Hybrid manufacturing, combining laser powder bed fusion (PBF-LB/M) with conventionally manufactured high-strength aluminium substrates, is hindered by interfacial hot cracking and porosity that compromise interface integrity and mechanical performance. This study investigates two TiC nanoparticle delivery strategies to reduce defects and to improve the mechanical properties of the interface between AA2017 substrates and PBF-LB/M-deposited AlSi10Mg: (i) a TiC nanoparticle interlayer applied directly to the substrate and (ii) TiC nanoparticles blended with the AlSi10Mg feedstock. Quantitative defect analysis combined with EBSD, EDS, microhardness, and miniature shear testing was used to correlate particle distribution with microstructural evolution, defect formation, and mechanical performance. Under optimised processing conditions, the TiC interlayer reduced the total defective interface area by 87 %, with crack-related defects reduced by >91 %, while the blended approach achieved a total defect reduction of 77 % and ∼84 % crack reduction. The interlayer promoted localised interfacial grain refinement via increased nucleant particle density within the crack-prone interface region, resulting in superior defect suppression. Depositing TiC as an interlayer, rather than blending, also reduced particle agglomeration and sintering. Furthermore, the interlayer approach suppressed interface softening, increased interfacial shear strength with reduced variability, and shifted the fracture path away from the interface into the AlSi10Mg region. The results demonstrate that the effectiveness of TiC modification depends on the spatial distribution of particles, establishing localised interface engineering as a more effective strategy than homogeneous feedstock modification for improving the integrity and mechanical performance of hybrid multi-alloy PBF-LB/M interfaces.     «

Hybrid manufacturing, combining laser powder bed fusion (PBF-LB/M) with conventionally manufactured high-strength aluminium substrates, is hindered by interfacial hot cracking and porosity that compromise interface integrity and mechanical performance. This study investigates two TiC nanoparticle delivery strategies to reduce defects and to improve the mechanical properties of the interface between AA2017 substrates and PBF-LB/M-deposited AlSi10Mg: (i) a TiC nanoparticle interlayer applied direc...     »