Interfacial engineering of superlattice coatings: Structural modulation, mechanical properties, and adaptation to...

Superlattice coatings consist of alternating nanoscale layers of metals, ceramics, or intermetallics. They have emerged as promising protective materials for extreme environments in advanced manufacturing, aerospace, and nuclear systems. Their periodic architectures offer synergistic enhancements in hardness, toughness, and thermal stability, surpassing conventional monolithic coatings. At the core of these properties lies interface engineering, which governs interlayer bonding, stress distribution, microstructural evolution, and high-temperature degradation. This review critically examines interface-dominated mechanisms underlying structural formation, growth dynamics, mechanical behavior, and environmental stability. Emphasis is placed on interfacial parameters such as lattice mismatch, interfacial energy, and atomic diffusion. These parameters play key roles in texture development, phase boundary design, and oxidation resistance. Despite recent advances, several challenges persist, including incomplete structure-property correlations, the lack of unified models linking processing to interface architecture, and limited integration with emerging functionalities. Future efforts should prioritize multiscale design platforms combining advanced characterization, modeling, and data-driven strategies to achieve precise interface control and multifunctionality in next-generation coatings.