Evading the strength-ductility trade-off dilemma in steel-nickel heterostructured material by bionic crossed-lamellar structures

Despite the limitations imposed by their composition, natural materials overcome the trade-off between strength and ductility through their unique structural features. Inspired by the crossed-lamellar structure of conch shells, SS316L-IN625 heterostructured materials were designed and fabricated by laser directed energy deposition (LDED). Interestingly, this bionic heterostructured material (BHM) breaks the strength-ductility trade-off of the constitutive material with a tensile strength of 731.74 MPa and a uniform elongation of 34.98%. This particular with multi-scale and periodic distributions and interfaces with crossed-lamellar deliver the BHM superior performance combinations beyond the rules of mixtures. The strain gradient induced by heterogeneous deformation activates additional slip systems, and this unique slip band delays premature necking in the SS316L region and hinders crack propagation. The BHM takes full advantage of the intrinsic strength of IN625 and the toughness of SS316L to stimulate multiple enhancement and toughening mechanisms.