A mortise-and-tenon structure inspired high strength-ductility 3D printed high-entropy alloys with mechanically interlocked network

Designing special heterogeneous structures has been proven to be an effective strategy for breaking the trade-off between strength and ductility. In this work, we drew inspiration from the architectural integrity and mechanical ingenuity of the mortise-and-tenon joint, a hallmark of traditional craftsmanship, to engineer a novel mechanically interlocked network (MIN) within a 3D printed high-entropy alloy (HEA). The sub-grains crosslink not only mimics the joint in structure, but also reproduces its function in modifying the mechanical properties of the MIN. The MIN structure provides the excellent structural stability and disperses the stress concentration at the grain boundary during the deformation process, which thus avoids the fracture failure caused by the crack propagation. The alloy's remarkable performance, characterized by a tensile strength of approximately 1152 MPa and an elongation of 28%, is attributed to a symphony of underlying mechanisms, including hetero-deformation induced strengthening and hardening, dislocation tangling, stacking faults, and the formation of Lomer-Cottrell locks. These findings demonstrate the feasibility of introducing MIN heterogeneous structures to enhance the mechanical properties of HEA and promote the development of high-performance materials with manufacturing flexibility, enabling customization of their multi-scale microstructure using additive manufacturing techniques.