Improved mechanical properties of laminate heterostructed 1060/7075/1060 alloys by interface diffusion

A laminate heterostructured 1060/7075/1060 alloy with a soft/hard/soft architecture was fabricated via diffusion bonding (DB). Post-DB heat treatment was found to be crucial for activating interfacial interdiffusion of Zn and Mg, which fundamentally tailored the interfacial microstructure and enhanced mechanical compatibility. The laminate heat-treated at 500 °C achieved an outstanding synergy of strength and ductility, with a yield strength of ~102 MPa, an ultimate tensile strength of ~223 MPa, and an elongation of 21.7%. This enhancement is attributed to the formation of a graded hardness profile and fine MgZn₂ precipitates across the interface, which mitigated mechanical incompatibility. Cyclic loading-unloading-reloading tests and microstructural characterization confirmed that the superior properties originate from significant hetero-deformation induced (HDI) stress strengthening, driven by the accumulation of geometrically necessary dislocations (GNDs) at the hetero-interface.