In Situ Formation of Mechanically Interlocked Heterointerfaces with Ultrahigh Bonding Strength for Mg‐Based Multilayered Sheets

Tailoring heterointerfaces is crucial for developing novel laminated metal composites (LMCs) with synergistic multifunctional structural properties. This study pioneers a novel approach to fabricating Mg-Ta incompatible LMCs via crystal orientation regulation, achieving in situ formed serrated mechanically interlocked interfaces with exceptional bonding strength (80.5 MPa) through hot-rolling. It also exhibits exceptional tensile properties with an ultimate tensile strength of 340-395 MPa, a yield strength of 301-363 MPa, and an elongation of 5-10.2%. Systematic multiscale investigations combining molecular dynamics (MD) simulations and density functional theory (DFT) calculations reveal a hierarchical interfacial architecture comprising dual heterointerfaces zone (hexagonal close-packed/face center cubic Mg/Cu and face centered cubic/body-centered cubicCu/Ta), with strain-modulated micro-serrations (width: 1.6-5.5 µm; depth: 6-15 µm) morphology, along with atomic interdiffusion zones (1.1-3.1 µm). A quantifiable inverse correlation is identified between serration dimensions and interfacial strength, with reduced width and depth directly enhancing bond integrity. Furthermore, the heterointerface evolution mechanism is decoupled into three thermomechanical stages: 1) crystallographic orientation optimization via dissimilar atomic contact, 2) strain-driven micro-sawtooth generation through dislocation slip competition, and 3) geometric interlocking completion via interface self-assembly. This work establishes a universal paradigm for designing multifunctional structural materials through strain-engineered heterointerface manipulation, rather than just applying several specific deformations processes.