Oxide films in Al–Li alloy diffusion bonding joints hinder atomic diffusion, reducing bond strength. A new electrodeposition process applies a nano-Cu coating, achieving a peak shear strength of 102.8 MPa at 1 μm and 520 °C. Cu atoms from the coating diffuse into the Al matrix, forming intermetallic compounds (IMCs) that enhance Al–Al mutual diffusion. However, thinner coatings (<0.5 μm) fail to prevent oxide film formation, while thicker ones (>4 μm) hinder Al diffusion due to continuous IMC structures. Low temperatures (<480 °C) result in coarse, non-diffusive IMCs, while high temperatures (>540 °C) promote IMC growth and increase void and crack risks. This study introduces a novel nano-coating concept for Al–Li alloy bonding, with practical engineering applications.
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