Multi-material laser powder bed fusion of Ti64/AlSi10Mg composites with bionic finger-inserted interface

Inspired by the interdigitated microstructures found in natural biological systems, this study explores the design and additive manufacturing of three-dimensional, multi-material Ti64/AlSi10Mg architectures with enhanced mechanical properties. Utilizing a multi-material laser powder bed fusion (LPBF) technique, we successfully fabricated bionic finger-inserted interface(FII) structures with high dimensional precision and fine feature resolution. The results not only demonstrate that the mechanical performance of these structures is highly dependent on the degree of material overlap, but also show that a significant enhancement in tensile strength was achieved, with the ultimate tensile strength (UTS) increasing by 156% (from 99 MPa to 254 MPa) as the architecture evolved from a single-layer to a five-layer interdigitated design. They also reveal, however, that the elongation of the composite structure is still relatively low (<1%). Microstructural characterization (XRD, EDS, EBSD) revealed interdiffusion and the formation of intermetallic compounds at the interface. The typical α/α' martensitic microstructure of LPBF-processed Ti64 was transformed into a more equiaxed-like morphology with a increased β-phase fraction. This microstructural evolution, combined with dispersion strengthening effects, led to a remarkable increase in microhardness, exceeding 500 HV. Despite achieving sound metallurgical bonding and geometric fidelity, the presence of micro-cracks highlights ongoing challenges associated with residual stress and material incompatibility. This work validates the feasibility of manufacturing high-performance, bio-inspired multi-material systems via LPBF and underscores the critical role of architectural design in tailoring mechanical properties, providing valuable insights for future applications in demanding multi-functional components.