Topology-alloy interactions governing deformation and failure in LPBF-fabricated A286 and Inconel 718 lattice structures.

This study presents a comprehensive multiscale comparison of LPBF-fabricated A286 and IN718 lattice structures across three architected topologies (BCC/BCCz, Gyroid/Hexstar and Honeycomb) to elucidate how alloy microstructure and geometry jointly control deformation and failure mechanisms. Quasi-static compression tests revealed a consistent topology-dependent strength hierarchy, with Honeycomb achieving the highest peak stresses (A286: 3.3 GPa; IN718: 2.89 GPa), followed by BCC/BCCz and Gyroid/Hexstar designs. A286 exhibited higher initial stiffness (9.3-11.2 GPa) but experienced early instability due to particle detachment and oxide-assisted cracking, whereas IN718 demonstrated smoother strain hardening and superior energy absorption, with W₆₀ values of 1.71-2.04 MJ/m³ compared to 1.32-1.85 MJ/m³ for A286. XRD analysis showed more compressive residual stresses in A286 (to - 585 MPa) than IN718 (to - 504 MPa), alongside higher microstrain (ε ≈ 5.6 × 10⁻³) and smaller crystallite size (27 nm vs. 43 nm), indicating greater lattice distortion in A286. FTIR spectra revealed stronger carbide- and oxide-related bands in A286, while IN718 displayed predominantly O-H and CO₂ signatures consistent with ductile surface formation. FESEM and EDS analyses confirmed fundamentally different failure pathways: A286 failed via particle pull-out, sinter-neck rupture and oxide-decorated cracking, whereas IN718 deformed through slip-dominated smearing, laminated tearing and blunted microcracks. Collectively, the results establish that topology governs global deformation, while alloy chemistry dictates whether collapse proceeds through brittle-assisted rupture (A286) or ductile, slip-mediated flow (IN718). This framework provides design guidelines for tailoring alloy-topology combinations for lightweight, impact-resistant applications.