays damage accumulation, whereas coarse, non-shearable Si particles intensify local strain gradients, facilitate void nucleation at the matrix/particle interface, and accelerate fracture. Overall, tailoring Si precipitation/coarsening offers an effective route to improve ductility and mitigate anisotropy in LPBF AlSi10Mg.

Nickel-titanium (NiTi) alloys are attractive for functional and biomedical applications due to their shape memory effect, superelasticity, and favorable corrosion resistance and biocompatibility. In this work, the influence of strut size on the compressive response of laser-based powder bed fusion (PBF-LB/M) fabricated NiTi ortho-octahedral porous scaffolds was systematically investigated using combined experiments and finite element simulations. Four scaffold designs with identical unit-cell size (2 mm) but different strut sizes (280, 320, 360, and 400 μm) were fabricated, and their forming quality and deformation behaviors were examined. The as-built scaffolds exhibited high geometric fidelity to the CAD models and stable manufacturability across the investigated parameter range. Quasi-static compression tests revealed a typical three-stage response (linear-elastic regime, plateau/collapse regime, and densification), with both elastic modulus and compressive strength increasing markedly with strut size. Specifically, the modulus increased from 1.17 to 4.28 GPa and the compressive strength increased from 155 to 564 MPa as the strut size increased from 280 to 400 μm. A pronounced oscillatory plateau was observed for the 280 μm scaffolds, indicating progressive layer-by-layer collapse, whereas larger struts promoted a shear-band-dominated failure mode characterized by an approximately 45° fracture zone. Explicit quasi-static simulations reproduced the experimentally observed collapse sequence and demonstrated that stress preferentially concentrates at nodal junctions, with load transfer dominated by struts aligned with the loading direction. The agreement between experiments and simulations confirms the predictive capability of the proposed modeling framework and provides mechanistic insights into geometry-controlled failure. These findings establish a structure-property-failure relationship for PBF-LB/M-fabricated NiTi octahedral scaffolds and offer practical guidance for tailoring stiffness, strength, and collapse mode through strut-size design.