Fine-spot laser direct energy deposition of gradient thin-walled honeycomb structure and compression property analysis

Integrating gradient materials with honeycomb structures offers a promising solution for achieving both multi-functional and lightweight. However, conventional laser direct energy deposition (L-DED) with large spot sizes (2-5 mm) limits deposition precision, particularly for thin-walled components. To address these issues, this study employs fine-spot laser directed energy deposition (FL-DED) with a 0.8 mm spot diameter to fabricate Ti6Al4V/TiC gradient thin-walled honeycomb structures, systematically investigating the effects of laser spot size (0.8 mm vs 2.7 mm) and TiC content gradient (0%-20%) on microstructural evolution and compression properties. Results show that FL-DED significantly refines TiC particles: compared with deposition using a 2.7 mm spot, the sizes of granular and dendritic primary TiC decrease by 18.9% and 60.4%, respectively, with all TiC phases tightly bonded to the matrix without defects. The bamboo-inspired gradient structure achieves a 19.95% mass reduction compared with traditional honeycombs, with 2.5° inclined walls exhibiting optimal load-bearing capacity. During compression, honeycomb cells achieve coordinated deformation through interconnected walls; dendritic and unmelted TiC particles tend to induce localized stress concentrations, reducing ductility. This study provides a strategy for high-precision fabrication of gradient honeycomb structures, holding promise for offering solutions to lightweight, high-performance components in aerospace and other extreme environments.