Enhanced strength-ductility synergy in directed energy deposition Ti alloy via interlayer laser cladding heterogeneous particles

Abstract

The inherent strength-ductility contradiction and pronounced mechanical anisotropy in directed energy deposition (DED) of metallic materials remain a significant scientific challenge. This study proposed a novel hybrid additive manufacturing strategy that decouples material deposition from microstructural refinement by integrating arc-DED with interlayer laser cladding of heterogeneous particles. Using Ti-6Al-4V and SiC as a model system, we demonstrated that this approach enables precise in-situ synthesis of nano-TiC/Ti₅Si₃. A critical finding was the existence of a well-defined threshold (∼1.4 wt% SiC) that triggers a dramatic columnar-to-equiaxed grains transition, refining the α-Ti grain length from 172.4 μm to 22.5 μm. The optimized composite exhibited an exceptional strength-ductility synergy, with an ultimate tensile strength of 1178.4 MPa (+5.1 %) and an elongation of 11.7 % (+44.4 %), while significantly reducing anisotropy from 15.9 % to 10.3 %. This work aimed to establish a versatile and cost-effective processing route that can be extended to other material systems, providing a clear pathway to fabricate large-scale, high-performance, and near-isotropic components via DED.