Research on the gradient passivation-stress coupling in Ti/HEA multilayer via hierarchical density at amorphous-nanocrystalline heterointerfaces

Based on magnetron sputtering technology, this study precisely controlled the hierarchical density of the Ti/HEA heterointerface at the atomic scale and successfully fabricated amorphous-nanocrystalline periodic composite films. It deeply revealed the microstructure evolution law induced by multi-level interfaces, the distribution of gradient stress fields caused by lattice mismatch during periodic deposition, and the preferred orientation growth mode of the nanocrystalline phase. The amorphous phase served as a corrosion passivation source, spontaneously forming a dense gradient oxide film under medium erosion, effectively blocking the penetration of chloride ions; the nanocrystalline phase acted as a mechanical load-bearing source, suppressing the nucleation and propagation of microcracks through interface pinning. After optimization, the corrosion potential increased by 38.01%, and the corrosion current density significantly decreased by 88.25%. It also proposed a double-threshold effect of heterointerface density, suggesting that a moderate interface density can balance the growth kinetics of the passivation film and the stability of interlayer stress, while excessive accumulation will cause stress channels and lead to corrosion failure. This study achieves long-term protection of thin films in corrosive environments by optimizing the interlayer distribution and interface stress field of amorphous/nanocrystalline layers and establishing an integrated design of “gradient passivation-structural buffering”.